Sensor Assembly for Edge Ring Position Detection
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Solution Overview
Problem
Conventional methods for determining the position of edge rings in semiconductor process kits are limited by the need for direct optical monitoring and are prone to interference from plasma and RF frequencies, especially when rings become wedged or debris builds up, affecting plasma sheath uniformity and die yields.
Innovation Solution
A sensor assembly with an alignment pin and contact member, coupled with a light emitting sensor, measures the displacement of the contact member to determine the position of edge rings, allowing for accurate positioning even when rings are obscured, and includes a housing with a transparent window to maintain signal quality and prevent arcing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical methods (interferometry) are used to measure ring position, then measurement can be performed non-contact, but the measurements are prone to interference from plasma and RF frequencies and require direct optical monitoring which is not possible when rings are obscured
Solution Approach 1:
The patent replaces optical measurement methods with a mechanical measurement system. A mechanical probe contacts the ring surface directly, and a displacement sensor measures the probe's position. This mechanical approach eliminates susceptibility to plasma and RF interference that plagues optical methods, while maintaining measurement accuracy through direct physical contact with the ring.
Solution Approach 2:
The patent introduces a mechanical probe as an intermediary between the measurement system and the ring. The probe physically contacts the ring surface and translates ring position into probe displacement, which is then measured by a displacement sensor. This intermediary mechanism allows accurate measurement even when the ring is obscured from direct optical view.
2Measurement precision
If mechanical measurement methods (stylus) are used to determine ring position, then direct contact measurement is possible, but the process requires manual operation and is time-consuming
Solution Approach 1:
The measurement system is integrated into the ring handling process itself. As rings are automatically transported and positioned by the substrate support mechanism, the mechanical probe automatically contacts and measures each ring without requiring separate manual measurement steps. The system measures rings during their normal operational movement, eliminating idle measurement time.
Solution Approach 2:
The patent enables continuous measurement of multiple rings as they are sequentially presented to the measurement position. The automated system maintains continuous operation by measuring rings during their normal transport and positioning cycles, rather than requiring interruption of the process for batch measurements. This keeps the measurement action continuous and integrated with ring handling.
3Reliability
If rings are replaced during maintenance, then compliance with specifications can be ensured, but verification of correct position and compliance requires complex measuring and testing techniques
Solution Approach 1:
The patent replaces complex optical measurement systems with a simple mechanical probe and displacement sensor arrangement. The mechanical probe directly contacts the ring and measures position through physical displacement, eliminating the need for complex optical setups, interferometry equipment, and associated alignment procedures. This simplifies the measurement system while maintaining compliance verification capability.
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 enables reliable and accurate determination of edge ring position and weight, simplifying maintenance and reducing interference from electromagnetic waves and high temperatures, thereby improving plasma sheath uniformity and die yields.
Implementation Method 1
A light emitting sensor is configured to detect a displacement of the contact member
Data Source
AI summary
Examples disclosed herein are directed to a method and apparatus for determining a position of a ring within a process kit. In one example, a sensor assembly for a substrate processing chamber is provided. The sensor assembly includes a housing having a top surface, a bottom surface opposite the top surface, and a plurality of sidewalls connecting the top surface to the bottom surface. The housing also has a recess in the top surface, the recess forming an interior volume within the housing. The sensory assembly includes a bias member, and a contact member disposed on the bias member. The bias member and contact member are disposed within the recess. A sensor is configured to detect a displacement of the contact member. The displacement of the contact member corresponds to a relative position of an edge ring.