Copper filling of deep sub-μm through-holes by high-vacuum planar magnetron sputtering using argon gas with added nitrogen:: Optimum quantity of nitrogen in argon gas

We investigated the effectiveness of using argon gas with added nitrogen when filling deep sub-mu m through-holes with copper by high-vacuum planar magnetron sputtering, and we examined the optimum amount of added nitrogen. This is done by varying the amount of added nitrogen between 0.5, 1.0, 3.0, 10, and 20 at.% in copper filling experiments conducted at a substrate temperature of 280 degrees C and a gas pressure of p = 9.0 x 10(-2) Pa with 80-nm-diameter holes having an aspect ratio of 5.6. The results show that the optimal amount of added nitrogen for copper filling is 1.0 at.%, and that the proportion of conformal filling is 1/5. The reasons for this are discussed in terms of the energy relationship between copper atoms adsorbed physically or chemically by nitrogen, sputtered atoms, and recoil atoms or molecules.