Browsing by Author "Yin, KM"

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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.
The effect of oxygen on the interfacial reactions of Cu/TaNx/Si multilayers
(2001-08-01)
Yin, KM
;
Chang, L
;
Chen, FR
;
Kai, JJ
;
材料科學與工程學系
Interfacial reactions of Cu/TaNx/Si and silicon nitride/Cu/TaNx/Si multilayers after thermal treatment at 500 and 700 degreesC under an ambient with residual oxygen were investigated using an energy-filtered TEM (EFTEM). The Cu and TaNx films were deposited onto the Si (0 0 1) wafer by ionized metal plasma (IMP) technique. An interlayer of TaOxNy was observed between Cu and TaNx diffusion barrier in the Cu/TaNx/Si sample after 500 degreesC annealing. It is evident that oxygen diffused through the Cu grain boundaries and promotes the oxidation of the Ta nitride barrier layer to form the TaOxNy. It is also found that the as-deposited TaNx (x similar to 0.5) film with nano-crystalline microstructure would transform into Ta2N structure with large grain character after 500 degreesC heat treatment. After 700"C annealing, not only the TaNx barrier layer transformed into Ta2N but the silicidation of Cu to Cu5Si and TaNx to Ta5Si3 occurred. However, no TaO(x)Ny interlayer was observed. This may result from the preferable oxidation of Cu3Si that may suppress the oxidation of TaNx. Nevertheless, in the silicon nitride capped (silicon nitride/Cu/TaNx/Si) case, there was no TaOxNy interlayer observed in the 500 degreesC annealed specimen. And the interfacial reaction in the silicon nitride/Cu/TaNx/Si annealed specimen at 700 degreesC also showed much less severe extent than the sample without capping. Experiments show that the oxygen in the ambient enhances the oxidation at 500 degreesC and silicidation at 700 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.