Application of the O-lattice theory for the reconstruction of the high-angle near 90° tilt Si(1 1 0)/(0 0 1) boundary created by wafer bonding N. Cherkashin a,⇑ , O. Kononchuk b , S. Reboh a , M. Hy ¨tch a a CEMES-CNRS and Universite ´ de Toulouse, 29 rue J. Marvig, 31055 Toulouse, France b SOITEC S.A., Core Technologies R&D, Parc Technologique des Fontaines, 38190 Bernin, France Received 8 October 2011; received in revised form 29 October 2011; accepted 29 October 2011 Abstract This work presents an experimental and theoretical identification of defects and morphologies of a high-angle near-90° tilt Si ð  110Þ==ð001Þ boundary created by direct wafer bonding. Two samples with different twist misorientations, between the ð  110Þ layer and the (0 0 1) substrate, were studied using conventional transmission electron microscopy (TEM) and geometric phase analysis of high-resolution TEM images. The O-lattice theory was used for atom reconstruction of the interface along the ½1  10 sub ==½001 lay direc- tion. It is demonstrated that to preserve covalent bonding across the interface, it should consist of f1  11g sub;lay ==f  112g lay;sub facets inter- sected by maximum of six f1  11g lay;sub planes with three 90° Shockley dislocations per facet. It is shown that a particular atom reconstruction is needed at transition points from one facet to another. The presence or absence of deviation from exact 90° tilt of the layer with respect to the substrate is shown to be related directly to the undulations of the interface. It is demonstrated that the latter has an influence on the Burgers vector of the dislocations adjusting in-plane twist misorientation. A general model for cubic face-centered materials for an arbitrary h110i sub,lay tilt interface is proposed, which predicts the net Burgers vector and the spacing between disloca- tions necessary to realize transition from the lattice of the substrate (layer) to the layer (substrate). Ó 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. Keywords: Bonding; Grain boundaries; Dislocations; Transmission electron microscopy; Modeling 1. Introduction Direct Si wafer bonding (DSB) with a desirable twist/tilt disorientation between wafers has become an attractive technique in modern semiconductor technology [1,2]. One of the applications of this technique, hybrid orientation technology (HOT), is a promising way of enhancing hole mobility for high-performance CMOS circuits [3]. The HOT integration process uses a thin Si(1 1 0) layer directly bonded to a Si(0 0 1) wafer as a starting substrate. Atomic rearrangement at the Si(1 1 0)//Si(0 0 1) interface results in the creation of a 90° high-angle grain boundary (HAGB), a so-called incommensurate grain boundary characterized by an absence of any periodic coincidence site lattice. It has been reported that this grain boundary can interfere with device performance by increasing the leakage current of positive channel field effect transistors [4]. Thus, the local structure, crystalline quality, planarity and width of a 90° HAGB are of great practical importance and have received considerable attention from the research commu- nity [5–14]. The few studies that have reported theoretical and experimental reconstruction of such interface reveal some contradictions. The simple model using flat 20/14 atom supercells, which preserves covalent bonding across the interface, leads to a flat interface with a width of 0.18 nm and accumulated strain of 1% [6,7]. The valence band 1359-6454/$36.00 Ó 2011 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.actamat.2011.10.054 ⇑ Corresponding author. E-mail address: nikolay.cherkashin@cemes.fr (N. Cherkashin). www.elsevier.com/locate/actamat Available online at www.sciencedirect.com Acta Materialia 60 (2012) 1161–1173