Symmetric Etching Chamber Pump Layout to Block Gas Backstreaming
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Solution Overview
Problem
Current semiconductor manufacturing processes face challenges in achieving uniform etching across substrates with high aspect ratios and varying feature densities due to non-symmetrical processing chamber designs, leading to inhomogeneities in plasma flow and etching results.
Innovation Solution
A symmetrical processing chamber design with a turbomolecular pump system that includes a rotor core with a through passage and spiral grooves on the stem or core to counter backstreaming gas, ensuring uniform gas flow and independent pressure regions within the chamber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-symmetrical processing chamber design is used, then the pump can be installed at the bottom of the chamber, but this causes inhomogeneities in plasma flow and etching results
Solution Approach 1:
The patent applies asymmetry by intentionally designing a non-symmetrical processing chamber configuration where the pump is positioned at the bottom and the gas port is positioned at the top. This asymmetric layout is accepted and optimized to achieve the desired plasma flow patterns and etching uniformity through careful positioning of components rather than attempting symmetric design.
Solution Approach 2:
The patent addresses the contradiction by transitioning to a vertical dimensionality arrangement where the pump is positioned at the bottom and the gas port at the top, creating a vertical plasma flow path. This dimensional arrangement allows the pump to be installed at the bottom while maintaining etching uniformity through the vertical configuration of gas flow and plasma generation.
2Reliability
If the stem passes through the core of the pump, then the chamber can be sealed, but gas may backstream from the exhaust to the processing chamber
Solution Approach 1:
The patent introduces a pump screen as an intermediary component positioned between the processing chamber and the pump inlet. This screen acts as a mediator that allows the stem to pass through for sealing purposes while preventing gas backstreaming from the pump exhaust to the processing chamber, thus resolving the contradiction between sealing reliability and preventing harmful backstreaming.
Solution Approach 2:
The patent extracts the harmful backstreaming gas flow by positioning the pump screen to block the direct path of exhaust gas returning to the chamber. The screen selectively removes the harmful backstreaming effect while maintaining the necessary sealing function of the stem passing through the core.
3Productivity
If the pump is positioned at the bottom to remove gas, then gas evacuation is efficient, but the design becomes non-symmetrical causing inhomogeneous plasma flow
Solution Approach 1:
The patent employs vertical dimensionality by positioning the pump at the bottom and gas port at the top, creating a vertical evacuation path that maintains high productivity. The vertical arrangement allows efficient gas removal while the strategic positioning of the gas port and plasma generation elements compensates for the asymmetric layout to achieve uniform plasma flow across the substrate.
Solution Approach 2:
The patent segments the processing chamber into distinct functional zones: a bottom region for pump installation and gas evacuation, a middle region for substrate processing, and a top region for gas introduction. This segmentation allows each zone to perform its function optimally, maintaining both evacuation efficiency and plasma uniformity through zoned functional separation.
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 enhances etching uniformity and reduces backstreaming, resulting in improved control over etching processes and reduced inhomogeneities across the substrate, even at high aspect ratios and varying feature densities.
Implementation Method 1
one or more spiral grooves are formed in the stem opposing an inner surface of the core, each spiral groove having dimensions to provide pumping action to counter back streaming of the gas from an exhaust of the pump to the processing chamber in an intermediate and viscous flow regime inside a gap between the stem and the core
Data Source
AI summary
A processing chamber and method of etching a semiconductor substrate are presented. The processing chamber is symmetric, with the centerlines of a chuck and stem of a stage to retain a semiconductor substrate aligned with a centerline of a passage in a core of a pump used to evacuate the processing chamber and with a centerline of a gas port through which gas is introduced to the processing chamber. The stem extends through the passage and a spiral groove is formed in the passage in only one of the stem or an inner surface of the core to provide pumping action to counter back streaming of the gas from an exhaust of the pump in an intermediate and viscous flow regime inside a gap between the stem and the core.