Dual Boat Substrate Holder for Polysilicon Film Sticking Prevention
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Solution Overview
Problem
Substrates tend to stick to the claws of a boat during film forming processes, especially when thick polysilicon films are formed, despite existing techniques to reduce contact area by forming fine irregularities on the claws.
Innovation Solution
A substrate holder with a dual boat structure, where a first boat holds substrates in a shelf-like manner and a second coaxial boat is movable up and down relative to the first boat, allowing substrates to be delivered between the two boats during processing to prevent sticking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If substrates are held on a single boat during film forming, then the structure is simple, but substrates stick to the boat when thick polysilicon films are formed
Solution Approach 1:
The single boat structure is segmented into two separate boats (first boat and second boat). Each boat has its own support columns and placement surfaces, allowing substrates to be transferred between them. This segmentation prevents substrate sticking by eliminating continuous contact with a single boat surface during thick film formation.
Solution Approach 2:
The system introduces dynamic movement between the first and second boats during the film forming process. The boats can move relative to each other vertically, enabling substrates to be delivered from one boat to the other. This dynamic transfer prevents substrates from remaining stationary on one boat surface, thereby preventing sticking.
2Reliability
If substrates are continuously moved between two boats, then substrate sticking is prevented, but the device complexity increases
Solution Approach 1:
The first and second boats are arranged coaxially with nested positioning. The boats share a common central axis and can be vertically positioned relative to each other within the same spatial envelope. This nesting arrangement minimizes the overall space required and reduces structural complexity compared to completely separate boat systems.
Solution Approach 2:
Both the first boat and second boat serve multiple functions: they each provide support columns for substrate placement, act as movable platforms for substrate transfer, and can independently hold substrates during different phases of the film forming process. This multi-functionality reduces the need for additional specialized components.
3Device complexity
If a single boat is used, then the structure is straightforward, but substrate integrity deteriorates due to sticking
Solution Approach 1:
The system performs preliminary substrate transfer to the second boat before thick polysilicon film formation begins. By proactively moving substrates to a fresh boat surface before sticking can occur, the system prevents substrate integrity deterioration rather than attempting to correct it after the fact.
Solution Approach 2:
The second boat acts as an intermediary platform between the first boat and the final substrate destination. During thick film formation, substrates are delivered to the second boat which serves as a temporary holding platform, preventing direct continuous contact between substrates and the first boat surface that would cause sticking and integrity loss.
Data Source
AI summary
A substrate holder includes a first boat configured to hold a substrate in a shelf-like manner, and a second boat coaxial with the first boat and provided to move up and down relative to the first boat. The second boat holds a substrate in a shelf-like manner. The first boat includes a first bottom plate and a first ceiling plate provided to face each other, a first support column connecting the first bottom plate and the first ceiling plate to each other, and a first placement surface on which the substrate is placed. The second boat includes a second bottom plate and a second ceiling plate provided to vertically face each other, a second support column connecting the second bottom plate and the second ceiling plate, and a second placement surface on which the substrate is placed. The second ceiling plate overlaps the first ceiling plate in a plan view.