Focus Ring Consumption Measurement via Electrostatic Capacitance
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Solution Overview
Problem
The existing methods for measuring the consumption of a focus ring in plasma etching apparatuses are inefficient, as they require exposing the processing chamber to atmospheric conditions, leading to contamination risks, decreased productivity, and increased manufacturing costs due to the need for modifying the apparatus with optical windows.
Innovation Solution
A measurement system using a sensor substrate with a distance sensor that can measure the consumption of the focus ring without exposing the processing chamber to atmospheric conditions, allowing for continuous operation and maintaining the chamber's vacuum state, by transferring the sensor substrate into the chamber and using electrostatic capacitance sensors to determine the focus ring's thickness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the processing chamber is exposed to atmospheric atmosphere to measure focus ring thickness using Vernier Caliper, then measurement can be performed, but productivity decreases due to vacuum re-establishment time and contamination risks increase
Solution Approach 1:
The patent replaces the mechanical measurement system (Vernier Caliper requiring atmospheric exposure) with an electromagnetic measurement system (distance sensor using electrostatic capacitance). This allows measurement to be performed through the chamber wall without breaking vacuum, eliminating the productivity loss associated with vacuum re-establishment while maintaining measurement capability.
Solution Approach 2:
The patent introduces a distance sensor as an intermediary measurement device that can operate through the chamber wall. This intermediary enables measurement without direct contact with the focus ring, allowing the chamber to remain sealed and maintaining vacuum state throughout the measurement process.
2Measurement precision
If Vernier Caliper is brought into contact with processing chamber to measure focus ring, then thickness measurement is possible, but by-product peeling occurs causing contamination
Solution Approach 1:
The patent replaces contact-based mechanical measurement with non-contact electromagnetic measurement using a distance sensor. This substitution eliminates the mechanical interaction that causes by-product peeling, thereby preventing contamination of the target substrate while still enabling accurate thickness measurement.
Solution Approach 2:
The distance sensor acts as an intermediary that measures focus ring thickness without physical contact. This intermediary measurement approach avoids the harmful mechanical interaction between the caliper and chamber wall that would otherwise cause by-product detachment and contamination.
3Measurement precision
If optical windows are installed to enable laser beam measurement of focus ring, then non-contact measurement is achieved, but manufacturing cost increases and design flexibility decreases
Solution Approach 1:
The patent uses a distance sensor as an intermediary measurement device that can operate through the existing chamber wall structure. This approach eliminates the need to install optical windows, thereby reducing manufacturing costs while still enabling non-contact measurement of focus ring consumption.
Solution Approach 2:
The patent replaces the optical measurement system (requiring laser windows) with an electromagnetic measurement system (distance sensor). This substitution eliminates the need for costly optical window installations and modifications to the chamber structure, reducing manufacturing complexity and cost while maintaining measurement 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
Enables accurate measurement of focus ring consumption without disrupting the vacuum state, reducing contamination risks and maintaining productivity, while avoiding the need for additional optical windows, thus preserving the design flexibility and cost-effectiveness of the plasma etching apparatus.
Implementation Method 1
a sensor substrate having a distance sensor; and a measurement unit configured to measure a consumption amount of the focus ring, wherein the measurement unit includes: a transfer instruction unit configured to instruct the transfer unit to transfer the sensor substrate into the processing chamber; an acquisition unit configured to acquire information on a physical amount corresponding to a distance from the distance sensor to the focus ring, which is measured by the distance sensor
Data Source
AI summary
A measurement system for measuring a consumption amount of a focus ring in a plasma etching apparatus including a processing chamber, a lower electrode and the focus ring surrounding a periphery of the lower electrode, comprises a sensor substrate having a distance sensor and a measurement unit configured to measure a consumption amount of the focus ring. The measurement unit includes a transfer instruction unit, an acquisition unit and a measurement unit. The transfer instruction unit is configured to instruct a transfer unit to transfer the sensor substrate into the processing chamber. The acquisition unit is configured to acquire information on a physical amount corresponding to a distance from the distance sensor to the focus ring, which is measured by the distance sensor. The measurement unit is configured to measure a consumption amount of the focus ring based on the acquired information on the physical amount.