Silicon Passivating Contact Patterning Without Etching Masks
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Solution Overview
Problem
Current methods for producing passivating contact layers on solar cells, especially for bifacial TOPCon cells, face challenges such as parasitic absorption of light and complex structuring processes, which are costly and unsuitable for large-scale production, particularly when using polycrystalline silicon layers on the front side or rear side of interdigitated back contact (IBC) solar cells.
Innovation Solution
A method for local structuring of silicon layers without an etching mask, achieved by modifying the etching resistance through local thermal treatment or doping, specifically using a laser to increase crystallinity or boron implantation, allowing for mask-free patterning with relaxed alignment requirements, and utilizing the resulting layers as passivating contacts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photolithography or printed mask layers are used for structuring polycrystalline silicon layers, then patterning precision is improved, but device complexity and production cost increase
Solution Approach 1:
The patent extracts and removes the etching mask layer from the conventional photolithography process. Instead of using photolithography to define patterns, the method directly patterns the polycrystalline silicon layer through selective removal of amorphous silicon regions, eliminating the need for separate mask deposition, alignment, and removal steps.
Solution Approach 2:
The patent introduces amorphous silicon as an intermediary layer that is deposited over the polycrystalline silicon layer. This amorphous silicon layer serves as a sacrificial material that can be selectively removed to reveal the underlying polycrystalline silicon patterns, acting as a mediator that simplifies the overall patterning process.
2Reliability
If polycrystalline silicon layers are applied on the front side, then passivation quality is improved, but parasitic absorption increases
Solution Approach 1:
The patent applies local quality by creating spatially varying properties in the silicon layer structure. Polycrystalline silicon regions are formed only in specific locations where passivation is needed, while other regions maintain different properties. The selective removal of amorphous silicon exposes polycrystalline silicon locally at contact regions while maintaining transparency in other areas.
Solution Approach 2:
The patent uses partial action by applying amorphous silicon deposition and selective removal only to the extent necessary for creating the desired pattern. The amorphous silicon layer is deposited uniformly but then selectively removed only in regions where polycrystalline silicon contact is needed, avoiding excessive material deposition that would increase absorption.
3Manufacturing precision
If laser ablation is used for structuring, then manufacturing precision is improved, but energy consumption increases
Solution Approach 1:
The patent replaces the mechanical/thermal laser ablation process with a chemical etching process. Instead of using laser energy to directly remove material, the method uses chemical etchants to selectively remove amorphous silicon regions, substituting a lower-energy chemical process for a high-energy physical process.
Solution Approach 2:
The patent changes the fundamental parameter of the structuring process from thermal/laser-based to chemical-based. By changing the mechanism from laser ablation to chemical etching, the energy consumption is significantly reduced while maintaining or improving patterning precision through controlled chemical reactions.
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 simplifies the patterning process, reduces parasitic absorption, and enables efficient production of solar cells with high acceptance in industry standards, maintaining the integrity of the silicon layer while achieving effective passivation for metal-silicon contacts.
Implementation Method 1
the local modification of the etching resistance is brought about by inducing a local increase in the crystallinity of the silicon layer in the modified regions
Implementation Method 2
local thermal treatment or local doping, specifically using a laser to increase crystallinity
Implementation Method 3
local thermal treatment or local doping, specifically using a laser to increase crystallinity or boron implantation
Data Source
AI summary
Provided are a method for local structuring of a silicon layer, which method comprises a step of local modification of the etching resistance within said silicon layer and a subsequent step of removing unmodified regions of said silicon layer by etching and applications of this method for the production of solar cells.