Wafer Protection Using Ice Layer Fixation
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Solution Overview
Problem
Existing methods for forming protective members on semiconductor wafers often introduce internal stress and alter the wafer's natural shape due to the viscosity of liquid resins, which can lead to variations in thickness and surface undulation.
Innovation Solution
A method involving a water film on a support base to fix the wafer, followed by forming an ice layer, applying and curing a liquid resin on the wafer's surface, and then separating the wafer from the ice layer, ensuring the wafer's natural shape is maintained during the process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If liquid resin is applied to the wafer surface and pressed to spread evenly, then a uniform protective member is formed, but internal stress is introduced that changes the wafer's natural shape
Solution Approach 1:
The wafer is fixed to the support base before applying the liquid resin. This preliminary fixation prevents the wafer from deforming under the pressure applied during resin spreading, allowing the protective member to be formed uniformly without altering the wafer's natural shape.
Solution Approach 2:
The support base acts as an intermediary between the wafer and the pressing force. By fixing the wafer to the support base, the pressing force is distributed evenly, preventing localized stress that would deform the wafer while still ensuring uniform resin spreading.
2Quantity of substance
If pressure is applied to spread liquid resin on the wafer surface, then complete coverage is achieved, but the wafer's initial shape is altered due to internal stress
Solution Approach 1:
The wafer is fixed to the support base before resin application. This preliminary action ensures the wafer maintains its shape stability throughout the resin spreading process, allowing complete coverage to be achieved without compromising shape stability.
3Reliability
If the wafer is fixed using viscous liquid resin, then the protective member is formed, but internal stress remains that may alter the wafer shape
Solution Approach 1:
The wafer is fixed to the support base before resin application, eliminating the need for viscous resin fixation. This preliminary fixation provides reliable wafer positioning without introducing the internal stress that would occur if viscous resin were used for fixation.
Solution Approach 2:
The fixation function is extracted from the liquid resin and performed by the support base instead. This separation of functions allows the resin to focus solely on forming the protective member without the side effect of introducing internal stress through fixation.
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 method effectively forms a protective member on the wafer while preserving its natural shape, allowing for uniform thickness and flat surfaces without external stress-induced distortions.
Implementation Method 1
freezing the water film in the condition where the wafer floats on the upper surface of the water film owing to surface tension of the water film
Implementation Method 2
freezing the water film in the condition where the wafer floats on the upper surface of the water film
Implementation Method 3
applying the external stimulus to the liquid resin after performing the liquid resin pressing step, thereby curing the liquid resin to form a protective member
Implementation Method 4
heating the ice layer to thereby melt the ice layer and next separate the wafer from the ice layer
Data Source
AI summary
A protective member forming method includes forming a water film on a flat holding surface of a support base, placing a wafer on the water film formed on the holding surface and next freezing the water film in a condition where the wafer floats on an upper surface of the water film owing to the surface tension of the water film, thereby forming an ice layer and fixing the wafer on the ice layer, supplying a liquid resin curable by the application of ultraviolet light to the upper surface of the wafer, opposing a transparent sheet to the wafer with the liquid resin interposed therebetween, and applying ultraviolet light to the liquid resin, thereby curing the liquid resin to form a protective member on a whole of the upper surface of the wafer.