Epitaxial Growth of B-Doped SiGe Films Using Si-GeH 4 -B 2 H 6 MBE
- PDF / 323,730 Bytes
- 6 Pages / 420.48 x 639 pts Page_size
- 57 Downloads / 240 Views
EPITAXIAL GROWTH OF B-DOPED SiGe FILMS USING Si-GeH 4 -B 2 H6 MBE YASUO KUNII NTT LSI Laboratories. 3-1 Morinosato Wakamiya, Kanagawa, 243-01 Japan
Atsugi-shi,
ABSTRACT
are epitaxialHigh-crystalline-quality B-doped SiGe films ly grown on Si(100) substrates using the Si-GeH4 -B 2 H6 MBE system. Both Ge and B profiles in the B-doped SiGe layer are readiThis technique should ly controlled using the present system. be very promising in the bandgap engineering of SiGe base HBTs. INTRODUCTION Recent intensive studies on SiGe base hetero-Junction bipolar transistors (HBTs) have demonstrated that the low-temperature epitaxial growth technique looks promising for highThe CVD techniques with B2 H6 -gasspeed IC fabrication [1-5]. doping and Ge-concentration-control have been shown to be useful for epitaxial base formation in the high-performance HBT procHowever, MBE techniques have the advantage of lowess [3,5]. base-pressure making it easy to keep the substrate surface clean. As surface cleanliness is essential in the growth of high-quality epitaxial layers, the author has studied the growth of B-doped SiGe films using the Si-GeH4 -B 2 H6 MBE system. The present Si-GeH4 -B 2 H6 MBE is a kind of Si MBE in a reactive-gas-ambient, or in other terms, a hybrid-source MBE. Materials grown using hybrid-source MBE's are SiOx using 02 8-SiC using C 2 H2 [9], etc. The [6,71, SiNx using NH3 [8]., typical ranges for the base pressure and working pressure of hybrid-source MBE's fall between those of solid-source MBE (10-10 Torr base and 10-8 Torr working) and gas-source MBE (10-9 Torr to base and 10-4 Torr working). Due to this, it is rather easy keep the substrate surface clean, by using a hybrid-source MBE In addition, system in comparison with a gas-source MBE system. in contrast with conventional total-gas-source growth systems (gas-source MBE, UHV/CVI), RT-CVD, etc.), the Si-GeH4 hybridsource MBE system primarily controls the film deposition rate (D.R.) through the use of Si flux. Some deviations in other growth parameters such as deposition temperature or GeH 4 flow rate have limited effect on the film D.R., because the sticking probability for the Si molecular beam is almost unity, over a wide range of substrate temperatures and in the relatively low pressure range ( Si-GeHA-B2H
S12 I0
Co
I0 0.05 Fig. 8
0.10
Depth (erm) Control of B depth profile by B 2 H6 pre-doping.
564
The transient layer is face segregation phenomena occurred. considerably thick in the B depth profile, as shown by Fig. 7. The introduction of B 2 H6 gas prior to Si MBE is effective in decreasing the thickness of the transient layer, as shown in Fig. 8. Crystalline quality The crystalline quality of as-deposited SiGe MBE layers was cross-sectional or plane TEM and Nomarski microevaluated by No crystalline defects scope observation after defect-etching. SiGe films grown in the commensurate growth were observed in range both with and without B-doping when Tsub = 580°C. SUMMARY of high-crystalline-quality The author studied the growth on Si(l00) substrat
Data Loading...
