Preparation and Properties of Pyrolytic Zirconium Dioxide Films

Abstract

Zirconium dioxide (ZrO2) films in the thickness range of 500-8000A havc been prepared by chemical vapor deposition in the temperature range of 800 ~ 1000~ The films were identified as fine-grained (~325A), nearly stoichiometric, monoclinic ZrO2, using electron microprobe analysis, infrared absorption, and transmission electron microscopy. The films exhibited r e m a r kable resistance to most aqueous acids and bases, although slight etching occurred in hot (220~ phosphoric acid. The deposits had an index of refraction of 2.1 -+ 0.1 at 546 nm and an optical energy gap of 5.12 eV. ZrO2 deposited on silicon offered little resistance to Na diffusion at 600~ while films deposited on thermal SiO2 were a good barrier due to pile-up of the Na near the ZrO2/SiO2 interface. The current density, J, depended on the field, E, as J -~ A E n, where n was 6 for the metal biased negatively and 2.75 or 5, depending on the magnitude of the field, for the opposite polarity. The dielectric constant in the frequency range of 5 x 10 S to 1 x l0 s Hz was relatively independent of frequency near 300~ and equal to approximately 18, however some dispersion was noted near 573~ The a-c conductivity could be represented by =ac ~ Cy~ where 5 is the measuring frequency and ~ a temperature dependent parameter, decreasing from ~1 at 300~ to ~0.5 at 573~ The dielectric strength of the films varied between 1 to 2 x 106 V/cm, independently of thickness and polarity. High frequency (1 MHz) C-V measurements indicated the presence of negative surface charge, which varied between --6 x 10 n to --1 x 1012 cm -2. The structures exhibited instability under negative bias, indicative of negative charge being injected into the insulator. C-V measurements on the double dielectric system (ZrO2/SiO2) showed that the presence of ZrO2 caused a flatband voltage displacement ~ +0.8V. In addition, the flatband voltage shifted as a function of time under negative bias and was found to obey the relationship aVFB -'-K log t.Recent developments in microelectronics, such as integrated circuit passivation and IGFET technology, have engendered extensive research in the preparation and characterization of insulating thin films (1). Much of the effort has been directed to SiO2, SlaY4, and Al203. Recently, alternatives to these materials have been sought. TiO2 (2) and Nb205 (3) have been investigated. It has been found that chemical vapor deposition (CVD) in the temperature range of 600 ~ 1000~ produces films with the most desirable properties for the above applications.A refractory oxide that has not been investigated in detail is zirconium dioxide (ZrO2). T h i s material is characterized by low electrical conductivity and extreme chemical inertness. Much of the information available on ZrO2 has been obtained on relatively impure bulk, sintered material. This paper reports on the preparation of ZrO2 films by CVD, and a survey of the optical, chemical, electrical, and interfacial properties of the resulting films. Film PreparationThe preparation of oxide films by CVD has been...

Deposition of Lanthanum Zirconium Oxide High‐k Films by Liquid Injection ALD and MOCVD

“…A wide variety of Zr precursors have been investigated in MOCVD and ALD, including ZrCl 4 , [31,32] [Zr(OR) 4 ], [33] [Zr(thd) 4 ], [34] [Zr(NR 2 ) 4 ] (R = Me, Et), [35,36] [Zr(NO 3 ) 4 ]. [37] However, all have various problems associated with them (e.g., impurity incorporation, low reactivity, low thermal stability) and none have proved suitable for dual application in ALD and MOCVD.…”

MOCVD and ALD of High‐k Dielectric Oxides Using Alkoxide Precursors

“…[2] However, the MOCVD of ZrO 2 and HfO 2 has been hindered by problems associated with existing Zr and Hf oxide precursors. For instance, ZrCl 4 [28] and HfCl 4 [29] are low-volatility solids which need substrate temperatures of 800°C and above for oxide deposition, and there is the possibility of chloride contamination in the films. [30] and the oxide films are often heavily contaminated with carbon.…”

“…[61] The [26][27][28][29][30], and have good thermodynamic stability on silicon, making them attractive materials for high-j dielectric applications. [2] Another attractive feature of some rare-earth oxides, such as Pr 2 O 3 and Gd 2 O 3 , is their relatively close lattice match to silicon (e.g., a(Gd 2 O 3 ) = 10.812Å; 2a(Si) = 10.862Å), which offers the possibility of epitaxial growth, thereby eliminating problems related to grain boundaries in polycrystalline films.…”

Growth and Properties of TiCl4‐Derived CVD Titanium Oxide Films at Different CO2/H2 Inputs

“…In this study, the ratio V(CO 2 )/V(H 2 ) had an effect on the deposition, indicating that CO 2 and/or H 2 are involved in the growth kinetics. Conventionally, the formation of oxide films such as Al 2 O 3 , [14,15] ZrO 2 , [16] and TiO 2 , [12] deposited by using the metal chloride (AlCl 3 , ZrCl 4 , and TiCl 4 )/CO 2 /H 2 systems at temperatures above 700 C involve water formed by hydrogen reduction of CO 2 , or the water gas shift reaction. The reactions of TiO 2 via the hydrolysis reaction are given below.…”