A method of dicing a wafer of LEDs

Abstract

The present application relates to a kind of cutting and splitting methods of LED wafer.Cutting and splitting method includes the following steps: (1) wafer N face is upward, N face is pasted film, then wafer P face is upward, and wafer is cut; (2) wafer P face is upward, and isolation ring is placed, and P face is pasted film; (3) wafer is turned over, N face is upward P face is downward, N face blue film is removed, and isolation ring is removed, and wafer is cut; N face is upward, and isolation ring is placed, and N face is pasted film; (4) wafer is turned over, P face is upward N face is downward, P face blue film is removed, and isolation ring is removed, and wafer is cut; (5) P face is upward, and protective liquid is coated, and P face is pasted film; (6) wafer is cut and split, and wafer is cleaned, and cutting and splitting of LED wafer are completed.Cutting and splitting method provided by the present application can effectively avoid wafer damage caused in the process of cutting and splitting, improve product pass rate, ensure product benefit, and completely eliminate blue film residual glue left on wafer surface, improve product appearance and soldering line yield.

Description

TECHNICAL FIELD

[0001] The present application relates to a cutting and splitting method of LED wafer, and belongs to the technical field of LED chip. BACKGROUND

[0002] In the preparation process of LED chip, cutting is a process of dividing the whole chip after photoetching, film plating, thinning and other processes into single dies of required size, which is an indispensable procedure in the preparation process of semiconductor light-emitting diode chip. For LED chip, the most widely used cutting method is sawing.

[0003] Laser cutting is a new type of cutting technology emerging with the development of laser technology, mainly including laser surface cutting and invisible cutting. Laser cutting is to focus laser beams with certain energy density and wavelength on the surface or inside of the chip, burn a scratch on the surface or inside of the chip by laser, and then split the chip along the scratch by a splitting machine to form several small chips. However, in the splitting process of the wafer, the wafer has a certain degree of crack risk after UV laser cutting, SD laser cutting and knife wheel cutting, which is easy to cause damage to the wafer during the turning process, resulting in loss, affecting output, and blue film residue will be left on the wafer surface when the cut wafer is split by the splitting machine, causing wafer pollution, affecting product appearance and soldering yield.

[0004] Chinese patent document CN104347760A discloses a cutting method of LED chip, which includes drawing a scratch on the back of the chip by laser, sawing the chip along the scratch by a diamond saw blade, and turning the back-cut chip to turn the film, and cutting the chip into single dies on the front surface of the chip along the groove by a splitting knife. The disadvantage of this method is that it is easy to cause damage to the wafer during the turning process, resulting in loss, affecting output and overall pass rate.

[0005] Chinese patent document CN102079015A discloses a laser cutting method of GaAs-based LED chip, which includes forming a laser scratch on the N surface of the GaAs chip by laser cutting, and then splitting the chip along the laser scratch by a splitting machine on the P surface of the GaAs chip to form a laser scratch with a depth of 1 / 10-4 / 5 of the thickness of the chip. The patent method will form blue film residue on the wafer surface under the pressure of splitting, which is not easy to clean, and will cause product appearance defects, unqualified soldering, and affect the use of downstream customers. SUMMARY

[0006] In view of the deficiencies of the prior art, the present application provides a cutting and splitting method of LED wafer.

[0007] The technical solution of the present application is as follows:

[0008] A cutting and splitting method of LED wafer, comprising the following steps:

[0009] (1) Put the wafer with N surface upward into a film sticking machine, cover the N surface of the wafer with a blue film, heat, and perform a first N surface film sticking operation, then put the wafer with P surface upward, and use a scribe machine to perform a scribing operation on the P surface of the wafer;

[0010] (2) Put the wafer obtained in step (1) with P surface upward into the film sticking machine, then put an isolation ring, so that the wafer is located in the center of the isolation ring, cover the P surface of the wafer with a blue film, heat, and perform a first P surface film sticking operation;

[0011] Wherein, the isolation ring is a circular ring structure;

[0012] (3) Turn over the wafer obtained in step (2) so that the N surface is upward and the P surface is downward, then remove the N surface blue film, take off the isolation ring, use a scribe machine to perform a scribing operation on the N surface of the wafer; keep the N surface of the wafer upward, put it into the isolation ring so that the wafer is located in the center of the isolation ring, cover the N surface of the wafer with a blue film, heat, and perform a first N surface film sticking operation;

[0013] (4) Turn over the wafer obtained in step (3) so that the P surface is upward and the N surface is downward, then remove the P surface blue film, take off the isolation ring, and use a scribe machine to perform a scribing operation on the P surface of the wafer;

[0014] (5) Keep the P surface of the wafer upward, uniformly coat a protective liquid on the P surface of the wafer, then use the centrifugal force of a high-pressure cleaning machine to uniformly shake the protective liquid to form a protective liquid layer, cover the P surface of the wafer with a blue film, heat, and perform a first P surface film sticking operation;

[0015] (6) Use a splitting machine to split the wafer obtained in step (5), and then use a high-pressure cleaning machine to clean the wafer, thereby completing the cutting and splitting of the LED wafer.

[0016] According to the application, preferably, in step (1), the wafer is a thinned wafer, and the thickness is 80-120 μm.

[0017] According to the application, preferably, in step (1), the heating temperature is 50-60 ℃, and the film sticking operation temperature in the other steps is the same as that in step (1).

[0018] According to the application, preferably, in step (1), the blue film is SPV-224, and the size is 220 mm*100 m-260 mm*100 m, and the blue film type in the other steps is the same as that in step (1).

[0019] Preferably, in step (2), the small diameter of the isolation ring is 0.4-0.6 cm larger than the wafer diameter, the thickness is 8-12 μm thinner than the wafer thickness, the large diameter is 16-18 cm, and the material is stainless steel or plastic.

[0020] Preferably, in step (2), the dicing machine is a sawing machine, an ultraviolet laser cutting machine, an SD laser cutting machine or a cutter wheel cutting machine.

[0021] Preferably, in step (4), the protective liquid is a mixed solution of water, polyether and surfactant, and the volume ratio of the water, polyether and surfactant is 10:(4-6):(4-6).

[0022] Further preferably, the surfactant is disodium lauryl sulfosuccinate or cocamide diethanol, etc. The specific surfactant can be adjusted according to actual needs.

[0023] Preferably, in step (4), the thickness of the protective liquid layer is 3-6 μm.

[0024] The unexplained parts of the present application are the conventional technologies in the field, and the unexplained apparatuses are the existing devices.

[0025] The present application has the following advantages:

[0026] 1. The isolation ring is used in the cutting and dicing process, and the wafer and the isolation ring are fixed together without direct contact through the operation of sticking the blue film, so that the isolation ring plays the role of supporting the wafer, and the wafer can be turned over by turning over the isolation ring in the wafer turning process. The whole turning process does not need to directly contact the wafer, avoids the wafer damage problem caused in the turning process due to the wafer being too thin or having been subjected to the dicing operation, and the isolation ring does not directly contact the wafer, the adhesion between the isolation ring and the wafer becomes smaller at low temperature, and the isolation ring is easy to separate after turning. Overall, the cutting and dicing method provided by the present application can effectively avoid the wafer damage caused in the cutting and dicing process, improve the product yield, and ensure the benefit of the product.

[0027] 2. A neutral protective liquid is coated on the contact surface between the blue film and the wafer in the dicing process, so that the wafer and the blue film are not completely adhered, and then the dicing is performed. After the dicing is completed, the high-pressure cleaning machine is used for cleaning, so that the blue film residue left on the wafer surface can be completely eliminated, and the product appearance and wire bonding yield are improved.

[0028] 3. The process of the present application is simple and easy to operate, and can be widely used in the cutting and dicing of GaAs gallium arsenide-based, silicon-based, gallium nitride, aluminum nitride and other substrate LED wafers after thinning process, with a thickness of 80-120 μm. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 The top view of the wafer after the blue film is pasted and the isolation ring is placed.

[0030] Figure 2 The right view of the wafer after the blue film is pasted and the isolation ring is placed.

[0031] Figure 3 The structural schematic diagram of the isolation ring.

[0032] In the figure: 1, wafer, 2, isolation ring, 3, blue film, 4, film pasting machine tray. DETAILED DESCRIPTION

[0033] The present application will be described in detail below in conjunction with specific embodiments and the accompanying drawings of the specification, but is not limited thereto.

[0034] Example 1

[0035] A cutting and splitting method of an LED wafer, comprising the following steps:

[0036] (1) Place the wafer with a thickness of 100 μm N face upward into the film pasting machine, cover the wafer N face with a blue film, heat to 55°C, and perform a first N face film pasting operation, at this time the wafer N face has a film; then place the wafer P face upward, and use an ultraviolet laser cutting machine to perform a wafer splitting operation on the wafer P face;

[0037] (2) Place the wafer P face obtained in step (1) upward into the film pasting machine, and then place an isolation ring, so that the wafer is located in the center of the isolation ring, cover the wafer P face with a blue film, heat to 55°C, and perform a first P face film pasting operation, at this time the wafer has films on both sides;

[0038] (3) Turn over the wafer obtained in step (2) so that the wafer N face is upward and the P face is downward, then remove the N face blue film, as shown in detail in Figures 1-2 ; remove the isolation ring, and use an ultraviolet laser cutting machine to perform a wafer splitting operation on the wafer N face; keep the wafer N face upward, place it into the isolation ring so that it is located in the center of the isolation ring, cover the wafer N face with a blue film, heat to 55°C, and perform a first N face film pasting operation, at this time the wafer has films on both sides;

[0039] (4) Turn over the wafer obtained in step (3) so that the wafer P face is upward and the N face is downward, then remove the P face blue film, remove the isolation ring, and use an ultraviolet laser cutting machine to perform a wafer splitting operation on the wafer P face, at this time the wafer N face has a film;

[0040] (5) Keep the wafer P face upward, coat the protective liquid on the wafer P face uniformly, then spin the protective liquid uniformly by the centrifugal force of the high-pressure cleaning machine to form a protective liquid layer with a thickness of 5 μm, cover the wafer P face protective liquid layer with a blue film, heat, and perform a first P face film pasting operation, at this time, the wafer has films on both sides;

[0041] The protective liquid is a mixed solution composed of water, polyether, and coconut oil diethanolamide in a volume ratio of 5:2:3;

[0042] (6) The wafer obtained in step (5) is cracked using a wafer breaking machine, and the wafer is cleaned using a high-pressure cleaning machine after cracking to complete the cutting and cracking of the LED wafer.

[0043] The blue film is SPV-224, and the size of the blue film is 220 mm*100 m. The small diameter of the isolation ring is 0.5 cm larger than the diameter of the wafer, the thickness is 10 μm thinner than the thickness of the wafer, the large diameter is 17 cm, and the material is stainless steel, as shown in Figure 3 .

[0044] In this embodiment, 347,620 wafers are obtained by cutting and cracking, 2,190 wafers are damaged during turning, the product quality qualification rate is 99.37%, and 409 wafers have blue film residual glue left after cracking, and the blue film residual glue qualification rate is 99.88%.

[0045] Example 2

[0046] An LED wafer cutting and cracking method, comprising the following steps:

[0047] (1) Put the wafer with a thickness of 80 μm N face upward into the film pasting machine, cover the wafer N face with a blue film, heat to 50℃, perform a first N face film pasting operation, then put the wafer P face upward, and use a cutter wheel cutting machine to perform a wafer P face scribing operation;

[0048] (2) Put the wafer obtained in step (1) P face upward into the film pasting machine, then put the isolation ring so that the wafer is located in the center of the isolation ring, cover the wafer P face with a blue film, heat to 50℃, and perform a first P face film pasting operation;

[0049] (3) Turn over the wafer obtained in step (2) so that the wafer N face is upward and the P face is downward, then remove the N face blue film, take off the isolation ring, use a cutter wheel cutting machine to perform a wafer N face scribing operation; keep the wafer N face upward, put it into the isolation ring so that it is located in the center of the isolation ring, cover the wafer N face with a blue film, heat to 50℃, and perform a first N face film pasting operation;

[0050] (4) Turn over the wafer obtained in step (3) so that the wafer P face is upward and the N face is downward, then remove the P face blue film, take off the isolation ring, and use a cutter wheel cutting machine to perform a wafer P face scribing operation;

[0051] (5) Keep the wafer P face upward, coat the protective liquid on the wafer P face uniformly, then spin the protective liquid uniformly by the centrifugal force of the high pressure cleaning machine to form a protective liquid layer with a thickness of 3 μm, cover the wafer P face protective liquid layer with a blue film, heat, and perform a first P face film pasting operation;

[0052] The protective liquid is a mixed solution composed of water, polyether, and lauryl sulfonated succinic acid monoester disodium in a volume ratio of 2:1:1;

[0053] (6) Use the wafer obtained in step (5) to perform wafer splitting in a wafer splitter, clean the wafer using a high pressure cleaning machine after splitting, and complete the cutting and splitting of the LED wafer.

[0054] The cutting and splitting in this example obtained 347620 wafers, 2210 of which were damaged during turning, the product quality qualified rate was 99.36%, and 511 had blue film residual glue left after splitting, the blue film residual glue qualified rate was 99.85%.

[0055] Example 3

[0056] An LED wafer cutting and splitting method, comprising the following steps:

[0057] (1) Place the wafer with a thickness of 120 μm N face upward into a film pasting machine, cover the wafer N face with a blue film, heat to 60°C, perform a first N face film pasting operation, then place the wafer P face upward, and use an SD laser cutting machine to perform wafer P face scribing;

[0058] (2) Place the wafer obtained in step (1) P face upward into a film pasting machine, place a spacer ring, so that the wafer is located in the center of the spacer ring, cover the wafer P face with a blue film, heat to 60°C, and perform a first P face film pasting operation;

[0059] (3) Turn over the wafer obtained in step (2) so that the wafer N face is upward and the P face is downward, then remove the N face blue film, remove the spacer ring, use an SD laser cutting machine to perform wafer N face scribing; keep the wafer N face upward, place it in the spacer ring so that it is located in the center of the spacer ring, cover the wafer N face with a blue film, heat to 60°C, and perform a first N face film pasting operation;

[0060] (4) Turn over the wafer obtained in step (3) so that the wafer P face is upward and the N face is downward, then remove the P face blue film, remove the spacer ring, and use an SD laser cutting machine to perform wafer P face scribing;

[0061] (5) Keep the wafer P face upward, coat the protective liquid on the wafer P face uniformly, then spin the protective liquid uniformly by the centrifugal force of the high-pressure cleaning machine to form a protective liquid layer with a thickness of 6 μm, cover the wafer P face protective liquid layer with a blue film, heat, and perform a first P face film pasting operation;

[0062] The protective liquid is a mixed solution composed of water, polyether, and lauryl sulfosuccinate monoisodium salt in a volume ratio of 2:1:1;

[0063] (6) Use the wafer obtained in step (5) to perform wafer splitting in a wafer splitter, clean the wafer by using a high-pressure cleaning machine after splitting, and complete the cutting and splitting of the LED wafer.

[0064] The cutting and splitting of this example obtained 347620 wafers, 1989 wafers were damaged in the turning, the product quality qualified rate was 99.42%, and 401 wafers had blue film residual glue left after splitting, the blue film residual glue qualified rate was 99.88%.

[0065] Comparative Example 1

[0066] An LED wafer cutting and splitting method, comprising the following steps:

[0067] (1) Put the wafer P face downward into a film pasting machine, cover the wafer N face with a blue film, heat, and make the wafer N face adhere to the blue film;

[0068] (2) Put the wafer obtained in step (1) P face upward into a cutting machine, calibrate the level, draw a cutting row and column, and form a scratch on the P face surface;

[0069] (3) Put the wafer of step (2) into a film pasting machine, remove the blue film, manually turn the wafer with tweezers, and repeat step (1) again;

[0070] (4) Put the wafer of step (3) into an SD laser cutting machine for operation, at this time, the N face is upward, put it into the SD laser cutting machine, calibrate the level, draw a cutting row and column, and form a scratch on the N face surface;

[0071] (5) Put it into a wafer splitter to perform splitting, and complete the splitting of the LED wafer.

[0072] The cutting and splitting of this comparative example obtained 347620 wafers, 66098 wafers were damaged in the turning, the product quality qualified rate was 80.98%, and 41349 wafers had blue film residual glue left after splitting, the blue film residual glue qualified rate was 88.11%.

Claims

1. A method for cutting and splitting LED wafer, comprising the following steps: (1) placing the wafer with N surface upward into a film sticking machine, covering the wafer N surface with a blue film, heating, and performing a first N surface film sticking operation, then placing the wafer with P surface upward, and performing a wafer P surface scribing operation using a scribing machine; (2) placing the wafer obtained in step (1) with P surface upward into a film sticking machine, and placing a spacer ring, so that the wafer is located in the center of the spacer ring, covering the wafer P surface with a blue film, heating, and performing a first P surface film sticking operation; wherein the spacer ring is a circular ring structure; (3) turning over the wafer obtained in step (2) so that the wafer N surface is upward and the P surface is downward, then removing the N surface blue film, taking off the spacer ring, and performing a wafer N surface scribing operation using a scribing machine; keeping the wafer N surface upward, placing the wafer in the spacer ring so that the wafer is located in the center of the spacer ring, covering the wafer N surface with a blue film, heating, and performing a first N surface film sticking operation; (4) turning over the wafer obtained in step (3) so that the wafer P surface is upward and the N surface is downward, then removing the P surface blue film, taking off the spacer ring, and performing a wafer P surface scribing operation using a scribing machine; (5) keeping the wafer P surface upward, uniformly coating a protective liquid on the wafer P surface, then uniformly spinning the protective liquid by the centrifugal force of a high-pressure cleaning machine to form a protective liquid layer, covering the wafer P surface protective liquid layer with a blue film, heating, and performing a first P surface film sticking operation; (6) splitting the wafer obtained in step (5) using a splitting machine, and cleaning the wafer using a high-pressure cleaning machine after splitting, to complete the cutting and splitting of the LED wafer.

2. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In step (1), the wafer is a thinned wafer with a thickness of 80-120 μm.

3. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In step (1), the heating temperature is 50-60℃.

4. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In step (1), the blue film model is SPV-224, and the size of the blue film is 220mm*100m-260mm*100m.

5. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In step (2), the small diameter of the spacer ring is 0.4-0.6 cm larger than the diameter of the wafer, the thickness is 8-12 μm thinner than the thickness of the wafer, the large diameter is 16-18 cm, and the material is stainless steel or plastic.

6. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In steps (1), (3) and (4), the scribing machine is a saw blade machine, an ultraviolet laser cutting machine, an SD laser cutting machine or a cutter wheel cutting machine.

7. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In step (5), the protective liquid is a mixed solution of water, polyether and surfactant; the volume ratio of the water, polyether and surfactant is 10: (4-6) : (4-6).

8. The method of claim 7, wherein the laser beam is focused to a spot size of 1- 10 microns. The surfactant is disodium lauryl sulfosuccinate or cocodiethanolamide.

9. The method of claim 1, wherein the LED wafer is cut into the dicing streets by a laser beam. In step (5), the thickness of the protective liquid layer is 3-6 μm.

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