Patent ID: 9481858
Filing Date: 2016-11-01
CPC Classification: C11D,H01L

Claim Text:
1. A cleaning method for a surface of a silicon wafer, comprising the steps of: (a) using a cleaning agent for substituting a cleaning liquid retained in recessed portions of a silicon wafer having a finely uneven pattern at its surface with another cleaning liquid, wherein at least one of the cleaning liquid retained in recessed portions of a silicon wafer having a finely uneven pattern or the another cleaning liquid is retained through the substitution, wherein the cleaning agent comprises a water-based first cleaning liquid; and a water-repellent second cleaning liquid for imparting water repellency at least to the recessed portions of the uneven pattern during a cleaning process, wherein the water-repellent second cleaning liquid comprises a liquid that contains a water-repellent compound having a reactive moiety chemically bondable to Si in the silicon wafer and a hydrophobic group, and an acid catalyst; or a liquid that contains the water-repellent compound in an amount of 0.1-50 mass % relative to the total quantity of 100 mass % of the water-repellent second cleaning liquid, an organic solvent, and an acid catalyst; wherein the water-repellent second cleaning liquid is retained in the recessed portions formed at the surface of the silicon wafer to provide said recessed portions with water repellency; wherein any water retained in the recessed portions has a capillary force not higher than 2.1 MN/m wherein the water-repellent compound comprises at least one compound selected from the group consisting of compounds represented by formula [2] or compounds represented by formula [3]: wherein R d is an integer of from 0 to 2; e is an integer of from 1 to 3; R Y represents a monovalent organic group whose element to be bonded to Si is nitrogen; (b) bringing the silicon wafer into contact with the water-based first cleaning liquid; and (c) thereafter bringing the silicon wafer into contact with the water-repellent second cleaning liquid.