The distribution of radiation‐induced charged defects and neutral electron traps in SiO2, and the threshold voltage shift dependence on oxide thickness

As insulated gate field effect transistor dimensions continue to decrease, and fabrication sequences rely increasingly on processes that involve ionizing radiation, it becomes essential to understand the radiation‐induced threshold voltage shift (ΔVT) dependence on gate‐insulator thickness (tox), since threshold voltage tolerances are required to scale with device dimensions. In the present study, n‐channel insulated gate field effect transistor devices were fabricated with gate‐insulator thicknesses ranging from 6–50 nm, and were then exposed in an unbiased state to AlKα x‐ray radiation to simulate process‐induced ionizing radiation exposure. Gate‐oxide Coulombic defects and neutral electron traps were measured before and after irradiation using optically assisted electron injection. Following irradiation and injection, the measured voltage shifts indicated that the ‘‘extrinsic’’ defects are localized near, but not at, the Si/SiO2 interface. For oxide thicknesses where the top gate electrode lies in the ...

[1]  MOS Hardness Characterization and Its Dependence upon Some Process and Measurement Variables , 1976, IEEE Transactions on Nuclear Science.

[2]  J. Aitken,et al.  1 µm MOSFET VLSI technology: Part VIII—Radiation effects , 1979, IEEE Transactions on Electron Devices.

[3]  Stephen Aplin Lyon,et al.  Location of positive charge trapped near the Si‐SiO2 interface at low temperature , 1986 .

[4]  A. Reisman,et al.  Device, circuit, and technology scaling to micron and submicron dimensions , 1983, Proceedings of the IEEE.

[5]  B. L. Gregory,et al.  Process Optimization of Radiation-Hardened CMOS Integrated Circuits , 1975, IEEE Transactions on Nuclear Science.

[6]  K. Y. Chiu,et al.  MOS Hardening Approaches for Low-Temperature Applications , 1977, IEEE Transactions on Nuclear Science.

[7]  H. Tango,et al.  Radiation-Induced Interface States of Poly-Si Gate MOS Capacitors Using Low Temperature Gate Oxidation , 1983, IEEE Transactions on Nuclear Science.

[8]  A. Reisman,et al.  The effects of pressure, temperature, and time on the annealing of ionizing radiation induced insulator damage in N-channel IGFET's , 1983 .

[9]  J. Maldonado,et al.  Generation and annealing of defects in silicon dioxide , 1987 .

[10]  E. P. EerNisse,et al.  Viscous Shear Flow Model for MOS Device Radiation Sensitivity , 1976, IEEE Transactions on Nuclear Science.

[11]  H. L. Hughes,et al.  CMOS Scaling Implications for Total Dose Radiation , 1985, IEEE Transactions on Nuclear Science.

[12]  C. R. Viswanathan,et al.  Model for Thickness Dependence of Radiation Charging in MOS Structures , 1976, IEEE Transactions on Nuclear Science.

[13]  H. E. Boesch,et al.  Annealing of MOS Capacitors with Implications for Test Procedures to Determine Radiation Hardness , 1981, IEEE Transactions on Nuclear Science.

[14]  J. McGarrity.  Considerations for Hardening MOS Devices and Circuits for Low Radiation Doses , 1980, IEEE Transactions on Nuclear Science.

[15]  M. Shimaya,et al.  Ionizing Radiation Effects in MOS Capacitors with Very Thin Gate Oxides , 1983 .

[16]  F. J. Grunthaner,et al.  Radiation-Induced Defects in SiO2 as Determined with XPS , 1982, IEEE Transactions on Nuclear Science.

[17]  B. F. Lewis,et al.  XPS Studies of Structure-Induced Radiation Effects at the Si/SiO2 Interface , 1980, IEEE Transactions on Nuclear Science.

[18]  J. Maldonado,et al.  Low Energy X‐Ray and Electron Damage to IGFET Gate Insulators , 1984 .

[19]  Arnold Reisman,et al.  X‐Ray Damage Considerations in MOSFET Devices , 1986 .

[20]  W. Haller,et al.  Effects of ionizing radiation on thin‐oxide (20–1500 Å) MOS capacitors , 1974 .

[21]  Enhanced Flatband Voltage Recovery in Hardened Thin MOS Capacitors , 1978, IEEE Transactions on Nuclear Science.

[22]  T. Ning.  Capture cross section and trap concentration of holes in silicon dioxide , 1976 .

[23]  H. E. Boesch,et al.  Charge Yield and Dose Effects in MOS Capacitors at 80 K , 1976, IEEE Transactions on Nuclear Science.

[24]  E. H. Nicollian,et al.  The modelling of silicon oxidation from 1 × 10−5 to 20 atmospheres , 1987 .

[25]  Oxide thickness dependence of high‐energy‐electron‐, VUV‐, and corona‐induced charge in MOS capacitors , 1976 .

[26]  Carlton M. Osburn,et al.  Challenges in advanced semiconductor technology in the ulsl era for computer applications , 1987 .

[27]  D. Young,et al.  Radiation induced electron traps in silicon dioxide , 1983 .

[28]  R. Williams,et al.  Prompt Radiation Damage and Short Term Annealing in CMOS/SOS Devices , 1976, IEEE Transactions on Nuclear Science.

[29]  A. Reisman,et al.  A controlled radiation source and electron/X-ray flux ratios in an electron beam metal evaporator , 1988 .

[30]  T. Ma,et al.  Effect of gamma‐ray irradiation on the surface states of MOS tunnel junctions , 1974 .

[31]  Mario G. Ancona,et al.  Generation of Interface States by Ionizing Radiation in Very Thin MOS Oxides , 1986, IEEE Transactions on Nuclear Science.

[32]  J. A. Modolo,et al.  Radiation Effects in MOS Capacitors with Very Thin Oxides at 80°K , 1984, IEEE Transactions on Nuclear Science.

[33]  T. R. Oldham,et al.  Spatial Dependence of Trapped Holes Determined from Tunneling Analysis and Measured Annealing , 1986, IEEE Transactions on Nuclear Science.

[34]  B. L. Gregory,et al.  Unified Model of Damage Annealing in CMOS, from Freeze-In to Transient Annealing , 1975, IEEE Transactions on Nuclear Science.

[35]  D. B. Brown,et al.  Photon Energy Dependence of Radiation Effects in MOS Structures , 1980, IEEE Transactions on Nuclear Science.