Bulk and interface charge in low temperature silicon nitride for thin film transistors on plastic substrates

• Published in: Journal of vacuum science & technology. A, Vacuum, surfaces, and films Vacuum, surfaces, and films, 2004-11, Vol.22 (6), p.2256-2260
• Main Authors: Park, Kie Jin, Parsons, Gregory N.
• Format: Article
• Language: English
• ISSN: 0734-2101; 1520-8559
• DOI: 10.1116/1.1795822

We report bulk and interface charge densities in silicon nitride thin films deposited by plasma chemical vapor deposition from N H 3 – N 2 – Si H 4 mixtures, at temperatures compatible with flexible plastic substrates. Bulk and interface charges are independently determined from measurements of flat band potential as a function of film thickness for a range of substrate temperatures and gas compositions. Increasing NH–SiH bond ratio in the deposited films (determined from infrared absorption) leads to a more positive interface charge and more negative bulk charge, and the trend in interface charge is consistent with a relation between charge and stress at the Si – Si N x interface. As substrate temperature is decreased from 250 to 50 ° C , the leakage is observed to decrease, the interface charge decreases, and the bulk charge changes from negative to net positive.