Method of forming interconnect

A method of forming an interconnect, comprising the steps of:

• a) forming a through hole in an insulating film over a substrate;
• b) depositing a photosensitive masking material over the insulating film as well as inside the through hole;
• c) patterning the masking material, thereby forming a mask pattern, which has an opening located over the through hole and is used to define a trench;
• d) etching the insulating film to a predetermined depth using the mask pattern, thereby defining a trench pattern, which is linked to the through hole, in an upper part of the insulating film;
• e) filling in the through hole and the trench pattern with a conductive material;
• and
• f) defining the mask pattern so that no remaining part of the masking material, which has been filled in the through hole, will reach a level higher than the bottom of the trench pattern, the step f) being performed before the step d).