Plasma Chamber Pressure Calibration via Dual Vacuum Gauges
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Solution Overview
Problem
Existing plasma processing apparatuses face inaccuracies in pressure calibration, particularly at high vacuum conditions, leading to deviations in processing results and yield, as they do not adequately account for the pressure conditions between the load lock chamber and the processing chamber, resulting in variations in processed shape dimensions and reduced processing yield.
Innovation Solution
A plasma processing apparatus with a first vacuum gauge for detecting pressure in the processing chamber and a second vacuum gauge for calibration, along with a correction unit, is used to correct the output of the first vacuum gauge at pressure values including zero and higher values, ensuring accurate pressure calibration across various conditions, including high vacuum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single pressure gauge is used for pressure adjustment in the processing chamber, then the device complexity is reduced, but the measurement precision deteriorates at high vacuum conditions
Solution Approach 1:
The pressure measurement function is segmented into two independent pressure gauges: a first pressure gauge for general pressure adjustment and a second pressure gauge for calibration. This segmentation allows each gauge to serve its specific purpose optimally, with the second gauge providing accurate reference measurements at high vacuum conditions without compromising the first gauge's broader operational range.
Solution Approach 2:
The second pressure gauge acts as an intermediary reference instrument that provides accurate calibration data. By comparing the output of the first pressure gauge against the second gauge's accurate measurements, the system mediates between the need for simple operation and the requirement for high measurement precision at extreme vacuum levels.
2Ease of operation
If pressure calibration is performed only at atmospheric pressure conditions, then the ease of operation is improved, but the manufacturing precision deteriorates at high vacuum conditions
Solution Approach 1:
The system performs preliminary calibration actions at multiple pressure conditions including high vacuum states. By pre-calibrating the first pressure gauge against the second gauge at various pressure points (including near-zero pressure), the system ensures accuracy is established beforehand for all operating conditions, not just atmospheric pressure.
Solution Approach 2:
The calibration process utilizes parameter changes by performing corrections at multiple different pressure conditions (atmospheric pressure, intermediate pressures, and high vacuum). This multi-parameter calibration approach ensures the pressure gauge maintains accuracy across the entire operating range, directly impacting manufacturing precision.
3Ease of manufacture
If the pressure gauge is calibrated under atmospheric pressure conditions, then the ease of manufacture is improved, but the reliability deteriorates during plasma processing
Solution Approach 1:
The calibration system is dynamic rather than static. It performs corrections at multiple pressure conditions including high vacuum states that actually occur during plasma processing. The calibration adapts to different operating conditions, ensuring the pressure gauge remains reliable throughout the entire pressure range from atmospheric to high vacuum.
Solution Approach 2:
The system implements feedback by continuously comparing the first pressure gauge readings against the second pressure gauge (which provides accurate reference measurements) at various pressure conditions. This feedback mechanism identifies deviations and applies corrections, ensuring the pressure control system maintains high reliability during actual plasma processing operations.
4Loss of time
If calibration is performed without considering high vacuum pressure conditions, then the loss of time is reduced, but the productivity deteriorates due to yield loss
Solution Approach 1:
Comprehensive calibration at multiple pressure conditions is performed as a preliminary action before production runs. By completing thorough calibration including high vacuum conditions upfront, the system prevents yield loss during actual processing, ensuring pressure accuracy is guaranteed before wafers are manufactured.
Solution Approach 2:
The calibration process efficiently utilizes parameter changes by performing measurements at multiple discrete pressure points (including near-zero pressure conditions). This multi-point calibration approach, while requiring more time than single-point calibration, establishes a comprehensive accuracy profile that prevents processing defects and maintains high productivity through yield protection.
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 approach improves the accuracy of pressure calibration, reducing variations in processed shape dimensions and enhancing the processing yield by ensuring precise pressure control during semiconductor wafer processing.
Implementation Method 1
a first vacuum gauge that is configured to detect a pressure in the processing chamber during the processing of the wafer
Implementation Method 2
a second vacuum gauge for calibration that is below the first vacuum gauge and in communication with an opening that disposed on an inner wall of the processing chamber
Implementation Method 3
an exhaust port that is disposed at a bottom portion of the lower space and is in communication with an exhaust device that exhausts and decompresses an inside of the processing chamber
Implementation Method 4
a heater that is configured to heat a lower portion of the vacuum container surrounding the lower space
Implementation Method 5
a plasma forming space that is a space above the sample stage of the processing chamber and in which plasma for processing the wafer is formed by using a supplied processing gas
Data Source
AI summary
To provide a plasma processing apparatus or an operating method of a plasma processing apparatus with improved yield. The plasma processing apparatus includes: a sample stage disposed in the processing chamber in a vacuum container; a plasma forming space in which plasma for processing a wafer is formed above the sample stage and a lower space communicated with the plasma forming space below; an exhaust port disposed at a bottom portion of the lower space; a heater for heating a lower portion of the vacuum container surrounding the lower space; a first vacuum gauge that detects a pressure in the processing chamber during the processing of the wafer; a second vacuum gauge for calibration communicated with an opening disposed in an inner wall of the processing chamber surrounding an outer periphery of the lower space below the first vacuum gauge; and a correction unit that is configured to correct an output of the first vacuum gauge by using outputs of the first and second vacuum gauges when a pressure in the processing chamber is at a pressure value regarded as 0 and at a plurality of pressure values higher than the pressure value.