N-Channel Mos Transistors below 0.5 μm with Ultra-Shallow Channels formed by Low Temperature Selective Silicon Epitaxy

1995 ◽  
Vol 387 ◽  
Author(s):  
P. L. Huang ◽  
K. Seastrand ◽  
K. E. Violette ◽  
J. Wolf ◽  
M. C. Öztürk
Keyword(s):  
Low Temperature ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Deep Submicron ◽  
Ultra High Vacuum ◽  
Doping Profile ◽  
Doping Density ◽  
Silicon Epitaxy ◽  
Threshold Voltages ◽  
Channel Lengths

AbstractIn this paper, we present an application of ultra high Vacuum Rapid Thermal Chemical Vapor Deposition (UHV-RTCVD) to MOSFET channel engineering. MOSFETs were fabricated on ultra-thin (200 Å), moderately doped (l×1017 - 6×1018 cm−3) p-type epitaxial layers selectively grown in active areas defined by standard LOCOS isolation. The selective epitaxy was achieved using a novel Si2H6Cl2/B2H6 process at 800°C and at a total pressure under 30 mtorr. Low thermal budget processing techniques were emphasized to minimize spread in the channel doping profile. Threshold voltages below 0.6 V were obtained. Transistors with effective channel lengths of 0.45 μm exhibit subthreshold slopes from 78 to 92 mV/decade determined by the epitaxial channel doping density. We have found that by using ultra-thin channels, expected transconductance degradation at high channel doping densities can be minimized. Furthermore, ultra-thin channels help reduce the sensitivity of the threshold voltage on substrate bias. The results show that low temperature selective silicon epitaxy can be used to form ultra-shallow channel doping profiles that can enhance the performance of MOSFETs in the deep submicron regime.

Low temperature selective silicon epitaxy by ultra high vacuum rapid thermal chemical vapor deposition using Si2H6, H2 and Cl2

1996 ◽  
Vol 68 (1) ◽  
pp. 66-68 ◽  
Author(s):  
Katherine E. Violette ◽  
Patricia A. O’Neil ◽  
Mehmet C. Öztürk ◽  
Kim Christensen ◽  
Dennis M. Maher
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Vapor Deposition ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Thermal Chemical Vapor Deposition ◽  
Silicon Epitaxy

Sub-Half Micron Elevated SourceDrain NMOSFETS by Low Temperature Selective Epitaxial Deposition

1996 ◽  
Vol 429 ◽  
Author(s):  
J. Sun ◽  
R. F. Bartholomew ◽  
K. Bellur ◽  
P. A. O'Neil ◽  
A. Srivastava ◽  
...  
Keyword(s):  
Low Temperature ◽  
Epitaxial Growth ◽  
High Vacuum ◽  
Chemical Vapor ◽  
High Growth ◽  
Deposition Process ◽  
Deep Submicron ◽  
Ultra High Vacuum ◽  
Gas Source ◽  
Drain Bias

AbstractIn this paper we report the first NMOSFETs with elevated S/D selectively deposited by ultra high vacuum rapid thermal chemical vapor deposition (UHV-RTCVD). The deposition process included an in-situ vacuum prebake (750 °C for 10 sec) followed by selective epitaxial growth (SEG) at 800 °C. Si2H6 was used as the silicon gas source instead of the more commonly used SiH4 and SiH2Cl2 in order to achieve high growth rates at low pressure. To prevent nucleation from occurring on insulator surfaces during growth, an etching mechanism was introduced by the addition of Cl2. The gases included 100 sccm of 10% Si2H6 in H2 and 2 sccm of Cl2 at a process pressure of 24 mTorr. An epitaxial growth rate of 160 nm/min has been achieved. The final epi thickness was around 0.1 μm. The S/D junctions were formed via ion implantation into the epi. The subsequent RTA (10 sec at 950 °C) resulted in an effective junction depth about 75 nm beneath the starting Si substrate. Process and device simulations reveal the importance of maintaining a shallow LDD junction for deep submicron devices by using low temperature selective deposition. MOSFETs exhibit good subthreshold characteristics with subthreshold swing of 86 mV/dec at a drain bias of 2.5 V, and threshold variations due to charge sharing and drain-induced-barrierlowering (DIBL) were moderate for Leff down to 0.35 μm. The gate-induced junction leakage current is below 2 pA/μm at a bias of 2.5 V.

Remote Plasma-Enhanced Chemical Vapor Deposition of Epitaxial Silicon on Silicon (100) at 150°C

1989 ◽  
Vol 165 ◽  
Author(s):  
T. Hsu ◽  
B. Anthony ◽  
L. Breaux ◽  
S. Banerjee ◽  
A. Tasch
Keyword(s):  
Chemical Vapor Deposition ◽  
Low Temperature ◽  
Vapor Deposition ◽  
Hydrogen Plasma ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ex Situ ◽  
Epitaxial Silicon ◽  
Remote Plasma ◽  
Silicon Epitaxy

AbstractLow temperature processing will be an essential requirement for the device sizes, structures, and materials being considered for future integrated circuit applications. In particular, low temperature silicon epitaxy will be required for new devices and technologies utilizing three-dimensional epitaxial structures and silicon-based heterostructures. A novel technique, Remote Plasma-enhanced Chemical Vapor Deposition (RPCVD), has achieved epitaxial silicon films at a temperature as low as 150°C which is believed to be the lowest temperature to date for silicon epitaxy. The process relies on a stringent ex-situ preparation procedure, a controlled wafer loading sequence, and an in-situ remote hydrogen plasma clean of the sample surface, all of which provide a surface free of carbon, oxygen, and other contaminants. The system is constructed using ultra-high vacuum technology (10-10 Torr) to achieve and maintain contaminantion-free surfaces and films. Plasma excitation of argon is used in lieu of thermal energy to provide energetic species that dissociate silane and affect surface chemical processes. Excellent crystallinity is observed from the thin films grown at 150°C using the analytical techniques of Transmission Electron Microscopy (TEM) and Nomarski interference contrast microscopy after defect etching.

Silicon epitaxy using tetrasilane at low temperatures in ultra-high vacuum chemical vapor deposition

2016 ◽  
Vol 444 ◽  
pp. 21-27 ◽  
Author(s):  
Ramsey Hazbun ◽  
John Hart ◽  
Ryan Hickey ◽  
Ayana Ghosh ◽  
Nalin Fernando ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Low Temperatures ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Ultra High Vacuum ◽  
Silicon Epitaxy

In-Situ Doped Multi-Layer Epitaxial Structures with Abrupt Doping Transitions by Ultra High Vacuum Rapid Thermal Chemical Vapor Deposition (UHV-RTCVD)

1994 ◽  
Vol 342 ◽  
Author(s):  
Mehmet C. ÅztÖjrk ◽  
S. Muhsin ◽  
Ibrahim Ban ◽  
Gari Harris ◽  
Mahesh K. Sanganeria ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Field Effect Transistors ◽  
High Vacuum ◽  
Chemical Vapor ◽  
Gate Oxide ◽  
Ultra High Vacuum ◽  
Dopant Diffusion ◽  
Short Channel ◽  
Doping Density

ABSTRACTIn this work, we have studied boron doped multi-layer epitaxial structures as active regions of deep submicron (< 0.25 gtm)metal oxide silicon field effect transistors (MOSFETs).The structures were formed by ultra high vacuum chemical vapor deposition (UHV-RTCVD) using Si2H6 and B2H6 as the source gases and H2 as the carrier gas at 750°C - 800°C and at a total pressure of 80 mTorr. With the high growth rates provided by Si2H6, thermal budgets were kept below the limit of boron diffusion in Si resulting in extremely abrupt doping transitions pushing the depth resolution limits of secondary ion mass spectroscopy. The structures consist of three epitaxial layers with thicknesses ranging from 100 A to 625 T. The top layer on which the gate oxide is formed is lightly doped (lxl016 cm-3) to minimize vertical electrical field and ionized impurity scattering for higher MOSFET channel mobility. The second layer is doped to lx1018 cm-3 for suppression of punchthrough short channel effects and finally the third layer is doped to lx 1017 cm-3 to decrease the parasitic source/drain junction capacitance that will result from the relatively high doping density of the intermediate layer. To minimize dopant diffusion in Si, low temperature (or low thermal budget) processes were employed for gate oxidation and polysilicon implant activation. A typical source/drain activation anneal was also included in sample preparation in order to simulate complete MOSFET fabrication assuming remaining steps could be carried out at lower temperatures with little contribution to dopant diffusion. Our results indicate that after all process steps a lightly doped region can still be obtained under the gate oxide with sufficient thickness to contain the MOSFET inversion layer. In these structures, the threshold voltage is determined by the doping density and thickness of the top two layers and can be easily tailored to the desired value by optimizing these parameters. With the range of parameters used in this study, our measurements show threshold voltages within the range desired for 0.1 µm MOSFETs.

Low Temperature Selective Silicon Epitaxy Using Si2H6, H2 and Cl2 in Ultra High Vacuum Rapid Thermal Chemical Vapor Deposition

1995 ◽  
Vol 387 ◽  
Author(s):  
Katherine E. Violette ◽  
Mehmet C. Öztürk ◽  
Patricia A. O'Neill ◽  
Kim Christensen ◽  
Dennis M. Maher
Keyword(s):  
Growth Rate ◽  
Flow Rate ◽  
High Vacuum ◽  
Chemical Vapor ◽  
High Growth ◽  
Ultra High Vacuum ◽  
Thermal Chemical Vapor Deposition ◽  
Silicon Epitaxy ◽  
Low Pressures ◽  
Wafer Manufacturing

In this paper we present for the first time the use of the Si2H6/H2/Cl2 chemistry for selective silicon epitaxy in a rapid thermal CVD reactor. Depositions were carried out in an ultra-high vacuum rapid thermal chemical vapor deposition (UHV-RTCVD) system designed and constructed at North Carolina State University. Experiments were performed over a temperature range of 650°C to 850°C and over a pressure range of 22 to 25 mTorr using a flow rate 100 sccm of 10% Si2H6 in H2 and 0 to 10 sccm of Cl2. Deposited layer thicknesses were evaluated using a combination of interferometry and profilometry. Without Cl2 over the range of 650°C to 850°C, the growth rate is approximately constant at 160 nm/min. exhibiting a weak dependence on temperature. A clear advantage of Si2H6 is that high growth rates compatible with single wafer manufacturing can be obtained at very low pressures thus minimizing the introduction of contaminants by the process gases. With the addition of C12, the growth rate is suppressed at temperatures below 800°C, but, at 800°C and above, it is affected only slightly for Cl2 flow rates below 5 sccm. As the Cl2 flow rate is increased past 5 sccm, the growth rate at higher temperatures becomes a strong function of Si2H6:Cl2 ratio. Excellent selectivity with respect to patterned SiO2 and Si3N4 was obtained over the entire Cl2 flow rate range suggesting that even lower Cl levels may be sufficient for selective deposition. This implies that selectivity can be obtained with Si:Cl ratios much lower than those introduced by the more commonly used SiH2Cl2 chemistry. Furthermore, because Si2H6 can provide high growth rates at very low pressures, the total partial pressures of Cl2 and resulting chlorinated species can be significantly lower than typically required for selectivity. Our results indicate that C12 successfully enhances selectivity and yields highly selective depositions for process durations well within the practical limits of single wafer manufacturing.

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