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US 2003/0156276 A1Published application
Aberration mark and method for estimating overlay error and optical aberrations
AssigneeMicron Technology, Inc.
InventorS. W. Bowes
Life of this patent
Estimating the term…
Abstract
An aberration mark for use in an optical photolithography system, and a method for estimating overlay errors and optical aberrations. The aberration mark includes an inner polygon pattern and an outer polygon pattern, wherein each of the inner and outer polygon patterns include a center, and two sets of lines and spaces having a different feature size and pitch that surround the outer polygon pattern. The aberration mark can be used to estimate overlay errors and optical aberrations. In some embodiments, the mark can also be used with scatterometry or scanning electron microscope devices. In other embodiments, the mark can be used to monitor aberrations of a lens in an optical photolithography system.
Claims65
An aberration mark for use in an optical photolithography system, the aberration mark comprising:
- an inner polygon pattern;
- an outer polygon pattern;
- and
- two sets of lines and spaces having a different feature size and pitch that surround the outer polygon pattern.
1 more element
A method for estimating overlay error and optical aberrations in a photolithography system, the method comprising:
- forming an outer polygon pattern on a first layer;
- forming a plurality of first arrays around the outer polygon pattern, the plurality of first arrays including one or more parallel lines having a first pitch;
- forming a plurality of second arrays around the plurality of first arrays, the plurality of second arrays including one or more parallel lines having a second pitch;
- forming an inner polygon pattern on a second layer;
- measuring a translational-displacement between the inner polygon pattern and the outer polygon pattern;
- measuring a line-shortening effect in the first arrays and the second arrays;
- estimating a defocus aberration;
- estimating a coma aberration;
- estimating a spherical aberration;
- and
- estimating an astigmatism aberration.
8 more elements
A calibration structure for use in calibrating an optical photolithography measurement system, the calibration structure comprising:
- a registration structure formed on a substrate and having an inner polygon pattern and an outer polygon pattern as viewed from a point perpendicular to a plane generally defined by the substrate, wherein each of the inner and outer polygon patterns include a center and a plurality of outer sides, wherein two sets of lines and spaces having a different feature size and pitch surround each outer side of the outer polygon pattern, and wherein a displacement between the centers of the inner and outer polygon patterns is selected to be zero, absent any misalignment induced by process fabrication steps.
A calibration structure for use in calibrating a semiconductor manufacturing system, the calibration structure comprising:
- an optical measurement structure formed on a substrate and having an inner polygon pattern and an outer polygon pattern as viewed from a point perpendicular to a plane generally defined by the substrate, wherein each of the inner and outer polygon patterns include a center and a plurality of outer sides, wherein two sets of lines and spaces having a different feature size and pitch surround each outer side of the outer polygon pattern, and wherein a displacement between the centers of the inner and outer polygon patterns is selected to be of a known non-zero magnitude and a known direction, absent any misalignment induced by process fabrication steps.
A registration structure for use in calibrating an optical photolithography system, the registration structure comprising:
- a first calibration structure formed on a substrate and having a first inner polygon pattern and a first outer polygon pattern as viewed from a point perpendicular to a plane generally defined by the substrate, wherein each of the first inner and first outer polygon patterns include a center and a plurality of outer sides, wherein two sets of lines and spaces having a different feature size and pitch surround each outer side of the first outer polygon pattern, and wherein a displacement between the centers of the first inner and first outer polygon patterns is selected to be zero, absent any misalignment induced by process fabrication steps;
- and
- one or more second calibration structures formed on the substrate and located on the substrate in spaced apart relation to each other and to the first calibration structure, each of the second calibration structures having a second inner polygon pattern and a second outer polygon pattern, wherein each of the second inner and second outer polygon patterns include a center and a plurality of outer sides, wherein two sets of lines and spaces having a different feature size and pitch surround each outer side of the second outer polygon pattern, and wherein a displacement between the centers of the second inner and second outer polygon patterns is selected to be zero, absent any misalignment induced by process fabrication steps.
A mask, comprising:
- a circuit pattern, the circuit pattern having one or more reticles, wherein each reticle comprises:
- an inner box;
- an outer box having a plurality of outer sides;
- a first plurality of arrays of parallel lines, wherein one of the first plurality of arrays is adjacent to each outer side of the outer box, and wherein each of the first plurality of arrays has a first pitch;
- and
- a second plurality of arrays of parallel lines, wherein one of the second plurality of arrays is adjacent to each of the first plurality of arrays, and wherein each of the second plurality of arrays has a second pitch.
3 more elements
A wafer, comprising:
- one or more patterned reticle images, wherein each patterned reticle image comprises:
- an inner pattern;
- an outer pattern having a plurality of outer sides;
- a first plurality of arrays of parallel lines, wherein one of the first plurality of arrays is adjacent to each outer side of the outer pattern, and wherein each of the first plurality of arrays has a first pitch;
- and
- a second plurality of arrays of parallel lines, wherein one of the second plurality of arrays is adjacent to each of the first plurality of arrays, and wherein each of the second plurality of arrays has a second pitch.
3 more elements
A method for estimating overlay errors and optical aberrations in a semiconductor fabrication system, the method comprising:
- exposing a mask to light beams emitted from a light source;
- forming a first registration pattern on a first layer of a substrate, the first registration pattern having an outer box, four interior arrays of parallel lines each having a first pitch, and four exterior arrays of parallel lines each having a second pitch, wherein the four interior arrays surround the outer box, and wherein the four exterior arrays surround the four interior arrays;
- forming a second registration pattern on a second layer of the substrate, the second registration pattern having an inner box, such that a displacement between a center of the inner box of the second registration pattern and a center of the outer box of the first registration pattern has a pre-selected value;
- measuring a translational-displacement between the inner box and the outer box in both a horizontal and a vertical direction;
- estimating a defocus aberration in both the horizontal and vertical directions;
- estimating a coma aberration in both the horizontal and vertical directions;
- estimating a spherical aberration in either of the horizontal or vertical directions;
- and
- estimating an astigmatism aberration,
- wherein a first line-shortening effect of the parallel lines of the four interior arrays is different than a second line-shortening effect of the parallel lines of the four exterior arrays.
7 more elements
A method of using an aberration mark during a scatterometry process to estimate optical aberrations, wherein the aberration mark has two schnitzel patterns of different pitch, and wherein the method comprises:
- shining a laser on the aberration mark at an angle;
- capturing an image of a scattering of the laser from the two schnitzel patterns;
- measuring a width of the two schnitzel patterns;
- estimating a defocus aberration;
- estimating a coma aberration;
- estimating a spherical aberration;
- and
- estimating an astigmatism aberration.
5 more elements
A method of using a mark with a scanning electron microscope to estimate overlay errors and optical aberrations, wherein the mark has a box-in-box structure and two schnitzel patterns of different pitch that surround the box-in-box structure, and wherein the method comprises:
- scanning the mark with an electron beam in a vacuum;
- capturing an image of ejected electrons from the two schnitzel patterns;
- measuring a width of the two schnitzel patterns;
- estimating a displacement of the box-in-box structure;
- estimating a defocus aberration;
- estimating a coma aberration;
- estimating a spherical aberration;
- and
- estimating an astigmatism aberration.
6 more elements
An aberration determination mark for determining aberrations when measuring overlay error between different layers of a wafer, the aberration determination mark comprising:
- an outer box formed on a first layer of a substrate, the outer box having a first, second, third, and fourth outer side;
- a first schnitzel pattern on the first layer of the substrate, the first schnitzel pattern comprising:
- a first array separate from and adjacent to the first outer side of the outer box, the first array having parallel lines that run in a direction perpendicular to the first outer side of the outer box;
- a second array separate from and adjacent to the second outer side of the outer box, the second array having parallel lines that run in a direction perpendicular to the second outer side of the outer box;
- a third array separate from and adjacent to the third outer side of the outer box, the third array having parallel lines that run in a direction perpendicular to the third outer side of the outer box;
- and
- a fourth array separate from and adjacent to the fourth outer side of the outer box, the fourth array having parallel lines that run in a direction perpendicular to the fourth outer side of the outer box,
- wherein each of the arrays of the first schnitzel pattern has a first pitch, and wherein each of the parallel lines in the arrays of the first schnitzel pattern has a first length;
- a second schnitzel pattern on the first layer of the substrate, the second schnitzel pattern comprising:
- a first array separate from and adjacent to the first array of the first schnitzel pattern, the first array of the second schnitzel pattern having parallel lines that run in a direction perpendicular to the first outer side of the outer box;
- a second array separate from and adjacent to the second array of the first schnitzel pattern, the second array of the second schnitzel pattern having parallel lines that run in a direction perpendicular to the second outer side of the outer box;
- a third array adjacent to the third array of the first schnitzel pattern, the third array of the second schnitzel pattern having parallel lines that run in a direction perpendicular to the third outer side of the outer box;
- and
- a fourth array separate from and adjacent to the fourth array of the first schnitzel pattern, the fourth array of the second schnitzel pattern having parallel lines that run in a direction perpendicular to the fourth outer side of the outer box,
- wherein each of the arrays of the second schnitzel pattern has a second pitch, each of the parallel lines in the arrays of the second schnitzel pattern has a second length, and wherein the first schnitzel pattern is in between the second schnitzel pattern and the outer box;
- and
- an inner box formed on a second layer of the substrate, wherein the inner box is smaller than the outer box.
14 more elements
A method for estimating a coma optical aberration in an optical photolithography system, the method comprising:
- exposing a mask to light beams emitted from a light source;
- forming an outer box on a first layer of a substrate, the outer box having left, right, upper, and lower outer sides;
- forming a first schnitzel pattern around the outer box on the first layer, the first schnitzel pattern having left, right, upper, and lower arrays of parallel lines of first pitch;
- forming a second schnitzel pattern around the first schnitzel pattern on the first layer, the second schnitzel pattern having left, right, upper, and lower arrays of parallel lines of second pitch;
- forming an inner box on a second layer of the substrate;
- measuring a first horizontal distance between the left outer side of the outer box and a line-end of the left array of parallel lines of the first schnitzel pattern;
- measuring a second horizontal distance between the left outer side of the outer box and a line-end of the left array of parallel lines of the second schnitzel pattern;
- measuring a third horizontal distance between the right outer side of the outer box and a line-end of the right array of parallel lines of the first schnitzel pattern;
- measuring a fourth horizontal distance between the right outer side of the outer box and a line-end of the right array of parallel lines of the second schnitzel pattern;
- measuring a first vertical distance between the upper outer side of the outer box and a line-end of the upper array of parallel lines of the first schnitzel pattern;
- measuring a second vertical distance between the upper outer side of the outer box and a line-end of the upper array of parallel lines of the second schnitzel pattern;
- measuring a third vertical distance between the lower outer side of the outer box and a line-end of the lower array of parallel lines of the first schnitzel pattern;
- measuring a fourth vertical distance between the lower outer side of the outer box and a line-end of the lower array of parallel lines of the second schnitzel pattern;
- estimating a first horizontal pattern-dependent placement shift, the first horizontal pattern-dependent placement shift being substantially equal to the difference between the first horizontal distance and the third horizontal distance;
- estimating a second horizontal pattern-dependent placement shift, the second horizontal pattern-dependent placement shift being substantially equal to the difference between the second horizontal distance and the fourth horizontal distance;
- estimating a first vertical pattern-dependent placement shift, the first vertical pattern-dependent placement shift being substantially equal to the difference between the first vertical distance and the third vertical distance;
- and
- estimating a second vertical pattern-dependent placement shift, the second vertical pattern-dependent placement shift being substantially equal to the difference between the second vertical distance and the fourth vertical distance.
15 more elements
A method for estimating a spherical optical aberration in an optical photolithography system, the method comprising:
- exposing a mask to light beams emitted from a light source;
- forming an outer box on a first layer of a substrate, the outer box having left, right, upper, and lower outer sides;
- forming a first schnitzel pattern around the outer box on the first layer, the first schnitzel pattern having left, right, upper, and lower arrays of parallel lines of first pitch;
- forming a second schnitzel pattern around the first schnitzel pattern on the first layer, the second schnitzel pattern having left, right, upper, and lower arrays of parallel lines of second pitch;
- forming an inner box on a second layer of the substrate;
- measuring a first horizontal distance between the left outer side of the outer box and a line-end of the left array of parallel lines of the first schnitzel pattern;
- measuring a second horizontal distance between the left outer side of the outer box and a line-end of the left array of parallel lines of the second schnitzel pattern;
- measuring a third horizontal distance between the right outer side of the outer box and a line-end of the right array of parallel lines of the first schnitzel pattern;
- measuring a fourth horizontal distance between the right outer side of the outer box and a line-end of the right array of parallel lines of the second schnitzel pattern;
- estimating a first horizontal focus, the first horizontal focus being substantially equal to a first average of the first horizontal distance and the third horizontal distance;
- estimating a second horizontal focus, the second horizontal focus being substantially equal to a second average of the second horizontal distance and the fourth horizontal distance;
- and
- estimating a pattern-dependent focus shift, the first pattern-dependent focus shift being substantially equal to the difference between the first horizontal focus and the second horizontal focus.
10 more elements
A method for estimating a spherical optical aberration in an optical photolithography system, the method comprising:
- exposing a mask to light beams emitted from a light source;
- forming an outer box on a first layer of a substrate, the outer box having left, right, upper, and lower outer sides;
- forming a first schnitzel pattern around the outer box on the first layer, the first schnitzel pattern having left, right, upper, and lower arrays of parallel lines of first pitch;
- forming a second schnitzel pattern around the first schnitzel pattern on the first layer, the second schnitzel pattern having left, right, upper, and lower arrays of parallel lines of second pitch;
- forming an inner box on a second layer of the substrate;
- measuring a first vertical distance between the upper outer side of the outer box and a line-end of the upper array of parallel lines of the first schnitzel pattern;
- measuring a second vertical distance between the upper outer side of the outer box and a line-end of the upper array of parallel lines of the second schnitzel pattern;
- measuring a third vertical distance between the lower outer side of the outer box and a line-end of the lower array of parallel lines of the first schnitzel pattern;
- measuring a fourth vertical distance between the lower outer side of the outer box and a line-end of the lower array of parallel lines of the second schnitzel pattern;
- estimating a first vertical focus, the first vertical focus being substantially equal to a first average of the first vertical distance and the third vertical distance;
- estimating a second vertical focus, the second vertical focus being substantially equal to a second average of the second vertical distance and the fourth vertical distance;
- and
- estimating a pattern-dependent focus shift, the second pattern-dependent focus shift being substantially equal to the difference between the first vertical focus and the second vertical focus.
10 more elements
A method for monitoring aberrations of a lens in an optical photolithography system, the method comprising:
- forming a reticle on a first mask, the reticle having a box-in-box structure and two schnitzel patterns of different pitch that surround the box-in-box structure;
- forming a first image pattern from the reticle during a first photolithography cycle, the first image pattern having a box-in-box structure and two schnitzel patterns of different pitch that surround the box-in-box structure of the first image pattern;
- measuring a first line-shortening effect in the two schnitzel patterns of the first image pattern;
- estimating a baseline set of optical-aberration values of the lens;
- forming the reticle on a second mask;
- forming a second image pattern from the reticle during a second photolithography cycle, the second image pattern having a box-in-box structure and two schnitzel patterns of different pitch that surround the box-in-box structure of the second image pattern;
- measuring a second line-shortening effect in the two schnitzel patterns of the second image pattern;
- estimating a subsequent set of optical-aberration values of the lens;
- and
- comparing the baseline and subsequent set of optical-aberration values of the lens to determine changes.
7 more elements
A method for estimating direction-dependent optical aberrations in a photolithography system, the method comprising:
- patterning an inner polygon mark on a substrate, the inner polygon mark having a plurality of outer sides;
- patterning an outer polygon mark on the substrate, the outer polygon mark having a plurality of outer sides;
- two sets of lines and spaces having a different feature size and pitch that surround each outer side of the outer polygon mark;
- estimating a coma aberration in at least one non-horizontal and non-vertical direction;
- and
- estimating an astigmatism aberration in at least one non-horizontal and non-vertical direction.
3 more elements
A die pattern on a wafer, the die pattern comprising:
- one or more chips, wherein at least one of the one or more chips includes a patterned reticle image, the patterned reticle image comprising:
- an inner pattern;
- an outer pattern having a plurality of outer sides;
- a first plurality of arrays of parallel lines, wherein one of the first plurality of arrays is adjacent to each outer side of the outer pattern, and wherein each of the first plurality of arrays has a first pitch;
- and
- a second plurality of arrays of parallel lines, wherein one of the second plurality of arrays is adjacent to each of the first plurality of arrays, and wherein each of the second plurality of arrays has a second pitch.
3 more elements
A computer system comprising:
- a computer unit, the computer unit having a processor operatively coupled to a memory system, wherein the memory system comprises:
- one or more patterned reticle images, wherein each patterned reticle image comprises:
- an inner pattern;
- an outer pattern having a plurality of outer sides;
- a first plurality of arrays of parallel lines, wherein one of the first plurality of arrays is adjacent to each outer side of the outer pattern, and wherein each of the first plurality of arrays has a first pitch;
- and
- a second plurality of arrays of parallel lines, wherein one of the second plurality of arrays is adjacent to each of the first plurality of arrays, and wherein each of the second plurality of arrays has a second pitch.
4 more elements
Dependencies are inferred from the claim text.