It is well known that Si surface treatment is crucial for low-temperature Si epitaxy. Although considerable work exists which is aimed at elucidating the effects of Si surface pretreatments on Si epitaxy, little is known about the effects of SiO2 surface pretreatments for polycrystalline silicon (poly-Si) growth. We report on a study of SiO2 surface pretreatment effects on poly-Si nucleation and film surface roughness using a low energy hydrogen ion beam (200 eV) and H2 gas annealing (850 °C) in a rapid thermal chemical vapor deposition system. In situ real-time ellipsometry was used to monitor the surfaces during pretreatment and observe the nucleation. The microstructure and surface roughness of the deposited poly-Si films are determined by analysis of in situ spectroscopic ellipsometry (SE) and atomic force microscopy (AFM) measurements. Hydrogen ion beam pretreatment was found to produce higher nuclei density and a smoother poly-Si surface than nonpretreated substrates, and the opposite was found for hydrogen gas annealing giving lower nuclei density and rougher poly-Si.

The primary purpose of this research was to elucidate the mechanism of Si nucleation on SiO2 in a rapid thermal chemical vapor deposition (RTCVD) environment. To this end a combination of in situ real time ellipsometry and atomic force microscopy (AFM) to follow the RTCVD process in real time and measure key nucleation parameters was used. Real time ellipsometry data, in terms of Δ versus time, show significant changes as the deposition evolves from critical nuclei through coalescence to continuous film growth. From these data nuclei parameters such as the incubation time (tinc), coalescence point, nuclei density, and nuclei size are obtained from nucleation models. From the AFM images, nuclei parameters such as nuclei height, radius, and density were collected and compared across processing temperatures. It was found that kinetics rather than thermodynamics controls nuclei growth, and the mechanism depended upon the temperature regime (pressure not varied) due to the higher activation energy (212 kJ/mol) for vertical growth relative to lateral growth (167 kJ/mol). A transition temperature (∼600 °C) was identified where the size, shape, and density of the nuclei abruptly change from small numerous nuclei at temperatures less than 660 °C to large, sparse, disklike nuclei for temperatures greater than 660 °C. The temperature regime also affected the shape of the nuclei during growth with low temperature nuclei becoming flatter with time as the adatoms attached to the nuclei circumference, whereas high temperature nuclei grew taller with time. It is demonstrated that the RTCVD temperature regime dictates both the initial nuclei size and the nuclei growth mechanism with high temperature processes (i.e., highest adatom mobility), yielding the lowest nuclei density, largest nuclei, and roughest final Si film.

A (silicon) boron nitride deposition process based on diborane and ammonia chemistry has been developed. Stable (silicon) boron nitride films have been obtained and the film properties were characterized. The mechanical resistance of boron nitride films against abrasives is utilized for stop layer applications for chemical mechanical polishing. The effectiveness of stop layers can be enhanced by end point detection systems. Two different systems will be discussed.

Oxygen and tetrafluorocarbon magnetically enhanced reactive ion etching (MERIE) of plasma chemical vapor deposited (CVD) boron nitride (BN) and silicon boron nitride (SiBN) was studied for both blanket and submicron patterned films. The relative etch selectivities of the BN and SiBN to oxide (SiO2) and nitride (SIN) were determined. In general, oxygen-rich Q/CF4 MERIE produce very high etch selectivity results while maintaining vertical etch profiles. This etch process expands the potential for use ol BN/SiBN in fabrication of subhalf micron devices.) unless CC License in place (see abstract). ecsdl.org/site/terms_use address. Redistribution subject to ECS terms of use (see 142.58.129.109 Downloaded on 2015-06-04 to IP