Laser-Cracked Substrate Edge Polishing for Precision
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Solution Overview
Problem
Conventional polishing apparatuses for semiconductor substrates face instability in positioning the polishing tape, leading to inaccurate polishing and potential particle generation in subsequent processing steps due to serrated recesses and displacement of the polishing start position.
Innovation Solution
A substrate processing method and apparatus that uses a laser beam to create an annular crack in the substrate's edge portion, followed by a polishing tool to form a stepped recess, ensuring accurate formation and removal of material from the peripheral area, with optional use of adhesive tape for material removal and a position detector for precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a polishing tape is pressed against a substrate edge using an air cylinder, then the peripheral portion of the substrate can be polished to form a stepped recess, but the position of the polishing tape becomes unstable and the polishing start position may be displaced
Solution Approach 1:
The patent applies preliminary action by forming an annular crack in the substrate edge portion using a laser beam before the polishing process. This pre-created crack serves as a precise guide for the polishing tape, ensuring that the polishing starts at the correct position and maintains stable positioning throughout the process, thereby resolving the positioning accuracy and stability issues.
Solution Approach 2:
The patent replaces the mechanical positioning system (air cylinder pressing the polishing tape) with a laser-based system. The laser beam creates a precise annular crack that guides the polishing tape, substituting the mechanical force-based positioning with an optical-based precision system, thus improving both positioning accuracy and stability.
2Productivity
If a polishing tape is pressed against a rotating substrate to form a stepped recess, then material can be removed from the peripheral portion, but the recess may have a serrated inside surface that causes particles in subsequent processing
Solution Approach 1:
The patent applies preliminary action by creating an annular crack in the substrate edge portion before polishing. This pre-formed crack provides a clean, precise boundary that guides the polishing tape, enabling smooth material removal without creating serrated surfaces. The crack acts as a template that ensures uniform polishing and prevents particle generation, thus resolving both productivity and surface quality issues.
Solution Approach 2:
The patent replaces the direct mechanical polishing approach with a combined laser and polishing system. The laser creates a precise annular crack that serves as a guide, and the polishing tape follows this guide to remove material smoothly. This substitution of mechanical positioning with optical guidance eliminates the serrated surface problem while maintaining efficient material removal.
3Device complexity
If the polishing start position is not precisely controlled, then the polishing process can proceed without complex positioning systems, but the stepped recess cannot be formed accurately in the peripheral portion
Solution Approach 1:
The patent applies preliminary action by using a laser beam to create an annular crack in the substrate edge portion before polishing. This pre-formed crack serves as a precise positional reference that guides the polishing tape, ensuring accurate stepped recess formation without requiring complex mechanical positioning systems. The laser-based approach simplifies the overall device complexity while maintaining high manufacturing precision.
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
The method achieves highly accurate formation of stepped recesses in semiconductor substrates, reducing particle generation and improving yield by stabilizing the polishing process and ensuring precise material removal.
Implementation Method 1
directing a laser beam to an edge portion of the rotating substrate to form an annular crack in the substrate
Data Source
AI summary
A method and an apparatus for processing a peripheral portion of a substrate, such as a wafer, are disclosed. The substrate processing method includes: holding a substrate on a substrate stage; rotating the substrate stage and the substrate about an axis of the substrate stage; directing a laser beam to an edge portion of the rotating substrate to form an annular crack in the substrate; and pressing a polishing tool against the edge portion of the rotating substrate to form a stepped recess in a peripheral portion of the substrate.