Effects of an alternating field in field-aided lateral crystallization process for low temperature poly-silicon

The effect of the alternating field (AC voltage) instead of the static field (DC voltage) was investigated in the field-aided lateral crystallization process, which is one of the low temperature crystallization processes for the amorphous silicon films. Using a photolithography process, a 5-mm-wide bar-shaped photoresist (PR) pattern was formed on the a-Si. On the PR-patterned a-Si, a 2-3-nm-thick Cu catalyst layer was deposited by a DC sputtering, and then, the Cu layer on the PR pattern was lifted off. The silver electrodes were pasted at the opposite sides of the Cu-free bar pattern. Then, the patterned specimen was annealed at 500 °C in N2 ambient for 5 h with the application of various AC fields (ranging from 1 to 5 V/cm) along with a DC field of 30 V/cm. As compared with the case of a DC field of 35 V/cm only, the specimen from a mixed field of 30 V/cm DC and 5 V/cm AC resulted in 1.5 times faster crystallization rate, regardless of experimental frequency values ranging from 10 Hz to 50 MHz. Presumably, the enhancement of the crystallization rate under the combined field is associated with an increase in the flux of the crucial diffusion species, Cu atoms, which govern the overall crystallization rate due to the effect by the AC field.