Browsing by Author "Chin, B"

Now showing 1 - 4 of 4

Four-dimensional dielectric property image obtained from electron spectroscopic imaging series
(2001)
Lo, SC
;
Kai, JJ
;
Chen, FR
;
Chang, L
;
Chen, LC
We have demonstrated a new quantitative method to characterize two- dimensional distributions of energy-dependent dielectric function of materials from low loss electron spectroscopic image (ESI) series. Two problems associated with extracted image-spectrum from the low-loss image series, under-sampling and loss of energy resolution, were overcome by using fast Fourier transformation (FFT) interpolation and maximum entropy deconvolution method. in this study, Black Diamond(TM)/Si3N4/SiO2/Si-substrate dielectric layer designed for copper metallization was used as the sample. We show that the reconstructed (FFT interpolated and maximum entropy deconvoluted) image-spectrum obtained from ESI series images can be quantified with the same accuracy as conventional electron energy-loss spectroscopy spectra. Since the analysis of the dielectric function is sensitive to the local thickness of the specimen using Kramers-Kronig analysis, we also developed a new method to quantitatively determine the dielectric constant for low-k materials. We have determined the thickness of the Black Diamond using the extrapolated thickness method from the materials of known dielectric constants. Using Kramers-Kronig formula, the dielectric function map can be deduced front two-dimensional reconstructed single scattering spectra with providing the information of thickness. We proposed a four-dimensional data presentation for revealing the uniformity of the energy dependent property. The accuracy of our methods depends on the thickness determination and on the quality of the reconstructed spectra from the image series.
HRTEM and EFTEM studies of the evolution of Cu/Ta/SiO2/Si interfaces in ULSI devices
(1999)
Yin, KM
;
Chang, L
;
Chen, FR
;
Kai, JJ
;
Chuang, CCCG
The Cu/Ta/SiO2/Si films have been annealed at temperatures from 500 degreesC to 600 degreesC in various vacuum conditions. Transmission electron microscopy has been used to characterize the microstructure of the films after annealing. It shows that different thicknesses of amorphous interlayer were formed between Cu and Ta under various vacuum conditions. Energy dispersive spectroscopy confirmed this interlayer to be tantalum oxide. It has also found that tantalum oxidation is caused by oxygen from the outside atmosphere diffusing along grain boundaries in copper films.
Oxidation of Ta diffusion barrier layer for Cu metallization in thermal annealing
(2001-06-01)
Yin, KM
;
Chang, L
;
Chen, FR
;
Kai, JJ
;
Chiang, CC
This work examines the thermal stability of Ta barrier layer for Cu metallization with the effect of oxygen. The Cu/Ta/SiO2/Si films were annealed at temperatures ranging from 400 to 600 degreesC under various vacuum conditions. Transmission electron microscopy has been performed to characterize the microstructure of the films after annealing. The results show that an amorphous interlayer of oxide between Cu and Ta can be formed at 400 degreesC in a vacuum of 10(-2) mbar. X-Ray energy dispersive spectroscopy and electron energy loss spectroscopy confirm that this interlayer is tantalum oxide. This interlayer transformed into a crystalline phase of Ta-Cu oxide at 600 degreesC. In addition, formation of tantalum oxide interlayer is more thermodynamically favorable than that of copper oxide layer at the Cu/Ta interface. Growth of the amorphous interlayer is atmosphere-dependent, as evidenced by the thickness of tantalum oxide being decreased with better vacuum or argon gas. This observation suggests that the oxidation source may arise from the annealing atmosphere rather than from interior SiO2. Furthermore, it has been observed that oxygen diffuses along grain boundaries in copper films to cause tantalum oxidation. (C) 2001 Elsevier Science B.V. All rights reserved.
The effect of oxygen in the annealing ambient on interfacial reactions of Cu/Ta/Si multilayers
(2001-06-01)
Yin, KM
;
Chang, L
;
Chen, FR
;
Kai, JJ
;
Chiang, CC
Interfacial reactions of Cu/Ta/Si multilayers after thermal treatment were investigated using transmission electron microscopy. The Cu and Ta films were deposited onto Si wafer by ionized metal plasma technique. The samples were then annealed at 400, 500, 550 and 600 degreesC in purified Ar atmosphere for 30 min. The effect of oxygen in the atmosphere on the thermal stability is studied. An interlayer of Ta oxide was observed between Cu and Ta after annealing at 400, 500 and 550 degreesC. It is evident that oxygen as residual gas from furnace ambient can diffuse through Cu grain boundaries to form the Ta oxide layer. After annealing at 600 degreesC, Si reacted with Ta to form TaSi2 at the interface of Ta and Si, in the meantime Cu3Si with surrounding SiO2 formed in the Si substrate. The thermal stability of the Cu/Ta/Si samples was also examined in a two-step annealing treatment of 400 degreesC for 30 min, followed by 600 degreesC for 30 min. Even though interlayers of crystalline Ta-Cu oxide and Ta silicide were formed, Cu silicides were not observed. Formation of TaOx interlayer at the first stage of 400 degreesC annealing may inhibit Cu diffusion into the Si substrate in the second stage of the 600 degreesC annealing process. (C) 2001 Elsevier Science B.V. All rights reserved.