A novel thin-film transistor with self-aligned field induced drain

• Published in: IEEE electron device letters Vol. 22; no. 1; pp. 26 - 28
• Main Authors: Horng-Chih Lin, Yu, C.-M., Lin, C.-Y., Yeh, K.-L., Tiao-Yuan Huang, Tan-Fu Lei
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.01.2001; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Active matrix liquid crystal displays; Amorphous silicon; Availability; Drains; Implants; Laboratories; Leakage current; Liquid crystal displays; Offsets; Photolithography; Plates (structural members); Semiconductor devices; Spacers; Substrates; Thin film transistors; Transistors; Voltage
• ISSN: 0741-3106; 1558-0563
• DOI: 10.1109/55.892433

In this letter, a novel thin-film transistor with a self-aligned field-induced-drain (SAFID) structure is reported for the first time. The new SAFID TFT features a self-aligned sidewall spacer located on top of the drain offset region to set its effective length, and a bottom gate (or field plate) situated under the drain offset region to electrically induce the field-induced-drain (FID). So, unlike the conventional off-set-gated TFTs with their effective FID length set by two separate photolithographic masking layers, the new SAFID is totally immune to photomasking misalignment errors, while enjoying the low off-state leakage as well as high turn-on characteristics inherent in the FID structure. Polycrystalline silicon TFTs with the new SAFID structure have been successfully fabricated with significant improvement in the on/off current ratio.