Improvement of dielectric properties of ZrO<inf>2</inf> films prepared by limited reaction sputtering

Abstract

t blIP a e . rocess parameters Parameters Values Oz concentration 2% Sputtering power 80W Substrate temperature 400-700°C Working pressure 5mTorrsuppressed. In the present paper, crystalline ZrOz thin films were prepared on Si (100) substrate by the limited reaction sputtering system. The results suggest that the crystalline phases have strong influences on the CooV performance, and the oriented tetragonal zrO z shows a permittivity as high as 32. ExperimentsThe substrates, p-type Si(100) wafers with p=0.6-1.2n·cm, were cleaned through conventional RCA cleaning process, and then dipped in 1% diluted HF solution for about 30 s to leave an H-terminated surface. ZrOz thin films with thickness of 1Onm--l OOnm were deposited by the limited reaction sputtering system. The detailed process parameters are listed in Table 1. AbstractWe investigated the growth of crystalline ZrOz film prepared on p-Si( 100) by limited reaction sputtering system under different growth temperatures from 400 to 700°C. The structural characteristics of the samples were studied by XRD, RHEED and AFM, which provided a solid identification of the phase transformation from monoclinic phase to tetragonal phase. The dielectric properties were studied by CooV and I-V measurements on Au/ZrOz/pooSi(100) MIS structures, suggesting that the tetragonal ZrOz thin film shows excellent dielectric performances including a high permittivity up to 32 as well as a negligible flatband voltage shift in CooV curves.

Improved Dielectric Properties of Tetragonal ZrO2 Gate Dielectric Fabricated by Ozone-Assisted Sputtering

“…However, the (200) peak shifts to 35.3 in the sample prepared at 700 C, which indicates the growth of the tetragonal phase. 10) As reported previously, 8) tetragonal ZrO 2 was fabricated using this sputtering system without ozone. From the XRD results, the introduction of ozone seems not to affect the growth of a tetragonal phase.…”

“…Fiorentini and Gulleri performed some interesting simulations, which indicate that a tetragonal phase against monoclinic distortions may be obtained in the epitaxial growth of ZrO 2 . 7) To prevent the structural and chemical modification of the Si substrate or film surface by the bombardment with energetic species from plasma, we have been investigating a sputtering technique named ''limited reaction sputtering'', 8) in which metal sputtering and oxidation deposition are separated. Owing to the suppressed oxidation of the Si substrate, epitaxial tetragonal ZrO 2 with a permittivity of about 32 has been reported in this technique.…”

“…Owing to the suppressed oxidation of the Si substrate, epitaxial tetragonal ZrO 2 with a permittivity of about 32 has been reported in this technique. 8) However, asdeposited films suffers from a large density of oxygen vacancies, 9) which results in frequency dispersion, uncontrollable flatband voltage, and large loop hysteresis. In the present work, we report the epitaxial growth of tetragonal ZrO 2 films by ozone-assisted sputtering.…”

“…There is no evident flatband voltage shift, only a small loop hysteresis in the forward-reverse C-V curves for the sample prepared at 700 C, which is much smaller than that of the sample prepared without ozone assistance. 8) Therefore, the ozone-assisted epitaxial growth suppresses the oxygen vacancy-induced band bending of Si. Moreover, all the samples show frequency dispersions in the accumulation and depletion region in the C-V curves.…”