A dicing method for cutting LED wafers

Abstract

The present application relates to a kind of cutting LED wafer's splitting method, belong to LED chip technical field.It includes the following steps: (1) wafer is placed in film sticking machine and carries out film sticking operation;(2) the wafer obtained in step (1) is placed into scribe machine, calibrates level, draws cutting row and column, and scribe machine forms scratch on wafer surface;(3) a layer of ion conductive film is pasted on the electrode side of wafer;(4) the wafer to be split is placed into tool base, then tool base is placed into splitting machine, and splitting operation is carried out, and splitting knife down pressure is adjusted to 6-7um;(5) after splitting is completed, tool base is taken out from splitting machine, and separation operation is carried out;(6) gas back flushing is started, and blue film is inflated upward, and wafer is completely separated.The present application can reduce the down pressure of splitting knife of splitting machine when splitting, avoid cutting failure caused by excessive down pressure of splitting knife, and avoid double crystal after film expansion due to adhesion between LED wafers after splitting is completed, which affects product yield.

Description

Technical Field

[0001] This invention relates to a method for dicing LED wafers, belonging to the field of LED chip technology. Background Technology

[0002] In LED chip manufacturing, dicing is the process of dividing the entire chip, after processes such as photolithography, coating, and thinning, into individual chips of the required size. This is an indispensable step in the manufacturing process of semiconductor light-emitting diode chips. Currently, the most widely used dicing method for LED chips in the industry is saw blade cutting.

[0003] Laser cutting is a new cutting technology that emerged with the development of laser technology. It mainly includes two types: laser surface cutting and stealth cutting. Laser cutting involves focusing a laser beam of a certain energy density and wavelength onto the surface or interior of a chip. The laser burns scratches into the chip's surface or interior, and then a dicing machine is used to split the chip along these scratches, forming several smaller chips. However, this method is prone to defects during dicing due to excessive pressure from the dicing machine's blades. Furthermore, the wafer substrate subjected to laser cutting is susceptible to melting under high pressure, leading to chip adhesion after dicing and the appearance of twinning after film expansion.

[0004] Chinese patent document CN102079015A discloses a laser cutting method for GaAs-based LED chips, which includes forming laser scratches on the N-side of the GaAs chip using a laser cutter, and then splitting the chip along the laser scratches on the P-side of the GaAs chip using a dicing machine. The depth of the laser scratches is 1 / 10 to 4 / 5 of the chip thickness. This method cannot avoid the possibility of poor cutting due to excessive downward pressure from the dicing machine's cutting blade during the dicing process, resulting in a low product yield. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a method for cleaving LED chips. This method can reduce the downward pressure of the cleaving blade during cleaving, avoiding poor cutting caused by excessive downward pressure. It also prevents the formation of twin crystals after film expansion due to adhesion between LED chips after cleaving, thus avoiding affecting product yield.

[0006] The technical solution of the present invention is as follows:

[0007] A method for dicing LED chips includes the following steps:

[0008] (1) Place the wafer on the laminating machine for lamination, heat it to make the wafer adhere to the blue film, and the side of the wafer without electrodes adheres to the blue film;

[0009] (2) Place the wafer obtained in step (1) into the dicing machine, calibrate the level, draw the cutting rows and columns, and the dicing machine forms scratches on the wafer surface;

[0010] (3) Apply an ion-conducting film to the electrode side of the wafer to prevent scratches and breakage;

[0011] (4) Place the wafer to be cracked into the fixture base, and then place the fixture base into the cleaver to carry out the cleaving operation. When cracking, adjust the downward pressure of the cleaver to 6-7 μm, which is 30%-40% less than the original 10 μm.

[0012] (5) After the wafer dicing is completed, the fixture base is removed from the wafer dicing machine and the fixture base is used for separation to separate the wafers;

[0013] (6) Turn on the gas backflush to make the blue film bulge upwards and the wafer completely separate.

[0014] According to a preferred embodiment of the present invention, in step (1), the wafer is a thinned wafer with a thickness of 150 to 220 μm.

[0015] According to a preferred embodiment of the present invention, in step (1), the heating temperature is 55-65°C.

[0016] According to a preferred embodiment of the present invention, in step (1), the blue film model is SPV-224 or YDX-P0250-R85, and the size of the blue film is 220mm*100m~260mm*100m;

[0017] According to a preferred embodiment of the present invention, in step (2), the dicing machine is a saw, an ultraviolet laser cutter, an SD laser cutter, or a blade wheel cutter.

[0018] According to a preferred embodiment of the present invention, in step (3), the thickness of the ion-conducting film is 40-60 μm.

[0019] According to a preferred embodiment of the present invention, in step (4), air holes are evenly distributed on the fixture base, and the air holes are connected to an air pump through a gas pipe provided inside the fixture base. A rectangular cutout is provided in the middle of the fixture base, and tracks are provided on both sides of the rectangular cutout. Rollers are movably arranged on the tracks. The rollers can be driven by human power or by a drive wheel to achieve the rolling of the rollers. A cover plate is provided inside the fixture base on both sides of the rectangular cutout. The cover plate is connected to the inside of the fixture base through a telescopic rod. The wafer to be cracked is placed on the fixture base with the blue film facing down. The blue film covers the entire fixture base, and the wafer is placed inside the rectangular cutout.

[0020] In a further preferred embodiment, in step (5), the separation process is as follows: the roller is driven to move along the track, and under the action of the upward force of the roller, the blue film generates an upward stretching force, thereby separating the wafer.

[0021] According to a preferred embodiment of the present invention, in step (6), the gas backflushing process is as follows: two baffles extend and close, the blue film and the tooling base form a sealed space, and then the air pump is started, blowing gas upward through the air hole. Under the action of the gas, the blue film bulges upward, and the wafer is completely separated.

[0022] All techniques not described in detail in this invention are conventional techniques already existing in the field.

[0023] The beneficial effects of this invention are as follows:

[0024] 1. This invention provides a method for cleaving LED chips, which can reduce the downward pressure of the cleaving blade during cleaving, avoid poor cutting caused by excessive downward pressure of the cleaving blade, and at the same time avoid double crystal formation after film expansion due to adhesion between LED chips after cleaving, which would affect product yield.

[0025] 2. The process of this invention is simple and easy to operate, and it can be widely applied to the wafer cutting and dicing of suitable GaAs gallium arsenide-based, silicon-based, gallium nitride, aluminum nitride and other materials for preparing LED substrates. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the tooling base structure of the present invention;

[0027] Figure 2 This is a front view of the tooling base structure of the present invention;

[0028] Figure 3 This is a side view of the tooling base structure of the present invention;

[0029] Figure 4 This is a top view of the tooling base structure of the present invention;

[0030] The components include: 1. Tooling base; 2. Roller; 3. Cover plate; 4. Rectangular cutout; 5. Air hole. Detailed Implementation

[0031] The present invention will be further described below with reference to the embodiments and accompanying drawings, but is not limited thereto.

[0032] Example 1:

[0033] This embodiment provides a method for dicing LED wafers, including the following steps:

[0034] (1) Place the thinned wafer on a laminator for lamination. The wafer thickness is 150μm. Heat the wafer to adhere it to the blue film. The heating temperature is 55℃. The side of the wafer without electrodes adheres to the blue film.

[0035] (2) Place the wafer obtained in step (1) into the dicing machine, calibrate the level, draw the cutting rows and columns, and the dicing machine forms scratches on the wafer surface;

[0036] (3) A layer of ion-conducting film is attached to the electrode side of the wafer to prevent scratches and breakage. The thickness of the ion-conducting film is 40 μm.

[0037] (4) Place the wafer to be cracked into the fixture base, and then place the fixture base into the cleaver for cleaving. When cleaving, adjust the downward pressure of the cleaver to 6-7 μm, which is 30%-40% less than the original 10 μm.

[0038] (5) After the wafer dicing is completed, the fixture base is removed from the wafer dicing machine and the fixture base is used for separation to separate the wafers;

[0039] (6) Turn on the gas backflush to make the blue film bulge upwards and the wafer completely separate.

[0040] In step (1), the blue film model is SPV-224 or YDX-P0250-R85, and the size of the blue film is 220mm*100m~260mm*100m.

[0041] In step (2), the dicing machine is a saw, an ultraviolet laser cutter, an SD laser cutter, or a blade wheel cutter.

[0042] In step (4), air holes 5 are evenly distributed on the fixture base 1. The air holes 5 are connected to an air pump through gas pipes installed inside the fixture base 1. A rectangular cutout 4 is set in the middle of the fixture base 1. Tracks are set on both sides of the rectangular cutout 4. Rollers 2 are movably set on the tracks. The rollers 2 can be driven by human power or by a drive wheel to achieve the rolling of the rollers. A cover plate 3 is set inside the fixture base 1 on both sides of the rectangular cutout 4. The cover plate 3 is connected to the inside of the fixture base 1 through a telescopic rod. The wafer to be cracked is placed on the fixture base with the blue film facing down. The blue film covers the entire fixture base. The wafer is placed in the rectangular cutout. The fixture base structure is as follows. Figures 1-4 As shown.

[0043] In step (5), the separation process is as follows: the roller is driven to move along the track, and under the action of the upward force of the roller, the blue film generates an upward stretching force, so that the wafer is separated.

[0044] In step (6), the gas backflushing process is as follows: two baffles extend and close, the blue film and the tooling base form a sealed space, and then the air pump is started, blowing gas upward through the air hole. Under the action of the gas, the blue film bulges upward, and the wafer is completely separated.

[0045] In this embodiment, 97,620 wafers were cut, and 2,190 wafers were defective due to deformation of the blue film during the cutting process, resulting in a cutting pass rate of 97.7%.

[0046] Example 2:

[0047] A method for cutting LED wafers, the steps of which are as described in Example 1, except that in step (1), the wafer thickness is 220 μm and the heating temperature is 65 °C.

[0048] In step (3), the thickness of the ion-conducting film is 60 μm.

[0049] Comparative example:

[0050] A comparative example provides an existing method for dicing LED wafers, the steps of which are as follows:

[0051] (1) The wafer is laminated on a laminating machine and heated to adhere the wafer to the blue film;

[0052] (2) Place the wafer obtained in step (1) into a dicing machine, calibrate the level, draw the cutting rows and columns, and form scratches on the surface;

[0053] (3) Start the wafer dicing process to complete the dicing of the LED wafer.

[0054] In the comparative example, 97,620 wafers were cut, and 9,009 wafers were defective due to deformation of the blue film during the cutting process, resulting in a cutting pass rate of 90.7%. The cutting pass rate of Example 1 was 7% higher than that of the comparative example, showing a significant improvement.

Claims

1. A method for dicing LED chips, characterized in that, The steps include the following: (1) Place the wafer on the laminating machine for lamination, heat it to make the wafer adhere to the blue film, and the side of the wafer without electrodes adheres to the blue film; (2) Place the wafer obtained in step (1) into the dicing machine, calibrate the level, draw the cutting rows and columns, and the dicing machine forms scratches on the wafer surface; (3) A layer of ion-conducting film is attached to the side of the wafer with electrodes; (4) Place the wafer to be cracked into the fixture base, and then place the fixture base into the wafer cracking machine to carry out the cracking operation. When cracking, adjust the downward pressure of the cleaver to 6-7 μm. The fixture base is evenly distributed with air holes, which are connected to an air pump through gas pipes inside the fixture base. A rectangular cutout is set in the middle of the fixture base, and tracks are set on both sides of the rectangular cutout. Rollers are movably set on the tracks. A cover plate is set inside the fixture base on both sides of the rectangular cutout. The cover plate is connected to the inside of the fixture base through a telescopic rod. The wafer to be cracked is placed on the fixture base with the blue film facing down, and the blue film covers the entire fixture base. The wafer is placed in the rectangular cutout. (5) After the wafer dicing is completed, the fixture base is removed from the wafer dicing machine and the fixture base is used for separation to separate the wafers; (6) Turn on the gas backflush to make the blue film bulge upwards and the wafer completely separate.

2. The method for dicing LED wafers as described in claim 1, characterized in that, In step (1), the wafer is a thinned wafer with a thickness of 150~220μm.

3. The method for dicing LED wafers as described in claim 1, characterized in that, In step (1), the heating temperature is 55-65℃.

4. The method for dicing LED wafers as described in claim 1, characterized in that, In step (1), the blue film model is SPV-224 or YDX-P0250-R85, and the size of the blue film is 220mm*100m~260mm*100m.

5. The method for dicing LED wafers as described in claim 1, characterized in that, In step (2), the dicing machine is a saw, an ultraviolet laser cutter, an SD laser cutter, or a blade wheel cutter.

6. The method for dicing LED wafers as described in claim 1, characterized in that, In step (3), the thickness of the ion-conducting film is 40-60 μm.

7. The method for dicing LED wafers as described in claim 1, characterized in that, In step (5), the separation process is as follows: the roller is driven to move along the track, and under the upward force of the roller, the blue film generates an upward stretching force, which separates the wafer.

8. The method for dicing LED wafers as described in claim 1, characterized in that, In step (6), the gas backflushing process is as follows: two baffles extend and close, then the air pump starts and blows gas upward through the air hole. Under the action of the gas, the blue film bulges upward and the wafer is completely separated.

Images