A pretreatment method for plasma cutting of filter chip wafers

Abstract

The present invention provides a pretreatment method for plasma cutting of filter chip wafers. This method ensures uniform application of protective liquid, resulting in consistent groove widths during subsequent laser cutting, effectively preventing bridging and improving chip yield. The method utilizes a two-step spin-coating process, ensuring uniform and dense application of the protective liquid while significantly minimizing air bubbles and reducing etching black spots caused by these bubbles by approximately 90%, effectively ensuring the quality of subsequent cutting.

Description

Technical Field

[0001] The present invention relates to the technical field of filter chip testing, in particular to a pretreatment method for plasma cutting of filter chip wafers. Background Art

[0002] As chip sizes continue to shrink and factory automation levels improve, the precision, speed, and quality of wafer dicing, a crucial step in the chip packaging process, are becoming increasingly important. Plasma dicing, with its high cutting efficiency and non-destructive processing, is gaining increasing popularity.

[0003] Plasma cutting is a typical dry etching process. It mainly generates plasma through high-voltage discharge, and reacts chemically with silicon-based chips under bias. For filter chips, in order to prevent problems such as misalignment, excessive width, and over-etching of the cutting path during plasma cutting, it is necessary to coat the cutting path with a layer of protective liquid before plasma cutting for pre-cutting treatment and protection of the non-cutting area. Chinese invention patent application number CN201911017463.8 discloses a processing method for wafer cutting and separation. Since it adopts a one-step spin coating method to apply the protective liquid, it is difficult to apply the protective liquid layer on the surface of the wafer evenly and it is easy to produce bubbles. The uneven protective liquid layer will lead to uneven groove width during subsequent laser grooving, which is easy to produce bridging. The bubbles will burst during the subsequent plasma etching process, and the protective liquid in the broken part will not have a protective effect, which is easy to produce etching black spots, affecting the chip yield. Summary of the Invention

[0004] In view of the problem that in the existing wafer cutting, a one-step spin coating method is used to apply the protective liquid, which makes it difficult to apply the protective liquid evenly, resulting in large differences in the width of the cutting paths of subsequent laser grooving, prone to bridging, and ultimately affecting the chip yield. The present invention provides a pretreatment method for plasma cutting of filter chip wafers, which can ensure that the protective liquid can be applied evenly, so that the width of the grooves of subsequent laser cutting is consistent, effectively preventing the bridging phenomenon, and improving the chip yield.

[0005] The technical solution is as follows: a pretreatment method for plasma cutting of filter chip wafers, characterized in that it includes the following steps:

[0006] Step 1: Place the pre-cut surface of the filter chip wafer upwards, with the EGT composite film layer connected to its bottom, and a wafer ring support provided at the bottom of the composite film layer;

[0007] Step 2. Fix the filter wafer processed in step 1 on the wafer turntable, first control the wafer turntable to idle at a low speed of 5rpm / s for 10s, then turn on the protective liquid nozzle, spray 5~30ml of protective liquid onto the surface of the filter chip wafer, and then close the protective liquid nozzle. Then accelerate the wafer turntable to 2000rpm / s and hold for 30s, then turn on the deionized water nozzle to clean the filter wafer surface. At this time, the speed of the wafer turntable is 400rpm / s, and the time is 60s. Then adjust the wafer speed to 5rpm / s, and finally turn on the protective liquid nozzle again, spray 15~90 ml of protective liquid, and then close the protective liquid nozzle. Control the wafer turntable to evenly accelerate to 200rpm / s, 400rpm / s and 800rpm / s, and the corresponding holding time is 30s, 30s, and 150s respectively. The thickness of the protective liquid layer on the surface of the filter wafer is 1μm~15μm;

[0008] Step 3: The filter wafer processed in step 2 is slotted along its transverse and longitudinal pre-cutting paths using a two-step laser slotting method, with a slot width of 5 μm to 30 μm and a slot depth of 2-3 μm.

[0009] The method is further characterized in that: in step 1, the filter chip wafer is made of silicon substrate, the wafer size is one of 6 inches, 8 inches or 12 inches, the wafer thickness should be 80-120 μm, the wafer ring support is made of stainless steel, and the EGT composite film layer is one of polymethacrylic acid or silicone;

[0010] In step 2, the spraying speed of the protective liquid is 0.5 ml / s to 1.0 ml / s, and the protective liquid is one of polyvinyl alcohol or polyether protective liquids;

[0011] In step 3, the laser is selected as a picosecond laser with a laser energy of 0.1W~15W, a pulse duration of 1fs~10fs, and a laser frequency of 100KHz~1MHz;

[0012] In step 3, the two-step grooving method is to first use infrared laser to locate the surface of the filter wafer, then groove the horizontal or vertical cutting path on the surface of the filter wafer once, and then repeat the above operation, that is, groove the position of the previous groove a second time to ensure the grooving effect.

[0013] After adopting the above method, a layer of protective liquid is first coated on the surface of the filter wafer, which is then rotated at high speed and then cleaned with plasma water. At this time, the protective liquid on the surface of the filter wafer forms a uniform thin layer. At the same time, the protective liquid has strong adhesion. More protective liquid is then sprayed onto the surface of the filter wafer, and the acceleration is continued uniformly, so that the protective liquid is evenly and densely covered on the surface of the filter wafer, and the generation of bubbles and other defects is reduced, so that the width of the subsequent laser-cut grooves can be consistent, effectively preventing the occurrence of bridging phenomena and improving the chip yield. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 This is a schematic structural diagram of the filter chip wafer of the present invention;

[0015] 1. Filter chip wafer; 2. Protective liquid layer; 3. Slot position in step 3. DETAILED DESCRIPTION

[0016] A pretreatment method for plasma cutting of filter chip wafers comprises the following steps:

[0017] Step 1: Place the pre-cut surface of the filter chip wafer upward, with the bottom connected to the EGT composite film layer, and a wafer ring bracket is provided at the bottom of the composite film layer.

[0018] Step 2: Fix the filter wafer processed in step 1 on the wafer turntable. First, control the wafer turntable to idle at a low speed of 5rpm / s for 10s, then turn on the protective liquid nozzle, spray 5~30ml of protective liquid onto the surface of the filter chip wafer, and then close the protective liquid nozzle. Then accelerate the wafer turntable to 2000rpm / s and maintain for 30s. Then turn on the deionized water nozzle to clean the surface of the filter wafer. At this time, the speed of the wafer turntable is 400rpm / s and the time is 60s. Then adjust the wafer speed to 5rpm / s and finally turn on the protective liquid nozzle again to spray 15~90 After spraying 1 ml of protective liquid, the protective liquid nozzle is closed, and the wafer turntable is controlled to accelerate evenly to 200 rpm / s, 400 rpm / s and 800 rpm / s, and the corresponding holding time is 30s, 30s and 150s respectively. The thickness of the protective liquid layer on the surface of the filter wafer is 1μm~15μm; through the two-step spin coating of the protective liquid, not only the protective liquid is evenly and densely coated, but also the bubble phenomenon can be greatly reduced. The etching black spots caused by bubbles are also reduced by about 90%, effectively ensuring the quality of subsequent cutting.

[0019] Step 3: The filter wafer processed in step 2 is slotted along its transverse and longitudinal pre-cutting paths using a two-step laser slotting method, with a slot width of 5 μm to 30 μm and a slot depth of 2-3 μm.

[0020] All the above steps are completed in a clean room with a cleanliness level of >10000 (in compliance with US Federal Standard 209E), an ambient temperature of 25±2°C, and a relative humidity of 45±10%.

[0021] Furthermore, in step 1, the filter chip wafer adopts a silicon substrate, the wafer size is one of 6 inches, 8 inches or 12 inches, the wafer thickness should be 80~120μm, the wafer ring bracket is made of stainless steel, and the EGT composite film layer is a polymethacrylate or silicone type.

[0022] Furthermore, in step 2, the spraying speed of the protective liquid is 0.5 ml / s to 1.0 ml / s, and the protective liquid is one of polyvinyl alcohol or polyether protective liquids.

[0023] Furthermore, in step 3, the laser is selected to be a picosecond laser, the laser energy is 0.1W~15W, the pulse duration is 1fs~10fs, the laser frequency is 100KHz~1MHz, and the speed of laser grooving is 500mm / s~1000mm / s.

[0024] Furthermore, in step 3, the two-step grooving method is to use infrared laser to locate the surface of the filter wafer, first groove the horizontal or vertical cutting path on the surface of the filter wafer respectively, and then repeat the above operation, that is, groove the position of the previous groove a second time. Grooving by the two-step grooving method can effectively prevent the high temperature during the first grooving from causing the protective liquid to flow back and cause the groove to be blocked, so as to ensure the grooving effect.

[0025] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by anyone familiar with the art within the technical scope disclosed by the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be based on the scope of protection of the claims.

Claims

1. A pretreatment method for plasma cutting of filter chip wafers, characterized by: It includes the following steps: Step 1: Place the pre-cut surface of the filter chip wafer upwards, with the EGT composite film layer connected to its bottom, and a wafer ring support provided at the bottom of the composite film layer; Step 2. Fix the filter wafer processed in step 1 on the wafer turntable, first control the wafer turntable to idle at a low speed of 5rpm / s for 10s, then turn on the protective liquid nozzle, spray 5~30ml of protective liquid onto the surface of the filter chip wafer, and then close the protective liquid nozzle. Then accelerate the wafer turntable to 2000rpm / s and hold for 30s, then turn on the deionized water nozzle to clean the surface of the filter wafer so that the protective liquid on the surface of the filter wafer forms a uniform thin layer. At this time, the speed of the wafer turntable is 400rpm / s, and the time is 60s. Then adjust the wafer speed to 5rpm / s, and finally turn on the protective liquid nozzle again, spray 15~90 ml of protective liquid, and then close the protective liquid nozzle. Control the wafer turntable to evenly accelerate to 200rpm / s, 400rpm / s and 800rpm / s, and the corresponding holding time is 30s, 30s, and 150s, respectively. The thickness of the protective liquid layer on the surface of the filter wafer is 1μm~15μm; Step 3, the filter wafer processed in step 2, using a two-step laser grooving method along its transverse and longitudinal pre-cutting road to groove, the groove width is 5μm~30μm, the groove depth is 2-3um; In step 2, the spraying speed of the protective liquid is 0.5 ml / s to 1.0 ml / s, and the protective liquid is one of polyvinyl alcohol or polyether protective liquids; In step 3, the two-step slotting method is to first use infrared laser positioning on the filter wafer surface, then slot the horizontal or vertical cutting path on the filter wafer surface once, and then repeat the above operation, that is, slot the second time at the position of the previous slot to ensure the slotting effect; The EGT composite membrane layer is a polymethacrylic acid or silica gel type.

2. The pretreatment method for plasma cutting of filter chip wafers according to claim 1, characterized in that: In step 1, the filter chip wafer uses a silicon substrate, the wafer size is one of 6 inches, 8 inches or 12 inches, the wafer thickness is 80~120μm, and the wafer ring bracket is made of stainless steel.

3. The pretreatment method for plasma cutting of filter chip wafers according to claim 1, characterized in that: In step 3, the laser is selected as a picosecond laser, the laser energy is 0.1W~15W, the pulse duration is 1fs~10fs, and the laser frequency is 100KHz~1MHz.

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