Protective Resin Layer for Warped Workpiece Grinding
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Solution Overview
Problem
Existing methods for flattening semiconductor workpieces with warping and undulations, and protecting surfaces with projections and depressions, often result in residue contamination, poor suction, and cracking during back grinding, especially when using ultraviolet curable resins or soft films.
Innovation Solution
A method involving coating the workpiece surface with a water-soluble resin, applying a liquid resin that cures with an external stimulus, and forming a protective layer without a soft film, followed by grinding and peeling off the cured resin using a water-soluble adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick adhesive layer is used to accommodate projections and depressions on the workpiece surface, then the surface can be protected adequately, but adhesive residue remains on projections and depressions when the protective member is peeled off, leading to defects in device chips
Solution Approach 1:
The patent changes the material parameter of the adhesive layer from a conventional non-water-soluble adhesive to a water-soluble resin. This parameter change enables the adhesive residue to be dissolved and removed by water during the rinsing step, eliminating the harmful adhesive residue while maintaining adequate protection during grinding. The water-soluble property allows complete removal without leaving defects on the device chip surface.
Solution Approach 2:
The protective member is designed as a temporary protective structure that is discarded after serving its protective function. The water-soluble adhesive layer is intentionally made removable through water rinsing, allowing the protective member to be easily discarded without leaving harmful residues. This aligns with the principle of using temporary structures that can be cleanly removed after completing their protective role.
2Reliability
If ultraviolet curable resin is used to protect the workpiece surface, then protection is provided, but the resin may remain on the surface during peeling, causing poor suction and fixation during back grinding, workpiece cracking, and apparatus contamination
Solution Approach 1:
The patent fundamentally changes the chemical parameter of the adhesive material from ultraviolet curable resin to water-soluble resin. This parameter change transforms the removal mechanism from mechanical peeling (which leaves residue) to chemical dissolution in water (which completely removes residue). The water-soluble property ensures no residue remains on the workpiece surface or in the apparatus, eliminating suction problems, cracking, and contamination.
Solution Approach 2:
The patent replaces the mechanical removal method (peeling) with a chemical removal method (water dissolution). Instead of mechanically peeling off the protective member which leaves residue, the water-soluble adhesive is chemically dissolved by water rinsing, achieving complete removal without mechanical stress that could cause cracking or residue that could contaminate the apparatus.
3Shape
If a soft resin film is used to conform to projections and depressions, then close contact with the front surface is achieved, but heating and stretching steps are required to bring the film into close contact, increasing process complexity
Solution Approach 1:
The patent changes the material parameter of the protective layer from a soft resin film requiring thermal and mechanical activation to a water-soluble resin that can be directly applied in liquid form. The water-soluble resin can be coated as a liquid that naturally conforms to the surface topology, eliminating the need for heating and stretching steps. The liquid state allows easy surface conformity, and the water-soluble property enables easy removal.
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
Eliminates warping and undulations, protects surfaces with projections and depressions, and prevents residue contamination by using a water-soluble resin that can be easily removed, ensuring uniform grinding and apparatus cleanliness.
Implementation Method 1
coating the front surface of the workpiece with a water-soluble resin
Implementation Method 2
a liquid resin that cures in response to an external stimulus
Data Source
AI summary
A new technique for removing warping and undulations in the shape of a workpiece, and a new technique for protecting a surface of a workpiece having projections and depressions without using a soft film are proposed. A protective layer forming method includes the steps of: coating a front surface of a workpiece with a water-soluble resin; pressing a liquid resin that cures in response to an external stimulus with a surface of the water-soluble resin coating the front surface of the workpiece and a resin film; and applying an external stimulus to the pressed liquid resin to cure the liquid resin.