Solar Cell Emitter Fabrication via Self-Aligned Stencil Mask
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Solution Overview
Problem
Current solar cell fabrication techniques face challenges in increasing efficiency and reducing costs, particularly in the alignment and removal of non-implanted polycrystalline silicon regions during the production of high-performance back contact solar cells, which requires cost-effective and high-throughput ion implant systems.
Innovation Solution
The use of self-aligned implant and cap processes involving silicon stencil masks for patterned ion implants and capping layers, allowing for simultaneous alignment and selective removal of non-implanted regions, thereby reducing process steps and thermal budget while maintaining high efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional alignment and removal processes are used for non-implanted polycrystalline silicon regions, then manufacturing precision can be maintained, but device complexity and production time increase
Solution Approach 1:
The patent combines the alignment and removal processes into a single self-aligned implant and cap process. The stencil mask serves dual purposes: it defines the implantation pattern and simultaneously serves as the cap structure that protects implanted regions during subsequent processing. This merging eliminates separate alignment and removal steps, reducing process complexity while maintaining manufacturing precision.
Solution Approach 2:
The stencil mask is prepared in advance with pre-defined patterns that will serve as both the implantation template and the protective cap. By performing the masking and patterning operations before implantation, the system establishes the alignment framework beforehand, eliminating the need for subsequent realignment operations and reducing overall process complexity.
2Manufacturing precision
If multiple separate process steps are used for implantation and capping, then manufacturing precision can be maintained, but productivity decreases
Solution Approach 1:
The patent merges implantation and capping into a single integrated process step. The stencil mask remains in place during both operations, allowing implantation to occur through the mask openings while the mask simultaneously serves as the cap structure. This eliminates the need for separate capping steps and intermediate handling, thereby increasing manufacturing throughput while maintaining alignment precision through the consistent use of the same mask structure.
Solution Approach 2:
The stencil mask remains continuously functional throughout both implantation and capping operations without being removed or replaced. This continuous presence of the mask ensures uninterrupted alignment reference and eliminates idle time between process steps, thereby improving productivity while maintaining manufacturing precision through unbroken process continuity.
3Manufacturing precision
If conventional implantation methods are used, then manufacturing precision can be maintained, but loss of time increases due to multiple process steps
Solution Approach 1:
The stencil mask is prepared in advance with all necessary pattern definitions before implantation begins. This preliminary preparation establishes the complete alignment framework and protective structure in one operation, eliminating the need for subsequent realignment or recapping operations that would consume additional time while potentially compromising precision.
Solution Approach 2:
By combining implantation and capping into a single simultaneous operation using the same stencil mask, the patent eliminates the sequential time required for separate process steps. The mask serves both functions concurrently, reducing total process time while maintaining alignment precision through the consistent geometric reference provided by the mask structure throughout the combined operation.
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 enables the fabrication of high-efficiency solar cells with reduced costs and improved throughput by ensuring precise alignment and protection of implanted regions during the manufacturing process, addressing contamination and thermal expansion issues associated with traditional methods.
Implementation Method 1
implanting, through a stencil mask, dopant impurity atoms in the silicon layer to form implanted regions of the silicon layer with adjacent non-implanted regions
Implementation Method 2
forming, through the stencil mask, a capping layer on and substantially in alignment with the implanted regions of the silicon layer
Implementation Method 3
removing the non-implanted regions of the silicon layer, wherein the capping layer protects the implanted regions of the silicon layer during the removing
Implementation Method 4
annealing the implanted regions of the silicon layer to form doped polycrystalline silicon emitter regions
Data Source
AI summary
Methods of fabricating solar cell emitter regions using self-aligned implant and cap, and the resulting solar cells, are described. In an example, a method of fabricating an emitter region of a solar cell involves forming a silicon layer above a substrate. The method also involves implanting, through a stencil mask, dopant impurity atoms in the silicon layer to form implanted regions of the silicon layer with adjacent non-implanted regions. The method also involves forming, through the stencil mask, a capping layer on and substantially in alignment with the implanted regions of the silicon layer. The method also involves removing the non-implanted regions of the silicon layer, wherein the capping layer protects the implanted regions of the silicon layer during the removing. The method also involves annealing the implanted regions of the silicon layer to form doped polycrystalline silicon emitter regions.