Semiconductor Wafer Thinning with Rinse-Separation Grinding
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Solution Overview
Problem
Conventional semiconductor wafer thinning processes using grinding result in surface damage such as cracks, gouges, and stress concentration points due to particles and contaminants lodging between the grinding wheel and the wafer, leading to potential wafer failure and reduced production yield.
Innovation Solution
Implementing a grinding phase followed by a separation phase with a rinsing solution to clear particles and contaminants from the grinding wheel and surface, reducing surface damage by lifting the grinding wheel and using rinsing solution to wash away debris, thereby minimizing cracks and gouges in the final post-grinding surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If conventional grinding is used to thin the wafer, then the wafer thickness is reduced, but surface damage such as cracks, gouges, and stress concentration points occur due to particles and contaminants lodging between the grinding wheel and wafer
Solution Approach 1:
The grinding process is segmented into multiple passes with intermediate separation phases. Between grinding passes, the grinding wheel is lifted away from the wafer surface to allow particles and contaminants to be removed from the grinding interface, preventing them from causing damage in subsequent passes
Solution Approach 2:
The grinding operation uses periodic action by alternating between grinding phases and separation phases. During separation phases, the grinding wheel is lifted and rinsing solution is applied to clear debris, creating a cyclical pattern that maintains surface quality while achieving the required thickness reduction
2Productivity
If grinding wheel operates continuously to reduce wafer thickness, then productivity is improved, but particles and contaminants become lodged between grinding wheel and wafer causing surface damage
Solution Approach 1:
The process uses periodic grinding phases followed by separation phases where the wheel is lifted and rinsing solution is applied. This periodic interruption maintains reliability by clearing contaminants while preserving overall productivity through efficient cycling between grinding and cleaning operations
Solution Approach 2:
A rinsing solution is introduced as an intermediary substance during the separation phase to wash away particles and contaminants from the grinding interface, preventing them from causing surface damage while allowing the grinding process to continue efficiently
3Reliability
If brittle conductive vias are ground through base substrate material, then electrical interconnect is achieved, but vias break apart and become lodged causing cracks and gouges in final surface
Solution Approach 1:
The grinding process is divided into multiple passes rather than removing all base substrate material in one pass. This segmentation allows conductive vias to be ground through gradually, reducing the risk of brittle fracture and via breakage while maintaining electrical interconnect functionality
Solution Approach 2:
The separation phase with rinsing solution acts as a protective measure by removing particles and contaminants before they can cause damage to the final surface, cushioning against potential surface defects that would result from via fragmentation
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
The method effectively reduces surface damage and stress concentration points, enhancing the quality of the semiconductor wafer and increasing production yield by maintaining a cleaner grinding surface and preventing brittle conductive vias from breaking during the grinding process.
Implementation Method 1
a rinsing solution to clear particles and contaminants from the grinding wheel and surface
Data Source
AI summary
A semiconductor wafer has a base material. The semiconductor wafer may have an edge support ring. A grinding phase of a surface of the semiconductor wafer removes a portion of the base material. The grinder is removed from or lifted off the surface of the semiconductor wafer during a separation phase. The surface of the semiconductor wafer and under the grinder is rinsed during the grinding phase and separation phase to remove particles. A rinsing solution is dispensed from a rinsing solution source to rinse the surface of the semiconductor wafer. The rinsing solution source can move in position while dispensing the rinsing solution to rinse the surface of the semiconductor wafer. The grinding phase and separation phase are repeated during the entire grinding operation, when grinding conductive TSVs, or during the final grinding stages, until the final thickness of the semiconductor wafer is achieved.