Recessed Carrier Ring for PECVD Fence Management
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Solution Overview
Problem
In PECVD deposition processes, the formation of a dielectric deposition fence outside the wafer edge leads to particle issues and increased manufacturing costs due to frequent chamber openings or plasma clean steps to address the fence buildup, which reduces tool availability and increases costs.
Innovation Solution
A PECVD deposition chamber with a recessed outer surface on the pedestal and wafer carrier ring design, which increases the distance between the deposition fence and the robot slider, allowing for more wafers to be processed before cleaning, thereby extending tool availability and reducing manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If deposition is extended beyond the wafer edge to provide uniform thickness, then film uniformity is improved, but a deposition fence forms on the carrier ring causing particle issues and requiring frequent cleaning
Solution Approach 1:
The harmful deposition fence is extracted from the problematic location by providing a recessed outer surface on the carrier ring. The recessed portion (0.020-0.040 inches deep) captures the deposited dielectric material away from the robot slider path, eliminating particle generation while preserving the beneficial deposition fence for maintaining film uniformity across the wafer edge.
Solution Approach 2:
The solution introduces a vertical dimension (depth) to the carrier ring structure by creating a recessed outer surface. This vertical displacement moves the deposition fence from a horizontal plane that interferes with the robot slider to a lower plane that does not interfere, allowing the deposition fence to serve its useful purpose without causing harmful effects.
2Reliability
If the deposition fence is removed by opening the chamber or running plasma clean steps, then particle issues are resolved, but tool availability decreases and manufacturing cost increases
Solution Approach 1:
The recessed carrier ring structure is prepared in advance to prevent the deposition fence from reaching a harmful thickness. By designing the carrier ring with a built-in recess of appropriate depth, the system pre-establishes a containment structure that delays the need for cleaning operations, allowing continuous processing without frequent interruptions for chamber opening or plasma clean steps.
3Ease of operation
If the deposition fence becomes thick enough to contact the robot slider, then transfer operations are disrupted, but pieces break off and redeposit on wafers causing yield depression
Solution Approach 1:
The recessed carrier ring structure acts as a protective cushion that absorbs the deposited dielectric material before it can reach harmful thicknesses. The recessed portion (0.020-0.040 inches deep) provides a buffer zone that accommodates the deposition fence, preventing it from contacting the robot slider and subsequently breaking off to contaminate wafers.
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 design significantly increases the number of wafers that can be processed between chamber cleans, reducing manufacturing costs and maintaining uniform film thickness across the wafer edges, thus enhancing the efficiency and cost-effectiveness of the deposition process.
Implementation Method 1
One technique used to deposit dielectric films at temperatures less than approximately 550 C is PECVD (plasma-enhanced chemical vapor deposition)
Data Source
AI summary
A method for processing a semiconductor wafer in a PECVD deposition chamber with a circular pedestal and a recessed portion formed around the outer top surface of the pedestal. The method may include using a circular wafer carrier ring with a recessed portion.