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DS: Fachverband Dünne Schichten

DS 44: Postersession II

DS 44.24: Poster

Donnerstag, 23. März 2017, 17:00–19:00, P1C

Perforation of CVD silicon nitride by AgAl alloy formation — •Katharina Krügel, Tobias Urban, and Johannes Heitmann — Institut für Angewandte Physik, TU Bergakademie Freiberg, Freiberg, Germany

The alloying of Al and Ag on dielectric silicon nitride layer (Si3N4), deposited by Chemical Vapor Deposition on <100> Silicon substrates, was investigated. Ag and Al were deposited in variable proportions with overall thickness of 1 μm by Physical Vapor Deposition on the Si-substrate with Si3N4 layers of 80 and 100 nm thickness. This setup is similar to industrial photovoltaic application.

The samples were tempered with Rapid Temperature Processing up to 1000°C. By microscopy square-shaped hollows within the metal layer for annealing temperatures higher than 800°C were shown. By preparation of a Focused Ion Beam-cut and following Scanning Electron Microscope investigation a local perforation of the Si3N4 layer was observed. Below this region a pyramidal etching spike is formed with an angle of 52.3° which is equal to the angle between the <100> and <111> plane. These spikes were filled with an intermetallic phase consisting of fcc AgAl- and hcp Ag2Al-phase with local silicon precipitations. The formation of this etching pits can be proven by resistance measurement between metal and silicon. With increasing temperature an electrical contact was formed due to the local etching of the dielectric layer.

Usually Si3N4 has a high chemical and thermal stability. For the first time an etching of the passivation layer only by AgAl was observed.