In situ etch treatment of bulk surface for epitaxial layer growth optimization C.F. Pirri a,b , S. Ferrero a,b , L. Scaltrito a,b, * , D. Perrone a,b , S. De Angelis a,b,c , M. Mauceri c , S. Leone c , G. Pistone c , G. Abbondanza c , D. Crippa d a INFM-Physics Department, Politecnico di Torino, C.so Duca degli Abruzzi 24, Torino, Italy b Material and Microsystems Laboratori-v Lab, Palazzo ‘‘L.EINAUDI’’, Lungo Piazza d’Armi 6, Chivasso, Torino, Italy c ETC s.r.l c/o BiC Sicilia, Z.I. Pantano DÕArci, 95030 Catania, Italy d LPE S.p.A Via Falzarego, 8 I-20021 Bollate, Milano, Italy Available online 18 November 2005 Abstract Homoepitaxial bulk 4H SiC-off-axis commercial wafers were investigated after in situ hydrogen etching on a hot wall chemical vapor deposition (HWCVD).We have performed test etching on several process conditions in order to study the surface defects reduction or transformation. A detailed map of bulk defects has been obtained by optical microscopy inspection to mark interesting position of inves- tigated area and to identify the same area after chemical etching, with the aim to compare the defect evolution after hydrogen etching in the reactor. The highlighted defects area was analysed by means of atomic force microscopy and Micro Raman spectroscopy in order to obtain morphological and structural information. On the etched surface bulk wafer a epilayer was grown by HWCVD reactor to study the development of marked defects. The etched surfaces show a significant defect density reduction and present a good surface morphology. Ó 2005 Elsevier B.V. All rights reserved. Keywords: SiC; Growth; Epitaxial layer; Etching 1. Introduction One of the most important key factor for the semicon- ductor technology is the quality of substrate material. It has been observed [1] that different types of defects on the bulk material can propagate in the epitaxial layer grown on. Some groups [2] have proposed etching treat- ment in order to improve the crystal quality of the sub- strate by removing some of these defects. Hydrogen etching in a hot wall CVD reactor has been proposed [3] as physical desorption mechanism to solve the defect problem and it also represents an interesting method to reduce the superficial roughness. In this work, we have studied the hydrogen etching effect, as physical desorption phenomenon of the gaseous hydrocarbons and silicon, at 1600 °C and 100 mbar pres- sure under different process conditions on commercially 4H-SiC substrates, and the surface morphology evolution after epilayer deposition. After the above-mentioned treatment, we did not observe any silicon droplets [4] and the surface appears specular and smooth in an AFM analysis more over the etch pits, previously present on the substrate, disappeared. 2. Experimental details A map of bulk defects has been achieved on three wafers (A1, A2 and A3) by means of optical microscopy inspec- tion to mark the defect position with the aim to study the defect evolution after hydrogen etching and epitaxial growth [6]. The etching tests and epitaxial growth were performed in a hot-wall CVD reactor [5], we used production 0167-9317/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.mee.2005.10.051 * Corresponding author. E-mail address: luciano.scaltrito@polito.it (L. Scaltrito). www.elsevier.com/locate/mee Microelectronic Engineering 83 (2006) 82–85