In-situ Analysis of HfO2 Formation of Remote Plasma Atomic Layer Deposition Process

Abstract

High dielectric constant materials are recently attracted for alternative gate dielectric application in sub-0.1 ㎛in metal-oxide-semiconductor (MOS) devices due to its thermodynamical stability on silicon, a high dielectric constant, a high breakdown field, and a large band gap. Among the several high dielectric constant materials, HfO$_{2}$ gate oxide has been focused to study to increased during recent years due to its high dielectric constant and good thermal stability in contact with silicon. We investigated the HfO2 gate dielectric material deposited by remote plasma enhanced atomic layer deposition (PEALD) method. HfO2 films were deposited at 200~350$^{\circ}$C using tetrakis-dimethyl-amino- hafnium (TDEAH) as Hf precursor and oxygen plasma as reactant gas. In this study, in-situ analysis system is constructed and is connected with remote PEALD system. We deposited HfO2 with this system and thickness of HfO2 was controlled by the number of deposition cycle. One cycle of HfO2 deposition consists of Hf precursor supply and O2 or O2 plasma supply. Each step of one cycle was monitored by in-situ XPS (X-ray photoemission spectroscopy) and AFM (atomic force microscopy). We observed XPS peak related with silicate grown from the first cycle of plasma enhanced ALD process. But no silicate peak was observed with O2 supply of normal ALD process. After growing HfO2, the electrical properties of HfO2 of MOS capacitor were measured. The physical and chemical characteristics of HfO$_{2}$ film were analyzed by cross-sectional transmission electron microscope (XTEM), Auger electron spectroscopy (AES), XPS. The electrical properties and reliability characteristics including EOT, hysteresis, leakage current and capacitance were evaluated by I-V and C-V measurements. This paper will present the characteristics and in-situ surface analysis of HfO$_{2}$ gate dielectric deposited by remote PEALD using metal organic precursor.