Atomic layer processing for doping of SiGe

Atomically Controlled Processing for Group IV Semiconductors by Chemical Vapor Deposition

“…Based on the investigation of surface reaction processes, the concept of atomic layer process control 3,6,7,[9][10][11] has been demonstrated for high-performance Si 0:65 Ge 0:35 -channel p-type MOS fieldeffect transistors (pMOSFETs) with a 0.12 mm gate length by utilizing in-situ impurity-doped Si 1Àx Ge x selective epitaxy on the source/drain regions at 550 C, 12) for ultrathin P barriers in infrared SiGe/Si heterojunction internal photoemission detectors, 13) and for B and P base doping in npn and pnp hetero-bipolar transistors (HBTs). [14][15][16] In this review, we describe ultraclean low-temperature low-pressure CVD processing using SiH 4 and GeH 4 gases. The in-situ doped Si 1Àx Ge x epitaxial growth on the (100) surface in a SiH 4 -GeH 4 -dopant (PH 3 , or B 2 H 6 or SiH 3 CH 3 )-H 2 gas mixture and the self-limited reactions of hydride gases (SiH 4 , GeH 4 , NH 3 , PH 3 , CH 4 , and SiH 3 CH 3 ) on Si(100) and Ge(100) for atomic-order growth are reviewed based on the Langmuir-type adsorption and reaction scheme.…”

Base doping and dopant profile control of SiGe npn and pnp HBTs

“…The B concentration measured by SIMS is increasing with increasing B 2 H 6 flow. The B peaks show a steepness of better than 1 nm/dec (SIMS resolution limit) [7]. Compared to experiments at temperatures above 250 8C (not shown here) the process tends to get self-limited at 100 8C exposure temperature.…”

“…Selflimitation of the process is possible at atomic level when all surface sites are occupied and adsorption on Si and Ge sites is dominating. This concept has been demonstrated for atomically controlled processing using the adsorption of hydride gases on Si, Ge or SiGe [7,8]. For doping of npn and pnp HBTs, the atomic layer processing approach has been applied by performing the adsorption of B 2 H 6 and PH 3 , respectively, during an interruption of the base layer growth at low temperature [7].…”

“…It is shown that by reducing the temperature for the deposition of the undoped spacer on top of the doped part of the SiGe base steep profiles have been achieved. In addition the atomic layer doping approach [7,8] is discussed for the creation of very steep dopant profiles.…”

Threshold Voltage Control through Layer Doping of Double Gate MOSFETs

“…This doped layer in the channel of the device provides simultaneously, an intrinsic region having reasonably high mobility, less leakage current due to BTBT, less dopant fluctuation effect etc., and a doped region capable of setting the threshold voltage to the desired value. The advances in doping technology such as atomically controlled chemical vapor deposition [27][28][29] make it possible to control the concentration and location of doping profiles in extremely thin layers of Si channels very precisely and to limit the thickness of the doped layers to within a few atomic layers. The results of our simulations have shown that the characteristics of this novel device are superior to that of a device with a fully doped channel.…”