Cu films on Si(100) by partially ionized beam deposition

Abstract

Highly (111) oriented Cu films with a thickness around 1800 angstroms 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 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 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 films at the ionization potential of 400 V decreased with Va, and resistivity had the same trends as that of the surface roughness. In the Cu films made by PIBD, it appears that changes of resistivity are mainly due to a surface scattering rather than a grain boundary scattering. The via holes, which is of 0.5 μm diameter ×1.5 μm deep, in the Cu films made at Va = 4 kV, were completely filled without voids. Adhesion of the Cu film on Si(100) deposited at Va = 3 kV was 5 times greater than that of Cu film deposited at Va = 0 kV, as determined by a scratch test.