Dual-Step Selective Homoepitaxy of Ge with Low Defect Density and Modulated Strain Based on Optimized Ge/Si Virtual Substrate

Buqing Xu; Yong Du; Guilei Wang; Wenjuan Xiong; Zhenzhen Kong; Xuewei Zhao; Yuanhao Miao; Yijie Wang; Hongxiao Lin; Jiale Su; Ben Li; Yuanyuan Wu; Henry H Radamson

doi:10.3390/ma15103594

Dual-Step Selective Homoepitaxy of Ge with Low Defect Density and Modulated Strain Based on Optimized Ge/Si Virtual Substrate

Materials (Basel). 2022 May 18;15(10):3594. doi: 10.3390/ma15103594.

Authors

Buqing Xu^{1

2}, Yong Du¹, Guilei Wang³, Wenjuan Xiong^{1

2}, Zhenzhen Kong^{1

2}, Xuewei Zhao^{1

4}, Yuanhao Miao^{1

4}, Yijie Wang^{1

5}, Hongxiao Lin⁴, Jiale Su¹, Ben Li⁴, Yuanyuan Wu⁴, Henry H Radamson^{2

4}

Affiliations

¹ Institute of Microelectronics, Chinese Academy of Sciences, Beijing 100029, China.
² School of Integrated Circuits, University of Chinese Academy of Sciences, Beijing 100029, China.
³ Beijing Superstring Academy of Memory Technology, Beijing 100176, China.
⁴ Research and Development Center of Optoelectronic Hybrid IC, Guangdong Greater Bay Area Institute of Integrated Circuit and System, Guangzhou 510535, China.
⁵ School of Information, North China University of Technology, Beijing 100144, China.

Abstract

In this manuscript, a novel dual-step selective epitaxy growth (SEG) of Ge was proposed to significantly decrease the defect density and to create fully strained relaxed Ge on a Si substrate. With the single-step SEG of Ge, the threading defect density (TDD) was successfully decreased from 2.9 × 10⁷ cm^-2 in a globally grown Ge layer to 3.2 × 10⁵ cm^-2 for a single-step SEG and to 2.84 × 10⁵ cm^-2 for the dual-step SEG of the Ge layer. This means that by introducing a single SEG step, the defect density could be reduced by two orders of magnitude, but this reduction could be further decreased by only 11.3% by introducing the second SEG step. The final root mean square (RMS) of the surface roughness was 0.64 nm. The strain has also been modulated along the cross-section of the sample. Tensile strain appears in the first global Ge layer, compressive strain in the single-step Ge layer and fully strain relaxation in the dual-step Ge layer. The material characterization was locally performed at different points by high resolution transmission electron microscopy, while it was globally performed by high resolution X-ray diffraction and photoluminescence.

Keywords: CMOS; Ge epitaxy; compressive strain; selective epitaxial growth.

Grants and funding

This work was supported by the construction of the high-level innovation research institute from the Guangdong Greater Bay Area Institute of Integrated Circuit and System (Grant No. 2019B090909006) and the projects of the construction of new research and development institutions (Grant No. 2019B090904015), in part by the National Key Research and Development Program of China (Grant No. 2016YFA0301701), the Youth Innovation Promotion Association of CAS (Grant No. 2020037) and the National Natural Science Foundation of China (Grant No. 92064002).