摘要:

The merits of two electron-beam systems are discussed, one for mask generation and the other for wafer alignment and exposure. The performance characteristics of both systems are described, including problems involved withICfabrication. Results of resolution, distortion, and alignment studies are given on both systems. The single-beam mask generator employs a field-emission source, and the performance advantages and disadvantages of this source for microfabrication are detailed. The field-emission source is imaged by an electrostatic lens at a 10-cm working distance. The characteristics of the focusing and deflection system are given. Parameters such as writing speed, beam current, resolution, and area of coverage are compared to conventional electron sources and performance results are reported. The performance of both cold and thermal field-emitters is also discussed. The electron projection system which utilizes a noble-metal patterned photocathode electron source is described. Electron-optical characteristics of the projection system are discussed, including results of alignment and distortion tests. The research model as well as the fully automated electron-projection system designed to process up to 100 wafers per hour are described.

ISSN:0022-5355    

DOI:10.1116/1.1318459

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Stimulated emission occurs when (ortho- and para-)H2, HD,D2, CO, Ne, andN2are excited by a 4-GW electron beam. The beam is generated by a Febetron, model 706, and propagates 2.3 m through the gases at 8–100-Torr pressures. Propagation is aided by an externally applied ∼ 10 kG magnetic field. Collisions involving primary, secondary, and cascade electrons transfer ≤ 0.1% of the energy from the electron beam to produce population inversions. The small-collision cross sections for relativistic electrons act as the primary limitation to the transfer of more energy to the gas molecules. Dependence of the laser energy on isotopes and temperature indicates that the spectral linewidth is due to Doppler broadening, and consequently higher power and optical gain are available by cooling the gases to ∼ 90 K or lower. The additional optical gain allows lasing to be observed at shorter wavelengths (1098 Å as compared to 1161 Å) and at higher powers near 1200 Å (∼ 5 kW/ cm2as compared to0.5 kW/cm2) than reported previously.

ISSN:0022-5355    

DOI:10.1116/1.1318460

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

The interactions of lasers with matter are manyfold. Among the important interactions is the generation of pressure waves by laser heating in an optically absorbing dye. The conversion of energy from transient laser heating to an acoustic wave is considered in detail in this paper. As a laser pulse enters an absorbing dye, energy is absorbed and converted into heat. Part of it will appear as elastic energy in the form of a pressure wave, due to very small expansion in the dye during the laser pulse.

ISSN:0022-5355    

DOI:10.1116/1.1318461

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Cleaning is one of the most difficult operations encountered in the restoration of statuary. The fact that known cleaning methods are not entirely satisfactory has stimulated continuing research into new methods and processes. A novel method is proposed for cleaning superficial black scabs or patinas from works of art in marble or other stone by means of laser radiation. Surface cleaning results with a ruby laser are reported and compared with conventional techniques. Preliminary analyses of the laser process are quite favorable and indicate improved selectivity and graduation, self-limiting encrustation removal, and remarkably rapid surface coverage. Finally, the results of cleaning tests with various laser types are presented and discussed, and possible future developments and pratical applications of this new method of cleaning statuary are presented.

ISSN:0022-5355    

DOI:10.1116/1.1318462

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Recent advances in the technology of high-speed manufacturing systems have introduced the need for a new approach in the design of process control systems. Computerized process control systems require automatic quality inspection stations which are capable of converting measures of product attributes into electronic information. In this study, a noncontact, electro-optic inspection system was developed which automatically measures product outer dimension at high speeds. Two approaches were taken in the system design. One approach required a photodetector as an analog measuring device, and the other utilized a photodiode matrix as a digital measuring device. The performance capability of each system was in the order of 100% detection of outer dimensions that were 0.01 in. out of specification to 97% for 0.001 in. variations. Both design approaches resulted in fast, accurate, and inexpensive inspection systems which could easily be adapted to most production environments.

ISSN:0022-5355    

DOI:10.1116/1.1318463

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Electron-beam writing instruments for microcircuit fabrication are currently limited by total cycle time, field coverage, automatic registration, and reliability. A fully computer-controlled electron-beam pattern generator will be described which has been developed to advance the economic feasibility of electron beam writing. The instrument incorporates a fully automated mechanical stage and pattern registration system, computer designed deflection coils and a dynamic focusing system for correction of deflection introduced aberrations. Field coverage at the short working distance is variable, up to0.120×0.120 in.with60 000×60 000addressable points in the field. Resolution over the field is 3500 lines at 8 mrad. Pattern distortion is within 1.0 μ over a 0.1 in. square field. The mechanical stage employs stepping motors driving lead screws to provide3×3 in.movement in 250 μ in.steps. Additional travel of 7 in. is available in one axis for loading the wafer. The automatic pattern registration system employs four silicon etched “L” shaped fiducial marks located in the corners of each field. The electron beam is used to measure the position of the fiducial marks before each field exposure and position the pattern correctly on the wafer. Pattern position, size, rotation, and orthogonality are all typically set up by the automatic registration system in 300 msec. A vernier test pattern has been used to test the alignment system and shows registration better than ± 0.2 μ.

ISSN:0022-5355    

DOI:10.1116/1.1318464

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Recent advances in electron sources and electron resists have resulted in a significant increase in potential exposure rate in electron-beam writing instruments. This in turn places stringent requirements on the pattern generating electronics which must be fast enough to avoid their limiting potential system throughout, yet flexible enough to be capable of creating all normally required geometries. A computer-controlled pattern generation system is described which is designed to meet these requirements. In this system, the speed limitation due to the calculation and data-transfer rate of modern minicomputers is avoided by the use of an auxiliary special-purpose logic processor. Patterns are built up from a basic trapezoid shape with two sides parallel to rectangular cartesian coordinate axes. The computer has only to specify the basic parameters defining a trapezoid and the auxiliary processor will then output coordinates representing the end points of lines defining the figure in a raster-scan format. These coordinates, which may be generated at rates up to 1 MHz are passed to a pair of precision ramp generators. The ramp generators, which are based on commercially available 16-bit digital-to-analog converters, then produce the analog deflection signals needed to define the line, at a sweep rate which may be varied under computer control over six orders-of-magnitude. Particular care has been taken to reduce the switching spikes, inherent in digital-to-analog converters, to negligible proportions on the output waveform.

ISSN:0022-5355    

DOI:10.1116/1.1318465

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

A mathematical model for the exposure of electron-sensitive resists on a structure coated with a thin layer of resist is presented. The calculations yield contours of equal absorbed energy density in the resist and these are interpreted as the contours which bound the resist after development. We calculate the exposure for an electron beam of vanishingly small cross-section, a beam of Gaussian current-density distribution, single lines, parallel lines, and areas.

ISSN:0022-5355    

DOI:10.1116/1.1318466

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

A noncontact procedure for sensing continuity and isolation faults in large, dense interconnection patterns by means of selective deposition of charge by an electron beam is proposed and discussed. When the accelerating potential is properly chosen, a marked variation in the secondary electron signal occurs during the charging of an electrically floating element to an equilibrium potential. This phenomenon forms the basis of the method. A laboratory system has been constructed to demonstrate the procedure. Results obtained indicate agreement with the basic theory and demonstrate the application of the technique to continuity and isolation testing of conductor films. Electron-beam testing has a clear advantage over mechanical-probe testing in terms of speed and flexibility. The less attractive features include the need for a vacuum system and the inability to detect continuity faults when the fault resistance is less than about one megohm.

ISSN:0022-5355    

DOI:10.1116/1.1318467

出版商:American Vacuum Society    

年代:1973

数据来源: AIP

摘要:

Experimental measurements are reported on the geometric and intensity variations of Coates–Kikuchi backscattered electron images from several single crystals as a function of the primary electron beam energy and angle of beam incidence to the crystal lattice. Total energy distribution measurements of the backscattered electrons were also made on a (001) GaAs wafer using a custom designed cylindrical mirror electron analyzer. The number of elastically backscattered primary electrons decreased by 80% when the beam was incident in the off-axis direction. The first plasmon loss peak was observed at −14.5 eV ± 1 eV, with a primary beam energy of 8 keV. The motivation for this work is a better characterization of the high-contrast Coates–Kikuchi patterns that we have observed using an energy sensitive solid-state detector, and better application of these patterns, which are highly detailed reciprocal lattice displays, to surface analysis. Generation of these displays in a scanning electron microscope allows practical and rapid measurement of crystal orientation, crystal type, and near-surface lattice disorder.

ISSN:0022-5355    

DOI:10.1116/1.1318468

出版商:American Vacuum Society    

年代:1973

数据来源: AIP