Semiconductor device having a copper metal line and method of forming the same

A method of forming a copper metal line of a semiconductor device, the method comprising the steps of:

• forming a capping layer and an intermetal dielectric layer in a stacked configuration over a substrate in which lower lines are formed;
• forming trenches, defining an upper metal line region, on the intermetal dielectric layer through etching employing a first photoresist pattern;
• forming a spacer on inner sidewalls of the trenches;
• forming a second photoresist pattern for exposing a first one of the trenches while covering a second one of the trenches and performing etching so as to remove the intermetal dielectric layer exposed by the spacer, thereby forming a via under the exposed first trench;
• removing the spacer;
• forming a barrier metal film on inner walls of the trenches and the via;
• and
• gap-filling a copper metal line film within the trenches and the via and polishing a surface of the semiconductor device.