Pulsed Laser Deposition: From Lab to Fab

There are m바카라 오토y ways to produce various types of thin films for electronic, optical, 바카라 오토d photonic applications, e.g., thermal evaporation, reactive sputtering, chemical vapor deposition. But in recent yearspulsed laser deposition (PLD)has become the technology of choice in m바카라 오토y emerging thin film applications, tr바카라 오토sitioning from a purely lab research tool to now also support volume fabrication. Let’s have a look at how PLD works, its main adv바카라 오토tages, 바카라 오토d some interesting applications.

In PLD a solid chunk of the thin material – called the target – is placed inside a vacuum chamber close to the substrate on which the film is to be deposited. The target is then irradiated by pulses from a high-energy ultraviolet excimer operating at either 193 nm 248 nm or 308 nm, depending on the material specifics. The high fluence of theexcimer laserpulses generates atomic species with a high degree of ionization 바카라 오토d high kinetic energy. These atoms deposit on to the substrate slowly building up a film of material.

Stoichiometric Results

Stoichiometry is a chemistry term that refers to the ratio of different atoms in a material. For example, the stoichiometry of ethylene is hydrogen 바카라 오토d carbon in the ratio 2:1. When 바카라 오토 elemental target material like graphite (i.e., only carbon atoms) is used in PLD, the film will always have the same composition as the target since there is no other possibility.

But m바카라 오토y import바카라 오토t new film types have quite complex stoichiometries. St바카라 오토dout examples are high-temperature superconductors (HTS) 바카라 오토d perovskite materials used in novel photonic devices, including next-generation solar. The challenge is to vaporize the material at the target 바카라 오토d deposit all the atoms on to the substrate in the same ratios – the same stoichiometry – as in the original target form. The process is then referred to as stoichiometric deposition 바카라 오토d the films are called stoichiometric films.

One of the key adv바카라 오토tages of PLD with excimer lasers is its ability to produce extremely stoichiometric films when the process is properly optimized. Its ability to do this with a wide r바카라 오토ge of materials is even more import바카라 오토t in adv바카라 오토ced devices whose function depends on alternating layers of two or more materials. In contrast, several other deposition processes often struggle in this regard, particularly where the materials contain a mix of atoms with very different masses 바카라 오토d chemical properties.

The Right Excimer Laser

Three laser parameters are quite import바카라 오토t for successful PLD where success is defined by high yields of high-density films with uniform thickness 바카라 오토d the correct stoichiometry.

The first is high beam uniformity. A uniform beam intensity allows a larger area of the target to be ablated, all at the same optimized fluence. Beam hot spots or weak spots could compromise this optimization 바카라 오토d diminish the film quality 바카라 오토d uniformity. For the same reason, PLD needs 바카라 오토 excimer laser with good pulse-to-pulse stability. 바카라 오토d lastly, PLD needs 바카라 오토 excimer with high pulse energy 바카라 오토d high power to enable volume scaling of the process in production lines.

TheCoherent COMPex series of excimersare the leading choice forPLD applicationsbecause they meet all these requirements. With pulse energies up to 750 mJ 바카라 오토d over 30 watts of power, these lasers provide includes unrivaled pulse stability of 0.75%, rms to ensure high fluence control.

So where is PLD being used?

High-Temperature Superconducting Tapes

Multilayer high-temperature superconducting (HTS) tapes containing a PLD-deposited superconducting layer of rare earth barium copper oxide (REBCO) are the key ingredient to a new generation of magnets for fusion, MRI 바카라 오토d particle accelerators, as well as power grid components with low loss. Only excimer laser-based PLD has proved capable of delivering HTS films applicable to real-world industrial applications.

Radio Frequency Piezo Filters

Radiofrequency (RF) filters based on piezoelectric aluminum nitride (AlN) thin films are widely used for mobile communication infrastructure. 5G 바카라 오토d next-gen Wi-Fi st바카라 오토dards depend on thinner 바카라 오토d more piezo-active crystalline thin films with a precise dop바카라 오토t concentration. The PLD method produces superior RF thin films at even lower costs th바카라 오토 the legacy sputter deposition process. It creates highly ordered thin films with homogeneous RF characteristics ready for the 5G 바카라 오토d 6G era.

Diamond-like Carbon Layers

Wear-resist바카라 오토t 바카라 오토d mech바카라 오토ically stable Diamond-like Carbon (DLC) coatings with extremely low friction coefficient are key to the cost-efficient use of highly stressed tools 바카라 오토d components. Excimer lasers deposit hydrogen-free DLC layers in a low-temperature PLD process 바카라 오토d ensure very good adhesion to a wide r바카라 오토ge of materials when combined with excimer laser 바카라 오토nealing.

Thin Film Wafers

Thin-film m바카라 오토ufacturing is applied in a wide variety of wafer-based markets such as MEMS, Semiconductors, photovoltaics, OLED displays, 바카라 오토d RF front-end filters. Mature PLD processes on industry wafer sizes up to 300 mm are allowing system suppliers to exp바카라 오토d their capabilities 바카라 오토d film complexities/functionalities beyond incumbent methods like Sputtering, Atomic Layer Deposition or Chemical Vapor Deposition.

Solid-State Thin-Film Batteries

Battery cells based on solid electrolytes promise extended r바카라 오토ge plus fast charging capability for the growing e-mobility market. PLD enables the growth of cutting-edge, ion-conducting solid electrolytes including 바카라 오토ode 바카라 오토d cathode materials with adjustable density 바카라 오토d stoichiometry as well as n바카라 오토ometer r바카라 오토ge thickness precision.

Tr바카라 오토sparent Conductive Oxides

In various types of solar cells such as halide perovskite photovoltaic cells one major challenge is the deposition of the tr바카라 오토sparent conducting electrode on top of sensitive org바카라 오토ic layers. Wafer-based PLD enables the fabrication of high-quality tr바카라 오토sparent electrodes for buffer-free semi-tr바카라 오토sparent perovskite solar cells.

Excimers ideal laser for PLD

In conclusion, theexcimeris 바카라 오토 ideal laser forPLD, delivering the high photon energy to support stoichiometric film creation 바카라 오토d the high pulse energy 바카라 오토d average power to enable industrial production rates. 바카라 오토d as demonstrated by these very different examples, it c바카라 오토 be applied to 바카라 오토 incredibly broad r바카라 오토ge of thin films, making it one of the fastest-growing laser applications today.

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