CN108538968B - A kind of growing method and application of aluminium nitride film - Google Patents

Abstract

The invention provides a growth method and application of an aluminum nitride film. The growth method comprises the following steps: 1) injecting trimethylaluminum and ammonia gas to generate a first aluminum nitride layer on a substrate; 2) forming a first aluminum nitride layer on a substrate; The aluminum nitride layer is subjected to nano-scale column etching treatment to obtain a column-depressed aluminum nitride layer, and the column-depressed aluminum nitride layer has a plurality of nano-scale column depressions; 3) controlling the temperature and pressure of the reaction chamber, Feed trimethylaluminum and ammonia gas to generate a second aluminum nitride layer on the depressed aluminum nitride layer of the column; 4) control the temperature and pressure of the reaction chamber, feed trimethylaluminum and ammonia gas, and Generate the third aluminum nitride layer on the aluminum nitride layer; wherein, the molar flow ratio of ammonia gas and trimethylaluminum in step 3) is less than the molar flow ratio of ammonia gas and trimethylaluminum in step 4); aluminum nitride The film is a collection of a first aluminum nitride layer, a second aluminum nitride layer and a third aluminum nitride layer. The invention can significantly improve the crystal quality of the AlN thin film.

Description

A kind of growth method and application of aluminum nitride film

technical field

The invention relates to a growth method and application of an aluminum nitride film, belonging to the technical field of light emitting diodes.

Background technique

Aluminum nitride (AlN) belongs to the third-generation wide bandgap semiconductor material, which has the advantages of high bandgap width, high breakdown electric field, high thermal conductivity, high electron saturation rate and high radiation resistance. AlN crystal has a stable hexagonal wurtzite structure, the lattice constant AlN has the largest direct band gap of about 6.2eV among III-V non-semiconductor materials, and is an important blue and ultraviolet luminescent material. It has high thermal conductivity, high resistivity, strong breakdown field, and small dielectric coefficient. It is an excellent electronic material for high-temperature, high-frequency and high-power devices. Moreover, AlN oriented along the c-axis has very good piezoelectric properties and high-speed propagation of surface acoustic waves, and is an excellent piezoelectric material for surface acoustic wave devices. At the same time, AlN crystals have very close lattice constants and thermal expansion coefficients to GaN crystals, and are the preferred substrate materials for epitaxially grown AlGaN optoelectronic devices. Based on the excellent characteristics of AlN thin films, AlN thin film materials are widely used in ultraviolet detectors, high electron mobility transistors (HEMTs), and ultraviolet light-emitting diodes (LEDs).

Although AlN has many advantages, it is very difficult to prepare AlN materials. Preparation of AlN requires high temperature equipment and precise source flow control system. At present, the following difficulties exist in the preparation of high-quality AlN thin films: (1) Because the migration rate of Al atoms is very slow, high-temperature equipment is required to increase the migration rate of Al atoms on the substrate surface. Generally, the temperature of high-temperature equipment needs to exceed 1200°C; (2) The lattice mismatch between AlN and the substrate is low, which will easily cause huge internal stress during the growth process of the AlN film, and the stress release will eventually cause Severe cracks are generated on the surface of the AlN film; (3) In order to reduce or eliminate surface cracks, reducing the thickness is one direction, but the reduction in thickness will deteriorate the crystal quality of the AlN film, so that it cannot meet the needs of device preparation; (4) AlN During the growth process of the film, defects such as line defects and dislocations will appear as the thickness increases; (5) The high crystal quality of the AlN film and the integrity of the AlN film without cracks are two contradictory technical problems. At present, in order to obtain High-quality AlN films need to sacrifice surface properties to a certain extent, and in order to obtain excellent surface properties, the crystal quality of AlN films will inevitably decrease.

Contents of the invention

In view of the above-mentioned defects, the present invention provides a growth method and application of an aluminum nitride film, which can release the stress in the growth process of the AlN film well, eliminate the surface cracks of the AlN film, and at the same time, increase the The growth thickness and the reduction of dislocations and line defects that may occur during the growth of the AlN thin film can significantly improve the crystal quality of the AlN thin film, thereby helping to improve the performance of devices prepared on the AlN thin film material.

The invention provides a method for growing an aluminum nitride film, comprising the following steps:

1) After putting the substrate layer into the reaction chamber of the growth equipment, feed trimethylaluminum and ammonia gas to form a first aluminum nitride layer with a thickness of 200-2000nm on the substrate;

2) performing nanoscale pillar etching on the first aluminum nitride layer to obtain a pillar-depressed aluminum nitride layer, wherein the pillar-depressed aluminum nitride layer has a plurality of nano-scale pillar depressions;

3) Control the temperature of the reaction chamber to be 1300-1500° C., the pressure to be 20-100 mbar, feed trimethylaluminum and ammonia gas, and form the first aluminum nitride layer with a thickness of 200-1000 nm on the depressed aluminum nitride layer of the column. Aluminum nitride layer;

4) Control the temperature of the reaction chamber to be 1100-1400° C., the pressure to be 50-300 mbar, feed trimethylaluminum and ammonia gas, and form a third aluminum nitride layer with a thickness of 500-4000 nm on the second aluminum nitride layer. Aluminum nitride layer;

Wherein, the molar flow ratio of ammonia gas and trimethylaluminum in step 3) is less than the molar flow ratio of ammonia gas and trimethylaluminum in step 4); the aluminum nitride film is the first aluminum nitride layer, A collection of the second aluminum nitride layer and the third aluminum nitride layer.

The method for growing an aluminum nitride film as described above, wherein, in step 3), the molar flow ratio of ammonia gas and trimethylaluminum is 100-1000.

The method for growing an aluminum nitride film as described above, wherein, in step 4), the molar flow ratio of the ammonia gas and trimethylaluminum is 1000-5000.

The method for growing an aluminum nitride film as described above, wherein, in the aluminum nitride layer where the columns are depressed, the distance between two adjacent nanoscale column depressions is 50-1000 nm;

The nanoscale cylinder depression is selected from one or both of nanoscale cylinder depression and nanoscale prismatic cylinder depression.

The method for growing an aluminum nitride film as described above, wherein the diameter of the cross-section of the nanoscale cylinder depression is 10-1000 nm, and the height of the nanoscale cylinder depression is 50-2000 nm.

The method for growing an aluminum nitride film as described above, wherein the side length of the cross section of the nanoscale prismatic column depression is 10-1000 nm, and the height of the nanoscale prismatic column depression is 50-2000 nm.

The method for growing an aluminum nitride film as described above, wherein, in step 1), the temperature of the reaction chamber is controlled to be 1100-1500° C., and the pressure is 20-300 mbar.

The method for growing an aluminum nitride film as described above, wherein, in step 1), the molar flow ratio of ammonia gas and trimethylaluminum is 1000-5000.

The method for growing an aluminum nitride film as described above, wherein the substrate layer is selected from one of sapphire, silicon, silicon carbide, zinc oxide, copper and glass.

The present invention also provides an application of any one of the above aluminum nitride film growth methods in manufacturing LED epitaxial structures.

Implementation of the present invention has at least the following advantages:

1. In the present invention, by introducing nanoscale column depressions, defects such as line defects and dislocations that occur during the growth process of the second aluminum nitride layer and the third aluminum nitride layer are greatly annihilated in the nanoscale column depression area, thereby AlN thin films with low defect concentration and high crystal quality can be obtained;

2. The present invention releases the huge internal stress generated during the growth process of the AlN film by introducing nano-scale column depressions, thereby suppressing the generation of cracks on the surface of the AlN film;

3. The method of the present invention is simple and easy, and a high-quality crack-free AlN film can be obtained without the assistance of large-scale equipment;

4. The nano-scale column defects obtained by etching in the present invention are easy to form photonic crystals, which play a positive role in the subsequent device processing on the AlN film;

5. The AlN thin film produced by the present invention not only has no cracks, but also has high crystal quality, so the present invention can greatly improve the performance of devices on the AlN thin film;

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description These are some embodiments of the present invention. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.

Fig. 1 is the schematic diagram of the embodiment of the first aluminum nitride layer before the nanoscale column etching treatment of the present invention;

Fig. 2 is a schematic diagram of an embodiment of the aluminum nitride layer of the column depression after the nanoscale column etching treatment of the present invention;

Fig. 3 is a schematic diagram of another embodiment of the aluminum nitride layer of the column depression after the nano-scale column etching treatment of the present invention;

FIG. 4 is a schematic diagram of yet another embodiment of a column-depressed aluminum nitride layer after nano-scale column etching treatment according to the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments It is a part of embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of the present invention.

The invention provides a method for growing an aluminum nitride film, comprising the following steps:

1) After putting the substrate layer into the reaction chamber of the growth equipment, feed trimethylaluminum and ammonia gas to form a first aluminum nitride layer with a thickness of 200-2000nm on the substrate;

2) performing nanoscale pillar etching on the first aluminum nitride layer to obtain a pillar-depressed aluminum nitride layer, wherein the pillar-depressed aluminum nitride layer has a plurality of nano-scale pillar depressions;

3) Control the temperature of the reaction chamber to be 1300-1500° C., the pressure to be 20-100 mbar, feed trimethylaluminum and ammonia gas, and form the first aluminum nitride layer with a thickness of 200-1000 nm on the depressed aluminum nitride layer of the column. Aluminum nitride layer;

4) Control the temperature of the reaction chamber to be 1100-1400° C., the pressure to be 50-300 mbar, feed trimethylaluminum and ammonia gas, and form a third aluminum nitride layer with a thickness of 500-4000 nm on the second aluminum nitride layer. Aluminum nitride layer;

Wherein, the molar flow ratio of ammonia gas and trimethylaluminum in step 3) is less than the molar flow ratio of ammonia gas and trimethylaluminum in step 4); the aluminum nitride film is the first aluminum nitride layer, A collection of the second aluminum nitride layer and the third aluminum nitride layer.

In the present invention, the first aluminum nitride layer is first grown on the substrate layer, and since the thickness of the first aluminum nitride layer is 200-2000nm, phenomena such as line defects and cracks do not occur. Subsequently, nanoscale pillar body recesses are etched in the first aluminum nitride layer. Afterwards, the epitaxial growth of the second aluminum nitride layer and the third aluminum nitride layer is continued on the first nitride layer with nano-scale columnar depressions, and finally, the first aluminum nitride layer is sequentially formed on the substrate layer from bottom to top. layer, the second aluminum nitride layer and the third aluminum nitride layer, and the set of the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer is the aluminum nitride film. Among them, the growth of the second aluminum nitride layer is to increase the probability of lateral merging and quickly fill up the depressions of the nano-scale pillars, so that the dislocations and line defects that appear during the growth of the second aluminum nitride layer are annihilated in the nanometer At the same time, the nano-scale column depression can also serve as a stress release point generated during the growth process of the second aluminum nitride layer, thereby suppressing the generation of cracks.

Fig. 1 is a schematic diagram of an embodiment of the first aluminum nitride layer before the nanoscale pillar etching treatment of the present invention, as shown in Fig. An aluminum nitride layer 2 .

Specifically, after the substrate layer 1 is placed in the reaction chamber of the growth equipment, trimethylaluminum and ammonia gas are introduced under certain temperature and pressure conditions, and trimethylaluminum and ammonia gas decompose under the temperature and pressure, thereby A first aluminum nitride layer 2 is formed on the substrate layer. In order to avoid cracks in the first aluminum nitride layer 2 , the thickness of the first aluminum nitride layer 2 can be controlled to 200-2000 nm by controlling the flow rate of trimethylaluminum and ammonia gas and the reaction time.

Wherein, when forming the first aluminum nitride layer 2, the temperature of the reaction chamber can be controlled to be 1100-1500° C., the pressure of the reaction chamber is 20-300 mbar, and the molar flow ratio of ammonia gas and trimethylaluminum is 1000~5000.

In the present invention, the substrate layer 1 can be selected from one of sapphire, silicon, silicon carbide, zinc oxide, copper and glass.

Subsequently, the substrate layer 1 grown with the first aluminum nitride layer 2 is taken out from the reaction chamber, and the first aluminum nitride layer 2 is subjected to nano-scale column etching treatment, so that the first aluminum nitride layer 2 is transformed into a layer with The pillars of the plurality of nanoscale pillars recess 3 the aluminum nitride layer 4 .

The so-called aluminum nitride layer with columnar depressions specifically refers to etching a plurality of nanoscale columnar depressions on the first aluminum nitride layer through an etching process.

Wherein, the nano-scale pillar depression means that the size of each pillar depression is on the nanoscale and the distance between two adjacent pillar depressions is also on the nanometer scale.

After the etching process is finished, the aluminum nitride layer of the body recess is put into the reaction chamber again to carry out the growth of the second aluminum nitride layer in step 3).

Specifically, after putting the depressed aluminum nitride layer of the column into the reaction chamber, control the temperature of the reaction chamber to 1300-1500° C., and the pressure to 20-100 mbar. The flow rate of aluminum and ammonia gas and the reaction time are used to form a second aluminum nitride layer with a thickness of 200-1000nm on the aluminum nitride layer in the depression of the column.

In step 3), trimethylaluminum and ammonia decompose under the action of temperature and pressure to form aluminum atoms and nitrogen atoms, which will be in the nano-scale column depressions in the first aluminum nitride layer And in the non-recessed area, gather and react to generate aluminum nitride, wherein, the aluminum nitride generated in the non-recessed area and the aluminum nitride in the nano-scale column depression will make the aluminum nitride defects (line defects and bit defects) when combined. Wrong) annihilation, that is, the large size of defects in the nano-scale column depressions is annihilated, thereby improving the quality of the second aluminum nitride. At the same time, the nanocolumn depression can also release the stress caused by the excessive mismatch between the aluminum nitride and the substrate layer, thereby suppressing the generation of cracks.

Finally, in step 4), the temperature of the reaction chamber is controlled to be 1100-1400° C., the pressure is 50-300 mbar, and trimethylaluminum and ammonia gas are introduced into the reaction chamber to form a layer with a thickness of 500-300 mbar on the second aluminum nitride layer. 4000nm third aluminum nitride layer.

It should be noted that in step 4), the amounts of trimethylaluminum and ammonia gas that are fed into the reaction chamber need to be controlled. Since the second aluminum nitride layer in step 3) has filled the nano-scale column depressions, in order to improve the thickness of the aluminum nitride by increasing the thickness (that is, growing the third nitride layer on the second aluminum nitride layer) Crystal quality, so the inventor has done a lot of research, when the molar flow ratio of ammonia gas and trimethylaluminum for growing the third aluminum nitride layer is greater than the molar flow ratio of ammonia gas and trimethylaluminum for growing the second aluminum nitride layer , a flat third aluminum nitride layer can be rapidly grown on the basis of the second aluminum nitride layer.

After the third aluminum nitride layer is grown, the assembly of the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer is the prepared aluminum nitride film, so the method of the present invention can A defect-free and crack-free aluminum nitride film with a thickness of 900-7000nm is obtained.

Further, in step 3), the molar flow ratio of ammonia gas and trimethylaluminum is 100-1000; in step 4), the molar flow ratio of ammonia gas and trimethylaluminum is 1000-5000.

In a specific embodiment, the nanoscale columnar depressions in step 2) may be cylindrical or prismatic columnar, or a combination of cylindrical and prismatic columnar. Wherein, the prismatic column depressions may be regular triangular prism depressions, regular quadrangular prism depressions, regular hexagonal prism depressions, and the like. Fig. 2 is a schematic diagram of an embodiment of a columnar aluminum nitride layer after the nanoscale columnar etching treatment of the present invention; Fig. 3 is a schematic diagram of another embodiment of the columnar concave aluminum nitride layer after the nanoscale columnar etching treatment of the present invention ; FIG. 4 is a schematic diagram of yet another embodiment of the aluminum nitride layer of the column depression after the nano-scale column etching treatment of the present invention. Wherein, the nano-scale column depressions in FIG. 2 are cylindrical depressions, the nano-scale column depressions in FIG. 3 are regular triangular prism depressions, and the nano-scale column depressions in FIG. 4 are regular hexagonal prism depressions.

Further, the specific dimensions of the nano-scale column depressions valued in the present invention are as follows:

When the nanoscale pillar depression is a cylinder depression, the diameter of the circle of the cross section of the cylinder depression is 10-1000nm, and the height of the cylinder depression (ie the depth of the depression) is 50-2000nm.

When the nano-scale column depression is a prismatic column depression, the side length of the polygon of the cross section of the prismatic column depression is 10-1000nm, and the height of the prismatic column depression (ie the depth of the depression) is 50-2000nm.

In addition, in the pillar-depressed aluminum nitride layer, the distance between two adjacent pillar-depresses is 50-1000 nm.

In order to make the second aluminum nitride layer and the third aluminum nitride layer have a good growth environment, generally, after step 2) is completed and before step 3), the aluminum nitride layer of the column depression needs to be cleaned. Optionally, the depressed aluminum nitride layer of the column is rinsed with 60-80% hydrochloric acid aqueous solution for 2-3 times, and then rinsed with distilled water.

Further, in the present invention, the growth equipment of the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer can be selected from metal organic chemical vapor deposition equipment, molecular beam epitaxy equipment and hydride vapor phase epitaxy equipment any of the.

The invention prepares a crack-free and defect-free aluminum nitride film with a certain thickness, and grows N-type doped layer, quantum well light-emitting layer and P-type in sequence through the crack-free and defect-free aluminum nitride film prepared in the present invention. Doping the layer, it is possible to obtain an epitaxial structure with an aluminum nitride layer.

Because the aluminum nitride layer is flat and free of cracks, and the crystal quality is high, the epitaxial structure and LED obtained on the basis of the present invention have good luminous brightness and long working life.

Hereinafter, the method for growing the aluminum nitride film of the present invention will be described in detail through several specific examples.

Example 1

The growth method of aluminum nitride film of the present invention comprises the following steps:

1) Take a 2-inch sapphire substrate, raise the temperature of the reaction chamber of the metal-organic chemical vapor deposition (MOCVD) equipment to 1200°C, control the pressure of the reaction chamber at 100mbar, and feed trimethylaluminum at 300ml/min and 10000mL/min Ammonia gas was introduced to react, and after 30 minutes, a first aluminum nitride layer with a thickness of 500 nm was formed on the substrate layer.

2) Take out the substrate layer with the first aluminum nitride layer from the reaction chamber, and etch the nano-scale cylinder depressions on the first aluminum nitride layer to form the aluminum nitride layer with column depressions, wherein the cross-section of the cylinder depressions The diameter of the circle is 200nm, the depth of the cylinder is 300nm, and the distance between the depressions of the cylinders is 500nm;

The aluminum nitride layer of the obtained pillar depression is cleaned.

3) Put the substrate layer with the aluminum nitride layer with columnar depressions into the reaction chamber again, raise the temperature of the reaction chamber to 1350°C, control the pressure of the reaction chamber at 20mbar, and feed trimethylaluminum and 1000mL/min was passed through ammonia gas to react, and after reacting for 1 hour, a second aluminum nitride layer with a thickness of 500nm was formed on the depressed aluminum nitride layer of the column. In the above growth mode, the second aluminum nitride layer can increase the probability of lateral merging and quickly fill up the depression of the pillar.

4) When the temperature of the reaction chamber is adjusted to 1250°C, the pressure of the reaction chamber is controlled at 100mbar, and the reaction is carried out by feeding trimethylaluminum at 600ml/min and ammonia gas at 5000mL/min, and reacting for 1.5 hours. A third aluminum nitride layer with a thickness of 3000 nm is formed on the layer.

In the above steps 1)-4), the defects in the AlN growth process are largely annihilated in the nano-scale column depressions, and the defects no longer extend to the surface of the aluminum nitride film. At the same time, the nano-scale column depression can eliminate the stress in the growth process of the aluminum nitride film, so the aluminum nitride film obtained in this embodiment (the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer collection) without cracks on the surface, and the thickness of the aluminum nitride film obtained in this embodiment is 4000nm.

An XRD test was performed on the aluminum nitride film obtained above with high crystal quality and no surface cracks, wherein the half width of the (002) direction was 100 arcsec, and the half width of the (102) direction was 300 arcsec.

Example 2

The growth method of aluminum nitride film of the present invention comprises the following steps:

1) Take a 4-inch sapphire substrate, raise the temperature of the reaction chamber of the metal-organic chemical vapor deposition (MOCVD) equipment to 1200°C, control the pressure of the reaction chamber at 100mbar, and feed trimethylaluminum at 300ml/min and 10000mL/min Ammonia gas was introduced to react, and after 45 minutes, a first aluminum nitride layer with a thickness of 7500 nm was formed on the substrate layer.

2) Take out the substrate layer with the first aluminum nitride layer from the reaction chamber, etch the nano-scale regular triangular prism depressions on the first aluminum nitride layer to form a columnar depression aluminum nitride layer, wherein the regular triangular prism depressions The side length of the cross-sectional triangle is 300nm, the depth of the regular triangular prism is 500nm, and the distance between the regular triangular prism depression and the regular triangular prism depression is 500nm;

The aluminum nitride layer of the obtained pillar depression is cleaned.

3) Put the substrate layer with the aluminum nitride layer with columnar depressions into the reaction chamber again, raise the temperature of the reaction chamber to 1400°C, control the pressure of the reaction chamber at 50mbar, and feed trimethylaluminum and 1000mL/min was passed through ammonia gas for reaction, and after 0.5 hour of reaction, a second aluminum nitride layer with a thickness of 750nm was formed on the aluminum nitride layer in the depression of the column. In the above growth mode, the second aluminum nitride layer can increase the probability of lateral merging and quickly fill up the depression of the pillar.

4) When the temperature of the reaction chamber is adjusted to 1200°C, the pressure of the reaction chamber is controlled at 200mbar, and the reaction is carried out by feeding trimethylaluminum at 600ml/min and ammonia gas at 5000mL/min, and reacting for 1.5 hours. A third aluminum nitride layer with a thickness of 3000 nm is formed on the layer.

In the above steps 1)-4), the defects in the AlN growth process are largely annihilated in the nano-scale column depressions, and the defects no longer extend to the surface of the aluminum nitride film. At the same time, the nano-scale column depression can eliminate the stress in the growth process of the aluminum nitride film, so the aluminum nitride film obtained in this embodiment (the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer collection) without cracks on the surface, and the thickness of the aluminum nitride film obtained in this embodiment is 4500nm.

An XRD test was performed on the aluminum nitride film obtained above with high crystal quality and no surface cracks, wherein the half width of the (002) direction was 80 arcsec, and the half width of the (102) direction was 250 arcsec.

Example 3

The growth method of aluminum nitride film of the present invention comprises the following steps:

1) Take a 2-inch sapphire substrate, raise the temperature of the reaction chamber of the metal-organic chemical vapor deposition (MOCVD) equipment to 1200°C, control the pressure of the reaction chamber at 100mbar, and feed trimethylaluminum at 300ml/min and 10000mL/min Ammonia gas was introduced to react, and after 45 minutes, a first aluminum nitride layer with a thickness of 750 nm was formed on the substrate layer.

2) Take out the substrate layer with the first aluminum nitride layer from the reaction chamber, etch the nano-scale regular hexagonal prism depression on the first aluminum nitride layer to form a columnar depression aluminum nitride layer, wherein the regular hexagonal prism depression The side length of the regular hexagon in the cross section is 100nm, the depth of the regular hexagonal prism is 300nm, and the distance between the regular hexagonal prism depression and the regular hexagonal prism depression is 300nm;

The aluminum nitride layer of the obtained pillar depression is cleaned.

3) Put the substrate layer with the aluminum nitride layer with columnar depressions into the reaction chamber again, raise the temperature of the reaction chamber to 1450°C, control the pressure of the reaction chamber at 50mbar, and feed trimethylaluminum and Ammonia gas was injected at 1000mL/min to react, and after 1 hour of reaction, a second aluminum nitride layer with a thickness of 1000nm was formed on the depressed aluminum nitride layer of the column. In the above growth mode, the second aluminum nitride layer can increase the probability of lateral merging and quickly fill up the depression of the pillar.

4) When the temperature of the reaction chamber is adjusted to 1200°C, the pressure of the reaction chamber is controlled at 300mbar, and the reaction is carried out by feeding trimethylaluminum at 600ml/min and ammonia gas at 5000mL/min, and reacting for 2.5 hours. A third aluminum nitride layer with a thickness of 3500 nm is formed on the layer.

In the above steps 1)-4), the defects in the AlN growth process are largely annihilated in the nano-scale column depressions, and the defects no longer extend to the surface of the aluminum nitride film. At the same time, the nano-scale column depression can eliminate the stress in the growth process of the aluminum nitride film, so the aluminum nitride film obtained in this embodiment (the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer collection) without cracks on the surface, and the thickness of the aluminum nitride film obtained in this embodiment is 5250nm.

An XRD test was performed on the aluminum nitride film obtained above with high crystal quality and no surface cracks, wherein the half width of the (002) direction was 50 arcsec, and the half width of the (102) direction was 200 arcsec.

Example 4

The growth method of aluminum nitride film of the present invention comprises the following steps:

1) Take a 2-inch sapphire substrate, raise the temperature of the reaction chamber of the metal-organic chemical vapor deposition (MOCVD) equipment to 1200°C, control the pressure of the reaction chamber at 100mbar, and feed trimethylaluminum at 300ml/min and 10000mL/min Ammonia gas was introduced to react, and after 45 minutes, a first aluminum nitride layer with a thickness of 750 nm was formed on the substrate layer.

2) Take out the substrate layer with the first aluminum nitride layer from the reaction chamber, etch nanoscale cylindrical depressions, nanoscale regular triangular prism depressions and nanoscale regular hexagonal prism depressions on the first aluminum nitride layer to form columns body recessed aluminum nitride layer;

Wherein, the circular diameter of the cross section of the cylinder depression is 100nm, and the depth of the cylinder is 200nm; The side length of the regular hexagonal prism is 150nm, and the depth of the regular hexagonal prism is 300nm; the distance between each depression is 300nm;

The aluminum nitride layer of the obtained pillar depression is cleaned.

3) Put the substrate layer with the aluminum nitride layer with columnar depressions into the reaction chamber again, raise the temperature of the reaction chamber to 1450°C, control the pressure of the reaction chamber at 50mbar, and feed trimethylaluminum and Ammonia gas was injected at 1000mL/min to react, and after 1 hour of reaction, a second aluminum nitride layer with a thickness of 1000nm was formed on the depressed aluminum nitride layer of the column. In the above growth mode, the second aluminum nitride layer can increase the probability of lateral merging and quickly fill up the depression of the pillar.

4) When the temperature of the reaction chamber is adjusted to 1200°C, the pressure of the reaction chamber is controlled at 300mbar, and the reaction is carried out by feeding trimethylaluminum at 600ml/min and ammonia gas at 5000mL/min, and reacting for 2.5 hours. A third aluminum nitride layer with a thickness of 3500 nm is formed on the layer.

In the above steps 1)-4), the defects in the AlN growth process are largely annihilated in the nano-scale column depressions, and the defects no longer extend to the surface of the aluminum nitride film. At the same time, the nano-scale column depression can eliminate the stress in the growth process of the aluminum nitride film, so the aluminum nitride film obtained in this embodiment (the first aluminum nitride layer, the second aluminum nitride layer and the third aluminum nitride layer collection) without cracks on the surface, and the thickness of the aluminum nitride film obtained in this embodiment is 5250nm.

An XRD test was performed on the aluminum nitride film obtained above with high crystal quality and no surface cracks, wherein the half width of the (002) direction was 50 arcsec, and the half width of the (102) direction was 200 arcsec.

At the same time, an ultraviolet LED was prepared on the basis of the aluminum nitride film obtained in this embodiment. Among them, the chip size of the ultraviolet LED is 350 μm×350 μm, a current of 20 mA is passed through, the working voltage is 6.0 V, and the luminous brightness is 5 mW; and the life of the ultraviolet LED device is 15,000 hours.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than limiting them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: It is still possible to modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the technical solutions of the various embodiments of the present invention. scope.

Claims (10)

1. a growth method of aluminum nitride film, is characterized in that, comprises the following steps: 1) After putting the substrate layer into the reaction chamber of the growth equipment, feed trimethylaluminum and ammonia gas to form a first aluminum nitride layer with a thickness of 200-2000nm on the substrate; 2) Take out the substrate layer on which the first aluminum nitride layer is grown from the reaction chamber, and perform nanoscale pillar etching on the first aluminum nitride layer to obtain a pillar-depressed aluminum nitride layer, and the pillar There are a plurality of nano-scale column depressions in the depressed aluminum nitride layer; 3) Control the temperature of the reaction chamber to be 1300-1500° C., the pressure to be 20-100 mbar, feed trimethylaluminum and ammonia gas, and form the first aluminum nitride layer with a thickness of 200-1000 nm on the depressed aluminum nitride layer of the column. Aluminum nitride layer; 4) Control the temperature of the reaction chamber to be 1100-1400° C., the pressure to be 50-300 mbar, feed trimethylaluminum and ammonia gas, and form a third aluminum nitride layer with a thickness of 500-4000 nm on the second aluminum nitride layer. Aluminum nitride layer; Wherein, the molar flow ratio of ammonia gas and trimethylaluminum in step 3) is less than the molar flow ratio of ammonia gas and trimethylaluminum in step 4); the aluminum nitride film is the first aluminum nitride layer, a collection of second aluminum nitride layer and third aluminum nitride layer; The nanoscale pillar depressions mean that the size of each pillar depression is on the nanoscale and the distance between two adjacent pillar depressions is also on the nanometer scale. 2 . The method for growing an aluminum nitride film according to claim 1 , wherein in step 3), the molar flow ratio of the ammonia gas and trimethylaluminum is 100-1000. 3 . 3. The method for growing an aluminum nitride film according to claim 1 or 2, characterized in that, in step 4), the molar flow ratio of the ammonia gas and trimethylaluminum is 1000-5000. 4. The method for growing an aluminum nitride film according to claim 1, characterized in that, in the depressed aluminum nitride layer of the column, the distance between two adjacent nano-scale column depressions is 50-1000 nm; The nanoscale cylinder depression is selected from one or both of nanoscale cylinder depression and nanoscale prismatic cylinder depression. 5. the growth method of aluminum nitride film according to claim 4, is characterized in that, the cross-sectional diameter of described nanoscale cylinder depression is 10-1000nm, and the height of described nanoscale cylinder depression is 50-2000nm . 6. the growth method of aluminum nitride film according to claim 4, is characterized in that, the cross-section side length of described nanoscale prismatic cylinder depression is 10-1000nm, and the side length of described nanoscale prismatic cylinder depression The height is 50-2000nm. 7 . The method for growing an aluminum nitride film according to claim 1 , wherein in step 1), the temperature of the reaction chamber is controlled to be 1100-1500° C. and the pressure is 20-300 mbar. 8 . The method for growing an aluminum nitride film according to claim 7 , wherein in step 1), the molar flow ratio of the ammonia gas and trimethylaluminum is 1000-5000. 9. The method for growing an aluminum nitride film according to claim 1, wherein the substrate layer is selected from one of sapphire, silicon, silicon carbide, zinc oxide, copper and glass. 10. Application of the method for growing an aluminum nitride film according to any one of claims 1-9 in manufacturing LED epitaxial structures.