Excimer laser ablation of aluminum: influence of spot size on ablation rate

Abstract

The dependence of ablation rate of an Al alloy on laser beam spot size (10-150 µm) was investigated using an ArF excimer laser operating at a wavelength of 193 nm and pulse width less than 4 ns. Ablation was conducted in air at a fluence of 11 J cm −2 and at a repetition rate of 20 Hz. Surface morphology and depth of craters produced by a variable number of laser pulses were characterized using optical and scanning electron microscopy. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) was used as an additional diagnostic technique to estimate the amount of material ablated from craters produced by a laser beam of different diameters. Laser beam spot size and number of laser pulses applied to the same spot were found to influence crater morphology, ablation rate, shape and amount of particles deposited at or around the crater rim. Ablation rate was found to be less dependent on spot size for craters greater than 85 µm. A four-fold increase in ablation rate was observed with decreasing crater size from 150 µm to 10 µm.

How the Physicochemical Properties of the Bulk Material Affect the Ablation Crater Profile, Mass Balance, and Bubble Dynamics During Single‐Pulse, Nanosecond Laser Ablation in Water

“…For further discussion, the dependence of the ablation depth on the incident laser fluence was evaluated. Generally, two different ablation regimes are distinguished in ultrashort‐pulsed LAL, characterized by a logarithmic dependence of the ablation depth on the laser fluence [76–79] . At low laser fluences, the ablation rate is determined by the optical penetration depth δ opt (see Equation ).…”

Laser Ablation Plasmas and Spectroscopy for Nuclear Applications

“…The authors further proposed a series of eight steps that commence from the onset of the first laser–matter interaction of ns-lasers up until the formation of the internal and external shockwave and the subsequent vortex rings, which are observed several hundreds of nanoseconds after the end of the laser pulse. 79 The timescale commences with the initial laser coupling onto a small area (10–100 µm diameter) 80 of material where the amount of energy absorbed is determined by the absorption and reflectance coefficients of the ablated material. 81 Thus, for plasma to form, a laser with a moderate to high irradiance ( ∼GW / normalcm 2) must be directly absorbed onto the surface of the material until the energy density exceeds the LA threshold, at which point mass ( ∼pg–ng) is removed and a luminous plasma is formed.…”

Interaction Energy Dependency on Pulse Width in ns NIR Laser Scanning of Silicon

“…Various studies have focused on understanding the mechanisms of laser–matter interactions, both experimentally and theoretically [ 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. The effects of laser pulse width, wavelength, fluence, pulse shape, focus position, and repetition rate on material removal, surface morphology, and ablation rate had been studied for different target materials under different operating conditions [ 2 , 6 , 7 , 11 , 17 , 18 , 19 , 20 , 22 , 25 , 26 , 27 , 28 ]. These parameters were found to have profound effects on the interaction processes that start with the absorption of laser energy and end with the removal of the target material for various applications such as surface texturing, drilling, grooving, cutting, etc.…”

“…Thus, ultrashort-pulse ablation of silicon has attracted much attention for many years. Many studies have focused on the study of the differences between the processes induced by ultrashort (ps or fs) pulses and those generated by long (ns) pulses [ 27 , 59 , 60 , 61 ]. Even within the fs domain, the laser ablation threshold can be very different for different fs pulse duration.…”