Hemt device with fin-gate

Abstract

This application relates to a HEMT device with a finned gate, comprising a semiconductor substrate, a buffer layer, multiple first gallium nitride channel layers, multiple second gallium nitride channel layers, a fin, a first gate, a drain 610, and a source. By setting the width of the fin between the first and second gallium nitride channel layers to gradually decrease along the length of the fin, the two-dimensional electron gas at the short side of the fin can be controlled by the first gate, thereby completely disconnecting the connection between the source and drain. Simultaneously, since the on-resistance at the long side of the fin is greater than that at the short side, compared to conventional fins with a consistent width, the fin of this application can control the on / off state of the entire HEMT device through the short side of the fin, and can also achieve a smaller on-resistance for the HEMT device through the long side of the fin.

Description

Technical Field

[0001] This application belongs to the field of semiconductor device technology, and particularly relates to a HEMT device with a fin gate. Background Technology

[0002] GaN possesses many excellent properties, but its poor voltage withstand capability has always been one of the pain points in its applications. If the thickness of the channel layer is increased in order to improve the voltage withstand capability, the current density is too low due to the fact that there is only one layer of two-dimensional electron gas (2DEG).

[0003] Device structures with multilayer GaN channels can simultaneously meet the requirements for voltage withstand capability and current density, but their problem is that they cannot be completely turned off. The gate, conventionally located on the upper surface of a multilayer GaN channel, can only control the two-dimensional electron gas closest to the gate, while other two-dimensional electron gases farther from the gate are difficult to control. This results in high electron mobility transistors (HEMTs) that cannot be completely turned off. Therefore, multilayer GaN channel devices are often used as normally-on (D-mode) HEMTs, with the disadvantage that a negative voltage is required to completely turn off the device, and significant losses occur during shutdown. Summary of the Invention

[0004] The purpose of this application is to provide a HEMT device with a finned gate, which aims to solve the problem of difficult turn-off in traditional multilayer gallium nitride channel semiconductor devices.

[0005] A first aspect of this application provides a HEMT device with a fin gate, comprising: a semiconductor substrate and a buffer layer disposed on the semiconductor substrate; multiple first gallium nitride channel layers, sequentially stacked on the buffer layer; multiple second gallium nitride channel layers, sequentially stacked on the buffer layer, corresponding one-to-one with the multiple first gallium nitride channel layers; and fins disposed on the buffer layer between the first gallium nitride channel layers and the second gallium nitride channel layers, wherein both ends of the fins are in contact with the first gallium nitride channel layer and the second gallium nitride channel layer, respectively, for connecting each first gallium nitride channel layer to each second gallium nitride channel layer. A one-to-one connection is established; a first gate, covering the surface of the fin and located between the first gallium nitride channel layer and the second gallium nitride channel layer, is used to control the on / off state of the two-dimensional electron gas in the fin; wherein the width of the fin gradually decreases along the length of the fin, and the first gate is used to deplete the two-dimensional electron gas on the short side of the fin when zero voltage is applied to the first gate; a drain is disposed on the buffer layer; wherein the drain and the fin are respectively located on both sides of the second gallium nitride channel layer; a source is disposed on the buffer layer; wherein the source and the fin are respectively located on both sides of the first gallium nitride channel layer.

[0006] In one embodiment, the sidewall of the first gallium nitride channel layer connected to the fin is parallel to the sidewall of the second gallium nitride layer connected to the fin, the short side and the long side of the fin are located at the two ends of the fin, and the cross-sectional pattern of the fin is trapezoidal.

[0007] In one embodiment, the cross-sectional pattern of the fin is an isosceles trapezoid.

[0008] In one embodiment, a plurality of fins are provided between the first gallium nitride channel layer and the second gallium nitride channel layer.

[0009] In one embodiment, a plurality of fins are staggered between the first gallium nitride channel layer and the second gallium nitride channel layer, with the short side of the fin and the long side of the adjacent fin located on the same side.

[0010] In one embodiment, the first gate includes a first capping layer and a first connecting metal layer; the first capping layer covers the sidewalls on both sides of the fin and is in contact with each layer of two-dimensional electron gas in the fin; the first connecting metal layer is disposed on the first capping layer and the fin.

[0011] In one embodiment, the first gallium nitride channel layer includes a first channel layer and a first barrier layer, with the first barrier layer disposed on the first channel layer; the second gallium nitride channel layer includes a second channel layer and a second barrier layer, with the second barrier layer disposed on the second channel layer.

[0012] In one embodiment, the fin includes multiple third channel layers and multiple third barrier layers, wherein the third barrier layers and the third channel layers are alternately stacked on the buffer layer; the number of first channel layers, second channel layers and third channel layers are equal and correspond one-to-one, and the first channel layer is connected to the corresponding second channel layer through the corresponding third channel layer; the number of first barrier layers, second barrier layers and third barrier layers are equal and correspond one-to-one, and the first barrier layer is connected to the corresponding second barrier layer through the corresponding third barrier layer.

[0013] In one embodiment, a second gate is further included, which is disposed on the uppermost second gallium nitride channel layer of the multilayer second gallium nitride channel layer, and the second gate is connected to the source.

[0014] In one embodiment, the second gate includes a second capping layer and a second connecting metal layer. The second capping layer is disposed on the uppermost second gallium nitride channel layer and is located between the first gate and the drain. The second connecting metal layer is disposed on the second capping layer and is connected to the source.

[0015] The beneficial effects of this application embodiment compared to the prior art are as follows: By setting the width of the fin between the first gallium nitride channel layer and the second gallium nitride channel layer to gradually decrease along the length of the fin, the application of voltage to the first gate can control the on / off state of the two-dimensional electron gas at the short side of the fin, thereby completely disconnecting the connection between the source and drain. Simultaneously, since the on-resistance at the long side of the fin is greater than that at the short side, compared to traditional fins with a consistent width, the fin of this application can control the on / off state of the entire HEMT device through the short side, and can also achieve a smaller on-resistance for the HEMT device through the long side of the fin, without increasing the manufacturing difficulty or cost. Attached Figure Description

[0016] Figure 1 A schematic diagram of the structure of a HEMT device with a finned gate provided in an embodiment of this application;

[0017] Figure 2 for Figure 1 The diagram shows the structure of the fins in the HEMT device.

[0018] Figure 3 for Figure 1 A top view of the fins in the HEMT device shown;

[0019] Figure 4 for Figure 1The diagram shows a side cross-sectional view of the fins and the first gate in the HEMT device.

[0020] Figure 5 Another schematic diagram of a HEMT device with a finned gate provided for an embodiment of this application;

[0021] Figure 6 for Figure 5 The equivalent circuit diagram of the HEMT device is shown.

[0022] The above figures illustrate the following: 100, semiconductor substrate; 200, buffer layer; 300, first gallium nitride channel layer; 310, first channel layer; 320, first barrier layer; 400, second gallium nitride channel layer; 410, second channel layer; 420, second barrier layer; 500, fin; 510, third channel layer; 520, third barrier layer; 610, drain; 620, source; 700, first gate; 710, first capping layer; 720, first interconnect metal layer; 800, second gate; 810, second capping layer; 820, second interconnect metal layer. Detailed Implementation

[0023] To make the technical problems, technical solutions, and beneficial effects to be solved by this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and are not intended to limit the scope of this application.

[0024] It should be noted that when a component is referred to as being "fixed to" or "set on" another component, it can be directly on or indirectly on that other component. When a component is referred to as being "connected to" another component, it can be directly connected to or indirectly connected to that other component.

[0025] It should be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0027] Figure 1 A schematic diagram of a HEMT device with a finned gate according to an embodiment of this application is shown. For ease of explanation, only the parts relevant to this embodiment are shown, and are described in detail below:

[0028] A HEMT device with a fin gate includes: a semiconductor substrate 100, a buffer layer 200, a multilayer first gallium nitride channel layer 300, a multilayer second gallium nitride channel layer 400, a fin 500, a first gate 700, a drain 610, and a source 620.

[0029] like Figure 1 As shown, the buffer layer 200 is disposed on the semiconductor substrate 100. Multiple first gallium nitride channel layers 300 are sequentially stacked on the buffer layer 200, and multiple second gallium nitride channel layers 400 are sequentially stacked on the buffer layer 200, corresponding one-to-one with the multiple first gallium nitride channel layers 300.

[0030] like Figure 1 , Figure 2 and Figure 3 As shown, a fin 500 is disposed on a buffer layer 200 between a first gallium nitride channel layer 300 and a second gallium nitride channel layer 400. The two ends of the fin 500 are in contact with the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400, respectively. The fin 500 contains multiple layers of two-dimensional electron gas, used to connect each first gallium nitride channel layer 300 to each second gallium nitride channel layer 400 in a one-to-one manner. A first gate 700 covers the surface of the fin 500 and is located between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400, used to control the on / off state of the two-dimensional electron gas in the fin 500. The width of the fin 500 gradually decreases along the length of the fin 500. The minimum width of the fin 500 is the short side of the fin 500, and the maximum width of the fin 500 is the long side of the fin 500. The first gate 700 is used to deplete the two-dimensional electron gas of the short side of the fin 500 when zero voltage is applied to the first gate 700.

[0031] In one embodiment, the width of the fin 500 varies linearly along the length of the fin 500.

[0032] like Figure 1 , Figure 2 and Figure 3 As shown, the drain 610 is disposed on the buffer layer 200, wherein the drain 610 and the fin 500 are respectively located on both sides of the second gallium nitride channel layer 400. The source 620 is disposed on the buffer layer 200, wherein the source 620 and the fin 500 are respectively located on both sides of the first gallium nitride channel layer 300. In one example, as... Figure 2As shown, the source 620 is in contact with the left side of each first gallium nitride channel layer 300, the fin 500 is located between the right side of the first gallium nitride channel layer 300 and the left side of the second gallium nitride channel layer 400, and the drain 610 is in contact with the right side of each second gallium nitride channel layer 400. The materials of the drain 610 and the source 620 can be ohmic metals (e.g., any one of titanium (Ti) and aluminum (Al)).

[0033] The two-dimensional electron gas at the short side of the fin 500 can be controlled by the first gate 700, thereby completely disconnecting the connection between the source 620 and the drain 610, and realizing the on / off control of the HEMT device. Even if the long side of the fin 500 cannot be completely turned off when the first gate 700 is applied with zero voltage or a small positive voltage, the HEMT device is still off due to the presence of the short side. At the same time, since the on-resistance at the long side of the fin 500 is greater than the on-resistance at the short side, the fin 500 of this application can achieve the on / off control of the entire HEMT device through the short side, and can also make the HEMT device obtain a smaller on-resistance through the long side, without increasing the difficulty of the manufacturing process or the manufacturing cost.

[0034] It should be noted that the length of the fin 500 is limited by the filling and etching processes, and has a minimum length that cannot be further reduced. Therefore, it is difficult to further reduce the on-resistance by reducing the length of the fin 500. Simultaneously, the fin 500 has a reference width, which is inversely proportional to the concentration of the two-dimensional electron gas in each layer of the fin 500. When the concentration of the two-dimensional electron gas is fixed, the reference width of the fin is also fixed. Only when the actual width of the fin 500 is less than this reference width can the two-dimensional electron gas in the portion of the fin 500 whose actual width is less than the reference width be depleted when zero voltage or a small positive voltage is applied to the first gate 700, making the HEMT device a normally closed switching device. If the actual width of the fin 500 is greater than the reference width, then the two-dimensional electron gas in the portion of the fin 500 whose actual width is greater than the reference width cannot be depleted when zero voltage or a small positive voltage is applied to the first gate 700.

[0035] In this application, the fin 500 can deplete the two-dimensional electron gas on the short side of the fin 500 when a zero voltage is applied to the first gate 700. This means the minimum width of the fin 500 is smaller than the aforementioned reference width. Since the width of the fin 500 varies linearly along its length, even if the width of a portion of the fin 500 (e.g., the long side of the fin 500) is greater than the width of the short side, and it cannot be completely turned off under zero voltage, the fin 500 and the first gate 700 can still achieve the effect of controlling the conduction and turn-off of the HEMT device. Simultaneously, since a larger fin width results in a smaller on-resistance, the overall on-resistance of the fin 500 is further reduced when the length of the fin 500 cannot be reduced.

[0036] In one embodiment, the width of the long side of the fin 500 is greater than the reference width.

[0037] In one embodiment, the width of the middle portion of the fin 500 is equal to the reference width. That is, the actual width of the fin 500 equals the reference width, and the length from the two ends of the fin 500 is equal.

[0038] like Figure 2 and Figure 3 As shown, in one embodiment, the sidewall of the first gallium nitride channel layer 300 connected to the fin 500 is parallel to the sidewall of the second gallium nitride layer connected to the fin 500, the short side and the long side are located at the two ends of the fin 500 respectively, and the cross-sectional pattern of the fin 500 is trapezoidal.

[0039] like Figure 2 and Figure 3 As shown, in one embodiment, the sidewalls on both sides of the fin 500 are perpendicular to the buffer layer 200 and are used to contact the first gate 700.

[0040] like Figure 2 and Figure 3 As shown, in one embodiment, the cross-sectional pattern of the fin 500 is an isosceles trapezoid.

[0041] like Figure 2 and Figure 3 As shown, in one embodiment, a plurality of fins 500 are provided between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400. The more fins 500 there are, the lower the on-resistance of the device and the stronger its high-voltage withstand capability. The number of fins 500 is determined by actual requirements.

[0042] like Figure 2 and Figure 3 As shown, in one example, two fins 500 are provided between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400.

[0043] like Figure 2 and Figure 3 As shown, in one embodiment, multiple fins 500 are staggered between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400, with the short side of each fin 500 and the long side of the adjacent fin 500 located on the same side. Since the on-resistance of the short side of each fin 500 is relatively high, the corresponding heat generation will also be relatively large. Therefore, the multiple fins 500 are staggered to facilitate heat dissipation and prevent heat concentration.

[0044] like Figure 2 and Figure 3 As shown, in one example, two fins 500 are provided between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400. The short side of one fin 500 is connected to the first gallium nitride channel layer 300, and the long side is connected to the second gallium nitride channel layer 400; the short side of the other fin 500 is connected to the second gallium nitride channel layer 400, and the long side is connected to the first gallium nitride channel layer 300.

[0045] like Figures 1 to 4 As shown, in one embodiment, the first gate 700 is concave. The fin 500 is located within the recess of the first gate 700, and the opening of the recess of the first gate 700 is opposite to the buffer layer 200, i.e., the opening of the recess of the first gate 700 faces downwards. At this time, the first gate 700 completely covers the surface of the fin 500.

[0046] like Figures 1 to 4 As shown, in one embodiment, the first gate 700 includes a first capping layer 710 and a first connecting metal layer 720. The first capping layer 710 covers the sidewalls on both sides of the fin 500 and contacts the two-dimensional electron gas layers within the fin 500. The first connecting metal layer 720 is disposed on the first capping layer 710 and the fin 500. The on / off state of the fin 500 can be controlled by applying a voltage to the first connecting metal layer 720. Specifically, when a positive low voltage or zero voltage is applied to the first gate 700, the first gate 700 will deplete the two-dimensional electron gas at the short side of the fin 500, and the fin 500 will be turned off; when a positive high voltage is applied to the first gate 700 and the positive high voltage is greater than the conduction threshold of the fin 500, the two-dimensional electron gas will be restored, and the fin 500 will be turned on.

[0047] In one embodiment, the first capping layer 710 is made of p-type gallium nitride (p-GaN), and the first connecting metal layer 720 is made of a Schottky metal (e.g., any one of gold (Au) or palladium (Pd)). The first connecting metal layer 720 may form a Schottky contact with the first capping layer 710.

[0048] In one embodiment, the first capping layer 710 fills all the gaps between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400 to reduce leakage current generated by the sidewalls of the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400.

[0049] In one embodiment, the drain 610 and the source 620 have equal thicknesses, and the thickness of the source 620 is greater than the sum of the thicknesses of the multilayer first gallium nitride channel layers 300, and the thickness of the source 620 is greater than the sum of the thicknesses of the multilayer second gallium nitride channel layers 400. The protruding portions of the drain 610 and the source 620 can be used for connection to external circuits.

[0050] like Figure 1 , Figure 2 As shown, in one embodiment, the first gallium nitride channel layer 300 includes a first channel layer 310 and a first barrier layer 320, with the first barrier layer 320 disposed on the first channel layer 310. When the first channel layer 310 and the first barrier layer 320 come into contact, a two-dimensional electron gas capable of transmitting electrical energy is formed.

[0051] In one example, the left sides of both the first channel layer 310 and the first barrier layer 320 are in contact with the source 620, so that the generated two-dimensional electron gas is connected to the source 620.

[0052] In one embodiment, the material of the first channel layer 310 is N-type gallium nitride (n-GaN), and the material of the first barrier layer 320 is aluminum gallium nitride (AlGaN).

[0053] In one embodiment, the thickness of the first channel layer 310 is greater than the thickness of the first barrier layer 320.

[0054] like Figure 1 , Figure 2 As shown, in one embodiment, the second gallium nitride channel layer 400 includes a second channel layer 410 and a second barrier layer 420, with the second barrier layer 420 disposed on the second channel layer 410. When the second channel layer 410 and the second barrier layer 420 come into contact, a two-dimensional electron gas capable of transmitting electrical energy is formed.

[0055] In one example, the right sides of both the second channel layer 410 and the second barrier layer 420 are in contact with the drain 610, so that the generated two-dimensional electron gas is connected to the drain 610.

[0056] In one embodiment, the material of the second channel layer 410 is N-type gallium nitride (n-GaN), and the material of the second barrier layer 420 is aluminum gallium nitride (AlGaN).

[0057] In one embodiment, the thickness of the first channel layer 310 is greater than the thickness of the first barrier layer 320.

[0058] In one embodiment, the fin 500 includes multiple third channel layers 510 and multiple third barrier layers 520, which are alternately stacked on the buffer layer 200. The number of first channel layers 310, second channel layers 410 and third channel layers 510 are equal and correspond one-to-one. The first channel layer 310 is connected to the corresponding second channel layer 410 through the corresponding third channel layer 510. The number of first barrier layers 320, second barrier layers 420 and third barrier layers 520 are equal and correspond one-to-one. The first barrier layer 320 is connected to the corresponding second barrier layer 420 through the corresponding third barrier layer 520.

[0059] In one embodiment, the material of the third channel layer 510 is N-type gallium nitride (n-GaN), and the material of the third barrier layer 520 is aluminum gallium nitride (AlGaN).

[0060] In one example, the first channel layer 310, the second channel layer 410, and the third channel layer 510 have the same thickness, and the first barrier layer 320, the second barrier layer 420, and the third barrier layer 520 have the same thickness.

[0061] It should be noted that a two-dimensional electron gas is also generated after the third channel layer 510 and the third barrier layer 520 come into contact. The two-dimensional electron gas in the fin 500 can connect with the two-dimensional electron gas in the corresponding first gallium nitride channel layer 300 and the corresponding second gallium nitride channel layer 400, thereby connecting the drain 610 and the source 620 through these two-dimensional electron gases. Therefore, the connection between the drain 610 and the source 620 can be controlled by controlling the two-dimensional electron gas in the fin 500. When the two-dimensional electron gas in the fin 500 is depleted due to the first gate 700, the drain 610 and the source 620 will be disconnected.

[0062] Meanwhile, the high voltage withstand capability and on-resistance of fin 500 largely determine the high voltage withstand capability and on-resistance of the HEMT device of this application.

[0063] In one embodiment, the length of the fin 500 is equal to the distance between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400, and the reference width of the fin 500 is negatively proportional to the thickness of the third barrier layer 520. The thickness of the third barrier layer 520 is positively proportional to the concentration of two-dimensional electron gas in the fin 500.

[0064] It should be noted that the greater the length of the fin 500 (i.e., the distance between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400), the higher the high voltage withstand capability of the fin 500, but the on-resistance of the fin 500 will also increase. The greater the width of the fin 500, the lower the leakage current and the lower the on-resistance; however, a larger fin width or a higher concentration of two-dimensional electron gas in the fin 500 makes it more difficult to deplete the two-dimensional electron gas in the fin 500 when no negative voltage is applied to the first gate 700, thus making it more difficult to turn off the fin 500. Therefore, the length and reference width of the fin 500 need to be configured according to actual requirements. In this application, the two-dimensional electron gas at the short side of the fin 500 can be completely depleted, ensuring that the HEMT device is a normally closed device.

[0065] like Figure 5 As shown, in one embodiment, a second gate 800 is also included. The second gate 800 is disposed on the uppermost second gallium nitride channel layer 400 of the multilayer second gallium nitride channel layer 400, and the second gate 800 is connected to the source 620.

[0066] The equivalent circuit diagram of the HEMT device in this application is as follows: Figure 6 As shown, by setting the fin 500 and the first gate 700, the connection between the first gallium nitride channel layer 300 and the second gallium nitride channel layer 400 can be completely cut off, allowing the source 620 and drain 610 to be completely disconnected, thus forming a switching structure similar to a normally closed HEMT device. Conversely, by connecting the second gate 800 and the multiple layers of the second gallium nitride channel layer 400, a switching structure similar to a normally open HEMT device can be constructed. By connecting the second gate 800 and the source 620, a cascode structure (CSCG) can be formed. The structure constructed by the second gate 800 and the multiple layers of the second gallium nitride channel layer 400, similar to a normally open HEMT device, can replace the fin 500 in bearing part of the high voltage. The fin 500 does not need to bear excessively high voltage; therefore, voltage division using a normally open HEMT device can increase the overall high voltage withstand capability of the HEMT device while maintaining the low on-resistance of the fin 500.

[0067] It should be noted that the second gate 800 can control the on / off state of the two-dimensional electron gas in the uppermost second gallium nitride channel layer 400. The second gate 800 and the uppermost second gallium nitride channel layer 400 can form a structure approximating a normally closed HEMT device. When a low voltage or zero voltage is applied to the second gate 800, the two-dimensional electron gas in the uppermost second gallium nitride channel layer 400 (located directly below the second gate 800) will disappear, but the two-dimensional electron gas in the other second gallium nitride channel layers 400 will remain conductive. When a positive high voltage is applied to the second gate 800 and the positive high voltage is greater than the conduction threshold of the normally closed HEMT device, the two-dimensional electron gas in the uppermost second gallium nitride channel layer 400 will remain conductive.

[0068] In one embodiment, the distance from the first gate 700 to the drain 610 is greater than the distance from the first gate 700 to the source 620.

[0069] In one embodiment, the distance from the second gate 800 to the drain 610 is equal to the distance from the second gate 800 to the first gate 700.

[0070] like Figure 5 As shown, in one embodiment, the second gate 800 includes a second capping layer 810 and a second connection metal layer 820. The second capping layer 810 is disposed on the uppermost second gallium nitride channel layer 400 and is located between the first gate 700 and the drain 610. The second connection metal layer 820 is disposed on the second capping layer 810 and is connected to the source 620.

[0071] In one embodiment, the material of the second capping layer 810 is P-type gallium nitride, the material of the second connecting metal layer 820 is Schottky metal, and the second connecting metal layer 820 can form a Schottky contact with the second capping layer 810.

[0072] Since the second gallium nitride channel layer 400 is always on, the actual second gate 800 and the multiple layers of second gallium nitride channel layers 400 can form a structure approximating a normally-on HEMT device. Only when a reverse high voltage is applied to the second gate 800 and the reverse high voltage is greater than a certain turn-off threshold will all the second gallium nitride channel layers 400 be turned off.

[0073] It should be noted that, in any of the above embodiments, when a forward high voltage is applied to the source 620 and drain 610 of the multilayer gallium nitride HEMT device (drain 610 is at a high potential, source 620 is at a low potential), when a forward low voltage or zero voltage is applied to the first gate 700, the normally closed HEMT device constructed with the first gate 700 is turned off, and the source 620 and drain 610 are disconnected; when a forward high voltage is applied to the first gate 700 and the forward high voltage is greater than the conduction threshold of the normally closed HEMT device constructed with the first gate 700, the normally closed HEMT device constructed with the first gate 700 is turned on. However, even if the uppermost second gallium nitride channel layer 400 is turned off due to the second gate 800 receiving a low voltage, the other second gallium nitride channel layers 400 will still be turned on, and the source 620 and drain 610 will be connected. The first gate 700 and the fin 500 are used to control the turn-on and turn-off of the device.

[0074] When the normally closed HEMT device constructed with the first gate 700 is turned off, if a forward high voltage is still applied to the source 620 and drain 610 (for example, in an inductor circuit, the source 620 and drain 610 will experience a high voltage at the moment the HEMT device is turned off), the second gate 800 will be subjected to a high reverse high voltage due to its connection with the source 620. If this reverse high voltage is lower than the turn-off threshold of the normally open HEMT device constructed with the second gate 800, the normally open HEMT device will be turned on. At this time, the normally closed HEMT device constructed with the first gate 700 will bear all the reverse voltage (specifically, the fin 500 will bear the voltage). However, the voltage is small at this time and is still within the range that the normally closed HEMT device can withstand. If the reverse high voltage exceeds the turn-off threshold of the normally open HEMT device constructed with the second gate 800, the normally open HEMT device turns off. At this time, the normally closed HEMT device and the normally open HEMT device jointly bear the reverse high voltage, with the normally open HEMT device bearing most of the voltage and the normally closed HEMT device bearing a smaller voltage. Therefore, the multilayer gallium nitride HEMT device has both high high voltage withstand performance and low on-resistance.

[0075] In the above embodiments, the descriptions of each embodiment have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0076] The above-described embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included within the protection scope of this application.

Claims

1. A HEMT device with fin-gate, characterized in that, include: A semiconductor substrate and a buffer layer disposed on the semiconductor substrate; Multiple first gallium nitride channel layers are sequentially stacked on the buffer layer; Multiple layers of second gallium nitride channel layers are sequentially stacked on the buffer layer, and each layer corresponds to a different layer of first gallium nitride channel layers. Fins are disposed on the buffer layer between the first gallium nitride channel layer and the second gallium nitride channel layer. The two ends of the fins are in contact with the first gallium nitride channel layer and the second gallium nitride channel layer, respectively, for connecting each first gallium nitride channel layer and each second gallium nitride channel layer one-to-one. A first gate, covering the surface of the fin and located between the first gallium nitride channel layer and the second gallium nitride channel layer, is used to control the on / off state of the two-dimensional electron gas in the fin; The width of the fin gradually decreases along the length of the fin, and the first gate is used to deplete the two-dimensional electron gas on the short side of the fin when zero voltage is applied to the first gate. A drain is disposed on the buffer layer; wherein the drain and the fin are respectively located on both sides of the second gallium nitride channel layer; The source electrode is disposed on the buffer layer; wherein the source electrode and the fin are respectively located on both sides of the first gallium nitride channel layer; A plurality of fins are provided between the first gallium nitride channel layer and the second gallium nitride channel layer; Multiple fins are staggered between the first gallium nitride channel layer and the second gallium nitride channel layer, with the short side of each fin and the long side of the adjacent fin located on the same side.

2. The HEMT device of claim 1, wherein, The sidewall of the first gallium nitride channel layer connected to the fin is parallel to the sidewall of the second gallium nitride layer connected to the fin. The short side and the long side of the fin are located at the two ends of the fin, respectively. The cross-sectional pattern of the fin is trapezoidal.

3. The HEMT device of claim 2, wherein, The cross-sectional pattern of the fin is an isosceles trapezoid.

4. The HEMT device of claim 1, wherein, The first gate includes a first capping layer and a first interconnect metal layer; The first capping layer covers the sidewalls on both sides of the fin and is in contact with each layer of two-dimensional electron gas within the fin; The first connecting metal layer is disposed on the first cap layer and the fin.

5. The HEMT device of claim 1, wherein, The first gallium nitride channel layer includes a first channel layer and a first barrier layer, wherein the first barrier layer is disposed on the first channel layer; The second gallium nitride channel layer includes a second channel layer and a second barrier layer, wherein the second barrier layer is disposed on the second channel layer.

6. The HEMT device of claim 5, wherein, The fin includes multiple third channel layers and multiple third barrier layers, wherein the third barrier layers and the third channel layers are alternately stacked on the buffer layer. The number of the first channel layer, the second channel layer, and the third channel layer are equal and correspond one-to-one. The first channel layer is connected to the corresponding second channel layer through the corresponding third channel layer. The number of the first barrier layer, the second barrier layer, and the third barrier layer are equal and correspond one-to-one. The first barrier layer is connected to the corresponding second barrier layer through the corresponding third barrier layer.

7. The HEMT device of claim 1, wherein, A second gate is arranged on the uppermost second gallium nitride channel layer of the plurality of second gallium nitride channel layers, and the second gate is connected to the source electrode.

8. The HEMT device of claim 7, wherein, The second gate comprises a second cap layer and a second connecting metal layer, The second cap layer is arranged on the uppermost second gallium nitride channel layer and between the first gate and the drain electrode, and the second connecting metal layer is arranged on the second cap layer and connected to the source electrode.

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