Semiconductor Wafer Thinning via Support Surface Planarization
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Solution Overview
Problem
The variation in film thickness of the support wafer during the thinning process of semiconductor devices affects the properties of the semiconductor device, and existing methods do not effectively mitigate this variation, leading to inconsistent film thickness in the device wafer.
Innovation Solution
The method involves grinding the surface of the support wafer prior to the thinning step of the device wafer, using infeed grinding with a grinder and chuck table rotation to planarize the support wafer, which serves as a reference surface for even thinning of the device wafer, thereby reducing the impact of film thickness variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the device wafer is thinned while bonded to the support wafer without pre-grinding the support wafer, then the thinning process is simpler, but the film thickness variation of the device wafer increases due to support wafer irregularities
Solution Approach 1:
The support wafer surface is ground before bonding to the device wafer. This preliminary action removes irregularities and creates a flat reference surface, ensuring that subsequent thinning of the device wafer produces uniform film thickness without being affected by support wafer variations.
2Manufacturing precision
If chemical mechanical polishing is used to thin the device wafer, then film thickness uniformity can be maintained, but the processing time increases
Solution Approach 1:
The patent replaces chemical mechanical polishing with a mechanical grinding process. By grinding the support wafer surface before bonding, the method achieves uniform film thickness through mechanical removal of material, which is faster than chemical mechanical polishing while maintaining precision.
3Manufacturing precision
If the support wafer surface is ground before bonding, then the film thickness variation of the device wafer is reduced, but the process complexity increases
Solution Approach 1:
The support wafer is ground in advance before bonding to the device wafer. This preliminary preparation creates a flat reference surface that eliminates the need for complex real-time compensation mechanisms during thinning, actually simplifying the overall control complexity despite adding one process step.
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 results in a 50% improvement in the variation of the device wafer's film thickness, allowing for more precise and efficient thinning, compared to methods without surface grinding, and reduces the time required for thinning compared to chemical mechanical polishing.
Implementation Method 1
grinding the surface of the support wafer prior to the thinning step of the device wafer
Data Source
AI summary
According to one embodiment, a method of manufacturing a semiconductor device includes a step of grinding to thin a first semiconductor wafer on which a semiconductor device is formed in a state in which a surface of a second semiconductor wafer is fixed on a chuck table of a grinding device after bonding the first semiconductor wafer to the second semiconductor wafer. The method includes a step of fixing a surface of the first semiconductor wafer on the chuck table and grinding the surface of the second semiconductor wafer in a state in which the first semiconductor wafer is bonded to the second semiconductor wafer prior to the grinding step to thin the first semiconductor wafer.