Cleaning solution, method of removing a removal target and method of etching a substrate using said cleaning solution

1. A cleaning liquid comprising:

(A1) 3-methoxy-3-methyl-1-butanol

(A2) diethylene glycol monomethyl ether;

(B) tetramethyl ammonium hydroxide; and

water,

wherein the content [a1] of (A1) 3 methoxy-3-methyl-1-butanol is greater than 40% by mass and 65% by mass or less with respect to the mass of the cleaning liquid,

and wherein a ratio [a1/(a1+a2)] of the content [a1] of the (A1) 3 methoxy-3-methyl-1-butanol to a total of the content [a1] and the content [a2] of the (A2) diethylene glycol monomethyl ether compound is 65% to 95% by mass.

2. The cleaning liquid according to claim 1 , wherein the content [a1] of (A1) 3 methoxy-3-methyl-1-butanol is 45% to 65% by mass with respect to the mass of the cleaning liquid.

3. The cleaning liquid according to claim 1 , wherein the content of water is 15% to 40% by mass with respect to the mass of the cleaning liquid.

4. A method of removing at least one target to be removed selected from the group consisting of a resist pattern, a fluorocarbon layer, and a polyimide layer, the method comprising:

removing the target to be removed with the cleaning liquid according to claim 1 ,

wherein the target to be removed is formed in a semiconductor manufacturing step.

5. A method of etching a substrate, comprising:

(A-I) forming an etching mask pattern on the surface of a substrate;

(A-II) etching the surface of the substrate which is exposed through the etching mask pattern to form a recessed portion;

(A-III) forming a recessed portion having a predetermined depth on the substrate by repeatedly performing the following steps (i) and (ii) until a recessed portion having the predetermined depth is formed:

(i) forming a fluorocarbon layer on a side wall of the recessed portion of the surface of the substrate, which is formed by etching;

(ii) etching a bottom face of the recessed portion; and

(A-IV) removing the fluorocarbon layer with a cleaning liquid after the recessed portion having the predetermined depth is formed,

wherein the cleaning liquid according to claim 1 is used as the cleaning liquid in the fluorocarbon layer removing step.

6. The method of etching a substrate according to claim 5 , wherein the etching mask pattern is formed by the following (B-I) to (B-III):

(B-I) applying a resist composition onto the surface of an etching mask layer to form a resist film,

(B-II) exposing and developing the resist film to form a resist pattern, and

(B-III) etching the surface of the etching mask layer exposed through the resist pattern.

7. The method of etching a substrate according to claim 6 , further comprising (B-IV) removing the resist pattern with the cleaning liquid according to claim 1 .

8. A method of etching a substrate, comprising:

(C-I) forming an etching mask layer on the surface of a substrate;

(C-II) applying a resist composition onto the etching mask layer to form a resist film;

(C-III) exposing and developing the resist film to form a resist pattern;

(C-IV) etching the etching mask layer exposed through an opening portion of the resist pattern to form an etching mask pattern, and then removing the resist pattern with a cleaning liquid;

(C-V) etching the surface of the substrate exposed through the etching mask pattern to form a recessed portion;

(C-VI) forming a recessed portion having a predetermined depth on the substrate by repeatedly performing the following steps (i) and (ii) until a recessed portion having the predetermined depth is formed:

(i) forming a fluorocarbon layer on a side wall of the recessed portion of the surface of the substrate, which is formed by etching;

(ii) etching a bottom face of the recessed portion; and

(C-VII) removing the fluorocarbon layer with a cleaning liquid after the recessed portion having the predetermined depth is formed,

wherein the cleaning liquid according to claim 1 is used as the cleaning liquid in at least one of the etching mask pattern forming step and the fluorocarbon layer removing step.

9. The method of etching a substrate according to claim 8 , wherein the cleaning liquid according to claim 1 is used as the cleaning liquid in each of the etching mask pattern forming step and the fluorocarbon layer removing step.