AIN films were deposited on silicon substrates at low temperatures (300-500 degrees C) by electron cyclotron resonance plasma-enhanced chemical vapor deposition (ECR PECVD) using trimethylaluminum, N-2 and H-2 gases. The degree of c-axis orientation, crystallinity, functional groups and chemical composition of the films were investigated for various deposition conditions. The degree of c-axis orientation depends on the substrate surface condition and it improves with increasing substrate temperature as well as with increasing microwave power. A c-axis oriented (sigma = 4.3 degrees) AlN film was prepared at 500 degrees C. The importance of the system design which allows the precursor to be dissociated efficiently by the ECR plasma is discussed.