On the Surface Structure of a Silicon Monoxide Film
Abstract Generated abstract
This study examines surface defects in evaporated silicon monoxide films, a problem relevant to producing defect-free coatings for microelectronic applications. Films were deposited from a tantalum cylinder onto glass and rock-salt substrates, both with and without an internal ring-disk-ring separator, and were analyzed by optical reflection microscopy and electron microscopy. The observations indicate that macroparticles ejected during evaporation can adhere to or pierce the developing film, leaving pores, while use of a separator reduces the number of visible defects by about a factor of 20 to 25. By varying the separator outlet aperture, the authors identify how the defect cone changes and recommend a 5.5 mm aperture for the stated substrate size and source-to-substrate distance.
Full Text
ON THE SURFACE STRUCTURE OF A SILICON MONOXIDE FILM
A. N. RUDNEV, G. A. EFIMENKO
(Presented by the scientific seminar of the Department of Physical Electronics of the Electrophysical Faculty)
Obtaining a defect-free silicon monoxide film is very important for many purposes of microelectronics.
A silicon monoxide film was evaporated from a tantalum cylinder without a separator and with a separator (of the ring–disk–ring type) inserted inside the cylinder. Deposition was carried out simultaneously on a glass substrate and on a rock-salt cleavage. The condensation rate was approximately \(\sim 13\ \text{Å/sec}\). The film on glass was examined in reflection with an MIM-8 optical microscope; the film on the NaCl cleavage was prepared and viewed with an EM-3 electron microscope. Figures 1 and 2 present
Fig. 1. SiO film deposited without a separator on glass. Magnification \(\times 400\), dark-field image
the corresponding photographs of the surface structure of the film, obtained with the optical microscope, where the bright points are surface defects. Separation reduces the number of defects by approximately a factor of 20–25. To clarify the nature of the defects, an electron-microscopic study of the film was carried out.
At the moment of nucleation, the condensing dielectric film may be regarded as a two-dimensional liquid possessing a certain viscosity [1]. The macroparticles of silicon monoxide powder ejected during evaporation bombard the film. In this process some macroparti-
particles adhere to the film, but sometimes the energy of the macroparticles is sufficient to pierce the film and, after being reflected from the substrate, rebound. At the site of such an impact, a through-hole remains (Fig. 3).
Fig. 2. SiO film deposited with a separator on glass. Magnification ×400, dark-field image.
Further investigations of the surface structure of a silicon monoxide film made it possible to develop an optimal separator design. By varying the diameter of the separator outlet aperture from 2.5 to 6.5 mm (in increments of 1 mm), it was found that the “complete cone of defects” formed by unseparated particles increases its opening angle from 10 to 45°. The recommended diameter of the separator outlet aperture is 5.5 mm for substrate dimensions of 60 × 60 mm and a source–substrate distance of 150 mm.
Fig. 3. SiO film deposited without a separator on a NaCl cleavage. Magnification ×24000. Two pores are visible.
REFERENCES
- Bourg Marel. “Ann. Phys.” 1962, 7, No. 11–12, pp. 623–658.