Search

The surface charging effect of positive ions at the trench bottom during the etching of dielectric materials has become a severe problem with the shrinkage of electronic feature dimensions. Pulsed plasmas have been widely used to overcome surface charging issues during plasma etching in industry. In this work, synchronized dual-level radio frequency pulsed modulation on capacitively coupled plasmas is investigated based on 1D3V particle-in-cell/Monte Carlo collision simulations. It is found that the plasma always remains a certain initial density during the dual-level pulse modulation, as the high frequency (HF) source still presents during pulse off time (with a reduced voltage amplitude), which may facilitate high processing efficiency. Meanwhile, many HF sheath oscillations are simulated at the initial stage of a pulse period, which induces vast high energy electrons to strike the electrode. When the HF voltage is maintained at a very low value during the pulse off (i.e. 0.1 V HF ), more electrons with higher energy bombard the bottom of the trench, effectively alleviating the charging effect. Furthermore, the nonlinear behavior of sheath oscillations is proved to be very sensitive to dual-frequency voltage amplitudes and pulse ramp-up times. [ABSTRACT FROM AUTHOR]

A statistical design of experiment (DOE) was used to investigate the effects of medium frequency pulsed substrate bias voltage, pulse frequency and pulse width on 150 nm sputtered C coatings doped with Cr. Within the scope of this work, the DOE treatment of nanoindentation/nanoscratch, atomic force microscopy and x-ray photoelectron spectroscopy results were shown to be a successful method for investigating and potentially optimizing very thin sputter ion plated coatings. Bias voltage was shown to be the most significant of the three bias factors for mechanical properties. Bias frequency and pulse width showed effects that partly matched the voltage results and this was discussed with regard to an increase in peak voltage accompanying an increase in frequency and pulse width. For surface topography, the results were more complicated with the significance of each parameter varying according to the property measured. This work also demonstrated the complex inter-relationships that exist between the three bias parameters, meaning that any attempt to optimize the pulse bias condition for a given coating property would require a consideration of all three factors (within the available operating window of the pulse unit). [ABSTRACT FROM AUTHOR]

Plasma polymerized SiOx barrier films were investigated by means of in situ spectroscopic and electrochemical methods to correlate the process parameters such as applied substrate bias with the resulting barrier properties. SiOx layers with various hexamethyldisiloxane/oxygen ratio were deposited with and without applied substrate bias. The resulting film morphologies were characterized by means of atomic force microscopy, and the presence of nanopores was analysed by cyclic voltammetry. In order to compare the film density and the presence of nanopore structure, evaluation of interfacial hydroxyl groups was performed by means of discrete polarization modulation Fourier transform infrared reflection-absorption spectroscopy in atmospheres with controlled partial pressures of H2O or D2O. It could be shown that the electrochemical and in situ spectroscopic approach allows for the analysis of nanopores and that a clear correlation of process parameters and film structure can be established. [ABSTRACT FROM AUTHOR]

Power-modulated (pulsed) plasmas have demonstrated several advantages compared to continuous wave (CW) plasmas. Specifically, pulsed plasmas can result in a higher etching rate, better uniformity, and less structural, electrical or radiation (e.g. vacuum ultraviolet) damage. Pulsed plasmas can also ameliorate unwanted artefacts in etched micro-features such as notching, bowing, micro-trenching and aspect ratio dependent etching. As such, pulsed plasmas may be indispensable in etching of the next generation of micro-devices with a characteristic feature size in the sub-10 nm regime. This work provides an overview of principles and applications of pulsed plasmas in both electropositive (e.g. argon) and electronegative (e.g. chlorine) gases. The effect of pulsing the plasma source power (source pulsing), the electrode bias power (bias pulsing), or both source and bias power (synchronous pulsing), on the time evolution of species densities, electron energy distribution function and ion energy and angular distributions on the substrate is discussed. The resulting pulsed plasma process output (etching rate, uniformity, damage, etc) is compared, whenever possible, to that of CW plasma, under otherwise the same or similar conditions. [ABSTRACT FROM AUTHOR]

As a variation of high power pulsed magnetron sputtering technique, modulated pulsed power (MPP) magnetron sputtering has shown the capability of maintaining a good deposition rate while achieving a high degree of ionization of the sputtered material with low ion energies. It is critical to usefully utilize the negative substrate bias voltage (Vb) to attract these ions towards the substrate to enhance the ion bombardment on growing films by controlling the kinetic energy and the behaviours of ions and electrons arriving on growing films. In this study, CrN thin films have been deposited by MPP in a closed field unbalanced magnetron sputtering system at different Vb varied from 0 to [?]150 V. The peak and mean substrate ion current densities were measured during the depositions as a function of Vb. The films were annealed at 450 degC in Ar for 1 hr in an effort to release the defects and residual stress in the as-deposited films. The structure and properties of as-deposited and annealed films were characterized by electron probe micro-analysis, x-ray diffraction, scanning electron microscopy, transmission electron microscopy, nanoindentation, and ball-on-disc wear test. An increase in the Cr/N ratio of the film was observed as the Vb was increased negatively to above [?]70 V, which resulted in the formation of the hexagonal Cr2N film at Vb = [?]150 V. A preferred (3 1 1) texture was observed in the CrN films deposited as Vb increased from [?]50 V to [?]100 V. The residual stress of the films increased as the Vb was increased from 0 to [?]100 V and then decreased with further increasing the Vb. The increase in the Vb led to grain refinement and an increase in the hardness of the films, but the wear resistance of the films decreased rapidly as the Vb was increased to [?]150 V. [ABSTRACT FROM AUTHOR]