Double rim phase shifter mask
First Claim
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1. A double rim phase shifter mask, comprising:
- a transparent substrate;
a patterned layer of partially transmitting material having pattern edges formed on said transparent substrate;
a patterned layer of phase shifting material having pattern edges formed on said patterned layer of partially transmitting material wherein said pattern edges of said patterned layer of phase shifting material extend beyond said patterned edges of said patterned layer of partially transmitting material; and
a patterned layer of opaque material having pattern edges formed on said patterned layer of phase shifting material wherein said pattern edges of said patterned layer of phase shifting material extend beyond said pattern edges of said patterned layer of opaque material and said pattern edges of said patterned layer of partially transmitting material extend beyond said pattern edges of said patterned layer of opaque material.
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Abstract
This invention describes the fabrication and use of a double rim phase shifter mask comprised of patterned layers of phase shifting material, partially transmitting material, and opaque material formed on a transparent substrate. Since the partially transmitting material is used as a rim at the pattern edge the light intensity transmitted to the wafer is not limited by the transmitting percentage of the partially transmitting material. The mask is self aligned and is readily manufacturable. Image resolution and depth of focus is improved over other photomasks.
15 Citations
21 Claims
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1. A double rim phase shifter mask, comprising:
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a transparent substrate; a patterned layer of partially transmitting material having pattern edges formed on said transparent substrate; a patterned layer of phase shifting material having pattern edges formed on said patterned layer of partially transmitting material wherein said pattern edges of said patterned layer of phase shifting material extend beyond said patterned edges of said patterned layer of partially transmitting material; and a patterned layer of opaque material having pattern edges formed on said patterned layer of phase shifting material wherein said pattern edges of said patterned layer of phase shifting material extend beyond said pattern edges of said patterned layer of opaque material and said pattern edges of said patterned layer of partially transmitting material extend beyond said pattern edges of said patterned layer of opaque material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of forming a double rim phase shifter mask, comprising the steps of:
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providing a transparent substrate; forming a layer of partially transmitting material on said transparent substrate; forming a layer of phase shifting material on said layer of partially transmitting material; forming a layer of opaque material on said layer of phase shifting material; forming a layer of photoresist on said layer of opaque material; forming a photoresist mask by exposing and developing a first pattern having pattern edges in said layer of photoresist; forming a second pattern having pattern edges in said layer of opaque material by means of isotropically etching said layer of opaque material through said photoresist mask so that said pattern edges of said first pattern in said layer of photoresist extend beyond said pattern edges in said second pattern in said layer of opaque material; forming a third pattern having pattern edges in said layer of phase shifting material by means of vertically anisotropically etching said layer of phase shifting material through said photoresist mask so that said pattern edges of said first pattern in said layer of photoresist are directly above said pattern edges of said third pattern in said layer of phase shifting material; forming a fourth pattern having pattern edges by means of isotropically etching said layer of partially transmitting material through said photoresist mask so that said pattern edges of said first pattern in said layer of photoresist extend beyond said pattern edges of said fourth pattern in said layer of partially transmitting material; and stripping said layer of photoresist. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification