摘要:

The scattering of sputtered atoms by the sputtering gas has been modelled to obtain values for the distances which the atoms travel normal to the sputtering target before their energies are reduced to the thermal energy of the gas. This distance increases with the mass and energy of the sputtered atom and with decreasing gas pressure; for a 5‐eV atom of mass 80, it decreases from 42 cm at an argon pressure of 0.1 Pa to 0.44 cm at 10 Pa. For most diode sputtering configurations, the sputtered atoms are thermalized before reaching the substrate and the transport to the substrate is by diffusion. Relative deposition rates for substrates situated behind apertures or masks in these diffusive sputtering situations have been measured and compared with the solid angles subtended at the substrate by the effective aperture. The agreement between relative values is very good. Thus, the solid angle provides a simple measure for determining the effect of a mask on the deposition profiles. Significant changes in rates and profiles are possible. With a 5‐cm‐square aperture, the rate at the center decreases by 50% as the substrate moves 2 cm away from the aperture plane and there is a 30% variation in rate over the substrate. It is impossible to obtain a sharply defined edge using a mechanical mask.

ISSN:0022-5355    

DOI:10.1116/1.569429

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

The molecular‐beam epitaxy (MBE) method is an important tool which can provide new and different types of semiconductor films. The effusion ovens used in MBE studies were not an ideal Knudsen‐type design that had employed small orifices. We have measured the beam intensity distribution of an effusion oven that had 240 small channels. Applying the theory of Clausing, who derived the angular distribution from a small hole of radiusrand lengthL, and using the superposition principle, we have compared the calculation with experimental data and found good agreement. Intensity distributions from an oven with a single large opening are also measured. This geometry cannot be calculated but actually provides a useful method of collimating molecular beams.

ISSN:0022-5355    

DOI:10.1116/1.569415

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

Minute cracks in integrated circuit metallization at step edges constitute a very real hazard to device reliability. The computer simulations of metal film deposition reported in this study are in excellent agreement with SEM photographs of actual film step coverage obtained on unheated substrates. The use of the simulation technique to optimize step coverage has led to the modification of the planetary system used to support the wafers in the electron beam metal deposition apparatus. However, even with optimization of the planetary‐source configuration, small cracks in metal films at steps occur if the step angles are greater than a maximum value determined by the system geometry. For the deposition system used in this work that maximum angle is 40°. However, steps with angles of 50° have been successfully coated with crack‐free films when the substrates are heated above 300°C during deposition. We conclude that good step coverage may be obtained by optimization of the source‐planetary configuration in the deposition apparatus, by controlling the substrate step profiles and by the use of elevated substrate temperatures.

ISSN:0022-5355    

DOI:10.1116/1.569428

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

X‐ray photoelectron spectroscopy is used to study the change in the chemical composition of the surface film of the metastable tin–nickel alloy as a function of age. As‐plated samples as well as HCl‐etched samples are studied from very young (6 h and 2 min old, respectively) to about 60 days old. The change in the spectra caused by heating in vacuum is also shown. The film which exists on the as‐plated samples which are reasonably young (e.g., 14 days old) is significantly different from the film which grows after this native film has been removed. In all samples studied, the film contains primarily tin components. A small amount of nickel hydroxide forms as the samples age. The change of the film on the etched sample would be described as growth. For the as‐plated sample some change in thickness probably occurs over very long times, but the major change is in the chemical composition.

ISSN:0022-5355    

DOI:10.1116/1.569430

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

rf‐sputtered coatings of CrB2, MoSi2, Mo2C, TiC, and MoS2were examined by x‐ray photoelectron spectroscopy (XPS). Data on stoichiometry, impurity content, and chemical bonding were obtained. The influences of sputtering target history, deposition time, rf power level, and substrate bias were studied. Significant deviations from stoichiometry and high oxide levels were related to target outgassing. The effect of substrate bias depended on the particular coating material studied.

ISSN:0022-5355    

DOI:10.1116/1.569431

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

Ion scattering spectrometry (ISS) and concurrent secondary ion mass spectrometry (SIMS) were used to determine the depth profiles of anodic barrier oxide films grown on tantalum and type 1100 aluminum. The sputter rate in each case was determined from the film thickness measured by the anodic overvoltage, and the penetration time determined by the decrease in intensity of the metal oxide fragment observed using SIMS. A mixture of helium and neon ions was used to sputter aluminum oxide films in order to observe ion scattering of helium by oxygen, while taking advantage of the higher sputtering rate available with neon. A comparison of sputter rates for helium and neon on tantalum oxide indicated that neon sputtered the film at a rate eight times that of helium. SIMS depth profiling of the residual boron in the anodic aluminum oxide indicated a mixing effect which did not permit adequate resolution of the interface between the oxide film and the underlying metal.

ISSN:0022-5355    

DOI:10.1116/1.569432

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

Depth profiles of sodium and calcium in soda‐lime glasses have been measured by both Auger electron spectrometry and secondary ion mass spectrometry. Profiles by the two techniques agree closely and can be influenced by experimental conditions. In particular, radiation heating from a charge neutralization filament in the SIMS system is shown to alter the sodium depth profile in specimens which have a surface depletion of sodium.

ISSN:0022-5355    

DOI:10.1116/1.569433

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

Clean and intentionally contaminated stoichiometric TiD2thin films have been formed under controlled conditions and the surface compositions of the films measured using Auger electron spectroscopy. The unique ultrahigh vacuum system used to fabricate the films is described in detail. In addition, the Auger spectra of clean and CO‐ and CO2‐contaminated films, before and after deuteriding, are presented. TheMVVandLMVpeaks in the differential spectrum of TiD2are significantly different from the corresponding peaks in the Ti spectrum, presumably a result of the deuteride formation. Films intentionally contaminated with CO and CO2have Auger spectra with oxygen peaks and carbide‐like carbon peaks. The C and O peak heights and shapes for Ti exposed to CO and CO2do not change upon formation of TiD2. In addition, for each of these gases, a definite ratio of C/O peak heights was observed: For CO, the C/O ratio was ∠1.3, while for CO2it was ∠0.58. Both ratios were independent of gas exposures up to ∠1 Torr s.

ISSN:0022-5355    

DOI:10.1116/1.569434

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

Auger electrons emitted from the valence band in solids carry information on the local density of states in this band in the surface region. The emitted Auger electron intensity distribution is a convolution product of the transition densities of the two valence‐band electrons involved in the Auger process in the ionized solid, multiplied with the probability of escape of the outgoing electron. In a first‐order approximation the transition density is proportional to the density of states. A comparison between a theoretical, or a directly measured, density of states and Auger spectra must rely on mathematical convolution/deconvolution techniques. Here it is proposed to use spline functions to represent the densities of states to be convolved. This method is unconstrained with respect to form of the density of states. The same representation is used to deconvolve experimental kinetic energy distributions of Auger electrons, in a nonlinear least‐squares fitting of a convolution square of a trial density‐of‐states function. As an example, the Auger spectrum of Si is considered and compared with a calculated density of states.

ISSN:0022-5355    

DOI:10.1116/1.569435

出版商:American Vacuum Society    

年代:1978

数据来源: AIP

摘要:

It is demonstrated that the chemical composition of thick and multilayer insulating films can be easily depth profiled by Auger electron spectroscopy by laterally scanning an angle‐lapped region that reveals the entire depth to be profiled. Conventional depth profiling of such structures is often difficult because of unstable sample charge‐up conditions that occur when Auger measurements are made during ion milling. The angle‐lap technique is nondestructive, in that it allows one to reexamine the entire profile whenever desired. It is thus particularly suitable for investigation of samples with initially unknown or trace impurities. Also, this technique is free of depth‐resolution degradation and differential sputter yield effects usually associated with long‐term ion milling of thick films. The absolute depth resolution of the angle‐lap–Auger profiling method is independent of the film thickness and is equal to the electron beam diameter plus sample manipulator resolution divided by the angle‐lap lateral magnification. An ultimate depth resolution of ∠35 Å would be possible using a 0.5‐μm‐diam beam, a 0.2° lap, and a 0.5‐μm manipulator resolution. This is approaching the depth resolution associated with the finite escape depth of Auger electrons. Using a 10‐μm electron beam and a 0.5° angle lap in the present study, a depth resolution of about 1000 Å was obtained, as predicted. The oxygen concentration in oxygen‐rich polysilicon films measured by this technique agrees with that measured by an Electron Probe Microanalyzer. The Auger data also suggest that all oxygen atoms in the films are bonded to silicon in the form of SiO2.

ISSN:0022-5355    

DOI:10.1116/1.569436

出版商:American Vacuum Society    

年代:1978

数据来源: AIP