- Email: [email protected]
Measurement of film thickness using infrared interference
ABSTRACTS ON MICROELECTRONICS AND RELIABILITY
341
high pressure and the anode in the vacuum chamber. This modification allows the extraction, through apertures, of a well defined ion beam of current up to 500 mA over an area of approximately 1 cm 2 into a vacuum chamber at a pressure of 10-5 torr. The ion beam is accelerated and made to impinge on a target material for sputtering. Sequential sputtering of different targets inside the vacuum chamber is possible with the help of suitable magnetic fields. The ion beam has been used to sputter conducting, semiconducting and insulating materials. Typical rate of deposition of silver films at a distance of 8 cm from the target with a 50 mA, 2 kV ion beam of 8 ram. dia. is 400 A/min. Deposition rates of about 50 A/rain are obtained for SiO~ and TiO films. Vacuum sputtered films adhere to the substrates much more strongly than evaporated films.
Flash evaporation and thin films of cuprous sulphide, selenide and telluride. S. G. ELLIS,
J. Appl. Phys. 38 (1967), p. 2906. Tile technique of flash evaporation is summarized. The resistivity and absorption coefficient of cuprous sulphide, selenide and telluride deposited by this technique are studied. It is found that if during flash evaporation the ratio of partial pressures of Cu and Se at the substrate fluctuates then the film does not have the composition of the charge.
Influence of a superimposed film on the electrical conductivity of thin metal films. K. L. CHOPRA and M. R. RANDLETT,J. Appl. Phys. 38 (1967), p. 3144. Thin films of high purity materials were prepared by vacuum evaporation from tungsten filaments in a standard oil diffusion pump system maintained at about 10-6 tort. Films were deposited on to ultrasonically cleaned glass slides at ambient temperature. Au, Ag, Cu and A1 films were used for the base on to which were superimposed thin films of SiO, Gc, Cr and l~crmalloy (80/20 FcNi). The rate of deposition of tile base film was 100 A/min and that of the superimposed films 10 A/min. It was found that the overlay of SiO or Permalloy increases the resistance of Au films, but has little effect on Ag films. An overlay of Ge increases the resistance of Ag films by about 25 per cent, but has neglible effect on A1 films. The resistance of Cu films first increases with the thickness of the Ge and Cr overlay and then decreases rapidly to a saturation value. The changes in the resistance are markedly dependent on the thickness of the overlay; saturation values are obtained for an avcragc thickness of less than 10 A. Measurement of film thickness using infrared interference. D. J. DUMIN, Rev. Sci. Instrum. 38 (1967), p. 1107. A technique for measuring the thickness of silicon films grown epitaxially on sapphire is described. The method, which can be used to monitor film thicknesses while the film is growing, utilizes the infrared emission from the sapphire substrate and from the growing film. The radiation from the sapphire substrate is partially transmitted through the silicon and partially reflected in the silicon, establishing an interference pattern which is used to determine silicon film thickness. Films in the range of 0.1 to 15 microns have been measured with an accuracy of 0.1 micron. The preparation and application of tantalum thin film passive components. R. ~NTAYLORand R. FAIRBANK, Radio Electron. Engr 33 (1967), p. 229. Thin film and diffused passive components are compared. Techniques are described for fabricating resistors and capacitors by sputtered tantalum and also inductors using nichrome/gold. Reasons for choosing T a as the resistor material and sputtering as the deposition method are discussed. Disproportionation and vaporization of solid silicon monoxide. W. HERTL and W. W. PULTZ,
J. Am. Ceram. Soc. 50 (7) (1967), p. 378. The vaporization rate of solid SiO was studied in the temperature range 1005 to 1475°C. It is concluded that: (a) in an argon atmosphere the vaporization rate is controlled by external gas diffusion ; (b) only the upper layers of the charge contribute to the vaporization ; (c) the heat of vaporization of SiO is 72.5 kcal/mole. Solid SiO disproportionates when heated in the temperature range 1000 to 1440°C, but the reaction does not go to completion. The reaction in the solid state is irreversible, the product silicon inhibits the reaction. Vaporization experiments in argon and in vacuum are described and compared to each other. The temperature dependence of the vaporization rate is also studied.
341
high pressure and the anode in the vacuum chamber. This modification allows the extraction, through apertures, of a well defined ion beam of current up to 500 mA over an area of approximately 1 cm 2 into a vacuum chamber at a pressure of 10-5 torr. The ion beam is accelerated and made to impinge on a target material for sputtering. Sequential sputtering of different targets inside the vacuum chamber is possible with the help of suitable magnetic fields. The ion beam has been used to sputter conducting, semiconducting and insulating materials. Typical rate of deposition of silver films at a distance of 8 cm from the target with a 50 mA, 2 kV ion beam of 8 ram. dia. is 400 A/min. Deposition rates of about 50 A/rain are obtained for SiO~ and TiO films. Vacuum sputtered films adhere to the substrates much more strongly than evaporated films.
Flash evaporation and thin films of cuprous sulphide, selenide and telluride. S. G. ELLIS,
J. Appl. Phys. 38 (1967), p. 2906. Tile technique of flash evaporation is summarized. The resistivity and absorption coefficient of cuprous sulphide, selenide and telluride deposited by this technique are studied. It is found that if during flash evaporation the ratio of partial pressures of Cu and Se at the substrate fluctuates then the film does not have the composition of the charge.
Influence of a superimposed film on the electrical conductivity of thin metal films. K. L. CHOPRA and M. R. RANDLETT,J. Appl. Phys. 38 (1967), p. 3144. Thin films of high purity materials were prepared by vacuum evaporation from tungsten filaments in a standard oil diffusion pump system maintained at about 10-6 tort. Films were deposited on to ultrasonically cleaned glass slides at ambient temperature. Au, Ag, Cu and A1 films were used for the base on to which were superimposed thin films of SiO, Gc, Cr and l~crmalloy (80/20 FcNi). The rate of deposition of tile base film was 100 A/min and that of the superimposed films 10 A/min. It was found that the overlay of SiO or Permalloy increases the resistance of Au films, but has little effect on Ag films. An overlay of Ge increases the resistance of Ag films by about 25 per cent, but has neglible effect on A1 films. The resistance of Cu films first increases with the thickness of the Ge and Cr overlay and then decreases rapidly to a saturation value. The changes in the resistance are markedly dependent on the thickness of the overlay; saturation values are obtained for an avcragc thickness of less than 10 A. Measurement of film thickness using infrared interference. D. J. DUMIN, Rev. Sci. Instrum. 38 (1967), p. 1107. A technique for measuring the thickness of silicon films grown epitaxially on sapphire is described. The method, which can be used to monitor film thicknesses while the film is growing, utilizes the infrared emission from the sapphire substrate and from the growing film. The radiation from the sapphire substrate is partially transmitted through the silicon and partially reflected in the silicon, establishing an interference pattern which is used to determine silicon film thickness. Films in the range of 0.1 to 15 microns have been measured with an accuracy of 0.1 micron. The preparation and application of tantalum thin film passive components. R. ~NTAYLORand R. FAIRBANK, Radio Electron. Engr 33 (1967), p. 229. Thin film and diffused passive components are compared. Techniques are described for fabricating resistors and capacitors by sputtered tantalum and also inductors using nichrome/gold. Reasons for choosing T a as the resistor material and sputtering as the deposition method are discussed. Disproportionation and vaporization of solid silicon monoxide. W. HERTL and W. W. PULTZ,
J. Am. Ceram. Soc. 50 (7) (1967), p. 378. The vaporization rate of solid SiO was studied in the temperature range 1005 to 1475°C. It is concluded that: (a) in an argon atmosphere the vaporization rate is controlled by external gas diffusion ; (b) only the upper layers of the charge contribute to the vaporization ; (c) the heat of vaporization of SiO is 72.5 kcal/mole. Solid SiO disproportionates when heated in the temperature range 1000 to 1440°C, but the reaction does not go to completion. The reaction in the solid state is irreversible, the product silicon inhibits the reaction. Vaporization experiments in argon and in vacuum are described and compared to each other. The temperature dependence of the vaporization rate is also studied.