Formation and characterization of locally strained Ge 1 - x Sn x / Ge microstructures Shinichi Ike a, ⁎ ,1 , Yoshihiko Moriyama b , Masashi Kurosawa a,c , Noriyuki Taoka a , Osamu Nakatsuka a , Yasuhiko Imai d , Shigeru Kimura d , Tsutomu Tezuka b , Shigeaki Zaima a a Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603, Japan b Green Nanoelectronics Collaborative Research Center (GNC), National Institute of Advanced Industrial Science and Technology (AIST), West 7A, Onogawa 16-1, Tsukuba, Ibaraki 305-8569, Japan c Research Fellow of the Japan Society for the Promotion of Science, Japan d Japan Synchrotron Radiation Research Institute (JASRI)/SPring-8, Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198, Japan abstract article info Available online 12 September 2013 Keywords: Germanium Tin X-ray microdiffraction Strain Epitaxial growth GeSn Finite element method In this study, we have examined the formation of uniaxially strained Ge microstructures with embedded Ge 1 - x Sn x epitaxial layers and the microscopic local strain structure in Ge and Ge 1 - x Sn x using synchrotron X-ray microdiffraction and the finite element method. We achieved local heteroepitaxial growth of Ge 0.947 Sn 0.053 layers on the Ge recess regions. Microdiffraction measurements reveal that an average uniaxial compressive strain of 0.19% is induced in Ge locally with Ge 1 - x Sn x stressors. In addition, we found that the Sn precipitation near the Ge 1 - x Sn x /Ge(001) interface occurs after post-deposition annealing at 500 °C without the introduction of disloca- tion. It is considered that the local Sn precipitation occurs preferentially due to the larger residual stresses near the Ge 1 - x Sn x /Ge interface. © 2013 Elsevier B.V. All rights reserved. 1. Introduction The strain engineering of the Ge channel is very attractive for im- proving the performance of Ge metal-oxide-semiconductor field effect transistors (MOSFETs). In particular, uniaxial compressively strained Ge(001) promises to realize a higher hole mobility than strained Si(001) or Ge(001) with other strain structures [1]. Therefore, uniaxial compressively strained Ge is a candidate high-speed channel material of p-type MOSFETs. According to a previous report [1], a uniaxial com- pressive strain of 1% for a Ge(001) channel is expected to exceed the ef- fective hole mobility of a strained Si(001) channel. Ge 1 - x Sn x , which has a larger lattice constant than Ge, has been considered a potential source/drain (S/D) stressor for realizing a uni- axial compressively strained Ge. To induce a uniaxial compressive strain of 1%, a substitutional Sn content of at least 5% is necessary for a Ge 1 - x Sn x stressor [2]. However, there is a concern of Sn precip- itation from the Ge 1 - x Sn x layer due to the very low equilibrium solid solubility of Sn, which is as low as 1% in Ge. In addition, the Ge 1 - x Sn x layer must be locally grown in S/D regions without the generation of any dislocations to suppress the leakage current through the S/D and the channel. Previously, in the case of blanket Ge 1 - x Sn x layers, we reported that the growth of a fully strained Ga-doped Ge 0.922 Sn 0.078 layer on Ge(001) was achieved without any dislocations or stacking faults by molecular beam epitaxy (MBE) [3]. The growth of fully-strained Ge 1 - x Sn x layers with Sn contents up to 10% on Ge(001), and unstrained Ge 1 - x Sn x layers with Sn contents up to 17% directly on Si(001) was demonstrated by chemical vapor deposition (CVD) [4,5]. On the other hand, the simula- tions of local stress structure for Ge channel p-MOSFETs with Ge 1 - x Sn x S/D [6], and strained Si 1 - x Ge x channel with Si 1 - x - y Ge x Sn y S/D stressors formed by Sn implantation were reported [7]. However, there are few reports about the local growth of Ge 1 - x Sn x in S/D regions and local strain structures around Ge 1 - x Sn x and Ge. In the application of Ge 1 - x Sn x S/D stressors for 3D-MOSFETs, such as FinFETs, the local growth of Ge 1 - x Sn x in the recess regions, including various surface orientations, is essential technology. Moreover, the local crystalline strains of Ge 1 - x Sn x /Ge microstructures also require investigation. To clarify the distribution and magnitude of local crystalline strains for Ge 1 - x Sn x /Ge structures, analysis methods with high spatial and strain resolution are required. X-ray diffraction (XRD) measurements provide the highest strain resolution and realize the direct measurement of strain components without the destruction of the sample, but its spatial resolution is not particularly high. On the other hand, X-ray microdiffraction combined with synchrotron radiation provides both high strain resolution (Δε ~ 10 -5 ) and sub-micron space resolution [8,9]. Previously, we reported the local crystalline structure in Si 1 - x Ge x heteroepitaxial layers on a sub-micron scale using microdiffraction Thin Solid Films 557 (2014) 164–168 ⁎ Corresponding author. E-mail address: sike@alice.xtal.nagoya-u.ac.jp (S. Ike). 1 Tel.: +81 52 789 3819; fax: +81 52 789 2760. 0040-6090/$ – see front matter © 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.tsf.2013.08.126 Contents lists available at ScienceDirect Thin Solid Films journal homepage: www.elsevier.com/locate/tsf