SiGe growth kinetics and doping in reduced pressure-chemical vapor deposition

Using a reduced pressure-chemical vapor deposition cluster tool, we have Studied the growth kinetics or Si and SiGe and the n-type and p-type doping of Si with both silane and dichlorosilane chemistries. As far as Si is concerned, a conventional behavior is found for both gases, i.e. a low-temperature region where the Si growth rate is limited by the desorption of the H atoms from the growing surface (activation energy equal to 47 kcal/mol), and a high-temperature region, where the Si growth rate is mainly piloted by the incoming flow of SiH4 or SiH2Cl2 (activation energy of 4kcal/ mol). The incorporation of B in Si is linear with the B2H6 flow (p-type doping of Si), achievable with an overall 9 x 10(16)-4 x 10(19) cm(-3) B ions concentration range. There is a sub-linear dependency of the P incorporation into Si with the PH3 flow (n-type doping of Si). A 2 x 10(16)-9 x 10(18)cm(-3) P ions concentration range can be reached with both silicon gas sources. The growth rate of boron-doped Si is virtually unaffected by increasing B2H6 flow. Meanwhile, the growth rate of phosphorous-doped Si steadily drops when the PH3 flow is increased. As far as the SiH4 + GeH4 chemistry is concerned. the Ge concentration v in the SiGe film obeys at 650degreesC the following law, as a function of the F(GeH4)/F(SiH4) mass flow ratio: x/(1 - x) = 2.7(F(GeH4)/F(SiH4)). For the SiH2Cl2 + GeH4 chemistry, x is linked at 750degreesC to the F(GeH4)/F(SiH2Cl2) mass flow ratio through the following relationship: nu(2)/(l - x) = 0,55(F(GeH4)/ F(SiH2Cl2)). The SiGe growth rate increases strongly with an increasing GeH4 flow with no apparent influence of the actual SiH4 or SiH2Cl2 flow. This is attributed to an increased hydrogen desorption caused by the presence of Ge atoms on the growing surface that frees nucleation sites for the incoming Ge and Si atoms. (C) 2002 Elsevier Science B.V. All rights reserved.