Etching Control of HfN Encapsulating Layer for PtHf-Silicide Formation with Dopant Segregation Process

Shun-ichiro OHMI  Yuya TSUKAMOTO  Rengie Mark D. MAILIG  

IEICE TRANSACTIONS on Electronics   Vol.E102-C   No.6   pp.453-457
Publication Date: 2019/06/01
Online ISSN: 1745-1353
DOI: 10.1587/transele.2018FUP0003
Type of Manuscript: Special Section PAPER (Special Section on Fundamentals and Applications of Advanced Semiconductor Devices)
PtHf-alloy silicide,  PtHf-alloy target,  selective etching,  contact resistivity,  dopant segregation,  RF magnetron sputtering,  

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In this paper, we have investigated the etching selectivity of HfN encapsulating layer for high quality PtHf-alloy silicide (PtHfSi) formation with low contact resistivity on Si(100). The HfN(10 nm)/PtHf(20 nm)/p-Si(100) stacked layer was in-situ deposited by RF-magnetron sputtering at room temperature. Then, silicidation was carried out at 500°C/20 min in N2/4.9%H2 ambient. Next, the HfN encapsulating layer was etched for 1-10 min by buffered-HF (BHF) followed by the unreacted PtHf metal etching. We have found that the etching duration of the 10-nm-thick HfN encapsulating layer should be shorter than 6 min to maintain the PtHfSi crystallinity. This is probably because the PtHf-alloy silicide was gradually etched by BHF especially for the Hf atoms after the HfN was completely removed. The optimized etching process realized the ultra-low contact resistivity of PtHfSi to p+/n-Si(100) and n+/p-Si(100) such as 9.4×10-9Ωcm2 and 4.8×10-9Ωcm2, respectively, utilizing the dopant segregation process. The control of etching duration of HfN encapsulating layer is important to realize the high quality PtHfSi formation with low contact resistivity.