Transfer of POCl3 diffusion processes from atmospheric pressure to high throughput low pressure

We transfer an industrial-type atmospheric pressure (AP) diffusion process using phosphorus oxychloride (POCl3) with short in-situ oxidation to a low-pressure (LP) system which allows significantly higher throughput. We demonstrate low emitter dark saturation current density j0e ≈ 45 fA/cm2 (texture, SiNX passivation) for optimized LP-POCl3 diffusion at 110 O/sq sheet resistance. Examinations of the glass layer grown on the silicon surface during POCl3 diffusion show a similar two layer system, i.e. phosphosilicate glass and silicon dioxide, for AP-POCl3 and LP-POCl3 diffusions. Industrial p-type Czochralski-grown silicon passivated emitter and rear solar cells yield peak energy conversion efficiencies of 21.1% for both AP- and LP-POCl3-diffused emitters.