Tapered Wafer Clamp Ring for Stable Plasma Etching
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Solution Overview
Problem
Thin semiconductor wafers can warp or become non-planar, leading to non-uniform layer thicknesses and etch defects due to horizontal shifting of the wafer clamp ring during plasma treatment processes.
Innovation Solution
The use of a wafer clamp ring with tapered outer support holes reduces horizontal shifting by minimizing tolerance, ensuring stable engagement with the wafer substrate and reducing the likelihood of etch defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a wafer clamp ring is used to flatten and hold the semiconductor wafer substrate, then the wafer substrate is stabilized and flattened, but the clamp ring may shift horizontally due to tolerances between parts, leading to etch defects
Solution Approach 1:
The patent applies curvature by using a spherical ball element within the clamp ring assembly. This ball element interacts with a tapered hole to create a self-centering mechanism that eliminates horizontal shifting while maintaining wafer flatness. The spherical geometry converts linear tolerance issues into rotational degrees of freedom that self-correct positioning errors.
Solution Approach 2:
The patent changes the geometric parameters of the clamp ring by introducing a tapered hole with specific angle requirements (e.g., 15-45 degrees). This parameter change transforms the rigid fixed-position clamp into an adjustable self-aligning mechanism that compensates for manufacturing tolerances and prevents horizontal drift during the etching process.
2Manufacturing precision
If tolerances between parts are reduced to prevent horizontal shifting, then etch uniformity improves, but manufacturing complexity and cost increase
Solution Approach 1:
The spherical ball element serves as a simple yet effective mechanism that replaces complex high-precision machining requirements. Instead of requiring extremely tight tolerances on multiple mating surfaces, the design uses the inherent properties of spherical geometry combined with a tapered hole to achieve self-centering, thereby reducing overall manufacturing complexity.
Solution Approach 2:
The ball element acts as an intermediary component between the clamp ring body and the wafer holding mechanism. This mediator absorbs the tolerance accumulation that would otherwise require extremely precise direct mating between multiple parts, simplifying the overall manufacturing requirements while maintaining etch 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 tapered design of the wafer clamp ring effectively minimizes horizontal movement, resulting in improved etch uniformity and reduced defects along the wafer edge, enhancing the precision of plasma treatment processes.
Implementation Method 1
Plasma treatment is used for various applications in the integrated circuit production process, such as cleaning the wafer or for etching
Data Source
AI summary
Methods and systems for dry etching are disclosed. The system includes a wafer clamp ring having a central opening through which a substrate may be treated and a plurality of smaller, outer support holes for receiving pins from plunger assemblies. The outer support holes are tapered and change in diameter. The tapered shape reduces horizontal shifting of the wafer clamp ring which can occur as the wafer clamp ring is moved up-and-down during operational use. The reduced shifting increases wafer yield along the edges of the wafer.