Deposition and Plasma Measurements of Zr-Oxide Films with Low Impurity Concentrations by Remote PEALD Ju Youn Kim, a Seok Hoon Kim, a Hyungtak Seo, b Jung-Hyung Kim, c and Hyeongtag Jeon a,z a Hanyang University, Division of Materials Science and Engineering, Seoul 133-791, Korea b Department of Electrical and Computer Engineering, North Carolina State University, Raleigh, North Carolina 27695-7911, USA c Korea Research Institute of Standards and Science, Center for Vacuum Technology, Daejeon 305-306, Korea Zr-oxide film was deposited by remote plasma-enhanced atomic layer deposition PEALD and showed relatively low impurity contamination. In the Zr-oxide film deposition process, the plasma diagnostics were performed to investigate the effects and characteristics of O 2 remote plasma. The carbon contents in Zr-oxide film were decreased with increasing rf power. The electron density and optical emission of species were measured using cutoff and optical emission spectroscopy during the deposition. The electron density in O 2 remote plasma was about 7.8  10 9 to 2.1  10 10 cm -3 . The dominant emission species of O 2 remote plasma was the excited atomic and molecular oxygen. © 2005 The Electrochemical Society. DOI: 10.1149/1.1854773 All rights reserved. Manuscript submitted September 10, 2004; revised manuscript received November 4, 2004. Available electronically January 24, 2005. The field of advanced gate dielectric in semiconductor devices has currently gained considerable attention. Based on the interna- tional technology roadmap for semiconductors, the development of 60 nm metal oxide semiconductor field-effect transistors MOS- FETs is predicted by the year 2007. 1 Therefore, the conventional thermal oxide, SiO 2 , will face its physical and electrical limits be- cause of the high tunneling leakage current and low breakdown voltage problems when the thickness of SiO 2 is reduced below 1 nm. 2 The high dielectric constant materials such as ZrO 2 , HfO 2 , and Ta 2 O 5 , etc have been evaluated as a replacement for a SiO 2 as a gate dielectric to reduce the tunneling leakage current and to im- prove the reliability. 3-5 Among the high dielectric constant materials, ZrO 2 is considered as a potential candidate for the replacement of SiO 2 gate dielectric due to its high dielectric constant (  = 20-25), large band gap 5.8 eV and thermodynamical stability. 6,7 The ZrO 2 gate dielectric has been studied predominantly by using physical vapor deposition PVD, chemical vapor deposi- tion CVD, and atomic layer deposition ALD methods. Among these methods, ALD has the such advantages over other conven- tional deposition methods as excellent uniform thickness, low pro- cessing temperature, and precise film thickness control. 8 Remote plasma-enhanced atomic layer deposition PEALD has many ad- vantages, such as the wide process window, high film density, low impurity contents, and broad choice of precursor chemistry and/or reactants compared to the conventional ALD and metallorganic atomic layer deposition MOALD methods. 9 However, remote PEALD has the disadvantage of difficulty in understanding the re- action mechanism in the plasma process. The electron density and reaction species of plasma are very important to understanding the reaction of the plasma process. The electron density is a key param- eter for the understanding of plasma sources and plasma process. 10 The electron density was measured using the cutoff method. The cutoff method is a measurement method of electron density using a concept of wave cutoff at a plasma frequency and can be applied to any type of plasma. The optical emission spectroscopy OES, which is a diagnostic technique for the real-time monitoring of plasma process, has been used to investigate the reaction species for plasma process. 11 This method provides real-time analysis of O 2 remote plasma without disturbing plasma or interfering with the current process. In this study, we investigated the electron density and reaction species to understand reaction mechanism and charac- teristics of plasma process for Zr-oxide gate dielectric deposition. Experimental Zr-oxide films were deposited on p-type Si100 substrates by remote PEALD using Zr(N(C 2 H 5 ) 2 ) 4 as a Zr-precursor and oxygen remote plasma as a reactant gas source. Si substrates were cleaned by dipping in a piranha solution (H 2 SO 4 :H 2 O 2 = 4:1) for 10 min and then in a diluted HF solution (HF:H 2 O = 1:50) for 1 min to remove organic and native oxide, respectively. The downstream type remote PEALD reactor with 13.56 MHz rf power source has been used in this study. Figure 1 shows the schematic drawing of down- stream type remote PEALD system. Zr(N(C 2 H 5 ) 2 ) 4 was delivered from an external reservoir at 90°C and pulsed into the reactor using Ar carrier gas with the flow rate of 20 sccm. O 2 gas flow rate was fixed at 70 sccm and Ar purge gas flow rate at 100 sccm. The chemical reaction of Zr(N(C 2 H 5 ) 2 ) 4 pulse and O 2 remote plasma pulse made a basic one cycle in this experiment. Ar-purge gas was introduced for the complete separation of the precursor and plasma z E-mail: hjeon@hanyang.ac.kr Figure 1. Schematic of the downstream type remote PEALD system. Electrochemical and Solid-State Letters, 8 3 G82-G84 2005 1099-0062/2005/83/G82/3/$7.00 © The Electrochemical Society, Inc. G82