Liquid Control Ring for Bevel Etching
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Solution Overview
Problem
Existing technologies for bevel etching of semiconductor wafers have a narrow process window, leading to inconsistent and non-uniform edge treatment, which affects the accuracy and reproducibility of the bevel etch process, particularly for wider extents of edge etching.
Innovation Solution
A novel ring configuration for the spin chuck with a reduced annular gap and a sloped or vertical surface that allows for a smaller capillary gap, enabling more controlled liquid distribution and renewal, while maintaining a stable gas cushion for wafer support, thereby improving process control and access for gripping mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional ring configuration with a fixed gap is used, then the bevel etch accuracy is maintained within a narrow process window, but the process window itself is narrow leading to inconsistent results
Solution Approach 1:
The ring is configured with a sloped or vertical surface that dynamically adjusts the capillary gap width based on the liquid level and rotational speed. This dynamic gap adjustment allows the system to maintain consistent liquid distribution across a broader range of process conditions, widening the process window while preserving etch accuracy
Solution Approach 2:
The invention changes the geometric parameters of the ring structure by introducing sloped or vertical surfaces instead of parallel surfaces. This parameter change creates a variable capillary gap that adapts to different liquid volumes and rotational speeds, enabling consistent performance across a wider range of process conditions
2Manufacturing precision
If the capillary gap is reduced for better liquid control, then liquid distribution is improved, but the gap may become filled causing liquid to stop flowing inwardly
Solution Approach 1:
The sloped or vertical surface creates a dynamic capillary gap that adjusts its effective width based on liquid level and rotational speed. This prevents the gap from becoming completely filled while maintaining precise liquid control, ensuring continuous liquid flow inwardly throughout the process
Solution Approach 2:
The invention introduces a vertical dimension to the ring surface, creating a three-dimensional capillary gap structure. This vertical component provides an additional degree of freedom for liquid flow, preventing complete gap filling while maintaining precise control over liquid distribution
3Manufacturing precision
If the ring is positioned closer to the wafer for better edge treatment control, then edge etching precision is improved, but access for gripping mechanisms is reduced
Solution Approach 1:
The ring structure is segmented with openings that allow gripping pins to pass through. This segmentation enables the ring to maintain its precise positioning for edge etching while providing clear access paths for gripping mechanisms to load and unload wafers
4Manufacturing precision
If the edge exclusion is increased for better edge treatment, then edge quality is improved, but less surface area is available for chip formation
Solution Approach 1:
The sloped or vertical surface parameters of the ring allow for optimized control of the liquid meniscus position. This enables precise control over the edge exclusion width, achieving high-quality edge treatment while maintaining adequate surface area for chip formation by optimizing the balance between these two parameters
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
This configuration widens the process window for accurate and reproducible edge treatment, allowing for consistent bevel etching across a broader range of wafer sizes and improving liquid renewal and access for handling, reducing the risk of contamination and ensuring adequate surface area for chip formation.
Implementation Method 1
a chuck 11 supports a wafer W by gas flow in the direction of the arrows G, according to the Bernoulli principle. Thus, pins 53 restrain the wafer W laterally, whereas the wafer is held to the chuck by the counterbalancing pressures created by the gas flow beneath the wafer
Implementation Method 2
as etching liquid L is dispensed onto the upwardly facing back side of wafer W, it also flows around the edge of wafer W and is drawn into gap 15 by capillary action
Data Source
AI summary
An apparatus for treating a wafer-shaped article includes a rotary chuck configured to hold a wafer-shaped article of a predetermined diameter such that a surface of the wafer-shaped article facing the rotary chuck is spaced from an upper surface of the rotary chuck. A ring is mounted on the rotary chuck, and includes a first upper surface overlapping an outer peripheral edge of a wafer-shaped article when positioned on the rotary chuck and a second upper surface positioned radially inwardly of the first surface. The second upper surface is elevated relative to the first upper surface, to define an annular gap between the second upper surface and a wafer-shaped article when positioned on the spin chuck that is smaller than a distance between the first upper surface and a wafer-shaped article when positioned on the rotary chuck.