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The formation mechanism and spectroscopic characterization of carbonaceous dust particles obtained by using benzene as the starting material in an rf discharge is discussed. The large particles are formed in benzene plasma by the inclusion of hydrogenated amorphous carbon (HAC) or microcrystalline graphite particles in the particle core while small particles are formed by direct aggregation and condensation of gas-phase polyphenyl molecules.

A different approach is employed to explore plasma propertied by combining an in situ optical emission technique with a contact angle measurement. The plasma excitation and reaction mechanisms for the observed correlation between plasma temperatures and the wettability of the silicon surface is proposed, which shows that small silicon chips can serve as litmus tests for the plasma conditions without introducing too much perturbation.

In this work, an approach has been adopted to explore plasma properties by combining an in situ optical emission technique with a contact angle measurement. Hydrogen plasma was generated with a radio-frequency power source. The plasma parameters such as number densities and temperatures were derived from the optical emission spectroscopic data. Small silicon chips were placed at various positions inside a discharge tube as probes for the plasma conditions. The hydrogen-plasma-treated silicon chip surfaces were characterized with the contact angle measurement method. The change of wettability on the silicon surface was observed with various plasma treatment times. The spectroscopic information about the plasma is correlated with the results of the surface characterization. It is found that the rate of the increasing hydrophilicity is sensitive to the amount of helium added and the location in the discharge tube. A simple model describing the relation between the surface coverage area of water droplet and the variation of contact angle has been established. We have proposed plasma excitation and reaction mechanisms for the observed correlation between plasma temperatures and the wettability of the silicon surface. It shows that small silicon chips can serve as “litmus tests” for the plasma conditions without introducing too much perturbation. [ABSTRACT FROM AUTHOR]

Abstract  A radio frequency (rf) discharge has been utilized to study the decomposition of benzene. SEM inspection has shown that the size of soot particles ranged from 0.5 to several μm. The soot deposited on silicon wafers was analyzed by gas chromatography/mass spectrometry (GC/MS). It was shown that the main components of the soot are polyphenyls (biphenyl and terphenyls) and a trace amount of polycyclic aromatic hydrocarbons (PAHs). Acetylene and hydrogen have been detected by plasma diagnostics techniques using Fourier transform infrared (FTIR) and optical emission spectroscopic techniques. However, GC/MS analysis has shown that the relative yields of PAHs are much less than those of polyphenyls, which indicates that the conventional hydrogen abstraction-acetylene addition (HACA) model for soot formation is not applicable to the benzene plasma due to the reason of temperature. The rf power, the carrier gas flow-rate, the relative yields of polyphenyls, and plasma temperatures were correlated. The reaction pathways of benzene elimination and soot formation in plasma are discussed. This study has provided a new route to control the contamination due to PAHs. [ABSTRACT FROM AUTHOR]

Plasma interactions with chamber components and wafers in semiconductor manufacturing processes have been monitored with a fault detection technique. Not only can this diagnostic technique monitor the wafer and process chamber components qualities, but it also has potential in saving tremendous amounts of manufacturing costs and improving equipment productivity. We have discovered that the abnormality in certain plasma processing parameters detected in the early stages of a manufacturing line can have a strong correlation with the product yield. Possible reasons for the observed correlations are explained. [ABSTRACT FROM AUTHOR]