Small geometry effects in n- and p-channel polysilicon thin film transistors

• Main Authors: Lewis, A.G., Wu, I.-W., Huang, T.Y., Koyanagi, M., Chiang, A., Bruce, R.H.
• Format: Conference Proceeding
• Language: English
• Subjects: CMOS digital integrated circuits; Degradation; Flat panel displays; Geometry; Laboratories; Shift registers; Substrates; Thin film transistors; Threshold voltage; Transconductance
• ISSN: 0163-1918; 2156-017X
• DOI: 10.1109/IEDM.1988.32806

The authors describe the results of an experimental study of small-geometry effects in n- and p-channel polysilicon TFTs (thin film transistors) fabricated on quartz substrates. Short-channel effects are shown to be severe, with significant threshold shifts observed in devices with gate lengths of less than about 8 mu m and degradation in drain breakdown voltages for gate lengths below about 5 mu m. The performance of simple digital CMOS circuits fabricated using TFTs with a range of gate lengths is also reported, and the improvement in speed achieved by reducing gate lengths is shown. In particular, the operation of shift registers, designed using 5- mu m-long TFTs at clock frequencies in excess of 50 MHz, is demonstrated.< >