Noboru Tokumasu

Thermal desorption spectra of SiO2 films deposited on Si and on thermal SiO2 by tetraethylorthosilicate/O3 atmospheric-pressure chemical vapor deposition

SiO2 films deposited on Si and on thermal SiO2 by tetraethylorthosilicate [TEOS, Si(OC2H5)4]/O3 atmospheric-pressure chemical vapor deposition (APCVD) were analyzed by thermal desorption spectra (TDS). The TDS results show that more silanols were incorporated during deposition and more water was absorbed during and after deposition in films deposited on Si substrates than on thermal oxide substrates. The latter result indicates that the elimination of water by-products is not the limiting step in TEOS/O3 APCVD. Based on the former result, a silanol model was proposed for the surface processes. On surfaces with a uniform and high density of silanol sites, or on which silanols readily form under TEOS/O3 APCVD conditions, the active silanol groups in the gas phase contribute to film formation and replenish silanol sites, resulting in continuous, high growth rates. On surfaces with few silanol sites, it is difficult to form silanol sites and the nonsilanol-containing polysiloxanes contribute to film formation...

Low Temperature Chemical Vapor Deposition of High Quality SiO2 Film Using Helicon Plasma Source

Helicon plasma, a new compact high density plasma source, was investigated for chemical vapor deposition (CVD) of dielectric oxide. High quality films having low compressive stress of 1-2 × 10 9 dyne/cm 2 , lower SiOH content with water-blocking capability and a wet HF etch rate comparable to that of thermal oxide were obtained. Sub-half-micron gaps with high aspect ratio were successfully filled by applying a substrate bias. A combination of biased helicon plasma CVD and atmospheric pressure (AP) tetraethyl orthosilicate [TEOS]-O 3 nondoped silicate glass (NSG) which has self-planarizing characteristics is proposed for planarization without chemical-mechanical polish (CMP)

Low-Temperature Atmospheric-Pressure Chemical Vapor Deposition Using 2, 4, 6, 8-Tetramethylcyclotetrasiloxane and Ozone

Tetramethylcyclotetrasiloxane (TMCTS) was studied as a possible silicon source for atmospheric-pressure chemical vapor deposition (CVD) using ozone chemistry. High-quality silicon dioxide films were produced at 400° C with a typical deposition rate of 100 nm/min. During the study, TMCTS was observed to have base material dependent characteristics which varied as a function of both deposition temperature and ozone concentration. The deposition rate vs deposition temperature relationship indicated that the film structure varies slightly as a function of the deposition temperature. Data collected for film shrinkage after annealing supported these structural changes. The typical as-deposited film stress was 2×109 dyn/cm2 (tensile). The step coverage varied from conformal to flow-shaped depending on the deposition temperature and ozone concentration. The results of this study show that TMCTS is a promising precursor for use in intermetal dielectric applications for ultra large-scale integration (ULSI) devices.

Evaluation of Parameters in Atmospheric-Pressure Chemical Vapor Deposition of Borophosphosilicate Glass Using Tetraethylorthosilicate and Ozone

The effective parameters for the atmospheric-pressure chemical vapor deposition (APCVD) of borophosphosilicate glass (BPSG) using tetraethylorthosilicate (TEOS) and ozone were evaluated by designing an experiment. Source efficiencies of the deposition and doping were evaluated at constant boron and phosphorus concentrations. Each parameter was also characterized in terms of uniformity and film properties, such as thermal shrinkage and wet etch rate. Interactions between boron and phosphorus were discussed in terms of the difference in influential parameters and reaction rates. The deposition was controlled by the deposition temperature and the deposition rate, which are the dominant parameters of the film quality and deposition efficiency. The balance between gas flow rate and temperature is important to improve deposition and doping uniformity.

Morphology Evolution of SIO2 Films Deposited by Tetraethylorthosilicate/O3 Atmospheric-Pressure Chemical Vapor Deposition on Thermal SiO2.

To understand the surface dependence of chemical vapor deposition using tetraethylorthosilicate and O3, the evolution of the morphology of 5.3-µm-thick oxide films deposited on thermal oxide was observed by scanning electron microscopy. The surface roughness and low etching resistance of the films was caused by different growth rates at different surface sites. Some sites grow much faster that other sites, evolving from island, to tree, and finally to continuous films. Because of this growth sequence, the film has high porosity and is rough. This growth mode might be caused by site-dependent tetraethylorthosilicate absorption rates.