Novel blue-film-pasted GPP chip and preparation method thereof

Abstract

The invention belongs to the technical field of semiconductor manufacturing, and provides a novel blue film pasted GPP chip and a preparation method thereof. The preparation method comprises the following steps: S1, carrying out crystal grain testing on a silicon wafer subjected to a metal plating process, sorting out good products and defective products, printing ink dots on crystal grains of the defective products, and then baking; s2, laser cutting is carried out on the back face of the silicon wafer to form a laser groove, and dust is sucked away while cutting is carried out; s3, a blue film is attached to the back face of the product obtained in the S2, an iron ring is arranged on the blue film, the width of the blue film is larger than the diameter of the silicon wafer, and a gap is formed between the inner edge of the iron ring and the outer edge of the silicon wafer; s4, a rubber roller is adopted for rolling the front face of the product obtained in the S3, so that the reserved amount positions between the laser grooves are cracked to separate crystal grains; and S5, carrying out whole piece appearance inspection on the product obtained in the step S4 by adopting a microscope, and marking the crystal grains with poor appearance by using a marking pen. According to the invention, the stability of the crystal grains can be improved, and the problem of unstable quality caused by corner collision is avoided.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor manufacturing, and in particular to a novel blue film GPP chip and a preparation method thereof. Background Art

[0002] GPP chip is a chip that uses glass passivation technology, which is mainly used to protect the PN junction of the chip and prevent the external environment from interfering with and damaging the internal circuit of the chip. This chip is commonly used in diodes, triodes, thyristors, rectifier bridges and other devices, and has high reliability and stability.

[0003] In the GPP process, wafer scribing is an indispensable process. The traditional scribing process uses mechanical blades for cutting, but this method has disadvantages such as slow cutting speed, low precision, and easy edge collapse. Therefore, with the development of technology, laser cutting technology has gradually been introduced into the wafer scribing process. The basic principle of laser cutting is to use a high-energy-density laser beam to irradiate the surface of the wafer, so that the wafer material quickly melts, evaporates or reaches the ignition point, thereby achieving cutting. The current scribing process includes testing, cutting, cracking, appearance selection, and packaging. After the grains are packaged, they are screened on a sieve plate, and the screened sieve plate is taken to the machine for automatic picking. This method has the following problems.

[0004] (1) Isopropyl alcohol is required for adsorption during the splitting process. Isopropyl alcohol is flammable and explosive, so there are safety hazards during the operation; (2) The appearance selection is carried out by an automatic appearance selection machine, which selects the appearance of grains one by one from the oscillating plate. There are constant collisions between grains and between grains and the rotating track, which causes the grains to collapse and have corners missing; (3) The packaging needs to be screened with a sieve plate first. This method will cause the grains to collide with each other and with the sieve plate, resulting in the phenomenon of grain edge collapse and chipping; ultimately leading to unstable product quality. Summary of the invention

[0005] In view of the defects in the prior art, the present invention provides a novel blue film GPP chip and a preparation method to solve the safety hazards in the current GPP chip dicing process, and the problem of chipping and corner breakage easily caused by appearance selection and packaging screening.

[0006] In a first aspect, the present invention provides a novel method for preparing a blue film GPP chip, comprising: S1. Test the silicon wafers that have completed the metallization process, sort out good and bad products, and put ink dots on the bad products, and then bake them; S2. Laser cutting is performed from the back of the silicon wafer to form a laser groove, and dust is sucked away while cutting; after laser cutting, there is a reserved vertical distance between the bottom of the etched groove and the bottom of the laser groove; S3. A blue film is attached to the back of the product obtained in S2, and an iron ring is arranged on the blue film, wherein the width of the blue film is greater than the diameter of the silicon wafer, and there is a gap between the inner edge of the iron ring and the outer edge of the silicon wafer; when the crystal bonding machine is used to bond the crystal later, the blue film provides tension to facilitate the transfer of the crystals one by one; S4. placing a buffer layer under the product obtained in S3, and rolling the front side of the product obtained in S3 with a rubber roller, so that the laser groove is cracked from the reserved amount to separate the grains; S5. Use a microscope to inspect the appearance of the entire product obtained in S4, and mark the grains with poor appearance with a marker.

[0007] It can be seen from the above technical scheme that the present invention provides a novel method for preparing a blue film GPP chip. First, direct chipping is performed during chipping without using isopropyl alcohol for adsorption, which can improve the safety during operation and reduce the collision between grains during chipping. It is used in conjunction with a die bonding machine for subsequent packaging. Optionally, the ink dots in S1 are made of ink material, and the baking temperature is 60-140° C. and the baking time is 10-30 minutes.

[0008] Optionally, the S2 is laser cut by a fully automatic laser cutting machine; the laser frequency is 40-80kHz, the laser power is 20%-90%, the cutting depth is 60-90μm, the groove width of the laser groove is ≥60μm, and the spacing between adjacent laser grooves is ≤100μm.

[0009] Optionally, in S2, the vertical distance of the reserved amount after laser cutting is 20-40 μm.

[0010] Optionally, in S3, a blue film machine is used to apply the blue film, and pressure is applied between the blue film and the silicon wafer, and between the blue film and the iron ring. The temperature of the blue film machine is 40-80°C.

[0011] Optionally, the model of the blue film is SPV-224SRB.

[0012] Optionally, in S4, the rubber roller is rolled 1-3 times, the size of the buffer layer is larger than the size of the silicon wafer, and the buffer layer is filter paper.

[0013] In the second aspect, the present invention provides a novel blue film GPP chip, which is prepared based on any possible implementation form of the first aspect. The novel blue film GPP chip provided by the present invention is shipped in the form of silicon wafers attached to the blue film and fixed on an iron ring; during the later crystal bonding, the blue film provides tension to transfer the grains one by one, and the later packaging uses a crystal bonding machine instead of the sieve plate to screen the grains, which causes the collision of the grain corners, and can improve the stability of the grains.

[0014] By adopting the above technical solution, the present application has the following beneficial effects: The present invention performs direct slicing during slicing without using isopropyl alcohol for adsorption, which can improve the safety during operation, reduce the collision between crystal grains during slicing, and reduce the process cost. The appearance selection of the present invention adopts the whole-piece inspection method, which avoids the problem of unstable grain quality caused by collision between grains when using AOI to select the appearance of a single grain; The novel blue film GPP chip prepared by the present invention is shipped in a manner that the silicon wafer is attached to the blue film and fixed on an iron ring; during the post-process packaging, a crystal bonding machine is used to replace the collision of crystal corners caused by the sieve plate sieving crystal grains, thereby improving the stability of the crystal grains. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for the specific embodiments or the description of the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn according to the actual scale.

[0016] Figure 1 A flow chart showing a method for preparing a novel blue film GPP chip provided by an embodiment of the present invention; Figure 2 A schematic diagram of the product obtained by S2 provided in an embodiment of the present invention is shown; Figure 3 A schematic diagram of the product obtained by S3 provided in an embodiment of the present invention is shown; Figure 4 Another schematic diagram of the product obtained by S3 provided in an embodiment of the present invention is shown.

[0017] Reference numerals: 1-silicon wafer; 11-laser groove; 12-etched groove; 2-blue film; 3-iron ring; 4-buffer layer. DETAILED DESCRIPTION

[0018] The following embodiments of the technical solution of the present invention are described in detail in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and are therefore only used as examples, and cannot be used to limit the protection scope of the present invention. It should be noted that, unless otherwise specified, the technical terms or scientific terms used in this application should have the common meanings understood by those skilled in the art to which the present invention belongs.

[0019] Example 1 like Figure 1 As shown, this embodiment provides a novel method for preparing a blue film 2GPP chip, which is used in conjunction with a die bonding machine for back-end packaging, and includes: S1. Silicon wafer 1 is tested by a probe station. According to the set test conditions, the silicon wafer 1 after nickel plating is tested for grains, good and bad products are sorted out, and ink dots are marked on the grains of bad products, and then baked. The baking temperature is 60-140°C and the time is 10-30 minutes. In this embodiment, the baking temperature is specifically 80°C and the time is specifically 30 minutes.

[0020] S2. Laser cutting. Laser cutting is performed from the back of the silicon wafer 1 to form a laser groove 11, and dust is removed while cutting. After laser cutting, there is a reserved vertical distance between the bottom of the etched groove 12 and the bottom of the laser groove 11. , see Figure 4 Part 1 of the silicon wafer.

[0021] In this step, a fully automatic laser cutting machine is used for laser cutting; the laser frequency is 40-80kHz, the laser power is 20%-90%, the cutting depth is 60-90μm, the groove width of the laser groove is ≥60μm, and the spacing between adjacent laser grooves is ≤100μm. The vertical distance of the reserved amount after laser cutting can be 20-40μm.

[0022] Specifically in this embodiment, the fully automatic laser cutting machine uses a laser frequency of 60 kHz, a laser power of 50%, and a cutting depth of 70 μm for cutting, and the reserved amount after cutting is 30 μm.

[0023] It should be noted that the frequency and power of laser cutting determine the cutting depth. When the laser power increases, the cutting depth will increase, but the dust must be removed simultaneously, otherwise the cutting depth cannot be guaranteed; the laser frequency is the frequency of laser scanning, and the consistency will increase with the increase of frequency, but there will be burn marks on the N side of the grain; on this basis, the reserved amount needs to meet the predetermined conditions, while ensuring the splitting effect, it can not only improve the efficiency of laser cutting, but also avoid damage to the grain.

[0024] S3. Paste the blue film 2 and adhere it to the iron ring 3. Figure 3-4As shown, a blue film 2 is attached to the back of the product obtained in S2, and an iron ring 3 is set on the blue film 2. The width of the blue film 2 is greater than the diameter of the silicon wafer 1, and there is a gap between the inner edge of the iron ring 3 and the outer edge of the silicon wafer 1; when the die bonder is used to bond the die later, the blue film 2 provides tension to facilitate the transfer of the die one by one. The model of the blue film 2 is SPV-224SRB.

[0025] In this step, a blue film machine is used to attach the blue film 2, and pressure is applied between the blue film 2 and the silicon wafer 1, and between the blue film 2 and the iron ring 3. The temperature of the blue film machine is 40-80°C.

[0026] Specifically in this embodiment, the temperature on the blue film machine is 60° C. To facilitate the subsequent die bonding by the die bonding machine, the blue film 2 can be stretched for loading, so as to accurately transfer the die one by one.

[0027] Depend on Figure 3 It can be seen that the width of the blue film is smaller than the inner diameter of the iron ring. This operation can reduce the process cost while ensuring the S4 splitting effect.

[0028] S4. Splitting. Place a buffer layer 4 under the product obtained in S3, and split the silicon wafer 1 with the blue film 2 attached. At this time, split directly without dipping in isopropyl alcohol, and use the rubber roller to roll 1-3 times. Push the rubber roller (pushers) along the direction of the groove to split the grains from the reserved amount. The rubber roller is pushed once during splitting. When rolling, 1-3 layers of filter paper need to be placed under the silicon wafer 1. The size of the filter paper should be larger than that of the silicon wafer 1 to prevent the grains from being squeezed and damaged.

[0029] The splitting process of this step does not use isopropyl alcohol for adsorption, which can improve the safety of the operation process. At the same time, the flexibility of the buffer layer 4 used in this step needs to meet certain requirements. A buffer material that is too hard will crush the silicon wafer 1. Although a buffer material that is too soft will reduce the risk of crushing, it may cause the problem of splitting failure for silicon wafers 1 of some specifications.

[0030] The buffer layer 4 used in this step is the filter paper used in the boron coating station. Those skilled in the art can determine the specific specification requirements of the filter paper used, which will not be described here.

[0031] S5. Whole-wafer appearance inspection. The silicon wafer 1 that has been split in step S4 is selected by appearance. The separated grains are still arranged on the blue film 2 in the original order. At this time, the bad ones are marked with a marker pen to facilitate identification during the later crystal bonding. The marker pen is an oil-based marker pen that is easy to dry and does not disappear easily.

[0032] Example 2 like Figure 1 As shown, this embodiment provides a novel method for preparing a blue film 2GPP chip, which is used in conjunction with a die bonding machine for back-end packaging, and includes: S1. Silicon wafer 1 is tested by a probe station. The silicon wafer 1 after nickel plating is tested by a probe station. According to the set test conditions, the grains are tested, good and bad products are sorted, and ink dots are marked on the grains of bad products, and then baked. In this embodiment, the baking temperature is 140°C and the time is 10 minutes.

[0033] S2. Laser cutting. Laser cutting is performed from the back of the silicon wafer 1 to form a laser groove 11, and dust is removed while cutting. After laser cutting, there is a reserved vertical distance between the bottom of the etched groove 12 and the bottom of the laser groove 11. .

[0034] The fully automatic laser cutting machine uses a laser frequency of 70kHz, a laser power of 60%, a cutting depth of 80μm, a laser groove width of ≥60μm, and a spacing of adjacent laser grooves of ≤100μm. The vertical distance of the reserved amount after cutting is 25μm.

[0035] It should be noted that, according to the thickness difference of different silicon wafers 1, the cutting depth and the vertical distance of the reserved amount are different.

[0036] S3. Paste the blue film 2 and adhere it to the iron ring 3. Figure 3-4 As shown, a blue film 2 is attached to the back of the product obtained in S2, and an iron ring 3 is set on the blue film 2. The width of the blue film 2 is greater than the diameter of the silicon wafer 1, and there is a gap between the inner edge of the iron ring 3 and the outer edge of the silicon wafer 1; when the crystal is fixed by the crystal fixing machine later, the blue film 2 provides tension to facilitate the transfer of each crystal.

[0037] The cut silicon wafer 1 is pasted with a blue film 2 and an iron ring 3 on a blue film machine at a certain temperature. The temperature of the blue film machine is 80°C. The blue film 2 is SPV-224SRB. In order to facilitate the subsequent die bonding of the die bonding machine, the blue film 2 can be stretched for loading.

[0038] S4. Splitting. A buffer layer 4 is placed under the product obtained in S3, and the silicon wafer 1 with the blue film 2 attached is split. In this case, the silicon wafer 1 is split directly.

[0039] The silicon wafer 1 with the blue film 2 attached is split directly without dipping in isopropyl alcohol. The rubber roller is pushed along the direction of the groove, and the rubber roller is pushed twice during the splitting. The buffer layer 4 is set to 3 layers of filter paper to prevent the grains from being squeezed and damaged, while ensuring that the grains can be separated.

[0040] S5. Whole wafer appearance inspection. The silicon wafers 1 that have been split in step S4 are selected by appearance, and the bad ones are marked with a marker pen to facilitate identification during the subsequent crystal bonding. The marker pen is an oil-based marker pen that is easy to dry and does not easily disappear.

[0041] Example 3 This embodiment provides a novel blue film 2GPP chip, which is prepared based on the preparation method provided in Example 1 or Example 2.

[0042] The new blue film 2GPP chip provided in this embodiment is shipped in the form of a silicon wafer 1 attached to a blue film 2 and fixed on an iron ring 3; during the later crystal bonding, the blue film 2 provides tension to transfer the crystals one by one. The new blue film 2GPP chip provided in this embodiment uses a crystal bonding machine instead of a sieve plate to screen the crystals, which causes the collision of the crystal corners, and can improve the stability of the crystals.

[0043] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A method for preparing a novel blue film GPP chip, characterized in that: Used with the die bonder for back-end packaging, including: S1. Test the silicon wafers that have completed the metallization process, sort out good and bad products, and put ink dots on the bad products, and then bake them; S2. Laser cutting is performed from the back of the silicon wafer to form a laser groove, and dust is sucked away while cutting; after laser cutting, there is a reserved vertical distance between the bottom of the etched groove and the bottom of the laser groove; S3. A blue film is attached to the back of the product obtained in S2, and an iron ring is arranged on the blue film, wherein the width of the blue film is greater than the diameter of the silicon wafer, and there is a gap between the inner edge of the iron ring and the outer edge of the silicon wafer; when the crystal bonding machine is used to bond the crystal later, the blue film provides tension to facilitate the transfer of the crystals one by one; S4. placing a buffer layer under the product obtained in S3, and rolling the front side of the product obtained in S3 with a rubber roller to crack the reserved space between the laser grooves to separate the grains; S5. Use a microscope to inspect the appearance of the entire product obtained in S4, and mark the grains with poor appearance with a marker.

2. The method according to claim 1, characterized in that The ink dots in S1 are made of ink material, and the baking temperature is 60-140° C. and the baking time is 10-30 minutes.

3. The method according to claim 1, characterized in that The S2 is laser cut by a fully automatic laser cutting machine; the laser frequency is 40-80kHz, the laser power is 20%-90%, the cutting depth is 60-90μm, the groove width of the laser groove is ≥60μm, and the spacing between adjacent laser grooves is ≤100μm.

4. The method according to claim 3, characterized in that In S2, the vertical distance of the reserved amount after laser cutting is 20-40 μm.

5. The method according to claim 3, characterized in that: The S3 uses a blue film machine to perform the blue film sticking operation, and applies pressure between the blue film and the silicon wafer, and between the blue film and the iron ring. The temperature of the blue film machine is 40-80°C.

6. The method according to claim 5, characterized in that The model of the blue film is SPV-224SRB.

7. The method according to claim 3, characterized in that The number of times the rubber roller is rolled in S4 is 1-3 times, the size of the buffer layer is larger than the size of the silicon wafer, and the buffer layer is filter paper.

8. A new blue film GPP chip, characterized in that: The method is prepared based on any one of claims 1 to 7.

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