| 1. |
- Erdal, Suvar, et al.
(författare)
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High frequency performance of SiGeCHBTs with selectively & non-selectively grown collector
- 2004
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T114, s. 138-141
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Tidskriftsartikel (refereegranskat)abstract
- Two high-frequency heterojunction bipolar transistor (HBT) architectures based on SiGeC have been fabricated and characterized. Different collector designs were applied either by using selective epitaxial growth doped with phosphorous or by non-selective epitaxial growth doped with arsenic. Both designs have a non-selectively deposited SiGeC base doped with boron and a poly-crystalline emitter doped with phosphorous. Both HBT designs exhibit similar electrical characteristics with a peak DC current gain of around 1600 and a BVCEO of 1.8V. The cut-off frequency (f(T)) and maximum frequency of oscillation (f(max)) vary from 40-80 GHz and 15-30 GHz, respectively, depending on lateral design relations. Good high frequency performance for a device with a selectively grown collector is demonstrated for the first time.
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| 2. |
- Haralson, Erik, 1975-
(författare)
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Device design and process integration for SiGeC and Si/SOI bipolar transistors
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- SiGe is a significant enabling technology for therealization of integrated circuits used in high performanceoptical networks and radio frequency applications. In order tocontinue to fulfill the demands for these applications, newmaterials and device structures are needed. This thesis focuseson new materials and their integration into heterojunctionbipolar transistor (HBT) structures as well as using devicesimulations to optimize and better understand the deviceoperation. Specifically, a SiGeC HBT platform was designed,fabricated, and electrically characterized. The platformfeatures a non-selectively grown epitaxial SiGeC base,in situdoped polysilicon emitter, nickel silicide,LOCOS isolation, and a minimum emitter width of 0.4 μm.Alternately, a selective epitaxy growth in an oxide window wasused to form the collector and isolation regions. Thetransistors exhibited cutoff frequency (fT) and maximum frequency of oscillation (fMAX) of 40-80 GHz and 15-45 GHz, respectively.Lateral design rules allowed the investigation of behavior suchas transient enhanced diffusion, leakage current, and theinfluence of parasitics such as base resistance and CBC. The formation of nickel silicide on polysiliconSiGe and SiGeC films was also investigated. The formation ofthe low resistivity monosilicide phase was shown to occur athigher temperatures on SiGeC than on SiGe. The stability of themonosilicide was also shown to improve for SiGeC. Nickelsilicide was then integrated into a SiGeC HBT featuring aselectively grown collector. A novel, fully silicided extrinsicbase contact was demonstrated along with the simultaneousformation of NiSi on thein situdoped polysilicon emitter. High-resolution x-ray diffraction (HRXRD) was used toinvestigate the growth and stability of SiGeC base layers forHBT integration. HRXRD proved to be an effective, fast,non-destructive tool for monitoring carbon out-diffusion due tothe dopant activation anneal for different temperatures as wellas for inline process monitoring of epitaxial growth of SiGeClayers. The stability of the SiGe layer with 0.2-0.4 at% carbonwhen subjected to dopant activation anneals ranging from1020-1100°C was analyzed by reciprocal lattice mapping.It was found that as the substitutional carbon increases theformation of boron clusters due to diffusion is suppressed, buta higher density of carbon clusters is formed. Device simulations were performed to optimize the DC and HFperformance of an advanced SiGeC HBT structure with low baseresistance and small dimension emitter widths. The selectivelyimplanted collector (SIC) was studied using a design ofexperiments (DOE) method. For small dimensions the lateralimplantation straggle has a significant influence on the SICprofile (width). A significant influence of the SIC width onthe DC gain was observed. The optimized structure showedbalanced fT/fMAXvalues of 200+ GHz. Finally, SOI BJT transistorswith deep trench isolation were fabricated in a 0.25μmBiCMOS process and self-heating effects were characterized andcompared to transistors on bulk silicon featuring deep trenchand shallow trench isolation. Device simulations based on SEMcross-sections and SIMS data were performed and the resultscompared to the fabricated transistors. Key words:Silicon-Germanium(SiGe), SiGeC,heterojunction bipolar transistor(HBT), nickel silicide,selectively implanted collector(SIC), device simulation, SiGeClayer stability, high resolution x-ray diffraction(HRXRD),silicon-on-insulator(SOI), self-heating.
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| 3. |
- Haralson, Erik, et al.
(författare)
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Device design for a raised extrinsic base SiGe bipolar technology
- 2004
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Ingår i: Solid-State Electronics. - : Elsevier BV. - 0038-1101 .- 1879-2405. ; 48:11-okt, s. 1927-1931
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Tidskriftsartikel (refereegranskat)abstract
- The impact of emitter, inside spacer, and SIC lateral scaling on the AC and DC performance of a raised extrinsic base SiGe HBT has been investigated using the ISE TCAD simulation package and design of experiments methods. Strong first order effects for all three variables were observed while the interactions of the variables had a weaker effect. It was found that as the emitter size shrinks towards 0.1 mum the impact of changes to inside spacer and SIC width on the current gain increased. The response surface design led to an optimized simulated transistor featuring f(T) and f(MAX) values of 214 and 332 GHz, respectively.
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| 4. |
- Haralson, Erik, et al.
(författare)
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HRXRD analysis of SiGeC layers for BiCMOS applications
- 2004
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Konferensbidrag (refereegranskat)abstract
- The use of HRXRD for the monitoring of the dopant activation anneal through the detection of carbon outdiffusion has been demonstrated. The advantages of HRXRD over other measurement techniques for in-line epi-growth monitoring are also discussed. HRXRD reciprocal space mapping was used to study the SiGe layer stability as a function of carbon concentration for vertically scaled layers designed for high performance BiCMOS applications. It was found that as the carbon concentration is increased there is a reduction of boron cluster formation, but an increase in defect density is also observed.
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| 5. |
- Haralson, Erik, et al.
(författare)
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Influence of self heating in a BiCMOS on SOI technology
- 2004
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Ingår i: ESSCIRC 2004. - NEW YORK : IEEE. - 0780384784 ; , s. 337-340
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Konferensbidrag (refereegranskat)abstract
- Self heating in a 0.25mum BiCMOS technology with different isolation structures is characterized. Thermal resistance values for single- and multiple-emitter devices are extracted and reported. The dependence of the thermal resistance on the emitter aspect ratio is critical to take into consideration when determining the isolation scheme for devices. 2-D electro-thermal simulations are performed and compared to experimental results. The impact of metallization on the self-heating in the device is examined through simulations.
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| 6. |
- Haralson, Erik, et al.
(författare)
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NiSi integration in a non-selective base SiGeCHBT process
- 2005
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 8:03-jan, s. 245-248
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Tidskriftsartikel (refereegranskat)abstract
- A self-aligned nickel silicide (salicide) process is integrated into a non-selective base SiGeC HBT process. The device features a unique, fully silicided base region that grows laterally under the emitter pedestal. This Ni(SiGe) formed in this base region was found to have a resistivity of 23-24 muOmega cm. A difference in the silicide thickness between the boron-doped SiGeC extrinsic base region and the in situ phosphorous-doped emitter region is observed and further analyzed and confirmed with a blanket wafer silicide study. The silicided device exhibited a current gain of 64 and HF device performance of 39 and 32 GHz for f(t) and f(MAX), respectively.
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| 7. |
- Haralson, Erik, et al.
(författare)
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The effect of C on emitter-base design for a single-polysilicon SiGe : C HBT with an IDP emitter
- 2004
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 224:1-4, s. 330-335
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Tidskriftsartikel (refereegranskat)abstract
- A differential epitaxy SiGe:C heterojunction bipolar junction transistor (HBT) design is reported and used to study the effect of carbon on junction formation as well as the effect of lateral design parameters on ac and dc performance. The device exhibits a high current gain (beta) of 1700 and a BVCEO of 1.8 V. The peak cutoff frequency (f(T)) and maximum oscillation frequency (f(MAX)) are 73 and 17 GHz, respectively. The effect of emitter overlap on f(T) was minimal, but it had a strong impact on dc performance. LOCOS opening size strongly impacted both ac and dc performance. In addition, the effect of carbon, base cap thickness, and rapid thermal anneal (RTA) temperature on the emitter-base (E-B) junction formation was studied.
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| 8. |
- Suvar, Erdal, et al.
(författare)
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As- or P-doped Si layers grown by RPCVD for emitter application in SiGeCHBTs
- 2004
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Ingår i: Physica Scripta. - 0031-8949 .- 1402-4896. ; T114, s. 34-36
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Tidskriftsartikel (refereegranskat)abstract
- A new module for the emitter formation in a bipolar transistor is presented. Arsenic- or phosphorus-doped polycrystalline silicon layer for the emitter formation is deposited in a reduced pressure chemical vapor deposition reactor using silane as the silicon source gas. Characteristics such as the carrier concentration, conductivity, surface morphology, and thermal stability of the polycrystalline-silicon layer as well as the influence this layer has on a SiGeC transistor structure during the drive-in step area studied. The active carrier concentration of the as-grown sample is strongly dependent on the deposition temperature, especially arsenic doped layers which exhibit more than one order of magnitude difference. However, the carrier concentration for the As- or P-doped layer were comparable to that of a standard in-situ doped poly-crystalline layer after a dopant activation at 925 degrees C for 10s.
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| 9. |
- Suvar, Erdal, et al.
(författare)
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Characterization of leakage current related to a selectively grown collector in SiGeC heterojunction bipolar transistor structure
- 2004
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Ingår i: Applied Surface Science. - : Elsevier BV. - 0169-4332 .- 1873-5584. ; 224:1-4, s. 336-340
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Tidskriftsartikel (refereegranskat)abstract
- Sources of base-collector and base-emitter leakage current in a SiGeC-based heterojunction bipolar transistor (HBT) with a selectively grown and chemical-mechanical polished (CMP) collector are discussed. Transmission electron microscopy and electrical measurement have been applied to investigate the leakage current. It has been demonstrated that the edge-located defects generated by selective epitaxy process are the origin of the junction leakage.
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| 10. |
- Östling, Mikael, et al.
(författare)
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High performance SiGeC HBT technology for radio frequency applications
- 2004
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Ingår i: 2004 Asia-Pacific Radio Science Conference - Proceedings. ; , s. 480-483
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Konferensbidrag (refereegranskat)abstract
- In this paper, the current status of SiGeC bipolar technologies for high-speed and wireless applications is reviewed. The key process features and radio frequency (RF) performance of advanced SiGe bipolar processes are summarized. The different approaches to form a self-aligned base-emitter structure with minimum parasitics are discussed. SiGe:C epitaxy allows very good profile control of the narrow base doping peak, which enables cut-off frequencies above 300 GHz. Downscaling of device dimensions for improved RF performance is also investigated using TCAD simulations. Finally, novel device structures using SOI substrates are discussed.
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