Spin-Coating Fluid Velocity Sensing for Pattern Fidelity Control
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Solution Overview
Problem
Conventional spin-on processes for semiconductor substrates face adverse local fluid dynamic effects, such as pattern collapse and critical dimension issues, due to uncontrolled local fluid dynamics during processing.
Innovation Solution
The method involves determining localized or average fluid velocity of processing liquids on spinning substrates by monitoring light intensity or flow time, using sensors to adjust operational parameters like rotational speed, flow rate, and nozzle position, thereby controlling fluid dynamics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional spin-on processes are used without fluid velocity control, then the process is simple and fast, but local fluid dynamic effects cause pattern collapse and critical dimension issues
Solution Approach 1:
The system employs optical sensors to detect fluid velocity in real-time during the spin-on process and feeds this information back to the controller, which adjusts operational parameters dynamically. This closed-loop feedback mechanism enables precise control of fluid dynamics to prevent pattern collapse while maintaining process efficiency
Solution Approach 2:
The patent replaces direct mechanical control of fluid flow with optical detection and computational analysis. By using light-based sensors to measure fluid velocity and implementing control through software algorithms rather than purely mechanical adjustments, the system achieves higher precision with reduced mechanical complexity
2Reliability
If fluid velocity is monitored and controlled in real-time, then local fluid dynamic effects are mitigated, but measurement and control systems become more complex
Solution Approach 1:
The system introduces optical sensors as intermediary devices that indirectly measure fluid velocity by detecting light transmission changes caused by fluid flow. This intermediary approach allows reliable measurement of fluid dynamics without requiring direct contact with the processing fluid, thereby improving reliability while keeping the measurement system non-intrusive and relatively simple
Solution Approach 2:
Mechanical flow measurement devices are replaced with optical sensing systems. The optical sensors detect fluid velocity through light transmission variations, eliminating the need for complex mechanical flow meters or direct fluid sampling systems, thus reducing measurement system complexity while maintaining high reliability
3Manufacturing precision
If operational parameters are dynamically adjusted based on fluid velocity measurements, then pattern collapse is prevented, but processing time increases
Solution Approach 1:
The system performs fluid velocity measurements and parameter adjustments continuously throughout the spin-on process without interrupting the coating operation. The optical sensing and control systems operate in real-time, allowing continuous monitoring and adjustment that maintains critical dimension control while keeping the processing flow uninterrupted and efficient
Solution Approach 2:
The system performs preliminary measurements of fluid velocity during the initial stages of coating and makes proactive adjustments to operational parameters before pattern collapse can occur. By detecting fluid dynamics early and adjusting parameters in advance, the system prevents defects rather than correcting them later, maintaining both precision and 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 approach effectively mitigates local fluid dynamic effects, improving the local area performance of patterned substrates by dynamically adjusting spin-on process parameters based on real-time fluid velocity measurements.
Implementation Method 1
directing light to the semiconductor substrate, or along the periphery of the semiconductor substrate, while the processing liquid is dispensed onto the first surface of the semiconductor substrate and detecting an intensity of light transmitted through the processing liquid
Implementation Method 2
The spin chuck 110 and drive mechanism 115 are disposed within an opening in the cup 130. The spin chuck 110 supports and rotates (i.e., spins) the semiconductor substrate W about its central normal axis relative to the cup 130, which is stationary. As the spin chuck 110 rotates, the cup 130 captures and collects a majority of the processing liquid, which is ejected from the surface of the semiconductor substrate W by the centrifugal forces generated during rotation of the spin chuck 110.
Data Source
AI summary
Embodiments of processing systems and methods are provided to control operational parameter(s) of a spin-on process based on a fluid height and/or a fluid velocity of a processing liquid dispensed onto a surface of a spinning semiconductor substrate. The disclosed embodiments determine the fluid height and/or the fluid velocity of the processing liquid by: (a) monitoring an intensity of light, which is transmitted through the processing liquid as the processing liquid flows across the surface of the spinning substrate or leaves the periphery of the spinning substrate, or (b) monitoring how long it takes for the processing liquid to flow from a dispensed location to the periphery of the spinning substrate. Once determined, the fluid velocity is used to control one or more operational parameters of a spin-on process.