Back-Contacted Solar Cell Metallization via Self-Aligned Sputtering
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Solution Overview
Problem
The production of back-contacted silicon solar cells is challenging and costly due to the complexity and expense of aligning and structuring closely spaced diffused regions, which is incompatible with large-scale, cost-competitive solar cell production.
Innovation Solution
A self-aligned metallization method using vacuum chamber sputtering to deposit a conductive material on a silicon wafer with a multi-level surface structure, where the substrate is positioned at an oblique angle to the sputtering source, allowing for precise deposition and subsequent etching to create defined interdigitated electrode patterns without traditional masking techniques.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional photolithography masking techniques are used to align and structure closely spaced diffused regions, then manufacturing precision can be achieved, but device complexity and production cost increase significantly
Solution Approach 1:
The method uses self-aligned metallization where the metallization process itself creates the alignment reference for subsequent steps. The first metallization layer is deposited and patterned, then used as a mask for the second metallization layer, eliminating the need for external photolithography masks. This self-referential approach maintains precision while reducing process complexity
Solution Approach 2:
The invention extracts and removes the photolithography masking steps from the manufacturing process entirely. By using the deposited metallization layers themselves as alignment references and masks, the complex photolithography equipment and multiple masking steps are eliminated, reducing device complexity while maintaining alignment precision through the self-aligned approach
2Manufacturing precision
If multiple photolithography masking steps are used to create interdigitated patterns, then manufacturing precision is maintained, but productivity decreases due to process time and cost
Solution Approach 1:
The invention merges multiple separate photolithography masking steps into a single integrated metallization process. The first metallization layer is deposited, then the second metallization layer is deposited in a self-aligned manner, combining what would have been separate patterning operations into one continuous process flow, thereby improving productivity while maintaining pattern accuracy
Solution Approach 2:
The first metallization layer is deposited and configured in advance to serve as a self-aligned mask for the second metallization layer. This preliminary action eliminates the need for subsequent photolithography masking steps, as the pre-deposited layer automatically provides the alignment reference, reducing total process time and improving production efficiency
3Ease of manufacture
If conventional front-contacted silicon solar cells are used, then manufacturing simplicity is maintained, but energy conversion efficiency is reduced due to front surface shading
Solution Approach 1:
The invention transitions from conventional front-contacted architecture to back-contacted architecture, moving all metallization and diffused regions to the backside of the solar cell. This dimensional reorganization eliminates front surface shading while maintaining manufacturing simplicity through the self-aligned metallization process that reduces overall process complexity
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 simplifies the process to two steps (sputtering and etching), reducing production costs and enabling efficient, accurate, and scalable manufacturing of back-contacted silicon solar cells by eliminating the need for costly masking techniques while ensuring precise electrical connections.
Implementation Method 1
vacuum chamber sputtering to deposit a conductive material on a silicon wafer
Data Source
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AI summary
A device, and a method and apparatus for producing the device, having a surface layer (4) of a selected material in a predetermined pattern on a surface of a substrate (1). The substrate has a groove (7) or a ridge arranged in said substrate surface, said groove (7) or ridge having a bottom (3) or top (2) face, respectively, and at least one side face (8) sloping with respect to said bottom face (3) or said top face (2). The surface layer (4,5) is deposited on a part of said substrate (1) comprising said groove (7) or ridge by vacuum chamber sputtering of said selected material from a sputtering source (30) whilst moving said substrate (1) past said sputtering source (30) in a direction substantially perpendicular to a direction (40) of a main lobe (20) of sputtering from said sputtering source (30) and with a normal to the substrate surface (1) substantially in a predefined angle with said main lobe (20) direction. After depositing said surface layer, by uniformly etching away surface layer material deposited on said substrate by sputtering until at least a substantial part of said side face (8) is free of said surface layer (5), the predetermined pattern becomes defined substantially by the bottom face (3) of the groove or by the top face (2) of the ridge.