As part of PERC processing, Plasma Enhanced Chemical Vapor Deposition (PECVD) has an undeniable advantage of depositing aluminum oxide and silicon nitride capping layer simultaneously in one system. Taking this concept to the next level, Meyer Burger is now introducing an innovative product platform that enables the deposition of even the front side silicon nitride layer along with the rear passivation stack in one machine.
The tool is appropriately tagged MAiA 3 in 1 as it deposits three dielectric layers in total.The inline design of Meyer Burger's deposition systems comes with the advantage of a modular platform that enables adding the number of process modules depending on the throughput requirement. Taking advantage of this modular design, the company has hooked up an additional process chamber for depositing silicon nitride on the front side.
The MAiA 3 in 1 3400 R2.1 represents the common product of the new platform. The system comes with 3 to 4 process chambers of which one is dedicated for aluminum oxide deposition. Depending on the capping layer thickness one or two chambers are integrated into the setup for capping silicon nitride deposition also on the rear side. The silicon nitride on sunny side is deposited in a separate chamber. There is no additional transfer chamber between the two silicon nitride chambers, underscores product manager Mirko Meyer. Since each chamber is equipped with a dedicated pumping system, Meyer Burger says the system has no cross gas flows. In order to avoid wafer flipping for depositing the passivation film on the front side, the plasma sources are arranged accordingly in top down manner. Meyer Burger has also optimized its tray design with this updated platform.
According to a presentation of the company at the 26th Asia Photovoltaic Solar Energy Conference and Exhibition (PVSEC) in Singapore in October, the 3in1 tray reduces the non deposited area to 0.1% compared to about 5% with pocket tray design. This optimized tray design reduces wrap around and shadowing, which has a potential to increase the efficiency by 0.1%. As with the earlier platform, the MAiA 3 in 1 also enables the deposition of dielectric films with gradient refractive index for better optical absorption of the incident light. According to the data presented at PVSEC, the cells processed in the 3 in 1 system attained a slightly better fill factor, which attributed to no additional vacuum interruption. Overall the new platform is at par in terms of cell efficiency compared to separated processes though with a slight upside potential.
The MAiA 3 in 1 3400 R2.1 supports a cycle time of 25.4 seconds, in which a tray with 24 wafers is processed. This account to a maximum throughput of 3,400 wafers per hour and a net capacity of 3,162 wafers per hour. The system has a rated uptime of 93%.
According to product manager Mirko Meyer, this combined front and rear side dielectric deposition approach not only eases the process but also has a potential to reduce the capex by 25% and cost of ownership by 20% without any performance loss. Meyer Burger has built a MAiA 3 in 1 3400 R2.1 for its internal usage and installed the tool at its own pilot line in Germany. The system has been thoroughly verified for layer uniformities and lifetimes – and was found to have the same level as that of the earlier configuration of separated deposition front and back passivation layers, according to Meyer Burger.
After presenting the results in October 2016 at the PVSEC in Singapore, Mirko Meyer says the platform has attracted interest from serious customers. Currently, Meyer Burger is doing live sampling at its German facility to demonstrate promised layer quality and cost reductions. The company is planning to ship the first system in Q3/2017.
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