CN109888066B - LED epitaxial growth method - Google Patents

Abstract

The application discloses an LED epitaxial growth method, which sequentially comprises the following steps: processing a substrate, growing a GaN low-temperature buffer layer, growing an undoped GaN layer, growing an N-type GaN layer doped with Si, growing a light emitting layer, growing a P-type AlGaN layer, growing a P-type GaN layer doped with Mg, growing an InGaN/SiGaN superlattice layer, and cooling. According to the scheme, after the Mg-doped P-type GaN layer grows, the InGaN/SiGaN superlattice layer is introduced, the warping of the epitaxial wafer can be reduced, the qualification rate of the GaN epitaxial wafer is improved, and the luminous efficiency and the antistatic capacity of the LED are improved.

Description

LED epitaxial growth method

Technical Field

The application relates to the technical field of LED epitaxial design application, in particular to an LED epitaxial growth method.

Background

An LED (Light Emitting Diode) is a solid lighting, and because the LED has the advantages of small size, low power consumption, long service life, high brightness, environmental protection, firmness and durability, etc., the LED is accepted by consumers, and the scale of domestic LED production is gradually expanding.

The problem of large warping of an epitaxial wafer generally exists in the existing epitaxial growth technology, and particularly when epitaxial crystal growth is carried out on a 4-inch sapphire substrate, due to the problems of uneven growth of polarization fields and in-wafer materials and the like generated in the epitaxial growth process, the warping of the epitaxial wafer is larger, and the yield and the luminous efficiency of products are lower. Therefore, it is necessary to develop an LED epitaxial growth method to solve the technical problem of epitaxial wafer warpage.

Disclosure of Invention

In view of the above, the present application provides an LED epitaxial growth method, which is advantageous to eliminate the stress accumulation effect of a sapphire substrate on a GaN film and significantly increase a stress control window of an epitaxial film material by introducing an InGaN/SiGaN superlattice layer and controlling the regular gradual change of Si and In doping concentrations during the growth process, so as to reduce the warpage of an epitaxial wafer, facilitate the improvement of the yield of the GaN epitaxial wafer, and improve the light emitting efficiency and the antistatic capability of an LED.

In order to solve the technical problem, the following technical scheme is adopted:

an LED epitaxial growth method is characterized by sequentially comprising the following steps: treating a substrate, growing a GaN low-temperature buffer layer, growing an undoped GaN layer, growing an N-type GaN layer doped with Si, growing a light emitting layer, growing a P-type AlGaN layer, growing a P-type GaN layer doped with Mg, cooling,

after the growing the Mg-doped P-type GaN layer, the method further comprises the following steps: growing an InGaN/SiGaN superlattice layer,

the growing InGaN/SiGaN superlattice layer specifically comprises the following steps:

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂And a TMIn source for growing an InGaN layer with a thickness of 1nm-2nm, wherein the In doping concentration is from 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³And the flow rate of TMIn is gradually increased from 2000sccm to 2500sccm by 2sccm increase per second;

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂5sccm-10sccm SiH₄Growing a SiGaN layer with a thickness of 1nm-2nm, wherein the Si doping concentration is increased by 4E +16atoms/cm per second³From 4E +19atoms/cm³A linear ramp increase of 6E +19atoms/cm³；

And periodically growing the InGaN layer and the SiGaN layer, wherein the growth period is 7-12.

Preferably, wherein:

the processing substrate specifically comprises: h at 1000-1100 deg.C₂Introducing H of 100L/min-130L/min under the atmosphere₂And keeping the pressure of the reaction cavity at 100mbar-300mbar, and processing the sapphire substrate for 8min-10 min.

Preferably, wherein:

the growing low-temperature buffer layer specifically comprises the following steps:

reducing the temperature to 500-600 ℃, keeping the pressure of the reaction cavity at 300-600 mbar, and introducing the flow of 10000sccm-20000sccm NH₃TMGa of 50sccm-100sccm and H of 100L/min-130L/min₂And growing a GaN low-temperature buffer layer with the thickness of 20nm-40nm on the sapphire substrate.

Preferably, wherein:

the growing of the undoped GaN layer specifically comprises the following steps:

raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300mbar-600mbar, and introducing NH with the flow rate of 30000sccm-40000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂And continuously growing the undoped GaN layer of 2-4 mu m.

Preferably, wherein:

the growing of the Si-doped N-type GaN layer specifically comprises the following steps:

keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂20sccm to 50sccm SiH₄Continuously growing N-type GaN doped with Si of 3 μm-4 μm with a Si doping concentration of 5E18atoms/cm³-1E19atoms/cm³；

Keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂2sccm-10sccm SiH₄Continuously growing N-type GaN doped with Si of 200nm-400nm with the Si doping concentration of 5E17atoms/cm³-1E18atoms/cm³。

Preferably, wherein:

the growing luminescent layer is specifically as follows:

keeping the pressure of the reaction cavity at 300mbar-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm to 40sccm of TMGa, 1500sccm to 2000sccm of TMIn, 100L/min to 130L/min of N₂Growing In doped with In to a thickness of 2.5nm to 3.5nm_xGa_(1-x)An N layer, wherein x is 0.20-0.25, and the light-emitting wavelength is 450nm-455 nm;

then raising the temperature to 750-850 ℃, keeping the pressure of the reaction cavity at 300mbar-400mbar, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa, 100L/min130L/min N₂Growing a GaN layer with the thickness of 8nm-15 nm;

repeating In_xGa_(1-x)Growth of N, and then repeating growth of GaN to alternately grow In_xGa_(1-x)The N/GaN luminescent layer has a control cycle number of 7-15.

Preferably, wherein:

the growing of the P-type AlGaN layer specifically comprises the following steps:

keeping the pressure of the reaction cavity between 200mbar and 400mbar and the temperature between 900 ℃ and 950 ℃, and introducing NH with the flow rate between 50000sccm and 70000sccm₃TMGa of 30sccm-60sccm and H of 100L/min-130L/min₂TMAl of 100sccm-130sccm, Cp of 1000sccm-1300sccm₂Mg, continuously growing a P-type AlGaN layer with the thickness of 50nm to 100nm and the Al doping concentration of 1E20atoms/cm³-3E20atoms/cm³Mg doping concentration of 1E19atoms/cm³-1E20atoms/cm³。

Preferably, wherein:

the growing of the Mg-doped P-type GaN layer specifically comprises the following steps:

keeping the pressure of the reaction cavity at 400mbar-900mbar and the temperature at 950-1000 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of H₂Cp of 1000sccm-3000sccm₂Mg, continuously growing a P-type GaN layer doped with Mg with the concentration of 1E19atoms/cm and the thickness of 50nm-100nm³-1E20atoms/cm³。

Preferably, wherein:

the cooling specifically comprises the following steps:

cooling to 650-680 ℃, preserving heat for 20-30 min, then closing the heating system and the gas supply system, and cooling along with the furnace.

Compared with the prior art, the method has the following effects:

(1) according to the LED epitaxial growth method provided by the invention, by introducing the InGaN/SiGaN superlattice layer, the stress accumulation effect of the sapphire substrate on the GaN film is favorably eliminated, and the stress control window of the epitaxial film material is obviously enlarged, so that the warping of the epitaxial wafer can be reduced, the qualification rate of the GaN epitaxial wafer is favorably improved, and the luminous efficiency and the antistatic capability of the LED are improved.

(2) According to the LED epitaxial growth method provided by the invention, the dissociation rate of indium nitride can be well inhibited and the distribution nonuniformity of indium can be improved by controlling the regular gradual change of the In doping concentration and the TMIn flow rate In the process of growing the InGaN/SiGaN superlattice layer, so that the external quantum efficiency of an LED light-emitting device is improved and the light output power is increased.

(3) According to the LED epitaxial growth method provided by the invention, the doping efficiency of Si and the crystallization quality of the layer can be improved by controlling the regular gradual change of the doping concentration of Si in the process of growing the InGaN/SiGaN superlattice layer, and the upward extension of defects generated by lattice mismatch in the early stage is prevented, so that the dislocation density is reduced, the crystal quality of the whole epitaxial layer is improved, and the performances of LED brightness, electric leakage, static resistance and the like are improved.

Drawings

The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this application, illustrate embodiment(s) of the application and together with the description serve to explain the application and not to limit the application. In the drawings:

FIG. 1 is a schematic structural diagram of an epitaxial layer of an LED according to the present invention;

FIG. 2 is a schematic structural view of an epitaxial layer of an LED in a comparative example;

wherein, 1, a substrate, 2, a GaN low-temperature buffer layer, 3, an undoped GaN layer, 4, an N-type GaN layer, 5, a luminous layer, 5.1 and In_xGa_(1-x)N layer, 5.2 GaN layer, 6P type AlGaN layer, 7P type GaN layer, 8 superlattice layer, 8.1 InGaN layer, 8.2 SiGaN layer, 9 ITO layer, 10 SiO₂And (3) a layer.

Detailed Description

As used in the specification and in the claims, certain terms are used to refer to particular components. As one skilled in the art will appreciate, manufacturers may refer to a component by different names. This specification and claims do not intend to distinguish between components that differ in name but not function. In the following description and in the claims, the terms "include" and "comprise" are used in an open-ended fashion, and thus should be interpreted to mean "include, but not limited to. "substantially" means within an acceptable error range, and a person skilled in the art can solve the technical problem within a certain error range to substantially achieve the technical effect. The description which follows is a preferred embodiment of the present application, but is made for the purpose of illustrating the general principles of the application and not for the purpose of limiting the scope of the application. The protection scope of the present application shall be subject to the definitions of the appended claims.

Example 1

The invention uses MOCVD to grow the high-brightness GaN-based LED epitaxial wafer. By using high-purity H₂Or high purity N₂Or high purity H₂And high purity N₂The mixed gas of (2) is used as a carrier gas, high-purity NH₃As the N source, a metal organic source, trimethyl gallium (TMGa) as the gallium source, trimethyl indium (TMIn) as the indium source, and an N-type dopant, Silane (SiH)₄) Trimethylaluminum (TMAl) as the aluminum source and magnesium diclomelate (CP) as the P-type dopant₂Mg), substrate 1 is (001) plane sapphire, and the reaction pressure is between 70mbar and 900 mbar. The specific growth mode is as follows:

an LED epitaxial growth method, see fig. 1, sequentially includes: processing a substrate 1, growing a GaN low-temperature buffer layer 2, growing an undoped GaN layer 3, growing an N-type GaN layer 4 doped with Si, growing a luminescent layer 5, growing a P-type AlGaN layer 6, growing a P-type GaN layer 7 doped with Mg, cooling,

after the growing of the Mg-doped P-type GaN layer 7, further comprising: an InGaN/SiGaN superlattice layer 8 is grown,

the growing InGaN/SiGaN superlattice layer 8 specifically comprises the following steps:

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂And a TMIn source for growing an InGaN layer 8.1 having a thickness of 1nm-2nm, wherein the In doping concentration is from 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³And the flow rate of TMIn is gradually increased from 2000sccm to 2500sccm by 2sccm increase per second;

maintaining reaction chamber pressure 300mbar-600mbar, keeping the temperature at 750 ℃ -850 ℃, introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂5sccm-10sccm SiH₄Growing a SiGaN layer 8.2 with a thickness of 1nm-2nm, wherein the doping concentration of Si is increased by 4E +16atoms/cm per second³From 4E +19atoms/cm³A linear ramp increase of 6E +19atoms/cm³；

The InGaN layer 8.1 and the SiGaN layer 8.2 are periodically grown with a growth period of 7-12.

Compared with the prior art, the method has the following effects:

(1) according to the LED epitaxial growth method provided by the invention, by introducing the InGaN/SiGaN superlattice layer 8, the stress accumulation effect of the sapphire substrate 1 on the GaN film is favorably eliminated, and the stress control window of the epitaxial film material is obviously increased, so that the warping of the epitaxial wafer can be reduced, the qualification rate of the GaN epitaxial wafer is favorably improved, and the luminous efficiency and the antistatic capability of the LED are improved.

(2) According to the LED epitaxial growth method provided by the invention, the dissociation rate of indium nitride can be well inhibited and the distribution nonuniformity of indium can be improved by controlling the regular gradual change of the In doping concentration and the TMIn flow rate In the process of growing the InGaN/SiGaN superlattice layer 8, so that the external quantum efficiency of an LED light-emitting device is improved and the light output power is increased.

(3) According to the LED epitaxial growth method provided by the invention, the doping efficiency of Si and the crystallization quality of the layer can be improved by controlling the regular gradual change of the doping concentration of Si in the process of growing the InGaN/SiGaN superlattice layer 8, and the upward extension of defects generated by lattice mismatch in the early stage is prevented, so that the dislocation density is reduced, the crystal quality of the whole epitaxial layer is improved, and the performances of LED brightness, electric leakage, static resistance and the like are improved.

Example 2

An example of an application of the LED epitaxial growth method of the present invention is provided below, and its epitaxial structure is shown in fig. 1. MOCVD is used to grow high-brightness GaN-based LED epitaxial wafers. By using high-purity H₂Or high purity N₂Or high purity H₂And high purity N₂The mixed gas of (2) is used as a carrier gas, high-purity NH₃As the N source, a metal organic source, trimethyl gallium (TMGa) as the gallium source, trimethyl indium (TMIn) as the indium source, and an N-type dopant, Silane (SiH)₄) Trimethylaluminum (TMAl) as the aluminum source and magnesium diclomelate (CP) as the P-type dopant₂Mg), the substrate 1 is (0001) plane sapphire, and the reaction pressure is between 70mbar and 900 mbar. The specific growth mode is as follows:

step 101, processing the substrate 1:

h at 1000-1100 deg.C₂Introducing H of 100L/min-130L/min under the atmosphere₂The pressure of the reaction cavity is kept between 100mbar and 300mbar, and the thickness of the sapphire substrate 1 is processed for 8min to 10 min.

Step 102, growing a low-temperature buffer layer:

reducing the temperature to 500-600 ℃, keeping the pressure of the reaction cavity at 300-600 mbar, and introducing NH with the flow rate of 10000-20000 sccm₃TMGa of 50sccm-100sccm and H of 100L/min-130L/min₂A GaN low-temperature buffer layer 2 with a thickness of 20nm to 40nm is grown on a sapphire substrate 1.

Step 103, growing the undoped GaN layer 3:

raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300mbar-600mbar, and introducing NH with the flow rate of 30000sccm-40000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂And continuously growing the undoped GaN layer 3 with the thickness of 2-4 mu m.

Step 104, growing the Si-doped N-type GaN layer 4:

keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂20sccm to 50sccm SiH₄Continuously growing N-type GaN doped with Si of 3 μm-4 μm with a Si doping concentration of 5E18atoms/cm³-1E19atoms/cm³；

Keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂2sccm-10sccm SiH₄Continuously growing N-type GaN doped with Si of 200nm-400nm with the Si doping concentration of 5E17atoms/cm³-1E18atoms/cm³。

In the present application, 1E18 represents the 18 th power of 10, i.e. 1 x 10¹⁸By analogy, atoms/cm³Is the unit of doping concentration, the same as below.

Step 105, growing a light-emitting layer 5:

keeping the pressure of the reaction cavity at 300mbar-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm to 40sccm of TMGa, 1500sccm to 2000sccm of TMIn, 100L/min to 130L/min of N₂Growing an InxGa (1-x) N layer 5.1 doped with In with the thickness of 2.5nm-3.5nm, wherein x is 0.20-0.25, and the light-emitting wavelength is 450nm-455 nm;

then raising the temperature to 750-850 ℃, keeping the pressure of the reaction cavity at 300mbar-400mbar, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of N₂Growing a GaN layer 5.2 with the thickness of 8nm-15 nm;

repeating In_xGa_(1-x)Growth of N, and then repeating growth of GaN to alternately grow In_xGa_(1-x)The N/GaN luminescent layer has a control cycle number of 7-15.

Step 106, growing a P-type AlGaN layer 6:

keeping the pressure of the reaction cavity between 200mbar and 400mbar and the temperature between 900 ℃ and 950 ℃, and introducing NH with the flow rate between 50000sccm and 70000sccm₃TMGa of 30sccm-60sccm and H of 100L/min-130L/min₂TMAl of 100sccm-130sccm, Cp of 1000sccm-1300sccm₂Mg, continuously growing a 50nm-100nm P-type AlGaN layer 6, wherein the Al doping concentration is 1E20atoms/cm³-3E20atoms/cm³Mg doping concentration of 1E19atoms/cm³-1E20atoms/cm³。

Step 107, growing a P-type GaN layer 7 doped with Mg:

keeping the pressure of the reaction cavity at 400mbar-900mbar and the temperature at 950-1000 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of H₂Cp of 1000sccm-3000sccm₂Mg, continuously growing a P-type GaN layer 7 doped with Mg with the concentration of 1E19atoms/cm and the thickness of 50nm-100nm³-1E20atoms/cm³。

Step 108, growing an InGaN/SiGaN superlattice layer 8:

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂And a TMIn source for growing an InGaN layer 8.1 having a thickness of 1nm-2nm, wherein the In doping concentration is from 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³And the flow rate of TMIn is gradually increased from 2000sccm to 2500sccm by 2sccm increase per second;

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂5sccm-10sccm SiH₄Growing a SiGaN layer 8.2 with a thickness of 1nm-2nm, wherein the doping concentration of Si is increased by 4E +16atoms/cm per second³From 4E +19atoms/cm³A linear ramp increase of 6E +19atoms/cm³；

The InGaN layer 8.1 and the SiGaN layer 8.2 are periodically grown with a growth period of 7-12.

Step 109, cooling:

cooling to 650-680 ℃, preserving heat for 20-30 min, then closing the heating system and the gas supply system, and cooling along with the furnace.

Example 3

A conventional LED epitaxial growth method is provided below as a comparative example of the present invention.

The conventional LED epitaxial growth method comprises the following steps (an epitaxial layer structure is shown in figure 2):

1. h at 1000-1100 deg.C₂Introducing H of 100L/min-130L/min under the atmosphere₂The pressure of the reaction cavity is kept between 100mbar and 300mbar, and the thickness of the sapphire substrate 1 is processed for 8min to 10 min.

2. Reducing the temperature to 500-600 ℃, keeping the pressure of the reaction cavity at 300-600 mbar, and introducing NH with the flow rate of 10000-20000 sccm₃TMGa of 50sccm-100sccm and H of 100L/min-130L/min₂A GaN low-temperature buffer layer 2 with a thickness of 20nm to 40nm is grown on a sapphire substrate 1.

3. Raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300mbar-600mbar, and introducing NH with the flow rate of 30000sccm-40000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂And continuously growing the undoped GaN layer 3 with the thickness of 2-4 mu m.

4. Keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂20sccm to 50sccm SiH₄Continuously growing N-type GaN doped with Si of 3 μm-4 μm with a Si doping concentration of 5E18atoms/cm³-1E19atoms/cm³。

5. Keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂2sccm-10sccm SiH₄Continuously growing N-type GaN doped with Si of 200nm-400nm with the Si doping concentration of 5E17atoms/cm³-1E18atoms/cm³。

6. Keeping the pressure of the reaction cavity at 300mbar-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm to 40sccm of TMGa, 1500sccm to 2000sccm of TMIn, 100L/min to 130L/min of N₂Growing an InxGa (1-x) N layer 5.1 doped with In with the thickness of 2.5nm-3.5nm, wherein x is 0.20-0.25, and the light-emitting wavelength is 450nm-455 nm;

then raising the temperature to 750-850 ℃, keeping the pressure of the reaction cavity at 300mbar-400mbar, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of N₂Growing a GaN layer with the thickness of 8nm-15 nm;

repeating In_xGa_(1-x)Growth of N, and then repeating growth of GaN to alternately grow In_xGa_(1-x)The N/GaN light-emitting layer 5 has a control cycle number of 7-15.

7. Keeping the pressure of the reaction cavity between 200mbar and 400mbar and the temperature between 900 ℃ and 950 ℃, and introducing NH with the flow rate between 50000sccm and 70000sccm₃TMGa of 30sccm-60sccm and H of 100L/min-130L/min₂TMAl of 100sccm-130sccm, Cp of 1000sccm-1300sccm₂Mg, continuously growing a 50nm-100nm P-type AlGaN layer 6, wherein the Al doping concentration is 1E20atoms/cm³-3E20atoms/cm³Mg doping concentration of 1E19atoms/cm³-1E20atoms/cm³。

8. Keeping the pressure of the reaction cavity at 400mbar-900mbar and the temperature at 950-1000 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of H₂Cp of 1000sccm-3000sccm₂Mg, continuously growing a P-type GaN layer 7 doped with Mg with the concentration of 1E19atoms/cm and the thickness of 50nm-100nm³-1E20atoms/cm³。

9. Cooling to 650-680 ℃, preserving heat for 20-30 min, then closing the heating system and the gas supply system, and cooling along with the furnace.

On the same bench, sample 1 was prepared according to the conventional LED growth method (method of comparative example), and sample 2 was prepared according to the method described in this patent; the difference in the parameters of the epitaxial growth methods of sample 1 and sample 2 is that the present invention introduces the step of growing the InGaN/SiGaN superlattice layer 8, i.e., step 108 in example 2, after growing the Mg-doped P-type GaN layer 7, and the growth conditions for growing other epitaxial layers are the same.

Sample 1 and sample 2 were plated with an ITO layer 9 of about 150nm under the same pre-process conditions, a Cr/Pt/Au electrode of about 1500nm under the same conditions, a protective SiO2 layer 10 of about 100nm under the same conditions, then the samples were ground and cut under the same conditions into 635 μm (25mil by 25mil) chip particles, and then sample 1 and sample 2 were each picked at the same location with 100 grains and packaged into a white LED under the same packaging process. The photoelectric properties of sample 1 and sample 2 were then tested using an integrating sphere at a drive current of 350 mA.

Table 1 is a table comparing the electrical parameters of sample 1 and sample 2.

TABLE 1 comparison of electrical parameters of samples 1, 2

As can be seen from the comparison of the data in Table 2, the brightness of sample 2 is increased from 129.15Lm/w to 147.201Lm/w, the voltage is decreased from 3.17V to 3.07V, the reverse voltage is decreased from 31.86V to 30.51V, and other parameters are not changed much compared with sample 1. The following conclusions can therefore be drawn:

the LED manufactured by the growth method provided by the patent has the advantages that the voltage is reduced, the lighting effect is improved, and the brightness is obviously improved. Experimental data proves that the scheme of this patent can show the feasibility that promotes LED product light efficiency, promotes the product quality.

The warping degrees BOW value data (um) of the epitaxial wafer samples 1 and 2 are counted, the mean value of the warping degrees of the samples 2 is 4.9um, the mean value of the warping degrees of the samples 1 is 6.4um, the warping degrees of the LED epitaxial wafer samples manufactured by the method are obviously small, and the method can obviously reduce the warping degree of the epitaxial wafer and improve the product percent of pass.

According to the embodiments, the application has the following beneficial effects:

(1) according to the LED epitaxial growth method provided by the invention, by introducing the InGaN/SiGaN superlattice layer 8, the stress accumulation effect of the sapphire substrate 1 on the GaN film is favorably eliminated, and the stress control window of the epitaxial film material is obviously increased, so that the warping of the epitaxial wafer can be reduced, the qualification rate of the GaN epitaxial wafer is favorably improved, and the luminous efficiency and the antistatic capability of the LED are improved.

(2) According to the LED epitaxial growth method provided by the invention, the dissociation rate of indium nitride can be well inhibited and the distribution nonuniformity of indium can be improved by controlling the regular gradual change of the In doping concentration and the TMIn flow rate In the process of growing the InGaN/SiGaN superlattice layer 8, so that the external quantum efficiency of an LED light-emitting device is improved and the light output power is increased.

(3) According to the LED epitaxial growth method provided by the invention, the doping efficiency of Si and the crystallization quality of the layer can be improved by controlling the regular gradual change of the doping concentration of Si in the process of growing the InGaN/SiGaN superlattice layer 8, and the upward extension of defects generated by lattice mismatch in the early stage is prevented, so that the dislocation density is reduced, the crystal quality of the whole epitaxial layer is improved, and the performances of LED brightness, electric leakage, static resistance and the like are improved.

As will be appreciated by one skilled in the art, embodiments of the present application may be provided as a method, apparatus, or computer program product. Accordingly, the present application may take the form of an entirely hardware embodiment, an entirely software embodiment or an embodiment combining software and hardware aspects. Furthermore, the present application may take the form of a computer program product embodied on one or more computer-usable storage media (including, but not limited to, disk storage, CD-ROM, optical storage, and the like) having computer-usable program code embodied therein.

The foregoing description shows and describes several preferred embodiments of the present application, but as aforementioned, it is to be understood that the application is not limited to the forms disclosed herein, but is not to be construed as excluding other embodiments and is capable of use in various other combinations, modifications, and environments and is capable of changes within the scope of the inventive concept as expressed herein, commensurate with the above teachings, or the skill or knowledge of the relevant art. And that modifications and variations may be effected by those skilled in the art without departing from the spirit and scope of the application, which is to be protected by the claims appended hereto.

Claims (9)

1. An LED epitaxial growth method is characterized by sequentially comprising the following steps: treating a substrate, growing a GaN low-temperature buffer layer, growing an undoped GaN layer, growing an N-type GaN layer doped with Si, growing a light emitting layer, growing a P-type AlGaN layer, growing a P-type GaN layer doped with Mg, cooling,

after the growing the Mg-doped P-type GaN layer, the method further comprises the following steps: growing an InGaN/SiGaN superlattice layer,

the growing InGaN/SiGaN superlattice layer specifically comprises the following steps:

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂And a TMIn source for growing an InGaN layer with a thickness of 1nm-2nm, wherein the In doping concentration is from 5E +20atoms/cm³Gradually reduced to 4E +20atoms/cm³And the flow rate of TMIn is gradually increased from 2000sccm to 2500sccm by 2sccm increase per second;

keeping the pressure of the reaction cavity at 300mbar-600mbar and the temperature at 750-850 ℃, and introducing TMGa with the flow rate of 10sccm-20sccm and N with the flow rate of 100L/min-130L/min₂5sccm-10sccm SiH₄Growing a SiGaN layer with a thickness of 1nm-2nm, wherein the Si doping concentration is increased by 4E +16atoms/cm per second³From 4E+19atoms/cm³A linear ramp increase of 6E +19atoms/cm³；

And periodically growing the InGaN layer and the SiGaN layer, wherein the growth period is 7-12.

2. LED epitaxial growth method according to claim 1,

the processing substrate specifically comprises: h at 1000-1100 deg.C₂Introducing H of 100L/min-130L/min under the atmosphere₂And keeping the pressure of the reaction cavity at 100mbar-300mbar, and processing the sapphire substrate for 8min-10 min.

3. LED epitaxial growth method according to claim 1,

the GaN low-temperature buffer layer comprises the following specific steps:

reducing the temperature to 500-600 ℃, keeping the pressure of the reaction cavity at 300-600 mbar, and introducing NH with the flow rate of 10000-20000 sccm₃TMGa of 50sccm-100sccm and H of 100L/min-130L/min₂And growing a GaN low-temperature buffer layer with the thickness of 20nm-40nm on the sapphire substrate.

4. LED epitaxial growth method according to claim 1,

the growing of the undoped GaN layer specifically comprises the following steps:

raising the temperature to 1000-1200 ℃, keeping the pressure of the reaction cavity at 300mbar-600mbar, and introducing NH with the flow rate of 30000sccm-40000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂And continuously growing the undoped GaN layer of 2-4 mu m.

5. LED epitaxial growth method according to claim 1,

the growing of the Si-doped N-type GaN layer specifically comprises the following steps:

keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂20sccm to 50sccm SiH₄Hand holdingContinuously growing Si-doped N-type GaN with the doping concentration of 5E18atoms/cm and the doping concentration of 3-4 μm³-1E19atoms/cm³；

Keeping the pressure and the temperature of the reaction cavity unchanged, and introducing NH with the flow rate of 30000sccm-60000sccm₃TMGa of 200sccm-400sccm, H of 100L/min-130L/min₂2sccm-10sccm SiH₄Continuously growing N-type GaN doped with Si of 200nm-400nm with the Si doping concentration of 5E17atoms/cm³-1E18atoms/cm³。

6. LED epitaxial growth method according to claim 1,

the growing luminescent layer is specifically as follows:

keeping the pressure of the reaction cavity at 300mbar-400mbar and the temperature at 700-750 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm to 40sccm of TMGa, 1500sccm to 2000sccm of TMIn, 100L/min to 130L/min of N₂Growing In doped with In to a thickness of 2.5nm to 3.5nm_xGa_(1-x)An N layer, wherein x is 0.20-0.25, and the light-emitting wavelength is 450nm-455 nm;

then raising the temperature to 750-850 ℃, keeping the pressure of the reaction cavity at 300mbar-400mbar, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of N₂Growing a GaN layer with the thickness of 8nm-15 nm;

repeating In_xGa_(1-x)Growth of N, and then repeating growth of GaN to alternately grow In_xGa_(1-x)The N/GaN luminescent layer has a control cycle number of 7-15.

7. LED epitaxial growth method according to claim 1,

the growing of the P-type AlGaN layer specifically comprises the following steps:

keeping the pressure of the reaction cavity between 200mbar and 400mbar and the temperature between 900 ℃ and 950 ℃, and introducing NH with the flow rate between 50000sccm and 70000sccm₃TMGa of 30sccm-60sccm and H of 100L/min-130L/min₂TMAl of 100sccm-130sccm, Cp of 1000sccm-1300sccm₂Mg, continuously growing a P-type AlGaN layer with the thickness of 50nm to 100nm and the Al doping concentration of 1E20atoms/cm³-3E20atoms/cm³Mg doping concentration of 1E19atoms/cm³-1E20atoms/cm³。

8. LED epitaxial growth method according to claim 1,

the growing of the Mg-doped P-type GaN layer specifically comprises the following steps:

keeping the pressure of the reaction cavity at 400mbar-900mbar and the temperature at 950-1000 ℃, and introducing NH with the flow rate of 50000sccm-70000sccm₃20sccm-100sccm of TMGa and 100L/min-130L/min of H₂Cp of 1000sccm-3000sccm₂Mg, continuously growing a P-type GaN layer doped with Mg with the concentration of 1E19atoms/cm and the thickness of 50nm-100nm³-1E20atoms/cm³。

9. LED epitaxial growth method according to claim 1,

the cooling specifically comprises the following steps:

cooling to 650-680 ℃, preserving heat for 20-30 min, then closing the heating system and the gas supply system, and cooling along with the furnace.

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