Wafer Bonding with Void Features for Recyclable Support
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Solution Overview
Problem
The challenge is to minimize material consumption and efficiently attach and detach wafers from supporting substrates during device fabrication, while ensuring mechanical stability and preventing damage or delamination, especially as wafer sizes increase and silicon material costs rise.
Innovation Solution
A method involving a wafer and a supporting substrate with void features, such as holes or depressions, to form a bond that is strong enough for device processing but weak enough to be severed, using loosening agents and pressure differentials to separate the wafer from the substrate, allowing for reuse of the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the wafer thickness is increased for mechanical stability, then the mechanical stability is improved, but the silicon material consumption increases
Solution Approach 1:
The wafer system is segmented into two functional parts: a thin semiconductor wafer (containing the actual device structures) and a separate supporting substrate (providing mechanical strength). This segmentation allows each component to be optimized independently - the wafer can be thin to conserve silicon while the substrate provides the necessary mechanical stability for handling and processing.
2Loss of substance
If the wafer is mechanically ground to reduce thickness, then the silicon material consumption is reduced, but the manufacturing complexity and material loss increase
Solution Approach 1:
Instead of grinding the wafer backside to reduce thickness, the thin wafer is bonded to a supporting substrate in advance. This preliminary bonding action provides the mechanical strength needed for subsequent processing steps, eliminating the need for time-consuming and material-intensive grinding operations while reducing overall manufacturing complexity.
3Ease of operation
If the bond between wafer and substrate is made weaker for easy separation, then the ease of separation is improved, but the reliability of the bond during processing deteriorates
Solution Approach 1:
The bond interface is designed with local quality variations through void features (holes or depressions) distributed at specific locations. These localized voids create predetermined weak points that facilitate separation, while the surrounding areas maintain strong bonding to ensure reliability during processing. This local modification allows the bond to be both strong enough for processing and separable when needed.
4Ease of operation
If the surface is etched to create roughness for weaker bonding, then the ease of separation is improved, but the risk of delamination during processing increases
Solution Approach 1:
Instead of uniformly etching the surface to create roughness, the bonding interface is segmented with discrete void features (holes or depressions) at specific locations. This segmentation allows separation to occur at these localized void points without compromising the integrity of the overall bond interface, thereby reducing delamination risk while still enabling easy separation.
Data Source
AI summary
A method for forming a device wafer with a recyclable support by providing a wafer having first and second surfaces, with at least the first surface of the wafer comprising a semiconductor material that is suitable for receiving or forming electronic devices thereon, providing a supporting substrate having upper and lower surfaces, and providing the second surface of the wafer or the upper surface of the supporting substrate with void features in an amount sufficient to enable a connecting bond therebetween to form a construct wherein the bond is formed at an interface between the wafer and the substrate and is suitable to maintain the wafer and supporting substrate in association while forming or applying electronic devices to the first surface of the wafer, but which connecting bond is severable at the interface due to the void features to separate the substrate from the wafer so that the substrate can be reused.