A method of fabricating a GaN HEMT device fabricated by Si ion implantation doping
By fabricating GaN HEMT devices through Si ion implantation doping, the problem of two-dimensional electron gas surface density saturation was solved, and the device performance was improved, especially in terms of high frequency, high breakdown voltage and high current density.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- XUZHOU GSR SEMICON CO LTD
- Filing Date
- 2022-09-07
- Publication Date
- 2026-07-31
AI Technical Summary
The surface density of the two-dimensional electron gas gradually saturates with the thickness of the AlGaN barrier layer, resulting in a limited increase in carrier surface density and failing to fully utilize the performance of GaN HEMT devices.
The method for fabricating GaN HEMT devices using Si ion implantation doping involves growing a SiO2 protective layer on the outer surface of the AlGaN barrier layer, and forming Si+ doping through Si ion implantation and high-temperature annealing. By combining the valence state difference between Si and Al, the concentration of the two-dimensional electron gas is increased, the on-resistance is reduced, and the power consumption is decreased.
It effectively increases the concentration of two-dimensional electron gas, reduces on-resistance, decreases power consumption, and improves the high-frequency, high-breakdown voltage, and high-current-density performance of the device. The process is simple and has good repeatability.
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Figure CN116798869B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of semiconductor device technology, and particularly relates to a method for manufacturing a GaN HEMT device by Si ion implantation doping. Background Technology
[0002] GaN HEMT devices, as third-generation semiconductor devices, possess inherent physical properties that make them ideal for high-frequency, high-power applications. Gallium nitride (GaN) materials exhibit excellent characteristics such as a large bandgap, high electron saturation velocity, high critical breakdown electric field, and strong radiation resistance. Therefore, high electron mobility transistors based on GaN materials are widely used in the fabrication of next-generation high-power, high-frequency solid-state microwave power devices. Because AlGaN materials have a wider bandgap than GaN materials, at equilibrium, the energy bands bend at the heterojunction interface, causing a discontinuity between the conduction and valence bands, forming a triangular potential well at the heterojunction interface. Figure 1 As can be seen, on the GaN side, the conduction band bottom EC is already below the Fermi level EF, so a large number of electrons accumulate in the triangular potential well. At the same time, the high potential barrier on the wide-bandgap AlGaN side makes it difficult for electrons to cross the potential well. Electrons are restricted to lateral movement in the thin layer of the interface, which is called the two-dimensional electron gas (2DEG).
[0003] The superior device performance of GaN-HEMTs primarily stems from the presence of a two-dimensional electron gas (2DEG) at the AlGaN / GaN interface. Due to polarization discontinuity and a large band offset, a high-concentration, high-mobility 2DEG can be induced at the AlGaN / GaN interface potential well, enabling GaN-HEMTs to exhibit excellent characteristics in high-voltage, high-frequency, and high-power applications. The unique two-dimensional electron gas structure of HEMT devices allows for low on-resistance. Based on strong polarization induction and a large band offset, a highly concentrated two-dimensional electron gas system with strong quantum localization can be formed within the quantum well of the AlGaN / GaN heterostructure interface, inducing up to ~10⁻⁶ electrons even without doping. 13 cm -2 2DEG.
[0004] Strengthening the control of 2DEG concentration and mobility at the AlGaN / GaN interface is crucial for improving the performance of power electronic devices, especially for controlling the threshold voltage and on-resistance. Increasing the 2DEG concentration at the AlGaN / GaN interface can reduce the on-resistance and power consumption of GaN-HEMTs. Currently, some methods increase the 2DEG areal density by increasing the AlGaN thickness or the Al content in AlGaN. However, the inventors believe that the 2DEG areal density gradually saturates with the AlGaN barrier layer thickness, limiting the increase in carrier areal density. Therefore, a method for fabricating GaN HEMT devices using Si ion implantation doping is needed.
[0005] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art. Summary of the Invention
[0006] Through research, the inventors discovered a technical problem: the surface density of two-dimensional electron gas gradually saturates with the thickness of the AlGaN barrier layer, resulting in a limited increase in carrier surface density and failing to fully utilize the performance of GaN HEMT devices.
[0007] In view of at least one of the above-mentioned technical problems, this disclosure provides a method for fabricating a GaN HEMT device by Si ion implantation doping, the specific technical solution of which is as follows:
[0008] A method for fabricating a GaN HEMT device using Si ion implantation doping includes the following steps: growing the basic structure of the GaN HEMT device, which includes a substrate and a buffer layer, a channel layer, and an AlGaN barrier layer epitaxially grown sequentially on the substrate; growing a SiO2 protective layer on the outer surface of the AlGaN barrier layer using PECVD technology; performing Si ion implantation on the upper surface of the AlGaN barrier layer to form a Si ion implantation layer; and annealing the Si ion implantation layer at high temperature until the Si... + Activation; depositing source / drain ohmic contact metals on the AlGaN barrier layer; achieving device isolation using ion implantation; photolithographically etching the gate pattern on the SiO2 protective layer, depositing the gate metal, growing the SiO2 isolation protective layer by PECVD, and then forming Si on the AlGaN barrier layer using ion implantation and high-temperature annealing. + Doping, since Si is a tetravalent element and Al is a trivalent element, the combination of the two can effectively increase the concentration of two-dimensional electron gas, reduce on-resistance, reduce power consumption, and improve device performance.
[0009] In some embodiments of this disclosure, the basic structure of the HEMT device is grown using MOCVD or MBE methods.
[0010] In some embodiments of this disclosure, the thickness of the buffer layer is 20–30 nm.
[0011] In some embodiments of this disclosure, the channel layer is a GaN layer with a thickness of 1–4 μm.
[0012] In some embodiments of this disclosure, the thickness of the AlGaN barrier layer is 10–20 nm.
[0013] In some embodiments of this disclosure, the Si ion implantation energy is 10–20 keV, and the implantation dose is 10. 14 ~10 15 / cm 2 .
[0014] In some embodiments of this disclosure, the high-temperature annealing activates Si + The annealing conditions are 1000–1200℃ for 1–5 min.
[0015] In some embodiments of this disclosure, the source / drain ohmic contact metal is a four-layer alloy structure of Ti / Al / Ni / Au, deposited using electron beam evaporation. The thicknesses of each metal layer are 10–30 nm / 100–200 nm / 50–100 nm / 50–100 nm, respectively. During evaporation, the metal evaporation rate is adjusted as needed according to the evaporation thickness. After all metals have evaporated, the metal is placed in a metal stripping solution for stripping to form an ohmic contact pattern. Then, the pattern is annealed in a rapid annealing furnace at a high temperature of 800–900 °C for 30–60 s to form the drain / source ohmic contact.
[0016] In some embodiments of this disclosure, the ion implantation isolation is the implantation of He into the basic structure of the HEMT device. + Ar + or N + At least one of them, forming an ion implantation region, He + Ar + or N + The implantation energy during ion implantation is 20–200 keV, and the implantation dose is 10. 14 ~10 15 cm 2 .
[0017] In some embodiments of this disclosure, the gate metal is at least one of nickel, gold, platinum, and palladium.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] After growing a SiO2 protective layer by PECVD, Si was formed in the AlGaN barrier layer by ion implantation and high-temperature annealing. + Doping, since Si is a tetravalent element and Al is a trivalent element, the combination of the two can effectively increase the concentration of two-dimensional electron gas, reduce on-resistance, reduce power consumption, and improve device performance. The process is simple and has good repeatability, and can meet the characteristics of high frequency, high breakdown voltage, and high current density of existing GaNHEMT devices. Attached Figure Description
[0020] Figure 1 Energy band diagram of GaN HEMT device;
[0021] Figure 2 This is a flowchart of the manufacturing process of GaN HEMT devices in the method of the present invention;
[0022] Figure 3 This is a structural diagram of a GaN HEMT device manufactured by the method of the present invention.
[0023] The labels in the figure are as follows: 1. Substrate; 2. Buffer layer; 3. Channel layer; 4. AlGaN barrier layer; 5. SiO2 protective layer; 6. Si ion implantation layer; 7. Source / drain ohmic contact metal; 8. Gate metal; 9. Two-dimensional electron gas; 10. Ion implantation region. Detailed implementation method:
[0024] To better understand the purpose, structure, and function of this invention, the technical solutions in the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments.
[0025] The component numbers used in this document are solely for distinguishing the objects described and have no sequential or technical meaning. The term "connection" in this disclosure, unless otherwise specified, includes both direct and indirect connections. In the description of this application, it should be understood that directional terms such as "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are used solely for the convenience of describing this application and for a brief description, and do not indicate or imply that the device or unit 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] As shown in the attached diagram. Figures 1 to 3As shown, a method for fabricating a GaN HEMT device using Si ion implantation doping is designed, including the following steps: growing the basic structure of the GaN HEMT device, which includes a substrate 1 and a buffer layer 2, a channel layer 3, and an AlGaN barrier layer 4 epitaxially grown sequentially on the substrate 1; growing a SiO2 protective layer 5 on the outer surface of the AlGaN barrier layer 4 using PECVD technology; performing Si ion implantation on the upper surface of the AlGaN barrier layer 4 to form a Si ion implantation layer 6; and annealing the Si ion implantation layer 6 at high temperature to form a Si ion implantation layer. + Activation; deposit source-drain ohmic contact metal 7 on AlGaN barrier layer 4; achieve device isolation by ion implantation isolation, photolithographically pattern the gate pattern on SiO2 protective layer 5, and deposit gate metal 8.
[0027] After growing a SiO2 protective layer by PECVD, Si was formed in the AlGaN barrier layer by ion implantation and high-temperature annealing. + Doping, since Si is a tetravalent element and Al is a trivalent element, the combination of the two can effectively increase the concentration of two-dimensional electron gas 9, reduce on-resistance, reduce power consumption, and improve device performance. The process is simple and has good repeatability, and can meet the characteristics of high frequency, high breakdown voltage, and high current density of existing GaNHEMT devices.
[0028] The above embodiments illustrate three examples of implementing the above technical solutions:
[0029] Example 1
[0030] This embodiment discloses a method for fabricating a GaN HEMT device using Si ion implantation doping, comprising the following steps: Growing the basic structure of the GaN HEMT device using MOCVD technology. The basic structure of the GaN HEMT device includes a substrate 1 and a buffer layer 2, a channel layer 3, and an AlGaN barrier layer 4 sequentially epitaxially grown on the substrate 1; Growing a SiO2 protective layer 5 on the outer surface of the AlGaN barrier layer 4 using PECVD technology. In this embodiment, the substrate 1 can be a silicon substrate, the buffer layer 2 is an aluminum nitride layer with a thickness of 20 nm, the channel layer 3 is a GaN layer with a thickness of 4 μm, and the AlGaN barrier layer 4 has a thickness of 20 nm; Performing Si ion implantation on the upper surface of the AlGaN barrier layer 4 to form a Si ion implantation layer 6, wherein the Si ion implantation energy is 20 keV and the implantation dose is 10. 14 / cm 2 High-temperature annealed Si ion implantation layer 6 to Si + Activation, high-temperature annealing activation of Si +The annealing conditions were 1000℃ for 5 minutes. Source / drain ohmic contact metal 7 was deposited on the AlGaN barrier layer 4. This source / drain ohmic contact metal 7 is a four-layer alloy structure of Ti / Al / Ni / Au, deposited using electron beam evaporation. The thicknesses of each metal layer were 10nm / 200nm / 100nm / 50nm, respectively. During evaporation, the evaporation rate was adjusted as needed based on the evaporation thickness. After all metals had evaporated, the metal was placed in a metal stripping solution for stripping to form the ohmic contact pattern. Then, it was subjected to high-temperature annealing at 800℃ for 60 seconds in a rapid annealing furnace to form the drain / source ohmic contacts 7. Isolation between devices was achieved using ion implantation isolation, specifically by implanting He into the basic structure of the HEMT device. + 10 ion implantation regions were formed, He + The implantation energy during ion implantation was 200 keV, and the implantation dose was 10. 14 cm 2 A gate pattern is photolithographically formed on the SiO2 protective layer 5, and gate metal 8 is deposited, wherein the gate metal 8 is nickel or gold.
[0031] After growing a SiO2 protective layer by PECVD, Si was formed in the AlGaN barrier layer by ion implantation and high-temperature annealing. + Doping, since Si is a tetravalent element and Al is a trivalent element, the combination of the two can effectively increase the concentration of two-dimensional electron gas 9, reduce on-resistance, reduce power consumption, and improve device performance. The process is simple and has good repeatability, and can meet the characteristics of high frequency, high breakdown voltage, and high current density of existing GaNHEMT devices.
[0032] Example 2
[0033] This embodiment discloses a method for fabricating a GaN HEMT device using Si ion implantation doping, comprising the following steps: Growing the basic structure of the GaN HEMT device using MOCVD technology. The basic structure of the GaN HEMT device includes a substrate 1 and a buffer layer 2, a channel layer 3, and an AlGaN barrier layer 4 sequentially epitaxially grown on the substrate 1; Growing a SiO2 protective layer 5 on the outer surface of the AlGaN barrier layer 4 using PECVD technology. In this embodiment, the substrate 1 can be a silicon carbide substrate, the buffer layer 2 is a gallium nitride layer with a thickness of 30 nm, the channel layer 3 is a GaN layer with a thickness of 1 μm, and the AlGaN barrier layer 4 has a thickness of 10 nm; Performing Si ion implantation on the upper surface of the AlGaN barrier layer 4 to form a Si ion implantation layer 6, wherein the Si ion implantation energy is 10 keV and the implantation dose is 10... 15 / cm 2 High-temperature annealed Si ion implantation layer 6 to Si +Activation, high-temperature annealing activation of Si + The annealing conditions were 1200℃ for 1 min. Source / drain ohmic contact metal 7 was deposited on the AlGaN barrier layer 4. This source / drain ohmic contact metal 7 is a four-layer alloy structure of Ti / Al / Ni / Au, deposited using electron beam evaporation. The thicknesses of each metal layer were 30nm / 100nm / 50nm / 100nm, respectively. During evaporation, the evaporation rate was adjusted as needed based on the evaporation thickness. After all metals had evaporated, the metal was placed in a metal stripping solution for stripping to form the ohmic contact pattern. Then, it was subjected to high-temperature annealing at 900℃ for 30 seconds in a rapid annealing furnace to form the drain / source ohmic contacts 7. Isolation between devices was achieved using ion implantation isolation, specifically by implanting Ar into the basic structure of the HEMT device. + , forming ion implantation region 10, Ar + The implantation energy during ion implantation was 20 keV, and the implantation dose was 10. 15 cm 2 A gate pattern is photolithographically formed on the SiO2 protective layer 5, and gate metal 8 is deposited, wherein the gate metal 8 is platinum.
[0034] After growing a SiO2 protective layer by PECVD, Si was formed in the AlGaN barrier layer by ion implantation and high-temperature annealing. + Doping, since Si is a tetravalent element and Al is a trivalent element, the combination of the two can effectively increase the concentration of two-dimensional electron gas 9, reduce on-resistance, reduce power consumption, and improve device performance. The process is simple and has good repeatability, and can meet the characteristics of high frequency, high breakdown voltage, and high current density of existing GaNHEMT devices.
[0035] Example 3
[0036] This embodiment discloses a method for fabricating a GaN HEMT device using Si ion implantation doping, comprising the following steps: The basic structure of the GaN HEMT device is grown using the MBE method. The basic structure of the GaN HEMT device includes a substrate 1 and a buffer layer 2, a channel layer 3, and an AlGaN barrier layer 4 sequentially epitaxially grown on the substrate 1; a SiO2 protective layer 5 is grown on the outer surface of the AlGaN barrier layer 4 using PECVD technology. In this embodiment, the substrate 1 can be a sapphire substrate, the buffer layer 2 is a gallium nitride layer with a thickness of 28 nm, the channel layer 3 is a GaN layer with a thickness of 3 μm, and the AlGaN barrier layer 4 has a thickness of 18 nm; Si ion implantation is performed on the upper surface of the AlGaN barrier layer 4 to form a Si ion implantation layer 6, the Si ion implantation energy is 16 keV, and the implantation dose is 10. 14 / cm 2High-temperature annealed Si ion implantation layer 6 to Si + Activation, high-temperature annealing activation of Si + The annealing conditions were 1100℃ for 3 minutes. Source / drain ohmic contact metal 7 was deposited on the AlGaN barrier layer 4. This source / drain ohmic contact metal 7 is a four-layer alloy structure of Ti / Al / Ni / Au, deposited using electron beam evaporation. The thicknesses of each metal layer were 16nm / 146nm / 87nm / 76nm, respectively. During evaporation, the evaporation rate was adjusted as needed based on the evaporation thickness. After all metals had evaporated, the metal was placed in a metal stripping solution for stripping to form the ohmic contact pattern. Then, it was subjected to high-temperature annealing at 850℃ for 40 seconds in a rapid annealing furnace to form the drain / source ohmic contacts 7. Isolation between devices was achieved using ion implantation isolation, specifically by implanting N2O3 into the basic structure of the HEMT device. + Forming an ion implantation region of 10 N + The implantation energy during ion implantation was 180 keV, and the implantation dose was 10. 14 cm 2 A gate pattern is photolithographically formed on the SiO2 protective layer 5, and gate metal 8 is deposited, wherein the gate metal 8 is palladium.
[0037] After growing a SiO2 protective layer by PECVD, Si was formed in the AlGaN barrier layer by ion implantation and high-temperature annealing. + Doping, since Si is a tetravalent element and Al is a trivalent element, the combination of the two can effectively increase the concentration of two-dimensional electron gas 9, reduce on-resistance, reduce power consumption, and improve device performance. The process is simple and has good repeatability, and can meet the characteristics of high frequency, high breakdown voltage, and high current density of existing GaNHEMT devices.
[0038] It is understood that the present invention has been described through some embodiments, and those skilled in the art will recognize that various changes or equivalent substitutions can be made to these features and embodiments without departing from the spirit and scope of the invention. Furthermore, under the teachings of the present invention, these features and embodiments can be modified to adapt to specific situations and materials without departing from the spirit and scope of the invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are within the protection scope of the present invention.
Claims
1. A method for fabricating a GaN HEMT device by Si ion implantation doping, characterized in that, The process includes the following steps: growing the basic structure of a GaN HEMT device, which includes a substrate (1) and a buffer layer (2), a channel layer (3), and an AlGaN barrier layer (4) epitaxially grown sequentially on the substrate (1); growing a SiO2 protective layer (5) on the outer surface of the AlGaN barrier layer (4) using PECVD technology; and performing Si ion implantation on the upper surface of the AlGaN barrier layer (4) to form a Si ion implantation layer (6), wherein the Si ion implantation energy is 10-20 keV and the implantation dose is 10... 14 ~10 15 / cm 2 ; High-temperature annealed Si ion implantation layer (6) to Si + Activate; deposit source and drain ohmic contact metal (7) on AlGaN barrier layer (4); achieve device isolation by ion implantation isolation, photolithographically pattern the gate pattern on SiO2 protective layer (5), and deposit gate metal (8).
2. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The basic structure of the HEMT device is grown using MOCVD or MBE methods.
3. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The thickness of the buffer layer (2) is 20-30 nm.
4. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The channel layer (3) is a GaN layer with a thickness of 1 to 4 μm.
5. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The thickness of the AlGaN barrier layer (4) is 10-20 nm.
6. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The high-temperature annealing activated Si + The annealing conditions are 1000–1200℃ for 1–5 min.
7. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The source-drain ohmic contact metal (7) is a four-layer alloy structure of Ti / Al / Ni / Au. The metal is deposited by electron beam evaporation. The thickness of each metal layer is 10-30nm / 100-200nm / 50-100nm / 50-100nm respectively. During the evaporation process, the metal evaporation rate is adjusted as needed according to the evaporation thickness. After all the metals have been evaporated, they are placed in a metal stripping solution for stripping to form an ohmic contact pattern. Then, the drain-source ohmic contact (7) is formed by high-temperature annealing in a rapid annealing furnace at a high temperature of 800-900℃ for 30-60s.
8. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The ion implantation isolation involves implanting He into the basic structure of the HEMT device. + Ar + or N + At least one of them, forming an ion implantation region (10), He + Ar + or N + The implantation energy during ion implantation is 20–200 keV, and the implantation dose is 10. 14 ~10 15 cm 2 .
9. The method for manufacturing a GaN HEMT device by Si ion implantation doping according to claim 1, characterized in that, The gate metal (8) is at least one of nickel, gold, platinum and palladium.