Record Low Contact Resistivity to Ge:B (8.1*10-10Omega-cm-2) and GeSn:B (4.1*10-10Omega-cm-2) with Optimized [B] and [Sn] by In-situ CVD Doping
Journal
Digest of Technical Papers - Symposium on VLSI Technology
Journal Volume
2020-June
Date Issued
2020
Author(s)
Abstract
The record low contact resistivity (pc) of Ti contact to Ge:B (8.1*10-10Omega-cm-2) is achieved by in-situ doped CVD using the high-order Ge precursor (Ge2H6). The best achievable [B]. of 7*1020cm-3} and extended epitaxial process window are obtained using Ge2H6. By optimizing the [B] and [Sn], 2% Sn addition into Ge epitaxy reaches the lowest (pc) of 4.1*10-10 Omega-cm-2. Further Sn addition (4.7% and 13.2%) increases pc due to reduced [B], and degrades the thermal stability. The record low resistivity (2*10-4Omega-cm) among epitaxial p-type Ge and GeSn is also demonstrated. Optimized metal etching processes (Cl2+BCl3 for metal on GeSn:B, while C12 for metal on Ge:B) are necessary to minimize etching of GeSn:B and Ge:B, and to fabricate the test structure. A two-sheet-resistance model is used to correctly extract the pc. B segregation (> 1*1021cm3) at the metal/semiconductor interface enables the record low pc. ? 2020 IEEE.
Subjects
Etching; Germanium; Segregation (metallography); Semiconductor alloys; Tin; VLSI circuits; B segregation; Contact resistivities; Epitaxial process; High-order; Low resistivity; Metal etching; Test structure; Ti contacts; Tin alloys
Type
conference paper