Plasma Chamber Flow Equalizer for Uniform Etching
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Solution Overview
Problem
Conventional plasma etch processes in integrated circuit manufacturing suffer from non-uniform etch rates across substrates due to uneven gas distribution, caused by vacuum pumps drawing etching gas towards the exhaust port, leading to performance issues and increased costs.
Innovation Solution
A plasma processing chamber design featuring a lowered flow equalizer and a lower chamber liner, which are electrically coupled to ensure even vacuum draw and plasma distribution by broadening the vacuum path and grounding the flow equalizer to both liners, thereby maintaining uniform etching across the substrate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional plasma etch process is used with a vacuum pump drawing etching gas toward the exhaust port, then the vacuum pumping efficiency is improved, but the etch rate uniformity across the substrate deteriorates
Solution Approach 1:
The flow equalizer is divided into multiple segments or zones along its length, with each segment capable of independent adjustment. This segmentation allows different regions of the chamber to have optimized vacuum draw characteristics, preventing the gas flow from being overly concentrated toward the exhaust port while maintaining overall pumping efficiency.
Solution Approach 2:
The flow equalizer features locally varied geometry, including sections with different widths, heights, or cross-sectional areas positioned at specific locations along its length. These local geometric variations are designed to compensate for the non-uniform gas flow distribution caused by the vacuum pump, ensuring more uniform etching across the substrate surface.
2Device complexity
If the flow equalizer is positioned in a conventional location, then the chamber structure is simpler, but the gas flow distribution and plasma uniformity deteriorate
Solution Approach 1:
The flow equalizer is repositioned to a lower location in the chamber, closer to the substrate surface, creating a new spatial configuration. This dimensional repositioning allows the flow equalizer to more effectively influence the gas flow distribution in the region where plasma generation occurs, improving plasma uniformity without significantly complicating the overall chamber structure.
3Ease of manufacture
If the flow equalizer geometry is not optimized, then the manufacturing cost is lower, but the vacuum draw uniformity and etch quality deteriorate
Solution Approach 1:
The flow equalizer geometry is optimized by adjusting key parameters such as the cross-sectional area, length, and position of the equalizer structure. These parameter changes are calculated to achieve the desired gas flow distribution and vacuum draw uniformity. The optimization process identifies the minimum necessary geometric modifications to achieve improved etch quality while avoiding excessive manufacturing complexity and cost.
Data Source
AI summary
A plasma processing chamber having a lowered flow equalizer and a lower chamber liner. In an etching process, the processing gases may be unevenly drawn from the processing chamber which may cause an uneven etching of the substrate. By equalizing the flow of the processing gases evacuated from the chamber, a more uniform etching may occur. By electrically coupling the flow equalizer to the chamber liners, the RF return path from the flow equalizer may run along the chamber liners and hence, reduce the amount of plasma drawn below the substrate during processing.