Double-Side Polishing Apparatus Inter-Plate Distance Control
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Solution Overview
Problem
Achieving high accuracy in the flatness of semiconductor wafers during double-side polishing is challenging due to variations in inter-plate distance, which affect the surface roughness and quality of the wafers.
Innovation Solution
A double-side polishing method and apparatus that utilize a rotating plate with a sun gear and internal gear, where relational data is obtained to calculate the optimum inter-plate distance at different radial positions, and the shape of the rotating plate is controlled to maintain this distance for precise flatness, using mechanical or thermal deformation to adjust the inter-plate distance based on calculated values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the inter-plate distance is kept uniform across the rotating plate, then the manufacturing process is simple, but the flatness of the work cannot be obtained with high accuracy due to variations in polishing pressure
Solution Approach 1:
The rotating plate is designed with non-uniform thickness distribution, where the thickness varies according to the radial position from the center. This local variation in plate geometry compensates for the non-uniform polishing pressure that would otherwise occur, ensuring that each region of the work receives appropriate polishing pressure to achieve high flatness accuracy.
Solution Approach 2:
The invention changes the geometric parameter of the rotating plate (thickness distribution) from uniform to non-uniform. By carefully designing the thickness profile, the system transforms the inherent non-uniformity in polishing contact into a controlled parameter that achieves uniform polishing pressure and high flatness across the work surface.
2Manufacturing precision
If the rotating plate shape is controlled to optimize inter-plate distance, then the flatness accuracy is improved, but the device complexity increases
Solution Approach 1:
The optimal thickness distribution of the rotating plate is calculated in advance based on the desired flatness specifications and polishing characteristics. This pre-calculated geometry is then incorporated into the plate manufacturing process, eliminating the need for complex real-time adjustments during operation and simplifying the actual manufacturing process.
3Measurement precision
If relational data is obtained and calculation is performed to determine optimum inter-plate distance, then the flatness measurement accuracy is improved, but the measurement and control process becomes more complex
Solution Approach 1:
Relational data between inter-plate distance and flatness measurement results is obtained in advance through experiments or simulations. This pre-acquired data is stored and used during actual polishing operations to quickly determine the optimal inter-plate distance without requiring complex real-time calculations, thereby improving measurement accuracy while keeping the control system relatively simple.
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 high-accuracy attainment of desired flatness in semiconductor wafers by optimizing the inter-plate distance, resulting in improved surface quality and reduced variations in flatness measurements.
Implementation Method 1
simultaneously polishing both sides of the work by rotating the rotating plate and the carrier plate relative to each other through the rotation of a sun gear provided at the center of the rotating plate and the rotation of an internal gear provided at the periphery of the rotating plate
Implementation Method 2
controlling the shape of the rotating plate to control the inter-plate distance to the optimum value
Data Source
AI summary
Based on the relational data that indicates the relationship between inter-plate distance, which is a distance between the upper plate and the lower plate at two or more positions where distances from the center of the rotating plate are different, and the flatness of the work, the optimal value of the inter-plate distance is calculated.