Semiconductor Wafer Thinning With Periodic Grind-Rinse Separation
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Solution Overview
Problem
The existing methods for thinning semiconductor wafers using grinding phases result in significant surface damage, including cracks, gouges, and other defects, which can lead to wafer failure and reduced production yield.
Innovation Solution
A method involving a grinding phase followed by a separation phase, where the grinding wheel lifts off the surface and rinsing solution is used to clear particles and contaminants, reducing surface damage and improving the final surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a grinding wheel operates on a constant feed rate to remove base substrate material, then the thickness of the semiconductor wafer is reduced, but particles and contaminants become lodged between the grinding wheel and base substrate material causing surface cracks, gouges, and other damage
Solution Approach 1:
The grinding wheel alternates between a grinding phase (where material is removed) and a separation phase (where the wheel lifts off the surface). This periodic action allows particles and contaminants to be cleared from between the wheel and workpiece during the separation phase, preventing surface damage while maintaining efficient material removal during the grinding phase.
Solution Approach 2:
The harmful interaction between the grinding wheel and contaminants is separated into distinct phases. During the separation phase, the grinding wheel is extracted from contact with the base substrate material, allowing particles and contaminants to be removed from the grinding zone without causing surface damage.
2Manufacturing precision
If the grinding wheel removes particles and contaminants during the grinding phase, then surface damage is reduced, but the grinding process becomes more complex with multiple phases
Solution Approach 1:
The grinding process uses periodic alternation between grinding and separation phases, controlled by oscillating the grinding wheel or the workpiece. This periodic action integrates particle removal into the existing grinding cycle without requiring separate equipment or complex additional processes.
Solution Approach 2:
The particle removal function is merged with the grinding process by combining the separation phase into the same grinding cycle. The oscillation mechanism that creates the separation phase is integrated into the grinding wheel drive system, eliminating the need for separate particle removal equipment.
3Productivity
If tungsten conductive vias are ground through with a constant feed rate, then the desired thickness is achieved, but the brittle via material breaks apart and becomes lodged between the grinding wheel and grinding surface
Solution Approach 1:
The periodic grinding and separation phases allow brittle via material to be removed in controlled amounts during the grinding phase, then cleared from the grinding zone during the separation phase before it can accumulate and cause surface damage or via breakage.
Solution Approach 2:
The separation phase acts as an intermediary between material removal and surface contact. During this phase, the grinding wheel is separated from the workpiece, allowing via material particles to be cleared from the interface without directly contacting and damaging the grinding surface or causing via breakage.
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 effectively minimizes surface damage, enhances the quality of the final surface, and reduces the likelihood of wafer failure, thereby improving production yield and semiconductor device reliability.
Implementation Method 1
Grinding wheel 20 removing a portion of base substrate material 12 from back surface 16 of semiconductor wafer 10
Implementation Method 2
rinsing solution is used to clear particles and contaminants
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.