Precision micromachining of CVD diamond films

Abstract

Abstract The laser ablation technique has been extensively recognized to be a unique method for the micromachining and designing of micro components. Chemical vapor deposited (CVD) diamond films have been processed by various types of pulsed lasers for this purpose. Nanosecond pulsed excimer lasers, and recently femtosecond pulsed lasers have been used for the micromachining of diamond films. Even though the interaction between the laser and the material is limited to the nanosecond to femtosecond range, plasma, induced by ablative material ejection, extends to tens of microseconds. Formation and expansion of the plasma give rise to thermal damage, material ejection and re-deposition, resulting in spoiled interfaces, recast layers, and rippled surfaces. The plasma generated thermal damage has been a major obstruction to micron and submicron micromachining of diamond films. To implement the laser ablation technique to the level of precision, a systematic investigation is required on the plasma interaction. This investigation is mainly focused on a novel approach to compensate for the deleterious plasma–diamond interaction. CVD diamond films were subject to various processing environments, such as atmospheric condition, vacuum condition and gas stream condition. Observed damage depends on behavior of the plasma in the different processing environments. In the gas stream condition, it has been clearly shown that proper dissipation of the high-temperature plasma leads to precisely irradiated surfaces, which are almost free from thermal damage. An emphasis of this research is to achieve maximum dissipation of the high-temperature plasma and proper quenching of the target surface. Based on a nanosecond pulsed excimer laser, technical and fundamental investigations for the precision micromachining are performed. Further investigations of the properties of the laser-irradiated films are also currently in progress, including investigations of laser-induced stress, surface morphologies, surface free energy and electronic properties.