Study On Thickness Uniformity Of Large Area DLC Thin Films Deposited By Femtosecond Pulsed Laser

Diamond-like carbon thin films possess a series of unique virtues similar to those of natural diamond, such as high hardness, low friction coefficient, large band gap, excellent field electron emission property, high optical transmittance and chemical inert, etc. Comparing with the diamond films, DLC has a good surface smoothness and a simple deposition technique, etc., which lead to a wide application in the microelectronics, optics, acoustics and mechanics industries.Among all the deposition techniques for DLC films, pulsed laser deposition (PLD) is paid more attention due to its advantages in simple deposition method, good deposition effects and possibility depositing on different substrates, etc. Femtosecond laser, due to its short pulse duration, high peak power and high repetition rate, can be used in high efficient deposition for various films and is widely used in PLD. Since laser produced plasma plume is very small, it is difficult to prepare large-area uniform films, which is one of the limitations in preparation of thin films.This thesis mainly deals with the large-area DLC films deposited with femtosecond laser pulses. A off-axis deposition method, which aligns the edge of the substrate to the normal of the plasma plume and makes the edge of the plasma plume at the center of the substrate, is used to deposit large-area DLC films. The distance between the target and the substrate and the deposition time are optimized to obtain uniform and large area DLC films on the K9 and fused silica glasses with the diameter of 50mm. It is shown that the thickness uniformity of the films with off-axis deposition method is much better than that with the on-axis method. The thickness uniformity for off-axis and on-axis deposition is compared, and the possibility for preparing large-area uniform films is discussed. In addition, the film thickness distributions are qualitatively calculated for off-axis and on-axis deposition methods, and the thickness distribution of thin films is compared in different deposition conditions, which will be useful for preparing large-area uniform thin films.