摘要:

Substrate ion fluxes from unbalanced magnetron sources are generally controlled by the use of additional magnetic fields. These methods are not always suitable for differentially controlling the ionic flux from multiple sources. We report here a simple method suitable for attaining such control that can be easily adapted to most unbalanced magnetron systems. The flux leakage from an unbalanced magnetron is controlled by the use of a mild steel keeper with a detachable mild steel annulus. The annulus redirects the unbalanced field lines through the keeper to the rear poles of the magnetron. The flux leakage is thus controlled by varying the thickness of the annulus. Ion saturation currents measured at the substrate, with and without a 0.9 mm thick mild steel annulus, were found to differ by a factor of approximately 3 at an argon partial pressure of 1 mTorr. Furthermore we demonstrate that the changes in ion current density are achieved without alteration to the magnetron operating parameters.

ISSN:0734-2101    

DOI:10.1116/1.580962

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The vacuum behavior of stainless steel vacuum chambers,ex situsputter coated with a thin film(∼1 μm)of getter material, has been studied to determine if after air exposure the getter film could be activated by a bakeout so as to transform the coated vacuum chamber into a pump. The materials studied so far are Ti, Zr, Hf, and some of their binary alloys. They all display an activation temperature lower than 400 °C, i.e., within the reach of the baking temperature of stainless steel vacuum chambers. The lowest activation temperature of 200–250 °C, measured for an equiatomic alloy of Ti and Zr, allows extension of this method to chambers made of copper and aluminum alloys. The experimental results, described here in detail, indicate that the values of the activation temperature obtained using electron stimulated desorption, pumping speed, and Auger spectroscopy measurements are self-consistent.

ISSN:0734-2101    

DOI:10.1116/1.580963

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

The continuing trend toward miniaturization of integrated circuits is driving the development of low dielectric constant materials(k<3)and their integration with copper metallization. In this work, the interface formed between copper or titanium and low dielectric constant polymer was explored. Fluorinated poly(arylene ether) (FLARE™ 1.0) was studied as an example of fluorinated organic polymers. X-ray photoelectron spectroscopy (XPS) was used to study the chemical interactions between the metal and FLARE™ 1.0 during interface formation. XPS revealed that copper is relatively unreactive with FLARE™ 1.0 compared to titanium. However, depositing the copper by rf sputtering caused significant defluorination of the FLARE™ 1.0 surface, which was not evident for thermally evaporated copper. No copper fluoride formation was observed for either deposition. Evaporation of titanium does cause defluorination of the polymer, with subsequent formation of titanium fluoride. Titanium is more reactive than copper and forms bonds of T–C, Ti–O, and Ti–F at the interface.

ISSN:0734-2101    

DOI:10.1116/1.580964

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Ex situaqueous (NH4)2S treated sulfur-passivated InP substrates have been studied using ultrahigh vacuum scanning tunnelling microscopy (STM) and low-energy electron diffraction (LEED). The morphology of the passivated surface was imaged after a mild sample annealing. The STM images of a surface exhibiting a good 1×1 LEED pattern show that the top layer of the sulfur-passivated surface is poorly ordered. A surface bilayer atomic step has been observed to be common on sulfur-passivated surfaces. The magnitude of the surface roughness for the passivated surfaces lies between 10 Å and 25 Å; this is much smaller than the roughness of InP(100) substrates prepared using previously published methods. After annealing the sample at∼420 °C, a (2×1) LEED pattern with split half-integer spots has been observed. The associated STM images show that these split half-integer diffraction beams correspond to regularly spaced domains with a width of∼20–30 Å in the [011̄] direction. The surface roughness increases with annealing temperature; the surface corresponding to the best 2×1 LEED symmetry (annealing at∼420 °C) has a roughness double that of the 1×1 phase.

ISSN:0734-2101    

DOI:10.1116/1.580953

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Thin films of lead titanate(PbTiO3)were prepared on silicon substrates by sputtering. Two processes have been developed; (a) thein situprocess (the growth temperature was 440 °C) and (b) the deposition at room temperature followed by a conventional annealing at 680 °C. The dielectric constant, the ferroelectric, and the piezoelectric properties were evaluated and compared. The dielectric constant of films depositedin situwas higher than those of postannealed films likely due to the dense microstructure with fine and homogeneous grains. The embedded beam method and the Berlincourt piezometer were used to measure thee31and thed33piezoelectric coefficients, respectively. ThePbTiO3films were naturally polarized, in particular the films grownin situhave large piezoelectric constants:e31=−0.49 C/m2andd33=20 pC/N.These values agree broadly with data of bulk ceramics, however, with bulk material a poling treatment is necessary to attain these values. The poling of the postannealed films leads to a substantial increase of their piezoelectric properties;e31=−0.26 C/m2andd33=8 pC/Nfor virgin film ande31=−0.41 C/m2−d33=18 pC/Nfor an applied electric field of 110 kV/cm (close to saturation) and a poling time of 30 min. The piezoelectric response was found to depend on the direction of the poling field. Noted33ande31decreased when the poling field was applied against the preferred polarization direction; the polar domains were oriented from the film surface to the substrate.

ISSN:0734-2101    

DOI:10.1116/1.580954

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Empirical formulae for the compression ratio and speed factor of a single stage turbomolecular pump operating in the molecular flow regime are developed for blade speeds lower than the most probable molecular velocity. These formulae are based on Becker’s compression formula derived from drag theory and on Bernhardt’s pumping speed formula but are modified and extended to take account of the full range of parameters in the two dimensional infinite blade row model of Kruger. Numerical constants are determined using the direct simulation Monte Carlo method. Results from the latter method are presented as contour plots of transmission probabilities intended to cover cases of interest for design calculations.

ISSN:0734-2101    

DOI:10.1116/1.580965

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

After confirming the basic characteristics of two types of metal gasket fittings, which are used in construction of ultrapure gas delivery systems for semiconductor manufacturing, it is noticed that the pipe usually twists at the time the fitting is tightened. This may be the possible cause of an external leak, therefore a twist leak test was undertaken to confirm the reliability of the seal during assembly. As a result, it was found that one type of fitting leaked and another type of fitting did not leak. This later type did not leak (leak rate is less than2.98×10−16 Pa m3/s) even after 70° of twisting.

ISSN:0734-2101    

DOI:10.1116/1.580966

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Hydrogen outgassing is the most significant factor limiting the attainment of outgassing rates below10−12 mbar l s−1 cm−2in stainless steel vacuum systems. This limit turns out to be crucial in very large vacuum systems, like the VIRGO vacuum tubes (2 tubes 1.2 m diam, 3000 m length). Heating the raw material at 400 °C in air was suggested as a money saving alternative to the classical vacuum heating at 950 °C. We report the results of hydrogen content analysis performed on stainless steel samples submitted to different treatments, and also the measurement performed on a prototype tube (1.2-m-diam, 48-m-long). We concluded that air bake-out drives out most of the hydrogen absorbed in the bulk stainless steel, while the presence of an oxide layer does not reduce the hydrogen outgassing.

ISSN:0734-2101    

DOI:10.1116/1.580967

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

摘要:

Numerical solution of the second-order partial differential equation describing the evolution of temperature of a tungsten filament in time allows the simulation of some effects that occur in the case of heating the filament by a series of pulses. Namely, the phenomena investigated are (1) phase shifts between heating current and filament temperature, (2) amplitude of temperature modulation due to variation of supply voltage and (3) the temperature dependence of the time constant of temperature changes. The method presented here may be used for any filament workingin vacuo. It may be applied in mass spectrometry, vacuum measurements, thin films deposition by hot filaments and other applications.

ISSN:0734-2101    

DOI:10.1116/1.580968

出版商:American Vacuum Society    

年代:1998

数据来源: AIP

ISSN:0734-2101    

DOI:10.1116/1.580970

出版商:American Vacuum Society    

年代:1998

数据来源: AIP