Laser-enhanced Chemical Etching Research Articles

Controllable high-throughput high-quality femtosecond laser-enhanced chemical etching by temporal pulse shaping based on electron density control.

We developed an efficient fabrication method of high-quality concave microarrays on fused silica substrates based on temporal shaping of femtosecond (fs) laser pulses. This method involves exposures of fs laser pulse trains followed by a wet etching process. Compared with conventional single pulses with the same processing parameters, the temporally shaped fs pulses can enhance the etch rate by a factor of 37 times with better controllability and higher quality. Moreover, we demonstrated the flexibility of the proposed method in tuning the profile of the concave microarray structures by changing the laser pulse delay, laser fluence, and pulse energy distribution ratio. Micro-Raman spectroscopy was conducted to elucidate the stronger modification induced by the fs laser pulse trains in comparison with the single pulses. Our calculations show that the controllability is due to the effective control of localized transient free electron densities by temporally shaping the fs pulses.

Sharpening Conical Tungsten Nanotips in KOH Solution under Laser Irradiation

Laser-enhanced chemical etching with a 532 nm neodymium-doped yttrium aluminum garnet pulsed laser in KOH solution was used for sharpening conical tungsten nanotips which were prefabricated with a conventional electrochemical etch. The laser irradiation was incident axially on the tip apex. Due to different light absorption mechanisms by objectives in different sizes, the laser irradiation generates a controllable temperature gradient profile from the tip apex to the tip base. In the KOH solution, the etching rate varies with the temperature profile along the tip axis. The tip apex radius was greatly reduced, with the shape and aspect ratio in good control.

ChemInform Abstract: Nanosecond Excimer Laser‐Enhanced Chemical Etching

Abstract The use of lasers in etching and deposition processes has been studied extensively, especially during the last decade. Progress in the understanding of the mechanisms of pulsed laser-enhanced chemical etching is largely of recent data. An overview of the mechanisms of laser-enhanced etching is given and discussed. Experimental results of the excimer laser-enhanced chemical etching of copper and silicon in a low-pressure chlorine environment are emphasized. In particular the measured detection angle and time-of-flight distributions are discussed. Calculations of the effects of post-desorption collisions between the etch products on the measurement of the kinetic energy of the etch products are presented and used to explain the experimental results. It is shown that both the laser-driven diffusion of chlorine into copper and the dependence of etch behaviour on surface coverage are effects which have to be taken into account in the description of the etch mechanism.

Nanosecond excimer laser-enhanced chemical etching

The use of lasers in etching and deposition processes has been studied extensively, especially during the last decade. Progress in the understanding of the mechanisms of pulsed laser-enhanced chemical etching is largely of recent data. An overview of the mechanisms of laser-enhanced etching is given and discussed. Experimental results of the excimer laser-enhanced chemical etching of copper and silicon in a low-pressure chlorine environment are emphasized. In particular the measured detection angle and time-of-flight distributions are discussed. Calculations of the effects of post-desorption collisions between the etch products on the measurement of the kinetic energy of the etch products are presented and used to explain the experimental results. It is shown that both the laser-driven diffusion of chlorine into copper and the dependence of etch behaviour on surface coverage are effects which have to be taken into account in the description of the etch mechanism.

Detection and Application of Acoustic Emission in Laser-Enhanced Chemical Etching

Automatic laser focus adjustment and nondestructive flaw detection on a ceramic surface, as well as monitoring of the laser machining process have been successfully carried out using a system to detect, process and feed back the photoacoustic (PA) signal emitted from the laser irradiated work point during the laser-induced chemical solution etching of ceramics such as PbTiO3, PZT and Mn–Zn ferrite.

Machining of PZT, PT and (Mn, Zn)Fe2O4 Ceramics by Laser-Induced Chemical Etching

Laser-enhanced chemical etching of PbTiO3, PZT and (Mn–Zn)-ferrite ceramics is reported. The KOH solution of 10 mol/1 is suitable for the laser enhanced inter-granular etching of the PbTiO3 and PZT with depth etching rate higher than 100 µm/s in the initial laser irradiation period of Ar+ laser of 1 W. The KOH and NaOH solutions are also suitable for the intergranular etching of (Mn–Zn)-ferrite. The H3PO4 solution of 6 mol/1 is suitable for the laser enhanced trans-granular etching of (Mn–Zn)-ferrite with the depth etching rate of about 10 µm/s in the initial irradiation period of an Ar+ laser of 1 W.

Laser Micromachining of a Modified PbTiO3 Ceramics in KOH Water Solution

The Ar+ laser-enhanced chemical etching of a modified PbTiO3 ceramics is studied. It is shown that 10 mol/lKOH water solution is the best etchant for the ceramics, giving excellent appearances and edge definitions for hole and slot machining. The depth etch rate is as high as 150 µm/s for the hole machining in the first one second irradiation at 1 W output at 514.5 nm wavelength. It is postulated the main etching mechanism is not direct melting, dissolving or vaporizing of the ceramics but removing of the ceramic grains one after another.

Laser-enhanced chemical etching of solid surfaces : T. J. Chuang. IBM Jl Res. Dev.26 (2), 145 (1982)

Laser-enhanced chemical etching of solid surfaces : T. J. Chuang. IBM Jl Res. Dev.26 (2), 145 (1982)

Laser-Enhanced Chemical Etching of Solid Surfaces

The laser-enhanced chemical etching of Si, SiO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> , Ta, and Te films with halogen-containing gases excited by a pulsed CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> laser and a continuous-wave (cw) Ar <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> laser has been studied. Detailed measurements of the etch rates as functions of the laser frequency, the laser intensity, and the gas pressure have been performed for some of the gas-solid systems. The enhanced surface reactions have been classified into three categories: those activated by the vibrational excitation of the etchant molecules, those with radicals generated by photodissociation, and those induced by laser excitation of solid substrates. Examples which illustrate the effects of laser radiation on these surface photochemical processes are given. Achievable etch rates and spatial resolutions for the various reaction mechanisms are also examined.

Laser Chemical Etching of Conducting and Semiconducting Materials

ABSTRACTThe purpose of the paper is to examine the basic processes involved in the laser-enhanced chemical etching of solids. Specifically, the process of chemisorption, the reaction between the adsorbate and substrate atoms and the vaporization of product species affected by the laser radiation are discussed. It is shown that the laser method can provide important insight into the gas-surface reaction mechanisms. In addition, a number of examples are given to demonstrate the potential of the technique for applications to material processing. Some current studies on the laser-induced chemical etching of materials relevant to microelectronics are reviewed. Certain practical experimental approaches are also considered.