Wafer Alignment Rollers for Ion Implantation Shadow Masks
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Solution Overview
Problem
The existing ion implant process for selective emitter solar cells is costly and inefficient due to the need for precise alignment of shadow masks over multiple wafers, which requires complex and expensive alignment mechanisms and increased processing time for cleaning.
Innovation Solution
A system that decouples vertical and horizontal alignment of substrates during transport, allowing for precise alignment of multiple wafers simultaneously using a carriage with vertical and horizontal control rollers and claws, enabling alignment at processing stations without requiring precise orientation of the substrate holder during transport.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If shadow mask is placed directly on the wafer and transported together, then alignment precision is improved, but device complexity and processing time increase due to mask placement and cleaning mechanisms
Solution Approach 1:
The alignment function is segmented between the mask (which remains fixed with its alignment features) and the wafer holder (which carries alignment features that engage with the mask). This separation allows the mask to stay stationary while only the wafer holder needs alignment capabilities, reducing overall system complexity.
Solution Approach 2:
Alignment features act as intermediaries between the mask and wafer holder. These features (such as alignment marks or mechanical engagement elements) enable precise alignment without requiring direct contact or complex mechanisms between the mask and wafer, simplifying the transport system.
2Productivity
If complex alignment mechanisms are used to align multiple wafers simultaneously, then productivity is improved, but device complexity and cost increase
Solution Approach 1:
Each wafer holder is equipped with its own alignment features that independently engage with the mask's alignment features. This segmentation allows multiple wafers to be aligned simultaneously through simple, identical mechanisms rather than requiring a complex centralized alignment system.
Solution Approach 2:
The alignment features are replicated on each wafer holder in an identical configuration. This copying approach allows simultaneous alignment of multiple wafers using simple, standardized components rather than complex, customized alignment mechanisms for each position.
3Manufacturing precision
If tight alignment tolerances are required during transport, then manufacturing precision is improved, but device complexity and cost increase
Solution Approach 1:
Alignment features are pre-configured on both the mask and wafer holders before transport begins. This preliminary setup establishes the alignment relationship in advance, allowing the transport system to operate with relaxed tolerances while still achieving precise final alignment.
Solution Approach 2:
The alignment features serve as intermediaries that maintain the precise relationship between mask and wafer during transport. These features absorb any transport inaccuracies, allowing the transport system to have loose tolerances while the alignment features ensure precise final positioning.
Data Source
AI summary
A system for transporting substrates and precisely alignment the substrates to shadow masks. The system decouples the functions of transporting the substrates, vertically aligning the substrates, and horizontally aligning the substrates. The transport system includes a carriage upon which plurality of pedestals are loosely positioned, each of the pedestals includes a base having vertical alignment wheels to place the substrate in precise vertical alignment. Two sidebars are configured to freely slide on the base. Each of the sidebars includes a set of horizontal alignment wheels that precisely align the substrate in the horizontal direction. Substrate support claws are attached to the sidebars in precise alignment to the vertical alignment wheels and the horizontal alignment wheels.