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 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) forming a water repellent protecting film,
• wherein a liquid chemical for forming a protecting film is retained at least in the recessed portions of the uneven pattern, and
• wherein the contact angle of the protecting film to the surfaces of the recessed portions of the uneven pattern is between 50° and 130°;
• (b) removing a liquid from the uneven pattern by drying;
• and
• (c) removing the protecting film;
• 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 %;
• wherein R1 represents a C1-C18 monovalent hydrocarbon group the hydrogen elements of which may partially or entirely be replaced with a fluorine element, 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, and “a” is an integer of from 0 to 2.

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

• (a) forming a water repellent protecting film, wherein a liquid chemical for forming a protecting film is retained at least on the surfaces of the recessed portions containing at least one of titanium, tungsten, and ruthenium;
• (b) removing a liquid from the uneven pattern by drying;
• and
• (c) removing the protecting film;
• 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 monophosphonic acid 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 %;
• wherein R1 represents a C1-C18 monovalent hydrocarbon group the hydrogen elements of which may partially or entirely be replaced with a fluorine element, 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, and “a” is an integer of from 0 to 2.