GaN-HEMT epitaxial structure and manufacturing method thereof

Abstract

The invention discloses a GaN-HEMT epitaxial structure and a manufacturing method thereof. The GaN-HEMT epitaxial structure comprises a substrate, and a nucleating layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked on the substrate. The high-resistance buffer layer is a forbidden band trapezoidal structure layer formed by a plurality of P-P-I heterojunctions which are sequentially grown in an epitaxial manner from bottom to top; and the forbidden band trapezoidal structure layer formed by the P-P-I heterojunction comprises an Al < x > Ga < 1-x > N layer doped with Fe, an Al < y > Ga < 1-y > N layer doped with C and an unartificially doped GaN layer. According to the high-resistance buffer layer of the forbidden band trapezoidal structure layer formed by epitaxially growing a plurality of P-P-I heterojunctions in sequence from bottom to top, the resistivity of the high-resistance layer can be improved, the uniformity can be improved, the leakage current can be reduced, and the reliability can be improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a GaN-HEMT epitaxial structure and a manufacturing method thereof. Background Art

[0002] GaN-based HEMT devices have become an excellent solution for high-frequency and high-power switching applications due to their excellent properties such as high electron mobility, high critical breakdown electric field strength, and high electron saturation velocity.

[0003] One of the key links in achieving high-quality GaN power devices is to grow a high-resistance layer, which can reduce the leakage current in the HEMT device, maintain the two-dimensional characteristics of the electron gas, increase the operating frequency of the device, suppress the current collapse effect, and increase the breakdown voltage of the HEMT device.

[0004] At present, some literature has proposed to use BGaN or (AlGa)2O3 alternating growth method to solve the problem. The reality is that these two materials currently require equipment and material growth at temperatures above 1400°C, which exceeds the limits of existing equipment on the market and is not suitable for large-scale mass production. In addition, the growth defects of the materials themselves are not well controlled.

[0005] Traditional high-resistance layers generally use C- or Mg-doped GaN layers to introduce deep energy level acceptors, thereby achieving a high-resistance state.

[0006] However, there are the following shortcomings: the Mg source has a memory effect, which will affect the channel layer of the device and thus deteriorate the device characteristics; and C doping is difficult to control uniformity.

[0007] To this end, a GaN-HEMT epitaxial structure and a manufacturing method thereof are proposed. Summary of the invention

[0008] The object of the present invention is to provide a GaN-HEMT epitaxial structure and a manufacturing method thereof to solve the problems raised in the above background technology.

[0009] To achieve the above object, the present invention provides the following technical solution: a GaN-HEMT epitaxial structure, comprising a substrate, on which a nucleation layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked;

[0010] The high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top;

[0011] The bandgap ladder structure layer formed by the PPI heterojunction includes Fe-doped Al x Ga 1-x N layer, C-doped Al y Ga 1-yN layer and non-artificially doped GaN layer.

[0012] Preferably: the Al x Ga 1-x In the N layer, 50%≤X≤100%, the Al y Ga 1-y In the N layer, 0%<y≤50%.

[0013] Preferably: the Al x Ga 1-x The thickness of the N layer is 2 to 5 nm. y Ga 1-y The thickness of N is 2-10 nm, and the thickness of the GaN layer is 5-10 nm.

[0014] Preferably: the Fe-doped Al x Ga 1-x The doping concentration of the N layer is 1e18at / cm 3 ~3e18at / cm 3 .

[0015] Preferably: the C-doped Al y Ga 1-y The doping concentration of the N layer is 5e18at / cm 3 ~3e19at / cm 3 .

[0016] Preferably, the repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 10 to 30.

[0017] Preferably, the substrate is a Si substrate, a SiC substrate or a sapphire substrate, and the nucleation layer is GaN or AlN.

[0018] A method for manufacturing a GaN-HEMT epitaxial structure according to any one of the above items comprises the following steps:

[0019] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0020] S2. growing a high-resistance buffer layer on the nucleation layer, wherein the growth temperature of the high-resistance buffer layer is 950-1100° C. and the growth pressure is 50-100 mbar;

[0021] S3, growing a channel layer on the high resistance buffer layer;

[0022] S4, growing a barrier layer on the channel layer;

[0023] S5. Growing a cap layer on the barrier layer.

[0024] Preferably, in step S3, the channel layer is a GaN layer grown at a temperature of 950-1100° C. and a pressure of 200 mbar, and has a thickness of 200-500 nm.

[0025] Preferably, in step S4, the barrier layer is Al grown at a temperature range of 1050-1100°C. t Ga 1-t N layer, thickness is 10-35 nm, wherein 15%<t<30%, and pressure is 50-100 mbar.

[0026] Compared with the prior art, the beneficial effects of the present invention are: by epitaxially growing a plurality of PPI heterojunctions from bottom to top to form a high-resistance buffer layer of a bandgap trapezoidal structure, the resistivity of the high-resistance layer can be increased, the uniformity can be improved, the leakage current can be reduced, and the reliability can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the present invention;

[0028] Figure 2 It is a schematic structural diagram of the high resistance buffer layer of the present invention;

[0029] Figure 3 The bandgap trapezoidal structure layer is formed by the PPI heterojunction of the present invention;

[0030] Figure 4 The voltage withstand and leakage curve diagram for verifying the device of the present invention. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0032] See also Figure 1-4 The present invention provides a technical solution: a GaN-HEMT epitaxial structure, including a substrate, such as Figure 1 As shown, a nucleation layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked on the substrate. The substrate is a Si substrate, a SiC substrate or a sapphire substrate, and the nucleation layer is GaN or AlN.

[0033] like Figure 2 and Figure 3 As shown, the high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top;

[0034] The so-called ladder structure refers to a heterojunction structure with three different band gaps: Al x Ga 1-x N layer, Al y Ga 1-yN layer and GaN layer, wherein 50%≤X≤100%, 0%<y≤50%.

[0035] Al x Ga 1-x The thickness of the N layer is 2 to 5 nm, and the Al y Ga 1-y The thickness of the N layer is 2 to 10 nm, and the thickness of the GaN layer is 5 to 10 nm.

[0036] The so-called PPI includes two different P-type semiconductor layers and an intrinsic semiconductor layer, and the Fe-doped Al x Ga 1-x N layer, doping concentration is 1e18at / cm 3 ~3e18at / cm 3 ; Use doped deep energy levels to capture scattered ions. C-doped Al y Ga 1-y N layer, doping concentration is 5e18at / cm 3 ~3e19at / cm 3 , compensating for the background N-type doping. The non-artificially doped GaN layer acts as a doped buffer isolation layer.

[0037] At the same time, the repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 10 to 30.

[0038] According to the above-mentioned method for manufacturing a GaN-HEMT epitaxial structure, the following steps are included:

[0039] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0040] S2. growing a high-resistance buffer layer on the nucleation layer, wherein the growth temperature of the high-resistance buffer layer is 950-1100° C. and the growth pressure is 50-100 mbar;

[0041] S3, growing a channel layer on the high resistance buffer layer, the channel layer is a GaN layer with a growth temperature of 950-1100° C. and a growth pressure of 200 mbar, and a thickness of 200-500 nm;

[0042] S4. A barrier layer is grown on the channel layer. The barrier layer is an Al2O3 layer grown at a temperature range of 1050-1100°C. t Ga 1-t N layer, thickness is 10-35nm, where 15%<t<30%, pressure is 50-100mbar;

[0043] S5. Growing a cap layer on the barrier layer.

[0044] Embodiment 1

[0045] The invention comprises a substrate, on which a nucleation layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked. The substrate is a Si substrate, and the nucleation layer is GaN.

[0046] The high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top;

[0047] The so-called ladder structure refers to a heterojunction structure with three different band gaps: Al x Ga 1-x N layer, Al y Ga 1-y N layer and GaN layer, where x=50%, y=10%.

[0048] Al x Ga 1-x The thickness of the N layer is 2nm, and the Al y Ga 1-y The thickness of the N layer is 2nm, and the thickness of the GaN layer is 5nm.

[0049] The so-called PPI includes two different P-type semiconductor layers and an intrinsic semiconductor layer, an AlxGa1-xN layer doped with Fe, and a doping concentration of 1e18at / cm 3 ; Use doped deep energy levels to capture scattered ions. AlyGa1-yN layer doped with C, with a doping concentration of 5e18at / cm 3 , compensating for the background N-type doping. The non-artificially doped GaN layer acts as a doped buffer isolation layer.

[0050] At the same time, the repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 10.

[0051] Embodiment 2

[0052] The invention comprises a substrate, on which a nucleation layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked. The substrate is a Si substrate, and the nucleation layer is GaN.

[0053] The high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top;

[0054] The so-called ladder structure refers to a heterojunction structure with three different band gaps: Al x Ga 1-x N layer, Al y Ga 1-y N layer and GaN layer, where x=60%, y=20%.

[0055] Al x Ga 1-x The thickness of the N layer is 3nm, and the Al y Ga1-y The thickness of the N layer is 4nm, and the thickness of the GaN layer is 7nm.

[0056] The so-called PPI includes two different P-type semiconductor layers and an intrinsic semiconductor layer, and the Fe-doped Al x Ga 1-x N layer, doping concentration is 1e18at / cm 3 ; Use doped deep energy levels to capture scattered ions. C-doped Al y Ga 1-y N layer, doping concentration is 5e18at / cm 3 , compensating for the background N-type doping. The non-artificially doped GaN layer acts as a doped buffer isolation layer.

[0057] At the same time, the repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 15.

[0058] Embodiment 3

[0059] The invention comprises a substrate, on which a nucleation layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked. The substrate is a SiC substrate, and the nucleation layer is AlN.

[0060] The high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top;

[0061] The so-called ladder structure refers to a heterojunction structure with three different band gaps: Al x Ga 1-x N layer, Al y Ga 1-y N layer and GaN layer, where x=70%, y=30%.

[0062] Al x Ga 1-x The thickness of the N layer is 4nm, and the Al y Ga 1-y The thickness of the N layer is 6nm, and the thickness of the GaN layer is 9nm.

[0063] The so-called PPI includes two different P-type semiconductor layers and an intrinsic semiconductor layer, and the Fe-doped Al x Ga 1-x N layer, doping concentration is 3e18at / cm 3 ; Use doped deep energy levels to capture scattered ions. C-doped Al y Ga 1-y N layer, doping concentration is 3e19at / cm 3 , compensating for the background N-type doping. The non-artificially doped GaN layer acts as a doped buffer isolation layer.

[0064] At the same time, the repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 20.

[0065] Embodiment 4

[0066] The invention comprises a substrate, on which a nucleation layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked. The substrate is a sapphire substrate, and the nucleation layer is AIN.

[0067] The high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top;

[0068] The so-called ladder structure refers to a heterojunction structure with three different band gaps: Al x Ga 1-x N layer, Al y Ga 1-y N layer and GaN layer, where x=80%, y=40%.

[0069] Al x Ga 1-x The thickness of the N layer is 5nm, and the Al y Ga 1-y The thickness of the N layer is 10 nm, and the thickness of the GaN layer is 10 nm.

[0070] The so-called PPI includes two different P-type semiconductor layers and an intrinsic semiconductor layer, and the Fe-doped Al x Ga 1-x N layer, doping concentration is 3e18at / cm 3 ; Use doped deep energy levels to capture scattered ions. C-doped Al y Ga 1-y N layer, doping concentration is 3e19at / cm 3 , compensating for the background N-type doping. The non-artificially doped GaN layer acts as a doped buffer isolation layer.

[0071] At the same time, the repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 30.

[0072] Embodiment 5

[0073] A method for manufacturing a GaN-HEMT epitaxial structure comprises the following steps:

[0074] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0075] S2. growing a high-resistance buffer layer on the nucleation layer. The growth temperature of the high-resistance buffer layer is 950° C. and the growth pressure is 50 mbar.

[0076] S3, growing a channel layer on the high resistance buffer layer, the channel layer is a GaN layer with a growth temperature of 950° C. and a growth pressure of 200 mbar, and a thickness of 200 nm;

[0077] S4. Grow a barrier layer on the channel layer. The barrier layer is Al grown at a temperature of 1050°C. t Ga 1-t N layer, thickness 10nm, where t = 17% and pressure 50mbar;

[0078] S5. Growing a cap layer on the barrier layer.

[0079] A method for manufacturing a GaN-HEMT epitaxial structure is implemented, comprising the following steps:

[0080] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0081] S2. growing a high-resistance buffer layer on the nucleation layer. The growth temperature of the high-resistance buffer layer is 1000° C. and the growth pressure is 65 mbar.

[0082] S3, growing a channel layer on the high resistance buffer layer, the channel layer is a GaN layer with a growth temperature of 1050° C. and a growth pressure of 200 mbar, and a thickness of 300 nm;

[0083] S4. A barrier layer is grown on the channel layer. The barrier layer is Al grown at a temperature range of 1060°C. t Ga 1-t N layer, thickness 15nm, where t = 20% and pressure 65mbar;

[0084] S5. Growing a cap layer on the barrier layer.

[0085] Embodiment 6

[0086] A method for manufacturing a GaN-HEMT epitaxial structure comprises the following steps:

[0087] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0088] S2. growing a high-resistance buffer layer on the nucleation layer. The growth temperature of the high-resistance buffer layer is 1050° C. and the growth pressure is 80 mbar.

[0089] S3, growing a channel layer on the high resistance buffer layer, the channel layer is a GaN layer with a growth temperature of 1070° C. and a growth pressure of 200 mbar, and a thickness of 400 nm;

[0090] S4. A barrier layer is grown on the channel layer. The barrier layer is Al grown at a temperature range of 1085°C. t Ga 1-tN layer, thickness 25nm, where t = 25% and pressure 80mbar;

[0091] S5. Growing a cap layer on the barrier layer.

[0092] Embodiment 7

[0093] A method for manufacturing a GaN-HEMT epitaxial structure comprises the following steps:

[0094] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0095] S2. growing a high-resistance buffer layer on the nucleation layer. The growth temperature of the high-resistance buffer layer is 1070° C. and the growth pressure is 90 mbar.

[0096] S3, growing a channel layer on the high resistance buffer layer, the channel layer is a GaN layer with a growth temperature of 1085° C. and a growth pressure of 200 mbar, and a thickness of 450 nm;

[0097] S4. A barrier layer is grown on the channel layer. The barrier layer is Al grown at a temperature range of 1095°C. t Ga 1-t N layer, thickness 30nm, where t = 27% and pressure 90mbar;

[0098] S5. Growing a cap layer on the barrier layer.

[0099] Embodiment 8

[0100] A method for manufacturing a GaN-HEMT epitaxial structure comprises the following steps:

[0101] S1, providing a substrate and epitaxially growing a nucleation layer on the substrate;

[0102] S2. growing a high-resistance buffer layer on the nucleation layer. The growth temperature of the high-resistance buffer layer is 1100° C. and the growth pressure is 100 mbar.

[0103] S3, growing a channel layer on the high resistance buffer layer, the channel layer is a GaN layer with a growth temperature of 1100° C. and a growth pressure of 200 mbar, and a thickness of 500 nm;

[0104] S4. A barrier layer is grown on the channel layer. The barrier layer is Al grown at a temperature range of 1100°C. t Ga 1-t N layer, thickness 35nm, where t = 30% and pressure 100mbar;

[0105] S5. Growing a cap layer on the barrier layer.

[0106] According to the technical requirements described in the present invention, it is possible to increase the resistivity of the high-resistance layer, improve uniformity, reduce leakage current, and improve reliability.

[0107] like Figure 4 As shown in the device verification voltage withstand-leakage curve, CenterA-1-S, MiddleA-2-S and EdgeA-3-S points were selected for production and performance measurement; while having strong voltage withstand characteristics and low leakage current, it has the consistency of the entire epitaxial wafer, ensuring high yield and low cost of production.

[0108] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A GaN-HEMT epitaxial structure, comprising a substrate, characterized in that: A core layer, a high-resistance buffer layer, a channel layer, a barrier layer and a cap layer are sequentially stacked on the substrate; The high-resistance buffer layer is a bandgap trapezoidal structure layer formed by multiple PPI heterojunctions grown epitaxially from bottom to top; The bandgap ladder structure layer formed by the PPI heterojunction includes Fe-doped Al x Ga 1-x N layer, C-doped Al y Ga 1- y N layer and non-artificially doped GaN layer.

2. A GaN-HEMT epitaxial structure according to claim 1, characterized in that: The Al x Ga 1-x In the N layer, 50%≤X≤100%, the Al y Ga 1-y In the N layer, 0%<y≤50%.

3. The GaN-HEMT epitaxial structure according to claim 1, characterized in that: The Al x Ga 1-x The thickness of the N layer is 2 to 5 nm. y Ga 1-y The thickness of N is 2-10 nm, and the thickness of the GaN layer is 5-10 nm.

4. The GaN-HEMT epitaxial structure according to claim 1, characterized in that: The Fe-doped Al x Ga 1-x The doping concentration of the N layer is 1e18at / cm 3 ~3e18at / cm 3 .

5. The GaN-HEMT epitaxial structure according to claim 1, characterized in that: The C-doped Al y Ga 1-y The doping concentration of the N layer is 5e18at / cm 3 ~3e19at / cm 3 .

6. The GaN-HEMT epitaxial structure according to claim 1, characterized in that: The repetition period of the PPI heterojunction structure in the PPI heterojunction structure is 10 to 30.

7. The GaN-HEMT epitaxial structure according to claim 1, characterized in that: The substrate is a Si substrate, a SiC substrate or a sapphire substrate, and the nucleation layer is GaN or AlN.

8. A method for manufacturing a GaN-HEMT epitaxial structure according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1, providing a substrate and epitaxially growing a nucleation layer on the substrate; S2. growing a high-resistance buffer layer on the nucleation layer, wherein the growth temperature of the high-resistance buffer layer is 950-1100° C. and the growth pressure is 50-100 mbar; S3, growing a channel layer on the high resistance buffer layer; S4, growing a barrier layer on the channel layer; S5. Growing a cap layer on the barrier layer.

9. A GaN-HEMT epitaxial structure and a method for manufacturing the same according to claim 8, characterized in that: In the step S3, the channel layer is a GaN layer grown at a temperature of 950-1100° C. and a pressure of 200 mbar, and has a thickness of 200-500 nm.

10. The GaN-HEMT epitaxial structure and the method for manufacturing the same according to claim 8, characterized in that: In step S4, the barrier layer is Al grown at a temperature range of 1050-1100°C. t Ga 1-t N layer, thickness is 10-35 nm, wherein 15%<t<30%, and pressure is 50-100 mbar.

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