New Single-Source Precursors for the MOCVD of High-κ Dielectric Zirconium Silicates to Replace SiO2 in Semiconducting Devices

• Published in: Chemical vapor deposition Vol. 8; no. 4; pp. 171 - 177
• Main Authors: Zürcher, S., Morstein, M., Spencer, N. D., Lemberger, M., Bauer, A.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag GmbH 01.07.2002; WILEY‐VCH Verlag GmbH; Wiley-VCH
• Subjects: Chemical vapor deposition (including plasma-enhanced cvd, mocvd, etc.); Chemical vapor deposition metal-organic (MOCVD); Cross-disciplinary physics: materials science; rheology; Dielectrics; Exact sciences and technology; Materials science; Methods of deposition of films and coatings; film growth and epitaxy; Physics; Precursor; Silicates; Zirkonium; Inorganic compounds; Dielectric materials; Transition element compounds; Operating mode; Thermodynamic stability; Crystallinity; Crystal growth from vapors; Leakage currents; Experimental study; MOCVD; Precursor; Characterization; CV characteristic; Thin films; CVD; Solid solutions; Silicon oxides; Zirconium oxides; MOS capacitors; Chemical composition; IV characteristic; Current density
• ISSN: 0948-1907; 1521-3862
• DOI: 10.1002/1521-3862(20020704)8:4<171::AID-CVDE171>3.0.CO;2-Z

Two new single‐source zirconium silicate precursors Zr(acac)2(OSiMe3)2 A, and Zr(acac)2(OSitBuMe2)2 B, have been synthesized. The stability and vapor pressure of the two compounds were investigated. They have been used to deposit films of Zr1−xSixO2 by metal–organic (MO)CVD in the temperature range 400–700 °C. Zirconium silicate films with very low carbon contamination and silicon content, x, in the range 0.05–0.25 have been obtained. The two precursors differ, by a factor of two, in activation energy for the MOCVD of films (63 kJ mol−1 for A, and 145 kJ mol−1 for B), and differential scanning calorimetry (DSC) shows they have quite different decomposition temperatures. The film composition was determined by X‐ray photoelectron spectroscopy (XPS) and the crystallinity of the layers was studied by X‐ray diffraction (XRD). Preliminary electrical characterizations of the zirconium silicate films were conducted on MOS capacitors with Al as gate electrodes. The experiments exhibit the generation of negative charges in the layers during the measurements, shown by a large hysteresis in the CV curves and a shift of the IV curves from the first to the following measurements. Low leakage current densities in the lower voltage regime are observed. Two single‐source MOCVD precursors for depositing zirconium silicates have been synthesized. The volatile and stable precursors are used to deposit Zr1−xSixO2 in the wide temperature range of 400 to 700 °C. Films deposited below 525 °C are amorphous; at higher temperatures, nanocrystalline cubic ZrO2 in a matrix of Zr1−xSixO2 is deposited. No phase transitions are observed by annealing at 1000 °C. XPS analysis shows very low carbon contamination. Preliminary electrical characterization on MOS capacitors shows a build‐up of negative charges during CV and IV measurements. The dielectric constant is found to be 9 compared to 3.9 for SiO2.