Preparation method for UVC epitaxial wafer structure having different indicator colors

Abstract

A preparation method for a UVC epitaxial wafer structure having different indicator colors. The preparation method comprises the following steps: using an MOCVD device to prepare AlN on the surface of a sapphire planar substrate, so as to grow an aluminum nitride buffer layer; continuing to grow a 3D layer on the surface of the aluminum nitride buffer layer; continuing to grow a high-temperature aluminum nitride layer on the surface of the 3D layer, so as to prepare an aluminum nitride template having air gaps; growing an electron supply layer on the surface of the aluminum nitride template; growing a multi-quantum well active layer on the surface of the electron supply layer; and growing a hole supply layer on the surface of the multi-quantum well active layer. In the present invention, by controlling the height of air gaps in an aluminum nitride template, the crystalline quality of the template is controlled, and the defect-related luminescence of an aluminum gallium nitride epitaxial layer is then controlled, thereby enabling an epitaxial wafer to exhibit a specific emission color while ensuring emission color consistency across different furnace runs and within the same epitaxial wafer. In the present invention, the emission colors of epitaxial wafers can be determined by means of the height of cross-sectional air gaps, and the epitaxial wafers are classified and distinguished on the basis of the emission colors.

Description

Preparation method of UVC epitaxial wafer structure with different indicating colors TECHNICAL FIELD

[0001] The present application belongs to the technical field of LED epitaxial wafer preparation, and particularly relates to a preparation method of a UVC epitaxial wafer structure with different indicating colors. BACKGROUND

[0002] The aluminum nitride template is a base material for epitaxial growth of aluminum gallium nitride-based deep ultraviolet LEDs, and the crystalline quality of the template directly determines the crystalline quality of the upper layer of aluminum gallium nitride. A high-quality aluminum nitride template can effectively reduce the threading dislocation density (TDDs) of aluminum gallium nitride, improve the radiative recombination efficiency of electrons and holes in the LED structure grown based on the material, and improve the reliability and service life of the LED.

[0003] The aluminum gallium nitride material is grown on the surface of the aluminum nitride template. There is a certain mismatch between aluminum nitride and aluminum gallium nitride, which is determined by the aluminum component. The lattice mismatch between stress-free aluminum nitride and gallium nitride is 2.43%. The lattice mismatch between aluminum nitride and aluminum gallium nitride is linearly related to the aluminum component. The lower the aluminum component, the greater the lattice mismatch between aluminum gallium nitride and aluminum nitride. The increase in lattice mismatch leads to an increase in the number of hill-shaped patterns of aluminum gallium nitride, poor crystal quality, and defect luminescence.

[0004] Due to the change of the chamber environment from one furnace to another, the repeated growth of the UVC LED epitaxial wafer by MOCVD will cause changes in the growth conditions of the bottom layer of the epitaxial layer, thereby affecting the density, height, and proportion of Al polarity of the nucleation layer, and further affecting the stress state and surface morphology of the epitaxial layer. This will cause differences in defect luminescence between different batches of epitaxial wafers, and even different regions of the same epitaxial wafer will emit different colors of visible light, thereby causing color differences in a large batch of prepared chips.

[0005] Since the visible light emitted by the UVC LED chip is defect luminescence, the intensity is very weak and cannot be classified and screened by using a chip point testing machine, which will cause different luminescence colors to exist in the shipped chips. SUMMARY

[0006] In view of the above technical problems of the UVC LED epitaxial wafer, the present application provides a preparation method of a UVC epitaxial wafer structure with different indicating colors.

[0007] To solve the above technical problems, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of a UVC epitaxial wafer structure with different indicating colors, comprising the following steps:

[0009] S1, using MOCVD equipment to prepare AlN with a thickness of 800nm-5000nm on the surface of a 2-inch sapphire flat substrate, to obtain an aluminum nitride template with air gaps;

[0010] S1.1, growing an aluminum nitride buffer layer with a thickness of 10nm-20nm;

[0011] S1.2, continuing to grow a 3D layer of 250nm-600nm on the surface of the aluminum nitride buffer layer;

[0012] S1.3, continuing to grow a high-temperature aluminum nitride layer with a thickness of 540nm-4380nm on the surface of the 3D layer, to obtain an aluminum nitride template with air gaps with a height of 300nm-650nm in cross section;

[0013] S2, placing the aluminum nitride template with air gaps into MOCVD to grow a structure layer;

[0014] S2.1, growing an electron supply layer of 1um-3.5um on the surface of the aluminum nitride template;

[0015] S2.2, growing a multi-quantum well active layer on the surface of the electron supply layer;

[0016] S2.3, growing a hole supply layer on the surface of the multi-quantum well active layer.

[0017] The height of the air gap and the emission color of the UVC epitaxial wafer have a corresponding relationship: when the height of the air gap is 300nm-400nm, the perceived color is blue, and the surface is a uniform hill shape without large hexagonal protrusions; when the height of the air gap is 400nm-650nm, the perceived color is purple, and the surface has hexagonal protrusions, and the number of protrusions is greater than 50.

[0018] The UVC epitaxial wafer has three emission peaks and can exhibit different indicator colors, with emission peaks at deep ultraviolet band 250nm-280nm, visible violet band 400nm-420nm, and yellow band 530nm-550nm.

[0019] The growth process of the 10nm-20nm thick aluminum nitride buffer layer in S1.1 is as follows: the growth temperature is 700℃-1000℃, the pressure is 30torr-60torr, the NH3 flow rate is 100sccm-2000sccm, the H2 flow rate is 10SLM-30SLM, the TMAl flow rate is 100umol / min-200umol / min, and the growth time is 2min-4min.

[0020] The growth process in S1.2 for growing a 3D layer of 250nm to 600nm on the aluminum nitride buffer surface is as follows: growth temperature is 1000℃ to 1100℃, pressure is 30 torr to 60 torr, NH3 flow rate is 2SLM to 10SLM, H2 flow rate is 10SLM to 30SLM, TMA1 flow rate is 200umol / min to 300umol / min, and growth time is 10min to 40min.

[0021] The growth process in S1.3 for continuing to grow a high-temperature aluminum nitride layer with a thickness of 540nm to 4380nm on the surface of the 3D layer is as follows: growth temperature is 1130℃ to 1300℃, pressure is 30 torr to 60 torr, NH3 flow rate is 50 sccm to 1000 sccm, H2 flow rate is 10 slm to 30 slm, TMA1 flow rate is 100 μmol / min to 300 μmol / min, and growth time is 50 min to 240 min.

[0022] The growth process for the 1µm to 3.5µm electron supply layer in S2.1 is as follows: growth temperature of 1020℃ to 1080℃, pressure of 80 torr to 100 torr, TMAl flow rate of 280µmol / min to 320µmol / min, TMGa flow rate of 172.3µmol / min to 229µmol / min, NH3 flow rate of 2000sccm to 4000sccm, and SiH4 flow rate of 2.8 × 10⁻⁶. -8 mol / min~5.6×10 -8 The growth rate was mol / min, the carrier gas was pure H2, the H2 flow rate was 30 L / min to 80 L / min, the thickness was 1000 nm to 3500 nm, and the growth time was 75 min to 263 min.

[0023] The Al composition of the AlGaN in the electron supply layer is 55%–65%, and the Si doping concentration of the electron supply layer is 1.3 × 10⁻⁶. 19 cm -3 ~2.6×10 19 cm -3 The hole supply layer is made of AlGaN with a thickness of 10–40 nm. The Al composition gradually changes from 80% to 20%, and the Mg doping concentration changes from 5e⁻¹ to 10%. 18 cm -3 ~8e 18 cm -3 Gradually becomes 1e 21 cm -3 ~3e 21 cm -3The period number of the multi-quantum well active layer is 1 pair to 10 pairs, the barrier layer Al component of the multi-quantum well active layer is 0.6 to 0.65, and the thickness is 10nm to 12nm, the well layer Al component of the multi-quantum well active layer is 0.49 to 0.54, and the thickness is 1.7nm to 3nm.

[0024] The growth process of the hole supply layer in S2.3 is as follows: the growth temperature is 900 DEG C to 1000 DEG C, the pressure is 100torr to 250torr, the TMAl flow rate is gradually changed from 210umol / min to 52.5umol / min, the TMGa flow rate is gradually changed from 52.5umol / min to 210umol / min, the NH3 flow rate is 4000sccm to 6000sccm, the Cp2Mg flow rate is gradually changed from 100sccm to 900sccm, the pure H2 carrier gas, the H2 flow rate is 40L / min to 60L / min, the thickness is 8nm to 15nm, and the growth time is 110s to 440s.

[0025] A UVC epitaxial wafer structure with different indicating colors comprises an aluminum nitride template, an electron supply layer, a multi-quantum well active layer and a hole supply layer, the electron supply layer is arranged on the aluminum nitride template, the multi-quantum well active layer is arranged on the electron supply layer, the hole supply layer is arranged on the multi-quantum well active layer, and the aluminum nitride template is internally provided with an air gap.

[0026] Compared with the prior art, the present application has the beneficial effects that:

[0027] By controlling the height of the air gap in the aluminum nitride template, the crystallization quality of the template is controlled, and then the defect luminescence of the aluminum gallium nitride epitaxial layer is controlled, so that the epitaxial wafer presents a specific luminescence color, and the luminescence colors of different furnace batches and the same epitaxial wafer are ensured to be consistent. The height of the cross-section air gap can be used to judge the luminescence color of the epitaxial wafer, and the epitaxial wafer is classified and distinguished according to the luminescence color. BRIEF DESCRIPTION OF DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description are only exemplary, and those skilled in the art can also obtain other implementation drawings according to the provided drawings without creating any creative labor.

[0029] The structures, proportions, sizes, etc. shown in the specification are merely used to cooperate with the content disclosed in the specification for the understanding and reading of those skilled in the art, and are not used to limit the conditions that can be implemented by the application, so they do not have technical significance. Any modification of the structure, change of the proportion relationship or adjustment of the size, which does not affect the effects and purposes that can be achieved by the application, should still fall within the scope of the technology disclosed by the application.

[0030] Fig. 1 is a structural schematic diagram of the application;

[0031] Fig. 2 is a cross-sectional SEM diagram of embodiment one of the application;

[0032] Fig. 3 is a surface OM diagram of embodiment one of the application;

[0033] Fig. 4 is a cross-sectional SEM diagram of embodiment two of the application;

[0034] Fig. 5 is a surface OM diagram of embodiment two of the application;

[0035] Fig. 6 is an EL diagram of embodiment one and embodiment two of the application.

[0036] Wherein: 1 is an aluminum nitride template, 2 is an electron supply layer, 3 is a multi-quantum well active layer, and 4 is a hole supply layer. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical scheme and advantages of the embodiments of the application more clear, the technical scheme in the embodiments of the application will be described clearly and completely below. Obviously, the described embodiments are only some of the embodiments of the application, but not all the embodiments. These descriptions are only for further illustrating the features and advantages of the application, but not for limiting the claims of the application. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the application.

[0038] The specific embodiments of the application will be further described in detail below in combination with the drawings and embodiments. The following embodiments are used to illustrate the application, but not to limit the scope of the application.

[0039] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integral connection; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0040] A preparation method of a UVC epitaxial wafer structure with different indicating colors, comprising the following steps:

[0041] Step one, growing a 10-20 nm thick aluminum nitride buffer layer on the surface of a 2-inch sapphire flat substrate using a MOCVD device, the growth process being: a temperature of 700-1000℃, a pressure of 30-60 torr, an NH3 flow rate of 100-2000 sccm, an H2 flow rate of 10-30 SLM, a TMAl flow rate of 100-200 umol / min, and a growth time of 2-4 min.

[0042] Step two, continuing to grow a 250-600 nm 3D layer on the surface of the aluminum nitride buffer layer, the growth process being: a temperature of 1000-1100℃, a pressure of 30-60 torr, an NH3 flow rate of 2-10 SLM, an H2 flow rate of 10-30 SLM, a TMAl flow rate of 200-300 umol / min, and a growth time of 10-40 min.

[0043] Step three, continuing to grow a high-temperature aluminum nitride layer with a thickness of 540-4380 nm on the surface of the 3D layer, the growth process being: a temperature of 1130-1300℃, a pressure of 30-60 torr, an NH3 flow rate of 50-1000 sccm, an H2 flow rate of 10-30 SLM, a TMAl flow rate of 100-300 umol / min, and a growth time of 50-240 min, thereby preparing an aluminum nitride template 1 with air gaps.

[0044] Step four, growing an electron supply layer 2 of 1-3.5 um on the aluminum nitride template with air gaps, the Al component of the electron supply layer 2 being 55-65%, and the Si doping concentration being 1.3×10 19 -2.6×10 19 cm -3 , the specific growth process of this stage being: a growth temperature of 1020-1080℃, a pressure of 80-100 torr, a TMAl flow rate of 280-320 umol / min, a TMGa flow rate of 229-172.3 umol / min, an NH3 flow rate of 2000-4000 sccm (89.3-179 mmol / min), and a SiH4 flow rate of 2.8×10 -8 -5.6×10 -8The growth rate was mol / min, the carrier gas was pure H2, the H2 flow rate was 30 L / min to 80 L / min, the thickness was 1000 nm to 3500 nm, and the growth time was 75 min to 263 min.

[0045] Step 5: Grow a multi-quantum-well active layer 3 on the electron supply layer 2, with a period number of 1 to 10 pairs, an Al composition of 0.6 to 0.65 for the barrier layer and a thickness of 10 nm to 12 nm, and an Al composition of 0.49 to 0.54 for the well layer and a thickness of 1.7 nm to 3 nm.

[0046] Step 6: Grow a hole supply layer 4 on the multi-quantum-well active layer 3. The material is AlGaN, with a thickness of 10–40 nm. The Al composition gradually changes from 80% to 20%, and the Mg doping concentration changes from 5e⁻¹ to 10%. 18 cm -3 ~8e 18 cm -3 Gradually becomes 1e 21 cm -3 ~3e 21 cm -3 The specific growth process in this stage is as follows: growth temperature is 900℃~1000℃, pressure is 100torr~250torr, TMAl flow rate gradually changes from 210umol / min to 52.5umol / min, TMGa flow rate gradually changes from 52.5umol / min to 210umol / min, NH3 flow rate is 4000sccm~6000sccm (179mmol / min~268mmol / min), Cp2Mg flow rate gradually changes from 100sccm to 900sccm (5.35mmol / min to 48.3mmol / min), pure H2 carrier gas is used, H2 flow rate is 40L / min~60L / min, thickness is 8nm~15nm, and growth time is 110s~440s.

[0047] A UVC epitaxial wafer structure with different indicator colors, as shown in Figure 1, includes an aluminum nitride template 1, an electron supply layer 2, a multi-quantum well active layer 3, and a hole supply layer 4. The electron supply layer 2 is grown on the aluminum nitride template 1, the multi-quantum well active layer 3 is grown on the electron supply layer 2, and the hole supply layer 4 is grown on the multi-quantum well active layer 3. An air gap exists inside the aluminum nitride template 1. By controlling the height of the air gap through the growth process of the aluminum nitride template, the morphology of the aluminum gallium nitride surface and the intensity of defect luminescence are affected, thus influencing the mixed color after defect luminescence in the epitaxial layer structure, ensuring stable and consistent product quality.

[0048] Example 1

[0049] As shown in Figure 2, the 3D layer growth thickness is 350nm-400nm, and the SEM observation of the growth structure shows that there is a certain density of air gap in the cross section of the epitaxial wafer, the height of the bottom end of the air gap from the sapphire substrate interface is 357nm-373nm; the surface is uniform hill morphology, without larger hexagonal protrusions, as shown in Figure 3; the positive and negative electrodes are prepared using indium balls on the surface of the epitaxial wafer structure, and the light emission color is blue after the direct current power is turned on.

[0050] Example two

[0051] As shown in Figure 4, the 3D layer growth thickness is 400nm-500nm, and the SEM observation of the growth structure shows that there is a certain density of air gap in the cross section of the epitaxial wafer, the height of the bottom end of the air gap from the sapphire substrate interface is 404nm-508nm; the surface has more hexagonal protrusions, the number of protrusions is greater than 50 (50 times field of view), as shown in Figure 5; the positive and negative electrodes are prepared using indium balls on the surface of the epitaxial wafer structure, and the light emission color is purple after the direct current power is turned on.

[0052] The integral sphere is used to test the light emission spectrum of the epitaxial wafer structure of two different light emission colors (visible light color is different), and the results are shown in Figure 6, there are three peaks, one 270nm-275nm UVC light emission peak, one 410nm purple light peak, and one 540nm yellow light peak, the yellow light peak is high, and the mixed color of the purple color is blue, the weak yellow light peak and the mixed color of the purple color is purple.

[0053] By controlling the growth process of the AlN template, the defect light emission peak of the UVC LED can be changed, thereby affecting the sensory color, which can be used as an indicator color to distinguish products, and does not affect the intensity of the UVC light emission peak. By using a microscope to quickly screen the epitaxial wafer structure morphology, the light emission color of the epitaxial wafer structure can be quickly distinguished, thereby classifying the products, and ensuring that there is no color difference phenomenon in the same batch of products.

[0054] The above only details the preferred embodiments of the present application, but the present application is not limited to the above embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application, and all changes shall be included in the protection scope of the present application.

Claims

1. A method for preparing a UVC epitaxial wafer structure with different indicator colors, characterized in that, The method comprises the following steps: S1, using MOCVD equipment to prepare AlN with a thickness of 800nm-5000nm on the surface of a 2-inch sapphire flat substrate, to obtain an aluminum nitride template (1) with air gaps; S1.1, growing an aluminum nitride buffer layer with a thickness of 10nm-20nm; S1.2, continuing to grow a 3D layer with a thickness of 250nm-600nm on the surface of the aluminum nitride buffer layer; S1.3, continuing to grow a high-temperature aluminum nitride layer with a thickness of 540nm-4380nm on the surface of the 3D layer, to obtain an aluminum nitride template (1) with air gaps with a height of 300nm-650nm in cross section; S2, placing the aluminum nitride template with air gaps into MOCVD to grow a structure layer; S2.1, growing an electron supply layer (2) with a thickness of 1um-3.5um on the surface of the aluminum nitride template (1); S2.2, growing a multi-quantum well active layer (3) on the surface of the electron supply layer (2); S2.3, growing a hole supply layer (4) on the surface of the multi-quantum well active layer (3).

2. The method of claim 1, wherein the UVC epitaxial wafer structure with different indicating colors is prepared by the steps of: The height of the air gap and the light-emitting color of the UVC epitaxial wafer have a corresponding relationship: when the height of the air gap is 300nm-400nm, the sensory color is blue, and the surface is a uniform hill shape without large hexagonal protrusions; when the height of the air gap is 400nm-650nm, the sensory color is purple, and the surface has hexagonal protrusions, and the number of protrusions is greater than 50. ​ 3. The method of claim 2, wherein the UVC epitaxial wafer structure has different indicator colors. The UVC epitaxial wafer has three light-emitting peaks and can exhibit different indication colors, and the light-emitting peaks are respectively a deep ultraviolet band of 250nm-280nm, a visible violet light band of 400nm-420nm, and a yellow light band of 530nm-550nm.

4. The method of claim 1, wherein the UVC epitaxial wafer structure with different indicating colors is prepared by the steps of: providing a UVC epitaxial wafer structure; and forming a plurality of indicating colors on the UVC epitaxial wafer structure. The growth process of the 10nm-20nm-thick aluminum nitride buffer layer in S1.1 is as follows: the growth temperature is 700℃-1000℃, the pressure is 30torr-60torr, the NH3 flow rate is 100sccm-2000sccm, the H2 flow rate is 10SLM-30SLM, the TMAl flow rate is 100umol / min-200umol / min, and the growth time is 2min-4min.

5. The method of claim 1, wherein the UVC epitaxial wafer structure with different indicating colors is prepared by the steps of: providing a UVC epitaxial wafer structure; and forming a plurality of indicating colors on the UVC epitaxial wafer structure. The growth process of the 250nm-600nm 3D layer on the surface of the aluminum nitride buffer layer in S1.2 is as follows: the growth temperature is 1000℃-1100℃, the pressure is 30torr-60torr, the NH3 flow rate is 2SLM-10SLM, the H2 flow rate is 10SLM-30SLM, the TMAl flow rate is 200umol / min-300umol / min, and the growth time is 10min-40min.

6. The method of claim 1, wherein the UVC epitaxial wafer structure with different indicating colors is prepared by the steps of: The growth process of the high-temperature aluminum nitride layer with a thickness of 540nm-4380nm on the 3D layer surface in S1.3 is as follows: the growth temperature is 1130-1300℃, the pressure is 30-60torr, the NH3 flow rate is 50-1000sccm, the H2 flow rate is 10-30SLM, the TMAl flow rate is 100-300umol / min, and the growth time is 50-240min. ​ 7. The method of claim 1, wherein the UVC epitaxial wafer structure with different indicating colors is prepared by the steps of: The growth process of the electronic supply layer (2) with a thickness of 1 um-3.5 um in S2.1 is as follows: the growth temperature is 1020-1080 °C, the pressure is 80-100 torr, the TMAl flow rate is 280-320 umol / min, the TMGa flow rate is 172.3-229 umol / min, the NH3 flow rate is 2000-4000 sccm, the SiH4 flow rate is 2.8-5.6 x 10 -8 mol / min, the carrier gas is pure H2, the H2 flow rate is 30-80 L / min, the thickness is 1000-3500 nm, and the growth time is 75-263 min. -8 ​ ​ 8. The method of claim 1, wherein the UVC epitaxial wafer structure having different indicator colors is prepared by the steps of: The Al composition of the AlGaN in the electron supply layer (2) is 55%–65%, and the Si doping concentration of the electron supply layer is 1.3 × 10⁻⁶. 19 cm -3 ~2.6×10 19 cm -3 The hole supply layer is made of AlGaN with a thickness of 10 nm to 40 nm. The Al composition gradually changes from 80% to 20%, and the Mg doping concentration changes from 5e... 18 cm -3 ~8e 18 cm -3 Gradually becomes 1e 21 cm -3 ~3e 21 cm -3 The number of periods of the multi-quantum well active layer (3) is 1 to 10 pairs, the Al composition of the barrier layer of the multi-quantum well active layer is 0.6 to 0.65, the thickness is 10 nm to 12 nm, the Al composition of the well layer of the multi-quantum well active layer is 0.49 to 0.54, and the thickness is 1.7 nm to 3 nm. ​ 9. The method of claim 1, wherein the UVC epitaxial wafer structure having different indicator colors is prepared by the steps of: The growth process of the hole supply layer (4) in S2.3 is as follows: the growth temperature is 900-1000℃, the pressure is 100-250torr, the TMAl flow rate gradually changes from 210umol / min to 52.5umol / min, the TMGa flow rate gradually changes from 52.5umol / min to 210umol / min, the NH3 flow rate is 4000-6000sccm, the Cp2Mg flow rate gradually changes from 100sccm to 900sccm, the pure H2 carrier gas has a flow rate of 40-60L / min, the thickness is 8-15nm, and the growth time is 110-440s. ​ 10. A UVC epitaxial wafer structure having different indicated colors, prepared according to the method of any one of claims 1-9, characterized by: The device comprises an aluminum nitride template (1), an electron supply layer (2), a multi-quantum well active layer (3), and a hole supply layer (4), the electron supply layer (2) is arranged on the aluminum nitride template (1), the multi-quantum well active layer (3) is arranged on the electron supply layer (2), and the hole supply layer (4) is arranged on the multi-quantum well active layer (3), and the aluminum nitride template (1) is internally provided with an air gap.

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