Polymer Passivation Film for Semiconductor Substrates
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Solution Overview
Problem
Conventional methods for producing silicon photovoltaic cell elements face issues with internal stress due to differing thermal expansion coefficients of silicon and aluminum, leading to crystal defects and warpage, and existing passivation films have high production costs and low throughput.
Innovation Solution
A passivation film for semiconductor substrates is formed using a polymer compound with anionic or cationic groups, combined with a filler and metal alkoxide, which is applied as a coating and dried to provide effective surface passivation with improved mechanical strength and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thick aluminum layer is formed on the back surface to reduce sheet resistance, then electrical conductivity is improved, but internal stress increases causing crystal defects and warpage
Solution Approach 1:
The back surface electrode is divided into multiple small point contacts instead of a single continuous thick layer. This segmentation reduces the total amount of aluminum while maintaining electrical conductivity through distributed contact points, thereby reducing internal stress and preventing crystal defects and warpage.
Solution Approach 2:
Aluminum electrodes are applied only at specific local positions (point contacts) on the back surface rather than uniformly across the entire surface. This localized approach reduces the overall aluminum thickness and internal stress while maintaining necessary electrical connections at critical points.
2Object-affected harmful factors
If the amount of aluminum paste is reduced to decrease internal stress, then warpage and crystal defects are reduced, but the BSF effect deteriorates due to insufficient aluminum diffusion
Solution Approach 1:
Aluminum paste is selectively applied at specific local positions where point contacts are formed, concentrating the aluminum diffusion effect at these critical locations. This localized application ensures sufficient BSF effect at the contact points while using minimal aluminum overall, thus reducing internal stress and warpage.
Solution Approach 2:
The back surface is pre-treated (e.g., with HF acid) before aluminum paste application to enhance aluminum diffusion efficiency. This preliminary treatment ensures that even small amounts of aluminum paste can achieve the desired BSF effect, allowing reduced aluminum usage while maintaining reliability.
3Reliability
If SiO2 or SiNx films are used as passivation films, then surface passivation is achieved, but production costs increase and throughput decreases
Solution Approach 1:
The patent employs simpler, more cost-effective passivation methods or materials that can be applied rapidly without requiring complex thermal oxidation or CVD equipment. This approach uses economical solutions that achieve sufficient passivation performance while enabling higher production throughput and lower costs.
Solution Approach 2:
The patent replaces complex thermal or chemical vapor deposition processes with simpler alternative methods for forming passivation films. This substitution eliminates the need for high-temperature furnaces or complex CVD equipment, thereby reducing production costs and increasing manufacturing throughput while maintaining adequate passivation performance.
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
The solution enables the formation of a passivation film that reduces recombination of minority carriers, enhances the effective lifetime of minority carriers, and improves the efficiency and stability of photovoltaic cell elements while reducing production costs.
Implementation Method 1
The passivation film reduces the surface state density, which causes recombination, by terminating dangling bonds of silicon atoms at a surface portion of the back surface of the silicon substrate, by forming an oxide film on the back surface of the silicon substrate.
Implementation Method 2
a passivation film for a semiconductor substrate that is a coating film formed on a semiconductor substrate from the material for forming a passivation film for a semiconductor substrate
Data Source
AI summary
The invention provides a material for forming a passivation film for a semiconductor substrate. The material includes a polymer compound having an anionic group or a cationic group.