A method for splitting LED wafers

Abstract

The present invention discloses a method for splitting LED wafers, which relates to the field of semiconductor technology. The method comprises: applying a white film to the front surface of the LED wafer and placing the wafer with the back surface facing upward on a workbench of a wafer splitter; resetting the splitter and receiving platform of the wafer splitter; obtaining an original grain image of the front surface of the LED wafer and performing grain partitioning, wherein the inscribed square area of ​​the LED wafer is area A1 and the non-inscribed square area is area A2; starting the wafer splitter to split the LED wafer; when the splitter splits only area A2, the gap spacing of the receiving platform is c2; when the splitter splits both areas A1 and A2 simultaneously, the gap spacing of the receiving platform is c1, where c1>c2. By dividing the LED wafer into regions and using different gap spacings on the receiving platform, the present invention can effectively reduce the generation of twins, thereby improving the manufacturing quality of LED chips.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to a method for splitting an LED wafer. Background Art

[0002] In the LED chip manufacturing process, chipping refers to the process of splitting the entire LED wafer into independent grains using a chipping machine. The chipping machine uses a support table as support and a splitter to split the LED wafer. Since the LED wafer is circular in shape, the support area of ​​the support table on the LED wafer will change when the splitter splits different areas, that is, the force applied to the LED wafer will change; however, the gap spacing of the support table of the existing chipping machine is fixed and does not change with the change of the splitting area, resulting in the support force of the support table on the LED wafer splitting area not matching the requirements. This can easily lead to the splitter being unable to effectively split the connected grains, resulting in the formation of twins (two grains not successfully separated), which reduces the manufacturing quality of the LED chip. Summary of the Invention

[0003] The purpose of the present invention is to overcome the shortcomings of the existing technology. The present invention provides a method for splitting LED wafers. By dividing the LED wafer into regions and making the supporting platform use different gap spacings, the generation of twins can be effectively reduced, which is beneficial to improving the production quality of LED chips.

[0004] The present invention provides a method for splitting an LED wafer, the method comprising the following steps:

[0005] S1. Apply a white film to the front side of the diced LED wafer and place the back side of the LED wafer upward on the workbench of the wafer splitting machine.

[0006] S2, resetting the splitting knife and the receiving platform of the splitting machine;

[0007] Align the cleaver with the back side of the LED wafer, align the support platform with the front side of the LED wafer, and operate the cleaver to align with the center of the gap of the support platform;

[0008] S3, operating the image recognition system of the wafer splitting machine to obtain an original grain image on the front side of the LED wafer, and performing grain partitioning on the LED wafer based on the original grain image;

[0009] The inscribed square area of ​​the LED wafer is area A1, and the non-inscribed square area of ​​the LED wafer is area A2;

[0010] S4, starting the wafer splitting machine, and using the splitting knife to split the LED wafer based on the areas divided by the die partitions;

[0011] When the splitting knife splits only the A2 area, the gap spacing of the supporting platform is controlled to be c2; when the splitting knife splits the A1 area and the A2 area at the same time, the gap spacing of the supporting platform is controlled to be c1, c1>c2.

[0012] Specifically, the splitting method further includes:

[0013] Before starting the wafer splitting machine, operating the laser thickness gauge of the wafer splitting machine to measure the thickness of the LED wafer, analyzing the overall thickness distribution of the LED wafer, and calculating the average thickness h of the LED wafer; dividing the area on the LED wafer with a thickness greater than the average thickness h into an H1 area, dividing the area on the LED wafer with a thickness equal to the average thickness h into an H2 area, and dividing the area on the LED wafer with a thickness less than the average thickness h into an H3 area;

[0014] The splitting knife strikes the LED wafer by hammering. When the H1 area accounts for more than or equal to one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G1; when the H2 area accounts for more than or equal to one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G3; when the H3 area accounts for more than or equal to one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G4; when the H1 area, the H2 area and the H3 area all account for less than one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G2, G1>G2>G3>G4.

[0015] Specifically, the splitting method further includes:

[0016] Before starting the chip splitter, operate the image recognition system of the chip splitter to identify and locate the cutting lines in the X-axis direction of the LED wafer, and assign a number E to each cutting line in the positive direction of the X-axis. x , x is an integer greater than 0; the E x and the area through which the corresponding cutting line passes; operating the image recognition system of the splitting machine to identify and locate the cutting line in the Y-axis direction of the LED wafer, and assigning a number F to each cutting line in the positive direction of the Y-axis. y , y is an integer greater than 0; the F y Associated with the area through which the corresponding cutting line passes.

[0017] Specifically, a tensioning ring is provided on the periphery of the white film on the front surface of the LED wafer, and the bonding width between the white film and the tensioning ring is in the range of 24 to 38 mm.

[0018] Specifically, the length of a single complete grain in the X-axis direction is a, the length of a single complete grain in the Y-axis direction is b, and the constraint relationship of a, b, and c1 is: a≤c1≤1.5a, or b≤c1≤1.5b;

[0019] The constraint relationship among a, b and c2 is: 0.5a≤c2≤0.8a, or 0.5b≤c2≤0.8b.

[0020] Specifically, before the A1 area and the A2 area are split simultaneously, the splitting positions of the splitting knife and the receiving platform are calibrated.

[0021] Specifically, after the LED wafer is split, the image recognition system of the wafer splitting machine is operated to obtain the image of the grains after splitting on the front side of the LED wafer, and the original grain image and the image of the grains after splitting are compared by a computer to determine whether twin grains exist.

[0022] Specifically, when the LED wafer is split, dry cold air is used to blow across the LED wafer, the temperature of the cold air is in the range of 14 to 16° C., and the speed of the cold air is in the range of 0.6 to 0.9 m / s.

[0023] Specifically, before the LED wafer is placed into the wafer splitting machine, the defective grains on the outer circle of the LED wafer are removed.

[0024] Specifically, the size of the LED wafer is 4 inches.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] The present invention divides the inscribed square area of ​​the LED wafer into area A1 based on the original grain image, and divides the non-inscribed square area of ​​the LED wafer into area A2. Due to the shape restriction of area A2, the contact area between the two sides of the support platform and area A2 is quite different. When the splitting knife only splits area A2, the support force of the support platform on area A2 is easily unbalanced. Therefore, the support platform supports the LED wafer with a smaller gap spacing c2 at this time, which can effectively improve the support stability of the support platform on the LED wafer, so that the splitting knife can effectively split the connected grains and effectively reduce the generation of twins. When the splitting knife splits areas A1 and A2 at the same time, both sides of the support platform have sufficient contact area with the LED wafer, and the support stability of the LED wafer is good. Therefore, the support platform supports the LED wafer with a larger gap spacing c1 (c1>c2) at this time, which can make it easier for the splitting knife to split the connected grains and also effectively reduce the generation of twins.

[0027] The chip splitting method of the present invention enables the gap spacing of the supporting platform to change with the change of the cracking area, thereby improving the support adaptability of the supporting platform to the cracking area of ​​the LED wafer, thereby effectively improving the splitting effect of the grains, reducing the generation of twins, and being beneficial to improving the production quality of LED chips. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 is a flow chart of a splitting method according to an embodiment of the present invention;

[0030] Figure 2 Schematic diagram of the positions of the wrench, LED wafer, and receiving platform in an embodiment of the present invention;

[0031] Figure 3 1 is a schematic diagram of the partitioning of an LED wafer in an embodiment of the present invention;

[0032] Figure 4 It is a schematic diagram of the splitting process of the riving knife and the receiving platform in an embodiment of the present invention.

[0033] In the attached drawings, 1 is a splitting knife; 2 is a receiving platform. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0035] The present invention provides a method for splitting LED wafers. Figure 1 , the splitting method comprises the following steps:

[0036] S1. Apply a white film to the front side of the diced LED wafer and place the back side of the LED wafer upward on the workbench of the wafer splitting machine.

[0037] The front of the diced LED wafer forms several neatly arranged grains and several cutting lines. A splitting machine is required to split the LED wafer into several independent grains along the cutting lines in the X-axis and Y-axis directions.

[0038] S2, resetting the splitting knife and the receiving platform of the splitting machine;

[0039] See also Figure 2 , align the splitting knife 1 with the back side of the LED wafer, align the supporting platform 2 with the front side of the LED wafer, and operate the splitting knife 1 to align with the center of the gap of the supporting platform 2.

[0040] S3, operating the image recognition system of the wafer splitting machine to obtain an original grain image on the front side of the LED wafer, and performing grain partitioning on the LED wafer based on the original grain image;

[0041] See also Figure 3 The inscribed square area of ​​the LED wafer is area A1, and the non-inscribed square area of ​​the LED wafer is area A2.

[0042] S4, starting the wafer splitting machine, and using the splitting knife to split the LED wafer based on the areas divided by the die partitions;

[0043] See also Figure 4 When the splitting knife only splits the A2 area, the gap spacing of the supporting platform is controlled to be c2; when the splitting knife splits the A1 area and the A2 area at the same time, the gap spacing of the supporting platform is controlled to be c1, c1>c2.

[0044] The present invention divides the inscribed square area of ​​the LED wafer into area A1 based on the original grain image, and divides the non-inscribed square area of ​​the LED wafer into area A2; due to the shape restriction of area A2, the contact area between the two sides of the support platform and area A2 is quite different. When the splitting knife only splits area A2, the support force of the support platform on area A2 is easily unbalanced. Therefore, the support platform supports the LED wafer with a smaller gap spacing c2 at this time, which can effectively improve the support stability of the support platform on the LED wafer, so that the splitting knife can effectively split the connected grains, effectively reducing the generation of twins; when the splitting knife splits area A1 and area A2 When splitting is performed simultaneously in the two regions, both sides of the supporting platform have sufficient contact area with the LED wafer, and the support stability of the LED wafer is good. Therefore, the supporting platform supports the LED wafer with a larger gap spacing c1 (c1>c2) at this time, which can make it easier for the splitting knife to split the connected grains and effectively reduce the generation of twins. The splitting method of the present invention enables the gap spacing of the supporting platform to change with the change of the splitting area, improves the support adaptability of the supporting platform to the splitting area of ​​the LED wafer, thereby effectively improving the splitting effect of the grains, reducing the generation of twins, and is conducive to improving the production quality of LED chips.

[0045] Furthermore, the length of a single complete die in the X-axis direction is a, and the length of a single complete die in the Y-axis direction is b. The constraints of a, b, and c1 are: a≤c1≤1.5a, or b≤c1≤1.5b; and the constraints of a, b, and c2 are: 0.5a≤c2≤0.8a, or 0.5b≤c2≤0.8b. This can effectively improve the splitting effect of the die in the corresponding area, reduce the generation of twins, and thus improve the manufacturing quality of the LED chip.

[0046] In some specific embodiments, the splitting method further comprises:

[0047] Before starting the wafer splitting machine, operate the laser thickness gauge of the wafer splitting machine to measure the thickness of the LED wafer, analyze the overall thickness distribution of the LED wafer, and calculate the average thickness h of the LED wafer; the overall thickness distribution of qualified LED wafers is relatively regular, usually thin in the middle and thick at the edges, or thick in the middle and thin at the edges, and the overall thickness difference is usually 10 to 15 μm.

[0048] Specifically, the area on the LED wafer with a thickness greater than the average thickness h is divided into area H1, the area on the LED wafer with a thickness equal to the average thickness h is divided into area H2, and the area on the LED wafer with a thickness less than the average thickness h is divided into area H3.

[0049] Furthermore, the splitting knife strikes the LED wafer by a hammer. When the proportion of the H1 area in the area to be split by the splitting knife is greater than or equal to one half, the striking force of the hammer is controlled to be G1; when the proportion of the H2 area in the area to be split by the splitting knife is greater than or equal to one half, the striking force of the hammer is controlled to be G3; when the proportion of the H3 area in the area to be split by the splitting knife is greater than or equal to one half, the striking force of the hammer is controlled to be G4; when the proportions of the H1 area, the H2 area and the H3 area in the area to be split by the splitting knife are all less than one half, the striking force of the hammer is controlled to be G2, G1>G2>G3>G4.

[0050] Existing wafer splitting machines usually only have one hammer striking force setting, that is, the splitting knife can only split the LED wafer with a fixed splitting force. For thick areas of the LED wafer, the splitting force of the splitting knife is too small; for thin areas of the LED wafer, the splitting force of the splitting knife is too large. On the one hand, it is easy to affect the splitting effect of the splitting knife on the LED wafer, resulting in twinning, edge collapse and other phenomena. On the other hand, it is easy to cause the white film to gradually deform, causing the cutting line to deviate from the landing point of the splitting knife, resulting in the inability to effectively separate the grains, or even damage and scrap.

[0051] The present invention sets different hammer striking forces according to the thickness distribution of the LED wafer, so that the grains in different thickness areas of the LED wafer can all receive appropriate splitting force, with good splitting effect, and can effectively reduce the occurrence of twins, edge collapse and other phenomena; and the adapted hammer striking force can also weaken the deformation degree of the white film, which is conducive to keeping several grains in an orderly arrangement, thereby facilitating the splitting knife to accurately split on the cutting line.

[0052] In some specific embodiments, the splitting method further comprises:

[0053] Before starting the chip splitter, operate the image recognition system of the chip splitter to identify and locate the cutting lines in the X-axis direction of the LED wafer, and assign a number E to each cutting line in the positive direction of the X-axis. x , x is an integer greater than 0; the E x and the area through which the corresponding cutting line passes; operating the image recognition system of the splitting machine to identify and locate the cutting line in the Y-axis direction of the LED wafer, and assigning a number F to each cutting line in the positive direction of the Y-axis. y , y is an integer greater than 0; the F y Associated with the area through which the corresponding cutting line passes.

[0054] This allows for more accurate determination of the position and direction of the cutting line, enabling more precise control of the splitting process. Furthermore, associating the cutting lines with the corresponding regions makes it easier to identify and track the areas each cutting line passes through, further improving the efficiency and accuracy of the splitting process.

[0055] In some specific embodiments, a tensioning ring is provided on the periphery of the white film on the front side of the LED wafer, and the bonding width range of the white film and the tensioning ring is 24 to 38 mm, which can fully ensure that the LED wafer has sufficient supporting force and tension during the splitting process, and has a good stress release effect during the splitting, which is conducive to improving the splitting effect.

[0056] In some specific embodiments, before simultaneously splitting the A1 area and the A2 area, the splitting positions of the splitting knife and the receiving platform are calibrated to ensure that the splitting knife is aligned with the cutting line and the center of the gap of the receiving platform is aligned with the cutting line.

[0057] In some specific embodiments, after the LED wafer is split, the image recognition system of the splitting machine is operated to obtain the image of the grains after splitting on the front side of the LED wafer. The original grain image and the image of the grains after splitting are compared by a computer to determine whether twin grains exist. The splitting results are tested, and if there are significant abnormalities, timely investigation and analysis can be carried out to avoid losses caused by continued abnormalities.

[0058] Moreover, if twin grains exist, they can be positioned at the cutting line with the corresponding number for secondary splitting; at this time, the gap spacing of the supporting platform is controlled to c2, and the striking force of the hammer is controlled to G1 to ensure complete separation of the twin grains.

[0059] In some specific embodiments, dry cold air is blown through the LED wafer during cleaving, with the temperature of the cold air ranging from 14°C to 16°C and the speed of the cold air ranging from 0.6 to 0.9 m / s. This method can better control the temperature of the LED wafer during cleaving, thereby ensuring the quality and effectiveness of the cleavage. The dry cold air can prevent moisture from adversely affecting the LED wafer. The temperature of the cold air ranging from 14°C to 16°C can help reduce the deformation of the white film without affecting the performance of the LED wafer. The speed of the cold air ranging from 0.6 to 0.9 m / s can effectively dissipate heat and blow away fine debris.

[0060] In some specific embodiments, before the LED wafer is placed into the wafer splitting machine, the defective grains on the outer circle of the LED wafer are removed, which is beneficial to improving the quality and effect of the wafer splitting.

[0061] In some specific embodiments, the size of the LED wafer is 4 inches, and the cracking quality and effect are good; it should be noted that the larger the size of the LED wafer, the more stringent the requirements for the cracking process, and slight changes may also cause huge deviations; the cracking method of the present invention is very suitable for 4-inch LED wafers, and the cracking yield is extremely high.

[0062] The present invention provides a chip splitting method that changes the gap spacing of the support platform with the change of the chip splitting area, thereby improving the support adaptability of the support platform to the chip splitting area of ​​the LED wafer, thereby effectively improving the chip splitting effect of the grains, reducing the generation of twins, and facilitating the improvement of the manufacturing quality of the LED chip. The present invention sets different hammer striking forces according to the thickness distribution of the LED wafer, so that the grains in different thickness areas of the LED wafer can all receive appropriate splitting forces, resulting in a good splitting effect and effectively reducing the occurrence of twins, edge collapse, and the like. Moreover, the adapted hammer striking force can also weaken the degree of deformation of the white film, which is conducive to maintaining a plurality of grains in an orderly arrangement, thereby facilitating the accurate splitting of the splitting knife on the cutting line. The present invention assigns a number to each cutting line in the X-axis direction and the Y-axis direction of the LED wafer, respectively, so that the position and direction of the cutting line can be determined more accurately, thereby more precisely controlling the chip splitting process. At the same time, the cutting line is associated with the corresponding area, so that the area passed by each cutting line can be more conveniently identified and tracked, further improving the efficiency and accuracy of the chip splitting process. After the present invention completes the splitting of the LED wafer, it will also conduct an inspection on the splitting results. If there is a significant abnormality, an investigation and analysis can be carried out in time to avoid losses caused by the continued abnormality.

[0063] The above is a detailed introduction to a method for splitting an LED wafer provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for general technical personnel in this field, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as a limitation on the present invention.

Claims

1. A method for splitting LED wafers, characterized in that: The splitting method comprises the following steps: S1. Apply a white film to the front side of the diced LED wafer and place the back side of the LED wafer upward on the workbench of the wafer splitting machine. S2, resetting the splitting knife and the receiving platform of the splitting machine; Align the cleaver with the back side of the LED wafer, align the support platform with the front side of the LED wafer, and operate the cleaver to align with the center of the gap of the support platform; S3, operating the image recognition system of the wafer splitting machine to obtain an original grain image on the front side of the LED wafer, and performing grain partitioning on the LED wafer based on the original grain image; The inscribed square area of ​​the LED wafer is area A1, and the non-inscribed square area of ​​the LED wafer is area A2; S4, starting the wafer splitting machine, and using the splitting knife to split the LED wafer based on the areas divided by the die partitions; When the splitting knife splits only the A2 area, the gap spacing of the supporting platform is controlled to be c2; when the splitting knife splits the A1 area and the A2 area at the same time, the gap spacing of the supporting platform is controlled to be c1, c1>c2; the length of a single complete grain in the X-axis direction is a, and the length of a single complete grain in the Y-axis direction is b, and the constraint relationship of a, b and c1 is: a≤c1≤1.5a, or b≤c1≤1.5b; the constraint relationship of a, b and c2 is: 0.5a≤c2≤0.8a, or 0.5b≤c2≤0.8b; Wherein, the splitting method further comprises: Before starting the wafer splitting machine, operating the laser thickness gauge of the wafer splitting machine to measure the thickness of the LED wafer, analyzing the overall thickness distribution of the LED wafer, and calculating the average thickness h of the LED wafer; dividing the area on the LED wafer with a thickness greater than the average thickness h into an H1 area, dividing the area on the LED wafer with a thickness equal to the average thickness h into an H2 area, and dividing the area on the LED wafer with a thickness less than the average thickness h into an H3 area; The splitting knife strikes the LED wafer by hammering. When the H1 area accounts for more than or equal to one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G1; when the H2 area accounts for more than or equal to one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G3; when the H3 area accounts for more than or equal to one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G4; when the H1 area, the H2 area and the H3 area all account for less than one half of the area to be split by the splitting knife, the striking force of the hammer is controlled to be G2, G1>G2>G3>G4.

2. The splitting method according to claim 1, wherein: The splitting method further comprises: Before starting the chip splitter, operate the image recognition system of the chip splitter to identify and locate the cutting lines in the X-axis direction of the LED wafer, and assign a number E to each cutting line in the positive direction of the X-axis. x , x is an integer greater than 0; the E x and the area through which the corresponding cutting line passes; operating the image recognition system of the splitting machine to identify and locate the cutting line in the Y-axis direction of the LED wafer, and assigning a number F to each cutting line in the positive direction of the Y-axis. y , y is an integer greater than 0; the F y Associated with the area through which the corresponding cutting line passes.

3. The splitting method according to claim 1, wherein: A tensioning ring is provided on the periphery of the white film on the front surface of the LED wafer, and the bonding width between the white film and the tensioning ring is in the range of 24 to 38 mm.

4. The splitting method according to claim 1, wherein: Before simultaneously splitting the A1 area and the A2 area, the splitting positions of the splitting knife and the receiving platform are calibrated.

5. The splitting method according to claim 1, wherein: After the LED wafer is split, the image recognition system of the wafer splitting machine is operated to obtain the image of the cracked grains on the front of the LED wafer. The original grain image and the cracked grain image are compared by a computer to determine whether twin grains exist.

6. The splitting method according to claim 1, wherein: When the LED wafer is split, dry cold air is used to blow the LED wafer, the temperature of the cold air is in the range of 14 to 16° C., and the speed of the cold air is in the range of 0.6 to 0.9 m / s.

7. The splitting method according to claim 1, wherein: Before the LED wafer is placed in the wafer splitting machine, the defective grains on the outer circle of the LED wafer are removed.

8. The splitting method according to claim 1, wherein: The size of the LED wafer is 4 inches.

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