Cu films by partially ionized beam deposition for ultra large scale integration metallization

Abstract

Highly (111) oriented Cu films with a thickness around 1800 Å were prepared on Si(100) at room temperature by partially ionized beam deposition (PIBD) at pressure of 8 × 10-7-1 × 10-6 Torr. Effects of acceleration voltage (Va) between 0 and 4 kV on such properties as crystallinity, surface roughness, resistivity, etc. of the films have been investigated. The Cu films deposited by PIBD had only (111) and (200) planes, and the relative intensity ratio, I(111)/I(200) of the Cu films increased from 6.8 at Va = 0 kV to 37 at Va = 4 kV. There was no indication of impurities in the system from Auger electron spectroscopy (AES) analyses. A large increase in grain size of the films occurred with Va up to Va = 1 kV, but little increase occurred with Va > 1 kV. Surface roughness of the Cu films decreased with Va, and resistivity showed the same trends as that of the surface roughness. In the Cu films by PIBD, it is considered that changes of resistivity are mainly due to a surface scattering rather than a grain boundary scattering. The via holes, dimensions of which are 0.5 μm in diameter and 1.5 μm in depth, in the Cu films made at Va = 4 kV were completely filled without voids. Interface adhesion of the Cu film on Si(100) deposited at Va = 3 kV was five times greater than that of Cu film deposited at Va = 0 kV, as determined by a scratch test.