Nozzle Ejection Angles for Substrate Cleaning Uniformity
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Solution Overview
Problem
Conventional substrate cleaning apparatuses are inefficient in cleaning the lower surface of substrates, such as semiconductor wafers, as the cleaning liquid often fails to reach the peripheral areas effectively and results in splash-back, reducing treatment efficiency.
Innovation Solution
A liquid treatment apparatus with a substrate retaining unit that rotates the substrate horizontally and a first nozzle with multiple ejection ports arrayed from the central to the peripheral portion of the substrate, ejecting treatment liquid in a direction inclined towards the rotation direction, ensuring uniform coverage and minimizing splash-back.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If cleaning liquid is ejected towards the center of the substrate, then the central area is effectively cleaned, but the peripheral area is not sufficiently cleaned
Solution Approach 1:
The nozzle is divided into multiple ejection ports arranged in a specific pattern (e.g., radial or grid arrangement) across the nozzle surface. Each port ejects liquid at a different angle and position, collectively covering the entire substrate surface including peripheral areas, thus resolving the contradiction between central and peripheral cleaning effectiveness.
Solution Approach 2:
Different regions of the nozzle have different ejection characteristics. The ejection ports are designed with varying angles, positions, and orientations so that ports near the center eject towards the substrate center while ports at the periphery eject towards the substrate edge, ensuring uniform cleaning across all areas.
2Productivity
If treatment liquid is ejected vertically onto the substrate, then direct coverage is achieved, but splash-back occurs reducing treatment efficiency
Solution Approach 1:
The ejection angle parameter is changed from vertical (90 degrees) to inclined angles (e.g., 30-60 degrees relative to the substrate surface). This parameter modification allows the liquid to glide across the substrate surface rather than bouncing back, significantly reducing splash-back and improving treatment efficiency while maintaining effective coverage.
Solution Approach 2:
Instead of ejecting liquid perpendicular to the substrate surface (conventional approach), the nozzle ejects liquid at inclined angles in the direction of substrate rotation. This inverted ejection strategy converts potential splash-back into a beneficial flow that follows the rotation direction, enhancing coverage and reducing waste.
3Device complexity
If a single nozzle is used to treat the substrate, then the device structure is simple, but uniform coverage across the entire surface is difficult to achieve
Solution Approach 1:
The single nozzle is segmented into multiple ejection ports distributed across its surface. This segmentation allows different portions of the substrate to be targeted simultaneously, achieving uniform coverage without requiring multiple separate nozzles or complex mechanical systems. The ports are arranged and angled to ensure overlapping coverage patterns.
Solution Approach 2:
The multi-port nozzle design makes a single device capable of performing multiple functions: it can treat both central and peripheral areas, accommodate different ejection angles, and work effectively with rotating substrates. This universal design replaces what would otherwise require multiple specialized nozzles or complex positioning mechanisms.
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 achieves high uniformity in treating the lower surface of substrates with reduced liquid waste and improved efficiency by ensuring the treatment liquid covers the entire surface without bouncing, enhancing the cleaning process.
Implementation Method 1
each of the first ejection ports is configured to eject the treatment liquid towards the lower surface of the substrate in an ejecting direction which is inclined towards a rotation direction of the substrate rotated by the rotational driving unit
Data Source
AI summary
Disclosed is a liquid treatment apparatus for processing a lower surface of the substrate. The apparatus includes a first nozzle disposed below a lower surface of the substrate retained by the substrate retaining unit to eject a treatment liquid towards the lower surface of the substrate, the first nozzle having a plurality of first ejection ports, which are arrayed from a position opposing a central portion of the substrate retained by the substrate retaining unit to a position opposing a peripheral portion of the substrate retained by the substrate retaining unit. An ejecting direction of the treatment liquid ejected from the first ejection port is inclined towards a rotation direction of the substrate rotated by the rotational driving unit.