Abstract: Disclosed is a process for cleaning a wafer having an uneven pattern at its surface. The process includes at least: a step of cleaning the wafer; a step of substituting a cleaning liquid retained in recessed portions of the wafer with a water-repellent liquid chemical after cleaning; and a step of drying the wafer. The process is characterized in that the cleaning liquid has a boiling point of 55 to 200° C., and characterized in that the water-repellent liquid chemical used for the substitution has a temperature of not lower than 40° C. and lower than a boiling point of the water-repellent liquid chemical thereby imparting water repellency at least to surfaces of the recessed portions. With this process, it is possible to provide a cleaning process for improving the cleaning step that tends to induce a pattern collapse.

Abstract: Disclosed is a liquid chemical for forming a water-repellent protecting film at least on a surface of a recessed portion of an uneven pattern at the time of cleaning a wafer having a finely uneven pattern at its surface and containing silicon at least a part of the uneven pattern. This liquid chemical contains a silicon compound A represented by the general formula: R1aSi(H)bX4-a-b and an acid A, the acid A being at least one selected from the group consisting of trimethylsilyl trifluoroactate, trimethylsilyl trifluoromethanesulfonate, dimethylsilyl trifluoroactate, dimethylsilyl trifluoromethanesulfonate, butyldimethylsilyl trifluoroactate, butyldimethylsilyl trifluoromethanesulfonate, hexyldimethylsilyl trifluoroacetate, hexyldimethylsilyl trifluoromethanesulfonate, octyldimethylsilyl trifluoroactate, octyldimethylsilyl trifluoromethanesulfonate, decyldimethylsilyl trifluoroacetate and decyldimethylsilyl trifluoromethanesulfonate.

Abstract: A cleaning agent for a silicon wafer (a first cleaning agent) contains at least a water-based cleaning liquid and a water-repellent cleaning liquid for providing at least a recessed portion of an uneven pattern with water repellency during a cleaning process. The water-based cleaning liquid is a liquid in which a water-repellent compound having a reactive moiety chemically bondable to Si element in the silicon wafer and a hydrophobic group, and an organic solvent including at least an alcoholic solvent are mixed and contained. With this cleaning agent, the cleaning process which tends to induce a pattern collapse can be improved.

Abstract: Disclosed is a liquid chemical for forming a water-repellent protecting film on a wafer. The liquid chemical is a liquid chemical containing a water-repellent-protecting-film-forming agent for forming the water-repellent protecting film, at the time of cleaning the wafer which has a finely uneven pattern at its surface and contains at least at a part of a surface of a recessed portion of the uneven pattern at least one kind of matter selected from the group consisting of titanium, titanium nitride, tungsten, aluminum, copper, tin, tantalum nitride, ruthenium and silicon, at least on the surface of the recessed portion. The liquid chemical is characterized in that the water-repellent-protecting-film-forming agent is a water-insoluble surfactant. The water-repellent protecting film formed with the liquid chemical is capable of preventing a pattern collapse of the wafer, in a cleaning step.

Abstract: A silicon wafer cleaning agent includes at least a water-based cleaning liquid, and a water-repellent cleaning liquid for providing water-repellent to an uneven pattern at least at recessed portions during a cleaning process. The water-repellent cleaning liquid is a liquid composed of a water-repellent compound containing a reactive moiety which is chemically bondable to Si in the silicon wafer, and a hydrophobic group, or is a liquid wherein 0.1 mass % or more of the water-repellent compound relative to the total quantity of 100 mass % of the water-repellent cleaning liquid and an organic solvent are mixed and contained therein. A cleaning process wherein a pattern collapse is easily induced can be improved by using the cleaning agent.