Thermal analysis for graphitization and ablation depths of diamond films

In the present study, a thick diamond film deposited on a 6″ silicon wafer was planarized by an ArF excimer laser. In order to predict the graphitization thickness formed in the diamond film by a laser beam moving with a sliding velocity as well as a fluence, the general solution of the three-dimensional temperature distribution is successfully developed to be a function of the fluence and pulse duration of the laser beam. A reported model developed for the graphitization probability of diamond film is adopted in the present study to determine the graphitization thickness if the temperature solutions are substituted into this model. The ablation thickness in the graphitization layer can be determined so long as the local temperature in the specimen is higher than the ablation temperature of the graphitization layer. Then, the thickness of graphite residual on the working surface after ablation can be obtained by the subtraction of the ablation thickness from the graphitization thickness. This graphite thickness is proved to be very close to the value obtained from scratching tests. This implies that the temperature solutions predicted by the present model are trustworthy. The effect of the scanning velocity is insignificant to the surface temperature if the pulse duration time is much shorter than the time period between two adjacent laser pulses.