A method for growing a GaN epitaxial film on a Si substrate

Abstract

The application discloses a growth method of Si substrate GaN epitaxial film, which avoids the growth of AlN or AlN / AlGaN buffer layer when growing the GaN film on the Si substrate, forms an interface for isolating Si and Ga by pretreating the Si substrate, avoids the reaction of Ga and Si to produce remelting, adjusts the growth temperature of the GaN stress regulation layer and the GaN layer, adjusts the stress generated in the material growth process, and thus forms a continuous and complete single crystal GaN film. The method avoids the growth of AlN or AlN / AlGaN buffer layer, thereby effectively reducing the deposition of AlN in the reaction chamber at positions such as graphite and a nozzle, reducing the cost of epitaxial growth, reducing the instability caused by the deposits, and reducing the uncertainty and cost increase caused by the deposit treatment, effectively reducing the cost of epitaxial growth and the frequency of deposit treatment, improving the stability, reliability and product yield of epitaxial growth, growing other structure or functional layers on the GaN film, and applying to the fields of power electronic devices, illumination and the like.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of semiconductor thin film materials, and particularly relates to a growth method of Si substrate GaN epitaxial thin film. BACKGROUND

[0002] As one of the three main GaN-based LED technology routes, the silicon substrate GaN-based LED technology has achieved fruitful results, and the Si substrate is also an ideal substrate suitable for the growth of commercial GaN power electronic devices. It has become a consensus in the industry to grow GaN materials on Si substrates.

[0003] At present, the industrialization method for epitaxial growth of GaN on Si substrate is to use metal organic chemical vapor deposition (MOCVD) to first epitaxially grow AlN or AlN / AlGaN as a buffer layer on the Si substrate, and then epitaxially grow GaN. This is because Ga will react with Si to cause back-melting corrosion of the Si substrate, so that a continuous and flat crystal thin film cannot be formed. Epitaxial growth of AlN or AlN / AlGaN buffer layer and then epitaxial growth of GaN can avoid the back-melting reaction caused by direct contact between Ga and Si substrate, and to some extent, reduce the stress between GaN and Si.

[0004] During the MOCVD growth of AlN and GaN, in addition to being deposited on the Si substrate, it will also be deposited on other positions in the reaction chamber, such as the nozzle, graphite, etc. These products will cause changes in the environment in the reaction chamber, leading to instability in growth. Among them, AlN is more likely to be deposited than GaN, and it is difficult to clean online. Only by regularly replacing the graphite, using high-temperature oven baking to remove the deposits, and manually cleaning the deposits at positions such as the nozzle can the stability of the environment in the reaction chamber be maintained. The growth of AlN greatly increases the frequency of deposit treatment, increases the time cost, and causes uncertainty in material growth, affecting product yield. SUMMARY

[0005] The purpose of the present application is to provide a growth method of Si substrate GaN epitaxial thin film, which does not need to grow AlN or AlN / AlGaN buffer layer, thereby avoiding the deposition of AlN at positions such as graphite and nozzle in the reaction chamber, reducing the instability caused by deposits and the uncertainty and cost increase caused by deposit treatment, effectively reducing the cost of epitaxial growth and the frequency of deposit treatment, and improving the stability, reliability and product yield of epitaxial growth.

[0006] The purpose of the present application is achieved as follows:

[0007] A growth method of Si substrate GaN epitaxial thin film, characterized by the following specific steps:

[0008] (1) Put Si substrate into reaction chamber, and pretreat the Si substrate to form interface isolating Si and Ga;

[0009] (2) Grow GaN stress regulation layer on the interface at first growth temperature;

[0010] (3) Grow GaN thin film layer on the GaN stress regulation layer at second growth temperature higher than the first growth temperature.

[0011] Optionally, the method for forming the interface isolating Si and Ga in step (1) is to introduce ammonia into the reaction chamber to realize ammonia treatment of the Si substrate.

[0012] Optionally, the method for forming the interface isolating Si and Ga in step (1) is to introduce Al source into the reaction chamber without introducing ammonia to realize pre-deposition of 1 to several atomic layers.

[0013] Optionally, the method for forming the interface isolating Si and Ga in step (1) is to introduce In source into the reaction chamber without introducing ammonia to realize pre-deposition of 1 to several atomic layers.

[0014] The first growth temperature in step (2) is 800-1000℃.

[0015] The carrier gas for growing the GaN stress regulation layer in step (2) is N2.

[0016] The second growth temperature in step (3) is 900-1200℃, and the second growth temperature is higher than the first growth temperature.

[0017] The carrier gas for growing the GaN thin film layer in step (3) is H2.

[0018] Optionally, the Si substrate is a patterned substrate, and the patterning is realized by local mask of heterogeneous material on the surface of the Si substrate to form a plurality of window regions or etching the surface of the Si substrate to form grooves, so that the surface of the Si substrate is divided into a plurality of mesas; GaN material is epitaxially grown on the patterns of the Si substrate.

[0019] The GaN thin film obtained by the method comprises, from bottom to top, Si substrate, interface isolating Si and Ga, GaN stress regulation layer and GaN thin film. In the growth of the GaN thin film, AlN buffer layer is avoided. Before the growth of the GaN stress regulation layer, the Si substrate is pretreated to form the interface isolating Si and Ga. The growth temperature of the GaN stress regulation layer is lower than the growth temperature of the GaN thin film.

[0020] Optionally, the GaN stress regulating layer is different from the carrier gas of the GaN thin film, and the carrier gas is N2 and H2 respectively.

[0021] The technical key of the application is that: in step (1), the interface isolating Si and Ga is formed by pre-treating the Si substrate, effectively avoiding the reaction of Ga and Si substrate to produce back-melting corrosion; by adjusting the growth temperature of the GaN stress regulating layer in step (2) and the GaN thin film in step (3), the stress in the material growth process is regulated, avoiding the generation of cracks when growing the GaN thin film on the GaN stress regulating layer, thereby forming a continuous and complete single crystal GaN thin film.

[0022] Compared with the prior art, the application has the following advantages:

[0023] The GaN thin film is epitaxially grown on the Si substrate, avoiding the growth of the AlN or AlN / AlGaN buffer layer, thereby effectively reducing the deposition of AlN in the reaction chamber at positions such as graphite and the nozzle, reducing the cost of epitaxial growth, reducing the instability caused by the deposition and the uncertainty and cost increase caused by the deposition treatment, effectively reducing the cost of epitaxial growth and the frequency of deposition treatment, improving the stability, reliability and product yield of epitaxial growth, growing other structure or functional layers on the GaN thin film, and applying to power electronic devices, lighting and other fields. DETAILED DESCRIPTION

[0024] In order to facilitate those skilled in the art to understand and implement the application, the application is further described in detail below in combination with examples, and it should be understood that the examples described herein are only used to illustrate and explain the application, and are not used to limit the application.

[0025] The application gives the following examples:

[0026] Example 1:

[0027] The implementation steps of the application are as follows:

[0028] Step 1, ammonia gas is introduced into the reaction chamber, and the Si substrate is subjected to ammonia treatment to form an interface isolating Si and Ga;

[0029] The patterned Si substrate is placed in a metal organic chemical vapor deposition (MOCVD) reaction chamber, and ammonia gas is introduced into the reaction chamber, and the Si substrate is pre-treated at a preset temperature of 925 DEG C for 20 s;

[0030] Step 2, growing a GaN stress regulating layer;

[0031] The temperature of the pretreated Si substrate is reduced to 800 DEG C, TMGa, ammonia gas is introduced into the reaction chamber, the carrier gas is nitrogen, and a GaN stress control layer with a thickness of 100 nm is grown;

[0032] Step 3, growing a GaN thin film;

[0033] The temperature is increased to 1000 DEG C, TMGa, ammonia gas is introduced into the reaction chamber, the carrier gas is hydrogen, and a GaN thin film with a thickness of 1000 nm is grown.

[0034] Example 2:

[0035] The implementation steps of the present application are as follows:

[0036] Step 1, an Al source is introduced into the reaction chamber without ammonia gas, a few Al atomic layers are pre-deposited on the Si substrate to form an interface for isolating Si and Ga;

[0037] The patterned Si substrate is placed in a metal organic chemical vapor deposition (MOCVD) reaction chamber, TMAl is introduced into the reaction chamber, the Si substrate is pretreated at a preset temperature of 925 DEG C, and the pretreatment time is 20 s;

[0038] Step 2, growing a GaN stress control layer;

[0039] The temperature of the pretreated Si substrate is increased to 950 DEG C, TMGa, ammonia gas is introduced into the reaction chamber, the carrier gas is nitrogen, and a GaN stress control layer with a thickness of 150 nm is grown;

[0040] Step 3, growing a GaN thin film;

[0041] The temperature of the Si substrate on which the GaN stress control layer has been grown is increased to 1050 DEG C, TMGa, ammonia gas is introduced into the reaction chamber, the carrier gas is hydrogen, and a GaN thin film with a thickness of 800 nm is grown.

[0042] Example 3:

[0043] The implementation steps of the present application are as follows:

[0044] Step 1, an In source is introduced into the reaction chamber without ammonia gas, a few In atomic layers are pre-deposited on the Si substrate to form an interface for isolating Si and Ga;

[0045] The patterned Si substrate is placed in a metal organic chemical vapor deposition (MOCVD) reaction chamber, TMIn is introduced into the reaction chamber, the Si substrate is pretreated at a preset temperature of 700 DEG C, and the pretreatment time is 20 s;

[0046] Step 2, growing a GaN stress control layer;

[0047] The temperature of the pretreated Si substrate is reduced to 850℃, TMGa, ammonia gas are introduced into the reaction chamber, the carrier gas is nitrogen, and a GaN stress control layer with a thickness of 80nm is grown;

[0048] Step 3: growing a GaN thin film.

[0049] The temperature is increased to 1050℃, TMGa, ammonia gas are introduced into the reaction chamber, the carrier gas is hydrogen, and a GaN thin film with a thickness of 600nm is grown.

[0050] The above are only three specific embodiments of the present application, not all embodiments.

[0051] It should be understood that the above description of the preferred embodiments is detailed and is not considered as a limitation to the patent protection scope of the present application. Those skilled in the art can make substitutions or modifications without departing from the scope of the present application, and all fall within the protection scope of the present application. The patent protection scope of the present application should be subject to the appended claims.

Claims

1. A method for growing GaN epitaxial thin films on Si substrates, characterized by the following specific steps: (1) The Si substrate is placed in the reaction chamber and pretreated to form an interface that isolates Si and Ga; wherein, The interface that isolates Si and Ga is achieved in any of the following ways: (a) Ammonia gas is introduced into the reaction chamber to perform ammoniation treatment on the Si substrate; or (b) Introduce an Al source into the reaction chamber without ammonia to pre-deposit one to several atomic layers; or (c) In a source is introduced into the reaction chamber without ammonia to pre-deposit 1 to several atomic layers; (2) On the interface, a GaN stress-controlled layer is grown at a first growth temperature; (3) On the GaN stress control layer, a GaN thin film layer is grown at a second growth temperature higher than the first growth temperature.

2. The method for growing GaN epitaxial films on Si substrates according to claim 1, characterized in that: the first growth temperature in step (2) is 800℃-1000℃.

3. The method for growing GaN epitaxial films on Si substrates according to claim 1, characterized in that: the carrier gas for growing the GaN stress-regulating layer in step (2) is N2.

4. The method for growing GaN epitaxial films on Si substrates according to claim 1, characterized in that: the second growth temperature in step (3) is 900℃-1200℃, and the second growth temperature is higher than the first growth temperature.

5. The method for growing GaN epitaxial thin films on Si substrates according to claim 1, characterized in that: the carrier gas for growing the GaN thin film layer in step (3) is H2.

6. The method for growing GaN epitaxial thin films on Si substrates according to claim 1, characterized in that: the Si substrate is a patterned substrate, and the patterning is achieved by locally masking the surface of the Si substrate with a heteromaterial to form multiple window areas on the surface of the Si substrate or etching the surface of the Si substrate to form trenches, thereby dividing the surface of the Si substrate into multiple mesa.