Atmospheric Pressure Dry Etching of Polysilicon Layers for Highly Reverse Bias‐Stable TOPCon Solar Cells

• DOI: 10.1002/solr.202100481
• Publication Date: 2021-09-12T17:19:01Z
• Authors: Bishal Kafle; Sebastian Mack; Christopher Teßmann; Sattar Bashardoust; Laurent Clochard; Edward Duffy; Andreas Wolf; Marc Hofmann; Jochen Rentsch
• Keywords: Dry etching; Polycrystalline silicon; Isotropic etching

Single‐sided etching (SSE) of a‐Si/poly‐Si is typically considered a challenge for realizing cost‐efficient TOPCon production sequence, as there certain degree unwanted wrap‐around poly‐Si deposition technologies such low pressure chemical vapor deposition, plasma‐enhanced and atmospheric deposition. To date, alkaline or acidic wet‐chemical solutions in either inline batch configurations are used this purpose. Herein, an alternative SSE process proposed using dry tool, which applies molecular fluorine the gas under conditions. The developed performs complete both as‐deposited amorphous silicon annealed polycrystalline layers, intrinsic doped, with measured etch rates >3 μm min −1 at 10% F 2 concentration allows typical layer thickness 200 nm just few seconds. also configured to perform excellent edge isolation while maintaining ( d rear < 500 μm) opposing‐side. successfully transferred industrial solar cell architecture, yielding high parallel resistances S shunt,avg. > 1500 kΩ cm ), reverse current density J rev,avg 0.8 mA −2 ) bias voltage −12 V, independently certified conversion efficiencies up 23.3%.