Optical Fiber Bundle Layout for Accurate Etch Endpoint Detection
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Solution Overview
Problem
Conventional fiber optic cables for endpoint detection in semiconductor processing suffer from low optical throughput and spectral fidelity due to signal splitting, leading to errors and increased chamber downtime.
Innovation Solution
An optical bundle with paired fibers configured at specific angles (175-185 degrees) is used to transmit and receive light, maintaining light intensity and reducing signal loss, enabling precise endpoint detection in semiconductor etching processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a beam splitter is used to separate light signals in a conventional fiber optic cable, then both transmission and reception of light signals can be achieved in the same cable, but the overall power of the signal is reduced
Solution Approach 1:
The optical cable is divided into separate transmitting fibers and receiving fibers instead of using a single cable with a beam splitter. This segmentation allows each fiber to be optimized for its specific function, avoiding the signal power reduction caused by beam splitting while maintaining the ability to perform both transmission and reception operations.
2Loss of energy
If light signals are split and manipulated through amplification or filtering, then signal power can be maintained, but errors are introduced and measurement accuracy decreases
Solution Approach 1:
The harmful beam splitter component is extracted and removed from the system. By separating the transmitting and receiving paths into distinct fibers, the patent eliminates the need for signal manipulation through amplification or filtering, thereby avoiding the introduction of errors while maintaining signal integrity and measurement precision.
3Ease of operation
If conventional fiber optic cables are used for endpoint detection, then basic light transmission can be achieved, but optical throughput and spectral fidelity are low
Solution Approach 1:
The patent applies local quality by optimizing specific properties of the transmitting and receiving fibers for their respective functions. The transmitting fibers are optimized for efficient light delivery to the substrate, while the receiving fibers are optimized for collecting reflected light with high spectral fidelity, thereby improving overall system reliability without compromising ease of operation.
4Measurement precision
If additional measures are taken to reduce signal loss and improve detection accuracy, then measurement precision can be improved, but chamber downtime increases
Solution Approach 1:
The optical cable is pre-configured with separately optimized transmitting and receiving fibers during manufacturing, eliminating the need for additional signal manipulation components and calibration procedures. This preliminary optimization maintains high measurement precision while reducing chamber downtime by simplifying the system setup and reducing calibration requirements.
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
The optical bundle enhances light collection efficiency, maintains light intensity, and reduces signal loss, allowing for more accurate endpoint detection in semiconductor processing systems.
Implementation Method 1
The optical bundle has a plurality of fibers configured to transmit the light from a light source towards a substrate
Implementation Method 2
receive light reflected from the substrate disposed in the processing chamber
Implementation Method 3
The first receiving fiber is radially disposed at a pairing angle from the first emitting fiber. The pairing angle is between about 175 degrees and about 185 degrees
Data Source
AI summary
Disclosed herein is an endpoint detection having an optical bundle configured to emit light through a ceiling of a processing chamber. The optical bundle has a plurality of fibers configured to transmit the light from a light source towards a substrate and is configured to receive light reflected from the substrate. The plurality of fibers include a first emitting fiber and a first receiving fiber. The first receiving fiber is radially disposed at a pairing angle from the first emitting fiber, and is configured to receive light emitted from the first emitting fiber. The plurality of fibers further include a second emitting fiber and a second receiving fiber. The second receiving fiber is radially disposed at the pairing angle from the second emitting fiber. The second receiving fiber is configured to receive light originating from the second emitting fiber. The pairing angle is between about 175 degrees and 185 degrees.