Substrate Holding State Detection via Multi-Position Light Reflection
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Solution Overview
Problem
Existing substrate processing apparatuses inaccurately detect the holding state of substrates due to the effects of layers formed on the substrates and surface states, leading to erroneous results regardless of the detection position.
Innovation Solution
A substrate processing apparatus that includes a placement table, a light source for irradiating light on the substrate, a detector for measuring the light amount reflected from the substrate, and a control unit that determines the holding state by consecutively changing detection positions and accumulating detection values, determining the holding state as abnormal only when a predetermined number of consecutive measurements below a threshold are reached.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single detection position is used to detect substrate holding state, then the detection process is simple and fast, but the detection accuracy is low due to effects of layers and surface states
Solution Approach 1:
The detection process is segmented into multiple detection positions around the substrate. Instead of using a single detection point, the system divides the detection task into multiple positions (e.g., multiple angular positions) to collectively assess the substrate holding state, thereby improving accuracy while managing complexity through systematic division
Solution Approach 2:
The detection is performed periodically at multiple positions as the substrate rotates or is repositioned. The system uses periodic detection cycles where the detector moves to different positions or the substrate is rotated to present different positions to the detector, allowing comprehensive assessment without requiring all positions simultaneously
2Measurement precision
If multiple detection positions are used to improve detection accuracy, then the detection precision improves, but the detection time increases
Solution Approach 1:
The detection process is made continuous by performing measurements at multiple positions without interrupting the substrate processing flow. The system continuously detects at different positions as the substrate moves or rotates, ensuring that detection occurs throughout the processing cycle rather than requiring separate measurement steps
Solution Approach 2:
Detection is performed periodically at multiple positions during the substrate's rotation or movement through processing chambers. This allows the system to gather data from multiple positions while maintaining continuous processing, reducing total detection time compared to stopping at each position
3Reliability
If light detection is performed on substrates with layers and complex surface states, then surface information is captured, but detection errors increase due to light absorption and scattering effects
Solution Approach 1:
The system performs continuous detection at multiple positions to accumulate sufficient signal data that overcomes local variations caused by layers and surface states. By continuously measuring reflected light intensity across multiple positions, the system builds a reliable assessment that compensates for localized light absorption and scattering effects
Solution Approach 2:
The detection process segments the substrate assessment into multiple positional measurements rather than relying on a single measurement. This segmentation allows the system to identify patterns consistent with proper holding across multiple positions, filtering out erroneous readings caused by local surface characteristics
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 allows for accurate detection of the substrate holding state without being influenced by layers or surface states, reducing erroneous detections and improving processing reliability.
Implementation Method 1
a light source configured to irradiate light on the surface of the substrate on the placement table; a detector configured to detect the light amount reflected from the surface of the substrate
Data Source
AI summary
Provided is a substrate processing apparatus including a placement table on which a substrate is disposed; a light source configured to irradiate light on the surface of the substrate on the placement unit; a detector configured to detect the light amount reflected from the substrate; and a control unit configured to perform a determination process of determining whether a detection value of the light amount is smaller than a predetermined value at a plurality of positions, and to determine that a holding state of the substrate is abnormal when the total number of times of determination in which it is determined that the detection value is smaller than the predetermined value reaches a predetermined number of times.