The damascene process for copper interconnects

Metal wiring is necessary to electrically connect the many individual elements of an integrated circuit. Metallization technology has evolved along with other advances in integrated circuit fabrication. Aluminum and its alloys were the standard choice for metallization in integrated circuits for 

In ULSI devices, multilevel metallization is required. As a result, the first-formed interconnect lines may undergo several thermal cycles between room temperature and about 400 °C as subsequent layers of metallization are formed. This temperature range is dictated by the fact that the deposition of the passivation layer is commonly done at about 400 °C. 

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