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The electrical properties of zinc implanted GaAs
World Abstracts on Microelectronics and Reliability The epitaxial layers deposited on substrates maintained at approximately 550°C during implantation have a crystalline quality comparable to those of layers on untreated substrates. Fabricated p - n junction diodes have low leakage currents and high breakdown voltages. The minority carrier lifetime is comparable to that in diodes processed similarly but without an implanted oxide layer.
Electrical characterization of ion-implanted silicon-onsapphire. ALICE L. LIN, ROY MADDOX and JACK E. MEE. Microelectron. J. 14 (6), 22 (1983). Electrical parameters of carrier transport in SOS films were investigated by measuring gate capacitance at frequencies ranging from 1 kHz to 10 MHz, conductance both in the linear region and in the saturation region and Hall effect as a function of gate bias voltage. The results show that the mobility decreases almost linearly with increasing distance from the Si/SiO 2 interface. Similar characteristics were obtained for the carrier concentration profile. The magnitudes drop more than 200 per cent from the Si/SiO 2 interface to about 0.2 Ixm deep in the Si film. This experimental result is very different from the data predicted by SUPREM. Spreading resistance profiles measured on the same n-type SOS film after wafer processing show increasing resistivity with increasing distance from the Si surface. The doping profile calculated from spreading resistance data by using the mobility data obtained from the gated Hall effect measurements also indicates that the n-type carrier concentration decreases toward the Si/sapphire interface. The discrepancy between experimental data and the carrier concentration profile predicted by SUPREM can be explained by the existence of deep-level acceptor traps that are evident from Hall effect measurements made on a lightly boron-implanted SOS sample. The temperature dependence of the free carrier concentration shows an activation energy close to 0.31 eV. Mobility and carrier concentration measured by different techniques is discussed. Electron-beam recrystallized polysilicon on silicon dioxide. TOMOYASU INOUE and KENJI SHIBATA.Mieroelectron. J. 14 (6), 74 (1983). Lateral seeded recrystallization of silicon layer evaporated in an ultra high vacuum has been studied experimentally by scanning electron beam annealing. Silicon layers on the seed area were grown epitaxially during the evaporation. Silicon layers above 1 ~tm thickness were successfully recrystallized, resulting in reproducible lateral epitaxy of ~40~tm in length. A pseudo-line shaped electron beam formed by high frequency oscillation enabled dimensional enlargement of lateral epitaxial growth to 120 ~tm in length and 150ttm in width. Crystalline properties were characterized by Rutherford backscattering measurement and electron channelling pattern observation. The electrical properties of zinc implanted GaAs. S. S. KULAR, B. J. SEALY,Y. ONO and K. G. STEPHENS.Solid-St. Electron. 27 (1), 83 (1984). The electrical properties of zinc implanted GaAs have been measured as a function of ion dose, ion energy, implant temperature and annealing temperature and time using either evaporated aluminium layers or pyrolytically deposited Si3N , as the encapsulant during annealing. The electrical profiles depend on all the above variables and thus profiles can be tailored by varying the relative magnitudes of these parameters. It is important to note that hole concentrations in excess of 1 × 1019 cm-3 can be obtained following an anneal at temperatures as low as 650°C. Also, at the same annealing temperature, profile depths can be varied from 0.2 to about 1 I.tm by correct choice of implantation parameters. Aluminium coatings are acceptable for annealing temperatures up to 700°C but Si3N , is required at higher temperatures. High-speed reactive ion etching of silicon by the application of a confined DC bias. ANDREWG. NAGY.Solid St. Technol. 173 (December 1983). The etch rate of single crystal silicon in a reactive ion etching system using a radio frequency C12
825
discharge was increased up to nearly two orders of magnitude by adding a negative bias to the powered cathode relative to the grounded anode. The increased etch rates occur in two stages: (i) through the application of a negative bias to the powered lower electrode without any modifications to the system, resulting in a moderate increase in etch rates, and (2) as a result of confining the path of the dc current to the area of the wafer, causing the unmasked portions of the wafer surface to act as the cathode of a very high current density dc discharge. Unusual etch profiles, dependent upon the feature geometry and the etch gas used, were also observed.
Applications of excimer lasers in microelectronics. TIM MCGRATH.Solid St. Technol. 165 (December 1983). Emerging applications for excimer lasers in the microelectronics industry are reviewed. The performance features of excimer lasers, with emphasis on those relating to device fabrication, are discussed. Topics covered in detail include photolithography, laser-induced etching, and simultaneous doping and deposition. Principles of laser scanning for defect and contamination detection in microfabrication. PETER GISE. Solid St. Technol. 163 (November 1983). A technique utilizing a sharply focused scanning laser beam and an integrating light collector to examine the surfaces of silicon wafers and photoplates for defects, particulate contamination and haze is discussed. Scattering theory is used to characterize the various types of scattering from surface irregularities. Poisson statistics are used to calculate the statistical uncertainty in counting particles which have random scattering of size and density. Semiconductor processing with excimer lasers. R. T. YOUNG, J. NARAYAN,W. H. CHRISTIE, G. A. VAN DER LEEDEN, J. I. LEVATTERand L. J. CHENG.Solid St. Technol. 183 (November 1983). The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeC1 and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at UV and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCI laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCI laser annealed region are 2-3 orders of magnitude lower than those obtained from ruby or Nd : YAG lasers. All these results seem to suggest that XeC1 lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications. Laser induced backside damage gettering. G. E. J. EGGERMONT, R. J. FALSTER and S. K. HAHN. Solid St. Technol. 171 (November 1983). The introduction of extrinsic getter sites at the backside of silicon wafers by means of high power laser pulses is discussed. Mechanical aspects of the process, such as surface roughness, wafer strength, warpage and flatness are shown to be compatible with IC processing. The laser induced damage is characterized with various techniques and its nature and stability are discussed. The gettering efficiency of the damage is shown to be very promising both in bipolar and MOS technology. A new ion dose uniformity measurement technique. JACK C. CHENGand GARYR. TRIPe. Solid St. Technol. 143 (November 1983). A new optical technique capable of measuring ion dose and dose uniformity of an ion implanter is presented. This method uses an organic photoresist coated on a glass substrate as an ion dosimeter monitor. The wafer darkens as a result of ion induced graphitization of the organic photoresist and these changes in the optical densities are then measured by a microdensitometer. The physics and applications of this technique are presented.
Electrical characterization of ion-implanted silicon-onsapphire. ALICE L. LIN, ROY MADDOX and JACK E. MEE. Microelectron. J. 14 (6), 22 (1983). Electrical parameters of carrier transport in SOS films were investigated by measuring gate capacitance at frequencies ranging from 1 kHz to 10 MHz, conductance both in the linear region and in the saturation region and Hall effect as a function of gate bias voltage. The results show that the mobility decreases almost linearly with increasing distance from the Si/SiO 2 interface. Similar characteristics were obtained for the carrier concentration profile. The magnitudes drop more than 200 per cent from the Si/SiO 2 interface to about 0.2 Ixm deep in the Si film. This experimental result is very different from the data predicted by SUPREM. Spreading resistance profiles measured on the same n-type SOS film after wafer processing show increasing resistivity with increasing distance from the Si surface. The doping profile calculated from spreading resistance data by using the mobility data obtained from the gated Hall effect measurements also indicates that the n-type carrier concentration decreases toward the Si/sapphire interface. The discrepancy between experimental data and the carrier concentration profile predicted by SUPREM can be explained by the existence of deep-level acceptor traps that are evident from Hall effect measurements made on a lightly boron-implanted SOS sample. The temperature dependence of the free carrier concentration shows an activation energy close to 0.31 eV. Mobility and carrier concentration measured by different techniques is discussed. Electron-beam recrystallized polysilicon on silicon dioxide. TOMOYASU INOUE and KENJI SHIBATA.Mieroelectron. J. 14 (6), 74 (1983). Lateral seeded recrystallization of silicon layer evaporated in an ultra high vacuum has been studied experimentally by scanning electron beam annealing. Silicon layers on the seed area were grown epitaxially during the evaporation. Silicon layers above 1 ~tm thickness were successfully recrystallized, resulting in reproducible lateral epitaxy of ~40~tm in length. A pseudo-line shaped electron beam formed by high frequency oscillation enabled dimensional enlargement of lateral epitaxial growth to 120 ~tm in length and 150ttm in width. Crystalline properties were characterized by Rutherford backscattering measurement and electron channelling pattern observation. The electrical properties of zinc implanted GaAs. S. S. KULAR, B. J. SEALY,Y. ONO and K. G. STEPHENS.Solid-St. Electron. 27 (1), 83 (1984). The electrical properties of zinc implanted GaAs have been measured as a function of ion dose, ion energy, implant temperature and annealing temperature and time using either evaporated aluminium layers or pyrolytically deposited Si3N , as the encapsulant during annealing. The electrical profiles depend on all the above variables and thus profiles can be tailored by varying the relative magnitudes of these parameters. It is important to note that hole concentrations in excess of 1 × 1019 cm-3 can be obtained following an anneal at temperatures as low as 650°C. Also, at the same annealing temperature, profile depths can be varied from 0.2 to about 1 I.tm by correct choice of implantation parameters. Aluminium coatings are acceptable for annealing temperatures up to 700°C but Si3N , is required at higher temperatures. High-speed reactive ion etching of silicon by the application of a confined DC bias. ANDREWG. NAGY.Solid St. Technol. 173 (December 1983). The etch rate of single crystal silicon in a reactive ion etching system using a radio frequency C12
825
discharge was increased up to nearly two orders of magnitude by adding a negative bias to the powered cathode relative to the grounded anode. The increased etch rates occur in two stages: (i) through the application of a negative bias to the powered lower electrode without any modifications to the system, resulting in a moderate increase in etch rates, and (2) as a result of confining the path of the dc current to the area of the wafer, causing the unmasked portions of the wafer surface to act as the cathode of a very high current density dc discharge. Unusual etch profiles, dependent upon the feature geometry and the etch gas used, were also observed.
Applications of excimer lasers in microelectronics. TIM MCGRATH.Solid St. Technol. 165 (December 1983). Emerging applications for excimer lasers in the microelectronics industry are reviewed. The performance features of excimer lasers, with emphasis on those relating to device fabrication, are discussed. Topics covered in detail include photolithography, laser-induced etching, and simultaneous doping and deposition. Principles of laser scanning for defect and contamination detection in microfabrication. PETER GISE. Solid St. Technol. 163 (November 1983). A technique utilizing a sharply focused scanning laser beam and an integrating light collector to examine the surfaces of silicon wafers and photoplates for defects, particulate contamination and haze is discussed. Scattering theory is used to characterize the various types of scattering from surface irregularities. Poisson statistics are used to calculate the statistical uncertainty in counting particles which have random scattering of size and density. Semiconductor processing with excimer lasers. R. T. YOUNG, J. NARAYAN,W. H. CHRISTIE, G. A. VAN DER LEEDEN, J. I. LEVATTERand L. J. CHENG.Solid St. Technol. 183 (November 1983). The advantages of pulsed excimer lasers for semiconductor processing are reviewed. Extensive comparisons of the quality of annealing of ion-implanted Si obtained with XeC1 and ruby lasers have been made. The results indicate that irrespective of the large differences in the optical properties of Si at UV and visible wavelengths, the efficiency of usage of the incident energy for annealing is comparable for the two lasers. However, because of the excellent optical beam quality, the XeCI laser can provide superior control of the surface melting and the resulting junction depth. Furthermore, the concentrations of electrically active point defects in the XeCI laser annealed region are 2-3 orders of magnitude lower than those obtained from ruby or Nd : YAG lasers. All these results seem to suggest that XeC1 lasers should be suitable for fabricating not only solar cells but also the more advanced device structures required for VLSI or VHSIC applications. Laser induced backside damage gettering. G. E. J. EGGERMONT, R. J. FALSTER and S. K. HAHN. Solid St. Technol. 171 (November 1983). The introduction of extrinsic getter sites at the backside of silicon wafers by means of high power laser pulses is discussed. Mechanical aspects of the process, such as surface roughness, wafer strength, warpage and flatness are shown to be compatible with IC processing. The laser induced damage is characterized with various techniques and its nature and stability are discussed. The gettering efficiency of the damage is shown to be very promising both in bipolar and MOS technology. A new ion dose uniformity measurement technique. JACK C. CHENGand GARYR. TRIPe. Solid St. Technol. 143 (November 1983). A new optical technique capable of measuring ion dose and dose uniformity of an ion implanter is presented. This method uses an organic photoresist coated on a glass substrate as an ion dosimeter monitor. The wafer darkens as a result of ion induced graphitization of the organic photoresist and these changes in the optical densities are then measured by a microdensitometer. The physics and applications of this technique are presented.