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Electrical activation and impurity redistribution during pulsed laser annealing of BF+2 implanted amorphized silicon
1198
World Abstracts on Microelectronics and Reliability
becomes evident that the initial THI can be used to predict the stability of a resistor in a nondestructive test.
Large area hybrid module. JAMES R. GASKILL, JR., ALBERT KAMENSKY, MILTON H. ROSENGARD and BRIAN J. TILLEY. IEEE Trans. Components Hybrids Mfg Technol. CHMT-4 (4), 379 (1981). A 3.25-in square 200W kovar large area hybrid (LAH) module was developed for ultrahigh-speed avionics signal processors. Module requirements and design are presented, the fabrication of four experimental prototypes is described, and current problems are summarized. Development and evaluation of a pre-encapsulation cleaning process to improve reliability of H1C's with aluminum metallized chips. MELANIE IANNUZZI. IEEE Trans. Components Hybrids Mild Technol. CHMT-4 (4), 429 (1981). With a view toward the use of aluminum metallized chips on hybrids, a pre-encapsulation cleaning process was developed and eval-
uated. The method involved the determination of the reactivity of Standard Bell System cleaning processes and reagents toward aluminum metallizations using continuity measurements. Substitutions for aggressive reagents were then sought. Evaluation of nonaggressive process sequences were carried out using ionograph measurements, quantitative carbon Auger analysis, and accelerated aging studies on purposely contaminated samples. It was determined that H202, alkali cleaners, and hot water are unacceptable for use. The use of a simple Freon degreasing step is inadequate. Introduction of a cold water rinse to effect removal of polar impurities is an improvement but not optimum. The Modified Plasma Cleaning Process (Freon, O z plasma, cold H20 ) is the most effective clean of those evaluated. The O2 plasma step is an effective component of the process. It does not increase the passivating oxide thickness. If a surface is clean, then the aluminum metallization will not corrode unless a new source of contamination is introduced.
9. E L E C T R O N , ION AND LASER BEAMS The effect of high speed laser trimming on accuracy and stability of thick film resistors. RENE E. COTE. Electrocomponent Sci. Technol. 8, 181 (1981). Many recommendations have been made on the proper operating conditions for the laser trimming process. In general these recommendations have centered on accuracy, precision or throughput. In some instances, these have appeared to be mutually exclusive. If one wanted accuracy and precision, one had to sacrifice trimming speed and, therefore, throughput. It has been reported that 40 % of the processing cost of a thick film resistor network is due to laser trimming. To continue to make these networks commercially attractive, the manufacturers of laser trimming systems have addressed themselves to the problem of providing suitable cuts at higher and higher trimming speeds. It is important for the user of such a system to understand the basics of the trimming process and to have an appreciation for the new factors which will affect the performance characteristics of laser trimmed thick film resistors. This paper summarizes the previous work as it relates to present technology. It then attempts to develop new guidelines for high speed laser trimming. Ion implantation in wafer fabrication. PIETER S. BURGGRAAF. Semicond. Int., 39 (November 1981). In production most issues concerning ion-implantation systems are not related to ion-beam physics but rather to wafer handling, throughput achieved with system reliability, doping uniformity and process compatibility. Accordingly, a selection from available ion implanters should be based on how equipment features improve wafer fabrication productivity. Annealing behaviour of aluminium implanted germanium. J. RAISANEN.Solid-St. Electron. 25 (1), 49 (1982). The annealing behaviour of aluminium implanted germanium has been investigated in the temperature range 775-525°C. The aluminium concentration profiles were determined using the (p,),) resonance broadening method. The values of 2.2 eV for the activation energy and 9.8 x 10-4cm2/s for the frequency factor for the AI diffusion in germanium are deduced. Fast outdiffusion is observed even at low temperatures. Surface enrichment and oxidation effects are discussed. Raman scattering from ion-implanted carriers in n-GaAs. R. J. NICHOLAS and H. J. STOLZ. Solid-St. Electron. 25 (1), 55 (1982). Raman scattering by the 09+ and co- coupled plasmon-phonon modes of the electrons close to the surface, in ion implanted and laser annealed GaAs, are reported. Measurement of the co+ frequency enables a contactless measurement of the electron concentration to be made in a
small region. Scattering from both screened and unscreened w - plasmons was observed, with frequencies and intensities dependent upon electron concentration. Strong band to band luminescence was also observed at energies up to Ey+EF, providing confirmation of the measured electron concentrations.
Ion-assisted plasma etching of silicon-oxides in a multifacet system. FRANK D. EGITTO, DAVID N . K . WANG, DAN MAYDAN and DAVID BENZING. Solid-St. Technol., 71 (December 1981). Ion assisted plasma etching has been demonstrated to be an important and necessary technology for the fabrication of VLSI circuits. The stringent requirements associated with the etching of silicon oxides and the etch results obtained in a multifacet reactor are discussed. Reduction of polymer formation, characteristic of selective oxide etching processes, is investigated. Several etching characteristics are studied under various operating conditions. Control of critical dimensions as well as control of etched profiles is also demonstrated. Electrical activation and impurity redistribution during pulsed laser annealing of BF~ implanted amorphized silicon. ANJAN BHATTACHARYYA, VENKATRAMANIYER, BEN G. STREETMAN, JUDITH E. BAKER and PETER WILLIAMS. IEEE Trans. Components Hybrids Mfg Technol. CHMT-4 (4), 425 (1981). Results of experiments studying the electrical activation and impurity redistribution during annealing of BF 2 ÷ implanted amorphized silicon with a Q-switched Nd:glass laser (2 = 1.06 lam) of 27.5 nm full-width half-maximum (FWHM) are presented. The experimental results are explained on the basis of a thermal melting model. The laser fluence necessary to initiate melting of the front surface was determined using time-resolved reflectivity measurements. The samples irradiated with laser fluences just below the melting threshold and with higher ftuences producing melting to successively deeper regions inside the material were specifically investigated. It was found that for full electrical activation, the laser fluence should be large enough to melt past the original amorphous-crystalline interface and the underlying damaged layer, leading to liquid phase epitaxial regrowth and ~ 100 percent electrical activation. Recent trends in ion implantation. WESLEY H. WE1SENBERGER. Solid St. Technol., 118 (November 1981). There have been many advances in ion implantation since it was conceived as a doping technique for semiconductors. This paper describes general trends in implant technology and deals with some of the most often asked questions regarding control of implant uniformity.
World Abstracts on Microelectronics and Reliability
becomes evident that the initial THI can be used to predict the stability of a resistor in a nondestructive test.
Large area hybrid module. JAMES R. GASKILL, JR., ALBERT KAMENSKY, MILTON H. ROSENGARD and BRIAN J. TILLEY. IEEE Trans. Components Hybrids Mfg Technol. CHMT-4 (4), 379 (1981). A 3.25-in square 200W kovar large area hybrid (LAH) module was developed for ultrahigh-speed avionics signal processors. Module requirements and design are presented, the fabrication of four experimental prototypes is described, and current problems are summarized. Development and evaluation of a pre-encapsulation cleaning process to improve reliability of H1C's with aluminum metallized chips. MELANIE IANNUZZI. IEEE Trans. Components Hybrids Mild Technol. CHMT-4 (4), 429 (1981). With a view toward the use of aluminum metallized chips on hybrids, a pre-encapsulation cleaning process was developed and eval-
uated. The method involved the determination of the reactivity of Standard Bell System cleaning processes and reagents toward aluminum metallizations using continuity measurements. Substitutions for aggressive reagents were then sought. Evaluation of nonaggressive process sequences were carried out using ionograph measurements, quantitative carbon Auger analysis, and accelerated aging studies on purposely contaminated samples. It was determined that H202, alkali cleaners, and hot water are unacceptable for use. The use of a simple Freon degreasing step is inadequate. Introduction of a cold water rinse to effect removal of polar impurities is an improvement but not optimum. The Modified Plasma Cleaning Process (Freon, O z plasma, cold H20 ) is the most effective clean of those evaluated. The O2 plasma step is an effective component of the process. It does not increase the passivating oxide thickness. If a surface is clean, then the aluminum metallization will not corrode unless a new source of contamination is introduced.
9. E L E C T R O N , ION AND LASER BEAMS The effect of high speed laser trimming on accuracy and stability of thick film resistors. RENE E. COTE. Electrocomponent Sci. Technol. 8, 181 (1981). Many recommendations have been made on the proper operating conditions for the laser trimming process. In general these recommendations have centered on accuracy, precision or throughput. In some instances, these have appeared to be mutually exclusive. If one wanted accuracy and precision, one had to sacrifice trimming speed and, therefore, throughput. It has been reported that 40 % of the processing cost of a thick film resistor network is due to laser trimming. To continue to make these networks commercially attractive, the manufacturers of laser trimming systems have addressed themselves to the problem of providing suitable cuts at higher and higher trimming speeds. It is important for the user of such a system to understand the basics of the trimming process and to have an appreciation for the new factors which will affect the performance characteristics of laser trimmed thick film resistors. This paper summarizes the previous work as it relates to present technology. It then attempts to develop new guidelines for high speed laser trimming. Ion implantation in wafer fabrication. PIETER S. BURGGRAAF. Semicond. Int., 39 (November 1981). In production most issues concerning ion-implantation systems are not related to ion-beam physics but rather to wafer handling, throughput achieved with system reliability, doping uniformity and process compatibility. Accordingly, a selection from available ion implanters should be based on how equipment features improve wafer fabrication productivity. Annealing behaviour of aluminium implanted germanium. J. RAISANEN.Solid-St. Electron. 25 (1), 49 (1982). The annealing behaviour of aluminium implanted germanium has been investigated in the temperature range 775-525°C. The aluminium concentration profiles were determined using the (p,),) resonance broadening method. The values of 2.2 eV for the activation energy and 9.8 x 10-4cm2/s for the frequency factor for the AI diffusion in germanium are deduced. Fast outdiffusion is observed even at low temperatures. Surface enrichment and oxidation effects are discussed. Raman scattering from ion-implanted carriers in n-GaAs. R. J. NICHOLAS and H. J. STOLZ. Solid-St. Electron. 25 (1), 55 (1982). Raman scattering by the 09+ and co- coupled plasmon-phonon modes of the electrons close to the surface, in ion implanted and laser annealed GaAs, are reported. Measurement of the co+ frequency enables a contactless measurement of the electron concentration to be made in a
small region. Scattering from both screened and unscreened w - plasmons was observed, with frequencies and intensities dependent upon electron concentration. Strong band to band luminescence was also observed at energies up to Ey+EF, providing confirmation of the measured electron concentrations.
Ion-assisted plasma etching of silicon-oxides in a multifacet system. FRANK D. EGITTO, DAVID N . K . WANG, DAN MAYDAN and DAVID BENZING. Solid-St. Technol., 71 (December 1981). Ion assisted plasma etching has been demonstrated to be an important and necessary technology for the fabrication of VLSI circuits. The stringent requirements associated with the etching of silicon oxides and the etch results obtained in a multifacet reactor are discussed. Reduction of polymer formation, characteristic of selective oxide etching processes, is investigated. Several etching characteristics are studied under various operating conditions. Control of critical dimensions as well as control of etched profiles is also demonstrated. Electrical activation and impurity redistribution during pulsed laser annealing of BF~ implanted amorphized silicon. ANJAN BHATTACHARYYA, VENKATRAMANIYER, BEN G. STREETMAN, JUDITH E. BAKER and PETER WILLIAMS. IEEE Trans. Components Hybrids Mfg Technol. CHMT-4 (4), 425 (1981). Results of experiments studying the electrical activation and impurity redistribution during annealing of BF 2 ÷ implanted amorphized silicon with a Q-switched Nd:glass laser (2 = 1.06 lam) of 27.5 nm full-width half-maximum (FWHM) are presented. The experimental results are explained on the basis of a thermal melting model. The laser fluence necessary to initiate melting of the front surface was determined using time-resolved reflectivity measurements. The samples irradiated with laser fluences just below the melting threshold and with higher ftuences producing melting to successively deeper regions inside the material were specifically investigated. It was found that for full electrical activation, the laser fluence should be large enough to melt past the original amorphous-crystalline interface and the underlying damaged layer, leading to liquid phase epitaxial regrowth and ~ 100 percent electrical activation. Recent trends in ion implantation. WESLEY H. WE1SENBERGER. Solid St. Technol., 118 (November 1981). There have been many advances in ion implantation since it was conceived as a doping technique for semiconductors. This paper describes general trends in implant technology and deals with some of the most often asked questions regarding control of implant uniformity.