An Advanced High-k Transistor Utilizing Metal-Organic Precursors in an ALD Deposition of Hafnium Oxide and Hafnium Silic
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D2.4.1
An Advanced High-k Transistor Utilizing Metal-Organic Precursors in an ALD Deposition of Hafnium Oxide and Hafnium Silicate with Ozone as Oxidizer J. Gutt1, G.A. Brown1, Yoshi Senzaki2, Seung Park2 1
International SEMATECH, Austin, TX, 78741, USA Tel: (512) 356-7197, e-mail:
[email protected]; 2Aviza Technology, Scotts Valley, California 95066
Abstract The International Technology Roadmap for Semiconductors (ITRS) has projected that continued scaling of planar CMOS technology to the 65nm node and beyond will require development of high-k films for transistor gate dielectric applications to allow further scaling of overall device sizes according to Moore’s Law [1]. Researchers have recently been studying hafnium-based high-k dielectrics as an alternative to SiO2 [2]. The method of deposition of these films has been found to impact the applicability of the films for both low standby power and high performance applications [3]. Atomic Layer Deposition (ALD) has been among the more widely studied deposition techniques for these films, but previous work has emphasized ALD utilizing inorganic precursors [4]. In this paper, we shall describe a process in which hafnium oxide and hafnium silicate films were deposited from alternating pulses of volatile metal-organic Hf/Si liquid precursors and ozone on 200mm diameter Si substrates using a single wafer ALD system. Electrical characterization of the films is presented, including equivalent oxide thickness (EOT), gate leakage, and electron mobility data, showing an achievement of EOT’s ranging from 1.19 to 1.69 nm with high field mobilities from 74% to more than 90% of that of SiO2 (2.1 nm film), and Jg in the range of 80mA to 3 A/cm2.
Introduction Recent interest in HfO2 as a high-k gate dielectric has extended to incorporation of Si to aid in retaining desirable scaling properties of the high-k film (low leakage and EOT) while enhancing/maintaining electrical characteristics of the device (Idsat, mobility). ALD has proven to be a technique that can provide high quality films with excellent control of deposition properties (uniformity, composition), but has not previously been effective for deposition of hafnium silicates. Recent advances in equipment technology by Aviza Technology, Inc. have provided the capability for ALD to deposit HfxSi(1-x)O films of varying compositions from volatile metal-organic precursors. The authors have fabricated devices using these films that are suited to meet the requirements of scaled transistors as outlined in the ITRS.
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Experimental Details The devices used in this study were fabricated on p-type 200mm epitaxial Si wafers. Table 1 summarizes the fabrication flow of the 40 at% Hf-silicate and hybrid HfO2/Hf-silicate NMOS devices. Prior to high-k deposition, all wafers were pretreated in an effort to provide a higher quality interface with the active channel. These pretreatments were either HF-last clean followed by anneal in NH3, or an ozone-based wet process. An Aviza Technology PantheonTM single-wafer ALD system was
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