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The power of approximate tests for the regression coefficients in a gamma regression model
World Abstracts on Microelectronics and Reliability
only is the design simple and efficient, but it can be expected to be tolerant to process variations. A comparison of SEF with conventional techniques for dealing with soft errors shows the former to be generally much more attractive, from the point of view of both area and time overhead.
being latched in the corresponding registers. Several approaches to the problem of designing filtering latches are compared. This comparison demonstrates the superiority of a double-filter realization. The design for a CMOS implementation of the double-filter latch is presented. Not
7. S E M I C O N D U C T O R
INTEGRATED
CIRCUITS,
Hot-electron trapping and generic reliability o f p ÷ polysilicon/ Si02/Si structures for fine-line CMOS technology. L. MANCHANDA. 24 a. Proc. IEEE Reliab. Phys. Syrup., 183 (1986). The generic reliability of p* polysilicon/SiO2/Si structure has been investigated using avalanche injection method on MOS capacitors. Hot-electron trapping in p+ polysilicon/SiO2/Si capacitors with 250A and 500A thick oxides was compared with n ÷ polysilicon/SiO2/Si capacitors. For the identical injection conditions, p+ polysilicon gate capacitors show larger threshold voltage shifts compared to n ÷ polysilicon gate capacitors with the same thickness. These threshold voltage shifts were significantly reduced after the standard low temperature H 2 anneal. A correlation of hot-electron trapping before and after the hydrogen anneal indicates that boron atoms themselves do not act as electron traps in SiO2, but the presence of boron in SiO 2 enhances the water-related electron traps. A model is proposed and supported by Infrared measurements on TEOS and BTEOS films. Ionic concentrations found in pure water used by the semiconductor industry. JANA HOUSKOVAand THERESACHU. Solid St. Technol., 205 (May 1986). The most commonly used instrument which presently monitors the ionic content of ultrapure water is the conductivity cell. However, the conductivity measurements provided by these cells, besides being influenced by several factors, also fail to offer any information about specific ions. A new approach is described that can monitor ions in high purity water through the application of ion chromatography. The required level of sensitivity is achieved by using preconcentration. It is shown that field sampling with bottles that are returned to the ionchromatography laboratory is an acceptable practise. Results of an ion chromatography study on pure water from 15 LSI and VLSI manufacturers are presented. Microlithographic techniques for high speed GaAs field effect transistors. J. F. ALLISON,W. H. CHANG,L. B. HOLDEMAN and T. SMITH. Solid St. Technol., 169 (June 1986). Microlithographic techniques for fabricating source, drain and gate electrodes for high-speed GaAs metal-semiconductor field effect transistors (MESFETs) are addressed. Source and drain electrodes of the MESFETs are produced using liftoff techniques and conventional optical lithography. Submicron
8. T H I C K -
AND
THIN-FILM
COMPONENTS,
Thick film temperature sensors using standard pastes. I. JANOSKA and M. R. HASKARD. Active Passive Electron. Compon. 12, 91 (1986). Standard thick film resistor pastes exhibit changes in their electrical characteristics when printed on top of dielectric layers. Of particular interest is the inherent change in their temperature coefficient of resistance. Simple temperature sensors were formed by deliberately printing thick film resistor pastes on top of larger area dielectric layers. Temperature tests carried out on these devices have shown that by selecting the correct paste combination and resistor aspect ratio stable, repeatable, temperature sensors with good linearity can be manufactured. A comparison is made of these sensors to other commercially available products currently used in the thick film industry.
593
DEVICES
AND
MATERIALS
gate formation using an angle evaporation is described. Electron-beam lithographic technology for gate writing and resist profile control are detailed. Data are presented illustrating the use of these techniques in fabricating GaAs FETs and MMICs. The power of approximate tests for the regression coefficients in a gamma regression model. AKRAM M. AL-ABOOD and DAVID H. YOUNG. IEEE Trans. Reliab. R-35, 216 (1986). A gamma regression model which has wide application in lifetesting and analysis of point processes is considered. Approximate statistical tests for the regression coefficients based on maximum likelihood and weighted least squares fits of the model are considered. The power and significance level properties of the tests are evaluated for a model with a single regressor variate when the underlying gamma distributions have the same shape parameter. The tests give good control over the actual significance levels for all values of the shape parameter. The test using the maximum likelihood estimators has much better power than the test using the weighted least squares estimators for small values of the shape parameter but the power differences are negligible when the shape parameter exceeds five. Silicon films deposited in a vertical-flow reactor. DERRICK FOSTER, ARTHUR LEARN and TED KAMINS. Solid St. Technol., 227 (May 1986). The deposition of silicon films by lowpressure chemical vapor deposition in a unique vertical-flow reactor has been compared to deposition in a conventional tube reactor. The deposition rate increases linearly with increasing silane partial pressure at low partial pressures and saturates at high partial pressures. Gas-depletion effects are less severe in the vertical-flow reactor because its shorter gasflow path results in smaller variations of partial pressure, allowing the vertical-flow reactor to be operated without a temperature gradient along the deposition chamber. The basic film structure and electrical properties of films deposited in the vertical-flow reactor are similar to those of films deposited in a tube reactor; therefore, the improved wafer-to-wafer structural and thickness uniformity of the films can be used readily without changing basic device characteristics. The breakdown voltage of oxides grown on the silicon films was higher when the films were initially amorphous.
HYBRID
CIRCUITS
AND
MATERIALS
Effect of V205 dopant on the electrical conductivity of RuO 2 thick film resistors. M. S. SETTY and R. F. SHINDE. Active Passive Electron. Compon. 12, 111 (1986). Thick film glaze resistors have been prepared using V20 5 doped RuO 2 conducting phase. Different amounts of V20 s were incorporated into RuO 2 lattice by solid state reaction. Sheet resistivity decreased from 235 to 10 kfl/sq, with the increase in the dopant concentration from 2 to 6~wt. The conductivity, 'a', was found to fit in the equation a = KS(1 - S), where S is the probability that a given cationic site will contain an extra charge carrier and K = 10 -3 mhosq. Preparation and properties of a new thick film system. T.
only is the design simple and efficient, but it can be expected to be tolerant to process variations. A comparison of SEF with conventional techniques for dealing with soft errors shows the former to be generally much more attractive, from the point of view of both area and time overhead.
being latched in the corresponding registers. Several approaches to the problem of designing filtering latches are compared. This comparison demonstrates the superiority of a double-filter realization. The design for a CMOS implementation of the double-filter latch is presented. Not
7. S E M I C O N D U C T O R
INTEGRATED
CIRCUITS,
Hot-electron trapping and generic reliability o f p ÷ polysilicon/ Si02/Si structures for fine-line CMOS technology. L. MANCHANDA. 24 a. Proc. IEEE Reliab. Phys. Syrup., 183 (1986). The generic reliability of p* polysilicon/SiO2/Si structure has been investigated using avalanche injection method on MOS capacitors. Hot-electron trapping in p+ polysilicon/SiO2/Si capacitors with 250A and 500A thick oxides was compared with n ÷ polysilicon/SiO2/Si capacitors. For the identical injection conditions, p+ polysilicon gate capacitors show larger threshold voltage shifts compared to n ÷ polysilicon gate capacitors with the same thickness. These threshold voltage shifts were significantly reduced after the standard low temperature H 2 anneal. A correlation of hot-electron trapping before and after the hydrogen anneal indicates that boron atoms themselves do not act as electron traps in SiO2, but the presence of boron in SiO 2 enhances the water-related electron traps. A model is proposed and supported by Infrared measurements on TEOS and BTEOS films. Ionic concentrations found in pure water used by the semiconductor industry. JANA HOUSKOVAand THERESACHU. Solid St. Technol., 205 (May 1986). The most commonly used instrument which presently monitors the ionic content of ultrapure water is the conductivity cell. However, the conductivity measurements provided by these cells, besides being influenced by several factors, also fail to offer any information about specific ions. A new approach is described that can monitor ions in high purity water through the application of ion chromatography. The required level of sensitivity is achieved by using preconcentration. It is shown that field sampling with bottles that are returned to the ionchromatography laboratory is an acceptable practise. Results of an ion chromatography study on pure water from 15 LSI and VLSI manufacturers are presented. Microlithographic techniques for high speed GaAs field effect transistors. J. F. ALLISON,W. H. CHANG,L. B. HOLDEMAN and T. SMITH. Solid St. Technol., 169 (June 1986). Microlithographic techniques for fabricating source, drain and gate electrodes for high-speed GaAs metal-semiconductor field effect transistors (MESFETs) are addressed. Source and drain electrodes of the MESFETs are produced using liftoff techniques and conventional optical lithography. Submicron
8. T H I C K -
AND
THIN-FILM
COMPONENTS,
Thick film temperature sensors using standard pastes. I. JANOSKA and M. R. HASKARD. Active Passive Electron. Compon. 12, 91 (1986). Standard thick film resistor pastes exhibit changes in their electrical characteristics when printed on top of dielectric layers. Of particular interest is the inherent change in their temperature coefficient of resistance. Simple temperature sensors were formed by deliberately printing thick film resistor pastes on top of larger area dielectric layers. Temperature tests carried out on these devices have shown that by selecting the correct paste combination and resistor aspect ratio stable, repeatable, temperature sensors with good linearity can be manufactured. A comparison is made of these sensors to other commercially available products currently used in the thick film industry.
593
DEVICES
AND
MATERIALS
gate formation using an angle evaporation is described. Electron-beam lithographic technology for gate writing and resist profile control are detailed. Data are presented illustrating the use of these techniques in fabricating GaAs FETs and MMICs. The power of approximate tests for the regression coefficients in a gamma regression model. AKRAM M. AL-ABOOD and DAVID H. YOUNG. IEEE Trans. Reliab. R-35, 216 (1986). A gamma regression model which has wide application in lifetesting and analysis of point processes is considered. Approximate statistical tests for the regression coefficients based on maximum likelihood and weighted least squares fits of the model are considered. The power and significance level properties of the tests are evaluated for a model with a single regressor variate when the underlying gamma distributions have the same shape parameter. The tests give good control over the actual significance levels for all values of the shape parameter. The test using the maximum likelihood estimators has much better power than the test using the weighted least squares estimators for small values of the shape parameter but the power differences are negligible when the shape parameter exceeds five. Silicon films deposited in a vertical-flow reactor. DERRICK FOSTER, ARTHUR LEARN and TED KAMINS. Solid St. Technol., 227 (May 1986). The deposition of silicon films by lowpressure chemical vapor deposition in a unique vertical-flow reactor has been compared to deposition in a conventional tube reactor. The deposition rate increases linearly with increasing silane partial pressure at low partial pressures and saturates at high partial pressures. Gas-depletion effects are less severe in the vertical-flow reactor because its shorter gasflow path results in smaller variations of partial pressure, allowing the vertical-flow reactor to be operated without a temperature gradient along the deposition chamber. The basic film structure and electrical properties of films deposited in the vertical-flow reactor are similar to those of films deposited in a tube reactor; therefore, the improved wafer-to-wafer structural and thickness uniformity of the films can be used readily without changing basic device characteristics. The breakdown voltage of oxides grown on the silicon films was higher when the films were initially amorphous.
HYBRID
CIRCUITS
AND
MATERIALS
Effect of V205 dopant on the electrical conductivity of RuO 2 thick film resistors. M. S. SETTY and R. F. SHINDE. Active Passive Electron. Compon. 12, 111 (1986). Thick film glaze resistors have been prepared using V20 5 doped RuO 2 conducting phase. Different amounts of V20 s were incorporated into RuO 2 lattice by solid state reaction. Sheet resistivity decreased from 235 to 10 kfl/sq, with the increase in the dopant concentration from 2 to 6~wt. The conductivity, 'a', was found to fit in the equation a = KS(1 - S), where S is the probability that a given cationic site will contain an extra charge carrier and K = 10 -3 mhosq. Preparation and properties of a new thick film system. T.