World Abstracts on Microelectronics and Reliability with mobilities ranging from 3,700 to 4,500cm2/Vsec for various Cr-doped GaAs substrates. The concentration of compensating acceptor impurities in semi-insulating GaAs/ PBN substrates is estimated to be 1 x 1016cm-3 or less, and permits the implantation of 2 x 10~6cm -3 channels which exhibit mobilities of 5,700 and 12,000cm2/Vsec at 298 K and 77 K, respectively. Discrete power FET's which exhibit 0.7 watts/mm output and 8 dB associated gain at 8 GHz have been fabricated using these directly implanted semi-insulating GaAs substrates.
Contribution to range statistics of Boron implanted into Silicon at high energies. A. G. K. LUTSCH, C. A. B. BALL, F. D. AURET and H. C. SNYMAN.Microelectron. J. 12 (2) 25 (1981). The theoretical distribution of implanted Boron in Silicon as computed by Gibbons et al. shows physically unrealistic negative values for energies higher than 100keV. The distribution for B in Si has been measured by Auger Electron Spectroscopy for an implant energy of 300 keV. It was found that the third moment as computed by Gibbons is too high. A good curve fitting with the experimental data can be obtained by a simplified Edgeworth distribution with half the third moment value proposed by Gibbons. Implant distributions are predicted for higher energies. Ohmic contacts to Si-implanted InP. EIICHI YAMAGUCH1, TAKASHI NISHIOKA and YOSHIRO OHMACHI. Solid-St. Electron. 24, 263 (1981). Ohmic contacts to Si-implanted, n + layers on semi-insulating InP are investigated on the basis of the transmission line model. It is found that Au/Ni/AuGeNi/InP system shows a good ohmic behaviour with the specific contact resistance Pc of 2 x 10 -5 f2cm 2 and the minimum contact resistance Z c of ~ 2 x 10-3 [2 cm for a Si-dose higher than 2 × 101*cm -2 at 100 or 200keV. The results indicate that, in the FET fabrication, at least 120/~m in length is necessary in order to obtain source and drain electrodes with the minimized resistance. Superfast annealing. WALTER L. BROWN. IEEE Spectrum 50 (April 1981). Application of laser and electron-beam annealing portends three-dimensional ICs and economical photoelectric cells. Investigation of the possibility of the laser trimming of ceramic capacitors. WIESLAW WOLINSKI, MARIAN NOWICKI, ZYGMUNT NIECHODA, JERZY LEMANOWICZ and JANUSZ ZIETEK. Electron Technol. 12 (3) 121 (1979). The new method of the trimming of ceramic capacitors with the accuracy of + 1 ~0 in the capacity range of 12 330pF is presented in this paper. This method is based on the partial removal of one of the electrodes by the focused beam of Nd:YAG laser, and has many advantages over the other trimming techniques. Initial experiments and measurements reported in the paper fully proved the necessity of further development of this method. A new production technique: ion milling. Part l l - Applications. D. BOLLINGER and g. FINK. Solid-St. Technol. 97 (December 1980). A number of physical processes simultaneously occur while a pattern is being milled. Control of the ion milling system parameters provides a means to adjust these processes and determine the pattern characteristics. This gives a flexibility to overcome the limitations of other etch techniques. Insensitivity to materials, sidewall slope control and extremely high resolution make it possible to meet den~anding production etch requirements in such different and potentially very high volume applications as bubble memory devices, magnetic tape heads and VLSI devices. A new area of development is Reactive Ion Beam Milling which can provide high etch selectivity and greater throughput.
Transmission electron microscopy observations of lowtemperature ion implanted (100) silicon. M. SERVIDOmand I. VECCm. Solid-St. Electron. 24, 329 (1981). Phosphorus implantations have been performed at room temperature and near 77°K on (100) silicon wafers. It is shown that this low-temperature process is able to produce after furnace annealing doped layers completely free from the usual residual damage (mainly dislocation loops) that is observed in room temperature implanted and furnace annealed silicon. Raman spectra of Si-implanted silicon on sapphire. Y. OHMURA,T. INOUE and T. YOSHH.Solid-St. Commun. 37, 583 (1981). Raman scattering from Si-implantation-amorphized and subsequently thermally recrystallized silicon on sapphire (SOS) shows that optical phonon frequencies of silicon well correlate with the recrystallization temperature rather than the epitaxial temperature. This implies that the strain in asepitaxial SOS has been relieved and replaced by the one which depends upon the recrystallization temperature. Electron beam lithography at the Rutherford Laboratory. R. A. LAWES. Circuit World 7 (3) 60 (1981). The Science Research Council has opened a mask-making facility at the Rutherford Laboratory based on the EBMF-2 Electron Beam Microfabricator. Ancillary equipment designed to support the EBM resolves features down to 1 micron or below. The paper discusses the principles, design parameters and the performance of the EBM and outlines mask manufacturing procedure. Base component of gain and delay time in base-implanted bipolar transistors. M. I. ELMASRYand D. J. ROULSTON.SolidSt. Electron. 24, 371 (1981). This paper uses a numerical analysis, backed by analytic solutions for some cases, to study the dependence of the base component of current gain and delay time in base implanted bipolar transistors on the base impurity profile. Results are presented in normalised form to facilitate their use in predicting device performance during the processing-device design stage. Change of the electron effective mass in extremely heavily doped n-type Si obtained by ion implantation and laser annealing. M. MIYAO, T. MOTOOKA, N. NATSUAKI and T. TOKUYAMA. Solid-St. Commun. 37, 605 (1981). Infrared optical properties of extremely heavily doped n-type Si, obtained by ion implantation and laser annealing, were studied. A new relation between free carrier effective mass (m*) and carrier concentration (1019 5 × 102'cm -3) was obtained. The value of m* increases significantly with the increase of carrier concentration, when carrier concentration exceeds 1021cm -3. The result is discussed in relation to the occupation of electrons in a new valley of the conduction band. Trimming behaviour and post-trim characteristics of Ta2 N resistors on silicon. AMI KESTENBAUMand THOMAS F. BAER. IEEE Trans. Components, Hybrids, Manuf. Technol. CHMT-3 (4) 637 (December 1980). Laser trimming of thin films on silicon differs in several important respects from trimming on passive substrates such as ceramic. These differences necessitate the characterization of the process and its effect on circuit performance. The trimming behavior of Ta2N thin-film resistors on silicon is studied in detail. Incremental changes in resistance are investigated for several important geometrical configurations. These results are of special value in trimming under measure and predict conditions. It is also shown that the laser trimming of these resistors results in post-trim drift. However, it is shown that proper design guidelines can minimize the effect so that high-precision monolithic circuits can be successfully produced. Dose accuracy and doping uniformity of ion implantation equipment. D. S. PERLOFF,J. N. GAN and F. E. WAHL. Solid-