Impurities in the solids of the Titanium Target Block and oxygen and moisture in the pores are the main sources of contamination in the deposited films. Targets for different applications have different requirements for different impurity contents. For example, pure aluminum and aluminum alloy targets for the semiconductor industry have special requirements for alkali metal content and radioactive element content.

In order to reduce the pores in the target solids and improve the performance of sputtered films, the target is usually required to have a high density. The density of the target not only affects the sputtering rate, but also influences the electrical and optical properties of the film. The higher the target density, the better the performance of the film. In addition, increasing the density and strength of the target allows the target to better withstand the thermal stresses of the sputtering process. Density is also one of the key performance indicators of target material, grain size and grain size distribution.
Usually the target is polycrystalline structure, the grain size can be from micron to millimeter. For the same kind of target, the sputtering rate of the target with fine grains is faster than that of the target with coarse grains; and the thickness distribution of the film deposited by sputtering of the target with small difference in grain size (uniform distribution) is more uniform.