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Solid-to-solid diffusion in the gallium arsenide device technology
202
A B S T R A C T S ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
Solid-to-solid diffusion in the g~llium a r s e n i d e d e v i c e technology. W. v. Muv_~CHand H. STATZ, Solid ,St. Electron., 9, (1966), p. 939. The technique of tin and zinc diffusion from doped pyrolytic SiOz-layers has been used to form the base regions of planar n/m- andpnp-GaAs-transistors. By a suitable sequence of deposition and photoresist processes it is possible to obtain a pattern of doped oxide layers which yields planar npn-transistors in a single diffusion step.
THIN-FILM CIRCUITS AND MATERIALS Crystallization o f a m o r p h o u s t i t a n i u m dioxide films prepared by vacuum evaporation. M. SHIOjIaI, J. Phys. Soc. Japan, 21, February (1966), p. 335. An electron microscopy and electron diffraction study was made on the structure of vacuum-deposited films of TiO 2. The films were amorphous when they were deposited on rocksalt at room temperature. When irradiated by an intense electron beam, the amorphous films crystallized in anatase and rutile forms. Resistivity a n d s t r u c t u r e o f sputtered molybdenum films. F. M. D'HEuRLE, Trans. Metall. Soc. AIME, 236, No. 3, March (1966), p. 321. Films of Mo have been prepared by sputtering on to oxidized silicon substrates. The resistivity lattice parameter, orientation and grain size were studied as a function of substrate temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600× 10-e ohm-era). T h e preparation and properties o f sputtered a l u m i n i u m thin films. H. C. COOK, C. W. COWNCTON and J. F. LIBSCH,Trans. Metal[. Soc..dIME, 236, March (1966), p. 314. Sputtered aluminium thin films were prepared in each of two conventional bell-jar vacuum systems. One system utilized an inner "getter sputtering" enclosure; the second system was a standard diode sputtering arrangement. Consistent and repeatable film properties were obtained in both systems provided sufficient clean-up and presputter time was allowed. The various problems associated with aluminium sputtering are discussed, with particular attention to the minimization of film contamination by outgassing and oxidation. The growth and structure of the aluminuim thin films were studied with the aid of electron microscopy and related to deposition rate, substrate temperature and film thickness. The resistivity of the films was correlated to film structure and surface roughness. Resistivities as low as 3-5 ~q-cm (1.3 × bulk resistivity) were measured for relatively thick films (10,000 A). Conduction in discontinuous m e t a l films. L. A. WEITZENKAMPand N. M. BASHARA,Trans. Metall. Soc. AIME, 236, March (1966), p. 351. A study of the electrical conductivity of gold films less than 200 A in thickness indicates a negative temperature coefficient of resistance and a thermal activation energy of less than 0-25 eV. The films consist of discrete metal islands of linear dimensions from a few angstroms to 1000 A. Films were able to withstand applied fields up to 60,000 V per cm before breakdown occurred. A model for the conduction mechanism is proposed which involves a potential barrier due to work function, image forces, and an electrostatic potential arising from separating an electron from a neutral island leaving behind a positively charged metal island. Activation energies of less than 0.25 eV are consistent with this model, which includes a tunneling and/or thermal mechanism for conduction between the separate metal islands. An apparent saturation effect in conductivity at high fields is observed experimentally. The saturation effect may be explained by the influence of the electrostatic contribution to the potential barriers for the transition through several islands adjacent to the original island which was activated to give up an electron. The proposed model gives poor quantitative agreement for the internal electrical field between islands.
Resistivity and s t r u c t u r e o f sputtered molybdenum films. F. M. D'HEuRLE, Trans. Metall. Soc. AIME, 236, March (1966), p. 321. Films of molybdenum have been prepared by sputtering on to oxidized silicon substrates. The resistivity, lattice parameter, orientation and grain size were studied as a function of substrata temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600× 10-s ~-cm). However, with the use of the negative substrata bias of 100 V and a substrata temperature of 350°C, films were produced with a resistivity of about t~vice that of bulk molybdenum. The lattice parameters measured in a direction normal to the
A B S T R A C T S ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
Solid-to-solid diffusion in the g~llium a r s e n i d e d e v i c e technology. W. v. Muv_~CHand H. STATZ, Solid ,St. Electron., 9, (1966), p. 939. The technique of tin and zinc diffusion from doped pyrolytic SiOz-layers has been used to form the base regions of planar n/m- andpnp-GaAs-transistors. By a suitable sequence of deposition and photoresist processes it is possible to obtain a pattern of doped oxide layers which yields planar npn-transistors in a single diffusion step.
THIN-FILM CIRCUITS AND MATERIALS Crystallization o f a m o r p h o u s t i t a n i u m dioxide films prepared by vacuum evaporation. M. SHIOjIaI, J. Phys. Soc. Japan, 21, February (1966), p. 335. An electron microscopy and electron diffraction study was made on the structure of vacuum-deposited films of TiO 2. The films were amorphous when they were deposited on rocksalt at room temperature. When irradiated by an intense electron beam, the amorphous films crystallized in anatase and rutile forms. Resistivity a n d s t r u c t u r e o f sputtered molybdenum films. F. M. D'HEuRLE, Trans. Metall. Soc. AIME, 236, No. 3, March (1966), p. 321. Films of Mo have been prepared by sputtering on to oxidized silicon substrates. The resistivity lattice parameter, orientation and grain size were studied as a function of substrate temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600× 10-e ohm-era). T h e preparation and properties o f sputtered a l u m i n i u m thin films. H. C. COOK, C. W. COWNCTON and J. F. LIBSCH,Trans. Metal[. Soc..dIME, 236, March (1966), p. 314. Sputtered aluminium thin films were prepared in each of two conventional bell-jar vacuum systems. One system utilized an inner "getter sputtering" enclosure; the second system was a standard diode sputtering arrangement. Consistent and repeatable film properties were obtained in both systems provided sufficient clean-up and presputter time was allowed. The various problems associated with aluminium sputtering are discussed, with particular attention to the minimization of film contamination by outgassing and oxidation. The growth and structure of the aluminuim thin films were studied with the aid of electron microscopy and related to deposition rate, substrate temperature and film thickness. The resistivity of the films was correlated to film structure and surface roughness. Resistivities as low as 3-5 ~q-cm (1.3 × bulk resistivity) were measured for relatively thick films (10,000 A). Conduction in discontinuous m e t a l films. L. A. WEITZENKAMPand N. M. BASHARA,Trans. Metall. Soc. AIME, 236, March (1966), p. 351. A study of the electrical conductivity of gold films less than 200 A in thickness indicates a negative temperature coefficient of resistance and a thermal activation energy of less than 0-25 eV. The films consist of discrete metal islands of linear dimensions from a few angstroms to 1000 A. Films were able to withstand applied fields up to 60,000 V per cm before breakdown occurred. A model for the conduction mechanism is proposed which involves a potential barrier due to work function, image forces, and an electrostatic potential arising from separating an electron from a neutral island leaving behind a positively charged metal island. Activation energies of less than 0.25 eV are consistent with this model, which includes a tunneling and/or thermal mechanism for conduction between the separate metal islands. An apparent saturation effect in conductivity at high fields is observed experimentally. The saturation effect may be explained by the influence of the electrostatic contribution to the potential barriers for the transition through several islands adjacent to the original island which was activated to give up an electron. The proposed model gives poor quantitative agreement for the internal electrical field between islands.
Resistivity and s t r u c t u r e o f sputtered molybdenum films. F. M. D'HEuRLE, Trans. Metall. Soc. AIME, 236, March (1966), p. 321. Films of molybdenum have been prepared by sputtering on to oxidized silicon substrates. The resistivity, lattice parameter, orientation and grain size were studied as a function of substrata temperature and substrate bias. Under normal sputtering conditions, the resistivity of the films was found to be quite high (600× 10-s ~-cm). However, with the use of the negative substrata bias of 100 V and a substrata temperature of 350°C, films were produced with a resistivity of about t~vice that of bulk molybdenum. The lattice parameters measured in a direction normal to the