Selective epitaxial growth of boron- and phosphorus-doped Si and SiGe for raised sources and drains

The aim of this study being the selective epitaxial growth of either intrinsic or in situ doped raised sources and drains, we have studied the growth kinetics and the boron and phosphorus doping of Si and SiGe with a dichlorosilane+germane + hydrochloric acid chemistry. Adding HCI to SiH2O2 + GeH4 leads at the same time to a strong decrease of the Si or SiGe growth rate and to a significant increase in the germanium content of the layers. Switching from bulk to Sol substrates with a very thin Si top layer induces a significant decrease in the Si growth rate, which we have quantified as a function of the buried oxide thickness. As far as the doping at 800degreesC of Si layers grown with a SiH2Cl2 + HCl chemistry is concerned, we have obtained a peak for B ions at 1.3 x 10(20) cm(-3). Beyond this peak, poly-crystalline Si:B layers are formed. Meanwhile, the phosphor-us ion concentration in Si increases monotonously with the PH3 flow, reaching a maximum value equal to 1.3 x 10(19)cm(-3). Switching over to Si0.8Ge0.2 (grown at 700degreesC with a chlorinated chemistry) enables to drastically reduce the resistivity (minima: 9.75 x 10(-4) Omegacm for SiGe:P and 1.02 x 10(-3) Omegacm for SiGe:B) and thus meet, for a lower thermal budget, the requirements of the forthcoming 45 run gate length technology node (not reached for Si:P). Finally, as far as growth kinetics are concerned, carrying out some heavy boron (phosphorus) doping induces a strong increase (decrease) of the Si or SiGe growth rate and a reduction (strong increase) of the apparent Ge concentration. (C) 2004 Elsevier B.V. All rights reserved.