SiNx Deposition Systems For Silicon Nitride Deposition
SiNx film engineering, especially graded-index and multilayer stacks, remains central to balancing passivation in TOPCon
UV-Induced Degradation concerns have renewed focus on emitter-side SiNx optimization, with improved stability for SiNx and AlOx/SiNx stacks
Leadmicro’s ZR5000X1 supports these advanced SiNx deposition requirements, offering high throughput with a 6-chamber design
The PECVD tools promoted for aluminum oxide (AlOx) deposition are not too different from those used for silicon nitride (SiNx). In fact, the former tools were derived from the latter by changing the precursor supply system and cleaning mechanism. On the process side, silicon nitride films with a 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 a higher refractive index support better passivation, lower refractive index films are ideal for better optical properties.
Films with a graded index, meaning a decreasing refractive index from substrate to ambient, and multilayer films built on the same logic have become 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 practice for several years, and most PECVD tools support this method. The silicon nitride deposition technology know-how is so widespread that it isn’t even aggressively promoted. However, the unfolding of UV-Induced Degradation (UVID) for TOPCon has brought these silicon nitride films into focus. Rumors made rounds in the PV circles that the deposition method used for depositing the rear passivation stack of TOPCon might be responsible for UVID. However, optimizing the emitter, especially the silicon nitride ARC layers, can potentially mitigate UVID in TOPCon.
According to Leadmicro’s PV Division CTO, Baochen Liao, the optimization of SiNx and/or AlOx/SiNx stacks has shown improved emitter stability under UV exposure. The ZR5000X1, launched in 2023, features a 6-process-chamber design and supports M6 to G12 wafers with thicknesses ranging from 140 to 170 μm in vertical orientation. It handles up to 768 M10 wafers per boat, with a deposition rate of 10 nm per minute. The system achieves a maximum throughput of 8,640 wafers per hour with a 33-minute cycle and a typical throughput of 7,725 wafers per hour with a 38-minute cycle time. Uptime and mechanical yield are reported at 98% and 99%, respectively.
