CMOS-compatible method for doping of buried vertical polysilicon structures by solid phase diffusion
- Micron Semiconductor Israel Ltd., Qiryat Gat 82109 (Israel)
- Department of Electrical and Computer Engineering, Ben Gurion University of the Negev, Beer-Sheva 8410501 (Israel)
Polysilicon receives attention nowadays as a means to incorporate 3D-structured photonic devices into silicon processes. However, doping of buried layers of a typical 3D structure has been a challenge. We present a method for doping of buried polysilicon layers by solid phase diffusion. Using an underlying silicon oxide layer as a dopant source facilitates diffusion of dopants into the bottom side of the polysilicon layer. The polysilicon is grown on top of the oxide layer, after the latter has been doped by ion implantation. Post-growth heat treatment drives in the dopant from the oxide into the polysilicon. To model the process, we studied the diffusion of the two most common silicon dopants, boron (B) and phosphorus (P), using secondary ion mass spectroscopy profiles. Our results show that shallow concentration profiles can be achieved in a buried polysilicon layer using the proposed technique. We present a quantitative 3D model for the diffusion of B and P in polysilicon, which turns the proposed method into an engineerable technique.
- OSTI ID:
- 22591502
- Journal Information:
- Applied Physics Letters, Journal Name: Applied Physics Letters Journal Issue: 13 Vol. 108; ISSN APPLAB; ISSN 0003-6951
- Country of Publication:
- United States
- Language:
- English
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