A method for improving post-polish wafer substrate debris adhesion

Abstract

The present application relates to a kind of methods for improving wafer substrate chip adhesion after grinding, belong to the technical field of semiconductor device processing. The wafer after thinning is first put into the device, and the device includes a micro-porous disc and a rotating disc. When removing the chip, the wafer is adsorbed on the micro-porous disc, then the wafer is contacted with the conical soft plastic on the lower side of the rotating disc. Sodium carbonate solution is injected into the gap between the micro-porous disc and the rotating disc. The rotating disc rotates, and the conical soft plastic is used to remove the chip surface debris. Then the wafer is further cleaned. The present application can quickly and effectively remove the debris adhered to the surface of the substrate after grinding and thinning, increase the adhesion of the substrate and the evaporated metal, the process is simple, easy to operate, efficient, and widely applicable to GaAs gallium arsenide-based, silicon-based and other LED substrate wafer preparation.

Description

TECHNICAL FIELD

[0001] The present application relates to a method for improving the adhesion of wafer substrate debris after grinding, belonging to the technical field of semiconductor device processing. BACKGROUND

[0002] At present, the substrate materials for manufacturing semiconductor light emitting diodes mainly include the following: sapphire (Al2O3), silicon (Si), silicon carbide (SiC), gallium arsenide (GaAs), AlN and ZnO.

[0003] Silicon and gallium arsenide substrates are currently mainly applied in the manufacturing of red, yellow and orange light emitting diodes. Gallium arsenide belongs to group III-V compound semiconductors, has better electronic properties than silicon, produces less noise at high frequencies, and is a direct bandgap material with good light emitting properties.

[0004] Regardless of the substrate, thinning of the substrate is essential in the process of manufacturing LED dies (required for subsequent cutting of the dies), but due to the material properties of silicon and gallium arsenide substrates, a large number of small-sized debris will be generated on the surface of the GaAs substrate during the conventional thinning process. The debris adheres to the surface of the substrate and is difficult to remove by conventional cleaning methods. In addition, the total thickness of the wafer after thinning is generally between 50-200 μm, and the size is relatively thin. Over-cleaning can easily cause cracks and loss of fragments. However, the manufacturing of N-face electrodes of silicon and GaAs-based LEDs must be completed on the thinned substrate surface. Therefore, it is necessary to minimize the generation of residual debris after thinning and quickly and effectively remove the debris on the surface of the substrate after thinning. For this reason, the present application is proposed. SUMMARY

[0005] In view of the deficiencies of the prior art, the present application provides a method for improving the adhesion of wafer substrate debris after grinding, which can quickly and effectively remove the adhered debris on the surface of the substrate after grinding and thinning, increase the adhesion of the substrate and the evaporated metal, is simple in process, convenient to operate, high in efficiency, and widely applicable to GaAs gallium arsenide-based, silicon-based and other LED substrate wafer manufacturing.

[0006] The technical scheme of the present application is as follows:

[0007] A method for improving the adhesion of wafer substrate debris after grinding, comprising the following steps:

[0008] Step (1): heat the heating table and the waxing machine to a set temperature;

[0009] Step (2): place the ceramic disc on the heating table for preheating, with the mark line of the ceramic disc facing upwards. When the display temperature reaches the set temperature, allow a floating range of 105±5℃, and evenly apply wax on each corresponding position of the ceramic disc;

[0010] Step (3): sequentially attach the wafers to the ceramic disc;

[0011] Step (4): After the patch is completed, the ceramic disc is placed on the waxing machine, and the dust-free paper is placed on the ceramic disc to cover all the wafers. After the covering, the dust-free paper should not be slid to prevent the wafers from sliding.

[0012] Step (5): The wafer starts to be pressed on the waxing machine, and the pressing time is 4-7 min. After completion, start cooling. When the temperature is lower than 30℃, take out the ceramic disc.

[0013] Step (6): Peel off the dust-free paper, and use ethanol and dust-free paper to wipe the wafer surface to remove the residual wax on the wafer surface to prevent errors during rough grinding and thickness measurement.

[0014] Step (7): Use the grinding equipment to grind the substrate surface of the wafer, and thin the thickness to 120um.

[0015] Step (8): Place the thinned wafer on the debris removal device, and use the debris removal device to remove the debris on the wafer surface.

[0016] Step (9): Place the debris-removed wafer on the heating table. When the display temperature reaches the set temperature and the wax is melted, use a blade to gently extend under the wafer along the edge of the wafer. Slowly pry the wafer up along the edge, and use tweezers to pick up and put into the wafer box. Then, the wafer box is conveyed to the cleaning station.

[0017] Step (10): Take out the wafer from the wafer box, and sequentially place it into the first and second wax removal liquid beakers for cleaning to improve the wax removal effect.

[0018] Step (11): Place the wax-removed wafer into the acetone tank, and slowly immerse it to avoid wafer cracking.

[0019] Step (12): Take out the wafer from the acetone tank, and perform ethanol cleaning.

[0020] Step (13): After the ethanol cleaning is completed, place the wafer into the hot nitrogen drying machine for drying.

[0021] Step (14): Perform N-face metal evaporation on the dried wafer, and the evaporation metal is Ni / Au / Ge / Ni / Au laminated metal.

[0022] According to the application, preferably, in step (1), the temperature of the heating table is set to 105℃, and the waxing machine is opened to heat to 100℃.

[0023] According to the application, preferably, in step (6), when wiping, ethanol is sprayed on the dust-free paper, and then the dust-free paper is used for wiping to prevent the wafer edge wax layer from being dissolved when the ethanol is directly sprayed on the wafer, which pollutes the wafer or causes the wafer to be blown away.

[0024] According to the application, preferably, in step (8), the dandruff removing device comprises a microporous disc and a rotating disc, a plurality of through holes are arranged in the microporous disc, the through holes are circumscribed by a vacuum pump, the wafer is adsorbed by the vacuum, the lower side of the microporous disc is supported on a plane (the plane is the ground or a fixed position required) by an electric telescopic rod, the rotating disc is arranged above the microporous disc, a plurality of conical soft plastics are arranged on the lower side of the rotating disc, a rotating motor is connected to the upper side of the rotating disc, the rotating motor can be supported and fixed on the plane or a position above which is convenient for fixing by a support, the fixing mode of the motor is selected conventionally and is not limited.

[0025] According to the application, preferably, in step (8), the working method of the dandruff removing device is as follows: the vacuum pump is started, then the wafer is adsorbed on the microporous disc, the electric telescopic rod is elongated, the wafer is contacted with the conical soft plastics, then sodium carbonate solution is injected into the gap between the microporous disc and the rotating disc, the rotating motor is started to drive the rotating disc to rotate, and the conical soft plastics are used to scrape off the dandruff on the surface of the wafer.

[0026] According to the application, preferably, in step (8), the weight ratio of sodium carbonate solid to water in the sodium carbonate solution is 1:15.

[0027] According to the application, preferably, in step (9), the temperature of the heating table is set to 105 DEG C.

[0028] According to the application, preferably, in step (10), the water bath heating temperature of the first and second depigmenting solution beakers is set to 50 DEG C, and the error is ±3 DEG C.

[0029] According to the application, preferably, in step (11), when the temperature of the acetone reaches 52 DEG C (the error is floating ±3 DEG C), the wafer is put into the acetone tank.

[0030] According to the application, preferably, in step (12), the ethanol cleaning time is 2 minutes, and the operation is at room temperature.

[0031] According to the application, preferably, in step (13), the temperature of the hot nitrogen drying machine is set to 60 DEG C, and the machine is started to be used when the display is greater than or equal to 35 DEG C, and the drying time is 8 minutes.

[0032] The unexplained parts of the application are the existing conventional technologies in the field, such as the heating table, the waxing machine and the like, which are all existing devices.

[0033] The application has the following beneficial effects:

[0034] The application provides a method for improving the adhesion of wafer substrate dandruff after grinding, which can quickly and effectively remove the dandruff adhered to the surface of the substrate by cooperation of the dandruff removing device and subsequent cleaning operation, increase the adhesion of the substrate and the evaporated metal, and is simple in process, convenient in operation, high in efficiency and widely applicable to the wafer for preparing GaAs arsenic gallium-based, silicon-based and other LED substrates. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 Structure diagram of the chipping removal device of the present application;

[0036] Wherein: 1, wafer; 2, microporous disc; 3, tapered soft plastic; 4, rotating disc; 5, sodium carbonate solution injection position. DETAILED DESCRIPTION

[0037] The present application is further illustrated by the following examples and in conjunction with the accompanying drawings, but is not limited thereto.

[0038] Example 1:

[0039] This example provides a method for improving the adhesion of wafer substrate chips after polishing, the steps are as follows:

[0040] Step (1): heat the stage to 105℃, and heat the waxing machine to 100℃;

[0041] Step (2): preheat the ceramic disc on the heating stage, with the ceramic disc mark facing up, and when the display temperature reaches the set temperature, allow a floating range of 105±5℃, evenly apply wax on each corresponding position of the ceramic disc;

[0042] Step (3): sequentially paste the wafer on the ceramic disc;

[0043] Step (4): after the wafer is pasted, place the ceramic disc on the waxing machine, and place a dust-free paper on the ceramic disc to cover all the wafers, and do not slide the dust-free paper after covering to prevent the wafer from sliding;

[0044] Step (5): start pressing the wafer on the waxing machine, the pressing time is 4-7min, and after completion, start cooling, and take out the ceramic disc when the temperature is lower than 30℃;

[0045] Step (6): peel off the dust-free paper, use ethanol and dust-free paper to wipe the wafer surface, when wiping, spray ethanol on the dust-free paper, then use the dust-free paper to wipe, prevent the wafer edge wax layer from being dissolved when the ethanol is directly sprayed towards the wafer, which may contaminate the wafer during polishing or cause the wafer to blow off, remove the residual wax on the wafer surface to prevent errors during rough grinding thickness measurement;

[0046] Step (7): use the polishing equipment to polish the substrate surface of the wafer, and the thickness is reduced to 120um;

[0047] Step (8): place the thinned wafer on the chipping removal device, and use the chipping removal device to remove the chips on the wafer surface;

[0048] The dandruff removing device comprises a microporous disc 2 and a rotating disc 4, the microporous disc 2 is provided with a plurality of through holes, the through holes are circumscribed by a vacuum pump, the wafer is adsorbed by the vacuum, the lower side of the microporous disc 2 is supported on a plane (the plane is the ground or a fixed position required) by an electric telescopic rod, the rotating disc 4 is arranged above the microporous disc 2, the lower side of the rotating disc 4 is provided with a plurality of conical soft plastics 3, the upper side of the rotating disc 4 is connected with a rotating motor, the rotating motor can be supported and fixed on the plane or a position above which is convenient for fixing by a support, the motor fixing mode is a conventional selection and is not limited;

[0049] The working method of the dandruff removing device is as follows: the vacuum pump is started, then the wafer 1 is adsorbed on the microporous disc 2, the electric telescopic rod is elongated, so that the wafer contacts the conical soft plastic 3, then sodium carbonate solution is injected into the gap between the microporous disc 2 and the rotating disc 4, the weight ratio of sodium carbonate solid to water in the sodium carbonate solution is 1:15, the rotating motor is started to drive the rotating disc to rotate, and the conical soft plastic is used to scrape off the dandruff on the wafer surface.

[0050] Step (9): the wafer after the dandruff is removed is placed on a heating table, when the display temperature reaches 105℃ and the wax is melted, a blade is gently inserted into the wafer below along the edge of the wafer, the wafer is slowly pried up along the edge, and then the wafer is taken out of the wafer box and placed into a wafer box, and then the wafer box is conveyed to a cleaning station.

[0051] Step (10): after the water bath heating temperature of the first and second wax removing liquid beakers reaches 50℃, the wafer is taken out of the wafer box and sequentially placed into the first and second wax removing liquid beakers for cleaning, so as to improve the wax removing effect by twice cleaning.

[0052] Step (11): when the temperature of the acetone reaches 52℃, the wafer after the wax is removed is placed into an acetone tank, and the immersion process is slow to avoid wafer cracking.

[0053] Step (12): the wafer is taken out of the acetone tank and cleaned by ethanol for 2 minutes at room temperature.

[0054] Step (13): after the ethanol cleaning is completed, the wafer is placed into a hot nitrogen drying machine for drying, the hot nitrogen drying machine is set at a temperature of 60℃, and is used when the display temperature is greater than or equal to 35℃, and the drying time is 8 minutes.

[0055] Step (14): the wafer after the drying is subjected to N face metal evaporation, and the evaporation metal is a Ni / Au / Ge / Ni / Au laminated metal.

[0056] After the wafer 119 pieces are subjected to the N face metal evaporation according to the embodiment, the qualified rate is 99.7%, and the wafer cracking rate caused by the cleaning process is 0.02%.

[0057] The above is the preferred embodiment of the present application, it should be noted that for those skilled in the art, without departing from the principles described in the present application, can also be made several improvements and refinements, these improvements and refinements should also be considered the scope of protection of the present application.

Claims

1. A method for improving the adhesion of debris to a wafer substrate after polishing, characterized in that, The steps are as follows: Step (1): Heat the heating table and waxing machine to the set temperature; Step (2): Place the ceramic plate on the heating table for preheating, with the markings on the ceramic plate facing upwards. When the displayed temperature reaches the set temperature, apply wax evenly to the corresponding positions on the ceramic plate. Step (3): Place the wafers sequentially onto the ceramic disk; Step (4): After the chip mounting is completed, place the ceramic disk on the waxing machine, place lint-free paper on the ceramic disk, and cover all the chips; Step (5): The wafer is pressed on the waxing machine for 4-7 minutes. After pressing, it is cooled. The ceramic plate is removed when the temperature is below 30℃. Step (6): Peel off the lint-free paper, and wipe the wafer surface with ethanol and lint-free paper to remove residual wax from the wafer surface; Step (7): Use a grinding machine to grind the substrate surface of the wafer to reduce the thickness by 120um; Step (8): Place the thinned wafer on the chip removal device and use the chip removal device to remove the chip surface debris; The dandruff removal device includes a microporous disk and a rotating disk. The microporous disk has several through holes, and a vacuum pump is connected to the outside of the through holes. The lower side of the microporous disk is supported on a plane by an electric telescopic rod. A rotating disk is set above the microporous disk. Several conical soft plastics are set on the lower side of the rotating disk. A rotating motor is connected to the upper side of the rotating disk. The working method of the chip removal device is as follows: the vacuum pump is started, and then the wafer is adsorbed onto the microporous disk. The electric telescopic rod is extended to make the wafer contact the conical soft plastic. Then, sodium carbonate solution is injected into the gap between the microporous disk and the rotating disk. The rotary motor is started to drive the rotating disk to rotate and use the conical soft plastic to scrape off the chip surface. Step (9): Place the de-dust-removed wafer on the heating table. After the displayed temperature reaches the set temperature and the wax melts, gently insert a blade along the edge of the wafer to the bottom of the wafer, pry the wafer up along the edge, and use tweezers to pick it up and put it into the wafer box. Then, transfer the wafer box to the cleaning station. Step (10): Remove the wafer from the wafer box and place it into the first dewaxing liquid beaker and the second dewaxing liquid beaker for cleaning in sequence; Step (11): Place the dewaxed wafer into the acetone bath; Step (12): Remove the wafer from the acetone bath and clean it with ethanol; Step (13): After ethanol cleaning, place the wafers in a hot nitrogen dryer to dry them; Step (14): The dried wafer is subjected to N-side metal evaporation, and the evaporated metal is a Ni / Au / Ge / Ni / Au stacked metal.

2. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (1), the heating table temperature is set to 105°C, and the waxing machine turns on the heater to raise the temperature to 100°C.

3. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (6), when wiping, spray ethanol onto the lint-free paper and then wipe with the lint-free paper.

4. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (8), the weight ratio of sodium carbonate solid to water in the sodium carbonate solution is 1:

15.

5. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (9), the temperature of the heating platform is set to 105°C.

6. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (10), the water bath heating temperature in the first and second dewaxing liquid beakers is set to 50℃, with an error of ±3℃.

7. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (11), when the acetone temperature reaches 52°C, the wafer is placed into the acetone bath.

8. The method for improving the adhesion of debris to a wafer substrate after polishing as described in claim 1, characterized in that, In step (12), the ethanol is used for cleaning for 2 minutes at room temperature; In step (13), the hot nitrogen dryer is set to 60°C. When the temperature is displayed as ≥35°C, it is put into use and the drying time is 8 minutes.

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