Plasma Etching Endpoint Detection via Optical Interference
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Solution Overview
Problem
Existing plasma processing techniques struggle to achieve high precision in etching film layers within trenches with varying initial depths, leading to incomplete processing and reduced yield due to difficulties in measuring groove depth accurately.
Innovation Solution
A plasma processing method and apparatus that involves forming plasma in a vacuum chamber, etching the upper film layer to expose the groove structure's end, and using light emission intensity variations to determine the endpoint of etching, allowing for precise measurement of remaining film thickness and trench depth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional plasma etching is performed on film layers within trenches with varying initial depths, then etching processing can be completed, but measurement precision of groove depth deteriorates leading to incomplete processing
Solution Approach 1:
The patent uses optical interference phenomena where light reflects off different film layer interfaces (top surface and groove interface) creating interference patterns. By detecting changes in interference light intensity and wavelength, the system can precisely measure film thickness and groove depth even when initial trench heights vary, thereby resolving the measurement precision problem while maintaining etching precision
Solution Approach 2:
The patent implements real-time monitoring of interference light during plasma etching processing. The detected light intensity variations provide feedback about the etching progress and remaining film thickness, allowing the system to accurately determine when the desired groove depth is achieved despite variations in initial trench depths across different wafers
2Manufacturing precision
If etching processing is performed to achieve desired groove depth, then processing quality improves, but yield degrades due to inability to accurately determine endpoint
Solution Approach 1:
The system continuously monitors interference light intensity during etching and uses this feedback to precisely determine the endpoint of the etching process. By detecting when the interference pattern indicates the desired groove depth has been reached, the system可以避免 over-etching or under-etching, thereby maintaining high processing quality while improving yield through consistent, accurate endpoint detection
Solution Approach 2:
The patent replaces mechanical or contact-based measurement methods with optical detection of interference light patterns. This non-contact optical measurement system can accurately detect groove depth and film thickness in real-time during processing, providing precise endpoint detection that improves both groove depth accuracy and processing yield
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 high-precision etching of film layers within trenches, improving processing yield by accurately determining the completion of the desired groove depth, even with non-uniform initial trench heights.
Implementation Method 1
forming plasma in the processing chamber; performing etching to a film to be processed of a film structure that has previously been disposed on an upper surface of the wafer
Implementation Method 2
using light acquired from a film structure during the processing to a film layer to be processed of the film structure including a plurality of film layers previously disposed on a surface of the sample
Implementation Method 3
Intensity of interference light including a plurality of wavelengths from a surface of a sample or a change with respect to a temporal change of a rate of change of the intensity, is detected from a top of the sample
Data Source
AI summary
A plasma processing method includes forming plasma in a processing chamber; and performing etching to a film to be processed of a film structure that has previously been disposed on an upper surface of a wafer that includes a plurality of film layers. The film structure includes: a lower film including at least one film layer and a groove structure; and an upper film including at least one film layer that covers an inside and an upper end of the groove structure. The plasma processing method includes: removing the upper film by etching until an upper end of the groove structure of the lower film is exposed; performing etching to a film layer of the upper film inside the groove structure; and determining an end point by using a value of thickness of the film layer inside the groove structure of the lower film upon completion of the removing.