AVS 45th International Symposium
    Thin Films Division Monday Sessions
       Session TF-MoA

Paper TF-MoA9
Stress Alignment in SiO@sub 2@ Thin Films Deposited on Thin Chromium and Aluminum Film

Monday, November 2, 1998, 4:40 pm, Room 310

Session: Mechanical Properties of Thin Films
Presenter: K.E. Coulter, Flex Products, Inc.
Authors: K.E. Coulter, Flex Products, Inc.
V. Raksha, Flex Products, Inc.
Correspondent: Click to Email
SiO@sub2@ as a low index material in optical applications is often complicated by the intrinsic stress that induces film cracking, substrate deformation and delamination. 400 - 600nm thick SiO@sub2@ films were deposited by e-beam evaporation onto Cr (10nm) and Al (100nm) films. Using design of experiment methodology, we evaluated deposition process parameters such as rate, vacuum pressure, substrate type, coating material and storage conditions. The thin films were deposited on 50 and 175 µm thick PET substrates as well as fused silica witnesses. Analysis methods included interferometry, profilometry, microscopy, ellipsometry and an evaluation principle based on laser deflection off the free end of a coated PET strip. A correlation was established between absolute stress values measured by interferometry and the laser deflection method. Cr/ SiO@sub2@ and Al/ SiO@sub2@ films were deposited under vacuum conditions which produced tensile and compressive stress. S! tress in all SiO@sub2@ thin film stacks became more tensile with age (shelf life) regardless of the initial stress in the film. Dopants in the silica source material such as B@sub 2@O@sub 3@, Na@sub 2@O and Vycor produced films with similar correlations between stress and deposition conditions but at lower absolute stress magnitudes. In this presentation, the influence of the vacuum pressure, deposition rate, storage conditions and substrate properties will be discussed relative to the effect of stress on the thin film optical performance.