摘要:

Experiments on reactive ion etching of plasma enhanced chemical vapor deposition (PECVD) phosphorus‐doped oxide [phosphosilicate glass (PSG)] and thermal oxide films have revealed significant differences which allow highly selective etching of PSG over SiO2. Samples were etched in a diode reactor with a Teflon‐covered cathode in a mixture of CF4and H2, and the proportion of hydrogen was varied over the whole range of 0%–100%. The plasma chemistry is significantly affected as the proportion of hydrogen in the mixture is increased leading to a transition from etching of oxide to deposition of a fluorocarbon film on the oxide surface. This transition occurs near 50% H2under our experimental conditions. In contrast to thermal oxide, PSG films with 7% phosphorus continue to etch in mixtures with as much as 80%–90% H2under the same conditions, and the etch rate is insensitive to the proportion of hydrogen. This effect is most likely due to the presence of phosphorus in the doped oxide film since PECVD borosilicate films etch similarly to thermal oxide. Furthermore, the transition from etching to deposition depends on the phosphorus concentration in the doped film.

ISSN:0734-2101    

DOI:10.1116/1.578726

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

Reactive ion etching (RIE) ofa‐SiC:H thin films in a CCl4/O2plasma has been investigated. The effects of process parameters, in particular radio‐frequency power, oxygen addition, gas flow rate, interelectrode spacing, and pumping speed, ona‐SiC:H etch rate anda‐SiC:H/oxide etch selectivity are reported. For the RIE ofa‐SiC:H in CCl4/O2plasmas, the gas phase plasma chemistry and surface reactions appear to be more important than ion bombardment. Reactive species generated from neutral chemical reactions of oxygen in the discharge play a more dominant role than those generated from the electron impact dissociation processes.

ISSN:0734-2101    

DOI:10.1116/1.578727

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

The influence of moisture on plasma etched polyimide (PI) films is reported. Reactive ion etching plasmas with different CF4/O2ratios (0%–30% CF4) are used to etch metal–polyimide–metal parallel plate capacitors. Plasma etching leads to a geometrical modification of the capacitor structures studied. This results in a reduction of the device capacitance which is modeled using a three‐dimensional Poisson solver (seses). A Debye type dielectric relaxation is observed in O2/CF4plasma treated capacitors when measured at 85% relative humidity. The location of the loss peak is found to be dependent on CF4/O2ratios. Wet capacitors do not exhibit this loss peak prior to etching. The observed relaxation in plasma treated PI capacitors can be removed by reheating to the cure temperature. A Debye model is used to extract a RC equivalent circuit for the etched capacitor structures. In parallel, x‐ray photoelectron spectroscopy (electron spectroscopy for chemical analysis) is used to monitor the chemical changes in PI due to plasma treatment, and the observed chemical and dielectric changes are correlated.

ISSN:0734-2101    

DOI:10.1116/1.578728

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

Time‐resolved optical emission spectroscopy, with a resolution of ≂10 ns, was used to investigate the formation of excited photofragments during pulsed ArF excimer‐laser irradiation of gaseous aluminum bromide. The solid Al2Br6source was maintained at 50 °C and Ar used as a carrier gas to provide an aluminum bromide partial pressure of ≂3×10−6Torr (4×10−4Pa). The total pressure in the reactor was typically 300 mTorr (40 Pa). Following the laser pulse, emission was observed from the Al 4s 2S1/2→3p 2P1/2and 4s 2S1/2→3p 2P3/2transitions at 394 and 396 nm, respectively. The decay of the Al emission intensityIAlwas convoluted with the temporal shape of the excitation pulse since the radiative lifetime of the Al 2Sstate, 6.8 ns, was less than the laser pulse width, ≂20 ns. The rise time ofIAl, on the other hand, was<10 ns, indicating that Al was formed photolytically rather than through subsequent collisions involving photofragments.IAlvaried with the ArF laser intensityIhνasIAl∝I2hνforIhν≲4.5 MW cm−2andIAl∝Ihνat higher laser fluences. Raising the source gas temperature to increase the AlBr3to Al2Br6ratio in the feed gas, at constant total pressure, dramatically increasedIAl.

ISSN:0734-2101    

DOI:10.1116/1.578729

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

Theinsitucleaning of a substrate surface by low‐energy ion bombardment is discussed concentrating on the effect on the quality of sputter‐deposited metal thin films. The removal of carbon from the wafer surface with the addition of H2to Ar plasma atmosphere during theinsitucleaning was confirmed by secondary ion mass spectrometry evaluation. High crystallinity Ti films were obtained by deposition using Ar/H2insitucleaning by low‐energy ion bombardment. By the introduction of the Ar/H2plasmainsitusubstrate surface cleaning, Ti film growth by sputtering was confirmed to improve its crystallinity and its surface smoothness.  

ISSN:0734-2101    

DOI:10.1116/1.578730

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

We describe serial cosputtering of Al/W, Ti/W, and Al/Zr metal alloys. Overcoating Al and Ti targets with the heavier metals Zr and W enhances the partial sputtering yield of the host metals. Computer modeling of sputtering from a bilayer structure using a modifiedt‐dynprogram indicates mixing of the two elements at the interface that takes place because of recoil implantation. In certain cases, such mixing can lead to the enhancement of the partial sputtering yield of the ground‐layer element.    

ISSN:0734-2101    

DOI:10.1116/1.578731

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

Ni(100–1000 nm)/Ti(250 nm) films were prepared by dc planar magnetron sputtering on Si(100) surfaces. Interface structures between Ti and Si and adhesion of the Ti films to Si after different surface pretreatments have been investigated. Before the film deposition, the Si substrate received an Ar ion bombardment or a chemical etching treatment. In the case of the Ar ion bombardment, we have investigated the effect of the cathodic voltage. A low cathodic voltage (50 V) resulted in high adhesion. The results by Rutherford backscattering spectroscopy showed that the amount of Ar incorporated in the Si surface during the Ar ion bombardment is increased with the cathodic voltage. The existence of Ar at the interface between the Si substrate and the Ti–Si mixed layer seems to lower the adhesion. In the case of the chemical pretreatment, we have investigated the effect of the exposure time in the atmosphere after the chemical etching treatment. A shorter exposure time (within 1 h) has been found to be preferred to a longer exposure time. The results of Auger electron spectroscopy and the peeling test showed that the exposure time is related to the oxide thickness, the Ti–Si alloy thickness, and the adhesion. It is considered that the stable SiO2formation prevents the Ti–Si mixed layer formation and lowers the adhesion.  

ISSN:0734-2101    

DOI:10.1116/1.578732

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

It is now widely acknowledged that the stability, performance, and life of prostheses fabricated from metallic materials are directly related to the compositional details of the layers formed on the surfaces of these components at the time of implantation. The thrust of the present investigation is thus the use of angle‐resolved x‐ray photoelectron spectroscopy for the identification of the differences in composition and thickness between the layers formed on the surface of a Ti–6Al–4V alloy specimen following exposure for 1 h to either laboratory air or wet steam.

ISSN:0734-2101    

DOI:10.1116/1.578733

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

The composition of films deposited by dissociating pure tetramethyltin (TMT) or TMT/O2mixtures at 193 nm, was monitored by ‘‘insitu’’ Auger spectroscopy. The presence of C contamination, which was considerable in films obtained from the pure organometallic, was greatly reduced by the occurrence of oxidation and carbon‐free films were achieved when the gas phase concentration of TMT was sufficiently small. The dependence of the O/Sn Auger electron spectroscopy peak‐to‐peak height ratio on thep(O2)/p(TMT) ratio in the precursor mixture showed a saturation for large concentration of oxygen. The surface properties of the tin oxide films were investigated by synchrotron radiation ultraviolet photoemission spectroscopy (UPS). To this aim samples were transferred to a synchrotron radiation facility, without any exposure to air and kept in dynamical high vacuum. The UPS demonstrated that the films were essentially made of SnO2: in fact the valence band exhibited the typical features of SnO2and the analysis of the 4dSn core levels demonstrated that all metal atoms were oxidized, since no contribution to the peak shape due to metallic tin was found. A weak emission from the band gap region indicated the presence of oxygen vacancies.

ISSN:0734-2101    

DOI:10.1116/1.578734

出版商:American Vacuum Society    

年代:1993

数据来源: AIP

摘要:

A comparison between the electronic structure of the alloy Al0.5Ga0.5As and that of the superlattice [(AlAs)2/(GaAs)2]10as determined by angle‐resolved photoelectron spectroscopy is presented. Experimental data have been acquired and interpreted according to identical methodologies for the two materials. A mini band gap observed in the superlattice due to the artificially induced periodicity in the growth direction is not present in the alloy. This suggests that the alloy as grown, exhibits no evidence of self‐induced long range order. The critical point energyX3vof the alloy is found to lie closer to the value for AlAs than that for GaAs, in agreement with a nonlinear interpolation scheme, and to be higher than the Γ̄4v(X3v) point of the superlattice.

ISSN:0734-2101    

DOI:10.1116/1.578735

出版商:American Vacuum Society    

年代:1993

数据来源: AIP