| 摘要 |
PURPOSE: A method for forming metal wirings of a semiconductor device is provided to prevent a diffusion of copper atoms into an insulating layer and thereby to improve electrical characteristics of the device. CONSTITUTION: A lower barrier metal layer(2), a metal wiring layer(3) of copper, an upper barrier metal layer(4), and a planarizing layer(5) are successively formed on an insulating layer(1). Next, a photoresist layer is deposited on the planarizing layer(5) and then patterned. The planarizing layer(5) is selectively etched through the patterned photoresist layer. Next, under a temperature of more than 250°C, the lower and upper barrier metal layers(2,4) and the copper wiring layer(3) are etched by using the etched planarizing layer(5) as a mask. Subsequently, sidewalls of the copper wiring layer(3) are overetched with etching gas containing very small amount of oxygen. Then oxygen and nitrogen in the etching gas and the insulating layer(1) react with copper in the wiring layer(3), and thereby a protective layer(7) of silicon nitride oxide is formed on sidewalls of the copper wiring layer(3). The planarizing layer(5) is then reflowed in a temperature of 700 to 900°C, and therefore wholly covering the copper wiring layer(3).
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