Nozzle Liquid Discharge Detection Using Reference Image Comparison
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Solution Overview
Problem
Conventional substrate processing apparatuses face challenges in reliably detecting the discharge of processing liquids from nozzles due to variations in substrate surface reflectance and noise, which can lead to incorrect detection of liquid discharge and nozzle position, affecting processing accuracy.
Innovation Solution
A substrate processing apparatus equipped with an imaging system that compares standard and monitor images to determine liquid discharge and nozzle position, using threshold settings and image processing techniques to account for substrate reflectance and noise, ensuring accurate detection regardless of substrate type and noise levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If imaging means is used to directly monitor discharge of processing liquid from nozzle, then discharge detection capability is improved, but measurement precision deteriorates due to substrate surface reflectance variations and noise
Solution Approach 1:
A liquid discharge determination unit is introduced as an intermediary between the imaging means and the discharge detection process. This unit processes the captured images by comparing them with reference images and determining whether liquid discharge has occurred based on image analysis, thereby eliminating the direct impact of substrate reflectance variations and noise on detection accuracy
Solution Approach 2:
Reference images are captured and stored before actual processing begins. These reference images serve as a baseline for comparison during discharge detection, allowing the system to account for substrate-specific reflectance characteristics in advance and improve detection precision during operation
2Reliability
If imaging means monitors discharge from nozzle, then discharge detection is improved, but device complexity increases due to additional imaging components and processing requirements
Solution Approach 1:
The imaging means is designed to serve multiple functions: capturing reference images during setup, monitoring liquid discharge during processing, and detecting nozzle position. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing device complexity while maintaining detection reliability
Solution Approach 2:
The system uses the existing imaging infrastructure to perform discharge detection without requiring additional specialized sensors or detection devices. The imaging means serves itself by processing its own captured images through the liquid discharge determination unit, eliminating the need for separate detection hardware
3Manufacturing precision
If nozzle position is determined by teaching, then positioning accuracy is improved, but reliability deteriorates due to adjustment errors during maintenance and temporal changes
Solution Approach 1:
The imaging means continuously captures images of the nozzle position, and the liquid discharge determination unit analyzes these images to determine the actual nozzle position in real-time. This feedback mechanism allows the system to detect and correct deviations from the taught position, maintaining positioning reliability even after maintenance or temporal changes
Solution Approach 2:
Reference images capturing the correct nozzle position are stored in advance during setup. These reference images serve as a permanent record of the correct position, allowing the system to compare current positions against this baseline and detect any drift or displacement that may occur during operation or after maintenance
Data Source
AI summary
An upper processing liquid nozzle moves back and forth between a processing position above a substrate held on a spin chuck and a standby position outside a processing cup. Before a processing liquid is discharged from the upper processing liquid nozzle having moved to the processing position, a camera takes a discharge standard image of an imaging region including the tip of the upper processing liquid nozzle. Then, multiple monitor target images of the imaging region taken successively by the camera are compared sequentially to the discharge standard image to determine discharge of a processing liquid from the upper processing liquid nozzle. The discharge standard image is obtained for each process on a new target substrate. This eliminates influence of a substrate surface to appear as a background both of the monitor target image and the discharge standard image. Thus, discharge of a processing liquid can be detected reliably.