In-Line observation and classification of water marks after the drying process was investigated with regard to the wettability of wafers and the drying methods applied. The formation of water marks was observed with a KLA wafer inspection system and a particle scanner on different hydrophilic and hydrophobic wafers with and without patterns. The wafers were spun and IPA vapor dried as a function of the air exposure time. The hydrophilic wafers did not create any water marks with either spin or vapor dries. The air exposure time and dry method are much more sensitive with the hydrophobic surfaces in creating water marks. The spin dry of hydrophobic wafers created a large quantity of water marks independent of the air exposure time. Homogeneously hydrophilic or hydrophobic wafers with and without patterns did not create any water marks following the vapor drying of wafers. However, the patterned wafers with both hydrophobic and hydrophilic sites created water marks even in IPA vapor dry. This indicates that the wettability and drying method of the wafer play an important role in creating water marks in semiconductor wet processes.