Hybrid Polishing Rate Profile for CMP Pressure Control
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Solution Overview
Problem
The existing chemical mechanical polishing (CMP) process faces challenges in accurately determining the responsiveness of the polishing rate to pressure changes in the pressure chamber, due to varying pressing pressures caused by temperature, polishing pad, and liquid factors, which affects the ability to achieve a target film thickness profile.
Innovation Solution
A method and apparatus that create a hybrid polishing-rate responsiveness profile by combining estimated and actual polishing-rate responsiveness profiles, using simulation and actual polishing results to account for pressure changes in multiple pressure chambers, allowing for precise control of pressing pressures and optimizing the CMP process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pressing pressure is increased to improve polishing rate, then polishing efficiency increases, but pressure distribution becomes non-uniform due to temperature, polishing pad, and liquid factors
Solution Approach 1:
The polishing head is divided into multiple pressure chambers (first pressure chamber and second pressure chamber) that can independently control pressure in different regions of the workpiece. This segmentation allows differential pressure control to compensate for non-uniform pressure distribution caused by temperature gradients, polishing pad variations, and liquid flow differences across the polishing surface.
Solution Approach 2:
Each pressure chamber is configured to apply locally optimized pressure to specific regions of the workpiece based on local requirements. The first pressure chamber targets regions requiring higher pressure while the second pressure chamber addresses regions needing lower pressure, creating non-uniform but controlled pressure distribution that maintains polishing rate uniformity across the workpiece surface.
2Loss of time
If simulation is used to estimate polishing-rate responsiveness, then computational efficiency improves, but accuracy decreases due to inability to capture actual process variations
Solution Approach 1:
The system merges simulation-based estimated polishing-rate responsiveness profile with actual polishing results to create a hybrid profile. The simulation provides initial estimates that reduce computational time, while actual polishing data compensates for simulation inaccuracies, resulting in a combined profile that achieves both efficiency and accuracy.
Solution Approach 2:
Actual polishing results are fed back into the profile creation process to correct and refine the simulation-based estimates. This feedback mechanism allows the system to learn from real process variations and improve the accuracy of polishing-rate responsiveness predictions while maintaining the efficiency benefits of simulation.
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 enables accurate determination of polishing rate responsiveness to pressure changes, ensuring consistent and targeted film thickness profiles, thereby improving the efficiency and precision of the CMP process.
Implementation Method 1
A compressed gas is supplied into the pressure chamber, and the pressure of the gas is applied to the workpiece through the elastic membrane
Implementation Method 2
The surface of the workpiece is polished by a chemical action of the polishing liquid and mechanical actions of the polishing pad and abrasive grains
Implementation Method 3
The surface of the workpiece is polished by a chemical action of the polishing liquid and mechanical actions of the polishing pad and abrasive grains
Data Source
AI summary
A method capable of accurately obtaining polishing-rate responsiveness to a change in pressure for pressing a workpiece, such as a wafer, against a polishing pad is disclosed. The method includes: creating an estimated polishing-rate responsiveness profile using simulation, the estimated polishing-rate responsiveness profile indicating a distribution of polishing-rate responsiveness to pressure change in the first pressure chamber; creating an actual polishing-rate responsiveness profile using polishing results of a workpiece, the actual polishing-rate responsiveness profile indicating a distribution of polishing-rate responsiveness to pressure change in the second pressure chamber, and creating a hybrid polishing-rate responsiveness profile by combining the estimated polishing-rate responsiveness profile and the actual polishing-rate responsiveness profile.