摘要:

Chemical effects on Auger spectra have been studied for some time. Only recently, however, has it been shown that these effects can be used to study the ’’chemical structure’’ of interfaces by observing the rate of appearance of one chemical state and the rate of disappearance of another chemical state of an element during depth profiling.1–3In this way, the simultaneous existence of different states of the same element can be observed. Percentages of the atoms in these different chemical states present at any position in the interface can be determined. Also, the chemical state of various elements present can be identified and changes mapped out through interfaces.Studies of the chemical structure of interfaces offer important information in the attempt to understand the behavior of interfaces in semiconductor devices. The characterization of these interfaces in Si and Al is of critical importance to LSI technology, particularly for MOS devices. The system which is of greatest interest in actual device configurations is the system wherein Al is deposited on top of SiO2which has been grown on Si. The real system thus produced consists of alumina on top of Al which is deposited on SiO2and may include alumina between the Al and SiO2and then SiO2on top of the Si. Before one can hope to understand these hybrid interfaces, it is necessary to understand interfaces of pure oxides grown on pure elemental substrates.We have used high‐energy‐resolution Auger spectroscopy in conjunction with high‐spatial‐resolution ion‐sputter depth profiling to study the chemical structure of the interfaces between MgO and Mg, Al2O3and Al, and SiO2and Si. The MgO/Mg system has been included in this study primarily because of the similarity of its spectra to those of Al, Si, and their oxides, and therefore as an aid to the understanding of this series of elements and to the interpretation of the shapes and energies of their peaks.LVVspectra: TheL2,3VVspectra we have observed are in agreement with the many previously reported observations. In MgO, we see a large peak at 31 eV and small peaks at 49 and 59 eV. Clean Mg spectra show the major peak at 43 eV.Al2O3produces a large peak at 52 eV and a small peak at 41 eV. The major peak of clean Al occurs at 67 eV with smaller ones at 52 and 41 eV.SiO2spectra have peaks at 62 and 78 eV. Clean Si has a major peak at 92 eV and small peaks at 62, 78, and 108 eV.The shift in the relative magnitude of the peaks upon oxidation can be explained by considering the up and down electron transitions in the oxide to come from the oxygen level, filling a vacancy in the Mg, Al, or SiL2,3level.4,5The structure in these oxide peaks can be explained through the different density of states and transition probabilities of the bonding and nonbonding oxygen 2pelectrons. The presence of free Mg, Al, or Si in the corresponding oxides can be detected with a high sensitivity due to the very sharp, mostly‐negative‐going, free‐atom peak in thedN/dEspectra, widely separated from the corresponding oxide peak. The shape and high sensitivity for this peak can be explained with reference to theN(E) curve.KLLspectra: TheKLLspectra of the pure metals are also in agreement with previous reports. However, we have also been able to observe the chemical shifts in these peaks upon oxidation. The majorKLL‐series peaks,KL1L1,KL1L2,3, andKL2,3L2,3, are seen to shift to lower energies in the oxides. Thus, the MgKL2,3L2,3peak at 1184 eV appears at 1177 eV in the oxide. The AlKL2,3L2,3peak at 1396 eV shifts to 1389 eV in the oxide. And the SiKL2,3L2,3peak moves from 1618 to 1611 eV upon oxidation.Interfaceprofiles: In the chemical profiling of these interfaces we monitor the appropriateL2,3VVregion of the spectrum, the oxygenKL2,3L2,3region, and the appropriate metalKL2,3L2,3region. We initially observe pure oxide spectra at the appropriate energies which includes some structure on the sides of the oxygenKLLspectra. As the profiling approaches the interface, the first indication is the reduction in the peak‐to‐peak height of the metalKL2,3L2,3peak and the appearance of the ’’free atom’’KL2,3L2,3peak of the appropriate metal atom. TheKLLspectra provide the first indication of the approach of the interface due to the larger escape depth of electrons at these energies. This transformation of the metalKL2,3L2,3peak continues showing the simultaneous presence of the two chemical states of the metal as the profiling moves into the interface. At this point, the oxygenKL2,3L2,3peak begins to decrease in height as does the metalL2,3VVoxide peak. A ’’free atom’’ metalLVVpeak also grows at the expense of the metal oxideLVVpeak and both the ’’free atom’’LVVandKLLpeaks reach a steady state value as the oxygen peak goes to zero. The SiO2/Si interface is the most abrupt of the three studied. With an estimated depth resolution of 10–15 Å, we have seen interfaces as narrow as 30 Å under oxide films of 1100 Å thickness. Al2O3/Al and MgO/Mg interfaces are much broader and are more difficult to profile. SEM and TEM studies show the craters produced in profiling SiO2/Si to be extremely smooth while Al and Mg craters appear to be very rough.

ISSN:0022-5355    

DOI:10.1116/1.568905

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

Dielectric instability and breakdown in SiO2have been well characterized by many experimental techniques, including measurements of thickness dependence, contact barrier dependence, and time dependence of breakdown as well as a determination of radiation sensitivity and prebreakdown charge buildup within the insulator. All of the various types of data can be explained consistently by an impact ionization model, which predicts a negative‐resistance type of instability; electrons are injected from the cathode, the electron distribution is heated, hot electrons ionize the lattice, and the residual positive charge distorts the electric field and further increases impact ionization. The model is sensitive to two key parameters, the ionization bandgap Ei, and the electron–phonon scattering length λ.

ISSN:0022-5355    

DOI:10.1116/1.568911

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

The kinetics of the reduction of SiO2in Au/SiO2/Si structures has been studied as a function of time, temperature, and annealing environment. Reduction of the oxide seems to be dependent on the presence of Au–Si eutectic as regions free of Au remained intact and samples of Au on bulk glass showed no reactions. The rate of reduction of the oxide proceeds with an activation energy of approximately 26 kcal/mole.

ISSN:0022-5355    

DOI:10.1116/1.568952

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

Nonstoichiometric interfacial transition regions located between thermally grown silicon oxide films and silicon substrates have been identified by variation in silicon and oxygen x‐ray photoelectron spectral data.1Changes in Si 2pbinding energies, and line intensities and linewidths of both Si 2pand O 1sphotoelectron lines are detected in spectra of oxide films less than 25‐Å thick and are each consistent with a silicon‐rich transition region. The composition and width of the nonhomogeneous oxide transition regions in ultrathin, thermally grown silicon oxide films are quantitatively evaluated in the present study using Si 2pbinding energy and intensity data.Homogeneous reference films are used to relate Si 2pbinding energies with oxygen content of the films. The determination of a mean escape depth for Si 2pphotoelectrons from oxide films provides a relationship between Si 2pline intensities and oxide film thickness. Changes in Si 2pbinding energies and intensity data are used to identify changes in ultrathin oxide film composition as a function of film thickness. Extrapolation of experimental Si 2pbinding energy and intensity data to a film thickness of 2.5 Å provides the composition of a first layer of oxide film. The composition of the silicon oxide transition region and its width are determined by fitting the experimental data to a set of generated theoretical curves. These curves are derived from calculations of the changes in Si 2ρ binding‐energy maxima as a function of the width of a transition region.Ultrathin silicon oxide samples less than 30 Å thick were generally formed onp‐type, 2‐Ω cm silicon substrates with both (100) and (111) orientations, althoughn‐type and 10−3Ω cm silicon and surfaces formed by cleavage were also studied. Oxide films were grown at oxidation temperatures ranging from 23° to 850 °C and with oxidants which included O2, O2+N2, air, and boiling aqueous solutions [concentrated HNO3, H2O2(30%), deionized water].Nonstoichiometric transition regions were identified in all thermally grown ultrathin silicon oxide films. These transition regions were indistinguishable as a function of oxidation conditions, oxidant, or substrate dopant, or type. The transition regions were resolvable from x‐ray photoelectron data only as a function of substrate orientation. Estimates of parameters characterizing ultrathin oxide transition regions are summarized in Table I. It was determined that oxide transition regions, which are approximately 14 Å thick, contain about 1015nonoxidized Si–Si bond cm−2. Ultrathin oxides formed on (100) oriented substrates have narrower, less steeply graded transition regions than do oxides on (111) oriented substrates. The first oxide layer is more completely oxidized in oxides on (100) oriented substrates.

ISSN:0022-5355    

DOI:10.1116/1.568955

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

This paper reports on the optical and electrical properties of thin (t<3000 Å) anodic oxides onp‐type GaSb. The oxides were grown in a 10−1Nsolution of KOH in methanol at constant current. Thin film interference techniques with phase shift and reflectivity corrections are used to determine the thickness, refractive index, and dispersion of the films in the range 2500<λ<8000 Å. MOS structures were prepared and the conductivity, dielectric constant (K=8.5), and breakdown strength (200 V/μm) are determined. At 77 KC–Vcurves show the surface is normally depleted at zero bias. The resultingC–Vcurves are compared with the ideal and a typical density of states of 1.0×1012s/cm−2eV−1is measured.

ISSN:0022-5355    

DOI:10.1116/1.568956

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

The differences between the electrical conductivity of thermal and anodic oxides of InSb have been reported previously. In this paper these differences are correlated with the chemical compositional profiles of the two oxides. The anodic oxide is shown to be an indium oxide containing a large concentration of Sb, while the thermal oxide contains a relatively low concentration of Sb, but has an Sb‐rich layer between the indium oxide and the InSb. By postformation annealing of the anodic oxide or application of a large electric field to the thermal oxide, the oxide compositions are changed. These changes are accompanied by a corresponding change in the electrical conductivity of the oxide. From these data and the changes in the Auger line shape for In, it appears that Sb–In bonding in the oxide is related to the change of conductivity.

ISSN:0022-5355    

DOI:10.1116/1.568958

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

Intermetallic coumpound formation at metal–metal interfaces was observed for thin film couples of Al and transition metals such as Cr, Ti, Hf, Zr, Co, Ta, Pd, and Pt. The Al–Cr system was investigated in some detail using a conductance method and nuclear backscattering for reaction‐rate measurements. The compounds CrAl7and Cr2Al11were identified and their growth was found to be diffusion controlled. The temperature dependence of the rate constant for CrAl7obeyed an Arrhenius plot from 300° to 450 °C with an activation energy of 1.91±0.1 eV. The Al‐rich phases of the remaining transition metals were investigated; the compounds either exhibited a planar interface with parabolic growth kinetics or an irregular interface with nonparabolic growth. An empirical relationship involving the melting point and stability of the compounds was proposed to explain the different growth kinetics.

ISSN:0022-5355    

DOI:10.1116/1.568959

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

The structural, compositional, and electrical properties of rf sputter‐deposited Y2O3‐doped ZrO2films have been investigated as a function of sputtering conditions. The results show that the application of an rf substrate bias during deposition has a large effect on both the morphological and electrical properties of the films. Auger electron spectroscopy, electron diffraction, and scanning‐electron‐fractography results show that films deposited atP=20 mTorr (2.67 Pa),VT=−500 V, andVS=−40 V are nearly stoichiometric, have a cubic crystal structure, and a relatively equiaxed microstructure. The results of electrical measurements indicate that films grown under these sputtering conditions have an ionic transference number which is nearly zero below 100 °C and rises to approximately 0.4 at 200 °C.

ISSN:0022-5355    

DOI:10.1116/1.568960

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

The science of tribology is the study of the interaction of engineering surfaces. Although the name implies interfacial sliding (tribology derives from the Greek word for rubbing), the discipline considers static contact as well. Lubrication to reduce friction and wear has been intimately involved with the empirical development of machinery through the ages. Tribology, therefore, has been basically a ’’catch‐up’’ science; trying to explain physical phenomena which were known phenomenogically for decades. The pervasive concept in all tribology is the elastoplastic interaction at the microscopic irregularities on engineering surfaces. Some of the major advances in tribology in the past ten years have been the definition of engineering surfaces on this microscopic scale and the analysis of the thermo‐mechanical situation which develops when such surfaces are slid against each other under load. This paper identifies the important parameters of mechanical surface interactions on both macro and micro scales in dry contact and under elastohydrodynamic lubrication.

ISSN:0022-5355    

DOI:10.1116/1.568961

出版商:American Vacuum Society    

年代:1976

数据来源: AIP

摘要:

Good adhesion and long durability of the ion‐plated film have provided a wide application of this technique to industry. Tribological applications of the ion‐plating technique reviewed in this paper concern not only the problems of friction, lubrication, and wear, but also mechanical behaviors such as fatigue and tensile strength properties, experiments upon which are conducted in air. Besides improvements on the frictional performance and anti‐wear properties of materials, further applications might include the development of reinforced filament by ion plating that is potentially useful for self‐lubricating composite materials, and an improvement in the fatigue property by ion plating; all these showed good results. Examinations of an ion‐plated film, interface, and substrate were also made using transmission and scanning electron microscopy; discussions of the adhesion and interfacial formation are given. A good adhesion would be caused by the dislocation‐pipe diffusion, since ion bombardment produced lattice defect concentration in the substrate. Several examples of vacuum ion plating at high vacuum of 1.33×10−6Pa are also reported.

ISSN:0022-5355    

DOI:10.1116/1.568962

出版商:American Vacuum Society    

年代:1976

数据来源: AIP