The PECVD tools promoted for aluminum oxide deposition are not too different to the ones used for silicon nitride. In fact, the former tools were derived from the latter by changing the precursor supply system and cleaning mechanism. On the process end, silicon nitride films of moderate refractive index of about 2 were typically used during the early days of its introduction. However, it is a tradeoff between passivation and optical properties. While silicon rich films with higher refractive index support better passivation, lower refractive index films are ideal for better optical properties. Films with a graded index, meaning decreasing the refractive index from substrate to ambience, and multilayer films built on the same logic became promising in this context. Such films were also considered a means to combat PID a few years ago. However, depositing these films has been a standard for several years and most PECVD tools support this. The silicon nitride deposition technology knowhow is so widespread that it isn't even aggressively promoted (see PECVD Systems Streamline Alox Deposition By Adding A Sinx Capping Layer Within A Single Vacuum, Optimizing PERC Solar Cell Rear Passivation).
The current Markey survey on Cell Production Equipment features 10 products from 5 suppliers, and none are new, as they feature in one or the other sections discussed above.
Banking on its experience of installing and commissioning such SiNx deposition tools, Centrotherm's c.Plasma XL – SiN tool supports deposition of a variety of silicon nitride layers and stacks. This 10-stack batch system has a rated throughput of 5,600 wafers per hour.
Leadmicro's latest ZR5000X1, introduced in 2023, has a 6-process-chamber setup and it can accommodate M6 to G12 wafer dimensions with a thickness of 140 to 170 μm. The maximum throughput for M10 is given as 8,640 wafers per hour for a cycle time of 33 minutes to process 768 wafers loaded into each boat.
Naura has provided data for 6 PECVD systems also for SiNx deposition; however, the company is repositioning the same aluminum oxide deposition systems also for silicon nitride deposition. The descriptions of the company's tool set presented in the PECVD aluminum oxide deposition tools section are equally valid here as well. Except for the adapted specs for the change in precursor, rest of the specifications including the model names are the same.
S.C New Energy has provided data for its PD520MAX PECVD system introduced in 2022. It can handle wafer dimensions from M0 to G12 with a thickness of 140 to 200 μm and comes in a 6-stack configuration. The system can process 7,250 (M10) or 5,800 (G12) wafers per hour, with a cycle time of 38 minutes. The typical deposition rate is given as 0.8 nm/s and the total system uptime is 96%.
Semco's VICTOR 7000 Series is its PECVD system for SiNx deposition that was first made available in 2011 and has been updated to the M12 version in 2019. It is suitable for M6, M10 and G12 wafer formats and can accommodate 4 to 7 process chambers, and each boat loaded into these tubes comes with a capacity of 850 wafers. In this way, the tool supports a maximum throughput of 8,000 wafers per hour based on a cycle time of 44 minutes.
The article is an excerpt from the TaiyangNews Market Survey on Solar Cell Production Equipment 2023, which also includes detailed product specs and can be downloaded for free here.
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