Preparation of boron nitride thin films by microwave PECVD and their analytical characterisation

Abstract

Hexagonal boron nitride films on Si(100) substrates are formed from the system N₂/B(OCH₃)₃ (TMOB) by microwave plasma enhanced chemical vapour deposition (PECVD). The parameters substrate temperature, deposition time and composition of the process gas mixture were varied. The stability of the deposited layers mainly depends on the substrate temperature during the deposition process. Layers formed below 650 °C showed strong decomposition features by contact with air humidity. Above this temperature very stable layers could be produced. This was confirmed by hydrolysis tests. The structural growth of the boron nitride layers was investigated by means of transmission electron microscopy (TEM) and electron energy loss spectroscopy (EELS). Three different growth zones were observed within the layers. The composition was determined by electron probe microanalysis (EPMA) and elastic recoil detection analysis (ERDA). Infrared and Raman spectroscopy were used for qualitative investigation of the BN layers.