Method for forming ultra fine contact holes in semiconductor devices

A method for forming an ultra fine contact hole in a semiconductor device with use of a KrF light source, the method comprising:

• forming a KrF photoresist pattern on an insulation layer disposed on a semiconductor substrate, the KrF photoresist pattern exposing a predetermined region of the insulation layer for forming a contact hole in the insulation layer;
• forming a chemically swelling process (CSP) layer by depositing a chemical material-containing layer that is reactive to the KrF photoresist pattern on an entire surface of the photoresist pattern and insulating layer;
• forming a chemical material-containing pattern encompassing the KrF photoresist pattern by reacting the chemical material-containing layer with the KrF photoresist pattern through the chemically swelling process to decrease a critical dimension of the contact hole;
• rinsing the semiconductor substrate;
• and
• increasing a thickness of a sidewall of the chemical material-containing pattern to a predetermined thickness by performing a resist flow process (RFP) that makes the chemical material-containing pattern flow decrease the critical dimension (CD) of the contact hole.