Wafer Back Side Grinding Using Bonded Carrier Assembly
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Solution Overview
Problem
Conventional wafer back side grinding processes have low throughput and high production costs due to the need for a silicon or glass carrier, which limits efficiency and increases expenses.
Innovation Solution
A wafer back side grinding process using a workpiece assembly with bonded semiconductor wafers and hot melt adhesive layers, where one wafer acts as a carrier for grinding the other, eliminating the need for a conventional carrier and allowing for efficient grinding and subsequent separation of wafers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional silicon or glass carrier is used to support the wafer during grinding, then the wafer can be properly supported and ground, but the production cost increases and throughput decreases
Solution Approach 1:
The patent merges two wafers into a single workpiece assembly where the first wafer is bonded to the second wafer using a release adhesive. This combination allows the second wafer to serve as a support carrier for the first wafer during grinding, eliminating the need for separate silicon or glass carriers. The merged structure maintains mechanical stability while enabling high-throughput processing since multiple wafers can be processed simultaneously in the same assembly.
Solution Approach 2:
The second wafer in the assembly serves multiple functions: it acts as the workpiece to be ground, simultaneously serves as a support carrier for the first wafer during grinding, and provides mechanical stability throughout the process. This multi-functionality eliminates the need for dedicated carrier components, reducing cost and improving throughput.
2Reliability
If a conventional silicon or glass carrier is used to support the wafer during grinding, then the wafer can be properly supported and ground, but the production expense increases
Solution Approach 1:
The second wafer serves itself by acting as both the workpiece and the support carrier. Instead of requiring an external silicon or glass carrier, the wafer assembly is self-supporting, with the second wafer providing the necessary mechanical stability for grinding the first wafer. This self-service approach eliminates the need for expensive carrier materials.
Solution Approach 2:
The release adhesive layer acts as a temporary, inexpensive component that enables the wafer assembly to function during processing. This cheap adhesive layer can be easily removed after grinding, leaving no permanent expensive carrier attached to the wafer. The temporary nature of this component allows for cost-effective processing.
3Productivity
If one wafer is used as a carrier for grinding the other, then the need for expensive carriers is eliminated and throughput increases, but a bonding mechanism is required to hold the wafers together
Solution Approach 1:
The release adhesive layer changes its bonding parameters based on temperature and time conditions. During assembly, the adhesive is applied in a state where it bonds effectively to both wafers. During grinding, the adhesive maintains sufficient bond strength to hold the wafers together. After grinding, the adhesive can be easily removed by heating or other methods, allowing the wafers to be separated. This parameter change enables simple assembly and disassembly without complex bonding mechanisms.
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 production efficiency and reduces costs by enabling high-throughput wafer processing without the need for expensive carriers, while maintaining mechanical support for thinned wafers.
Implementation Method 1
the first and second assemblies are bonded together with at least one hot melt adhesive layer
Implementation Method 2
grinding a first back side of the first semiconductor wafer by using the second assembly as a carrier
Data Source
AI summary
A wafer back side grinding process. A workpiece comprising a first assembly having a first semiconductor wafer and a second assembly having a second semiconductor wafer is provided. A first back side of the first semiconductor wafer is grinded by using the second assembly as a carrier. Thereafter, a second back side of the second semiconductor wafer is grinded.