Intense Pulsed Light Annealing for High-k Capacitor Integration in 1T-1C DRAM With a-IGZO Cell Transistors

In this study, we report the integration of an a-IGZO cell transistor and a high-k ZrO2 cell capacitor using Intense Pulsed Light (IPL) annealing for 1T-1C DRAM application. With IPL annealing, the ZrO2 capacitor can successfully achieve a high k-value of 33, without any detrimental effect to the electrical performance of the IGZO transistor which is vulnerable to high temperature process. The a-IGZO transistor could maintain an ultra-low leakage current of $1.3\times 10^{-{16}}$ A/ $\mu $ m, even after the high-k dielectric crystallization process.

I. Introduction

There is a growing demand for high density and low power consumption Dynamic Random Access Memory (DRAM) devices for modern computing and artificial intelligence systems. One of the major issues in the power consumption of DRAM devices is the DRAM cell refresh time which is determined by the leakage currents of the cell transistor and the capacitor dielectric. The refresh time of current DRAM devices is on the order of tens milliseconds order and there is not much room for further improvement because of the limitations of silicon-based transistors. Recently, Amorphous Indium Gallium Zinc Oxide (a-IGZO) has emerged as a promising alternative to traditional silicon-based channels [1], [2]. This material offers advantages in current 1T-1C DRAM technology, such as low power consumption due to its significantly lower leakage current compared to Si [3]. However, the weak thermal stability of a-IGZO [4], [5] poses a challenge when integrating an a-IGZO channel TFT with a DRAM cell capacitor [6] because the high-k capacitor dielectric requires a crystallization process at a high temperature to achieve a sufficiently high k-value.