A method for selectively laser-de-visualizing UV films on wafers

Abstract

This invention relates to the field of semiconductor packaging technology, specifically a method for selectively removing UV film from wafers using laser technology. The method includes the following steps: S1, applying a UV film to the back of the wafer and installing a metal ring support; S2, laser-grooving the front of the wafer with a 600-micron kerf width, followed by a double-blade dicing process along both sides of the kerf, leaving residual material on the kerf; S3, selecting the desired chip as the area requiring removal based on a mapping diagram, and designating other areas as areas not requiring removal, including areas with residual material; S4, removing the UV film from the areas requiring removal using a pulsed laser; S5, peeling the chip off from the UV film. Compared to existing technologies, this method effectively prevents chip damage caused by residual material adhering to or splashing onto the chip, significantly improving wafer dicing and pick-up yield, and enhancing the controllability and stability of wafer processing.

Description

Technical Field

[0001] This invention relates to the field of semiconductor packaging technology, and more specifically to a method for selectively removing UV films from wafers using laser technology. Background Technology

[0002] With the development of technology, wafers can achieve more functions or more storage space by stacking multiple layers. However, multi-layer stacking of wafers will lead to increased stress and increased risk of edge chipping. There will be stacking errors when stacking multiple layers. As the stacking errors accumulate, the process becomes more complicated and requires a larger operating space. Usually, the method of increasing the width of the dicing track is adopted.

[0003] However, when removing the UV coating from a wafer, this operation is performed on the entire wafer. This overall removal reduces the adhesiveness of the UV coating in all areas within the dicing channel, causing the residual material generated during the previous dicing process to lose its adhesive bond. Furthermore, because the dicing channel is widened, during subsequent chip mounting operations, such as chip ejection or pick-up, residual material within the dicing channel may adhere to the chip or splatter during pickup, causing multiple chips to stick together, chips to fly away, and in severe cases, even damaging adjacent good chips, reducing product yield. Summary of the Invention

[0004] To address the problems mentioned in the background art, this invention provides a method for selectively removing UV film from wafers using laser technology, comprising the following steps: S1, applying UV film to the back of the wafer and installing an iron ring support; S2, laser-grooving the front of the wafer with a 600-micron kerf width, followed by double-blade cutting along both sides of the kerf, leaving excess material on the kerf; S3, selecting the desired chip as the area requiring removal based on the mapping diagram, and designating other areas as areas not requiring removal, including the areas with excess material; S4, removing the UV film from the areas requiring removal using a pulsed laser. The pulsed laser determines the laser repetition frequency f, single-pulse energy E, and average power P based on the set spot area and laser scanning speed, using the following calculation formula: E = ρ×S; f=v / d; P=E×f; where S is the spot area, ρ is the debonding energy density of the UV film, v is the laser scanning speed, and d is the spot diameter; S5. After laser debonding, the chip is lifted by a pin and picked up by a vacuum nozzle to peel the chip off from the UV film.

[0005] The area with remaining material in step S3 is specifically a strip-shaped area with a width of 100 micrometers, based on the center line of the cutting track.

[0006] In step S4, the pulsed laser uses a wavelength of 355 nanometers.

[0007] In step S4, the pulsed laser performs an N-shaped scan of the UV film containing the area that needs to be debonded.

[0008] In step S4, when the pulsed laser is used to desorb the adhesive with a spot diameter of 200 μm and a laser scanning speed of 200 mm / s, the repetition frequency f is 1000 Hz, the single pulse energy E is 62.8 μJ, and the average power P is 62.8 mW.

[0009] In step S4, when the pulsed laser is used to desorb the adhesive with a spot diameter of 100 μm and a laser scanning speed of 200 mm / s, the repetition frequency f is 2000 Hz, the single pulse energy E is 16 μJ, and the average power P is 32 mW.

[0010] In step S4, when the pulsed laser is used to desorb the adhesive with a spot diameter of 50 μm and a laser scanning speed of 200 mm / s, the repetition frequency f is 4000 Hz, the single pulse energy E is 4 μJ, and the average power P is 16 mW.

[0011] Compared with existing technologies, this invention, by setting a 600μm dicing width and employing a combination of laser grooving and double-blade cutting, ensures that residual material remains fixed on the UV film after dicing. This prevents residual material from adhering to the chip or splattering, effectively preventing chip damage caused by residual material and significantly improving wafer dicing and pick-up yield. By employing selective region laser debonding technology based on mapping, the adhesion of different areas of the UV film can be precisely controlled, improving the controllability and stability of wafer processing. The laser ensures debonding efficiency without causing thermal damage to the wafer chip, demonstrating strong adaptability. Attached Figure Description

[0012] Figure 1 Flowchart of laser wafer UV film removal method; Figure 2 This is a schematic diagram of a wafer structure. Detailed Implementation

[0013] The present invention will now be further described with reference to the accompanying drawings.

[0014] like Figure 1A method for selectively removing UV film from wafers using laser technology includes the following steps: S1. Applying UV film to the back of the wafer and installing iron ring supports; S2. Laser grooving the front of the wafer with a groove width of 600 micrometers, followed by double-blade cutting along both sides of the groove, leaving excess material on the groove; S3. Selecting the desired chip as the area requiring debonding based on the mapping diagram, and designating other areas as areas not requiring debonding, including areas with excess material; S4. Removing the UV film from the areas requiring debonding using a pulsed laser. The pulsed laser determines the laser repetition frequency f, single pulse energy E, and average power P based on the set spot area and laser scanning speed, using the following formulas: E = ρ × S; f = v / d; P = E × f; where S is the spot area, ρ is the UV film debonding energy density, v is the laser scanning speed, and d is the spot diameter; S5. After laser debonding, using a lifting pin to lift the chip and a vacuum nozzle to pick it up, peeling the chip off the UV film.

[0015] The area with remaining material in step S3 is specifically a strip area with a width of 100 micrometers, based on the center line of the cutting track.

[0016] In step S4, the pulsed laser uses a wavelength of 355 nanometers.

[0017] In step S4, the pulsed laser performs an N-shaped scan of the UV film containing the area that needs to be debonded.

[0018] In step S4, when the pulsed laser is used to desorb the adhesive with a spot diameter of 200 μm and a laser scanning speed of 200 mm / s, the repetition frequency f is 1000 Hz, the single pulse energy E is 62.8 μJ, and the average power P is 62.8 mW.

[0019] In step S4, when the pulsed laser is used to desorb the adhesive with a spot diameter of 100 μm and a laser scanning speed of 200 mm / s, the repetition frequency f is 2000 Hz, the single pulse energy E is 16 μJ, and the average power P is 32 mW.

[0020] In step S4, when the pulsed laser is used to desorb the adhesive with a spot diameter of 50 μm and a laser scanning speed of 200 mm / s, the repetition frequency f is 4000 Hz, the single pulse energy E is 4 μJ, and the average power P is 16 mW.

[0021] The chip testing method of the present invention will be described below with reference to specific examples.

[0022] First, a UV film is attached to the back of a 12-inch multilayer stacked wafer and fixed to a metal ring. Then, laser grooving is performed along 600μm wide dicing channels. Next, a dual-blade dicing machine is used to cut along the grooved channels. After cutting, residual material remains between the two blades. Based on the wafer's mapping, the location of the chip is determined as the area requiring debonding. A 100μm area along the center line of each dicing channel is designated as the non-debonding area. Laser debonding is performed with a pulsed laser spot diameter of 200μm, a laser scanning speed v of 200mm / s, a repetition frequency f of 1000Hz, a single pulse energy E of 62.8μJ, and an average power P of 62.8mW. When reaching the debonding area, the laser debonds the UV film in that area. When reaching the non-debonding area, the laser output is turned off. After laser debonding, the adhesiveness of the UV film in the chip area has decreased. The chip is lifted by a pin and then sucked up by a vacuum nozzle to peel the chip off from the UV film. The remaining material is fixed on the UV film because the UV film below still has high adhesiveness and will not be lifted up, thus not causing any interference to other chips.

Claims

1. A method for selective area laser de-crystallization of a UV film on a wafer, the method comprising: Includes the following steps: S1. Apply a UV film to the back of the wafer and install a metal ring support; S2. Laser-grooving is performed on the front of the wafer, followed by double-blade dicing along both sides of the dicing track. The dicing track width is 600 micrometers, leaving some material on the track; S3. Based on the mapping diagram, select the required chips as the areas requiring debonding, and designate other areas as areas not requiring debonding, including areas with remaining material; S4. Use a pulsed laser to remove the UV film from the areas requiring debonding. The pulsed laser determines the laser repetition frequency f, single pulse energy E, and average power P based on the set circular spot diameter and laser scanning speed. The calculation formulas include: E = ρ × S; f = v / d; P = E × f; Where S is the area of ​​the circular light spot, ρ is the debonding energy density of the UV film, v is the laser scanning speed, and d is the light spot diameter; S5. After laser debonding, the chip is lifted by a pin and picked up by a vacuum nozzle to peel the chip off from the UV film.

2. The method of claim 1, wherein: The area with remaining material in step S3 is specifically a strip-shaped area with a width of 100 micrometers, based on the center line of the cutting track.

3. The method of claim 1, wherein: In step S4, the pulsed laser uses a wavelength of 355 nanometers.

4. The method of claim 1, wherein: In step S4, the pulsed laser performs an N-shaped scan of the UV film containing the area that needs to be debonded.

5. The method of claim 1, wherein: In step S4, when the pulsed laser uses a circular spot diameter of 200 μm and a laser scanning speed of 200 mm / s for debonding, the repetition frequency f is 1000 Hz, the single pulse energy E is 62.8 μJ, and the average power P is 62.8 mW.

6. The method of claim 1, wherein: In step S4, when the pulsed laser uses a circular spot diameter of 100μm and a laser scanning speed of 200mm / s to desorb the adhesive, the repetition frequency f is 2000Hz, the single pulse energy E is 16μJ, and the average power P is 32mW.

7. The method of claim 1, wherein: In step S4, when the pulsed laser uses a circular spot diameter of 50 μm and a laser scanning speed of 200 mm / s for debonding, the repetition frequency f is 4000 Hz, the single pulse energy E is 4 μJ, and the average power P is 16 mW.

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