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Vacuum deposition of films by sputtering using an ion-beam source
Abstracts
of the papers presented
at the Thirteenth
National
the gauges to be calibrated was not uniform although a calibration dome very similar to an AVS standard pump speed dome was used. Second, it was found that small temperature fluctuation of less than 1°C during a calibration run could cause large errors when measuring gas flow rates of 5 x 1O-6 torr litres/sec by the variable volume technique. Variations in the calibration dome were taken into account by experimentally determining the pumping speed at the port of each gauge to be calibrated. Errors in the gas flow measurements were corrected by precise balancing of the reference and leak volumes. When proper attention is paid to the above parameters, gauges can be calibrated over the range of 4 x 1O-4 torr with a consistency of &2%. Peter J Clake, Veeco Instruments Inc, Terminal Drive, Plainview, New York 11803.
Sputtering Rf sputter etching-a
universal etch
Rf sputtering and standard photoresist techniques have been used to etch patterns and holes in metals, semiconductors and insulators. The samples were placed on an electrode that was capacitively coupled to the rf power supply. The technique was found to be especially useful for etching high-precision thin-film resistors, where dimensional control is very critical. P D Davidse, IBM Components Division, East Fishkill Facility, Hopewell Junction, NY 12533. Recrystallization
and phase transformations
in oxide thin films
The conditions under which the amorphous and various polymorphic crystalline structures of Ta,O,, Nb*O&, TiO, and ZrO,, deposited by low pressure reactive sputtering, have been investigated. Structure transformations observed in furnace annealed films and in samples temperature-cycled in the hot stage of the electron microscope are described. Data on the nucleation and growth of the beta phases of Ta,O, and Nb,O, and the rutile phase of TiO, from the amorphous forms of these oxides is presented, and the crystal habits preferred in the films compared with those occurring in melt-growth crystals. Preliminary results on growth at elevated temperature on epitaxial platinum film surfaces are also considered. M H Francombe, A J Noreika and S A Z&man, Westinghouse Research Laboratories, Pittsburgh, Pennsylvania 15235. Impedance matching network for rf sputtering systems Although radio-frequency sputtering has proven a successful technique for deposition of various dielectrics, problems arise in coupling the rf power source to the contents of the bell jar because changes in the contents of the bell jar result in drastic impedance changes of the load seen by the rf power source. This paper describes a systematic approach to a solution of this problem. By means of measurement of the standing wave on a cable connected between bell jar and rf source, the rf impedance of the contents of the bell jar is determined. Simple reactive matching networks are calculated and designed to permit efficient coupling between source and bell jar. D J Healey, III and M Lauriente, Westinghouse Electric Corporation, Defense and Space Center, Aerospace Division, Baltimore, Maryland. Self-sticking
coe@cients of SiOa iihns deposited through rf sputtering
Investigators have reported that the deposition rate through rf sputtering of relatively refractory materials such as Ge, SiOz, GaAs, etc, varies appreciably with substrate temperature. To better understand this phenomenon, self-sticking coefficients for SiO, films (deposited through rf sputtering) were measured in the temperature range 0-4OOC. Unexpectedly low values (in the order of 0.5) were obtained; however, little or no dependence on temperature was seen in the range investigated. The experimental method is described and the influence of sputtering pressure and other parameters on the measurements is discussed. R E Jones, C L Standley and L I Maissei, IBM Components Division, East Fishkill Facility, Hopeweii Junction, NY 12433.
Vacuum Symposium chamber at a pressure of -lO-6-1O-8 torr. The beam has been used to sputter conducting, semiconducting and insulating materials. The vacuum sputtered metal films adhere very strongly to the substrates. Vacuum sputtered films of gold and silver have been found to grow epitaxially on rock salt and mica at liquid nitrogen temperature (77°K). The electrical resistivities of metal films are comparable to those observed in the best films obtained by any other deposition technique. K L Chopra and M R Randlett, Ledgemont Laboratory, Kennecott Copper Corp, 128 Spring Street, Lexington, Mass. The effect of residual gases on sputtering rates Mass spectrometer data is presented which indicates that residual water vapour can play a chief role in determining the deposition rate in a given run. It is shown that dissociation of water vapor by the glow discharge gives rise to copious quantities of hydrogen which can become a significant fraction of the sputtering atmosphere. A simple model is suggested to explain the effect of hydrogen, and this is compared with data obtained for a number of metals sputtered in a glow discharge apparatus. E Stem, IBM Watson Research Center, Yorktown Heights, New York. Sputtered germanium
films on sapphire and germanium
A high current vacuum torr range
A modification of the Von Ardenne type of a duoplasmatron ion source has been developed. The well-defined ion beam delivering current -0.5 A over an area -1 cm2 is extracted into a vacuum
discharge
for t&de-sputtering
in the lo-’
A new discharge arrangement has been developed, which allows especially high sputtering rates in a triode discharge arrangement. The principle of this arrangement which allows the production of argon ion currents up to 2 A is as follows: A magnetically confined arc burns between an ionization chamber on the top of the bell jar and an anode near the base plate. The material to be sputtered is placed in the middle of the annular anode and has an accelerating voltage of approximately - 1500 V applied. Reactive sputtering is also possible. Generally, the layers show very good adhesion. At a distance of 38 cm from the target a coating rate of 100-300 A/min is reached on a substrate surface of about 1000 cm*. Francois Gaydou, Balzers Aktiengesellschaft fur Hochvakuumtechnik und Diinne Schichten, Balzers, Liechtenstein.
Pressure
measurements
The measurement
of very low pressure
Significant advances made recently in the measurement of very low pressure (10-O to lo-l6 torr) are reviewed. The performance and limitation of several new types of hot cathode-gauge are compared; these include the suppressor, extractor and orbitron gauges. It is shown that the limitation on pressure measurement in hot-cathode gauges established by electron desorption effects is normally more difficult to overcome than the x-ray limit. The performance of coldcathode gauges at pressures below lo-lo torr is compared and their usefulness in this pressure range discussed. Recent improvements in our understanding of the physical processes which (a) limit the lowest measurable pressures and (b) influence the accuracy of such measurements are discussed. P A Redhead, Radio and Electrical Engineering Division, National Research Council, Ottawa 2, Ontario, Canada. Increase of spectrometer
Vacuum deposition of films by sputtering using an ion-beam source
substrates
The structural and electrical characteristics of germanium films deposited in a low pressure discharge onto single crystal sapphire and self-substrates have been investigated. Deposition rates of 5-10 Ajmin, and 100-135 A/min were employed to obtain films ranging in thicknesses from 2500 to 52,000 A. All films on sapphire were polycrystalline over the substrate temperature range of 300 to 650°C. Epitaxy was obtained on self-substrates in the 200-250°C region at the lowest deposition rates while at the higher rates the films were polycrystalline at these temperatures. Electrical measurements of films on sapphire indicate that the films have a layered structure. G Wallis and S P Wolsky, P R Mallory & Co Inc, Laboratory for Physical Science, Northwest Industrial Park, Burlington, Mass.
resolving power by digital processing
The method is applicable to any type of spectrometer (mass, wavelength, diffusion time, etc) for which the line shape is known. Application of the method to the termal desorption spectrometer is described. The resolving power of this instrument is very low (about 165
of the papers presented
at the Thirteenth
National
the gauges to be calibrated was not uniform although a calibration dome very similar to an AVS standard pump speed dome was used. Second, it was found that small temperature fluctuation of less than 1°C during a calibration run could cause large errors when measuring gas flow rates of 5 x 1O-6 torr litres/sec by the variable volume technique. Variations in the calibration dome were taken into account by experimentally determining the pumping speed at the port of each gauge to be calibrated. Errors in the gas flow measurements were corrected by precise balancing of the reference and leak volumes. When proper attention is paid to the above parameters, gauges can be calibrated over the range of 4 x 1O-4 torr with a consistency of &2%. Peter J Clake, Veeco Instruments Inc, Terminal Drive, Plainview, New York 11803.
Sputtering Rf sputter etching-a
universal etch
Rf sputtering and standard photoresist techniques have been used to etch patterns and holes in metals, semiconductors and insulators. The samples were placed on an electrode that was capacitively coupled to the rf power supply. The technique was found to be especially useful for etching high-precision thin-film resistors, where dimensional control is very critical. P D Davidse, IBM Components Division, East Fishkill Facility, Hopewell Junction, NY 12533. Recrystallization
and phase transformations
in oxide thin films
The conditions under which the amorphous and various polymorphic crystalline structures of Ta,O,, Nb*O&, TiO, and ZrO,, deposited by low pressure reactive sputtering, have been investigated. Structure transformations observed in furnace annealed films and in samples temperature-cycled in the hot stage of the electron microscope are described. Data on the nucleation and growth of the beta phases of Ta,O, and Nb,O, and the rutile phase of TiO, from the amorphous forms of these oxides is presented, and the crystal habits preferred in the films compared with those occurring in melt-growth crystals. Preliminary results on growth at elevated temperature on epitaxial platinum film surfaces are also considered. M H Francombe, A J Noreika and S A Z&man, Westinghouse Research Laboratories, Pittsburgh, Pennsylvania 15235. Impedance matching network for rf sputtering systems Although radio-frequency sputtering has proven a successful technique for deposition of various dielectrics, problems arise in coupling the rf power source to the contents of the bell jar because changes in the contents of the bell jar result in drastic impedance changes of the load seen by the rf power source. This paper describes a systematic approach to a solution of this problem. By means of measurement of the standing wave on a cable connected between bell jar and rf source, the rf impedance of the contents of the bell jar is determined. Simple reactive matching networks are calculated and designed to permit efficient coupling between source and bell jar. D J Healey, III and M Lauriente, Westinghouse Electric Corporation, Defense and Space Center, Aerospace Division, Baltimore, Maryland. Self-sticking
coe@cients of SiOa iihns deposited through rf sputtering
Investigators have reported that the deposition rate through rf sputtering of relatively refractory materials such as Ge, SiOz, GaAs, etc, varies appreciably with substrate temperature. To better understand this phenomenon, self-sticking coefficients for SiO, films (deposited through rf sputtering) were measured in the temperature range 0-4OOC. Unexpectedly low values (in the order of 0.5) were obtained; however, little or no dependence on temperature was seen in the range investigated. The experimental method is described and the influence of sputtering pressure and other parameters on the measurements is discussed. R E Jones, C L Standley and L I Maissei, IBM Components Division, East Fishkill Facility, Hopeweii Junction, NY 12433.
Vacuum Symposium chamber at a pressure of -lO-6-1O-8 torr. The beam has been used to sputter conducting, semiconducting and insulating materials. The vacuum sputtered metal films adhere very strongly to the substrates. Vacuum sputtered films of gold and silver have been found to grow epitaxially on rock salt and mica at liquid nitrogen temperature (77°K). The electrical resistivities of metal films are comparable to those observed in the best films obtained by any other deposition technique. K L Chopra and M R Randlett, Ledgemont Laboratory, Kennecott Copper Corp, 128 Spring Street, Lexington, Mass. The effect of residual gases on sputtering rates Mass spectrometer data is presented which indicates that residual water vapour can play a chief role in determining the deposition rate in a given run. It is shown that dissociation of water vapor by the glow discharge gives rise to copious quantities of hydrogen which can become a significant fraction of the sputtering atmosphere. A simple model is suggested to explain the effect of hydrogen, and this is compared with data obtained for a number of metals sputtered in a glow discharge apparatus. E Stem, IBM Watson Research Center, Yorktown Heights, New York. Sputtered germanium
films on sapphire and germanium
A high current vacuum torr range
A modification of the Von Ardenne type of a duoplasmatron ion source has been developed. The well-defined ion beam delivering current -0.5 A over an area -1 cm2 is extracted into a vacuum
discharge
for t&de-sputtering
in the lo-’
A new discharge arrangement has been developed, which allows especially high sputtering rates in a triode discharge arrangement. The principle of this arrangement which allows the production of argon ion currents up to 2 A is as follows: A magnetically confined arc burns between an ionization chamber on the top of the bell jar and an anode near the base plate. The material to be sputtered is placed in the middle of the annular anode and has an accelerating voltage of approximately - 1500 V applied. Reactive sputtering is also possible. Generally, the layers show very good adhesion. At a distance of 38 cm from the target a coating rate of 100-300 A/min is reached on a substrate surface of about 1000 cm*. Francois Gaydou, Balzers Aktiengesellschaft fur Hochvakuumtechnik und Diinne Schichten, Balzers, Liechtenstein.
Pressure
measurements
The measurement
of very low pressure
Significant advances made recently in the measurement of very low pressure (10-O to lo-l6 torr) are reviewed. The performance and limitation of several new types of hot cathode-gauge are compared; these include the suppressor, extractor and orbitron gauges. It is shown that the limitation on pressure measurement in hot-cathode gauges established by electron desorption effects is normally more difficult to overcome than the x-ray limit. The performance of coldcathode gauges at pressures below lo-lo torr is compared and their usefulness in this pressure range discussed. Recent improvements in our understanding of the physical processes which (a) limit the lowest measurable pressures and (b) influence the accuracy of such measurements are discussed. P A Redhead, Radio and Electrical Engineering Division, National Research Council, Ottawa 2, Ontario, Canada. Increase of spectrometer
Vacuum deposition of films by sputtering using an ion-beam source
substrates
The structural and electrical characteristics of germanium films deposited in a low pressure discharge onto single crystal sapphire and self-substrates have been investigated. Deposition rates of 5-10 Ajmin, and 100-135 A/min were employed to obtain films ranging in thicknesses from 2500 to 52,000 A. All films on sapphire were polycrystalline over the substrate temperature range of 300 to 650°C. Epitaxy was obtained on self-substrates in the 200-250°C region at the lowest deposition rates while at the higher rates the films were polycrystalline at these temperatures. Electrical measurements of films on sapphire indicate that the films have a layered structure. G Wallis and S P Wolsky, P R Mallory & Co Inc, Laboratory for Physical Science, Northwest Industrial Park, Burlington, Mass.
resolving power by digital processing
The method is applicable to any type of spectrometer (mass, wavelength, diffusion time, etc) for which the line shape is known. Application of the method to the termal desorption spectrometer is described. The resolving power of this instrument is very low (about 165