摘要:

Assuming a uniform flux of ions upon the target, a cosine distribution of sputtered material, unity sticking coefficient on the substrate, no surface mobility and no gas collisions, deposition uniformities are calculated for several device configurations. These include: (1) the “peak” configuration of adjacent rectangular targets, (2) the disk type, and (3) coaxial cylindrical targets and substrate holders. Areas over which the deposition uniformities are predicted to be within ±1% to ±10% were computed and these results compared with available experimental results obtained from rf sputtering devices. The good agreement obtained shows that the method does give a practical approach to estimating deposition uniformities for rf sputtering systems where the assumptions are reasonably well obeyed. The peak configuration is examined in some detail and it is found that there is an optimum position for the substrate table at which the largest, area of uniform deposition is obtained.

ISSN:0022-5355    

DOI:10.1116/1.1492710

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

The capacitance manometer appears to be a convenient and reliable pressure measuring device over the range 0.1–1000 mTorr. We find that deviations from linearity in this region do not exceed a few tenths of a percent. On the other hand, mercury streaming in a trapped McLeod gauge can introduce errors in the measured pressures which are dependent upon the pressure in a complicated manner.

ISSN:0022-5355    

DOI:10.1116/1.1492711

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

Adhesion of evaporated amorphous Se on oxide surfaces has been studied. For selenium evaporated in a relatively poor vacuum of10−5Torr onto aluminum substrates coated with a surface oxide layer, the Se deposit could easily be peeled off the substrate. Electron microscope examination of the separated surfaces showed that the separation, in general, occurred at or in the immediate vicinity of the Se-aluminum oxide interface. Complimentary studies were also conducted on Se evaporated onto oxide substrates in an ultra-high vacuum system. Substrates used were single crystals of sapphire and MgO and virteous quartz. Experimental observations indicated that the relative strength of adhesion and the fractured surface features were dependent on and could be correlated with the substrate preheat temperaure in a high vacuum prior to Se evaporation. With a sufficiently high preheat temperature, the interfacial bond strength exceeded that of the cohesive energy of Se and the failure occurred in the Se layer. Studies on the effect of chemisorbed gas species on adhesion showed that water absorption does not degrade the strength of the Se-oxide structure. However, absorption of long chain organic acids and alcohols on the substrate surface resutled in poor adhesion strength, and the failure occurred at the interface region.

ISSN:0022-5355    

DOI:10.1116/1.1492712

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

A gas-reaction chamber has been constructed, which allows thein situtransmission electronmicroscopic study of gas-solid reactions at temperatures up to 900 °–1000 °C. The morphological and crystallographic properties of iron, of iron and wüstite, and of magnetite depositing epitaxially on (111) gold substrates, either by the thermal decomposition ofFe(CO)5or by decomposition and chemical reaction fromFe(CO)5–H2or fromFe(CO)5–H2–H2Omixtures, are described. In other examples, the oxidation of the initially depositing iron is illustrated. In some of the experiments, polycrystalline iron foils were substituted for the (111) gold substrates, and a profound effect of iron deposition on the rate of grain growth in the iron foil was found. Coalescence of iron crystallites and high mobility of the deposit were observed. Incidental observations on the decomposition ofNi(CO)4are described. These permit comparison of the epitaxial relationships in the Ni–Au and NiO–Au systems with those of the corresponding iron systems.

ISSN:0022-5355    

DOI:10.1116/1.1492713

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

ISSN:0022-5355    

DOI:10.1116/1.1492714

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

Nb–Nb2O5–metal diodes, after voltage breakdown, exhibit current-controlled negative resistance and switching between two stable conduction states. Before breakdown,Nb–Nb2O5–Audiodes are electroluminescent with hole injection occurring at theNb2O5–Auinterface. After breakdown, electroluminescence is closely related to switching. The energy of emitted radiation has maxima at 1.3 and 1.6 eV. Electroluminescence is both polarity- and voltage-dependent, indicating that hole injection, not heating, produces electroluminescence. Increased electroluminescence accompanies diode switching. Microscopic observation shows that bistable switching and dielectric breakdown ofNb–Nb2O5–Audiodes occur at small conducting regions in the oxide. Destructive dielectric breakdown inNb–Nb2O5–Cudiodes differs from that inNb–Nb2O5–Audiodes.

ISSN:0022-5355    

DOI:10.1116/1.1492715

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

Observations have been made on the motion of thin films of oil on polycrystalline tungsten surfaces at pressures of the order of10−6−10−8Torr. Measurements were made by utilizing the difference in secondary electron coefficient between a clean and an oil-covered surface. The apparatus is discussed. Propagation velocities of films of Octoil-S and Dow Corning 702 are presented for surface temperatures between 230 and 310 K. The implications of this motion are discussed.

ISSN:0022-5355    

DOI:10.1116/1.1492716

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

Emission and absorption measurements have been made in rf glow discharges through pure argon and through argon with 1%O2added. The results indicate that addedO2reduces the amount of excitation of neutral argon, particularly the concentration of metastable atoms. At the same time, increased emission is observed from argon ions whenO2is added. This is attributed to an increase in the argon ion concentration. The results of these experiments have important implications regarding the mechanisms operative in rf sputtering processes. Namely, under the conditions studied (rf power density of10 W/cm2and argon pressure4×10−2Torr) direct electron impact ionization appears to be the predominant maintenance mechanism of the glow rather than ionization resulting from metastable atom collisions. In addition, it is proposed that addition of oxygen to the argon discharge atmosphere serves to increase the secondary electron emission coefficient of the fused silica target.

ISSN:0022-5355    

DOI:10.1116/1.1492717

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

The ac impedance has been considered in a general way which includes the effect of a distribution of trapping states within Schottky-type energy barriers. Starting with the complete unipolar transport equation, and introducing a density-of-trapping-states function, depending generally on both position and energy, one arrives at a useful formulation of the ac impedance. This result is possible because of the rapid variation of the effect of traps in such barriers which restricts their main contribution to a narrow range of positions and energies. Thus, expressions are obtained which relate the ac impedance measurements to the trapping effect at regions of the barrier corresponding to the applied frequency, voltage, and temperature. With these three independent variables, it is possible to experimentally scan the barrier over energy and position, obtaining a profile of trap densities and other barrier properties as well as independent tests on the selfconsistency of the method. Some experimental results obtained from thin-filmNb2O5capacitors are given and shown to be in general agreement with the theory. This agreement also supports our contention, based on previous dc studies, that theNb2O5film contains a large ionic space charge. From the results we calculate a barrier minimum of 0.38 eV, an average trap density of about1019 cm−3 eV−1, and trap capture cross section of about10−13 cm2.

ISSN:0022-5355    

DOI:10.1116/1.1492718

出版商:American Vacuum Society    

年代:1969

数据来源: AIP

摘要:

The sensitivity of Bayard–Alpert gauges has been measured as a function of the grid-filament spacing and found to vary by as much as a factor of 2.5. It is suggested that the large variation of sensitivity from one gauge to another results from variability of filament positioning. An hypothesis is proposed, and substantiated by test, which relates the sensitivity to the angular momentum, about the axis of the grid, with which electrons are launched into the grid. It is shown that electrons with small initial angular momentum have the longest orbits in the useful ionizing volume. A new type of Bayard–Alpert gauge has been developed, based on this hypothesis, whose sensitivity is independent of filament position and of the potential of the envelope. The sensitivity factor of this new design is about55 Torr−1for nitrogen.

ISSN:0022-5355    

DOI:10.1116/1.1492719

出版商:American Vacuum Society    

年代:1969

数据来源: AIP