Segmented Shadow Ring for Wafer Edge Deposition Uniformity
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Solution Overview
Problem
Existing shadow ring technologies for semiconductor wafers fail to achieve uniform deposition at the edge and bevel, leading to non-uniformity and particle contamination, as they reduce the useful surface area and can misalign, affecting heat distribution and plasma interaction.
Innovation Solution
A modified shadow ring with adjustable parameters such as a recessed slot, varying material composition, and shape modifications to control heat and plasma effects, ensuring improved deposition uniformity and reduced particle contamination by optimizing the edge exclusion area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a shadow ring is used to mask the wafer perimeter, then deposition uniformity at the edge is improved, but the useful surface area is reduced
Solution Approach 1:
The shadow ring is segmented with radial slots that divide the continuous masking structure into discrete segments. This segmentation allows process gases to flow through the slots and reach the wafer edge regions that would otherwise be completely blocked, maintaining deposition uniformity while preserving more of the wafer's useful surface area.
Solution Approach 2:
The shadow ring implements local quality by providing different masking characteristics at different angular positions around the wafer. The radial slots create regions of varying gas flow and deposition, allowing the shadow ring to selectively control deposition in specific zones rather than uniformly blocking the entire perimeter, thus optimizing both edge uniformity and useful area.
2Manufacturing precision
If the shadow ring is positioned closer to the wafer edge, then edge deposition control is improved, but alignment difficulty increases
Solution Approach 1:
The shadow ring incorporates multiple functional features including alignment pins, radial slots, and a beveled inner surface in a single component. The alignment pins provide automatic mechanical registration with the wafer, eliminating the need for complex external alignment procedures and making the shadow ring universally applicable across different wafer processing scenarios.
Solution Approach 2:
The shadow ring includes pre-formed alignment pins and predefined radial slot patterns that are manufactured into the component before use. These preliminary features ensure proper positioning and gas flow distribution without requiring complex alignment procedures during wafer processing, thereby improving both edge deposition control and alignment ease.
3Object-affected harmful factors
If the shadow ring masks the wafer perimeter, then particle contamination is reduced, but heat distribution to the edge is reduced
Solution Approach 1:
The radial slots in the shadow ring maintain continuous gas flow paths from the chamber center to the wafer edge regions. This continuity ensures that process gases and thermal energy can reach the edge zones throughout the deposition process, preventing the shadow ring from becoming a complete thermal barrier while still providing particle contamination protection through selective masking.
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 modified shadow ring enhances deposition uniformity at the wafer edge, minimizing unwanted particle generation and increasing the useful surface area by tailoring thermal and plasma interactions, thus improving the quality of deposited films.
Implementation Method 1
a shadow ring which essentially masks or shields a portion of the perimeter of the wafer from the process gasses
Implementation Method 2
the shadow ring itself affects the deposition uniformity in the region of the wafer's edge by drawing heat (from both resistive and plasma type heat sources) away from the edge of the wafer
Implementation Method 3
In plasma enhanced CVD (PECVD), one or more RF electrodes are provided to energize a gas to form a plasma. The heat to activate the precursors and form the thin film layer is provided by the plasma.
Implementation Method 4
one or more RF electrodes are provided to energize a gas to form a plasma
Implementation Method 5
a precursor gas reacts on the heated wafer surface to deposit a thin layer thereon
Implementation Method 6
Thermal and plasma enhanced chemical vapor deposition (CVD) are some of a number of processes used to deposit thin films of material on semiconductor wafers or wafers
Data Source
AI summary
Embodiments of the invention contemplate a shadow ring that provides increased or decreased and more uniform deposition on the edge of a wafer. By removing material from the top and/or bottom surfaces of the shadow ring, increased edge deposition and bevel coverage can be realized. In one embodiment, the material on the bottom surface is reduced by providing a recessed slot on the bottom surface. By increasing the amount of material of the shadow ring, the edge deposition and bevel coverage is reduced. Another approach to adjusting the deposition at the edge of the wafer includes increasing or decreasing the inner diameter of the shadow ring. The material forming the shadow ring may also be varied to change the amount of deposition at the edge of the wafer.