Method of manufacturing semiconductor device

A method of manufacturing a semiconductor device, comprising the steps of:

• a) forming a first conductive layer comprising a metal on a semiconductor substrate;
• b) forming an interlayer insulating film on the first conductive layer;
• c) applying a first photoresist mask on the interlayer insulating film, the photoresist mask defining a hole;
• d) removing an exposed portion of the interlayer insulating film to form the hole exposing a part of the first conductive layer;
• e) ashing the first photoresist mask;
• f) forming a first protective layer on the first conductive layer by treating the resultant structure with a mixture consisting essentially of an organic acid having a carboxyl group and mixed with deionized water at a volume ratio of 1:0 to 1:100;
• g) after forming the first protective layer on the first conductive layer stripping the first photoresist mask;
• h) forming a contact plug by filling the hole with tungsten;
• i) forming a metal layer covering the upper surface of the interlayer insulating film and the contact plug;
• j) dry etching the metal layer using a second photoresist pattern as a mask to form a second conductive layer;
• k) ashing the second photoresist pattern;
• l) forming a second protecting layer on the contact plug and the second conductive layer by treating the resultant structure of the step (k) with a mixture consisting essentially of an organic acid having a carboxyl group and mixed with deionized water at a volume ratio of 1:0 to 1:100;
• and
• m) after forming the second protective layer on the contact plug and the second conductive layer stripping the second photoresist pattern.