Grinding Wheel Speed Adjustment for Multi-Layer Device Chips
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Solution Overview
Problem
The existing grinding methods for device chips face challenges in efficiently processing workpieces with varying materials, such as silicon and silicon oxide, leading to reduced productivity and increased apparatus footprint due to the need for high-capability grinding wheels and reduced grinding speeds for harder materials.
Innovation Solution
A method involving two grinding steps with different rotational speeds for silicon and silicon oxide layers, where the silicon oxide layer is ground at a lower speed to accelerate self-sharpening of grindstones, eliminating the need for high-capability wheels and maintaining productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a grinding wheel with a high grinding capability is used to grind a layer containing a hard-to-grind material, then the grinding capability is improved, but the device complexity increases due to the need to replace or add selective grinding wheels
Solution Approach 1:
The patent changes the operational parameters of the grinding wheel by adjusting rotational speed based on the material being ground. When grinding hard-to-grind materials like silicon oxide, the rotational speed is reduced to prevent abrasive grain detachment, while maintaining the same physical grinding wheel structure. This eliminates the need for multiple specialized grinding wheels or complex replacement mechanisms.
2Ease of manufacture
If the rotational speed of the grinding wheel is lowered to grind hard-to-grind materials, then the grinding capability is improved, but the productivity decreases
Solution Approach 1:
The patent implements dynamic adjustment of the grinding wheel's rotational speed according to the material layer being ground. The system automatically or manually adjusts speed during the grinding process - using lower speeds for hard-to-grind materials like silicon oxide to prevent abrasive grain loss, and higher speeds for easier materials like silicon to maintain productivity. This dynamic parameter adjustment resolves the contradiction between grinding capability and production efficiency.
3Ease of manufacture
If a grinding wheel with a high grinding capability is used, then the grinding capability is improved, but the footprint of the grinding apparatus increases
Solution Approach 1:
Instead of adding physical components like multiple specialized grinding wheels or auxiliary positioning mechanisms (which would increase footprint), the patent achieves enhanced grinding capability through parameter changes - specifically adjusting rotational speed. This software/control-based solution maintains high grinding capability for various materials without requiring additional physical space or complex mechanical structures.
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 allows for effective grinding of both silicon and silicon oxide layers without lowering productivity or increasing apparatus size, preventing the need for specialized wheels and maintaining efficient device chip production.
Implementation Method 1
grinding the first layer of the workpiece held on a chuck table with a plurality of grindstones included in a grinding wheel and arranged in an annular array while the grinding wheel is being rotated
Data Source
AI summary
A workpiece to be ground by a grinding wheel of a grinding apparatus has a first layer including a first material and a second layer including a second material that is harder to grind than the first material and stacked on the first layer. The rotational speed of the grinding wheel for grinding the second layer, i.e., a second rotational speed, is lower than the rotational speed of the grinding wheel for grinding the first layer, i.e., a first rotational speed. The second layer can thus be ground effectively, as it is not necessary to use a grinding wheel with a high grinding capability or to lower a rate at which the workpiece is ground. Consequently, it is possible to maintain productivity for device chips manufactured by dividing the workpiece, and also prevent the footprint of the grinding apparatus from increasing.