apparatus and method are provided for improved washing and drying of semiconductor wafers utilizing an enhanced &# 34 ; marangoni effect &# 34 ; flow of liquid off of the wafers for superior prevention of watermarks on integrated circuits on the wafers . the apparatus includes a housing 12 which may be hermetically sealed , an open - top wash tank 60 within a lower part of the housing , a moveable rack 16 for holding the wafers either in the tank for washing or in an upper part of the housing for drying , apparatus 34 for supplying chilled de - ionized water to a lower part of the tank , the diw flowing within the tank and overflowing the top thereof , a pump 20 for draining overflowing diw from the housing , and apparatus 40 for supplying to the housing organic vapor such as isopropyl alcohol in a dry gas such as nitrogen . during wafer drying operation of the apparatus the pressure within the housing is kept at about one torr or less .