We have used high-resolution angle-dependent x-ray photoemission to study the evolving interface formed by vapor depositing Ge (0–80 A) onto cured polyimide (PI). The core level line-shape changes of PI and Ge demonstrate that Ge reacts chemically with PI for coverages below ~10 A. The rapid attenuation of the carbonyl C 1s photoemission intensity shows that Ge reaction preferentially occurs with carbonyl groups for Ge deposition below ~0.5 A and charge withdrawal from the imide-benzene ring is reduced. With increasing Ge deposition (between 0.5 and 5 Å), more carbonyl groups are involved in reaction with Ge and the excess of charge carried by carbonyl carbon atoms induces a hyperconjugation form of the imide-benzene ring. These rings are more vulnerable to Ge chemical attack and the formation of Ge-C bonds. Our results indicate multiple Ge-O-C and Ge-C bonding configurations. Once the initial reaction is complete, the growth mode of Ge on PI appears to be layer-by-layer-like. Time and temperature-dependent x-ray photoelectron spectroscopy studies of the 40-A Ge/PI interface showed no changes below 400 °C. At 400 °C, changes in core level emission intensities indicate clustering and slight intermixing at the interface.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Vacuum Science and Technology A: Vacuum, Surfaces and Films|
|State||Published - Jul 1988|