Hydrido-organo-siloxane-polymer (HOSP), a typical silsesquioxane-based low dielectric constant material, was etched with ions of different incident angles in CHF3 plasma. The etch rate normalized to the rate obtained with ions incident perpendicular to the surface deviated from the general cosine dependence on the ion incident angle. That is, the rate deviated to over-cosine values at low ion angles below 70°, due to the physical sputtering of the surface by energetic ions, and to under-cosine values at high angles, above 70°, due to the redeposition of particles emitted from the bottom. The roughness of the etched surface also varied with the ion incident angle as a result of the surface etching by energetic ions and the redeposition of particles emitted from the bottom. For example, when the bias voltage was –100V, the surface roughness was different according to three angle regions: i) ion bombardment dominant region below 70°, ii) intermediate region between 70° and 85o, and iii) redeposition dominant region above 85°. The surface composition and chemical structure after etching were also affected by the ion incident angle. The F/C atomic in the surface layer was much lower at ion angles higher than 70° than below 70° because cage-like Si-O bonds were more rapidly dissociated by F atoms from fluorocarbon polymer layer than network Si-O bonds at high angles. This information obtained in this study is useful for predicting the profile and surface characteristics of interconnection patterns in microelectronics fabrication.

Profile evolution simulations during chemical vapor deposition based on a 2D continuum model reveal that the type of surface kinetics plays an important role in determining step coverage of films deposited in high aspect ratio trenches and vias. Linear surface kinetics, resulting from an adsorption rate limited process, is found to cause difficulty in bringing about conformal step coverage in deep narrow trenches without reducing the growth rate considerably. Under such condition, void-free filling cannot be achieved while maintaining a growth rate acceptable to integrated circuit (IC) manufacturing. The numerical study also suggests that the high tendency of the precursor for chemical equilibrium on a surface, resulting in nonlinear kinetics by a surface reaction limited process, is crucial to achieve a uniform step coverage as typically observed in SiO2 deposition from tetraethylorthosilicate (TEOS).

Thermal decomposition of SiH4, Si2H6, SiF4 and SiH2F2 used as the reactants in the Si-CVD process was studied by monitoring the gaseous products with a quadrupole mass spectrometcr (QMS). The rates of SiH4 pyrolysis showed a large compensation effect at low pressures, which agreed with the theory of unimolecular reaction. Si2H6 decomposed at relatively low temperatures producing SiH4 as the intermediate products. The decomposition temperatures of the other compounds increased in the order of SiH4, SiH2F2 and SiF4. The pyrolysis rates of SiH2F2 and silanes, i.e., SiH4 or Si2H6, were enhanced synergically when they were mixed together. The results were explained by a reaction mechanism proposed based on analysis of the intermediates produced in the process.

For the analysis of as-cleaned surface, we have used a the unique IR method that uses a highsurface-area porous sample. We have observed by experiments that the oxide growth rate on silicon is reduced to a minimum when the surface is treated with a proper amount of HF vapor obtained from 1% I-IF solution. FTIR and XPS observations of the treated surface suggest that the oxide growth rate is closely related to the amount of the surface fluorides. In UV/O2 cleaning process, we have observed experimentally that addition of water vapor to cleaning gas stream enhances the cleaning efficiency by as much as 1.3 times.

Deposition of a thin film in the LPCVD process has been simulated by a Monte–Carlo method based on a simple model taking into account the desorption, the surface reaction, and the surface migration of the film precursor. The model has been used for the simulation of the film profile obtained in a narrow and deep trench and of the film crystallinity on a flat surface. The simulation results describe successfully those obtained by experiments under various process conditions.

Decomposition of Sr(tmhd)2 and Ba(tmhd)2 was investigated by thermogravimetric analysis, in-situ FTIR, and mass spectrometry. Both compounds decomposed following 3 steps: 1) decomposition of the ligands, 2) simultaneous vaporization and partial decomposition of metal-organics, and 3) decomposition of the vaporized metal-organics which existed as the oligomeric species.

The Sr source decomposed at lower temperatures and in a narrower temperature range than the Ba source. Also, the gaseous oligomeric species from the Sr source decomposed relatively quickly while the corresponding species from the Ba source decomposed slowly over a long period. Such a difference between the two compounds is due to different bond energies between the metal atom and the ligands, as indicated by our FTIR results.