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Physics and technology of vapour phase epitaxial growth of GaAs—a review
World Abstracts on Microelectronics and Reliability automatic system, designed to measure electrical properties, is used to study the homogeneity of gallium arsenide crystals grown in our laboratory. Material resistivity and carriers mobility are determined locally by means of Hall effect measurements. These characteristics are taken on 800 points of a 50mm diameter wafer, which enables assessment of the radial and longitudinal homogeneity of the single crystal. Most of the undoped, semi-insulating substrates used for the production of GaAs integrated circuits have been characterized using this method. Mechanism of oxide leakage current of silicide gate MOSFET's. T. WATANABE,H. ISHIUCHI, T. TANAKA, T. MOCHIZUKI and O. OZAWA. Proc. IEEE Reliab. Phys. Conf. 193 (1984). Oxide leakage currents of silicide gate MOSFET's have been studied. It has been revealed that large oxide leakage currents flow under the negative gate bias in spite of reasonable Fowler-Nordheim currents under the positive gate bias. Local electric field enhancement due to the interfacial molybdenum silicide asperity well explains the experimental results. The free charge carrier effects on elastic properties of silicon. N. S. AVERKIEV,Yu V. ILISAVSKIYand V. M. STERNIN. Solid St. Commun. 52 (1), 17 (1984). The exact theory of the free hole contribution to the elastic moduli of p-Si taking into account all three valence bands is developed. The fair agreement is found between this theory and experimental measurements of the concentration dependence of sound velocity made for p-Si with different boron content. For n-Si analogous measurements were made and the results agree well with the theory of Keyes. Physics and technology of vapour phase epitaxial growth of G a A s - - a review. B. P. JAIN and R. K. PUROH1T. Prog. Crystal Growth Charact. 9, 51 (1984). The chemical vapour phase epitaxial process refers to the formation of a condensed phase from a gaseous medium of different chemical composition. In the chemical vapour transport process the condensed phase reacts with a transport agent to produce volatile substances which in another region undergoes a chemical reaction to form the condensed phase of the required material. This recondensed phase then deposits on a suitable substrate. Therefore, the chemical vapour growth requires both a source and a transport agent. The main advantages of the chemical vapour growth are as follows: 1. Growth of material far below their melting point. 2. Growth from high purity starting materials. 3. Near equilibrium growth. 4. Atmospheric pressure operation. 5. Multiple choice of starting material.
8. T H I C K -
AND
THIN-FILM
COMPONENTS,
The role of thermal grooving, thermotransport and electrotransport on the failure of thin film metallizations. R. E. HUMMEL, S. MATTS GOHO and R. T. DEHOFF. Proc. IEEE Reliab. Phys. Conf. 234 (1984). Grain boundary grooving, thermotransport and electrotransport operate simultaneously during current stressing of thin film metallizations. For different operating conditions or positions along a stripe, they may compete or reinforce each other in promoting hole formation. This work demonstrates that second components may influence this competition in a variety of ways. As the interactions become better understood, they may ultimately provide the basis for controlling hole formation and predicting reliability of thin film stripes. Hybrid packaging for the 1980s at EDI. PIETERBURGGRAAF. Semiconductor Int. 58 (July 1984). Combined leading-edge ICs in standard packages yields a hybrid circuit that precedes future monolithic IC trends.
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6. Thin film layers of various properties and variable composition possible through gas compositional control. 7. Insulating substrate may also be used. 8. Heteroepitaxy possible. 9. Impurity easily controllable. 10. Large scale multislice operation adaptability. As with other systems, CDV also has certain disadvantages. Investigations of metal-insulator-semiconductor structure inhomogeneities using a small-size mercury probe. R. S. NAKHMANSON and S. B. SEVASTIANOV. Solid-St. Electron. 27 (10), 881 (1984). Capacitance and (under feedback mode of operation) bias voltage of Hg-SiO2-Si structures were measured using a 7gm diam. mercury probe as a metal contact. The measurements were carried out both with separate points and during continuous scanning of the investigated surface. The inhomogeneities of insulator capacitance, built-in charge, surface state charge and doping level could be measured separately. The accuracy of measuring was approximately 1 ~ , the resolving power was better than 1 gm. The inhomogeneity of the electrophysical state of the interface was found to be connected mainly with inhomogeneity of built-in charge. The charge inhomogeneities looked like peaks or steps on a relatively homogeneous background. The charge distribution was not a Gaussian. The more the deviation of the varying physical parameter from its mean value the larger was the space size 2 of this inhomogeneity. The results touch upon the assumption that the idea about a geometrical spectrum of charge fluctuations must be corrected to emphasize large 2 components (like a 1/f frequency spectrum of noise). Space-charge behaviour of "thin-MOS" diodes with MBEgrown silicon films. UDO LIENEWEGand JOHN C. BEAN. SolidSt. Electron. 27 (10), 867 (1984). We present basic theoretical and experimental characteristics of a novel "Thin-MOS" technology, which has promising aspects for integrated highfrequency devices up to several hundred gigahertz. The operation of such devices depends on charge injection into undoped silicon layers of ~1000-,~ thickness, grown by molecular beam epitaxy on heavily doped substrates, a n d isolation by thermally grown oxides of ~ 100-~ thickness. Capacitance-voltage characteristics measured at "high" and "low" frequencies agree well with theoretical ones derived from uni- and ambipolar space-charge models. We conclude that after oxidation the residual doping in the epilayer is less than ~ 10 t6 cm--3 and rises by three orders of magnitude at the substrate interface within less than 100,~ and that interface states at the oxide interface can be kept low.
HYBRID
CIRCUITS
AND
MATERIALS
Cleaning processes for H|C's with solder paste. SUSAN D. SCHLOUGH and EDWARD F. O'CONNELL. IEEE Trans. Components Hybrids Mfg Technol. CHMT-7 (2), 176 (1984). The use of solder paste for hybrid integrated circuit (HIC) assembly is increasing. However the full potential of solder paste has not yet been realized, partly because the fluxing systems may be very different from paste to paste. Therefore choosing the proper cleaning treatment is not trivial. In addition to removing any soldering flux present, the cleaning treatment must also effectively remove any solder spheres formed during reflow. Our work to identify the most effective combinations of cleaning treatments and solder pastes is described. The effects of paste reflow atmosphere on ease of cleaning were investigated. Cleaning techniques were assessed first visually and then by ionic contamination measurements. Those paste/cleaning combinations that seemed most promising were evaluated for accelerated aging performance. It was found that (1) conventional detergent cleaning (with
8. T H I C K -
AND
THIN-FILM
COMPONENTS,
The role of thermal grooving, thermotransport and electrotransport on the failure of thin film metallizations. R. E. HUMMEL, S. MATTS GOHO and R. T. DEHOFF. Proc. IEEE Reliab. Phys. Conf. 234 (1984). Grain boundary grooving, thermotransport and electrotransport operate simultaneously during current stressing of thin film metallizations. For different operating conditions or positions along a stripe, they may compete or reinforce each other in promoting hole formation. This work demonstrates that second components may influence this competition in a variety of ways. As the interactions become better understood, they may ultimately provide the basis for controlling hole formation and predicting reliability of thin film stripes. Hybrid packaging for the 1980s at EDI. PIETERBURGGRAAF. Semiconductor Int. 58 (July 1984). Combined leading-edge ICs in standard packages yields a hybrid circuit that precedes future monolithic IC trends.
593
6. Thin film layers of various properties and variable composition possible through gas compositional control. 7. Insulating substrate may also be used. 8. Heteroepitaxy possible. 9. Impurity easily controllable. 10. Large scale multislice operation adaptability. As with other systems, CDV also has certain disadvantages. Investigations of metal-insulator-semiconductor structure inhomogeneities using a small-size mercury probe. R. S. NAKHMANSON and S. B. SEVASTIANOV. Solid-St. Electron. 27 (10), 881 (1984). Capacitance and (under feedback mode of operation) bias voltage of Hg-SiO2-Si structures were measured using a 7gm diam. mercury probe as a metal contact. The measurements were carried out both with separate points and during continuous scanning of the investigated surface. The inhomogeneities of insulator capacitance, built-in charge, surface state charge and doping level could be measured separately. The accuracy of measuring was approximately 1 ~ , the resolving power was better than 1 gm. The inhomogeneity of the electrophysical state of the interface was found to be connected mainly with inhomogeneity of built-in charge. The charge inhomogeneities looked like peaks or steps on a relatively homogeneous background. The charge distribution was not a Gaussian. The more the deviation of the varying physical parameter from its mean value the larger was the space size 2 of this inhomogeneity. The results touch upon the assumption that the idea about a geometrical spectrum of charge fluctuations must be corrected to emphasize large 2 components (like a 1/f frequency spectrum of noise). Space-charge behaviour of "thin-MOS" diodes with MBEgrown silicon films. UDO LIENEWEGand JOHN C. BEAN. SolidSt. Electron. 27 (10), 867 (1984). We present basic theoretical and experimental characteristics of a novel "Thin-MOS" technology, which has promising aspects for integrated highfrequency devices up to several hundred gigahertz. The operation of such devices depends on charge injection into undoped silicon layers of ~1000-,~ thickness, grown by molecular beam epitaxy on heavily doped substrates, a n d isolation by thermally grown oxides of ~ 100-~ thickness. Capacitance-voltage characteristics measured at "high" and "low" frequencies agree well with theoretical ones derived from uni- and ambipolar space-charge models. We conclude that after oxidation the residual doping in the epilayer is less than ~ 10 t6 cm--3 and rises by three orders of magnitude at the substrate interface within less than 100,~ and that interface states at the oxide interface can be kept low.
HYBRID
CIRCUITS
AND
MATERIALS
Cleaning processes for H|C's with solder paste. SUSAN D. SCHLOUGH and EDWARD F. O'CONNELL. IEEE Trans. Components Hybrids Mfg Technol. CHMT-7 (2), 176 (1984). The use of solder paste for hybrid integrated circuit (HIC) assembly is increasing. However the full potential of solder paste has not yet been realized, partly because the fluxing systems may be very different from paste to paste. Therefore choosing the proper cleaning treatment is not trivial. In addition to removing any soldering flux present, the cleaning treatment must also effectively remove any solder spheres formed during reflow. Our work to identify the most effective combinations of cleaning treatments and solder pastes is described. The effects of paste reflow atmosphere on ease of cleaning were investigated. Cleaning techniques were assessed first visually and then by ionic contamination measurements. Those paste/cleaning combinations that seemed most promising were evaluated for accelerated aging performance. It was found that (1) conventional detergent cleaning (with