Fluorinated Oxide Films Research Articles

Growth and properties of fluorinated plasma oxide for Si MOSFET devices

Plasma oxidation is a potentially attractive technique for growth of silicon dioxide at low temperatures for Si MOSFET devices and for thin film transistor (TFT) devices. It avoids the use of H containing materials as precursors and therefore, can be more stable. In this paper, we report on the growth, electronic properties and stability of plasma oxidized SiO2 films grown in an electron cyclotron (ECR) plasma reactor. The films were grown using either oxygen or oxygen with small amount of fluorine. We show that negative ions play a major role in the growth of oxide films. MOSFET devices that use films grown using plasma oxidation with oxygen alone show higher interface defect densities and much poorer stability than films grown using dry thermal oxides. When fluorine is added to oxygen, the plasma oxidized films grow at a higher rate and the interface density is reduced to the range typical of dry thermal oxides. The MOSFET devices made using the fluorinated oxide films grown at low temperatures perform as well and are almost as stable against hot electron degradation as devices grown using dry thermal oxide at much higher temperatures.

Ion Beam Techniques for Low K Materials Characterization

ABSTRACTIon beam analysis techniques have become very useful for characterization of low k materials. Studies on several ion beam analysis techniques will be discussed. Rutherford Backscattering Spectrometry (RBS) provides a very powerful analytical technique for the thickness and porosity measurements on porous Si0 2 films. Nuclear Reaction Analysis (NRA) techniques for hydrogen and fluorine profiling are very useful to characterize fluorinated polymer and fluorinated oxide films. Examples of low k materials including Si02:F, Parylene-AF and Teflon-AF will be discussed. Fluorine diffusion in to metals and various interface effects between metal and low k materials will be presented.

Characterization of fluorinated tetra ethyl ortho silicate oxide films deposited in a low pressure plasma enhanced chemical vapor deposition reactor

Fluorinated silicon dioxide films were deposited in a commercial plasma enhanced chemical vapor deposition reactor using tetra ethyl ortho silicate (TEOS), oxygen, and C2F6. The depositions were carried out using dual rf frequency power at low pressure, 500–750 mTorr. Film properties were investigated as a function of rf power, pressure, gas flows, and wafer temperature. Fluorine content, refractive index, stress, and deposition rate are among the film properties studied. Special attention was paid to the stability of these properties in air, in boiling water, and after subsequent annealing. The base line TEOS process is unusual in that high compressive stress values can be achieved, up to about 300 MPa. It was thought that this high initial stress would lead to improved stability at higher fluorine concentration. Film stress was found to be quite compressive, even at high fluorine concentration. Good film stability was observed for fluorine concentrations up to 10% (Si–F/Si–O peak ratio). Refractive indices as low as 1.40 were measured. This work demonstrates that a stable, production-quality, fluorinated oxide film can be deposited in this reactor.

Leakage Performance and Breakdown Mechanism of Silicon‐Rich Oxide and Fluorinated Oxide Prepared by Electron Cyclotron Resonance Chemical Vapor Deposition

The characteristics of silicon‐rich oxide and fluorinated oxide films deposited in an electron cyclotron resonance chemical vapor deposition system with and as the oxide sources and as the fluorinating precursor are investigated in this work. According to experimental results, the dangling bonds in Si‐rich oxide behave as positively by charged electron traps and degrade the dielectric strength by lowering the barrier height for Fowler‐Nordheim tunneling. On the other hand, a small amount of incorporated F atoms will passivate and neutralize these excess Si dangling bonds, thereby elevating the dielectric strength. However, too much incorporated F will degrade the pretunneling leakage performance owing to the porosity and fatigues structure in film. The high leakage and even breakdown at low field strongly limits the incorporated F concentration in film and the lowering of dielectric constant.

Effect of fluorine concentration on the etch characteristics of fluorinated tetraethylorthosilicate films

Fluorinated silicon dioxide films have generated much interest as potential low dielectric constant materials for use in back end interconnect technologies in microelectronics manufacturing. A recent article from this group reported on the reliability and stability of fluorinated oxide films. These films were prepared in a conventional parallel plate dual frequency plasma-enhanced chemical-vapor deposition reactor. The concentration of the fluorine in the film was varied by changing the deposition parameters. The highest fluorine concentration obtained was 15% in that study. The fluorine included in the film is expected to affect the results obtained during plasma etch of the film. The effect of the incorporated fluorine on the etch rate of the film and microloading and the profile of contact structures are examined.

Low Dielectric Constant Fluorinated Oxide Films Prepared by Remote Plasma Chemical Vapor Deposition

Low dielectric constant fluorinated oxide (SiOF) films were deposited using SiF4/SiH4/O2 mixtures by remote plasma chemical vapor deposition (RPCVD). The refractive index and relative dielectric constant decrease with increasing SiF4/SiH4 ratio. The fluorine content in the SiOF film observed by X-ray photoelectron spectroscopy increases with SiF4/SiH4 ratio. With increase of fluorine content in the SiOF film, the peak position of the Si-O stretching mode shifts to a higher wave number and the relative dielectric constant decreases. The SiOF film, deposited with SiF4/SiH4 mixture ([SiF4]/[SiH4]=40), exhibited an F content of 12 at.% and a relative dielectric constant of 3.38.

SiO2 Film Stress—Thickness Dependence, Non‐Planar Oxidation, and Fluorine‐Related Effects

The thickness dependence of oxide stress for dry and fluorinated oxide films grown by enhanced thermal oxidation was investigated. A small variation of stress with thickness was observed. Non‐planar structures were oxidized and rounder corner structures were found to result in the case of fluorinated oxidation. Furthermore, pronounced oxide stress differences were observed for samples grown using two distinct fluorinated oxidation procedures and were ascribed to different fluorine profiles in the oxides.