Highly Volatile, Low Melting, Fluorine-Free Precursors for Metal-Organic Chemical Vapor Deposition of Lanthanide Oxide-Containing Thin Films
✍ Scribed by John A. Belot; Anchuan Wang; Richard J. McNeely; Louise Liable-Sands; Arnold L. Rheingold; Tobin J. Marks
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 369 KB
- Volume
- 5
- Category
- Article
- ISSN
- 0948-1907
No coin nor oath required. For personal study only.
✦ Synopsis
cm 3 in comparison to 1.8 g/cm 3 obtained for SiBCN 3 synthesized by polymer pyrolysis. High hardness values up to 22 GPa are found, which might be further increased by reducing the residual hydrogen content by applying higher bias potentials or by reduced precursor flow.
Experimental
The experiments were carried out in the parallel plate plasma reactor described in [20]. A 13.56 MHz RF transmitter (ENI ACG 5) and a corresponding matching unit were used. Si(100) wafers served as substrates for the deposition of the (Si)BCN films. Prior to deposition the substrates were sputtered by an Ar plasma (30 min at 50 Pa and 2.0 W/cm 2 ) and heated up to 250 C for cleaning and improvement of adhesion.
The liquid precursor tris(dimethylamino)silylamino-bis(dimethylamino)borane (TDADB) was vaporized outside the vessel by heating up to 100 C and was fed together with the carrier gas (Ar or N 2 ) into the plasma chamber. The precursor is described in detail in [19]. Constant pressure, substrate temperature, carrier gas flow, and precursor flow of 50 Pa, 250 C, 100 sccm, and 2 sccm, respectively were used throughout the experiments.
The (Si)B x C y N z films were characterized by thickness using atomic force microscopy (PSI Autoprobe CP) and by density calculated from the volume of the film and the mass increase of the substrate (Tables 1 and2). Depth profile analyses of the chemical composition were performed by Auger electron spectroscopy (PHI 545 C) with 5 keV Ar sputtering. X-ray photoelectron spectroscopy (Kratos Axis Ultra) with monochromatic Al Ka radiation was used to determine chemical composition and type of chemical bonds by 5 keV Ar sputtering. X-ray diffraction spectroscopy (Siemens D 5000) was employed to prove that all films were X-ray amorphous.
Fourier transform infrared (FTIR) spectroscopy were carried out using a Perkin-Elmer FTIR spectrometer Spectrum 1000. Both transmission and reflection spectra were investigated in the wavenumber range 400±4000 cm ±1 . For transmission analyses the films were partly scratched off by a Si 3 N 4 cutting tool and mixed and pressed with KBr. The reflectivity spectra of the films on Si wafers were performed at near normal incidence, whereby interference fringes overlap the spectra, complicating their evaluation. Therefore, these spectra serve for comparison.
The hardness and elastic (Young's) modulus were obtained by means of a microhardness indenter (Shimadzu DUH 202). The measurement and the evaluation from the initial unloading stiffness were carried out as described in [31,32]. A load of 10 mN (10 s holding time) was used and at least 8 measurements were recorded per sample. From the indentation depth at maximum load (d max ) and the residual indentation depth (d res ) the elastic recovery was determined using the formula (d max -d res )/d max [33]. The Young's modulus of one film was also measured for comparison by laser-induced surface acoustic waves (SAWs) [34].