摘要:

An apparatus to measure the outgassing rate of small parts in an ultrahigh vacuum environment was constructed using aluminum alloys. In order to test the reliability of the apparatus, we prepared test pieces and test chambers with various surface areas but with the same surface treatments, and measured the dependence of the outgassing rate on the surface area. The outgassing rate was measured using the throughput method. Before and during baking, the outgassing rate was proportional to the surface area, but after baking, the outgassing from a Bayard–Alpert (BA) gauge modified the proportionality. Residual gas analysis using a quadrupole mass spectrometer (QMS), which was specially prepared for use in extreme‐high vacuum [H. Ishimaru, J. Vac. Sci. Technol. A7, 2439 (1989)], showed that the main component of the outgassing before baking was H2O. After baking, H2was dominant if the outgassing from the BA gauge was subtracted. The outgassing from the BA gauge was composed of mainly H2and CO. The outgassing rate of the gauge was the dominant contribution to the background outgassing rate after baking and was about 6×10−10‐2×10−9Torrl/s. Moreover, the outgassing rate of the gauge depended on the ambient pressure. If the outgassing rate of the gauge is correctly subtracted from the total outgassing rate, the correct outgassing rate of the sample can be determined.

ISSN:0734-2101    

DOI:10.1116/1.577197

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Molecular dynamics calculations of nuclear stimulated desorption are carried out for a palladium crystal containing radioactive palladium atoms. The total desorption probability from various sites are computed, as well as the angular distribution of the desorbing atoms. The implications of the results to different experimental scenarios are discussed.

ISSN:0734-2101    

DOI:10.1116/1.577198

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Two methods of analyzing particles were interfaced to a low pressure chemical vapor deposition (CVD) reactor to evaluate whether or not particles were formed in the gas phase during the growth of aluminum films using tertiaryamine complexes of alane. A laser light scattering particle counter was used to detect large (>200 nm) particles in real time and established that the appearance of particles corresponded to the flow of precursor into the CVD reactor. A particle impaction system was used to collect particles (>20 nm) for analysis using analytical electron microscopy and electron diffraction. This established that the particles were crystalline aluminum and that the particle sizes ranged from 20–700 nm. The median size was 85 nm.

ISSN:0734-2101    

DOI:10.1116/1.577534

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

ISSN:0734-2101    

DOI:10.1116/1.577199

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Sulfur overlayers on the Fe(100) surface were deposited by decomposition of methanethiol (CH3SH), and characterized by Auger electron spectroscopy and low‐energy electron diffraction. Thermal decomposition of CH3SH results in the formation ofc(2×2) sulfur overlayers. In the presence of electron beam irradiation, high coverage (greater than half monolayer) sulfur overlayers with antiphase domain structures can be produced.

ISSN:0734-2101    

DOI:10.1116/1.577200

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The optical emission spectra from species excited during radio‐frequency sputtering of a Y–Ba–Cu–O target were observed as a function of position. A collimated optical fiber bundle parallel to the plane of the horizontal sputter target was translated vertically and horizontally to spectroscopically profile the excited species. The Ba and Cu constant intensity contours indicate a significantly different intensity decrease with increasing distance along a line normal to the plane of the target. However, there does exist a region immediately to the side and slightly above the target surface in which the Ba and Cu contours are similar. The pronounced extension of the O contours in a direction perpendicular to the target surface is consistent with negative ion resputtering phenomena.

ISSN:0734-2101    

DOI:10.1116/1.577201

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

To the model of reactive sputtering of Bergetal. [S. Berg, H.‐O. Blom, T. Larsson, C. Nender, J. Vac. Sci. Technol. A5, 202 (1987)] an energy dependent sputtering yield was introduced. Calculated hysteresis curves were in good agreement with measurements.

ISSN:0734-2101    

DOI:10.1116/1.577202

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The performance of a substrate heater/manipulator designed to address reliability and vacuum quality issues is discussed. The manipulator employs a novel, hollow magnetic feedthrough which is directly coupled to the substrate cradle, thus eliminating a gear train between the two. The need for only twoinvacuobearings enhances reliability, with a total of 5×106rotations accumulated to date without degradation in performance. Negligible increases in residual gas species, most notably CO, are found with either rotation (a severe problem with previous designs employing gear trains) or heating.

ISSN:0734-2101    

DOI:10.1116/1.577203

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

The drop in temperature resulting from adiabatic expansion during pumping from atmosphere can cause formation of a dense water aerosol in an ordinary vacuum chamber. The aerosol, consisting of water and impurities, can form rapidly, deposit on a silicon wafer and introduce contamination. In this study a unique thermocouple arrangement has been used to obtain the temperature profile of the gas during the pumping transient. From the temperature profile the maximum degree of saturation was calculated. The distance between adjacent surfaces was decreased until the thermocouple measurements no longer indicated supersaturation. Measurements of water aerosol generation were also made in a chamber in which the wall spacing could be varied. Finally a model for a vacuum load lock has been proposed in which water aerosol will not form adjacent to a silicon wafer. This model proposes that wafer be positioned in thex–yplane, with the pumping port located on the 0,0,zaxis. For typical system pumping time constants (V/S=3–6 s), a wafer spacing of ≤0.5 mm will permit normal pumping of the load lock without the added processing time required for nitrogen purging or slow pumping.

ISSN:0734-2101    

DOI:10.1116/1.577204

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Utilizing a previously developed entrapment model, the equations of motion for a particle confined within an intense cylindrical ion beam are derived. Energy transfer from the beam to the particle is then calculated and an expression for the time rate of change of the particle’s temperature determined. From the resulting model, trajectories and temperatures are calculated for micron and submicron‐sized aluminum and tungsten particles placed in a 100 keV, 10 mA, 3‐cm‐diam BF2ion beam. It is predicted that the Al particles undergo a phase transition in a time ∼1 ms, during which they acquire a center‐of‐mass velocity ∼1 m/s, and traverse an axial distance ∼1 mm, ultimately reaching the vaporization temperature. In contrast, during a 50 ms flight, the denser W particles are expected to follow precessing orbits, travel axial distances ∼0.1–1 m, and possess final axial velocities ∼10–100 m/s, never attaining their vaporization temperature. Along trajectories crossing a beam of radially varying ion density (a Gaussian profile is assumed), heat transfer to the particle varies as a function of radial position. Thus, as the particle’s radial position fluctuates, particle temperatures are predicted to oscillate about an equilibrium value that is independent of particle properties, varying solely with beam parameters.

ISSN:0734-2101    

DOI:10.1116/1.577205

出版商:American Vacuum Society    

年代:1991

数据来源: AIP