A feasibility study of using Ta-Co-N ternary thin film as diffusion-barrier and catalytic layers for copper processing

• Main Authors: Yen-Wei Lin, 林彥瑋
• Other Authors: GSChen
• Format: Others
• Language: zh-TW
• Published: 2002
• Online Access: http://ndltd.ncl.edu.tw/handle/by3q32

碩士 === 逢甲大學 === 材料科學所 === 90 === Abstract Thin film of Co and Co-N were sputter deposited at different nitrogen / argon gas pressure ratios on (100) silicon substrates which did not heat (room temperature) and heat with 300 ℃. The properties of these films, particularly electric conductivity, microstructure and phase transition were explored using x-ray diffractometry (XRD), electric resistance measurement, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). On the unheated substrates, we can deposit: HCP (a-Co), FCC (Co4N) and mix with few a-Co, orthorhombic (Co2N), FCC (CoN) and mix with few Co2N along with the increase nitrogen/argon gas pressure ratios. In the same pressure condition but heating with 300 ℃, we can deposit: HCP (a-Co), HCP(Co3N) and mix with few FCC(β-Co), Co2N and mix with fewβ-Co, CoN and mix with few Co2N andβ-Co (in which, Co3N and β-Co are thermal decomposition with two reaction which are Co4N Co3N + β-Co and Co2N CoN +β-Co). Electric resistivities and microstructure of thin films are difference, among them electric resistivities lie in between 200 to 900 mW-cm (It is dependent on substrate heating or not heating and the nitrogen concentrations of stoichiometry). The traditional XRD showed a few and weak diffraction pattern, so could not identify the crystal structure or the kind of the phase. We can prove the phase transition, thermal decomposition reaction and the change of grain size with the TEM Selected-area diffraction pattern. The increasing of the nitrogen pressure would cause grain refinement. In order to understand the phase transition of thermal decomposition reaction. We annealed Co3N, Co2N and CoN which deposited with 300 ℃ under high temperature range (400-700 ℃) and were analyzed by using grazing incident XRD. It showed that they have the similar phase transition and the same material under 700 ℃. They were CoN andβ-Co that formed by thermal decomposition from Co3N and Co2N. Additionally, the use 20 nm-thick Co3N, Co2N and CoN thin film as diffusion barriers between silicon and copper were evaluated by sheet resistance measurement, grazing incident XRD and SEM to examine Si/Co-N/Cu sample after annealing under high temperature range (350-600 ℃). Result, based on sheet resistance measurement, grazing incident XRD and SEM, showed that the three samples yield a threshold temperature for electrical failure and the formation of Cu3Si at 500 ℃. The situation should be cased by the thermal decomposition. Thin films of Co4N, Co4N/Co2N and Co2N all could catalyze copper. Co4N surface could deposit a good adhesion and complete copper film. Although Co2N have catalytic ability, it had poor adhesion with copper film and peel off easily. Finally, We will take the catalytic capability of Co-N and the against diffusion of Ta-N, intend to manufacture the Ta-Co and Ta-Co-N alloy thin film that could be as diffusion-barrier and catalytic layers for copper processing.