Porous Plug Structure for Stable Argon Backside Gas Delivery
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Solution Overview
Problem
Helium, commonly used as a backside gas in semiconductor processing, is expensive and causes vacuum instability due to its small atomic size, leading to increased leakage and uncontrollable gas rates, necessitating a more economical and stable gas solution.
Innovation Solution
A substrate support assembly with a porous plug, specifically designed with a cross-linked polystyrene material, is used to facilitate the use of argon as a backside gas, which reduces leakage and allows for controlled gas delivery, maintaining substrate temperatures below −20°C while minimizing vacuum instability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If helium is used as backside gas, then cooling effectiveness is improved, but cost increases and vacuum stability deteriorates due to increased leakage
Solution Approach 1:
The patent employs a porous plug made of porous polymer material with specific pore size distribution to control gas flow. The porous structure allows argon gas to pass through while maintaining vacuum stability, resolving the contradiction between effective cooling and vacuum leakage. The porous material acts as a flow restrictor that compensates for argon's larger atomic size compared to helium.
Solution Approach 2:
The patent changes the gas type parameter from helium to argon and adjusts the porous plug parameters (pore size, porosity, length) to optimize performance. By modifying these parameters, the system achieves effective cooling with argon while maintaining vacuum stability, thus resolving the cost and reliability issues associated with helium usage.
2Temperature
If helium is used as backside gas, then cooling performance is improved, but processing cost increases
Solution Approach 1:
The patent replaces expensive helium gas with cheaper argon gas as the backside gas. The porous plug is designed as a disposable or replaceable component made from inexpensive porous polymer material. This substitution significantly reduces processing costs while maintaining effective substrate cooling performance.
Solution Approach 2:
The patent changes the gas type parameter from expensive helium to economical argon, and optimizes the porous plug parameters to ensure equivalent cooling performance. This parameter change achieves cost reduction without sacrificing thermal management effectiveness.
3Force
If chucking voltage is increased to improve substrate holding force, then substrate adhesion is improved, but vacuum leakage increases when using helium
Solution Approach 1:
The patent changes the backside gas parameter from helium to argon and adjusts the porous plug parameters to compensate for the different gas properties. This allows the system to maintain vacuum stability at higher chucking voltages, enabling improved substrate adhesion without the vacuum leakage problems associated with helium.
4Reliability
If a porous plug is designed with larger volume to improve gas flow control, then gas delivery stability is improved, but device complexity increases
Solution Approach 1:
The patent uses a porous plug made of porous polymer material that inherently provides gas flow control through its porous structure. The material's natural porosity and tortuous pore paths provide effective gas delivery control without requiring complex internal structures, thus improving gas delivery stability while minimizing 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 use of argon as a backside gas with the porous plug design reduces vacuum leakage and enables controlled gas delivery, achieving stable processing conditions and cost savings by replacing expensive helium, while maintaining substrate temperatures effectively.
Implementation Method 1
The porous plug includes a material having a porosity
Data Source
AI summary
The disclosure relates to a substrate support assembly for reducing the evacuation time when using argon gas. In one embodiment, a substrate support assembly includes a porous plug within the substrate support assembly. The porous plug includes a first cylindrical section with a first volume and axial length, a second cylindrical section with a second volume and axial length. The first cylindrical section has a larger volume than the second cylindrical section. The first cylindrical section and second cylindrical section have a volume ratio between about 2 and about 12. The first cylindrical section axial length and second cylindrical section axial length have a length ratio between about 2 and about 10.