Sensor Device for Etching Apparatus Focus Ring Wear Monitoring
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Solution Overview
Problem
In semiconductor etching processes, the exposure of components to corrosive plasma leads to wear of the focus ring, affecting the processing ability and quality of the wafer, particularly at the edge portion.
Innovation Solution
An etching apparatus equipped with a sensor device that measures the wear of the focus ring and adjusts its height using an elevating member, ensuring accurate imaging and compensation of the focus ring's wear without exposing the sensor to plasma, thereby maintaining process capability and preventing damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the sensor device is placed inside the reaction chamber to measure focus ring wear, then measurement capability is improved, but the sensor is exposed to corrosive plasma which reduces its reliability and lifespan
Solution Approach 1:
A transfer chamber is introduced as an intermediary space between the reaction chamber and the sensor device. The transfer chamber allows the sensor device to move into position to measure the focus ring wear, then retract to a safe position away from the plasma environment. This mediator chamber enables the sensor to perform its measurement function without being permanently exposed to the corrosive plasma that would otherwise degrade its reliability.
2Measurement precision
If the sensor device remains stationary inside the reaction chamber for continuous monitoring, then real-time measurement capability is improved, but the complexity of the system increases and the sensor is continuously exposed to plasma
Solution Approach 1:
The sensor device is made dynamic rather than stationary, capable of moving between a measurement position near the focus ring and a retracted safe position. This dynamic positioning allows the sensor to monitor focus ring wear at critical moments (such as during or after plasma exposure cycles) without remaining continuously exposed to the plasma environment, thereby reducing system complexity compared to a permanently installed sensor while still providing effective monitoring capability.
3Device complexity
If the focus ring height is not compensated for wear, then the structure remains simple, but the manufacturing precision of the wafer edge portion deteriorates
Solution Approach 1:
A feedback mechanism is implemented where the sensor device measures the actual wear of the focus ring, and this measurement information is used to adjust or compensate the focus ring height. The system continuously monitors the focus ring condition and makes corrective adjustments to maintain the proper height, ensuring that wafer edge quality remains high despite the focus ring being subject to plasma-induced wear over time.
Solution Approach 2:
The focus ring height parameter is made adjustable and dynamically changeable based on measured wear conditions. Instead of using a fixed-height focus ring structure, the system allows the height parameter to be modified in response to sensor measurements, enabling compensation for wear and maintaining manufacturing precision without requiring complete structural redesign.
Data Source
AI summary
An etching apparatus includes a reaction chamber having an internal space, a fixing chuck disposed in the reaction chamber, an electrostatic chuck disposed on the fixing chuck and on which a wafer is placed, a focus ring surrounding the electrostatic chuck, and a sensor device configured to be transferred into or out of the reaction chamber and placed on the electrostatic chuck. The sensor device includes a body having a plate shape, and a sensor disposed on an upper surface of the body which senses whether the focus ring is worn.