Wafer Stress Imaging for Real-Time Non-Uniformity Control
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Solution Overview
Problem
Conventional semiconductor processing technologies require contact with the wafer for stress measurements, leading to defects being recognized only after processing, resulting in substrate scrapping and yield loss.
Innovation Solution
An optical imaging device within a cluster tool collects wafer surface color images in real-time, translating them into stress intensity data for comparison with reference data, allowing corrective actions to be implemented without contacting the wafer, such as adjusting processing recipes or replacing components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If contact-based stress measurement methods are used, then measurement accuracy is achieved, but substrate defects are recognized only after processing leading to yield loss
Solution Approach 1:
The optical imaging device performs stress measurements on the wafer surface before subsequent processing steps complete, enabling early detection of stress non-uniformity. The system captures color images and converts them to stress intensity data at an intermediate stage, allowing corrective actions to be taken before final processing that would otherwise render the substrate defective.
Solution Approach 2:
The patent replaces contact-based mechanical stress measurement methods with non-contact optical imaging. The optical imaging device uses light reflection and colorimetry to measure stress intensity without physically touching the wafer, eliminating the need to wait until after processing and enabling real-time monitoring and corrective actions.
2Manufacturing precision
If real-time optical imaging is implemented, then process uniformity control is improved, but system complexity increases
Solution Approach 1:
The optical imaging device is integrated into the existing cluster tool infrastructure, sharing vacuum chambers, wafer handling mechanisms, and control systems with other processing equipment. This multi-functionality approach allows the imaging system to utilize existing hardware resources rather than requiring entirely separate measurement equipment, thereby limiting the increase in overall system complexity.
Solution Approach 2:
The system uses color images as an intermediary representation of wafer stress states. By capturing optical reflectance data and converting it to stress intensity information through established colorimetry relationships, the system creates a manageable data intermediary that can be processed and analyzed without requiring direct complex mechanical measurement apparatus.
3Measurement precision
If contact-based measurement methods are used, then stress data is obtained, but wafer surface contamination occurs leading to defects
Solution Approach 1:
The patent replaces mechanical contact measurement systems with non-contact optical imaging. The optical imaging device measures stress intensity through light reflection and colorimetry without physically touching the wafer surface, thereby eliminating source of contamination while still acquiring accurate stress data for process control.
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 method ensures increased process uniformity and yield by identifying and addressing stress non-uniformity in real-time, reducing substrate losses and improving chip performance.
Implementation Method 1
reflecting light off a surface of a wafer with an optical imaging device disposed within a cluster tool
Data Source
AI summary
Methods of controlling stress non-uniformity for semiconductor processing may include reflecting light off a surface of a wafer with an optical imaging device disposed within a cluster tool. The cluster tool may include a multi-chamber processing system. The methods may include collecting one or more color images of the surface of the wafer. The methods may include converting the one or more color images to sample stress intensity data comparing the sample stress intensity data to reference wafer stress intensity data. The methods may include identifying deviations of the sample stress intensity data relative to the reference wafer stress intensity data. The methods may include determining corrective actions for bringing the sample stress intensity data into conformity with the reference wafer stress intensity data. The methods may include implementing the corrective actions on the multi-chamber processing system.