| 摘要 |
PURPOSE: A method for forming an alignment key of a metal wiring mask is provided to be capable of exactly aligning a via mask and the metal wiring mask while a metal film is over-polished. CONSTITUTION: An inter-metal dielectric(12) is formed on a lower metal line and planarized by CMP(Chemical Mechanical Polishing). An alignment key(14a) having topology is formed on the inter-metal dielectric. Via holes are formed in the inter-metal dielectric(12). A barrier metal film(18) and a metal film are sequentially filled into the via hole and planarized, thereby forming a plug(20). An upper metal line(22) is then formed on the plug. At this time, the alignment key(14a) is the same use in the step of forming the upper metal line(22).
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