Liquid Chemical for Forming Water Repellent Protecting Film, and Process for Cleaning Wafers Using the Same

A process for cleaning a wafer having an uneven pattern at its surface, the wafer containing at least one kind of element selected from the group consisting of titanium, tungsten, aluminum, copper, tin, tantalum and ruthenium at surfaces of recessed portions of the uneven pattern, comprising at least the steps of:

• a water repellent protecting film forming step in which a liquid chemical for forming a protecting film is retained at least in the recessed portions of the uneven pattern;
• a drying step in which a liquid is removed from the uneven pattern by drying;
• and
• a film removing step in which the protecting film is removed,
• wherein the liquid chemical for forming a protecting film includes a water repellent protecting film forming agent and water,
• wherein the water repellent protecting film forming agent is at least one selected from compounds represented by the following general formula [1] and salt compounds thereof, and
• wherein the concentration of the water relative to the total quantity of a solvent contained in the liquid chemical is not smaller than 50 mass %.
• (In the formula [1], R1 represents a C1-C18 monovalent hydrocarbon group the hydrogen elements of which may partially or entirely be replaced with a fluorine element(s). R2 mutually independently represents a monovalent organic group having a C1-C18 hydrocarbon group the hydrogen elements of which may partially or entirely be replaced with a fluorine element(s). “a” is an integer of from 0 to 2.)