Method for manufacturing an optical filter

• US 4,808,501 A
• Filed: 05/15/1987
• Issued: 02/28/1989
• Est. Priority Date: 10/15/1985
• Status: Expired due to Term

• Current Assignee: Polaroid Corporation (PLR IP Holdings LLC)
• Original Assignee: C/O Polaroid Corporation Patent Dept
• Inventors: Chiulli, Carl A.
• Primary Examiner(s): Dees, Jose G.
• Application Number:
  US07/050,743
• Time in Patent Office: 655 Days
• Field of Search: 430/7, 430/321, 430/293, 430/394, 430/326, 430/330, 430/4, 430/145, 430/165, 430/191, 350/339 F
• US Class Current: 430/7
• CPC Class Codes: G03F 7/0007 Filters, e.g. additive colour filters; Components for display devices
• CPC Class Codes: G03F 7/0035 Multiple processes, e.g. applying a further resist layer on an already in a previously step, processed pattern or textured surface
• CPC Class Codes: H01L 31/02162 for filtering or shielding light, e.g. multicolour filters for photodetectors

Abstract

A color filter is formed on a support, such as a charge coupled device, by (a) forming a layer on a support with a composition comprising a positive photoresist and a dye; said dye being soluble in the solvent of said photoresist; (b) exposing predetermined portions of said layer to radiation adapted to increase the solubility of said coating in the exposed areas; (c) developing said exposed areas to form a pattern of filter elements; and (d) repeating said steps with a different color dye in said composition; wherein said dye constitutes in excess of 10% by weight, dry basis of said composition, is substantially non-absorptive in the exposure wavelength of said composition, and provides predetermined absorptive characteristics for the specified filter element and said dye possessing substantially the same polarity as said composition.

Claims

1. A method for making a color filter having a plurality of colored filter elements, which method comprises the steps of

(a) forming, onto a support, a solvent-coating of a dye-containing positive photoresist composition and drying said solvent coating to an adherent layer, said composition comprising a photoresist resin and a dye;

said dye being soluble in the solvent of said photoresist composition and constituting in excess of 10% up to about 50% of said composition, on a dry weight basis;

said dye having substantially the same polarity as said resin, thereby interacting sufficiently with said resin and being sufficiently compatible therewith as not to form a separate phase from said coated photoresist composition;

said dye providing the desired dye density and the predetermined absorption and transmission properties characteristic of the predetermined color desired in filter elements to be prepared from said photoresist composition;

said dye being sufficiently transmission of radiation used for exposure of said photoresist composition as to permit desired control of the solubility of said photoresist composition in areas of exposure and the formation on development, of a pattern of said filter elements having said predetermined absorption and transmission properties;

(b) exposing predetermined portions of said layer to radiation adapted to increase the solubility of said layer in the exposed areas;

(c) developing said exposed areas to form said pattern of filter elements; and

(d) repeating steps (a) to (c) with a different color dye in said composition.

2. The method of claim 1 wherein said positive photoresist composition comprises a novolak resin and a photoactive dissolution rate inhibitor.

3. The method of claim 2 wherein said novolak is present at a level of about 40-75% by weight, dry basis, said photoactive dissolution rate inhibitor is present at a level of about 10-18% by weight, dry basis, and said dye is present at a level in excess of 10% to 50% by weight, dry basis.

4. The method of claim 3 wherein said dye is present at a level in excess of 30% up to about 50% by weight, dry basis.

5. The method of claim 1 which includes stabilizing said filter elements.

6. The method of claim 5 which includes a thermal stabilization step.

7. The method of claim 5 wherein said stabilization step comprises subjecting said filter elements to ultraviolet radiation.

8. The method of claim 5 which includes both an ultraviolet and a thermal stabilization step.

9. The method of claim 2 wherein said dye contains hydroxyl groups.

10. The method of claim 9 wherein said dye contains hydroquinone groups.

11. The method of claim 1 which includes the step of drying said composition prior to exposure.

12. The method of claim 1 wherein said exposing radiation is predominantly in the ultraviolet region.

13. The method of claim 1 wherein said exposed areas are developed by contact with an aqueous alkaline solution.

14. The method of claim 1 wherein said dye is hydrogen bonded to the resin of said positive photoresist.

15. The method of claim 1 wherein said support is a solid state imager.

16. The method of claim 1 wherein said solid state imager is a charge coupled device.

17. The method of claim 16 wherein said charge coupled device is of the type comprising a plurality of spaced apart elements each defined by a surrounding channel stop, said method further comprising the step of predetermining the portions of said composition to be exposed to radiation by masking selected ones of said elements in a manner so that the edges of the filter elements formed upon the subsequent exposure and development of said selectively masked elements extends over the channel stop surrounding said selectively masked elements.

18. A method for making a color filter having a plurality of colored filter elements, which method comprises the steps of

(a) forming, onto a support, a solvent coating of a dye-containing positive photoresist composition and drying said solvent coating to an adherent layer, said composition comprising 40-75% by weight, dry basis, of a novolak resin, 10-18% by weight, dry basis, photoactive dissolution rate inhibitor and a first dye in excess of 10% to 50% by weight, dry basis;

said first dye being soluble in the solvent of said photoresist composition;

said first dye having substantially the same polarity as said novolak resin, thereby interacting sufficiently with said resin and being sufficiently compatible therewith as not to form a separate phase from said coated photoresist composition;

said dye providing the dseired dye density and the predetermined absorption and transmission properties characteristic of the predetermined color desired in filter elements to be prepared from said photoresist composition;

said dye being sufficiently transmissive of radiation used for exposure of said layer as to permit desired control of the solubility of said photoexposed photoresist composition in exposed areas, and the formation on development, of a pattern of said filter elements having said predetermined absorption and transmission properties;

(b) exposing predetermined portions of said layer to radiation adapted to increase the solubility of said layer in the exposed areas;

(c) developing said exposed areas to form said pattern of filter elements;

(d) forming a second layer on said support with a composition comprising a negative photoresist and a second dye;

said second dye being soluble in the solvent of the photoresist;

(e) exposing predetermined portions of said second layer to radiation adapted to cross-link the photoresist in the exposed areas; and

(f) developing said second layer to provide a second set of filter elements.

19. A method for making a color filter having a plurality of colored filter elements, which method comprises the steps of

(a) forming, on a solid state imager, a solvent coating of a dye-containing positive photoresist composition, said composition comprising a novolak resin at a level of about 40-75% by weight, dry basis, a photoactive dissolution rate inhibitor at a level of about 10-18% by weight, dry basis, and a dye of a first color, at a level in excess of 10% to 50% by weight dry basis;

said dye being soluble in the solvent to said photoresist composition;

said first color dye having substantially the same polarity as said novolak resin, thereby interacting sufficiently with said novolak resin and being sufficiently compatible therewith as not to form a separate phase from said coated photoresist composition;

said first color dye providing the desired dye density and the predetermined absorption and transmission properties of filter elements to be prepared from said layer;

said dye being sufficiently transmissive of radiation used for exposure of said photoresist composition as to permit the desired control of the solubility of said photoresist composition in areas of exposure, and the formation on development, of a pattern of filter elements of said first color;

(b) drying said solvent coating to an adherent layer;

(c) exposing predetermined portions of said layer to radiation adapted to increase the solubility of said layer in the exposed areas;

(d) developing said exposed areas to form said pattern of filter elements;

(e) thermally stabilizing said pattern of filter elements;

(f) forming a solvent coating of a second dye-containing positive photoresist composition, said second composition being defined as in step a), except comprising a dye of a second color, said second color dye being soluble in the solvent of said second photoresist composition;

said second color dye interacting sufficiently with the novolak resin of said second composition and being sufficiently compatible therewith as not to form a separate phase from said coated photoresist composition;

said second color dye providing the desired dye density and the predetermined absorption and transmission properties of filter elements to be prepared from said photoresist composition;

said dye being sufficiently transmissive of radiation used for exposure of said photoresist composition as to permit desired control of the solubility of said photoresist composition in areas of exposure, and the formation on development, of a pattern of filter elements of said second color;

(g) drying the solvent coating of said second composition to an adherent layer;

(h) exposing predetermined portions of said layer of said second composition to radiation adapted to increase the solubility of said layer in the exposed areas;

(i) developing said exposed areas to form a second pattern of filter elements;

(j) thermally stabilizing said second pattern of filter elements;

(k) forming a solvent coating of a third dye-containing positive photoresist composition, said third composition being defined as in step (a), except comprising a dye of a third color, said third color dye being soluble in the solvent of said third photoresist composition;

said third color dye interacting sufficiently with the novolak resin of said third composition and being sufficiently compatible therewith as not to form a separate phase from said coated photoresist composition;

said third color dye providing the desired dye density and the predetermined absorption and transmission properties of filter elements to be prepared from said photoresist composition;

said dye being sufficiently transmissive of radiation used for exposure of said photoresist composition as to permit desired control of the solubility of said photoresist composition in areas of exposure, and the formation on development, of a pattern of filter elements of said third color;

(l) drying the solvent coating of said third composition to an adherent layer;

(m) exposing predetermined portions of said layer of said third composition to radiation adapted to increase the solubility of said layer in the exposed areas; and

(n) developing said exposed areas to form a third pattern of filter elements.

20. The method of claim 19 wherein said first, second and third dyes are red, green and blue respectively.

21. The method of claim 19 wherein said first, second and third dyes are yellow, cyan and magenta respectively.