Wafer Grinding for Rigidity via Recessed Center and Reinforcing Ring
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Solution Overview
Problem
Existing wafer grinding methods, such as TAIKO grinding, often result in insufficient rigidity of thinned wafers, leading to deformation issues like warpage or bending, especially in large-diameter wafers, and require the use of support substrates to mitigate these problems.
Innovation Solution
A grinding method that forms a circular recessed part in the central region of the wafer and a ring-shaped reinforcing part on the outer circumference using a grinding wheel, ensuring the ring-shaped reinforcing part maintains the original thickness to suppress deformation without the need for a support substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If TAIKO grinding is performed to thin the wafer, then the wafer thickness is reduced, but the rigidity of the wafer decreases
Solution Approach 1:
The invention applies local quality by creating a ring-shaped reinforcing part with original thickness at the outer circumference while the central region is thinned to form a circular recessed part. This localized structural differentiation provides rigidity enhancement where needed (outer circumference) while achieving thickness reduction where required (central region), resolving the contradiction between overall thinning and rigidity maintenance.
2Length of moving object
If the wafer is thinned to reduce size, then the wafer dimensions are reduced, but deformation such as warpage or bending occurs
Solution Approach 1:
The invention applies preliminary anti-action by pre-forming the ring-shaped reinforcing part with original thickness at the outer circumference before subsequent processing steps. This preliminary structural reinforcement counteracts the thinning effect in the central region and prevents deformation such as warpage or bending that would otherwise occur during handling and post-processing, thereby stabilizing the thinned wafer structure.
3Strength
If a support substrate is stuck to the wafer to maintain rigidity, then the rigidity is improved, but the process complexity and work required increases
Solution Approach 1:
The invention applies self-service by forming the ring-shaped reinforcing part directly as an integral component of the wafer structure through the grinding process itself. This self-contained structural solution provides the necessary rigidity without requiring external support substrates or additional complex assembly steps, thereby eliminating the need for separate support substrate handling and adhesion processes.
4Length of moving object
If the central region is ground to form a circular recessed part, then the wafer thickness is reduced centrally, but the rigidity of the thinned region decreases
Solution Approach 1:
The invention applies the counterweight principle by creating a ring-shaped reinforcing part with original thickness at the outer circumference that acts as a structural counterbalance to the thinned central region. This outer reinforcing structure compensates for the reduced rigidity in the central area, providing overall structural stability while maintaining the desired central thickness reduction for device mounting or other applications.
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 provides high rigidity to the wafer post-grinding, effectively reducing deformation and preventing errors like warpage and breakage, especially in large-diameter wafers, without the necessity of sticking a support substrate, thus enhancing handling and processing reliability.
Implementation Method 1
a grinding step of grinding, by a grinding wheel, a central region of the wafer held by a holding table, to form a circular recessed part and form a ring-shaped reinforcing part on an outer circumferential side of the circular recessed part
Data Source
AI summary
A method of grinding a wafer includes a grinding step of grinding, by a grinding wheel, a central region of a wafer held by a holding table, to form a circular recessed part and form a ring-shaped reinforcing part 18 on the outer circumferential side of the circular recessed part. The wafer has such a thickness that the deformation of the wafer in which the circular recessed part 17 is formed is able to be suppressed by the ring-shaped reinforcing part.