Vacuum Pump Layout to Prevent Etch-Deposition Byproduct Buildup
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Solution Overview
Problem
Vacuum pumps in semiconductor processing equipment face issues with undesirable buildup of byproducts from mixing etch and deposition precursors, leading to corrosion and degradation, which reduces their performance and lifetime.
Innovation Solution
The implementation of a vacuum pump system with separate roughing pumps for etch gases and deposition precursors, along with a turbomolecular pump, and the use of a foreline and divert lines to direct gases appropriately, combined with heating of pump surfaces and the application of reactive gases for cleaning to prevent byproduct accumulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single vacuum pump is used to exhaust both etch gases and deposition precursors, then the system is simpler and easier to operate, but byproducts from mixing etch and deposition precursors build up in the pump causing corrosion and degradation
Solution Approach 1:
The vacuum pump system is segmented into multiple independent roughing pumps (first roughing pump for etch gases, second roughing pump for deposition precursors) that operate separately. This segmentation prevents mixing of etch and deposition precursors, eliminating byproduct formation while maintaining system reliability. Each pump handles only its designated gas type, resolving the contradiction between simplicity and reliability.
2Reliability
If separate roughing pumps are used for etch gases and deposition precursors, then byproduct buildup is prevented, but the system complexity increases
Solution Approach 1:
The vacuum pump system incorporates a shared turbomolecular pump that serves both the first roughing pump (etch gases) and second roughing pump (deposition precursors). This multi-functionality reduces overall system complexity while maintaining the benefits of separate roughing pumps. The common turbomolecular pump handles high vacuum for both gas types, simplifying the architecture compared to having completely separate pump systems.
3Ease of operation
If a common foreline is used to receive both etch gases and deposition precursors, then the system is easier to operate, but it allows mixing of gases that forms corrosive byproducts
Solution Approach 1:
The exhaust system is segmented into separate forelines: a first foreline for etch gases connected to the first roughing pump, and a second foreline for deposition precursors connected to the second roughing pump. This segmentation prevents gas mixing and byproduct formation while maintaining ease of operation through dedicated pathways for each gas type.
Solution Approach 2:
The system introduces a divert line with a divert valve as an intermediary mechanism that can redirect deposition precursors from the second foreline to the first foreline when needed. This mediator allows flexible gas routing without direct mixing, enabling the system to adapt to different operational requirements while preventing harmful byproduct formation.
4Ease of manufacture
If the vacuum pump processes both etch and deposition gases together, then cleaning and maintenance is simpler, but byproduct accumulation degrades pump performance
Solution Approach 1:
The pump system is segmented into separate roughing pumps for etch and deposition gases, which reduces byproduct accumulation and extends pump lifespan. This segmentation decreases maintenance frequency and complexity, ultimately improving productivity by reducing downtime associated with pump maintenance and replacement.
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 configuration effectively prevents deposition byproduct buildup, extends the lifespan of vacuum pumps, and maintains the utility of using etch and deposition gases together in a single processing chamber by ensuring efficient separation and cleaning of gases.
Implementation Method 1
a turbomolecular pump, the turbomolecular pump being in fluid communication with one or both of the first roughing pump and the second roughing pump
Implementation Method 2
heating of pump surfaces and the application of reactive gases for cleaning to prevent byproduct accumulation
Implementation Method 3
the application of reactive gases for cleaning to prevent byproduct accumulation
Data Source
AI summary
A processing chamber such as a plasma etch chamber can perform deposition and etch operations, where byproducts of the deposition and etch operations can build up in a vacuum pump system fluidly coupled to the processing chamber. A vacuum pump system may have multiple roughing pumps so that etch gases can be diverted a roughing pump and deposition precursors can be diverted to another roughing pump. A divert line may route unused deposition precursors through a separate roughing pump. Deposition byproducts can be prevented from forming by incorporating one or more gas ejectors or venturi pumps at an outlet of a primary pump in a vacuum pump system. Cleaning operations, such as waferless automated cleaning operations, using certain clean chemistries may remove deposition byproducts before or after etch operations.