Excimer laser micromachining of TiN films from chromium and copper sacrificial layers

Abstract

This paper presents results on the laser micromachining of TiN films. Machining performance was evaluated in terms of patterning quality and the ability to remove TiN with minimal interference with an underlying sacrificial layer. TiN was arc-deposited onto (100) silicon substrate with chromium (Cr) and copper (Cu) sacrificial layers. Films were also deposited onto bare silicon substrates under the same conditions. These films were analysed for their composition and structure using Rutherford backscattering spectroscopy and x-ray diffraction techniques. Laser micromachining was performed using a KrF excimer laser at 248 nm. The effect of fluence and number of shots on the machined features has been investigated in detail. The patterned features were examined using optical, confocal and scanning electron microscopes. The characteristics observed were analysed and compared in all three sets of samples. The results showed selective removal of TiN films from Cr and Cu sacrificial layers under different conditions. The machining of TiN from (100) silicon showed relatively poor definition of patterned features. The analysis of these results indicated that laser machining of TiN from Cr and Cu layers is best explained using the explosion mechanism of removal.

Laser micromachining of TiN coatings with variable pulse durations and shapes in ns regime

“…However, the direct writing of desired patterns with laser micromachining provides a flexible solution with high machining resolution, flexibility in machined geometries, and reduced lead times between design and production, because the process does not necessarily require dies or masks. The laser micromachining applications of TiN coatings include microdrilling for the enhanced fixation of dental implants [4], surface micromachining of sensors and actuators in MEMS [5], and surface texturing for the improved tribological performance of mechanical components [6], among others. In addition to surface patterning, laser micromachining has also been used to remove TiN layers from cutting tools [7].…”

Investigation of pulse shape characteristics on the laser ablation dynamics of TiN coatings in the ns regime

“…This paper describes a method to investigate the pulse shape characteristics to identify critical points for pulse shape design. Two different techniques were used namely, reflected pulse analysis and digital holography, to identify the ablation characteristics with ns pulses of different durations on TiN ceramic coating, a highly interesting material for mechanical [27], electronical [28], and biomedical [29] applications. For a better comprehension of the pulse characteristics, single pulse ablation conditions were tested, since it generates the simplest block for more complex micromachining processes based on multiple pulses.…”

Evaluation of excimer laser ablation of thin Cr film on glass substrate by analysing acoustic emission

“…* Solid phase explosive removal, caused by a gas pressure build-up at film-substrate interface as a result from substrate vaporization or by thermal-induced stresses. * Two-phase removal, which was characterized by partial vaporization and subsequent liquid expulsion [1][2][3][4].…”