Overview

The Room Temperature Wet Chemistry Growth (RTWCG) technology is a novel technology for growing highly uniform amorphous SiOx layers into silicon substrates. It can be broken down into two kinds of applications: as a chemical etchant and as a SiOx growth chemistry. For etching applications, the RTWCG formulation is adjusted to maximize the competitive SiOx etch rate so that it exceeds the oxide growth rate . For SiOx growth applications, the RTWCG formulation’s SiOx growth rate is optimized to exceed the competitive oxide etch rate . By varying the SiOx growth rate and/or the competitive etch-back rate, RTWCG SiOx growth solutions can be formulated to create SiOx thicknesses that range from no oxide to up to 5,000 Angstrom (Å) per a certain constant substrate etch-back. In PV, the RTWCG etch technology can be utilized in various ways such as: dead layer etching, surface etching for selective emitter applications, and as a junction isolation process. The SiOx growth technology can be used to improve the optical properties of solar cells, to mitigate PID, and to increase passivation when used in, for instance, a SiNx/SiOx stack. . For the photovoltaic (PV) industry, the technology can be applied to, either or both, the front and rear side of the solar cell to yield the following: o Front side silicon nitride (SiNx)/SiOx passivation and anti-reflection stack; o Front side SiOx passivation and anti-reflection coating (ARC); o Rear side parasitic emitter etch for junction isolation; o Rear side SiOx passivation layer growth; o Rear side SiOx optical layer; o Diffusion barrier layer. The following cell architectures for both N-type and P-type substrates: o Passivated emitter and rear totally diffused (PERT); o Passivated emitter and rear cell (PERC); o Passivated emitter and rear local back surface field (PERL); o Inter-digitated back contact cell (IBC); o Bi-facial.