Channel-Shortening Effect Suppression of a High-Mobility Self-Aligned Oxide TFT Using Trench Structure

Channel-shortening effect (CSE) in oxide thin film transistors (TFTs) is a crucial issue that must be resolved for applications in ultra-high-resolution displays. One of the origins of the CSE is the diffusion of a shallow donor such as hydrogen from other layers into the channel. In this study, we...

Full description

Saved in:
Bibliographic Details
Published in:IEEE electron device letters 2021-12, Vol.42 (12), p.1798-1801
Main Authors: Kim, Junsung, Kim, Do Hyung, Cho, Seong-In, Lee, Seung Hee, Jeong, Wooseok, Park, Sang-Hee Ko
Format: Article
Language:English
Subjects:
Aluminum
Annealing
Channels
Diffusion layers
Displays
Electrodes
High current
High resistance
High resolution
high stability
Logic gates
Planar structures
Resistance
Self alignment
Semiconductor devices
suppressing channel-shortening effect
Temperature measurement
Thermal stability
Thin film transistors
trench structure
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Channel-shortening effect (CSE) in oxide thin film transistors (TFTs) is a crucial issue that must be resolved for applications in ultra-high-resolution displays. One of the origins of the CSE is the diffusion of a shallow donor such as hydrogen from other layers into the channel. In this study, we investigated for the first time the CSE of self-aligned Al-doped In-Sn-Zn-O (Al-ITZO) TFTs with planar and trench structures. The TFTs with planar structures exhibited severe negative \text{V}_{ {{ON}}} shifts after an annealing process, whereas the TFTs with trench structures were barely affected, thereby exhibiting excellent ON/ OFF characteristics. The vertical channel in the trench TFT had higher resistance than the horizontal channel because of a back-sidewall roughness and thin channel. The high resistance of vertical channels played a significant role in determining the ON/ OFF characteristics of Al-ITZO TFT, where \text{V}_{ {{ON}}} remained constant until the diffused shallow donors made the resistive vertical channels become conductive. Based on these unique operation characteristics, the suppression of CSE in a trench TFT was demonstrated even under a high annealing temperature. Trench TFT exhibited higher mobility, higher drain currents, and higher stability than planar TFT, thus making it suitable for ultra-high-resolution displays.
ISSN:0741-3106
1558-0563
DOI:10.1109/LED.2021.3125146