MOCVD (Metal Organic Chemical Vapor Deposition) card slot and application thereof in preparing GaN / AlGaN heterojunction

Abstract

The invention discloses an MOCVD (Metal Organic Chemical Vapor Deposition) card slot and an application thereof in preparing a GaN / AlGaN heterojunction, and belongs to the technical field of electronic materials. Introduction and distribution of stress are controlled through the MOCVD growth clamping groove, materials with different thermal expansion coefficients are selected as composition materials of the clamping groove base, thermal expansion of different degrees is generated through the thermal expansion difference of the materials, the growth substrate is made to present different warping states in the growth process, controllable stress is obtained, and therefore the thermal expansion performance of the substrate is improved. And therefore, the GaN / AlGaN heterojunction with high hole mobility can be obtained.

Description

Technical Field

[0001] This invention relates to the field of electronic materials, and more specifically to an MOCVD card slot and its application in the preparation of GaN / AlGaN heterojunctions. Background Technology

[0002] Compared to Si, a material used in traditional electronic power devices, group III nitride semiconductors possess superior properties such as a large bandgap, high breakdown electric field strength, high saturated electron mobility, high thermal conductivity, low dielectric constant, and strong radiation resistance. Furthermore, the polarization-induced carrier density in gallium nitride is independent of temperature. Therefore, GaN is considered a promising candidate material for power integrated circuits used in harsh environments.

[0003] In the past two years, GaN-based complementary logic circuits have been researched and proven, and monolithic GaN CL gates with truly "CMOS-like" behavior have been obtained. GaN-based complementary logic integrated circuits are currently in their early stages, and further optimization of device performance is needed. Carrier concentration and mobility need to be improved, especially the low channel mobility and high on-resistance of current GaN-based p-channel field-effect transistors. On the one hand, Mg impurities in GaN have high ionization energy and low hole concentration; on the other hand, the large effective hole mass greatly limits hole mobility. First-principles calculations show that introducing biaxial tensile strain into GaN can raise the spin-orbit coupling splitting band to above the light hole band and heavy hole band. This effect changes the order of the valence band top and the characteristics of the wavefunction, which can significantly reduce the effective hole mass and thus improve the hole mobility of GaN.

[0004] Currently, common methods for introducing the desired stress distribution into GaN during MOCVD growth involve using a substrate with a high lattice constant and changing the barrier layer material. However, due to lattice mismatch, the crystal growth quality can degrade. Furthermore, existing stress introduction methods are unstable, easily leading to film quality degradation, and stress introduction is difficult.

[0005] Therefore, providing an MOCVD growth slot capable of controlling the introduction and distribution of force, and using it to prepare GaN / AlGaN heterojunctions, is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0006] In view of this, the invention proposes an MOCVD growth slot to control the introduction and distribution of stress. By selecting materials with different coefficients of thermal expansion as the constituent materials of the slot base, the thermal expansion difference of the materials is used to generate different degrees of thermal expansion, so that the growth substrate exhibits different warping states during the growth process, thereby obtaining controllable stress and thus obtaining a GaN / AlGaN heterojunction with high hole mobility.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An MOCVD card slot includes a card slot base, a growth substrate, and a cover plate; The growth substrate is positioned directly above the card slot base; the cover plate is hollow and is fixed directly above the growth substrate. The card slot base includes a first base and a second base; the second base is embedded in the first base; The first base and the second base are made of different materials.

[0008] This invention generates stress through the difference in the thermal expansion coefficients of the card slot base materials, resulting in controllable stress for better stress distribution and lattice matching. The card slot base of this invention employs traditional material processing techniques, such as cutting, milling, and grinding, to shape and sized the material according to design requirements. The cover plate of this invention also employs traditional material processing techniques, such as cutting, milling, and grinding, to shape and sized the material according to design requirements.

[0009] Furthermore, the materials of the first base and the second base are each independently selected from one of metal, ceramic, quartz, graphite or polymer materials, and the first base and the second base are made of different materials.

[0010] Furthermore, the metal is any one of gold, copper, and manganese; The polymer material is either polyimide or silicone rubber.

[0011] Furthermore, the growth substrate is made of any one of sapphire, silicon, or silicon carbide.

[0012] Furthermore, the cover plate is made of tungsten metal.

[0013] Furthermore, this invention also provides the application of the above-mentioned MOCVD card slot in the preparation of GaN / AlGaN heterojunctions, wherein the preparation method of the GaN / AlGaN heterojunction is as follows: (1) Fix the first base and the second base with adhesive, and then assemble the card slot base, growth substrate and cover plate into an MOCVD card slot; (2) Place the card slot into the MOCVD reaction chamber, introduce the first reaction gas, raise the temperature to 900-1100 ℃, maintain the reaction chamber pressure at 30-75 Torr, control the temperature of the card slot base and substrate support structure, and maintain the temperature until the grown substrate shows a warped state. (3) Maintain the reaction chamber temperature at 900-1000℃ and the reaction chamber pressure at 20-100 Torr. Introduce the second reaction gas into the reaction chamber and complete the epitaxy of the GaN / AlGaN heterojunction on the warped growth substrate. After the heterojunction growth is completed, turn off the reaction gas supply and stop heating. After the card slot cools to a safe temperature, take out the grown substrate.

[0014] Furthermore, in step (2), the first reaction gas is composed of nitrogen, hydrogen, and ammonia; The flow rates are as follows: nitrogen 64 L / min, hydrogen 120 L / min, and ammonia 50 L / min.

[0015] In step (2) of the present invention, due to the difference in the thermal expansion coefficient of the card slot base material under high temperature environment, the base material will undergo different degrees of thermal expansion due to temperature change. The quartz base undergoes smaller thermal expansion, while the copper base undergoes larger thermal expansion, causing the growth substrate to exhibit a warped state with a positive warping degree.

[0016] Furthermore, in step (3), the second reaction gas is composed of a nitrogen source with a flow rate of 2500-4000 sccm, a gallium source with a flow rate of 40-120 sccm, and an aluminum source with a flow rate of 120-180 sccm.

[0017] Furthermore, the gallium source is trimethylgallium, and the aluminum source is trimethylaluminum. In step (3) of the present invention, the tensile stress introduced in the growth substrate will be distributed on the entire surface of the substrate during the growth process, so that the entire epitaxial structure is in a state of tensile stress.

[0018] The beneficial effects of this invention are as follows: 1. Selection and Composition of Card Slot Base Materials: This invention selects two or more materials with different coefficients of thermal expansion as the constituent materials of the card slot base. This allows for the generation of controlled stresses by utilizing the differences in thermal expansion between the materials, thereby optimizing stress distribution and lattice matching. Simultaneously, the stress-introduced card slot design, through reasonable material selection and structural design, achieves a more uniform stress distribution. This helps reduce stress concentration in the thin film, mitigating problems such as film cracking and mismatch.

[0019] 2. Stress Distribution and Lattice Matching During Thin Film Growth: This invention introduces stress by utilizing the difference in the thermal expansion coefficients of the slot base materials to achieve better stress distribution and lattice matching, thereby improving the quality and performance of the grown thin film. The stress-introducing slot can introduce stress through the difference in the thermal expansion coefficients of the materials, thus improving the lattice matching between the thin film and the substrate to a certain extent. This helps reduce lattice distortion and improve the crystallinity and electrical properties of the thin film. The optimized design of the stress-introducing slot helps improve the quality of the grown thin film. Reducing stress concentration and lattice distortion can lower defect density and improve the optical and electrical properties of the thin film.

[0020] 3. Wide Range of Applications: The MOCVD stress growth groove provided by this invention is suitable for the growth of various semiconductor materials and has broad application prospects. The stress-introduced groove can improve the stability of growth processes such as MOCVD through precise stress adjustment. This helps reduce the impact of process variations on film quality and improves production consistency and reliability.

[0021] In summary, the MOCVD growth slot of this invention can effectively utilize the difference in the thermal expansion coefficients of the slot base materials to introduce tensile stress into the GaN / AlGaN heterostructure, achieving better stress distribution and lattice matching, thereby realizing a p-channel heterojunction with high hole mobility. The slot base of this invention can generate controlled stress, optimizing stress distribution and thus reducing stress concentration problems. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the disassembled structure of the MOCVD card slot in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the card slot base structure in this invention; Figure 3 This is a schematic diagram of the cover plate structure in this invention; Figure 4 This is a schematic diagram of the process for preparing GaN / AlGaN heterojunctions according to the present invention; In the attached diagram, the structures indicated by each number are as follows: 1-Card slot base, 2-Growth substrate, 3-Cover plate, 11-First base, 12-Second base. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1 An MOCVD card slot includes a card slot base 1, a growth substrate 2, and a cover plate 3; The growth substrate 2 is positioned directly above the slot base 1; the cover plate 3 is hollow and is fixed directly above the growth substrate 2. The card slot base 1 includes a first base 11 and a second base 12; the second base 12 is embedded in the first base 11; The first base 11 and the second base 12 are made of different materials.

[0025] In some embodiments, the materials of the first base 11 and the second base 12 are each independently selected from one of metal, ceramic, quartz, graphite or polymer materials, and the first base and the second base are made of different materials.

[0026] In other embodiments, the metal is any one of gold, copper, and manganese; The polymer material can be either polyimide or silicone rubber.

[0027] In some embodiments, the growth substrate 2 is made of any one of sapphire, silicon, or silicon carbide.

[0028] In some embodiments, the cover plate 3 is made of tungsten metal.

[0029] Example 2: Preparation method of GaN / AlGaN heterojunction: (1) Using the MOCVD slot of Example 1, the first base and the second base are fixed with adhesive, and then the slot base, growth substrate and cover plate are assembled into MOCVD slot; (2) Place the card slot into the MOCVD reaction chamber, introduce the first reaction gas, raise the temperature to 1000℃, maintain the reaction chamber pressure at 45 Torr, control the temperature of the card slot base and substrate support structure, and maintain the temperature until the grown substrate exhibits a warped state; the first reaction gas consists of nitrogen, hydrogen and ammonia; wherein the nitrogen flow rate is 64 L / min, the hydrogen flow rate is 120 L / min and the ammonia flow rate is 50 L / min.

[0030] (3) Keep the reaction chamber temperature at 1000℃ and the reaction chamber pressure at 50 Torr. Introduce a second reaction gas into the reaction chamber. The second reaction gas consists of a nitrogen source with a flow rate of 3000 sccm, a gallium source (trimethylgallium) with a flow rate of 80 sccm, and an aluminum source (trimethylaluminum) with a flow rate of 150 sccm. Complete the epitaxy of the GaN / AlGaN heterojunction on the warped growth substrate. After the heterojunction growth is completed, turn off the reaction gas supply and stop heating. After the card slot cools to a safe temperature, take out the grown substrate.

[0031] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. An MOCVD card slot, characterized in that, Includes the card slot base, growth substrate, and cover plate; The growth substrate is positioned directly above the card slot base; the cover plate is hollow and is fixed directly above the growth substrate. The card slot base includes a first base and a second base; the second base is embedded in the first base; The first base and the second base are made of different materials.

2. The MOCVD card slot according to claim 1, characterized in that, The materials of the first base and the second base are each independently selected from one of metal, ceramic, quartz, graphite or polymer materials, and the first base and the second base are made of different materials.

3. The MOCVD card slot according to claim 2, characterized in that, The metal is any one of gold, copper, and manganese; The polymer material is either polyimide or silicone rubber.

4. The MOCVD card slot according to claim 1, characterized in that, The growth substrate is made of any one of sapphire, silicon, or silicon carbide.

5. The MOCVD card slot according to claim 1, characterized in that, The cover plate is made of tungsten metal.

6. The application of the MOCVD card slot according to any one of claims 1-5 in the preparation of GaN / AlGaN heterojunctions, characterized in that, The method for preparing the GaN / AlGaN heterojunction is as follows: (1) Fix the first base and the second base with adhesive, and then assemble the card slot base, growth substrate and cover plate into an MOCVD card slot; (2) Place the card slot into the MOCVD reaction chamber, introduce the first reaction gas, raise the temperature to 900-1100℃, maintain the reaction chamber pressure at 30-75 Torr, control the temperature of the card slot base and substrate support structure, and maintain the temperature until the grown substrate exhibits a warped state. (3) Maintain the reaction chamber temperature at 900-1000℃ and the reaction chamber pressure at 20-100 Torr. Introduce the second reaction gas into the reaction chamber and complete the epitaxy of the GaN / AlGaN heterojunction on the warped growth substrate. After the heterojunction growth is completed, turn off the reaction gas supply and stop heating. After the card slot cools to a safe temperature, take out the grown substrate.

7. The application of the MOCVD card slot according to claim 6 in the preparation of GaN / AlGaN heterojunctions, characterized in that, In step (2), the first reactant gas consists of nitrogen, hydrogen, and ammonia. The flow rates are as follows: nitrogen 64 L / min, hydrogen 120 L / min, and ammonia 50 L / min.

8. The application of the MOCVD card slot according to claim 6 in the preparation of GaN / AlGaN heterojunctions, characterized in that, In step (3), the second reaction gas consists of a nitrogen source with a flow rate of 2500-4000 sccm, a gallium source with a flow rate of 40-120 sccm, and an aluminum source with a flow rate of 120-180 sccm.

9. The application of the MOCVD card slot according to claim 8 in the preparation of GaN / AlGaN heterojunctions, characterized in that, The gallium source is trimethylgallium, and the aluminum source is trimethylaluminum.

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