Semiconductor device

Abstract

To provide a semiconductor device capable of changing a storage area in each hierarchy of a storage device.SOLUTION: In a semiconductor device including a storage device having first and second memory circuits and a control circuit, the first memory circuit includes a first capacitive element and a first transistor having a function of retaining charge held in the first capacitive element and the second memory circuit includes a second transistor, a second capacitive element electrically connected to the gate of the second transistor, and a third transistor having a function of retaining charge held in the second capacitive element. The first and third transistors include a semiconductor layer having an oxide semiconductor, a gate, and a back gate. By adjusting a voltage applied to the first or third transistor back gate, the respective storage area of the first or second storage circuit is changed.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] One embodiment of the present invention relates to a semiconductor device.

[0002] Note that one embodiment of the present invention is not limited to the above technical fields. The technical field of one aspect of the present invention relates to an object, a method, or a manufacturing method. One aspect of the present invention is a process, machine, manufacture, or composition of matter. Another embodiment of the present invention relates to a semiconductor device, a display device, device, light emitting device, power storage device, storage device, driving method thereof, or manufacturing method thereof do. [Background technology]

[0003] A wide variety of configurations have been proposed for computer systems that process information, depending on their applications. However, in many computer systems, memory units are divided into multiple hierarchies. In this case, an architecture is adopted in which storage devices with different performance are assigned to each layer. In such a computer system, registers, cache memory, main memory, auxiliary Structures including storage devices, such as memory devices, are widely known.

[0004] Patent Document 1 describes a memory circuit using a transistor including an oxide semiconductor in a semiconductor layer. The invention discloses an application of oxide semiconductors to memory chips, cache memories, and main storage devices. It has a wider band gap than silicon and a smaller intrinsic carrier concentration, making it an oxide semiconductor. A transistor that includes a conductor in a semiconductor layer has the characteristic of having an extremely small off-state current. By using the transistor in a memory circuit, stored data can be retained for a long time. It is possible. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2015-180994 A Summary of the Invention [Problem to be solved by the invention]

[0006] The required performance of each memory device, such as registers, cache memory, and main memory, is Therefore, it is difficult to share the memory area between them. When the storage capacity of the cache memory becomes insufficient, the main memory makes up for the shortage. It is difficult to make up for this.

[0007] An object of one embodiment of the present invention is to provide a novel semiconductor device. Another object of the present invention is to provide a semiconductor device capable of reducing power consumption. Another object of the present invention is to provide a semiconductor device whose area can be reduced. One of the objects of the present invention is to provide a semiconductor device that can increase the capacity of a memory device.

[0008] Note that one embodiment of the present invention does not necessarily have to solve all of the above problems, but It is sufficient if the invention can solve at least one of the problems. In addition, the description of the problem above may be changed without prior notice. Problems other than these cannot be identified from the description in the specification, drawings, claims, etc. It is obvious that there are other problems than these from the description, drawings, claims, etc. It is possible to extract [Means for solving the problem]

[0009] (1) One aspect of the present invention is a memory device and a control circuit, the memory device operating in a first memory hierarchy. and a second memory circuit operating in a second memory hierarchy, the first memory hierarchy comprising: A hierarchical level having a faster access speed than the second memory hierarchical level, the first memory circuit includes a first capacitive element and a first transistor having a function of holding a charge held in the first capacitance element, The second memory circuit includes a second transistor and a gate of the second transistor. a second capacitance element; and a third transistor having a function of retaining the charge retained in the second capacitance element. the first and third transistors each include a semiconductor layer having an oxide semiconductor and a first a control circuit for applying a voltage to the second gate of the first transistor; A function of changing the first memory circuit from the first memory hierarchy to the second memory hierarchy by inputting By inputting a voltage to the second gate of the third transistor, the second memory circuit is and a function of changing the memory hierarchy from the first memory hierarchy to the second memory hierarchy.

[0010] (2) In addition, in one aspect of the present invention, in the configuration (1), the control circuit has a temperature detection circuit. The temperature detection circuit has a function of outputting a correction voltage according to the temperature around the storage device. The control circuit adjusts the voltage applied to the second gate of each of the first and third transistors by a correction voltage. It is a semiconductor device having a function of varying the voltage depending on the pressure.

[0011] (3) Another embodiment of the present invention is a memory device including a first memory layer and a control circuit. A first memory circuit operates in a first memory hierarchy and a second memory circuit operates in a second memory hierarchy. The tier is a tier having a faster access speed than the second storage tier, and the first storage circuit is a first capacitance a first transistor having a function of holding a charge held in the first capacitance element; the second memory circuit is electrically connected to a second transistor and a gate of the second transistor; a second capacitance element connected to the second capacitance element and a third transistor having a function of holding the charge held in the second capacitance element; a first transistor and a third transistor, the first transistor and the third transistor being formed of a semiconductor layer having an oxide semiconductor a first gate and a second gate, and the control circuit controls the second gate of the first transistor to By inputting a voltage, the first memory circuit is changed from the first memory hierarchy to the second memory hierarchy. and inputting a voltage to the second gate of the third transistor to generate a second memory circuit. from the second storage hierarchy to the first storage hierarchy, and the control circuit is a controller a plurality of voltage generating circuits and a switching circuit, and the storage device is and a function of outputting a signal indicating the usage status of the storage capacity of the storage device, and the controller In response to the signal, a voltage output from one of the plurality of voltage generating circuits is selected from the first and third The switching circuit has a function of controlling the switching circuit so that a second gate of the transistor , a semiconductor device.

[0012] (4) In addition, in one aspect of the present invention, in the configuration (3) above, the control circuit has a temperature detection circuit. The temperature detection circuit has a function of outputting a correction voltage according to the temperature around the storage device. The control circuit adjusts the voltage applied to the second gate of each of the first and third transistors by a correction voltage. It is a semiconductor device having a function of varying the voltage depending on the pressure.

[0013] (5) Another embodiment of the present invention is a memory device including a first memory layer and a control circuit. A first memory circuit operates in a first memory hierarchy and a second memory circuit operates in a second memory hierarchy. The tier is a tier having a faster access speed than the second storage tier, and the first storage circuit is a first capacitance a first transistor having a function of holding a charge held in the first capacitance element; the second memory circuit is electrically connected to a second transistor and a gate of the second transistor; a second capacitance element connected to the second capacitance element and a third transistor having a function of holding the charge held in the second capacitance element; a first transistor and a third transistor, the first transistor and the third transistor being formed of a semiconductor layer having an oxide semiconductor a first gate and a second gate, and the control circuit controls the second gate of the first transistor to By inputting a voltage, the first memory circuit is changed from the first memory hierarchy to the second memory hierarchy. and inputting a voltage to the second gate of the third transistor to generate a second memory circuit. from the second storage hierarchy to the first storage hierarchy, and the control circuit is a controller a plurality of voltage generating circuits and a switching circuit, and the storage device is and a function of outputting a signal indicating the usage status of the storage capacity of the storage device, and the controller In response to the signal, a voltage output from one of the plurality of voltage generating circuits is selected from the first and third a switching circuit for controlling the switching circuit to apply a voltage to the second gate of the transistor; The first memory circuit is a semiconductor device having a region overlapping with the second memory circuit.

[0014] (6) In addition, in one aspect of the present invention, in the configuration (5) above, the control circuit has a temperature detection circuit. The temperature detection circuit has a function of outputting a correction voltage according to the temperature around the storage device. The control circuit adjusts the voltage applied to the second gate of each of the first and third transistors by a correction voltage. It is a semiconductor device having a function of varying the voltage depending on the pressure.

[0015] (7) In addition, one embodiment of the present invention is a method for manufacturing a semiconductor device comprising the steps of: Semiconductors are indium, element M (element M is aluminum, gallium, yttrium, or The semiconductor device has one or more materials selected from the group consisting of tin, zinc, and the like.

[0016] In this specification, a semiconductor device is a device that utilizes semiconductor characteristics. A circuit including a semiconductor element (transistor, diode, photodiode, etc.) It also refers to any device that can function by utilizing the properties of semiconductors. For example, Integrated circuits, chips with integrated circuits, and electronic components that house chips in a package are called semiconductors. In addition, a storage device, a display device, a light-emitting device, a lighting device, an electronic device, etc. It may itself be a semiconductor device or may include a semiconductor device.

[0017] In addition, in the present specification and the like, when it is described that X and Y are connected, X and When X and Y are electrically connected, when X and Y are functionally connected, and when X and The case where Y is directly connected is also considered to be disclosed in the present specification. In addition, the present invention is not limited to a specific connection relationship, for example, a connection relationship shown in a drawing or text, and may be modified without departing from the spirit or scope of the present invention. Connections other than those shown in the figure or text are also considered to be disclosed. X and Y are Assume that the object is an object (e.g., a device, an element, a circuit, a wiring, an electrode, a terminal, a conductive film, a layer, etc.) .

[0018] An example of the case where X and Y are electrically connected is The elements that function as One or more diodes, display elements, light-emitting elements, loads, etc.) are connected between X and Y. The switch has a function of being controlled to be on and off. A switch can be in a conductive state (on) or a non-conductive state (off) and can either pass current or It has a function to control whether or not water is flushed.

[0019] An example of a case where X and Y are functionally connected is the case where the functional connection between X and Y is possible. Circuits that perform the functions of the following: logic circuits (inverters, NAND circuits, NOR circuits, etc.), signal Conversion circuits (DA conversion circuits, AD conversion circuits, gamma correction circuits, etc.), potential level conversion circuits ( Power supply circuits (boosting circuits, step-down circuits, etc.), level shifter circuits that change the potential level of signals, etc. ), voltage sources, current sources, switching circuits, amplifier circuits (which can increase the signal amplitude or current amount, etc.) circuits, operational amplifiers, differential amplifier circuits, source follower circuits, buffer circuits, etc.), signal generation One or more devices (such as a memory circuit, a control circuit, etc.) can be connected between X and Y. For example, even if another circuit is inserted between X and Y, the signal output from X X and Y are said to be functionally connected if

[0020] In addition, when it is explicitly stated that X and Y are electrically connected, it means that X and Y are electrically connected. When X and Y are electrically connected (i.e., when another element or circuit is placed between X and Y) X and Y are functionally connected (i.e., there is no connection between X and Y) When X and Y are connected directly, the two are functionally connected via another circuit. (That is, when X and Y are connected without any other element or circuit between them) In other words, when it is explicitly stated that something is electrically connected, it should simply be "connected" to the "other" section.

[0021] Also, for example, "X and Y and the source (or first terminal, etc.) and drain ( or the second terminal, etc.) are electrically connected to each other, and X, the source of the transistor (or first terminal, etc.), the drain (or second terminal, etc.) of the transistor, and Y. "The source ( or the first terminal, etc.) is electrically connected to X, and the drain (or the second terminal, etc.) is electrically connected to Y, and X, the source (or first terminal, etc.) of the transistor. , the drain (or second terminal, etc.) of the transistor, Y, are electrically connected in this order. Alternatively, "X is the source (or first terminal) of the transistor." The Y is electrically connected to the X through the drain (or second terminal, etc.) and the The source (or first terminal, etc.) of a transistor, the drain (or second terminal, etc.) of a transistor (e.g., Y is provided in this connection order). By using a similar expression method to specify the order of connections in a circuit configuration, The source (or first terminal, etc.) and the drain (or second terminal, etc.) of the transistor are The technical scope can be determined by distinguishing between the above. Note that these methods of expression are merely examples. , but is not limited to these representation methods. Here, X, Y, Z1, and Z2 are the object (e.g., device, element, circuit, wiring, electrode, terminal, conductive film, layer, etc.).

[0022] In addition, the circuit diagram shows that independent components are electrically connected to each other. Even if one component has the functions of multiple components, For example, when a part of the wiring also functions as an electrode, one conductive film functions as the wiring and The function of both components is combined with the function of the electrode. Electrical connection means that one conductive film has the functions of multiple components. cases are also included in this category.

[0023] In this specification, a transistor is referred to as a gate, a source, and a drain. The gate is a control terminal that controls the conductive state of the transistor. The two terminals that function as the source and drain are the input and output terminals of the transistor. The two input / output terminals are selected based on the transistor conductivity type (n-channel type, p-channel type) and the transistor Depending on the potential applied to the three terminals of the transistor, one becomes the source and the other becomes the drain. Therefore, in this specification and the like, the terms source and drain can be interchanged. In addition, in this specification and the like, when describing the connection relationship of a transistor, "One of the source or drain" (or the first electrode, or the first terminal), "the source or drain The term "second electrode" or "second terminal" is used. Some devices have a back gate in addition to the three terminals described above.

[0024] In this specification, a node may be a terminal, a wiring, or the like depending on a circuit configuration, a device structure, or the like. It can be called a line, an electrode, a conductive layer, a conductor, an impurity region, etc. The wiring etc. can be called a node in other words.

[0025] In addition, in this specification, the terms "voltage" and "electric potential" can be interchanged as appropriate. "Voltage" refers to the potential difference from a reference potential. For example, If we define "voltage" as "ground potential," then "potential" can be used instead of "ground potential." The potential does not necessarily mean 0V. Note that the potential is relative and the reference Depending on the potential, the potential applied to the wiring etc. may be changed.

[0026] Generally, "electric current" is defined as the transfer of electric charge (electrical conduction) that accompanies the movement of positively charged bodies. However, the statement that "electrical conduction of positive charges is occurring" does not necessarily mean "the opposite In other words, "electrical conduction of negative charges occurs in the ion exchange region." In this document, unless otherwise specified, "current" refers to the phenomenon of charge transfer accompanying the movement of carriers (electric current). The carriers referred to here are electrons, holes, anions, and cations. , complex ions, etc., and in systems where current flows (e.g., semiconductors, metals, electrolytes, vacuum, etc.) The carriers differ depending on the type of material. Also, the "direction of current" in wiring, etc. is positive. The direction in which negative carriers move is expressed as a positive current amount. In other words, the direction in which negative carriers move is , the direction of the current is opposite to that of the current flow, and is expressed as a negative current amount. If there is no mention of the positive or negative current (or the direction of the current), it means that "current flows from element A to element B." A statement such as "current flows from element B to element A" can be rephrased as "current flows from element B to element A" In addition, statements such as "current is input to element A" should be interpreted as "current is output from element A." This can be rephrased as "can be used for the purpose of the purpose" etc.

[0027] In addition, in this specification, the ordinal numbers "first," "second," and "third" refer to components. Therefore, the number of components is not limited. In addition, the order of the components is not limited. The components referred to as "first" in the above may be included in other embodiments or in the claims. In addition, for example, the second component may be referred to as a "second" component in the present specification. A component referred to as "first" in one embodiment may be used in other embodiments or in particular It may be omitted within the scope of the claims.

[0028] In addition, in this specification, the terms "above" and "below" that indicate an arrangement are used to refer to the relationship between components. The positional relationship may be used for convenience in explaining the drawings. The relative positions of the elements change depending on the direction in which each element is depicted. The term is not limited to the words and phrases explained in the notes, etc., and can be rephrased appropriately according to the situation. For example, For example, in the expression "insulator on top of conductor," the orientation of the drawing shown is rotated 180 degrees. By rotating it, it can be rephrased as "insulator located on the underside of a conductor."

[0029] In addition, the terms "above" and "below" refer to the positional relationship of a component directly above or below and directly adjacent to it. For example, if the expression is "electrode B on insulating layer A," It is not necessary that the electrode B is formed directly on the insulating layer A. This does not exclude the inclusion of other components in between.

[0030] In addition, in this specification and the like, the terms "film" and "layer" may be used interchangeably depending on the situation. For example, the term "conductive layer" can be changed to the term "conductive film." Or, for example, the term "insulating film" may be changed to "insulating layer." In some cases, or depending on the circumstances, it may be possible to change the term to " For example, words such as "film" and "layer" may be omitted and substituted with other terms. For example, the term "conductive layer" or "conductive film" may be changed to the term "conductor." For example, the terms "insulating layer" and "insulating film" may be changed to "insulator." In some cases, it may be possible to change the term to something like this:

[0031] In addition, the terms "electrode" and "wiring" used in this specification and the like refer to these components functionally. This is not intended to be limiting. For example, an "electrode" may be used as a part of a "wire." , and vice versa. Furthermore, the terms "electrode" and "wiring" may be used interchangeably to refer to the plural "electrodes" and "wirings." This also includes cases where the wiring is formed integrally.

[0032] In addition, in this specification and the like, the terms "wiring," "signal line," "power line," etc. may be used interchangeably. Depending on the circumstances, they can be interchanged. For example, "wiring" In some cases, it may be possible to change the term to "signal line". In some cases, it may be possible to change the term "wiring" to a term such as "power line." And vice versa, terms such as "signal line" and "power line" will be changed to the term "wiring". It may be possible to change terms such as "power line" to terms such as "signal line." In addition, the opposite is also true, and terms such as "signal line" may be used interchangeably with "power line" In addition, the term "potential" applied to the wiring may be changed to another term. In some cases or circumstances, the term "signal" may be changed to "signal" or similar. And vice versa, terms such as "signal" may be used to refer to "potential". It may be possible to change the term.

[0033] In this specification, impurities in a semiconductor are, for example, any impurities other than the main components constituting the semiconductor layer. For example, an element with a concentration of less than 0.1 atomic percent is an impurity. This can result in the formation of DOS (Density of States) in semiconductors. In some cases, the carrier mobility may decrease, or the crystallinity may decrease. When the semiconductor is an oxide semiconductor, the impurities that change the characteristics of the semiconductor include, for example, , Group 1 elements, Group 2 elements, Group 13 elements, Group 14 elements, Group 15 elements, other than the main component Transition metals, particularly hydrogen (which is also contained in water), lithium, sodium, Silicon, boron, phosphorus, carbon, nitrogen, etc. In the case of oxide semiconductors, for example, hydrogen, etc. In addition, the inclusion of impurities may cause oxygen vacancies. In this case, impurities that change the properties of a semiconductor include, for example, oxygen and Group 1 elements excluding hydrogen. , Group 2 elements, Group 13 elements, Group 15 elements, etc.

[0034] In this specification, a switch refers to a device that is in a conductive state (on state) or a non-conductive state (off state). A switch is a device that has the function of controlling whether or not current flows by switching on or off. A switch is a device that has the function of selecting and switching the path through which current flows. , electrical switches, mechanical switches, etc. can be used. The present invention is not limited to a specific one, and may be applied to any device capable of controlling a current.

[0035] An example of an electrical switch is a transistor (e.g., a bipolar transistor, MOS transistors, etc.), diodes (e.g., PN diodes, PIN diodes, Schottky diode, MIM (Metal Insulator Metal) die MIS (Metal Insulator Semiconductor) die diode-connected transistors, etc.), or logic circuits that combine these When using a transistor as a switch, the "conduction state" of the transistor This means that the source and drain electrodes of the transistor can be considered to be electrically shorted. The "non-conducting state" of a transistor refers to the state in which the source and drain electrodes of the transistor are in a non-conducting state. This refers to a state in which the gate electrodes can be considered to be electrically disconnected. When the transistor is operated as a switch, the polarity (conductivity type) of the transistor is not particularly limited.

[0036] An example of a mechanical switch is a digital micromirror device (DMD). In 2013, a switch using MEMS (microelectromechanical system) technology was developed. The switch has a mechanically movable electrode, and when the electrode moves, Therefore, the device operates by controlling conduction and non-conduction. Effect of the Invention

[0037] According to one aspect of the present invention, a novel device is provided. As a result, a semiconductor device capable of reducing power consumption can be provided. According to one embodiment of the present invention, a semiconductor device whose area can be reduced can be provided. According to one embodiment, a semiconductor device capable of increasing the capacity of a storage device can be provided.

[0038] The description of these effects does not preclude the existence of other effects. An embodiment does not necessarily have to have all of these effects. The above will become apparent from the description in the specification, drawings, claims, etc. It is possible to extract other effects from the descriptions in the claims, etc. [Brief description of the drawings]

[0039] [Figure 1] Fig. 1(A) is a block diagram showing an example of the configuration of a storage device, and Fig. 1(B) is a diagram explaining an example of a hierarchy of storage areas in the storage device. [Diagram 2] FIG. 2 is a diagram illustrating an example of a hierarchy of storage areas in a storage device. [Diagram 3] 3A, 3B, and 3B2 are circuit diagrams showing examples of the configuration of a memory cell included in a memory device. [Figure 4] 4A and 4B are diagrams illustrating an example of a hierarchy of storage areas in a storage device. [Diagram 5] FIG. 5 is a block diagram showing an example of the configuration of a storage device. [Figure 6] FIG. 6 is a block diagram showing an example of the configuration of a storage device. [Figure 7]FIG. 7 is a block diagram showing an example of the configuration of a storage device. [Figure 8] FIG. 8 is a block diagram showing an example of the configuration of a storage device. [Figure 9] FIG. 9 is a block diagram showing an example of the configuration of a storage device. [Figure 10] FIG. 10 is a block diagram showing an example of the configuration of a memory cell array included in a memory device. [Figure 11] FIG. 11 is a block diagram showing an example of the configuration of a memory cell array included in a memory device. [Figure 12] 12A and 12B are diagrams showing an example of the configuration of a memory cell array included in a memory device. [Figure 13] FIG. 13 is a diagram showing an example of the configuration of a memory cell array included in a memory device. [Figure 14] FIG. 14 is a cross-sectional view showing a configuration example of a semiconductor device. [Figure 15] 15A, 15B, and 15C are cross-sectional views showing examples of the structure of a transistor. [Figure 16] FIG. 16A is a top view illustrating a structural example of a transistor, and FIGS. 16B and 16C are cross-sectional views illustrating the structural example of the transistor. [Figure 17] FIG. 17A is a top view illustrating a structural example of a transistor, and FIGS. 17B and 17C are cross-sectional views illustrating the structural example of the transistor. [Figure 18] FIG. 18A is a top view illustrating a structural example of a transistor, and FIGS. 18B and 18C are cross-sectional views illustrating the structural example of the transistor. [Figure 19] FIG. 19A is a top view illustrating a structural example of a transistor, and FIGS. 19B and 19C are cross-sectional views illustrating the structural example of the transistor. [Figure 20] FIG. 20A is a top view illustrating a structural example of a transistor, and FIGS. 20B and 20C are cross-sectional views illustrating the structural example of the transistor. [Figure 21] FIG. 21A is a top view illustrating a structural example of a transistor, and FIG. 21B is a perspective view illustrating the structural example of the transistor. [Figure 22] 22A and 22B are cross-sectional views showing examples of the structure of a transistor. [Diagram 23] 23(A)(B)(C)(D)(E)(F)(G)(H) are perspective views showing examples of electronic devices. [Figure 24] 24(A) and (B) are perspective views showing an example of an electronic device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] In this specification, the term "metal oxide" refers to metals in a broad sense. Metal oxides are oxide insulators and oxide conductors (including transparent oxide conductors). ), oxide semiconductor (also called "OS"), For example, when a metal oxide is used in the active layer of a transistor, the metal oxide In other words, metal oxides have the functions of amplification, rectification, and forming a channel forming region of a transistor having at least one switching function. If possible, the metal oxide is called a metal oxide semiconductor. It can also be called OS FET or OS transistor. In the above description, the transistor may be expressed as a transistor including a metal oxide or an oxide semiconductor. It is possible.

[0041] In the present specification and the like, metal oxides having nitrogen are also referred to as metal oxides. Metal oxides containing nitrogen are also called metal oxynitrides (MEs). It may also be called tal oxynitride.

[0042] In addition, in this specification and the like, the configurations shown in each embodiment may be the same as the configurations shown in other embodiments. The above-mentioned embodiments can be combined appropriately to form one aspect of the present invention. In the case where multiple configuration examples are shown, the configuration examples can be combined with each other as appropriate.

[0043] In addition, the contents (or even a part of the contents) described in one embodiment may be used in the embodiment. Another content (or a part of the content) described in the embodiment and one or more other embodiments ( or one or more other embodiments) (or a part of the contents) The content may be applied, combined, or substituted for another content.

[0044] In addition, the contents described in the embodiments refer to the following in each embodiment (or example): The contents described using various figures or the contents described using text in the specification be.

[0045] In addition, a figure (or a part of it) described in one embodiment may be replaced with another part of the figure. In the embodiment, another figure (or a part of it) and one or more other embodiments may be used. At least one of the figures (or a part of the figures) described in the embodiment is combined. By adding more, more figures can be constructed.

[0046] The embodiments described in this specification are described with reference to the drawings. The present invention may be embodied in many different forms without departing from the spirit and scope thereof. It will be easily understood by those skilled in the art that various changes in form and detail may be made without departing from the spirit and scope of the present invention. Therefore, the present invention should not be construed as being limited to the description of the embodiment. In the configuration of the invention of the embodiment, the same parts or parts having similar functions are denoted by the same reference numerals. The same description may be used in different drawings and repeated explanations may be omitted. In some cases, in order to make the drawings clearer, the illustration of some components may be omitted. be.

[0047] Also, in the drawings of this specification, the sizes, layer thicknesses, or areas may be exaggerated for clarity. Therefore, the drawings are not necessarily limited to the scale. The drawings are merely illustrative examples, and are not limited to the shapes or values ​​shown in the drawings. For example, signal, voltage, or current variations due to noise, or timing errors This may include signal, voltage or current variations, and the like.

[0048] (Embodiment 1) In this embodiment, an example of a structure according to one embodiment of the present invention will be described.

[0049] <Example of semiconductor device configuration> FIG. 1A illustrates an example of the structure of a semiconductor device 11 according to one embodiment of the present invention. The memory device includes a memory circuit 210, a memory circuit 220, a memory circuit 230, and a memory circuit The control circuit 20 includes a path 240.

[0050] Although not shown in FIG. 1A, the semiconductor device 11 may include an integrated circuit (e.g., a CPU, The memory circuit 210 is included in an integrated circuit. Furthermore, the memory circuit 220 may also be included in an integrated circuit.

[0051] The memory circuit 220 is a dynamic oxide semiconductor memory (DOSRAM). Apply Inductor Random Access Memory (registered trademark) The memory circuit 230 can be implemented using NOSRAM (Dynamic Oxide Semiconductor Random Access Memory). Conductor Random Access Memory (registered trademark) is applied The details of DOSRAM and NOSRAM will be described later.

[0052] FIG. 1B shows a hierarchical structure of the memory circuit of the memory device included in the semiconductor device 11 shown in FIG. FIG. 1 is a diagram showing an example for each layer.

[0053] FIG. 1B shows memory circuits of a memory device included in the semiconductor device 11, in order of access speed. The memory circuit 210 is the highest level, and the memory circuit 220 is the lowest level. The memory circuit 230 is a lower layer than the memory circuit 220. 240 is illustrated as the lowest hierarchy.

[0054] In this specification, the memory circuit of the memory device included in the semiconductor device 11 is the top In order from the top, the first storage area 110, the second storage area 120, the third storage area 130, the fourth storage area 140, the The first memory area 110 is a memory area such as a register. The second memory area 120 is a memory area of ​​a cache memory, and the third memory area 130 is a memory area of ​​a main memory device. The fourth memory area 140 is a memory area of ​​the auxiliary storage device. It is treated as such.

[0055] The memory circuit 210 in the first memory area 110 stores the results and status of arithmetic processing in an integrated circuit or the like. For this reason, the memory circuit 21 is used to transmit and receive data required for the computation process. 0 is electrically connected to the memory circuit 220 and the memory circuit 230.

[0056] The memory circuit 210 that can be applied to the first memory area 110 is, for example, a register, a flip-flop, It has chips, SRAM (Static Random Access Memory), etc. do.

[0057] The second memory area 120 is treated as a memory area of ​​a cache memory, so that the memory circuit 2 20 receives data from the memory circuit 230 that functions as the main memory device, which is the third memory area 130. The memory circuit 230 is electrically connected to the memory device 230 for storing a copy of a portion of the data.

[0058] In addition, since the second memory area 120 corresponds to the memory area of ​​the cache memory, The area 120 can be further divided into a plurality of hierarchical layers. For example, in FIG. The memory circuit 220 in FIG. The first storage area 110 includes a cache 121 to a cache 123. A cache 121 (first level cache, L1 cache) is provided at the top level. A cache 122 (secondary cache, L2 cache) is provided in a lower hierarchy of the cache 121. The cache 122 is placed in a lower level, and the cache 123 (third level cache, L3 cache) is placed in a lower level. There is a designated area for guests.

[0059] The number of hierarchical layers in the second storage area 120 is not limited to this. 20 may consist of only one floor, two floors, or four or more floors. It may be made up of layers.

[0060] The memory circuit 240 applicable to the fourth memory area 140 is the memory circuit 230 of the third memory area. The input data is electrically connected to a memory circuit 230 for storing the input data.

[0061] The memory circuit 240 applicable to the fourth memory area 140 is, for example, a non-volatile memory. The non-volatile memory may include, for example, a flash memory, a hard disk drive, etc. Examples include disk drives and solid-state drives.

[0062] The control circuit 20 is electrically connected to the memory circuit 220 and the memory circuit 230. The control circuit 20 is a second memory area 120 and a third memory area 130 in the semiconductor device 11. It has the function of changing the storage area of ​​each hierarchical level.

[0063] The higher the memory circuit is located in the hierarchy, the faster it is required to operate. The more memory devices are deployed, the greater the demand for larger capacity and higher density (or smaller area per bit). For example, the first storage area 110 stores data used for calculations in an integrated circuit or the like. In order to store the data, high speed operation is particularly required. The first level cache, which is located at the top of the hierarchy, is accessed most frequently and therefore has high speed. On the other hand, the second and third caches are required to operate as fast as the first cache. Although it does not require high speed operation, it has a large capacity and more bits per second than the first level cache. A reduction in area is required.

[0064] In addition, the higher the hierarchy of the memory circuit, the greater the number of times data is rewritten to the memory device. (or refresh frequency) will increase, so the specifications of the storage device will require data retention. On the other hand, the lower the hierarchy of a storage device, the more time it takes to Since the number of times of rewriting data (or the number of refresh times) to the memory device decreases, it is necessary to extend the data retention time as a specification of the memory device. As a specification of the memory device, it is necessary to extend the data retention time.

[0065] One aspect of the present invention changes the data retention time of each layer of the memory device according to the usage status of the semiconductor device, and increases or decreases the memory area of each layer. That is, the memory device or the semiconductor device according to one aspect of the present invention can change the performance of each layer of the memory device according to the usage status. By changing the data retention time of each layer of the memory device according to the usage status of the semiconductor device, the memory area of each layer is increased or decreased. That is, the memory device or the semiconductor device according to one aspect of the present invention can change the performance of each layer of the memory device according to the usage status. According to the usage status, the semiconductor device can change the performance of each layer of the memory device. It can be done.

[0066] <Circuit Configuration Examples of DOSRAM and NOSRAM> Next, the circuit configurations of the memory cells of DOSRAM applicable to the memory circuit 220 and NOSRAM applicable to the memory circuit 230 will be described. The circuit configurations of the memory cells of DOSRAM applicable to the memory circuit 220 and NOSRAM applicable to the memory circuit 230 will be described.

[0067] Note that the low-level potential and high-level potential used in the following description do not mean specific potentials, and if the wiring is different, the specific potentials may also be different. For example, the low-level potential and high-level potential applied to the wiring WOL may be different from the low-level potential and high-level potential applied to the wiring BIL. Note that the low-level potential and high-level potential used in the following description do not mean specific potentials, and if the wiring is different, the specific potentials may also be different. For example, the low-level potential and high-level potential applied to the wiring WOL may be different from the low-level potential and high-level potential applied to the wiring BIL. Each of the low-level potential and high-level potential applied to the wiring WOL may be a potential different from the low-level potential and high-level potential applied to the wiring BIL. Each of the low-level potential and high-level potential applied to the wiring WOL may be a potential different from the low-level potential and high-level potential applied to the wiring BIL.

[0068] FIG. 3(A) shows an example of the circuit configuration of the memory cell of DOSRAM. The memory cell 221 has a transistor M1 and a capacitive element CA. Note that the transistor M1 has a front gate (which may be simply called a gate) and a back gate. The memory cell 221 has a transistor M1 and a capacitive element CA. Note that the transistor M1 has a front gate (which may be simply called a gate) and a back gate. The transistor M1 has a front gate (which may be simply called a gate) and a back gate.

[0069] The first terminal of the transistor M1 is connected to the first terminal of the capacitive element CA, the second terminal of the transistor M1 is connected to the wiring BIL, and the gate of the transistor M1 is connected to the wiring WOL. The first terminal of the transistor M1 is connected to the first terminal of the capacitive element CA, the second terminal of the transistor M1 is connected to the wiring BIL, and the gate of the transistor M1 is connected to the wiring WOL. The back gate of the transistor M1 is connected to the wiring BGL. The second terminal of A is connected to the wiring CAL.

[0070] Transistor M1 functions as a write transistor in memory cell 221. The write transistor is preferably an OS transistor, which will be described later. .

[0071] The wiring BIL functions as a bit line, and the wiring WOL functions as a word line. CAL functions as a wiring for applying a predetermined potential to the second terminal of the capacitive element CA. When writing and reading data, the line CAL is supplied with a low-level potential (reference potential It is preferable to apply a voltage of 100 V.

[0072] The wiring BGL functions as a wiring for applying a potential to the back gate of the transistor M1. By applying an arbitrary potential to the wiring BGL, the threshold voltage of the transistor M1 The voltage can be increased or decreased.

[0073] Data is written and read by applying a high-level potential to the wiring WOL and M1 is turned on to establish electrical continuity between the wiring BIL and the first terminal of the capacitance element CA. This is carried out by.

[0074] Specifically, data is written by applying a potential corresponding to the data to be written to the wiring BIL. This is done by writing the potential to the first terminal of the capacitance element CA via the transistor M1. After writing the data, a low-level potential is applied to the wiring WOL to turn on the transistor M1. By turning off the potential, the potential can be held in the memory cell 221.

[0075] In addition, in order to read data, first, the wiring BIL is set to an appropriate potential, for example, a low level potential. and the high-level potential, and then the wiring BIL is electrically floating. After that, a high-level potential is applied to the wiring WOL to turn on the transistor M1. The potential of the wiring BIL is changed by turning on the wiring BIL. Since it is determined according to the potential written to the first terminal of A, from the changed potential of the wiring BIL, The data stored in the memory cell 221 can be read.

[0076] In addition, the above-mentioned memory cell 221 is not limited to the circuit configuration shown in FIG. The circuit configuration of memory cell 221 may be changed as appropriate.

[0077] FIG. 3(B1) shows an example of the circuit configuration of a memory cell of NOSRAM. The filter 231 includes a transistor M2, a transistor M3, and a capacitance element CB. The transistor M2 has a front gate (sometimes simply called a gate) and a back gate. It has a kugate.

[0078] Transistor M2 functions as a write transistor in memory cell 231. The write transistor is preferably an OS transistor, which will be described later. .

[0079] Transistor M3 also functions as a read transistor in memory cell 231. The readout transistor is an OS transistor, which will be described later, or a transistor having a semiconductor layer with a silicon layer. In this operation example, the transistor Unless otherwise specified, the transistor M3 operates in the saturation region. The gate, source, and drain voltages of transistor M3 are set to the range in which it operates in the saturation region. The inputs are assumed to be appropriately biased to a voltage of

[0080] A first terminal of the transistor M2 is connected to a first terminal of the capacitance element CB, and the transistor M The second terminal of the transistor M2 is connected to the wiring WBL, and the gate of the transistor M3 is connected to the wiring WOL. The back gate of the transistor M2 is connected to the wiring BGL. The second terminal of the transistor M1 is connected to the wiring CAL. The first terminal of the transistor M2 is connected to the wiring R BL, the second terminal of the transistor M3 is connected to the line SL, and the second terminal of the transistor M The gate of 3 is connected to a first terminal of the capacitance element CB.

[0081] The wiring WBL functions as a write bit line, and the wiring RBL functions as a read bit line. The wiring WOL functions as a word line. The wiring CAL is connected to the second It functions as a wiring for applying a predetermined potential to the terminal. It is preferable to apply a low-level potential (sometimes called a reference potential) to the line CAL. When writing data and when reading data, a high-level potential is applied to the wiring CAL. It is preferable to

[0082] The wiring BGL functions as a wiring for applying a potential to the back gate of the transistor M2. By applying an arbitrary potential to the wiring BGL, the threshold voltage of the transistor M2 The voltage can be increased or decreased.

[0083] To write data, a high-level potential is applied to the wiring WOL to turn on the transistor M2. This is achieved by bringing the line WBL and the first terminal of the capacitance element CB into a conductive state. Specifically, when the transistor M2 is in an on state, the information to be recorded in the wiring WBL is A corresponding potential is applied to the first terminal of the capacitance element CB and the gate of the transistor M3. Then, a low-level potential is applied to the wiring WOL to turn off the transistor M2. By setting the capacitor CB in the ON state, the potential of the first terminal of the capacitor CB and the potential of the gate of the transistor M3 are The potential is maintained at .

[0084] Data is read by applying a predetermined potential to the line SL. The current flowing between the source and drain of transistor M3 and the potential of the first terminal of transistor M3 is determined by the potential of the gate of the transistor M3 and the potential of the second terminal of the transistor M3. Since the potential of the wiring RBL connected to the first terminal of the transistor M3 is determined, As a result, a current is held at the first terminal of the capacitance element CB (or the gate of the transistor M3). That is, the potential at the first terminal of the capacitance element CB (or the transistor The information written in this memory cell is read from the potential held at the gate of M3. It can be seen.

[0085] In addition, the above-described memory cell 231 is not limited to the circuit configuration shown in FIG. The circuit configuration of the memory cell 231 may be changed as appropriate. For example, the wiring WBL and the wiring RBL The memory cell may be configured as a single wiring BIL. 3B2. The memory cell 232 has a wiring WBL and a wiring RBL of the memory cell 231. The second terminal of the transistor M2 and the first terminal of the transistor M3 are connected to each other through a single wiring BIL. The terminal is connected to the wiring BIL. The write bit line and the read bit line are configured to operate as a single wiring BIL. It is.

[0086] As mentioned above, DOSRAM and NOSRAM use OS transistors as write transistors. The semiconductor layer of the OS transistor is the same as that described in Embodiment 3. The metal oxide includes, for example, indium, element M (element M is selected from one or more of aluminum, gallium, yttrium, or tin, and zinc; In particular, metal oxides of indium, gallium, and zinc are suitable for this purpose. By being contained in the semiconductor layer, the band gap of the semiconductor layer can be increased. Therefore, the off-state current of the OS transistor can be reduced.

[0087] <How to change the storage area of ​​each tier of a storage device> By the way, the OS transistor can be formed by applying the structure described in Embodiment 3. In the OS transistor having a back gate, By applying a potential to the back gate, the threshold voltage of the OS transistor is changed. For example, when the OS transistor is an n-channel transistor, By applying a positive potential to the back gate, the threshold voltage of the OS transistor By applying a negative potential to the back gate, By this, the threshold voltage of the OS transistor can be shifted to the positive side.

[0088] By varying the threshold voltage of the OS transistor, The off-state current of the OS transistor can be increased or decreased. The charge transfers quickly between the source and drain of the transistor according to the stored data. This shortens the data retention time and increases the operating speed (drive frequency and In addition, the off-state current of the OS transistor can be reduced. When the OS transistor is turned on, the data stored in the OS transistor is transferred between the source and drain. This slows down the movement of charges, which results in longer data retention time and faster operation of the OS transistor. In other words, the threshold voltage of the OS transistor can be changed. The data retention time and operation speed can be adjusted by this.

[0089] Here, the above-mentioned DOSRAM is applied as the memory circuit 220 of the semiconductor device 11, and the memory circuit Consider the case where the above-mentioned NOSRAM is used as the circuit 230. For example, in FIG. In the semiconductor device 11, the storage capacity of the storage circuit 210 used as the first storage area is The memory capacity of the memory circuit 220 used as the second memory area 120 is insufficient. In this case, as shown in FIG. 4A, the memory circuit 220a, which is a part of the memory circuit 220, has The threshold voltage of the OS transistor in the memory circuit 220a is reduced to shorten the data retention time. By shortening the length and increasing the operating speed, the memory circuit 220a can be made to be the first memory area 110. It can be utilized as.

[0090] Specifically, the transistor M1 of the memory cell 221 of the memory circuit 220a is applied with a gate When the applied voltage range is -0.8V to 2.5V, the transistor M For example, a voltage of −1.5 V or more and less than 1.5 V is applied to the back gate of the transistor 1. Thus, the memory circuit 220 a can be utilized as the first memory area 110 .

[0091] In addition, for example, in the semiconductor device 11 of FIG. 1(A)(B), the third memory area 130 may be The storage capacity of the memory circuit 230 used as the second storage area 120 is insufficient. If the memory circuit 220 has a surplus memory capacity, as shown in FIG. The threshold voltage of the OS transistor in the memory circuit 220b, which is a part of the semiconductor memory device 20, is increased. In this way, the data retention time of the memory circuit 220b is increased and the operation speed is slowed down, so that the memory The memory circuit 220b can be utilized as the third memory area 130.

[0092] Specifically, the transistor M1 of the memory cell 221 of the memory circuit 220b is applied with a gate voltage of When the applied voltage range is -0.8V to 2.5V, the transistor M For example, a voltage of −7.5 V or more and less than −4.5 V is applied to the back gate of the transistor 1. Therefore, the memory circuit 220 a can be utilized as the third memory area 130 .

[0093] In the semiconductor device 11 of FIGS. 1A and 1B, the memory region of the memory circuit 220 is If the hierarchy is not changed, that is, the memory circuit 220 is used as the second memory area 120 as usual. When the transistor M1 is operated as above, the range of potential applied to the gate of the transistor M1 is set to -0.8V or more. 2.5V or less, and the back gate of the transistor M1 is set to, for example, -4.5V or more. A voltage of less than 1.5V is sufficient.

[0094] In addition, for example, in the semiconductor device 11 of FIG. 1(A)(B), The storage capacity of the memory circuit 220 used as the third storage area 130 is insufficient. If the memory circuit 230 has a surplus memory capacity, as shown in FIG. The threshold voltage of the OS transistor included in the memory circuit 230a, which is a part of the semiconductor memory device 30, is reduced. In this way, the data retention time of the memory circuit 230a is shortened, so that the memory circuit 230a can be used as a second memory. It can be utilized as a memory area 120.

[0095] Specifically, the transistor of the memory cell 231 (memory cell 232) of the memory circuit 230a The voltage applied to the gate of the transistor M2 is set to -0.8V or more and 2.5V or less. In this case, the back gate of the transistor M2 is, for example, −4.5 V or more and less than −1.5 V. By applying a voltage, the memory circuit 230a can be used as the second memory area 120. can be done.

[0096] In addition, for example, in the semiconductor device 11 of FIG. 1(A)(B), The storage capacity of the memory circuit 240 used as the third storage area 130 is insufficient. If the memory circuit 230 has a surplus memory capacity, as shown in FIG. The threshold voltage of the OS transistor included in the memory circuit 230b, which is a part of the semiconductor memory device 30, is increased. In addition, by lengthening the data retention time of the memory circuit 230b, the memory circuit 230b can be used as a fourth memory. It can be utilized as a memory area 140.

[0097] Specifically, the transistor of the memory cell 231 (memory cell 232) of the memory circuit 230b The potential applied to the gate of the transistor M2 is set to -0.8V or more and 2.5V or less. In this case, for example, a voltage of less than −7.5 V is applied to the back gate of the transistor M2. This allows the memory circuit 230b to be used as the fourth memory area 140.

[0098] In the semiconductor device 11 of FIGS. 1A and 1B, the memory region of the memory circuit 230 is If the hierarchy is not changed, that is, the memory circuit 230 is used as the third memory area 130 as usual. When the transistor M1 is operated as above, the range of potential applied to the gate of the transistor M1 is set to -0.8V or more. The back gate of the transistor M1 is set to, for example, -7.5V or more. Just apply a voltage of less than 4.5V.

[0099] Furthermore, the transistor M1 of the memory cell 221, the memory cell 231 (memory cell 232 ) the range of voltages applied to the gates of the transistors M2 and M3 are approximately the same. Specifically, the gates of the transistors M1 and M2 can be The circuits that generate the positive (or negative) voltages to be applied to the This allows the voltage applied to the gates of the transistors M1 and M2 to be Since it is not necessary to provide a large number of circuits for generating voltages, the power consumption of the semiconductor device 11 can be reduced. In particular, when a negative voltage is applied to the gate of a transistor, the Since the power consumption for generating the voltage can be large, the transistor M1 and the transistor A negative voltage generating circuit (e.g., a charge pump circuit) for applying a negative voltage to each gate of M2 It is preferable that the above-mentioned 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 29,

[0100] By the way, the gate and back gate of the above-mentioned transistor M1 (transistor M2) The range of voltages applied to is an example. The characteristics of a transistor change depending on the material and structure of the semiconductor layer of the transistor. Depending on the situation, it is necessary to set the range of voltages to be applied to the gate and back gate.

[0101] In addition, in semiconductor devices in general, the transistors may vary depending on the environment in which the semiconductor device is operated. Specifically, when the temperature of the environment in which the semiconductor device is operated increases, the characteristics of the semiconductor device may change. The higher the gate-source voltage, the larger the drain current of the transistor. In other words, depending on the temperature of the environment, The performance of the semiconductor device may change depending on the temperature of the environment. By changing the voltage applied to the back gate of the OS transistor, which is the write transistor, It is more preferable to appropriately adjust the characteristics of the transistor by using the above-mentioned method. That is, the transistors included in the memory cell 221 and the memory cell 231 (memory cell 232) The semiconductor device 11 drives the back gates of the transistors M1 and M2. By applying a voltage according to the temperature of the environment, the memory circuits 220 and 230 Each of them can perform an operation appropriate to the temperature of the environment.

[0102] <Control circuit 20> Next, the write transistors ( Transistor M1 in FIG. 3(A), and transistor M2 in FIG. 3(B1) and (B2) A circuit configuration for controlling the threshold voltage of the transistor (corresponding to a transistor having a threshold voltage of 10 V or 11 V) will be described.

[0103] FIG. 5 shows a control circuit 20 for controlling the threshold voltage of the write transistor. In addition, in order to explain the electrical connection with the storage device, FIG. Also shown is a memory unit 30 including a memory circuit 220 and a memory circuit 230.

[0104] The control circuit 20 includes a control unit 21 and voltage generation circuits 22[1] to 22[P]. (P is an integer equal to or greater than 1), a circuit 23A, a circuit 23B, a temperature detection circuit 25, In addition, when the potential of the back gate is not changed according to the environmental temperature, the control circuit The temperature sensor circuit 25 may be omitted from the configuration of the temperature sensor 20 .

[0105] The control unit 21 includes a storage unit 30, and voltage generating circuits 22[1] to 22[P]. , the circuit 23A, the circuit 23B, and the temperature detection circuit 25. Each of the voltage generating circuits 22[1] to 22[P] includes a circuit 23A and a circuit 23B. The circuit 23A is electrically connected to the memory circuit 220, and the circuit 23B is electrically connected to the memory circuit 23 through a plurality of wirings BGL2. Electrically connected to 0.

[0106] The storage unit 30 stores the usage status of the storage circuit 220 and the storage circuit 230 (for example, The control unit 2 receives a signal indicating the percentage of the total storage capacity that is being used, etc. The control unit 21 receives the signal and transmits it to the corresponding Depending on the usage state, each layer of the storage unit 30 (for example, the first storage area 11 shown in FIG. 1B) 0, the first memory area 120, the third memory area 130, and the fourth memory area 140. In order to perform the change, a signal is sent to each circuit included in the control circuit 20. Specifically, the control unit 21 includes voltage generation circuits 22[1] to 22[P], a circuit 23A, and a circuit 2 A signal is sent to 3B.

[0107] Each of the voltage generating circuits 22[1] to 22[P] is a write transistor. The voltage generating circuit 22 [1 The voltage generating circuit 22[P] generates the voltage in response to a signal sent from the control unit 21. This function allows the memory unit to start generating the voltage or stop generating the voltage. Only the voltage generation circuit that generates the necessary voltage in each of the 30 hierarchical allocations is driven, and Therefore, the voltage generating circuit 22[1] through the voltage Since only the necessary circuits of the generation circuit 22[P] can be driven, the control circuit 20 The power consumption can be reduced.

[0108] In addition, among the voltage generating circuits 22[1] to 22[P], The circuit may be, for example, a charge pump circuit.

[0109] The circuit 23A generates voltages to be applied to the multiple wirings BGL1 from a voltage generating circuit 22[1 ] to voltage generation circuit 22[P]. The voltage to be selected for each of the multiple wirings BGL1 is sent from the control unit 21. This function determines the write trace included in the memory circuit 220. A predetermined voltage can be applied to the back gate of the transistor from the wiring BGL1. The circuit 220 can be divided into regions according to the hierarchy to which it is assigned. For example, When dividing 220 into p levels (p is an integer between 2 and P), the circuit 23A is It is sufficient to apply p types of voltages to the wirings BGL1 and divide the memory circuit 220 into p regions. .

[0110] Similarly, the circuit 23B generates voltages to be applied to the multiple wirings BGL2 by a voltage generating circuit The function of selecting from the voltages generated by each of the voltage generating circuits 22[1] to 22[P] The control unit 2 determines which voltage is selected for each of the multiple wirings BGL2. This function determines the write operation of the memory circuit 230 in response to a signal sent from the A certain voltage can be applied to the back gate of the write transistor from the wiring BGL2. In this way, the memory circuit 230 can be divided into regions according to the hierarchical levels to which it is assigned.

[0111] <Example of operation> Here, an example of the operation of the control circuit 20 will be described. The case where the potential of the back gate is not changed accordingly will be described.

[0112] In the initial stage of the operation example, for example, the usage state of the storage unit 30 is as shown in FIG. The entire storage capacity of the memory circuit 220 to which the second memory area 120 is assigned is used up by data. The storage capacity of the memory circuit 230 used for holding and to which the third memory area 130 is assigned Consider the case where a part of the voltage is used to hold data. A circuit 22[p1] (p1 is an integer between 1 and P) is a memory cell of the memory circuit 220. The write transistor included in the memory cell used as the second memory area 120 among the memory cells A voltage generating circuit 22[p2] (p2 is 1 or more and P The third memory cell among the memory circuits 230 is an integer that is equal to or smaller than p1. The back gate of the write transistor included in the memory cell used as region 130 It is assumed that the voltage to be applied to the

[0113] In this case, the storage unit 30 determines that the storage capacity of the second storage area 120 is insufficient. At this time, the storage unit 30 has the entire storage capacity of the storage circuit 220 in a used state, and the storage circuit 23 0, a signal Sig1 is sent to the control unit 21 to inform the control unit 21 that a portion of the storage capacity of the memory area is free.

[0114] By receiving the signal, the control unit 21 controls the voltage generating circuit 22[1] to the voltage generating The signal Sig2 is sent to the synthesis circuit 22[P], and the signal Sig3 is sent to the circuit 23B. The signal Sig2 and the signal Sig3 are used to allocate the second memory area 120 to the memory circuit 230. It's a signal.

[0115] Specifically, the signal Sig2 allocates the second memory area 120 to a predetermined area of ​​the memory circuit 230. In order to assign the write transistor to the target region, a voltage is applied to the back gate of the write transistor included in the target region. The signal may be used to select a circuit for generating a voltage. The voltage generating circuit 22[p3] (p3 is an integer between 1 and P, and is not p2) ) is selected. The voltage generating circuit 22[p3] is connected to the voltage generating circuit 22[p1]. They may be the same or different circuits.

[0116] In addition, the voltage generating circuits that are not selected by the signal Sig2 are as described above. For example, a voltage generating circuit and a wiring for supplying a driving voltage may be configured to stop the driving voltage. By making the electrical connection between the The voltage generating circuit can be stopped. This allows only the necessary voltage generating circuits to be driven. Therefore, the power consumption of the control circuit 20 can be reduced.

[0117] The signal Sig3 is a bias voltage for the write transistor in the specified region of the memory circuit 230. The voltage generated by the voltage generating circuit 22[p3] is applied to BGL2, which is electrically connected to the clock gate. The signal Sig3 may be a signal including a command to apply a voltage. The back gate of the write transistor included in the third memory area 130 of 30 is provided with a It may also include a command to subsequently apply the voltage generated by the voltage generating circuit 22[p2].

[0118] The signal Sig3 is sent to the circuit 23B, whereby the voltage generating circuit 22[p3] generates The voltage thus determined is applied to the write area of ​​the memory circuit 230 to which the second memory area 120 is to be newly allocated. This can be applied to the back gate of the transistor. The second storage area 120 can be allocated to the area. 1 is a continuation of the block diagram shown in FIG. 1, in which the signal Sig3 is sent to the circuit 23B. Thus, all of the remaining free space in the memory capacity of the memory circuit 230 of the memory unit 30 is used as the second memory. An example of allocation to area 120 is shown.

[0119] <Temperature control> Next, the write transistors (transistors M1, A method for changing the potential applied to the back gate of the transistor M2 will be described.

[0120] The temperature detection circuit 25 may have a configuration shown in FIG. In order to explain the electrical connection configuration with the sensing circuit 25, FIG. 22[1], the voltage generating circuit 22[P], the circuit 23A, and the wiring BGL1 are also shown. , the circuit 23B, the wiring BGL2, and the storage unit 30 are omitted.

[0121] The temperature detection circuit 25 includes a temperature sensor 25a, an analog-to-digital conversion circuit 25b, and a voltage and a control circuit 25c.

[0122] The temperature sensor 25a senses the temperature around the semiconductor device 11 and outputs a temperature signal in response to the temperature. The output analog signal is converted into an analog digital signal. The temperature sensor 25a is made of, for example, platinum or nickel. Use a resistance thermometer such as Kel or copper, a thermistor, a thermocouple, or an IC temperature sensor. can be done.

[0123] The analog-to-digital conversion circuit 25b has a function of converting an analog signal into a digital signal. The digital signal is sent to the voltage control circuit 25c.

[0124] The voltage control circuit 25c has a function of generating a correction voltage in response to the digital signal. For example, the voltage control circuit 25c stores a correspondence table that associates digital signals with correction voltages. and a circuit for generating a correction voltage, The magnitude of the corresponding correction voltage is read out from the digital signal sent from the conversion circuit 25b. After reading out the level of the correction voltage, the circuit that generates the correction voltage generates the corresponding correction voltage. The generated signal is sent to the circuit 23A and the circuit 23B via the control unit 21. 6, 7, and 8, the temperature detection circuit 25 is electrically connected to the control unit 21. The temperature detection circuit 25 may be electrically connected directly to the circuit 23A and the circuit 23B. .

[0125] Here, the circuit 23A (circuit 23B) has a plurality of capacitance elements CF. One of the two pairs of electrodes is electrically connected to the wirings BGL1 (the wirings BGL2). The correction voltage sent to the circuit 23A (circuit 23B) is connected to the capacitance element The voltage Vcc is applied to the other of the two pairs of electrodes of the CF.

[0126] Incidentally, the circuit 23A (circuit 23B) has an internal circuit 23IN. N receives a signal from the control unit 21 and controls a plurality of wirings BGL1( The voltage generating circuits 22[1] to 22[P] are connected to the respective wirings BGL2). The device has a function of applying multiple types of voltages generated by the above.

[0127] When changing the potential of the back gate in response to the environmental temperature, first, the internal circuit 23I A potential is applied to the multiple wirings BGL1 (multiple wirings BGL2) by N, and then A correction voltage is applied to the other of the two pairs of electrodes of the capacitance element. The capacitance of the multiple wirings BGL1 (multiple wirings BGL2) is increased by the capacitive coupling of the capacitance element CF. The potential varies depending on the correction voltage. By having such a function, the characteristics of the write transistor of the memory unit 30 can be compensated for depending on the temperature of the environment. It can be corrected.

[0128] Note that one embodiment of the present invention is not limited to the circuit configuration described in this embodiment and may be modified as appropriate. It is possible.

[0129] Note that this embodiment mode can be appropriately combined with other embodiment modes shown in this specification. do.

[0130] (Embodiment 2) In this embodiment, the DOSRAM, NOSRAM, etc. described in the above embodiment are configured. A configuration example of the memory cell array 40 and its peripheral circuits will be described. In this embodiment, the memory cell array 40 and its peripheral circuits are collectively referred to as a memory device 200.

[0131] <Storage device configuration example> An example of the configuration of a storage device is shown in Fig. 9. The storage device 200 includes a peripheral circuit 50 and a memory. The peripheral circuit 50 includes a row decoder 53, a word line driver circuit 5 1, bit line driver circuit 52, output circuit 54, and control logic circuit 56 9 also shows the control circuit 20 described in the first embodiment.

[0132] The bit line driver circuit 52 includes a column decoder 52a, a precharge circuit 52b, and a sensor The precharge circuit 52b includes a scan amplifier 52c and a write circuit 52d. SL, wiring CAL, wiring BIL, etc. The transistor c has a function of amplifying the data signals read from the wirings BIL and RBL. The wiring SL, the wiring CAL, and the wiring RBL are memory cells included in the memory cell array 40. The amplified data signal is then fed to the output circuit. 54, and is outputted to the outside of the storage device 200 as a digital data signal RDATA. do.

[0133] The storage device 200 is supplied with a low power supply voltage (VSS) from the outside as a power supply voltage, A high power supply voltage (VDD) for the memory cell array 40 and a high power supply voltage (VIL) for the memory cell array 40 are supplied. .

[0134] The memory device 200 also includes control signals (CE, WE, RE), an address signal ADDR, A data signal WDATA is input from the outside. An address signal ADDR is input to a row decoder 5. 3 and the column decoder 52a, and WDATA is input to the write circuit 52d. do.

[0135] The control logic circuit 56 processes input signals (CE, WE, RE) from the outside. The CE generates control signals for the row decoder 53 and the column decoder 52a. WE is the write enable signal, and RE is the read enable signal. The signals processed by the control logic circuit 56 are not limited to these. Instead, other control signals may be input as required.

[0136] It should be noted that the above-mentioned circuits and signals can be appropriately selected or omitted as necessary.

[0137] Not only the memory cell array 40 but also the peripheral circuit 50 can be configured with OS transistors. This is preferable because the peripheral circuit 50 and the memory cell array 40 can be manufactured in the same manufacturing process. This makes it possible to keep the manufacturing cost of the memory device 200 low.

[0138] <Example of memory cell array configuration> FIG. 1 shows details of a memory cell array 40 in which DOSRAM is used as a memory cell. The memory cell array 40 has m (m is an integer of 1 or more) memory cells arranged in a row. The memory cell 221 has n (n is an integer of 1 or more) memory cells 221 in a row, totaling m×n memory cells 221. The cells 221 are arranged in a matrix. In FIG. 10, the addresses of the memory cells 221 are also shown. The notation is [1,1], [m,1], [i,j], [1,n], [m,n] (i is , m is an integer between 1 and m, and j is an integer between 1 and n. In the configuration of memory cell 221, the memory cell array The number of wirings WOL connecting the array 40 and the word line driver circuit 51 is m (see FIG. In FIG. 10, only the wiring WOL[1], the wiring WOL[i], and the wiring WOL[m] are illustrated. ), the number of wirings BGL connecting the memory cell array 40 and the control circuit 20 is also m. (In FIG. 10, only the wiring BGL[1], the wiring BGL[i], and the wiring BGL[m] are shown. In addition, the wiring connecting the memory cell array 40 and the bit line driver circuit 52 The number of BILs is n (in FIG. 10, the wiring BIL[1], the wiring BIL[j], the wiring BI Only L[n] is shown.)

[0139] In addition, details of the memory cell array 40 when NOSRAM is used as the memory cell are shown in FIG. 11. The memory cell array 40 has m (m is an integer of 1 or more) memory cells arranged in a row. Each row has n (n is an integer of 1 or more) memory cells 231, for a total of m×n memory cells 231. The memory cells 231 are arranged in a matrix. In FIG. 11, the addresses of the memory cells 231 are Also shown are [1,1], [m,1], [i,j], [1,n], and [m,n]. (i is an integer between 1 and m, and j is an integer between 1 and n.) In the configuration of memory cell 231, the memory The number of wirings WOL connecting the cell array 40 and the word line driver circuit 51 is m. (In FIG. 11, only the wiring WOL[1], the wiring WOL[i], and the wiring WOL[m] are shown.) ), the number of wirings BGL connecting the memory cell array 40 and the control circuit 20 is also m. (In FIG. 11, only the wiring BGL[1], the wiring BGL[i], and the wiring BGL[m] are shown.) The number of wires in the wiring CAL is also m (in Fig. 11, wiring C Only AL[1], wiring CAL[i], and wiring CAL[m] are shown.) The connection to the memory cell 231 via the memory cell array 231 is omitted. The wiring RBL, the wiring WBL, and the wiring SL which connect the bit line driver circuit 40 and the bit line driver circuit 52 The number of each is n (in FIG. 11, RBL[1], RBL[j], RBL[j], RBL[n], wiring WBL[1], wiring WBL[j], wiring WBL[n], wiring SL[1 ], wiring SL[j], and wiring SL[n] are only shown.)

[0140] In the memory cell array 40 shown in each of FIGS. 10 and 11, the wiring BGL[1 Since the wirings BGL[m] to BGL[m] are provided for each row, The change of the area of ​​each layer of the memory cell array 40 is performed on a row-by-row basis. The backgain of the transistor M1 (transistor M2) of the resistor 221 (memory cell 231) The arrangement of the wiring BGL electrically connected to the port is not limited to that shown in FIG. 10 and FIG. 11. For example, , the transistors M1 (M2 ) is provided with a wiring BGL, and each memory cell 221 (memory cell 231) is stored The area of ​​each layer of the device may be changed. Divide the cell 221 (memory cell 231) into regions such as 2×2 or 2×3, and A different wiring BGL may be provided for each of the layers to change the area of ​​each layer of the memory device.

[0141] In each of the memory cell arrays 40 shown in FIG. 10 and FIG. 11, the memory cells 221 The memory cells 231 are arranged two-dimensionally. As shown in FIG. 12A, the memory cells may be arranged in three dimensions. The wiring BIL provided in the array 40 is substantially perpendicular to the bit line driver circuit 52. In FIG. 12B, a plurality of memory cell arrays 40 and a bit line driver The memory 52 and the circuit 53 are overlapped with each other. Although the example of the cell 221 is shown, the memory cell 231 can also be arranged three-dimensionally in the same manner. In FIGS. 12A and 12B, the bit line driver circuit 52 is illustrated in the lower layer. Instead of the line driver circuit 52, a word line driver circuit 51, a row decoder 53, or A plurality of these may be selected and stacked to form a circuit.

[0142] As shown in FIG. 10 and FIG. 11, the memory device 200 is configured to reduce the circuit area. This allows for a smaller file size and a larger memory capacity.

[0143] 12(A) and (B), a memory cell array 40 having a plurality of memory cell arrays 40 shown in FIG. As shown in FIG. 13, the memory cell arrays 40 shown in FIG. 10 and FIG. 11 are configured as follows. In other words, the storage device 200 is a DOSRAM and a N The OSRAM and the memory circuit 220 are overlapped with each other, that is, the memory circuit 230 and the memory circuit 230 are overlapped with each other. In addition, in FIG. 13, the overlapping configuration For clarity, the voltages between the memory cell arrays 40 and the bit line driver circuits 52 are In addition, in FIG. 13, the bit line driver circuit 52 is illustrated in the lower layer. However, instead of the bit line driver circuit 52, a word line driver circuit 51 and a row decoder In particular, the lower layer may have a voltage generating By providing circuits such as a memory circuit 220 and a precharge circuit, In each operation of 230, the circuits can be shared with each other.

[0144] Note that one embodiment of the present invention is not limited to the circuit configuration described in this embodiment and may be modified as appropriate. For example, in this embodiment, the memory cell array 40 includes the memory cell 221. Although the case where the memory cell 231 is applied has been described, a different memory cell may be applied. Good too.

[0145] Note that this embodiment mode can be appropriately combined with other embodiment modes shown in this specification. do.

[0146] (Embodiment 3) In this embodiment mode, an OS transistor applicable to the semiconductor device described in the above embodiment mode will be described. A configuration example of the data recorder will be described below.

[0147] <Example of semiconductor device configuration> The semiconductor device shown in FIG. 14 includes a transistor 300, a transistor 500, and a capacitor element FIG. 15A is a cross-sectional view of the transistor 500 in the channel length direction. 15(B) is a cross-sectional view of the transistor 500 in the channel width direction, and FIG. 4C) is a cross-sectional view of the transistor 300 in the channel width direction.

[0148] The transistor 500 is a transistor having a metal oxide in a channel formation region (OS transistor). Since the off-state current of the transistor 500 is small, In particular, by using it for the transistor M2 of the memory cell 231, the first data In other words, the frequency of refresh operations is low, or Since no refresh operation is required, the power consumption of the semiconductor device can be reduced.

[0149] The transistor 500 is provided above the transistor 300, and the capacitance element 600 is The capacitor 600 is disposed above the transistor 300 and the transistor 500. can be the capacitance element CB in the memory cell 231.

[0150] The transistor 300 is disposed on a substrate 311, and includes a conductor 316, an insulator 315, and a substrate 316. A semiconductor region 313 formed of a part of 311, a low-temperature region functioning as a source region or a drain region The transistor 300 has a resistive region 314a and a low resistive region 314b. For example, the present invention can be applied to the transistor M3 in the above embodiment.

[0151] As shown in FIG. 15C, the transistor 300 is The side surfaces in the width direction of the panel are covered with the conductor 316 via the insulator 315. By forming the transistor 300 as a fin type, the effective channel width is increased. This improves the on-characteristics of the transistor 300. Since the contribution can be increased, the off-characteristics of the transistor 300 can be improved. Cut.

[0152] The transistor 300 may be either a p-channel type or an n-channel type. .

[0153] The region in which the channel of the semiconductor region 313 is formed, the region in the vicinity thereof, the source region, or the drain region In the low resistance region 314a and the low resistance region 314b which become the drain region, silicon It is preferable that the semiconductor material contains a semiconductor such as a silicon-based semiconductor, and it is preferable that the semiconductor material contains single crystal silicon. are Ge (germanium), SiGe (silicon germanium), and GaAs (gallium arsenide). Alternatively, the insulating layer 12 may be formed of a material having a conductivity of 0.1 to 1.0 m / s, such as gallium aluminum arsenide (GaAlAs) or gallium aluminum arsenide (GaAlAs). The effective mass of silicon is controlled by applying stress to the crystal lattice and changing the lattice spacing. Alternatively, the transistor 30 may be made of GaAs and GaAlAs. 0 stands for High Electron Mobility Transistor (HEMT) ) can also be used.

[0154] The low resistance region 314a and the low resistance region 314b are semiconductor regions applied to the semiconductor region 313. In addition to the material, elements that impart n-type conductivity, such as arsenic or phosphorus, or p-type conductivity, such as boron, are added. Contains an element that imparts electrical conductivity.

[0155] The conductor 316 that functions as the gate electrode is made of arsenic, phosphorus, or the like that imparts n-type conductivity. An element, or a semiconductor material such as silicon that contains an element that gives it p-type conductivity, such as boron For example, a conductive material such as a graphite material, a metal material, an alloy material, or a metal oxide material can be used.

[0156] In addition, since the work function is determined by the material of the conductor, it is necessary to select the material of the conductor. In this way, the threshold voltage of the transistor can be adjusted. It is preferable to use a material such as tantalum or tantalum nitride. To achieve this, metal materials such as tungsten and aluminum are used as laminations for the conductor. It is particularly preferable to use tungsten from the viewpoint of heat resistance.

[0157] Note that the transistor 300 shown in FIG. 14 is just an example, and the present invention is not limited to this structure. An appropriate transistor may be used depending on the configuration and driving method. For example, the transistor 300 The structure of the transistor 500 may be the same as that of the transistor 500 including an oxide semiconductor (see FIG. The transistor 500 will be described in detail later.

[0158] Covering the transistor 300 are an insulator 320, an insulator 322, an insulator 324, and an insulator 326. The bodies 326 are stacked in order.

[0159] The insulators 320, 322, 324, and 326 may be, for example, oxide. Silicon, silicon oxynitride, silicon nitride oxide, silicon nitride, aluminum oxide, oxide Aluminum oxynitride, aluminum oxynitride, aluminum nitride, or the like may be used.

[0160] In this specification, silicon oxynitride refers to a material having a higher content of oxygen than nitrogen. Silicon oxide nitride refers to a material that contains more nitrogen than oxygen in its composition. In this specification, aluminum oxynitride refers to a material with a high content. Aluminium oxide nitride refers to a material that contains more oxygen than nitrogen as a composition. This refers to a material that has a higher nitrogen content than oxygen content as a composition.

[0161] The insulator 322 serves to eliminate a step caused by the transistor 300 and the like provided below. For example, the upper surface of the insulator 322 may have a function as a planarizing film to reduce the In order to improve the flatness, the surface is flattened by a planarization process such as chemical mechanical polishing (CMP). It may be possible.

[0162] The insulator 324 is provided with a transistor-insulating layer 324. The transistor-insulating layer ... A film having a barrier property to prevent diffusion of hydrogen and impurities is used in the area where the capacitor 500 is provided. It is preferable that

[0163] An example of a film having a barrier property against hydrogen is silicon nitride formed by a CVD method. Here, a semiconductor having an oxide semiconductor such as the transistor 500 can be used. When hydrogen diffuses into a semiconductor element, the characteristics of the semiconductor element may deteriorate. Therefore, a film for suppressing hydrogen diffusion is provided between the transistor 500 and the transistor 300. Specifically, the film that suppresses hydrogen diffusion is one that reduces the amount of hydrogen desorption. The membrane is thin.

[0164] The amount of desorption of hydrogen can be analyzed, for example, by using thermal desorption spectroscopy (TDS). For example, the amount of hydrogen desorbed from the insulator 324 can be calculated by TDS analysis. In the range of 50°C to 500°C, the amount of desorption converted to hydrogen atoms is Converted to a hit, it's 10 x 10 15 atoms / cm 2 Less than or equal to 5×10 15 a toms / cm 2 The following is acceptable.

[0165] It is preferable that the insulator 326 has a lower relative dielectric constant than the insulator 324. For example, The relative dielectric constant of the insulator 326 is preferably less than 4, more preferably less than 3. The relative dielectric constant of the body 326 is preferably 0.7 times or less than the relative dielectric constant of the insulator 324, and more preferably 0.6 times or less. By using a material with a low dielectric constant as the interlayer film, the parasitic capacitance between the wirings can be reduced. can be reduced.

[0166] In addition, the insulators 320, 322, 324, and 326 are provided with a capacitance element 6. 00, or a conductor 328 and a conductor 330 connected to the transistor 500 are embedded. The conductor 328 and the conductor 330 function as plugs or wiring. In addition, the conductor having the function of a plug or wiring is a single structure that is integrated with multiple structures. In addition, in this specification, wiring and a plug connected to the wiring may be In other words, a part of the conductor functions as a wiring, and In some cases, a portion of the conductor serves as the plug.

[0167] The materials for each plug and wiring (conductor 328, conductor 330, etc.) include metal materials, alloys, Conductive materials such as gold, metal nitride, or metal oxide materials are used in a single layer or in a laminated form. High melting point materials such as tungsten and molybdenum that are both heat resistant and conductive can be used. It is preferable to use a material such as tungsten, and more preferably, aluminum. It is preferable to form the wiring layer from a low-resistance conductive material such as aluminum or copper. This makes it possible to reduce the wiring resistance.

[0168] A wiring layer may be provided on the insulator 326 and the conductor 330. For example, in FIG. An insulator 350, an insulator 352, and an insulator 354 are stacked in this order. In addition, a conductor 356 is formed on the insulators 350, 352, and 354. The conductor 356 functions as a plug or wiring that connects to the transistor 300. The conductor 356 is provided using the same material as the conductors 328 and 330. It is possible.

[0169] For example, the insulator 350 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator having a barrier property against hydrogen as the conductor 356. In particular, the insulator 350 having a barrier property against hydrogen is useful. A conductor having a barrier property against hydrogen is formed in the opening. The transistor 300 and the transistor 500 can be separated by a barrier layer. Therefore, the diffusion of hydrogen from the transistor 300 to the transistor 500 can be suppressed.

[0170] As a conductor having a barrier property against hydrogen, for example, tantalum nitride or the like is used. In addition, by laminating tantalum nitride and highly conductive tungsten, The diffusion of hydrogen from the transistor 300 can be suppressed while maintaining the overall conductivity. In this case, the tantalum nitride layer having a barrier property against hydrogen is It is preferable that the insulating body 350 has a structure in which the insulating body 350 is in contact with the insulating body 350.

[0171] A wiring layer may be provided on the insulator 354 and the conductor 356. For example, in FIG. An insulator 360, an insulator 362, and an insulator 364 are stacked in this order. In addition, a conductor 366 is formed on the insulators 360, 362, and 364. The conductor 366 functions as a plug or wiring. The conductive body 328 and the conductive body 330 may be formed using similar materials.

[0172] For example, the insulator 360 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator having a barrier property against hydrogen as the conductor 366. In particular, the insulator 360 having a barrier property against hydrogen is useful. It is preferable that a conductor having a barrier property against hydrogen is formed in the opening. In this configuration, transistor 300 and transistor 500 are separated by a barrier layer. This makes it possible to suppress the diffusion of hydrogen from the transistor 300 to the transistor 500. can.

[0173] A wiring layer may be provided on the insulator 364 and the conductor 366. For example, in FIG. An insulator 370, an insulator 372, and an insulator 374 are stacked in this order. In addition, a conductor 376 is formed on the insulators 370, 372, and 374. The conductor 376 functions as a plug or wiring. The conductive body 328 and the conductive body 330 may be formed using similar materials.

[0174] For example, the insulator 370 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator having a barrier property against hydrogen as the conductor 376. In particular, the insulator 370 having a barrier property against hydrogen is useful. It is preferable that a conductor having a barrier property against hydrogen is formed in the opening. In this configuration, transistor 300 and transistor 500 are separated by a barrier layer. This makes it possible to suppress the diffusion of hydrogen from the transistor 300 to the transistor 500. can.

[0175] A wiring layer may be provided on the insulator 374 and the conductor 376. For example, in FIG. An insulator 380, an insulator 382, ​​and an insulator 384 are stacked in this order. In addition, a conductor 386 is formed on the insulators 380, 382, ​​and 384. The conductor 386 functions as a plug or wiring. The conductive body 328 and the conductive body 330 may be formed using similar materials.

[0176] For example, the insulator 380 has a barrier property against hydrogen, similar to the insulator 324. It is preferable to use an insulator having a barrier property against hydrogen. In particular, the insulator 380 having a barrier property against hydrogen is useful. It is preferable that a conductor having a barrier property against hydrogen is formed in the opening. In this configuration, transistor 300 and transistor 500 are separated by a barrier layer. This makes it possible to suppress the diffusion of hydrogen from the transistor 300 to the transistor 500. can.

[0177] In the above, the wiring layer including the conductor 356, the wiring layer including the conductor 366, the conductor 376 The wiring layer including the conductor 386 and the wiring layer including the conductor 387 have been described above. However, the semiconductor device to be used is not limited to this. Alternatively, the number of wiring layers may be three or less, or the number of wiring layers similar to the wiring layer including the conductor 356 may be five or more. Good too.

[0178] On the insulator 384, an insulator 510, an insulator 512, an insulator 514, and an insulator 516 are formed. , are stacked in this order. It is preferable that any of the bodies 516 is made of a material that has a barrier property against oxygen and hydrogen. .

[0179] For example, the insulator 510 and the insulator 514 may include, for example, the substrate 311 or the transistor. Hydrogen and impurities diffuse from the region where the transistor 300 is provided to the region where the transistor 500 is provided. It is preferable to use a film having a barrier property that prevents the insulator 324 from scattering. The same materials as those mentioned above can be used.

[0180] As an example of a film that has a barrier property against hydrogen, silicon nitride formed by CVD method is used. Here, a semiconductor element having an oxide semiconductor, such as a transistor 500, However, the diffusion of hydrogen may deteriorate the characteristics of the semiconductor element. A film that suppresses hydrogen diffusion is used between the transistor 500 and the transistor 300. Specifically, the film that suppresses hydrogen diffusion is a film that reduces the amount of hydrogen desorption. do.

[0181] In addition, as a film having a barrier property against hydrogen, for example, an insulator 510 and an insulator 5 14 uses metal oxides such as aluminum oxide, hafnium oxide, and tantalum oxide. It is preferred.

[0182] In particular, aluminum oxide is highly resistant to oxygen and hydrogen, which are factors that affect the electrical characteristics of transistors. The membrane has a high blocking effect, preventing both impurities such as oxygen and water from penetrating the membrane. Aluminum oxide is highly resistant to insufficient hydrogen, moisture, and other impurities during and after the transistor manufacturing process. It is possible to prevent the inclusion of impurities in the transistor 500. Therefore, the release of oxygen from the oxide constituting the transistor 5 can be suppressed. It is suitable for use as a protective film against 00.

[0183] For example, the insulator 512 and the insulator 516 are made of the same material as the insulator 320. In addition, it is possible to use materials with a relatively low dielectric constant for these insulators. For example, the insulator 512 and the insulator The body 516 may be a silicon oxide film, a silicon oxynitride film, or the like.

[0184] In addition, the insulators 510, 512, 514, and 516 are provided with a conductor 5 18, and conductors (e.g., conductor 503) constituting the transistor 500 are embedded. Note that the conductor 518 is connected to the capacitor 600 or the transistor 300. The conductor 518 functions as a plug or a wiring. It can be provided using the same material as 30.

[0185] In particular, the insulator 510 and the conductor 518 in the area in contact with the insulator 514 are oxidized to oxygen, hydrogen, It is preferable that the conductive material has a barrier property against water. The transistor 300 and the transistor 500 have a barrier property against oxygen, hydrogen, and water. The layers can be separated, and hydrogen diffusion from transistor 300 to transistor 500 can be prevented. can be suppressed.

[0186] Above the insulator 516 is a transistor 500 .

[0187] As shown in FIGS. 15A and 15B, the transistor 500 includes an insulator 514 and an insulator A conductor 503 disposed so as to be embedded in an insulator 516 and a conductor 503 An insulator 520 disposed on the insulator 520, an insulator 522 disposed on the insulator 520, and an insulator An insulator 524 is disposed on the body 522, and an oxide 530 is disposed on the insulator 524. a, an oxide 530b disposed on the oxide 530a, and a layer of oxide 530b spaced apart from each other. Conductor 542a and conductor 542b are arranged in a parallel relationship. b, and an opening is formed between the conductor 542a and the conductor 542b. Formation of the oxide 530c disposed on the bottom and sides of the opening and the body 580. An insulator 550 is disposed on the surface of the substrate 50, and a conductor 560 is disposed on the surface of the insulator 550. Yes.

[0188] As shown in FIGS. 15(A) and 15(B), the oxide 530a, the oxide 530b, the conductor 542a, and an insulator 544 is disposed between the conductor 542b and the insulator 580. As shown in FIGS. 15(A) and 15(B), the conductor 560 is preferably an insulator 550. A conductor 560a is provided inside the conductor 560a, and a conductor 560b is provided so as to be embedded inside the conductor 560a. It is preferable that the conductor 560b is provided in the conductor 560b. As shown, the insulator 574 is disposed on the insulator 580, the conductor 560, and the insulator 550. It is preferable that

[0189] In the following, the oxide 530a, the oxide 530b, and the oxide 530c are collectively referred to as oxides 530a, 530b, and 530c. This is sometimes called oxide 530.

[0190] In the transistor 500, an oxide is formed in the region where the channel is formed and in the vicinity thereof. 5 shows a structure in which three layers of oxide 530a, oxide 530b, and oxide 530c are laminated. However, the present invention is not limited thereto. For example, a single layer of oxide 530b, A two-layer structure of the oxide 530b and the oxide 530a, a two-layer structure of the oxide 530b and the oxide 530c, Alternatively, a stacked structure of four or more layers may be provided. Although the conductor 560 is shown as having a two-layer laminate structure, the present invention is not limited to this. For example, the conductor 560 may have a single-layer structure or a laminated structure of three or more layers. The transistor 500 illustrated in FIGS. 14, 15A, and 15B is just an example. There are no limitations on the structure, and appropriate transistors may be used depending on the circuit configuration and driving method.

[0191] Here, the conductor 560 functions as a gate electrode of the transistor, and the conductors 542a and The conductor 542b functions as a source electrode and a drain electrode, respectively. The conductor 560 is sandwiched between the opening of the insulator 580 and the conductors 542a and 542b. The conductor 560, the conductor 542a, and the conductor 542b are formed so as to be embedded in the region. The location of 42b is selected to be self-aligned with the opening of the insulator 580. In the transistor 500, the gate electrode is self-aligned between the source electrode and the drain electrode. Therefore, the conductor 560 can be arranged with a margin for alignment. Since the transistor 500 can be formed without any need for a gate, the area occupied by the transistor 500 can be reduced. This allows miniaturization and high integration of semiconductor devices.

[0192] Furthermore, a conductor 560 is formed in a self-aligned manner in the region between the conductors 542a and 542b. Since the conductor 560 is formed, the conductor 560 has an overlapping region with the conductor 542a or the conductor 542b. As a result, the conductor 560 is not formed between the conductor 542a and the conductor 542b. Therefore, the switching speed of the transistor 500 can be improved. It is possible to improve the transmission efficiency and provide high frequency characteristics.

[0193] The conductor 560 may function as a first gate (also called a top gate) electrode. The conductor 503 also functions as a second gate (also called a bottom gate) electrode. In this case, the potential applied to the conductor 503 may be different from the potential applied to the conductor 560. By changing the threshold voltage of the transistor 500 independently, the threshold voltage of the transistor 500 can be controlled. In particular, applying a negative potential to the conductor 503 can turn on the transistor 5 It is possible to increase the threshold voltage of 00 to be higher than 0V and reduce the off-current. Therefore, applying a negative potential to the conductor 503 increases the current flow rate of the conductor 560 compared to when no negative potential is applied. This can reduce the drain current when the potential applied to is 0V.

[0194] The conductor 503 is disposed so as to overlap the oxide 530 and the conductor 560. Therefore, when a potential is applied to the conductor 560 and the conductor 503, The electric field and the electric field generated by the conductor 503 are connected, forming a channel in the oxide 530. In the present specification and the like, the first gate electrode and the second gate electrode can cover the region where the first gate electrode and the second gate electrode are formed. The structure of a transistor in which the electric field of the gate electrode electrically surrounds the channel formation region is called This is called a surrounded channel (S-channel) structure.

[0195] The conductor 503 has the same configuration as the conductor 518, and the insulators 514 and 5 A conductor 503a is formed in contact with the inner wall of the opening 16, and a conductor 503b is formed further inside. It has been made.

[0196] The insulators 520, 522, 524, and 550 serve as gate insulating films. It has all the functions.

[0197] Here, the insulator 524 in contact with the oxide 530 has more oxygen than the stoichiometric composition. It is preferable to use an insulator that contains a large amount of oxygen. That is, the insulator 524 has an excess oxygen region. It is preferable that the insulator containing such excess oxygen is formed in the oxide 530. By providing the oxide 530 in contact with the oxide 530, oxygen vacancies in the oxide 530 are reduced, and the signal quality of the transistor 500 is improved. The reliability can be improved.

[0198] As an insulator having an excess oxygen region, specifically, an oxide insulator in which a part of oxygen is released by heating is used. It is preferable to use oxide materials that release oxygen when heated. Thermal Desorption Spectroscopy (DSA) analysis revealed that oxygen atoms The converted amount of oxygen released is 1.0 x 10 18 atoms / cm 3 More than or equal to 1.0 ×10 19 atoms / cm 3 More preferably, 2.0×10 19 atoms / c m 3 or more than 3.0 x 10 20 atoms / cm 3 The oxide film is as described above. The surface temperature of the film during the TDS analysis is 100°C or higher and 700°C or lower, or The temperature range is preferably from 0° C. to 400° C.

[0199] Also, if the insulator 524 has an excess oxygen region, the insulator 522 may be oxygen-absorbed (e.g., It has the function of suppressing the diffusion of oxygen atoms, oxygen molecules, etc. (the oxygen is less likely to permeate). is preferred.

[0200] The insulator 522 has a function of suppressing the diffusion of oxygen and impurities, and the oxide 530 The oxygen contained in the conductor 503 is preferably not diffused to the insulator 520 side. In this way, reaction with the oxygen contained in the insulator 524 and the oxide 530 can be suppressed.

[0201] The insulator 522 may be, for example, aluminum oxide, hafnium oxide, or aluminum and hafnium oxide. Hafnium-containing oxides (hafnium aluminate), tantalum oxide, zirconium oxide, titanium Lead zirconate titanate (PZT), strontium titanate (SrTiO3), or (Ba Insulators including so-called high-k materials such as ,Sr)TiO3(BST) are used as single layers or stacked layers. As transistors become smaller and more highly integrated, the gate insulating layer Thinning the film can cause problems such as leakage current. Functions as a gate insulating film. By using a high-k material as the insulator, the transistor operation can be improved while maintaining the physical thickness. This makes it possible to reduce the gate potential during operation.

[0202] In particular, it has the function of suppressing the diffusion of impurities and oxygen (the oxygen is difficult to penetrate ) Uses an insulator containing oxide of one or both of aluminum and hafnium, which are insulating materials. It is recommended to use an oxide of aluminum, hafnium, or both as an insulator. Aluminum oxide, hafnium oxide, oxides containing aluminum and hafnium (hafnium It is preferable to use such a material for the insulator 522. When formed, the insulator 522 prevents oxygen from being released from the oxide 530 and prevents the transistor 500 from being damaged. It functions as a layer that suppresses the intrusion of impurities such as hydrogen from the surrounding area into the oxide 530.

[0203] Alternatively, for example, aluminum oxide, bismuth oxide, germanium oxide, etc. may be added to these insulators. Aluminum, niobium oxide, silicon oxide, titanium oxide, tungsten oxide, yttrium oxide, Zirconium oxide may be added to the insulator. Alternatively, these insulators may be nitrided. Silicon oxide, silicon oxynitride, or silicon nitride may be laminated on the edge.

[0204] In addition, the insulator 520 is preferably thermally stable. For example, silicon oxide and Silicon oxide nitride and silicon oxynitride are preferred because they are thermally stable. Combining the insulator with silicon oxide or silicon oxynitride provides thermally stable and It is possible to obtain a laminated insulator 520 with a high relative dielectric constant.

[0205] The insulators 520, 522, and 524 each have a laminated structure of two or more layers. In this case, the laminated structure is not limited to the same material, and may be made of different materials. A laminated structure may also be used.

[0206] In the transistor 500, an oxide semiconductor is added to an oxide 530 including a channel formation region. It is preferable to use a metal oxide that functions as the oxide 530. For example, In-M- Zn oxide (element M is aluminum, gallium, yttrium, copper, vanadium, beryllium, Sodium, boron, titanium, iron, nickel, germanium, zirconium, molybdenum, lambda Tungsten, cerium, neodymium, hafnium, tantalum, tungsten, or magnesium In particular, the oxide 53 The In-M-Zn oxide that can be used as the In-Zn oxide is CAAC-OS, The oxide 530 is preferably an In-Ga oxide, an I n-Zn oxide may also be used.

[0207] The metal oxide that functions as the channel forming region in the oxide 530 has a band gap It is preferable to use one having a value of 2 eV or more, preferably 2.5 eV or more. The off-state current of a transistor is reduced by using a metal oxide with a wide band gap. It is possible.

[0208] The oxide 530 has an oxide 530a under the oxide 530b. The diffusion of impurities from the structure formed below the oxide 530b can be suppressed. In addition, by having the oxide 530c on the oxide 530b, the oxide 530c can be formed. Therefore, the diffusion of impurities from the structure formed above into the oxide 530b can be suppressed. do.

[0209] The oxide 530 has a layered structure made of oxides with different atomic ratios of metal atoms. Specifically, in the metal oxide used for the oxide 530a, the constituent elements The atomic ratio of element M in the oxide 530b is the atomic ratio of element M in the metal oxide in the constituent elements. It is preferable that the atomic ratio of the metal oxide 530a is larger than that of the element M. In the metal oxide used for the oxide 530b, the atomic ratio of element M to In is It is preferable that the atomic ratio of element M to In is larger than that of element In. In the metal oxide used, the atomic ratio of In to the element M is It is preferable that the atomic ratio of In is larger than that of the element M in the metal oxide. The oxide 530c is a metal oxide that can be used for the oxide 530a or the oxide 530b. can be used.

[0210] In addition, the energy of the conduction band minimum of the oxide 530a and the oxide 530c is It is preferable that the energy of the oxide is higher than the conduction band minimum energy of the oxide. The electron affinity of oxide 530a and oxide 530c is smaller than the electron affinity of oxide 530b. is preferred.

[0211] Here, at the junctions of the oxide 530a, the oxide 530b, and the oxide 530c, The energy level of the lower band edge changes gradually. The energy levels of the conduction band minimum at the junction of 530b and oxide 530c are continuous. In order to achieve this, the oxide 530 a and the interface between oxide 530b and oxide 530c. It is preferable to reduce the defect level density of the resulting mixed layer.

[0212] Specifically, oxide 530a and oxide 530b, and oxide 530b and oxide 530c are By having a common element other than oxygen (as the main component), a mixed layer with a low defect level density is formed. For example, when the oxide 530b is an In-Ga-Zn oxide, the oxide 530a and oxide 530c are In-Ga-Zn oxide, Ga-Zn oxide, oxide Gallium or the like may be used.

[0213] At this time, the main path of the carriers is the oxide 530b. By configuring the oxide 530c as described above, the interface between the oxide 530a and the oxide 530b and the oxide The defect state density at the interface between the substrate 530b and the oxide 530c can be reduced. Therefore, the effect of interface scattering on carrier conduction is reduced, and the transistor 500 has a high On-current can be obtained.

[0214] On the oxide 530b, a conductor 542a serving as a source electrode and a drain electrode is formed. The conductor 542a and the conductor 542b are provided. Aluminum, chromium, copper, silver, gold, platinum, tantalum, nickel, titanium, molybdenum, ungsten, hafnium, vanadium, niobium, manganese, magnesium, zirconium , beryllium, indium, ruthenium, iridium, strontium, and lanthanum. The metal elements mentioned above, or alloys containing the above metal elements, or combinations of the above metal elements For example, tantalum nitride, titanium nitride, tungsten nitride, etc. Stainless steel, nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, oxide Ruthenium oxide, ruthenium nitride, oxides containing strontium and ruthenium, lanthanum and It is preferable to use an oxide containing nickel. In addition, tantalum nitride, titanium nitride, Nitrides containing titanium and aluminum, nitrides containing tantalum and aluminum, ruthenium oxide Ruthenium, ruthenium nitride, oxides containing strontium and ruthenium, lanthanum and nickel Oxides containing these are conductive materials that are resistant to oxidation, or materials that maintain their conductivity even when they absorb oxygen. This is preferable because it is a

[0215] As shown in FIG. 15A, the oxide 530 is formed of the conductor 542a (conductor 542b At the interface with the semiconductor layer 543 and in the vicinity thereof, a region 543a and a region 543b are formed as low resistance regions. In this case, the region 543a may be used as either a source region or a drain region. The region 543b functions as the other of the source region and the drain region. A channel forming region is formed in a region between 543a and region 543b.

[0216] By providing the conductor 542a (conductor 542b) so as to be in contact with the oxide 530, The oxygen concentration in the region 543a (region 543b) may decrease. The metal contained in the conductor 542a (conductor 542b) and the oxide 530 are In such a case, a metal compound layer containing the component may be formed in the region 543a (region The carrier concentration in the region 543a (region 543b) increases, and the region 543a (region 543b) becomes a low resistance region. become.

[0217] The insulator 544 is provided to cover the conductor 542a and the conductor 542b. At this time, the insulator 544 prevents the oxidation of the oxide 542a and the conductor 542b. 30 and may be provided in contact with the insulator 524 .

[0218] Insulator 544: hafnium, aluminum, gallium, yttrium, zirconium tungsten, titanium, tantalum, nickel, germanium, or magnesium A metal oxide containing one or more selected from the above can be used.

[0219] In particular, the insulator 544 may be made of oxide of either or both of aluminum and hafnium. Aluminum oxide, hafnium oxide, aluminum and hafnium are insulators containing It is preferable to use oxides containing hafnium (e.g., hafnium aluminate). Aluminate has higher heat resistance than hafnium oxide film. Therefore, it is possible to reduce the heat treatment time in the subsequent process. In theory, this is preferable because it is difficult to crystallize. In the case of a material that has oxidation resistance or whose conductivity does not decrease significantly even when it absorbs oxygen The insulator 544 is not an essential component. It can be appropriately designed according to the desired transistor characteristics. Good.

[0220] The insulator 550 functions as a gate insulating film. It is preferable that the insulator 550 is disposed so as to be in contact with the upper and side surfaces of the insulator 550. Like 524, it is made of an insulator that contains excess oxygen and releases oxygen when heated. It is preferable to form the

[0221] Specifically, silicon oxide having excess oxygen, silicon oxynitride, silicon nitride oxide, Silicon nitride, silicon oxide doped with fluorine, silicon oxide doped with carbon, carbon and Silicon oxide doped with nitrogen and silicon oxide having vacancies can be used. Silicon oxide and silicon oxynitride are preferred because they are stable to heat.

[0222] An insulator that releases oxygen when heated is used as the insulator 550, and is placed on the top surface of the oxide 530c. By providing the oxide 530b in contact with the insulator 550, the oxide 530b passes through the oxide 530c. In addition, oxygen can be effectively supplied to the channel formation region of the insulator 524. In particular, it is preferable that the concentration of impurities such as water or hydrogen in the insulator 550 is reduced. The thickness of the edge 550 is preferably 1 nm or more and 20 nm or less.

[0223] In addition, in order to efficiently supply excess oxygen contained in the insulator 550 to the oxide 530, A metal oxide may be provided between the insulator 550 and the conductor 560. The metal oxide serves as an insulating material. It is preferable to suppress the diffusion of oxygen from the body 550 to the conductor 560. By providing a metal oxide, the diffusion of excess oxygen from the insulator 550 to the conductor 560 is suppressed. In other words, the reduction in the amount of excess oxygen supplied to the oxide 530 can be suppressed. In addition, the oxidation of the conductor 560 due to excess oxygen can be suppressed. Any material that can be used for the insulator 544 may be used.

[0224] The conductor 560 functioning as the first gate electrode has a two-layer structure in FIGS. However, it may have a single layer structure or a laminated structure of three or more layers.

[0225] The conductor 560a is a hydrogen atom, a hydrogen molecule, a water molecule, a nitrogen atom, a nitrogen molecule, or a nitrogen oxide molecule. (N2O, NO, NO2, etc.), conductive material with the function of suppressing the diffusion of impurities such as copper atoms It is preferable to use a material containing oxygen (e.g., oxygen atoms, oxygen molecules, etc.) It is preferable to use a conductive material having a function of suppressing the diffusion of the conductive material 56. Since 0a has the function of suppressing oxygen diffusion, the oxygen contained in the insulator 550 Therefore, it is possible to prevent the conductor 560b from being oxidized and the conductivity from decreasing. Examples of conductive materials that have the function of suppressing the above include tantalum, tantalum nitride, and ruthenium. It is preferable to use ruthenium oxide or ruthenium oxide.

[0226] The conductor 560b is a conductive material mainly composed of tungsten, copper, or aluminum. In addition, since the conductor 560b also functions as wiring, It is preferable to use a conductor having high electrical conductivity. The conductor 560b may have a laminated structure. For example, a laminated structure of titanium, titanium nitride and the above-mentioned conductive material may be used.

[0227] The insulator 580 is provided on the conductor 542a and the conductor 542b via the insulator 544. Insulator 580 preferably has an excess oxygen region. For example, insulator 58 0, silicon oxide, silicon oxynitride, silicon nitride oxide, silicon nitride, fluorine Silicon oxide doped with , silicon oxide doped with carbon, silicon oxide doped with carbon and nitrogen It is preferable that the material contains silicon, silicon oxide having voids, or resin. Silicon oxide and silicon oxynitride are preferred because they are thermally stable. In addition, silicon oxide with vacancies can easily form excess oxygen regions in later processes. This is preferable because it is possible to

[0228] The insulator 580 having an excess oxygen region and from which oxygen is released by heating is treated with an oxide 530. By providing the insulator 580 in contact with the oxide 530c, the oxygen in the insulator 580 is transferred to the oxide 530c through the oxide 530c. The water in the insulator 580 can be efficiently supplied to the oxide 530a and the oxide 530b. Alternatively, it is preferable that the concentration of impurities such as hydrogen is reduced.

[0229] The opening of the insulator 580 is formed to overlap the region between the conductor 542a and the conductor 542b. As a result, the conductor 560 is inserted through the opening of the insulator 580 and the conductor 542a and the conductor 542b. It is formed so as to be embedded in the region sandwiched between 542b.

[0230] In miniaturizing semiconductor devices, it is necessary to shorten the gate length. It is necessary to prevent the conductivity of the conductor 60 from decreasing. In this embodiment, the conductor 560 may have a high aspect ratio. The conductor 560 is provided so as to be embedded in the opening of the insulator 580. Even if the shape has a high ratio, the conductor 560 can be formed without collapsing during the process. Cut.

[0231] The insulator 574 is disposed on the upper surface of the insulator 580, the upper surface of the conductor 560, and the upper surface of the insulator 550. The insulator 574 is preferably provided in contact with the insulating film 574 by sputtering. , insulator 550, and insulator 580 may be provided with excess oxygen regions. Oxygen can be provided into the oxide 530 from the excess oxygen region.

[0232] For example, the insulator 574 may be hafnium, aluminum, gallium, yttrium, Zirconium, tungsten, titanium, tantalum, nickel, germanium, or magnesium A metal oxide containing one or more metals selected from the group consisting of tungsten, cadmium, etc. can be used. .

[0233] In particular, aluminum oxide has high barrier properties and is a thin film with a thickness of 0.5 nm to 3.0 nm. Therefore, the diffusion of hydrogen and nitrogen can be suppressed even if the sputtering method is used. The aluminum oxide film formed by this method is a source of oxygen and also acts as a barrier against impurities such as hydrogen. It can also function as a membrane.

[0234] In addition, it is preferable to provide an insulator 581 functioning as an interlayer film over the insulator 574. The insulator 581, like the insulator 524, has a low impurity concentration, such as water or hydrogen, in the film. It is preferable that the amount of the ion exchange rate is reduced.

[0235] In addition, the openings formed in the insulators 581, 574, 580, and 544 Conductor 540a and conductor 540b are placed in the opening. The conductors 540a and 540b are disposed opposite each other with the conductor 560 in between. It has the same structure as conductor 546 and conductor 548 described later.

[0236] An insulator 582 is provided on the insulator 581. The insulator 582 is It is preferable to use a material that has a barrier property against the insulator 582. The insulator 582 may be made of the same material as the insulator 514. For example, the insulator 582 may be made of aluminum oxide. It is preferable to use metal oxides such as tungsten oxide, hafnium oxide, and tantalum oxide.

[0237] In particular, aluminum oxide is highly resistant to oxygen and hydrogen, which are factors that affect the electrical characteristics of transistors. The membrane has a high blocking effect, preventing both impurities such as oxygen and water from penetrating the membrane. Aluminum oxide is highly resistant to insufficient hydrogen, moisture, and other impurities during and after the transistor manufacturing process. It is possible to prevent the inclusion of impurities in the transistor 500. Therefore, the release of oxygen from the oxide constituting the transistor 5 can be suppressed. It is suitable for use as a protective film against 00.

[0238] Further, an insulator 586 is provided on the insulator 582. The insulator 586 is The same materials as those in 320 can be used. In addition, these insulators have relatively low dielectric constants. By using low-cost materials, the parasitic capacitance between wiring lines can be reduced. For example, As the insulator 586, a silicon oxide film, a silicon oxynitride film, or the like can be used.

[0239] In addition, the insulator 520, the insulator 522, the insulator 524, the insulator 544, the insulator 580, the insulator The edge 574, the insulator 581, the insulator 582, and the insulator 586 are provided with the conductor 546, Conductors 548 and the like are embedded.

[0240] The conductor 546 and the conductor 548 are the capacitor 600, the transistor 500, or the transistor The conductor 546 has a function as a plug or wiring for connecting to the transistor 300. The conductor 548 can be formed using a material similar to that of the conductor 328 and the conductor 330. Cut.

[0241] Next, a capacitor 600 is provided above the transistor 500. 600 includes a conductor 610, a conductor 620, and an insulator 630.

[0242] A conductor 612 may be provided over the conductor 546 and the conductor 548. Reference numeral 12 serves as a plug or wiring that is connected to the transistor 500. The conductor 610 functions as an electrode of the capacitor 600. The body 610 can be formed simultaneously.

[0243] The conductor 612 and the conductor 610 may be made of molybdenum, titanium, tantalum, or tungsten. a metal film containing an element selected from aluminum, copper, chromium, neodymium, and scandium; Or a metal nitride film containing the above-mentioned elements (tantalum nitride film, titanium nitride film, molybdenum nitride film, etc.) Alternatively, indium tin oxide, Indium oxide containing tungsten oxide, Indium zinc oxide containing tungsten oxide Indium oxide containing titanium oxide, indium tin oxide containing titanium oxide, indium Conductive materials such as indium zinc oxide and indium tin oxide doped with silicon oxide are used. It is also possible.

[0244] In FIG. 14, the conductor 612 and the conductor 610 are shown to have a single-layer structure. However, this is not limited to this structure. For example, a conductive material having a barrier property and a conductive material having a high conductivity may be used. Conductors that have barrier properties and have high adhesion to highly conductive conductors A thin conductor may be formed.

[0245] The conductor 620 is provided so as to overlap with the conductor 610 with the insulator 630 interposed therebetween. The conductor 620 is made of a conductive material such as a metal material, an alloy material, or a metal oxide material. High-melting-point materials such as tungsten and molybdenum, which have both heat resistance and electrical conductivity, are used. It is preferable to use tungsten, and it is particularly preferable to use tungsten. When forming the structure at the same time as other structures, low resistance metal materials such as Cu (copper) and Al (aluminum) are used. It is advisable to use a

[0246] An insulator 650 is provided on the conductor 620 and the insulator 630. The insulator 650 can be provided using a material similar to that of the insulator 320. It may also function as a planarizing film that covers the uneven shape underneath.

[0247] By using this structure, a semiconductor device using a transistor having an oxide semiconductor This can suppress the fluctuation of electrical characteristics and improve reliability. To achieve miniaturization or high integration in a semiconductor device using transistors having a compound semiconductor It is possible.

[0248] <Example of transistor structure> Note that the transistor 500 of the semiconductor device described in this embodiment is not limited to the above structure. The following describes examples of structures that can be used for the transistor 500. The transistors described below are modifications of the transistors described above. Therefore, in the following description, the differences will be mainly described, and the same points may be omitted.

[0249] <<Transistor structure example 1>> An example of a structure of a transistor 500A will be described with reference to FIGS. FIG. 16A is a top view of a transistor 500A. FIG. 16B is a top view of the transistor 500A shown in FIG. FIG 16(C) is a cross-sectional view of a portion indicated by a dashed line L1-L2 in FIG 16(A). 16A is a cross-sectional view of a portion indicated by a line W1-W2. For convenience, some elements are omitted in the figure.

[0250] 16A, 16B, and 16C, a transistor 500A and a semiconductor device that functions as an interlayer film are shown. Insulators 511, 512, 514, 516, 580, and 5 16(A), (B) and (C) show the conductor 74 and the insulator 581. A conductor 540a, a conductor 540b, and a In particular, conductor 540a and conductor 540b are contact plugs. The conductor 505 functions as wiring.

[0251] The transistor 500A includes a conductor 560 (conductor 56 0a and conductor 560b), and conductor 503 (conductor 503a and conductor 503b), and an insulator 550 functioning as a first gate insulating film. , an insulator 520, an insulator 522, and an insulator 524 functioning as a second gate insulating film; , an oxide 530 having a region in which a channel is to be formed (oxide 530a, oxide 530b, and oxide 530c), a conductor 542a functioning as one of a source or drain, It has a conductor 542b which functions as the other of the source or drain, and an insulator 544.

[0252] In addition, in the transistor 500A shown in FIGS. 0c, an insulator 550, and a conductor 560 are inserted into an opening in the insulator 580. The oxide 530c, the insulator 550, and the conductor 560 are disposed through the insulating layer 544. is disposed between conductor 542a and conductor 542b.

[0253] The insulators 511 and 512 function as interlayer films.

[0254] The interlayer film may be silicon oxide, silicon oxynitride, silicon nitride oxide, or aluminum oxide. , hafnium oxide, tantalum oxide, zirconium oxide, lead zirconate titanate (PZ T), strontium titanate (SrTiO3) or (Ba,Sr)TiO3 (BST) Insulators such as the above may be used in a single layer or a laminated layer. Aluminum oxide, bismuth oxide, germanium oxide, niobium oxide, silicon oxide, titanium oxide Tungsten, tungsten oxide, yttrium oxide, zirconium oxide may be added. These insulators may be nitrided. Alternatively, silicon nitride may be laminated.

[0255] For example, the insulator 511 prevents impurities such as water or hydrogen from entering the transistor 500 from the substrate side. It is preferable that the insulator functions as a barrier film to prevent the insulator from being mixed into A. 511 has the function of suppressing the diffusion of impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. It is preferable to use an insulating material that is impermeable to the above impurities. For example, it has a function of suppressing the diffusion of at least one of oxygen atoms, oxygen molecules, etc. (see above) It is preferable to use an insulating material that is difficult for oxygen to permeate. Aluminum oxide or silicon nitride may be used as the material 1. Impurities such as water are prevented from diffusing from the substrate side to the transistor 500A side by the insulator 511. It can be suppressed.

[0256] For example, it is preferable that the insulator 512 has a lower dielectric constant than the insulator 511. By using a material with a low dielectric constant for the interlayer film, the parasitic capacitance occurring between wirings can be reduced.

[0257] The conductor 505 is formed so as to be embedded in the insulator 512. The height of the upper surface of the conductor 505 can be made to be approximately the same as the height of the upper surface of the insulator 512. Although a single-layer structure is shown, the present invention is not limited to this. For example, The conductor 505 may have a multi-layer structure of two or more layers. It is preferable to use a conductive material having high conductivity, the main component of which is silicon, copper, or aluminum. stomach.

[0258] In the transistor 500A, the conductor 560 is a first gate (also called a top gate). The conductor 503 may function as a second gate (bottom gate). In this case, the electric potential applied to the conductor 503 may function as an electrode. By changing the potential of the transistor independently of the potential applied to the conductor 560, the transistor In particular, applying a negative potential to the conductor 503 can control the threshold voltage of the conductor 500A. By this, the threshold voltage of the transistor 500A is increased to be higher than 0 V, and the off-current is reduced. Therefore, applying a negative potential to the conductor 503 is more effective. The drain current when the potential applied to the conductor 560 is 0 V is made smaller than when there is no conductor. It is possible.

[0259] In addition, for example, by providing the conductor 503 and the conductor 560 in an overlapping state, the conductor 56 When a potential is applied to conductor 503, the electric field generated by conductor 560 and conductor 5 530 and the electric field generated by the junction 531 is connected to the electric field generated by the junction 531 and covers the channel forming region formed in the oxide 530. It is possible.

[0260] That is, the electric field of the conductor 560 functioning as the first gate electrode and the electric field of the conductor 560 functioning as the second gate electrode The electric field of the conductor 503, which functions as an electrode, electrically connects the channel formation region. In this specification, the electric field of the first gate electrode and the electric field of the second gate electrode The structure of a transistor in which the channel formation region is electrically surrounded by a field is called a surrou This is called the ned channel (S-channel) structure.

[0261] The insulators 514 and 516 are interlayer films, like the insulators 511 and 512. For example, the insulator 514 functions as a barrier against impurities such as water or hydrogen from the substrate side. It is preferable that the film functions as a barrier film that prevents the inclusion of the foreign matter in the transistor 500A. Due to the configuration, impurities such as hydrogen and water are introduced from the substrate side of the insulator 514 to the transistor 500. In addition, for example, the insulator 516 can suppress the diffusion of the insulator 51 It is preferable that the dielectric constant of the interlayer film is lower than that of the dielectric constant of 4. The parasitic capacitance occurring between lines can be reduced.

[0262] The conductor 503, which functions as a second gate, is disposed between the openings of the insulator 514 and the insulator 516. A conductor 503a is formed in contact with the inner wall, and a conductor 503b is formed further inside. Here, the height of the upper surfaces of the conductors 503a and 503b and the height of the upper surface of the insulator 516 are In the transistor 500A, the conductor 503a and the conductor 50 3b are stacked, the present invention is not limited to this. For example, the conductor 503 may be provided as a single layer or a laminated structure of three or more layers.

[0263] Here, the conductor 503a is a diffusion layer for impurities such as hydrogen atoms, hydrogen molecules, water molecules, and copper atoms. It is preferable to use a conductive material that has a function of suppressing the impurities (i.e., the impurities are less likely to permeate). Alternatively, the diffusion of oxygen (e.g., at least one of oxygen atoms, oxygen molecules, etc.) is suppressed. It is preferable to use a conductive material having the above-mentioned function (i.e., being difficult for oxygen to permeate). In this specification, the function of suppressing the diffusion of impurities or oxygen means the function of suppressing the diffusion of the above impurities or the above The function is to suppress the diffusion of any one or all of the oxygen.

[0264] For example, the conductor 503a has a function of suppressing the diffusion of oxygen, so that the conductor 503 It is possible to suppress the oxidation of b and the decrease in electrical conductivity.

[0265] In addition, when the conductor 503 also functions as a wiring, the conductor 503b is made of tungsten, copper, etc. It is preferable to use a conductive material having high conductivity, such as aluminum or aluminum-based material. In this case, the conductor 505 is not necessarily provided. Although shown in the figure, it may have a laminated structure, for example, titanium, titanium nitride and the above conductive material. It may also be a laminate.

[0266] The insulator 522 having a function as a second gate insulating film preferably has a barrier property. The insulator 522 has a barrier property, so that the transistor 500A can be prevented from being exposed to the periphery of the transistor 500A. It functions as a layer that suppresses the intrusion of impurities such as hydrogen into the transistor 500A.

[0267] In addition, in Fig. 16(B) and (C), a three-layer laminate structure is shown as the second gate insulating film. However, it may be a single layer, two layers, or a laminated structure of four or more layers. In that case, the layers must be made of the same material. The present invention is not limited to a laminated structure made of one material, but may be a laminated structure made of different materials.

[0268] The oxide 530 having a region that functions as a channel formation region is made up of an oxide 530a and an oxide 5, an oxide 530b is formed on the oxide 530a, and an oxide 530c is formed on the oxide 530b. By having the oxide 530a under the oxide 530b, the oxide 530a is formed below the oxide 530a. The diffusion of impurities from the structure to the oxide 530b can be suppressed. By having oxide 530c on object 530b, the oxide 530c is formed above the oxide 530c. The diffusion of impurities from the structure to the oxide 530b can be suppressed. As the insulating layer, an oxide semiconductor, which is one of the above-mentioned metal oxides, can be used.

[0269] The oxide 530c is formed in the opening of the insulator 580 through the insulator 544. When the insulator 544 has a barrier property, the insulator 580 is preferably provided. This can prevent impurities from diffusing into the oxide 530.

[0270] A conductor 542a serving as one of a source electrode and a drain electrode, The conductor 542b functioning as the other drain electrode is made of aluminum, titanium, chromium, or the like. , nickel, copper, yttrium, zirconium, molybdenum, silver, tantalum, or tungsten Metals such as stainless steel or alloys containing stainless steel as the main component can be used. Metal nitride films such as tantalum have barrier properties against hydrogen and oxygen and also have high oxidation resistance. Therefore, it is preferable.

[0271] Although a single-layer structure is shown in FIG. 16B, a laminated structure of two or more layers may be used. For example, a tantalum nitride film and a tungsten film may be laminated. Alternatively, a two-layer structure may be used in which an aluminum film is laminated on a tungsten film, or a copper film may be laminated on a copper layer. - Two-layer structure with copper film laminated on magnesium-aluminum alloy film, copper film laminated on titanium film Alternatively, a two-layer structure in which a copper film is laminated on a tungsten film may be used.

[0272] In addition, a titanium film or titanium nitride film and an aluminum film over the titanium film or titanium nitride film are A three-layer structure in which a titanium film or a copper film is laminated and a titanium film or a titanium nitride film is further formed on the aluminum film or a copper film. A molybdenum film or a molybdenum nitride film is formed on the molybdenum film or the molybdenum nitride film. An aluminum film or a copper film is laminated on top of it, and a molybdenum film or a molybdenum nitride film is further laminated on top of it. In addition, a transparent film containing indium oxide, tin oxide, or zinc oxide may be used. Transparent conductive materials may also be used.

[0273] A barrier layer may be provided over the conductor 542a and the conductor 542b. It is preferable to use a material having a barrier property against oxygen or hydrogen. As a result, when the insulator 544 is formed, the conductor 542a and the conductor 542b are oxidized. It is possible to suppress the above.

[0274] The barrier layer may be made of, for example, a metal oxide. In particular, aluminum oxide, Using insulating films with barrier properties against oxygen and hydrogen, such as hafnium oxide and gallium oxide. It is also preferable to use silicon nitride formed by a CVD method.

[0275] The barrier layer can be used to expand the range of materials that can be used for the conductor 542a and the conductor 542b. For example, the conductor 542a and the conductor 542b may be made of tungsten or alumina. Materials with low oxidation resistance but high electrical conductivity, such as aluminum, can be used. For example, a conductor that is easy to form or process can be used.

[0276] The insulator 550 functions as a first gate insulating film. In the opening formed in the insulating layer 530, an oxide 530c and an insulator 544 are provided. preferable.

[0277] As transistors become smaller and more highly integrated, the gate insulating film becomes thinner, causing leakage currents. In this case, the insulator 550 may become a second gate insulating film. Similarly, a laminated structure may be used. The insulator that functions as the gate insulating film may be a high-k material. By using a laminated structure of a material that is thermally stable and a material that is not thermally stable, the thickness of the material is maintained while the It is possible to reduce the gate potential during transistor operation. It may be a laminated structure.

[0278] The conductor 560 functioning as the first gate electrode includes a conductor 560a and a conductor 560b. The conductor 560a has a conductor 560b on a. The conductor 560a has a hydrogen atom, similar to the conductor 503a. The conductive material has the function of suppressing the diffusion of impurities such as hydrogen molecules, water molecules, and copper atoms. It is preferable that the oxygen (e.g., at least one of an oxygen atom, an oxygen molecule, etc.) It is preferable to use a conductive material that has a function of suppressing diffusion.

[0279] The conductor 560a has a function of suppressing the diffusion of oxygen, so that the material of the conductor 560b In other words, by having the conductor 560a, the conductor 560 The oxidation of b is suppressed, and the decrease in electrical conductivity can be prevented.

[0280] Examples of conductive materials that have the function of suppressing oxygen diffusion include tantalum and tantalum nitride. It is preferable to use ruthenium, ruthenium oxide, or the like. As a, an oxide semiconductor which can be used as the oxide 530 can be used. In this case, the conductor 560b is formed by sputtering, so that the electric It is possible to lower the resistance and make it a conductor. This is called OC (Oxide Conductor). The tor electrode can be called a

[0281] The conductor 560b is made of a conductive material mainly composed of tungsten, copper, or aluminum. In addition, since the conductor 560 functions as a wiring, it is preferable to use It is preferable to use a conductor. The conductor 560b may have a layered structure, for example. Alternatively, a laminate of titanium, titanium nitride and the above conductive material may be used.

[0282] An insulator 544 is disposed between the insulator 580 and the transistor 500A. 4 uses an insulating material that has the function of suppressing the diffusion of impurities such as water or hydrogen, and oxygen. For example, it is preferable to use aluminum oxide or hafnium oxide. In addition, other oxides such as magnesium oxide, gallium oxide, germanium oxide, and indium oxide are also available. ttrium oxide, zirconium oxide, lanthanum oxide, neodymium oxide or tantalum oxide Metal oxide, silicon nitride oxide, silicon nitride, or the like can be used.

[0283] By including the insulator 544, impurities such as water and hydrogen contained in the insulator 580 are converted into oxygen. The oxide 530c is prevented from diffusing into the oxide 530b through the insulator 550. In addition, the excess oxygen contained in the insulator 580 can suppress the oxidation of the conductor 560. It is possible.

[0284] The insulators 580, 574, and 581 function as interlayer films.

[0285] The insulator 574, like the insulator 514, prevents impurities such as water or hydrogen from entering the transistor from the outside. It is preferable that the insulating film functions as a barrier insulating film that prevents the inclusion of the oxide in the transistor 500A.

[0286] In addition, the insulators 580 and 581 are, like the insulator 516, longer than the insulator 574. By using a material with a low dielectric constant as the interlayer film, The resulting parasitic capacitance can be reduced.

[0287] The transistor 500A is embedded in an insulator 580, an insulator 574, and an insulator 581. Through plugs and wiring such as embedded conductors 540a and 540b, electrical connections to other structures are established. They may also be electrically connected.

[0288] The material of the conductor 540a and the conductor 540b is the same as that of the conductor 503. Conductive materials such as metal materials, alloy materials, metal nitride materials, or metal oxide materials are applied in a single layer or For example, tungsten and molybdenum, which have both heat resistance and electrical conductivity, can be used. It is preferable to use a high melting point material such as butene, or a low resistance material such as aluminum or copper. It is preferable to form the wiring from a conductive material. By using a low-resistance conductive material, the wiring resistance can be reduced. It is possible.

[0289] For example, the conductor 540a and the conductor 540b are, for example, hydrogen and oxygen. The compound of tantalum nitride, which is a conductor with barrier properties, and tungsten, which has high electrical conductivity, By using a layered structure, the conductivity of the wiring is maintained while preventing the diffusion of impurities from the outside. It can be suppressed.

[0290] By using the above structure, a transistor including an oxide semiconductor having a large on-state current can be provided. Alternatively, a semiconductor device having an oxide semiconductor with low off-state current can be provided. It is possible to provide a semiconductor device having a transistor. It is therefore possible to provide a semiconductor device having stable electrical characteristics and improved reliability. Cut.

[0291] <<Transistor structure example 2>> A structural example of the transistor 500B will be described with reference to FIGS. FIG. 17A is a top view of a transistor 500B. FIG. 17B is a top view of the transistor 500B shown in FIG. 17(C) is a cross-sectional view of a portion indicated by a dashed line L1-L2 in FIG. 17A is a cross-sectional view of a portion indicated by a line W1-W2. For convenience, some elements are omitted in the figure.

[0292] Transistor 500B is a modified version of transistor 500A. To avoid confusion, the following description will focus mainly on the differences from transistor 500A.

[0293] The transistor 500B includes a conductor 542a (conductor 542b), an oxide 530c, and The insulator 550 and the conductor 560 overlap each other. It is possible to provide a transistor with a high on-state current. can be provided.

[0294] The conductor 560 functioning as the first gate electrode includes a conductor 560a and a conductor 560b. The conductor 560a has a conductor 560b on a. The conductor 560a has a hydrogen atom, similar to the conductor 503a. The conductive material has the function of suppressing the diffusion of impurities such as hydrogen molecules, water molecules, and copper atoms. It is preferable that the oxygen (e.g., at least one of an oxygen atom, an oxygen molecule, etc.) It is preferable to use a conductive material that has a function of suppressing diffusion.

[0295] The conductor 560a has a function of suppressing the diffusion of oxygen, so that the material of the conductor 560b In other words, by having the conductor 560a, the conductor 560 The oxidation of b is suppressed, and the decrease in electrical conductivity can be prevented.

[0296] In addition, the upper surface and side surface of the conductor 560, the side surface of the insulator 550, and the side surface of the oxide 530c It is preferable to provide an insulator 544 so as to cover the above-mentioned. It is preferable to use an insulating material that has a function of suppressing the diffusion of impurities such as hydrogen and oxygen. For example, it is preferable to use aluminum oxide or hafnium oxide. For example, magnesium oxide, gallium oxide, germanium oxide, yttrium oxide , a metal oxide such as zirconium oxide, lanthanum oxide, neodymium oxide or tantalum oxide; Silicon oxynitride, silicon nitride, or the like can be used.

[0297] By providing the insulator 544, oxidation of the conductor 560 can be suppressed. By providing the insulator 544, impurities such as water and hydrogen contained in the insulator 580 can be prevented from being generated in the transistor. Therefore, diffusion to the star 500B can be suppressed.

[0298] The contact plug of the transistor 500B is connected to the contact plug of the transistor 500A. The structure of the contact plug in the transistor 500B is different from that of the contact plug in the transistor 500A. Between the conductor 546a (conductor 546b) that functions as a barrier and the insulator 580, An insulator 576a (insulator 576b) is disposed. By providing the insulating layer 580, oxygen in the insulating layer 580 reacts with the conductor 546, and the conductor 546 is oxidized. This can prevent the above from happening.

[0299] In addition, by providing an insulator 576a (insulator 576b) having a barrier property, The range of materials that can be used for the wiring can be expanded. For example, the conductor 546a (Conductor 546b) is made of a metal material that has the property of absorbing oxygen while being highly conductive. By using tungsten, a semiconductor device with low power consumption can be provided. Alternatively, a material having low oxidation resistance but high conductivity, such as aluminum, can be used. Furthermore, for example, a conductor that is easy to form a film or process can be used.

[0300] <<Transistor structure example 3>> An example of a structure of a transistor 500C will be described with reference to FIGS. FIG. 18A is a top view of a transistor 500C. FIG. 18B is a top view of the transistor 500C shown in FIG. FIG 18(C) is a cross-sectional view of a portion indicated by a dashed line L1-L2 in FIG 18(A). 18(A) is a cross-sectional view of a portion indicated by a line W1-W2. For convenience, some elements are omitted in the figure.

[0301] Transistor 500C is a modified version of transistor 500A. To avoid confusion, the following description will focus mainly on the differences from transistor 500A.

[0302] The transistor 500C shown in FIGS. 18A, 18B, and 18C includes a conductor 542a and an oxide. A conductor 547a is disposed between the conductor 542b and the oxide 530b. The conductor 547b is disposed. Here, the conductor 542a (conductor 542b) is a conductive The oxide layer 547a (conductor 547b) extends beyond the top surface of the conductor 547a (conductor 547b) and the side surface of the conductor 560. The conductor 547a and the conductor 547b have a region in contact with the upper surface of the conductor 530b. Any conductor that can be used for the conductor 542a and the conductor 542b may be used. Furthermore, the film thickness of the conductor 547a and the conductor 547b is at least as thick as the conductors 542a and It is preferably thicker than conductor 542b.

[0303] The transistor 500C shown in FIGS. 18A, 18B, and 18C has the above-described structure. By having the above, the conductor 542a and the conductor 542b can be formed more efficiently than the transistor 500A. The end of the conductor 542a and the end of the conductor 542a can be brought close to the conductor 560. The end of b can be overlapped with the conductor 560. This allows the transistor 500C It is possible to shorten the effective channel length, improve the on-current and improve the frequency characteristics. Cut.

[0304] In addition, the conductor 547a (conductor 547b) overlaps with the conductor 542a (conductor 542b). It is preferable that the conductor 540a (conductive In the etching to form the opening in which the conductor 547a (conductor 540b) is embedded, 47b) acts as a stopper to prevent oxide 530b from being over-etched. It is possible.

[0305] In addition, the transistor 500C shown in FIGS. The insulator 544 may be water or Impurities such as hydrogen and excess oxygen may enter the transistor 500C from the insulator 580 side. It is preferable that the insulator 545 functions as a barrier insulating film that suppresses the insulator from being broken down. The insulator that can be used for the insulator 544 can be used. Examples of the nitride include aluminum nitride, aluminum titanium nitride, titanium nitride, and silicon nitride. Alternatively, a nitride insulator such as silicon oxynitride may be used.

[0306] In addition, the transistor 500C shown in FIGS. 18A, 18B, and 18C has the same structure as that shown in FIG. Unlike the transistor 500A shown in (B) and (C), the conductor 503 is set to have a single-layer structure. In this case, an insulating layer, which becomes an insulator 516, may be formed on the patterned conductor 503. A film is formed, and the upper part of the insulating film is removed by a CMP method or the like until the upper surface of the conductor 503 is exposed. Here, it is preferable to improve the flatness of the upper surface of the conductor 503. For example, the average surface roughness (Ra) of the upper surface of the conductor 503 is set to 1 nm or less, preferably 0.5 nm or less. The thickness of the conductive layer 503 is preferably 0.3 nm or less. The planarity of the insulating layer formed is improved, and the crystallinity of the oxide 530b and the oxide 530c is improved. It is possible to aim higher.

[0307] <<Transistor structure example 4>> An example of a structure of a transistor 500D will be described with reference to FIGS. FIG. 19A is a top view of a transistor 500D. 19(C) is a cross-sectional view of a portion indicated by a dashed line L1-L2 in FIG. 19(A) is a cross-sectional view of a portion indicated by a line W1-W2. For convenience, some elements are omitted in the figure.

[0308] The transistor 500D is a transistor 500A, a transistor 500B, a transistor The structure is different from that of the 500C. Therefore, to avoid repetition, the explanation will be mainly The contents of Transistor 500A, Transistor 500B, and Transistor 500C overlap. A detailed description of these will be omitted and only the differences will be described.

[0309] The transistor 500D shown in FIGS. 19A to 19C is the same as that shown in FIGS. As in the transistor 500C shown in FIG. 5C, the conductor 505 is not provided, and the second gate and The conductor 503 also functions as a wiring. The insulating layer 550 is disposed on the insulating layer 550, and the metal oxide layer 552 is disposed on the insulating layer 550. A conductor 560 is provided on the object 552, and an insulator 570 is provided on the conductor 560. An insulator 571 is provided on the body 570 .

[0310] The metal oxide 552 preferably has a function of suppressing oxygen diffusion. By providing a metal oxide 552 between the conductor 560 and the conductive material 560, which suppresses the diffusion of oxygen, The diffusion of oxygen into the dielectric 560 is suppressed. In other words, the amount of oxygen supplied to the oxide 530 is reduced. In addition, the oxidation of the conductor 560 due to oxygen can be suppressed. .

[0311] Note that the metal oxide 552 may function as a part of the first gate. For example, The oxide semiconductor that can be used as the oxide 530 is used as the metal oxide 552. In this case, the conductor 560 can be formed by sputtering to form a metal oxide film. The electrical resistance of the oxide 552 can be reduced to make it a conductive layer. The electrode can be called an e Conductor.

[0312] The metal oxide 552 may function as a part of the gate insulating film. Therefore, when silicon oxide or silicon oxynitride is used for the insulator 550, the metal oxide The material 552 is preferably a metal oxide, which is a high-k material having a high dielectric constant. This laminated structure is stable against heat and has a high dielectric constant. Therefore, the gate voltage applied during transistor operation can be adjusted while maintaining the physical film thickness. In addition, the equivalent oxide thickness ( It is possible to reduce the thickness of the EOT.

[0313] In the transistor 500D, the metal oxide 552 is illustrated as a single layer. For example, a metal oxide that functions as a part of the gate electrode and a gate insulating film may be used. A metal oxide that functions as a part of the film may be laminated thereon.

[0314] When the metal oxide 552 functions as a gate electrode, It is possible to improve the on-state current of transistor 500D without weakening the effect of the electric field from Alternatively, when it functions as a gate insulating film, the insulator 550 and the metal oxide 552 The physical thickness of the oxide 530 and the conductor 560 maintains a distance between the oxide 530 and the conductor 560. The leakage current between the insulator 560 and the oxide 530 can be suppressed. By providing a stacked structure of the conductor 560 and the oxide 53, 0 and the electric field strength applied from the conductor 560 to the oxide 530. can be appropriately adjusted.

[0315] Specifically, the resistance of an oxide semiconductor that can be used for the oxide 530 is reduced. Metal oxide 552 can be used. Alternatively, hafnium, aluminum, gallium, Aluminum, Yttrium, Zirconium, Tungsten, Titanium, Tantalum, Nickel, Germanium Metal oxide containing one or more metals selected from the group consisting of nium, magnesium, etc. can be used.

[0316] In particular, the oxide is an insulating layer containing one or both of aluminum and hafnium oxides. Aluminum oxide, hafnium oxide, oxides containing aluminum and hafnium (hafnium It is preferable to use hafnium aluminate. In particular, hafnium aluminate is an oxide. It has higher heat resistance than hafnium film. Therefore, it does not crystallize during the heat treatment in the later process. It is preferable that the metal oxide 552 is not an essential component. The design should be appropriate depending on the starter characteristics.

[0317] The insulator 570 is an insulating material having a function of suppressing the permeation of impurities such as water or hydrogen, and oxygen. It is advisable to use insulating materials such as aluminum oxide or hafnium oxide. This prevents the conductor 560 from being oxidized by oxygen from above the insulator 570. In addition, it is possible to prevent impurities such as water or hydrogen from entering from above the insulator 570. Impurities are prevented from being mixed into the oxide 530 through the conductor 560 and the insulator 550. It is possible.

[0318] The insulator 571 functions as a hard mask. When processing 60, the side of the conductor 560 is approximately vertical. The angle of the plate surface is set to 75 degrees or more and 100 degrees or less, preferably 80 degrees or more and 95 degrees or less. This can be done.

[0319] The insulator 571 has a function of suppressing the permeation of impurities such as water or hydrogen, and oxygen. By using an insulating material having the above-mentioned properties, the insulating layer may also function as a barrier layer. The insulator 570 is not necessarily provided.

[0320] Using the insulator 571 as a hard mask, the insulator 570, the conductor 560, and the metal oxide 552, insulator 550, and oxide 530c are selectively removed to remove these The sides can be made roughly flush and part of the oxide 530b surface can be exposed.

[0321] Transistor 500D also has regions 531a and 531b on the exposed oxide 530b surface. One of the regions 531a and 531b functions as a source region. The other serves as a drain region.

[0322] The regions 531a and 531b are formed by, for example, an ion implantation method or an ion doping method. , plasma immersion ion implantation, or plasma treatment to remove the exposed oxide. This can be achieved by introducing impurity elements such as phosphorus or boron into the surface of 530b. In the embodiments and the like, the term "impurity elements" refers to elements other than the main component elements.

[0323] In addition, after exposing a part of the surface of the oxide 530b, a metal film is formed and then heat-treated. By this, the elements contained in the metal film are diffused into the oxide 530b, forming the regions 531a and Region 531b may also be formed.

[0324] The region of the oxide 530b into which the impurity element is introduced has a reduced electrical resistivity. The regions 531a and 531b may be referred to as "impurity regions" or "low-resistance regions".

[0325] By using the insulator 571 and / or the conductor 560 as a mask, the regions 531a and The region 531b can be formed in a self-aligned manner. The region 531a and / or the region 531b do not overlap with the conductor 560, thereby reducing parasitic capacitance. In addition, the channel forming region and the source / drain region (region 531a or region 53 1b), no offset region is formed between the regions 531a and 531b. By forming it in a self-aligned manner, the on-current is increased and the threshold voltage is reduced. , and improve the operating frequency.

[0326] In order to further reduce the off-state current, an off-type MOSFET is placed between the channel formation region and the source / drain region. An offset region may be provided. The offset region is a region having a high electrical resistivity. The offset region is a region where the dopant element is not introduced. This can be achieved by introducing the above-mentioned impurity element after the formation of the insulator 5. The insulating layer 75 functions as a mask in the same manner as the insulating layer 571. Impurity elements are not introduced into the region overlapping with the body 575, and the electrical resistivity of the region remains high. It is possible.

[0327] The transistor 500D also includes an insulator 570, a conductor 560, a metal oxide 552, and an insulator 570. The insulator 575 is disposed on the side of the insulator 550 and the oxide 530c. It is preferable to use an insulator with a low dielectric constant. For example, silicon oxide, silicon oxynitride, or nitride. Silicon oxide, silicon nitride, silicon oxide with fluorine, silicon oxide with carbon Silicon, carbon and nitrogen doped silicon oxide, porous silicon oxide, or resin In particular, silicon oxide, silicon oxynitride, and silicon nitride oxide are preferable. When silicon oxide having voids is used for the insulator 575, the insulator 575 is filled with voids in a later process. This is preferable because an oxygen excess region can be easily formed. The insulator 575 is preferably made of a material having thermal stability. It is preferable to do so.

[0328] Transistor 500D also includes insulator 575 and insulator 544 on oxide 530. The insulator 544 is preferably formed by a sputtering method. By using this method, it is possible to form an insulator film with few impurities such as water or hydrogen. For example, the insulator 544 may be made of aluminum oxide.

[0329] The oxide film formed by the sputtering method extracts hydrogen from the film-forming structure. Therefore, the insulator 544 may separate the hydrogen and water from the oxide 530 and the insulator 575. The absorption can reduce the hydrogen concentration in the oxide 530 and the insulator 575.

[0330] <<Transistor structure example 5>> A structural example of the transistor 500E will be described with reference to FIGS. FIG. 20(A) is a top view of a transistor 500E. FIG. 20(B) is a top view of a transistor 500E. FIG 20(C) is a cross-sectional view of the portion indicated by the dashed line L1-L2 in FIG 20(A). It is to be noted that in the top view of FIG. 20(A), the cross-sectional view of the portion indicated by W1-W2 is omitted for clarity of the drawing. For this reason, some elements are omitted in the illustration.

[0331] The transistor 500E is a transistor 500A, a transistor 500B, a transistor 500C and transistor 500D have different structures. To prevent this, transistors 500A, 500B, and 500C are In this embodiment, the description of the transistor 500D will be omitted, and the main differences will be described. I will explain this in more detail.

[0332] In FIGS. 20A, 20B, and 20C, a conductor 542a and a conductor 542b are provided. The exposed oxide 530b surface has regions 531a and 531b. One of the regions 531a and 531b functions as a source region, and the other functions as a drain region. In addition, an insulator 573 is provided between the oxide 530b and the insulator 544.

[0333] In the region 531a and the region 531b shown in FIG. 20B, the oxide 530b is added with the following element: The regions 531a and 531b are regions where, for example, dummy gates are formed. It can be formed by using

[0334] Specifically, a dummy gate is provided on the oxide 530b, and the dummy gate is used as a mask to It is preferable to use the oxide 530b as a thin film and add an element that reduces the resistance of a part of the oxide 530b. The element is added to the region of the oxide 530a and the region of the oxide 530b that do not overlap with the dummy gate. The element is added to form the regions 531a and 531b. The ion implantation method uses mass-separated ionized source gas for injection, and the ionized source Plasma immersion ion impingement is an ion doping method that adds gas without mass separation. The oration method can be used.

[0335] In addition, a representative example of an element that reduces the resistance of a portion of the oxide 530b is boron. Also, hydrogen, carbon, nitrogen, fluorine, sulfur, chlorine, titanium, rare gas, etc. Representative examples of rare gases include helium, neon, argon, crypto The concentration of the elements is measured by secondary ion mass spectrometry (SIMS:Se Condary Ion Mass Spectrometry (CIMMS) is used to measure the Good.

[0336] In particular, Si transistors that contain amorphous silicon or low-temperature polysilicon in the semiconductor layer Boron and phosphorus can be added in the equipment of the DIS production line, By using the equipment of the manufacturing line, it is possible to reduce the resistance of a part of the oxide 530b. In other words, part of the manufacturing line for Si transistors is being used for the manufacturing process of transistor 500E. can be used.

[0337] Next, an insulating film that will become an insulator 573 and an insulating film are formed on the oxide 530b and the dummy gate. An insulating film that becomes the insulator 544 may be formed. 4 is laminated, the region 531a or the region 531b and the oxide 53 There may be an overlapping region between 0c and the insulator 550.

[0338] Specifically, after forming an insulating film that will become the insulator 580 on the insulating film that will become the insulator 544, The insulating film that will become the insulating film 580 is CMP (Chemical Mechanical Polishing). By performing a dummy gate insulating film (580) etching process, a part of the insulating film that will become the insulator 580 is removed. When the dummy gate is subsequently removed, the insulator 57 in contact with the dummy gate is removed. Therefore, the side of the opening in the insulator 580 is covered with the insulating material. The insulating body 544 and the insulating body 573 are exposed, and the insulating body 544 and the insulating body 573 are exposed at the bottom of the opening. Next, a part of each of the exposed regions 531a and 531b is exposed through the opening. The oxide film which becomes the oxide 530c, the insulating film which becomes the insulator 550, and the conductive film which becomes the conductor 560 are After the films are formed in order, the oxide 530 is removed by a CMP process or the like until the insulator 580 is exposed. c, the insulating film which becomes the insulator 550, and a part of the conductive film which becomes the conductor 560. By removing the insulating layer, the transistors shown in FIGS. 20(A), (B), and (C) can be formed. can.

[0339] Note that the insulator 573 and the insulator 544 are not essential components. The design should be appropriate depending on the requirements.

[0340] The transistors shown in FIGS. 20A, 20B, and 20C include a conductor 542a and a conductor Since the body 542b is not provided, the cost for manufacturing the transistor can be reduced. can be done.

[0341] <<Transistor structure example 6>> In addition, in FIG. 15(A)(B), the conductor 560 that functions as a gate is an insulating The structure formed inside the opening of the conductive body 580 has been described. A structure in which the insulator is provided above such a transistor can also be used. Examples of the structure are shown in Figures 21(A) and 21(B) and Figures 22(A) and 22(B).

[0342] FIG. 21(A) is a top view of a transistor, and FIG. 21(B) is a perspective view of the transistor. A cross-sectional view of L1-L2 in FIG. 21(A) is shown in FIG. 22(A), and A cross-sectional view of 2 is shown in FIG.

[0343] The transistors shown in FIGS. 21(A) and 21(B) and 22(A) and 22(B) have a back gate. The BGE is a conductor having the function of a gate insulating film, the BGI is an insulator having the function of a gate insulating film, and the a gate insulating film FGI; and a front gate. A conductor FGE having a function as a wiring, and a conductor WE having a function as a wiring. In addition, the conductor PE is a mixture of the conductor WE, the oxide S, the conductor BGE, or the conductor FGE, In this embodiment, the oxide semiconductor S has a function as a plug for connecting the 1 shows an example consisting of oxide layers S1, S2 and S3.

[0344] Note that this embodiment mode can be appropriately combined with other embodiment modes shown in this specification. do.

[0345] (Embodiment 4) In this embodiment, the present invention can be applied to the OS transistor described in the above embodiment. Cloud-Aligned Composite Silicon-Oxide (CAC-OS) Oxide Semiconductor), and CAAC-OS(c-axis Al The structure of the ignited Crystalline Oxide Semiconductor In the specification, CAC is used as an example of the function or material structure. and CAAC represents an example of a crystal structure.

[0346] <Metal oxide composition> CAC-OS or CAC-metal oxide is a material that has a conductive function in some parts. A part of the material has an insulating function, and the whole material has a semiconductor function. In addition, CAC-OS or CAC-metal oxide is used as the active layer of a transistor. When used in a material, the function of conductivity is to allow electrons (or holes) to flow as carriers, and The insulating function is the function of preventing the flow of electrons that act as carriers. By making the two functions work in a complementary manner, a switching function (On / Off) is realized. The function of providing a CAC-OS or CAC-metal oxide with a In CAC-OS or CAC-metal oxide, the functions are separated. By combining them, the functions of both can be maximized.

[0347] In addition, CAC-OS or CAC-metal oxide has a conductive region and an insulating region. The conductive region has the above-mentioned conductive function, and the insulating region has the above-mentioned insulating function. In addition, the conductive and insulating regions in the material are formed at the nanoparticle level. In addition, the conductive and insulating regions may be separated by a metal. In addition, the conductive area may be observed as a cloud-like connected area with a blurred periphery. There may be cases where this occurs.

[0348] In addition, in the CAC-OS or CAC-metal oxide, a conductive region and an insulating region are The peripheral region is 0.5 nm to 10 nm, preferably 0.5 nm to 3 nm. The following sizes may be present in the material:

[0349] In addition, CAC-OS and CAC-metal oxide have different band gaps. For example, CAC-OS or CAC-metal oxide e is a component with a wide gap due to the insulating region and a component with a narrow gap due to the conductive region. In the case of this configuration, when a carrier is caused to flow, In the component with a narrow gap, carriers mainly flow. The component having a narrow gap acts complementary to the component having a wide gap. In conjunction with the component, carriers also flow to the component with a wide gap. C-OS or CAC-metal oxide is used for the channel formation region of a transistor. In this case, the transistor has a high current driving capability in the on-state, i.e., a large on-current, and High field effect mobility can be obtained.

[0350] That is, CAC-OS or CAC-metal oxide is a matrix composite material. (matrix composite), or metal matrix composite It can also be called atrix composite.

[0351] <Metal oxide structure> Oxide semiconductors can be divided into single-crystal oxide semiconductors and other non-single-crystal oxide semiconductors. As a non-single-crystal oxide semiconductor, for example, CAAC-OS (c-axis all-crystalline oxide semiconductor) igned crystalline oxide semiconductor), Crystalline oxide semiconductor, nc-OS (nanocrystalline oxide semiconductor) iconductor), pseudo-amorphous oxide semiconductor (a-like OS:amorph crystalline-like oxide semiconductor and amorphous oxide semiconductor etc.

[0352] CAAC-OS has a c-axis orientation and multiple nanocrystals are connected in the ab-plane direction. The nanocrystals are connected together to form a distorted crystal structure. In a region, a lattice arrangement is formed between a region having a uniform lattice arrangement and another region having a uniform lattice arrangement. This refers to the point where the direction of the

[0353] Nanocrystals are basically hexagonal, but are not limited to regular hexagons and may have non-regular hexagonal shapes. In addition, the distortion may have a lattice arrangement such as a pentagon or a heptagon. In addition, in the CAAC-OS, clear grain boundaries (grain boundaries) are not observed even in the vicinity of the strain. In other words, the grain boundaries are not observed due to the distortion of the lattice arrangement. This is because the CAAC-OS has a high lattice constant in the ab-plane direction. The oxygen atoms are not densely packed, and the bond distance between atoms changes due to the substitution of metal elements. This is believed to be because distortion can be tolerated by, for example, adjusting the thickness of the optical fiber.

[0354] In addition, the CAAC-OS has a layer containing indium and oxygen (hereinafter, referred to as an In layer) and an element A layered crystal structure in which layers containing M, zinc, and oxygen (hereinafter, (M,Zn) layers) are stacked. (also called layered structure). Indium and element M are mutually substitutable. When the element M in the (M,Zn) layer is replaced with indium, the (In,M,Zn) layer Also, when the indium in the In layer is replaced with element M, (In,M) It can also be expressed as a layer.

[0355] CAAC-OS is a highly crystalline oxide semiconductor. Since it is not possible to confirm the grain boundaries, the decrease in electron mobility caused by the grain boundaries occurs. In addition, the crystallinity of oxide semiconductors can be easily affected by impurities and defects. Therefore, CAAC-OS is an oxidized material with few impurities and defects (oxygen vacancies, etc.). Therefore, oxide semiconductors with CAAC-OS have stable physical properties. Therefore, oxide semiconductors having CAAC-OS are resistant to heat and have high reliability. In addition, CAAC-OS is designed to withstand the high temperatures (so-called thermal budget) in the manufacturing process. Therefore, when CAAC-OS is used for an OS transistor, This allows for greater freedom.

[0356] nc-OS is a material that is used in microscopic regions (e.g., regions between 1 nm and 10 nm, especially regions between 1 nm and The atomic arrangement has periodicity in the region of 3 nm or less. There is no regularity in the crystal orientation between the crystals. Therefore, no orientation is observed throughout the film. Therefore, depending on the analysis method, nc-OS may be classified as a-like OS or amorphous oxide semiconductor. Sometimes it is indistinguishable from the body.

[0357] The a-like OS is an oxide semiconductor that has a structure between the nc-OS and the amorphous oxide semiconductor. A-like OS is a semiconductor. It has voids or low density regions. The OS has a lower crystallinity than the nc-OS and CAAC-OS.

[0358] The oxide semiconductor has various structures and has different characteristics. The oxide semiconductors in The compound may have two or more of c-OS and CAAC-OS.

[0359] <Transistor Having Oxide Semiconductor> Next, the case where the oxide semiconductor is used for a transistor will be described.

[0360] By using the oxide semiconductor for a transistor, a transistor with high field-effect mobility can be obtained. In addition, a highly reliable transistor can be realized.

[0361] In addition, the transistor is preferably formed using an oxide semiconductor with a low carrier concentration. In the case of decreasing the carrier concentration of the oxide semiconductor film, the impurity concentration in the oxide semiconductor film is In the present specification and the like, the impurity concentration is low, and the defect level density is low. A low density of defect states is called high purity intrinsic or substantially high purity intrinsic. A conductor has a carrier concentration of 8×10 11 cm -3 Less than 1 x 10 11 cm -3 Not yet More preferably, 1×10 10 cm -3 Less than 1 x 10-9 cm -3 That's all. That's good.

[0362] In addition, a highly purified intrinsic or substantially highly purified intrinsic oxide semiconductor film has a low density of defect states. Therefore, the trap state density may be low.

[0363] In addition, the time required for the charge trapped in the trap level of the oxide semiconductor to disappear is Therefore, the trap level density is high. A transistor in which a channel formation region is formed in an oxide semiconductor has unstable electrical characteristics. There may be cases where this occurs.

[0364] Therefore, in order to stabilize the electrical characteristics of a transistor, the impurity concentration in the oxide semiconductor In order to reduce the impurity concentration in the oxide semiconductor, It is preferable to reduce the impurity concentration in the adjacent film. These include alkali metals, alkaline earth metals, iron, nickel, and silicon.

[0365] <Impurities> Here, the influence of each impurity in an oxide semiconductor will be described.

[0366] When oxide semiconductors contain silicon or carbon, which is one of the group 14 elements, they become oxidized. Defect levels are formed in oxide semiconductors. The concentration of silicon and carbon near the interface with the oxide semiconductor (secondary ion mass spectrometry) (SIMS: Secondary Ion Mass Spectrometry) The concentration that can be obtained is 2 x 10 18 atoms / cm 3 Less than or equal to 2×1017 a toms / cm 3 The following applies.

[0367] In addition, when an oxide semiconductor contains an alkali metal or an alkaline earth metal, a defect level is formed. Therefore, when alkali metals or alkaline earth metals are included, Transistors using oxide semiconductors, which are widely used in semiconductor manufacturing, tend to be normally on. Therefore, it is preferable to reduce the concentration of the alkali metal or alkaline earth metal in the oxide semiconductor. Specifically, the alkali metal or alkali metal in the oxide semiconductor obtained by SIMS The concentration of earth metals is 1×10 18 atoms / cm 3 Less than or equal to 2×10 16 at oms / cm 3 To the following:

[0368] In addition, when nitrogen is contained in an oxide semiconductor, electrons that serve as carriers are generated, and As a result, the nitrogen-containing oxide semiconductor is easily converted to n-type. Therefore, the transistor used in the oxide semiconductor In this case, it is preferable that the nitrogen content is reduced as much as possible. For example, the nitrogen content in the oxide semiconductor is The concentration is 5×10 19 atoms / cm 3 Less than 5 x 10 18 atoms / cm 3 Less than or equal to 1×10 18 atoms / cm 3 Below, More preferably 5×10 17 atoms / cm 3 The following applies.

[0369] In addition, hydrogen contained in oxide semiconductors reacts with oxygen that bonds with metal atoms to form water. When hydrogen enters the oxygen vacancy, the carrier, In some cases, hydrogen atoms are formed by bonding with oxygen atoms that bond with metal atoms. Therefore, it is necessary to use an oxide semiconductor that contains hydrogen. Therefore, the hydrogen in the oxide semiconductor tends to cause a transistor to be normally on. It is preferable that the Si content in the oxide semiconductor is as low as possible. The hydrogen concentration obtained by MS is 1×10 20 atoms / cm 3 Less than 1x, preferably 10 19 atoms / cm 3 less than 5×10 18 atoms / cm 3 less than , and more preferably 1×10 18 atoms / cm 3 Less than.

[0370] By using an oxide semiconductor in which impurities are sufficiently reduced for a channel formation region of a transistor, This makes it possible to impart stable electrical characteristics.

[0371] Note that this embodiment mode can be appropriately combined with other embodiment modes shown in this specification. do.

[0372] (Embodiment 5) In this embodiment, a product in which the semiconductor device described in the above embodiment is applied to an electronic device is provided. An example will be described.

[0373] <Notebook type personal computer> The semiconductor device according to one embodiment of the present invention can be applied to a display included in an information terminal device. FIG. 23(A) shows a notebook type personal computer, which is a type of information terminal device. The device includes a housing 5401, a display unit 5402, a keyboard 5403, a pointing device It has the 5404 etc.

[0374] <Smartwatch> The semiconductor device of one embodiment of the present invention can be applied to a wearable terminal. B) is a smart watch, which is a type of wearable terminal, and includes a housing 5901, a display unit 5 902, operation buttons 5903, operators 5904, bands 5905, etc. The display unit 5902 may be a display device having a position input function. In addition, the function as a position input device can be added by providing a touch panel to the display device. Alternatively, the function as a position input device can be called a photosensor. It can also be added by providing a photoelectric conversion element in the pixel portion of the display device. Button 5903 is the power switch to start the smartwatch, the smartwatch app Buttons for operating the application, volume control buttons, or turning on or off the display unit 5902 In addition, the smart switch shown in FIG. In the smart watch, the number of operation buttons 5903 is two. The number of operation buttons to be operated is not limited to this. The operator 5904 also functions as a crown for adjusting the time on the watch. In addition, it can be used as an input interface to operate smartwatch applications. In addition, in the smart watch shown in FIG. 23(B), the operation button 59 However, the present invention is not limited to this, and may be configured without the operation element 5904. It's fine.

[0375] <Video camera> The semiconductor device of one embodiment of the present invention can be applied to a video camera. The video camera shown in FIG. 5 includes a first housing 5801, a second housing 5802, a display unit 5803, and an operation key. The operation keys 5804 and the lens 5805 are connected to the connector 5806. 5805 is provided in a first housing 5801, and a display unit 5803 is provided in a second housing 5802. The first housing 5801 and the second housing 5802 are connected to each other by a connection portion 5806. The angle between the first housing 5801 and the second housing 5802 is 5806. The image on the display unit 5803 can be changed by the first It may be configured to switch according to the angle between the housing 5801 and the second housing 5802.

[0376] <Mobile phone> The semiconductor device of one embodiment of the present invention can be applied to a mobile phone. This is a mobile phone having an information terminal function, and includes a housing 5501, a display unit 5502, and a microphone 550. 3, a speaker 5504, and an operation button 5505. A display device having a function as a position input device may be used. The function of the display device can be added by providing a touch panel. The function of the position input device is to use a photoelectric conversion element, also called a photosensor, on the display device. It can also be added by providing the operation button 5505 in the pixel portion of the mobile phone. A power switch to start a conversation, buttons to operate mobile phone applications, and volume control buttons The display unit 5502 may be provided with a button or a switch for turning the display unit 5502 on or off. This can be done.

[0377] In addition, the mobile phone shown in FIG. 23(D) has two operation buttons 5505. However, the number of operation buttons on a mobile phone is not limited to this. The mobile phone shown in FIG. 23(D) is a light-emitting device for use as a flashlight or illumination. The configuration may include the following.

[0378] <Home video game console> The semiconductor device of one embodiment of the present invention is applied to a stationary game machine, which is an example of a game machine. In FIG. 23E, a game machine main body 7520 and In addition, the game console 7520 may include a wireless or wired The controller 7522 can be connected by a wire. However, the controller 7522 has a display for displaying game images, and input devices other than buttons. The interface includes touch panels, sticks, rotary knobs, and sliding knobs. The controller 7522 may be provided with a shape not limited to that shown in FIG. The shape of the controller 7522 can be changed according to the genre of the game. For example, in shooters such as FPS (First Person Shooter), In gaming, the trigger is a button and a controller shaped like a gun is used. For example, in music games, controllers that mimic musical instruments and other equipment can be used. Furthermore, stationary game consoles do not use controllers, but can use a substitute Instead, it is equipped with a camera, depth sensor, microphone, etc. to capture the gestures of game players. The device may be operated by a keyboard and / or voice.

[0379] <Portable game console> The semiconductor device of one embodiment of the present invention can be applied to a portable game machine, which is an example of a game machine. The portable game machine shown in FIG. 23(F) includes a housing 5201, a display portion 5202, and a button 5203. 203, etc. Note that the portable game machine shown in FIG. 23(F) is an example and is not an embodiment of the present invention. The layout, shape and number of the display and buttons of a portable game machine to which such a semiconductor device is applied are The shape of the housing of the portable game machine is not limited to the configuration shown in FIG. F) is not limited to the configuration shown in FIG.

[0380] In the above, we have given examples of game consoles, such as stationary game consoles and portable game consoles. In addition to the above, the semiconductor device according to one embodiment of the present invention can be used in a commercial game machine (arcade game machine ) can also be applied.

[0381] <Television equipment> The semiconductor device of one embodiment of the present invention can be applied to a television set. The television device shown in FIG. 90G includes a housing 9000, a display unit 9001, a speaker 9003, and an operation panel. It has an operation key 9005 (including a power switch or an operation switch), a connection terminal 9006, etc. The television device has a large screen, for example, 50 inches or more, or 100 inches or more. A display unit 9001 can be incorporated.

[0382] <Mobile object> The semiconductor device according to one embodiment of the present invention can be applied to the vicinity of a driver's seat in an automobile, which is a moving object. Cut.

[0383] For example, FIG. 23(H) is a diagram showing the vicinity of the windshield in the interior of an automobile. In FIG. 23(H), a display panel 5701 and a display panel 5702 are attached to the dashboard. 702, display panel 5703, and display panel 5704 attached to the pillar are also shown. is.

[0384] The display panels 5701 to 5703 display navigation information, a speedometer, It can display the time, tachometer, mileage, fuel gauge, gear status, air conditioning settings, etc. This allows various information to be provided. The layout can be changed as needed to suit the user's preferences, enhancing the design. The display panels 5701 to 5703 can be used as lighting devices. It is also possible that

[0385] The display panel 5704 displays an image captured by an imaging means provided on the vehicle body. This can complement the blind spot that is blocked by the pillar. By displaying images from the imaging means provided, blind spots can be compensated for and safety can be improved. In addition, by projecting an image that complements the invisible parts, it is possible to make the sense of discomfort more natural. The display panel 5704 can also be used as a lighting device. can.

[0386] <Electronic devices for electronic advertising> The semiconductor device of one embodiment of the present invention can be applied to a display for electronic advertising. Figure 24(A) shows an example of a wall-mountable digital signage. FIG. 24(A) shows an electronic signboard 6200 attached to a wall 6201. This shows that.

[0387] <Foldable tablet-type information terminal> The semiconductor device of one embodiment of the present invention can be applied to a tablet information terminal. 24(B) shows a tablet-type information terminal that has a foldable structure. The information terminal illustrated in FIG. 24B includes a housing 5321a, a housing 5321b, and a display unit 5321b. 22 and an operation button 5323. In particular, the display unit 5322 is flexible. The device has a base material, and a foldable structure can be realized by the base material.

[0388] The housing 5321a and the housing 5321b are connected by a hinge portion 5321c. The hinge portion 5321c allows the display unit 532 to be folded in two. 2 is provided on the housing 5321a, the housing 5321b, and the hinge portion 5321c.

[0389] Although not shown, in Figs. 23(A) to (C), (E), 24(A), and (B), The electronic device shown may have a microphone and a speaker. For example, the electronic device described above can be provided with a voice input function.

[0390] Although not shown, the followings are shown in Figs. 23(A), (B), (D), 24(A), and (B). The electronic device may include a camera.

[0391] Although not shown, the electrodes shown in FIGS. 23(A) to 23(G) and 24(A) and 24(B) may be used. The child device has sensors inside the housing (force, displacement, position, speed, acceleration, angular velocity, rotation speed, distance , light, liquid, magnetism, temperature, chemicals, sound, time, hardness, electric field, current, voltage, power, radiation (including functions to measure temperature, flow rate, humidity, gradient, vibration, odor, infrared, etc.) In particular, the mobile phone shown in FIG. 23(D) may be equipped with a gyro sensor, an acceleration sensor, etc. By providing a detection device having a sensor that detects the inclination of the mobile phone, the orientation (vertical direction) of the mobile phone can be detected. The direction of the mobile phone relative to the direction of the camera is determined, and the screen display of the display unit 5502 is The display can be automatically switched depending on the orientation of the mobile phone.

[0392] Although not shown, the electrodes shown in FIGS. 23(A) to 23(G) and 24(A) and 24(B) may be used. The slave device is configured to have a device for acquiring biometric information such as fingerprints, veins, irises, or voiceprints. By applying this configuration, an electronic device having a biometric authentication function can be realized. It is possible.

[0393] In addition, a flexible display device may be used as a display unit of the electronic device shown in FIG. 23(A) to (G) and FIG. 24(A). Specifically, the display unit may be a display having a trajectory on a flexible substrate. A configuration including a transistor, a capacitance element, a display element, and the like may be used. As a result, flat electronic devices such as those shown in Figs. 23(A) to (G) and Fig. 24(A) can be manufactured. Not only the housing having a surface, but also the curved part such as the dashboard and pillar shown in FIG. 23(H) can be used. It is possible to realize an electronic device having a housing with a surface.

[0394] A flexible display device that can be applied to the display units shown in FIGS. 23(A) to 23(G) and 24(A) and 24(B) Examples of the base material that can be used include a material that is transparent to visible light, such as polyethylene terephthalate. Phthalate resin (PET), polyethylene naphthalate resin (PEN), polyether Polypropylene resin (PES), polyacrylonitrile resin, acrylic resin, polyimide resin, Polymethyl methacrylate resin, polycarbonate resin, polyamide resin, polycyclohexyl ether resin olefin resin, polystyrene resin, polyamide-imide resin, polypropylene resin, polyethylene Use ster resin, polyvinyl halide resin, aramid resin, epoxy resin, etc. Moreover, these materials may be mixed or laminated.

[0395] Note that this embodiment mode can be appropriately combined with other embodiment modes shown in this specification. do. [Explanation of symbols]

[0396] M1: transistor, M2: transistor, M3: transistor, CA: capacitance element, CB : Capacitor, CF: Capacitor, BIL: Wiring, RBL: Wiring, WBL: Wiring, WOL: Wiring Line, SL: Wiring, CAL: Wiring, BGL: Wiring, BGL1: Wiring, BGL2: Wiring, BG I: Insulator, FGI: Insulator, BGE: Conductor, FGE: Conductor, PE: Conductor, WE: Conductor, 11: semiconductor device, 20: control circuit, 21: control unit, 22[1]: voltage generating circuit , 22[P]: voltage generating circuit, 22[p1]: voltage generating circuit, 22[p2]: voltage generating circuit 22[p3]: voltage generating circuit, 23A: circuit, 23B: circuit, 23IN: internal circuit, 25: temperature detection circuit, 25a: temperature sensor, 25b: analog-to-digital conversion circuit, 25c : voltage control circuit, 30: memory unit, 40: memory cell array, 50: peripheral circuit, 51: word 52: bit line driver circuit; 52a: column decoder; 52b: processor; recharge circuit, 52c: sense amplifier, 52d: write circuit, 53: row decoder, 54: output circuit, 56: control logic circuit, 110: first storage area, 120: second storage area 2 memory areas, 121: cache, 122: cache, 123: cache, 130: 3rd storage area, 140: 4th storage area, 200: storage device, 210: storage circuit, 220: Memory circuit, 220a: Memory circuit, 220b: Memory circuit, 221: Memory cell, 230: Memory memory circuit, 230a: memory circuit, 230b: memory circuit, 231: memory cell, 232: memory Recell, 240: memory circuit, 300: transistor, 311: substrate, 313: semiconductor region , 314a: low resistance region, 314b: low resistance region, 315: insulator, 316: conductor, 3 20: insulator, 322: insulator, 324: insulator, 326: insulator, 328: conductor, 3 30: conductor, 350: insulator, 352: insulator, 354: insulator, 356: conductor, 3 60: insulator, 362: insulator, 364: insulator, 366: conductor, 370: insulator, 3 72: insulator, 374: insulator, 376: conductor, 380: insulator, 382: insulator, 3 84: Insulator, 386: Conductor, 500: Transistor, 500A: Transistor, 50 0B: transistor, 500C: transistor, 500D: transistor, 500E: transistor Transistor, 503: conductor, 503a: conductor, 503b: conductor, 505: conductor, 510: insulator, 511: insulator, 512: insulator, 514: insulator, 516: insulator, 518: conductor, 520: insulator, 522: insulator, 524: insulator, 530: oxide, 530a: oxide, 530b: oxide, 530c: oxide, 531a: region, 531b: Region, 540a: conductor, 540b: conductor, 542a: conductor, 542b: conductor, 5 43a: area, 543b: area, 544: insulator, 545: insulator, 546: conductor, 5 46a: conductor, 546b: conductor, 547a: conductor, 547b: conductor, 548: conductor 550: insulator, 552: metal oxide, 560: conductor, 560a: conductor, 56 0b: conductor, 570: insulator, 571: insulator, 573: insulator, 574: insulator, 5 75: insulator, 576a: insulator, 576b: insulator, 580: insulator, 581: insulator , 582: insulator, 586: insulator, 600: capacitive element, 610: conductor, 612: conductor body, 620: conductor, 630: insulator, 650: insulator, 5201: housing, 5202: surface display unit, 5203: button, 5321a: housing, 5321b: housing, 5321c: hinge unit , 5322: display unit, 5323: operation button, 5401: housing, 5402: display unit, 54 03: keyboard, 5404: pointing device, 5501: case, 5502: table display unit, 5503: microphone, 5504: speaker, 5505: operation button, 5701: display panel, 5702: display panel, 5703: display panel, 5704: display panel, 580 1: first housing, 5802: second housing, 5803: display unit, 5804: operation keys, 5805 : Lens, 5806: Connection section, 5901: Housing, 5902: Display section, 5903: Operation button , 5904: Operator, 5905: Band, 6200: Digital sign, 6201: Wall, 752 0: Game console, 7522: Controller, 9000: Housing, 9001: Display, 90 03: Speaker, 9005: Operation keys, 9006: Connection terminal

Claims

[Claim 1] A storage device and a control circuit, the storage device includes a first storage circuit that operates in a first storage hierarchy and a second storage circuit that operates in a second storage hierarchy; the first storage tier has a faster access speed than the second storage tier, the first memory circuit includes a first capacitance element and a first transistor having a function of holding a charge held in the first capacitance element; the second memory circuit includes a second transistor, a second capacitance element electrically connected to a gate of the second transistor, and a third transistor having a function of holding a charge held in the second capacitance element; the first and third transistors each include a semiconductor layer including an oxide semiconductor, a first gate, and a second gate; the control circuit has a function of changing the first memory circuit from the first memory hierarchy to the second memory hierarchy by inputting a voltage to the second gate of the first transistor, and a function of changing the second memory circuit from the second memory hierarchy to the first memory hierarchy by inputting a voltage to the second gate of the third transistor. Semiconductor device.

Images