METHOD OF CLEANING A SEMICONDUCTOR WAFER
The invention provides a method of cleaning the surface ( 3 ) of a wafer ( 1 ), comprising a hot rinse step in which the wafer ( 1 ) is at a temperature that is at least 100C higher than room temperature, the wafer ( 1 ) is rotated around an axis perpendicular to the wafer surface ( 3 ) and water is dispensed on the wafer surface ( 3 ). Thereafter a first drying step is performed in which the wafer ( 1 ) is rotated around the axis perpendicular to the wafer surface ( 3 ) and in which the humidity of the environment is such that the water on the wafer surface ( 3 ) is partially removed while the wafer surface ( 3 ) remains covered with a film of water ( 13 ). The first drying step is followed by a second drying step, which removes the film of water ( 13 ) from the wafer surface ( 3 ). The method according to the invention advantageously reduces metal ion contamination on the wafer surface ( 3 ).
1 . A method of cleaning a surface of a wafer, the method comprising the. subsequent steps of:
a first step comprising a hot rinse in which the wafer is at a temperature that is at least 10° C. higher than room temperature, the wafer is rotated around an axis perpendicular to the wafer surface and water is dispensed on the wafer surface;
a second step in which the wafer is rotated around the axis perpendicular to the wafer surface and in which the evaporation rate of the water on the wafer surface is such that the water is mainly removed from the wafer surface by the rotation of the wafer while the wafer surface remains covered with a film of water; and
a third step which removes the film of water from the wafer surface.
2 . A method of cleaning a wafer surface as claimed in claim 1 , wherein the first step is preceded by a cold rinse step in which the wafer is at room temperature and water is dispensed on the wafer surface.
3 . A method of cleaning a wafer surface as claimed in claim 1 , wherein the method is applied in a single wafer process.
4 . A method of cleaning a wafer surface as claimed in claim 3 , wherein the first step is during a time period of 0.5 seconds to 90 seconds, and the second step during a time period of 10 seconds to 100 seconds.
5 . A method of cleaning a wafer surface as claimed in claim 3 , wherein during the first step and the second step the wafer is rotated at a rotation speed higher than 1000 rotations per minute.
6 . A method of cleaning a wafer surface as claimed in claim 1 , wherein the method is applied in a batch process.
7 . A method of cleaning a wafer surface as claimed in claim 6 , wherein the first step is during a time period of 20 seconds to 300 seconds, and the second step during a time period of 30 seconds to 300 seconds.
8 . A method of cleaning a wafer surface as claimed in claim 6 , wherein during the first step and the second step the wafer is rotated at a rotation speed higher than 200 rotations per minute.
9 . A method of cleaning a wafer surface as claimed in claim 1 , wherein the water is dispensed on the wafer surface during the first step with a gradually decreasing flow rate.
10 . A method of cleaning a wafer surface as claimed in claim 1 , wherein a nitrogen gas flow controls the humidity of the environment which gas flow is higher during the third step than during the second step.