Process for preparing chemical liquid of silylating agent and surface treatment method

A process for preparing a chemical liquid comprising a silylating agent, the process comprising sequential steps of:

• contacting an ion-exchange resin membrane with an organic solvent;
• and
• removing metal impurities from an untreated chemical liquid comprising a silylating agent by passing the untreated chemical liquid through the ion-exchange resin membrane, thereby obtaining the chemical liquid,
• wherein the ion-exchange resin membrane is purged with nitrogen before contacting with the organic solvent.

A process for preparing a chemical liquid comprising a silylating agent, the process comprising sequential steps of:

• contacting an ion-exchange resin membrane with an organic solvent;
• and
• removing metal impurities from an untreated chemical liquid comprising a silylating agent by passing the untreated chemical liquid through the ion-exchange resin membrane, thereby obtaining the chemical liquid,
• wherein the silylating agent is a silicon compound represented by the following general formula (1) respectively:
• (R1)aSi(H)bX14-a-b (1)
• wherein each R1 independently represents a monovalent organic group comprising a monovalent hydrocarbon group having 1 to 18 carbon atoms in which a part or all of hydrogen atoms may be substituted by fluorine atoms;
• each X1 independently represents a monovalent functional group having nitrogen that is an atom bonded to the silicon atom;
• a is an integer of 1 to 3;
• and b is an integer of 0 to 2, with the total of a and b being 1 to 3.