Dopant Patterning by PECVD and Mechanical Masking for Passivated Tunneling Contact IBC Cell Architectures

We present a robust, simple technique for dopant patterning onto poly-Si/SiO 2 passivated tunneling contacts on nCz wafers. Heavily doped, thin nand ptype a-Si:H overlayers serve as solid-state dopant sources for blanket intrinsic a-Si:H layer on tunneling SiO 2 . Subsequent processing results in uniformly doped, functional n- and p-type passivated contacts. Furthermore, physical masking during the PECVD of the dopant source overlayers enables an interdigitated back contact (IBC) cell structure with sufficient doped finger edge fidelity to preserve an intrinsic electrode gap. Lithography-free, passivated contact IBC cell structures are made using a set of n-, p-, and metallization masks from patterned Si wafers with mechanical alignment. Alternatively, doped a-Si:H overlayers are patterned by dielectric layer deposition and lithography.