A manufacturing method for preventing pollution of cutting of out-of-plane electrodes of a gallium arsenide-based LED die

Abstract

The application relates to a manufacturing method for preventing pollution caused by cutting of a gallium arsenide-based LED tube core out-of-plane electrode, and belongs to the technical field of semiconductor processing. The method steps are as follows: (1) placing a thinned wafer on a bearing disc, and pressing the wafer by using a tablet of the bearing disc; (2) respectively installing spring clamps on tray holes at opposite positions of the bearing disc, and pressing the wafer on the bearing disc by using the spring clamps; (3) placing the bearing disc and a planet carrier self-provided at the lower side of the bearing disc in a chamber of an evaporation device, rotating the planet carrier, and performing evaporation operation after determining that the wafer is stably installed. The application assists the bearing disc in pressing the wafer by using the separately designed spring clamps, only a very small area needs to be shielded during use, wafer scratches are avoided, wafer warping is avoided, pollution in the wafer evaporation process is reduced, and the out-of-plane electrode leakage after the evaporation is reduced.

Description

TECHNICAL FIELD

[0001] The application relates to a manufacturing method for preventing pollution caused by cutting of out-of-plane electrodes of a gallium arsenide-based LED (Light Emitting Diode) die, and belongs to the technical field of semiconductor processing. BACKGROUND

[0002] LED is the abbreviation of Light Emitting Diode in English, which is a common semiconductor capable of converting electrical energy into light energy, mainly made of group III-IV compounds such as GaAs (gallium arsenide), GaP (gallium phosphide), GaAsP (gallium arsenide phosphide) and other semiconductors. The most core of the light emitting diode is the P-N junction, which forms energy through the recombination of electrons and holes, and the energy is radiated in the form of light. Taking the preparation of a gallium arsenide-based LED die as an example, the preparation of the die mainly includes the following processes: first, an epitaxial layer is prepared on a corresponding substrate; then, a wafer with an epitaxial layer is processed into a single die through a die process. The manufacturing process of the die structure is usually as follows: epitaxial wafer cleaning--current expansion layer preparation--P-face electrode preparation--substrate thinning--N-face electrode preparation--die cutting--optoelectronic parameter testing--grading into the warehouse.

[0003] With the increasing integration and complexity of semiconductor chips, heat dissipation has become a key factor affecting the performance and service life of the chips. A large amount of heat is released during the operation of the chip, generating high internal stress at the back of the chip. The thicker the chip, the greater the internal stress between the layers. At the same time, the thinned chip can greatly reduce the packaging volume, reduce the processing amount during packaging scribing, avoid defects such as edge collapse and corner collapse during scribing, and reduce the chip breakage rate. Therefore, wafer thinning process is used in almost all types of LED chip preparation processes to polish the back material of the wafer after the functional design.

[0004] In actual production process, the wafer is thinned and then the out-of-plane electrode is evaporated. In the electron beam evaporation equipment used in current production, the wafer is usually fixed on the bearing disc of the planet carrier by three wafer clamps, and the planet carrier rotates after the evaporation starts. However, after the wafer is thinned, the wafer warps greatly due to the thin thickness, which can be as high as millimeter level. If the temperature is as high as several hundred degrees during evaporation, the wafer warping during evaporation will become more serious. There is a large gap between the edge of the wafer and the bearing disc during evaporation, and the adhesion between the two is poor, which causes the metal to diffuse to the light-emitting surface along the gap during the evaporation of the back electrode, resulting in chip appearance pollution, and even chip leakage, which can only be handled by downgrading, thus causing yield reduction and cost loss.

[0005] At present, reducing the pollution of the thinned chip is an important issue in the production process of the LED. However, with the increasing integration of the chip, the chip is getting thinner and thinner, and how to reduce the chip pollution and scratches caused by the evaporation of the out-of-plane electrode after thinning, and reduce the yield reduction and cost loss caused thereby has become a key problem.

[0006] Chinese patent document CN 116190505A discloses a preparation method of a GaAs-based LED chip, which comprises the following steps: growing an epitaxial layer on a GaAs substrate, and coating a positive photoresist on the surface of the epitaxial layer to form a plurality of positive photoresist layers by photolithography, depositing a P-face Au film on the surface of the positive photoresist layer, forming a P electrode in the gap between the plurality of positive photoresist layers, retaining the positive photoresist, directly thinning the GaAs substrate, and the thickness of the positive photoresist is greater than the thickness of the P electrode; and placing the prepared chip under a photolithography machine for full-area light exposure, and then using a positive photoresist developer for cleaning, so as to ensure that the P electrode is not lost or contaminated during the preparation of the N electrode. However, the method involves multiple steps such as photolithography, exposure, development, cleaning, and the operation is complicated; the photoresist is used during the evaporation of the out-of-plane electrode, which is easy to contaminate the evaporation chamber; in addition, if the electrode is grown at high temperature, the photoresist will be solidified, which makes it difficult to remove the photoresist. SUMMARY

[0007] In view of the deficiencies of the prior art, the present application provides a manufacturing method for preventing cutting pollution of the out-of-plane electrode of a gallium arsenide-based LED die, which uses a separately designed spring clamp to press the wafer, only needs to block a very small area during use, does not cause scratches on the wafer, avoids warping of the wafer, reduces pollution during the evaporation process of the wafer, and reduces the leakage of the out-of-plane electrode.

[0008] The technical scheme of the present application is as follows:

[0009] A manufacturing method for preventing cutting pollution of the out-of-plane electrode of a gallium arsenide-based LED die, which comprises the following steps:

[0010] (1) Place the thinned wafer on the carrier plate, and press the wafer with the self-contained wafer press of the carrier plate;

[0011] (2) Install a spring clamp on the tray hole at the opposite position of the carrier plate, and press the wafer on the carrier plate with the spring clamp;

[0012] (3) Place the carrier plate and the planetary gear attached to the lower side of the carrier plate in the evaporation equipment chamber, rotate the planetary gear, and after determining that the wafer is stably installed, perform the evaporation operation.

[0013] According to the application, preferably, in step (2), the spring clip comprises a main body, the main body is helical, a fastening rod is vertically arranged at the top of the main body, and a pressing rod is vertically arranged at the bottom of the main body, the pressing rod is an L-shaped rod, the top of the L-shaped rod is horizontally arranged on the upper side of the main body, the top horizontal rod of the L-shaped rod is inclined downward, and an arc-shaped rod is arranged at the end of the top horizontal rod of the L-shaped rod, the arc-shaped rod is arranged opposite to the fastening rod, and the arc-shaped rod can avoid the tip from contacting the wafer and damaging the wafer.

[0014] According to the application, further preferably, the spring clip is made of stainless steel wire, the diameter of the wire is 700 microns to 1 millimeter, and the diameter of the main body of the spring clip is 7 millimeters to 1 centimeter.

[0015] According to the application, preferably, in step (2), when the spring clip is used, the spring clip is arranged in a tray hole on one side of the bearing disc, the top horizontal rod of the pressing rod of the spring clip is arranged on the upper side of the bearing disc, the main body of the spring clip is arranged on the lower side of the bearing disc, the wafer is pressed by the top horizontal rod of the pressing rod and the main body, the fastening rod is attached to one side of the tray hole, and the relative fixation of the spring clip and the bearing disc is realized.

[0016] The application has the following advantages:

[0017] 1. The bearing disc of the evaporation equipment is processed, the area of the wafer back surface that is shielded is controlled, the warping degree of the thinned wafer on the bearing disc is greatly reduced, and the pollution phenomenon caused by the evaporation of the out-of-plane electrode after thinning is improved. The application only needs to prepare a spring clip with a special structure, only needs to shield a very small area, and can press the wafer without causing scratches, avoid wafer warping, reduce wafer evaporation pollution, and reduce the out-of-plane electrode leakage after thinning.

[0018] Although the use of the spring clip shields a very small area of the wafer, the wafer in the shielded area is sucked and removed in the subsequent sorting process. However, the number of dies discarded due to the shielding of the spring clip is far less than the number of dies lost due to the pollution of the light-emitting surface. Overall, the use of the spring clip effectively improves the yield of the product and greatly reduces the downgrade ratio of the product.

[0019] 2. The diameter of the spring clip wire is designed separately. If the stainless steel wire is thick, the wafer back surface is blocked, and the deposition area of the electrode is reduced. If the stainless steel wire is thin, the pressing force is insufficient, and the spring clip cannot reduce pollution.

[0020] 3. The process method designed by the application is simple to operate, reusable, low in cost, high in efficiency, and can be applied in a large scale in the production process, and is suitable for the evaporation process of all LED die thinning. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 The figure is a state diagram of the spring clip of the application.

[0022] Figure 2 This is a schematic diagram of the spring clip structure of the present invention;

[0023] The components include: 1. Spring clip; 2. Main body; 3. Fastening rod; 4. Pressing rod; 5. Arc rod; 6. Bearing plate; 7. Tray hole; 8. Wafer; 9. Pressing plate. Detailed Implementation

[0024] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0025] Example 1:

[0026] like Figure 1 As shown, this embodiment provides a method for preventing contamination during the cutting of the opposite-plane electrodes of a gallium arsenide-based LED die. The steps are as follows:

[0027] (1) TCL is grown on the surface of a wafer with an epitaxial layer using conventional processes, and the TCL covers the entire wafer surface; a photoresist mask pattern is made on the wafer surface with the TCL by spin coating, exposure, development and other steps; conventional P-side metal electrodes are grown by electron beam evaporation, and patterned metal electrodes are made by peeling; then, the wafer is thinned. The above wafer preparation process is an existing process. The thinned wafer 8 is placed on the carrier disk 6, and the wafer 8 is pressed by the clamping sheet 9 on the carrier disk 6.

[0028] (2) Install spring clips 1 on the tray holes 7 at opposite positions on the carrier disk 6, and use the spring clips 1 to press the wafer 8 on the carrier disk;

[0029] (3) Place the carrier plate 6 and its lower planetary carrier in the vapor deposition equipment chamber, rotate the planetary carrier, and after confirming that the wafer is installed securely, perform vapor deposition. After vapor deposition is completed, cut, test, and sort the wafers into the warehouse in sequence to complete the production of the core.

[0030] The vapor deposition equipment used in this invention is an electron beam evaporation stage, and the carrier plate and planetary carrier are existing supporting equipment.

[0031] In step (2), the spring clip 1 includes a main body 2, which is spiral-shaped. A fastening rod 3 is vertically arranged at the top of the main body 2, and a pressing rod 4 is vertically arranged at the bottom of the main body 2. The pressing rod 4 is an L-shaped rod, with the top of the L-shaped rod horizontally located on the upper side of the main body. The top horizontal bar of the L-shaped rod is inclined downward, and an arc-shaped rod 5 is arranged at the end of the top horizontal bar of the L-shaped rod. The arc-shaped rod 5 is arranged opposite to the fastening rod 3. The arc-shaped rod can prevent the tip from contacting the wafer and avoid wafer damage.

[0032] The spring clip 1 is made of stainless steel wire with a wire diameter of 700 micrometers to 1 millimeter, and the main body of the spring clip has a diameter of 7 millimeters to 1 centimeter.

[0033] In use, the spring clip 1 is placed in the tray hole on one side of the carrier plate, the top horizontal bar of the pressing rod of the spring clip is arranged on the upper side of the carrier plate, the main body of the spring clip is arranged on the lower side of the carrier plate, the wafer is pressed by the cooperation of the top horizontal bar of the pressing rod and the main body, the fastening rod is attached to one side of the tray hole, and the relative fixation of the spring clip and the carrier plate is realized.

[0034] The above merely describes the preferred embodiments of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

[0035] The above describes the specific embodiments of the present application in combination with the drawings, but is not intended to limit the protection scope of the present application. It should be understood by those skilled in the art that various modifications or changes made on the basis of the technical solutions of the present application without creative labor are still within the protection scope of the present application.

Claims

1. A method for preventing contamination during the cutting of out-of-plane electrodes in gallium arsenide-based LED dies, characterized in that, The steps are as follows: (1) Place the thinned wafer on the carrier tray and use the clamping plate on the carrier tray to hold the wafer in place; (2) Install spring clips on the tray holes at the opposite positions of the carrier tray, and use the spring clips to press the wafers on the carrier tray; The spring clip includes a main body, which is spiral-shaped. A fastening rod is vertically installed at the top of the main body, and a pressing rod is vertically installed at the bottom of the main body. The pressing rod is an L-shaped rod, with the top of the L-shaped rod horizontally positioned on the upper side of the main body. The top horizontal bar of the L-shaped rod is inclined downwards, and an arc-shaped rod is installed at the end of the top horizontal bar of the L-shaped rod. The arc-shaped rod is positioned opposite to the fastening rod. The spring clip is made of stainless steel wire with a wire diameter of 700 micrometers to 1 millimeter. The diameter of the main body of the spring clip is 7 millimeters to 1 centimeter. (3) Place the carrier plate and its lower planetary carrier in the vapor deposition equipment chamber, rotate the planetary carrier, and after confirming that the wafer is securely installed, perform the vapor deposition operation.

2. The manufacturing method for preventing contamination during the cutting of the opposite-plane electrodes of a gallium arsenide-based LED die as described in claim 1, characterized in that, In step (2), when using the spring clip, place the spring clip in the tray hole on one side of the carrier plate. The top horizontal bar of the pressing rod of the spring clip is set on the upper side of the carrier plate, and the main body of the spring clip is set on the lower side of the carrier plate. The wafer is pressed by the top horizontal bar of the pressing rod and the main body, and the fastening rod is attached to one side of the tray hole to achieve relative fixation between the spring clip and the carrier plate.

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