Semiconductor epitaxial wafer and process method thereof
By constructing a P-type nitride composite layer in a semiconductor epitaxial sheet and co-doping is formed by using Si atom diffusion to solve the defect problem caused by high doping activation energy, the carrier injection uniformity and luminous efficiency are improved, and the leakage performance and production cost are improved.
Patent Information
- Application Number
- CN202311422092.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-30
- Publication Date
- 2025-05-06
AI Technical Summary
The existing semiconductor epitaxial sheet has high doping activation energy in the P-type nitride layer, resulting in low ionization rate, forming deep energy level defects, increasing leakage channels, and uneven carrier distribution, affecting luminescence efficiency.
The P-type nitride seed layer and the connecting layer and the P-type nitride sub-layer formed by alternately laminating are formed in the P-type nitride composite layer. The Si atom diffusion forms co-doping, improves the doping activation efficiency, and forms a hole concentration gradient in the thickness direction to enhance the lateral expansion and injection uniformity of holes.
The crystal quality of the semiconductor epitaxial sheet is improved, the carrier radiation recombination efficiency is enhanced, the leakage performance is improved, the luminous brightness is improved, and the growth cost is reduced.
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Figure CN119947359A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor epitaxy technology, and in particular to a semiconductor epitaxial wafer and a process method thereof. Background Art
[0002] As semiconductor materials are increasingly used, the performance requirements for semiconductor materials and devices are constantly increasing, so LED-related structural research is very important for understanding materials and improving device performance and quality. In the prior art, SiNx mask technology is introduced during epitaxial growth. SiNx mask is used to reduce nitride material defects and improve crystal quality, but the introduction of SiNx will also cause changes in GaN film strain, electrical, optical and other properties. Therefore, it is of great significance to improve the performance of semiconductor devices on the basis of obtaining low-defect epitaxial layers.
[0003] In the prior art, in the semiconductor epitaxial wafer structure, the P-type nitride layer has a high resistivity, and a relatively high P-type dopant is usually used to dope the P-type nitride. However, due to the high activation energy of the P-type dopant, the ionization rate of the high doping in the P-type nitride layer is less than 1%, and the doping atoms that fail to ionize form deep energy level defects, resulting in the P-type nitride layer having a high defect formation leakage channel, which further leads to uneven distribution of P-type nitride carriers, reduces the injection of carriers in the P-type nitride into the nitride light-emitting layer, and in order to reduce the effect of doping in the P-type nitride layer on the nitride light-emitting layer, and at the same time, in order to prevent the electrons from the N-type nitride layer from overflowing to the P-type nitride layer, a high barrier nitride layer is generally set in the nitride light-emitting layer and the N-type nitride layer. However, this technology does not improve the crystal quality and carrier optimization of the P-type layer itself.
[0004] So, in order to solve these technical problems, we need to improve the existing semiconductor epitaxial wafers to improve these defects. Summary of the invention
[0005] The object of the present invention is to provide a semiconductor epitaxial wafer and a process method thereof, which can improve the crystal quality of the semiconductor epitaxial wafer, enhance the uniformity of carrier injection from the P-type nitride composite layer to the nitride light-emitting layer, improve the carrier radiation recombination efficiency and the luminous brightness of the semiconductor epitaxial wafer, improve the leakage performance of the semiconductor epitaxial wafer, improve the production yield of the semiconductor epitaxial wafer, and reduce the growth cost of the semiconductor epitaxial wafer.
[0006] The purpose of the present invention is achieved by the following technical solutions:
[0007] A semiconductor epitaxial wafer, comprising a substrate, an N-type nitride layer located on the substrate, a nitride light-emitting layer and a P-type nitride composite layer, wherein the P-type nitride composite layer comprises a P-type nitride seed layer and a connection layer and a P-type nitride sublayer generated by cyclic alternating stacking;
[0008] Among them, the majority carriers of the P-type nitride sublayer are holes, and the connecting layer introduces Si atoms to diffuse into the P-type nitride sublayer. After the Si atoms diffuse, co-doping is formed in the P-type nitride sublayer to improve the activation efficiency of the doping in the P-type nitride sublayer.
[0009] Preferably, during the cyclic alternation process, in the direction from the substrate to the nitride light-emitting layer, the thickness of each connecting layer in the P-type nitride composite layer increases successively.
[0010] Preferably, the connection layer is a silicon nitride layer, and the atomic ratio of Si to N in the connection layer is greater than 1;
[0011] Preferably, the connecting layer has a nanoporous layered structure, and the size of the nanoporous layered structure of the connecting layer is 5-150 nm.
[0012] Preferably, the thickness of the connection layer and the P-type nitride sublayer after cyclic alternation is 50 to 200 nm;
[0013] The thickness of the P-type nitride seed layer is 5-15 nm;
[0014] The thickness of each connecting layer is 1 to 10 nm;
[0015] The thickness of each P-type nitride sublayer is 10-20 nm.
[0016] Preferably, the hole concentration of the P-type nitride sublayer increases sequentially;
[0017] Preferably, the hole concentration of the P-type nitride seed layer is 1×10 17 cm -3 ~1×10 19 cm -3 , the electron compensation concentration of the connecting layer is 1×10 17 cm -3 ~1×10 18 cm -3 , the hole concentration of the P-type nitride sublayer is 1×10 17 cm -3 ~1×10 19 cm -3 ; The electron compensation concentration of the connecting layer is the compensated electron concentration in the P-type nitride sublayer caused by the diffusion of Si atoms in the connecting layer in the thickness growth direction of the substrate toward the nitride light-emitting layer.
[0018] A process method for semiconductor epitaxial wafer, wherein an N-type nitride layer, a nitride light-emitting layer and a P-type nitride composite layer are sequentially grown on a substrate; the P-type nitride composite layer comprises a P-type nitride seed layer and a connection layer and a P-type nitride sublayer generated by cyclic alternating stacking;
[0019] The process of the P-type nitride composite layer comprises:
[0020] Under a first growth condition, growing the P-type nitride seed layer;
[0021] Under the second growth condition, growing the connection layer;
[0022] Under a third growth condition, growing the P-type nitride sublayer;
[0023] Among them, the majority carriers of the P-type nitride sublayer are holes, and the connecting layer introduces Si atoms to diffuse into the P-type nitride sublayer. After the Si atoms diffuse, co-doping is formed in the P-type nitride sublayer to improve the activation efficiency of the doping in the P-type nitride sublayer.
[0024] Preferably, the first growth condition includes at least a first temperature and a first pressure; the second growth condition includes at least a second temperature and a second pressure; the third growth condition includes at least a third temperature and a third pressure;
[0025] wherein the first temperature is higher than the third temperature, and the first pressure is higher than the third pressure;
[0026] Preferably, the first temperature is 900-1200° C., and the first pressure is 100-600 torr;
[0027] The second temperature is 950-1050°C, and the second pressure is 300-600 torr;
[0028] The third temperature is 850-1000° C., and the third pressure is 100-400 torr.
[0029] Preferably, the connecting layer is a silicon nitride layer;
[0030] The second growth condition at least includes: introducing SiH4 as a Si source and NH3 as a N source; in the thickness growth direction from the substrate to the nitride light-emitting layer, the concentration of compensated electrons in the P-type nitride sublayer caused by the diffusion of Si atoms in the connecting layer is 1×10 17 cm -3 ~1×10 18 cm -3 ;
[0031] The third growth condition at least includes: introducing a Ga source, a Mg source and a N source, wherein the N source flow rate is 5 to 100 slm, and the Mg source flow rate is 200 to 1000 sccm; wherein, during the cyclic alternation process, the Mg source flow rate of growing the P-type nitride sublayer is gradually increased, so that the hole concentration of the P-type nitride sublayer is sequentially increased;
[0032] Preferably, the increase rate of the Mg source flow rate is 5-20%.
[0033] Preferably, the flow ratio of the Si source to the N source gradually increases with the cyclic growth of the connection layer and the P-type nitride sublayer;
[0034] And / or, the flow ratio of the Si source to the N source is: 1:100-1:5.
[0035] Preferably, after growing the P-type nitride sublayer under the third growth condition, the method further comprises:
[0036] Turning off the Ga source and the Mg source, and maintaining the N source to flow continuously for 10 to 30 seconds to treat the surface of the P-type nitride sublayer;
[0037] And / or, the first growth condition at least includes: introducing Ga source, Mg source and N source, and after growing the P-type nitride seed layer under the first growth condition, it also includes: turning off the Ga source and the Mg source, maintaining the continuous introduction of the N source for 10 to 30 seconds, and treating the surface of the P-type nitride seed layer.
[0038] Compared with the prior art, the beneficial effects of the present invention include at least:
[0039] The semiconductor epitaxial wafer and the process method thereof of the present invention generate a P-type nitride composite layer through a P-type nitride seed layer and a connection layer and a P-type nitride sublayer generated by cyclically alternating stacking from bottom to top. The connection layer can shield the surface defects of the P-type nitride seed layer, and also strengthen the lateral epitaxial growth of the P-type nitride sublayer, thereby improving the crystal quality of the semiconductor epitaxial wafer. The P-type nitride seed layer blocks the Si atoms in the connection layer from diffusing into the nitride light-emitting layer, thereby improving the carrier radiation recombination efficiency and the leakage performance of the semiconductor epitaxial wafer.
[0040] Furthermore, the thickness of each connecting layer in the P-type nitride composite layer increases in the direction from the substrate to the nitride light-emitting layer, so that the electron supply capacity formed by the diffusion of Si atoms in each connecting layer is enhanced in turn, which matches the increase in the carrier concentration in the P-type nitride sublayer. Therefore, the co-doping effect formed by Si as a donor and acceptor impurity in each P-type nitride sublayer is enhanced in turn, which improves the acceptor doping activation efficiency. Therefore, the P-type nitride composite layer forms a concentration gradient of hole concentration from low to high in the thickness direction, which improves the P-type nitride The holes in the P-type nitride composite layer expand laterally, which improves the hole injection in the P-type nitride composite layer and the carrier injection uniformity in the nitride light-emitting layer, thereby improving the luminescence brightness of the semiconductor epitaxial wafer. In addition, in the direction of the substrate toward the nitride light-emitting layer, the high acceptor activation efficiency of the P-type nitride composite layer makes it unnecessary to use excessive doping in the P-type nitride sublayer to increase the hole concentration, thereby avoiding the leakage problem caused by the introduction of defects caused by high doping, improving the comprehensive yield of semiconductor epitaxial wafers, and reducing the growth cost of semiconductor epitaxial wafers. BRIEF DESCRIPTION OF THE DRAWINGS
[0041] Figure 1 It is a schematic diagram of the cross-sectional structure of a semiconductor epitaxial wafer according to an embodiment of the present invention.
[0042] Figure 2 It is a schematic diagram of the cross-sectional structure of another semiconductor epitaxial wafer according to an embodiment of the present invention.
[0043] Figure 3 It is a schematic flow chart of a process method for producing a semiconductor epitaxial wafer according to an embodiment of the present invention.
[0044] In the figure: 1, substrate; 2, N-type nitride layer; 3, nitride light-emitting layer; 31, nitride quantum well layer; 32, nitride quantum barrier layer; 4, P-type nitride composite layer; 41, P-type nitride seed layer; 42, connection layer; 43, P-type nitride sublayer. DETAILED DESCRIPTION
[0045] Example embodiments will now be described more fully with reference to the accompanying drawings. However, example embodiments can be implemented in a variety of forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided to make the present invention more comprehensive and complete and to fully convey the concepts of example embodiments to those skilled in the art. The same reference numerals in the figures represent the same or similar structures, and thus their repeated description will be omitted.
[0046] The words expressing positions and directions described in the present invention are all explained with reference to the accompanying drawings as examples, but they can be changed as needed, and all such changes are included in the protection scope of the present invention.
[0047] Reference Figure 1 to Figure 2 The present invention provides a semiconductor epitaxial wafer, comprising a substrate 1, an N-type nitride layer 2, a nitride light-emitting layer 3 and a P-type nitride composite layer 4. The N-type nitride layer 2 is located on the substrate 1, the nitride light-emitting layer 3 is located on the N-type nitride layer 2, and the P-type nitride composite layer 4 is located on the nitride light-emitting layer 3.
[0048] Specifically, the substrate 1 may be made of materials such as sapphire, silicon, gallium nitride or silicon carbide. In this embodiment, the substrate 1 is preferably sapphire.
[0049] The N-type nitride layer 2 is grown on the substrate 1. The N-type nitride layer 2 is, for example, an N-type GaN layer. The N-type GaN layer has a high ionization degree and provides electrons for the semiconductor epitaxial wafer. The thickness of the N-type nitride layer 2 is 1-10 μm, for example, 2 μm, 4 μm, 6 μm, 8 μm, and the electron concentration of the N-type nitride layer 2 is 1×10 18 cm -3 ~1×10 19 cm -3 , for example, 3×10 18 cm -3 , 5×10 18 cm -3 ,7×10 18 cm -3 ,9×10 18 cm -3 .
[0050] The nitride light-emitting layer 3 is preferably a gallium nitride system material, and the nitride light-emitting layer 3 is used for carrier recombination light emission. The nitride light-emitting layer 3 includes a nitride quantum well layer 31 and a nitride quantum barrier layer 32 which are generated by cyclic alternating stacking from bottom to top, and the number of cyclic alternations of the nitride quantum well layer 31 and the nitride quantum barrier layer 32 is 2 to 20, for example, 3, 6, 9, 12, 15, 18. The nitride quantum well layer 31 is, for example, an InGaN quantum well layer, and the nitride quantum barrier layer 32 is, for example, a GaN quantum barrier layer. The thickness of each nitride quantum well layer 31 is 1 to 6 nm, for example, 2 nm, 3 nm, 4 nm, and 5 nm, and the thickness of each nitride quantum barrier layer 32 is 6 to 18 nm, for example, 8 nm, 10 nm, 12 nm, 14 nm, and 16 nm. As a preferred embodiment, in each cycle, the thickness of the nitride quantum barrier layer 32 is greater than the thickness of the nitride quantum well layer 31. The thicker nitride quantum barrier layer 32 can suppress the carrier leakage in the nitride light-emitting layer 3, thereby improving the light-emitting effect and stability of the semiconductor epitaxial wafer.
[0051] The P-type nitride composite layer 4 includes a P-type nitride seed layer 41 and a connection layer 42 and a P-type nitride sublayer 43 that are formed by cyclically alternating stacking from bottom to top. The P-type nitride seed layer 41 and the P-type nitride sublayer 43 are, for example, a P-type GaN layer. The majority carriers of the P-type nitride seed layer 41 and the P-type nitride sublayer 43 are holes. The connection layer 42 introduces Si atoms for diffusion into the P-type nitride sublayer 43. After the Si atoms diffuse, co-doping is formed in the P-type nitride sublayer 43. The P-type nitride sublayer 43 is generally doped with Mg to improve the activation efficiency of the doping in the P-type nitride sublayer 43.
[0052] In the present invention, a SiN connecting layer 42 is grown in the P-type nitride composite layer 4, Si atoms are diffused in the SiN connecting layer 42, and a small amount of electrons are introduced. In this way, Si in the P-type nitride sublayer 43 can be used as a donor and an acceptor to form a co-doping effect. The co-doping effect is achieved by increasing the solubility of the required dopant and improving the doping activation efficiency of the dopant through the interaction between dopants. In the present invention, a co-doping effect is formed by Si atoms and Mg atoms, thereby improving the doping activation efficiency of Mg. In the direction of the substrate 1 toward the nitride light-emitting layer 3, the high acceptor activation efficiency of the P-type nitride composite layer 4 makes it unnecessary to use excessive doping in the P-type nitride sublayer 43 to increase the hole concentration (in the semiconductor epitaxial wafer structure, a relatively high P-type dopant is usually used to dope the P-type nitride, but due to the high activation energy of the P-type dopant, the high doping ionization rate in the P-type nitride layer is <1%, and the unionized doping atoms form deep energy level defects, resulting in the P-type nitride layer having a high defect formation leakage channel, further resulting in uneven distribution of P-type nitride carriers, reducing the injection of carriers in the P-type nitride into the nitride light-emitting layer 3. Because the activation efficiency of the present invention is high, a high hole concentration can be achieved within the process range by relatively low doping compared to the growth of conventional P-type nitride layers), thereby avoiding the leakage problem caused by the introduction of defects caused by high doping, improving the overall yield of semiconductor epitaxial wafers, and reducing the growth cost of semiconductor epitaxial wafers.
[0053] As a preferred mode, in the process of cyclic alternation, in the direction from the substrate 1 to the nitride light-emitting layer 3, the thickness of each connecting layer 42 in the P-type nitride composite layer 4 increases successively. As the thickness of the connecting layer 42 increases, the electron supply capacity formed by the diffusion of Si atoms in the connecting layer 42 is successively enhanced, which matches the sequential increase in the carrier concentration in the P-type nitride sublayer 43. Therefore, the co-doping effect formed by Si as a donor and an acceptor impurity in each P-type nitride sublayer 43 is successively strengthened, which improves the acceptor doping activation efficiency. Therefore, in the thickness direction, the P-type nitride composite layer 4 forms a concentration gradient of hole concentration from low to high, which improves the lateral expansion of holes in the P-type nitride composite layer 4, improves the hole injection in the P-type nitride composite layer 4, and improves the uniformity of carrier injection in the nitride light-emitting layer 3, thereby improving the luminous brightness of the semiconductor epitaxial wafer.
[0054] It should be noted that, during the cyclic alternation process, in the direction from the substrate 1 to the nitride light-emitting layer 3, the thickness of each connecting layer 42 in the P-type nitride composite layer 4 increases successively. This does not only mean that the thickness of each connecting layer 42 increases layer by layer, but also means that in the direction from the substrate 1 to the nitride light-emitting layer 3, the thickness of the connecting layer 42 increases successively and has an increasing trend.
[0055] Thus, a P-type nitride composite layer 4 is generated by the P-type nitride seed layer 41 and the connecting layer 42 and the P-type nitride sublayer 43 which are stacked alternately from bottom to top. The connecting layer 42 can shield the surface defects of the P-type nitride seed layer 41, and also strengthen the lateral epitaxial growth of the P-type nitride sublayer 43, thereby improving the crystal quality of the semiconductor epitaxial wafer. The P-type nitride seed layer 41 blocks the Si atoms in the connecting layer 42 from diffusing into the nitride light-emitting layer 3, thereby improving the carrier radiation recombination efficiency and the leakage performance of the semiconductor epitaxial wafer. During the cyclic alternation process, the thickness of each connecting layer 42 in the P-type nitride composite layer 4 increases in the direction from the substrate 1 to the nitride light-emitting layer 3, so that the electron supply capacity formed by the diffusion of Si atoms in each connecting layer 42 is enhanced in turn, which matches the increase in the carrier concentration in the P-type nitride sublayer 43. Therefore, the co-doping effect formed by Si as a donor and acceptor impurity in each P-type nitride sublayer 43 is enhanced in turn, which improves the acceptor doping activation efficiency. Therefore, the P-type nitride composite layer 4 forms a concentration gradient of hole concentration from low to high in the thickness direction, which improves The holes in the P-type nitride composite layer 4 expand laterally, which improves the hole injection in the P-type nitride composite layer 4 and improves the carrier injection uniformity in the nitride light-emitting layer 3, thereby improving the luminescence brightness of the semiconductor epitaxial wafer. In addition, in the direction of the substrate 1 toward the nitride light-emitting layer 3, the high acceptor activation efficiency of the P-type nitride composite layer 4 makes it unnecessary to use excessive doping in the P-type nitride sublayer 43 to increase the hole concentration, thereby avoiding leakage problems caused by the introduction of defects caused by high doping, improving the overall yield of the semiconductor epitaxial wafer, and reducing the growth cost of the semiconductor epitaxial wafer.
[0056] As a preferred embodiment, the connection layer 42 is a silicon nitride layer, and the atomic ratio of Si to N in the connection layer 42 is greater than 1. The SiN structure layer containing rich Si is formed by utilizing the non-stoichiometric ratio of the atoms in the seed layer. As the thickness of the connection layer 42 increases, a Si diffusion electron supply layer is formed during the subsequent growth of the P-type nitride composite layer 4. As the thickness of the connection layer 42 increases, the Si diffusion electron supply layer has a stronger capacity, and can provide more compensation electrons to the subsequent P-type nitride composite layer 4.
[0057] The connection layer 42 has a nanoporous layered structure, and the size of the nanoporous layered structure of the connection layer 42 is 5-150nm. The silicon nitride layer has the characteristic of discontinuous film formation at the micro-nano thickness, and the deposition of the connection layer 42 is completed on the P-type nitride seed layer 41 and the P-type nitride sublayer 43. The method for completing the deposition of the connection layer 42 on the P-type nitride seed layer 41 and the P-type nitride sublayer 43 can adopt the existing technology, which will not be repeated here. The connection layer 42 can form a nanoporous layered structure.
[0058] The connection layer 42 can shield the surface defects of the P-type nitride seed layer 41 and the P-type nitride sublayer 43, thereby improving the crystal quality of the P-type nitride seed layer 41 and the P-type nitride sublayer 43. In addition, during the cyclic alternation process, the thickness of the connection layer 42 increases in the thickness direction, and the nanopore structure can be used to roughen the surface of the P-type nitride seed layer 41 and the P-type nitride sublayer 43, while strengthening the lateral epitaxial growth of the P-type nitride seed layer 41 and the P-type nitride sublayer 43, thereby improving the crystal quality of the P-type nitride seed layer 41 and the P-type nitride sublayer 43.
[0059] As a preferred embodiment, the thickness of the P-type nitride seed layer 41 is 5 to 15 nm, for example, 7 nm, 9 nm, 11 nm, or 13 nm. The hole concentration of the P-type nitride seed layer 41 is 1×10 17 cm -3 ~1×10 19 cm -3 , for example, 4×10 17 cm -3 , 8×10 17 cm -3 , 4×10 18 cm -3 , 8×10 18 cm -3 .
[0060] The thickness of each connecting layer 42 is 1-10 nm, for example, 2 nm, 4 nm, 6 nm, 8 nm. The electron compensation concentration of the connecting layer 42 is 1×10 17 cm -3 ~1×10 18 cm -3 , for example, 3×10 17 cm -3 , 5×10 17 cm -3 ,7×10 17 cm -3 ,9×10 17 cm -3 .
[0061] The thickness of each P-type nitride sublayer 43 is 10-20 nm, for example, 12 nm, 14 nm, 16 nm, 18 nm. The hole concentration of the P-type nitride sublayer 43 is 1×10 17 cm -3 ~1×10 19 cm -3 , for example, 4×10 17 cm -3 , 8×10 17 cm -3 , 4×10 18cm -3 , 8×10 18 cm -3 .
[0062] The number of cyclic alternations of the connection layer 42 and the P-type nitride sublayer 43 can be set according to actual needs. The thickness of the connection layer 42 and the P-type nitride sublayer 43 after cyclic alternation is 50-200 nm, for example, 90 nm, 120 nm, 160 nm, 190 nm.
[0063] The electron compensation concentration of the connection layer 42 is the electron concentration compensated in the P-type nitride sublayer 43 by the diffusion of Si atoms in the connection layer 42 in the thickness growth direction from the substrate 1 to the nitride light-emitting layer 3. The hole concentration of the P-type nitride sublayer 43 increases successively, and the hole concentration of the P-type nitride sublayer 43 increases successively in the thickness growth direction from the substrate 1 to the nitride light-emitting layer 3. The Si diffusion in the connection layer 42 forms a co-doping match, which improves the lateral expansion of the holes in the P-type nitride composite layer 4, improves the hole sub-injection in the P-type nitride composite layer 4, and improves the uniformity of carrier injection in the nitride light-emitting layer 3, thereby improving the luminous brightness of the semiconductor epitaxial wafer. At the same time, there is no need to use excessive doping to increase the hole concentration, thereby avoiding the leakage problem caused by the introduction of defects caused by high doping.
[0064] Reference Figure 3 The present invention also provides a process method for a semiconductor epitaxial wafer, wherein an N-type nitride layer 2, a nitride light-emitting layer 3 and a P-type nitride composite layer 4 are sequentially grown on a substrate 1; the P-type nitride composite layer 4 comprises a P-type nitride seed layer 41 and a connecting layer 42 and a P-type nitride sublayer 43 generated by cyclic alternating stacking, specifically comprising steps S1-S4.
[0065] Step S1: providing a substrate 1.
[0066] Step S2: growing an N-type nitride layer 2 on the substrate 1 .
[0067] When growing the N-type nitride layer 2, the growth temperature of the N-type nitride layer 2 is 900-1200°C, for example, 950°C, 1000°C, 1050°C, 1100°C, 1150°C, and the growth pressure of the N-type nitride layer 2 is 50-650 torr, for example, 100 torr, 200 torr, 300 torr, 400 torr, 500 torr, 600 torr. The thickness of the N-type nitride layer 2 is 1-10 μm, for example, 2 μm, 4 μm, 6 μm, 8 μm, and the electron concentration of the N-type nitride layer 2 is 1×10 18 cm -3 ~1×10 19 cm -3 , for example, 3×1018 cm -3 , 5×10 18 cm -3 ,7×10 18 cm -3 ,9×10 18 cm -3 The N-type nitride layer 2 is, for example, N-type GaN, the Ga source used is TMG (trimethylgallium, C3H9Ga), the N source is NH3, and the dopant is SiH4.
[0068] Step S3: growing a nitride light emitting layer 3 on the N-type nitride layer 2 .
[0069] When the nitride light emitting layer 3 is grown, the nitride light emitting layer 3 includes a nitride quantum well layer 31 and a nitride quantum barrier layer 32 which are cyclically and alternately stacked from bottom to top, and the number of cyclic alternations of the nitride quantum well layer 31 and the nitride quantum barrier layer 32 is 2 to 20, for example, 3, 6, 9, 12, 15, 18. The growth temperature of the nitride quantum well layer 31 is 700 to 1150° C., for example, 800° C., 900° C., 1000° C., 1100° C., the growth pressure of the nitride quantum well layer 31 is 100 torr to 500 torr, for example, 150 torr, 200 torr, 300 torr, 350 torr, 400 torr, 450 torr, and the thickness of each nitride quantum well layer 31 is 1 to 6 nm, for example, 2 nm, 3 nm, 4 nm, 5 nm. The growth temperature of the nitride quantum barrier layer 32 is 750-1200°C, for example, 800°C, 900°C, 1000°C, and 1100°C. The growth pressure of the nitride quantum barrier layer 32 is 100-500 torr, for example, 150 torr, 200 torr, 300 torr, 350 torr, 400 torr, and 450 torr. The thickness of each nitride quantum barrier layer 32 is 6-18 nm, for example, 8 nm, 10 nm, 12 nm, 14 nm, and 16 nm.
[0070] The nitride quantum well layer 31 is, for example, an InGaN quantum well layer, the Ga source used is trimethylgallium, triethylgallium, etc., the In source is TMIn, and the N source is NH3. The nitride quantum barrier layer 32 is, for example, a GaN quantum barrier layer, the Ga source used is triethylgallium, trimethylgallium, etc., and the N source is NH3.
[0071] Step S4: growing a P-type nitride composite layer 4 on the nitride light-emitting layer 3 .
[0072] Specifically, the P-type nitride composite layer 4 includes a P-type nitride seed layer 41 and a connection layer 42 and a P-type nitride sublayer 43 that are cyclically and alternately stacked from bottom to top. The thickness of the P-type nitride seed layer 41 is 5 to 15 nm, for example, 7 nm, 9 nm, 11 nm, and 13 nm. The thickness of the connection layer 42 and the P-type nitride sublayer 43 after cyclic alternation is 50 to 200 nm, for example, 90 nm, 120 nm, 160 nm, and 190 nm. The number of cyclic alternations of the connection layer 42 and the P-type nitride sublayer 43 can be set according to actual needs.
[0073] The P-type nitride seed layer 41 and the P-type nitride sublayer 43 are, for example, P-type GaN layers, the connecting layer 42 is a silicon nitride layer, and the atomic ratio of Si to N in the connecting layer 42 is greater than 1, for example, 1.3, 1.5, 1.8, 2.0, 2.3. During the cyclic alternation process, in the direction from the substrate 1 to the nitride light-emitting layer 3, the atomic ratio of Si to N in each connecting layer 42 increases successively.
[0074] The connection layer 42 preferably has a nanoporous layered structure, and the size of the nanoporous layered structure of the connection layer 42 is 5-150 nm. The majority carriers of the P-type nitride sublayer 43 are holes, and the connection layer 42 introduces Si atoms for diffusion into the P-type nitride sublayer 43. After the Si atoms diffuse, co-doping is formed in the P-type nitride sublayer 43 to improve the activation efficiency of the doping in the P-type nitride sublayer 43.
[0075] Step S4 includes steps S41-S43.
[0076] Step S41 : growing a P-type nitride seed layer 41 under a first growth condition.
[0077] The first growth condition at least includes a first temperature and a first pressure. The first temperature is 900-1200°C, for example, 950°C, 1000°C, 1050°C, 1100°C, 1150°C. The first pressure is 100-600 torr, for example, 100 torr, 200 torr, 300 torr, 400 torr, 500 torr, 600 torr. The thickness of the P-type nitride seed layer 41 is 5-15 nm, for example, 7 nm, 9 nm, 11 nm, 13 nm. The hole concentration of the P-type nitride seed layer 41 is 1×10 17 cm -3 ~1×10 19 cm -3 , for example, 4×10 17 cm -3 , 8×10 17 cm -3 , 4×10 18 cm -3 , 8×10 18cm -3 .
[0078] The P-type nitride seed layer 41 is, for example, P-type GaN, the Ga source used is TMG (trimethylgallium, C3H9Ga), the N source is NH3, and the Mg source is the dopant Cp2Mg.
[0079] Step S42: growing a connection layer 42 under the second growth condition.
[0080] The second growth condition includes at least a second temperature and a second pressure, the second temperature is 950-1050°C, for example, 970°C, 990°C, 1010°C, 1030°C, the second pressure is 300-600torr, for example, 350torr, 400torr, 450torr, 500torr, 550torr, the thickness of each connecting layer 42 is 1-10nm, for example, 2nm, 4nm, 6nm, 8nm.
[0081] The connection layer 42 is, for example, a silicon nitride layer, into which SiH4 is introduced as a Si source and NH3 is introduced as a N source. In the thickness growth direction of the substrate 1 toward the nitride light-emitting layer 3, the Si atoms in the connection layer 42 diffuse to form a compensated electron concentration in the P-type nitride sublayer 43 of 1×10 17 cm -3 ~1×10 18 cm -3 , for example, 3×10 17 cm -3 , 5×10 17 cm -3 ,7×10 17 cm -3 ,9×10 17 cm -3 .
[0082] As a preferred mode, the flow ratio of the Si source and the N source gradually increases with the cyclic growth of the connection layer 42 and the P-type nitride sublayer 43. In the thickness growth direction from the substrate 1 to the nitride light-emitting layer 3, the atomic ratio of Si to N in each connection layer 42 can be changed by changing the flow ratio of SiH4 to NH3, and the thickness of each connection layer 42 can also be changed. The atomic ratio of Si to N in each connection layer 42 can also be controlled by changing the growth time of the connection layer 42, and the thickness of each connection layer 42 can also be changed.
[0083] As the thickness of the connection layer 42 increases or the atomic ratio of Si to N in the connection layer 42 increases, a Si diffusion electron supply layer is formed in the subsequent growth process of the P-type nitride composite layer 4. As the thickness of the connection layer 42 increases or the atomic ratio of Si to N in the connection layer 42 increases, the Si diffusion electron supply layer has a stronger ability and can provide more electrons to the subsequent P-type nitride composite layer 4. The flow ratio of the Si source and the N source is preferably: 1:100-1:5.
[0084] The flow ratio of SiH4 to NH3 is changed to control the ratio of Si to N atoms in each connecting layer 42. Specifically, when growing the connecting layer 42, the flow ratio of SiH4 to NH3 in the growth environment is greater than 0.01, and the flow ratio can be less than 0.2. In the direction from the substrate 1 to the nitride light-emitting layer 3, the ratio of the flow ratio of SiH4 to NH3 when growing the previous connecting layer 42 and the flow ratio of SiH4 to NH3 when growing the next adjacent connecting layer 42 is not less than 1:1.05. The growth time is 60s to 600s, for example, 100s, 200s, 300s, 400s, and 500s. In the cyclic alternation process, in the direction from the substrate 1 to the nitride light-emitting layer 3, the thickness of each connecting layer 42 increases successively.
[0085] Under the condition of a specific NH3 flow rate, the thickness of the connecting layer 42 is positively correlated with the SiH4 flow rate. By setting the SiH4 flow rate to increase in the direction from the substrate 1 to the nitride light-emitting layer 3, the thickness of the connecting layer 42 is increased. At the same time, the Si-rich process growth is guaranteed by setting the SiH4 and NH3 flow ratio, and the number of Si atoms in each connecting layer 42 is increased, thereby forming an increasing Si atom diffusion supply capacity in the direction from the substrate 1 to the nitride light-emitting layer 3. The P-type nitride composite layer 4 forms a carrier concentration gradient in the direction from the substrate 1 to the nitride light-emitting layer 3, thereby improving the uniformity of carrier injection, and improving the capacitance effect of the semiconductor epitaxial wafer, thereby improving the brightness and ESD performance of the semiconductor epitaxial wafer.
[0086] The growth time of the connection layer 42 is changed to control the ratio of Si to N atoms in each connection layer 42. Specifically, when growing the connection layer 42, the flow ratio of SiH4 to NH3 in the growth environment is greater than 0.01, and the growth time is 60s to 600s, for example, 100s, 200s, 300s, 400s, and 500s. The growth time of the previous connection layer 42 and the next adjacent connection layer 42 increases in sequence in the direction from the substrate 1 to the nitride light-emitting layer 3. In the cyclic alternation process, the thickness of each connection layer 42 increases in sequence in the direction from the substrate 1 to the nitride light-emitting layer 3.
[0087] Step S43: growing a P-type nitride sublayer 43 under the third growth condition.
[0088] The third growth condition at least includes a third temperature and a third pressure. The third temperature is 850-1000°C, for example, 880°C, 910°C, 940°C, 970°C. The third pressure is 100-400 torr, for example, 150 torr, 200 torr, 300 torr, 350 torr, 400 torr. The thickness of each P-type nitride sublayer 43 is 10-20 nm, for example, 12 nm, 14 nm, 16 nm, 18 nm. The hole concentration of the P-type nitride sublayer 43 is 1×10 17 cm -3 ~1×10 19 cm -3 , for example, 4×10 17 cm -3 , 8×10 17 cm -3 , 4×10 18 cm -3 , 8×10 18 cm -3 .
[0089] The P-type nitride sublayer 43 is, for example, P-type GaN, the Ga source used is TMG (trimethylgallium, C3H9Ga), the N source is NH3, and the Mg source is the dopant Cp2Mg. The N source flow rate is 5 to 100 slm, and the Mg source flow rate is 200 to 1000 sccm. In the thickness growth direction of the substrate 1 toward the nitride light-emitting layer 3, in the cyclic alternating process, the Mg source flow rate of the P-type nitride sublayer 43 is gradually increased, so that the hole concentration of the P-type nitride sublayer 43 is successively increased, and the increase rate of the Mg source flow rate is 5 to 20%.
[0090] Compared with the conventional Mg flow rate of 500-1500sccm, the present invention obtains an epitaxial wafer with excellent performance (brightness, leakage) through a process lower than the conventional process doping (Mg flow rate). For the change of Mg source flow rate, if the increase rate is less than 5%, the concentration difference is too small, the hole concentration gradient is not obvious, and the uniformity of carrier injection into the nitride light-emitting layer 3 is affected. If the increase rate is higher than 20%, the concentration gradient is too large, resulting in excessive stress, affecting the interface quality and crystal quality.
[0091] As a preferred method, the first growth condition at least includes: introducing Ga source, Mg source and N source, and after growing the P-type nitride seed layer 41 under the first growth condition, it also includes: turning off the Ga source and Mg source, maintaining the continuous introduction of N source for 10 to 30 seconds, and treating the surface of the P-type nitride seed layer 41.
[0092] And / or, after growing the P-type nitride sublayer 43 under the third growth condition, it also includes: turning off the Ga source and the Mg source, maintaining the continuous flow of the N source for 10 to 30 seconds, and treating the surface of the P-type nitride sublayer 43. The surface of each layer of the P-type nitride sublayer 43 may be treated, the surface of a certain layer of the P-type nitride sublayer 43 may be treated, or the surfaces of several layers of the P-type nitride sublayer 43 may be treated.
[0093] In the P-type nitride seed layer 41 and the P-type nitride sublayer 43, N vacancies have extremely low formation energy. The N vacancies acting as donor impurities offset and compensate for the hole concentration in the P-type nitride seed layer 41 and the P-type nitride sublayer 43. Donor doping atoms will gather and form at the N vacancies, which not only reduces the doping activation efficiency, but also reduces the leakage performance and luminescence brightness of the semiconductor epitaxial wafer. After the growth of the P-type nitride seed layer 41 and the P-type nitride sublayer 43 is completed, the nitrogen source is continuously introduced for 10 to 30 seconds to perform surface treatment on the P-type nitride seed layer 41 and the P-type nitride sublayer 43 to reduce N vacancies on the surface of the P-type nitride seed layer 41 and the P-type nitride sublayer 43. On the one hand, the N vacancies of the donor impurities are reduced to offset and compensate for the hole concentration in the P-type nitride seed layer 41 and the P-type nitride sublayer 43, and at the same time, the aggregation of P-type doped atoms in the P-type nitride seed layer 41 and the P-type nitride sublayer 43 at the N vacancies is reduced; on the other hand, the N source is pre-decomposed during the surface treatment process to ensure sufficient N bonds in the initial growth of the SiN connecting layer. When the Si source is introduced during the growth of the SiN connecting layer, it can avoid excessive Si atoms from accumulating on the surface of the P-type nitride sublayer 43 due to the low thermal decomposition efficiency of the N source, thereby improving the leakage performance and luminous brightness of the semiconductor epitaxial wafer.
[0094] As a preferred method, the first temperature is higher than the third temperature, and the first pressure is higher than the third pressure. When growing the P-type nitride seed layer 41, relatively high temperature and high pressure are conducive to reducing impurities such as C, H, and O in the seed layer during the growth of the P-type nitride seed layer 41, and providing a high-quality growth template. When growing the P-type nitride sublayer 43, relatively low temperature is conducive to reducing the time that the P-type nitride composite layer 4 is at the high growth temperature, reducing the interface damage to the nitride light-emitting layer 3 during the growth of the P-type nitride composite layer 4, and improving the brightness of the semiconductor epitaxial wafer. Relatively low pressure is conducive to the lateral growth of the P-type nitride sublayer 43 to fill the connecting layer 42 to obtain a flat and smooth epitaxial surface, and improve the excellent contact characteristics of the epitaxial surface.
[0095] The scheme of the present invention will be described in detail below in conjunction with embodiments, but those skilled in the art will understand that the following embodiments are only used to illustrate the present invention and should not be regarded as limiting the scope of the present invention.
[0096] In the following embodiments and comparative examples, the N-type nitride layer 2 is an N-type GaN layer, the nitride quantum well layer 31 is an InGaN quantum well layer, the nitride quantum barrier layer 32 is a GaN quantum barrier layer, the P-type nitride seed layer 41 is a P-type GaN seed layer, the P-type nitride sublayer 43 is a P-type GaN sublayer, the P-type nitride composite layer 4 is a P-type GaN composite layer, and the connecting layer 42 is a silicon nitride layer.
[0097] Example 1
[0098] The process of semiconductor epitaxial wafer includes the following steps.
[0099] 1) Provide a sapphire substrate 1.
[0100] 2) Under the conditions of temperature 1090°C and pressure 300 torr, an N-type GaN layer is grown on the sapphire substrate 1. The electron concentration of the N-type GaN layer is 5×10 18 cm -3 , the thickness of the N-type GaN layer is 5μm.
[0101] 3) On the N-type GaN layer, InGaN quantum well layers and GaN quantum barrier layers are stacked alternately from bottom to top, with the number of cycles being 10, to obtain a nitride light-emitting layer 3.
[0102] Under the conditions of temperature of 750° C. and pressure of 300 torr, an InGaN quantum well layer is grown on the N-type GaN layer, and the thickness of the InGaN quantum well layer is 4 nm.
[0103] Under the conditions of temperature 880° C. and pressure 300 torr, a GaN quantum barrier layer is grown on the InGaN quantum well layer, and the thickness of the GaN quantum barrier layer is 12 nm.
[0104] 4) On the nitride light-emitting layer 3, a P-type GaN seed layer and a silicon nitride layer and a P-type GaN sublayer are generated by cyclically alternating stacking from bottom to top. The steps S42 and S43 are cyclically alternating for 10 times to obtain a 160nm P-type GaN composite layer.
[0105] Step S41: Under the conditions of temperature 1000°C, pressure 300 torr, and Mg flow rate 500 sccm, a P-type GaN seed layer is grown on the nitride light-emitting layer 3. The hole concentration of the P-type GaN seed layer is 5×10 17 cm -3 , the thickness of the P-type GaN seed layer is 10 nm.
[0106] The Ga source and Mg source were turned off, and the N source was continuously introduced for 20 seconds to treat the surface of the P-type GaN seed layer.
[0107] Step S42: Under the conditions of temperature of 1000° C. and pressure of 400 torr, SiH 4 and NH 3 are introduced to grow a silicon nitride layer on the P-type GaN seed layer for 300 seconds.
[0108] Step S43: Under the conditions of temperature 900°C, pressure 200 torr, and Mg flow rate 150 sccm, a P-type GaN sublayer is grown on the silicon nitride layer. The hole concentration of the P-type GaN sublayer is 2×10 17 cm -3 , the thickness of the P-type GaN sublayer is 15nm.
[0109] The Ga source and Mg source were turned off, and the N source was continuously introduced for 20 seconds to treat the surface of the P-type GaN sublayer.
[0110] Among them, the initial SiH4 flow rate in step S42 is 200 sccm, and the NH3 flow rate is 20 slm. During the cyclic alternation process, the SiH4 flow rate is increased successively so that the SiH4 and NH3 flow ratios are 0.010, 0.011, 0.012, 0.013, 0.015, 0.016, 0.018, 0.020, 0.022, and 0.024 respectively.
[0111] The starting Mg flow rate in step S43 is 200 sccm, and the Mg flow rate is increased successively during the cyclic alternation process, so that the Mg flow rate is 200 sccm, 220 sccm, 242 sccm, 266 sccm, 293 sccm, 322 sccm, 354 sccm, 390 sccm, 429 sccm, and 472 sccm respectively.
[0112] Comparative Example 1
[0113] The process of the semiconductor epitaxial wafer of Comparative Example 1 is substantially the same as that of Example 1, except that:
[0114] When growing the P-type GaN composite layer, the SiH4:NH3 ratio in step S42 is fixed, and the flow rates of SiH4 and NH3 remain unchanged during the cyclic alternation process, with a SiH4 flow rate of 250 sccm and an NH3 flow rate of 20 slm, to obtain a 160 nm P-type GaN composite layer.
[0115] Comparative Example 2
[0116] The process of the semiconductor epitaxial wafer of Comparative Example 2 is substantially the same as that of Example 1, except that:
[0117] When growing the P-type GaN composite layer, no silicon nitride layer is provided, and a 160nm P-type GaN composite layer is obtained.
[0118] Comparative Example 3
[0119] The process of the semiconductor epitaxial wafer of Comparative Example 3 is substantially the same as that of Example 1, except that:
[0120] When growing the P-type GaN composite layer, only the P-type GaN seed layer is provided to obtain a 160nm P-type GaN seed layer.
[0121] Comparative Example 4
[0122] The process of the semiconductor epitaxial wafer of Comparative Example 4 is substantially the same as that of Example 1, except that:
[0123] When growing the P-type GaN composite layer, only the P-type GaN sublayer is provided to obtain a 160nm P-type GaN sublayer.
[0124] Comparative Example 5
[0125] The process of the semiconductor epitaxial wafer of Comparative Example 5 is substantially the same as that of Example 1, except that:
[0126] When growing a P-type GaN composite layer, the SiH4:NH3 ratio in step S42 is fixed, and the flow rates of SiH4 and NH3 remain unchanged during the cyclic alternation process. The SiH4 flow rate is 250ccm, and the NH3 flow rate is 20slm. The growth time of each silicon nitride layer increases successively to 100s, 150s, 200s, 250s, 300s, 350s, 400s, 450s, 500s, and 550s to obtain a 160nm P-type GaN composite layer.
[0127] Comparative Example 6
[0128] The process of the semiconductor epitaxial wafer of Comparative Example 6 is substantially the same as that of Example 1, except that:
[0129] When growing the P-type GaN composite layer, the SiH4:NH3 ratio in step S42 is less than 0.01, and the flow rates of SiH4 and NH3 remain unchanged during the cyclic alternation process, with a SiH4 flow rate of 10 sccm and a NH3 flow rate of 20 slm, to obtain a 160nm P-type GaN composite layer.
[0130] Comparative Example 7
[0131] The process of the semiconductor epitaxial wafer of Comparative Example 7 is substantially the same as that of Example 1, except that:
[0132] When growing the P-type GaN composite layer, the SiH4:NH3 ratio in step S42 is greater than 0.2, and the flow rates of SiH4 and NH3 remain unchanged during the cyclic alternation process, with a SiH4 flow rate of 200 sccm and an NH3 flow rate of 0.52 slm, to obtain a 160nm P-type GaN composite layer.
[0133] Comparative Example 8
[0134] The process of the semiconductor epitaxial wafer of Comparative Example 8 is substantially the same as that of Example 1, except that:
[0135] When growing the P-type GaN composite layer, the Mg flow rate in step S43 remains unchanged. During the cyclic alternation process, the Mg flow rate is 200 sccm, and a 160 nm P-type GaN composite layer is obtained.
[0136] Comparative Example 9
[0137] The process of the semiconductor epitaxial wafer of Comparative Example 9 is substantially the same as that of Example 1, except that:
[0138] When growing a P-type GaN composite layer, in step S41, the Ga source and the Mg source are not turned off, and the N source is kept flowing for 20 seconds to treat the surface of the long P-type GaN seed layer. In step S43, the Ga source and the Mg source are not turned off, and the N source is kept flowing for 20 seconds to treat the surface of the P-type GaN sublayer to obtain a 160nm P-type GaN composite layer.
[0139] Test results: Semiconductor epitaxial wafers were prepared by Example 1 and Comparative Examples 1 to 9, and the brightness, voltage, leakage performance and electrostatic discharge performance of the epitaxial wafers with the same luminous wavelength (450±0.5nm) were tested, see Table 1.
[0140] Table 1
[0141] Serial number Brightness / m W Voltage / V Leakage yield / % ESD yield / % Example 1 13.8 2.92 99 100 Comparative Example 1 13.1 2.94 99 98 Comparative Example 2 12.7 2.95 96 95 Comparative Example 3 12,1 2.97 95 94 Comparative Example 4 11.8 2.98 96 96 Comparative Example 5 13.3 2.93 99 98 Comparative Example 6 12.7 2.95 98 97 Comparative Example 7 12.1 2.95 91 89 Comparative Example 8 13.2 2.94 98 98 Comparative Example 9 13.2 2.94 98 97
[0142] in conclusion:
[0143] 1) Comparing Example 1 with Comparative Example 1, the brightness of Comparative Example 1 is reduced, the voltage is increased, and the ESD yield is reduced, which indicates that in Example 1, the flow ratio of SiH4 and NH3 is increased, and the electron supply capacity formed by the diffusion of Si atoms in the connecting layer 42 is successively enhanced, which matches the sequential increase in the carrier concentration in the P-type nitride sublayer 43. Therefore, the co-doping effect formed by Si as a donor and an acceptor impurity in each P-type nitride sublayer 43 is successively strengthened, thereby improving the acceptor doping activation efficiency. Therefore, in the thickness direction, the P-type nitride composite layer 4 forms a concentration gradient of hole concentration from low to high, thereby improving the lateral expansion of holes in the P-type nitride composite layer 4, and improving the hole injection in the P-type nitride composite layer 4. In addition, the increase in the flow ratio of SiH4 and NH3 improves the lateral epitaxial growth of the P-type nitride sublayer 43, and improves the crystal quality of the P-type nitride composite layer, thereby improving the luminous brightness of the semiconductor epitaxial wafer, and improving the leakage current and ESD yield performance.
[0144] 2) Comparison between Example 1 and Comparative Example 2 shows that the brightness of Comparative Example 2 is reduced, the voltage is increased, and the leakage and ESD yield are reduced. Although the Mg flow rate is increased in Comparative Example 2, the difference in hole concentration gradient can be achieved to a certain extent, but limited by the activation efficiency of Mg doping, the hole injection improvement of Comparative Example 2 for the P-type nitride sublayer 43 is not obvious, indicating that the electron supply capacity formed by the diffusion of Si atoms in the present invention is successively enhanced, which matches the carrier concentration in the P-type nitride sublayer 43. Therefore, each layer of P-type The co-doping effect formed by Si as a donor and acceptor impurity in the nitride sublayer 43 is successively strengthened, thereby improving the acceptor doping activation efficiency. Therefore, a concentration gradient of hole concentration from low to high is formed in the P-type nitride composite layer 4 in the thickness direction, thereby improving the lateral expansion of holes in the P-type nitride composite layer 4 and improving the hole injection in the P-type nitride composite layer 4. In addition, the setting of the SiN connecting layer in Example 1 improves the lateral epitaxial growth of the P-type nitride sublayer 43, improves the crystal quality of the P-type nitride composite layer, and improves the leakage and ESD yield performance.
[0145] 3) Comparing Example 1 with Comparative Examples 3 and 4, Comparative Examples 3 and 4 only grow the P-type layer of the conventional process structure, and the brightness of the semiconductor epitaxial wafer is reduced, the voltage is increased, and the leakage and ESD performances are all deteriorated, indicating that the electron supply capacity formed by the diffusion of Si atoms in the connecting layer 42 in Example 1 is successively enhanced, which matches the successively increased carrier concentration in the P-type nitride sublayer 43. Therefore, the co-doping effect formed by Si as a donor and an acceptor impurity in each P-type nitride sublayer 43 is successively strengthened, which improves the acceptor doping activation efficiency. Therefore, in the thickness direction, the P-type nitride composite layer 4 forms a concentration gradient of hole concentration from low to high, which improves the lateral expansion of holes in the P-type nitride composite layer 4, improves the hole injection in the P-type nitride composite layer 4, and the increase in the SiH4 and NH3 flow ratio improves the lateral epitaxial growth of the P-type nitride sublayer 43, improves the crystal quality of the P-type nitride composite layer, thereby improving the luminous brightness of the semiconductor epitaxial wafer and improving the leakage and ESD yield performance.
[0146] 4) Comparing Example 1 with Comparative Example 5, the brightness, voltage, leakage current and ESD performance of Comparative Example 5 are deteriorated to a certain extent compared with Example 1. The reason is that although increasing the time can also increase Si diffusion and improve the co-doping effect, the increase in time will to a certain extent destroy the interface performance of the nitride light-emitting layer 3, causing the components of the nitride light-emitting layer 3 to fluctuate. Therefore, Example 1 presents the best performance by adjusting the flow ratio.
[0147] 5) Comparing Example 1 with Comparative Examples 6 and 7, the flow ratio of SiH4 to NH3 in Comparative Example 6 is too low, and Si atoms cannot play a role in diffusion and lateral epitaxy. The flow ratio of SiH4 to NH3 in Comparative Example 7 is too high, and Si itself forms acceptor defects as an impurity atom and compensates for the holes in the P-type nitride sublayer 43. Therefore, the performance of the semiconductor epitaxial wafers in Comparative Examples 6 and 7 is reduced.
[0148] 6) Comparing Example 1 with Comparative Example 8, the Mg flow rate in Comparative Example 8 remains unchanged, and the brightness, voltage, leakage current and ESD performance of Comparative Example 8 are all deteriorated to a certain extent compared with Example 1, indicating that under the condition of the Mg flow rate in Comparative Example 8, after Si atoms diffuse into the P-type nitride sublayer 43, there is no matching Mg doping to match it, resulting in the acceptance activation efficiency being affected, indicating that the electron supply capacity formed by the diffusion of Si atoms in the connecting layer 42 in Example 1 is successively enhanced, which is matched with the sequential increase in the carrier concentration in the P-type nitride sublayer 43. Therefore, the co-doping effect formed by Si as a donor and an acceptor impurity in each P-type nitride sublayer 43 is successively strengthened, thereby improving the acceptor doping activation efficiency. Therefore, in the thickness direction, the P-type nitride composite layer 4 forms a concentration gradient of hole concentration from low to high, thereby improving the lateral expansion of holes in the P-type nitride composite layer 4, and improving the hole injection in the P-type nitride composite layer 4, thereby improving the luminous brightness of the semiconductor epitaxial wafer and improving the leakage current and ESD yield performance.
[0149] 7) Comparing Example 1 with Comparative Example 9, the brightness, voltage, leakage and ESD performance of Comparative Example 9 are all deteriorated to a certain extent compared with Example 1, which indicates that in the surface treatment process of Example 1, on the one hand, the N vacancies of the donor impurities are reduced to offset and compensate the hole concentration in the P-type nitride seed layer 41 and the P-type nitride sublayer 43, and at the same time, the aggregation of P-type doped atoms at N vacancies in the P-type nitride seed layer 41 and the P-type nitride sublayer 43 is reduced; on the other hand, the N source is pre-decomposed during the surface treatment process to ensure sufficient N bonds in the initial growth of the SiN connecting layer, and when the Si source is introduced during the growth of the SiN connecting layer, the excessive aggregation of Si atoms on the surface of the P-type nitride sublayer 43 caused by the low thermal decomposition efficiency of the N source can be avoided, thereby improving the leakage performance and luminous brightness of the semiconductor epitaxial wafer.
[0150] The semiconductor epitaxial wafer and the process method thereof of the present invention generate a P-type nitride composite layer 4 through a P-type nitride seed layer 41 and a connecting layer 42 and a P-type nitride sublayer 43 that are generated by cyclically alternating stacking from bottom to top. The connecting layer 42 can shield the surface defects of the P-type nitride seed layer 41, and also strengthen the lateral epitaxial growth of the P-type nitride sublayer 43, thereby improving the crystal quality of the semiconductor epitaxial wafer. The P-type nitride seed layer 41 blocks the Si atoms in the connecting layer 42 from diffusing into the nitride light-emitting layer 3, thereby improving the carrier radiation recombination efficiency and improving the leakage performance of the semiconductor epitaxial wafer. The thickness of each connecting layer 42 in the P-type nitride composite layer 4 increases in the direction from the substrate 1 to the nitride light-emitting layer 3, so that the electron supply capacity formed by the diffusion of Si atoms in each connecting layer 42 is successively enhanced, which matches the sequential increase in the carrier concentration in the P-type nitride sublayer 43. Therefore, the co-doping effect formed by Si as a donor and acceptor impurity in each P-type nitride sublayer 43 is successively strengthened, which improves the acceptor doping activation efficiency. Therefore, in the thickness direction, the P-type nitride composite layer 4 forms a concentration gradient of hole concentration from low to high, which improves the P-type nitride The holes in the P-type nitride composite layer 4 expand laterally, which improves the hole injection in the P-type nitride composite layer 4 and the carrier injection uniformity in the nitride light-emitting layer 3, thereby improving the luminescence brightness of the semiconductor epitaxial wafer. In addition, in the direction of the substrate 1 toward the nitride light-emitting layer 3, the high acceptor activation efficiency of the P-type nitride composite layer 4 makes it unnecessary to use excessive doping in the P-type nitride sublayer 43 to increase the hole concentration, thereby avoiding the leakage problem caused by the introduction of defects caused by high doping, improving the comprehensive yield of the semiconductor epitaxial wafer, and reducing the growth cost of the semiconductor epitaxial wafer.
[0151] Although the embodiments of the present invention have been shown and described above, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. A person skilled in the art may change, modify, substitute and modify the above embodiments within the scope of the invention without departing from the principles and purpose of the present invention. All such changes should fall within the scope of protection of the claims of the present invention.
Claims
1. A semiconductor epitaxial wafer, comprising a substrate, an N-type nitride layer, a nitride light-emitting layer and a P-type nitride composite layer located on the substrate, characterized in that: The P-type nitride composite layer includes a P-type nitride seed layer and a connection layer and a P-type nitride sublayer generated by cyclic alternating stacking; Among them, the majority carriers of the P-type nitride sublayer are holes, and the connecting layer introduces Si atoms to diffuse into the P-type nitride sublayer. After the Si atoms diffuse, co-doping is formed in the P-type nitride sublayer to improve the activation efficiency of the doping in the P-type nitride sublayer.
2. A semiconductor epitaxial wafer as claimed in claim 1, characterized in that: During the cyclic alternation process, in the direction from the substrate to the nitride light-emitting layer, the thickness of each connecting layer in the P-type nitride composite layer increases successively.
3. A semiconductor epitaxial wafer as claimed in claim 1, characterized in that: The connecting layer is a silicon nitride layer, and the atomic ratio of Si to N in the connecting layer is greater than 1; Preferably, the connecting layer has a nanoporous layered structure, and the size of the nanoporous layered structure of the connecting layer is 5-150 nm.
4. A semiconductor epitaxial wafer as claimed in claim 1, characterized in that: The thickness of the connection layer and the P-type nitride sublayer after cyclic alternation is 50 to 200 nm; The thickness of the P-type nitride seed layer is 5-15 nm; The thickness of each connecting layer is 1 to 10 nm; The thickness of each P-type nitride sublayer is 10-20 nm.
5. A semiconductor epitaxial wafer as claimed in claim 1, characterized in that: The hole concentration of the P-type nitride sublayer increases sequentially; Preferably, the hole concentration of the P-type nitride seed layer is 1×10 17 cm -3 ~1×10 19 cm -3 , the electron compensation concentration of the connecting layer is 1×10 17 cm -3 ~1×10 18 cm -3 , the hole concentration of the P-type nitride sublayer is 1×10 17 cm -3 ~1×10 19 cm -3 ; The electron compensation concentration of the connecting layer is the compensated electron concentration in the P-type nitride sublayer caused by the diffusion of Si atoms in the connecting layer in the thickness growth direction of the substrate toward the nitride light-emitting layer.
6. A process for producing a semiconductor epitaxial wafer, characterized in that: An N-type nitride layer, a nitride light-emitting layer and a P-type nitride composite layer are sequentially grown on a substrate; the P-type nitride composite layer comprises a P-type nitride seed layer and a connection layer and a P-type nitride sublayer generated by cyclic alternating stacking; The process of the P-type nitride composite layer comprises: Under a first growth condition, growing the P-type nitride seed layer; Under the second growth condition, growing the connection layer; Under a third growth condition, growing the P-type nitride sublayer; Among them, the majority carriers of the P-type nitride sublayer are holes, and the connecting layer introduces Si atoms to diffuse into the P-type nitride sublayer. After the Si atoms diffuse, co-doping is formed in the P-type nitride sublayer to improve the activation efficiency of the doping in the P-type nitride sublayer.
7. A process for producing a semiconductor epitaxial wafer as claimed in claim 6, characterized in that: The first growth condition includes at least a first temperature and a first pressure; the second growth condition includes at least a second temperature and a second pressure; the third growth condition includes at least a third temperature and a third pressure; Wherein, the first temperature is higher than the third temperature, and the first pressure is higher than the third pressure; Preferably, the first temperature is 900-1200° C., and the first pressure is 100-600 torr; The second temperature is 950-1050°C, and the second pressure is 300-600 torr; The third temperature is 850-1000° C., and the third pressure is 100-400 torr.
8. A process for producing a semiconductor epitaxial wafer as claimed in claim 6, characterized in that: The connecting layer is a silicon nitride layer; The second growth condition at least includes: introducing SiH4 as a Si source and NH3 as a N source; in the thickness growth direction from the substrate to the nitride light-emitting layer, the concentration of compensated electrons in the P-type nitride sublayer caused by the diffusion of Si atoms in the connecting layer is 1×10 17 cm -3 ~1×10 18 cm -3 ; The third growth condition at least includes: introducing a Ga source, a Mg source and a N source, wherein the N source flow rate is 5 to 100 slm, and the Mg source flow rate is 200 to 1000 sccm; wherein, during the cyclic alternation process, the Mg source flow rate of growing the P-type nitride sublayer is gradually increased, so that the hole concentration of the P-type nitride sublayer is sequentially increased; Preferably, the increase rate of the Mg source flow rate is 5-20%.
9. A process for producing a semiconductor epitaxial wafer as claimed in claim 8, characterized in that: The flow ratio of the Si source to the N source gradually increases as the connection layer and the P-type nitride sublayer grow cyclically; And / or, the flow ratio of the Si source to the N source is: 1:100-1:
5.
10. A process for producing a semiconductor epitaxial wafer as claimed in claim 8, characterized in that: After growing the P-type nitride sublayer under the third growth condition, the method further includes: Turning off the Ga source and the Mg source, and maintaining the N source to flow continuously for 10 to 30 seconds to treat the surface of the P-type nitride sublayer; And / or, the first growth condition at least includes: introducing Ga source, Mg source and N source, and after growing the P-type nitride seed layer under the first growth condition, it also includes: turning off the Ga source and the Mg source, maintaining the continuous introduction of the N source for 10 to 30 seconds, and treating the surface of the P-type nitride seed layer.