Thin film forming method

Abstract

The present invention relates to a thin film forming method and, more specifically, to a thin film forming method for forming a dielectric thin film containing metal. A thin film forming method according to an embodiment of the present invention comprises the steps of: loading a substrate into a chamber; and forming a titanium dioxide (TiO2) layer on the substrate, wherein the step for forming the titanium dioxide (TiO2) includes a step for supplying a titanium (Ti)-containing gas onto the substrate, a step for supplying an oxygen (O)-containing gas onto the substrate, and a step for forming a plasma of a helium (He)- or germanium (Ge)-containing gas on the substrate.

Description

Thin film formation method

[0001] The present invention relates to a method for forming a thin film, and more particularly, to a method for forming a thin film for forming a dielectric thin film containing a metal.

[0002] Atomic Layer Deposition (ALD) is a well-known technology for forming thin films on substrates. It involves repeatedly depositing thin films layer by layer until they reach a desired thickness. Compared to conventional chemical vapor deposition (CVD) methods, the ALD process can produce thin films with superior step coverage and high film density.

[0003] Meanwhile, dielectric thin films containing metal are widely used in the manufacture of semiconductors, displays, solar cells, etc., and are mainly used as gate insulating films of transistors and dielectric thin films of capacitors.

[0004] Forming dielectric thin films containing metals using atomic layer deposition offers the advantages of precise thickness control, excellent step coverage, and low-temperature deposition. However, impurities in the thin films can cause leakage currents and other deteriorated electrical properties, necessitating additional high-temperature processing to address these issues.

[0005] (Prior art document) (Patent document 1) KR 10-2019-0125093 A

[0006] The present invention provides a thin film forming method capable of forming a dielectric thin film with excellent electrical properties.

[0007] A method for forming a thin film according to an embodiment of the present invention includes the steps of: introducing a substrate into a chamber; and forming a titanium dioxide (TiO2) layer on the substrate; wherein the step of forming the titanium dioxide (TiO2) layer includes the steps of: supplying a titanium (Ti)-containing gas onto the substrate; supplying an oxygen (O)-containing gas onto the substrate; and forming a plasma of a helium (He) or germanium (Ge)-containing gas onto the substrate.

[0008] After the step of supplying the titanium (Ti) containing gas, the step of forming plasma of a helium (He) or germanium (Ge) containing gas on the substrate may be included.

[0009] The above titanium (Ti) containing gas may include TiCl4 gas or Star-Ti gas.

[0010] The step of forming the above titanium dioxide (TiO2) layer can be repeated multiple times.

[0011] The step of forming plasma of the above helium (He) or germanium (Ge) containing gas may form plasma by supplying at least one of an argon (Ar) containing gas, a hydrogen (H) containing gas, a helium (He) containing gas, and a germanium (Ge) containing gas together with the helium (He) or germanium (Ge) containing gas.

[0012] After the step of forming the titanium dioxide (TiO2) layer, the method may further include a step of forming a high-k dielectric layer or a strontium oxide (SrO) layer on the titanium dioxide (TiO2) layer.

[0013] The step of forming the titanium dioxide (TiO2) layer and the step of forming the strontium oxide (SrO) layer can be repeated multiple times.

[0014] The step of importing the above substrate may include importing a substrate on which a ruthenium oxide (RuO2) layer is formed.

[0015] The above ruthenium oxide (RuO2) layer may have a rutile structure.

[0016]

[0017] A method for forming a thin film according to an embodiment of the present invention may further include a step of forming a ruthenium oxide (RuO2) layer on the substrate between the step of introducing the substrate and the step of forming the titanium dioxide (TiO2) layer.

[0018] A method for forming a thin film according to an embodiment of the present invention may further include, after the step of forming the titanium dioxide (TiO2) layer, a step of forming a thin film of at least one of hafnium (Hf), aluminum (Al), magnesium (Mg), yttrium (Y), zirconium (Zr), gadolinium (Gd), and lanthanum (La), or an oxide film or nitride film of at least one of these, on the titanium dioxide (TiO2) layer.

[0019] The step of forming plasma of the above helium (He) or germanium (Ge) containing gas can form plasma by supplying an oxygen (O) containing gas together with the helium (He) or germanium (Ge) containing gas.

[0020] According to an embodiment of the present invention, by supplying a titanium (Ti)-containing gas and an oxygen (O)-containing gas onto a substrate and then forming a plasma of a helium (He) or germanium (Ge)-containing gas and treating the substrate, impurities inside the thin film can be removed, thereby suppressing leakage current and promoting densification of the thin film, as well as improving the quality of the thin film.

[0021] In addition, by improving the properties of the dielectric thin film, the performance of the semiconductor device including it can be greatly improved.

[0022] FIG. 1 is a drawing exemplarily showing a semiconductor device according to an embodiment of the present invention.

[0023] Figure 2 is a schematic drawing showing a substrate processing device according to an embodiment of the present invention.

[0024] FIG. 3 is a schematic drawing of a gas injection unit of a substrate processing device according to one embodiment of the present invention.

[0025] FIG. 4 is a schematic drawing of a gas injection unit of a substrate processing device according to another embodiment of the present invention.

[0026] Figure 6 is a drawing schematically showing a thin film forming method according to an embodiment of the present invention.

[0027] FIG. 6 is a schematic diagram showing a transistor according to an embodiment of the present invention.

[0028] FIG. 7 is a schematic diagram showing a capacitor according to an embodiment of the present invention.

[0029] Hereinafter, embodiments of the present invention will be described in detail with reference to the attached drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms. These embodiments of the present invention are provided solely to ensure complete disclosure of the present invention and to fully inform those skilled in the art of the scope of the invention.

[0030] When a component, such as a layer, film, region or substrate, is referred to as being "on" another component throughout the specification, it can be interpreted that the component is either directly "on" the other component, or there may be other components intervening therebetween.

[0031] Additionally, relative terms such as "upper" or "lower" may be used herein to describe the relative relationship of certain elements to other elements as depicted in the drawings. It should be understood that relative terms are intended to encompass other orientations of the elements in addition to the orientation depicted in the drawings. To illustrate the invention in detail, the drawings may be exaggerated, and like reference numerals throughout the drawings designate like elements.

[0032]

[0033] FIG. 1 is a drawing exemplarily showing a semiconductor device according to an embodiment of the present invention.

[0034] As illustrated in FIG. 1, a semiconductor device according to an embodiment of the present invention may include a memory device such as a DRAM (Dynamic Random Access Memory). DRAM is a type of volatile semiconductor memory device commonly used in electronic devices such as computers and portable terminals.

[0035] A DRAM may include a plurality of memory cells arranged in a plurality of rows and columns, wherein each memory cell may include, for example, one transistor (100) and one capacitor (200).

[0036] As such, a DRAM may include a word line and a bit line. Here, the word line may be connected to or included in the gate electrode of the transistor (100) and determines whether the memory cell is used. On the other hand, the bit line may be connected to or included in the source electrode or drain electrode of the transistor (100) and serves to confirm the value (0 or 1) of the stored memory. For example, when a high voltage is applied to the gate electrode of the transistor (100), the capacitor (200) is charged and the memory may have a value of 1, and when a low voltage is applied to the gate electrode of the transistor (100), the capacitor (200) is discharged and the memory may have a value of 0.

[0037] Hereinafter, a method for forming a thin film according to an embodiment of the present invention will be described as an example in which it is used for manufacturing DRAM, and more specifically, for manufacturing transistors and capacitors included in DRAM. However, it should be understood that the method for forming a thin film according to an embodiment of the present invention can be applied in various ways to manufacturing not only DRAM but also other semiconductor devices, display devices, solar cells, etc.

[0038]

[0039] FIG. 2 is a schematic drawing showing a substrate processing device according to an embodiment of the present invention.

[0040] Referring to FIG. 2, a substrate processing device according to an embodiment of the present invention is a device for forming a thin film, for example, a thin film including a titanium dioxide (TiO2) layer, on a substrate, and includes a chamber (10), a substrate support unit (20) provided within the chamber (10) so as to support at least one substrate, and a gas injection unit (30) provided within the chamber (10) so as to face the substrate support unit (20) and for injecting a process gas toward the substrate support unit (20). In addition, the substrate processing device may include a gas supply unit (40) for providing gas to the gas injection unit (30), and may include an RF power source (50) for supplying power to generate plasma within the chamber (10). In addition, the substrate processing device may further include a control unit (not shown) for controlling the RF power source (50).

[0041] The chamber (10) provides a predetermined reaction space and maintains it airtight. The chamber (10) may include a body (12) having a predetermined reaction space, including a flat surface of approximately circular or rectangular shape and a side wall extending upward from the flat surface, and a cover (14) positioned on the body (12) in an approximately circular or rectangular shape to maintain the reaction space airtight. However, the chamber (10) is not limited thereto and may be manufactured in various shapes corresponding to the shape of the substrate (S).

[0042] An exhaust port (not shown) may be formed in a predetermined area on the lower surface of the chamber (10), and an exhaust pipe (not shown) connected to the exhaust port may be provided on the outside of the chamber (10). In addition, the exhaust pipe may be connected to an exhaust device (not shown). A vacuum pump such as a turbo molecular pump may be used as the exhaust device. Therefore, the inside of the chamber (10) may be vacuum-sucked to a predetermined reduced pressure atmosphere, for example, a predetermined pressure of 0.1 mTorr or less, by the exhaust device. The exhaust pipe may be installed not only on the lower surface of the chamber (10), but also on the side surface of the chamber (10) below the substrate support member (20) described later. In addition, it goes without saying that a plurality of exhaust pipes and corresponding exhaust devices may be further installed in order to reduce the exhaust time.

[0043] A substrate support (20) is installed within the chamber (10), and at least one substrate brought into the chamber (10) for a substrate processing process, for example, a thin film deposition process, can be mounted on the substrate support (20). The substrate support (20) can be equipped with, for example, an electrostatic chuck to hold the substrate by electrostatic force so that such a substrate can be mounted and supported, or the substrate can be supported by vacuum suction or mechanical force.

[0044] Here, the substrate provided to the substrate support (20) may be a substrate that has already undergone a predetermined treatment before forming a titanium dioxide (TiO2) layer. For example, the substrate may be a substrate on which a gate electrode (110) has already been formed to form a gate insulating film (120) included in a transistor (100), and may be a substrate on which a first capacitor electrode (210) has already been formed to form a dielectric thin film (220) included in a capacitor (200). At this time, the gate electrode (110) or the first capacitor electrode (210) may include a ruthenium oxide (RuO2) layer. Of course, the substrate may also be a substrate on which a ruthenium oxide (RuO2) layer is not formed. The substrate support (20) may be provided with, for example, an electrostatic chuck or the like to hold the substrate in place and supported by electrostatic force, or may support the substrate by vacuum adsorption or mechanical force.

[0045] The substrate support unit (20) may include a substrate support (22) on which the substrate is mounted, and an elevator (24) disposed below the substrate support (22) to move the substrate support (22) up and down. Here, the substrate support (22) may be manufactured to be larger than the substrate, and the elevator (24) is provided to support at least one area of ​​the substrate support (22), for example, the central area, and when the substrate is mounted on the substrate support (22), the substrate support (22) may be moved closer to the gas injection unit (20). In addition, a heater (not shown) may be installed inside the substrate support. The heater generates heat at a predetermined temperature to heat the substrate support (22) and the substrate mounted on the substrate support (22), thereby allowing a thin film to be uniformly deposited on the substrate.

[0046] A gas supply unit (40) may be installed in the lid (12) of the chamber (10). The gas supply unit (40) may be installed so as to penetrate the lid (12) of the chamber (10) and may provide a plurality of different gases to the gas injection unit (30). Here, the plurality of gases may include a source gas and a reaction gas, and may further include a purge gas. In addition, the plurality of gases may further include a processing gas for forming a plasma to remove impurities on the substrate. The gas supply unit (40) may be configured to provide the plurality of gases simultaneously, or to provide a gas selected from among the plurality of gases to the gas injection unit (30).

[0047] The gas injection unit (30) is provided at the upper side inside the chamber (10) and injects process gas toward the substrate. The gas injection unit (30) is connected to the gas supply unit at the upper side, and an injection hole for injecting the process gas to the substrate is formed at the lower side. Such a gas injection unit (30) may include an injector having an injection hole formed at the end or a shower head having a plurality of fine injection holes formed. Meanwhile, the gas injection unit (30) may be provided with a plurality of gas supply paths that are separated from each other. Various structures of the gas injection unit (30) according to an embodiment of the present invention will be described later with reference to FIGS. 3 and 4.

[0048] The RF power source (50) supplies power to form plasma. That is, the RF power source (50) supplies power to generate plasma in the reaction space within the chamber (10). For example, the RF power source (50) supplies power to either the substrate support (20) or the gas injection unit (30), and the other of the substrate support (20) or the gas injection unit (30) is grounded, so that plasma can be formed in the space between the substrate support (20) and the gas injection unit (30).

[0049]

[0050] FIG. 3 is a schematic drawing of a gas injection unit of a substrate processing apparatus according to one embodiment of the present invention, and FIG. 4 is a schematic drawing of a gas injection unit of a substrate processing apparatus according to another embodiment of the present invention. Here, FIG. 3 shows a bottom surface of a gas injection unit of a substrate processing apparatus according to one embodiment of the present invention, and FIG. 4 shows a bottom surface of a gas injection unit of a substrate processing apparatus according to another embodiment of the present invention.

[0051] Referring to FIG. 3, a gas injection unit (30) of a substrate processing device according to an embodiment of the present invention may be formed with a first gas supply path for injecting and supplying a first gas onto a substrate and a second gas supply path for injecting and supplying a second gas onto the substrate. The first gas supply path and the second gas supply path are formed to be independent and separate from each other, so that the first gas and the second gas can be supplied onto the substrate separately without being mixed within the gas injection unit (30). A first gas passing through the first gas supply path can be supplied onto the substrate through a first gas injection hole (h1) communicating with the first gas supply path, and a second gas passing through the second gas supply path can be supplied onto the substrate through a second gas injection hole (h2) communicating with the second gas supply path.

[0052] Here, the first gas may include a raw material gas, and the raw material gas may include a titanium (Ti)-containing gas. In addition, the second gas may include a reaction gas, and the reaction gas may include an oxygen (O)-containing gas. For example, the titanium (Ti)-containing gas may be TiCl4 gas or Star-Ti gas, and the reaction gas may be oxygen (O2) gas. Here, Star-Ti gas may refer to trimethoxy(pentamethylcyclopentadienyl) titanium(IV) gas. However, it is not limited thereto, and the raw material gas may use various gases containing titanium (Ti), and the reaction gas may use various gases containing oxygen (O), such as ozone (O3).

[0053] Meanwhile, a purge gas may be supplied through at least one of the first gas supply path and the second gas supply path, and a processing gas for forming plasma on the substrate may be supplied through at least one of the first gas supply path and the second gas supply path. That is, the first gas supply path and the second gas supply path do not necessarily supply a single gas each, but may be configured to supply a mixture of a plurality of gases or to supply a gas selected from the plurality of gases.

[0054] Although not shown, the gas injection unit (30) may be configured to inject gas in an area other than the center. That is, as described below, in the case where the substrate support unit (20) supports multiple substrates, the gas injection unit (30) may have gas injection holes formed to inject gas only in the outer area of ​​the substrate support unit (20).

[0055] In the substrate processing device according to one embodiment of the present invention, the substrate support unit (20) facing the gas injection unit (30) can support at least one substrate provided into the chamber (10). That is, the substrate support unit (20) can support one substrate or a plurality of substrates. For example, the substrate support unit (20) can support six substrates. In this case, the substrate support unit (20) can have a central region and an outer region arranged outside the central region, and the substrate support unit (20) can support a plurality of substrates in the outer region. At this time, the outer region can be arranged to surround the central region. Accordingly, the central region can be arranged inside the outer region. For example, when the central region is formed in a circular shape, the outer region can be formed in a circular ring shape surrounding the central region. Here, the plurality of substrates can be arranged to be spaced apart from each other along the outer region. For example, a plurality of substrates may be supported on the support surface of the substrate support (22) so as to be spaced apart from each other at the same angle with respect to the central axis of the substrate support (22) in the outer region. The substrate support (22) may be rotated around the central axis while the processing process is performed. When the support surface is formed in a circular shape, the central axis may correspond to the center of the support surface. Meanwhile, since a plurality of substrates are supported on the support surface in the outer region, no substrates may be positioned in the central region.

[0056] Referring to FIG. 4, a gas injection unit (30) of a substrate processing device according to another embodiment of the present invention may include a first gas injection unit (31) having a first gas supply path for supplying a first gas to a first region (Z1), and a second gas injection unit (32) having a second gas supply path for supplying a second gas to a second region (Z2).

[0057] To explain this in more detail, the reaction space within the chamber (10) can be divided into a first region (Z1), a second region (Z2), and a third region (Z3). The first region (Z1) may be a portion of one side of the reaction space, and a first gas injection unit (31) for injecting a first gas, for example, a raw material gas, into the first region (Z1) may be arranged in the first region (Z1). In addition, the second region (Z2) may be a portion of the other side of the reaction space, and a second gas injection unit (32) for injecting a reaction gas into the second region (Z2) may be arranged in the second region (Z2). Here, a first gas injection hole (not shown) for injecting the first gas may be formed in the first gas injection unit (31), and a second gas injection hole (not shown) for injecting the second gas may be formed in the second gas injection unit (32). The first gas injection unit (31) and the second gas injection unit (32) can be coupled to the lid (12) of the chamber (10).

[0058] The first gas injection unit (31) and the second gas injection unit (32) may be implemented with the same type of injection structure, or may be implemented with different types of injection structures. For example, the first gas injection unit (31) and the second gas injection unit (32) may both have a showerhead type injection structure, or may have an electrode structure type injection structure including a first electrode and a second electrode that are spaced apart from each other. In the electrode structure type, power may be applied to the first electrode and the second electrode may be grounded, or the first electrode may be grounded and power may be applied to the second electrode. Meanwhile, the first gas injection unit (31) may have a showerhead type injection structure and the second gas injection unit (32) may have an electrode structure type injection structure, or the first gas injection unit (31) may have an electrode structure type injection structure and the second gas injection unit (32) may have a showerhead type injection structure.

[0059] The third region (Z3) may be a region that divides the reaction space within the chamber (10) into a first region (Z1) and a second region (Z2). That is, the third region (Z3) may be a portion of the center side of the reaction space. The third region (Z3) may divide the reaction space within the chamber (10) into the first region (Z1) and the second region (Z2) so that the raw material gas supplied within the first region (Z1) and the reaction gas supplied within the second region (Z2) do not mix. A third gas injection unit (33) for injecting a purge gas may be arranged in the third region (Z3). Here, a third gas injection hole (not shown) for injecting the purge gas may be formed in the third gas injection unit (33).

[0060] The third gas injection unit (33) can divide the third zone (Z3) into a first zone, a second zone, and a third zone and inject purge gas into the third zone (Z3). To this end, the third gas injection unit (33) can include a first purge gas injection unit (33a) for injecting purge gas into the first zone, a second purge gas injection unit (33b) for injecting purge gas into the second zone, and a center purge gas injection unit (33c) for injecting purge gas into the third zone.

[0061] The first purge gas injection unit (33a) can inject purge gas into the first zone of the third region (Z3). The first purge gas injection unit (33a) can be equipped with a first plasma injection unit (33a-1) that can inject an activated processing gas, i.e., a plasma gas, into the first zone of the third region (Z3). An RF power source (50) for generating plasma can be connected to the first plasma injection unit (33a-1). For example, the first plasma injection unit (33a-1) can inject plasma gas into the first zone from the inside of the first purge gas injection unit (33a). Accordingly, in the process of the substrate moving from the first region (Z1) to the second region (Z2) through the first region as the substrate support member (20) rotates after the first gas, for example, the raw material gas, is supplied to the substrate in the first region (Z1), the first plasma injection unit (33a-1) can perform plasma treatment on the substrate passing through the first region. That is, the first plasma injection unit (33a-1) can treat (pre-treat) the substrate on which the raw material gas is injected using plasma. Accordingly, by removing impurities within the raw material gas adsorbed on the substrate, it can contribute to improving the quality of the thin film deposited on the substrate.

[0062] The second purge gas injection unit (33b) can inject purge gas into the second zone of the third zone (Z3). The second zone may be an opposite zone of the first zone. The second purge gas injection unit (33b) may be provided with a second plasma injection unit (33b-1) capable of injecting an activated processing gas, i.e., a plasma gas, into the second zone of the third zone (Z3). An RF power source (50) for generating plasma may be connected to the second plasma injection unit (33b-1). For example, the second plasma injection unit (33b-1) may inject plasma gas into the second zone from the inside of the second purge gas injection unit (33b). Accordingly, in the process of the substrate moving from the second zone (Z2) to the first zone (Z1) through the second zone as the substrate support member (20) rotates after the second gas, for example, the reaction gas, is supplied to the substrate in the second zone (Z2), the second plasma injection unit (33b-1) can perform plasma treatment on the substrate passing through the second zone. That is, the second plasma injection unit (33b-1) can treat (post-treat) the substrate on which the reaction gas has been injected using plasma. Accordingly, by removing impurities inside the thin film deposited on the substrate, the thin film can be densified, and the quality of the thin film can be further improved.

[0063] The center purge gas injection unit (33c) can inject purge gas into the third zone of the third zone (Z3). Accordingly, the center purge gas injection unit (33c) can prevent the raw material gas injected into the first zone (Z1) and the reaction gas injected into the second zone (Z2) from mixing with each other through the third zone. Meanwhile, the first purge gas injection unit (33a) can prevent the raw material gas injected into the first zone (Z1) and the reaction gas injected into the second zone (Z2) from mixing with each other through the first zone. The second purge gas injection unit (33b) can prevent the raw material gas injected into the first zone (Z1) and the reaction gas injected into the second zone (Z2) from mixing with each other through the second zone.

[0064] In the case of a substrate processing device according to another embodiment of the present invention, a processing process for a substrate can be performed by moving the substrate through the first region (Z1), the first zone, the second zone (Z2), and the second zone and then back to the first zone (Z1) by rotating the substrate support unit (20). In this case, the substrate support unit (20) can be rotated around a central axis. Here, the substrate support unit (20) can support a plurality of substrates, and for example, the substrate support unit (20) can support a plurality of substrates including two substrates introduced into the first region (Z1) and two substrates introduced into the second region (Z2). Of course, the substrate support unit (20) can also support a plurality of substrates including three substrates introduced into the first region (Z1) and three substrates introduced into the second region (Z2). Here, the substrate support (20) may have a central region and an outer region disposed outside the central region, and the substrate support (20) may support a plurality of substrates in the outer region. At this time, the outer region may be disposed to surround the central region. Accordingly, the central region may be disposed inside the outer region. For example, when the central region is formed in a circular shape, the outer region may be formed in a circular ring shape surrounding the central region. Here, the plurality of substrates may be disposed to be spaced apart from each other along the outer region. For example, the plurality of substrates may be supported on the support surface of the substrate support (22) in the outer region so as to be spaced apart from each other at the same angle with respect to the central axis of the substrate support (22). During the processing, the substrate support (22) may be rotated around the central axis. When the support surface is formed in a circular shape, the central axis may correspond to the center of the support surface. Meanwhile, since multiple substrates are supported on the support surface in the outer region, no substrates may be positioned in the central region.

[0065]

[0066] Hereinafter, the thin film forming method of the present invention will be described in detail with reference to FIG. 5. The thin film forming method according to an embodiment of the present invention may be a method of forming a thin film using the substrate processing apparatus described above, and therefore, any description overlapping with the above-described content with respect to the substrate processing apparatus will be omitted.

[0067] A method for forming a thin film according to an embodiment of the present invention includes a step (S100) of introducing a substrate into a chamber (10) and a step (S200) of forming a titanium dioxide (TiO2) layer on the substrate, and the step (S200) of forming the titanium dioxide (TiO2) layer includes a step (S210) of supplying a titanium (Ti)-containing gas onto the substrate, a step (S220) of supplying an oxygen (O)-containing gas onto the substrate, and a step (S230) of forming a plasma of a helium (He) or germanium (Ge)-containing gas onto the substrate.

[0068] A titanium dioxide (TiO2) thin film composed of a titanium dioxide (TiO2) layer has a dielectric constant (high-K) that is four times higher than that of zirconium oxide (ZrO2) thin films and hafnium oxide (HfO2) thin films, which are known as materials with high dielectric constants. A method for forming a thin film according to an embodiment of the present invention forms a titanium dioxide (TiO2) thin film having such a high dielectric constant on a substrate, thereby minimizing the size of semiconductor devices and improving their performance when manufacturing semiconductor devices such as transistors and capacitors.

[0069] A titanium dioxide (TiO2) thin film like this can be formed by a chemical vapor deposition (CVD) process in which a step of supplying a raw material gas and a step of supplying a reaction gas are performed simultaneously, or by an atomic layer deposition (ALD) process in which the steps of supplying a raw material gas and a step of supplying a reaction gas are performed sequentially. Hereinafter, an embodiment of forming a titanium dioxide (TiO2) thin film by an atomic layer deposition process will be described, but it is of course possible for such a titanium dioxide (TiO2) thin film to be formed by various processes other than the atomic layer deposition process.

[0070] The substrate introduction step (S100) introduces a substrate (S) into the reaction space of the chamber (10). The substrate (S) introduced into the reaction space may be mounted on a substrate support member (20). Here, the substrate may include various semiconductor substrates. For example, the substrate (S) may be a semiconductor substrate including silicon (Si), and such a substrate may be a substrate on which a predetermined treatment has already been performed before forming a titanium dioxide (TiO2) thin film. For example, the substrate (S) may be a substrate on which a gate electrode (110) has already been formed to form a gate insulating film (120) included in a transistor (100), and may be a substrate on which a first capacitor electrode (210) has already been formed to form a dielectric thin film (220) included in a capacitor (200). At this time, the gate electrode (110) or the first capacitor electrode (210) may include a ruthenium oxide (RuO2) layer. That is, the step of introducing the substrate (S100) may introduce a substrate on which a ruthenium oxide (RuO2) layer has already been formed. In addition, between the step of introducing the substrate (S100) and the step of forming the titanium dioxide (TiO2) layer (S200), a step of forming a ruthenium oxide (RuO2) layer on the substrate may be further included. Here, the ruthenium oxide (RuO2) layer may have a rutile structure. The rutile structure can be viewed as a form in which anions form a hexagonal close-packed structure (HCP; Hexagonal Closed Packed) and cations fill half of the octahedral sites of this hexagonal close-packed structure. When a titanium dioxide (TiO2) thin film is formed with a rutile structure, the dielectric constant can be improved. In an embodiment of the present invention, a titanium dioxide (TiO2) thin film with a rutile structure having a high dielectric constant can be formed by forming a titanium dioxide (TiO2) layer on a ruthenium oxide (RuO2) layer having a rutile structure using an atomic layer deposition process.However, it is of course possible that the substrate may be one on which a ruthenium oxide (RuO2) layer has not been formed.

[0071] The step of supplying a titanium (Ti)-containing gas (S210) supplies a titanium (Ti)-containing gas as a raw material gas onto a substrate. Here, the titanium (Ti)-containing gas may be TiCl4 gas or Star-Ti gas, and the reaction gas may be oxygen (O2) gas. Here, Star-Ti gas may mean Trimethoxy(pentamethylcyclopentadienyl) titanium(IV) gas.

[0072] As described above, the ruthenium oxide (RuO2) layer can have a rutile structure, and by forming a titanium dioxide (TiO2) layer on the ruthenium oxide (RuO2) layer having a rutile structure, a titanium dioxide (TiO2) thin film having a rutile structure and a high dielectric constant can be formed. However, the ruthenium oxide (RuO2) layer has a property that it can be easily reduced to ruthenium (Ru) depending on the type of gas supplied onto the ruthenium oxide (RuO2) layer. When the ruthenium oxide (RuO2) layer is reduced, volume shrinkage and voids may occur due to the loss of oxygen (O), which may deteriorate the leakage current characteristics. In addition, when the oxygen (O) generated by the reduction reaction diffuses, it may cause deterioration of the characteristics of the semiconductor device.

[0073] Accordingly, in an embodiment of the present invention, TiCl4 gas or Star-Ti gas may be used as a raw material gas for forming a titanium oxide film (TiO2) on a ruthenium oxide (RuO2) layer. When TiCl4 gas or Star-Ti gas is used, reduction of the ruthenium oxide (RuO2) layer can be prevented, and impurities due to reduction can be prevented from being formed at the interface between the ruthenium oxide (RuO2) layer and the titanium dioxide (TiO2) layer.

[0074] The step of supplying an oxygen (O)-containing gas (S220) supplies an oxygen (O)-containing gas as a reaction gas on a substrate to which a titanium (Ti)-containing gas has been supplied. Here, the step of supplying an oxygen (O)-containing gas (S200) may include a step of forming a plasma of an oxygen (O)-containing gas on the substrate, and the oxygen (O)-containing gas may be various gases containing an oxygen (O) component, such as oxygen (O2), ozone (O3), and nitrous oxide (N2O).

[0075] Meanwhile, the step of supplying a titanium (Ti)-containing gas (S210) may include a step of supplying a first purge gas after supplying the titanium (Ti)-containing gas as a raw material gas, and the step of supplying an oxygen (O)-containing gas (S220) may include a step of supplying a second purge gas after supplying the oxygen (O)-containing gas as a reaction gas. That is, the titanium dioxide (TiO2) layer may be formed by sequentially supplying a raw material gas, a first purge gas, a reaction gas, and a second purge gas onto the substrate (S).

[0076] The step (S230) of forming plasma of a helium (He) or germanium (Ge) containing gas forms plasma of a helium (He) or germanium (Ge) containing gas on the substrate. That is, the step (S230) of forming plasma of a helium (He) or germanium (Ge) containing gas forms plasma of a helium (He) containing gas on the substrate or forms plasma of a germanium (Ge) containing gas. The step (S230) of forming plasma of a helium (He) or germanium (Ge) containing gas supplies a helium (He) or germanium (Ge) containing gas on the substrate, and supplies power from an RF power source (50) to generate plasma within the chamber (10), thereby forming plasma of a helium (He) or germanium (Ge) containing gas on the substrate.

[0077] In the past, when forming a titanium dioxide (TiO2) thin film by an atomic layer deposition process, a high-temperature process of heat-treating (post-annealing) the titanium dioxide (TiO2) thin film at a high temperature exceeding 400°C was performed to improve the electrical properties. However, when treating a titanium dioxide (TiO2) thin film by such a high-temperature process, there was a problem that the lower electrode already formed on the substrate, for example, an electrode including a ruthenium oxide (RuO2) layer, may be oxidized. Therefore, in a method for forming a thin film according to an embodiment of the present invention, after a step (S220) of supplying an oxygen (O)-containing gas, a step (S230) of forming a plasma of a helium (He) or germanium (Ge)-containing gas is performed, thereby preventing oxidation damage to the electrode and minimizing the diffusion of impurities.

[0078] That is, in the step (S230) of forming plasma of a helium (He) or germanium (Ge) containing gas, the substrate onto which the oxygen (O) containing gas, i.e., the reaction gas, is sprayed can be treated (post-treated) using plasma. When the plasma of the helium (He) containing gas is formed on the substrate onto which the oxygen (O) containing gas is sprayed, the heat treatment effect can be obtained through the plasma without performing a high-temperature process. Accordingly, by removing impurities inside the thin film deposited on the substrate, it is possible to suppress leakage current, promote densification of the thin film, and improve the quality of the thin film. Here, the step (S230) of forming plasma of the helium (He) containing gas can form plasma by supplying at least one of an argon (Ar) containing gas, a hydrogen (H) containing gas, a helium (He) containing gas, and a germanium (Ge) containing gas together with the helium (He) containing gas.

[0079] If a plasma of a germanium (Ge)-containing gas is formed on a substrate onto which an oxygen (O)-containing gas is sprayed, germanium dioxide (GeO2) can be formed within the thin film. Germanium dioxide (GeO2) has a band gap of approximately 6.6 eV, which is higher than that of titanium dioxide (TiO2) which has a band gap of approximately 3 eV. Therefore, when germanium dioxide (GeO2) is formed within the thin film, the band gap can be increased, thereby suppressing leakage current. In addition, germanium dioxide (GeO2) has a rutile structure, like titanium dioxide (TiO2). Therefore, even when germanium dioxide (GeO2) is formed within a titanium dioxide (TiO2) thin film, the rutile structure can be maintained, which not only induces crystallization of the thin film but also improves the quality of the thin film.

[0080] In addition, the method for forming a thin film according to an embodiment of the present invention may further include a step of forming a plasma of a helium (He) or germanium (Ge) containing gas on the substrate after the step (S210) of supplying a titanium (Ti) containing gas. That is, the method for forming a thin film according to an embodiment of the present invention may include a step of forming a plasma of a helium (He) or germanium (Ge) containing gas on the substrate after the step (S210) of supplying a titanium (Ti) containing gas and before the step (S220) of supplying an oxygen (O) containing gas. In this way, when the step of forming a plasma of a helium (He) or germanium (Ge) containing gas on the substrate is performed after the step (S210) of supplying a titanium (Ti) containing gas, the substrate onto which the titanium (Ti) containing gas, i.e., the raw material gas, is sprayed can be treated (pre-treated) using plasma. Accordingly, it can contribute to improving the quality of a thin film deposited on the substrate by removing impurities within the raw material gas adsorbed on the substrate. Here, the step of forming plasma of a helium (He) or germanium (Ge)-containing gas after the step of supplying a titanium (Ti)-containing gas (S210) may form plasma by supplying at least one of an argon (Ar)-containing gas, a hydrogen (H2)-containing gas, a helium (He)-containing gas, and a germanium (Ge)-containing gas together with the helium (He) or germanium (Ge)-containing gas. In addition, the step of forming plasma of the helium (He) or germanium (Ge)-containing gas may form plasma by supplying an oxygen (O)-containing gas, for example, an oxygen (O2) gas, together with the helium (He) or germanium (Ge)-containing gas. In this case, impurities inside the thin film can be removed more effectively.

[0081] As described above, the step (S200) of forming a titanium dioxide (TiO2) layer can be performed by a substrate processing device having a gas injection unit in which a first gas supply path and a second gas supply path are separated. That is, the thin film forming method according to an embodiment of the present invention can be performed in a chamber (10) having a gas injection unit (30) in which a first gas supply path for supplying a first gas, for example, a titanium (Ti) containing gas, and a second gas supply path for supplying a second gas, for example, an oxygen (O) containing gas, are separately formed, as described above with respect to FIG. 3. In this case, one or a plurality of substrates can be introduced into the chamber (10), and as described above, the plurality of substrates can be six substrates. In addition, in this case, a helium (He) containing gas can be supplied through at least one of the first gas supply path and the second gas supply path.

[0082] Meanwhile, the step (S200) of forming a titanium dioxide (TiO2) layer may be performed by a substrate processing device provided with a gas injection unit that supplies a first gas to a first region (Z1) and a second gas to a second region (Z2). That is, the thin film forming method according to an embodiment of the present invention may be performed in a chamber (10) provided with a gas injection unit (30) in which a first gas supply path for supplying a first gas, for example, a titanium (Ti)-containing gas, to the first region (Z1) and a second gas supply path for supplying a second gas, for example, an oxygen (O)-containing gas, to the second region (Z2) are separately formed, as described above with respect to FIG. 4. In this case, a plurality of substrates may be loaded into the chamber (10), and as described above, two or three substrates may be loaded into each of the first region (Z1) and the second region (Z2). Additionally, helium (He) containing gas can be supplied through at least one of the first plasma injection unit (33a-1) and the second plasma injection unit (33b-1).

[0083] In addition, the method for forming a thin film according to an embodiment of the present invention may further include, after the step (S200) of forming a titanium dioxide (TiO2) layer, a step of forming a dielectric layer having a high dielectric constant, i.e., a high-k dielectric layer or a strontium oxide (SrO) layer, on the titanium dioxide (TiO2) layer. Of course, the method for forming a thin film according to an embodiment of the present invention may also form, after the step (S200) of forming a titanium dioxide (TiO2) layer, a thin film of at least one of strontium (Sr), hafnium (Hf), titanium (Ti), aluminum (Al), magnesium (Mg), yttrium (Y), zirconium (Zr), gadolinium (Gd), and lanthanum (La), or an oxide film or nitride film of at least one of these, on the titanium dioxide (TiO2) layer. At this time, the step of forming a titanium dioxide (TiO2) layer may include a step of supplying a titanium (Ti)-containing gas (S210), a step of supplying an oxygen (O)-containing gas (S220), and a step of forming a plasma of a germanium (Ge)-containing gas (S230), which may constitute a process cycle of an atomic layer deposition process, and such a process cycle may be repeated multiple times until a thin film of a desired thickness is formed, thereby forming a titanium dioxide (TiO2) thin film. Here, the step of forming a strontium oxide (SrO) layer may be performed by sequentially performing a step of supplying a strontium (Sr)-containing gas onto the substrate and a step of supplying an oxygen (O)-containing gas onto the substrate after forming a titanium dioxide (TiO2) thin film on the substrate through the above process cycle, and such a process cycle may be repeated multiple times until a thin film of a desired thickness is formed.In addition, the step of forming a strontium oxide (SrO) layer may include a step of forming plasma of at least one of a germanium (Ge)-containing gas, an argon (Ar)-containing gas, a hydrogen (H2)-containing gas, and a helium (He)-containing gas on the substrate after at least one of a step of supplying a strontium (Sr)-containing gas onto the substrate and a step of supplying an oxygen (O)-containing gas onto the substrate. In this case, impurities of a raw material gas adsorbed on the substrate or a thin film formed on the substrate can be effectively removed.

[0084] Meanwhile, the thin film forming method according to an embodiment of the present invention can be performed at a temperature of 200 to 400°C. That is, the step of forming a titanium dioxide (TiO2) layer can be performed at a temperature of 200°C or higher and 400°C or lower. When a titanium oxide (TiO2) film is formed at a high temperature exceeding 400°C, there was a problem that the lower electrode already formed on the substrate, for example, an electrode including a ruthenium oxide (RuO2) layer, may be oxidized. Therefore, the thin film forming method according to an embodiment of the present invention can prevent oxidation damage to the electrode and minimize diffusion of impurities by forming the titanium dioxide (TiO2) layer through a low-temperature process of 200 to 400°C.

[0085] After forming a titanium dioxide (TiO2) thin film by forming multiple layers of titanium dioxide (TiO2) in this way or after forming a high-k dielectric layer or a strontium oxide (SrO) layer on the titanium dioxide (TiO2) thin film, a step of forming an upper electrode can be performed, and here, the upper electrode can play the role of the source and drain electrodes (140a, 140b) of the transistor (100) or the second capacitor electrode (230) of the capacitor (200).

[0086]

[0087] FIG. 6 is a schematic diagram showing a transistor according to an embodiment of the present invention.

[0088] The above-described thin film forming method can be used to form a gate insulating film (120) of a transistor (100) according to an embodiment of the present invention. At this time, the transistor (100) according to an embodiment of the present invention can include a gate electrode (110), an active layer (130) spaced apart from the gate electrode (110), a gate insulating film (120) disposed between the gate electrode (110) and the active layer (130), and source and drain electrodes (140a, 140b) disposed to be in contact with the active layer (130). Here, the transistor (100) can include a bottom gate type transistor in which the gate electrode (110) is disposed on the lower side of the gate insulating film (120), as illustrated in FIG. 6. Although not shown, it is to be understood that the transistor (100) may include a top gate type transistor in which the gate electrode (110) is positioned on the upper side of the gate insulating film (120).

[0089] Here, the gate electrode (110) may include a ruthenium oxide (RuO2) layer, and the gate insulating film may include a titanium dioxide (TiO2) layer formed by the aforementioned thin film forming method. That is, the transistor (100) according to the embodiment of the present invention may include a MOS (Metal-Oxide-Semiconductor) transistor in which a titanium dioxide (TiO2) thin film including a titanium dioxide (TiO2) layer is disposed between the gate electrode (110) and the active layer (130). In this way, the embodiment of the present invention can be applied to minimize the content of impurities and improve the film quality when forming the gate insulating film (120) of the MOS transistor, while simultaneously implementing a MOS transistor with low power consumption required for control and a fast switching speed.

[0090]

[0091] FIG. 7 is a schematic diagram showing a capacitor according to an embodiment of the present invention.

[0092] The above-described thin film forming method can be used to form a dielectric thin film (220) of a capacitor (200) according to an embodiment of the present invention. At this time, the capacitor (200) according to an embodiment of the present invention can include a first capacitor electrode (210), a second capacitor electrode (230) spaced apart from the first capacitor electrode (210), and a dielectric thin film (220) disposed between the first capacitor electrode (210) and the second capacitor electrode (230).

[0093] Here, the capacitor electrodes (210, 230) may include a ruthenium oxide (RuO2) layer, and the dielectric thin film (220) may include a titanium dioxide (TiO2) layer formed by the thin film forming method described above. That is, the capacitor (200) according to the embodiment of the present invention may include a MIM (Metal-Insulator-Metal) capacitor in which a titanium dioxide (TiO2) thin film including a titanium dioxide (TiO2) layer is disposed between the first capacitor electrode (210) and the second capacitor electrode (230), as illustrated in FIG. 7. In this way, the embodiment of the present invention can be applied to implement an MIM capacitor in which the manufacturing process is simplified while minimizing the content of impurities and improving the film quality when forming the dielectric thin film (220) of the MIM capacitor.

[0094]

[0095] While the preferred embodiments of the present invention have been described and illustrated using specific terms above, such terms are solely for the purpose of clearly describing the present invention, and it is to be understood that various modifications and variations may be made to the embodiments and terms described herein without departing from the spirit and scope of the appended claims. Such modified embodiments should not be construed individually from the spirit and scope of the present invention, but should be considered to fall within the scope of the claims.

[0096] According to an embodiment of the present invention, by supplying a titanium (Ti)-containing gas and an oxygen (O)-containing gas onto a substrate and then forming a plasma of a helium (He) or germanium (Ge)-containing gas and treating the substrate, impurities inside the thin film can be removed, thereby suppressing leakage current and promoting densification of the thin film, as well as improving the quality of the thin film.

Claims

1. Step of bringing the substrate into the chamber; and A step of forming a titanium dioxide (TiO2) layer on the substrate; The step of forming the titanium dioxide (TiO2) layer is: A step of supplying a titanium (Ti) containing gas onto the above substrate; A step of supplying an oxygen (O) containing gas onto the substrate; and A method for forming a thin film, comprising: forming a plasma of a helium (He) or germanium (Ge) containing gas on the substrate.

2. In claim 1, After the step of supplying the titanium (Ti) containing gas, A method for forming a thin film, comprising: forming a plasma of a helium (He) or germanium (Ge) containing gas on the substrate.

3. In claim 1, A method for forming a thin film, wherein the above titanium (Ti) containing gas includes TiCl4 gas or Star-Ti gas.

4. In claim 1, A thin film forming method in which the step of forming the above titanium dioxide (TiO2) layer is repeated multiple times.

5. In claim 1, The step of forming plasma of the above helium (He) or germanium (Ge) containing gas is: A method for forming a thin film by supplying at least one of an argon (Ar)-containing gas, a hydrogen (H)-containing gas, a helium (He)-containing gas, and a germanium (Ge)-containing gas together with the above helium (He) or germanium (Ge)-containing gas to form a plasma.

6. In claim 1, After the step of forming the titanium dioxide (TiO2) layer, A method for forming a thin film further comprising a step of forming a high-k dielectric layer or a strontium oxide (SrO) layer on the titanium dioxide (TiO2) layer.

7. In claim 6, A thin film forming method in which the step of forming the titanium dioxide (TiO2) layer and the step of forming the strontium oxide (SrO) layer are repeated multiple times.

8. In claim 1, The step of introducing the above substrate is a thin film forming method of introducing a substrate on which a ruthenium oxide (RuO2) layer is formed.

9. In claim 8, A method for forming a thin film having a rutile structure, wherein the above ruthenium oxide (RuO2) layer has a rutile structure.

10. In claim 1, A thin film forming method further comprising a step of forming a ruthenium oxide (RuO2) layer on the substrate between the step of introducing the substrate and the step of forming the titanium dioxide (TiO2) layer.

11. In claim 1, A method for forming a thin film, further comprising: after the step of forming the titanium dioxide (TiO2) layer, a step of forming a thin film of at least one of hafnium (Hf), aluminum (Al), magnesium (Mg), yttrium (Y), zirconium (Zr), gadolinium (Gd), and lanthanum (La), or an oxide film or nitride film of at least one of these, on the titanium dioxide (TiO2) layer.

12. In claim 1, The step of forming plasma of the above helium (He) or germanium (Ge) containing gas is: A method for forming a thin film by supplying an oxygen (O)-containing gas together with the above helium (He) or germanium (Ge)-containing gas to form a plasma.

Images