N-type bifacial cell manufacturing method with solid boron diffusion
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Solution Overview
Problem
Conventional n-type bifacial solar cell manufacturing processes face challenges such as limited productivity due to boron diffusion space constraints, contamination of non-diffused areas, poor passivation effects, and high energy consumption, especially with silicon nitride and thermal silicon oxide methods.
Innovation Solution
A manufacturing method involving alkaline surface treatment, boron diffusion in a mixed oxygen-nitrogen atmosphere, phosphorus diffusion, and the use of aluminum oxide and silicon nitride passivation films, with PECVD or ALD deposition, to create a high-low-junction structure and improve diffusion uniformity and productivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If gas carrying boron tribromide steam is used for diffusion, then boron diffusion can be achieved, but productivity is limited due to space constraints and additional cleaning steps are required
Solution Approach 1:
The patent changes the diffusion method from gas-phase boron tribromide steam diffusion to solid-phase boron source diffusion. This parameter change allows the use of spin coating to uniformly deposit boron sources on the silicon wafer surface, achieving consistent diffusion without requiring large furnace spaces. The solid-phase diffusion process also eliminates the contamination issue affecting non-diffused areas, reducing or eliminating cleaning steps and improving productivity.
Solution Approach 2:
The patent replaces the complex gas-phase diffusion system with a simpler solid-phase diffusion approach. Instead of using gas carriers and steam generation systems, the invention uses direct spin coating of boron-containing materials followed by thermal diffusion. This substitution simplifies the equipment requirements, increases production speed, and improves diffusion uniformity while reducing the need for additional cleaning operations.
2Reliability
If silicon nitride is used for passivation, then passivation layer can be formed, but passivation effect is poor due to positive charge
Solution Approach 1:
The patent employs a composite passivation structure consisting of multiple layers including silicon nitride and other materials. By combining silicon nitride with additional passivation layers, the positive charge effect is compensated or neutralized, achieving effective surface passivation. This composite approach maintains the manufacturing simplicity of silicon nitride deposition while overcoming its inherent electrical property limitations.
3Reliability
If thermal silicon oxide is used for passivation, then passivation layer can be formed, but energy consumption is high and PN junction morphology is easily damaged
Solution Approach 1:
The patent changes the passivation process parameters by replacing high-temperature thermal oxidation with lower-temperature chemical vapor deposition or other low-energy deposition methods. This parameter change reduces energy consumption significantly while still forming effective passivation layers. The lower processing temperature also prevents damage to the PN junction morphology, maintaining device integrity without requiring excessive thermal energy input.
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 method enhances efficiency, reduces additional cleaning steps, and maintains a low-temperature process, ensuring better passivation and productivity while preventing PN junction damage.
Implementation Method 1
a step S1 of performing treatment on an upper surface and a lower surface of an n-type silicon wafer by using an alkaline solution; a damaged layer is removed by using a NaOH solution
Implementation Method 2
performing boron diffusion in a furnace tube; the boron diffusion is performed in the furnace tube under atmosphere of mixed gases of oxygen and nitrogen
Implementation Method 3
manufacturing a passivation anti-reflection film made of aluminum oxide and silicon nitride on the surface of the diffused boron
Implementation Method 4
with PECVD or ALD deposition
Implementation Method 5
passivation and anti-reflection on a p-type surface (a diffused boron surface) are mainly realized by manufacturing silicon nitride or silicon oxide
Implementation Method 6
performing phosphorus diffusion on the lower surface of the n-type silicon wafer, and forming a high-low-junction structure on the lower surface
Data Source
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AI summary
Provided is a manufacturing method for an N-type double-sided battery. The method comprises the following steps: S1, performing texturing treatment; S2, evenly coating a boron source on the upper surface of an N-type silicon wafer in a spin coating or silk-screen printing manner, and conducting boron diffusion in a furnace tube; S3, manufacturing a mask; S4, conducting phosphorus diffusion on the lower surface of the N-type silicon wafer, and forming a high-low-junction structure on the lower surface; S5, removing phosphorosilicate glass and the mask that is manufactured in step S3; S6, manufacturing a passivation anti-reflection film made from aluminum oxide and silicon nitride on the surface of the diffused boron, and manufacturing a silicon nitride passivation anti-reflection film on the surface of the diffused phosphorus; and S7, manufacturing an electrode. The manufacturing method for the N-type double-sided battery is simple in process, and effectively improves the efficiency of the battery. In addition, also provided is an N-type double-sided battery. A passivation layer manufacturing method for the N-type double-sided battery is a low-temperature process, and does not damage a PN junction.