T. Kashiro et al., IMPORTANCE OF FIRST LAYER THICKNESS ON TFT CHARACTERISTICS USING A-SI-H DEPOSITED BY 2-STEP PROCESS, Journal of non-crystalline solids, 200, 1996, pp. 1130-1133
In order to increase the throughput during thin film transistor-liquid
crystal display manufacture, we investigated a 2-step deposition proc
ess for hydrogenated amorphous silicon. The first hydrogenated amorpho
us silicon layer of an inverted staggered type thin film transistor wa
s deposited at a lower deposition rate to improve the interface with t
he gate insulator layer and the second hydrogenated amorphous silicon
layer was deposited at a higher rate to improve the throughput, It was
found that the mobility values of thin film transistors increased wit
h increasing first layer thickness and reached a saturation value afte
r a certain first layer thickness. When the first hydrogenated amorpho
us silicon layer quality was improved by decreasing its deposition rat
e, a thicker first layer hydrogenated amorphous silicon was needed to
reach a mobility saturation.