Wafer Coating Cup Exhaust Layout for Film Uniformity
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Solution Overview
Problem
Existing resist film forming processes face challenges in achieving uniform film thickness on semiconductor wafers due to variations in airflow velocity and mist scattering, leading to non-uniform film thickness and potential contamination from splashed processing liquids.
Innovation Solution
A cup design with separate exhaust passages and a scattered substance collection passage, including a sub-edge ring, is used to manage airflow and collect scattered substances, minimizing airflow velocity variations and preventing liquid splashing, thereby enhancing film uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional cup design is used for resist film formation, then the structure is simple, but the film thickness uniformity deteriorates due to uneven airflow and pressure distribution
Solution Approach 1:
The cup structure is segmented into multiple functional regions: a first exhaust passage for general exhaust, a scattered substance collection passage for collecting mist and scattered materials, and a second exhaust passage for additional exhaust capacity. This segmentation allows each region to handle specific airflow tasks, improving film thickness uniformity by creating more controlled pressure distribution across the wafer surface.
Solution Approach 2:
Different regions of the cup are given different functions and properties. The scattered substance collection passage is positioned to specifically address mist collection needs, while the first and second exhaust passages are strategically located to create optimized airflow patterns. This local differentiation of functions enables precise control over airflow velocity and pressure at different locations, directly improving film thickness uniformity.
2Object-affected harmful factors
If exhaust passages are positioned close to the wafer periphery, then airflow velocity increases, but mist splashing back onto the wafer occurs
Solution Approach 1:
The scattered substance collection passage acts as an intermediary structure between the exhaust passages and the wafer periphery. It collects mist and scattered substances before they can splash back onto the wafer, while still maintaining effective exhaust function. This intermediary structure prevents direct interaction between high-velocity exhaust airflow and the wafer surface, eliminating the harmful splashing effect.
3Manufacturing precision
If airflow velocity is increased to improve exhaust efficiency, then mist collection improves, but film thickness uniformity deteriorates due to excessive velocity at the periphery
Solution Approach 1:
The exhaust system is divided into multiple passages that handle different portions of the exhaust load. The first exhaust passage and second exhaust passage work together to distribute airflow more evenly, while the scattered substance collection passage handles mist collection. This segmentation allows the system to maintain high overall exhaust efficiency while preventing excessive localized velocity that would harm film uniformity.
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 cup design achieves high in-surface uniformity of resist films on wafers by controlling airflow and preventing mist adhesion, reducing film thickness deviations and contamination.
Implementation Method 1
a communication hole provided in the flow passage forming member to allow the scattered substance collection passage and the joint exhaust passage to communicate with each other such that a pressure loss of the communication hole is large as compared to a pressure loss in a gap formed between the first annular member and the substrate
Implementation Method 2
a cup, surrounding a substrate which is disposed in a placing unit and to which a processing liquid is supplied, configured to be evacuated
Data Source
AI summary
A cup includes a flow passage forming member forming a first exhaust passage, a scattered substance collection passage configured to collect a scattered substance from a substrate, and a second exhaust passage in sequence as going upwards; a joint exhaust passage connected to each of the first exhaust passage, the scattered substance collection passage, and the second exhaust passage; a first annular member included in the flow passage forming member, the scattered substance collection passage and the first exhaust passage being formed above and below the first annular member, respectively; and a communication hole provided in the flow passage forming member to allow the scattered substance collection passage and the joint exhaust passage to communicate with each other such that a pressure loss of the communication hole is large as compared to a pressure loss in a gap formed between the first annular member and the substrate.