Method and apparatus for self-referenced wafer stage positional error mapping
First Claim
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1. A method of determining inter-field overlay error of a stage on a projection imaging tool, the method comprising:
- exposing a first reticle pattern onto a substrate with a recording media, thereby producing a first exposure, wherein the first reticle pattern includes at least two arrays of alignment attributes such that the arrays of alignment attributes have features complementary to each other and the arrays are offset from each other in distinct directions;
exposing a second reticle pattern onto the substrate thereby producing a second exposure, wherein the second reticle pattern overlaps the first reticle pattern and is shifted in a desired direction so that a single row or column of alignment attributes of the first exposure overlays with a single row or column of complementary attributes of the second exposure, thereby creating an interlocking row or column of completed attributes;
measuring positional offsets of the alignment attributes in the interlocking row or column of completed attributes; and
determining a stage overlay error map from the offsets.
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Abstract
A wafer stage overlay error map is created using standard overlay targets and a special numerical algorithm. A reticle including a 2-dimensional array of standard overlay targets is exposed several times onto a photoresist coated silicon wafer using a photolithographic exposure tool. After exposure, the overlay targets are measured for placement error using a conventional overlay metrology tool. The resulting overlay error data is then supplied to a software program that generates a 2-dimensional wafer stage distortion and yaw overlay error map.
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Citations
50 Claims
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1. A method of determining inter-field overlay error of a stage on a projection imaging tool, the method comprising:
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exposing a first reticle pattern onto a substrate with a recording media, thereby producing a first exposure, wherein the first reticle pattern includes at least two arrays of alignment attributes such that the arrays of alignment attributes have features complementary to each other and the arrays are offset from each other in distinct directions;
exposing a second reticle pattern onto the substrate thereby producing a second exposure, wherein the second reticle pattern overlaps the first reticle pattern and is shifted in a desired direction so that a single row or column of alignment attributes of the first exposure overlays with a single row or column of complementary attributes of the second exposure, thereby creating an interlocking row or column of completed attributes;
measuring positional offsets of the alignment attributes in the interlocking row or column of completed attributes; and
determining a stage overlay error map from the offsets. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A method of determining inter-field overlay error of a stage on a projection imaging tool, the method comprising:
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exposing a first reticle pattern onto a substrate with a recording media;
exposing a second reticle pattern onto the substrate, wherein the second reticle pattern overlaps the first reticle pattern and is shifted in a desired direction so that a single row or column of alignment attributes of the first exposure overlays with a single row or column of complementary attributes of the second exposure thereby creating an interlocking row or column of completed attributes;
measuring positional offsets of the alignment attributes in the interlocking row or column;
providing additional substrates with recording media and repeating the steps of exposing a first reticle pattern, and exposing a second reticle pattern, and measuring the positional error for a desired number of substrates; and
determining a stage overlay error map by averaging the positional offsets of the desired number of substrates.
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43. A method of determining inter-field overlay error of a stage on a projection imaging tool, the method comprising:
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providing a reticle with a pattern of at least two arrays of alignment attributes, wherein the arrays of alignment attributes have features complementary to each other and the arrays are offset from each other in distinct directions;
exposing a first reticle pattern, using an exposure level below a minimum dose, onto a substrate with a recording media;
exposing a second reticle pattern, using an exposure level below a minimum dose, onto the substrate, wherein the second reticle pattern overlaps the first reticle pattern and is shifted in a desired direction so that a single row or column of alignment attributes of the first exposure overlays with a single row or column of complementary attributes of the second exposure thereby creating an interlocking row or column of completed attributes;
repeating exposing the second reticle pattern a desired number of times;
measuring positional offsets of the alignment attributes in the interlocking row or column; and
determining a stage overlay error map from the positional offsets.
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44. A reticle used for determining inter-field overlay error of a stage on a projection imaging tool, the reticle comprising:
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a first set of alignment attributes disposed along a first column;
a second set of alignment attributes that are complementary to the first set of alignment attributes, the second set of alignment attributes disposed along a second column distinct from the first column, wherein the alignment attributes in the first and second sets are aligned in corresponding rows;
a third set of alignment attributes distributed along a first row between the first and second column; and
a fourth set of attributes complementary to the third set of attributes, the fourth set of alignment attributes disposed in a second row distinct from the first row, wherein the alignments attributes in the third and fourth sets are aligned in corresponding columns. - View Dependent Claims (45, 46, 47)
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48. An apparatus for determining inter-field overlay error of a stage on a projection imaging tool, the apparatus comprising:
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means for providing a reticle with a pattern of at least two arrays of alignment attributes, wherein the arrays of alignment attributes have features complementary to each other and the arrays are offset from each other in distinct directions;
means for exposing a first reticle pattern onto a substrate with a recording media;
means for exposing a second reticle pattern onto the substrate, wherein the second reticle pattern overlaps the first reticle pattern and is shifted in a desired direction so that a single row or column of alignment attributes of the first exposure overlays with a single row or column of complementary attributes of the second exposure thereby creating an interlocking row or column of completed attributes;
means for measuring positional offsets of the alignment attributes in the interlocking row or column; and
means for determining a stage overlay error map from the offsets.
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49. An apparatus for determining inter-field overlay error of a stage on a projection imaging tool, the apparatus comprising:
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means for providing a reticle with a pattern of at least two arrays of alignment attributes, wherein the arrays of alignment attributes have features complementary to each other and the arrays are offset from each other in distinct directions;
means for exposing a first reticle pattern, using an exposure level below a minimum dose, onto a substrate with a recording media;
means for exposing a second reticle pattern, using an exposure level below a minimum dose, onto the substrate, wherein the second reticle pattern overlaps the first reticle pattern and is shifted in a desired direction so that a single row or column of alignment attributes of the first exposure overlays with a single row or column of complementary attributes of the second exposure thereby creating an interlocking row or column of completed attributes;
means for repeating exposing the first reticle pattern and the second reticle pattern a desired number of times;
means for measuring positional offsets of the alignment attributes in the interlocking row or column; and
means for determining a stage overlay error map from the offsets.
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50. A reticle used for determining inter-field overlay error of a stage on a projection imaging tool, the reticle comprising:
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means for producing a first set of alignment attributes disposed along a first column;
mean for producing a second set of alignment attributes that are complementary to the first set of alignment attributes, the second set of alignment attributes disposed along a second column distinct from the first column, wherein the alignment attributes in the first and second sets are aligned in corresponding rows;
means for producing a third set of alignment attributes distributed along a first row between the first and second column; and
means for producing a fourth set of attributes complementary to the third set of attributes, the fourth set of alignment attributes disposed in a second row distinct from the first row, wherein the alignment attributes in the third and fourth sets are aligned in corresponding columns.
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Specification