| 1. |
- Luo, Jun, et al.
(författare)
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Thermal Stability and Dopant Segregation for Schottky Diodes With Ultrathin Epitaxial NiSi(2-y)
- 2011
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 32:8, s. 1029-1031
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Tidskriftsartikel (refereegranskat)abstract
- The Schottky barrier height (SBH) of an ultrathin epitaxial NiSi(2-y) film grown on Si(100) is modified significantly by means of dopant segregation (DS). The DS process begins with the NiSi(2-y) formation and is followed by dopant implantation and drive-in annealing. The rapid lattice restoration and superior morphological stability upon heat treatment up to 800 degrees C allow the epitaxial NiSi(2-y) film to take full advantage of the DS process. For drive-in annealing below 750 degrees C, the effective SBH is altered to similar to 0.9-1 eV for both electrons and holes by B-DS and As-DS, respectively, without deteriorating the integrity of the NiSi(2-y) film.
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| 2. |
- Luo, Jun, et al.
(författare)
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Effects of carbon pre-silicidation implant into Si substrate on NiSi
- 2014
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 120, s. 178-181
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the effects of carbon pre-silicidation implant into Si(1 0 0) substrate on NiSi were investigated. NiSi films with carbon pre-silicidation implant to different doses were characterized by means of sheet resistance measurements, X-ray diffraction, scanning electron microscopy (SEM), planar view transmission electron microscopy (TEM) and second ion mass spectroscopy (SIMS). The presence of C is found to indeed significantly improve the thermal stability of NiSi as well as tends to change the preferred orientations of polycrystalline NiSi. The homogeneously distributed C at NiSi grain boundaries and C peak at NiSi/Si interface is ascribed to the improved thermal stability of NiSi. More importantly, the dose of carbon pre-silicidation implant also plays a key role in the formation of NiSi, which is suggested not to exceed a critical value about 5 x 10(15) cm(-2) in practical application in accordance with the results achieved in this work. (C) 2013 Elsevier B.V. All rights reserved.
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| 3. |
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| 4. |
- Luo, Jun, et al.
(författare)
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Variation of Schottky barrier height induced by dopant segregation monitored by contact resistivity measurements
- 2014
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Ingår i: Microelectronic Engineering. - : Elsevier BV. - 0167-9317 .- 1873-5568. ; 120, s. 174-177
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Tidskriftsartikel (refereegranskat)abstract
- Change of contact resistivity (rho(c)) is monitored for evaluation of Schottky barrier height (SBH) variation induced by dopant segregation (DS). This method is particularly advantageous for metal-semiconductor contacts of small SBH, as it neither requires low-temperature measurement needed in current-voltage characterization of Schottky diodes nor is affected by reverse leakage current often troubling capacitance-voltage characterization. With PtSi contact to both n- and p-type diffusion regions, and the use of opposite or alike dopants implant into pre-formed PtSi films followed by drive-in anneal at different temperatures to induce DS at PtSi/Si interface, the formation of interfacial dipole is confirmed as the responsible cause for modification of effective SBHs thus the increase or decrease of rho(c). A tentative explanation for the change of contact resistivity based on interfacial dipole theory is provided in this work. Influences and interplay of interfacial dipole and space charge on effective SBH are also discussed. (C) 2013 Elsevier B.V. All rights reserved.
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| 5. |
- Gudmundsson, Valur, et al.
(författare)
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Fully Depleted UTB and Trigate N-Channel MOSFETs Featuring Low-Temperature PtSi Schottky-Barrier Contacts With Dopant Segregation
- 2009
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Ingår i: IEEE Electron Device Letters. - 0741-3106 .- 1558-0563. ; 30:5, s. 541-543
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Tidskriftsartikel (refereegranskat)abstract
- Schottky-barrier source/drain (SB-S/D) presents a promising solution to reducing parasitic resistance for device architectures such as fully depleted UTB, trigate, or FinFET. In this letter, a low-temperature process (<= 700 degrees C) with PtSi-based S/D is examined for the fabrication of n-type UTB and trigate FETs on SOI substrate (t(si) = 30 nm). Dopant segregation with As was used to achieve the n-type behavior at implantation doses of 1 (.) 10(15) and 5. 10(15) cm(-2). Similar results were found for UTB devices with both doses, but trigate devices with the larger dose exhibited higher on currents and smaller process variation than their lower dose counterparts.
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| 6. |
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| 7. |
- Lu, Jun, et al.
(författare)
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On Epitaxy of Ultrathin Ni1-xPtx Silicide Films on Si(001)
- 2010
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Ingår i: Electrochemical and solid-state letters. - : The Electrochemical Society. - 1099-0062 .- 1944-8775. ; 13:10, s. H360-H362
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial Ni(Pt)Si2-y (y < 1) films readily grow upon thermal treatment of 2 nm thick Ni and Ni0.96Pt0.04 films deposited on Si(001). For annealing at 500 degrees C, the films are 5.4-5.6 nm thick with 61-70 mu cm in resistivity. At 750 degrees C, the epitaxial Ni(Pt)Si2-y films become 6.1-6.2 nm thick with a resistivity of 42-44 mu cm. Structural analysis reveals twins, facet wedges, and thickness inhomogeneities in the films grown at 500 degrees C. For higher temperature, an almost defect-free NiSi2-y film with a flat and sharp interface is formed. The presence of Pt makes the aforementioned imperfections more persistent.
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| 8. |
- Luo, Jun, et al.
(författare)
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Effects of Carbon on Schottky Barrier Heights of NiSi Modified by Dopant Segregation
- 2009
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Ingår i: IEEE Electron Device Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 0741-3106 .- 1558-0563. ; 30:6, s. 608-610
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Tidskriftsartikel (refereegranskat)abstract
- The presence of carbon at the interface between NiSi and Si has been found to participate in the process of modification of effective Schottky barrier heights using the dopant segregation (DS) method. Carbon alone results in an increased phi(bn) from 0.7 to above 0.9 eV. Boron diffusion in NiSi is inhibited by carbon, and no B-DS at the NiSi/Si interface occurs below 600 degrees C. Above this temperature, B-DS at this interface is evident thus keeping phi(bn) high. The presence of interfacial carbon leads to an increased interfacial As concentration resulting in beneficial effects in tuning phi(bn) above 1.0 eV by As-DS.
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| 9. |
- Luo, Jun, et al.
(författare)
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Interaction of NiSi with dopants for metallic source/drain applications
- 2010
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 28:1, s. C1I1-C1I11
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Tidskriftsartikel (refereegranskat)abstract
- This work has a focus on NiSi as a possible metallic contact for aggressively scaled complementary metal oxide semiconductor devices. As the bulk work function of NiSi lies close to the middle of Si bandgap, the Schottky barrier height (SBH) of NiSi is rather large for both electron (similar to 0.65 eV) and hole (similar to 0.45 eV). Different approaches have therefore been intensively investigated in the literature aiming at reducing the effective SBH: dopant segregation (DS), surface passivation (SP), and alloying, in order to improve the carrier injection into the conduction channel of a field-effect transistor. The present work explores DS using B and As for the NiSi/Si contact system. The effects of C and N implantation into Si substrate prior to the NiSi formation are examined, and it is found that the presence of C yields positive effects in helping reduce the effective SBH to 0.1-0.2 eV for both conduction polarities. A combined use of DS or SP with alloying could be considered for more effective control of effective SBH, but an examination of undesired compound formation and its probable consequences is necessary. Furthermore, an analysis of the metal silicides that have a small "intrinsic" SBH reveals that only a very small number of them are of practical interest as most of the silicides require either a high formation temperature or possess a high specific resistivity.
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| 10. |
- Luo, Jun, et al.
(författare)
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On Different Process Schemes for MOSFETs With a Controllable NiSi-Based Metallic Source/Drain
- 2011
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Ingår i: IEEE Transactions on Electron Devices. - : IEEE Institute of Electrical and Electronics. - 0018-9383 .- 1557-9646. ; 58:7, s. 1898-1906
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Tidskriftsartikel (refereegranskat)abstract
- This paper focuses on different silicidation schemes toward a controllable NiSi-based metallic source/drain (MSD) process with restricted lateral encroachment of NiSi. These schemes include thickness control of Ni, Ni-Pt alloying, and two-step annealing. Experimental results show that all the three process schemes can give rise to effective control of lateral encroachment during Ni silicidation. By controlling t(Ni), NiSi-based MSD metal-oxide-semiconductor field-effect transistors (MOSFETs) of gate length L-G = 55 nm are readily realized on ultrathin-body silicon-on-insulator substrates with 20-nm surface Si thickness. With the aid of dopant segregation (DS) to modifying the Schottky barrier heights of NiSi, both n- and p-type MSD MOSFETs show significant performance improvement, compared to reference devices without DS.
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