Confinement of Threading Dislocations in SIMOX with A GeSi Strained Layer
- PDF / 4,070,254 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 40 Downloads / 249 Views
CONFINEMENT OF THREADING DISLOCATIONS IN SIMOX WITH A GeSi STRAINED LAYER F. NAMAVAR*, E. CORTESI*, D.L. PERRY**, E.A. JOHNSON*, N.M. J.M. MANKE*, N.H. KARAM*, R.F. PINIZZOTTO***, and H. YANG*** * Spire Corporation, Patriots Park, Bedford, MA ** Purdue University, West Lafayette, IN *** University of North Texas, Denton, TX
KALKHORAN*,
ABSTRACT We have investigated improving the crystalline quality of epitaxial silicon grown on SIMOX by confining threading dislocations in the original Si top layer using a GeSi strained layer. Epitaxial Si/GeSi/Si structures were grown by CVD on SIMOX and Si substrates with a GeSi alloy layer about 1000 - 1500 angstroms thick with Ge concentrations of about 0-20%. A Ge concentration in the alloy layer of about 5.5% or higher appears to be necessary in order to bend any of the threading dislocations from the original SIMOX top layer. For a higher Ge concentration of about 16%, most of the threading dislocations appear to be bent and confined by the GeSi layer. In addition, the GeSi strained layers grown by CVD (at about 1000*C) appear to be high quality and no misfit dislocations were observed in the regions studied by XTEM and plane view TEM. INTRODUCTION The Separation by IMplantation of OXygen (SIMOX) process is a leading technology for the formation of silicon-on-insulator (SOI) material (1-3]. One important attribute of SIMOX material is its inherent radiation hardness since the buried Si0 2 layer separates the device region from the substrate and thus from most of the effects of ionizing radiation.
However, one problem with SIMOX has been the relatively high threading dislocation density in the silicon top layer which is detrimental for submicron CMOS or bipolar device structures. A number of methods have been investigated to improve the crystalline quality of the silicon top layer [4-8]. It has been shown that multiple implant processes as well as implantation at high temperature can significantly improve the quality of the entire silicon top layer. However, it has been observed [9,10] in SOI material that improving the quality of the silicon all the way to the insulator interface results in reduced radiation hardness because of radiation induced back channel leakage (11-13] and parasitic bipolar effects (14]. Thus, we believe that for SIMOX material also, it is desirable to improve the quality of the surface silicon in order to enhance device performance while maintaining poorer quality silicon near the oxide interface in order to enhance the radiation hardness of the material. Earlier work [15] suggested that a Ge implantation and solid phase epitaxy regrowth process can be used to improve the quality of the surface silicon without improving the quality of the silicon near the oxide interface. However, we believed that a similar effect could be achieved more easily and economically with growth of a strained GeSi layer by chemical vapor deposition (CVD). We have investigated the effectiveness of a thin epitaxial GeSi strained layer to deflect threading dislocations (from t
Data Loading...
