Ester group-containing poly (imide-azomethine) copolymer, ester group-containing poly (amide acid-azomethine) copolymer, and positive photosensitive resin composition

1. An ester group-containing poly(imide-azomethine)copolymer comprising an azomethine polymer unit of the formula (1) and an imide polymer unit of the formula (2):

wherein in the formulas (1) and (2), A and D are each independently a divalent aromatic or aliphatic group with D containing an ester group; and B is a tetravalent aromatic or aliphatic group.

2. The ester group-containing poly(imide-azomethine)copolymer according to claim 1 , wherein a molar fraction of the polymer unit of the formula (1) with respect to a total amount of the polymer unit of the formula (1) and the polymer unit of the formula (2) is in a range of 0.05 to 0.95.

3. The ester group-containing poly(imide-azomethine)copolymer according to claim 1 that has a linear thermal expansion coefficient of less than 30 ppm/K and a glass transition temperature of 250° C. or above.

4. A method for producing the ester group-containing poly(imide-azomethine)copolymer according to claim 1 , comprising:

mixing and polymerizing together a diamine of the formula (a), a tetracarboxylic acid dianhydride of the formula (b) and a dialdehyde of the formula (c):

wherein in the formulas (a), (b) and (c), A and D are each independently a divalent aromatic or aliphatic group with D containing an ester group; and B is a tetravalent aromatic or aliphatic group,

to form an ester group-containing poly(amide acid-azomethine)copolymer composed of an ester group-containing azomethine polymer unit of the formula (1) and an amide acid polymer unit of the formula (3):

wherein in the formulas (1) and (3), A and D are each independently a divalent aromatic or aliphatic group with D containing an ester group; and B is a tetravalent aromatic or aliphatic group; and

imidizing the obtained ester group-containing poly(amide acid-azomethine)copolymer to give an ester group-containing poly(imide-azomethine)copolymer.

5. The method according to claim 4 , wherein a molar fraction of the polymer unit of the formula (1) with respect to a total amount of the polymer unit of the formula (1) and the polymer unit of the formula (3) is in a range of 0.05 to 0.95.

6. The method according to claim 4 , wherein the diamine of the formula (a) and the acid dianhydride of the formula (b) are mixed and reacted with each other, and the dialdehyde of the formula (c) is subsequently mixed with the reaction mixture for reaction.

7. An ester group-containing poly(amide acid-azomethine)copolymer, comprising an azomethine polymer unit of the formula (1) and an amide acid polymer unit of the formula (3):

wherein in the formulas (1) and (3), A and D are each independently a divalent aromatic or aliphatic group with D containing an ester group; and B is a tetravalent aromatic or aliphatic group.

8. The ester group-containing poly(amide acid-azomethine)copolymer according to claim 1 , wherein a molar fraction of the polymer unit of the formula (1) with respect to a total amount of the polymer unit of the formula (1) and the polymer unit of the formula (2) is in a range of 0.05 to 0.95.

9. The ester group-containing poly(amide acid-azomethine)copolymer according to claim 7 that has an intrinsic viscosity of 0.1 dL/g or higher.

10. A positive photosensitive resin composition comprising the ester group-containing poly(amide acid-azomethine)copolymer according to claim 7 and a diazonaphthoquinone sensitizer.

11. The positive photosensitive resin composition according to claim 10 , wherein an amount of the diazonaphthoquinone sensitizer with respect to an amount of the ester group-containing poly(amide acid-azomethine)copolymer is 10 to 40% by weight.

12. A method for forming a fine pattern of an ester group-containing poly(imide-azomethine)copolymer, comprising:

forming the positive photosensitive resin composition according to claim 10 into film;

exposing the film of the positive photosensitive resin composition to a pattern of light;

developing the pattern in an alkaline solution; and

imidizing the resin composition to make the fine pattern of the ester group-containing poly(imide-azomethine)copolymer.

13. The method according to claim 12 , wherein the ester group-containing poly(imide-azomethine)copolymer has a linear thermal expansion coefficient of less than 30 ppm/K and a glass transition temperature of 250° C. or above.

14. A method for forming a fine pattern of an ester group-containing poly(imide-azomethine)copolymer, comprising:

depositing a layer of a photoresist over a thin film of the ester group-containing poly(imide-azomethine)copolymer according to claim 1 ;

exposing the photoresist to a pattern of light;

developing the photoresist; and

etching the thin film of the ester group-containing poly(imide-azomethine)copolymer with an alkaline solution to form the fine pattern.

15. A method for forming fine pattern of ester group-containing poly(imide-azomethine)copolymer, comprising:

depositing a layer of a photoresist over a thin film of the ester group-containing poly(amide acid-azomethine)copolymer according to claim 7 ;

exposing the photoresist to a pattern of light;

developing the pattern in an alkaline solution;

etching the film in an alkaline solution; and

imidizing the copolymer to form the fine pattern of the ester group-containing poly(imide-azomethine)copolymer.