Surface Morphology and Microstructure of Al-O Alloys Grown by ECR Plasma Deposition
- PDF / 2,546,746 Bytes
- 6 Pages / 414.72 x 648 pts Page_size
- 75 Downloads / 217 Views
including ion energy, temperature, and plasma density allows accurate control of film composition and microstructure. In this paper, we will examine the effects of ion energy and deposition temperature on the film microstructure and surface roughness for ECR plasmadeposited AI(O) alloys. EXPERIMENTAL AIOx and A12 0 3 samples were deposited onto Si (100) substrates by electron-beam evaporation of Al in the presence of an 02 plasma generated by a broad-area ECR source; the source operates at 2.45 GHz microwave frequency with the resonance condition created by two electromagnets generating a 875 G magnetic field. Langmuir probe and optical spectroscopy measurements during ECR operation in the pressure range of 2 to 7 x 10-5 Torr indicate that the predominant species in the oxygen plasma are 02+ ions [6]. The A10, and A12 0
3
films were
grown by independently varying the following parameters: Al deposition rate (0.2 to 3.0 nm/sec), applied dc bias (0 to -300 V), 02 flow rate (0.7 to 2.5 sccm), total chamber pressure (2 to 7.5 x 10-5 Torr), microwave power (35 to 150 W), and substrate temperature (100 to 400'C). Deposited films were characterized using Rutherford Backscattering Spectrometry (RBS) in order to determine the composition and thickness of the films, Transmission Electron Microscopy (TEM) to determine the crystallinity and microstructure, and Atomic Force Microscopy (AFM) for measuring the surface roughness. The films in this study ranged in thickness from 100-900 rim. In addition, samples grown under similar conditions were examined using ultra-low load nanoindentation (NANO Instruments Nano-Indenter II®) for the film hardness and elasticity. Nanoindentation measurements were performed on both pure Al and AIOx films, for which three sets of measurements were taken at total penetration depths of 50, 100, and 200 nm. The results indicate a large increase in hardness (3.2 GPa) for the A1Ox film (20 at.% 0) grown at I 00°C over that for the pure Al film (hardness - 0.9 GPa) as a result of the dispersion strengthening [6]. A dramatic decrease in hardness was found [7] for AlOx samples grown at higher temperatures (400'C) and therefore the surface morphology and sample microstructure were examined for samples from these two deposition-temperature regimes. A120 3 FILMS A120 3 films were deposited onto Si (100) substrates without an applied bias and with an applied bias up to -155 V, over the temperature range from 100 to 400'C. RBS indicated that all of these films nominally had a stoichiometric A120 3 composition. TEM results shown in Fig. I c reveal that the sample grown at 400'C with a -140 V bias is polycrystalline y-A120 3 with grains ranging in size from 10 to 40 nm. The use of the substrate bias was crucial in order to obtain a crystalline A120 3 phase at this relatively low temperature. At 130'C with no bias, an amorphous film was produced as shown in Fig. la. Similarly, amorphous films were produced for a deposition temperature of 400 'C without an applied bias, or for deposition temperatures < 250'C wi
Data Loading...
