Polybenzoxazoles from poly-o-hydroxyamide, novel poly-o-hydroxyamides, preparation processes therefor, and their application in microelectronics
View Patent ↗High-temperature-stable polybenzoxazoles are formed from novel poly-o-hydroxyamides. The novel poly-o-hydroxyamides have low dielectric constants, are suitable for exposure at 248 nm or shorter wavelengths, and have hydroxyl groups at least some of which have been protected by tert-butoxycarbonyl protective groups.
1. A poly-o-hydroxyamide, comprising:
hydroxyl groups; and
tert-butoxycarbonyl groups protecting at least some of said hydroxyl groups, said tert-butoxycarbonyl groups having the formula
wherein the radicals R 3 , R 4 , and R 5 are selected from the group consisting of —H, —F, —(CH 2 ) n —CH 3 , —(CF 2 ) n —CF 3 , where n=0 to 10, and with a proviso that at least one of the radicals R 3 , R 4 , and R 5 is different from hydrogen.
2. The poly-o-hydroxyamide according to claim 1 , corresponding to the general formula
wherein
R 1 and R 2 are or are not hydrogen or a tert-butoxycarbonyl group of the general formula I, and wherein at least one of R 1 or R 2 is formed at least in part by —COOC(R 3 R 4 R 5 );
A 1 and A 2 (attached to —NH—) are identical or different and are selected from the group consisting of —H; —CO—(CH 2 ) n —CH 3 ; —CO—(CF 2 ) n —CF 3 ; —CO—CH═CH—COOH; where n=0 to 10;
wherein W is selected from the group consisting of W=—H, —F, —CN, —C(CH 3 ) 3 , —(CH 2 ) n —CH 3 , —(CF 2 ) n —CF 3 , —O—(CH 2 ) n —CH 3 , —O—(CF 2 ) n —CF 3 ; —CH═CH 2 , —C≡CH and
where n=0 to 10;
wherein A 2 is an OH group if at least one of the following is true: A 2 is attached to —CO—, and c=0;
X 1 and X 2 , independently of one another, are:
Z is selected from the group consisting of —O—; —CO—; —S—; —S—S—; —SO 2 —; —(CH 2 ) m —; —(CF 2 ) m — where m=1 to 10; —C(CR 6 3 ) 2 — where R 6 is identical or different and can be a hydrocarbon radical with 1 to 2 carbon atoms and may also be fully or partly fluorinated, hydrogen, halide or pseudohalide;
Y 1 and Y 2 , independently of one another, are:
wherein R 7 is selected from the group consisting of —H, —CN; —C(CH 3 ) 3 ; —C(CF 3 ) 3 ; —(CH 2 ) n —CH 3 ; —(CF 2 ) n —CF 3 ; —O—(CH 2 ) n —CH 3 , —O—(CF 2 ) 2 —CF 3 , —C≡CH; —CH═CH 2 ; —O—CH═CH 2 ; —O—CH 2 —CH═CH 2 ; —CO—(CH 2 ) n —CH 3 ; and —CO—(CF 2 ) n —CF 3 , where n=0 to 10;
and Z is as defined above; and
wherein a may adopt any value from 1 to 100; b may adopt any value from 0 to 100; and c may adopt the value 0 or 1.
3. A method of producing polybenzoxazole, which comprises providing a poly-o-hydroxyamide according to claim 1 , and heat-treating the poly-o-hydroxyamide to obtain the polybenzoxazole.
4. A method of preparing a poly-o-hydroxyamide, which comprises the following steps:
providing bisaminophenol having at least one protected hydroxyl group, the hydroxyl function being protected by a tert-butoxycarbonyl group defined by the formula
wherein the radicals R 3 , R 4 , and R 5 are selected from the group consisting of —H, —F, —(CH 2 ) n —CH 3 , —(CF 2 ) n —CF 3 , where n=0 to 10, and with a proviso that at least one of the radicals R 3 , R 4 , and R 5 is different from hydrogen; and
reacting the bisaminophenol having the protected hydroxyl group with at least one activated dicarboxylic acid.
5. A process for preparing a poly-o-hydroxyamide, which comprises reacting a poly-o-hydroxyamide of the formula
having unprotected hydroxyl groups, where R 1 =R 2 =—H, with di-tert-butyl dicarbonate.
6. An improved coating method, which comprises providing a poly-o-hydroxyamide according to claim 1 and forming a coating layer with the poly-o-hydroxyamide.
7. The method according to claim 6 , which comprises heat-treating the poly-o-hydroxyamide to form a coating of polybenzoxazole.
8. The method according to claim 7 , wherein the polybenzoxazole is formed with a dielectric constant of less than 3.0.
9. The method according to claim 6 , which comprises forming a coating on a microelectronic device.
10. A photosensitive formulation, comprising the poly-o-hydroxyamide according to claim 1 .
11. The photosensitive formulation according to claim 10 , which further comprises a photoacid generator.
12. A photosensitive formulation, comprising the polybenzoxazole according to claim 3 .
13. The photosensitive formulation according to claim 12 , which further comprises a photoacid generator.
14. A photosensitive formulation for a microelectronics production process, comprising the poly-o-hydroxyamide according to claim 1 .
15. The photosensitive formulation according to claim 14 , which further comprises a photoacid generator.
16. A photosensitive formulation for a microelectronics production process, comprising the polybenzoxazole formed by the method of claim 3 .
17. The photosensitive formulation according to claim 16 , which further comprises a photoacid generator.
18. The poly-o-hydroxyamide according to claim 1 , wherein the proportion of the hydroxyl groups blocked by a t-butoxycarbonyl group of the formula I relative to the number of free hydroxyl groups in the unprotected poly-o-hydroxyamide is at least 30%.