Wafer Edge Cutting and Back Grinding for Damage Reduction
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Solution Overview
Problem
The back-grinding process for semiconductor wafers can cause damage and contamination due to the exposure of adhesive during subsequent processes, and existing methods of edge removal before attachment to a carrier wafer do not effectively minimize these issues.
Innovation Solution
A wafer processing method where the edges of a device wafer and adhesive are cut at a predetermined angle after attachment to a carrier wafer, followed by grinding to reduce the wafer thickness, minimizing damage and contamination by maintaining a small adhesive exposure and using a carrier wafer with sufficient mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If edge removal is performed before attaching the device wafer to the carrier wafer, then adhesive exposure is reduced, but the device wafer is more susceptible to damage during grinding and subsequent processes
Solution Approach 1:
The edges of the device wafer are removed before attachment to the carrier wafer, preparing the wafer in advance for the bonding process. This preliminary edge removal reduces adhesive exposure during subsequent processes while the wafer is still supported by the carrier, minimizing damage risk.
Solution Approach 2:
The carrier wafer serves as an intermediary support structure that holds the device wafer during grinding and subsequent processes. This intermediary provides mechanical support to the device wafer, preventing damage even after edge removal, and can be easily separated later.
2Length of moving object
If the device wafer is ground to reduce thickness, then the wafer becomes thinner and more flexible, but the wafer becomes more prone to damage and harder to handle
Solution Approach 1:
The carrier wafer acts as a mediator that provides mechanical support to the thinned device wafer during and after the grinding process. This allows the device wafer to achieve the desired thinness while the carrier wafer compensates for the loss of structural integrity.
Solution Approach 2:
The device wafer is attached to the carrier wafer before the grinding process begins, providing beforehand cushioning and support. This prevents damage during the thickness reduction process and maintains handleability throughout subsequent manufacturing steps.
3Strength
If adhesive is applied between the device wafer and carrier wafer, then the device wafer is supported during processing, but adhesive exposure causes contamination during subsequent processes
Solution Approach 1:
The wafer structure is segmented into three distinct parts: the device wafer, the carrier wafer, and the adhesive layer between them. This segmentation allows the adhesive to be confined to the interface between wafers, reducing exposure and contamination risk while maintaining the necessary bonding strength.
Solution Approach 2:
The adhesive is extracted and confined to the specific interface region between the device wafer and carrier wafer, rather than being exposed across the entire wafer surface. This extraction of adhesive to a localized area minimizes contamination during subsequent processing steps.
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 reduces damage to the device wafer during grinding and subsequent processes, minimizes contamination from the adhesive, and allows for easier handling of the thin wafer post-processing by maintaining a strong adhesive support.
Implementation Method 1
attaching a device wafer to a carrier wafer using an adhesive
Implementation Method 2
cutting respective edges of the device wafer and the adhesive at a predetermined angle with respect to a back surface of the device wafer
Implementation Method 3
grinding the back surface of the device wafer
Data Source
AI summary
Wafer processing methods are provided. The methods may include cutting respective edges of a wafer and an adhesive a predetermined angle before grinding a back surface of the wafer.