摘要:

The etching of CHF3plasma polymer in fluorine containing electrical discharges was studied. The fluorine sources were SF6, CF4, and mixtures of the two. For discharges in SF6and mixtures of SF6and CF4, a good correlation was obtained between the etch rate and the atomic fluorine concentration measured using actinometry. For CF4, the etch rate was found to be much higher than that predicted from this correlation. This is attributed to the energetic ion bombardment of the polymer surface in the CF4discharge. X‐ray photoelectron spectroscopy analysis of the etched polymer surface shows an increased fluorine content, but the F:C ratio was independent of the etching conditions. The implications of the results for the kinetics of fluorocarbon plasma polymerization are discussed.

ISSN:0734-211X    

DOI:10.1116/1.585784

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

It is now generally accepted that the frequency ω/2π at which a high frequency (hf) discharge is sustained has considerable influence on the properties of the plasma. For example, the electron density obtained for a given hf power density deposited into the plasma is usually higher at microwave than at radio frequencies (rfs). This paper reviews a series of experiments at the Université de Montréal designed to investigate the influence of ω on the power balance between the hf field and the plasma, and the plasma processing of materials. For the two particular etching and deposition processes which are described here, the ‘‘optimum’’ frequency (at which the process is most efficient) appears to be in the range between 50 and 100 MHz. This suggests that converting a plasma process from 13.56 to 2450 MHz does not necessarily lead to the greatest possible process enhancement, and that optimization may require the plasma reactor to be constructed in such a way as to allow the excitation frequency to be changed. To provide insight into these results, the most recent models dealing with the influence of ω on the electron energy distribution are reviewed and extended to calculate parameters that can be compared with our experimental data.

ISSN:0734-211X    

DOI:10.1116/1.585795

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Experimental details and results are presented for a permanent magnet electron cyclotron resonance plasma source matched to a multipolar confined process chamber. A Nd–Fe–B magnet structure provides a resonant axial magnetic field with no electrical or cooling input power, replacing the more typical current driven coils. Plasma parameter and etch characterization measurements in Ar and SF6are presented for the pressure range 0.1–1.0 mTorr and input microwave power levels 100–500 W.

ISSN:0734-211X    

DOI:10.1116/1.585785

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

A multipolar confined electron cyclotron resonance discharge has been characterized by plasma parameter and etch measurements in Ar and SF6. Positive ion densities of 1011cm−3or greater are obtained at pressures of 0.1–1.0 mTorr with 400–600 W input microwave power. The positive ion current density uniformity across a 16 cm diam is ±4% at 1.0 mTorr. Silicon etch rates of 0.25–1.25 μm/min are obtained with 0.1–1.0 mTorr of SF6, with −60 V substrate bias.

ISSN:0734-211X    

DOI:10.1116/1.585786

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

For selective etching of SiO2on silicon, gases or gas mixtures containing hydrogen are often used. Hydrogen from the glow discharge promotes the formation of a thin film polymer layer responsible for the selectivity of the etching process. The reactive ion etch (RIE) process is known to create damage in the silicon substrate. The influence of hydrogen on the damage and deactivation of dopants is investigated in the present work. The distribution of hydrogen in silicon, after different etching and annealing conditions have been studied. The influence of the RIE process on the charge carrier concentration in silicon has been investigated. Various analytical techniques like contact resistivity measurements, four point probe measurements, and Hall measurements have been used to determine the influence of the RIE process on the electrical properties of processed silicon wafers. The hydrogen profile in as‐etched and post annealed wafers was determined by the1H(15N,αγ)12C nuclear reaction. The depth of the deactivated surface layer is discussed in terms of the impinging hydrogen ion energy, i.e., the possibility of H+ions to pick up an energy equal to the peak‐to‐peak voltage of the rf signal.

ISSN:0734-211X    

DOI:10.1116/1.585787

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Differential reflectance (DR) spectroscopy has recently been reported to be effective in measuring the damage imparted to a Si surface by ion beams. Spectroscopic ellipsometry (SE) has been used extensively for this measurement. The present study compares DR and SE, ‘‘head‐to‐head,’’ from both high energy ion implanted samples (60–180 keV) and low energy (0.1–1.5 keV) ion exposures. In most cases DR and SE yield the same information, but SE has a greater analytical capability at the present time. DR is shown to be quite useful for buried layers and being simpler in terms of hardware requirements, perhaps more suitable for process monitoring.

ISSN:0734-211X    

DOI:10.1116/1.585788

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Dielectric behavior of SiO2films fabricated by microwave electron cyclotron resonance (ECR) plasmas under high‐electric stresses has been studied on the basis of the current–voltage (I–V) characteristics, the capacitance–voltage (C–V) characteristics, and the effects of the ramp rate as functions of film thickness. In the region from the current at the onset of Fowler–Norheim (FN) injection to the current at the onset of trapped space charge effects, theI–Vcharacteristics follow closely the FN relation, implying that at least in this region the motion of the electrons is controlled by their interaction with the lattice rather than by their interaction with traps in the forbidden gap. The width of this current region increases with increasing film thickness for a given ramp rate of applied field indicating that the injected electrons may travel quite a distance before being effectively trapped. This also implies that the effects of this trapped space charge on the reduction of the field at the cathode and hence the injecting current become important at a lower field for thinner films. There is no evidence of electron impact ionization taking place prior to dielectric breakdown. After the onset of FN injection,the current density in the leading filament could reach a value as high as 10 A/cm2at the breakdown field, which could therefore cause thermal instability in the filament. Dielectric breakdown may be initiated by thermal destruction and followed by impact ionization leading to a sharp increase in current at the breakdown field.

ISSN:0734-211X    

DOI:10.1116/1.585789

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Hillocks, small outgrowths on a film surface, form when compressional stresses in an aluminum film are relaxed at elevated temperature (≥90 °C), for instance during the phase of rising temperature in an annealing cycle. This paper reports a study of hillock formation in Al films of thicknesses in the interval 0.25–2.2 μm and which have been deposited by electron beam evaporation. Hillock sizes, shapes, number and formation temperatures were determined, the latter on a heating stageinsituin a scanning electron microscope. The internal structure of the hillocks was studied by cross‐sectional transmission electron microscopy technique. These studies provided strong support for the idea that hillocks are formed by migration of material along grain boundaries, presumably at triple junctions, up to the surface where it is deposited in a growing hillock. Initially, the hillocks are separated from the original film surface by a grain boundary‐like interface, but prolonged annealing will cause underlaying grains to grow into the hillocks, until they become integrated in the film.

ISSN:0734-211X    

DOI:10.1116/1.585790

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

Highly oriented films of the semiconducting transition metal silicide, CrSi2, were grown on (111) silicon substrates, with the matching crystallographic faces being CrSi2(001)/Si(111). Reflection high‐energy electron diffraction (RHEED) yielded symmetric patterns of sharp streaks. The expected streak spacings for different incident RHEED beam directions were calculated from the reciprocal net of the CrSi2(001) face and shown to match the observed spacings. The predominant azimuthal orientation of the films was thus determined to be CrSi2〈210〉∥Si〈110〉. This highly desirable heteroepitaxial relationship may be described with a common unit mesh of 51 Å2and a mismatch of −0.3%. RHEED also revealed the presence of limited film regions of a competing azimuthal orientation, CrSi2〈110〉∥Si〈110〉. A new common unit mesh for this competing orientation is suggested; it possesses an area of 612 Å2and a mismatch of −1.2%.

ISSN:0734-211X    

DOI:10.1116/1.585791

出版商:American Vacuum Society    

年代:1991

数据来源: AIP

摘要:

TiW barrier properties have been investigated by electrical testing of shallow CoSi2junctions. Rutherford backscattering and Auger analyses have been used to study Al(0.5% Cu)/TiW/CoSi2/Si structure. Based on the electrical data, it was demonstrated that 900 Å of TiW will serve as a good diffusion barrier up to 475 °C/30 min. The junctions failed at 450 °C when TiW thickness was reduced to 450 Å. The electrical data show the stress of TiW film does not show any significant effects on its properties. Furthermore, shallower junctions (i.e.,p+n) are more vulnerable to barrier failure.

ISSN:0734-211X    

DOI:10.1116/1.585792

出版商:American Vacuum Society    

年代:1991

数据来源: AIP