Single-oriented thin film interconnects in LSI technology prepared based on the epitxial relationships

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Metal/semiconductor contacts with a stacking structure consisting of a single oriented thin film of interconnects on a single oriented diffusion barrier deposited on Si are developed. The contacts of (1) Al (001)/YSi_<2-x>/Si (001), (2) Cu (111) /W (110) /Si(100), (3) Cu (110) /ZrN (100) /Si (100), (4) Cu (111) /Ta-W (110) /Si (100), and (5) Al (111) /Ta-W (110) /Si (100) are successfully prepared. The epitaxial growth of each layr in the contact of (1) and the oriented layrs in those of (2) - (5) are confirmed by x-ray diffraction and transmission electron microscopy. The contact of (1) fails due to the formation of Al_3Y compound upon annealing for 1 h at temperatures over 450ﾟC.Since the epitaxial relationships restrict the combination of materials used in the contacts, the thermal stability is not always compatible with the formation of epitaxial contacts. The contacts with single oriented layrs, on the other hand, are stable upon annealing at high temperatures. The [110] oriented W barrier is consumed by a uniform silicidation reaction, and the contact is sable upon annealing at 690ﾟC for 1 h, while the polycrystalline W barrier fails before the silicidation reaction occurs. The ZrN barrier is stable upon annealing at 750ﾟC,but fails due to re-crystallization upon annealing at 800ﾟC.The solid solution of Ta-W barrier shows an excellent barrier property as compared with each component barrier. The Ta_<0.5>W_<0.5> barrier is the most stable among alloys with different compositions, which tolerates upon annealing at 700ﾟC.The [111] texture of Al is grown on the Ta-W barriers, and is useful for the electromigration torelant contacts.