Shielding Member Geometry for Oxygen Control
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Solution Overview
Problem
In substrate processing for semiconductor and liquid crystal display devices, existing technologies face challenges in maintaining low oxygen concentrations in the atmosphere to prevent oxidation and watermark formation on substrates during processing and drying, as oxygen from the atmosphere dissolves in processing liquids and can cause oxidation and watermark issues.
Innovation Solution
A substrate processing apparatus is designed with a shielding member that discharges inert gas downward between the substrate and the shielding member, and an exhaust unit to reduce oxygen concentration, featuring a specific geometry to enhance gas discharge efficiency and prevent oxygen retention, including a rotating shielding member and an annular clearance with an L-shaped flow passage to minimize oxygen ingress.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a shielding member is used to cover the substrate, then oxygen concentration in the atmosphere is reduced, but the space between substrate and shielding member may retain oxygen if not properly designed
Solution Approach 1:
The shielding member is designed with a specific geometric relationship where the radial distance from the lower end of the inner peripheral surface to the outer peripheral surface of the spin base is at least equal to the vertical distance from the upper surface of the substrate to the opposed surface of the shielding member. This segmentation of spatial dimensions ensures effective oxygen displacement and prevents retention in the gap between substrate and shielding member.
2Object-affected harmful factors
If inert gas is discharged downward from the shielding member, then oxygen is displaced from the space between substrate and shielding member, but improper discharge design may lead to oxygen retention
Solution Approach 1:
The invention controls the geometric parameters of the shielding member and spin base relationship, ensuring the radial distance is at least equal to the vertical distance. This parameter control enables effective inert gas flow and oxygen displacement without requiring complex discharge systems, achieving reliable oxygen removal through simple geometric design.
3Volume of stationary object
If the radial distance from shielding member lower end to spin base outer surface is small, then device size is reduced, but oxygen may be retained in the gap
Solution Approach 1:
Instead of minimizing the radial distance to reduce size, the invention inverts the design approach by ensuring the radial distance is at least equal to the vertical distance. This inverted design priority ensures oxygen-free environment is achieved first, with size optimization considered secondary, thereby preventing oxygen retention through proper geometric configuration.
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 oxygen concentration around the substrate, preventing oxidation and watermark formation, thereby enhancing processing quality by ensuring a low-oxygen environment during both liquid processing and drying.
Implementation Method 1
an inert gas is discharged downward from a downward discharge port provided at the opposed surface of the shielding member. The inert gas discharged from the downward discharge port spreads in a space between the upper surface of the substrate and the opposed surface of the shielding member
Implementation Method 2
an exhaust unit that discharges a gas in the cup to outside of the cup
Data Source
AI summary
A substrate processing apparatus includes a spin chuck, a shielding member disposed over the substrate, a cup surrounding a spin base, an upper gas valve that makes an inert gas be discharged from a downward discharge port of the shielding member, and an exhaust duct that discharges a gas in the cup. The shielding member includes an opposed surface disposed over the substrate and an inner peripheral surface surrounding the substrate. The lower end of the inner peripheral surface of the shielding member is disposed in the periphery of the spin base. The distance in the radial direction from the lower end of the inner peripheral surface of the shielding member to an outer peripheral surface of the spin base is not less than the distance in the vertical direction from an upper surface of the substrate to the opposed surface.