| 1. |
- Balestra, F., et al.
(författare)
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NANOSIL network of excellence-silicon-based nanostructures and nanodevices for long-term nanoelectronics applications
- 2008
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 11:5-6, s. 148-159
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Tidskriftsartikel (refereegranskat)abstract
- NANOSIL Network of Excellence [NANOSIL NoE web site < www.nanosil-noe.eu >], funded by the European Commission in the 7th Framework Programme (ICT-FP7, no 216171), aims at European scale integration of the excellent European research laboratories and their capabilities in order to strengthen scientific and technological excellence in the field of nanoelectronic materials and devices for terascale integrated circuits (ICs), and to disseminating the results in a wide scientific and industrial community. NANOSIL is exploring and assessing the science and technological aspects of nanodevices and operational regimes relevant to the n+4 technology node and beyond. It encompasses projects on nanoscale CMOS and beyond-CMOS. Innovative concepts, technologies and device architectures are proposed-with fabrication down to the finest features, and utilising a wide spectrum of advanced deposition and processing capabilities, extensive characterization and very rigorous device modeling. This work is carried out through a network of joint processing, characterization and modeling platforms. This critical interaction strengthens European integration in nanoelectronics and will speed up technological innovation for the nanoelectronics of the next two to three decades.
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| 2. |
- Carvahlo, A., et al.
(författare)
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Studies of the VO centre in Ge using first principles cluster calculations
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 9:4-5, s. 489-493
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Tidskriftsartikel (refereegranskat)abstract
- The small or near-zero band gap of germanium found by supercell local density functional treatments causes difficulties in the study of the properties of charged defects in Ge. Here, we use large H-terminated Ge clusters together with a non-linear core corrected (NLCC) Ge pseudopotential to explore the structure, vibrational and electrical properties of the vacancy-oxygen complex (VO). The cluster possesses a gap sufficiently wide to contain defect related energy levels, thus allowing us to model the three charge states of the defect. The local vibrational modes (LVM) calculated for the neutral (VO0), negatively charged (VO-) and double negative (VO=) defect are 602, 684 and 694 cm- 1, and can be favourably compared with experimental values of 621, 669 and 716 cm- 1, respectively [Markevich VP, et al. Physica B 2003; 340-2, 844-8]. Using substitutional gold (Aus) as a marker defect, electric levels of VO are found at E (-/ 0) = Ev + 0.30 eV and E (= /-) = Ec - 0.29 eV, in excellent agreement with the respective experimental enthalpies for hole and electron emission Δ Hh (-/ 0) ≃ 0.32 eV and Δ He (= /-) = 0.26 eV, respectively. Finally, the migration, dissociation and reorientation energies of the defect are also reported.
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| 3. |
- Carvalho, A., et al.
(författare)
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Density-functional theory study of Au, Ag and Cu defects in germanium
- 2008
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 11:5, s. 340-343
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Tidskriftsartikel (refereegranskat)abstract
- Gold, silver and copper defects in germanium are modeled using density functional theory. The structures and electrical properties of the substitutional metals are calculated in excellent agreement with experiment. Interstitial Au, Ag and Cu are found to be shallow donors, in disagreement with a previous assignment of Cui to a hole trap in the lower half of the gap. Substitutional-interstitial metal (Mi - Ms) pairs and metal-vacancy pairs (Ms - V) are also investigated.
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| 4. |
- Christensen, J. S., et al.
(författare)
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Phosphorus diffusion in the presence of threading dislocations in strain relaxed SiGe films
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 9:4-5, s. 650-654
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Tidskriftsartikel (refereegranskat)abstract
- We have studied phosphorus diffusion in strain relaxed Si1-xGex films (x = 0.1 and 0.2) by secondary ion mass spectrometry (SIMS). The relaxed films were grown with low-pressure chemical vapor deposition (LPCVD) on a Si substrate followed by a graded SiGe layer. Two sets of samples were prepared under different growth conditions, and by transmission electron microscopy (TEM) it was shown that these conditions resulted in one set of samples containing a high density of threading dislocations in the relaxed films, and one set with a low dislocation density. The SIMS profiles of the phosphorus distributions in the samples, after annealing in N-2-ambient in the temperature range of 700-950 degrees C, show that the phosphorus diffusion is significantly faster in the films with the high dislocation density. Furthermore, the data suggests that the fast diffusion is due to a higher mobility of the diffusing complex rather than an increase in the point defect concentration mediating the diffusion, a result which indicates that the threading dislocations may act as channels for the rapid dopant diffusion in SiGe.
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| 5. |
- Coutinho, J., et al.
(författare)
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Ab initio modeling of defect levels in Ge clusters and supercells
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 9:4-5, s. 477-483
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Tidskriftsartikel (refereegranskat)abstract
- Most density-functional studies of defects in semiconductors invariably use (i) a supercell that imitates the host crystal, as well as (ii) a local treatment of the exchange-correlation potential. The first approximation has had an enormous success in many materials, provided that the size of cell is large enough to minimize long-range interactions between the infinite lattice of defects. For instance, these may arise from strain fields or from the overlap between shallow defect states. The second approximation, when combined with the periodic boundary conditions, leads to an essentially metallic density of states in Ge, which can compromise any investigation of electronic transitions involving gap levels. Here, we report on two approaches to surmount these difficulties, namely (i) to open the gap by reducing the host to a Ge cluster of atoms whose states are confined by a surface potential and (ii) to use supercells, but choosing carefully the Brillouin zone sampling scheme, taking k-points that minimize the admixture between defect-related gap states and the host density of states. These methods are utilized in the calculation of the electronic structure of the vacancy, divacancy, and vacancy-donor pairs in Ge
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| 6. |
- Gomeniuk, Y., et al.
(författare)
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Low-temperature conductance measurements of surface states in HfO2-Si structures with different gate materials
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 9:6, s. 980-984
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Tidskriftsartikel (refereegranskat)abstract
- Metal-oxide-semiconductor capacitors based on HfO2 gate stack with different metal and metal compound gates (Al, TiN, NiSi and NiAlN) are compared to study the effect of the gate electrode material on the trap density at the insulator-semiconductor interface. C-V and G-omega measurements were made in the frequency range from 1 kHz to 1 MHz in the temperature range 180-300 K. From the maximum of the plot G/omega vs. ln(omega) the density of interface states was calculated, and from its position on the frequency axis the trap cross-section was found. Reducing temperature makes it possible to decrease leakage current through the dielectric and to investigate the states located closer to the band edge. The structures under study were shown to contain significant interface trap densities located near the valence band edge (around 2 x 10(11) cm(-2)eV(-1) for Al and up to (3.5-5.5) x 10(12)cm(-2)eV(-1) for other gate materials). The peak in the surface state distribution is situated at 0.18 eV above the valence band edge for Al electrode. The capture cross-section is 5.8 x 10(-17)cm(2) at 200 K for Al-HfO2-Si structure.
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| 7. |
- Gottlob, H. D. B., et al.
(författare)
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Investigation of high-K gate stacks with epitaxial Gd(2)O(3) and FUSINiSi metal gates down to CET=0.86 nm
- 2006
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 9:6, s. 904-908
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Tidskriftsartikel (refereegranskat)abstract
- Novel gate stacks with epitaxial gadoliniurn oxide (Gd(2)O(3)) high-k dielectrics and fully silicided (FUSI) nickel silicide (NiSi) gate electrodes are investigated. Ultra-low leakage current densities down to 10(-7) A cm(-2) are observed at a capacitance equivalent oxide thickness of CET = 1.8 nm. The influence of a titanium nitride (TiN) capping layer during silicidation is studied. Furthermore, films with an ultra-thin CET of 0.86 nm at a Gd(2)O(3) thickness of 3.1 nm yield current densities down to 0.5 A cm(-2) at V(g) = + 1 V. The extracted dielectric constant for these gate stacks ranges from k = 13 to 14. These results emphasize the potential of NiSi/Gd(2)O(3) gate stacks for future material-based scaling of CMOS technology.
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| 8. |
- 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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| 9. |
- Hållstedt, Julius, et al.
(författare)
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Incorporation of boron in SiGe(C) epitaxial layers grown by reduced pressure chemical vapor deposition
- 2005
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 8:03-jan, s. 97-101
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Tidskriftsartikel (refereegranskat)abstract
- In this paper the strain and electrical properties of epitaxial in situ B-doped (10(18)-10(21) cm(-3)) SiGeC layers (23, 28% Ge and 0, 0.5% C) has been investigated. The growth rate was shown to have a significant increase at 3 x 10(-2) mTorr diborane partial pressure. This point coincides with an enhancement in boron incorporation, which was explained by the strain compensation effect of boron in the highly strained SiGeC layers. In these samples, the total Ge and C content was shown to remain constant with increasing diborane partial pressure. The substitutional/active dopant concentration in SiGe layers was obtained by high-resolution X-ray diffraction by measuring the strain compensation effect of boron. The interaction between C and B in SiGe matrix was also investigated. This was compared with the active dopant concentration obtained from Hall measurements in order to achieve a Hall scattering factor of 0.3-0.7 for dopant concentrations between 3 x 10(18) and 5 x 10(21) cm(-3). The resistivity values of these layers were in the range 2 x 10(-2) -4 x 10(-4) Omega cm. Finally, it was shown that boron atoms in SiGeC layers locate preferably at substitutional sites in contrary to carbon atoms at both substitutional and interstitial sites.
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| 10. |
- Isheden, Christian, et al.
(författare)
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pMOSFETs with recessed and selectively regrown Si1-xGex source/drain junctions
- 2005
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Ingår i: Materials Science in Semiconductor Processing. - : Elsevier BV. - 1369-8001 .- 1873-4081. ; 8:1-3, s. 359-362
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Tidskriftsartikel (refereegranskat)abstract
- A new source/drain formation concept based on selective Si etching followed by selective regrowth of in situ B-doped Si(1-x)Ge(x)is presented. Both process steps are performed in the same reactor to preserve the gate oxide. Well-behaved transistors are demonstrated with a negligibly low gate-to-substrate leakage current.
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