Gallium nitride-based HEMT device and manufacturing method thereof
By doping the nucleation layer of the GaN HEMT device to make it n-type and passivating defects in the nitride epitaxial layer, the problem of current collapse effect in the device is solved, high-frequency performance and applicability are improved, and the Effective suppression of current collapse effect.
Patent Information
- Application Number
- CN202411242517.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-05
- Publication Date
- 2024-12-13
AI Technical Summary
GaN HEMT devices are defective due to differences in the lattice constant and thermal expansion coefficient between the heterogeneous substrate and the nitride material layer, resulting in a current collapse effect, affecting the dynamic characteristics of the device and high-frequency application performance.
By doping on the nucleation layer, it is n-type and passivating defects in the nitride epitaxial layer, avoiding defects from trapping or emitting electrons, thereby suppressing the current collapse effect.
It effectively suppresses the current collapse effect, improves the high-frequency response performance and applicability of the device, has a simple process, no new equipment or structure is required, and improves the overall performance of the device.
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Figure CN119132953A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of integrated circuit devices and manufacturing, and relates to a gallium nitride-based HEMT device and a manufacturing method thereof. Background Art
[0002] GaN HEMT devices can achieve smaller on-resistance and gate charge due to their material advantages, such as high power density, high bandwidth, high electron mobility, high saturation electron velocity and breakdown electric field, and are very suitable for high-power and high-frequency applications (such as high-frequency communications and radar systems), or to improve the efficiency and power density of converters.
[0003] GaN HEMT devices usually include a nitride material layer epitaxially grown on a foreign substrate. Due to the obvious difference in lattice constant and thermal expansion coefficient between the foreign substrate and the nitride material layer, a large number of defects (such as dislocations, vacancies, impurities, etc.) are generated in the epitaxial material layer, which affects the quality of the material layer. These defects are distributed on the surface and inside of the nitride material layer, and will capture or emit electrons when the HEMT device is working. The speed of this process is much slower than the switching speed of the device, causing the source-drain current response of the device to deviate from the ideal situation (the so-called current collapse effect). Among the many phenomena caused by the current collapse effect, IDQ drop will seriously affect the changes in the dynamic characteristics of the device, thereby restricting the application of the device in technical fields such as base stations. For details, please refer to Figures 1 to 3 ,in, Figure 1 The graph shows the variation of the applied RF current over time when a conventional HEMT device is working. Figure 2 Displayed as based on Figure 1 The output current variation data collected when the HEMT device is working is shown in the figure. Figure 3 Display as Figure 2 Schematic diagram of the enlarged local area (corresponding to Figure 1 IDQ drop refers to the phenomenon that when an RF signal is applied to a HEMT RF device for a period of time and then turned off, the source-drain current of the device will drop sharply below the bias current immediately after the RF signal is turned off, and then gradually recover to the bias current in a very short time (usually at the ms level). That is, IDQ drop is a manifestation of the current collapse effect. Of course, the same current collapse effect also exists in HEMT power devices, which has a deteriorating effect on the working performance.
[0004] Therefore, how to provide a gallium nitride-based HEMT device and a method for manufacturing the same to improve the current collapse effect and thus enhance the working performance of the HEMT device has become an important technical problem that needs to be solved urgently by those skilled in the art.
[0005] It should be noted that the above introduction to the technical background is only for the convenience of providing a clear and complete description of the technical solutions of the present application and for the convenience of understanding by those skilled in the art. It cannot be considered that the above technical solutions are well known to those skilled in the art simply because they are described in the background technology section of the present application. Summary of the invention
[0006] In view of the above-mentioned shortcomings of the prior art, an object of the present invention is to provide a gallium nitride-based HEMT device and a method for manufacturing the same, so as to solve the problem in the prior art that the current collapse effect occurs when the HEMT device is working and affects its working performance.
[0007] To achieve the above-mentioned object and other related objects, the present invention provides a method for manufacturing a gallium nitride-based HEMT device, comprising the following steps:
[0008] providing a substrate;
[0009] forming a nucleation layer on the substrate and doping the nucleation layer to make the nucleation layer n-type;
[0010] A nitride epitaxial layer is grown on the nucleation layer. The nitride epitaxial layer contains defects that capture emitted electrons. The nucleation layer is doped to raise the Fermi level so as to passivate the defects and make them lose the ability to capture emitted electrons.
[0011] Optionally, the effective n-type doping concentration range of the nucleation layer is 3E17-1E18 cm -3 , the element doped into the nucleation layer includes at least one of Si, Te and Sn, or the element doped into the nucleation layer includes at least one of Si, Te and Sn and a p-type element.
[0012] Optionally, the growth of the nucleation layer and the doping are performed simultaneously.
[0013] Optionally, the material of the substrate includes at least one of silicon carbide, sapphire and diamond; the material of the nucleation layer includes aluminum nitride, the growth temperature range of the nucleation layer is 1100-1300°C, the growth pressure range of the nucleation layer is 50-100mbar, and the thickness range of the nucleation layer is 10-100nm.
[0014] Optionally, the nitride epitaxial layer includes a channel layer, the material of the channel layer includes GaN, the growth temperature range of the channel layer is 1000-1050° C., the growth pressure range of the channel layer is 200-400 mbar, and the thickness range of the channel layer is 300-1200 nm.
[0015] Optionally, the nitride epitaxial layer further includes a buffer layer located below the channel layer, and the buffer layer is doped with Fe element, and the material of the buffer layer is Al x Ga 1-x N, 0≤x≤0.1, the growth temperature range of the buffer layer is 900~1100℃, the growth pressure range of the buffer layer is 200~400mbar, the thickness range of the buffer layer is 200~600nm, and the doping concentration range of the Fe element is 5E15~1E19 cm -3 .
[0016] Optionally, the nitride epitaxial layer also includes a barrier layer located above the channel layer, the barrier layer and the channel layer form a heterojunction, the barrier layer includes at least one of a single-layer structure and a stacked structure, the growth temperature range of the barrier layer is 1050-1150°C, the growth pressure range of the barrier layer is 100-200 mbar, and the thickness range of the barrier layer is 10-30 nm.
[0017] Optionally, when the barrier layer is a stacked structure, the barrier layer includes at least one of AlN / Al(In)GaN / GaN, Al(In)N / GaN, Al(In)GaN / GaN, AlN / Al(In)GaN, AlN / AlScN / GaN, Al(In)N / GaN, AlScN / GaN, AlN / AlScN, AlN / Al(In)GaN / SiN, Al(In)N / SiN, Al(In)GaN / SiN, AlN / Al(In)GaN, AlN / AlScN / SiN, Al(In)N / SiN, AlScN / SiN and AlN / AlScN, wherein the thickness range of the AlN layer is 0 to 4 nm, the thickness range of the Al(In)GaN layer or the AlScN layer is 10 to 30 nm, and the thickness range of the GaN layer is 0 to 5 nm.
[0018] Optionally, the gallium nitride-based HEMT device includes at least one of a radio frequency device and a power device.
[0019] The present invention also provides a gallium nitride-based HEMT device, which comprises a substrate, a nucleation layer and a nitride epitaxial layer arranged in sequence from bottom to top, wherein the nucleation layer is n-type by doping, and the nitride epitaxial layer has defects that capture emitted electrons, and the defects are passivated by doping the nucleation layer to raise the Fermi level, so that the defects lose the ability to capture emitted electrons.
[0020] As described above, the method for manufacturing the gallium nitride-based HEMT device of the present invention performs doping during the growth of the nucleation layer to make the nucleation layer n-type, and uses the doping elements introduced into the device structure to raise the Fermi level to passivate the defects in the nitride epitaxial layer, so as to prevent the defects from capturing and emitting electrons during the operation of the device and thereby causing or aggravating the current collapse effect (IDQ drop), thereby greatly suppressing the current collapse effect, improving the high-frequency response performance of the device, and expanding the high-frequency applicability of the device. In addition, the overall process steps are simple and easy to implement, and the current collapse effect can be effectively improved without the need for new processes, structures or equipment. In addition, the device performance can be further improved by omitting the buffer layer and optimizing the process or structure such as the ultra-thin AlN layer. The gallium nitride-based HEMT device of the present invention has an n-type nucleation layer, and the defects in the nitride epitaxial layer are passivated by introducing doping elements to prevent the defects from participating in the capture or emission of electrons during the operation of the device, thereby greatly suppressing or avoiding the occurrence of the current collapse effect (for example, IDQ drop), and will not significantly deteriorate other working performances of the device, and is suitable for large-scale promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Figure 1 The graph shows the time variation of the applied RF current when a conventional HEMT device is operating.
[0022] Figure 2 Displayed as based on Figure 1 The data of output DC current variation over time collected when a conventional HEMT device is working.
[0023] Figure 3 Display as Figure 2 Schematic diagram of the enlarged local area.
[0024] Figure 4 The flowchart is a method for manufacturing a gallium nitride-based HEMT device according to the present invention.
[0025] Figure 5 It is a schematic diagram of a local cross-section of a device manufactured in Example 1 according to the manufacturing method of the gallium nitride-based HEMT device of the present invention.
[0026] Figure 6 It is a schematic diagram showing the energy band distribution of the device obtained when the nucleation layer is not doped in the conventional manufacturing method.
[0027] Figure 7 It is a schematic diagram showing the energy band distribution of the device obtained when the nucleation layer is doped using the method for manufacturing the gallium nitride-based HEMT device of the present invention.
[0028] Figure 8 It is a schematic diagram of a local cross-section of a device manufactured in Example 2 according to the manufacturing method of the gallium nitride-based HEMT device of the present invention.
[0029] Description of Reference Numerals
[0030] 10 Substrate
[0031] 20 Nucleation layer
[0032] 30 Nitride Epitaxial Layer
[0033] 31 Channel layer
[0034] 32 Buffer layer
[0035] 33 Barrier layer
[0036] Steps S1 to S3 DETAILED DESCRIPTION
[0037] The following describes the embodiments of the present invention through specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention.
[0038] See also Figures 4 to 8 It should be noted that the illustrations provided in this embodiment are only used to illustrate the basic concept of the present invention in a schematic manner, and the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.
[0039] Embodiment 1
[0040] This embodiment provides a method for manufacturing a gallium nitride-based HEMT device. Figure 4 , which is a flowchart of the steps of the production method, comprising the following steps:
[0041] S1: providing a substrate;
[0042] S2: forming a nucleation layer on the substrate, and doping the nucleation layer to make the nucleation layer n-type;
[0043] S3: growing a nitride epitaxial layer on the nucleation layer, wherein the nitride epitaxial layer contains defects that capture emitted electrons, and passivating the defects by doping the nucleation layer to raise the Fermi level, thereby making the defects lose the ability to capture emitted electrons.
[0044] First, please refer to 5 , step S1 is performed to provide a substrate 10 .
[0045] As an example, the material of the substrate 10 includes at least one of silicon carbide, sapphire and diamond, and in this embodiment, it is a silicon carbide substrate. In this embodiment, the substrate is a semi-insulating SiC substrate, and the substrate is placed in a metal organic chemical vapor deposition (MOCVD) chamber for subsequent steps, and before performing the subsequent steps, the temperature inside the chamber is first raised to 1050°C and thermal cleaning is performed in a hydrogen atmosphere for about 10 minutes. The thermal cleaning step is used to eliminate the oxide layer and impurities on the surface of the SiC substrate, and at the same time, the substrate surface is activated to provide a clean and active surface condition for the subsequent growth of the nucleation layer, promote the growth of the nucleation layer and improve its growth quality.
[0046] It should be noted that the substrate in this embodiment cannot be a silicon substrate. If a silicon substrate is used as the base of the subsequent structural layers, when a nucleation layer is formed on the silicon substrate, an additional current flow path (i.e., an additional channel) is introduced at the interface between the two due to the problem of mutual diffusion, and the insulation of the silicon substrate may not be as good as the nucleation layer, thereby affecting the insulation performance of the device. The above reasons cause serious RF loss or leakage problems when the nucleation layer is subsequently grown and doped, and the effect of element doping on improving device performance is lost.
[0047] Then, if Figure 5 As shown, step S2 is performed to form a nucleation layer 20 on the substrate 10, and the nucleation layer 20 is doped to make the nucleation layer 20 n-type. To avoid ambiguity, "the nucleation layer is n-type" means that the majority carriers in the nucleation layer are free electrons.
[0048] As an example, the growth and doping of the nucleation layer 20 are carried out simultaneously, that is, when the substrate 10 is placed in a semiconductor chamber to form the nucleation layer 20, a gas source for growing the nucleation layer 20 and a doping source of doping elements (for example, silane) are introduced into the semiconductor chamber together to perform doping during the growth of the nucleation layer 20, thereby improving doping uniformity and doping efficiency.
[0049] As an example, the effective n-type doping concentration range of the nucleation layer is 3E17-1E18 cm -3 , including but not limited to 4E17cm -3 、6E17 cm -3 and 8E17 cm -3 In practical applications, the effective n-type doping concentration can be selected within the above range based on actual needs. Exceeding the above range will easily cause lateral leakage due to high doping or the improvement effect on the current collapse effect will not be obvious. The "effective n-type doping concentration range" refers to the concentration range that can actually contribute free electrons after doping the nucleation layer.
[0050] In one example, the element doped into the nucleation layer includes at least one of Si, Te and Sn, that is, only n-type doping elements are doped into the nucleation layer.
[0051] In another example, the element doped into the nucleation layer includes at least one of Si, Te and Sn and a p-type element, that is, the n-type doping element and the p-type doping element are doped into the nucleation layer at the same time, but the main charge carriers in the nucleation layer after doping are still free electrons to ensure that the nucleation layer is n-type as a whole after doping. Of course, other suitable elements can also be used to dope the nucleation layer, not limited to the above elements.
[0052] As an example, the material of the nucleation layer 20 includes aluminum nitride (AlN); the growth temperature range of the nucleation layer 20 is 1100-1300°C, including but not limited to 1150°C, 1200°C and 1250°C; the growth pressure range of the nucleation layer 20 is 50-100mbar, including but not limited to 60mbar, 70mbar and 80mbar; the thickness range of the nucleation layer 20 is 10-100nm, including but not limited to 25nm, 50nm and 75nm. In this embodiment, after the substrate surface is thermally cleaned, the chamber temperature is raised to 1200°C to grow a 40nm thick AlN layer as the nucleation layer 20, and Si element doping is performed during the growth process of the nucleation layer 20, and the doping concentration is 1E18 cm -3 .
[0053] In a specific example, the nucleation layer 20 is an ultra-thin AlN layer, the thickness of the ultra-thin AlN layer is less than 40nm, while the thickness of a conventional AlN nucleation layer is between 40 and 100nm. The ultra-thin AlN layer has a smaller thermal resistance, which helps the device to better dissipate heat through the substrate, improves device reliability, and can also suppress the current collapse effect to a certain extent (high device temperature will aggravate the degree of current collapse effect), thereby improving device performance.
[0054] Next, if Figure 5 As shown, step S3 is performed to grow a nitride epitaxial layer 30 on the nucleation layer 20, wherein the nitride epitaxial layer 30 contains defects ( Figure 5 The nucleation layer 20 is doped to raise the Fermi level and passivate the defects, which make the defects lose the ability to capture emitted electrons. The defects include but are not limited to impurities, vacancies and dislocations. In fact, since the nucleation layer is grown on a heterogeneous substrate, the nucleation layer itself also has a certain number of growth defects. To avoid ambiguity, "passivation" here refers to the process of filling the energy level of the defect with electrons and being in a passivated state, which can no longer capture emitted electrons.
[0055] For details, please refer to Figure 6 and Figure 7 ,in, Figure 6 This is a schematic diagram showing the energy band distribution of the device obtained when the nucleation layer is not doped in the conventional manufacturing method. Figure 7 The figure shows the energy band distribution of the device obtained when the nucleation layer is doped in this embodiment. Since the band gap of the nucleation layer is very high, electrons need more energy to jump from the valence band to the conduction band, and the semi-insulating property of the substrate means that the substrate does not provide enough free paths, which further limits the possibility of electrons jumping to the conduction band. Therefore, the Fermi level will be located far below the conduction band (such as Figure 6 As shown in Figure 2, defects (such as impurities, dislocations, and vacancies) in the nitride epitaxial layer (or even the nucleation layer) will introduce additional energy levels ( Figure 6 and Figure 7 The defect energy level shown by the short and medium line segments) is in the energy band structure of the corresponding structural layer, and the corresponding energy level is above the Fermi level and is not occupied by electrons. At this time, the defect energy level is in an activated state and will participate in the capture or emission of electrons during the operation of the HEMT device. In this embodiment, after the nucleation layer is doped, the nucleation layer as a whole tends to be n-type, which is equivalent to introducing additional electron donors in the nucleation layer to provide additional electrons, such as Figure 7 As shown, the Fermi level will rise until it is higher than the defect energy level of the defect, and the energy levels of these defects are filled with electrons (based on the passivation of the defects in the nitride epitaxial layer by element doping). At this time, the energy level of the defect is in an unactivated passivated state and no longer participates in the capture or emission of electrons during the subsequent device operation. In short, in this embodiment, the position of the Fermi level is adjusted by doping the nucleation layer so that it is higher than the energy level of the defect, thereby passivating the growth defect, reducing or avoiding the defect from participating in electron capture or emission during the device operation, greatly suppressing the current collapse effect (IDQ drop phenomenon), and thus improving the device performance.
[0056] As an example, the nitride epitaxial layer 30 includes a channel layer 31, and the material of the channel layer 31 includes GaN; the growth temperature range of the channel layer 31 is 1000-1050°C, including but not limited to 1020°C and 1040°C; the growth pressure range of the channel layer 31 is 200-400mbar, including but not limited to 250mbar, 300mbar and 350mbar; the thickness range of the channel layer 31 is 300-1200nm, including but not limited to 500nm, 800nm and 1000nm.
[0057] As an example, the nitride epitaxial layer 30 further includes a buffer layer 32 located below the channel layer 31, and the buffer layer 32 is doped with Fe elements. The material of the buffer layer 32 includes Alx Ga 1-x N, 0≤x≤0.1; the growth temperature range of the buffer layer 32 is 900~1100℃, including but not limited to 950℃, 1000℃ and 1050℃; the growth pressure range of the buffer layer 32 is 200~400mbar, including but not limited to 250mbar, 300mbar and 350mbar; the thickness range of the buffer layer 32 is 200~600nm, including but not limited to 300nm, 400nm and 500nm, and the doping concentration range of the Fe element is 5E15~1E19 cm -3 , including but not limited to 1E16 cm -3 、1E17 cm -3 、1E18 cm -3 Since the undoped buffer layer usually has a lower resistivity, which may lead to increased leakage and lower breakdown voltage of the device, doping the buffer layer with Fe can reduce the occurrence of device leakage problems to improve device performance and reliability, while also improving the voltage tolerance of the device.
[0058] As an example, the nitride epitaxial layer 30 also includes a barrier layer 33 located above the channel layer 31, the barrier layer 33 and the channel layer 31 form a heterojunction, the barrier layer 33 includes at least one of a single-layer structure and a stacked structure, the growth temperature range of the barrier layer 33 is 1050-1150°C, including but not limited to 1080°C, 1100°C and 1125°C; the growth pressure range of the barrier layer 33 is 100-200mbar, including but not limited to 125mbar, 150mbar and 175mbar; the thickness range of the barrier layer 33 is 10-30nm, including but not limited to 15nm, 20nm and 25nm. When the nitride epitaxial layer 30 includes a buffer layer 32, a channel layer 31 and a barrier layer 33 at the same time, the above three structural layers are epitaxially grown in sequence, wherein the channel layer 31 is formed by unintentional doping, which will introduce uncontrollable impurities of type and concentration during the growth process, further increasing the defects in the nitride epitaxial layer 30, and increasing the occurrence of the current collapse phenomenon to a certain extent. That is, during the growth of the nitride epitaxial layer 30 of the present embodiment, it is not necessary to deliberately control the growth environment in the cavity to be good to avoid unintentional doping. Even if the impurities introduced into the nitride epitaxial layer 30 due to unintentional doping have an auxiliary effect on the current collapse effect, it can be eliminated later through the n-type doping of the nucleation layer 20, reducing the difficulty of process control.
[0059] As an example, when the barrier layer 33 is a stacked structure, the barrier layer 33 includes AlN / Al(In)GaN / GaN, Al(In)N / GaN, Al(In)GaN / GaN, AlN / Al(In)GaN, AlN / AlScN / GaN, Al(In)N / GaN, AlScN / GaN, AlN / Al(In)GaN / SiN, Al(In)N / SiN, Al(In)GaN / SiN, AlN / Al At least one of (In)GaN, AlN / AlScN / SiN, Al(In)N / SiN, AlScN / SiN and AlN / AlScN, wherein the thickness of the AlN layer ranges from 0 to 4 nm, including but not limited to 1 nm, 2 nm and 3 nm; the thickness of the Al(In)GaN layer or the AlScN layer ranges from 10 to 30 nm, including but not limited to 15 nm, 20 nm and 25 nm, and the thickness of the GaN layer ranges from 0 to 5 nm, including but not limited to 1 nm, 2 nm and 3 nm. Taking the barrier layer as AlN / Al(In)GaN / GaN as an example, that is, the barrier layer is composed of an AlN layer, an Al(In)GaN layer and a GaN layer stacked in sequence to form a three-layer stacked structure, and the Al(In)GaN layer refers to the general term for aluminum gallium nitride (AlGaN) and aluminum indium gallium nitride (AlInGaN), and can be an AlGaN layer or an AlInGaN layer.
[0060] In this embodiment, after growing the AlN nucleation layer, the chamber temperature is lowered to 1050°C to grow a 400nm AlGaN buffer layer, and the AlGaN buffer layer has a doping concentration of 5E18 cm -3 Fe element; then, the chamber pressure is increased to 300mbar and a 600nm unintentionally doped GaN channel layer is grown; the temperature is then raised to 1070°C and a stacked AlN / AlGaN / GaN barrier layer is grown, and finally, the above structure is placed in an ammonia protective atmosphere for cooling treatment to complete the nitride epitaxial layer growth.
[0061] As an example, the gallium nitride-based HEMT device includes at least one of a radio frequency device and a power device. Although the current collapse phenomenon exists in the operation process of the above two devices, the operating frequencies of the power device and the radio frequency device are not in the same order of magnitude. Compared with the radio frequency device, the power device is relatively less sensitive to IDQ drop. Therefore, the gallium nitride-based HEMT device of this embodiment is particularly suitable as a radio frequency device. Compared with the traditional HEMT radio frequency device, the current collapse effect of the device during operation, especially the IDQ drop, can be greatly suppressed, and the high-frequency effect performance of the device is significantly improved.
[0062] The manufacturing method of the gallium nitride-based HEMT device of this embodiment performs doping during the growth of the nucleation layer, and utilizes the doping elements introduced into the device structure to make the nucleation layer n-type to raise the Fermi level, thereby passivating the defects in the nitride epitaxial layer, making the defects lose the ability to capture emitted electrons, and preventing the defects from capturing emitted electrons during the operation of the device and causing or aggravating the current collapse effect (IDQ drop), thereby greatly suppressing the current collapse effect, improving the high-frequency response performance of the device, and expanding the high-frequency applicability of the device. In addition, the overall process steps are simple and easy to implement, and the current collapse effect can be effectively improved without the need for new processes, structures or equipment.
[0063] Embodiment 2
[0064] This embodiment provides a method for manufacturing a gallium nitride-based HEMT device. The difference between this embodiment and the manufacturing method in the first embodiment is that the nitride epitaxial layer in this embodiment does not include a buffer layer (that is, the nitride epitaxial layer only includes a channel layer and a barrier layer, and the step of growing the buffer layer is reduced in the manufacturing steps), while the nitride epitaxial layer in the first embodiment includes a buffer layer. Figure 4 , which is a flowchart of the steps of the production method, comprising the following steps:
[0065] S1: providing a substrate;
[0066] S2: forming a nucleation layer on the substrate, and doping the nucleation layer to make the nucleation layer n-type;
[0067] S3: growing a nitride epitaxial layer on the nucleation layer, wherein the nitride epitaxial layer contains defects that capture emitted electrons, and passivating the defects by doping the nucleation layer to raise the Fermi level, thereby making the defects lose the ability to capture emitted electrons.
[0068] As an example, see Figure 8 , performing the above steps S1 to S3 in sequence, wherein growing the nitride epitaxial layer 30 on the nucleation layer 20 includes the following steps: sequentially growing a channel layer 31 and a barrier layer 33 on the nucleation layer 20 to form a heterojunction structure.
[0069] Furthermore, in this embodiment, after growing the AlN nucleation layer, the chamber pressure is increased to 300 mbar to grow a GaN channel layer that is not intentionally doped with 300 nm; then the temperature is increased to 1070°C, and a stacked AlN / AlGaN / GaN barrier layer is grown, and finally the above structure is placed in an ammonia protective atmosphere for cooling treatment to complete the growth of the nitride epitaxial layer.
[0070] Specifically, in this embodiment, since the nitride epitaxial layer does not include a buffer layer (i.e., buffer free), that is, a channel layer is directly formed above the nucleation layer, and since there is no need to introduce Fe doping in the device structure, the IDQ drop caused by impurities in the growth defects can be further reduced, thereby improving the device performance. However, in the traditional sense, the buffer layer can improve the crystal quality and crystal defects based on its growth. The reduction of the buffer layer will directly deteriorate the quality of the channel layer thereon. Based on this, it is necessary to strictly control the growth process of the nucleation layer to compensate for the indirect adverse effects caused by not forming the buffer layer by improving the growth quality of the nucleation layer, thereby ensuring that the device performance will not be affected by the lack of the buffer layer.
[0071] Compared with the manufacturing method of the first embodiment, the manufacturing method of the gallium nitride-based HEMT device of the present embodiment omits the step of growing the buffer layer, thereby avoiding the introduction of Fe impurity elements into the device, and further improving the device performance.
[0072] Embodiment 3
[0073] This embodiment provides a gallium nitride-based HEMT device, which is manufactured by the method of the first or second embodiment. Figure 5 and Figure 8 , showing two partial cross-sectional schematic diagrams of the GaN and HEMT devices.
[0074] Specifically, the gallium nitride-based HEMT device includes a substrate 10, a nucleation layer 20 and a nitride epitaxial layer 30 arranged in sequence from bottom to top, wherein the nucleation layer 20 is n-type by doping, and the nitride epitaxial layer 30 contains defects that capture and emit electrons, and the defects are passivated by doping the nucleation layer to a too high Fermi level so that the defects lose the ability to capture electrons.
[0075] In one example, the nitride epitaxial layer 30 includes a channel layer 31 and a barrier layer 33 stacked from bottom to top. Figure 8 As shown; in another example, the nitride epitaxial layer 30 includes a buffer layer 32, a channel layer 31 and a barrier layer 33 stacked sequentially from bottom to top, as shown Figure 5 The main difference between the two exemplary structures is the presence or absence of the buffer layer 32, which is selected based on needs and application scenarios in actual applications.
[0076] The gallium nitride-based HEMT device of this embodiment has an n-type nucleation layer. By introducing doping elements to passivate defects in the nitride epitaxial layer, defects are prevented from capturing emitted electrons when the device is working, thereby greatly suppressing or avoiding the occurrence of current collapse effect (for example, IDQ drop), and other working performances of the device (for example, power density, leakage and reliability, etc.) will not be significantly degraded, and is suitable for large-scale promotion and application.
[0077] In summary, the method for manufacturing a gallium nitride-based HEMT device of the present invention performs doping during the growth of the nucleation layer to make the nucleation layer n-type, and uses the doping elements introduced into the device structure to passivate the growth defects in the nitride epitaxial layer, so as to prevent the defects from capturing the emitted electrons during the operation of the device and thus causing or aggravating the current collapse effect (IDQdrop), thereby greatly suppressing the current collapse effect, improving the high-frequency response performance of the device, and expanding the high-frequency applicability of the device. In addition, the overall process steps are simple and easy to implement, and the current collapse effect can be effectively improved without new processes, structures or equipment. In addition, the device performance can be further improved by omitting the buffer layer and optimizing the process or structure such as the ultra-thin AlN layer. The gallium nitride-based HEMT device of this embodiment has an n-type nucleation layer, and the growth defects in the nitride epitaxial layer are passivated by the introduction of doping elements, so as to prevent the growth defects from capturing the emitted electrons during the operation of the device, thereby greatly suppressing or avoiding the occurrence of the current collapse effect (for example, IDQ drop), and will not significantly deteriorate other working performances of the device, and is suitable for large-scale promotion and application. Therefore, the present invention effectively overcomes various shortcomings in the prior art and has high industrial utilization value.
[0078] The above embodiments are merely illustrative of the principles and effects of the present invention, and are not intended to limit the present invention. Anyone familiar with the art may modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by a person of ordinary skill in the art without departing from the spirit and technical concept disclosed by the present invention shall still be covered by the claims of the present invention.
Claims
1. A method for manufacturing a gallium nitride-based HEMT device, characterized in that: The following steps are involved: providing a substrate; forming a nucleation layer on the substrate and doping the nucleation layer to make the nucleation layer n-type; A nitride epitaxial layer is grown on the nucleation layer. The nitride epitaxial layer contains defects that capture emitted electrons. The nucleation layer is doped to raise the Fermi level so as to passivate the defects and make them lose the ability to capture emitted electrons.
2. The method for manufacturing a gallium nitride-based HEMT device according to claim 1, characterized in that: The effective n-type doping concentration range of the nucleation layer is 3E17-1E18 cm -3 , the element doped into the nucleation layer includes at least one of Si, Te and Sn, or the element doped into the nucleation layer includes at least one of Si, Te and Sn and a p-type element.
3. The method for manufacturing a gallium nitride-based HEMT device according to claim 1, characterized in that: The growth of the nucleation layer and the doping are performed simultaneously.
4. The method for manufacturing a gallium nitride-based HEMT device according to claim 1, characterized in that: The material of the substrate includes at least one of silicon carbide, sapphire and diamond; the material of the nucleation layer includes aluminum nitride, the growth temperature range of the nucleation layer is 1100-1300°C, the growth pressure range of the nucleation layer is 50-100mbar, and the thickness range of the nucleation layer is 10-100nm.
5. The method for manufacturing a gallium nitride-based HEMT device according to claim 1, characterized in that: The nitride epitaxial layer includes a channel layer, the material of the channel layer includes GaN, the growth temperature range of the channel layer is 1000-1050° C., the growth pressure range of the channel layer is 200-400 mbar, and the thickness range of the channel layer is 300-1200 nm.
6. The method for manufacturing a gallium nitride-based HEMT device according to claim 5, characterized in that: The nitride epitaxial layer further includes a buffer layer located below the channel layer, and the buffer layer is doped with Fe element. The material of the buffer layer is Al x Ga 1-x N, 0≤x≤0.1, the growth temperature range of the buffer layer is 900~1100℃, the growth pressure range of the buffer layer is 200~400mbar, the thickness range of the buffer layer is 200~600nm, and the doping concentration range of the Fe element is 5E15~1E19 cm -3 .
7. The method for manufacturing a gallium nitride-based HEMT device according to claim 6, characterized in that: The nitride epitaxial layer also includes a barrier layer located above the channel layer, the barrier layer and the channel layer form a heterojunction, the barrier layer includes at least one of a single-layer structure and a stacked structure, the growth temperature range of the barrier layer is 1050-1150°C, the growth pressure range of the barrier layer is 100-200mbar, and the thickness range of the barrier layer is 10-30nm.
8. The method for manufacturing a gallium nitride-based HEMT device according to claim 7, characterized in that: When the barrier layer is a stacked structure, the barrier layer includes at least one of AlN / Al(In)GaN / GaN, Al(In)N / GaN, Al(In)GaN / GaN, AlN / Al(In)GaN, AlN / AlScN / GaN, Al(In)N / GaN, AlScN / GaN, AlN / AlScN, AlN / Al(In)GaN / SiN, Al(In)N / SiN, Al(In)GaN / SiN, AlN / Al(In)GaN, AlN / AlScN / SiN, Al(In)N / SiN, AlScN / SiN and AlN / AlScN, wherein the thickness range of the AlN layer is 0 to 4 nm, the thickness range of the Al(In)GaN layer or the AlScN layer is 10 to 30 nm, and the thickness range of the GaN layer is 0 to 5 nm.
9. The method for manufacturing a gallium nitride-based HEMT device according to claim 1, characterized in that: The gallium nitride-based HEMT device includes at least one of a radio frequency device and a power device.
10. A gallium nitride-based HEMT device, characterized in that: The gallium nitride-based HEMT device comprises a substrate, a nucleation layer and a nitride epitaxial layer arranged in sequence from bottom to top, wherein the nucleation layer is doped to be n-type, the nitride epitaxial layer has defects that capture emitted electrons, and the nucleation layer is doped to raise the Fermi level to passivate the defects, so that the defects lose the ability to capture emitted electrons.