Leave-In Etch Mask for Solar Cell Foil Patterning
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Solution Overview
Problem
The existing methods for fabricating solar cells face challenges in efficiently patterning thick metal foils, such as aluminum, due to the limitations of traditional etch resist materials and the complexity of masking both sides of metal foil tabs, which affects the manufacturing efficiency and cost-effectiveness of solar cells.
Innovation Solution
The approach involves using a leave-in etch mask with a wet etchant-resistant polymer layer and laser ablation to pattern the metal foil, followed by wet etching, which reduces the etch time and allows for cost-effective coating and patterning of the entire wafer and cell assembly, enabling efficient isolation of metal finger structures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional etch resist materials and masking methods are used to pattern thick metal foils, then the metal foil can be patterned, but the etch time is excessive and manufacturing efficiency is reduced
Solution Approach 1:
The method performs preliminary grooving of the metal foil using a laser beam before the etching process. This pre-processing step creates initial channels or grooves in the thick metal foil, which significantly reduces the subsequent etch time required to complete the patterning, thereby resolving the contradiction between achieving precise patterning and reducing etch time
Solution Approach 2:
The invention replaces traditional mechanical or chemical masking methods with a laser-based grooving approach. The laser beam directly ablates or melts the metal foil to create grooves, substituting complex masking procedures with a more efficient thermal processing method that reduces overall process time while maintaining patterning precision
2Reliability
If traditional masking methods are used for both sides of metal foil tabs, then complete coverage is achieved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The invention extracts or removes the requirement for complex dual-sided masking by implementing grooving on only one side of the metal foil. The laser grooving process is applied selectively to the side that requires patterning, eliminating the need for cumbersome masking operations on both sides while still achieving the desired metal foil patterning and maintaining reliability
Solution Approach 2:
Instead of using masking to protect areas that should not be etched, the invention inverts the approach by using laser grooving to directly create the desired pattern on one side of the foil. This reversal of the traditional masking paradigm simplifies the process by eliminating the need for complex masking arrangements while achieving the same patterning result
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 method enhances the manufacturing efficiency and cost-effectiveness of solar cells by reducing etch time and avoiding the use of hazardous solvents, while maintaining the integrity of the solar cell structure and performance.
Implementation Method 1
A laser beam is used to groove only a portion of the metal foil
Implementation Method 2
A laser beam is used to groove only a portion of the metal foil
Implementation Method 3
The metal foil is wet etched to isolate the metal finger structures
Data Source
AI summary
Approaches for fabricating foil-based metallization of solar cells based on a leave-in etch mask, and the resulting solar cells, are described. In an example, a solar cell includes a substrate having a back surface and an opposing light-receiving surface. A plurality of alternating N-type and P-type semiconductor regions is disposed in or above the back surface of the substrate. A conductive contact structure is disposed on the plurality of alternating N-type and P-type semiconductor regions. The conductive contact structure includes metal foil portions in alignment with corresponding ones of the alternating N-type and P-type semiconductor regions. A patterned wet etchant-resistant polymer layer is disposed on the conductive contact structure. Portions of the patterned wet etchant-resistant polymer layer are disposed on and in alignment with the metal foil portions.