Photoresists comprising novolak resin blends

Abstract

Photoresist compositions are provided comprising a radiation sensitive component and at least two distinct novolak resins. In one aspect, photoresists of the invention exhibit notably high dissolution rates, such as in excess of 800 angstroms per second in aqueous developer solution. In another aspect, photoresists of the invention can exhibit good photospeeds, such as 100 mJ/cm.sup.2 or less.

Claims

1. A photoresist composition comprising: (i) (a) a radiation sensitive component comprising a polymeric diazo-naphthoquinone material and (b) a non-polymeric diazonaphthoquinone photoactive compound; and (ii) at least two distinct novolak resins that comprise 1) a cresol-formaldehyde reaction product and 2) a reaction product of benzaldehyde and/or salicylaldehyde, wherein both of the two distinct novolak resins have a molecular weight (weight average) of less than 2000 but not less than 1000, wherein the photoresist exhibits a photospeed of 100 mJ/cm.sup.2 or less, and wherein the at least two distinct novolak resins comprise (a) 50 to 65 wt % cresol reaction product based on total weight of the novolak resins and polymeric diazo-naphthoquinone material and (b) 5 to 30 wt % benzaldehyde and/or salicylaldehyde resin based on total weight of the novolak resins and polymeric diazo-naphthoquinone material; and wherein the polymeric diazo-naphthoquinone material is present in an amount of 10 to 30 weight percent based on total weight of the novolak resins and polymeric diazo-naphthoquinone material.

2. The photoresist composition of claim 1, wherein the photoresist exhibits a dissolution rate of 800 angstroms per second or more in an aqueous alkaline developer solution.

3. A method of forming a photoresist relief image, comprising: (A) applying a photoresist composition on a semiconductor substrate, the photoresist composition comprising: (i) (a) a radiation sensitive component comprising a polymeric diazo-naphthoquinone material and (b) a non-polymeric diazonaphthoquinone photoactive compound; and (ii) at least two distinct novolak resins that comprise 1) a cresol reaction product and 2) a reaction product of benzaldehyde and/or salicylaldehyde, wherein both of the two distinct novolak resins have a molecular weight (weight average) of less than 2000 but not less than 1000, wherein the photoresist exhibits a photospeed of 100 mJ/cm.sup.2 or less, and wherein the at least two distinct novolak resins comprise (a) 50 to 65 wt % cresol-formaldehyde reaction product based on total weight of the novolak resins and polymeric diazo-naphthoquinone material and (b) 5 to 30 wt % benzaldehyde and/or salicylaldehyde resin based on total weight of the novolak resins and polymeric diazo-naphthoquinone material; wherein the polymeric diazo-naphthoquinone material is present in an amount of 10 to 30 weight percent based on total weight of the novolak resins and polymeric diazo-naphthoquinone material; (B) exposing and developing the photoresist layer to provide a resist relief image.

4. The method of claim 3 wherein the photoresist composition is exposed with radiation having a wavelength of 365 nm.

Description

EXAMPLE 1

Photoresist Composition Preparation and Lithographic Processing

(1) A photoresist composition was prepared by admixing the following materials in amounts specified below:

(2) Resin Component

(3) (2,5-xylenol)-(m-cresol)-(p-cresol)formaldehyde resin benzaldehyde-salicylaldehyde novolak resin

(4) Photoactive Component

(5) Diazonaphthoquinone ester of benzaldehyde-salicylaldehyde novolak resin glycouril resin

(6) 2,1,4-diazonaphthoquinone (non-polymeric)

(7) Additives

(8) Leveling Agent of Silwet

(9) Adhesion promoter of polyvinyl ethyl ether

(10) Solvent

(11) Ethyl lactate

(12) Amyl acetate

(13) Anisole

(14) The (2,5-xylenol)-(m-cresol)-(p-cresol) formaldehyde resin was prepared from a monomer charge of p-cresol 65 weight percent, m-cresol 34.5 weight percent and xylenol 2.5 weight percent. The three components (“resin solids”) of 1) (2,5-xylenol)-(m-cresol)-(p-cresol) formaldehyde resin, 2) benzaldehyde-salicylaldehyde novolak resin and 3) diazonaphthoquinone ester of benzaldehyde-salicylaldehyde novolak resin glycouril resin were present in the photoresist composition in the following relative weight percent based on total weight of these resin solids: 1) cresol resin—59%, 2) benzaladehyde resin—15%, 3) DNQ resin—26%. The 2,1,4-diazonaphthoquinone was present in the photoresist composition in 3 weight percent relative to resin solids. The leveling agent and adhesion promoter were both present in the photoresist composition in amounts of 1 weight percent each relative to the resin solids.

(15) The photoresist composition was spin-coated onto a wafer substrate, soft-baked to remove solvent, exposed to 365 nm radiation and developed with 0.26 N alkaline aqueous developer. The photoresist provided good quality relief images. Photospeed of the resist composition 54 mJ/cm.sup.2 for 365 nm radiation.