Fig.4 shows that the deposition rate is insensitive to changes of substrate temperature. The process parameters are: reaction pressure is 0.7 Pa, flow ratio of O2 gas and Ar gas is 3/20, sputtering power is 140 W. With the increase of substrate temperature, the adhesion coefficient of gas phase atoms on the surface of the substrate increases, and the deposition rate should be reduced. However, the effect in this experiment is not large. This is probably because the instrument shows temperature does not match the actual temperature or due to etch damage to the substrate surface by the sputtered particles.
The two points at 170°C and 230°C are plotted on the curve of Fig. 4, and plotted as Fig. 4.1, the other process parameters remain the same. It can be seen that at a lower flow rate, the deposition rate is basically unchanged, and the abrupt changes in the deposition rate are almost the same at both points, but at a higher flow rate, the deposition rate becomes larger as the substrate temperature increases. Therefore, high temperature cannot delay the phenomenon of target poisoning, but it can make the rate of change of deposition rate reduce. It can be seen from Figure 4.1 that whether change a parameter of reaction pressure, sputtering power or deposition temperature, the deposition rate of the film is consistent with the trend of the O2 flow rate, it will undergo the transition from the metal mode to the oxide mode both because of target poisoning. So, the gas pressure, power, and temperature can be appropriately increased to obtain a higher deposition rate to alleviate the target poisoning phenomenon.
Fig.4 Relationship between substrate temperature and deposition rate
Fig 4.1 Relationship between O2 gas flow and deposition rate at different substrate temperatures