Inline PECVD Deposition of Poly‐Si‐Based Tunnel Oxide Passivating Contacts

In this publication, the deposition of a‐Si(n) layers using an industrially relevant inline plasma‐enhanced chemical vapor deposition (PECVD) tool for the successful realization of passivating contacts is reported. Dynamic inline deposition has the potential to increase production throughput and yield compared to the conventional cluster‐like PECVD tools which is the current standard for deposition of a‐Si:H layers. Besides structural investigations concerning absorbance and band gap energy of these layers, the dependence of layer thickness and PH3 gas phase doping on implied open circuit voltage iVOC, sheet resistance, and the corresponding diffusion profile is investigated. A significant influence of PH3 gas phase doping is demonstrated whereas no significant dependence of the layer thickness is elaborated. Excellent values of iVOC = 740 mV and iFF = 85% on planar and iVOC = 720 mV and iFF = 84% on textured surfaces can be reached implementing the developed n‐doped layers in the tunnel oxide passivating contact (TOPCon) structure. Results of symmetrical semi‐finished TOPCon test‐structures with a‐Si(n) layers deposited by using an industrially relevant inline PECVD tool for the realization of passivating contacts are presented. Besides structural properties (e.g., absorbance, band gap energy), diffusion profiles and passivation characteristics have been determined where excellent passivation quality can be demonstrated.