Borosilicate Glass Doping Layer for Solar Cell Subzones
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Solution Overview
Problem
Conventional methods for producing differently doped subzones in silicon substrates for solar cells require multiple processing steps and cannot efficiently produce both p-type and n-type doped subzones with varying doping concentrations in a single step.
Innovation Solution
A method involving the use of a borosilicate glass doping layer with boron, which enhances the diffusion of phosphorus into a silicon substrate at high temperatures, allowing for the production of multiple subzones with varying doping concentrations in a single process by controlling the coverage of the doping layer and parameters during heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional methods using masking layers and multiple processing steps are used to produce differently doped subzones, then manufacturing precision can be achieved, but device complexity and manufacturing time increase significantly
Solution Approach 1:
The patent combines multiple doping operations into a single processing step by using a doping layer with spatially varying dopant concentrations. Different subzones (first, second, and third subzones) are doped simultaneously in one heating process, eliminating the need for multiple separate doping steps and masking operations that would otherwise be required to achieve different doping concentrations.
Solution Approach 2:
The doping layer is prepared in advance with predetermined dopant concentration distributions before the actual doping process. The layer contains different concentrations of first and second dopants in different regions, so when heating is applied, the desired doping profiles are achieved automatically without requiring complex real-time control during the doping process.
2Manufacturing precision
If multiple separate doping processes are used to produce p-type and n-type doped subzones with varying concentrations, then doping precision is maintained, but productivity decreases
Solution Approach 1:
The patent merges multiple doping processes into a single heating step. The doping layer contains both first dopant (for n-type regions) and second dopant (for p-type regions) with different concentrations in different areas. During one heating process, all subzones are doped simultaneously to their respective target concentrations, achieving what would otherwise require multiple sequential doping steps.
Solution Approach 2:
The single heating process serves multiple functions simultaneously: it diffuses first dopant into regions requiring n-type doping, diffuses second dopant into regions requiring p-type doping, and achieves different doping concentrations in different subzones all within one operation, replacing what would traditionally require multiple specialized doping processes.
3Manufacturing precision
If doping layers with different dopant concentrations are applied to different subzones, then manufacturing precision improves, but device complexity and process difficulty increase
Solution Approach 1:
The patent uses a composite doping layer structure that combines multiple dopants (first dopant for n-type, second dopant for p-type) with different concentrations in a single layer. This composite layer is applied to the entire semiconductor substrate surface, and during heating, the different regions receive the appropriate dopants at the appropriate concentrations based on the layer's composition, achieving complex doping profiles without complex layer structures.
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 enables the efficient production of multiple subzones with heavy and light doping concentrations, achieving unique doping profiles that enhance the performance of solar cells by promoting charge separation and reducing recombination, while simplifying the manufacturing process.
Implementation Method 1
Heating the thus prepared silicon substrate to temperatures above 800 °C., preferably above 900 °C., in a furnace in an atmosphere containing significant quantities of the first dopant type
Data Source
AI summary
What is proposed is a method of producing at least two differently heavily doped subzones (3, 5) predominantly doped with a first dopant type in a silicon substrate (1), in particular for a solar cell. The method comprises:covering at least a first subzone (3) of the silicon substrate (1) in which a heavier doping with the first dopant type is to be produced with a doping layer (7) of borosilicate glass, wherein at least a second subzone (5) of the silicon substrate (1) in which a lighter doping with the first dopant type is to be produced is not covered with the doping layer (7), and wherein boron as a dopant of a second dopant type differing from the first dopant type and oppositely polarized with respect to the same is included in the layer (7), and;heating the such prepared silicon substrate (1) to temperatures above 300° C., preferably above 900° C., in a furnace in an atmosphere containing significant quantities of the first dopant type. Additionally, at least a third doped subzone (15) doped with the second dopant type may be produced by the method additionally comprising, prior to the heating, a covering of the doping layer (7), above the third doped subzone (15) to be produced, with a further layer (17) acting as a diffusion barrier for the first dopant type.The method uses the observation that a borosilicate glass layer seems to promote an in-diffusion of phosphorus from a gas atmosphere and may substantially facilitate a manufacturing for example of solar cells, in particular back contact solar cells.