Yoshio Uhara

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-µm 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°C and a gas pressure of p=9.0×10-2 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.

Cu filling of 10 nm trenches by high-magnetic-field magnetron sputtering

Ru and Cu sputterings were performed with two different high-vacuum sputtering systems. The Ru sputtering was performed by high-vacuum sputtering. On the other hand, the Cu sputtering was performed by high-magnetic-field sputtering. High-magnetic-field sputtering, which entails a Cu deposition rate of 80 nm/min (target–substrate distance: 200 mm) at a sputtering pressure of 7 × 10−2 Pa, is used for the Cu filling of 10-nm-wide Ru-lined trenches with an aspect ratio of 6.5. The complete Cu filling of trenches is accomplished within 1 min of sputtering time using a 1 at. % N2–Ar sputtering gas. The reason for the complete Cu filling is considered in terms of the capillary theory, focusing on the wettability of Cu on Ru. The improvement in Cu wettability with the use of a N2 additive is also evaluated in terms of the contact angle for Cu on Ru and surface shape.

Development of high-vacuum planar magnetron sputtering using an advanced magnetic field geometry

A permanent magnet in a new magnetic field geometry (namely, with the magnetization in the radial direction) was fabricated and used for high-vacuum planar magnetron sputtering using Penning discharge. Because of the development of this magnet, the discharge current and deposition rate were increased two to three times in comparison with the values attainable with a magnet in the conventional geometry. This improvement was because the available space for effective discharge of the energetic electrons for the ionization increased because the magnetic field distribution increased in both the axial and radial directions of discharge.