Effects of oxygen ion implantation on the structure and properties of aluminum thin films

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4420-4426

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I. General engineering 11. GASES

vacuum

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science

4420-4598

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the title of each item denotes country or origin of publication, indicates country of origin of work (where known).

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SOLIDS 11

4420. Effects of oxygen ion implantation on the structure and properties of aluminum thin films. (USA) Aluminum thin films having a nominal thickness of 350 nm were implanted with oxygen ions to integrated dosage of 10”-IO’” atom/ cm’. Structural investigations by X-ray diffraction techniques indicated that ion implantation substantially decreased the particle size, increased the magnitude of microstrains and introduced significant amount of stacking faults. implantation also tended to introduce macroscopic compressive stresses. Both structural and electrical resistivity measurements showed that the ion implanted structure has exceptional thermal stability. Cross-stripe experiments gave direct evidence that oxygen ion implantation decreases the grain boundary diffusivity in aluminum. A Cangulee et al, J Voc Sci ~~clrrwl, 16 (2), 1979, 156-159. II 4421. Resistance stabilization of Ni-Cr films by surface oxide formation. (USA) An investigation has been made of the resistivity and temperature coethcient of resistivity of Ni-Cr thin films deposited under carefully controlled conditions in ultra-high vacuum. Auger depth profiling has been used to monitor the films, quantification of the Auger data being achieved both by the use of bulk alloy standards-and by Rutherford backscatterine. This oaocr deals soeciticallv with the 0 effects of residual gas on the resistance of the film and describes how this may be stabilized by the formation of a surface oxide. After stabilization the films have resistivities and temperature coefficients of resistivity which are indistinguishable from bulk samples of the same composition. Auger data has shown that the skin is predominately chromium oxide with a thickness in the region of two monolayers, this figure being supported by the percentage change of resistance on oxidatton. (GB) G Nocerino and K E Singer, J VNC Sci Tec/~d, 16 (2). 1979, 147-l 50.

II 4422. Induced interface interactions in Ti/Si systems by ion implantation. (USA) Experimental evidence is presented which suggests ion-bombardmentinduced formation of titanium silicide(s) at the interface of ion implanted Ti/Si structures. Titanium films of 1000 to 2000 A were evaporated onto silicon substrates. The structures were implanted with 1 x 10Ls to 2 i: 1Oi7 t*N+ or “B+ ionscm-’ al beam energies 50-190 keV and at fixed temperatures ranging from - 195” to ab&t 25°C. Using Auger electron spectroscopy combined with active ion sputtering, the thickness of the silicide layers was found to vary with implantation temperature, energy, and fluence. Since relatively high temperatures are required for the formation of titanium silicides (-650°C). it is unlikely that the formation is due to sample heating upon implantation. This was confirmed by implanting at different beam fluxes and temperatures. The formation mechanism is most likely one of enhanced diffusion and chemical reaction processes during ionic impact. which competes with the recombination of vacancies and self-interstitials, and other capture processes. This mechanism is supported by data from structures implanted at - 195°C which showed silicide layers being thicker than those observed for room temperature implants under otherwise identical implant conditions. K L Wang et al, J Vuc Sci TCC/I~IO/, 16 (2), 1979, 130-133.

4423. Oxygen chemisorption on Bi (0001): LEED/Auger/loss study. (USA) The (0001) crystal face of Bi and its reaction with oxygen have been studied using LEED, Auger electron spectroscopy, and electron loss measurements. Loss spectra from the clean surface included two peaks from the 5d levels, a 14 eV bulk plasmon loss, and a 6.5 eV loss which like that from a surface plasmon became more pronounced with decrease in incident electron energy. Room-temperature exposure to 10” L of oxygen was necessary before the onset of appreciable chemisorption and the development of overlayer diffraction features. For the oxidized condition, the 5d loss peaks were seen to shift away from the elastic peak while the 6.5 eV loss was replaced by one at 9.3 eV. T N Taylor et al, J Vat Sci T~c/~w/. 16 (2). 1979, 581-583. II 4424. UPS Studies of Hz, 0, and CO adsorption on ordered carbon overlayers on W(100). (USA) An ordered carbon overlayer which is prepared by carburization of a W(lO0) surface and exhibits a (5 :.’ 1) LEED pattern, is used as a model of bulk WC. UPS studies at /IV = 21.2 eV were performed on this surface with adsorbed H,. OZ. or CO. No evidence for HZ adsorption was seen. Oxygen is easily adsorbed and probably bonds in a manner dilferent from oxygen in dissociated CO on W(lO0). CO adsorbs molecularly, as cvidenccd by emission from CO 5o-lr molecular orbitals. P M Stefan et al, J Vat Sci Trchwl, 16 (2). 1979, 577-580.

11 4425. High-resolution LMM Auger spectra from argon implanted in Be and Si. (USA) The L2,.IMI,JM2.3 and L2,Jvf,Mz.., Auger electron spectra from argon implanted by I keV ion bombardment in Be and Si crystals have been obtained using a double-pass CMA operated in both the non-retard and retard modes. Background subtraction and lossdeconvolution were subsequently apphed to obtain the final results. The argon-in-Be spectrum consists of a series of narrow peaks (FWHM less than 2 eV) which are sharper than those previously reported for the L2,J~fI,3ML.3 spectrum from solid argon. Associating the major peak in our spectrum with the L,M,,,M,,,(‘D,) peak in the gas-phase spectrum leads IO an identification in terms of energy separations of our peak structure with the principal peaks of the gas-phase spectrum to within 0.5 eV. We conclude that the transitions responsible for the Auger spectrum can be characterized as quasiatomic. although the multitude of gas-phase satellite peaks is not seen in our results. Peaks in the argon-in-Si spectrum are slightly broader than those in the argon-in-Be spectrum. As a result of screening by the conduction electrons in the host material, our argon Auger emission energies are higher than those in the gas-phase spectrum. D M Zehner and H H Madden, J VW Sci T~c/Iw/, 16 (2). 1979, 562-

565. 11 4426. AES study of the adsorption of Oz. CO, COz, and Hz0 on indium. (USA) The adsorption of various oxygen-containing gases on clean polycrystalline In has been studied. For the In-O, system, the relationship between N(E) areas and dN(E)/dE peak heights for In MNN Auger transition was found IO be linear. At saturation, an oxygenlindium ratio of 3/2 was measured, consistent with the formation of the Low-coverage sticking coefficients were found stable oxide ln20,. for HzO. -2 x 10e5 for CO, and to be -0.014 for OZ. -0.004 -5 .I toe5 for CO,. In each case, chemical shifts and peak distortions in the N(E) and r/N(E)/dE spectra have been measured for the

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