Laser assisted magnetron sputter deposition with ultrashort pulses

薄膜和纳米结构的制备可以通过各种技术来实现。这使得材料的定制成为可能，包括它们的光学、电学和磁性。在各种方法中，溅射是一种物理气相沉积技术，它基于离子与靶的碰撞，材料从靶上分离并沉积在衬底上。在磁控溅射(MS)中，利用靠近靶表面的电磁场使惰性气体电离并产生等离子体，产生离子并加速轰击靶材料，从而获得高质量的均匀薄膜。虽然沉积速度与离子的数量成比例，但使用高压惰性气体是很有诱惑力的，但这是以结构和密度方面的低质量薄膜为代价的。因此，MS的限制因素是低沉积速率，从而限制了这项技术的工业应用。近年来，我们的工业合作伙伴Plamionique Inc.与INRS-EMT的研究人员合作，开发了一种名为MS/PLD(脉冲激光沉积)的混合技术。他们已经证明，将MS与20赫兹的纳秒UV激光与目标相互作用，可以保持高沉积速率，同时保持足够低的压力，以实现高质量的薄膜。由于在较低的脉冲宽度下，达到消融阈值所需的通量减少，与脉冲宽度的平方根成反比(降至1皮秒-皮秒脉冲宽度)，我们假设MS/PLD将受益于使用超短脉冲来触发和维持磁控放电。利用超快激光系统，我们将研究0.04-10ps的超短脉冲MS/PLD。此外，超短脉冲激光以高得多的重复频率工作，因此提供了研究MS/PLD的比例到更高的激光重复频率以增加沉积速率(例如，5 kHzvs20 HZ代表125倍)的可能性。

The fabrication of thin films and nanostructures can be realized through various techniques. This enables the tailoring of materials including their optical, electrical, and magnetic properties. Among the various approaches, sputtering is a physical vapour deposition technique which is based on ions colliding with a target from which material is detached and deposited on a substrate. In magnetron sputtering (MS), an electromagnetic field confined near the surface of the target is used to ionize the inert gas and to create aplasma, from which ions are produced and accelerated to bombard the target materials from which high quality uniform thin films are obtained. While the rate of deposition scales with the number of ions, it is tempting of using a high pressure of inert gas, but this comes at the costs of low quality films in terms of structure and density. Therefore, the limiting factor for MS is a low rate of deposition thus limiting the industrial applications of this technique.Over the recent years, our industrial partner Plasmionique Inc. has developed, in collaboration with INRS-EMT researchers, a hybrid technique called MS/PLD (Pulsed Laser Deposition). They have demonstrated that combining MS with a 20 Hz nanosecond UV laser interacting with the target allows the retention of a high rate of deposition while keeping the pressure sufficiently low enough to enable high quality films. As the fluence needed to reach the ablation threshold is reduced at lower pulse duration, with the inverse of the square root of the pulse duration (down to 1 picosecond - ps - pulse duration), we hypothesize that MS/PLD will benefit fromthe use of ultrashort pulses for triggering and maintaining the magnetron discharge. Using ultrafast laser systems, we will study MS/PLD with ultrashort pulses from 0.04 to 10 ps. Furthermore, ultrashort pulsed laser are operated at much high repetition rate, thus offering the possibility of studying the scaling of MS/PLD to higher laser repetition rate for increasing the rate of deposition (e.g. 5 kHz vs 20 Hz represents a factor of 125).