Evaluation of Vacancy-Type Defects in Simox Substrates by a Slow Positron Beam and a Pulsed Positron Beam
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EVALUATION OF VACANCY-TYPE DEFECTS IN SIMOX SUBSTRATES BY A SLOW POSITRON BEAM AND A PULSED POSITRON BEAM H.KAMETANI*, H.AKIYAMA*, Y.YAMAGUCHI*, M.KOUMARU*, Y.TABUKI**, S.TANIGAWA**,A.UEDONO***, S.WATAUCHI***, Y.UJIHIRA*** R.SUZUKI****, H.OHGAKI****, T.MIKADO****
L.WEI**,
*Mitubishi Electric Corporation, Tsukaguchi-Honmachi, Amagasaki, Hyogo 661,Japan **Institute of Material Science, University of Tukuba, Tennoudai, Tsukuba, Ibaragi 305,Japan ***Department of Industrial Chemistry, Faculty of Engineering, University of Tokyo, Hongo, Bunkyou-ku, Tokyo l13,Japan ****Electrotechnical Laboratory,Umezono,Tsukuba,Ibaragi 305,Japan ABSTRACT Slow/monoenergetic positron beams and pulsed positron beams have been used as a non-destructive probe to investigate vacancy-type defects in SIMOX substrates which were formed by high - dose oxygen implantation and high-temperature annealing. To obtain depth profiles of vacancy-type defects, a positron beam in the 0-3OkeV energy range was used. Doppler broadened annihilation spectrum and positron lifetime were measured as a function of incident positron energy. These measurements show the following results ; vacancy -type defects exist near the surface of the top silicon layer even if the specimen was analyzed as defect -free Silicon by XTEM, and in the case of the as-implanted specimen, cavities in diameter of about 50-200A are created in the top silicon layer and they include high pressure gases. INTRODUCTION One of the most promising silicon on insulator(SOI) substrates available for device fabrication is produced by highdose oxygen-ion implantation under high substrate temperature followed by an appropriate high temperature annealing.[l-3] The resulting SOI material is often called SIMOX(separation by implanted oxygen). A crystalline Si/buried SiO2 /crystalline Si structure is created by oxygen implantation and subsequent high-temperature annealing. Effects of the implantation on the crystallinity of the top Si layer have been investigated using various analytical methods, such as Rutherford backscattering spectroscopy (RBS)[4-5], and cross-sectional transmission electron microscopy (XTEM)[6]. Although the RBS and XTEM methods have yielded useful information on the crystallinity, those methods don't give specific information on vacancy-type defects in the substrates. In the present paper, we made slow positron beam studies on SIMOX substrates containing implanted oxygen. Particular attention is paid to the depth profile of defects. EXPERIMENTAL SIMOX substrates were produced by implanting oxygen ions 18 using a high current oxygen implanter . A dose of 1-2.2x10 cm-2 oxygen ions implanted into (100)p-type silicon with resistivity 10 0cm. The substrate temperature during oxygen implantation was Mat. Res. Soc. Symp. Proc. Vol. 262. 01992 Materials Research Society
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0 0 After the implantation, each of maintained at 550 C and 450 C. them was annealed at a high temperature over 1300 °C for 8 hours in an Ar+0 2 atmosphere. The specific parameters are given in Table 1. A specimen #4
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