Capacitive Sensor Gap Control for High-Temperature Wafer Placement
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Solution Overview
Problem
Current methods for monitoring the gap between a wafer and a deposition source in processing tools face challenges due to temperature limitations of cameras, limited space for remote imaging, and interference from high-temperature processes, making it difficult to ensure uniform deposition thickness and quality.
Innovation Solution
The use of proximity sensors, specifically capacitive or inductive displacement sensors, are integrated into the processing fixture to measure the gap distance between the fixture and susceptor, allowing for precise detection of wafer positioning and gap control, even at high temperatures, and enabling accurate placement and alignment of wafers within recesses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cameras are used to monitor gap uniformity, then measurement precision is improved, but the system cannot operate at high temperatures above 80°C
Solution Approach 1:
The patent replaces optical detection systems (cameras) with capacitive sensors to measure gap uniformity. Capacitive sensors can operate at high temperatures where optical detectors would overheat, enabling gap monitoring during high-temperature deposition processes without temperature limitations.
Solution Approach 2:
The patent introduces capacitive sensors as an intermediary measurement system between the processing fixture and susceptor. These sensors serve as a mediator that can withstand high temperatures while providing precise gap measurements, bridging the gap between process conditions and measurement requirements.
2Device complexity
If cameras are arranged around the outside edge of wafer support, then device complexity is reduced, but they cannot easily monitor the inside edge of the support
Solution Approach 1:
The patent divides the monitoring function into multiple capacitive sensors positioned at different locations (including inside edges) of the processing fixture. This segmentation allows each sensor to independently monitor specific regions, including areas that would be inaccessible to externally mounted cameras.
Solution Approach 2:
The patent transitions from external 2D camera monitoring to distributed 3D sensor positioning. By placing capacitive sensors at multiple spatial dimensions including inside edges, the system achieves comprehensive coverage of the susceptor surface that external cameras cannot access.
3Measurement precision
If proximity sensors are integrated into the processing fixture, then measurement precision at high temperatures is improved, but device complexity increases
Solution Approach 1:
The patent merges the capacitive sensors directly into the processing fixture structure, combining the measurement function with the processing system. This integration eliminates the need for separate external measurement systems and reduces overall system complexity despite adding sensor functionality.
Solution Approach 2:
The processing fixture is designed to serve multiple functions: it provides the processing surface, supports the susceptor, and integrates capacitive sensors for gap measurement. This multi-functionality reduces the need for separate dedicated measurement systems, offsetting the complexity of sensor integration.
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 solution provides accurate and reliable gap control and wafer placement, even in high-temperature environments, enhancing the uniformity of deposition processes and maintaining optimal wafer positioning, which is critical for maintaining deposition quality and throughput.
Implementation Method 1
three or more capacitive displacement sensors that measures the gap distance
Implementation Method 2
one or more proximity sensor(s) retained within the one or more openings
Data Source
AI summary
Apparatus and methods of dimension control and monitoring between a processes fixture and a susceptor, and position determination of wafers are described.