Novel low-temperature double passivation layer in hydrogenated amorphous silicon thin film transistors
Journal
Japanese Journal of Applied Physics, Part 1: Regular Papers and Short Notes and Review Papers
Journal Volume
36
Journal Issue
4
Pages
2073-2076
Date Issued
1997
Author(s)
Liao W.-S
Abstract
Hydrogenated amorphous silicon nitride (a-SiNx:H) films fabricated by plasma-enhanced chemical vapor deposition (PECVD) at low temperatures (<150°C) tend to be oxidized within one month because of their porous structure which permits the percolation of H2O (moisture) molecules from air. The a-SiNx:H film deposited at a low temperature of 100°C oxidizes more quickly (within 1 day) due to its greater porosity. However, it is found that a very thin coating (>6.4nm) of PECVD a-Si:H can prevent the percolation of H2O molecules. Hence, for a-Si:H thin film transistor (TFT) with a 100°C-deposited 470-nm-thick a-SiNx:H passivation layer, the ON/OFF current ratio will be degraded by ∼2 orders of magnitude after 7 days of exposure to air. On the other hand, for the 100°C-deposited a-SiNx:H passivation layer with an additional 100°C-deposited 50-nm-thick a-Si:H coating, the measured ON/OFF current ratio does not show any sings of degradation for up to one week. Therefore, a novel low-temperature (<150°C) water-resistant a-Si:H coating on a a-SiNx:H passivation layer deposited at the same temperature, which can be consecutively processed vising the same PECVD system without breaking the vacuum, is proposed.
Subjects
a-Si:H TFT; Low-temperature a-SiNx:H passivation; PECVD; Water-resistant a-Si:H coating
Other Subjects
Hydrogenated amorphous silicon thin film transistors; Plasma enhanced chemical vapor deposition (PECVD); Amorphous silicon; Chemical vapor deposition; Hydrogenation; Passivation; Silicon nitride; Thin film transistors
Type
journal article