Wafer Processing Using Polyolefin Sheet Bonding
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Solution Overview
Problem
The existing wafer processing methods generate cutting dust from adhesive tapes, which adheres to device chips, leading to quality degradation during the cutting process.
Innovation Solution
A wafer processing method using a polyolefin sheet without an adhesive layer for thermocompression bonding with the wafer and ring frame, allowing for clean cutting and easy removal of cutting dust, and employing air blowing to pick up device chips, reducing the load on the chips during separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesive tape is used to bond the wafer to the ring frame, then the wafer can be held and processed, but cutting dust from the adhesive layer adheres to the front side of device chips, degrading quality
Solution Approach 1:
The invention extracts and removes the adhesive layer from the bonding structure. Instead of using adhesive tape with an adhesive layer, the patent uses a double-sided tape where only the peripheral portion is bonded to the ring frame, and the central portion is bonded to the wafer back side, but the adhesive layer is completely removed after bonding. This eliminates the source of cutting dust that would otherwise adhere to device chips during cutting operations.
Solution Approach 2:
The invention discards the adhesive layer after it has served its bonding purpose. The adhesive layer is removed completely after the wafer is bonded to the ring frame and before cutting operations begin. This discarding of the adhesive layer prevents it from generating harmful cutting dust during subsequent processing, while the bonding function it provided is preserved and then discarded appropriately.
2Productivity
If the cutting blade is lowered to cut through the wafer, then the wafer is divided into device chips, but cutting dust is generated and adheres to the front side of devices
Solution Approach 1:
The invention performs preliminary action by removing the adhesive layer before the cutting operation begins. The adhesive layer is completely removed after bonding but before cutting, so that when the cutting blade divides the wafer into device chips, there is no adhesive layer present to generate cutting dust that would adhere to the front side of the devices and degrade their quality.
3Ease of manufacture
If adhesive tape is used to unit the wafer and ring frame, then the frame unit is formed, but the adhesive layer generates cutting dust that is difficult to remove in cleaning steps
Solution Approach 1:
The invention extracts and removes the adhesive layer from the system after it has fulfilled its bonding function. The adhesive layer is completely removed after the wafer is bonded to the ring frame, eliminating the source of cutting dust that would otherwise be generated during cutting and be difficult to remove in subsequent cleaning steps.
4Reliability
If the cutting blade reaches below the wafer surface to ensure complete cutting, then the wafer is reliably divided, but the adhesive layer is also cut generating additional cutting dust
Solution Approach 1:
The invention performs preliminary action by removing the adhesive layer before cutting operations. Since the adhesive layer is completely removed after bonding, when the cutting blade is lowered to cut through the wafer and reach below the surface to ensure complete division, there is no adhesive layer present to be cut and generate additional cutting dust.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Prevents cutting dust adherence to device chips, thereby suppressing quality degradation and facilitating reliable cleaning and chip separation.
Implementation Method 1
heating the polyolefin sheet as applying a pressure to the polyolefin sheet after performing the polyolefin sheet providing step, thereby uniting the wafer and the ring frame through the polyolefin sheet by thermocompression bonding
Implementation Method 2
blowing out air from the polyolefin sheet side to push up each device chip and picking up the device chip from the polyolefin sheet
Data Source
AI summary
A wafer processing method includes a polyolefin sheet providing step of positioning a wafer in an inside opening of a ring frame and providing a polyolefin sheet on a back side of the wafer and on a back side of the ring frame, a uniting step of heating the polyolefin sheet as applying a pressure to the polyolefin sheet to thereby unite the wafer and the ring frame through the polyolefin sheet by thermocompression bonding, a dividing step of cutting the wafer by using a cutting apparatus to thereby divide the wafer into individual device chips, and a pickup step of blowing out air to push up each device chip and picking up each device chip from the polyolefin sheet.