Methods for depositing polymer layer for sensor applications via hot wire chemical vapor deposition

1. A method of depositing a polymer layer, comprising:

heating a substrate, a field-effect transistor sensor structure disposed on the substrate, and a process gas comprising an initiator gas, a monomer gas, and a carrier gas within a hot wire chemical vapor deposition (HWCVD) chamber, wherein the heating is to a temperature sufficient to form initiator radicals without decomposing the monomer gas; and

contacting the field-effect transistor sensor structure, the initiator radicals, and the monomer gas to form a polymer layer atop the field-effect transistor sensor structure, wherein the polymer layer has a thickness of about 1 nm to about 100 nm, and wherein the thickness has a thickness deviation of less than about 5 percent across the substrate, wherein the field-effect transistor sensor structure is one of a chemical field effect transistor, an ion sensitive field effect transistor, a field-effect transistor-based biosensor, an enzyme field effect transistor, a chip-based chemical sensor, or a chip-based biosensor.

2. The method of claim 1 , further comprising cooling the substrate and field-effect transistor sensor structure.

3. The method of claim 1 , wherein the polymer layer is a copolymer layer, and wherein the copolymer comprises one or more hydrophilic monomer constituents, functional monomer constituents, and optionally a crosslinker.

4. A method of depositing a polymer layer, comprising:

providing a substrate, having a field-effect transistor sensor structure disposed on the substrate, to a substrate support within a hot wire chemical vapor deposition (HWCVD) chamber, wherein the field-effect transistor sensor structure is one of a chemical field effect transistor, an ion sensitive field effect transistor, a field-effect transistor-based biosensor, an enzyme field effect transistor, a chip-based chemical sensor, or a chip-based biosensor;

providing a process gas comprising an initiator gas and a monomer gas and a carrier gas to the HWCVD chamber;

heating a plurality of filaments disposed in the HWCVD chamber to a first temperature sufficient to activate the initiator gas without decomposing the monomer gas; and

exposing the substrate to initiator radicals from the activated initiator gas and to the monomer gas to deposit a polymer layer atop the field-effect transistor sensor structure, wherein the polymer layer has a thickness of about 1 nm to about 100 nm, and wherein the thickness has a thickness deviation of less than about 5 percent across the substrate.

5. The method of claim 4 , wherein the plurality of filaments are heated to a temperature of about 150 to about 600 degrees Celsius.

6. The method of claim 4 , wherein a temperature of the substrate is about −20 degrees Celsius to about 100 degrees Celsius.

7. The method of claim 4 , further comprising:

prior to flowing the process gas, treating the substrate with an adhesion chemistry to prevent delamination of the polymer layer from the field-effect transistor sensor structure.

8. The method of claim 4 , wherein the carrier gas is argon, nitrogen, or helium.

9. The method of claim 4 , wherein the initiator gas is di-tert-butyl peroxide (TBPO), di-tert-amyl peroxide (TAPO), triethylamine (TEA), tert-butyl peroxybenzoate, perfluorooctane sulfonyl fluoride, or perfluorobutane sulfonyl fluoride.

10. The method of claim 4 , wherein the monomer gas comprises a mixture of a hydrophilic monomer, a crosslinker and a functional monomer.

11. The method of claim 10 , wherein the hydrophilic monomer contains a polymerizable carbon-carbon double bond and a hydrophilic pendant group.

12. The method of claim 10 , wherein the hydrophilic monomer is hydroxyethyl methacrylate, N-iso-propylacrylamide, N,N-dimethylacrylamide, or methacrylic acid.

13. The method of claim 10 , wherein the crosslinker contains more than one polymerizable carbon-carbon double bond, or wherein the crosslinker is ethyleneglycol dimethacrylate, ethylene glycol diacrylate, butanediol diacrylate, or hexanediol diacrylate.

14. The method of claim 10 , wherein the functional monomer contains a polymerizable carbon-carbon double bond and a moiety with chemical or biological functionality.

15. The method of claim 10 , wherein the functional monomer is glycidyl methacrylate, methacrylic acid, or 4-aminostyrene.

16. The method of claim 4 , wherein a ratio of a flow rate of the initiator gas to the monomer gas is about 0.1:1 to about 1:1, and wherein a pressure in the HWCVD chamber is about 0.1 to about 10 Torr.

17. A method of depositing a polymer layer, comprising:

heating a substrate, a sensor structure disposed on the substrate, and a process gas comprising an initiator gas, a monomer gas, and a carrier gas within a hot wire chemical vapor deposition (HWCVD) chamber, wherein the heating is to a temperature sufficient to form initiator radicals without decomposing the monomer gas; and

contacting the sensor structure, the initiator radicals, and the monomer gas to form a polymer layer atop the sensor structure, wherein the sensor structure is one of a chemical field effect transistor, an ion sensitive field effect transistor, a field-effect transistor-based biosensor, an enzyme field effect transistor, a chip-based chemical sensor, or a chip-based biosensor.

18. The method of depositing a polymer layer of claim 17 , wherein the polymer layer has a thickness of about 1 nm to about 100 nm, and wherein the thickness has a thickness deviation of less than about 5 percent across the substrate.