Wafer Thinning via Laser Bond Break and Substrate Peel
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Solution Overview
Problem
Existing methods for thinning device chips from wafers, such as dicing before grinding (DBG), face limitations in reducing chip size and thickness due to scattering and breaking issues during grinding.
Innovation Solution
A method involving integrating a supporting substrate with the wafer, reverse-side grinding, cutting along division lines, placing a protective member, breaking the bonding material with a laser, and peeling off the substrate to separate chips, allowing for thinner configurations without scattering or breaking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the wafer is ground to reduce thickness to 10 μm or less, then the device chips become thinner, but the device chips scatter off from the protective member or break due to vibrations and load variations
Solution Approach 1:
The supporting substrate is bonded to the face side of the wafer before the reverse-side grinding process. This preliminary action provides mechanical support and stability to the device chips during grinding, preventing them from scattering or breaking even when ground to thickness of 10 μm or less.
Solution Approach 2:
The supporting substrate acts as an intermediary between the grinding wheel and the device chips. It absorbs and distributes the vibrations and load variations from the grinding wheel, protecting the device chips from direct mechanical stress that would cause scattering or breaking.
2Area of moving object
If the device chips are made as small as 1 mm on each side, then the mobile phones or wrist watches become smaller, but the device chips are more prone to scattering and breaking during grinding
Solution Approach 1:
The supporting substrate is bonded to the wafer before dicing and grinding processes. This preliminary support structure enables the safe production of small device chips (1 mm on each side) by preventing them from scattering or breaking during subsequent processing steps.
Solution Approach 2:
The supporting substrate provides beforehand cushioning for small device chips during the grinding process. It absorbs mechanical shocks and vibrations, creating a protective environment that allows small chips to be processed without scattering or breaking.
3Length of moving object
If grooves are formed deeper than the thickness of completed device chips in DBG technology, then the wafer can be thinned, but the device chips may still scatter or break due to grinding vibrations
Solution Approach 1:
The supporting substrate is bonded to the wafer face side before the reverse-side grinding process, enabling the wafer to be ground to the finished thickness of device chips with high precision while maintaining chip integrity through the supportive bonding structure.
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
Enables the production of smaller and thinner device chips by stabilizing the wafer during grinding and separation, overcoming limitations of conventional methods.
Implementation Method 1
applying a laser beam having a wavelength which is able to transmit the supporting substrate in the condition where a focused spot of the laser beam is set in the bonding material, thereby breaking the bonding material
Implementation Method 2
the reverse side of the wafer is ground and polished to the thickness of the completed device chips
Data Source
AI summary
A method of processing a wafer includes placing a supporting substrate in confronting relation to a face side of the wafer and integrally bonding the supporting substrate to the face side of the wafer with a bonding material, grinding a reverse side of the wafer to thin the wafer, cutting the wafer along division lines from the reverse side of the wafer into chips that carry individual devices thereon, placing a protective member on the reverse side of the wafer, applying a laser beam having a wavelength which is able to transmit the supporting substrate in the condition where a focused spot of the laser beam is set in the bonding material, thereby breaking the bonding material, and peeling the supporting substrate off from the devices to separate the chips that carry the individual devices thereon.