Ceramic Purge Ring Layout for Uniform Wafer-Edge Gas Flow
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Solution Overview
Problem
Existing semiconductor substrate processing technologies face challenges in achieving uniform film deposition due to nonuniform gas flow and charge buildup at the wafer edge, leading to electrical discharges and wafer nonuniformity, especially in PECVD and ALD processes.
Innovation Solution
A ceramic purge ring with radial internal passageways and plenums is designed to deliver inert gas symmetrically around the wafer perimeter, reducing charge buildup and preventing electrical discharges by maintaining uniform gas flow and pressure across the wafer edge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a standard pedestal configuration is used, then the device complexity is low, but film uniformity deteriorates due to nonuniform gas flow and charge buildup at the wafer edge
Solution Approach 1:
The pedestal configuration is segmented into multiple functional zones: a central pedestal body and a surrounding purge ring with distributed gas delivery channels. This segmentation allows independent optimization of gas flow patterns in different regions, enabling uniform film deposition by delivering purge gas specifically to the wafer edge region where charge buildup occurs, without complicating the entire pedestal structure.
Solution Approach 2:
The purge ring introduces local quality by providing targeted gas delivery only at the wafer perimeter region where charge buildup and nonuniformity problems occur. The radial channels and plenums are strategically positioned to deliver inert gas locally at the edge, rather than uniformly across the entire wafer surface, thus improving film uniformity at the problematic edge region without requiring system-wide structural changes.
2Reliability
If purge gas is delivered to reduce charge buildup, then electrical discharge risk is reduced, but gas flow uniformity deteriorates without proper distribution structure
Solution Approach 1:
The gas distribution system is segmented into multiple radial channels and plenums that independently deliver purge gas around the wafer perimeter. This segmentation ensures that gas is delivered at multiple discrete locations, and when combined, creates a uniform annular flow pattern that consistently suppresses charge buildup along the entire wafer edge, preventing electrical discharge while maintaining flow uniformity.
Solution Approach 2:
The plenums act as intermediary chambers that receive purge gas from the radial channels and distribute it uniformly around the wafer perimeter. These plenums serve as mediators between the gas source and the wafer edge, ensuring that the gas flow is evenly distributed in the azimuthal direction, thus maintaining both reliability (discharge prevention) and manufacturing precision (flow uniformity).
3Manufacturing precision
If radial channels and plenums are added to the purge ring, then gas distribution uniformity is improved, but device complexity increases
Solution Approach 1:
The radial channels and plenums are merged into a single integrated purge ring structure rather than being separate components. This merging allows the complex gas distribution network to be compacted into one piece that can be installed as a single unit on the pedestal, reducing assembly complexity while maintaining the uniform gas distribution function provided by the multiple channels and plenums.
Solution Approach 2:
The purge ring structure serves multiple functions simultaneously: it provides structural support, delivers purge gas through radial channels, distributes gas uniformly via plenums, and prevents electrical discharge. This multi-functionality reduces the need for separate components for each function, thereby improving gas distribution uniformity without proportionally increasing device complexity.
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 solution enhances film uniformity and reduces the risk of electrical discharges, improving wafer quality and process efficiency by ensuring consistent gas distribution and pressure across the wafer perimeter.
Implementation Method 1
a purge ring configured with radial internal passageways and/or plenums designed to deliver inert gas through a distribution network
Implementation Method 2
providing localized dilution of a plasma sheath around a perimeter of a wafer using a ceramic purge ring
Data Source
AI summary
A purge ring including a supply port configured for receiving gas. An outer channel is connected to the supply port. An outlet network is configured for an exit flow of the gas proximate to an inner diameter of the purge ring. The purge ring includes a plurality of channels configured for flow of the gas in a radial direction from the outer channel to the outlet network. The purge ring includes a plurality of passageways configured for reduced flow of the gas in the radial direction between the outer channel and the outlet network. The plurality of channels and the plurality of passageways are configured for providing a uniform pressure of the exit flow of the gas across the outlet network circumference.