| 摘要 |
PURPOSE: A method for forming an interconnection of an SRAM device using damascene processing is provided to be capable of removing recess of tungsten by controlling the polishing selectivity of an oxide layer and a tungsten film. CONSTITUTION: An etch stop layer(23') is formed on a wafer(21) having the first metal line(22). After forming an insulating layer(24') on the resultant structure, a trench is formed by selectively etching the insulating layer and the etch stop layer. A tungsten film is filled into the trench and planarized by the first and second CMP, thereby forming the second metal line(26''). At this time, the first CMP is used to slurry having pH of 1-4 and adding hydrogen peroxide of 2-6 weight percent. Also, the second CMP is added hydrogen peroxide of 2 weight percent below to the slurry, thereby removing the recess of the tungsten film.
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