CN114823284A - Growth method of Si substrate GaN epitaxial film - Google Patents

Abstract

The invention discloses a growth method of a Si substrate GaN epitaxial film, which avoids the growth of an AlN or AlN/AlGaN buffer layer when growing a GaN film on a Si substrate, and forms an interface for isolating Si and Ga by preprocessing the Si substrate to avoid the reaction of Ga and Si to generate meltback; the stress generated in the material growth process is adjusted by adjusting the growth temperature of the GaN stress adjusting layer and the GaN layer, so that a continuous and complete single crystal GaN film is formed. The method avoids the growth of the AlN or AlN/AlGaN buffer layer, thereby effectively reducing the deposition of AlN at the positions of graphite, a spray head and the like in a reaction chamber, reducing the cost of epitaxial growth, reducing the instability caused by the deposition and the uncertainty and the cost increase caused by the deposition treatment, effectively reducing the cost of epitaxial growth and the frequency of the deposition treatment, improving the stability, the reliability and the product yield of the epitaxial growth, growing other structures or functional layers on the GaN film, and being applied to the fields of power electronic devices, illumination and the like.

Description

A kind of growth method of GaN epitaxial thin film on Si substrate

technical field

The invention relates to the technical field of semiconductor thin film materials, in particular to a growth method of a GaN epitaxial thin film on a Si substrate.

Background technique

As one of the three main GaN-based LED technology routes, silicon-substrate GaN-based LED technology has achieved fruitful results. At the same time, Si substrate is also an ideal substrate for the growth of commercial GaN power electronic devices. The use of Si substrates to grow GaN materials has become an industry consensus.

At present, the industrialized method of 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 Si substrate, and then epitaxially grow GaN. This is because Ga reacts with Si, causing reflow corrosion to the Si substrate, so a continuous and flat crystal film cannot be formed. First, epitaxial growth of AlN or AlN/AlGaN buffer layer and then epitaxial growth of GaN can avoid Ga and Si substrate. The meltback reaction occurs in direct contact and reduces the stress between GaN and Si to a certain extent.

In the MOCVD growth process of AlN and GaN, in addition to being deposited on the Si substrate, they will also be deposited in other positions in the reaction chamber, such as showerheads, graphite, etc. These products will cause changes in the reaction chamber environment and lead to unstable growth. sex. Among them, AlN is easier to deposit than GaN, and it is difficult to clean it online. Only by regularly replacing graphite, using high-temperature furnace baking to remove deposits, and manually cleaning the deposits at the nozzle and other positions, the stability of the reaction chamber environment can be maintained. The growth of AlN will greatly increase the frequency of deposit processing, increase the time cost, and will cause uncertainty in material growth, affecting product yield.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a growth method of GaN epitaxial thin film on Si substrate, which does not require the growth of AlN or AlN/AlGaN buffer layer, thereby avoiding the deposition of AlN on graphite and showerhead in the reaction chamber, reducing the risk of deposition due to deposition. It can effectively reduce the cost of epitaxial growth and the frequency of deposition processing, and improve the stability, reliability and product yield of epitaxial growth.

The object of the present invention is achieved in this way:

A method for growing a GaN epitaxial thin film on a Si substrate, characterized in that the specific steps are as follows:

(1) placing the Si substrate in a reaction chamber, and pre-processing the Si substrate to form an interface isolating Si and Ga;

(2) growing a GaN stress regulating layer at the first growth temperature on the interface;

(3) growing a GaN thin film layer on the GaN stress regulating layer at a second growth temperature higher than the first growth temperature.

Optionally, in the step (1), the method for realizing the separation of the interface between Si and Ga is realized by introducing ammonia gas into the reaction chamber and performing ammoniation treatment on the Si substrate.

Optionally, in step (1), the interface between Si and Ga is isolated by feeding an Al source into the reaction chamber without feeding ammonia gas, and pre-depositing 1 to several atomic layers.

Optionally, the method for separating the interface between Si and Ga in step (1) is achieved by feeding an In source into the reaction chamber without feeding ammonia gas, and pre-depositing 1 to several atomic layers.

The first growth temperature in step (2) is 800°C-1000°C.

In step (2), the carrier gas for growing the GaN stress regulating layer is N ₂ .

In step (3), the second growth temperature is 900°C-1200°C, and the second growth temperature is higher than the first growth temperature.

The carrier gas for growing the GaN thin film layer in step (3) is H ₂ .

Optionally, the Si substrate is a patterned substrate, and the patterning is to partially mask the surface of the Si substrate with a foreign material, so that a plurality of window regions or etchings are formed on the surface of the Si substrate. A trench is formed on the surface of the Si substrate, which is realized by dividing the surface of the Si substrate into a plurality of mesas; the GaN material is epitaxial on the patterns of each Si substrate.

The GaN thin film obtained by the method of the present invention includes, from bottom to top, a Si substrate, an interface between Si and Ga, a GaN stress control layer and a GaN thin film. When growing the GaN thin film, growth of an AlN buffer layer was avoided. Before growing the GaN stress regulating layer, the Si substrate is pretreated to form the interface separating Si and Ga. The growth temperature of the GaN stress regulating layer is lower than the growth temperature of the GaN thin film.

Optionally, the carrier gas of the GaN stress control layer and the GaN thin film is different, and the carrier gas is N ₂ and H ₂ respectively.

The technical key of the present invention is: in step (1), by preprocessing the Si substrate, the interface between Si and Ga is formed to isolate Si, so as to effectively avoid the reaction of Ga and Si substrate to cause melting back corrosion; by adjusting step (2) The growth temperature of the GaN stress control layer and the GaN thin film described in step (3) plays the role of regulating the stress in the growth process of the material, so as to avoid the generation of cracks when the GaN film is subsequently grown on the GaN stress control layer, thereby A continuous and complete single crystal GaN thin film is formed.

Compared with the prior art, the present invention has the following advantages:

Epitaxial growth of GaN thin films on Si substrates avoids the growth of AlN or AlN/AlGaN buffer layers, thereby effectively reducing the deposition of AlN on graphite and showerheads in the reaction chamber, reducing the cost of epitaxial growth and reducing the risk of deposition caused by deposits. The uncertainty and cost increase caused by the instability and deposition processing, effectively reduce the cost of epitaxial growth and the frequency of deposition processing, improve the stability, reliability and product yield of epitaxial growth, in the GaN thin film Other structural or functional layers are grown on it, which are used in power electronic devices, lighting and other fields.

Detailed ways

In order to facilitate the understanding and implementation of the present invention by those of ordinary skill in the art, the present invention will be further described in detail below with reference to the embodiments. It should be understood that the embodiments described herein are only used to illustrate and explain the present invention, but not to limit the present invention.

The present invention provides following embodiment:

Example 1:

The implementation steps of the present invention are as follows:

In step 1, ammonia gas is introduced into the reaction chamber, and the Si substrate is subjected to ammoniation treatment to form an interface separating Si and Ga;

The patterned Si substrate is placed in the MOCVD reaction chamber of metal organic chemical vapor deposition, and ammonia gas is passed into the reaction chamber, and the Si substrate is pretreated at a preset temperature of 925 °C, and the pretreatment time is 20s ;

Step 2, growing a GaN stress control layer;

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

Step 3, growing a GaN thin film;

The temperature was raised to 1000° C., TMGa and ammonia gas were introduced into the reaction chamber, and the carrier gas was hydrogen gas, and a GaN film with a thickness of 1000 nm was grown.

Example 2:

The implementation steps of the present invention are as follows:

Step 1, pass an Al source into the reaction chamber without passing ammonia gas, and pre-deposit several Al atomic layers on the Si substrate to form an interface separating Si and Ga;

The patterned Si substrate is placed in a MOCVD reaction chamber for metal organic chemical vapor deposition, and TMAl is passed into the reaction chamber, and the Si substrate is pretreated at a preset temperature of 925°C, and the pretreatment time is 20s;

Step 2, growing a GaN stress control layer;

The temperature of the pretreated Si substrate was raised to 950°C, TMGa and ammonia gas were introduced into the reaction chamber, the carrier gas was nitrogen, and a GaN stress control layer with a thickness of 150 nm was grown;

Step 3, growing a GaN thin film;

The temperature of the Si substrate on which the GaN stress control layer has been grown is raised to 1050°C, TMGa and ammonia gas are fed into the reaction chamber, and the carrier gas is hydrogen to grow a GaN film with a thickness of 800 nm.

Example 3:

The implementation steps of the present invention are as follows:

Step 1, pass an In source into the reaction chamber without passing ammonia gas, and pre-deposit several In atomic layers on the Si substrate to form an interface separating Si and Ga;

The patterned Si substrate is placed in a MOCVD reaction chamber for metal organic chemical vapor deposition, and TMIn is passed into the reaction chamber, and the Si substrate is pretreated at a preset temperature of 700°C, and the pretreatment time is 20s;

Step 2, growing a GaN stress control layer;

The temperature of the pretreated Si substrate was lowered to 850°C, TMGa and ammonia gas were introduced into the reaction chamber, the carrier gas was nitrogen, and a GaN stress control layer with a thickness of 80 nm was grown;

Step 3, growing a GaN thin film.

The temperature was raised to 1050° C., TMGa and ammonia gas were introduced into the reaction chamber, and the carrier gas was hydrogen, and a GaN film with a thickness of 600 nm was grown.

The above are only three specific embodiments of the present invention, rather than all the embodiments.

It should be understood that the above description of the preferred embodiment is relatively detailed, and therefore should not be considered as a limitation on the scope of the patent protection of the present invention. In the case of the protection scope, substitutions or deformations can also be made, which all fall within the protection scope of the present invention, and the claimed protection scope of the present invention shall be subject to the appended claims.

Claims (9)

1. a growth method of Si substrate GaN epitaxial film, is characterized in that: Concrete steps are as follows: (1) placing the Si substrate in a reaction chamber, and pre-processing the Si substrate to form an interface isolating Si and Ga; (2) growing a GaN stress regulating layer at the first growth temperature on the interface; (3) growing a GaN thin film layer on the GaN stress regulating layer at a second growth temperature higher than the first growth temperature. 2 . The method for growing a GaN epitaxial thin film on a Si substrate according to claim 1 , wherein the method for isolating the interface between Si and Ga in the step (1) is to pass ammonia gas into the reaction chamber, so that the The Si substrate is subjected to ammonia treatment. 3 . The method for growing a GaN epitaxial thin film on Si substrate according to claim 1 , wherein the method for isolating the interface between Si and Ga in the step (1) is by reacting with gas without introducing ammonia gas. 4 . Al source is connected to the chamber, and 1 to several atomic layers are pre-deposited. 4 . The method for growing a GaN epitaxial thin film on a Si substrate according to claim 1 , wherein the method for isolating the interface between Si and Ga in the step (1) is by reacting with gas without introducing ammonia gas. 5 . The In source is connected to the chamber, and 1 to several atomic layers are pre-deposited. 5 . The method for growing a GaN epitaxial thin film on Si substrate according to claim 1 , 2 or 3 or 4 , wherein the first growth temperature in step (2) is 800° C.-1000° C. 6 . 6 . The method for growing a GaN epitaxial thin film on Si substrate according to claim 1 , wherein the carrier gas for growing the GaN stress control layer in step (2) is N ₂ . 7 . 7 . The method for growing a GaN epitaxial thin film on Si substrate according to claim 1 or 2 or 3 or 4, characterized in that: in step (3), the second growth temperature is 900°C-1200°C, and the first The second growth temperature is higher than the first growth temperature. 8 . The method for growing a GaN epitaxial thin film on Si substrate according to claim 1 , wherein the carrier gas for growing the GaN thin film layer in step (3) is H ₂ . 9 . 9 . The method for growing a GaN epitaxial thin film on a Si substrate according to claim 1 , wherein the Si substrate is a patterned substrate, and the patterning is formed by using a foreign material on the surface of the Si substrate. 10 . The partial mask is used to form a plurality of window regions on the surface of the Si substrate or to etch the surface of the Si substrate to form trenches, so that the surface of the Si substrate is divided into a plurality of mesas.