End Point Detection Using Diffused Light in Semiconductor Processing
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Solution Overview
Problem
Existing end point detection systems in semiconductor wafer processing face challenges such as optical noise interference, inaccurate measurements due to plastic chamber materials, and alignment issues, leading to inefficiencies and potential damage to workpieces.
Innovation Solution
A novel end point detection system that diffuses emitted light and places a light emitter and detector within the process chamber, with a translucent housing to reduce noise and prevent chemical contact, allowing for accurate detection without precise alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If optical end point detection is used to improve measurement speed and reliability, then productivity is improved, but measurement precision deteriorates due to optical noise from liquid sprays and plastic chamber materials
Solution Approach 1:
A diffuse reflector is introduced as an intermediary element between the light source and the workpiece. This diffuse reflector scatters the light uniformly, creating a noise-resistant optical path that eliminates the harmful effects of direct light paths through plastic chamber walls and liquid sprays, while maintaining fast optical detection speed
Solution Approach 2:
The optical detection system is configured with localized light emission and detection at specific positions within the chamber, using a diffuse reflector to create a localized measurement zone that is isolated from external optical noise sources such as chamber wall reflections and spray interference
2Reliability
If plastic materials are used for process chamber to resist chemical corrosion, then reliability is improved, but measurement precision deteriorates due to light penetration and stray light
Solution Approach 1:
The diffuse reflector serves as a mediator that creates a controlled light path independent of the plastic chamber walls. By scattering light uniformly in all directions, it ensures that only light reflected from the workpiece surface reaches the detector, blocking stray light paths through the translucent chamber material
Solution Approach 2:
The optical measurement is performed in a localized zone defined by the diffuse reflector and sensor positioning, creating a measurement environment that is chemically resistant (using plastic chamber) but optically precise (through localized light scattering and detection)
3Adaptability or versatility
If visual end point detection by human operator is used to adjust process parameters, then adaptability is improved, but productivity deteriorates due to manual operation and subjectivity
Solution Approach 1:
An automated optical detection system with diffuse reflector provides real-time feedback on the workpiece processing state by measuring light scattering changes. This feedback loop automatically detects endpoint conditions and can trigger process parameter adjustments, replacing manual visual inspection with objective, high-speed optical measurement that maintains adaptability while dramatically improving throughput
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 system enhances accuracy and reduces noise, enabling precise end point detection and efficient processing by minimizing stray light interference and chemical exposure, thus optimizing the processing time and preventing workpiece damage.
Implementation Method 1
the present end point detection system diffuses emitted light directed at the workpiece, and/or reflected light impinging on a light detecting element
Data Source
AI summary
In a workpiece process end point detection system, light is diffused and then light intensity or color is sensed. Optical noise is greatly reduced and more accurate end point detection can be made. A light emitter and a light sensor may be located within a workpiece process chamber. A housing around the light emitter and the light sensor seals out process fluids and also diffuses light passing through. The diffused light may be optically filtered before reaching the light sensor.