Structural evolution of in situ boron-doped SiGe ultrathin film analyzed by multi-optical methods

In situ boron (B)-doped SiGe (BSG) layer is extensively used in the source (S)/(D) drain of metal-oxide-semiconductor field-effect transistors. An unexpected structural evolution occurs in BSG during metallization and activation annealing during actual fabrication, which involves a correlated intera...

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Published in:Nanotechnology 2020-04, Vol.31 (27), p.275702-275702
Main Authors: Chang, Feng-Ming, Wu, Zong-Zhe, Chen, Yeh, Yen, Ting-Yu, Huang, Yu-Hsiang, Chong, Li-Yun, JangJian, Shiu-Ko, Lee, Fu-Ying, Chang, Yu-Ming, Lo, Kuang-Yao
Format: Article
Language:English
Subjects:
aggregation
boron-doped SiGe
reflective second harmonic generation (RSHG)
structural evolution
synchrotron x-ray diffraction (XRD)
ultrathin layer
UV Raman
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Summary:In situ boron (B)-doped SiGe (BSG) layer is extensively used in the source (S)/(D) drain of metal-oxide-semiconductor field-effect transistors. An unexpected structural evolution occurs in BSG during metallization and activation annealing during actual fabrication, which involves a correlated interaction between B and SiGe. Herein, the complicated phenomena of the structural evolution of BSG were analyzed by 325 nm micro-Raman spectroscopy, x-ray photoelectron spectroscopy (XPS), reflective second harmonic generation (RSHG), and synchrotron x-ray diffraction (XRD). Optical inspection was integrated into these processes to establish a multi-optical method. 325 nm micro-Raman spectroscopy was used to determine variations in Si-Si, Si-Ge, and Ge-Ge bonds in BSG. XPS exhibited the binding energy evolution of Ge3d during different annealing processes at varied Ge ratios and B concentrations. RSHG revealed the polar Si-B and Ge-B bonds formed during annealing. Synchrotron XRD provided the structure and strain changes of BSG. Secondary-ion mass spectrometer profiles provided the species distribution, which was used to examine the results of multi-optical method. Furthermore, double-layered BSG (DBSG) with different B concentrations were analyzed using the multi-optical method. Results revealed that Ge aggregated in the homogeneous interface of DBSG, and that B dopants in BSG served as carrier providers that strongly influenced the BSG structure. However, BSG with excessive B concentration was unstable and increased the B content (SiB3) through metallization. For BSG with a suitable B concentration, the formation of Si-B and Ge-B bonds suppressed the diffusion of Ge from SiGe, thereby reducing the possibility of Ge loss and further B pipe-up in the heavily doped S/D region.
ISSN:0957-4484
1361-6528
DOI:10.1088/1361-6528/ab8422