Wafer Protective Sheet Lamination for Uniform Resin Wetting
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Solution Overview
Problem
The existing methods for protecting wafers during grinding often result in poor surface accuracy due to inadequate wettability of the liquid resin on the base film, leading to unfilled regions and adhesion issues with the chuck table, which complicates the peeling process.
Innovation Solution
A method involving a first protective sheet with a non-adhesive portion over the device region and an adhesive portion around the outer circumferential region, combined with a second protective sheet having surface irregularities, where a liquid resin is dropped and cured using an external stimulus to ensure even coverage and easy removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a liquid resin is dropped onto a base film with poor wettability, then the liquid resin cannot spread evenly, but this leaves unfilled regions that reduce surface accuracy
Solution Approach 1:
The invention changes the surface parameter of the base film by forming a roughness layer with controlled surface roughness (Ra 0.03 to 3 μm). This parameter change improves wettability of the liquid resin, enabling even spreading across the base film surface and eliminating unfilled regions, thereby resolving the contradiction between surface accuracy and wettability
Solution Approach 2:
The roughness layer creates a porous or micro-structured surface on the base film that enhances capillary action and liquid resin penetration. This porous structure increases the effective contact area between liquid resin and base film, improving wetting behavior and ensuring complete coverage without reducing surface accuracy
2Ease of manufacture
If a base film is used without surface treatment, then the structure is simple, but the liquid resin does not spread properly causing unfilled regions
Solution Approach 1:
Instead of complex surface treatments, the invention applies a simple roughness layer formation process that changes only the surface roughness parameter of the base film. This minimal intervention maintains manufacturing simplicity while effectively improving liquid resin spreading and surface accuracy
3Reliability
If the base film has high adhesion to the chuck table, then the wafer is securely held, but peeling the base film becomes time-consuming
Solution Approach 1:
The invention applies local quality by creating a roughness layer only on the surface of the base film that contacts the liquid resin, while maintaining appropriate adhesion properties at the chuck table interface. This localized modification allows secure holding during processing while enabling easy peeling afterward, resolving the contradiction between holding stability and peeling time
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
This approach enhances the surface accuracy of the wafer's reverse side during grinding by preventing resin-filled regions and simplifying the peeling process, thereby improving the grinding process efficiency and productivity.
Implementation Method 1
dropping a liquid resin that can be cured by an external stimulus onto a surface of the second protective sheet
Data Source
AI summary
A method of laying a protective sheet on a face side of a wafer includes preparing a first protective sheet having, on one surface thereof, a non-adhesive portion to be coextensive with a device region of the wafer and an adhesive portion to be positioned along an outer circumferential excessive region of the wafer, affixing the one surface of the first protective sheet to the face side of the wafer, dropping a liquid resin onto a surface of a second protective sheet that has surface irregularities ranging from Ra 0.2 to 7 μm and is free of an adhesive layer, bringing another surface of the first protective sheet into facing relation to the surface of the second protective sheet onto which the liquid resin has been dropped, and curing the liquid resin.