Figure 3 is a plot of sputtering power versus film deposition rate. The process parameters are: reaction pressure is 0.7 Pa, flow ratio of O2 and Ar is 3/20, deposition temperature is 200°C. From Fig. 3, it is known that the deposition rate of ZAO thin film almost linearly increases with the increase of sputtering power. Because in the sputter coating process, the deposition rate (R) is proportional to the product of the incident ion flux density (J) and the sputtering yield (Y), ie:
R = CYJ
C is the constant of the characteristics of the sputtering device. According to the above formula, when the sputtering power increases, the sputtering current and the voltage increase simultaneously, so that the incident ion current density (J) and the incident ion energy (E) increase, and the relationship between incident ion energy (E) and sputtering yield within this interval shows an approximate linear increase, and the film deposition rate also increases approximately.
On the curve of Figure 3, two points of 120W and 170W are chose and plotted as Figure 3.1, the other process parameters are consistent. It can be seen that as the power increases, the deposition rate curve as a whole moves to the upper right and maintains the similarity of the shape, which means that it can only increase the deposition rate than reduce the impact of the target poisoning phenomenon.
Fig.3 Relationship between sputtering power and deposition rate
Fig. 3.1 Relationship between O2 flow rate and deposition rate under different sputtering power