Cost-effective method to fabricate a combined attenuated-alternating phase shift mask
AssigneeTaiwan Semiconductor Manufacturing Company, Ltd.
InventorsSan-De Tzu, Ching-Shiun Chiu, Wei-Zen Chou
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Abstract
A mask combining an alternating phase shift part and an attenuating phase shift part on a single blank and a method of forming said mask. The method involves fewer processing steps, fewer layers of material and is more cost effective than other methods in the current art. A central reason for the simplicity of the method is the use of different intensity levels of E-beam exposure in a single resist layer and achieving phase shifts by transmitting radiation through alternating regions of the same transparent substrate that are etched and not etched.
Claims42
A method for fabricating a mask combining an attenuating phase shift part and an alternating phase shift part on the same mask blank, comprising:
- providing a mask blank comprising a transparent substrate on which has been sequentially deposited a first mask layer and a second mask layer;
- depositing on said mask blank a first layer of resist material;
- exposing said first layer of resist material with two deposition amounts of exposure energy, wherein a more deeply penetrating amount penetrates to the second mask layer, whereas the less deeply penetrating amount, outlines a shallow rim region;
- removing the exposed areas of the first resist layer by developing and baking;
- subjecting the exposed second mask layer to a dry etch, removing both the second mask layer and the first mask layer immediately below said second mask layer;
- applying a highly selective and anisotropic etch to the surface of the first resist layer, selectively etching down the shallow rim region to expose the second mask layer beneath it;
- etching away said second mask layer to expose the first mask layer surrounding the rim region;
- removing the remaining first resist layer;
- depositing a second resist layer on the mask;
- exposing said second resist layer to an exposure intensity sufficient to delineate the portions of the transparent substrate that will not phase shift;
- developing and baking the exposed regions of the second resist layer to expose the surface of the transparent substrate below;
- subjecting said surface of the optically transparent substrate to a dry etch to a depth of approximately 2700 angstroms below the surface of the substrate;
- removing the remaining second resist layer.
A method for fabricating a mask combining an attenuating phase shift part and an alternating phase shift part on the same mask blank, comprising:
- providing a mask blank comprising a transparent substrate on which has been sequentially deposited a first mask layer and a second mask layer;
- depositing on said mask blank a first layer of resist material;
- exposing said layer of resist material with three intensity levels of exposure energy, wherein the highest intensity level penetrates to the depth of the second mask layer, the least intense level outlines a shallow depth rim region and the intermediate intensity level penetrates to a depth between those two depths;
- removing the exposed areas of the first resist layer by developing and baking;
- removing the second mask layer exposed by the resist development with a first etch;
- applying a second etch to the regions from which the second mask layer has been removed, said etch penetrating the first mask layer and penetrating into the transparent substrate;
- applying a highly selective and anisotropic etch to the surface of the resist layer, selectively etching down the regions of the resist layer exposed to the intermediate exposure energy to the depth of the second mask layer;
- etching though said second mask layer with a dry etch;
- applying a highly selective and anisotropic etch to the surface of the resist layer to etch back the shallow rim region produced by the lowest exposure energy to the depth of the second mask layer;
- etching away said second mask layer with a wet etch to the depth of the first mask layer;
- removing the remaining resist layer.
A mask combining an attenuated phase shift part and an alternating phase shift part on the same mask blank, comprising:
- a mask blank comprising a transparent substrate on which has been sequentially deposited a first mask layer and a second mask layer;
- an alternating phase shift part consisting of regions from which the first and second mask layers have been removed from the transparent substrate and said substrate has been etched to a certain depth;
- an attenuated phase shift part consisting of an isolated region from whose center the two mask layers have been removed, having an annular rim region from which only the second mask layer has been removed.
Dependencies are inferred from the claim text.