Composite resist structures

Claim 2

A composite resist structure for the manufacture of integrated circuits, the resist structure being comprised of (a) a first underlayer of an aqueous alkaline soluble positive photoresist composition and (b) a second, top layer composition comprised of the reaction product of (1) a novolak type cresol-­formaldehyde resin represented by the formula wherein R and R₁ are independently selected from hydrogen, an alkyl group containing 1 to 3 carbon atoms, a halogen atom and an alkoxy group containing 1 to 3 carbon atoms, and (2) 1,2-naphthoquinone-2-­diazidio-4 sulfonyl chloride represented by the formula wherein R and R₁ are independently selected from hydrogen, an alkyl group containing 1 to 3 carbon atoms, a halogen atom and an alkoxy group containing 1 to 3 carbon atoms.

Claim 3

The composite resist structure of Claim 1 wherein the first underlayer composition is comprised of a novolak-type phenol formaldehyde resin sensitized with a diazoquinone compound.

Claim 4

The composite resist structure of Claim 1 wherein a sensitizer is incorporated in the top layer composition.

Claim 5

The composite resist structure of Claim 3 wherein the sensitizer is the reaction product of bis (4,8-hydrosymethyl)-tricyclo [5.2.1.0. 2,6 ] decane and a 1,2-naphthoquinone-2-diazidio-4sulfonyl chloride represented by the formula wherein R and R₁ are independently selected from hydrogen, and alkyl group containing 1 to 3 carbon atoms, a halogen atom, and a alkoxy group containing 1 to 3 carbon atoms.

Claim 6

The composite resist structure of Claim 1 wherein the top layer is comprised of a mixture of about 75 to about 90 percent by weight of the reaction product of 1,2-naphthoquinone-2-diazidio-4-sulfonyl chloride and a novolak-type cresol-formaldehyde resin represented by the formula and about 10 to about 25 percent by weight of a sensitizer.

Claim 7

The composite structure of Claim 5 wherein the reaction product is the reaction product of about 0.8 to about 2.5 equivalents of 1,2-naphthoquinone-2-diazidio-4-­sulfonyl chloride per 1 equivalent of the novolak resin.

Claim 8

A process for the preparation of a composite resist structure for use in a lift-off process which comprises coating a substrate sequentially with a first layer comprised of an aqueous alkaline soluble positive photoresist composition, overcoating the first layer with a second layer comprised of the reaction product of (1) a novolak type cresol-formaldehyde resin represented by the formula wherein R and R₁ are independently selected from a hydrogen atom, an alkyl group containing 1 to 3 carbon atoms, a halogen atom and an alkoxy group containing 1 to 3 carbon atoms, and (2) 1,2-naphthoquinone-2-­diazidio-4-sulfonyl chloride represented by the formula wherein R and R₁ are independently selected from hydrogen, an alkyl group containing 1 to 3 carbon atoms a halogen atom and an alkoxy group containing 1 to 3 carbon atoms, the second layer having a solubility in alkaline media which is less than that of the first layer, patternwise exposing the layers with a source of radiation and then developing the layers in an alkaline medium.

Claim 9

A process for the preparation of a composite resist structure for use in a lift-off process which comprises coating a substrate sequentially with a first layer comprised of an aqueous alkaline soluble positive photoresist composition, overcoating the first layer with a second layer comprised of the reaction product of (1) a novolak type cresol-formaldehyde resin represented by the formula wherein R and R₁ are independently selected from a hydrogen atom, an alkyl group containing 1 to 3 carbon atoms, a halogen atom and an alkoxy group containing 1 to 3 carbon atoms, and (2) 1,2-naphthoquinone-2-­diazidio-4-sulfonyl chloride represented by the formula wherein R and R₁ are independently selected from hydrogen, an alkyl group containing 1 to 3 carbon atoms a halogen atom and an alkoxy group containing 1 to 3 carbon atoms, the second layer having a solubility in alkaline media which is less than that of the first layer, patternwise exposing the layers with a source of radiation and then developing the layers in an alkaline medium.

Claim 10

The process of Claim 7 wherein the first layer is comprised of a novolak-type phenol-formaldehyde resin and a diazoquinone sensitizer.

Claim 11

The process of Claim 7 wherein a sensitizer is incorporated in the top layer composition.

Claim 12

The process of Claim 9 wherein the sensitizer is the reaction product of bis (4,8-hydroxymethyl)-tricyclo [5.2.1.0. 2,6 ] decane and a 1,2-naphthoquinone-2-­diazidio-4-sulfonyl chloride represented by the formula wherein R and R₁ are independently selected from hydrogen, an alkyl group containing 1 to 3 carbon atoms, a halogen atom, and an alkoxy group containing 1 to 3 carbon atoms.

Claim 13

The process of Claim 7 wherein the second layer reaction product is the reaction product of 1,2-naphthoquinone-2-diazidio-4-sulfonyl chloride and a novolak phenol-formaldehyde resin represented by the formula

Claim 14

The process of Claim 11 wherein the reaction product is the reaction product about 0.8 to about 2.5 equivalents of 1,2-naphthoquinone-2-diazidio-4-sulfonyl chloride per 1 equivalent of the novolak resin.

Claim 15

The process of Claim 7 wherein the substrate is softbaked at about 60° to about 150°C for about 1 to 30 minutes before the deposit of the second layer thereon.

Claim 16

The process of Claim 7 wherein the substrate is baked at about 75° to about 150°C for about 1 to about 40 minutes after application of the second layer and before image-wise exposure.

Claim 17

The process of Claim 6 wherein the exposed layers are developed in a solution whose major component is alkaline water.

Claim 18

The process of Claim 5 wherein the first layer has a thickness of about 1.0 to about 4.0 µm and the second layer has a thickness of about 0.1 to about 1.0 µm.