Sputter Deposition Processes

Abstract

Deposition of films by sputtering was observed first in 1852 by Grove. The technique was in general use through the 1920s for preparing reflective coatings and other thin film samples. Western Electric deposited gold on wax masters for phonograph recordings. The improvement in diffusion pump technology at that time caused thermal evaporation deposition to replace sputtering.Not till the 1950s did sputter deposition reappear… Bell Laboratories developed tantalum hybrid circuit technology using sputter deposition. Besides depositing Ta, they created a new material, Ta2N, by reactively sputtering tantalum in gas mixtures of argon and N2. Since then, these two methods, sputtering of metals and alloys and reactive sputtering of compounds, have been investigated for many applications of thin film materials.Although the general aspects of the methods have changed little in the past 30 years, the implementations have changed significantly, particularly since the introduction of magnetron systems in the 1970s. This review will concentrate mainly on these flexible, high rate magnetron deposition systems.The term sputtering actually applies to the physical processes by which atoms are removed from a material. Momentum is transferred from an incident, energetic particle, usually in the form of an ion, to atoms of the target material. A large number of these atoms are displaced from their normal sites in the crystal lattice, producing a disordered structure that also contains some of the incident particles, which are implanted. Some of the target atoms are displaced from the surface; if they have enough energy, they escape from the target as sputtered atoms.