1158. Methods and equipment for measurement of vacuum pump parameters

Classi fled abstracts 1149--1158

II. Vacuum apparatus and auxiliaries 20. P U M P I N G SYSTEMS 20 1149. Ultrahigh vacuum evaporation apparatus type NP-350-UW. (Poland) A metal ultrahigh vacuum evaporation apparatus with sputter-ion pumps as described Three cryosorption pumps together with a zeolite trapped rotary p u m p establish fore vacuum of 4 to 5 × 10-3 torr. The I00 lltre/sec sputter-ion p u m p and the 1000 litre/sec subhmation p u m p provide evacuation of a bell jar with diameter 350 m m , and height 450 ram, down to the 10 -1° torr range. The feed-through for voltages up to 25 kV and the currents up to 5 A is described. R Cvranski et al, Prace PIE. 12 (1/2), 197 l 35-43 (in Pohsh). 20 1150. Modem pumping systems with diffusion pumps. (Poland) Pumping systems are described which use the oil diffusion p u m p type P D O 2000, with a pumping speed of 1800 htres/sec, ultimate pressure with a baffle and without freezing of 2 × 10 -7 torr, ultimate pressure with a llqmd nitrogen cooled baffle of 4 × 10 -6 torr, and m a x i m u m backing pressure of 4.5 × 10 -I torr at which the p u m p operates in a stable manner. The p u m p is filled with DC-705 oil and all gaskets are made of viton. With cooling of the enclosure of the p u m p Isolation valve, pressure of 2 × 10 -6 torr is reached. Also parameters of pumping systems with an oil diffusion p u m p having 800 htres/sec pumping speed are presented. Ultimate pressure of 5 × 10 -6 torr is reached in the pumping systems with freezmg. T Fiiewski, Prace PIE, 12 (1/2), 1971, 61-66 (in Pohsh). 20 1151. Technical parameters and arrangements of the vacuum evaporator type NA-500S. (Poland) Technical parameters and exploitation possibilities of the diffusionpumped evaporator type NA-500S are described. Pump-down curves of the evaporator are presented. On application of cooling by liquid nitrogen, pressure below 1 × 10 -7 torr can be attained after 70 minutes of pumping. The bell jar diameter is 500 m m . A n inductionheated evaporator arrangement enables evaporation of 1 g of permalloy in less than 15 minutes. Arrangements of the evaporator for deposition of Ni-Cr resistive thin films, conductive and dielectric thin films, are described. T Fijewski, Prace PIE, 12 (1/2), 1971,71-76 (m Pohsh). 20 1152. Improvement of production systems for vacuum metallization of quartz resonators. (Poland) Quahty of quartz resonators depends on the quality of metallLzmg electrodes. It is shown that application of a freon refrigerator for coolmg of the p u m p casing results in a decrease in pressure from 1.5 × 10 -5 to 2 × 10 -6 torr in the diffusion-pumped evaporator used for metalhzation quartz resonators, and thus better electrodes are obtained. K Goduslawski and J Grzybowski, Prace PIE, 12 (1/2), 1971, 77-81 (m

Polish). 20 " 30 1153. Vacuum evaporation apparatus with electron-beam evaporator. (USSR) A vacuum apparatus for deposition of films of metals and semiconductors by crucible-less electron-beam evaporation is described. The evaporator consists of an electron gun, focusing and deflecting systems and a magnetic prism. Application of the magnetic prism for deflection of the electron beam by 90 ° eliminates contamination of the electron gun by evaporating material. The gun is separated from the evaporation zone and it is not affected by heating of evaporating material or by gases released from it. This measure guarantees a high reliability of the evaporator, over 50 hours of continuous operation and its hfe is determined only by the life of the cathode of the electron gun. The diameter of the evaporating zone is not larger than 1 m m at the accelerating voltage of 20 kV and the beam current up to 25 mA. The evaporation zone-substrate distance is 60 ram. Yu P Terentev et al, Electromc Industry, Scmnt-Techn Coil, No 3, 1971, 62 (in Russian). 21. P U M P S AND P U M P FLUIDS 21 1154. Properties of the orbitron ion-sorption pump type PO-2000. (Poland) Properties of the orbltron pump with multiple lomzatlon cells (type

660

PO-2000), developed in Poland, are described. The criteria for choice of construction of ionization cells are considered. The water-cooled enclosure of the pump, 320 m m in length, with 260 m m diameter and weight of 23 kg is made of stainless steel. The p u m p consists of four ionization cells with anodes and field forming electrodes made of mesh to give low resistance to flow of gas. One electron source is used for all ionization cells. In the inlet of the p u m p a curtain is placed which prevents penetration of electrons and titanium vapour out of the pump. A titanium supply of 80 g is sufficient for about 1000 hours of continuous operation. The pumping speed of the orbltron pump is measured for various gases. The m a x i m u m pumping speed for nitrogen is 2600 htres/sec and that for argon is 29 htres/sec at anode voltage of 7 kV and power of 1200 W used for TI sublimation. The p u m p was used for evacuation of an evaporation apparatus. W Czarycki and J Filipowiez, Prace PIE, 12 (1/2), 1971, 5-12 (m

Pohsh). 21 1155. Properties of a modified ion-sorption pump with cold cathode. (Poland) Factors influencing the pumping speed for noble gases of sputter-ion pumps are considered. Properties of a modified diode sputter-ion p u m p with cathode columns on titanium cathode plates are investigated. Columns of silver, tantalum and titanium have been examined. It is found that the pumping speed for argon of the conventional diode p u m p is 4 per cent of the pumping speed for air. A modified p u m p with titanium columns reaches an argon pumping speed of 11 per cent of that for air, which is lower than that of the conventional pump. A modified p u m p with silver columns reaches an argon pumpmg speed of 27 per cent of the pumping speed for air, but the argon pumping speed decreases according to the amount of argon buried, probably due to diffusion of Ar in Ag. The modified pumps with tantalum columns (5 m m diameter and height 6 m m ) exhibit argon pumping speeds of 22 and 35 per cent of the pumping speed for air, which is the same as at the conventional pump. W Czarycki and E Nowicka, Prace PIE, 12 (1/2), 1971, 12-22 (m

Pohsh). 21 1156. Properties of sorption pumps and zeolite traps. (Poland) The properties of type PS-3, zeolite sorptlon roughing p u m p and type PZ-D zeolite trap type for oll diffusion pumps are studied. The sorpt~on p u m p is made of stainless steel and charged with 450 g of zeolite 5A. It is found that operating two sorptlon pumps in succession gives lower pressures than two pumps operated simultaneously. With a 10 minute preliminary cooling of the sorption pump, the pumping time m a y be reduced. An omegatron was used for gas analyslslnthesystem. In sorption pumped systems, the noble gases, such as neon and helium, appear in great quantities after reaching the final pressure. Construction of a zeohte trap filled with 150 g of 13X zeolite is described. It is shown that such traps reduce the backstreaming of oil vapours and the products of their decomposition from diffusion pumps and lower the ultimate pressure in the system. H Magielko, Prace PIE, 12 (l/2), 1971, 23-24 (m Pohsh). 21 1157. Problems of diffusion pump design. (Poland) Problems of diffusion p u m p design are considered. The dependences of the pumping speed on the gap of the nozzle and on the vapour pressure are studied both theoretically and experimentally. B Biezysko, Prace PIE, 12 (1/2), 1971, 44-49 (in Pohsh). 21 1158. Methods and equipment for measurement of vacuum pump parameters. (Poland) Equipment for measurement of pumping speed and ultimate pressure of diffusion pumps is described which is based on the method of constant pressure. The dimensions of the test dome agree with ISO recommendations. The throughput of gas is measured by four burettes with volumes of 5, 10, 50 and 100 ml. with stopcocks, and connected to an oil reservoir. The arrangement provides gas throughput in the range of 6 × 10 -4 to 2 torr litre/sec with an accuracy of 4-5 per cent and it enables measurement of diffusion p u m p speeds in the range 60 to 2000 litre/sec in the pressure range 10 -3 to 10 -e torr. The pressure in the test dome is measured by a hot-cathode ionization gauge. Also an equipment for calibration of lomzatlon gauges is described which Js based on the dynamical method using an iris with known conductivity. The arrangement for measurement of the back-

Classified abstracts 1159--1169 streaming rate of oil vapours from diffusion pumps, using the method of condensating the oil vapour on a cooled plate, is described. Z Marknw, Prace PIE, 12 (1/2), 1971,50-56 (in Polish). 22. GAUGES 22 1159. Rotary compression vacuum gauge with mercury drop. (Czechoslovakia) Construction of a simple glass vacuum gauge with mercury drop using a rotating capillary and a greased conical stopcock is described. The measuring range of the compression gauge Is 3 × 10 -2 to 20 torr. Accuracy of measurement is better than 4-7.5 × 10-3 torr. M Bano, CzechJPhys, A21 (3), 1971, 279-280 (in Czech). 23. PLUMBING 23 1160. Thermoelastic demountable vacuum seals. (Poland) Thermoelastic demountable vacuum seals are described. Two stareless steel cyhnders, with external knife-edges to be scaled, are connected by a centring tube. An external ring of soft material, for example copper, with an internal diameter several tenths of millimetre smaller than the diameter of the knife-edges, ts heated before it is attached to the cyhnders. The sealing force is prowded by the thermoelashc force generated by cooling of the ring. The construction of a valve with thermoelastic sealing is also presented. No leaks were found in the thermoelastic seals of two tubes, with diameter of 125 mm, subjected to heat cycling to 350°C and room temperature, using a leak detector with sensitivity of 10-13 torr lltres/sec. J Groszkowski and S Pytkowski, Prace PIE, 12 (1/2), 1971, 57-60 (in

Pohsh). 23 1161. Sealing of vacuum chambers. (Poland) The characteristics of creep in steel and copper and the structure and application of a vacuum-tight rotary seal with teflon are presented. Results of an investigation of time dependent leakage in seals are described. S Jonak and W Welik, Elektronika, 12 (5), 1971, 181-184 (m Pohsh). 25. BAFFLES, TRAPS AND REFRIGERATION EQUIPMENT 25 1162. Construction of cold traps for vacuum systems used in the Lamina factory. (Poland) The construction of stainless steel cold traps for vacuum systems used in the fabrication of microwave and transmitting tubes is described. Pressures of 1 × 10-7 torr can be attained after filhng the traps with liqmd nitrogen. J Podohas, PracePIE, 12 (1/2), 1971, 67-70 (inPolish).

III. Vacuum applications 30. EVAPORATION AND SPUTTERING 30 1163. Thin-film cadmium telluride solar cell. (Hungary) The junction characteristics and some properties of thin-film cadmium telluride solar cells with conversion efficiencies up to 6 per cent are investigated. The high efficiency has been obtained by removing adsorbed oxygen atoms on a polycrystalline CdTe layer by a glow discharge apphed before flash evaporation of copper telluride layer in vacuum. (France) J Lehran, International Conf Phys Chem Semiconductors Heterojunctions Layer Structure, Vol 4, Akademtai Kiado Budapest, 1971 163-170. 30 1164. Instability in cadmium selenide TFT. (Hungary) Thin-film field effect transistors with 10/~m gap using CdSe semiconductor and single SIO= or double SiO and Dy=O8 mixed layer insulator are investigated. The devices fabricated in the staggered structure were vacuum deposited in one pumpdown of a conventional oil-pumping system. Transconductance of about 2 mA/V, threshold voltage about - 1 V and input reststance greater than 101° ohm are obtained in transistors with the double layer of SiO and Dy203 mixture insulator. (Poland) B Mirowski et al, lnternatwnal Conf Phys Chem Semiconductors

30 1165. ESR and electrical properties of ion implanted layers in semiconductors. (Hungary) Defects and electrical properties of 10 keV nitrogen and 80 keV antimony ion implanted silicon have been investigated by means of electron spin resonance and Hall effect. The ion implantation was carried out at room temperature in a vacuum chamber evacuated by an ion pump to 2 × 10-6 torr. The annealing properties of defects were studied in vacuum at I × 10-7 tort. (Japan) S Namlm et al, International ConfPhys Chem Semiconductors Heterojunctions Layer Structure, Vol 4, Akademiai Kiado Budapest 1971, 179-186. 3O 1166. Photoelectric properties of PbTe epitaxial films. (Hungary) Influence of the growth conditions on the photoelectric properties of epitaxlal thin films of PbTe is investigated. The films were obtained by sublimahon from a quartz crucible or a tantalum boat onto heated substrates of NaCl, KCI and CaF= at 10-5 torr. It is found that the optimum temperature for a good epitaxial growth of PbTe films is about 250°C. (Italy) P de Stefano et al, Internatwnal Conf Phys Chem Semwonductors

Heterojunctions Layer Structure, Vol 4, Akademiai Kiado Budapest 1971, 187-193. 30 1167. Generation of anomalous photovoltages. (Hungary) A summatton model theory of anomalously high photovoltage in CdTe, CdSe, CdS, St and Ge thm films prepared by vacuum evaporation is presented. Results of experimental investigation of CdSe, CdS, CdTe, $1 and Ge thm films prepared by vacuum evaporation at 10-5 torr and deposited at an angle of about 30 ° to the substrate plane on substrates of glass, freshly cleaved mica and rock salt crystal are presented. The substrates were heated durmg the evaporation process to temperatures ranging from 20 to 800°C. The film thickness vaned from hundreds up to some thousands angstroms. The resistance of the films was in the range from 101° to 10TM ohm at room temperature. Electron microscope investigation showed that the photovoltage occurred in amorphous, polycrystalline and nearly monocrystalline films. The value of photovoltage depends on the size of the crystallltes and hasa maximum (e.g. at 1/~m for CdTe films). Thehighphotovoltage occurs due to the angle of evaporation of the films but not due to the gradient of thickness of the films. (Poland) B Orlowski, lnternattonal Con./"Phys Chem Semiconductors Heterojunctton Layer Structure, Vol 4, Akademlai Kiado Budapest 1971, 195-203. 3O 1168. Doping profile measurements of epitaxial gallium arsenide films. (Hungary) Doping profiles of epttaxial galhum arsemde films are determined by measurement of capacitance-voltage characteristics. Ohmic contacts to GaAs were obtained by evaporation of Au-Ge-Ni alloy in a vacuum system with background pressure of 10-7 torr. (Czechoslovakia) J Pokorny and R Fremunt, International Conf Phys Chem Semicon-

ductors Heterojunctions Layer Structure, Vol 4, Akademiai Ktado Budapest 1971, 215-224. 30 1169. The electrical conductivity of CdSe films prepared by vacuum evaporation. (Hungary) Influence of oxygen on the basic electrical properties of the CdSe thin films has been studied in order to determine the mechanism involved m the electrical conduction of these films during their annealing in an oxygen atmosphere. CdSe thin films were prepared by evaporation in vacuum at 10-3 to 10-8 torr on glass substrates from a molybdenum boat. Low-resistance hexagonal films about 3000/~ thick were obtamed. The CdSe thin films were prepared with a large selenium vacancy concentration and the vacancy concentration was changed step by step by annealing the films in oxygen at pressures of 10-4 to 760 torr. During these experiments the change of the electrical conductivity, earner concentration and effective mobihty in the films under study was measured and from the temperature dependence of these parameters an attempt was made to find the predominant scattering mechamsm in them. (Czechoslovakta) V Snejdar et al, International Conf Phys Chem Semiconductors

Heterojunctions Layer Structure, Vol 4, Akademtai Kaido Budapest

Heterojunctwns Layer Structure, Vol 4, Akademlal Kiada Budapest

1971. 171-178.

1971, 233-241.

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