Method for producing aqueous solution of purified aminosilanol compound and aminosiloxane compound, and composition for etching

A method for producing an aqueous solution of a purified aminosilanol compound and aminosiloxane compound, the method comprising contacting, with an acidic cation exchange resin, an aqueous solution containing an aminosilanol compound and an aminosiloxane compound that is a condensate thereof to remove a metal component from the aqueous solution, the aminosilanol compound being represented by the following general formula (1):

• wherein R1 and R2 each independently represent a hydrogen atom or a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms that may contain a heteroatom, R1 and R2 may be bonded together to form a ring with a nitrogen atom to which R1 and R2 are bonded, R3 represents a substituted or unsubstituted divalent hydrocarbon group having 1 to 20 carbon atoms that may contain a heteroatom, R4 represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 20 carbon atoms, and m represents an integer of 0 to 2,
• wherein a concentration of the aminosilanol compound and the aminosiloxane compound in the aqueous solution to be contacted with the acidic cation exchange resin is 10 to 70 wt %.