PURPOSE: To prevent failure due to coating unevenness by dripping a liquid for forming an SOG (spin-on-glass) film on a semiconductor substrate where an SiO2 ground film is formed and then judging if a spread diameter D per dip (approximately 0.005ml) is equal to or longer than 6.5mm.

CONSTITUTION: A liquid for forming an SOG film is dripped on a semiconductor substrate where an SiO2 ground film is formed and a spread diameter D per drip (approximately 0.005ml) is measured for judging if D is equal to or longer than 6.5mm, where the liquid for forming the SOG film generally consists of alkyl silanol and an organic solvent and the concentration of alkyl silanol is normally 5 - 20%. Also, it is desirable that a semiconductor substrate which is used for evaluating performance of liquid for forming the SOG film should be equal to what coats solution actually. The solution for forming the SOG film is dripped from a location which is approximately 3 - 5mm above onto the semiconductor substrate and the diameter D can be measured by slide calipers.