- Email: [email protected]
4040. Argon plasma bridge neutralizer operation with a 10 cm beam diameter ion etching source. (USA)
Classified abstracts 4035-4043 The resolution achieved is better than 1.5 nm for irradiation temperatures above 90 K, using conventional holders. In the temperature range 20-100 K irradiation experiments are performed using a liquid helium cooled holder built in the laboratory. The resolution is then about 3 rim. (France) M O Ruault et al, JPhys E: Sci Instrum, 11 (11), 1978, 1125-1128. 34 4035. Resolution of M O S one-transistor, dynamic RAM bit failures using S E M stroboscopic techniques. (USA) Stroboscopic techniques are used to allow the scanning electron microscope (SEM) to function as an electronic probe with a spatial resolution of 0.2 ~,m~ and a time resolution of 0.3 ns. The causes of 'row' and 'single-bit' failures in the one-transistor, dynamic randomaccess-memory (RAM) are resolved using the SEM electronic probe technique. A J Gonzales and M W Powell, J Vac Sci Technol, 15 (3), 1978, 1043-1046. 34 4036. Modeling charge storage in electron-beam-accessed M O S memories. (USA) MOS capacitors have been subjected to 10 kV electron irradiation at different gate biases, resulting in charge storage in the oxide. C-V translations vs bias are given for various accumulated electron doses extending from 10 -4 to 0.1 C/cm 2. To explain the essential features of the data, a single-layer model for the charge distribution is proposed. The model comprises several stages which depend upon the irradiation bias. For the first stage, a characteristic charge layer thickness is independent of bias; this thickness varies from less than 300 A early in the radiation history to over 800 A for an accummulated dose of 0.1 C/cm z. A critical interracial electric field and a trap density are incorporated in the model to directly account for other features of the data. H K Rockstad, J Vac Sci Technol, 15 (3), 1978, 1039-1042. 34 4037. Matrix lens electron-beam recording systems. (USA) State-of-the-art achievements of matrix lens recording systems are presented in this paper. Also the primary beam limiting aberrations and physical constraints of matrix lens electron-beam recording systems are discussed. A new concept in matrix lens optics, known as the short focus plus relay with improved performance over conventional matrix lens systems is presented. Analytical projections of the beam current and spot size for this configuration are shown indicating significant performance improvements in matrix lens capabilities. Preliminary experimental data for the short focus plus relay matrix optics is presented. H G Parks, J Vac Sci Technol, 15 (3), 1978, 1035-1038. 34 4038. Diode-array-targeted CRT scan converter: some operational limitations and failure mechanisms. /(USA) Some operational limitations of a high-speed, dual-gun, diode-arraytargeted CRT scan converter when used as a transient signal acquisition unit and A/D converter are discussed with respect to trace blooming and target burning at slow trace velocities and/or excessive writing gun beam current. The blooming characteristics of three target types are described. It is shown that a five times reduction in trace blooming can be obtained, but only with a resultant loss of a factor of four in writing sensitivity. Residual trace retention phenomena (burning) are analysed. X-ray generation in the silicon by the 10 kV writing beam is shown to cause the damage and experimental data is offered to verify this effect and determine the X-ray dose. G Hnshizume et al, J Vac Sci Technol, 15 (3), 1978, 1032-1034.
35. PROCESSING O F MATERIALS 35 4039. Microfabrication in LiNbO3 by ion-bombardment-enhanced etching. (USA) Ion-bombardment-enhanced etching is suggested as an useful microfabrication technique for LiNbO3. Diluted H F was found to be a good selective etchant for a layer damaged by Ar + and N +. This method is compared with another microfabrication method, ion beam etching. The accuracy of the pattern width by this method is better than that ion beam etching and the slope of the grooved wall is very steep. The etched depths of the layer damaged by 60 keV Ar + at
the dose of 3 × 10tS/cm 2 and N + at the dose of 2 x I016/cm 2 are 70 and 145 nm, respectively.The depth is controllable by changing the ion energy and dose. (Japan) M Kawabe et al, J Vac Sci Technol, 15 (3), 1978, 1096-1098. 35 4040. Argon plasma bridge neutralizer operation with a 10 cm beam diameter ion etching source. (USA) The plasma bridge neutralizer operating on argon offers a long life, contamination free method of neutralizing the ion beams of industrial etching and deposition sources. The neutralizer described herein is capable of neutralizing the 200 mA beam produced by the l0 cm diameter ion source used for these tests. Beam plasma potential and electron temperature are essentially the same as those from an immersed thermionic emitter neutralizer. Lifetimes 3 to 5 times as great as immersed wires were obtained with the plasma bridge neutralizer in similar reactive ehvironments. P D Reader et al, J Vac Sci Technol, 15 (3), 1978, 1093-1095. 35 4041. Implantation temperature for III-V compound semiconductors. (USA) Ion implantation in various III-V compound semiconductors (BP, InSb, G a P and GaAs) has been investigatedto revcal the effect of implantation temperature on the general implantation bchaviours of III-V compounds. Lattice location of implanted ions and defects were measured by means of Hc ion-channelling techniques as a function of implantation temperature. For all of the crystalsstudied, it was found that no amorphous layer was formed above the critical temperature (To),and that 7"=is linearlycorrelatcdto a melting point of a crystal.High substitutionalfraction of implantcd ions and low defect density wcrc obtained by an implantation above 7"=.Oapan) K G a m e et al,J Vac Sci Technol, 15 (3), 1978, 1086-1088. 35 4042. PR-200 ion implantation system. (USA) PR-200 is a 200 kV, general-purpose,high-throughout ion implantation system which was installedon Western Electric'sproduction line at Reading, P A in mid 1975. The "frontend' is a commercial Lintott mass separator to which has been added a high-currentversion of the Lintott-Harwell hot-cathode ion source. The front end produces 21B currents of 1 mA and 3zp, ~SAs' and ~2~Sb currents of 3 mA. The 'rear end' is an acceleration and rotating scan target stage based upon the PR-500 technology which was developed at this laboratory. Careful matching of the front end slit-beam ion optics to the rear end circular-beam optics produces high currents on target, up to 1 mA of l~B and 2.5 mA or a~P, 7SAs and 121Sb. These currents, combined with fast turnaround time (5-7 rain) and rotating mechanical scan, permit more than 100 3 in. wafcrs/h to be implanted with wafer nonuniformities (l a=) less than 0.5 % and a total product non-uniformity (1 at) less than 2.0~o. The target stage floats at high voltage and is pumped through insulating columns by a vacuum system at ground potential. Additional pumping speed is obtained by a titanium sublimation pump inside the target stage. The pumpdown sequence is automated and the implant sequence is under minicomputer control, permitting operation of the system by unskilled personnel. Communication between the high voltage target stage and ground potential is accomplished with a four light beam telemetry system. Two light beams are dedicated to the rotating-scan implant and dose control, and two other light beams communicate a variety of analogue, digital, and status information. H M B Bird et al, J Vac Sci Technol, 15 (3), 1978, 1080--1085. 35 4043. High-current ion source for use on the PR-30 implanter. (USA) An ion source of the Freeman type has been extensively reworked and tailored for the routine production of dopant species on the PR-30 ion implantation machine. The modified source is presently used on several such machines within the Bell System, routinely producing intense beams of B +, P÷, As + and Sb + . Typical PR-30 target currents for the above species are 1, 5, 6 and 5 mA, respectively, with peak currents about 20% higher than these figures. With the possible exception of B +, these beam current intensities are the highest presently available for implantation applications. Further studies on improved B + production are being pursued. BF3 gas is used as a feed for B + production and solid charges arc used for P+, As + and Sb + , usually without a carrier gas, so as to maintain maximum beam
255
35. PROCESSING O F MATERIALS 35 4039. Microfabrication in LiNbO3 by ion-bombardment-enhanced etching. (USA) Ion-bombardment-enhanced etching is suggested as an useful microfabrication technique for LiNbO3. Diluted H F was found to be a good selective etchant for a layer damaged by Ar + and N +. This method is compared with another microfabrication method, ion beam etching. The accuracy of the pattern width by this method is better than that ion beam etching and the slope of the grooved wall is very steep. The etched depths of the layer damaged by 60 keV Ar + at
the dose of 3 × 10tS/cm 2 and N + at the dose of 2 x I016/cm 2 are 70 and 145 nm, respectively.The depth is controllable by changing the ion energy and dose. (Japan) M Kawabe et al, J Vac Sci Technol, 15 (3), 1978, 1096-1098. 35 4040. Argon plasma bridge neutralizer operation with a 10 cm beam diameter ion etching source. (USA) The plasma bridge neutralizer operating on argon offers a long life, contamination free method of neutralizing the ion beams of industrial etching and deposition sources. The neutralizer described herein is capable of neutralizing the 200 mA beam produced by the l0 cm diameter ion source used for these tests. Beam plasma potential and electron temperature are essentially the same as those from an immersed thermionic emitter neutralizer. Lifetimes 3 to 5 times as great as immersed wires were obtained with the plasma bridge neutralizer in similar reactive ehvironments. P D Reader et al, J Vac Sci Technol, 15 (3), 1978, 1093-1095. 35 4041. Implantation temperature for III-V compound semiconductors. (USA) Ion implantation in various III-V compound semiconductors (BP, InSb, G a P and GaAs) has been investigatedto revcal the effect of implantation temperature on the general implantation bchaviours of III-V compounds. Lattice location of implanted ions and defects were measured by means of Hc ion-channelling techniques as a function of implantation temperature. For all of the crystalsstudied, it was found that no amorphous layer was formed above the critical temperature (To),and that 7"=is linearlycorrelatcdto a melting point of a crystal.High substitutionalfraction of implantcd ions and low defect density wcrc obtained by an implantation above 7"=.Oapan) K G a m e et al,J Vac Sci Technol, 15 (3), 1978, 1086-1088. 35 4042. PR-200 ion implantation system. (USA) PR-200 is a 200 kV, general-purpose,high-throughout ion implantation system which was installedon Western Electric'sproduction line at Reading, P A in mid 1975. The "frontend' is a commercial Lintott mass separator to which has been added a high-currentversion of the Lintott-Harwell hot-cathode ion source. The front end produces 21B currents of 1 mA and 3zp, ~SAs' and ~2~Sb currents of 3 mA. The 'rear end' is an acceleration and rotating scan target stage based upon the PR-500 technology which was developed at this laboratory. Careful matching of the front end slit-beam ion optics to the rear end circular-beam optics produces high currents on target, up to 1 mA of l~B and 2.5 mA or a~P, 7SAs and 121Sb. These currents, combined with fast turnaround time (5-7 rain) and rotating mechanical scan, permit more than 100 3 in. wafcrs/h to be implanted with wafer nonuniformities (l a=) less than 0.5 % and a total product non-uniformity (1 at) less than 2.0~o. The target stage floats at high voltage and is pumped through insulating columns by a vacuum system at ground potential. Additional pumping speed is obtained by a titanium sublimation pump inside the target stage. The pumpdown sequence is automated and the implant sequence is under minicomputer control, permitting operation of the system by unskilled personnel. Communication between the high voltage target stage and ground potential is accomplished with a four light beam telemetry system. Two light beams are dedicated to the rotating-scan implant and dose control, and two other light beams communicate a variety of analogue, digital, and status information. H M B Bird et al, J Vac Sci Technol, 15 (3), 1978, 1080--1085. 35 4043. High-current ion source for use on the PR-30 implanter. (USA) An ion source of the Freeman type has been extensively reworked and tailored for the routine production of dopant species on the PR-30 ion implantation machine. The modified source is presently used on several such machines within the Bell System, routinely producing intense beams of B +, P÷, As + and Sb + . Typical PR-30 target currents for the above species are 1, 5, 6 and 5 mA, respectively, with peak currents about 20% higher than these figures. With the possible exception of B +, these beam current intensities are the highest presently available for implantation applications. Further studies on improved B + production are being pursued. BF3 gas is used as a feed for B + production and solid charges arc used for P+, As + and Sb + , usually without a carrier gas, so as to maintain maximum beam
255