IBC Photovoltaic Back Contacts With Single-Step Isolation Etching
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing interdigitated back-contact (IBC) photovoltaic devices are complex and costly due to the need for multiple process steps and high accuracy in patterning semiconducting p- and n-type contacts, which increases operational costs and reduces production yield.
Innovation Solution
A simplified process using a conductive layer with a patterned isolation resist layer and conductive pads, where the resist layer remains permanently on the device, allowing for a single etching step to separate charge collecting structures, reducing the number of process steps to four: depositing a conductive layer, an isolation resist layer, contact pads, and etching to form trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If complex lithographic techniques and multiple patterning steps are used to achieve precise interdigitated contact structures, then manufacturing precision is improved, but device complexity and production cost increase
Solution Approach 1:
The conductive layer is segmented into functionally distinct regions (emitter contact regions, base contact regions, and intermediate regions) with different doping types and contact configurations. This segmentation allows each region to be optimized independently while simplifying the overall patterning process through the use of a single resist layer with multiple aperture types.
Solution Approach 2:
A single resist layer serves multiple functions simultaneously: it defines emitter contact apertures, base contact apertures, and intermediate region apertures, and also provides alignment references for subsequent processing steps. This multi-functionality eliminates the need for multiple separate patterning operations.
2Manufacturing precision
If multiple patterning and alignment steps are implemented to create alternating p- and n-type structures, then manufacturing precision is improved, but productivity decreases
Solution Approach 1:
The resist layer is designed with built-in alignment references and geometric relationships that pre-establish the correct positioning of emitter and base contacts before doping occurs. This preliminary geometric configuration eliminates the need for multiple alignment operations during subsequent processing steps.
Solution Approach 2:
Multiple patterning functions that would traditionally require separate lithographic steps are merged into a single resist layer deposition and patterning operation. The resist layer simultaneously defines all contact regions and provides alignment features, combining what would otherwise be multiple sequential operations into one step.
3Manufacturing precision
If conventional patterning methods with multiple process steps are used, then manufacturing precision is improved, but ease of manufacture deteriorates
Solution Approach 1:
The resist layer is designed with locally optimized aperture configurations: emitter contact apertures with specific dimensions and shapes, base contact apertures with different dimensions, and intermediate region apertures with yet another configuration. Each local region of the resist layer is optimized for its specific function while maintaining compatibility with the overall single-step patterning approach.
4Manufacturing precision
If precise localization of semiconducting contacts is achieved through complex techniques, then manufacturing precision is improved, but loss of time increases
Solution Approach 1:
The correct spatial arrangement and positioning of all contact regions are predetermined and encoded in the resist layer geometry before any doping or etching occurs. This preliminary configuration eliminates the need for time-consuming alignment and positioning operations during subsequent processing steps.
Solution Approach 2:
Multiple time-consuming patterning operations are merged into a single resist layer deposition and patterning step. The simultaneous definition of all contact regions, alignment references, and intermediate structures in one operation dramatically reduces the total processing time compared to sequential patterning steps.
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 simplifies the back-end process flow, reduces production costs, and ensures high reliability and efficiency by eliminating the need for complex patterning and multiple etching steps, while maintaining high efficiency in electrical carrier collection.
Implementation Method 1
crystalline silicon with back-contacts being of the interdigitated back contact (IBC) type... an incoming radiation is converted into an electrical signal
Implementation Method 2
etching of the conductive layer in areas specified by apertures in the isolation resist layer
Implementation Method 3
a plurality of conductive pads are applied onto the conductive layer, and so that the conductive pads make electrical contact to the conductive layer
Data Source
AI summary
Disclosed is a method to fabricate an interdigitated back contact photovoltaic device including: providing a substrate of a first-type doping being an n-type or a p-type doping; realizing on a back side a semiconducting doped structure including individual doped layers portions of the first type doping and a semiconducting doped structure of a second type; realizing a conductive layer on top of the semiconducting structure; realizing a patterned isolation resist layer having contact apertures and isolation apertures onto the conductive layer; further applying conductive pads to the contact apertures; and etching the conductive layer up to the second-type doped layer to realize trenches to electrically separate first type charge collecting structures from second type charge collecting structures. Also disclosed is an interdigitated back contact photovoltaic device as manufactured according to the disclosed method of fabrication, and a photovoltaic system including at least two interdigitated back contact photovoltaic devices.