Electrical and Reliability Characteristics of High-K Er2O3 Dielectrics InGaZnO TFT and Memory Devices

The InGaZnO TFT device has attracted much attention for the AMOLED flat panel display (FPD) applications because of their high mobility, good uniformity and low process temperature. This device has the opportunity to replace amorphous silicon TFT and polycrystalline silicon TFT devices in the next generation TFT application. IGZO TFT using a high-k gate dielectric can achieve a lower operation voltage and a higher on/off current ratio. High-k dielectric materials as charge-trapping layers were also explored in IGZO TFT nonvolatile memory devices for the portable electronic product. In order to obtain large capacity, high speed and low operation voltage in IGZO TFT nonvolatile memory is one of most significant candidate for next generation memory. The electrical mechanism of InGaZnO TFTs is little different in comparison with traditional Si-based channel material. Hence, it still needs to overcome many challenges for practical applications. The electrical degradation of the InGaZnO TFT is one of the most important issues for future applications. The one of electrical degradation issue is due to the environment effect which results in the instability of threshold voltage. Therefore, in this project a detail and systematic effort of electrical and reliability characteristics of high-k Er2O3 dielectrics InGaZnO TFT and memory devices will be investigated. This project will focus on the electrical reliability issue of the devices with various factors including measurement environment effect, voltage stress, and illumination stress. The post-deposition annealing (PDA) process will be studied for reliability improvement. This process will be explored to the IGZO TFTs for better integration and commercialization of our devices. The project is divided into three years: First year: Physical and electrical properties of high-k Er2O3 dielectric films were investigated. High-k Er2O3 gate dielectrics for IGZO TFT device application ere developed to achieve high Ion/Ioff ratio, high effective mobility, and low subthreshold swing (SS). Second year: High-k Er2O3 films as a charge trapping layer in IGZO TFT memory device were developed to achieve high P/E speed, low operation voltage, good data retention, high P/E cycles, and small gate and drain disturb. Third year: Investigation of electrical reliability issues for high-k Er2O3 IGZO TFT and memory devices includes the positive/negative bias stress (PBS/NBS), light stress (LS), positive/negative bias-light stress (PBLS/NBLS), positive/negative-bias temperature instability (PBTI/NBTI), and high temperature/moisture effect. The Er2O3 IGZO TFT and memory devices using different PDA treatments can improve their electrical reliability characteristics.

Project ID:PB10301-0497
External Project ID:NSC102-2221-E182-072-MY3