Wafer Alignment Under Opaque Layers via Transparent Stage
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Solution Overview
Problem
Existing methods for aligning photovoltaic substrates with obscured edges are inefficient, particularly in processes requiring fine pitch alignment, as overhead visual alignment systems lack precision due to the obstruction caused by substantially opaque layers, leading to challenges in accurate substrate positioning during solar cell fabrication.
Innovation Solution
A method and system that involves forming a substantially opaque layer over the substrate edges, illuminating them through a transparent or partially transparent stage, capturing images of the edges using image sensors, and determining the substrate's position relative to the stage using computing devices, enabling precise alignment and processing despite edge obscuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substantially opaque layer is formed over the substrate edges to protect or define boundaries, then the substrate structure is improved, but visual alignment precision deteriorates due to edge obscuration
Solution Approach 1:
The patent introduces a transparent stage as an intermediary between the light source and the substrate edges. This stage transmits light to illuminate the edges from below, allowing image sensors to capture edge images through the stage without being blocked by the opaque layer above the substrate. The intermediary enables visual access to otherwise obscured features.
Solution Approach 2:
The patent transitions from overhead illumination (top-down dimension) to bottom-up illumination through the transparent stage. By changing the dimension of light transmission from above to below the substrate, the system achieves visual access to the substrate edges through the transparent stage, bypassing the obstruction caused by the opaque layer.
2Device complexity
If overhead visual alignment systems are used for substrate alignment, then the system complexity is reduced, but alignment precision deteriorates when edges are obscured
Solution Approach 1:
The patent changes the alignment approach from overhead imaging to bottom-up imaging through the transparent stage. This dimensional change allows standard image sensors to achieve high precision alignment by viewing substrate edges through the transparent stage from below, maintaining system simplicity while overcoming the obscuration problem.
3Measurement precision
If high-precision transport components are used to achieve accurate substrate positioning, then alignment precision is improved, but manufacturing cost increases
Solution Approach 1:
The patent replaces complex mechanical positioning systems with an optical imaging solution. By using the transparent stage to enable precise visual alignment of substrate edges, the system achieves high positioning accuracy through optical means rather than relying on expensive high-precision mechanical transport components.
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 allows for accurate alignment and processing of substrates with obscured edges, improving manufacturing efficiency and reducing the need for high-precision, costly transport components, thereby enhancing the overall equipment effectiveness in solar cell production.
Implementation Method 1
illuminating the covered edges of the substrate with light transmitted through the stage
Data Source
AI summary
Wafer alignment with restricted visual access has been disclosed. In an example, a method of processing a substrate for fabricating a solar cell involves supporting the substrate over a stage. The method involves forming a substantially opaque layer over the substrate. The substantially opaque layer at least partially covers edges of the substrate. The method involves performing fit-up of the substantially opaque layer to the substrate. The method involves illuminating the covered edges of the substrate with light transmitted through the stage, and capturing a first image of the covered edges of the substrate based on the light transmitted through the stage. The method further includes determining a first position of the substrate relative to the stage based on the first image of the covered edges. The substrate may be further processed based on the determined first position of the substrate under the substantially opaque layer.