Chemical Vapor Deposition

Tungsten films are deposited by ALD using dilute SiH₄ as the silicon source. Growth rates of 6.0 ± 0.5 Å per cycle are observed between 200 and 300°C. Analysis by AES and depth-profile SIMS show a silicon content of <5 at.-% in the W films. Higher deposition temperatures favor lower Si incorporation. A dilute silane co-reactant offers an alternative to pure silane with better process safety and 4.5 Å per cycle growth at low temperature (150°C).

Oxide-based thin film devices and sensor structures deposited on transparent substrates are investigated. All oxide elements in these structures are deposited using ALD. The composite dielectrics consisting of pairs of Al₂O₃, HfO₂, ZrO₂, or TiO₂ are used as insulators in capacitors and transistor structures, with ZnO layers deposited as channel and gate layers. The structures are obtained at low temperature, which enables their deposition on elastic, transparent substrates.