Substrate Drying Nozzle Dynamics and Sensor Feedback Control
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Solution Overview
Problem
The existing single wafer IPA drying method faces challenges in effectively drying large diameter substrates without causing defects like watermarks or residual foreign substances, due to inappropriate drying conditions and relative moving speeds between the rinse agent and drying gas nozzles and the substrate surface.
Innovation Solution
A substrate drying apparatus and method that includes a rotating substrate mechanism, a rinse agent nozzle, a drying gas nozzle, and sensors to control the drying conditions based on real-time sensing of the rinse edge, ensuring the rinse edge is spread evenly towards the substrate's outer circumference using centrifugal and Marangoni forces, with adjustable ejection amounts and speeds to maintain optimal drying performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the rinse agent nozzle and drying gas nozzle are moved from the center to the outer circumference of the substrate, then the drying uniformity is improved, but the relative moving speed difference between nozzle and substrate surface increases causing inappropriate drying conditions
Solution Approach 1:
The patent applies dynamics by making the nozzle moving speed adjustable and adaptable during the drying process. The control unit dynamically adjusts the moving speed of the rinse agent nozzle and drying gas nozzle based on real-time feedback from sensors, allowing the system to maintain optimal relative moving speed between the nozzle and substrate surface throughout the movement from center to outer circumference.
Solution Approach 2:
The patent implements feedback control by using sensors to detect the actual state of the substrate surface and nozzle position, then feeding this information back to the control unit. The control unit processes this feedback and adjusts the nozzle moving speed accordingly, ensuring that the drying conditions remain appropriate even as the relative moving speed difference changes during the process.
2Productivity
If the substrate rotation speed is increased to maintain high throughput, then the productivity is improved, but the defect occurrence increases due to insufficient drying time
Solution Approach 1:
The patent applies continuity of useful action by ensuring that the drying process continues effectively throughout the entire substrate surface without interruption. The rinse agent nozzle and drying gas nozzle continuously move from the center to the outer circumference while the substrate rotates, maintaining continuous drying action. This allows high throughput to be achieved without compromising drying quality, as the drying process is sustained throughout the entire cycle.
Solution Approach 2:
The patent implements preliminary action by applying the drying process in a controlled sequence from the center to the outer circumference of the substrate. The rinse agent and drying gas are supplied in advance to specific regions before the substrate completes its rotation, ensuring that each area receives adequate drying treatment. This preliminary and sequential approach prevents defects while maintaining high productivity.
3Manufacturing precision
If the ejection amount of rinse agent is increased to improve drying coverage, then the drying effectiveness is improved, but the liquid flow control becomes difficult causing non-uniform drying
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the ejection amount of the rinse agent based on the nozzle's position and the substrate's rotation speed. The control unit modifies the rinse agent flow rate parameter in real-time as the nozzle moves from the center to the outer circumference, compensating for changes in centrifugal force and surface speed. This ensures uniform drying coverage while maintaining easy liquid flow control throughout the process.
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 effectively suppresses defect occurrence by ensuring uniform drying across the substrate surface, maintaining high throughput, and adapting to varying substrate sizes by dynamically controlling the rinse agent and drying gas distribution.
Implementation Method 1
the rinse agent is moved to the outer circumference side by centrifugal force and Marangoni force
Implementation Method 2
by increasing surface tension of an edge or an interface of the rinse agent (hereinafter referred to as "rinse edge") outward by the Marangoni effect caused by the IPA
Data Source
AI summary
The substrate drying apparatus includes a rinse agent nozzle configured to eject a rinse agent to the substrate while moving away from a center of the substrate relative to the substrate, a drying gas nozzle configured to spout a drying gas to the substrate while moving away from the center of substrate relative to the substrate with movement of the rinse agent nozzle, a liquid area sensor and a dried area sensor configured to sense a surface of the substrate around an interface of the rinse agent by moving away from the center of the substrate with movement of the rinse agent nozzle and the drying gas nozzle, and a control unit configured to control a drying condition based on the sensing results of the liquid area sensor and the dried area sensor.