IBC Photovoltaic Back Contacts With Permanent Resist Isolation
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Solution Overview
Problem
The production of interdigitated back-contact (IBC) photovoltaic devices is hindered by complex and costly processing methods, which complicate the patterning and alignment of p- and n-type contacts, leading to high operational costs and reduced production yield.
Innovation Solution
A simplified process involving a conductive layer with a patterned isolation resist layer and conductive pads, where the resist layer remains permanently on the device, allowing for the realization of interdigitated conducting contact structures through a single etching step, reducing the number of process steps from multiple complex etchings to just four main steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multiple complex patterning and etching steps are used to realize IBC devices, then high manufacturing precision is achieved, but device complexity and production cost increase significantly
Solution Approach 1:
The patent combines multiple patterning and etching operations into a single integrated process. The method uses one masking layer with multiple aperture patterns that defines all necessary contact regions (p-type and n-type contacts) in one step, followed by a single etching process that creates all required trenches simultaneously. This merging of operations maintains manufacturing precision while dramatically reducing process complexity.
Solution Approach 2:
The masking layer serves multiple functions: it defines p-type contact regions, defines n-type contact regions, and serves as a protective layer during etching, all in a single component. This multi-functional approach eliminates the need for separate masking layers for different contact types, reducing the overall number of process steps while maintaining the required patterning precision.
2Manufacturing precision
If multiple patterning steps are used to create alternating p- and n-type structures, then manufacturing precision is improved, but productivity decreases due to increased process time
Solution Approach 1:
The patent merges the patterning of p-type and n-type contacts into a single masking step. The masking layer contains aperture patterns for both contact types defined simultaneously, allowing both contact structures to be created in one etching operation rather than requiring sequential patterning steps, thus improving productivity while maintaining alignment precision.
Solution Approach 2:
The masking layer is designed and prepared in advance with all necessary aperture patterns pre-defined. This preliminary preparation of the masking layer with complete patterning information allows the actual contact formation to proceed in a single step, eliminating the need for multiple sequential patterning operations and thereby increasing production speed.
3Manufacturing precision
If complex masking and etching processes are used, then manufacturing precision is achieved, but loss of time increases due to multiple process steps
Solution Approach 1:
The patent combines multiple etching operations into a single etching step. The masking layer with its multiple aperture patterns enables simultaneous etching of all required trenches for both p-type and n-type contacts in one continuous process, eliminating the time required for multiple sequential etching operations while maintaining precise trench alignment.
Solution Approach 2:
All patterning information is pre-defined in the masking layer before the etching process begins. This preliminary configuration of the masking layer with complete aperture patterns for all contacts allows the etching process to proceed in a single step without intermediate masking changes, significantly reducing the total process time while ensuring precise alignment.
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 enhances the reliability and efficiency of IBC solar cells by using a conductive layer with a patterned isolation resist layer and conductive pads, enabling precise etching and protecting the underlying conductive layer during chemical attacks.
Implementation Method 1
etching of the conductive layer in areas specified by apertures in the isolation resist layer and form trenches to electrically separate first type charge collecting structures F1 from second type charge collecting structures F2
Implementation Method 2
apply a plurality of conductive pads onto said resist layer, and so that the conductive pads fill said resist apertures making electrical contact to said conductive layer
Data Source
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AI summary
In the present invention a method to fabricate an interdigitated back contact (IBC) photovoltaic device (1) is disclosed and comprises the steps of providing a substrate (2) of a first-type doping being an n-type or a p-type doping; realizing on a back side (2b) a semiconducting doped structure (6) comprising individual doped layers portions (6') of said first type doping and a semiconducting doped structure (6'') of a second type; realizing a conductive layer (100) on top of the semiconducting structure (6); realizing a patterned isolation resist layer (14) having contact apertures (14b) and isolation apertures (14c) onto said conductive layer (100); further applying a plurality of conductive pads (16, 16') to said contact apertures (14b); and etching the conductive layer (100) up to said second-type doped layer (6'') to realize trenches (20) to electrically separate first type charge collecting structures (F1) from second type charge collecting structures (F2). The invention provides also an interdigitated back contact (IBC) photovoltaic device (1) as manufactured according to the disclosed method of fabrication. The invention relates also to a photovoltaic system comprising at least two interdigitated back contact (IBC) photovoltaic devices (1).