Photopatternable materials and related electronic devices and methods
The present polymeric materials can be patterned with relatively low photo-exposure energies and are thermally stable, mechanically robust, resist water penetration, and show good adhesion to metal oxides, metals, metal alloys, as well as organic materials. In addition, these polymeric materials can be solution-processed (e.g., by spin-coating), and can exhibit good chemical (e.g., solvent and etchant) resistance in the cured form.
1. A method of fabricating an electronic device comprising a semiconductor layer, the method comprising:
forming an organic layer in contact with the semiconductor layer, wherein the organic layer is formed by depositing a thin film from a composition comprising a polymer having the formula:
wherein:
U and U′, at each occurrence, independently are selected from the group consisting of a halogen, CN, a C 1-6 alkyl group, and a C 1-6 haloalkyl group;
W and W′ independently are —Ar[—Y—Ar] q —, wherein:
Ar, at each occurrence, independently is a divalent C 6-18 aryl group;
Y, at each occurrence, independently is selected from the group consisting of —O—,—S—,—S(O) 2 —,—(CR′R″) r —,—C(O)—, and a covalent bond, wherein R′ and R″, at each occurrence, independently are selected from the group consisting of H, a halogen, CN, a C 1-10 alkyl group, and a C 1-10 haloalkyl group; and r is selected from 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10; and
q is selected from 0, 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10;
Z and Z′ independently are selected from the group consisting of —O—, —S—, and —Se—;
L and L′, at each occurrence, independently are selected from the group consisting of —O—, —S—, a divalent C 1-10 alkyl group, a divalent C 6-18 aryl group, and a covalent bond;
T and T′, at each occurrence, independently are Q or R, wherein:
Q is a crosslinkable group comprising an ethenyl moiety, an ethynyl moiety, a dienyl moiety, an acrylate moiety, a coumarinyl moiety, an epoxy moiety, or a combination thereof; and
R is selected from the group consisting of H, a halogen, a C 1-10 alkyl group, a C 1-10 haloalkyl group, and a C 6-10 aryl group optionally substituted with 1 to 5 substituents independently selected from the group consisting of a halogen and CN, provided that W comprises at least one Ar group selected from
p is 1, 2, 3, 4, 5, 6, 7 or 8;
p′ is 0, 1, 2, 3, 4, 5, 6, 7 or 8;
x and x′ independently are 0, 1, 2, 3 or 4;
m is a real number, wherein 0<m≦1; and
n is an integer ranging from 10 to 500; and
exposing the thin film to irradiation to photocrosslink the polymer so that the organic layer comprises a photocrosslinked product of the polymer.
2. The method of claim 1 , wherein U and U′, at each occurrence, independently are selected from the group consisting of F, Cl, CH 3 , and CF 3 ; and x and x′, at each occurrence, independently are 0, 1, 2 or 4.
3. The method of claim 2 , wherein each of x and x′ is 0, and the polymer has the formula:
wherein L, L′, T, T′, W, W′, Z, Z′, m, n, p and p′ are as defined in claim 1 .
4. The method of claim 2 , wherein at least one of x is not 0.
5. The method of claim 1 , wherein the polymer has the formula:
wherein L, L′, T, T′, W, W′, Z, Z′, m, n, p and p′ are as defined in claim 1 .
6. The method of claim 1 , wherein Z and Z′ are O or S.
7. The method of claim 1 , wherein the polymer is a homopolymer of the repeat unit:
where x can be 0 or 4, which is selected from the group consisting of:
wherein L and Q are as defined in claim 1 .
8. The method of claim 7 , wherein Q is selected from the group consisting of:
wherein R 1 is H or a C 1-20 alkyl group.
9. The method of claim 7 , wherein the polymer is a homopolymer of a repeat unit selected from the group consisting of:
10. The method of claim 3 , wherein m<1, and the moieties
are different and independently are selected from the group consisting of:
wherein each —L—Q group independently is selected from the group consisting of:
wherein R 1 is H or a C 1-20 alkyl group.
11. The method of claim 1 , wherein the polymer is a copolymer of:
where x is 0 or 4.
12. The method of claim 1 , wherein the polymer is a copolymer of:
13. The method of claim 1 , wherein the composition further comprises a bismaleimide crosslinker.
14. The method of claim 1 , wherein the composition further comprises a photoacid generator.
15. The method of claim 14 , wherein the composition comprises the polymer and the photoacid generator dispersed in a liquid medium, wherein the polymer is present in the composition at a concentration between about 1 wt. % and about 20 wt. % and the photoacid generator is present in the composition at a concentration between about 0.05 wt. % and about 1 wt. %.
16. The method of claim 1 comprising exposing the thin film to irradiation under a mask to induce photocrosslinking only in exposed areas of the thin film; and developing unexposed areas of the thin film so that the organic layer is patterned.
17. The method of claim 1 , wherein the electronic device is a thin film transistor and the method further comprises forming source and drain electrodes in contact with the semiconductor layer, and forming the organic layer over the source and drain electrodes and the semiconductor layer as a passivation layer.
18. The method of claim 1 , wherein the electronic device is a thin film transistor and the method comprises forming the organic layer as a dielectric layer between the semiconductor layer and a gate electrode.
19. The method of claim 1 , wherein the electronic device is a thin film transistor and the method further comprises forming source and drain electrodes in contact with the organic layer, wherein the organic layer functions as an etch stop layer.