Ozone-Based Atomic Layer Deposition of HfO 2 and Hf x Si 1-x O 2 and Film Characterization
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Ozone-Based Atomic Layer Deposition of HfO2 and HfxSi1-xO2 and Film Characterization Yoshihide Senzaki*, Seung Park AVIZA Technology 440 Kings Village Road, Scotts Valley, CA, 95066, USA Douglas Tweet, John F. Conley Jr., and Yoshi Ono SHARP Laboratories of America, 5700 NW Pacific Rim Blvd., Camas, WA, USA Abstract: New ALD processes for hafnium silicate films have been developed at Aviza Technology by co-injection of tetrakis(ethylmethylamino)hafnium and tetrakis(ethylmethylamino)silicon precursors. Alternating pulses of the Hf/Si precursor vapor mixture and ozone allow process temperatures below 400ºC to grow HfxSi1-xO2 films. Film characterization, including film density, crystallinity, and thermal anneal effect, was performed on five 20 nm thick HfxSi1-xO2 films where x = 0.2, 0.4, 0.6, 0.8, 1.0. X-ray measurements revealed the film densities and thicknesses for the as-deposited and 1000°C annealed samples. The densification with anneals seen in the optical measurements were confirmed. The as-deposited amorphous HfO2 and Hf0.8Si0.2O2 were crystallized after a 600°C anneal. The HfO2 formed the well known monoclinic phase while the silicate formed a face-centered-cubic (fcc) structure. This fcc phase has only recently been mentioned in the literature [1]. Introduction: As the integrated circuit device scale approaches the 65 nm node, the need for high-k gate dielectrics to replace SiO2 is rapidly increasing. Conventional SiO2 gate dielectrics suffer from leakage and reliability deficiencies as the silicon oxide thickness decreases below 2 nm. There is a growing need for high-k gate dielectric materials that are thermally stable with Si and provide good electrical properties. Metal oxides such as HfO2, ZrO2, and the silicate forms of these materials have been studied as promising alternative candidates to SiO2. A good high-k material preferably remains amorphous during thermal processing to prevent grain boundary formation which induces leakage current [2]. Numerous liquid precursors have been investigated for metal-organic chemical vapor deposition (MOCVD). Liquid precursors are preferred over solid precursors for accurate chemical delivery to the process chamber where solid precursors suffer from inconsistent surface area with time of delivery. Metal dialkylamide compounds are of particular interest due to versatility in applications for both high-k metal oxide and conductive metal nitride deposition [3]. MOCVD of high-k metal oxides such as Ta2O5 [4], ZrO2 [5], HfO2 [6], ZrSiOx [7], and ZrSnTiOx [8] has been explored using liquid metal amide precursors. Thickness control of high-k films is critical to ensure good performance for IC device applications. ALD is a self-limiting surface-controlled reaction and provides precise thickness control as the film grows linearly with the number of alternating pulse cycles of precursor and reactant gas [9]. Previous hafnium silicate ALD studies focused on sequential delivery of Hf and Si precursors to form nanolaminate films (an alternating stack of HfO2 and SiO2 la
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