Location of Repository

Fabrication and characterisation of novel Ge MOSFETs

By Chris Beer

Abstract

As high-k dielectrics are introduced into commercial Si CMOS (Complimentary Metal Oxide Semiconductor) microelectronics, the 40 year channel/dielectric partnership of Si/SiO2 is ended and the door opened for silicon to be replaced as the active channel material in MOSFETs (Metal Oxide Semiconductor Field Effect Transistor). Germanium is a good candidate as it has higher bulk carrier mobilities than silicon. In addition, Si and Ge form a thermodynamically stable SiGe alloy of any composition, allowing Ge to be implemented as a thin layer on the surface of a standard Si substrate. This thesis is a practical investigation on several aspects of Ge CMOS technology. \ud High-k dielectric Ge p-MOSFETs are electrically characterised. A large variation in interface state densities is demonstrated to be responsible for a threshold voltage shift and this is proportional to reciprocal peak mobility due to the Coulomb scattering of carriers by charged states. A theoretical mobility is fitted to that measured at 4.2 K and confirms that interface states are the main source of interface charged impurities.\ud The model demonstrates a reduction in the interface charged impurity density in p-MOSFETs that underwent a PMA (Post Metallisation Anneal) in hydrogen atmosphere and that the anneal also reduces the RMS (Root Mean Square) dielectric/semiconductor interface roughness, from an average of 0.60 nm to 0.48 nm.\ud High-k strained Ge p-MOSFETs are electrically characterised and have peak mobilities at 300 K (470 cm2 V-1 s-1) and 4.2 K (1780 cm2 V-1 s-1) far in excess of those measured for the unstrained Ge p-MOSFETs (285 cm2 V-1 s-1,785 cm2 V-1 s-1 respectively). Strained Ge n-MOSFETs perform significantly worse than standard Si P, - MOSFETs primarily due to a high source/drain resistance.\ud A 10 nm thick SiGe-01 (On Insulator) layer with a Ge composition of 58% is obtained from a 55 nm Si0_88Ge1o2. initial layer on 100 nm Si-Ol substrate via the germanium condensation technique. For the first time, germanium is demonstrated to diffuse through the BOX (Buried OXide) during Ge-condensation and into the underlying Si substrate. An order of magnitude increase in the calculated ITOX (Internal Thermal OXidation) rate of the BOX in the final stages of Ge-condensation is hypothesised to be responsible for stopping this diffusion

Topics: TK, QC
OAI identifier: oai:wrap.warwick.ac.uk:2411

Suggested articles

Preview

Citations

  1. A 90nm high volume manufacturing logic technology featuring novel 45nm gate length strained silicon CMOS transistors ". doi
  2. (2001). A theoretical study of the hole mobility in silicon-germanium heterostrucLures.
  3. A two step oxidation mediated condensation process for ultrathin high Ge content SiGe epitaxial films on insulator". electrochemical and solid-state letters, doi
  4. Analysis of GOI-MOSFET with highk gate dielectric and metal gate fabricated by Ge condensation technique". surface and interface analysis, doi
  5. Application of hydrogen ion beams to Silicon On Insulator material technology". nuclear instruments and methods in physics research doi
  6. Band structure, deformation potentials and carrier mobility in strained Si, Ge and SiGe alloys". journal of applied physics, doi
  7. Brother silicon, sister germanium" . journal of the electrochemical society, 154(7): H572-H583,2007. doi
  8. Calculation of critical layer thickness versus lattice mismatch for GexSil_x/Si strained-layer heterostructures". applied physics letters, doi
  9. (2008). Channel backscattering characteristics of high performance germanium pMOSFETs". doi
  10. Characteristics of strainedgermanium p- and n-channel field effect transistors on a Si (111) substrate". semiconductor science and technology, doi
  11. Characterization of 7-nm-thick strained Ge-on-insulator layer fabricated by Ge-condensation technique". applied physics letters, doi
  12. Charge accumulation and mobility in thin dielectric transistors". solid-state electronics, doi
  13. Charge compensation using optical conductivity enhancement and simple analytical protocols for SIMS of resistive Sil_xGex alloy layers". applied surface science,
  14. Compressive strain dependence of hole mobility in strained Ge channels". applied physics letters, doi
  15. Correcting effective mobility measurements for the presence of significant gate leakage current". doi
  16. Counter-oxidation of superficial Si in singlecrystalline Si on 5i02 structure". applied physics letters, doi
  17. (1965). Cramming more components onto integrated circuits". doi
  18. (1986). Crystalline semiconducting materials and devices. doi
  19. Defects and strain relaxation in silicon-germanium-on-insulator formed by high-temperature oxidation". applied physics letters, doi
  20. Defects in epitaxial multilayers: I. misfit dislocations". journal of crystal growth, doi
  21. Diffusion of Ge in SiGe alloys". physical review doi
  22. Diffusion of germanium in silica glass". journal of non-crystalline solids, doi
  23. Drivecurrent enhancement in Ge n-channel MOSFET using laser annealing for source/drain activation". doi
  24. Effective and field-effect mobilities in Si MOSFETs". solid-state electronics, doi
  25. Effective electron mobility in Si inversion layers in metal-oxide-semiconductor systems with a high-k insulator: The role of remote phonon scattering". journal of applied physics, doi
  26. Effects of hydrogen annealing on heteroepitaxial-Ge layers on Si: surface roughness and electrical quality". applied physics letters, doi
  27. Electrical characterization of germanium p-channel MOSFETs". doi
  28. (2004). Electron states at the (1 0 0)Ge/HfO2 Interface". material science in semiconductor processing, doi
  29. Electronic properties of two-dimensional systems". reviews of modern physics, doi
  30. Enhancement of SiGe relaxation for fabrication of SGOI substrates using condensation". electrochemical society proceedings,
  31. Evaluations of scaling properties of Ge on insulator MOSFETs in nano-scale". Japanese journal of applied physics, doi
  32. Fabrication of high-quality p-MOSFET in Ge grown heteroepitaxially on Si". doi
  33. (2000). Fundamentals of carrier transport. doi
  34. (1998). Fundamentals of modern VLSI devices.
  35. Ge dots embedded in Si02 obtained by oxidation of Si/Ge/Si nanostructures". doi
  36. General relationship for the thermal oxidation of silicon" journal of applied physics, doi
  37. Germanium channel MOSFETs: opportunities and challenges". IBM journal of research and development, doi
  38. (2005). Growth and characterisation of terrace graded virtual substrates with Sil_xGee
  39. Growth kinetics and related physical/electrical properties of Ge quantum dots formed by thermal oxidation of SiGe-on-insulator". doi
  40. High dielectric constant gate oxides for metal oxide Si". reports on progress in modern physics, doi
  41. High mobility strained Ge pMOSFETs with high-kappa/metal gate". doi
  42. (2006). High performance Ge pMOS devices using a Si-compatible process flow". doi
  43. (2007). High-k, metal gates a 'Go' for 45 nm".
  44. High-mobility Si and Ge structures". semiconductor science and technology, doi
  45. High-performance deep submicron Ge pMOSFETs with halo implants". doi
  46. Hole mobility enhancement of p-MOSFETs using global and local Ge-channel technologies". materials science and engineering doi
  47. Impact of interface traps on gate-induced drain leakage current in n-type metal oxide semiconductor field effect transistor". international journal of electronics, doi
  48. Impact of the annealing temperature on the homogeneity of SiGe-oninsulator". In
  49. (2005). Interfacial characteristics of fully depleted SiGe-on-insulator (SGOI) substrate fabricated by modified Ge condensation". semiconductor science and technology, 20: L31-L35, doi
  50. (2004). Investigation into the electrical properties of tensile strained silicon MOSFETs.
  51. (2001). Investigation of high mobility pseudomorphic SiGe p-channels in Si MOSFETs at low and high electric fields. PhD thesis,
  52. Investigation of strainsymmetrized and pseudomorphic Sim, Gen, superlattices by x-ray reciprocal space mapping". journal of applied physics, doi
  53. Investigations on the high-temperature thermal oxidation process at top and bottom interfaces of top silicon of SIMOX wafers". doi
  54. Kinetics and mechanism of oxidation of SiGe: dry versus wet oxidation". applied physics letters, doi
  55. Kinetics of thermal growth of ultra-thin layers of Si02 on silicon". journal of the electrochemical society, doi
  56. Mobility measurement and degradation mechanisms of MOSFETs made with ultrathin high-k dielectrics". doi
  57. (1982). MOS (metal oxide semiconductor) physics and technology. doi
  58. On the universality of inversion layer mobility in Si MOSFET's: part 1-effects of substrate impurity concentration". doi
  59. On the universality of inversion layer mobility in Si MOSFET's: part 2-effects of surface orientation". doi
  60. (1991). Oxidation of Sil_ýGex alloys at atmospheric and elevated pressure". journal of applied physics, doi
  61. Physically-based threshold voltage determination for MOSFETs of all gate lengths". doi
  62. (1989). Physics and applications of semiconductor microstructures. doi
  63. Properties of semiconductor surface inversion layers in the electric quantum limit". physical review, doi
  64. (1995). Properties of strained and relaxed silicon germanium. doi
  65. Reconsidering germanium". solid state technology,
  66. Relaxation of strained Si layers grown on SiGe buffers". journal of vacuum science and technology doi
  67. Relaxed SiGe-on-insulator substrates without thick SiGe buffer layers". applied physics letters, doi
  68. reports on progress in modern physics, doi
  69. Scattering mechanism and low temperature mobility of MOS inversion layers". Japanese journal of applied physics, suppliment 2(part 2): doi
  70. Scattering mechanisms affecting hole transport in remote-doped Si/SiGe heterostructures". journal of applied physics, doi
  71. (2004). Scattering mechanisms in high-mobility strained Ge channels". journal of applied physics, doi
  72. (1985). Semiconductor devices physics and technology. doi
  73. (2006). Semiconductor material and device chacterization. doi
  74. (2004). Semiconductor physics. doi
  75. SiGe relaxation on siliconon-insulator substrates: an experimental and modelling study". journal of applied physics, doi
  76. (2007). SiGeO layer formation mechanism at the SiGe/oxide interfaces during Ge condensation". applied physics letters, 90(3): 032111, doi
  77. Strain and lattice engineering for Ge FET devices". materials science in semiconductor processing, doi
  78. Strain relaxation mechanism in SiGe-on-insulator fabricated by Ge condensation". journal of crystal growth, doi
  79. Strained Si, SiGe and Ge on-insulator: review of wafer bonding fabrication techniques". solid-state electronics, doi
  80. Study of strain relaxation in Si/SiGe metal-oxide-semiconductor field-effect transistors". journal of applied physics, doi
  81. (1990). Surface electronic transport phenomena in semiconductors.
  82. Technological innovation in low-dose SIMOX wafers fabricated by an internal thermal oxidation (ITOX) process". microelectronic engineering, doi
  83. Temperature dependence of gate induced drain leakage current in silicon CMOS devices". electronics letters, doi
  84. Temperature dependence of the conductivity for the twodimensional electron gas: analytical results for low temperatures" . physical review doi
  85. Temperature effects on Ge condensation by thermal oxidation of SiGe-oninsulator structures".
  86. The diffusion of oxygen in silicon and germanium". journal of the physics and chemistry of solids, doi
  87. The formation of SGOI structures with low dislocation density by a two-step oxidation and condensation method". semiconductor science and technology, doi
  88. The impact of Gate-Induced Drain Leakage on MOSFET scaling". doi
  89. The standard thermodynamic functions for the formation of electrons and holes in Ge, Si, GaAs and GaP". journal of the electrochemical society: solid-state science and technology, doi
  90. Thermal diffusion behavior of implanted germanium atoms in silicon dioxide film measured by high-resolution RBS". doi
  91. Ultrahigh room-temperature hole Hall and effective mobility in Si0_3Ge0,7/Ge/Sio. 3Geo. 7 heterostructures". applied physics letters, doi
  92. Ultrashallow junctions or ultrathin SOI? ". solid state technology,
  93. Understanding the differences in the effective-field dependence of electron and hole inversion layer mobilities". doi

To submit an update or takedown request for this paper, please submit an Update/Correction/Removal Request.