- Email: [email protected]
Precision thin-film cermet resistors for integrated circuits
334
ABSTRACTS ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
should be governed by the characteristics desired in the film. The vacuum evaporation and sputtering techniques are outlined; advantages and disadvantages of each method are presented. The application of electron beam heating to the vacuum evaporation technique is also discussed. High v a c u u m s y s t e m s for thin ~ applications. M. H. HABLANIANand H. A. S~tNHESZ, SCP and Solid State Technology, December (1966), p. 37. The importance of low pressure environment on thin film deposition is discussed. Pressure measurement is shown to be both critical and complex. The location of the gauge in the system and of the connecting tubulation are important considerations. Errors encountered with conventional and nude ionization gauges can be significant. Contamination of thin film deposition systems are grouped into six categories. Three are characteristic of the vacuum system while the other three are associated with the material being processed. Diffusion pump backstreaming is shown to contribute only 1/100 of a monolayer per hour in a well baffled system. P r e c i s i o n thln-film c e r m e t resistors for integrated circuits. L. BP.AUIqand D. E. Loop, Proc. IEEE
54, No. 11, November (1966), p. 1521. The use of thin-film resistors in monolithic integrated circuits is becoming more widespread as the performance requirements imposed upon circuit designers become more stringent. A cermet, consisting of a mixture of Cr and SiO, was selected as a suitable resistor material for this purpose because of its compatibility with semiconductor materials and processes, and because of its stability and reproducibility over a wide range of sheet resistance. Cermet films with sheet resistances of 300, 1000 and 2000 fl/square were flash evaporated on silicon substrates, and resistors were fabricated. The techniques for depositing the cermet films and fabricating the resistors are discussed, and methods for subsequently adjusting the resistors to precise values are described. The properties of the completed resistors are presented in detail. Some applications o f thin film circuits in electronic equipment. P. C. MICHAEL,Electron. Equip. News November (1966), p. 78. Thin film circuits can be used to replace discrete components, in their own right or in hybrid circuits. Production techniques and properties of t.f.c.s, are considered together with specific applications such as in resistor networks, signal attenuators, linear active circuits and digital active circuits. Evaluation of Mgh v a c u u m pumlag H. G. NOLLm, Vacuum 16, No. 11, p. 613. The speed of a pump depends not only upon the properties of the pump itself but generally also upon the velocity- and angledistribution of the gas molecules entering the pump. For the exact definition of the speed therefore these influences besides other parameters, e.g. the nature of the gas, must be known. Consequently the effective speed for instance of the combination of a pump and a baffle or of a pump and a length of pipe can be calculated from the intrinsic speed S' of the pump, if the value of 8' includes the angle distribution as produced by the baffle or pipe respectively. 8' generally is not identical with the intrinsic speed S that corresponds to the cosine-distribution of the incoming molecules. The backstreaming rate of pump fluid lies between zero and a maximum value of R,,~ depending on the state of the vacuum container. It is therefore suggested to specify R~,.~---being a characteristic quantity for the pump propermimtead of the actual hackstrearning rate which may vary in each individual case. Some characteristics o f t r l o d e ion pumps. U. R. BANC~and R. D. CRAm, Vacuum 16, No. 12, p. 647. This paper describes experiments with the triode type ion pump which differs in a number of important respects from the original diode design. The construction of a typical triode pump is described and its method of operation is discussed. A number of experiments have been carried out to investigate stability of pumping over both short (15 min) and long (100 hr) periods when pumping air, argon, hydrogen and acetylene at pressure in the 10-5 torr region. In no cases were sharp pressure fluctuations observed though with hydrogen and acetylene it was found that over the longer periods the speed, in certain circumstances, would change by up to a factor of two. With air the change in speed even on a 10.4 torr run was less than 10 per cent over 400 hr. Data on variation of pump speed and throughput with pressure is also presented and work using starting pressures up to 0.1 tort of air is described. A comparison has also been made between the measured weight loss of cathode material and quantity of air pumped and it is found that apparently ordy one titanium atom is lost from the cathode for approximately two gas molecules pumped.
ABSTRACTS ON M I C R O E L E C T R O N I C S AND R E L I A B I L I T Y
should be governed by the characteristics desired in the film. The vacuum evaporation and sputtering techniques are outlined; advantages and disadvantages of each method are presented. The application of electron beam heating to the vacuum evaporation technique is also discussed. High v a c u u m s y s t e m s for thin ~ applications. M. H. HABLANIANand H. A. S~tNHESZ, SCP and Solid State Technology, December (1966), p. 37. The importance of low pressure environment on thin film deposition is discussed. Pressure measurement is shown to be both critical and complex. The location of the gauge in the system and of the connecting tubulation are important considerations. Errors encountered with conventional and nude ionization gauges can be significant. Contamination of thin film deposition systems are grouped into six categories. Three are characteristic of the vacuum system while the other three are associated with the material being processed. Diffusion pump backstreaming is shown to contribute only 1/100 of a monolayer per hour in a well baffled system. P r e c i s i o n thln-film c e r m e t resistors for integrated circuits. L. BP.AUIqand D. E. Loop, Proc. IEEE
54, No. 11, November (1966), p. 1521. The use of thin-film resistors in monolithic integrated circuits is becoming more widespread as the performance requirements imposed upon circuit designers become more stringent. A cermet, consisting of a mixture of Cr and SiO, was selected as a suitable resistor material for this purpose because of its compatibility with semiconductor materials and processes, and because of its stability and reproducibility over a wide range of sheet resistance. Cermet films with sheet resistances of 300, 1000 and 2000 fl/square were flash evaporated on silicon substrates, and resistors were fabricated. The techniques for depositing the cermet films and fabricating the resistors are discussed, and methods for subsequently adjusting the resistors to precise values are described. The properties of the completed resistors are presented in detail. Some applications o f thin film circuits in electronic equipment. P. C. MICHAEL,Electron. Equip. News November (1966), p. 78. Thin film circuits can be used to replace discrete components, in their own right or in hybrid circuits. Production techniques and properties of t.f.c.s, are considered together with specific applications such as in resistor networks, signal attenuators, linear active circuits and digital active circuits. Evaluation of Mgh v a c u u m pumlag H. G. NOLLm, Vacuum 16, No. 11, p. 613. The speed of a pump depends not only upon the properties of the pump itself but generally also upon the velocity- and angledistribution of the gas molecules entering the pump. For the exact definition of the speed therefore these influences besides other parameters, e.g. the nature of the gas, must be known. Consequently the effective speed for instance of the combination of a pump and a baffle or of a pump and a length of pipe can be calculated from the intrinsic speed S' of the pump, if the value of 8' includes the angle distribution as produced by the baffle or pipe respectively. 8' generally is not identical with the intrinsic speed S that corresponds to the cosine-distribution of the incoming molecules. The backstreaming rate of pump fluid lies between zero and a maximum value of R,,~ depending on the state of the vacuum container. It is therefore suggested to specify R~,.~---being a characteristic quantity for the pump propermimtead of the actual hackstrearning rate which may vary in each individual case. Some characteristics o f t r l o d e ion pumps. U. R. BANC~and R. D. CRAm, Vacuum 16, No. 12, p. 647. This paper describes experiments with the triode type ion pump which differs in a number of important respects from the original diode design. The construction of a typical triode pump is described and its method of operation is discussed. A number of experiments have been carried out to investigate stability of pumping over both short (15 min) and long (100 hr) periods when pumping air, argon, hydrogen and acetylene at pressure in the 10-5 torr region. In no cases were sharp pressure fluctuations observed though with hydrogen and acetylene it was found that over the longer periods the speed, in certain circumstances, would change by up to a factor of two. With air the change in speed even on a 10.4 torr run was less than 10 per cent over 400 hr. Data on variation of pump speed and throughput with pressure is also presented and work using starting pressures up to 0.1 tort of air is described. A comparison has also been made between the measured weight loss of cathode material and quantity of air pumped and it is found that apparently ordy one titanium atom is lost from the cathode for approximately two gas molecules pumped.