Plasma Processing Apparatus Stable End-Point Detection
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Solution Overview
Problem
In semiconductor wafer dry etching, the faint change in light-emission intensity at the etching end point is difficult to detect accurately due to significant noise components when comparing low and high light-emission intensity signals, especially in low opening ratio wafers, leading to unstable end-point detection.
Innovation Solution
A plasma processing apparatus that uses an optical receiver to collect light emissions at multiple wavelengths during different time intervals and a detector to process these signals, ensuring that intensities are not saturated, allowing for the calculation of a combined spectrum by multiplying non-saturated intensity data, thereby enhancing the signal-to-noise ratio for stable end-point detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If division is performed between light-emission intensity of reaction product and light-emission intensity of etchant to amplify faint change at etching end point, then end-point detection sensitivity is improved, but noise component becomes relatively large when comparing low and high intensity signals making accurate detection difficult
Solution Approach 1:
The optical receiver alternately measures light emission intensity at multiple wavelengths during different time intervals within one processing cycle. This periodic measurement approach allows the system to collect data from both low-intensity and high-intensity wavelengths without noise accumulation, then combines these measurements to achieve both high sensitivity and low noise in end-point detection.
2Loss of information
If light emission intensity at multiple wavelengths is measured simultaneously, then comprehensive spectral information is obtained, but saturation occurs in high intensity regions reducing measurement accuracy
Solution Approach 1:
The measurement process is segmented into multiple time intervals, with each interval dedicated to measuring specific wavelengths. By dividing the measurement into sequential segments rather than simultaneous measurement, the system avoids saturation in high-intensity regions while still collecting comprehensive spectral information across all wavelengths through the combination of segmented measurements.
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 enables stable and accurate end-point detection with a high signal-to-noise ratio, even when light-emission intensities differ significantly, by compensating for saturated areas with data from alternate time intervals, improving the detection precision in low opening ratio wafers.
Implementation Method 1
detecting the light-emission from the plasma during the processing
Implementation Method 2
processing it using plasma formed inside the processing chamber
Data Source
AI summary
A processing apparatus and a processing method for a semiconductor wafer, which allow stable end point detection, are provided. In the plasma processing apparatus or method in which a processing-target film layer of a film structure including a plurality of film layers formed in advance on a surface of a wafer mounted on a sample stage deployed within a processing chamber inside a vacuum vessel, by using plasma formed with the processing chamber, intensities of lights of a plurality of wavelengths are detected using data composed of results of reception of lights during a plurality of different time-intervals by an optical receiver which receives lights of the plurality of wavelengths from an inside of the processing chamber while processing is going.