Method for improving bar dissociation yield through substrate flat edge positioning

Abstract

The invention discloses a method for improving bar dissociation yield through substrate flat edge positioning, and the method comprises the following steps: growing gallium nitride on a self-supporting gallium nitride substrate by using an HVPE technology, and carrying out the cutting, thinning and polishing of the grown gallium nitride; the positions of a C surface and a plurality of m surfaces are found out through XRD, the m surface with the smallest included angle between the m surface and the C surface is found out from the m surfaces, and the m surface is parallel to the flat edge of the self-supporting gallium nitride substrate; a gallium nitride substrate long laser device is used for epitaxy, and laser cutting and mechanical dissociation methods are used for dissociation on the front surface of a sample, so that a high-quality bar cavity surface is obtained. The method has the beneficial effects that the included angle between the C surface and the m surface can be reduced, the gravitation between the m surfaces is also reduced, a dissociation surface is easily formed during cracking along the m surface, and the dissociation is smoother, so that the success rate of bar dissociation is greatly improved, a higher-quality cavity surface can be obtained, the stability and the yield of the gallium nitride laser are further improved, and the production cost is reduced. And production and manufacturing of the gallium nitride laser are facilitated.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor optoelectronic device technology, and in particular to a method for improving the bar dissociation yield rate by positioning the flat edge of a substrate. Background Art

[0002] Gallium nitride laser is a semiconductor laser that uses gallium nitride material as the working medium. Compared with traditional semiconductor lasers, gallium nitride lasers have a wider spectral range, better stability and higher electro-optical conversion efficiency. Its main working principle is based on the band structure of semiconductors and the transport characteristics of carriers. When a forward voltage is applied to the gallium nitride material, carriers (electrons and holes) move freely in the material and generate photons through injection and recombination processes. These photons are reflected back and forth in the resonant cavity between the reflectors, continuously amplified, and finally form laser output. Its technical advantages are that the wavelength range is from 350 nanometers in ultraviolet to 550 nanometers in green light, which enables it to cover a wider range of application needs; with high electron saturation drift velocity, wide band gap and high thermal stability, gallium nitride lasers show high stability and reliability in long-term operation; with high electro-optical conversion efficiency, it reduces heat generation, thereby improving overall work efficiency. Gallium nitride lasers have the advantages of small size, long life, and high efficiency. Their wavelength range covers visible light and ultraviolet bands. Their application scenarios include laser display, industrial processing, laser lighting, laser communications, laser medical treatment and many other fields. In recent years, the overall market demand has shown a relatively high compound growth trend.

[0003] As a very important process technology in the preparation of GaN lasers, the quality of the cavity surface obtained after bar cleavage will directly affect the threshold current and output power of the GaN laser, which will further affect the stability and reliability of the GaN laser. Therefore, improving the success rate of bar dissociation is related to the production and manufacturing of GaN lasers.

[0004] For example, China's invention patent authorization announcement number CN109510061B discloses a method for cleaving gallium nitride laser bars, which deeply etches wide cleavage guide grooves and V-shaped narrow guide grooves to allow the etching depth to penetrate the entire epitaxial layer, and then performs back thinning, etching, and electrode growth processes, and then cleaves the front side of the sample by laser cutting and Loomis cleavage machine rollers to obtain the bar cavity surface. The innovation of this method focuses on the preparatory work for bar dissociation, rather than the process of bar dissociation. The process is cumbersome and the cost is high. Summary of the invention

[0005] The technical problem to be solved by the present invention is that the existing method for dissociating gallium nitride laser bars is complicated and costly, and therefore a method for improving the bar dissociation yield by positioning the flat edge of the substrate is provided.

[0006] The technical solution of the present invention is: a method for improving the bar dissociation yield by positioning the flat edge of the substrate, comprising the following steps: using a self-supporting gallium nitride substrate to grow gallium nitride using the HVPE technology, cutting, thinning and polishing the grown gallium nitride; using XRD to find the positions of the C-plane and multiple m-planes, and finding the m-plane with the smallest angle between the m-plane and the C-plane among the multiple m-planes, and the m-plane is parallel to the flat edge of the self-supporting gallium nitride substrate; using a gallium nitride substrate to grow laser epitaxy, and using laser cutting and mechanical dissociation methods to dissociate on the front side of the sample, thereby obtaining high-quality bar cavity surfaces.

[0007] The self-supporting gallium nitride substrate described in the above scheme is made of a sapphire substrate through epitaxy, coating and photolithography processes.

[0008] The sapphire substrate in the above solution is cut before epitaxy, and the deviation angle between the c-plane and the m-plane is 0.5°.

[0009] The beneficial effect of the present invention is that the angle between the C-plane and the m-plane can be reduced, and the attraction between the m-planes is also reduced, so that a dissociation plane is easily formed when cracking along the m-plane, and the dissociation is smoother, thereby greatly improving the success rate of bar dissociation and obtaining a better quality cavity surface, further improving the stability and yield of the gallium nitride laser, and facilitating the production and manufacturing of the gallium nitride laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a flow chart of obtaining high-quality noodle cavity surface of the present invention;

[0011] Figure 2 It is a regular hexagonal prism stereogram in the present invention;

[0012] Figure 3 It is a top view and a side view of a regular hexagonal prism in the present invention;

[0013] Figure 4 is the dihedral angle formula;

[0014] Figure 5 This is a flow chart for finding the m2 surface using XRD;

[0015] In the figure, 100, c-plane; 100a, c-plane; 101, m-plane; 101a, m1 plane; 101b, m2 plane; 101c, m3 plane; 102, GaN102 plane peak; 103, GaN 002 plane Phi = 0° Omega peak; 104, GaN 002 plane Phi = 90° Omega peak; 105, GaN 002 plane Phi = 180° Omega peak; 106, GaN 002 plane Phi = 270° Omega peak; 107, flat edge angle. DETAILED DESCRIPTION

[0016] The technical solutions in the embodiments of the present invention are described clearly and completely below in conjunction with the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments by ordinary technicians in this field without creative work are within the protection scope of the present invention.

[0017] The general steps of a method for improving the bar dissociation yield by positioning the flat edge of the substrate are as follows: Figure 1 As shown:

[0018] 1. Provide sapphire substrate;

[0019] 2. Using sapphire substrate to make a self-supporting gallium nitride substrate;

[0020] 3. Growing GaN using a self-supporting substrate;

[0021] 4. Find the optimal m-plane of the GaN substrate;

[0022] 5. Use gallium nitride substrate to grow laser epitaxy;

[0023] 6. Obtain the cavity surface of the strip by laser cutting and mechanical dissociation.

[0024] Combine the following Figures 2 to 5 , the method for dissociating the strips of the present invention is described in detail.

[0025] A sapphire substrate is provided, having an m-plane 101, a c-plane 100, an m1-plane 101a, a c-plane 100a, an m2-plane 101b, and an m3-plane 101c. When the sapphire substrate is cut, the deviation angle of the c-plane to the m-plane is about 0.5°. A layer of gallium nitride is grown on the sapphire substrate by the MOCVD method, and then a metal is plated on it as a mask, followed by photolithography and etching to obtain a self-supporting gallium nitride substrate. The self-supporting gallium nitride substrate is grown on the gallium nitride by the HVPE technology, and HCl and Ga are reacted to generate GaCl3, and GaCl3 and NH3 are reacted to generate GaN. This GaN is the required gallium nitride. The obtained GaN is processed by cutting, thinning, polishing and other processes to make a gallium nitride substrate. The gallium nitride substrate needs to be leveled, and the angle between the m-plane and the c-plane is calculated as follows: Figure 2 As shown, a three-dimensional coordinate system is established for the regular hexagonal prism:

[0026] m1 face normal vector c-plane normal vector The angle between the m1 plane and the c plane is known to be 89.5°.

[0027] m2 face normal vector c-plane normal vector Calculate using the dihedral angle formula, such as Figure 4 As shown,∴ ∵ ∴θ=90.249998°, ∴the angle between the m2 plane and the c plane is 89.75°.

[0028] m3 face normal vector Similarly, the angle between the m3 plane and the c plane is also 89.75°.

[0029] Therefore, the angle between the m2 / m3 surface and the c surface is the smallest, and the m2 / m3 surface can be used as a flat edge.

[0030] Use XRD to find the m1 face. There are 6 m faces for a regular hexagonal prism. Once you find an m face, you can find other m faces by rotating 60°. For example, you can find the m2 face by rotating 60°. Figure 5 As shown, the operation is as follows: fix gallium nitride on the XRD carrier and scan the Z axis for calibration; adjust the position of GaN102 surface, roughly scan Phi 60°, finely scan Phi 2°, and record the peak at 102; adjust the position of GaN002 surface, scan Omega at Phi 0°, record the peak at 103, and record the Omega peak at 104, 105, and 106 for Phi 90°, Phi 180°, and Phi270° respectively; calculate to get 107, and then draw the flat edge position.

Claims

1. A method for improving the bar dissociation yield by positioning the flat edge of the substrate, characterized by: The following steps are involved: GaN is grown on a self-supporting GaN substrate using HVPE technology, and the grown GaN is cut, thinned and polished; XRD is used to find the positions of the C-plane and multiple m-planes, and the m-plane with the smallest angle between the m-plane and the C-plane is found among the multiple m-planes, and this m-plane is parallel to the flat edge of the self-supporting GaN substrate; laser epitaxy is grown on the GaN substrate, and laser cutting and mechanical dissociation methods are used to dissociate the sample on the front side, thereby obtaining high-quality bar-strip cavity surfaces.

2. The method for improving the bar dissociation yield by positioning the flat edge of the substrate as claimed in claim 1, characterized in that: The self-supporting gallium nitride substrate is made of a sapphire substrate through epitaxy, coating and photolithography processes.

3. The method for improving the bar dissociation yield by positioning the flat edge of the substrate as claimed in claim 2, characterized in that: The sapphire substrate is cut before epitaxy, and the offset angle between the c-plane and the m-plane is 0.5°.

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