semiconductor element

Abstract

To provide semiconductor devices with improved reliability. [Solution] The semiconductor device of the present invention comprises a channel layer, a barrier layer, a gate electrode, a gate semiconductor layer, a first protective layer located on the barrier layer and containing a first substance, a source electrode located on the first side surface of the gate electrode, a drain electrode located on the second side surface which is the opposite side of the first side surface of the gate electrode, a first field dispersion layer, a second protective layer, and a third protective layer including a third lower protective layer located on the second protective layer and containing a first substance, a third upper protective layer located on the third lower protective layer and containing a first substance, and a third interlayer protective layer located between the third lower protective layer and the third upper protective layer and containing a first substance, wherein the atomic percentage (at%) content of the first substance in any one of the third lower protective layer, the third interlayer protective layer, and the third upper protective layer is greater than the content (at%) of the first substance in the first protective layer.

Description

[Technical Field]

[0001] This invention relates to a semiconductor device. [Background technology]

[0002] In modern society, semiconductor devices are closely related to daily life. In particular, the importance of power semiconductor devices, used in various fields such as transportation (electric vehicles, railways, electric trams), renewable energy systems (solar and wind power), and mobile devices, is increasing. Power semiconductor devices are semiconductor devices used to handle high voltages and high currents, performing functions such as power conversion and control in large power systems and high-power electronic devices. Power semiconductor devices possess the ability and durability to handle high power, can handle large amounts of current, and can withstand high voltages. For example, power semiconductor devices can handle voltages of several hundred to several thousand volts and currents of several tens to several thousand amperes. Power semiconductor devices can minimize power loss and improve the efficiency of electrical energy. Furthermore, power semiconductor devices can operate stably even in environments with high temperatures.

[0003] These power semiconductor devices are classified by material, such as SiC power semiconductor devices and GaN power semiconductor devices. By using SiC or GaN instead of existing silicon (Si) to manufacture power semiconductor devices, the disadvantages of silicon, which has unstable properties at high temperatures, can be compensated for. SiC power semiconductor devices are resistant to high temperatures, have low power loss, and are suitable for electric vehicles and renewable energy systems. GaN power semiconductor devices require a higher cost, but are efficient in terms of speed and are suitable for high-speed charging of mobile devices, etc. [Overview of the project] [Problems that the invention aims to solve]

[0004] The present invention has been made in view of the above-mentioned prior art, and the object of the present invention is to provide a semiconductor device with improved reliability. [Means for solving the problem]

[0005] A semiconductor device according to one aspect of the present invention, made to achieve the above objective, comprises a channel layer, a barrier layer located above the channel layer and containing a material having a different energy band gap from the channel layer, a gate electrode located above the barrier layer, a gate semiconductor layer located between the barrier layer and the gate electrode, a first protective layer located above the barrier layer and covering the gate electrode and containing a first material, a source electrode located on the first side surface of the gate electrode and connected to the channel layer, a drain electrode located on the second side surface which is the opposite side of the first side surface of the gate electrode and connected to the channel layer, and located above the first protective layer The device comprises a first field dispersion layer placed on the source electrode and electrically connected to it; a second protective layer located on the first protective layer and covering the first field dispersion layer; a third protective layer located on the second protective layer and containing the first substance; a third upper protective layer located on the third lower protective layer and containing the first substance; and a third interlayer protective layer located between the third lower protective layer and the third upper protective layer and containing the first substance, wherein the atomic percentage (at%) content (at%) of the first substance in any one of the third lower protective layer, the third interlayer protective layer, and the third upper protective layer is greater than the content (at%) of the first substance in the first protective layer.

[0006] To achieve the above objective, a semiconductor device according to another aspect of the present invention comprises a channel layer, a barrier layer located above the channel layer and containing a material having a different energy band gap than the channel layer, a gate electrode located above the barrier layer, a gate semiconductor layer located between the barrier layer and the gate electrode, a first protective layer located above the barrier layer and covering the gate electrode and containing a first material, a source electrode located on the first side surface of the gate electrode and connected to the channel layer, a drain electrode located on the second side surface which is the opposite side of the first side surface of the gate electrode and connected to the channel layer, and a sequentially connected to the source electrode and located on the first protective layer. The device comprises a first field dispersion layer, a second field dispersion layer, and a third field dispersion layer, a second protective layer located between the first field dispersion layer and the second field dispersion layer, and a third protective layer located between the second field dispersion layer and the third field dispersion layer and containing the first substance, wherein the third protective layer includes a third lower protective layer located above the second field dispersion layer and the second protective layer, and a third upper protective layer located between the third lower protective layer and the third field dispersion layer, and the atomic percentage (at%) content (at%) of the first substance in either the third lower protective layer or the third upper protective layer is greater than the content (at%) of the first substance in the first protective layer.

[0007] A semiconductor device according to yet another aspect of the present invention, made to achieve the above objective, comprises a channel layer containing GaN, a barrier layer containing AlGaN located on the channel layer, a gate electrode located on the barrier layer, a gate semiconductor layer containing p-type impurities located between the barrier layer and the gate electrode, a first protective layer containing a first substance located on the barrier layer and covering the gate electrode, a source electrode located on the first side of the gate electrode and connected to the channel layer, a drain electrode located on the second side which is the opposite side of the first side of the gate electrode and connected to the channel layer, and the source electrode The device comprises a first field dispersion layer, a second field dispersion layer, and a third field dispersion layer electrically connected to and sequentially positioned on the first protective layer; a second protective layer located between the first field dispersion layer and the second field dispersion layer and containing the first substance; and a third protective layer located between the first field dispersion layer and the second field dispersion layer and containing the first substance, wherein the maximum content (at%) of the first substance in the second protective layer is greater than the maximum content (at%) of the first substance in the first protective layer, and the maximum content (at%) of the first substance in the third protective layer is greater than the maximum content (at%) of the first substance in the second protective layer.

[0008] A method for manufacturing a semiconductor device according to one embodiment includes the steps of: forming a barrier layer on a channel layer containing a material having a different energy band gap from the channel layer; forming a gate semiconductor layer and a gate electrode on the barrier layer; forming a first protective layer containing a first material on the barrier layer and the gate electrode; forming a source electrode and a drain electrode that penetrate the first protective layer and the barrier layer and are electrically connected to the channel layer, and forming a first field dispersion layer on the first protective layer; forming a second protective layer on the first protective layer and the first field dispersion layer; forming a third lower protective layer containing the first material on the second protective layer, and forming a third upper protective layer containing the first material on the third lower protective layer to form a third protective layer, wherein the content (at%) of the first material in either the third lower protective layer or the third upper protective layer is greater than the content (at%) of the first material in the first protective layer.

[0009] The first substance may be hydrogen (H), carbon (C), nitrogen (N), or a combination thereof. The second protective layer contains the first substance, and the content (at%) of the first substance in either the third lower protective layer or the third upper protective layer may be greater than the content (at%) of the first substance in the second protective layer. The content (at%) of the first substance in the third lower protective layer may be greater than or equal to the content (at%) of the first substance in the third upper protective layer. The step of forming the third protective layer includes forming the third lower protective layer, and then forming a third interlayer protective layer containing the first substance on the third lower protective layer, wherein the content (at%) of the first substance in the third interlayer protective layer may be greater than the content (at%) of the first substance in the third lower protective layer and the content (at%) of the first substance in the third upper protective layer. The third interlayer protective layer comprises silicon nitride, and the third lower protective layer and the third upper protective layer may comprise silicon oxide. The thickness of the third interlayer protection layer may be less than the thickness of the third lower protection layer.

Advantages of the Invention

[0010] According to the present invention, the breakdown voltage of the semiconductor device can be increased, the decrease in the hole concentration in the gate semiconductor layer can be prevented, the decrease in the density of the two-dimensional electron gas can be prevented, the deterioration of characteristics such as the on-current and on-resistance can be prevented, and the reliability of the semiconductor device can be improved.

Brief Description of the Drawings

[0011] [Figure 1] It is a cross-sectional view showing the off state of the semiconductor device of the first example according to one embodiment. [Figure 2] It is a cross-sectional view showing the on state of the semiconductor device of the first example according to one embodiment. [Figure 3A] It is a graph showing the first example of the content of the first substance in the first to third protection layers of the semiconductor device according to one embodiment. [Figure 3B] It is a graph showing the second example of the content of the first substance in the first to third protection layers of the semiconductor device according to one embodiment. [Figure 3C] It is a graph showing the third example of the content of the first substance in the first to third protection layers of the semiconductor device according to one embodiment. [Figure 3D] It is a graph showing the fourth example of the content of the first substance in the first to third protection layers of the semiconductor device according to one embodiment. [Figure 4] It is a cross-sectional view showing the semiconductor device of the second example according to one embodiment. [Figure 5] It is a cross-sectional view showing the first to third protection layers of the semiconductor device of the embodiment of FIG. 4. [Figure 6A] It is a graph showing the first example of the content of the first substance in the first to third protection layers of the semiconductor device according to the embodiment of FIG. 4. [Figure 6B] It is a graph showing the second example of the content of the first substance in the first to third protection layers of the semiconductor device according to the embodiment of FIG. 4. [Figure 6C] This graph shows a third example of the content of the first substance in the first to third protective layers of the semiconductor device according to the embodiment shown in Figure 4. [Figure 6D] This graph shows a fourth example of the content of the first substance in the first to third protective layers of the semiconductor device according to the embodiment shown in Figure 4. [Figure 6E] This graph shows the fifth example of the content of the first substance in the first to third protective layers of the semiconductor device according to the embodiment shown in Figure 4. [Figure 7] This is a cross-sectional view showing the first to third protective layers of a semiconductor device in a second example according to one embodiment. [Figure 8] This is a cross-sectional view showing a third example of a semiconductor device according to one embodiment. [Figure 9] This is a cross-sectional view showing a fourth example of a semiconductor device according to one embodiment. [Figure 10] This is a cross-sectional view showing a fifth example of a semiconductor device according to one embodiment. [Figure 11] This is a cross-sectional view showing a sixth example of a semiconductor device according to one embodiment. [Figure 12] This is a cross-sectional view showing a semiconductor device of the seventh example according to one embodiment. [Figure 13] This is a cross-sectional view showing the process sequence for manufacturing a semiconductor device according to one embodiment. [Figure 14] This is a cross-sectional view showing the process sequence for manufacturing a semiconductor device according to one embodiment. [Figure 15] This is a cross-sectional view showing the process sequence for manufacturing a semiconductor device according to one embodiment. [Figure 16] This is a cross-sectional view showing the process sequence for manufacturing a semiconductor device according to one embodiment. [Figure 17] This is a cross-sectional view showing the process sequence for manufacturing a semiconductor device according to one embodiment. [Figure 18] This is a cross-sectional view showing the process sequence for manufacturing a semiconductor device according to one embodiment. [Modes for carrying out the invention]

[0012] Hereinafter, specific examples of embodiments for carrying out the present invention will be described in detail with reference to the drawings.

[0013] However, the present invention can be embodied in various forms and should not be construed as being limited to the embodiments described herein. Furthermore, while the present invention provides details regarding embodiments, it should be emphasized that this catalog of embodiments is not complete. Also, items described singularly herein may be provided plurally, for example, as shown in the drawings. Therefore, a description of a single item provided plurally should be understood to apply to the remaining plural items unless otherwise explicitly stated in the context.

[0014] To clearly explain the present invention, unnecessary parts have been omitted, and the same or similar components are given the same reference numerals throughout the specification.

[0015] Furthermore, the dimensions and thicknesses of each component shown in the drawings are arbitrarily shown for the sake of explanation and are not necessarily limited to those shown in the drawings. The thicknesses are shown enlarged in the drawings to clearly represent multiple layers and regions. In addition, the thicknesses of some layers and regions are exaggerated in the drawings for the sake of explanation.

[0016] Furthermore, when a layer, membrane, region, plate, or other part is said to be "on top" of another part, this includes not only when it is "directly above" the other part, but also when the other part is in between. Conversely, when one part is said to be "directly above" another part, it means that there is no other part in between. Also, being "on top" of a reference part means being located above or below the reference part, and does not necessarily mean being located "above" in the opposite direction of gravity.

[0017] When it is mentioned that a component is “connected” or “joined” to another component, or that it is “joined” to another component, it should be understood that it is either directly connected or joined to the other component, or that an intermediate component exists. In contrast, when it is mentioned that a component is “directly connected” or “directly joined” to another component, or that it “is in contact” with another component, or that it is “in contact,” there is no intermediate component at the point of contact.

[0018] When two conductive components come into contact with each other, an ohmic contact state is created, where an electric current is conducted between the two conductive components according to Ohm's law. Ohmic contact results in the two conductive components being electrically connected to each other. In this specification, items described as "electrically connected" are configured to transmit an electrical signal from one item to another. Therefore, passively electrically conductive components (e.g., wires, pads, internal electrical lines, etc.) that are physically connected to passively electrically insulating components (e.g., prepreg layers of printed circuit boards, electrically insulating adhesives connecting two devices, electrically insulating underfills or mold layers, etc.) are not electrically connected to those components.

[0019] Wherever a specification describes a component as "including" a particular component or group of components, unless otherwise explicitly stated in the context, it should be understood that the component is formed solely by that component or group of components, or that the component or group of components can be combined with additional components to form a component.

[0020] Throughout the specification, when a component or layer is composed of two or more materials, the relative amount of each material is referred to as the content in atomic percentage (at%). In content, "%" represents the percentage that indicates the relative ratio of the number of atoms of a substance in a component or layer to the total number of atoms of that component or layer.

[0021] Hereinafter, a first example of a semiconductor device according to one embodiment will be described with reference to Figures 1 and 2.

[0022] Figures 1 and 2 are cross-sectional views showing a first example semiconductor element according to one embodiment. Figure 1 shows the first example semiconductor element according to one embodiment in the off state, and Figure 2 shows the first example semiconductor element according to one embodiment in the on state.

[0023] Referring to Figures 1 and 2, the semiconductor device according to this embodiment includes a channel layer 132, a barrier layer 136 located on the channel layer 132, a gate electrode 155 located on the barrier layer 136, a gate semiconductor layer 152 located between the barrier layer 136 and the gate electrode 155, a first protective layer 210 located on the barrier layer 136 and covering the gate electrode 155, a source electrode 170 and a drain electrode 190 located on both sides of the gate electrode 155 and electrically connected to the channel layer 132, a first field dispersion layer 177a located on the first protective layer 210 and electrically connected to the source electrode 170, a second protective layer 220 located on the first protective layer 210, and a third protective layer 230 located on the second protective layer 220.

[0024] The channel layer 132 is a layer that forms a channel between the source electrode 170 and the drain electrode 190, and a two-dimensional electron gas 134 (2DEG) is located inside the channel layer 132. The two-dimensional electron gas 134 is a charge transport model used in solid-state physics, and refers to a group of electrons that can move freely in two dimensions (e.g., the xy-plane direction) but cannot move in another one-dimensional direction (e.g., the z-direction) and are therefore firmly constrained within the two dimensions. For example, the two-dimensional electron gas 134 exists in a three-dimensional space in the form of a two-dimensional piece of paper. Such a two-dimensional electron gas 134 mainly appears in semiconductor heterogeneous junction structures, and in the semiconductor device according to this embodiment, it is generated at the interface between the channel layer 132 and the barrier layer 136. For example, the two-dimensional electron gas 134 is generated in the portion of the channel layer 132 adjacent to the barrier layer 136.

[0025] The channel layer 132 contains one or more substances selected from group III-V substances, such as nitrates containing Al, Ga, In, B, or combinations thereof. The channel layer 132 is composed of a single layer or multiple layers. The channel layer 132 contains Al x In y Ga 1-x-y The matrix is ​​N(0≦x≦1, 0≦y≦1, x+y≦1). For example, channel layer 132 contains AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof. Channel layer 132 is either an impurity-doped layer or an undoped layer. The thickness of channel layer 132 is approximately several hundred nm or less.

[0026] The channel layer 132 is located on the substrate 110, with a seed layer 121 and a buffer layer 120 located between the substrate 110 and the channel layer 132. The substrate 110, seed layer 121, and buffer layer 120 are necessary layers for forming the channel layer 132, and can be omitted in some cases. For example, when using a substrate made of GaN as the channel layer 132, at least one of the substrate 110, seed layer 121, and buffer layer 120 may be omitted. Considering that substrates made of GaN are relatively expensive, a Si substrate 110 is used to grow the GaN-containing channel layer 132. In this case, because the lattice structure of Si and the lattice structure of GaN are different, it is not easy to grow the channel layer 132 directly on the substrate 110. For this reason, the seed layer 121 and buffer layer 120 are grown on the substrate 110 first, and then the channel layer 132 is grown on the buffer layer 120. Furthermore, at least one of the substrate 110, seed layer 121, and buffer layer 120 may be removed in the final structure of the semiconductor device after being used in the manufacturing process.

[0027] The substrate 110 contains a semiconductor material. For example, the substrate 110 may contain sapphire, Si, SiC, AlN, GaN, or a combination thereof. The substrate 110 is an SOI (Silicon on Insulator) substrate. However, the material of the substrate 110 is not limited to this, and all commonly used substrates may be applied. In some cases, the substrate 110 may also contain an insulating material. For example, various layers, including a channel layer 132, may be formed on a semiconductor substrate first, and then the semiconductor substrate may be removed and replaced with an insulating substrate.

[0028] The seed layer 121 is located directly above the substrate 110. However, it is not limited to this, and other predetermined layers may be located between the substrate 110 and the seed layer 121. The seed layer 121 is a layer that serves as a seed for growing the buffer layer 120, and is composed of a crystal lattice structure that serves as a seed for the buffer layer 120. The buffer layer 120 is located directly above the seed layer 121. However, it is not limited to this, and other predetermined layers may be located between the seed layer 121 and the buffer layer 120. The seed layer 121 contains one or more substances selected from group III-V materials, such as nitrates containing Al, Ga, In, B, or combinations thereof. The seed layer 121 contains Al x In y Ga 1-x-y N is defined as (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). For example, the seed layer 121 includes AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof.

[0029] The buffer layer 120 is located above the seed layer 121. The buffer layer 120 is located between the seed layer 121 and the channel layer 132. The buffer layer 120 is a layer for relaxing the difference in lattice constant and thermal expansion coefficient between the seed layer 121 and the channel layer 132, or for preventing leakage current from flowing through the channel layer 132. The buffer layer 120 contains one or more substances selected from nitrates containing III-V group substances, such as Al, Ga, In, B, or combinations thereof. The buffer layer 120 contains Al x In y Ga 1-x-y N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, x + y ≦ 1). For example, the buffer layer 120 contains AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or combinations thereof.

[0030] The buffer layer 120 of the semiconductor device according to this embodiment includes a superlattice layer 124 located above the seed layer 121 and a high-resistance layer 126 located above the superlattice layer 124. The superlattice layer 124 and the high-resistance layer 126 are sequentially located above the substrate 110.

[0031] The superlattice layer 124 is located above the seed layer 121. The superlattice layer 124 is located directly above the seed layer 121. However, it is not limited thereto, and a predetermined other layer may be further located between the seed layer 121 and the superlattice layer 124. The superlattice layer 124 relaxes the difference in lattice constant and thermal expansion coefficient between the substrate 110 and the channel layer 132, thereby relaxing the tensile stress and compressive stress generated between the substrate 110 and the channel layer 132, and relaxing the stress between all layers formed by growth in the final structure of the semiconductor device according to this embodiment. The superlattice layer 124 contains one or more substances selected from nitrates containing III-V group substances, such as Al, Ga, In, B, or combinations thereof. The superlattice layer 124 contains Al x In y Ga 1-x-yN is (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). For example, the superlattice layer 124 includes AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof.

[0032] In one embodiment, the superlattice layer 124 is composed of multiple layers in which layers containing different materials are stacked alternately. For example, the superlattice layer 124 has a structure in which layers composed of AlGaN and layers composed of AlN are repeatedly stacked. For example, AlGaN / AlN / AlGaN / AlN / AlGaN / AlN are stacked sequentially to form a superlattice layer. The number of AlGaN layers and GaN that make up the superlattice layer 124 can be varied, and the materials that make up the superlattice layer 124 can be varied. As another example, the superlattice layer 124 can also have a structure in which layers composed of AlGaN and layers composed of GaN are repeatedly stacked. For example, AlGaN / GaN / AlGaN / GaN / AlGaN / GaN can be stacked sequentially to form a superlattice layer. In one embodiment, when the superlattice layer 124 includes GaN, InN, AlGaN, AlInN, InGaN, AlN, AlInGaN, or a combination thereof, the superlattice layer 124 has n-type semiconductor properties in which the electron concentration is greater than the hole concentration, but is not limited to this.

[0033] The high-resistance layer 126 is located on top of the superlattice layer 124. The high-resistance layer 126 is located directly above the superlattice layer 124. However, it is not limited to this, and other predetermined layers may be located between the superlattice layer 124 and the high-resistance layer 126. The high-resistance layer 126 is located between the superlattice layer 124 and the channel layer 132. The high-resistance layer 126 is a layer for preventing degradation of the semiconductor device according to this embodiment by preventing leakage current from flowing through the channel layer 132. The high-resistance layer 126 is composed of a material with low conductivity so that the substrate 110 and the channel layer 132 are electrically insulated. The high-resistance layer contains one or more materials selected from III-V group materials, such as nitrates containing Al, Ga, In, B, or combinations thereof. The high-resistance layer 126 is Al x Iny Ga 1-x-y N is (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). For example, the high-resistance layer 126 includes AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof. The high-resistance layer 126 consists of a single layer or multiple layers. The barrier layer 136 is located on top of the channel layer 132.

[0034] The barrier layer 136 is located directly above the channel layer 132. However, it is not limited to this, and other predetermined layers may be located between the channel layer 132 and the barrier layer 136. The region of the channel layer 132 that overlaps the barrier layer 136 between the source electrode 170 and the drain electrode 190 becomes the drift region (DTR). The drift region (DTR) is located between the source electrode 170 and the drain electrode 190. The drift region (DTR) is the region where carriers move when a potential difference is generated between the source electrode 170 and the drain electrode 190.

[0035] The semiconductor element according to this embodiment is switched on / off depending on whether a voltage is applied to the gate electrode 155 and / or the magnitude of the voltage applied to the gate electrode 155, thereby causing carrier movement to occur or to be blocked in the drift region (DTR).

[0036] The barrier layer 136 contains one or more substances selected from group III-V substances, such as nitrates containing Al, Ga, In, B, or combinations thereof. x In y Ga 1-x-y N is (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). The barrier layer 136 includes GaN, InN, AlGaN, AlInN, InGaN, AlN, AlInGaN, or combinations thereof. The energy band gap of the barrier layer 136 is adjusted by the composition ratio of Al and / or In (e.g., content (at%)).

[0037] The barrier layer 136 contains a semiconductor material having different properties from the channel layer 132. The barrier layer 136 differs from the channel layer 132 in one of the following: polarization characteristics, energy band gap, or lattice constant. For example, the barrier layer 136 contains a material having a different energy band gap than the channel layer 132. In this case, the barrier layer 136 has a higher energy band gap and a higher electrical polarizability than the channel layer 132. Such a barrier layer 136 induces a two-dimensional electron gas 134 in the channel layer 132, which has a relatively lower electrical polarizability. For this reason, the barrier layer 136 is sometimes called a channel supply layer or a two-dimensional electron gas supply layer. The two-dimensional electron gas 134 is formed in the portion of the channel layer 132 located below the interface between the channel layer 132 and the barrier layer 136. The two-dimensional electron gas 134 has very high electron mobility.

[0038] The barrier layer 136 is composed of a single layer or multiple layers. When the barrier layer 136 is composed of multiple layers, the materials in each layer constituting the multiple layers have different energy band gaps. In this case, the various layers constituting the barrier layer 136 are arranged such that the energy band gap increases the closer they are to the channel layer 132.

[0039] The gate electrode 155 is located on the barrier layer 136. The gate electrode 155 overlaps a portion of the barrier layer 136 in the third direction (Z direction). The gate electrode 155 overlaps a portion of the drift region (DTR) of the channel layer 132 in the third direction (Z direction). The gate electrode 155 is located between the source electrode 170 and the drain electrode 190. The gate electrode 155 is spaced apart from the source electrode 170 and the drain electrode 190. For example, the gate electrode 155 is located closer to the source electrode 170 than to the drain electrode 190. For example, the separation distance between the gate electrode 155 and the source electrode 170 is smaller than the separation distance between the gate electrode 155 and the drain electrode 190, but is not limited to this. Here, the third direction (Z direction) refers to the thickness direction of the channel layer 132.

[0040] The gate electrode 155 contains a conductive material. For example, the gate electrode 155 includes metals, metal alloys, conductive metal nitrates, metal silicides, doped semiconductor materials, conductive metal oxides, conductive metal nitrogen oxides, etc. For example, the gate electrode 155 includes titanium nitrate (TiN), tantalum carbide (TaC), tantalum nitrate (TaN), titanium silicon nitride (Ti silicon nitride (SiN)), tantalum silicon nitride (Ta silicon nitride (SiN)), tantalum titanium nitrate (TaTiN), titanium aluminum nitrate (TiAlN), tantalum aluminum nitrate (TaAlN), tungsten nitrate (WN), ruthenium (Ru), titanium aluminum (TiAl), titanium aluminum carbide nitrate (TiAlC-N), titanium aluminum carbide (TiAlC), titanium carbide (TiC), tantalum carbide nitrate ( This includes, but is not limited to, TaCN, tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), titanium (Ti), tantalum (Ta), nickel (Ni), platinum (Pt), nickel-platinum (Ni-Pt), niobium (Nb), niobium nitrate (NbN), niobium carbide (NbC), molybdenum (Mo), molybdenum nitrate (MoN), molybdenum carbide (MoC), tungsten carbide (WC), rhodium (Rh), palladium (Pd), iridium (Ir), osmium (Os), silver (Ag), gold (Au), zinc (Zn), vanadium (V), or combinations thereof. The gate electrode 155 is composed of a single layer or multiple layers.

[0041] In one embodiment, a hard mask layer located on the gate electrode 155 may be further included. The hard mask layer is a hard mask used when patterning the gate semiconductor material layer (152a in Figure 13) and the gate electrode material layer (155a in Figure 13) during the process of forming the gate electrode 155. However, the hard mask layer may be removed during etching of the gate semiconductor material layer (152a in Figure 13) by etching conditions or post-etching cleaning conditions. As an example, the hard mask layer includes silicon oxide, silicon nitride, silicon nitrogen oxide, or a combination thereof.

[0042] The gate semiconductor layer 152 is located between the barrier layer 136 and the gate electrode 155. For example, the gate semiconductor layer 152 is located on top of the barrier layer 136, and the gate electrode 155 is located on top of the gate semiconductor layer 152. The gate electrode 155 makes Schottky contact or ohmic contact with the gate semiconductor layer 152. The gate semiconductor layer 152 overlaps the gate electrode 155 in a third direction (Z direction). In this case, the gate semiconductor layer 152 completely overlaps the gate electrode 155 in the third direction (Z direction), and the upper surface of the gate semiconductor layer 152 is entirely covered by the gate electrode 155. For example, the gate semiconductor layer 152 has substantially the same planar shape as the gate electrode 155. However, it is not limited to this, and the gate electrode 155 can also be positioned to cover at least a portion of the gate semiconductor layer 152.

[0043] In one embodiment, the barrier layer 136 located below the gate semiconductor layer 152 in the depletion region (DPR) is doped with a predetermined impurity. The impurity doped into the barrier layer 136 is a p-type dopant that provides holes. For example, the impurity doped into the barrier layer 136 is magnesium (Mg). By increasing or decreasing the impurity doping concentration of the barrier layer 136, the threshold voltage, on-resistance, etc., of the semiconductor device according to this embodiment can be adjusted.

[0044] The gate semiconductor layer 152 is located between the source electrode 170 and the drain electrode 190. The gate semiconductor layer 152 is spaced apart from the source electrode 170 and the drain electrode 190. The gate semiconductor layer 152 is located closer to the source electrode 170 than to the drain electrode 190. For example, the separation distance between the gate semiconductor layer 152 and the source electrode 170 is smaller than the separation distance between the gate semiconductor layer 152 and the drain electrode 190, but is not limited to this.

[0045] In this embodiment, the gate semiconductor layer 152 overlaps the gate electrode 155 in the third direction (Z direction). For example, the gate semiconductor layer 152 completely overlaps the gate electrode 155 in the third direction (Z direction). For example, the side surface of the gate semiconductor layer 152 is aligned with the side surface of the gate electrode 155. However, it is not limited to this, and the gate semiconductor layer 152 may also partially overlap the gate electrode 155.

[0046] The gate semiconductor layer 152 contains one or more substances selected from group III-V materials, such as nitrates containing Al, Ga, In, B, or combinations thereof. x In y Ga 1-x-y N is (0≦x≦1, 0≦y≦1, x+y≦1). For example, the gate semiconductor layer 152 includes AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof. The gate semiconductor layer 152 includes a material having a different energy band gap than the barrier layer 136. For example, the gate semiconductor layer 152 includes GaN and the barrier layer 136 includes AlGaN. The gate semiconductor layer 152 is doped with a predetermined impurity. In this case, the impurity doped into the gate semiconductor layer 152 is a p-type dopant that provides holes. For example, the gate semiconductor layer 152 includes GaN doped with a p-type impurity. For example, the gate semiconductor layer 152 is composed of a p-GaN layer. However, it is not limited to this, and for example, the gate semiconductor layer 152 may be a p-AlGaN layer. As another example, the gate semiconductor layer 152 can also be formed as a multilayer including a p-GaN layer and a p-AlGaN layer.

[0047] The gate semiconductor layer 152 forms a depletion region (DPR) within the channel layer 132. The depletion region (DPR) is located within the drift region (DTR) and has a narrower width than the drift region (DTR). Because the gate semiconductor layer 152, which has a different energy band gap than the barrier layer 136, is located above the barrier layer 136, the energy band levels of the portion of the barrier layer 136 overlapping the gate semiconductor layer 152 become higher. As a result, a depletion region (DPR) is formed in the region of the channel layer 132 overlapping the gate semiconductor layer 152. The depletion region (DPR) is a region in the channel path of the channel layer 132 where the two-dimensional electron gas 134 is not formed or has a lower electron concentration than the remaining region. For example, the depletion region (DPR) means a region within the drift region (DTR) where the flow of the two-dimensional electron gas 134 is interrupted. The occurrence of a depletion region (DPR) prevents current from flowing between the source electrode 170 and the drain electrode 190, thus blocking the channel path. As a result, the semiconductor device according to this embodiment has normally-off characteristics.

[0048] For example, the semiconductor device according to this embodiment is a normally-off high electron mobility transistor (HEMT). As shown in Figure 1, in the normal state where no voltage is applied to the gate electrode 155, a depletion region (DPR) exists, and the semiconductor device according to this embodiment is in the off state. As shown in Figure 2, when a voltage greater than the threshold voltage is applied to the gate electrode 155, the depletion region (DPR) disappears, and the two-dimensional electron gas 134 remains connected without being interrupted within the drift region (DTR). For example, the two-dimensional electron gas 134 is formed throughout the entire channel path between the source electrode 170 and the drain electrode 190, and the semiconductor device according to this embodiment becomes on. In summary, the semiconductor device according to this embodiment includes semiconductor layers with different electrical polarization characteristics, and the semiconductor layer with a relatively large polarization rate induces the formation of a two-dimensional electron gas 134 in other semiconductor layers joined to it. Such a two-dimensional electron gas 134 is used as a channel between the source electrode 170 and the drain electrode 190, and the connection or disconnection of the flow of such two-dimensional electron gas 134 is controlled by a bias voltage applied to the gate electrode 155. When the gate is off, the flow of the two-dimensional electron gas 134 is interrupted, and no current flows between the source electrode 170 and the drain electrode 190. When the gate is on, the flow of the two-dimensional electron gas 134 is connected, and current flows between the source electrode 170 and the drain electrode 190.

[0049] The above describes the case where the semiconductor element according to this embodiment is a normally-off high electron-mobility transistor, but it is not limited to this. For example, the semiconductor element according to one embodiment may be a normally-on high electron-mobility transistor. In the case of a normally-on high electron-mobility transistor, the gate semiconductor layer 152 is omitted, and as a result, the gate electrode 155 is located directly above the barrier layer 136. For example, the gate electrode 155 is in contact with the barrier layer 136. However, it is not limited to this, and a gate insulating layer may be further located between the gate electrode 155 and the barrier layer 136. The insulating layer is composed of a single layer or multiple layers. In this case, the gate insulating layer completely overlaps the gate electrode 155 in the third direction (Z direction), but it is not limited to this.

[0050] In this structure, when no voltage is applied to the gate electrode 155, the two-dimensional electron gas 134 is used as a channel, and a current flows between the source electrode 170 and the drain electrode 190. Furthermore, when a negative voltage is applied to the gate electrode 155, a depletion region (DPR) is created below the gate electrode 155 where the flow of the two-dimensional electron gas 134 is interrupted.

[0051] The seed layer 121, superlattice layer 124, high-resistance layer 126, channel layer 132, barrier layer 136, and gate semiconductor layer 152 described above are sequentially stacked on the substrate 110. In one embodiment of the semiconductor device, at least one of the seed layer 121, superlattice layer 124, high-resistance layer 126, channel layer 132, barrier layer 136, and gate semiconductor layer 152 may be omitted. Such a seed layer 121, superlattice layer 124, high-resistance layer 126, channel layer 132, barrier layer 136, and gate semiconductor layer 152 are composed of semiconductor materials from the same substrate, and the material composition ratio of each layer differs considering the role of each layer and the performance required of the semiconductor device.

[0052] The first protective layer 210 is located on top of the barrier layer 136. The first protective layer 210 covers the gate electrode 155. For example, the first protective layer 210 is located directly above the upper surface (136_U) of the barrier layer 136. The first protective layer 210 covers the upper and side surfaces of the gate electrode 155, as well as the side surfaces of the gate semiconductor layer 152. The lower surface of the first protective layer 210 is in contact with the upper surface (136_U) of the barrier layer 136, the side surfaces of the gate electrode 155, and the upper surface of the gate electrode 155. As a result, the barrier layer 136, the gate semiconductor layer 152, and the gate electrode 155 are protected by the first protective layer 210. However, this is not limited to the above, and there are cases where the gate electrode 155 penetrates the first protective layer 210 and is connected to the gate semiconductor layer 152, and the first protective layer 210 does not cover the upper surface of the gate electrode 155. Alternatively, the lower surface of the first protective layer 210 can be in contact with the gate semiconductor layer 152.

[0053] Furthermore, the first protective layer 210 is located on the sides of the source electrode 170 and the drain electrode 190. For example, the first protective layer 210 covers at least a portion of the sides of the source electrode 170 and the drain electrode 190.

[0054] The first protective layer 210 contains an insulating material. For example, the first protective layer 210 contains, but is not limited to, oxides such as silicon oxide (SiO2) or aluminum oxide (Al2O3). As another example, the first protective layer 210 may also contain nitrates such as silicon nitride (SiN) or nitrates such as silicon nitride (SiON).

[0055] The first protective layer 210 contains a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof. In one embodiment, the first protective layer 210 contains the first substance in a first content (at%). In one embodiment, the first content (at%) of the first substance in the first protective layer 210 is constant even as it moves away from the upper surface (136_U) of the barrier layer 136, but is not limited thereto. For example, the first content (at%) of the first substance in the first protective layer 210 may increase as it moves away from the upper surface (136_U) of the barrier layer 136. As another example, the first content (at%) of the first substance in the first protective layer 210 may include a portion that decreases as it moves away from the upper surface (136_U) of the barrier layer 136. Furthermore, the first content (at%) of the first substance in the first protective layer 210 is different from the first content (at%) of the first substance in the second protective layer 220 and the first content (at%) of the third protective layer 230. A detailed explanation of this will be given later in Figures 3A to 3D.

[0056] Figures 1 and 2 show the first protective layer 210 as a single layer, but it is not limited to this. The first protective layer 210 can also be composed of two or more layers having different content (at%) of the first substance. This will be explained later with reference to Figure 10.

[0057] The source electrode 170 and the drain electrode 190 are located on the channel layer 132. The source electrode 170 and the drain electrode 190 are in direct contact with the channel layer 132 and are electrically connected to the channel layer 132.

[0058] The source electrode 170 and the drain electrode 190 extend in a second direction (Y direction). The source electrode 170 and the drain electrode 190 are separated from each other, and the gate electrode 155 and the gate semiconductor layer 152 are located between the source electrode 170 and the drain electrode 190. The gate electrode 155 and the gate semiconductor layer 152 are separated from the source electrode 170 and the drain electrode 190. For example, the source electrode 170 is electrically connected to the channel layer 132 on one side of the gate electrode 155, and the drain electrode 190 is electrically connected to the channel layer 132 on the other side of the gate electrode 155. The source electrode 170 and the drain electrode 190 are located outside the drift region (DTR) of the channel layer 132. The interface between the source electrode 170 and the channel layer 132 is one end of the drift region (DTR). Similarly, the interface between the drain electrode 190 and the channel layer 132 is the other end of the drift region (DTR).

[0059] However, this is not limited to the above, and the channel layer 132 may not be recessed, with the source electrode 170 and drain electrode 190 positioned above the upper surface of the channel layer 132 and / or the upper surface (136_U) of the barrier layer 136. In this case, the bottom surfaces of the source electrode 170 and drain electrode 190 will be in contact with the upper surface of the channel layer 132 and the upper surface (136_U) of the barrier layer, or a portion of the partially recessed barrier layer 136. The portion of the channel layer 132 or barrier layer 136 in contact with the source electrode 170 and drain electrode 190 is highly doped. As an example, the portion of the channel layer 132 or barrier layer 136 in contact with the source electrode 170 and drain electrode 190 is highly doped with an N-type dopant. At this time, carriers that have passed through the two-dimensional electron gas 134 are transmitted to the source electrode 170 and drain electrode 190 through the highly doped portion of the channel layer 132 or the barrier layer 136, i.e., the upper part of the two-dimensional electron gas 134. It is also possible to ensure that the source electrode 170 and drain electrode 190 do not directly contact the two-dimensional electron gas 134 in the horizontal direction. Here, the horizontal direction means the direction aligned with the upper surface (136_U) of the channel layer 132 or barrier layer 136.

[0060] Specifically, trenches (141 and 143 in Figure 16) that penetrate the first protective layer 210 and the barrier layer 136 and recess the upper surface of the channel layer 132 are located on both sides of the gate electrode 155, spaced apart from each other. The source electrode 170 and drain electrode 190 are located within the trenches (141 and 143 in Figure 16), respectively, on both sides of the gate electrode 155. The source electrode 170 and drain electrode 190 are formed to fill the trenches (141 and 143 in Figure 16). Within the trenches, the source electrode 170 and drain electrode 190 are in contact with the channel layer 132 and the barrier layer 136. The channel layer 132 forms the bottom and side walls of the trenches, and the barrier layer 136 forms the side walls of the trenches. The source electrode 170 and drain electrode 190 are also in contact with the sides of the barrier layer 136. For example, the source electrode 170 and the drain electrode 190 cover the sides of the channel layer 132 and the barrier layer 136.

[0061] The source electrode 170 and drain electrode 190 contain conductive materials. For example, the source electrode 170 and drain electrode 190 contain metals, metal alloys, conductive metal nitrates, metal silicides, doped semiconductor materials, conductive metal oxides, conductive metal nitrogen oxides, etc. For example, the source electrode 170 and drain electrode 190 contain titanium nitrate (TiN), tantalum carbide (TaC), tantalum nitrate (TaN), titanium silicon nitride (Ti silicon nitride (SiN)), tantalum silicon nitride (Ta silicon nitride (SiN)), tantalum titanium nitrate (TaTiN), titanium aluminum nitrate (TiAlN), tantalum aluminum nitrate (TaAlN), tungsten nitrate (WN), ruthenium (Ru), titanium aluminum (TiAl), titanium aluminum carbide nitrate (TiAlC-N), titanium aluminum carbide (TiAlC), titanium carbide (TiC), tantalum This includes, but is not limited to, nitrate carbides (TaCN), tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), titanium (Ti), tantalum (Ta), nickel (Ni), platinum (Pt), nickel-platinum (Ni-Pt), niobium (Nb), niobium nitrate (NbN), niobium carbide (NbC), molybdenum (Mo), molybdenum nitrate (MoN), molybdenum carbide (MoC), tungsten carbide (WC), rhodium (Rh), palladium (Pd), iridium (Ir), osmium (Os), silver (Ag), gold (Au), zinc (Zn), vanadium (V), or combinations thereof. The source electrode 170 and drain electrode 190 are composed of a single layer or multiple layers. The source electrode 170 and the drain electrode 190 are in ohmic contact with the channel layer 132. The regions in the channel layer 132 and the barrier layer 136 that are in contact with the source electrode 170 and the drain electrode 190 are doped to a relatively higher concentration compared to other regions.

[0062] The source electrode 170 of the semiconductor device according to this embodiment includes a plurality of source electrodes (171-173) sequentially stacked on the channel layer 132 in a third direction (Z direction), and the drain electrode 190 includes a plurality of drain electrodes (191-193) sequentially stacked on the channel layer 132 in a third direction (Z direction).

[0063] The first source electrode 171 and the first drain electrode 191 penetrate the first protective layer 210 and the barrier layer 136. The first source electrode 171 and the first drain electrode 191 are in contact with the channel layer 132. In this embodiment, the first source electrode 171 and the first drain electrode 191 are located on the side surfaces of the barrier layer 136 and the side surfaces of the first protective layer 210. The first source electrode 171 and the first drain electrode 191 cover a portion of the side surfaces of the barrier layer 136 and the side surfaces of the first protective layer 210. The upper surfaces of the first source electrode 171 and the first drain electrode 191 protrude in a third direction (Z direction) beyond the upper surface of the first protective layer 210. In addition, either the first source electrode 171 or the first drain electrode 191 covers at least a portion of the upper surface of the first protective layer 210, but is not limited to this.

[0064] The second source electrode 172 is located on the first source electrode 171. The second source electrode 172 is in contact with the first source electrode 171. The second source electrode 172 is located on the side surface of the second protective layer 220, which will be described later. The second source electrode 172 is in contact with the second protective layer 220, which will be described later. In this embodiment, the second source electrode 172 covers at least a portion of the upper surface of the second protective layer 220, which will be described later, but is not limited thereto. The second source electrode 172 contains a conductive material. The second source electrode 172 contains the same conductive material as the first source electrode 171, but is not limited thereto. As another example, the second source electrode 172 may contain a different conductive material than the first source electrode 171.

[0065] The third source electrode 173 is located on top of the second source electrode 172. The third source electrode 173 is in contact with the second source electrode 172. The third source electrode 173 is located on the side surface of the third protective layer 230, which will be described later. The third source electrode 173 is in contact with the third protective layer 230, which will be described later. In one embodiment, the third source electrode 173 covers at least a portion of the upper surface of the third protective layer 230, which will be described later, but is not limited thereto. The third source electrode 173 contains a conductive material. The third source electrode 173 contains the same conductive material as the first source electrode 171 and the second source electrode 172, but is not limited thereto. As another example, the third source electrode 173 may contain a different conductive material than the first source electrode 171 and the second source electrode 172.

[0066] The second drain electrode 192 is located above the first drain electrode 191. The second drain electrode 192 is in contact with the first drain electrode 191. The second drain electrode 192 is located above the side surface of the second protective layer 220, which will be described later. The second drain electrode 192 is in contact with the second protective layer 220, which will be described later. In this embodiment, the second drain electrode 192 covers at least a portion of the upper surface of the second protective layer 220, which will be described later, but is not limited thereto. The second drain electrode 192 contains a conductive material. The second drain electrode 192 contains the same conductive material as the first drain electrode 191, but is not limited thereto. As another example, the second drain electrode 192 may contain a different conductive material than the first drain electrode 191.

[0067] The third drain electrode 193 is located above the second drain electrode 192. The third drain electrode 193 is in contact with the second drain electrode 192. The third drain electrode 193 is located above the side surface of the third protective layer 230, which will be described later. The third drain electrode 193 is in contact with the third protective layer 230, which will be described later. In this embodiment, the third drain electrode 193 covers at least a portion of the upper surface of the third protective layer 230, which will be described later, but is not limited thereto. The third drain electrode 193 contains a conductive material. The third drain electrode 193 contains the same conductive material as the first drain electrode 191 and the second drain electrode 192, but is not limited thereto. As another example, the third drain electrode 193 may contain a different conductive material than the first drain electrode 191 and the second drain electrode 192.

[0068] The field dispersion layer 177 is located between the gate electrode 155 and the drain electrode 190. The field dispersion layer 177 is located between the source electrode 170 and the drain electrode 190. The field dispersion layer 177 overlaps the gate electrode 155, the gate semiconductor layer 152, and the channel layer 132 in the third direction (Z direction).

[0069] The field dispersion layer 177 of the semiconductor device according to this embodiment includes first field dispersion layers 177a to third field dispersion layers 177c that are sequentially located in the third direction (Z direction).

[0070] The first field dispersion layer 177a is located on the first protective layer 210. The first field dispersion layer 177a is located directly above the upper surface of the first protective layer 210. The first field dispersion layer 177a is located between the first protective layer 210 and the second protective layer 220, which will be described later. The lower surface of the first field dispersion layer 177a is in contact with the first protective layer 210. In this embodiment, the first field dispersion layer 177a extends in a first direction (X direction). For example, the first field dispersion layer 177a extends in a first direction (X direction) from one side of the first source electrode 171 toward the first drain electrode 191.

[0071] The first field dispersion layer 177a contains the same material as the first source electrode 171 and is located in the same layer as the first source electrode 171. For example, at least a portion of the first field dispersion layer 177a and the first source electrode 171 is located on the first protective layer 210. At least a portion of the first field dispersion layer 177a and the first source electrode 171 is located directly above the upper surface of the first protective layer 210. At least a portion of the first field dispersion layer 177a and the first source electrode 171 is located between the first protective layer 210 and the second protective layer 220. The first field dispersion layer 177a is formed simultaneously in the same process as the first source electrode 171. For example, the boundary between the first field dispersion layer 177a and the first source electrode 171 is not clear, and the first field dispersion layer 177a is integrated with the first source electrode 171. However, it is not limited to this, and the first field dispersion layer 177a may be a separate component separated from the first source electrode 171. For example, the first field dispersion layer 177a may be located away from the first source electrode 171 in a first direction (X direction). Furthermore, the first field dispersion layer 177a may be located in a different layer from the first source electrode 171 and may be formed by a different process.

[0072] The second field dispersion layer 177b is located above the first field dispersion layer 177a.

[0073] The second field dispersion layer 177b is located separated from the first field dispersion layer 177a in the third direction (Z direction). For example, the second protective layer 220, which will be described later, is located between the second field dispersion layer 177b and the first field dispersion layer 177a. The second field dispersion layer 177b is located above the second protective layer 220. The second field dispersion layer 177b is located directly above the upper surface of the second protective layer 220. The second field dispersion layer 177b is located between the second protective layer 220 and the third protective layer 230, which will be described later. The lower surface of the second field dispersion layer 177b is in contact with the second protective layer 220, which will be described later. The upper surface of the second field dispersion layer 177b is in contact with the third protective layer 230, which will be described later.

[0074] In this embodiment, the second field dispersion layer 177b extends in a first direction (X direction). For example, the second field dispersion layer 177b extends in a first direction (X direction) from one side of the second source electrode 172 toward the second drain electrode 192. In this embodiment, the length of the second field dispersion layer 177b along the first direction (X direction) is greater than the length of the first field dispersion layer 177a along the first direction (X direction). One end of the second field dispersion layer 177b protrudes toward the drain electrode 190 more than one end of the first field dispersion layer 177a. For example, one end of the second field dispersion layer 177b is located closer to the drain electrode 190 than one end of the first field dispersion layer 177a.

[0075] The second field dispersion layer 177b contains the same material as the second source electrode 172 and is located in the same layer as the second source electrode 172. For example, at least a portion of the second field dispersion layer 177b and the second source electrode 172 is located on the second protective layer 220. At least a portion of the second field dispersion layer 177b and the second source electrode 172 is located directly above the upper surface of the second protective layer 220. At least a portion of the second field dispersion layer 177b and the second source electrode 172 is located between the second protective layer 220 and the third protective layer 230. The second field dispersion layer 177b is formed simultaneously in the same process as the second source electrode 172. For example, the boundary between the second field dispersion layer 177b and the second source electrode 172 is not clearly defined, and the second field dispersion layer 177b is integrally formed with the second source electrode 172. However, it is not limited to this, and the second field dispersion layer 177b may be a separate component separated from the second source electrode 172. For example, the second field dispersion layer 177b can be located away from the second source electrode 172 in the first direction (X direction). Furthermore, the second field dispersion layer 177b can be located in a different layer from the second source electrode 172 and can be formed by a different process.

[0076] The third field dispersion layer 177c is located above the second field dispersion layer 177b. The third field dispersion layer 177c is located separated from the second field dispersion layer 177b in the third direction (Z direction). For example, the third protective layer 230, which will be described later, is located between the third field dispersion layer 177c and the second field dispersion layer 177b. The third field dispersion layer 177c is located above the third protective layer 230. The third field dispersion layer 177c is located directly above the upper surface of the third protective layer 230. The third field dispersion layer 177c is located between the third protective layer 230 and the capping layer (240 in Figure 11), which will be described later. The lower surface of the third field dispersion layer 177c is in contact with the third protective layer 230, which will be described later.

[0077] In this embodiment, the third field dispersion layer 177c extends in a first direction (X direction). For example, the third field dispersion layer 177c extends in a first direction (X direction) from one side of the third source electrode 173 toward the third drain electrode 193. In this embodiment, the length of the third field dispersion layer 177c along the first direction (X direction) is greater than the length of the second field dispersion layer 177b along the first direction (X direction). One end of the third field dispersion layer 177c protrudes toward the drain electrode 190 more than one end of the second field dispersion layer 177b. For example, one end of the third field dispersion layer 177c is located closer to the drain electrode 190 than one end of the second field dispersion layer 177b.

[0078] The third field dispersion layer 177c contains the same material as the third source electrode 173 and is located in the same layer as the third source electrode 173. For example, at least a portion of the third field dispersion layer 177c and the third source electrode 173 is located on the third protective layer 230. At least a portion of the third field dispersion layer 177c and the third source electrode 173 is located directly above the upper surface of the third protective layer 230. The third field dispersion layer 177c is formed simultaneously with the third source electrode 173 in the same process. For example, the boundary between the third field dispersion layer 177c and the third source electrode 173 is not clear, and the third field dispersion layer 177c is formed integrally with the third source electrode 173. However, it is not limited to this, and the third field dispersion layer 177c may be a separate component separated from the third source electrode 173. For example, the first field dispersion layer 177a may be located separated from the first source electrode 171 in a first direction (X direction). Furthermore, the third field dispersion layer 177c can be located in a different layer from the third source electrode 173, and can also be formed by a different process.

[0079] Multiple field dispersion layers (177a-177c) play a role in dispersing the electric field concentrated around the gate electrode 155. Specifically, when a high voltage is applied to the drain electrode 190 in the gate-off state, a very high concentration of two-dimensional electron gas 134 is located in the channel layer 132 between the gate electrode 155 and the drain electrode 190. In this case, the electric field is concentrated at the edge of the gate electrode 155 or gate semiconductor layer 152 near the drain electrode. On the other hand, the gate electrode 155 and gate semiconductor layer 152 are vulnerable to electric fields, and when the electric field is concentrated, the leakage current increases and the breakdown voltage of the semiconductor device decreases. At this time, the multiple field dispersion layers (177a-177c) can disperse the electric field concentrated around the gate electrode 155 or gate semiconductor layer 152, reducing the leakage current and increasing the breakdown voltage. In particular, the distance along the first direction (X direction) between one end of the second field dispersion layer 177b and the second drain electrode 192 is smaller than the distance along the first direction (X direction) between one end of the first field dispersion layer 177a and the first drain electrode 191, and the distance along the first direction (X direction) between one end of the third field dispersion layer 177c and the third drain electrode 193 is smaller than the distance along the first direction (X direction) between one end of the second field dispersion layer 177b and the second drain electrode 192, so that the electric field concentrated around the gate electrode 155 or gate semiconductor layer 152 can be effectively dispersed.

[0080] Figures 1 and 2 show a semiconductor device according to this embodiment that includes three field dispersion layers (177a to 177c), but the number of field dispersion layers 177 is not limited to this.

[0081] The second protective layer 220 is located on top of the first protective layer 210. The second protective layer 220 is located directly above the first protective layer 210. The second protective layer 220 covers the first protective layer 210 and the first field dispersion layer 177a. The second protective layer 220 is located between the first field dispersion layer 177a and the second field dispersion layer 177b. The lower surface of the second protective layer 220 is in contact with the first protective layer 210 and the first field dispersion layer 177a, and the upper surface of the second protective layer 220 is in contact with the second field dispersion layer 177b. The second protective layer 220 is also located on the sides of the source electrode 170 and the drain electrode 190. For example, the second protective layer 220 is located on the sides of the second source electrode 172 and the second drain electrode 192. The second protective layer 220 covers at least a portion of the side surfaces of the second source electrode 172 and the second drain electrode 192. The second protective layer 220 is located on, but is not limited to, the side surfaces of the first source electrode 171 and the first drain electrode 191. In this embodiment, the thickness of the second protective layer 220 along the third direction (Z direction) is greater than, but is not limited to, the thickness of the first protective layer 210 along the third direction (Z direction).

[0082] The second protective layer 220 contains an insulating material. The second protective layer 220 contains, but is not limited to, the same material as the first protective layer 210. For example, the second protective layer 220 contains, but is not limited to, oxides such as silicon oxide (SiO2) or aluminum oxide (Al2O3). As another example, the second protective layer 220 may also contain nitrates such as silicon nitride (SiN) or nitrates such as silicon nitride (SiON).

[0083] The second protective layer 220 contains the first substance. In one embodiment, the second protective layer 220 contains the first substance in a second content (at%). The second content (at%) of the first substance in the second protective layer 220 is greater than the first content (at%) of the first substance in the first protective layer 210. In one embodiment, the second content (at%) of the first substance in the second protective layer 220 remains constant even when farther away from the upper surface (136_U) of the barrier layer 136, but is not limited to this. For example, the second content (at%) of the first substance in the second protective layer 220 may increase as it moves further away from the upper surface (136_U) of the barrier layer 136. As another example, the second content (at%) of the first substance in the second protective layer 220 may include a portion that decreases as it moves further away from the upper surface (136_U) of the barrier layer 136. A detailed explanation of this will be given later in Figures 3A to 3D.

[0084] Figures 1 and 2 show the second protective layer 220 as a single layer, but it is not limited to this. The second protective layer 220 can also be formed from two or more layers having different content (at%) of the first substance. This will be explained later with reference to Figures 8 and 9.

[0085] The third protective layer 230 is located on top of the second protective layer 220. The third protective layer 230 is located directly above the second protective layer 220. The third protective layer 230 covers the second protective layer 220 and the second field dispersion layer 177b. The third protective layer 230 is located between the second field dispersion layer 177b and the third field dispersion layer 177c. The lower surface of the third protective layer 230 is in contact with the second protective layer 220 and the second field dispersion layer 177b, and the upper surface of the third protective layer 230 is in contact with the third field dispersion layer 177c. The third protective layer 230 is also located on the sides of the source electrode 170 and the drain electrode 190. For example, the third protective layer 230 is located on the sides of the third source electrode 173 and the third drain electrode 193. The third protective layer 230 covers at least a portion of the side surfaces of the third source electrode 173 and the third drain electrode 193. The third protective layer 230 is located on, but is not limited to, the side surfaces of the second source electrode 172 and the second drain electrode 192. In this embodiment, the thickness of the third protective layer 230 along the third direction (Z direction) is greater than the thickness of the second protective layer 220 along the third direction (Z direction).

[0086] The third protective layer 230 contains the first substance. In one embodiment, the third protective layer 230 includes a portion in which the content (at%) of the first substance in the third protective layer 230 is greater than the first content (at%) of the first substance in the first protective layer 210. In one embodiment, the third protective layer 230 includes a portion in which the content (at%) of the first substance in the third protective layer 230 is greater than the second content (at%) of the first substance in the second protective layer 220. For example, the maximum content (at%) refers to the content (at%) of the portion having the largest content (at%) within the composition. In this case, the maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the first protective layer 210. The maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the second protective layer 220. A detailed explanation of this will be given later with reference to Figures 3A to 3D.

[0087] The third protective layer 230 of the semiconductor device according to this embodiment includes a third lower protective layer 231 located on the second protective layer 220 and a third upper protective layer 232 located on the third lower protective layer 231.

[0088] The third lower protective layer 231 is located on the second protective layer 220 and the second field dispersion layer 177b. The third lower protective layer 231 is located directly above the second protective layer 220. The third lower protective layer 231 covers the second field dispersion layer 177b. The lower surface of the third lower protective layer 231 is in contact with the second protective layer 220 and the second field dispersion layer 177b.

[0089] The third lower protective layer 231 contains an insulating material. The third lower protective layer 231 contains, but is not limited to, the same material as the first protective layer 210 and the second protective layer 220. For example, the third lower protective layer 231 contains, but is not limited to, oxides such as silicon oxide (SiO2) or aluminum oxide (Al2O3). As another example, the third lower protective layer 231 may also contain nitrates such as silicon nitride (SiN) or nitrates such as silicon nitrogen oxide (SiON).

[0090] The third lower protective layer 231 contains the first substance. In one embodiment, the third lower protective layer 231 contains the first substance in a third content (at%). The third content (at%) of the first substance in the third lower protective layer 231 is greater than the first content (at%) of the first substance in the first protective layer 210. The third content (at%) of the first substance in the third lower protective layer 231 is greater than the second content (at%) of the first substance in the second protective layer 220. However, it is not limited to this, and the third content (at%) of the first substance in the third lower protective layer 231 may be less than or the same as the second content (at%) of the first substance in the second protective layer 220. An explanation regarding this will be given later with reference to Figures 3A to 3D.

[0091] The third upper protective layer 232 is located on top of the third lower protective layer 231. The third upper protective layer 232 is located between the third lower protective layer 231 and the third field dispersion layer 177c. The upper surface of the third upper protective layer 232 is in contact with the third field dispersion layer 177c.

[0092] The third upper protective layer 232 contains an insulating material. In one embodiment, the third upper protective layer 232 contains the same material as the third lower protective layer 231, but is not limited thereto. The third upper protective layer 232 contains the same material as the first protective layer 210 and the second protective layer 220, but is not limited thereto. For example, the third upper protective layer 232 contains oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3), but is not limited thereto. As another example, the third upper protective layer 232 may also contain nitrates such as silicon nitride (SiN) or nitrates such as silicon nitride (SiON).

[0093] The third upper protective layer 232 contains the first substance. In one embodiment, the third upper protective layer 232 contains the first substance in a fourth content (at%). The fourth content (at%) of the first substance in the third upper protective layer 232 is greater than the first content (at%) of the first substance in the first protective layer 210. The fourth content (at%) of the first substance in the third upper protective layer 232 is greater than the second content (at%) of the first substance in the second protective layer 220. However, it is not limited to this, and the fourth content (at%) of the first substance in the third upper protective layer 232 may be less than or the same as the second content (at%) of the first substance in the second protective layer 220. An explanation relating to this will be given later with reference to Figures 3A to 3D.

[0094] Figures 1 and 2 show the third protective layer 230 as being composed of a double layer, but it is not limited to this, and the third protective layer 230 can be formed of three or more layers having different content (at%) of the first substance. This will be explained later with reference to Figures 4 to 6E.

[0095] The first to third protective layers of a semiconductor device according to one embodiment will be described below with further reference to Figures 3A to 3D.

[0096] Figures 3A to 3D are graphs showing various examples of the content of the first substance in the first to third protective layers of a semiconductor device according to one embodiment.

[0097] As described above, the first protective layer 210 is located on top of the barrier layer 136, the second protective layer 220 is located on top of the first protective layer 210, and the third protective layer 230 is located on top of the second protective layer 220. The first protective layer 210 to the third protective layer 230 contain the first substance.

[0098] Referring further to Figures 3A to 3D, the third protective layer 230 of a semiconductor device according to one embodiment includes a portion in which the content (at%) of the first substance in the third protective layer 230 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210. In this case, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210. The maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the first protective layer 210.

[0099] For example, as shown in Figure 3A, the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210. In this case, the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210, but is not limited to this. For example, the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 may be less than or the same as the first content (N1) (at%) of the first substance in the first protective layer 210. In summary, the maximum content (at%) of the first substance in the third protective layer 230 is the third content (N3) (at%) of the first substance in the third lower protective layer 231, and the maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the first protective layer 210.

[0100] As another example, as shown in Figure 3B, the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210. In this case, the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210, but is not limited to this. For example, the third content (N3) (at%) of the first substance in the third lower protective layer 231 may be less than or the same as the first content (N1) (at%) of the first substance in the first protective layer 210. In summary, the maximum content (at%) of the first substance in the third protective layer 230 is the fourth content (N4) (at%) of the first substance in the third upper protective layer 232, and the maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the first protective layer 210.

[0101] In one embodiment, the third protective layer 230 of a semiconductor device includes a portion in which the content (at%) of the first substance in the third protective layer 230 is greater than the second content (N2) (at%) of the first substance in the second protective layer 220. In this case, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than or equal to the second content (N2) (at%) of the first substance in the second protective layer 220.

[0102] For example, as shown in Figure 3A, the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than or equal to the second content (N2) (at%) of the first substance in the second protective layer 220. In this case, the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 is less than the second content (N2) (at%) of the first substance in the second protective layer 220. However, it is not limited to this, and the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 may be greater than or equal to the second content (N2) (at%) of the first substance in the second protective layer 220.

[0103] As another example, as shown in Figure 3B, the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 is greater than or equal to the second content (N2) (at%) of the first substance in the second protective layer 220. In this case, the third content (N3) (at%) of the first substance in the third lower protective layer 231 is less than the second content (N2) (at%) of the first substance in the second protective layer 220. However, it is not limited to this, and the third content (N3) (at%) of the first substance in the third lower protective layer 231 may be greater than or equal to the second content (N2) (at%) of the first substance in the second protective layer 220.

[0104] In one embodiment, the content (at%) of the first substance in the first protective layer 210, the second protective layer 220, the third lower protective layer 231, and the third upper protective layer 232 remains constant even when far from the upper surface (136_U) of the barrier layer 136, but is not limited to this.

[0105] For example, as shown in Figure 3C, the content (at%) of any one of the first protective layer 210, the second protective layer 220, the third lower protective layer 231, and the third upper protective layer 232 can increase as it moves further away from the upper surface (136_U) of the barrier layer 136. For example, the first content (N1) (at%) of the first substance is at its minimum value (N1min) at the lower surface of the first protective layer 210, and the first content (N1) (at%) of the first substance is at its maximum value (N1max) at the upper surface of the first protective layer 210. The second content (N2) (at%) of the first substance is at its minimum value (N2min) at the lower surface of the second protective layer 220, and the second content (N2) (at%) of the first substance is at its maximum value (N2max) at the upper surface of the second protective layer 220. The third lower protective layer 231 has a minimum value (N3min) for the third content (N3) (at%) of the first substance on its lower surface, and a maximum value (N3max) for the third content (N3) (at%) of the first substance on its upper surface. The third upper protective layer 232 has a minimum value (N4min) for the fourth content (N4) (at%) of the first substance on its lower surface, and a maximum value (N4max) for the fourth content (N4) (at%) of the first substance on its upper surface. In the example shown in Figure 3C, the minimum value (N3min) for the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the maximum value (N1max) for the first content (N1) (at%) of the first substance in the first protective layer 210. The maximum value (N3max) of the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the maximum value (N1max) of the first content (N1) (at%) of the first substance in the first protective layer 210. In summary, the maximum content (at%) of the first substance in the third protective layer 230 is the maximum value (N3max) of the third content (N3) (at%) of the first substance in the third lower protective layer 231, and the maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the first protective layer 210.

[0106] At this time, the rate at which the content (at%) of the first substance in the first protective layer 210, the second protective layer 220, the third lower protective layer 231, and the third upper protective layer 232 increases with respect to a unit distance increases as the distance from the upper surface (136_U) of the barrier layer 136 increases. Here, the rate at which the content (at%) of the first substance increases with respect to a unit distance means the change in content in proportion to the change in distance in the vertical direction (for example, the thickness direction of the channel layer 132, hereinafter referred to as the "third direction (Z direction)"). As an example, the third content (N3) (at%) of the first substance in the third lower protective layer 231 and the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 increase exponentially as the distance from the upper surface (136_U) of the barrier layer 136 increases, but this is not limited to the example.

[0107] As another example, as shown in Figure 3D, the content (at%) of any one of the first protective layer 210, the second protective layer 220, the third lower protective layer 231, and the third upper protective layer 232 may include portions that decrease with increasing distance from the upper surface (136_U) of the barrier layer 136. For example, the third content (N3) (at%) of the first substance is at its minimum value (N3min) at the upper surface of the third lower protective layer 231 and at its maximum value (N3max) at the center of the third lower protective layer 231. The fourth content (N4) (at%) of the first substance is at its minimum value (N4min) at the upper surface of the third upper protective layer 232 and at its maximum value (N4max) at the lower surface of the third upper protective layer 232. In the embodiment shown in Figure 3D, the minimum value (N3min) of the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the maximum value (N1max) of the first content (N1) (at%) of the first substance in the first protective layer 210. The maximum value (N3max) of the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the maximum value (N1max) of the first content (N1) (at%) of the first substance in the first protective layer 210.

[0108] In one embodiment, the second content (N2) (at%) of the first substance in the second protective layer 220 is greater than the first content (N1) (at%) of the first substance in the first protective layer 210.

[0109] In one embodiment, the first content (N1) (at%) of the first substance in the first protective layer 210 of the semiconductor device is smaller than the second content (N2) (at%) of the first substance in the second protective layer 220. Within this range, the first protective layer 210 located on the barrier layer 136 has excellent film quality, and dangling bonds generated at the interface between the barrier layer 136 and the first protective layer 210 can be effectively removed. This can increase the breakdown voltage of the semiconductor device, prevent a decrease in the density of the two-dimensional electron gas 134, and improve the reliability of the semiconductor device.

[0110] Furthermore, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 of the semiconductor device according to one embodiment is greater than the first content (N1) (at%) of the first substance in the first protective layer 210. Also, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the second content (N2) (at%) of the first substance in the second protective layer 220. Within this range, it is possible to prevent a decrease in hole concentration within the gate semiconductor layer 152. In addition, it is possible to prevent a decrease in the density of the two-dimensional electron gas 134 formed in the channel layer 132, thereby preventing degradation of characteristics such as on-current and on-resistance. Therefore, the semiconductor device can have stable electrical characteristics, and reliability can be improved.

[0111] A second example of a semiconductor device according to one embodiment will be described below with reference to Figures 4 to 7.

[0112] Figure 4 is a cross-sectional view showing a second example semiconductor device according to one embodiment. Figure 5 is a cross-sectional view showing the first to third protective layers of the embodiment in Figure 4. Figures 6A to 6E are graphs showing various examples of the content of the first substance in the first to third protective layers of the semiconductor device according to the embodiment in Figure 4. Figure 7 is a cross-sectional view showing the first to third protective layers of the second example semiconductor device according to one embodiment.

[0113] Figures 4 to 7 show various modifications of the semiconductor device according to one embodiment shown in Figures 1 to 3D. Since the embodiment shown in Figures 4 to 7 has a considerable amount of the same parts as the embodiment shown in Figures 1 to 3D, a description of these parts will be omitted, and the focus will be on the differences. In addition, the same reference numerals are used for the same components as in the above-described embodiment.

[0114] Referring to Figures 4 and 5, the third protective layer 230 of the semiconductor device according to this embodiment further includes a third interlayer protective layer 233 located between the third lower protective layer 231 and the third upper protective layer 232.

[0115] The third interlayer protective layer 233 is located between the third lower protective layer 231 and the third upper protective layer 232. The third interlayer protective layer 233 is located between the second field dispersion layer 177b and the third field dispersion layer 177c. The third interlayer protective layer 233 is located between the third source electrode 173 and the third drain electrode 193.

[0116] In this embodiment, the third thickness (TH3) of the third interlayer protective layer 233 along the third direction (Z direction) is smaller than the first thickness (TH1) of the third lower protective layer 231 along the third direction (Z direction). Also, the third thickness (TH3) of the third interlayer protective layer 233 along the third direction (Z direction) is smaller than the second thickness (TH2) of the third upper protective layer 232 along the third direction (Z direction). For example, the third thickness (TH3) of the third interlayer protective layer 233 along the third direction (Z direction) is 1 / 3 to 1 / 64 of the thickness of the third protective layer 230 along the third direction (Z direction), but is not limited to this.

[0117] The third interlayer protective layer 233 is located in the center of the third protective layer 230. In this embodiment, the distance along the third direction (Z direction) between the lower surface of the third interlayer protective layer 233 and the lower surface of the third lower protective layer 231 is substantially the same as the distance between the upper surface of the third interlayer protective layer 233 and the upper surface of the third upper protective layer 232, but is not limited to this. For example, the distance along the third direction (Z direction) between the lower surface of the third interlayer protective layer 233 and the lower surface of the third lower protective layer 231 may be greater than or less than the distance between the upper surface of the third interlayer protective layer 233 and the upper surface of the third upper protective layer 232.

[0118] In one embodiment, the third interlayer protective layer 233 contains a different substance from the third lower protective layer 231 and the third upper protective layer 232. For example, the third interlayer protective layer 233 contains nitrates such as silicon nitride (SiN) or nitrates such as silicon nitrile oxide (SiON). As another example, the third interlayer protective layer 233 may also contain oxides such as silicon oxide (SiO2) or aluminum oxide (Al2O3). In one embodiment, the third interlayer protective layer 233 contains silicon nitride (SiN), silicon nitrile oxide (SiON), or a combination thereof, and the third lower protective layer 231 and the third upper protective layer 232 contain silicon oxide (SiO2).

[0119] Referring further to Figure 6A, the third interlayer protective layer 233 of a semiconductor device according to one embodiment contains the first substance. In one embodiment, the third interlayer protective layer 233 contains the first substance in a fifth content (N5) (at%).

[0120] In one embodiment, the fifth content (N5) (at%) of the first substance in the third interlayer protective layer 233 is greater than or equal to the first content (N1) (at%) of the first substance in the first protective layer 210 and the second content (N2) (at%) of the first substance in the second protective layer 220. Furthermore, the fifth content (N5) (at%) of the first substance in the third interlayer protective layer 233 is greater than the third content (N3) (at%) of the first substance in the third lower protective layer 231 and the fourth content (N4) (at%) of the first substance in the third upper protective layer 232. Within this range, it is possible to prevent a decrease in hole concentration within the gate semiconductor layer 152. In addition, it is possible to prevent a decrease in the density of the two-dimensional electron gas 134 formed in the channel layer 132, thereby preventing degradation of characteristics such as on-current and on-resistance. Therefore, the semiconductor device can have stable electrical characteristics, and reliability can be improved.

[0121] In one embodiment, the third content (N3)(at%) of the first substance in the third lower protective layer 231 and the fourth content (N4)(at%) of the first substance in the third upper protective layer 232 are varied. For example, as shown in Figure 6A, the third content (N3)(at%) of the first substance in the third lower protective layer 231 and the fourth content (N4)(at%) of the first substance in the third upper protective layer 232 are smaller than the second content (N2)(at%) of the first substance in the second protective layer 220. The third content (N3)(at%) of the first substance in the third lower protective layer 231 and the fourth content (N4)(at%) of the first substance in the third upper protective layer 232 are substantially the same as the first content (N1)(at%) of the first substance in the first protective layer 210. As another example, as shown in Figure 6B, the third content (N3) (at%) of the first substance in the third lower protective layer 231 and the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 are greater than the first content (N1) (at%) of the first substance in the first protective layer 210.

[0122] As another example, as shown in Figure 6C, the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the fourth content (N4) (at%) of the first substance in the third upper protective layer 232. The third content (N3) (at%) of the first substance in the third lower protective layer 231 is substantially the same as the second content (N2) (at%) of the first substance in the second protective layer 220, or the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 is less than the second content (N2) (at%) of the first substance in the second protective layer 220.

[0123] As another example, as shown in Figure 6D, the third content (N3) (at%) of the first substance in the third lower protective layer 231 is greater than the second content (N2) (at%) of the first substance in the second protective layer 220. As yet another example, as shown in Figure 6E, the third content (N3) (at%) of the first substance in the third lower protective layer 231 and the fourth content (N4) (at%) of the first substance in the third upper protective layer 232 are greater than the second content (N2) (at%) of the first substance in the second protective layer 220.

[0124] In summary, the content (at%) of any one of the third lower protective layer 231, the third interlayer protective layer 233, and the third upper protective layer 232 is greater than or equal to the first content (N1) (at%) of the first substance in the first protective layer 210. Furthermore, the content (at%) of any one of the third lower protective layer 231, the third interlayer protective layer 233, and the third upper protective layer 232 is greater than or equal to the second content (N2) (at%) of the first substance in the second protective layer 220.

[0125] The third lower protective layer 231, the third interlayer protective layer 233, and the third upper protective layer 232 of the semiconductor device according to one embodiment may contain a first substance in various amounts (at%). In one embodiment, the fifth content (N5) (at%) of the first substance in the third interlayer protective layer 233 is greater than or equal to the first content (N1) (at%) of the first substance in the first protective layer 210 and the second content (N2) (at%) of the first substance in the second protective layer 220. Such characteristics can further prevent a decrease in the density of the two-dimensional electron gas 134 formed in the channel layer 132, and further prevent degradation of characteristics such as on-current and on-resistance. Therefore, the semiconductor device can have stable electrical characteristics and its reliability can be improved.

[0126] Referring to Figure 7, the third protective layer 230_1 of the semiconductor device in the second example according to one embodiment may include a plurality of regions (AR1 to AR3) containing a first material and a second material different from the first material.

[0127] For example, the third protective layer 230_1 includes a first region (AR1) to a third region (AR3) that are sequentially located on the second protective layer 220 along the third direction (Z direction). The third region (AR3) is located between the first region (AR1) and the second region (AR2).

[0128] Regions 1 (AR1) to 3 (AR3) contain the same substance. For example, regions 1 (AR1) to 3 (AR3) contain, but are not limited to, silicon oxide (SiO2) or silicon nitrogen oxide (SiON).

[0129] Regions 1 (AR1) to 3 (AR3) contain a first substance and a second substance different from the first substance. Here, the first substance includes hydrogen (H), carbon (C), or a combination thereof, and the second substance includes nitrogen (N). In one embodiment, the content (at%) of the second substance in each of regions 1 (AR1) to 3 (AR3) is different. For example, the content (at%) of the second substance in region 3 (AR3) is greater than the content (at%) of the second substance in region 1 (AR1). The content (at%) of the second substance in region 3 (AR3) is greater than the content (at%) of the second substance in region 2 (AR2). In one embodiment, the content (at%) of the second substance in region 1 (AR1) increases with increasing distance from the upper surface of the second protective layer 220, but is not limited to this. Furthermore, the content (at%) of the second substance in the third region (AR3) increases and decreases as it moves further away from the upper surface of the second protective layer 220, but is not limited to this. Also, the content (at%) of the second substance in the second region (AR2) decreases as it moves further away from the upper surface of the second protective layer 220, but is not limited to this.

[0130] Hereinafter, various examples of semiconductor devices according to one embodiment will be described with reference to Figures 8 to 12.

[0131] Figures 8 to 12 are cross-sectional views showing various examples of semiconductor devices according to one embodiment.

[0132] Figures 8 to 12 show various modifications of the semiconductor device according to one embodiment shown in Figures 1 to 3D. Since the embodiments shown in Figures 8 to 12 correspond to the same parts as the embodiments shown in Figures 1 to 3D, a description of those parts will be omitted, and the focus will be on the differences. In addition, the same reference numerals are used for the same components as in the embodiments described above.

[0133] Referring to Figure 8, the second protective layer 220 of the third example semiconductor device according to this embodiment includes a second lower protective layer 221 located on the first protective layer 210, and a second upper protective layer 222 located on the second lower protective layer 221.

[0134] The second lower protective layer 221 is located on top of the first protective layer 210 and the first field dispersion layer 177a. The second lower protective layer 221 covers the first field dispersion layer 177a. The lower surface of the second lower protective layer 221 is in contact with the first protective layer 210 and the first field dispersion layer 177a. The second upper protective layer 222 is located on top of the second lower protective layer 221. The second upper protective layer 222 is located between the third lower protective layer 231 and the second lower protective layer 221. The upper surface of the second upper protective layer 222 is in contact with the second field dispersion layer 177b.

[0135] The second lower protective layer 221 and the second upper protective layer 222 contain an insulating material. The second lower protective layer 221 contains the same material as the third lower protective layer 231, and the second upper protective layer 222 contains the same material as the third upper protective layer 232, but is not limited thereto. For example, the second lower protective layer 221 and the second upper protective layer 222 contain oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3), but are not limited thereto. As another example, the second lower protective layer 221 and the second upper protective layer 222 contain nitrates such as silicon nitride (SiN) and nitrogen oxides such as silicon nitrogen oxide (SiON). The second lower protective layer 221 and the second upper protective layer 222 contain a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof.

[0136] In one embodiment, the content (at%) of one of the second lower protective layer 221 and the second upper protective layer 222 is greater than the first content (at%) of the first substance in the first protective layer 210. For example, the content (at%) of one of the second lower protective layer 221 and the second upper protective layer 222 is greater than the first content (at%) of the first substance in the first protective layer 210, and the content (at%) of the other one is less than or equal to the first content (at%) of the first substance in the first protective layer 210.

[0137] In one embodiment, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the content (at%) of the first substance in the second lower protective layer 221. Also, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the content (at%) of the first substance in the second upper protective layer 222.

[0138] Referring to Figure 9, the second protective layer 220 of the fourth example semiconductor device according to this embodiment further includes a second interlayer protective layer 223 located between the second lower protective layer 221 and the second upper protective layer 222.

[0139] The second interlayer protective layer 223 is located between the second lower protective layer 221 and the second upper protective layer 222. The second interlayer protective layer 223 is located between the first field dispersion layer 177a and the second field dispersion layer 177b. The second interlayer protective layer 223 is located between the second source electrode 172 and the second drain electrode 192.

[0140] In one embodiment, the thickness of the second interlayer protective layer 223 along the third direction (Z direction) is smaller than the thickness of the second lower protective layer 221 along the third direction (Z direction). Also, the thickness of the second interlayer protective layer 223 along the third direction (Z direction) is smaller than the thickness of the second upper protective layer 222 along the third direction (Z direction). For example, the thickness of the second interlayer protective layer 223 along the third direction (Z direction) is 1 / 3 to 1 / 64 of the thickness of the second protective layer 220 along the third direction (Z direction), but is not limited to this.

[0141] In one embodiment, the second interlayer protective layer 223 contains a different substance from the second lower protective layer 221 and the second upper protective layer 222. For example, the second interlayer protective layer 223 contains nitrates such as silicon nitride (SiN) or nitrates such as silicon nitrile oxide (SiON). As another example, the second interlayer protective layer 223 contains oxides such as silicon oxide (SiO2) or aluminum oxide (Al2O3). In one embodiment, the second interlayer protective layer 223 contains silicon nitride (SiN), silicon nitrile oxide (SiON), or a combination thereof, and the second lower protective layer 221 and the second upper protective layer 222 contain silicon oxide (SiO2).

[0142] In one embodiment, the second interlayer protective layer 223 of a semiconductor device contains a first substance. Here, the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof. In one embodiment, the content (at%) of the first substance in the second interlayer protective layer 223 is greater than the first content (at%) of the first substance in the first protective layer 210. Also, the content (at%) of the first substance in the second interlayer protective layer 223 is greater than the content (at%) of the first substance in the second lower protective layer 221 and the second upper protective layer 222. In one embodiment, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the content (at%) of the first substance in the second interlayer protective layer 223.

[0143] Referring to Figure 10, the first protective layer 210 of the fifth example semiconductor device according to this embodiment includes a first lower protective layer 211 located on the barrier layer 136, and a first upper protective layer 212 located on the first lower protective layer 211.

[0144] The first lower protective layer 211 is located on top of the barrier layer 136 and the gate electrode 155. The first lower protective layer 211 covers the gate electrode 155. The lower surface of the first lower protective layer 211 is in contact with the barrier layer 136 and the gate electrode 155. The first upper protective layer 212 is located on top of the first lower protective layer 211. The first upper protective layer 212 is located between the second protective layer 220 and the first lower protective layer 211. The upper surface of the first upper protective layer 212 is in contact with the first field dispersion layer 177a.

[0145] The first lower protective layer 211 and the first upper protective layer 212 contain an insulating material.

[0146] The first lower protective layer 211 contains the same material as the third lower protective layer 231, and the first upper protective layer 212 contains the same material as the third upper protective layer 232, but is not limited thereto. For example, the first lower protective layer 211 and the first upper protective layer 212 contain oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3), but are not limited thereto. As another example, the first lower protective layer 211 may contain oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3), and the first upper protective layer 212 may contain nitrates such as silicon nitride (SiN) or nitrates such as silicon nitrogen oxide (SiON).

[0147] The first lower protective layer 211 and the first upper protective layer 212 contain a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof. In one embodiment, the content (at%) of the first substance in the first upper protective layer 212 is greater than the content (at%) of the first substance in the first lower protective layer 211.

[0148] In one embodiment, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the content (at%) of the first substance in the first lower protective layer 211. Also, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the content (at%) of the first substance in the first upper protective layer 212.

[0149] It goes without saying that the embodiments of Figures 4 to 7 can be applied to the embodiment of Figure 11. The first protective layer 210 of the semiconductor device according to one embodiment may further include a first interlayer protective layer located between the first lower protective layer 211 and the first upper protective layer 212 and containing the first substance. The content (at%) of the first substance in the first interlayer protective layer is greater than the content (at%) of the first substance in the first lower protective layer 211 and the content (at%) of the first substance in the first upper protective layer 212.

[0150] Referring to Figure 11, the sixth semiconductor device according to this embodiment further includes a capping layer 240 located on the third protective layer 230 and the third field dispersion layer 177c. The capping layer 240 covers the third field dispersion layer 177c. The lower surface of the capping layer 240 is in contact with the third field dispersion layer 177c and the third protective layer 230. The thickness of the capping layer 240 along the third direction (Z direction) is greater than the thickness of the third protective layer 230 along the third direction (Z direction). The thickness of the capping layer 240 along the third direction (Z direction) is greater than the thickness of the second protective layer 220 along the third direction (Z direction). The thickness of the capping layer 240 along the third direction (Z direction) is greater than the thickness of the first protective layer 210 along the third direction (Z direction).

[0151] The capping layer 240 contains an insulating material. The capping layer 240 contains, but is not limited to, the same material as the third lower protective layer 231 or the third upper protective layer 232. For example, the capping layer 240 contains, but is not limited to, oxides such as silicon oxide (SiO2) or aluminum oxide (Al2O3). As another example, the capping layer 240 may also contain nitrates such as silicon nitride (SiN) or nitrates such as silicon nitrogen oxide (SiON).

[0152] The capping layer 240 contains a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof. In one embodiment, the content (at%) of the first substance in the capping layer 240 is greater than the content (at%) of the first substance in the first protective layer 210. In one embodiment, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is less than or equal to the content (at%) of the first substance in the capping layer 240. However, the content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 may be greater than the content (at%) of the first substance in the capping layer 240.

[0153] Referring to Figure 12, the capping layer 240 of the seventh example semiconductor device according to this embodiment includes a lower capping layer 241 located on the third field dispersion layer 177c and the third upper protective layer 232, and an upper capping layer 242 located on the lower capping layer 241, and metal wiring for resistance improvement may be further arranged on the upper capping layer 242. The lower capping layer 241 and the upper capping layer 242 contain various insulating materials. In one embodiment, each of the lower capping layer 241 and the upper capping layer 242 contains a first material. The content (at%) of the first material in either the lower capping layer 241 or the upper capping layer 242 is greater than the first content (at%) of the first material in the first protective layer 210.

[0154] It goes without saying that the embodiments in Figures 4 to 7 can be applied to the embodiment in Figure 12. The capping layer 240 of the semiconductor device according to one embodiment may further include an interlayer capping layer containing the first substance, located between the lower capping layer 241 and the upper capping layer 242. The content (at%) of the first substance in the interlayer capping layer is greater than the content (at%) of the first substance in the lower capping layer 241 and the content (at%) of the first substance in the upper capping layer 242.

[0155] A method for manufacturing a semiconductor device according to one embodiment will be described below with reference to Figures 13 to 18.

[0156] Figures 13 to 18 are cross-sectional views showing the process sequence for manufacturing a semiconductor device according to one embodiment.

[0157] First, as shown in Figure 13, a seed layer 121, a buffer layer 120, a channel layer 132, a barrier layer 136, a gate semiconductor material layer 152a, and a gate electrode material layer 155a are sequentially formed on the substrate 110.

[0158] The substrate 110 contains a semiconductor material. For example, the substrate 110 may contain sapphire, Si, SiC, AlN, GaN, or a combination thereof. The substrate 110 is an SOI (Silicon on Insulator) substrate. However, the material of the substrate 110 is not limited to this, and all commonly used substrates may be used.

[0159] The seed layer 121 and the superlattice layer 124 are formed sequentially using an epitaxial growth method. The seed layer 121 and the superlattice layer 124 are composed of the same semiconductor material substrate. However, the material composition ratio of each layer differs, taking into consideration the role of each layer and the performance required for the semiconductor device. The seed layer 121 and the superlattice layer 124 contain one or more materials selected from III-V group materials, such as nitrates containing Al, Ga, In, B, or combinations thereof. The seed layer 121 and the superlattice layer 124 contain Al x In y Ga 1-x-y N is (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). For example, the seed layer 121 and the superlattice layer 124 include AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof.

[0160] In one embodiment, the superlattice layer 124 is composed of multiple layers in which layers containing different materials are stacked alternately. For example, the superlattice layer 124 has a structure in which layers composed of AlGaN and layers composed of AlN are repeatedly stacked. For example, AlGaN / AlN / AlGaN / AlN / AlGaN / AlN are stacked sequentially to form the superlattice layer 124.

[0161] The high-resistance layer 126 is composed of a material with low conductivity so that the substrate 110 and the channel layer 132 are electrically insulated. The high-resistance layer contains one or more materials selected from group III-V materials, such as nitrates containing Al, Ga, In, B, or combinations thereof. The high-resistance layer 126 is composed of Al x In y Ga 1-x-y N is defined as (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). For example, the high-resistance layer 126 includes AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or a combination thereof. The high-resistance layer 126 consists of a single layer or multiple layers.

[0162] In one embodiment, the channel layer 132 and the barrier layer 136 are formed sequentially using an epitaxial growth method. For example, the channel layer 132 is formed on the high-resistance layer 126, and the barrier layer 136 is formed on the channel layer 132.

[0163] The channel layer 132 and the barrier layer 136 are composed of semiconductor material from the same substrate. However, the material composition ratio of each layer differs, taking into consideration the role of each layer and the performance required of the semiconductor device. The channel layer 132 and the barrier layer 136 contain one or more substances selected from III-V group materials, such as nitrates containing Al, Ga, In, B, or combinations thereof. The channel layer 132 and the barrier layer 136 contain Al x In y Ga 1-x-yN is (0 ≤ x ≤ 1, 0 ≤ y ≤ 1, x + y ≤ 1). For example, the channel layer 132 and the barrier layer 136 include AlN, GaN, InN, InGaN, AlGaN, AlInN, AlInGaN, or combinations thereof. The barrier layer 136 includes a material having a different energy band gap than the channel layer 132. The barrier layer 136 has a higher energy band gap than the channel layer 132.

[0164] For example, the substrate 110 contains Si, the seed layer 121 contains AlN, and the superlattice layer 124 contains AlGaN and AlN. The high-resistance layer 126 contains GaN, the channel layer 132 contains GaN, and the barrier layer 136 contains AlGaN. The channel layer 132 and the barrier layer 136 may or may not be doped with impurities.

[0165] The gate electrode material layer 155a is formed using a vapor deposition process. For example, the gate electrode material layer 155a is formed using one of the following techniques: physical vapor deposition (PVD), thermal chemical vapor deposition (thermal CVD), low-pressure chemical vapor deposition (LP-CVD), plasma-enhanced chemical vapor deposition (PE-CVD), or atomic layer deposition (ALD).

[0166] The gate electrode material layer 155a contains a conductive material. For example, the gate electrode material layer 155a contains metals, metal alloys, conductive metal nitrates, metal silicides, doped semiconductor materials, conductive metal oxides, conductive metal nitrogen oxides, etc. For example, the gate electrode material layer 155a contains titanium nitrate (TiN), tantalum carbide (TaC), tantalum nitrate (TaN), titanium silicon nitride (TiSiN), tantalum silicon nitride (TaSiN), tantalum titanium nitrate (TaTiN), titanium aluminum nitrate (TiAlN), tantalum aluminum nitrate (TaAlN), tungsten nitrate (WN), ruthenium (Ru), titanium aluminum (TiAl), titanium aluminum carbide nitrate (TiAlC-N), titanium aluminum carbide (TiAlC), titanium carbide (TiC), tantalum carbide nitrate (TaCN), etc. This includes, but is not limited to, tungsten (W), aluminum (Al), copper (Cu), cobalt (Co), titanium (Ti), tantalum (Ta), nickel (Ni), platinum (Pt), nickel-platinum (Ni-Pt), niobium (Nb), niobium nitrate (NbN), niobium carbide (NbC), molybdenum (Mo), molybdenum nitrate (MoN), molybdenum carbide (MoC), tungsten carbide (WC), rhodium (Rh), palladium (Pd), iridium (Ir), osmium (Os), silver (Ag), gold (Au), zinc (Zn), vanadium (V), or combinations thereof. The gate electrode material layer 155a is composed of a single layer or multiple layers.

[0167] As shown in Figure 14, the gate electrode 155 and gate semiconductor layer 152 are formed by patterning the gate electrode material layer 155a and gate semiconductor material layer 152a using photo and etching processes.

[0168] For example, a hard mask layer and a photoresist layer are sequentially formed on the gate electrode material layer 155a. A photoresist pattern is formed by patterning the photoresist layer using a photoprocess. The hard mask pattern and the gate electrode 155 are formed by etching the hard mask layer and the gate electrode material layer 155a using the photoresist pattern as a mask. Subsequently, at least a portion of the gate semiconductor material layer 152a is removed by etching the gate semiconductor material layer 152a using the hard mask pattern as a mask.

[0169] As a result, the remaining portion of the gate electrode material layer 155a becomes the gate electrode 155. Also, the remaining portion of the gate semiconductor material layer 152a becomes the gate semiconductor layer 152. The gate semiconductor layer 152 is located between the barrier layer 136 and the gate electrode 155. The gate electrode 155 makes Schottky contact or ohmic contact with the gate semiconductor layer 152. At this time, the hard mask layer is removed when etching the gate semiconductor material layer, depending on the etching conditions or the cleaning conditions after etching. Alternatively, the hard mask pattern may remain on the gate electrode 155 without being removed.

[0170] By patterning the gate semiconductor material layer 152a and the gate electrode material layer 155a using the same mask, the gate semiconductor layer 152 and the gate electrode 155 have the same pattern. For example, the gate semiconductor layer 152 and the gate electrode 155 have the same planar shape. In cross-section, the gate semiconductor layer 152 and the gate electrode 155 have the same width. The gate semiconductor layer 152 completely overlaps the gate electrode 155 in the third direction (Z direction), and the upper surface of the gate semiconductor layer 152 is entirely covered by the gate electrode 155, but this is not limited to this. For example, the gate semiconductor layer 152 and the gate electrode 155 can partially overlap in the third direction (Z direction).

[0171] As shown in Figure 15, a first protective layer 210 is formed on the barrier layer 136 and the gate electrode 155. The first protective layer 210 is formed using a vapor deposition process. The first protective layer 210 contains, but is not limited to, oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3). The first protective layer 210 contains a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof.

[0172] As shown in Figure 16, the first protective layer 210 is patterned to form the first trench 141 and the second trench 143, and the first source electrode 171 and the first drain electrode 191 are formed in the first trench 141 and the second trench 143.

[0173] First, the first protective layer 210 is patterned using photoetching and etching processes to form the first trench 141 and the second trench 143. At this time, not only the first protective layer 210, but also the barrier layer 136 and the channel layer 132 are patterned together.

[0174] For example, a photoresist pattern is formed on the first protective layer 210, and this is used as a mask to sequentially etch the first protective layer 210, the barrier layer 136, and the channel layer 132. At this time, the first protective layer 210 and the barrier layer 136 are penetrated by the first trench 141 and the second trench 143, and the upper surface of the channel layer 132 is recessed. The channel layer 132 is not penetrated by the first trench 141 or the second trench 143. For example, the depth to which the upper surface of the channel layer 132 is recessed is less than the total thickness of the channel layer 132. At this time, the depth to which the upper surface of the channel layer 132 is recessed is much smaller than the total thickness of the channel layer 132. Also, the depth to which the upper surface of the channel layer 132 is recessed is larger than the thickness of the barrier layer 136. However, it is not limited to this, and the depth to which the upper surface of the channel layer 132 is recessed can be varied in various ways.

[0175] The first trench 141 and the second trench 143 expose the sides of the first protective layer 210 and the barrier layer 136 to the outside, and the top surface and sides of the channel layer 132. The channel layer 132 forms the bottom surface and side walls of the first trench 141 and the second trench 143, and the barrier layer 136 forms the side walls of the first trench 141 and the second trench 143.

[0176] The first trench 141 and the second trench 143 are spaced apart from each other. The first trench 141 and the second trench 143 are located on either side of the gate electrode 155. The first trench 141 is located on one side of the gate electrode 155, spaced apart from it. The second trench 143 is located on the other side of the gate electrode 155, spaced apart from it. The distance at which the first trench 141 is spaced apart from the gate electrode 155 is smaller than the distance at which the second trench 143 is spaced apart from it. The shapes of the first trench 141 and the second trench 143 are shown as being similar in width, depth, etc., but are not limited to this. The shapes of the first trench 141 and the second trench 143 can be changed in various ways.

[0177] Next, conductive material is deposited in the first trench 141 and the second trench 143, and this is patterned to form the first source electrode 171 and the first drain electrode 191.

[0178] The first source electrode 171 and the first drain electrode 191 contain a conductive material. For example, the first source electrode 171 and the first drain electrode 191 contain metals, metal alloys, conductive metal nitrates, metal silicides, doped semiconductor materials, conductive metal oxides, conductive metal nitrogen oxides, and the like. The first source electrode 171 and the first drain electrode 191 are composed of a single layer or multiple layers. For example, a plurality of conductive layers containing different materials are stacked and then patterned to form the first source electrode 171 and the first drain electrode 191.

[0179] The first source electrode 171 is formed to fill the interior of the first trench 141. The first source electrode 171 is also formed to cover at least a portion of the upper surface of the first protective layer 210. As a result, at least a portion of the first source electrode 171 overlaps the channel layer 132, the barrier layer 136, and the drift region (DTR) in the third direction (Z direction). Within the first trench 141, the first source electrode 171 is in contact with the channel layer 132 and the barrier layer 136. The first source electrode 171 is in contact with the sides of the channel layer 132 and the barrier layer 136. The first source electrode 171 covers the sides of the channel layer 132 and the barrier layer 136. The first source electrode 171 is electrically connected to the channel layer 132 through the first trench 141. The upper surface of the first source electrode 171 protrudes beyond the upper surface of the first protective layer 210.

[0180] The first drain electrode 191 is formed to fill the interior of the second trench 143. The first drain electrode 191 is also formed to cover at least a portion of the upper surface of the first protective layer 210. As a result, at least a portion of the first drain electrode 191 overlaps the channel layer 132, the barrier layer 136, and the drift region (DTR) in the third direction (Z direction). Within the second trench 143, the first drain electrode 191 is in contact with the channel layer 132 and the barrier layer 136. The first drain electrode 191 is in contact with the sides of the channel layer 132 and the barrier layer 136. The first drain electrode 191 covers the sides of the channel layer 132 and the barrier layer 136. The first drain electrode 191 is electrically connected to the channel layer 132 through the second trench 143. The upper surface of the first drain electrode 191 protrudes beyond the upper surface of the first protective layer 210.

[0181] The first source electrode 171 and the first drain electrode 191 are in ohmic contact with the channel layer 132. The regions in the channel layer 132 and the barrier layer 136 that are in contact with the first source electrode 171 and the first drain electrode 191 are doped to a relatively higher concentration than other regions. For example, a portion of the channel layer 132 or the barrier layer 136 is doped by an ion implantation process, an annealing process, etc. However, it is not limited to this, and the doping process of a portion of the channel layer 132 or the barrier layer 136 can be composed of various other processes.

[0182] The doping process of a portion of the channel layer 132 or barrier layer 136 is performed before forming the first source electrode 171 and the first drain electrode 191. In some cases, the channel layer 132 may not be doped.

[0183] A two-dimensional electron gas 134 is formed inside the channel layer 132 in the portion adjacent to the barrier layer 136. The two-dimensional electron gas 134 is located at the interface between the channel layer 132 and the barrier layer 136. The two-dimensional electron gas 134 is located in the drift region (DTR) between the first source electrode 171 and the first drain electrode 191. A depletion region (DPR) is formed within the channel layer 132 by the gate semiconductor layer 152, which has a different energy band gap than the barrier layer 136. Therefore, the semiconductor device according to this embodiment has normally-off characteristics. For example, the semiconductor device according to one embodiment is a normally-off high electron mobility transistor (HEMT). In the gate-off state, the two-dimensional electron gas 134 is located in the drift region (DTR) of the channel layer 132, excluding the depletion region (DPR). In the gate-on state, the flow of the two-dimensional electron gas 134 continues within the depletion region (DPR), and the two-dimensional electron gas 134 is generally located within the drift region (DTR).

[0184] In the step of forming the first source electrode 171 and the first drain electrode 191, the first field dispersion layer 177a is formed together. The first field dispersion layer 177a is located between the first source electrode 171 and the first drain electrode 191. The first field dispersion layer 177a overlaps with the gate electrode 155, but is not limited to this. As another example, the first field dispersion layer 177a may be located away from the first source electrode 171 in a first direction (X direction). The first field dispersion layer 177a is electrically connected to the first source electrode 171. The first field dispersion layer 177a is formed integrally with the first source electrode 171. The first field dispersion layer 177a contains the same material as the first source electrode 171 and is located in the same layer as the first source electrode 171. For example, at least a portion of the first field dispersion layer 177a and the first source electrode 171 is located on the first protective layer 210. At least a portion of the first field dispersion layer 177a and the first source electrode 171 is located directly above the upper surface of the first protective layer 210. At least a portion of the first field dispersion layer 177a and the first source electrode 171 is located between the first protective layer 210 and the second protective layer 220.

[0185] As shown in Figure 17, a second protective layer 220 is formed on the first protective layer 210 and the first field dispersion layer 177a, and a second source electrode 172 and a second drain electrode 192 are formed penetrating the second protective layer 220.

[0186] First, a second protective layer 220 is formed on the first protective layer 210 and the first field dispersion layer 177a. The second protective layer 220 is formed using a vapor deposition process. The second protective layer 220 contains, but is not limited to, oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3). The second protective layer 220 contains a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof. In one embodiment, the second content (at%) of the first substance in the second protective layer 220 is greater than the first content (at%) of the first substance in the first protective layer 210.

[0187] Next, a trench is formed that penetrates the second protective layer 220, exposing the first source electrode 171 and the first drain electrode 191, and the second source electrode 172 and the second drain electrode 192 are formed within the trench. The process of forming the second source electrode 172 and the second drain electrode 192 is substantially the same as the process of forming the first source electrode 171 and the first drain electrode 191, so a detailed explanation of this process is omitted.

[0188] In the step of forming the second source electrode 172 and the second drain electrode 192, the second field dispersion layer 177b is formed together. The second field dispersion layer 177b is located between the second source electrode 172 and the second drain electrode 192. The second field dispersion layer 177b is formed on top of the second protective layer 220. The second field dispersion layer 177b is electrically connected to the second source electrode 172. The second field dispersion layer 177b is formed integrally with the second source electrode 172, but is not limited to this. As another example, the second field dispersion layer 177b may be located away from the second source electrode 172 in a first direction (X direction). The second field dispersion layer 177b contains the same material as the second source electrode 172 and is located in the same layer as the second source electrode 172. For example, at least a portion of the second field dispersion layer 177b and the second source electrode 172 is located on top of the second protective layer 220. At least a portion of the second field dispersion layer 177b and the second source electrode 172 is located directly above the upper surface of the second protective layer 220. At least a portion of the second field dispersion layer 177b and the second source electrode 172 is located between the second protective layer 220 and the third protective layer 230.

[0189] As shown in Figure 18, a third protective layer 230 is formed by sequentially forming a third lower protective layer 231 and a third upper protective layer 232 on the second protective layer 220 and the second field dispersion layer 177b, and a third source electrode 173 and a third drain electrode 193 are formed penetrating the third protective layer 230.

[0190] First, a third lower protective layer 231 and a third upper protective layer 232 are sequentially formed on the second protective layer 220 and the second field dispersion layer 177b. The third protective layer 230 is formed using a vapor deposition process. The third lower protective layer 231 and the third upper protective layer 232 contain, but are not limited to, oxides such as silicon oxide (SiO2) and aluminum oxide (Al2O3). The third lower protective layer 231 and the third upper protective layer 232 may contain the same substance or different substances. The third lower protective layer 231 and the third upper protective layer 232 contain a first substance, where the first substance includes hydrogen (H), carbon (C), nitrogen (N), or a combination thereof.

[0191] In one embodiment, the third protective layer 230 includes a portion in which the content (at%) of the first substance in the third protective layer 230 is greater than the first content (at%) of the first substance in the first protective layer 210. The content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the first content (at%) of the first substance in the first protective layer 210. In this case, the maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the first protective layer 210.

[0192] In one embodiment, the third protective layer 230 includes a portion in which the content (at%) of the first substance in the third protective layer 230 is greater than the second content (at%) of the first substance in the second protective layer 220. The content (at%) of the first substance in either the third lower protective layer 231 or the third upper protective layer 232 is greater than the second content (at%) of the first substance in the second protective layer 220. In this case, the maximum content (at%) of the first substance in the third protective layer 230 is greater than the maximum content (at%) of the first substance in the second protective layer 220.

[0193] Next, a trench is formed that penetrates the third protective layer 230, exposing the second source electrode 172 and the second drain electrode 192, and the third source electrode 173 and the third drain electrode 193 are formed within the trench. The process of forming the third source electrode 173 and the third drain electrode 193 is substantially the same as the process of forming the second source electrode 172 and the second drain electrode 192, so a detailed explanation of this process is omitted.

[0194] In the step of forming the third source electrode 173 and the third drain electrode 193, the third field dispersion layer 177c is formed together. The third field dispersion layer 177c is located between the third source electrode 173 and the second drain electrode 192. The third field dispersion layer 177c is formed on top of the third protective layer 230. The third field dispersion layer 177c is electrically connected to the third source electrode 173. The third field dispersion layer 177c is formed integrally with the third source electrode 173, but is not limited to this. As another example, the third field dispersion layer 177c may be located separated from the third source electrode 173 in a first direction (X direction). The third field dispersion layer 177c contains the same material as the third source electrode 173 and is located in the same layer as the third source electrode 173. This forms the semiconductor device according to this embodiment. For example, at least a portion of the third field dispersion layer 177c and the third source electrode 173 is located on top of the third protective layer 230. At least a portion of the third field dispersion layer 177c and the third source electrode 173 is located directly above the upper surface of the third protective layer 230.

[0195] Although embodiments of the present invention have been described in detail above with reference to the drawings, the present invention is not limited to the embodiments described above, and can be modified and implemented in various ways without departing from the technical spirit of the present invention. [Explanation of symbols]

[0196] 110 circuit boards 120 buffer layers 121 Seed Layer 124 Superlattice layer 126 High resistance layer 132 channel layer 134 Two-dimensional electron gas 136 Barrier layer 136_U Upper surface of the barrier layer 141, 143 Trench 1 and 2 152 Gate Semiconductor Layer 152a Gate semiconductor material layer 155 Gate Stop 155a Gridgate material layer 170 Source Electrodes 171, 172, 173 First to third source electrodes 177 Field Dispersion Layer 177a, 177b, 177c: 1st to 3rd field dispersion layers 190 Drain electrode 191, 192, 193 First to third drain electrodes 210, 220 1st and 2nd protective layer 211, 221, 231 1st to 3rd lower protective layer 212, 222, 232 1st to 3rd upper protective layer 223, 233 2nd and 3rd interlayer protective layer 230, 230_1 3rd protective layer 240 capping layers AR1~AR3 1st~3rd area DTR Drift Region DPR depletion region N1~N5 1st~5th content

Claims

1. Channel layer and A barrier layer comprising a material located on the channel layer and having a different energy band gap from the channel layer, A gate electrode located on the barrier layer, A gate semiconductor layer located between the barrier layer and the gate electrode, A first protective layer located on the barrier layer and covering the gate electrode, comprising a first substance, A source electrode located on the first side surface of the gate electrode and connected to the channel layer, A drain electrode is located on the second side surface, which is the opposite side of the first side surface of the gate electrode, and is connected to the channel layer. A first field dispersion layer located on the first protective layer and electrically connected to the source electrode, A second protective layer located on the first protective layer and covering the first field dispersion layer, The third protective layer comprises a third lower protective layer located on the second protective layer and containing the first substance, a third upper protective layer located on the third lower protective layer and containing the first substance, and a third interlayer protective layer located between the third lower protective layer and the third upper protective layer and containing the first substance, A semiconductor device characterized in that the atomic percentage (at%) content (at%) of the first substance in any one of the third lower protective layer, the third interlayer protective layer, and the third upper protective layer is greater than the content (at%) of the first substance in the first protective layer.

2. The semiconductor device according to claim 1, characterized in that the first substance is hydrogen (H), carbon (C), nitrogen (N), or a combination thereof.

3. The second protective layer comprises the first substance, The semiconductor device according to claim 1, characterized in that the content (at%) of the first substance in any one of the third lower protective layer, the third interlayer protective layer, and the third upper protective layer is greater than or equal to the content (at%) of the first substance in the second protective layer.

4. The second protective layer comprises the first substance, The semiconductor element according to claim 1, characterized in that the content (at%) of the first substance in the second protective layer is greater than the content (at%) of the first substance in the first protective layer.

5. The semiconductor element according to claim 1, characterized in that the content (at%) of the first substance in the third interlayer protective layer is greater than the content (at%) of the first substance in the third lower protective layer and the content (at%) of the first substance in the third upper protective layer.

6. The semiconductor element according to claim 5, characterized in that the content (at%) of the first substance in the third lower protective layer is greater than the content (at%) of the first substance in the third upper protective layer.

7. The second protective layer comprises the first substance, The semiconductor element according to claim 1, characterized in that the content (at%) of the first substance in the third upper protective layer is less than or equal to the content (at%) of the first substance in the second protective layer.

8. The third interlayer protective layer comprises silicon nitride, The semiconductor device according to claim 1, characterized in that the third lower protective layer and the third upper protective layer contain silicon oxide.

9. The semiconductor element according to claim 8, characterized in that the thickness of the third interlayer protective layer is less than the thickness of the third lower protective layer.

10. A second field dispersion layer is located between the second protective layer and the third protective layer and is electrically connected to the source electrode, The semiconductor element according to claim 1, further comprising a third field dispersion layer located on the third protective layer and electrically connected to the source electrode.

11. The source electrode is A first source electrode that penetrates the barrier layer and is located on the channel layer, A second source electrode located on the first source electrode, A third source electrode located above the second source electrode, The drain electrode is A first drain electrode that penetrates the barrier layer and is located on the channel layer, A second drain electrode located above the first drain electrode, The system includes a third drain electrode located above the second drain electrode, The second field dispersion layer contains the same material as the second source electrode and is located in the same layer. The semiconductor device according to claim 10, characterized in that the third field dispersion layer contains the same material as the third source electrode and is located in the same layer.

12. A capping layer located on the third protective layer and covering the third field dispersion layer, further comprising the first substance, The semiconductor element according to claim 10, characterized in that the content (at%) of the first substance in either the third lower protective layer or the third upper protective layer is less than or equal to the content (at%) of the first substance in the capping layer.

13. The aforementioned second protective layer is A second lower protective layer located on the first protective layer and containing the first substance, A second upper protective layer containing the first substance is located between the second lower protective layer and the third lower protective layer, and includes the following: The content (at%) of the first substance in either the third lower protective layer or the third upper protective layer is greater than the content (at%) of the first substance in the second lower protective layer. The semiconductor element according to claim 1, characterized in that the content (at%) of the first substance in either the third lower protective layer or the third upper protective layer is greater than the content (at%) of the first substance in the second upper protective layer.

14. The second lower protective layer contains the same material as the third lower protective layer. The semiconductor element according to claim 13, characterized in that the second upper protective layer contains the same material as the third upper protective layer.

15. The semiconductor element according to claim 13, characterized in that the content (at%) of the first substance in either the second lower protective layer or the second upper protective layer is greater than the content (at%) of the first substance in the first protective layer.

16. Channel layer and A barrier layer comprising a material located on the channel layer and having a different energy band gap from the channel layer, A gate electrode located on the barrier layer, A gate semiconductor layer located between the barrier layer and the gate electrode, A first protective layer located on the barrier layer and covering the gate electrode, comprising a first substance, A source electrode located on the first side surface of the gate electrode and connected to the channel layer, A drain electrode located on the second side surface, which is the opposite side of the first side surface of the gate electrode, and connected to the channel layer, A first field dispersion layer, a second field dispersion layer, and a third field dispersion layer are electrically connected to the source electrode and sequentially positioned on the first protective layer, A second protective layer located between the first field dispersion layer and the second field dispersion layer, A third protective layer containing the first substance is located between the second field dispersion layer and the third field dispersion layer, The third protective layer is, A third lower protective layer located above the second field dispersion layer and the second protective layer, The third upper protective layer is located between the third lower protective layer and the third field dispersion layer, A semiconductor device characterized in that the atomic percentage (at%) content (at%) of the first substance in either the third lower protective layer or the third upper protective layer is greater than the content (at%) of the first substance in the first protective layer.

17. The semiconductor device according to claim 16, characterized in that the first substance is hydrogen (H), carbon (C), nitrogen (N), or a combination thereof.

18. The second protective layer comprises the first substance, The semiconductor element according to claim 16, characterized in that the content (at%) of the first substance in either the third lower protective layer or the third upper protective layer is greater than the content (at%) of the first substance in the second protective layer.

19. The semiconductor element according to claim 18, characterized in that the content (at%) of the first substance in the second protective layer is greater than the content (at%) of the first substance in the first protective layer.

20. A channel layer containing GaN, A barrier layer containing AlGaN is located above the channel layer, A gate electrode located on the barrier layer, A gate semiconductor layer containing p-type impurity-doped GaN is located between the barrier layer and the gate electrode, A first protective layer located on the barrier layer and covering the gate electrode, comprising a first substance, A source electrode located on the first side surface of the gate electrode and connected to the channel layer, A drain electrode located on the second side surface, which is the opposite side of the first side surface of the gate electrode, and connected to the channel layer, A first field dispersion layer, a second field dispersion layer, and a third field dispersion layer are electrically connected to the source electrode and sequentially positioned on the first protective layer, A second protective layer containing the first substance is located between the first field dispersion layer and the second field dispersion layer, A third protective layer containing the first substance is located between the first field dispersion layer and the second field dispersion layer, The maximum content (at%) of the first substance in the second protective layer is greater than the maximum atomic percentage content (at%) of the first substance in the first protective layer. A semiconductor device characterized in that the maximum content (at%) of the first substance in the third protective layer is greater than the maximum content (at%) of the first substance in the second protective layer.

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