Vacuum Sputtering of Doped Silicon for Edge-Shaded Solar Cells
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Solution Overview
Problem
The production of solar cells with passivated contacts, such as TOPCon technology, is hindered by high costs and inefficiencies due to recombination losses and edge grip issues caused by conventional chemical vapor deposition methods, leading to increased waste and production challenges.
Innovation Solution
The use of physical vapor deposition (PVD) techniques, specifically sputtering with a shading mask and low coating temperatures, to form a tunnel oxide passivated contact with a doped polycrystalline silicon layer, reducing recombination losses and edge grip while minimizing toxic gas usage and energy consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical vapor deposition (CVD) is used to produce the doped silicon thin film, then the film can be deposited, but toxic gases are used and the process is limited in scalability
Solution Approach 1:
The patent transitions from chemical vapor deposition to physical vapor deposition (sputtering), fundamentally changing the deposition mechanism from chemical reaction-based to physical bombardment-based. This parameter change eliminates the need for toxic silane gases while achieving comparable or superior film quality through controlled atomic deposition
Solution Approach 2:
The patent replaces the chemical field (CVD using chemical reactions of silane gas) with a physical field (PVD/sputtering using ion bombardment and physical deposition). This substitution eliminates toxic gas chemistry while maintaining film deposition capability through purely physical processes
2Manufacturing precision
If CVD process is used for coating, then the doped silicon thin film can be formed, but edge wrapping occurs causing electrical short-circuit
Solution Approach 1:
The patent applies different deposition conditions to different regions of the substrate. By controlling the sputtering geometry, deposition angle, and using masking techniques, the process achieves precise lateral confinement of the film only to the rear surface area where passivated contacts are needed, preventing edge wrapping while ensuring complete coverage of the intended region
Solution Approach 2:
The patent segments the deposition process into controlled zones using masks and geometric control. The rear surface is divided into active contact regions and passive regions, with deposition selectively applied only where needed, preventing unwanted material deposition on edges and sides
3Reliability
If additional process steps like wet chemical etching are used to remove edge overhang, then edge grip issues are resolved, but extra costs and scrap losses increase
Solution Approach 1:
The patent performs preliminary action by precisely controlling the deposition process from the start to prevent edge wrapping before it occurs. The sputtering process parameters, mask design, and substrate positioning are optimized upfront to ensure material is deposited only where intended, eliminating the need for subsequent corrective etching steps
Solution Approach 2:
The patent extracts the problematic edge wrapping issue from the process by fundamentally changing the deposition mechanism. Instead of depositing material and then removing excess, the process directly deposits material only in the desired location through physical vapor deposition with controlled trajectory and masking, taking out the need for material removal steps
4Manufacturing precision
If conventional CVD processes are used, then film deposition is achieved, but scalability is limited and production efficiency is reduced
Solution Approach 1:
The patent changes the fundamental deposition parameter from chemical vapor-phase reaction to physical sputtering deposition. This enables higher deposition rates, better conformal coverage, and easier integration with automated production lines, significantly improving scalability and productivity while maintaining or enhancing film quality
Solution Approach 2:
The patent replaces the chemical reaction-based CVD system with a physical sputtering system that can be more easily scaled. The sputtering process allows for higher throughput, better process control, and easier integration with continuous production methods, removing the scalability limitations of conventional CVD
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 enhances the efficiency and cost-effectiveness of solar cell production by reducing recombination losses, avoiding edge grip issues, and minimizing waste, making mass production of high-efficiency solar cells economically viable.
Implementation Method 1
physikalische Gasphasenabscheidung (PVD), bevorzugt Sputtern
Implementation Method 2
in einem Vakuum angeordnete Beschichtungseinrichtung
Data Source
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AI summary
According to various embodiments, a method (300) for processing a solar cell precursor (402) having a side coated with at least one dielectric may comprise: atomizing (303) a sputtering target (404) into a coating area (401), wherein the sputtering target (404) comprises a semiconductor material; wherein the sputtering target (404) further comprises a dopant of the semiconductor material in an amount greater than a solubility limit of the dopant in the semiconductor material and/or a mass fraction of the dopant of 0.15%; arranging (305) the solar cell precursor (402), which is embedded in a substrate support, in the coating area (401), with the sputtering of the sputtering target (404) into the coating area (401) such that the side is facing the sputtering target (404);wherein the substrate carrier is arranged such that an edge (510k, 512k) of the solar cell precursor (402) running along a closed path is shaded by means of the substrate carrier from the sputtering of the sputter target (404).