A Benchmark of Germane and Digermane for the Low Temperature Growth of Intrinsic and Heavily in-situ Boron-Doped SiGe. (18th August 2016)

• Record Type: Journal Article
• Authors: Hartmann, Jean-Michel; Aubin, Joris; Barnes, Jean-Paul
• Is Part Of: ECS transactions. Volume 75:Number 8(2016)
• Page Start: 281
• Page End: 293
• Publication Date: 2016-08-18
• Subjects: Electrochemistry -- Periodicals; Electrochemistry; Periodicals; Electronic journals; Electronic journal; 541.37
• DOI: 10.1149/07508.0281ecst
• Languages: English
• ISSNs: 1938-5862

Abstract

Abstract : We have benchmarked germane and digermane for the low temperature growth of SiGe and SiGe:B (with disilane as the Si gaseous precursor). At 500°C, 20 Torr, the SiGe growth rate increased linearly with the Ge flow. It was 8 to 10 times higher with Ge2 H6 than with GeH4, however. Ge atoms were otherwise 4 times more likely to incorporate in SiGe films with Ge2 H6 than with GeH4 . The use of GeH4 led to an exponential increase of the 20 Torr SiGe growth rate with temperature (42 kcal. mol. -1 activation energy), together with a slight linear decrease of x. The situation was different with Ge2 H6 . As T increased, we had a slight exponential increase of the SiGe growth rate (Ea = 15 kcal. mol. -1 ) and a huge linear decrease of the Ge content. Adding HCl to Si2 H6 + Ge2 H6 otherwise led at 500 °C, 20 Torr to a significant decrease of the growth rate, together with a significant Ge concentration increase. Finally, we have investigated the 500°C, 20 Torr growth of SiGe:B layers (with a Si2 H6 + Ge2 H6 + B2 H6 chemistry). A marked increase of the SiGe:B growth rate with the B2 H6 flow was observed, together with a less than linear decrease of the Ge concentration. The lowest resistivity, e.g. 4.3x10 -4 Ω.cm, was obtained for F(B2 H6 )/F(H2 ) = 2.5x10 -6 . For higher B2 H6 flows, we had a resistivity re-increase, which was likely due to the crystalline quality degradation then the transformation into poly-SiGe:B evidenced in X-Ray Diffraction.