Wafer Transport with Edge-Free Support Elements
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Solution Overview
Problem
Existing methods for treating plate-shaped process items, such as semiconductor wafers, often result in unintentional treatment of the top side due to capillary effects and surface tension, leading to inefficiencies and potential damage during processing.
Innovation Solution
An apparatus and method utilizing an endless transport means with support elements that move in parallel to the process media level, ensuring the bottom side of the wafer is in contact with the medium without engaging the edges, thereby preventing unintentional top-side treatment by maintaining a sufficient distance and using surface tension for secure holding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If transport rollers are used to convey wafers through liquid media, then the wafers can be transported horizontally through the bath, but the blade effect causes process medium to be conveyed to the top side that is not to be treated
Solution Approach 1:
The invention extracts and eliminates the slide elements that were causing the harmful blade effect. By removing these elements that engaged the edges of the wafers, the patent prevents the conveyance of process medium to the top side while maintaining horizontal transport capability through the liquid bath.
Solution Approach 2:
The transport system is segmented into discrete support elements rather than continuous contact with slide elements. This segmentation allows the wafer to be supported at specific points without edge engagement, preventing the blade effect while maintaining transport functionality.
2Stability of the object's composition
If downholders are used to prevent floating of wafers during two-sided processing, then the wafers remain stable, but mechanical effects on the surface cause spurious effects such as banding
Solution Approach 1:
The invention removes downholders from the transport system. By eliminating these mechanical contact elements, the patent prevents the spurious effects and banding that occur on wafer surfaces while maintaining stability through alternative means such as meniscus formation and controlled support element positioning.
3Ease of operation
If slide elements engage the edges of process items to transport them, then the items can be conveyed through the process medium, but capillary effects and surface tension transport process medium to the top of the process item
Solution Approach 1:
The invention extracts and eliminates the slide elements that engaged the edges of the process items. By removing these elements, the patent prevents the formation of menisci at the edges that would otherwise transport process medium to the top side through capillary effects and surface tension.
4Manufacturing precision
If rollers are used for one-sided treatment, then the bottom side can be processed, but the relative movement between rollers and process item causes blade effect
Solution Approach 1:
The continuous roller contact is segmented into discrete support elements. This segmentation eliminates the relative movement between rolling surfaces and the process item, preventing the blade effect while maintaining the ability to convey the item through the process medium for one-sided treatment.
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 approach effectively reduces capillary effects and surface tension-induced issues, allowing for reliable one-sided processing of the bottom side while preventing top-side treatment, and enables secure support without relative movement, enhancing processing precision and reducing stress on the wafer.
Implementation Method 1
utilizing an endless transport means with support elements that move in parallel to the process media level, ensuring the bottom side of the wafer is in contact with the medium without engaging the edges, thereby preventing unintentional top-side treatment by maintaining a sufficient distance and using surface tension for secure holding
Implementation Method 2
Existing methods for treating plate-shaped process items, such as semiconductor wafers, often result in unintentional treatment of the top side due to capillary effects and surface tension
Data Source
Figure 1
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Figure 2B
AI summary
In apparatuses and methods for treating a plate-shaped process item comprising a bottom side, a top side and edges between the bottom side and the top side with a process medium, a transport means is used, which comprises an endless means with support elements projecting from the same. A bottom side of the plate-shaped process item is supported on support elements of the transport means and the transport means is driven to move the support elements together with the supported plate-shaped process item in parallel to a process media level of a process medium. In a first operating mode, during a movement of the plate-shaped process item in parallel to the process media level, no parts of the transport means engage the edges of the plate-shaped process item.