Laser-based Thickness Control in a Double-Side Polishing System for Silicon Wafers

Area of Science:

• Semiconductor Manufacturing
• Materials Science
• Precision Engineering

Background:

• Accurate thickness control is vital for large, thin silicon wafers in semiconductor fabrication.
• Existing automated polishing methods require refinement for enhanced precision.

Purpose of the Study:

• To demonstrate an advanced double-side polishing (DSP) system with integrated feedback control for silicon wafer thickness.
• To detail the mechanical structure, signal processing, and control strategies of the DSP system.
• To validate the effectiveness of the B-spline model in characterizing and controlling wafer thickness.

Main Methods:

• Development of a DSP system incorporating a laser probe for real-time wafer thickness scanning.
• Implementation of a feedback control loop utilizing laser scan data for thickness adjustment.
• Application of a B-spline model to accurately represent wafer thickness deviation.
• Experimental evaluation of the DSP system's performance in wafer thickness control.

Main Results:

• Precise positioning of the laser probe ensures continuous and valid thickness data acquisition.
• The B-spline model effectively characterizes wafer thickness, providing reliable deviation information.
• Experimental results demonstrate effective control of thickness variation using the DSP system and B-spline fitting.

Conclusions:

• The developed DSP system offers a robust solution for precise silicon wafer thickness control.
• The integration of laser probing, feedback control, and B-spline modeling significantly enhances polishing accuracy.
• This approach is crucial for improving yield and quality in semiconductor wafer manufacturing.