Benchmarking of HCl-Based Cyclic Deposition / Etch (CDE) and Single Deposition / Etch (DE) Processes for Selective Epitaxial Growth of SiGeC:B Films

In this paper, SiGeC:B growth behaviors at 550 °C, 10 Torr, were studied in a 300 mm industrial Reduced Pressure-Chemical Vapor Deposition reactor using a Si 2 H 6 /GeH 4 /SiH 3 CH 3 /B 2 H 6 chemistry. Carbon atoms, for both SiGeC and SiGeC:B layers, were only incorporated into substitutional sites, with concentrations up to ~ 1.4 at%. It appeared that in-situ boron doping at a level of 1x10 20 at.cm -3 did not modify the substitutional carbon incorporation. However, carbon and boron atoms were shown to compete for substitutional incorporation sites, as outlined by the increased SiGeC:B films resistivity. Cyclic Deposition / Etch (CDE) and Deposition / Etch (DE) processes were then benchmarked on blanket Si substrates and blanket Si wafers covered with 10 nm of Si 3 N 4 , with the aim to achieve selective growth on patterned wafers. The CDE process consisted of 10 cycles with deposition steps at 550 °C, 10 Torr and etch steps at 550 °C, 50 Torr with a very high HCl flow. The simpler DE process consisted in a single deposition step at 550 °C, 10 Torr, followed by a single etch step at 550, 575 or 600 °C, 600 Torr, with a very low HCl flow. CDE and DE processes both resulted in a rather low etch selectivity of 1.8 and produced slightly rough SiGeC:B surfaces. Finally, it was shown that the use of a HCl-based CDE process is not a viable solution to obtain high quality SiGeC:B films on patterned wafers at low growth temperatures. Meanwhile, DE yielded higher quality if slightly rough SiGeC:B layers.