Wafer Cleaning Gas Barrier Layout for Edge Backflow Control
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Solution Overview
Problem
In existing backside clean processes, reducing the N2 flow rate to prevent acid erosion on the front side of a wafer leads to acid fluid backflow, causing edge residue and particulate contamination defects.
Innovation Solution
Adjust the distance between the side not to be cleaned and the chuck surface, and configure a protective gas flow rate and distribution to prevent backflow without reducing the gas flow rate, using pins of varying lengths and a targeted gas hole distribution to maintain pattern integrity and protect the edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the N2 flow rate is reduced to protect the pattern structure, then the pattern collapse is prevented, but the cleaning fluid flows back to the front side causing acid erosion and edge residue
Solution Approach 1:
The patent introduces a vertical distance dimension (first distance) between the wafer front side and chuck surface, transforming the problem from a 2D flow rate control to a 3D spatial control. By adjusting this vertical dimension, the protective gas forms a more effective barrier that prevents cleaning fluid backflow while maintaining pattern structure stability.
Solution Approach 2:
The patent changes multiple parameters simultaneously: increases the first distance from wafer to chuck surface, optimizes the first flow rate of protective gas, and configures gas hole distribution. These parameter changes work together to create a protective gas barrier that prevents acid erosion without causing pattern collapse.
2Object-affected harmful factors
If the N2 flow rate is maintained at high level to prevent backflow, then acid erosion is prevented, but the pattern structure on the front side collapses
Solution Approach 1:
The patent applies local quality by configuring gas holes in specific distributions (concentric circles, radial patterns) to create localized high-velocity gas jets at the wafer edge region. This provides enhanced protective gas flow exactly where backflow occurs, allowing lower overall flow rates that prevent pattern collapse while still preventing acid erosion at critical locations.
Solution Approach 2:
By introducing the vertical distance parameter (first distance) and configuring gas hole distributions in multiple dimensions, the patent creates a three-dimensional protective gas barrier. This spatial configuration allows the protective gas to effectively counteract cleaning fluid backflow at the wafer edge without requiring uniformly high flow rates across the entire wafer surface, thus preventing pattern collapse.
3Productivity
If the distance between wafer and chuck is reduced to improve cleaning efficiency, then cleaning speed increases, but the pattern structure becomes vulnerable to collapse
Solution Approach 1:
The patent applies local quality by concentrating gas holes in the edge region (outermost circle configuration) to provide localized protective gas flow exactly where the pattern structure is most vulnerable. This allows the wafer to be positioned closer to the chuck for efficient cleaning while the targeted gas flow protects the pattern structure at the edge region from collapse.
4Manufacturing precision
If the gas hole distribution is uniform across the chuck, then the protective gas flow is evenly distributed, but the edge region of the wafer receives insufficient protection
Solution Approach 1:
The patent applies local quality by configuring gas holes with non-uniform distribution, specifically concentrating more gas holes in the edge region (outermost circle with higher density). This creates localized high-velocity gas jets at the wafer edge where cleaning fluid backflow and acid erosion are most severe, providing enhanced protection exactly where needed while maintaining overall process precision.
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
Prevents pattern collapse and edge erosion by independently adjusting pressure and flow rate, enhancing wafer protection and improving product yield.
Implementation Method 1
flowing a protective gas from a gas hole of the chuck to the side not to be cleaned
Implementation Method 2
introducing a cleaning fluid above the side to be cleaned to implement the wafer cleaning
Data Source
AI summary
The present disclosure discloses a wafer cleaning method including: providing a wafer; placing the wafer on a chuck in a cleaning chamber, and configuring a first distance between the side not to be cleaned and the surface of the chuck; flowing a protective gas, and configuring a first flow rate of the protective gas; and introducing a cleaning fluid above a side to be cleaned. The magnitude of the first flow rate is configured so that the cleaning fluid does not flow back from the edge of the wafer to the side not to be cleaned. The first distance is configured according to a first pressure formed by the protective gas of the first flow rate on the side not to be cleaned, the first pressure is less than a minimum pressure that causes a pattern structure on the side not to be cleaned of the wafer to collapse.