Plasma Sheath Modulation for Solar Cell Texturing
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Solution Overview
Problem
Existing methods for fabricating workpieces, such as solar cells, are costly and time-consuming due to the complexity and number of process steps required, particularly in patterning layers and forming metal contacts, which can be simplified by integrating multiple processes in a single system using plasma processing.
Innovation Solution
A method involving the generation of a plasma with a controlled plasma sheath, where the shape of the boundary between the plasma and the sheath is modified using an insulating modifier to allow for precise etching, sputtering, and doping of workpiece surfaces, enabling efficient texturing and metal layer formation without the need for multiple steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple process steps are used for fabricating solar cells (patterning, doping, metal layer formation), then manufacturing precision is improved, but device complexity and fabrication time increase
Solution Approach 1:
The patent combines multiple separate process steps (patterning, doping, metal layer formation) into a single integrated plasma processing step. The plasma process simultaneously performs etching to create patterns, deposits dopants through ion implantation, and forms metal layers, eliminating the need for sequential separate processes and reducing overall device complexity
Solution Approach 2:
The plasma processing system is designed to perform multiple functions simultaneously: it acts as an etching tool for patterning, a doping tool for introducing dopants, and a deposition tool for forming metal layers. This multi-functional approach allows a single process step to achieve what previously required multiple specialized processes
2Manufacturing precision
If multiple process steps are used for fabricating solar cells, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
By merging patterning, doping, and metal layer formation into a single plasma process step, the patent eliminates the sequential time required for multiple separate processes. The simultaneous execution of these operations in one step dramatically increases fabrication throughput while maintaining the precision required for each individual operation
3Loss of substance
If conventional plasma etching is used, then material removal is achieved, but surface uniformity deteriorates due to random pyramid patterns
Solution Approach 1:
The patent introduces an insulating modifier that creates locally differentiated plasma properties. The modifier causes the plasma to have different characteristics in different regions, enabling controlled and uniform material removal across the surface. This local variation in plasma quality ensures consistent etching rates and uniform surface patterns, eliminating the random pyramid structures produced by conventional uniform plasma
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 significantly reduces fabrication time and cost by enabling efficient texturing, doping, and metal layer formation on solar cells, increasing throughput and improving the uniformity and efficiency of light absorption, while minimizing metal contamination and process duration.
Implementation Method 1
generating a plasma having a plasma sheath proximate a surface of the workpiece. A first portion of the surface of the workpiece is removed with the plasma
Implementation Method 2
A first portion of the surface of the workpiece is removed with the plasma
Implementation Method 3
A shape of a boundary between the plasma and the plasma sheath is controlled such that a portion of the shape is not parallel to the surface of the workpiece
Implementation Method 4
The workpiece is rotated in a direction parallel to the plane. A second portion of the surface of the workpiece is removed with the plasma
Data Source
AI summary
Methods to texture or fabricate workpieces are disclosed. The workpiece may be, for example, a solar cell. This texturing may involve etching or localized sputtering using a plasma where a shape of a boundary between the plasma and the plasma sheath is modified with an insulating modifier. The workpiece may be rotated in between etching or sputtering steps to form pyramids. Regions of the workpiece also may be etched or sputtered with ions formed from a plasma adjusted by an insulating modifier and doped. A metal layer may be formed on these doped regions.