Method for forming thin films

Abstract

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 gallium nitride thin film, the method for forming a thin film according to an embodiment of the present invention includes the steps of: loading a substrate into a processing space of a chamber; and forming a gallium nitride thin film on the substrate, the step of forming the gallium nitride thin film including the steps of supplying a source gas containing gallium onto the substrate, supplying a reaction gas containing nitrogen onto the substrate, and activating and supplying a post-treatment gas containing hydrogen onto the substrate to which the reaction gas has been supplied.

Description

Technical Field

[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 gallium nitride thin film.

Background Art

[0002] A thin film transistor (TFT) is used as a switching circuit in a semiconductor device or a display device. The active layer of such a thin film transistor forms a channel region between a gate electrode, a source electrode, and a drain electrode.

[0003] Conventionally, the active layer of a thin film transistor has been formed using amorphous silicon or crystalline silicon. However, when crystalline silicon is used as the active layer, the reaction rate is relatively slow, and since it is inevitable to use a glass substrate as the substrate for forming the active layer, it has the disadvantages of not only being heavy but also not being able to be used as a flexible display device because it is not flexible. For this reason, efforts are being actively made to use a gallium nitride thin film having a high carrier concentration and excellent electrical conductivity in order to realize a high-speed element, that is, to improve mobility, as the active layer of a thin film transistor.

[0004] In general, a metal organic chemical vapor deposition (MOCVD) method is used to form a gallium nitride thin film. In such a metal organic chemical vapor deposition method, a gallium nitride thin film is deposited while adjusting the temperature of the substrate to a high temperature of about 1200°C. That is, when the substrate is maintained at a high temperature of about 1200°C, it becomes possible to deposit a gallium nitride thin film on the substrate.

[0005] However, forming a gallium nitride thin film while the substrate is heated to a high temperature in this manner can cause damage to the substrate or the thin film formed on it. This can degrade the function of thin-film transistors or cause malfunctions, and in particular, it can significantly reduce the quality and reliability of semiconductor elements and display devices that require stable switching operation. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Republic of Korea Published Patent No. 10-2017-0120443 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] This invention provides a method for forming a thin film that can form a gallium nitride thin film at low temperatures. [Means for solving the problem]

[0008] A method for forming a thin film according to an embodiment of the present invention includes the steps of: introducing a substrate into a processing space of a chamber; forming a gallium nitride thin film on the substrate; wherein the step of forming the gallium nitride thin film includes the steps of: supplying a source gas containing gallium onto the substrate; supplying a reaction gas containing nitrogen onto the substrate; and activating and supplying a post-treatment gas containing hydrogen onto the substrate.

[0009] The step of forming the gallium nitride thin film may be carried out by controlling the temperature of the processing space to 600°C or lower.

[0010] The step of supplying the reaction gas may involve supplying the reaction gas onto the substrate via a supply route different from that of the source gas.

[0011] The step of supplying the reaction gas may be performed by activating the reaction gas before supplying it, and the step of forming the gallium nitride thin film may be performed by controlling the temperature of the processing space to 350°C or lower.

[0012] The step of forming the gallium nitride thin film may further include, before the step of supplying the reaction gas, activating and supplying a hydrogen-containing pretreatment gas onto the substrate.

[0013] The step of forming the gallium nitride thin film may further include a step of purging the source gas before the step of activating and supplying the pretreatment gas.

[0014] The step of forming the gallium nitride thin film may further include a step of purging the reaction gas before the step of activating and supplying the post-treatment gas.

[0015] The source gas may contain trimethylgallium (TMGa) gas, the reaction gas may contain ammonia (NH3) gas, and the post-treatment gas may contain hydrogen (H2) gas.

[0016] The step of forming the gallium nitride thin film further includes a step of forming a buffer layer on the substrate before the step of forming the gallium nitride thin film, and the buffer layer may comprise an aluminum nitride thin film.

[0017] The step of forming the gallium nitride thin film may be performed in multiple process cycles, each cycle including the steps of supplying the source gas, supplying the reaction gas, and activating and supplying the post-treatment gas.

[0018] The step of forming the gallium nitride thin film further includes a step of supplying a dopant gas onto the substrate, and the step of supplying the dopant gas may supply the dopant gas simultaneously with the step of supplying the source gas or after the step of supplying the source gas.

[0019] The dopant gas includes a p-type dopant gas or an n-type dopant gas. The p-type dopant gas may include bis-cyclopentadienylmagnesium (Cp2Mg) gas, and the n-type dopant gas may include diisopropylaminosilane (DIPAS) gas.

Advantages of the Invention

[0020] According to an embodiment of the present invention, a gallium nitride thin film can be formed by a low-temperature process to prevent the substrate or the gallium nitride thin film from being damaged by high-temperature heat. In addition, the time for raising the temperature of the substrate to form the gallium nitride thin film can be reduced, thereby shortening the manufacturing time of the semiconductor device or the display device.

[0021] Further, according to an embodiment of the present invention, a gallium nitride thin film having a high charge concentration and an excellent crystal structure with excellent electrical conductivity can be formed by a low-temperature process.

Brief Description of the Drawings

[0022] [Figure 1] A diagram schematically showing a vapor deposition apparatus according to an embodiment of the present invention. [Figure 2] A diagram schematically showing a method for forming a thin film according to an embodiment of the present invention. [Figure 3] A diagram for explaining a process cycle of a method for forming a thin film according to an embodiment of the present invention. [Figure 4] A diagram schematically showing a state of a thin film transistor manufactured according to an embodiment of the present invention. [Figure 5] A diagram schematically showing a state of a semiconductor device manufactured according to an embodiment of the present invention.

Embodiments for Carrying Out the Invention

[0023] Hereinafter, embodiments of the present invention will be described in more detail based on the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and can be embodied in various different forms. The following embodiments are provided only to make the disclosure of the present invention complete and to fully inform those with ordinary knowledge of the scope of the invention.

[0024] Throughout the specification of the present application, when referring to a component being "above" another component, such as a layer, film, region, or substrate, etc., it may be interpreted that the certain component directly contacts "above" the other component, or there may be additional components intervening between them.

[0025] Also, relative terms such as "upper" or "lower" may be used herein to describe the relative relationship of an element with respect to other elements as shown in the drawings. The relative terms are intended to include other directions of the element in addition to the direction depicted in the drawings. The drawings may be shown exaggerated for the purpose of explaining the invention in detail, and in the figures, the same reference numerals indicate the same elements.

[0026] FIG. 1 is a diagram schematically showing a vapor deposition apparatus according to an embodiment of the present invention.

[0027] Referring to Figure 1, an embodiment of the present invention is an apparatus for depositing a thin film, i.e., a gallium nitride thin film, and comprises a chamber 10, a substrate support section 20 provided within the chamber 10 for supporting a substrate disposed within the chamber 10, a gas injection section 30 provided within the chamber 10 so as to be opposite the substrate support section 20 for injecting process gas toward the substrate support section 20, and an RF power supply 50 for supplying power to generate plasma within the chamber 10. The deposition apparatus may further comprise a gas supply section 40 for supplying gas to the gas injection section 30, and in addition to these, it may further comprise a control section (not shown) for controlling the RF power supply 50. Here, the gas injection section 30 is formed by separating a first gas supply route for supplying a first gas, for example, a source gas, and a second gas supply route for supplying a second gas, for example, a reaction gas.

[0028] The chamber 10 provides a predetermined processing space and maintains it in an airtight manner. The chamber 10 may comprise a body 12 having a predetermined processing space with a generally circular or rectangular flat surface and side walls extending upward from the flat surface, and a lid 14 positioned on the body 12 in a generally circular or rectangular shape to maintain the chamber 10 in an airtight manner. However, the chamber 10 is not limited in any way and can be manufactured in various shapes corresponding to the shape of the substrate.

[0029] An exhaust port (not shown) is 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. The exhaust pipe may also be connected to an exhaust device (not shown). A vacuum pump such as a turbomolecular pump can be used as the exhaust device. Therefore, the inside of the chamber 10 can be evacuated 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 arranged not only on the lower surface of the chamber 10, but also on the side of the chamber 10 below the substrate support section 20, which will be described later. It goes without saying that in order to shorten the exhaust time, a number of exhaust pipes and associated exhaust devices may be further arranged.

[0030] On the other hand, a substrate disposed in the chamber 10 for the thin film formation process may be placed on the substrate support section 20. Here, the substrate may be a variety of substrates for forming a gallium nitride (GaN) thin film. For example, the substrate may be a sapphire substrate, a glass substrate, or a silicon wafer. The substrate support section 20 may be equipped with, for example, an electrostatic chuck to hold the substrate by electrostatic force, or the substrate may be supported by vacuum suction or mechanical force.

[0031] The substrate support portion 20 may be provided in a shape corresponding to the shape of the substrate, for example, a circular or square shape. The substrate support portion 20 may include a substrate support base 22 on which the substrate is placed and a lifter 24 positioned below the substrate support base 22 to raise and lower the substrate support base 22. Here, the substrate support base 22 may be made larger than the substrate, and the lifter 24 is provided to support at least one area of ​​the substrate support base 22, for example, the center, so that when a substrate is placed on the substrate support base 22, the substrate support base 22 can be moved closer to the gas injection unit 30. In addition, a heater (not shown) may be provided inside the substrate support base 22. The heater generates heat at a predetermined temperature to heat the substrate support base 22 and the substrate placed on the substrate support base 22 so that a thin film is deposited uniformly on the substrate.

[0032] The gas supply unit 40 may be arranged to penetrate the lid 14 of the chamber 10, and may include a first gas supplyer 42 and a second gas supplyer 44 to supply the first gas and the second gas to the gas injection unit 30, respectively. In the thin film deposition process, the first gas may include a source gas, and the second gas may include a reaction gas. However, the first gas supplyer 42 and the second gas supplyer 44 do not necessarily supply only one type of gas, and the first gas supplyer 42 and the second gas supplyer 44 may be configured to supply multiple types of gases simultaneously, or to supply a gas selected from among multiple types of gases.

[0033] For example, the first gas supplier 42 may be configured to supply a gas containing gallium (Ga) as the source gas, and the second gas supplier 44 may supply a gas containing nitrogen (N) as the reaction gas. Here, the source gas, i.e., the gas containing gallium, may contain trimethylgallium (TMGa) gas, and the reaction gas, i.e., the gas containing nitrogen, may contain ammonia (NH3) gas.

[0034] The gas injection unit 30 is disposed inside the chamber 10, for example, on the lower surface of the lid 14. Inside the gas injection unit 30, a first gas supply route is formed for injecting and supplying a first gas onto the substrate, and a second gas supply route is formed for injecting and supplying a second gas onto the substrate. The first gas supply route and the second gas supply route may be formed to be independent and separate from each other so that the first gas and the second gas are supplied to the substrate separately without mixing within the gas injection unit 30.

[0035] The gas injection unit 30 may include an upper frame 32 and a lower frame 34. Here, the upper frame 32 is detachably coupled to the lower surface of the lid 14, and a part of its upper surface, for example, the center of the upper surface, is separated from the lower surface of the lid 14 by a predetermined distance. This allows the first gas from the first gas supply unit 42 to spread in the space between the upper surface of the upper frame 32 and the lower surface of the lid 14. The lower frame 34 is disposed on the lower surface of the upper frame 32 at a certain distance. This allows the second gas from the second gas supply unit 44 to spread in the space between the upper surface of the lower frame 34 and the lower surface of the upper frame 32. It goes without saying that the upper frame 32 and the lower frame 34 may be connected along their outer circumferential surfaces to form a partitioned space inside and be formed as a single unit, or they may be structured to have their outer circumferential surfaces sealed by a separate sealing member.

[0036] The first gas supply route may be configured such that the first gas from the first gas supply unit 42 spreads in the space between the lower surface of the lid 14 and the upper frame 32, and is supplied to the inside of the chamber 10 by penetrating the upper frame 32 and the lower frame 34. The second gas supply route may be configured such that the second gas from the second gas supply unit 44 spreads in the space between the lower surface of the upper frame 32 and the upper surface of the lower frame 34, and is supplied to the inside of the chamber 10 by penetrating the lower frame 34. The first gas supply route and the second gas supply route do not have to communicate with each other, thereby allowing the first gas and the second gas to be supplied separately from the gas supply unit 40 through the gas injection unit 30 to the inside of the chamber 10.

[0037] A first electrode 38 may be disposed on the lower surface of the lower frame 34, and a second electrode 36 may be disposed on the lower side of the lower frame 34 and outside the first electrode 38 at a predetermined distance apart. In this case, the lower frame 34 and the second electrode 36 may be formed by being connected along their outer surfaces, and it goes without saying that the outer surfaces may be sealed by a separate sealing member.

[0038] In this manner, when the first electrode 38 and the second electrode 36 are arranged, the first gas can be injected onto the substrate through the first electrode 38, and the second gas can be injected onto the substrate through the separation space between the first electrode 38 and the second electrode 36.

[0039] RF power may be applied from the RF power supply 50 to either the lower frame 34 or the second electrode 36. Figure 1 shows an example structure in which the lower frame 34 is grounded and RF power is applied to the second electrode 36. When the lower frame 34 is grounded, the first electrode 38 disposed on the lower surface of the lower frame 34 is also grounded. Therefore, when the RF power supply 50 is supplied to the second electrode 36, a first activation region, i.e., a first plasma region, is formed between the gas injection unit 30 and the substrate support unit 20, and a second activation region, i.e., a second plasma region, can be formed between the first electrode 38 and the second electrode 36.

[0040] Therefore, when the second gas is injected through the separation space between the first electrode 38 and the second electrode 36, the second gas is activated between the first electrode 38 and the second electrode 36, which corresponds to the inside of the gas injection unit 30, that is, over the region from the second plasma region to the first plasma region. Thus, in the deposition apparatus according to the embodiment of the present invention, the second gas can be activated inside the gas injection unit 30 and injected onto the substrate. Furthermore, by forming a first gas supply route for supplying the first gas and a second gas supply route for supplying the second gas separately, for example, the source gas and reaction gas can be distributed and injected via an optimal supply route for deposition of a thin film.

[0041] The thin film formation method of the present invention will be described in detail below with reference to Figures 2 and 3. In describing the thin film formation method according to the embodiment of the present invention, explanations that overlap with the previously mentioned explanation of the deposition apparatus will be omitted.

[0042] Figure 2 is a schematic diagram showing a thin film formation method according to an embodiment of the present invention, and Figure 3 is a diagram illustrating the process cycle of the thin film formation method according to an embodiment of the present invention.

[0043] Referring to Figures 2 and 3, the method for forming a thin film according to an embodiment of the present invention includes the steps of: bringing a substrate into the processing space of a chamber 10 (S100); and forming a gallium nitride thin film on the substrate (S200). The step of forming the gallium nitride thin film (S200) includes the steps of: supplying a source gas containing gallium onto the substrate (S210); supplying a reaction gas containing nitrogen onto the substrate (S240); and activating and supplying a post-treatment gas containing hydrogen onto the substrate (S260).

[0044] Step S100 involves loading a substrate into the processing space of the chamber 10. The substrate loaded into the processing space may be placed on the substrate support section 20. As mentioned above, the substrate may be any one of the following: a sapphire substrate, a glass substrate, or a silicon wafer for forming a gallium nitride thin film. Step S100 may also involve loading a substrate on which a predetermined functional layer has been formed. For example, in step S100, the substrate loaded may be one on which a gate electrode is formed on its upper surface, and a gate insulating film is formed on the substrate and the gate electrode so as to cover the gate electrode. The substrate support section 20 may be equipped with, for example, an electrostatic chuck to hold the substrate by electrostatic force, or it may be supported by vacuum suction or mechanical force.

[0045] The step of forming a gallium nitride thin film (S200) involves forming a gallium nitride thin film on a substrate brought into the processing space of chamber 10. Here, the gallium nitride (GaN) thin film may form at least a portion of the active layer of a thin-film transistor (TFT) used as a switching circuit in semiconductor devices and display devices. For example, the gallium nitride thin film may form a channel region between the gate electrode of the thin-film transistor and the source and drain electrodes.

[0046] In embodiments of the present invention, the step of forming a gallium nitride thin film (S200) may be carried out in a low-temperature process at 600°C or lower. That is, the step of forming a gallium nitride thin film (S200) may be carried out by controlling the temperature of the processing space of the chamber 10 to 250°C or higher and 600°C or lower. The gallium nitride thin film may be formed in a low-temperature process of 250°C to 600°C by an atomic layer growth (ALG) process, and the details of this will be explained below.

[0047] In the step of supplying the source gas (S210), a source gas containing gallium is supplied onto the substrate. Here, in the step of supplying the source gas (S210), the source gas containing gallium is supplied onto the substrate via the first gas supply route of the deposition apparatus described above. At this time, the source gas containing gallium may also contain trimethylgallium (TMGa) gas, which mainly contains gallium. In the step of supplying the source gas (S210), the source gas containing gallium is sprayed onto the substrate and adsorbed. At this time, the step of supplying the source gas (S210) may be performed without supplying power.

[0048] Although not shown in Figures 2 and 3, the step of supplying a dopant gas onto the substrate may be performed simultaneously with or after the step of supplying the source gas (S210). As mentioned above, the gallium nitride thin film forms at least a portion of the active layer, and such an active layer needs to be formed as either a p-type active layer or an n-type active layer, depending on the type. Therefore, the step of supplying a p-type dopant gas or an n-type dopant gas onto the substrate may be performed simultaneously with or after the step of supplying the source gas (S210). The dopant gas may be supplied via at least one of the first gas supply route and the second gas supply route, where the p-type dopant gas may contain bis-cyclopentadienylmagnesium (Cp2Mg) gas, and the n-type dopant gas may contain diisopropylaminosilane (DIPAS) gas. In this way, by supplying a p-type dopant gas or an n-type dopant gas simultaneously with the source gas supply step (S210), or after the source gas supply step (S210), it becomes possible to form a p-type gallium nitride thin film or an n-type gallium nitride thin film.

[0049] A step of purging the source gas (S220) may be performed after the step of supplying the source gas (S210). In the step of purging the source gas (S220), any source gas remaining in the processing space of the chamber 10 can be removed. Such a step of purging the source gas (S220) may be performed by supplying an inert gas, such as argon (Ar) gas, to the processing space, and the argon (Ar) gas may be supplied via at least one of the first gas supply route and the second gas supply route. In this case, the RF power supply 50 does not need to be supplied while the source gas is being purged.

[0050] After the step of purging the source gas (S220), a step of activating and supplying a hydrogen-containing pretreatment gas onto the substrate (S230) may be performed. In the step of activating and supplying the pretreatment gas (S230), a hydrogen-containing pretreatment gas, for example, hydrogen (H2) gas, is supplied onto the substrate, and an RF power supply 50 is supplied to generate hydrogen plasma on the substrate. Here, the hydrogen (H2) gas can be supplied via at least one of the first gas supply route and the second gas supply route. In this way, if the step of activating and supplying a hydrogen-containing pretreatment gas (S230) is performed after the raw material has been adsorbed onto the substrate by the supply of the source gas, impurities contained in the raw material adsorbed onto the substrate can be removed by the hydrogen plasma, and the raw material can be adsorbed more firmly onto the substrate.

[0051] Following the step of activating and supplying a hydrogen-containing pretreatment gas (S230), the step of supplying a reaction gas (S240) is performed. In the step of supplying the reaction gas (S240), a reaction gas containing nitrogen is supplied onto the substrate. In this step of supplying the reaction gas (S240), the reaction gas containing nitrogen is supplied onto the substrate via the second gas supply route of the deposition apparatus described above. At this time, the reaction gas containing nitrogen may also contain ammonia (NH3) gas, which contains nitrogen as its main component. When the reaction gas is supplied onto the substrate on which the raw material material is adsorbed, the raw material material reacts with the reactants contained in the reaction gas.

[0052] In this case, during the step of supplying the reaction gas (S240), an RF power supply 50 may be supplied to the processing space to activate the reaction gas and generate plasma in order to effectively react the nitrogen component with the gallium component. By activating the reaction gas during the step of supplying the reaction gas (S240), the supplied nitrogen-containing gas is activated by nitrogen radicals and reacts with the gallium component, making it possible to form a gallium nitride thin film on the substrate at a lower process temperature. That is, when the reaction gas is activated and supplied onto the substrate, the step of forming the gallium nitride thin film (S200) may be carried out by controlling the processing space of the chamber 10 to a low temperature of 250°C or higher and 350°C or lower.

[0053] Following the step of supplying the reaction gas (S240), a step of purging the reaction gas (S250) may be performed. In the step of purging the reaction gas (S250), any reaction gas remaining in the processing space of the chamber 10 can be removed. This step of purging the reaction gas (S250) may be performed by supplying an inert gas, such as argon (Ar) gas, to the processing space, similar to the step of purging the source gas (S220), and the argon (Ar) gas may be supplied via at least one of the first gas supply route and the second gas supply route.

[0054] After the step of purging the reaction gas (S250), a step of activating and supplying a hydrogen-containing post-treatment gas onto the substrate (S260) may be performed. In the step of activating and supplying the post-treatment gas (S260), a hydrogen-containing post-treatment gas, for example, hydrogen (H2) gas, is supplied onto the substrate, and an RF power supply 50 is supplied to generate hydrogen plasma on the substrate. Here, the hydrogen (H2) gas may be supplied via at least one of the first gas supply route and the second gas supply route.

[0055] After a gallium nitride thin film is formed on the substrate by injecting a source gas and a reaction gas, if a hydrogen-containing post-treatment gas is activated and supplied onto the substrate, the amorphous gallium nitride thin film can be crystallized by hydrogen plasma. When a gallium nitride thin film is formed simply by injecting a source gas and a reaction gas, the gallium nitride thin film is deposited on the substrate in an amorphous state. However, as in the embodiment of the present invention, if a step of activating and supplying a hydrogen-containing post-treatment gas onto the substrate (S260) is performed after the step of purging the reaction gas (S250), the amorphous gallium nitride thin film can be crystallized to have a polycrystalline or single-crystal structure. Furthermore, if the temperature inside the chamber 10 or the substrate is low, for example, at a low temperature of 250°C to 600°C, or if the reaction gas is activated and supplied, the gallium nitride thin film may be formed at an extremely low temperature of 250°C to 600°C. Furthermore, it goes without saying that the step of activating and supplying a hydrogen-containing post-treatment gas onto the substrate (S260) effectively removes impurities remaining inside the chamber 10 and impurities contained in the gallium nitride thin film.

[0056] In the thin film formation method according to the embodiment of the present invention, the process cycle including the step of supplying a source gas (S210) and the step of supplying a reaction gas (S240) may be performed multiple times. At this time, at least one of the steps of activating and supplying a hydrogen-containing pretreatment gas (S230) and activating and supplying a posttreatment gas (S260) may be included in each process cycle, as shown in Figure 3, and the step of activating and supplying a pretreatment gas (S230) and the step of activating and supplying a posttreatment gas (S260) may be performed in each process cycle, or at least one of the steps of activating and supplying a pretreatment gas (S230) and activating and supplying a posttreatment gas (S260) may be included in a part of each process cycle and performed only in a part of the process cycle.

[0057] For example, if the steps of activating and supplying a pretreatment gas (S230) and activating and supplying a posttreatment gas (S260) are included in each process cycle, then in the thin film formation method according to the embodiment of the present invention, the steps of supplying a source gas (S210), purging the source gas (S220), activating and supplying a hydrogen-containing pretreatment gas (S230), supplying a reaction gas (S240), purging the reaction gas (S250), and activating and supplying a posttreatment gas (S260) constitute one process cycle, and this process cycle may be repeated until a gallium nitride thin film of a desired thickness is formed on the substrate.

[0058] Figure 4 is a schematic diagram showing a thin-film transistor manufactured according to an embodiment of the present invention. Specifically, Figure 4 shows a thin-film transistor manufactured by forming an active layer having a gallium nitride thin film using a thin film formation method according to an embodiment of the present invention.

[0059] Referring to Figure 4, a thin-film transistor according to one embodiment of the present invention comprises a gate electrode 110, a source electrode 142a and a drain electrode 144a disposed above or below the gate electrode 110 and separated from each other in the horizontal direction, an active layer 130 disposed between the gate electrode 110, the source electrode 142a and the drain electrode 144a, and a gate insulating film 120 disposed between the gate electrode 110 and the active layer 130, wherein at least a portion of the active layer 130 is formed as a gallium nitride thin film.

[0060] Herein, the thin-film transistor according to one embodiment of the present invention may be a bottom-gate type thin-film transistor, as shown in Figure 4, comprising a gate electrode 110 formed on a substrate 100, a gate insulating film 120 formed on the gate electrode 110, an active layer 130 formed on the gate insulating film 120, and a source electrode 142 and a drain electrode 144 formed on the active layer 130 so as to be separated from each other. However, it goes without saying that this is also applicable to a top-gate type thin-film transistor in which the gate electrode 110 is located on top.

[0061] Here, the substrate 100 may include a wide variety of substrates for forming a gallium nitride (GaN) thin film. For example, the substrate may be any one of the following: a sapphire substrate, a glass substrate, or a silicon wafer. Moreover, it goes without saying that a wide variety of other substrates, such as transparent substrates or flexible substrates, can also be used.

[0062] The gate electrode 110 can be formed using a conductive material, but may also be formed from at least one metal or alloy containing these, such as aluminum (Al), neodymium (Nd), silver (Ag), chromium (Cr), titanium (Ti), tantalum (Ta), molybdenum (Mo), and copper (Cu). Furthermore, the gate electrode 110 may be formed not only as a single layer but also as a multilayer consisting of multiple metal layers. That is, it may be formed as a two-layer structure including a metal layer of chromium (Cr), titanium (Ti), tantalum (Ta), or molybdenum (Mo) with excellent physicochemical properties, and an aluminum (Al), silver (Ag), or copper (Cu) metal layer with low resistivity.

[0063] The gate insulating film 120 is formed on the gate electrode 110. That is, the gate insulating film 120 may be formed on a substrate 100 including the upper and side portions of the gate electrode 110. The gate insulating film 120 may be formed from a thin film using one or more insulating materials selected from silicon oxide (SiO2), silicon nitride (SiN), high-K dielectric, and aluminum oxide (Al2O3), which have excellent adhesion to metallic materials and excellent dielectric breakdown voltage. Here, the high-K dielectric is a dielectric having a higher dielectric constant than silicon oxide (SiO2), and may include hafnium oxide (HfO2), zirconium oxide (ZrO2), etc.

[0064] The active layer 130 is formed on the gate insulating film 120 and is formed so that at least a portion of it overlaps with the gate electrode 110. The active layer 130 may be formed with a gallium nitride thin film, but such a gallium nitride thin film can be formed by a thin film formation method according to an embodiment of the present invention, which includes the steps of bringing a substrate into the processing space of the chamber 10 (S100) and forming a gallium nitride thin film on the substrate (S200), and the step of forming the gallium nitride thin film (S200) includes the steps of supplying a source gas containing gallium onto the substrate (S210), supplying a reaction gas containing nitrogen onto the substrate (S240), and activating and supplying a post-treatment gas containing hydrogen onto the substrate to which the reaction gas has been supplied (S260).

[0065] Although not shown in Figure 4, such a gallium nitride thin film may be formed directly on the gate insulating film 120, but it goes without saying that a buffer layer may be formed on the gate insulating film and the gallium nitride thin film may be formed on the buffer layer. Here, the buffer layer is a layer formed before the gallium nitride thin film in order to form the gallium nitride thin film, and may be a seed layer that assists in the more effective crystallization of the gallium nitride thin film. In other words, the buffer layer may be a seed layer that makes the gallium nitride thin film crystallize more easily when forming the gallium nitride thin film. Such a buffer layer may be formed from an aluminum nitride (AlN) thin film and can be formed by a wide variety of thin film formation processes such as atomic layer deposition and chemical vapor deposition.

[0066] The source electrode 142 and drain electrode 144 are formed on top of the active layer 130, i.e., the gallium nitride thin film, and may be formed so that they partially overlap with the gate electrode 110, and the source electrode 142 and drain electrode 144 are separated from each other with the gate electrode 110 in between. The source electrode 142 and drain electrode 144 may be formed using the same material and the same process, or they may be formed using a conductive material, but for example they may be formed from at least one metal or alloy containing these, such as aluminum (Al), neodymium (Nd), silver (Ag), chromium (Cr), titanium (Ti), tantalum (Ta), and molybdenum (Mo). In other words they may be formed from the same material as the gate electrode 110, or from a different material than the gate electrode 110. It goes without saying that the source electrode 142 and drain electrode 144 may be formed not only as a single layer, but also as a multilayer of multiple metal layers.

[0067] Figure 5 is a schematic diagram showing a semiconductor device manufactured according to an embodiment of the present invention. Specifically, Figure 5 shows a semiconductor device manufactured by forming at least one of a p-type active layer comprising a p-type gallium nitride thin film and an n-type active layer comprising an n-type gallium nitride thin film using a thin film formation method according to an embodiment of the present invention.

[0068] Referring to Figure 5, a semiconductor device according to one embodiment of the present invention comprises a substrate 100 having a first region A and a second region B, a first thin-film transistor disposed in the first region A and having a p-type active layer 130a, and a second thin-film transistor disposed in the second region B and having an n-type active layer 130b.

[0069] Herein, the semiconductor device according to one embodiment of the present invention may include a bottom-gate type thin-film transistor in which the active layer is located above the gate electrode, as shown in Figure 5. However, it goes without saying that the semiconductor device may also include a top-gate type thin-film transistor in which the gate electrode is located above the active layer.

[0070] Here, the substrate 100 is directly subject to the same conditions described above in relation to the thin-film transistor in Figure 4. On the other hand, the substrate 100 has a first region A and a second region B that is different from the first region A. Here, the first region A means the region on the substrate 100 on which the first thin-film transistor, described later, is formed, and the second region B means the region on the substrate 100 on which the second thin-film transistor, described later, is formed. In Figure 5, the first region A and the second region B are shown to be adjacent to each other, but it goes without saying that the first region A and the second region B can be arranged with a predetermined distance between them, or they can have various positions defined on the substrate 100 for forming the first and second thin-film transistors.

[0071] The first thin-film transistor is disposed in a first region A of the substrate 100 and has a p-type active layer 130a. That is, the first thin-film transistor may be a p-type thin-film transistor having a p-type active layer 130a as its active layer. The second thin-film transistor is disposed in a second region B of the substrate 100 and has an n-type active layer 130b. That is, the second thin-film transistor may be an n-type thin-film transistor having an n-type active layer 130b as its active layer.

[0072] Here, the first thin-film transistor and the second thin-film transistor each comprise a first gate electrode 110a and a second gate electrode 110b, a gate insulating film 120, a first source electrode 142a and a first drain electrode 144a and a second source electrode 142b and a second drain electrode 144b, respectively. As described above, the semiconductor device according to one embodiment of the present invention comprises a bottom-gate type thin-film transistor. Therefore, the first thin-film transistor may comprise a first gate electrode 110a formed on a substrate 100, a gate insulating film 120 formed on the first gate electrode 110a, a p-type active layer 130a formed on the gate insulating film 120, and a first source electrode 142a and a first drain electrode 144a formed on the p-type active layer 130a so as to be separated from each other. The second thin-film transistor also includes a second gate electrode 110b formed on the substrate 100, a gate insulating film 120 formed on the second gate electrode 110b, an n-type active layer 130b formed on the gate insulating film 120, and a second source electrode 142b and a second drain electrode 144b formed on the n-type active layer 130b so as to be separated from each other. Here, as shown in Figure 5, the gate insulating film 120 may be shared by the first thin-film transistor and the second thin-film transistor.

[0073] The first gate electrode 110a and the second gate electrode 110b may be arranged such that at least a portion of them overlap the p-type active layer 130a and the n-type active layer 136, respectively. Regarding the first gate electrode 110a and the second gate electrode 110b, the same explanations described above in relation to the thin-film transistor in Figure 4 are applicable, so redundant explanations are omitted.

[0074] The gate insulating film 120 is formed on top of the first gate electrode 110a and the second gate electrode 110b. That is, the gate insulating film 120 may be formed on the substrate 100 on which the first gate electrode 110a and the second gate electrode 110b are formed. The same explanation as above regarding the gate insulating film 120 in relation to the thin-film transistor in Figure 4 is applicable, so redundant explanations will be omitted.

[0075] A p-type active layer 130a is formed between the gate insulating film 120 and the first source electrode 142a and the first drain electrode 144a as the active layer of the first thin-film transistor, and an n-type active layer 130b is formed between the gate insulating film 120 and the second source electrode 142b and the second drain electrode 144b as the active layer of the second thin-film transistor.

[0076] Here, the p-type active layer 130a may comprise a p-type gallium nitride thin film. That is, the p-type active layer 130a may comprise a magnesium-doped p-type gallium nitride thin film. On the other hand, the n-type active layer 130b may comprise an n-type gallium nitride thin film. That is, the n-type active layer 130b may comprise a silicon-doped n-type gallium nitride thin film. However, in addition to the n-type gallium nitride thin film, the n-type active layer 130b may also comprise at least one of the following: Zn-based oxides (ZnO, binary, ternary, or quaternary oxides containing Zn, etc.), In-based oxides (InO, binary, ternary, or quaternary oxides containing In, etc.), and Ga-based oxides (GaO, binary, ternary, or quaternary oxides containing Ga, etc.). In addition to these, the n-type active layer 130b may also contain indium zinc oxide (IZO), In-Zn-O or indium gallium zinc oxide (IGZO), and In-Ga-Zn-O.

[0077] On the other hand, in a semiconductor device according to one embodiment of the present invention, the p-type active layer 130a and the n-type active layer 130b may each be formed in a multilayer structure. That is, the p-type active layer 130a may be formed in a multilayer structure comprising a first p-type active layer and a second p-type active layer, and the n-type active layer 130b may be formed in a multilayer structure comprising a first n-type active layer and a second n-type active layer. In this case, the first p-type active layer may comprise a magnesium-undoped gallium nitride thin film, and the second p-type active layer may comprise a magnesium-doped gallium nitride thin film. Furthermore, the first n-type active layer may comprise a silicon-undoped gallium nitride thin film, and the second n-type active layer may comprise a silicon-doped gallium nitride thin film.

[0078] Herein, in a semiconductor device according to one embodiment of the present invention, the p-type active layer 130a and the n-type active layer 130b may be formed by the thin film formation method according to the embodiment of the present invention described above. That is, the p-type active layer 130a and the n-type active layer 130b may be formed by comprising a doped gallium nitride thin film, and such a doped gallium nitride thin film may be formed by a thin film formation method that includes, as described above, the step of bringing a substrate into the processing space of the chamber 10 (S100) and the step of forming a gallium nitride thin film on the substrate (S200), and the step of forming the gallium nitride thin film (S200) may be formed by a thin film formation method that includes the step of supplying a source gas containing gallium onto the substrate (S210), supplying a doped gas onto the substrate together with the source gas or after the supply of the source gas, supplying a reaction gas containing nitrogen onto the substrate (S240), and activating and supplying a post-treatment gas containing hydrogen onto the substrate to which the reaction gas has been supplied (S260).

[0079] The first source electrode 142a and the first drain electrode 144a are formed on top of the p-type active layer 130a, and the second source electrode 142b and the second drain electrode 144b are formed on top of the n-type active layer 130b. In this case, the first source electrode 142a and the first drain electrode 144a may be formed apart from each other so that at least a portion of them is connected to the p-type active layer 130a, and the second source electrode 142b and the second drain electrode 144b may be formed apart from each other so that at least a portion of them is connected to the n-type active layer 130b. The same information described above in relation to the thin-film transistor in Figure 4 can be applied to the first source electrode 142a and the first drain electrode 144a and the second source electrode 142b and the second drain electrode 144b, so redundant explanations will be omitted.

[0080] A passivation layer 150 may be formed on the first source electrode 142a and the first drain electrode 144a, and on the second source electrode 142b and the second drain electrode 144b. That is, the passivation layer 150 may be formed on a gate insulating film 120 comprising a p-type active layer 130a, the first source electrode 142a and the first drain electrode 144a, and an n-type active layer 130b, the second source electrode 142b and the second drain electrode 144b. Here, the passivation layer 150 may be formed to prevent corrosion of the surface of the semiconductor device and to protect the semiconductor device from the external environment, and may be formed using one or more insulating materials from silicon oxide (SiO2) and silicon nitride (SiN).

[0081] Thus, according to the embodiments of the present invention, a gallium nitride thin film can be formed by a low-temperature process, preventing damage to the substrate or the gallium nitride thin film from high temperatures. Furthermore, the time required to heat the substrate for forming the gallium nitride thin film can be reduced, thereby shortening the manufacturing time of semiconductor elements or display devices.

[0082] Furthermore, according to embodiments of the present invention, a gallium nitride thin film having a high charge concentration and a crystalline structure with excellent electrical conductivity can be formed by a low-temperature process.

[0083] Although preferred embodiments of the present invention have been described and illustrated using specific terminology, these terms are merely for the purpose of clearly explaining the present invention, and it is clear that various modifications and changes can be made to the embodiments and described terminology of the present invention without departing from the technical idea and scope of the claims. These modified embodiments should not be understood individually from the idea and scope of the present invention, but should be considered to fall within the scope of the claims of the present invention.

Claims

1. The steps include: loading the substrate into the processing space of the chamber, The steps include forming a gallium nitride thin film on the substrate, Includes, The step of forming the gallium nitride thin film is, The steps include supplying a source gas containing gallium onto the substrate, The step of supplying a reaction gas containing nitrogen onto the substrate, The steps include: activating and supplying a post-treatment gas containing hydrogen onto the substrate; Includes, A gas injection unit is provided inside the chamber. The aforementioned gas injection unit is The upper frame and A lower frame is provided on the lower side of the upper frame, with a first electrode and a second electrode provided on the lower surface, with a predetermined distance between them outside the first electrode. Equipped with, The step of supplying the reaction gas is, A method for forming a thin film, comprising activating the reaction gas inside the gas injection section, which includes a separation space between the first electrode and the second electrode, and injecting it onto the substrate.

2. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 1, wherein the processing space is controlled to a temperature of 600°C or less.

3. The step of supplying the reaction gas is, The method for forming a thin film according to claim 1, wherein the reaction gas is supplied onto the substrate via a supply route different from the source gas.

4. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 1, wherein the processing space is controlled to a temperature of 350°C or less.

5. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 1, further comprising the step of activating and supplying a hydrogen-containing pretreatment gas onto the substrate before the step of supplying the reaction gas.

6. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 5, further comprising the step of purging the source gas before the step of activating and supplying the pretreatment gas.

7. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 1, further comprising the step of purging the reaction gas before the step of activating and supplying the post-treatment gas.

8. The source gas includes trimethylgallium (TMGa) gas. The reaction gas includes ammonia (NH3) gas. The method for forming a thin film according to claim 1, wherein the post-treatment gas includes hydrogen (H2) gas.

9. The step of forming the gallium nitride thin film further includes the step of forming a buffer layer on the substrate before the step of forming the gallium nitride thin film, The method for forming a thin film according to claim 1, wherein the buffer layer comprises an aluminum nitride thin film.

10. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 1, comprising performing a process cycle including the step of supplying the source gas, the step of supplying the reaction gas, and the step of activating and supplying the post-treatment gas multiple times.

11. The step of forming the gallium nitride thin film is, The process further includes the step of supplying a dopant gas onto the substrate, The step of supplying the dopant gas is, The method for forming a thin film according to claim 1, wherein the dopant gas is supplied simultaneously with or after the step of supplying the source gas.

12. The dopant gas includes a p-type dopant gas or an n-type dopant gas. The aforementioned p-type dopant gas contains bis-cyclopentadienylmagnesium (Cp2Mg) gas. The method for forming a thin film according to claim 11, wherein the n-type dopant gas includes diisopropylaminosilane (DIPAS) gas.

13. The steps include: loading the substrate into the processing space of the chamber, The steps include forming a gallium nitride thin film on the substrate, Includes, The step of forming the gallium nitride thin film is, The steps include supplying a source gas containing gallium onto the substrate, The step of supplying a reaction gas containing nitrogen onto the substrate, Includes, The step of forming the gallium nitride thin film is, This process is carried out by controlling the temperature of the processing space to 600°C or lower. A gas injection unit is provided inside the chamber. The aforementioned gas injection unit is The upper frame and A lower frame is provided on the lower side of the upper frame, with a first electrode and a second electrode provided on the lower surface, with a predetermined distance between them outside the first electrode. Equipped with, The step of supplying the reaction gas is, A method for forming a thin film, comprising activating the reaction gas inside the gas injection section, which includes a separation space between the first electrode and the second electrode, and injecting it onto the substrate.

14. The method for forming a thin film according to claim 13, further comprising the step of activating and supplying a hydrogen-containing gas onto the substrate after the step of supplying the source gas.

15. The step of forming the gallium nitride thin film is, The method for forming a thin film according to claim 13, wherein the processing space is controlled to a temperature of 350°C or less.

16. The steps include: loading the substrate into the processing space of the chamber, The steps include forming a gallium nitride thin film on the substrate, Includes, The step of forming the gallium nitride thin film is, The steps include supplying a source gas containing gallium onto the substrate, The steps include: activating and supplying a reaction gas containing nitrogen onto the substrate; Includes, A gas injection unit is provided inside the chamber. The aforementioned gas injection unit is The upper frame and A lower frame is provided on the lower side of the upper frame, with a first electrode and a second electrode provided on the lower surface, with a predetermined distance between them outside the first electrode. Equipped with, The step of supplying the reaction gas is, A method for forming a thin film, comprising activating the reaction gas inside the gas injection section, which includes a separation space between the first electrode and the second electrode, and injecting it onto the substrate.

17. The method for forming a thin film according to claim 16, further comprising the step of activating and supplying a hydrogen-containing gas onto the substrate after the step of supplying the source gas.

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