- Email: [email protected]
Thermal management techniques keep semiconductors cool
World Abstracts continued from page 43
Heat transfer correlations for use in naturally cooled enclosures with high-power integrated circuits R. D. FLACK and B. L. T U R N E R IEEE Trans. Components, Hybrids Atfng TechnoL Chmt-3(3), 449 (1980). Heat transfer rates were experimentally measured in an air-filled two-dimensional simplified model of a naturally cooled rectangular enclosure with a concentrated energy source representing a highpower integrated circuit (IC). q'he aspect ratio of the enclosure and the size and location of the source were parametrically varied. Correlations are presented such that a component temperature rise can be estimated if the energy dissipation rate is known in a specified design. On the physics and modeling of small semiconductor devices - I J. R. B A R K E R and D. K. FERRY Solid-St. Electron. 23,519 (1980). Current LSI technology has progressed rapidly and is pushing toward fabrication of submicron dimensional devices. Several authors have previously used static characteristics, power dissipation, noise, and packing density to look at limiting properties of small devices, although the actual device physics was not considered in detail. As devices become smaller, we expect that the temporal and spatial scales in these devices become sufficiently small that the semi-classical approach to transport theory, as expressed by the Boltzmann transport equation, becomes of questionable validity. In this paper, we address the question of whether our physical understanding of devices and their operation can be extrapolated to small space and time scales, and to what extent the essential quantum electronics prevents a downscaling. We attempt to lay here a conceptual framework for an ultimate physics of small devices and the modeling necessary to characterise these devices. In this first paper, we work with a dimensional scale of ! -- 2500]~, the medium small device, leaving a smaller scale to a subsequent work. Although this scale is marginally in a region where the semi-classical approach is valid, extensive modifications must be made to incorporate several new physical effects, including: intro-collision field effect, retarded spatial and temporal non-local effects, two-dimensional quantisation, memory effects in the transport parameters, nonlinear screening/descreening, and multiple scattering effects. On the physics and modeling of small semiconductor devices II. The very small device J. R. B A R K E R and D. K. FERRY Solid-St. Electron. 23, 531 (1980). In a previous paper, we attempted to lay a conceptual framework for an ultimate physics of small semiconductor devices and concentrated on the medium small device.. Here we treat the very small device (VSD), characterised by an effective channel length of 2 5 0 ~ We demonstrate how such a device could conceivably be fabricated using two side processing of the wafer. In treating the transport, however, it is found that the time and distance scales are such that the Boltzmann transport equation is completely invalidated. Here we develop the appropriate quantum transport equations'based upon the density matrix for the entire system, device plus boundaries plus environment. It is found that the boundaries and environment can lead to renormalisation of the energy spectrum as well as long range dissipative interactions Two special cases of the transport equations are treated. If the transport is dominantly stochastic, an exact Langevin equation is found for the various transport parameters. In a second case, a parameterisod density matrix is used in analogy to the displaced Maxwellian. In this latter case, a hierarchy of moment equations can be developed to yield, e.g. energy and momentum balance equations. The influence of VLSI circuitry on the progress of microlithographic equipment K. KASCHLIK Jena Rev. 2, (57) (1980). The development towards degrees of integration of 10~ functions per chip and beyond (Very-Large-Scale-Integration, VLSI technology) proceeds concurrently with the application of continuously larger silicon slice diameters for the production of the integrated circuits as a principal method to increase production. Silicon wafers of 3" and 4" in diameter represent now the top product on the international market and experts foresee the introduction of wafers having diameters of 5"
44
(125mm) and 6" (150ram). Implementation of such objectives necessitates new processes and instruments for use in research, development and production of microelectronic modules. Thermal management techniques keep semiconductors cool G. OWEN Electronics p. 135 (1980). Heat-dissipation requirements depend on device and heat-sink thermal resistance, type of cooling, maximum junction temperature, mechanical factors, and the thermal environment. On the physics and modeling of small semiconductor devices III. Transient response in the finite collision-duration regime D. K. FERRY and J. R. BARKER Solid-St. Electron. 23,545 (1980). The role of the finite, non-zero collision duration in high electric fields is examined for its effect on transient and over-shoot response of the carrier velocity and energy. The finite collision duration introduces a temporal retardation effect on the collisional relaxation mechanisms for energy and momentum. As a consequence, the effective temperature also undergoes an overshoot behaviour, which leads to a general quickening of the total transient response. Calculations were performed for steady, homogeneous fields utilising a displaced Maxwellian approach. These calculations were performed for GaAs and Si and have significance for sub-micron devices in these materials. The generally faster response leads to the prospect of improved high frequency properties over what is normally expected. Interface charges beneath laser.annealed insulators on silicon T. I. KAMINS, K. F. LEE and J. F. GIBBONS Solid-St. Electron. 23, 1037 (1980). Laser annealing of a thermally grown, silicon-dioxide layer reduces an initially high fixed-charge density. Similar annealing of a siliconnitride-coverd silicon wafer does not markedly improve the interface characteristics. Laser melting and recrystallisation of polycrystalline silicon above a thermally grown oxide does not appreciably increase the interface charges at the underlying silicon-dioxide/single-crystalsilicon interface.
8.
Testing
Chips detects errors in 25 ns B. Le BOSS Electronics (1980). 16-bit IC uses modified Hamming code to detect and correct data errors in fast bipolar and MOS microprocessor systems. A study of diffused bipolar transistors by electron microscopy C. J. BULL, P. ASHBURN and J. P. GOWERS Solid-St. Electron. 23, 953 (1980). Shallow junction bipolar transistorshave been fabricated on bulk (001) silicon starting material using a diffusion processing technology. The resultant junction depths were about 0.5 and 0.8/.tin respectively for the emitter-base and base-collector junctions. The crystallographic defects present have been detected and characterised using a combination of electrical measurements, the electron beam induced current (EBIC) mode of the scanning electron microscope (SEM) and both conventional and high voltage transmission electron microscopy (TEM). Two types of dislocations were identified in the TEM. The first consisted of an orthogonal array of sessile, diffusion-induced edge dislocations located about halfway down in the heavily doped emitter. The second type consisted of 60~ glissile dislocations that looped down from the orthogonal array and in some cases penetrated the emitterbase junction. Observations of a number of 60° dislocations yielded a good correlation between their depth and their contrast when imaged in the EBIC mode of the SEM. The 60° dislocations locally retard the emitter diffusion when they fie near to the emitter-base junction. Local breakdown effects under reverse bias were observed at the sites of these dislocations.
Heat transfer correlations for use in naturally cooled enclosures with high-power integrated circuits R. D. FLACK and B. L. T U R N E R IEEE Trans. Components, Hybrids Atfng TechnoL Chmt-3(3), 449 (1980). Heat transfer rates were experimentally measured in an air-filled two-dimensional simplified model of a naturally cooled rectangular enclosure with a concentrated energy source representing a highpower integrated circuit (IC). q'he aspect ratio of the enclosure and the size and location of the source were parametrically varied. Correlations are presented such that a component temperature rise can be estimated if the energy dissipation rate is known in a specified design. On the physics and modeling of small semiconductor devices - I J. R. B A R K E R and D. K. FERRY Solid-St. Electron. 23,519 (1980). Current LSI technology has progressed rapidly and is pushing toward fabrication of submicron dimensional devices. Several authors have previously used static characteristics, power dissipation, noise, and packing density to look at limiting properties of small devices, although the actual device physics was not considered in detail. As devices become smaller, we expect that the temporal and spatial scales in these devices become sufficiently small that the semi-classical approach to transport theory, as expressed by the Boltzmann transport equation, becomes of questionable validity. In this paper, we address the question of whether our physical understanding of devices and their operation can be extrapolated to small space and time scales, and to what extent the essential quantum electronics prevents a downscaling. We attempt to lay here a conceptual framework for an ultimate physics of small devices and the modeling necessary to characterise these devices. In this first paper, we work with a dimensional scale of ! -- 2500]~, the medium small device, leaving a smaller scale to a subsequent work. Although this scale is marginally in a region where the semi-classical approach is valid, extensive modifications must be made to incorporate several new physical effects, including: intro-collision field effect, retarded spatial and temporal non-local effects, two-dimensional quantisation, memory effects in the transport parameters, nonlinear screening/descreening, and multiple scattering effects. On the physics and modeling of small semiconductor devices II. The very small device J. R. B A R K E R and D. K. FERRY Solid-St. Electron. 23, 531 (1980). In a previous paper, we attempted to lay a conceptual framework for an ultimate physics of small semiconductor devices and concentrated on the medium small device.. Here we treat the very small device (VSD), characterised by an effective channel length of 2 5 0 ~ We demonstrate how such a device could conceivably be fabricated using two side processing of the wafer. In treating the transport, however, it is found that the time and distance scales are such that the Boltzmann transport equation is completely invalidated. Here we develop the appropriate quantum transport equations'based upon the density matrix for the entire system, device plus boundaries plus environment. It is found that the boundaries and environment can lead to renormalisation of the energy spectrum as well as long range dissipative interactions Two special cases of the transport equations are treated. If the transport is dominantly stochastic, an exact Langevin equation is found for the various transport parameters. In a second case, a parameterisod density matrix is used in analogy to the displaced Maxwellian. In this latter case, a hierarchy of moment equations can be developed to yield, e.g. energy and momentum balance equations. The influence of VLSI circuitry on the progress of microlithographic equipment K. KASCHLIK Jena Rev. 2, (57) (1980). The development towards degrees of integration of 10~ functions per chip and beyond (Very-Large-Scale-Integration, VLSI technology) proceeds concurrently with the application of continuously larger silicon slice diameters for the production of the integrated circuits as a principal method to increase production. Silicon wafers of 3" and 4" in diameter represent now the top product on the international market and experts foresee the introduction of wafers having diameters of 5"
44
(125mm) and 6" (150ram). Implementation of such objectives necessitates new processes and instruments for use in research, development and production of microelectronic modules. Thermal management techniques keep semiconductors cool G. OWEN Electronics p. 135 (1980). Heat-dissipation requirements depend on device and heat-sink thermal resistance, type of cooling, maximum junction temperature, mechanical factors, and the thermal environment. On the physics and modeling of small semiconductor devices III. Transient response in the finite collision-duration regime D. K. FERRY and J. R. BARKER Solid-St. Electron. 23,545 (1980). The role of the finite, non-zero collision duration in high electric fields is examined for its effect on transient and over-shoot response of the carrier velocity and energy. The finite collision duration introduces a temporal retardation effect on the collisional relaxation mechanisms for energy and momentum. As a consequence, the effective temperature also undergoes an overshoot behaviour, which leads to a general quickening of the total transient response. Calculations were performed for steady, homogeneous fields utilising a displaced Maxwellian approach. These calculations were performed for GaAs and Si and have significance for sub-micron devices in these materials. The generally faster response leads to the prospect of improved high frequency properties over what is normally expected. Interface charges beneath laser.annealed insulators on silicon T. I. KAMINS, K. F. LEE and J. F. GIBBONS Solid-St. Electron. 23, 1037 (1980). Laser annealing of a thermally grown, silicon-dioxide layer reduces an initially high fixed-charge density. Similar annealing of a siliconnitride-coverd silicon wafer does not markedly improve the interface characteristics. Laser melting and recrystallisation of polycrystalline silicon above a thermally grown oxide does not appreciably increase the interface charges at the underlying silicon-dioxide/single-crystalsilicon interface.
8.
Testing
Chips detects errors in 25 ns B. Le BOSS Electronics (1980). 16-bit IC uses modified Hamming code to detect and correct data errors in fast bipolar and MOS microprocessor systems. A study of diffused bipolar transistors by electron microscopy C. J. BULL, P. ASHBURN and J. P. GOWERS Solid-St. Electron. 23, 953 (1980). Shallow junction bipolar transistorshave been fabricated on bulk (001) silicon starting material using a diffusion processing technology. The resultant junction depths were about 0.5 and 0.8/.tin respectively for the emitter-base and base-collector junctions. The crystallographic defects present have been detected and characterised using a combination of electrical measurements, the electron beam induced current (EBIC) mode of the scanning electron microscope (SEM) and both conventional and high voltage transmission electron microscopy (TEM). Two types of dislocations were identified in the TEM. The first consisted of an orthogonal array of sessile, diffusion-induced edge dislocations located about halfway down in the heavily doped emitter. The second type consisted of 60~ glissile dislocations that looped down from the orthogonal array and in some cases penetrated the emitterbase junction. Observations of a number of 60° dislocations yielded a good correlation between their depth and their contrast when imaged in the EBIC mode of the SEM. The 60° dislocations locally retard the emitter diffusion when they fie near to the emitter-base junction. Local breakdown effects under reverse bias were observed at the sites of these dislocations.