Self-aligned fabrication technique for tri-tone attenuated phase-shifting masks
AssigneeNumerical Technologies, Inc.
InventorChristophe Pierrat
Life of this patent
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Abstract
A structure and method are provided to ensure self-aligned fabrication of a tri-tone attenuated phase-shifting mask. A sub-resolution, 0 degree phase, greater than 90% transmission rim is provided along the edge of an opaque region. The alignment of this sub-resolution rim with the opaque and attenuated regions of the mask is performed in a single patterning step. In one embodiment, a narrow opaque region can be replaced by a sub-resolution, 0 degree phase, greater than 90% transmission line.
Claims52
A lithographic mask comprising:
- a plurality of structures,
- wherein a subset of the structures include an opaque region, an attenuated region, and a sub-resolution transparent rim between the opaque region and the attenuated region.
A method of forming a plurality of structures in an attenuated phase-shifting mask, wherein a subset of the structures are formed by a first region and a second region, wherein the first region has a phase shift relative to the second region of 180 degrees, the method comprising:
- providing a third region within a boundary for the second region;
- and
- providing a sub-resolution rim within the boundary of the second region and adjacent a boundary for the third region.
A method of forming a plurality of structures in an attenuated phase-shifting mask, wherein a subset of the structures are formed by a transparent region and an attenuated region, wherein the transparent region has a phase shift relative to the attenuated region of 180 degrees, the method comprising:
- providing an opaque region within a boundary for the attenuated region;
- and
- providing a sub-resolution rim within the boundary of the attenuated region and adjacent a boundary for the opaque region.
A method of fabricating an attenuated phase-shifting mask, the method comprising:
- providing a transparent layer;
- providing an attenuated layer on the transparent layer, wherein a phase shift of the attenuated layer relative to the transparent layer is approximately 180 degrees;
- providing an opaque layer on the attenuated layer;
- providing a first resist layer on the opaque layer;
- and
- patterning the first resist layer to provide an alignment for an attenuated region, an opaque region, and a sub-resolution rim.
Computer software for forming an attenuated phase-shifting mask from a blank, the blank including a transparent layer, an attenuated layer, and an opaque layer, the attenuated phase-shifting mask including a plurality of structures, a subset of the structures including a transparent region, an attenuated region, an opaque region formed within the attenuated region, a transparent rim formed adjacent the opaque region, the software comprising:
- means for aligning the attenuated region, the opaque region, and the transparent rim simultaneously.
Computer software to convert an integrated circuit layout into an attenuated phase-shifting mask layout for fabricating the integrated circuit, the software comprising:
- means for identifying a subset of structures in the integrated circuit layout;
- and
- means for converting the subset of structures into the mask layout, wherein each converted structure includes a transparent region, an attenuated region formed within the transparent region, an opaque region formed within the attenuated region, and a sub-resolution transparent rim formed adjacent the opaque region.
A method of fabricating an integrated circuit, the method comprising:
- radiating a plurality of lithographic masks, at least one mask comprising:
- a plurality of structures,
- wherein a subset of the structures include an opaque region, an attenuated region, and a sub-resolution transparent rim between the opaque region and the attenuated region;
- focusing emanating radiation from the at least one mask onto a resist layer provided on a wafer;
- and
- developing the resist layer to form the integrated circuit.
A method of converting a binary mask layout into a tri-tone, attenuating mask layout, the method comprising:
- dividing up a structure on the binary mask layout into one or more polygons,
- wherein if the width of a polygon is smaller than a first width W1, then replacing the polygon with a first structure including only an attenuated portion,
- wherein if the width of the polygon is between the first width W1 and a second width W2, then replacing the polygon with a second structure including a sub-resolution line formed in the middle of an attenuated portion, and
- wherein if the width of the polygon is larger than the second width W2, then replacing the polygon with a third structure including an opaque portion surrounded by a sub-resolution rim, which in turn is surrounded by an attenuated portion.
A mask including a plurality of structures, the plurality of structures representing a layer of an integrated circuit, the mask including:
- means for providing a sub-resolution feature associated with at least one structure, the feature having an approximately 0 degree phase shift.
Dependencies are inferred from the claim text.