Wafer Processing Without Adhesive Layer
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Solution Overview
Problem
The existing wafer processing methods result in adhesive layer adherence to device chips, degrading their quality due to the use of adhesive tapes during the division process.
Innovation Solution
A wafer processing method utilizing a polyolefin sheet without an adhesive layer for thermocompression bonding with the wafer and ring frame, allowing for division and chip pickup without adhesive layer adherence, using polyethylene, polypropylene, or polystyrene sheets heated within specific temperature ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If an adhesive tape is used to hold the wafer during laser division, then the wafer can be securely held and processed, but the adhesive layer adheres to the device chips and degrades their quality
Solution Approach 1:
The invention extracts and removes the adhesive layer from the holding structure. Instead of using an adhesive tape that adheres to the wafer and chips, the patent uses a holding structure composed of a base sheet and a pressing sheet that physically holds the wafer through friction and pressure without any adhesive material, thereby preventing adhesive contamination of the device chips
Solution Approach 2:
The invention introduces an intermediary holding mechanism between the wafer and the processing equipment. The base sheet and pressing sheet act as intermediaries that provide the necessary holding function during laser division, while their non-adhesive nature ensures they do not transfer any contaminating material to the device chips
2Ease of operation
If ultraviolet light is applied to reduce adhesive tape adhesion for chip pickup, then chips can be released from the tape, but the melted adhesive layer remains on the chip surfaces and degrades quality
Solution Approach 1:
The invention extracts the adhesive layer entirely from the system, eliminating the need for ultraviolet light treatment to release chips. Without an adhesive layer to melt and contaminate the chip surfaces, the chips can be picked up directly from the holding structure without any quality degradation
3Manufacturing precision
If a polyolefin sheet is used for thermocompression bonding instead of adhesive tape, then adhesive layer adherence is prevented, but additional heating and bonding steps are required
Solution Approach 1:
The invention merges the holding function and the bonding function into a single integrated structure. The base sheet and pressing sheet work together as a unified holding mechanism that secures the wafer during processing, eliminating the need for separate adhesive application and bonding steps that would increase process complexity
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 adhesive layer adherence to device chips, maintaining their quality by using a polyolefin sheet for thermocompression bonding and expanding to facilitate easy chip separation.
Implementation Method 1
a uniting step of 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
a pickup step of cooling the polyolefin sheet in each of the plurality of separate regions corresponding to each device chip, pushing up each device chip through 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 or a front 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 applying a laser beam to the wafer to form modified layers in the wafer, thereby dividing the wafer into individual device chips, and a pickup step of cooling the polyolefin sheet in each of the plurality of separate regions corresponding to each device chip, pushing up each device chip through the polyolefin sheet, then picking up each device chip from the polyolefin sheet.