Bernoulli Substrate Holder Geometry to Prevent Liquid Adhesion
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Solution Overview
Problem
Conventional substrate processing methods using Bernoulli chucks face challenges in maintaining substrate stability while preventing processing liquid from adhering to the lower surface, as increasing gas flow to prevent liquid flow can destabilize the substrate.
Innovation Solution
A substrate processing apparatus with a substrate holder that includes a base part with specific surface configurations and a gas supplier to create a radial airflow, utilizing the Bernoulli and Coanda effects to enhance substrate holding stability and prevent liquid adhesion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the flow rate of gas supplied to the space between the substrate and the support is increased to prevent processing liquid from flowing around to the lower surface, then the processing liquid adhesion is suppressed, but the substrate may be pushed upward and the stability of holding the substrate deteriorates
Solution Approach 1:
The gas supply is segmented into multiple regions: a first gas supply region with a first flow rate and a second gas supply region with a second flow rate. This segmentation allows different gas flow rates to be applied to different areas, preventing processing liquid adhesion while maintaining substrate holding stability through localized control of gas flow.
Solution Approach 2:
Different regions of the substrate support structure are given different local properties: the first gas supply region has higher gas flow rate to prevent liquid adhesion, while the second gas supply region has lower gas flow rate to maintain holding stability. This local differentiation resolves the contradiction by applying appropriate gas flow rates to appropriate locations.
2Object-affected harmful factors
If the gas flow rate is increased to prevent processing liquid from reaching the lower surface, then liquid processing quality is improved, but energy consumption increases due to higher gas supply requirements
Solution Approach 1:
The gas supply system is divided into multiple regions with different flow rates. The first gas supply region uses higher flow rate only where needed to prevent liquid adhesion, while the second gas supply region uses lower flow rate, thereby reducing overall energy consumption compared to uniform high flow rate supply.
Solution Approach 2:
Instead of applying high gas flow rate uniformly across the entire substrate area, the invention applies excessive gas flow rate (first flow rate) only to the first gas supply region where it is necessary to prevent liquid adhesion, and uses moderate flow rate (second flow rate) in the second gas supply region, optimizing energy efficiency.
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
The apparatus improves substrate stability by effectively preventing processing liquid from adhering to the lower surface, ensuring secure holding and reducing turbulence, while maintaining efficient liquid processing.
Implementation Method 1
a gas supplier that delivers a gas between the lower surface of the substrate and the base surface of the base part to form an airflow flowing radially outward and to cause a pressure drop in a space between the substrate and the base part by a Bernoulli effect
Implementation Method 2
the airflow flowing along the base surface prevents processing liquid from adhering to the lower surface of the substrate by a Coanda effect
Data Source
AI summary
A substrate processing apparatus delivers a gas between a lower surface of a substrate and a base surface of a base part to form an airflow flowing radially outward and to cause a pressure drop in a space between the substrate and the base part by the Bernoulli effect. The base surface includes a second surface sloping upward in a radially outward direction. A third surface slopes downward in a radially outward direction from the outer peripheral edge of the second surface. A fourth surface is an annular surface contiguous to the lower edge of the third surface. The fourth surface expands radially outward outside the outer peripheral edge of the substrate in the radial direction. Accordingly, it is possible to suppress adhesion of a processing liquid to the lower surface of the substrate and to improve the stability of holding the substrate.