Modified Tunnel Oxide Layers for Boron-Resistant TOPCon Passivation
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Solution Overview
Problem
Existing p-type TOPCon solar cell technologies face challenges in achieving high passivation quality due to issues with silicon oxide preparation methods, leading to poor performance and increased costs.
Innovation Solution
A modified tunnel oxide layer with a Si4+ content greater than or equal to 18% is prepared using an ion-free bombardment oxidation method and plasma treatment with hydrogen and oxygen-containing gases, resulting in a stable Si—O bond and reduced boron diffusion, enhancing the passivation effect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If plasma-assisted N2O oxidation method is used to prepare silicon oxide, then the silicon oxide can be formed, but oxygen plasma bombardment introduces huge number of defects at the interface, leading to bad passivation effect
Solution Approach 1:
The patent changes the oxidation method from plasma-assisted N2O oxidation to ion-free bombardment oxidation, fundamentally altering the process parameters to eliminate ion bombardment damage. This parameter change resolves the contradiction by forming silicon oxide without introducing interface defects, achieving both formation and high passivation quality.
Solution Approach 2:
The patent converts the harmful effect of ion bombardment into a beneficial process by using controlled ion-free oxidation conditions. Instead of allowing damaging plasma bombardment, the method utilizes pure oxidation reactions to form high-quality silicon oxide with excellent passivation properties, turning the potential harm of oxidation into a beneficial defect-free formation process.
2Manufacturing precision
If nitric acid oxidation method is used, then silicon oxide surface is formed, but the silicon oxide surface is relatively loose and can be damaged during cleaning and transfer process
Solution Approach 1:
The patent changes the oxidation method from nitric acid oxidation to ion-free bombardment oxidation, altering the chemical and physical parameters of the process. This results in silicon oxide with different structural properties - denser and more robust - that maintains integrity during subsequent cleaning and transfer operations while still achieving proper formation.
3Manufacturing precision
If thermal oxygen oxidation method is used, then silicon oxide with good quality is obtained, but the silicon oxide is relatively thick, leading to bad contact
Solution Approach 1:
The patent changes the oxidation method from thermal oxygen oxidation to ion-free bombardment oxidation, fundamentally altering the growth kinetics and mechanism. This parameter change enables formation of thin silicon oxide layers (1-3 nm) with excellent quality, achieving both good passivation and proper contact by controlling the thickness parameter that was problematic in thermal oxidation.
4Ease of manufacture
If existing silicon oxide preparation methods are used for p-type TOPCon, then the process can be completed, but the passivation quality is bad and cannot satisfy the requirements
Solution Approach 1:
The patent applies ion-free bombardment oxidation with specific parameters (ion-free conditions, controlled temperature, pure oxidizing atmosphere) to fundamentally improve the silicon oxide quality. This parameter change enables achievement of excellent passivation quality (iVoc ≥ 730 mV, J0 ≤ 7 fA/cm2) while maintaining process completeness, resolving the contradiction between ease of manufacture and manufacturing precision.
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 modified tunnel oxide layer improves passivation quality, increasing iVoc to 730 mV and reducing contact resistivity to 5 mΩcm2, while maintaining compatibility with mass-production equipment and reducing material costs.
Implementation Method 1
at step S1, by ion-free bombardment oxidation method, forming a SiOx layer on a surface of a semiconductor substrate
Implementation Method 2
at step S2, with hydrogen and an oxygen-containing gas as treatment atmosphere, performing treatment on SiOx surface by plasma to obtain a modified tunnel oxide layer
Data Source
AI summary
A modified tunnel oxide layer and a preparation method, a TOPCon structure and a preparation method, and a solar cell are provided. The modified tunnel oxide layer is SiOx subjected to plasma surface treatment, and a Si4+ content in the SiOx is greater than or equal to above 18%. The density of the interface state subjected to plasma surface treatment decreases, and compared with the silicon oxide layer prepared in the prior arts, boron has a low diffusion rate in the modified silicon oxide layer and hence the damaging effect of the boron on the tunnel oxide layer is reduced effectively, thereby improving the integrity of the silicon oxide layer and maintaining chemical passivation effect. The modified tunnel oxide layer significantly increases the performance indexes of the TOPCon structure.