Recently, octahedron structures have been found in the Czochralski-silicon substrate surface layer just under the oxide defects. An attempt is made to characterize these structures by analysis with transmission electron microscopy and energy-dispersive x-ray spectroscopy. Several results indicate that the structure is full of vacancies. This is contrary to previously reported results suggesting that the octahedron structures found in Si bulk are filled with amorphous SiO2. A model for the formation of an octahedron structure with many vacancies is proposed.

Analysis by TEM-energy-dispersive-X-ray-spectroscopy indicates that the majority of the octahedral structure found just under the oxide defect with Czochralski Si is void. This is contrary to previously reported results suggesting that the octahedral structures found in Si bulk are filled with amorphous SiO2. We investigate three models to explain our results. The first model, which we think most probable, suggests that the void formation occurs during Si crystal growth. The second model indicates that octahedral structures full of SiO2 are formed during Si crystal growth and, after wafer slicing, much of the SiO2 is removed. The third model suggests that the void is formed during copper decoration. We show some experimental results that are inconsistent with the second and third models.

Spatial profiles of CF2 concentration in C2 F6 rf plasma are measured by the laser-induced fluorescence method. The observed profiles are explained by the generation and recombination reaction mechanisms of CF2 . It is found that the deposition rate of fluorocarbon polymer on SiO2 film is proportional to [CF2]n ; n=2.5–3.0, whereas the etch rate of SiO2 is proportional to [CF2]. Both the etching and the deposition reactions proceed at the same time. Based on these observations, reaction mechanisms for fluorocarbon polymer deposition and SiO2 etching are analyzed.

Articles you may be interested inAdvanced transfer system for spin coating film transfer and hot-pressing in planarization technology Global planarization technology based on a new concept comprised of spin on glass ͑SOG͒ film transfer and hot pressing is proposed for interlayer dielectrics. The technology basically involves coating a SOG film onto a sheet film in advance and then transferring it from the sheet film to a Si substrate by pressing and heating it in a vacuum. Planarization and filling of the interlayer dielectrics can be carried out by this process. For this technology, perhydrosilazane, which has a high viscosity for a thick formation during coating and a low viscosity for the flow during heating, is used as the SOG material. Experimental results show that the SOG thickness is reduced by the pressing and heating process and that its uniformity can be improved by the press force. By applying this technology to Al interconnection, it is found that planarization and filling can be completely realized. Therefore, this technology is very promising for simple and inexpensive global planarization.

Effects of chelating agent additions to an NH4OH-H202-H20 wet cleaning solution are examined in terms of metallic contamination on Si surfaces. While ethylenediaminetetraacetic acid and other well-known chelating agents have been shown to reduce Fe adsorption onto an Si surface only by one third, adding a phosphonic acid chelating agent at a concentration of only 1 ppm reduces Fe and Ca contamination by more than one order of magnitude and increases dielectric strength of 11 nm thin oxide.