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Si1−yCy heterostructures for nMOS devices
Materials Science and Engineering B102 (2003) 119 /122 www.elsevier.com/locate/mseb
Advanced characterization of Si/Si1 y Cy heterostructures for nMOS devices F. Laugier *, P. Holliger, J.M. Hartmann, T. Ernst, V. Loup, G. Rolland, D. Lafond CEA-DRT, LETI/DTS, CEA/GRE, 17 rue des Martyrs, 38 054 Grenoble, Cedex 9, France
Abstract Si/Si1 y Cy /Si heterostructures for ultra-short gate length (50 nm) metal oxide semiconductor (nMOS) devices were grown by reduced pressure chemical vapor deposition (RP-CVD) and characterized. Low energy secondary ion mass spectrometry (SIMS), high resolution X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microcopy (TEM) were jointly used to build a coherent picture of the physical and electrical properties of the layers. SIMS and XRD measurements indicate that high carbon concentration samples (substitutional C /1.12 at.%) also contain many interstitial carbon atoms (interstitial C /0.45 at.%). We demonstrated by XRD that such Si/Si1 y Cy /Si stacks are stable versus standard thermal anneals. We thus integrated them into a conventional nMOS process. Cross-sectional TEM imaging shows that the resulting heterostructures arc of high crystalline quality, with well defined interfaces. Finally, an in-depth SIMS analysis using either Cs or O2 primary ions of the C, O and B concentration profiles inside such transistors reveals that (i) some C segregation occurs during the growth of the Si cap, generating the presence of C inside the Si cap and SiO2 gate (ii) C atoms induce a strong reduction of the B diffusion from the antipunch-through layer underneath, generating highly retrograde doping profiles. All these measurements will help understanding the electrical properties of such ultimate devices. # 2003 Elsevier B.V. All rights reserved. Keywords: Si1 y Cy ; nMOS transistor; SIMS; XRD; Reduced pressure-chemical vapor deposition
1. Introduction To improve electrical performances of n-type and ptype advanced metal oxide semiconductor (MOS) devices, it has been suggested to replace the conventional silicon channel by epitaxial Si/SiGe(C) heterostructures [1]. In relation to germanium and carbon concentrations, tensile-strain or compressive-strain is present in SiGe channels, generating band structure modification, and higher electron or hole mobilities [2]. Epitaxy of tensile-strain Si1 y Cy on Si has also been considered as an alternative to improve the performances of n-type MOS devices [3,4]. In practice, it is not an easy task to grow C containing silicon films because of the high mismatch between the Si and C lattices (52%) [5]. Carbon has also a tendency to precipitate into b poly-type silicon carbide [6].
* Corresponding author. Tel.: /33-438-78-5544; fax: /33-438-789485. E-mail address: [email protected] (F. Laugier). 0921-5107/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0921-5107(03)00016-3
In our study, Si/Si1 y Cy /Si heterostructures are produced by reduced pressure chemical vapor deposition (RP-CVD) and characterized by low energy secondary ion mass spectrometry (SIMS), high resolution X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microcopy (TEM). We will focus on carbon, oxygen, and boron concentration profiles, and on the thermal stability of such stacks. Our stacks were limited to those used in ultra-short gate length (50 nm) nMOS transistors.
2. Experimental procedures Si/Si1 y Cy /Si heterostructures were grown in an industrial RP-CVD reactor (Epi Centura, Applied Materials) at 600 8C and 20 Torr, on 200 mm n-type (100) Si substrates. Gas precursors were silane (SiH4) and diluted methylsilane (5% SiH3CH3 in hydrogen), with purified hydrogen as a carrier gas. SIMS measurements were carried out on a Cameca IMS 5f. O2 primary ions were used for boron depth profiling, with
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F. Laugier et al. / Materials Science and Engineering B102 (2003) 119 /122
an impact energy of 1 keV and incidence angle of 508 relative to normal. 10B 11B , 28Si secondary ions were monitored. Cs primary ions were used for carbon and oxygen depth profiling, applying the MCs2 cluster method (where M is the element of interest) [7]. The corresponding impact energy was 2 keV with an incidence angle of 508. X-ray diffraction measurements were performed on a Philips high resolution diffraction (X’Pert MRD) system at the Cu Kal wavelength of ˚ in combination with the ‘EPITAXY’ software 1.5406 A based on the Takagi /Taupin dynamical scattering theory. Comparison between simulated and measured (004) HR-XRD V /2u enabled us to determine the substitutional carbon concentrations in the Si1 y Cy films. Tapping mode AFM was performed on a Digital Instrument Dimension 3 100 SPM equipped with a camera. Cross sectional TEM imaging was performed on an Akashi EM-002B operating at 200 kV. The TEM samples were mechanically polished down to a 20 mm thickness and then ion milled at 5.5 keV with Ar ions.
3. Substitutional and interstitial C in Sil y Cy layers Si buffer 35 nm/Si1 y Cy 92/101 nm/Si cap 12 nm stacks were grown epitaxially on Si (001) substrates. Three of nine XRD profiles around the (004) diffraction order of these films are presented in Fig. 1. Interference fringes evidence good crystallographic quality of the heterostructures as well as the abruptness of the Si buffer/Si1 y Cy and Si1 y Cy /Si cap interfaces. The shift of the Si1 y Cy peak towards higher incidence angles demonstrates an increase of the tensile strain due to an incorporation of carbon atoms into substitutional sites of Si lattice. The highest percentage of carbon atoms incorporated into Si1 y Cy layers is 1.12%. In Fig. 2, four carbon SIMS profiles are plotted. Carbon concentration is uniform throughout Si1 y Cy layers. As long as small amounts of carbon are added, the C profile slope is quite steep, evidencing the abruptness of the Si1 y Cy /Si interface. However the SiC1.12% carbon
Fig. 1. HR-XRD (004) V /2u scans for Si/Si1 y Cy /stacks.
Fig. 2. C SIMS depth profiles for Si/Si1 y Cy /stacks.
SIMS profile shows a large trailing edge, which corresponds to a degradation of the epitaxial quality (for thick layers, however). The substitutional carbon concentrations Csub determined by XRD and the total carbon concentration Ctot given by SIMS are compared as a function of precursors flows in Fig. 3. For measured C concentration below 0.5%, results are similar. All C atoms are in substitutional sites. Above 0.5%, a difference appears. The substitutional carbon concentration seems to saturate when increasing the SiCH6 flow, whereas the total carbon concentration still increases. This is a sign that a higher number of C atoms are incorporated in interstitial sites (up to 0.45 at.% for a 0.018 mass flow ratio of methylsilane/silane).
4. Thermal stability of Si1 y Cy in nMOS transistor High temperature treatments are used whenever making MOS transistors. The most aggressive is the annealing for electrical activation of source/drains implants. Fig. 4 shows the (004) XRD profiles of Si/Si0.9888 C0.0112 60 nm/Si cap 12 nm stacks: as-grown; after the formation of a 2 nm SiO2 gate followed or not by rapid thermal anneal at 950 8C for 15 s or by 1050 8C spike anneal (normally used for electrical activation). In this
Fig. 3. Comparison of the carbon concentrations in Si1 y Cy layers as determined by XRD and SIMS.
F. Laugier et al. / Materials Science and Engineering B102 (2003) 119 /122
Fig. 4. HR-XRD (004) V /2u scans for Si/Si0.9888C0.0112/Si stacks asgrown or subjected to various thermal treatments.
figure, only the 1050 8C spike anneal induces a slight effect on the XRD curve, with a reduction of the substitutional C atoms concentration from 1.12 to 1.07%. Consequently, the tensile-strain state of our Si1 y Cy layers is not significantly altered during the most aggressive thermal treatments used in MOS technology.
121
Fig. 6. Carbon and oxygen SIMS depth profiling.
nm)/Si:B (setback layer). Results are plotted in Fig. 6. The oxygen peak at a depth of 20 nm is linked to the presence of the 2 nm gate oxide. The C peak concentration is roughly the one expected (i.e. 1.6%) in the targeted place of the Si1 y Cy layer. A significant amount of C is also present in the 2 nm Si cap layer (1%) and in the 2 nm SiO2 layer. This segregation of C is currently under investigation to optimize (through its minimization) future nMOS stacks based on Si1 y Cy .
5. Vertical integration in nMOS transistor Si/Si1 y Cy /Si stacks were integrated into nMOS transistors. Fig. 5 presents a cross-sectional TEM image of the boundary between the gate stack and the Si buffer (10 nm)/Si0.9888C0.0112 channel (10 nm)/Si cap (2 nm). The thickness of the Si1 y Cy layer is, as targeted, of about 10 nm with good epitaxial quality. No roughness of the gate oxide can be observed. AFM measurement gives a surface rms roughness value of 0.09 nm. SIMS depth profiles (using Cs primary ions) of the C and O atoms were carried out on the following layer stack: starting from the top 20 nm of poly-Si/2 nm of SiO2/Si cap (2 nm)/Si0.9888C0.0112 channel (10 nm)/Si buffer (10
6. Boron diffusion barrier Scaling-down of MOS transistors in the deep submicron region requires very shallow and abrupt doping profiles in the active region. In order to avoid implant damage in the SiO2 gate, channel implantation is usually performed prior to gate oxidation. However, during oxidation, oxidation-enhanced diffusion (OED) due to the injection of self-interstitials contributes significantly to dopant redistribution and makes the desired doping profiles very difficult to realize [8]. SIMS depth profiling (using O2 primary ions) of the B atoms in our test
Fig. 5. HR-TEM cross-sectional imaging of the heterostructures into ultra-short gate length (50 nm) nMOS transistor.
F. Laugier et al. / Materials Science and Engineering B102 (2003) 119 /122
122
Fig. 7. Boron SIMS depth profiling.
structures has, therefore, been carried out. The resulting profiles arc plotted in Fig. 7. Without any epitaxy, the boron atoms present in the B implanted ‘anti-punch through’ layer diffuse as expected inside the SiO2 gate during its formation. With the insertion of 22 nm of Si, a retrograde B concentration profile is obtained, with a reduction by a factor of 10 of the B concentration in the vicinity of the Si/SiO2 gate interface. Substituting to 22 nm of Si, a Si buffer (10 nm)/Si0.9888C0.0112 channel (10 nm)/Si cap (2 nm) stack leads to a more retrograde B concentration profile, with a reduction by a factor of more than 100 compared with the case without any epitaxy. Using epitaxy instead of ion implantation to form the anti-punch through layer (with a 40 nm Si layer boron doped at a maximum concentration of 4 /l018 cm 3) grown prior to the growth of the Si/Si1 y Cy /Si stacks, a reduction by a factor of nearly 1000 was observed, as illustrated in Fig. 7.
7. Conclusion Si/Si1 y Cy /Si heterostructures for nMOS transistors were deposited using a RP-CVD reactor and analyzed. A comparison between SIMS and XRD data shows that, for small carbon concentrations (B/0.5%), all the C
atoms added are incorporated into substitutional sites. For higher concentration, the total carbon increases linearly with the flux whereas substitutional carbon satures. Interstitial carbon concentrations up to 0.45 at.% were obtained. Those Si/Si1 y Cy /Si heterostructures have been shown to be stable versus conventional gate oxidations and electrical activation anneals for substitutional carbon. We have thus integrated Si buffer (10 nm)/Si0.9888C0.0112 channel (10 nm)/Si cap (2 nm) stack into ultra-short gate length (50 nm) nMOS transistors and observed by TEM the corresponding cross section. Good epitaxial characteristics were achieved. AFM confirms absence of roughness. SIMS profiles of the C and B atoms in the channel region show that C atoms are present in the Si cap and the SiO2 gate, but that they block the boron diffusion coming from the anti-punch through layer towards the gate, generating very retrograde doping profiles.
Acknowledgements This work was carried out within the frame of the ‘SIGMOS’ European Union IST Project in the Silicon Technologies Department from CEA/LETI. V. Loup’s Ph.D. thesis is co-funded by Applied Materials.
References [1] E.H.C. Parker, T.E. Whall, Solid-State Electron. 43 (1999) 1497. [2] M. Mu¨hlberger, C. Schelling, N. Sandersfeld, H. Seyringer, F. Scha¨ffler, Thin Solids Films 369 (2000) 306. [3] J.B. Posthill, R.A. Rudder, S.V. Hattangady, G.G. Fountain, R.J. Markunas, Appl. Phys. Lett. 56 (1990) 734. [4] W. Fashinger, S. Zerlauth, G. Bauer, L. Palmetshofer, Appl. Phys. Lett. 67 (1995) 26. [5] R.W. Olesinski, G.J. Abbaschian, Bull. Alloy Phase Diag. 5 (1984) 484. [6] A.R. Powell, F.K. LeGoues, S.S. Iyer, Appl. Phys. Lett. 64 (1994) 324. [7] P. Holliger, F. Laugier, J.C. Dupuy, Surf. Interf. Anal. 34 (2002) 472 /476. ¨ ztu¨rk, E.K. Demirlioglu, IEEE Trans. Electr. Dev. [8] I. Ban, M.C. .O 44 (1997) 1544.
Advanced characterization of Si/Si1 y Cy heterostructures for nMOS devices F. Laugier *, P. Holliger, J.M. Hartmann, T. Ernst, V. Loup, G. Rolland, D. Lafond CEA-DRT, LETI/DTS, CEA/GRE, 17 rue des Martyrs, 38 054 Grenoble, Cedex 9, France
Abstract Si/Si1 y Cy /Si heterostructures for ultra-short gate length (50 nm) metal oxide semiconductor (nMOS) devices were grown by reduced pressure chemical vapor deposition (RP-CVD) and characterized. Low energy secondary ion mass spectrometry (SIMS), high resolution X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microcopy (TEM) were jointly used to build a coherent picture of the physical and electrical properties of the layers. SIMS and XRD measurements indicate that high carbon concentration samples (substitutional C /1.12 at.%) also contain many interstitial carbon atoms (interstitial C /0.45 at.%). We demonstrated by XRD that such Si/Si1 y Cy /Si stacks are stable versus standard thermal anneals. We thus integrated them into a conventional nMOS process. Cross-sectional TEM imaging shows that the resulting heterostructures arc of high crystalline quality, with well defined interfaces. Finally, an in-depth SIMS analysis using either Cs or O2 primary ions of the C, O and B concentration profiles inside such transistors reveals that (i) some C segregation occurs during the growth of the Si cap, generating the presence of C inside the Si cap and SiO2 gate (ii) C atoms induce a strong reduction of the B diffusion from the antipunch-through layer underneath, generating highly retrograde doping profiles. All these measurements will help understanding the electrical properties of such ultimate devices. # 2003 Elsevier B.V. All rights reserved. Keywords: Si1 y Cy ; nMOS transistor; SIMS; XRD; Reduced pressure-chemical vapor deposition
1. Introduction To improve electrical performances of n-type and ptype advanced metal oxide semiconductor (MOS) devices, it has been suggested to replace the conventional silicon channel by epitaxial Si/SiGe(C) heterostructures [1]. In relation to germanium and carbon concentrations, tensile-strain or compressive-strain is present in SiGe channels, generating band structure modification, and higher electron or hole mobilities [2]. Epitaxy of tensile-strain Si1 y Cy on Si has also been considered as an alternative to improve the performances of n-type MOS devices [3,4]. In practice, it is not an easy task to grow C containing silicon films because of the high mismatch between the Si and C lattices (52%) [5]. Carbon has also a tendency to precipitate into b poly-type silicon carbide [6].
* Corresponding author. Tel.: /33-438-78-5544; fax: /33-438-789485. E-mail address: [email protected] (F. Laugier). 0921-5107/03/$ - see front matter # 2003 Elsevier B.V. All rights reserved. doi:10.1016/S0921-5107(03)00016-3
In our study, Si/Si1 y Cy /Si heterostructures are produced by reduced pressure chemical vapor deposition (RP-CVD) and characterized by low energy secondary ion mass spectrometry (SIMS), high resolution X-ray diffraction (XRD), atomic force microscopy (AFM) and transmission electron microcopy (TEM). We will focus on carbon, oxygen, and boron concentration profiles, and on the thermal stability of such stacks. Our stacks were limited to those used in ultra-short gate length (50 nm) nMOS transistors.
2. Experimental procedures Si/Si1 y Cy /Si heterostructures were grown in an industrial RP-CVD reactor (Epi Centura, Applied Materials) at 600 8C and 20 Torr, on 200 mm n-type (100) Si substrates. Gas precursors were silane (SiH4) and diluted methylsilane (5% SiH3CH3 in hydrogen), with purified hydrogen as a carrier gas. SIMS measurements were carried out on a Cameca IMS 5f. O2 primary ions were used for boron depth profiling, with
120
F. Laugier et al. / Materials Science and Engineering B102 (2003) 119 /122
an impact energy of 1 keV and incidence angle of 508 relative to normal. 10B 11B , 28Si secondary ions were monitored. Cs primary ions were used for carbon and oxygen depth profiling, applying the MCs2 cluster method (where M is the element of interest) [7]. The corresponding impact energy was 2 keV with an incidence angle of 508. X-ray diffraction measurements were performed on a Philips high resolution diffraction (X’Pert MRD) system at the Cu Kal wavelength of ˚ in combination with the ‘EPITAXY’ software 1.5406 A based on the Takagi /Taupin dynamical scattering theory. Comparison between simulated and measured (004) HR-XRD V /2u enabled us to determine the substitutional carbon concentrations in the Si1 y Cy films. Tapping mode AFM was performed on a Digital Instrument Dimension 3 100 SPM equipped with a camera. Cross sectional TEM imaging was performed on an Akashi EM-002B operating at 200 kV. The TEM samples were mechanically polished down to a 20 mm thickness and then ion milled at 5.5 keV with Ar ions.
3. Substitutional and interstitial C in Sil y Cy layers Si buffer 35 nm/Si1 y Cy 92/101 nm/Si cap 12 nm stacks were grown epitaxially on Si (001) substrates. Three of nine XRD profiles around the (004) diffraction order of these films are presented in Fig. 1. Interference fringes evidence good crystallographic quality of the heterostructures as well as the abruptness of the Si buffer/Si1 y Cy and Si1 y Cy /Si cap interfaces. The shift of the Si1 y Cy peak towards higher incidence angles demonstrates an increase of the tensile strain due to an incorporation of carbon atoms into substitutional sites of Si lattice. The highest percentage of carbon atoms incorporated into Si1 y Cy layers is 1.12%. In Fig. 2, four carbon SIMS profiles are plotted. Carbon concentration is uniform throughout Si1 y Cy layers. As long as small amounts of carbon are added, the C profile slope is quite steep, evidencing the abruptness of the Si1 y Cy /Si interface. However the SiC1.12% carbon
Fig. 1. HR-XRD (004) V /2u scans for Si/Si1 y Cy /stacks.
Fig. 2. C SIMS depth profiles for Si/Si1 y Cy /stacks.
SIMS profile shows a large trailing edge, which corresponds to a degradation of the epitaxial quality (for thick layers, however). The substitutional carbon concentrations Csub determined by XRD and the total carbon concentration Ctot given by SIMS are compared as a function of precursors flows in Fig. 3. For measured C concentration below 0.5%, results are similar. All C atoms are in substitutional sites. Above 0.5%, a difference appears. The substitutional carbon concentration seems to saturate when increasing the SiCH6 flow, whereas the total carbon concentration still increases. This is a sign that a higher number of C atoms are incorporated in interstitial sites (up to 0.45 at.% for a 0.018 mass flow ratio of methylsilane/silane).
4. Thermal stability of Si1 y Cy in nMOS transistor High temperature treatments are used whenever making MOS transistors. The most aggressive is the annealing for electrical activation of source/drains implants. Fig. 4 shows the (004) XRD profiles of Si/Si0.9888 C0.0112 60 nm/Si cap 12 nm stacks: as-grown; after the formation of a 2 nm SiO2 gate followed or not by rapid thermal anneal at 950 8C for 15 s or by 1050 8C spike anneal (normally used for electrical activation). In this
Fig. 3. Comparison of the carbon concentrations in Si1 y Cy layers as determined by XRD and SIMS.
F. Laugier et al. / Materials Science and Engineering B102 (2003) 119 /122
Fig. 4. HR-XRD (004) V /2u scans for Si/Si0.9888C0.0112/Si stacks asgrown or subjected to various thermal treatments.
figure, only the 1050 8C spike anneal induces a slight effect on the XRD curve, with a reduction of the substitutional C atoms concentration from 1.12 to 1.07%. Consequently, the tensile-strain state of our Si1 y Cy layers is not significantly altered during the most aggressive thermal treatments used in MOS technology.
121
Fig. 6. Carbon and oxygen SIMS depth profiling.
nm)/Si:B (setback layer). Results are plotted in Fig. 6. The oxygen peak at a depth of 20 nm is linked to the presence of the 2 nm gate oxide. The C peak concentration is roughly the one expected (i.e. 1.6%) in the targeted place of the Si1 y Cy layer. A significant amount of C is also present in the 2 nm Si cap layer (1%) and in the 2 nm SiO2 layer. This segregation of C is currently under investigation to optimize (through its minimization) future nMOS stacks based on Si1 y Cy .
5. Vertical integration in nMOS transistor Si/Si1 y Cy /Si stacks were integrated into nMOS transistors. Fig. 5 presents a cross-sectional TEM image of the boundary between the gate stack and the Si buffer (10 nm)/Si0.9888C0.0112 channel (10 nm)/Si cap (2 nm). The thickness of the Si1 y Cy layer is, as targeted, of about 10 nm with good epitaxial quality. No roughness of the gate oxide can be observed. AFM measurement gives a surface rms roughness value of 0.09 nm. SIMS depth profiles (using Cs primary ions) of the C and O atoms were carried out on the following layer stack: starting from the top 20 nm of poly-Si/2 nm of SiO2/Si cap (2 nm)/Si0.9888C0.0112 channel (10 nm)/Si buffer (10
6. Boron diffusion barrier Scaling-down of MOS transistors in the deep submicron region requires very shallow and abrupt doping profiles in the active region. In order to avoid implant damage in the SiO2 gate, channel implantation is usually performed prior to gate oxidation. However, during oxidation, oxidation-enhanced diffusion (OED) due to the injection of self-interstitials contributes significantly to dopant redistribution and makes the desired doping profiles very difficult to realize [8]. SIMS depth profiling (using O2 primary ions) of the B atoms in our test
Fig. 5. HR-TEM cross-sectional imaging of the heterostructures into ultra-short gate length (50 nm) nMOS transistor.
F. Laugier et al. / Materials Science and Engineering B102 (2003) 119 /122
122
Fig. 7. Boron SIMS depth profiling.
structures has, therefore, been carried out. The resulting profiles arc plotted in Fig. 7. Without any epitaxy, the boron atoms present in the B implanted ‘anti-punch through’ layer diffuse as expected inside the SiO2 gate during its formation. With the insertion of 22 nm of Si, a retrograde B concentration profile is obtained, with a reduction by a factor of 10 of the B concentration in the vicinity of the Si/SiO2 gate interface. Substituting to 22 nm of Si, a Si buffer (10 nm)/Si0.9888C0.0112 channel (10 nm)/Si cap (2 nm) stack leads to a more retrograde B concentration profile, with a reduction by a factor of more than 100 compared with the case without any epitaxy. Using epitaxy instead of ion implantation to form the anti-punch through layer (with a 40 nm Si layer boron doped at a maximum concentration of 4 /l018 cm 3) grown prior to the growth of the Si/Si1 y Cy /Si stacks, a reduction by a factor of nearly 1000 was observed, as illustrated in Fig. 7.
7. Conclusion Si/Si1 y Cy /Si heterostructures for nMOS transistors were deposited using a RP-CVD reactor and analyzed. A comparison between SIMS and XRD data shows that, for small carbon concentrations (B/0.5%), all the C
atoms added are incorporated into substitutional sites. For higher concentration, the total carbon increases linearly with the flux whereas substitutional carbon satures. Interstitial carbon concentrations up to 0.45 at.% were obtained. Those Si/Si1 y Cy /Si heterostructures have been shown to be stable versus conventional gate oxidations and electrical activation anneals for substitutional carbon. We have thus integrated Si buffer (10 nm)/Si0.9888C0.0112 channel (10 nm)/Si cap (2 nm) stack into ultra-short gate length (50 nm) nMOS transistors and observed by TEM the corresponding cross section. Good epitaxial characteristics were achieved. AFM confirms absence of roughness. SIMS profiles of the C and B atoms in the channel region show that C atoms are present in the Si cap and the SiO2 gate, but that they block the boron diffusion coming from the anti-punch through layer towards the gate, generating very retrograde doping profiles.
Acknowledgements This work was carried out within the frame of the ‘SIGMOS’ European Union IST Project in the Silicon Technologies Department from CEA/LETI. V. Loup’s Ph.D. thesis is co-funded by Applied Materials.
References [1] E.H.C. Parker, T.E. Whall, Solid-State Electron. 43 (1999) 1497. [2] M. Mu¨hlberger, C. Schelling, N. Sandersfeld, H. Seyringer, F. Scha¨ffler, Thin Solids Films 369 (2000) 306. [3] J.B. Posthill, R.A. Rudder, S.V. Hattangady, G.G. Fountain, R.J. Markunas, Appl. Phys. Lett. 56 (1990) 734. [4] W. Fashinger, S. Zerlauth, G. Bauer, L. Palmetshofer, Appl. Phys. Lett. 67 (1995) 26. [5] R.W. Olesinski, G.J. Abbaschian, Bull. Alloy Phase Diag. 5 (1984) 484. [6] A.R. Powell, F.K. LeGoues, S.S. Iyer, Appl. Phys. Lett. 64 (1994) 324. [7] P. Holliger, F. Laugier, J.C. Dupuy, Surf. Interf. Anal. 34 (2002) 472 /476. ¨ ztu¨rk, E.K. Demirlioglu, IEEE Trans. Electr. Dev. [8] I. Ban, M.C. .O 44 (1997) 1544.