Latent interface-trap buildup and its implications for hardness assurance (MOS transistors)

Long-term anneals at temperatures from 25 degrees C to 135 degrees C were performed on irradiated MOS transistors. Following the normal saturation of interface-trap density (within 10/sup 2/ to 10/sup 5/ s after irradiation), large increases in the number of interface traps were observed for both commercial and radiation-hardened transistors at very long times after irradiation (>10/sup 6/ s at 25 degrees ). This latent buildup of interface traps can be significant, up to a factor of four times larger than the normal saturation value. The latent buildup is thermally activated with an activation energy of 0.47+or-0.08 eV. As a natural consequence of the delay between the normal and the latent buildup, there is a window in time in which little or no interface-trap buildup occurs. Two possible mechanisms for the latent buildup are explored: (1) the direct conversion of oxide traps into interface traps or border traps and (2) the diffusion of molecular hydrogen into the gate oxide from adjacent structures. The latent buildup of interface traps can degrade the performance of ICs in space systems and may cause IC failure at long times. Recommendations are provided for characterizing latent interface-trap buildup. >

[1]  D. Fleetwood.  'Border traps' in MOS devices , 1992 .

[2]  P. V. Dressendorfer,et al.  A Reevaluation of Worst-Case Postirradiation Response for Hardened MOS Transistors , 1987, IEEE Transactions on Nuclear Science.

[3]  P. S. Winokur,et al.  Field- and Time-Dependent Radiation Effects at the SiO2/Si Interface of Hardened MOS Capacitors , 1977, IEEE Transactions on Nuclear Science.

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

[5]  P. S. Winokur,et al.  The Role of Hydrogen in Radiation-Induced Defect Formation in Polysilicon Gate MOS Devices , 1987, IEEE Transactions on Nuclear Science.

[6]  Orientation dependence of interface-trap transformation , 1989 .

[7]  Dennis B. Brown,et al.  Time dependence of interface trap formation in MOSFETs following pulsed irradiation , 1988 .

[8]  T. R. Oldham,et al.  Response of interface traps during high-temperature anneals (MOSFETs) , 1991 .

[9]  R. K. Lawrence,et al.  Post-irradiation behavior of the interface state density and the trapped positive charge , 1990 .

[10]  Daniel M. Fleetwood,et al.  Long‐term annealing study of midgap interface‐trap charge neutrality , 1992 .

[11]  Daniel M. Fleetwood,et al.  Charge yield for cobalt-60 and 10-keV X-ray irradiations of MOS devices , 1991 .

[12]  James R. Schwank,et al.  Correlation of Radiation Effects in Transistors and Integrated Circuits , 1985, IEEE Transactions on Nuclear Science.

[13]  K. F. Galloway,et al.  A Simple Model for Separating Interface and Oxide Charge Effects in MOS Device Characteristics , 1984, IEEE Transactions on Nuclear Science.

[14]  Daniel M. Fleetwood,et al.  Effect of post-oxidation anneal temperature on radiation-induced charge trapping in metal-oxide-semiconductor devices , 1988 .

[15]  B. J. Mrstik,et al.  Si-SiO/sub 2/ interface state generation during X-ray irradiation and during post-irradiation exposure to a hydrogen ambient (MOSFET) , 1991 .

[16]  Daniel M. Fleetwood,et al.  Theory and application of dual-transistor charge separation analysis , 1989 .

[17]  P. S. Winokur,et al.  Physical Mechanisms Contributing to Device "Rebound" , 1984, IEEE Transactions on Nuclear Science.

[18]  P. S. Winokur,et al.  Correlating the Radiation Response of MOS Capacitors and Transistors , 1984, IEEE Transactions on Nuclear Science.

[19]  J.R. Schwank,et al.  Latent thermally activated interface-trap generation in MOS devices , 1992, IEEE Electron Device Letters.

[20]  Daniel M. Fleetwood,et al.  Field dependence of interface-trap buildup in polysilicon and metal gate MOS devices , 1990 .

[21]  P. Winokur,et al.  Simple technique for separating the effects of interface traps and trapped‐oxide charge in metal‐oxide‐semiconductor transistors , 1986 .

[22]  Daniel M. Fleetwood,et al.  Using laboratory X-ray and cobalt-60 irradiations to predict CMOS device response in strategic and space environments , 1988 .

[23]  Daniel M. Fleetwood,et al.  Hardness assurance for low-dose space applications (MOS devices) , 1991 .

[24]  Daniel M. Fleetwood,et al.  Comparison of low-energy x-ray and cobalt-60 irradiations of MOS devices as a function of gate bias , 1991 .

[25]  R. A. Kushner,et al.  Total dose radiation hardness of MOS devices in hermetic ceramic packages , 1988 .

[26]  G. Groeseneken,et al.  A reliable approach to charge-pumping measurements in MOS transistors , 1984, IEEE Transactions on Electron Devices.

[27]  S. Lai,et al.  Interface trap generation in silicon dioxide when electrons are captured by trapped holes , 1983 .

[28]  F. B. McLean.  A Framework for Understanding Radiation-Induced Interface States in SiO2 MOS Structures , 1980, IEEE Transactions on Nuclear Science.

[29]  David L. Griscom,et al.  Diffusion of radiolytic molecular hydrogen as a mechanism for the post‐irradiation buildup of interface states in SiO2‐on‐Si structures , 1985 .

[30]  F. V. Thome,et al.  High-temperature silicon-on-insulator electronics for space nuclear power systems: requirements and feasibility , 1988 .

[31]  R. K. Smeltzer,et al.  Hole Trap Creation in SiO2 by Phosphorus Ion Penetration of Polycrystalline Silicon , 1982, IEEE Transactions on Nuclear Science.