Bernoulli Substrate Holder Geometry to Block 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 increased gas flow to prevent liquid adhesion can lead to substrate instability.
Innovation Solution
A substrate processing apparatus with a substrate holder featuring a base part with specific surface configurations and support pins, along with a gas supplier that creates a radially outward airflow to enhance substrate holding stability and prevent liquid adhesion, utilizing the Bernoulli and Coanda effects.
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 adhesion of processing liquid to the lower surface is suppressed, but the substrate may be pushed upward and the stability of holding the substrate deteriorates
Solution Approach 1:
The gas supply system is segmented into multiple independent gas supply ports distributed across the support surface. Instead of using a single high-flow gas source, multiple low-flow ports are strategically positioned to create localized gas flows that collectively prevent liquid adhesion while maintaining substrate stability through distributed pressure control.
Solution Approach 2:
Gas flow characteristics are optimized locally at each gas supply port position rather than using uniform high-flow gas across the entire substrate area. Each port delivers gas at a controlled flow rate tailored to its specific location, creating effective liquid barriers only where needed while minimizing overall gas flow and preventing substrate instability.
2Stability of the object's composition
If the Bernoulli effect is utilized to hold the substrate, then the substrate holding stability is improved, but the processing liquid may be drawn under the negative pressure and flow around to the lower surface
Solution Approach 1:
The negative pressure parameters generated by the Bernoulli effect are modified by introducing gas flow counter-pressure. Gas is supplied at controlled rates to create positive pressure zones that counterbalance the negative pressure, preventing processing liquid from being drawn downward while maintaining sufficient holding force through optimized pressure differential control.
Solution Approach 2:
Gas flow acts as an intermediary substance between the Bernoulli effect's negative pressure and the processing liquid. The supplied gas creates a pressure barrier that mediates the interaction, preventing direct contact between the negative pressure field and the processing liquid, thereby stopping liquid adhesion while preserving substrate holding stability.
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 effectively improves substrate stability and suppresses adhesion of processing liquid to the lower surface by optimizing gas flow patterns, ensuring reliable processing without substrate instability.
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 generated by the gas supplier flows along the base surface of the base part outside the outer peripheral edge of the substrate in the radial direction by a Coanda effect, and this prevents adhesion of the processing liquid to the lower surface of the substrate
Data Source
Figure 1
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AI summary
A substrate processing apparatus delivers a gas between a lower surface (92) of a substrate (9) and a base surface (210) of a base part (21) to form an airflow (93) flowing radially outward and to cause a pressure drop in a space (90) between the substrate (9) and the base part (21) by the Bernoulli effect. The base surface (210) includes a second surface (212) sloping upward in a radially outward direction. A third surface (213) slopes downward in a radially outward direction from the outer peripheral edge of the second surface (212). A fourth surface (214) is an annular surface contiguous to the lower edge of the third surface (213). The fourth surface (214) expands radially outward outside the outer peripheral edge of the substrate (9) in the radial direction. Accordingly, it is possible to suppress adhesion of a processing liquid to the lower surface (92) of the substrate (9) and to improve the stability of holding the substrate (9).