Woong-Sun Kim

Improvement in the bias stability of amorphous indium gallium zinc oxide thin-film transistors using an O2 plasma-treated insulator

The effects of an O2 plasma-treated SiNX-based insulator on the interfacial property and the device performances of amorphous indium gallium zinc oxide thin-film transistors (a-IGZO TFTs) were investigated. We tried to improve the interfacial characteristics by reducing the trap density between the SiNX gate insulator and a-IGZO channel by the O2 plasma treatment. The plasma treated-device performances were remarkably improved. The drastic improvements obtained for the O2 plasma-treated a-IGZO TFTs included excellent bias stability as well as a high field effect mobility (μFE) of 19.4 cm2/V s, an on/off current (ION/IOFF) of 108, and a subthreshold value (S) of 0.5 V/decade.

The Influence of the Hafnium Doping on Negative Bias Stability in Zinc Oxide Thin Film Transistor

The influence of hafnium doping on negative bias temperature instability in zinc oxide thin film transistors (TFTs) was investigated. The hafnium zinc oxide TFTs showed that the turn-on voltage (V ON ) shifted from -2 to -7 V with negligible changes in the subthreshold swing and field effect mobility (μ FE ) after a time of total stress. The enhanced improvement of the V ON shift was attributed to the reduction in interface trap density, which might result from the suppression of oxygen vacancy related defects due to the role of Hf ions.

Amorphous Indium Gallium Zinc Oxide Semiconductor Thin Film Transistors Using O2 Plasma Treatment on the SiNx Gate Insulator

In this study, we investigated the role of processing parameters on the electrical characteristics of amorphous In–Ga–Zn–O (a-IGZO) thin film transistors (TFTs) fabricated using DC magnetron sputtering at room temperature. Processing parameters including the oxygen partial pressure, annealing temperature, and channel thickness have a great influence on TFT performance and better devices are obtained at a low oxygen partial pressure, annealing at 200 °C, and a low channel thickness. We attempted to improve the a-IGZO TFT performance and stability under a gate bias stress using O2 plasma treatment. With an O2 plasma treated gate insulator, remarkable properties including excellent bias stability as well as a field effect mobility (µFE) of 11.5 cm2 V-1 s-1, a subthreshold swing (S) of 0.59 V/decade, a turn-on voltage (VON) of -1.3 V, and an on/off current ratio (ION/IOFF) of 105 were achieved.

Characteristics of lanthanum hafnium oxide deposited by electron cyclotron resonance atomic layer deposition

Lanthanum hafnium oxide (LHO) thin films were grown using an electron cyclotron resonance atomic layer deposition technique. Tetrakis(ethylmethylamino)hafnium (TEMAHf) and tris(ethylcyclopentadienyl) lanthanum (III) [La(EtCp)3] were utilized as the hafnium and lanthanum precursors, respectively. O2 plasma was used as a reactant gas. Transmission electron microscopy analyses revealed that the as-deposited LHO film had a crystalline structure at a deposition temperature of 400°C. Rapid thermal annealing of the LHO films induced dramatic changes in the electrical properties. The VFB for the films shifted toward the ideal VFB and the amount of positive fixed charge disappeared in the LHO films. The leakage current density of the film deposited at 400°C was estimated to be 4.6×10−7A∕cm2 at −1V. The leakage characteristic of the LHO films was improved with annealing at temperatures above 900°C.

Titanium Oxide Thin Films Prepared by Plasma Enhanced Atomic Layer Deposition Using Remote Electron Cyclotron Resonance Plasma for Organic Devices Passivation

We examined titanium oxide films and their barrier characteristics. Titanium oxide films were deposited at room temperature with electron cyclotron resonance plasma power of 300 W. We measured the growth rate of the titanium oxide film to be 1.8 A/cycle. Barrier layers on poly(ether sulfon) (PES) substrates were observed to provide activation energy for water permeation. Activation energy of 12.4 kJ/mol was added by applying a titanium oxide coating with a thickness of 100 nm. The passivation performance of the titanium oxide film was also investigated using organic light-emitting diodes (OLEDs). The relative luminance of a 400-nm-thick-coated OLED device was diminished by 11.6% for 20 h.

Copper seed layer using atomic layer deposition for Cu interconnect

Cu has replaced Al for interconnection material in ultra large integrated circuit (ULSI), resulting in reducing the RC delay and achieving higher electro-migration reliability. However, it becomes more difficult to form reliable Cu wire as the feature size more decreases. For successful electrochemical plating (ECP) filling, continuous Cu seed layer with low resistivity and conformallity is essentially required. We have studied a Cu seed layer deposited using plasma enhanced atomic layer deposition (PE-ALD). The electrical property of sub-10 nm thickness Cu thin film was determined by the continuity and morphology of thin film. Based on these results, Cu seed layers were deposited on the 32 nm sized Ta/SiO2 trench substrate, and ECP was performed under the conventional conditions. It was observed that the continuous seed layer was deposited using PE-ALD and the trench was perfectly filled.

Water Vapor Permeation Properties of Al 2 O 3 /TiO 2 Passivation Layer Deposited by Atomic Layer Deposition

In this study, and films was deposited on to PES (poly(ethersulfon) substrate by using atomic layer deposition as functions of deposition temperature and plasma power. The density and carbon contents of and films was changed by varying process conditions. High density thin films was achieved through optimizing the process conditions. Buffer layer was deposited prior to the processing of upper thin films to avoid PES surface destruction during the high power plasma process and to enhances the tortuous path for water vapor permeation for the defect decoupling effect. The water vapor transmission rate by using MOCON test was investigated to analyze the effect. Water vaper permeation properties was improved by using the inorganic multi-layer passivation layer and activation energy of the water vapor permeation was increased.

Phosphorus Doping Effect in a Zinc Oxide Channel Layer to Improve the Performance of Oxide Thin-Film Transistors

In this study, we fabricated phosphorus-doped zinc oxide-based thin-film transistors (TFTs) using direct current (DC) magnetron sputtering at a relatively low temperature of 100°C. To improve the TFT device performance, including field-effect mobility and bias stress stability, phosphorus dopants were employed to suppress the generation of intrinsic defects in the ZnO-based semiconductor. The positive and negative bias stress stabilities were dramatically improved by introducing the phosphorus dopants, which could prevent turn-on voltage (VON) shift in the TFTs caused by charge trapping within the active channel layer. The study showed that phosphorus doping in ZnO was an effective method to control the electrical properties of the active channel layers and improve the bias stress stability of oxide-based TFTs.

The influence of the SiO[sub 2] interlayer on transfer characteristic in tin oxide thin film transistor

In this article, we report the fabrication on SnO2 thin film transistors (TFTs) fabricated by DC sputtering system. SnO2 based TFTs have been reported previously, and all the TFTs operate depletion‐mode, requiring the application of a gate voltage to turn it off. In contrast to previously reports, the SnO2 TFT reported herein operates as an enhancement‐mode device, requiring the application of a gate voltage to turn the device on. Furthermore, we introduce an hafnium‐tin oxide (HfSnO) semiconductor materials that have been developed for use as p‐channel TFTs.