Curved Guide Unit Prevents Mist Reattachment
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Solution Overview
Problem
In semiconductor wafer photolithography, high substrate rotation speeds during bevel cleaning lead to reverse gas flow and mist reattachment to the wafer, causing pattern defects, and existing exhaust systems are complex and environmentally costly due to increased power usage.
Innovation Solution
A solution treatment apparatus with a treatment cup design featuring a lower guide unit extending downward and an upper guide unit with a curved inner surface forming an annular flow path, which reduces gas flow speed and prevents reverse flow, allowing for high substrate rotation speeds with low exhaust rates during bevel cleaning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the substrate rotation speed is increased during bevel cleaning, then the cleaning solution can be pushed up to the peripheral edge position, but reverse gas flow occurs causing mist reattachment to the substrate
Solution Approach 1:
The upper guide unit is designed with a curved inner peripheral surface that bulges outward, creating a smooth curved flow path for the gas. This curvature prevents sharp edges and abrupt flow direction changes that would cause turbulence and reverse flow, thereby preventing mist reattachment to the substrate while maintaining high rotation speeds for effective bevel cleaning
2Reliability
If high exhaust rate is used to collect mist during resist solution discharge, then mist collection is effective, but power usage increases and environmental impact worsens
Solution Approach 1:
The curved inner peripheral surface of the upper guide unit converts the harmful high-speed gas flow that causes reverse flow and mist scattering into a beneficial smooth downward flow. The curvature guides the gas flow to follow the contour, transforming the potentially harmful kinetic energy into useful downward motion that effectively collects mist without requiring high exhaust rates, thus reducing power consumption
3Manufacturing precision
If the annular flow path space is narrowed to uniformly exhaust gas, then exhaust uniformity improves, but reverse flow increases when substrate rotates at high speed
Solution Approach 1:
The curved inner peripheral surface creates a flow path that naturally guides gas downward along the curve, maintaining stable flow direction even in a narrow annular space. The curvature prevents the gas from reversing direction by providing a smooth contour that the flow follows, thus maintaining both exhaust uniformity and flow stability at high rotation speeds
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 reduces mist reattachment to the substrate and simplifies exhaust system control by maintaining low exhaust rates during high rotation speeds, minimizing pattern defects and environmental impact.
Implementation Method 1
an upper guide unit which forms a lower annular flow path between the upper guide unit and the lower guide unit for guiding downward together with a gas flow a treatment solution scattering from the substrate
Implementation Method 2
a treatment solution scattering from the substrate held on the substrate holding unit
Data Source
AI summary
The invention includes a lower guide unit which obliquely extends downward to an outside from a position closely opposed to a peripheral edge portion of a rear surface of the substrate held on the substrate holding unit, and is formed in an annular shape in a circumferential direction of the substrate; and an upper guide unit which has an upper end surface located at a substantially same height as a front surface of the substrate held on the substrate holding unit, forms a lower annular flow path between the upper guide unit and the lower guide unit for guiding downward together with a gas flow a treatment solution scattering from the substrate, is formed in an annular shape opposed to the lower guide unit to surround an outside lower region of the substrate, and has an inner peripheral surface having a longitudinal-sectional shape curved to bulge outward and extending downward.