Laser Scanning Surface Profiling for Semiconductor Wafer Bow Measurement
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Solution Overview
Problem
Existing methods for measuring semiconductor substrate planarity, such as laser interferometry, are expensive and time-consuming, and there is a need for alternative, more efficient techniques to determine substrate bowing and warping.
Innovation Solution
A non-contact, laser-scanning metrology tool that uses a fixed optical system to measure the slope of the substrate surface at multiple points, combining these measurements to determine the surface profile and calculate bow or warp.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If laser interferometry is used to measure substrate planarity, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent replaces the complex mechanical laser interferometry system with a simplified optical scanning system. Instead of using beam splitters, reference mirrors, and interferometric detection, the invention uses a single coherent light source that scans across the substrate surface, detecting reflected light intensity variations to determine surface profile and planarity parameters.
Solution Approach 2:
The patent creates an optical copy of the substrate surface profile by scanning coherent light across the surface and detecting reflected light patterns. The system reconstructs the surface topography through optical measurement rather than direct physical contact or complex interferometric analysis, enabling planarity assessment through simplified optical detection.
2Measurement precision
If laser interferometry is used to measure substrate planarity, then measurement accuracy is improved, but measurement time increases
Solution Approach 1:
The patent employs periodic scanning of coherent light across the substrate surface in systematic patterns. The light source scans back and forth across the substrate, collecting surface profile data through repeated periodic passes, which enables accurate planarity measurement while maintaining efficient measurement throughput through automated scanning sequences.
Solution Approach 2:
The patent maintains continuous measurement action by scanning the coherent light beam across the entire substrate surface without interruption. The system continuously collects surface profile data as the light scans across different regions, eliminating idle time between measurements and enabling complete substrate characterization in a single continuous operation.
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
Provides a cost-effective and efficient method for measuring substrate planarity, enabling accurate characterization of bow and warp without introducing motion artifacts, thus improving substrate quality control in semiconductor fabrication.
Implementation Method 1
directs a coherent light beam onto a surface of the substrate, detects light reflected from a plurality of measurement points on the surface of the substrate
Data Source
AI summary
Systems and methods are provided herein for determining the planarity of a semiconductor substrate. The systems and methods described herein use a metrology tool that utilizes a non-contact, laser-scanning technique to determine the planarity a semiconductor substrate. The metrology tool disclosed herein uses a fixed optical system to measure the slope of the substrate surface at multiple points across the substrate surface as the semiconductor substrate is moved in at least one direction (e.g., an x and/or y direction). The slope measurements obtained across the substrate surface are then combined to determine a surface profile of the semiconductor substrate, or used to calculate the amount of bow or warp attributed to the substrate surface.