CN113325665A - Overlay error measuring device and method - Google Patents
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- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
- G03F7/70605—Workpiece metrology
- G03F7/70616—Monitoring the printed patterns
- G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
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- G—PHYSICS
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- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
- G03F7/70—Microphotolithographic exposure; Apparatus therefor
- G03F7/708—Construction of apparatus, e.g. environment aspects, hygiene aspects or materials
- G03F7/7085—Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load
Abstract
The invention provides an overlay error measuring device and method. Illumination provided by the illumination unit passes through a first light beam and a second light beam of the light splitting device, the first light beam is transmitted to the substrate through the objective lens and is reflected to the light splitting device through the substrate to form a third light beam, the third light beam is transmitted to the first detection unit, and the first detector acquires a second signal. The second light beam is transmitted to the light splitting device through the light path deflection unit and reflected to the first detection unit through the light splitting device, and the first detector obtains a first signal. The data processor calibrates the second signal according to the first signal to obtain a more accurate alignment error, so that the detection performance of the alignment error measuring device is improved, and the working efficiency is improved.
Description
Technical Field
The invention relates to the technical field of integrated circuit manufacturing, in particular to an overlay error measuring device and method.
Background
As the Critical Dimension (CD) of the lithography pattern enters 22nm and below process nodes, especially the application and development of Double exposure (Double Patterning) and extreme ultraviolet lithography (EUVL), the requirement for the measurement accuracy of the lithography process parameter overlay (overlay) has entered the sub-nanometer field, according to the lithography measurement Technology Roadmap given by the semiconductor industry organization (ITRS). Due to the limitation of Imaging resolution, the conventional Imaging-Based overlay measurement technology (IBO) Based on Imaging and image recognition has gradually failed to meet the requirements of new process nodes on overlay measurement, and the Diffraction-Based overlay measurement technology (DBO) Based on Diffraction light detection and the overlay measurement technology (uDBO) Based on micro-mark Diffraction light detection are gradually becoming the main means of overlay measurement.
However, in a common device or method for measuring overlay errors, the influence of the nonuniformity of the measured illumination light spot on the overlay errors is often ignored, or the calibration overlay mark is moved to be located at a plurality of different positions of the measured illumination light spot, and the device is calibrated according to the sample measurement result.
Therefore, an overlay error measuring device and method are needed to achieve more accurate calibration of the nonuniformity of the measured illumination light spot, so that the detection performance of the overlay error measuring device is improved, and more accurate overlay error is obtained.
Disclosure of Invention
The invention aims to provide an alignment error measuring device and method, which aim to solve the problem that the measurement of the alignment error is influenced by the nonuniformity of a measured illumination light spot.
In order to solve the technical problem, the invention provides an overlay error measuring device, which comprises an illumination unit, a light splitter, a light path turning unit, an objective lens, a first detection unit and a data processor, wherein the illumination unit is used for illuminating the first detection unit; wherein the content of the first and second substances,
the lighting unit is used for providing illumination;
the light splitting device comprises a first light splitting plate and a second light splitting plate, the illumination provided by the lighting unit is split into a first light beam and a second light beam through the first light splitting plate, the first light beam is transmitted to a substrate through the objective lens, is reflected by the substrate, and is transmitted through the objective lens, the first light splitting plate and the second light splitting plate to form a third light beam, and the third light beam is transmitted to the first detection unit;
the second light beam is transmitted to the light path deflection unit, reflected to the light splitting device by the light path deflection unit and reflected to the first detection unit by the second light splitting plate;
the first detection unit comprises a pupil modulator and a first detector, the pupil modulator is used for modulating the second light beam and the third light beam and transmitting the second light beam and the third light beam to the first detector, and the first detector outputs a first signal and a second signal to the data processor;
the data processor is configured to calculate an overlay error based on the first signal and the second signal.
Optionally, in the overlay error measuring apparatus, the light path deflecting unit includes a mirror group, and the light path deflecting unit is configured to transmit the second light beam to the light splitting device after being reflected for multiple times.
Optionally, in the overlay error measuring apparatus, the pupil modulator includes a first aperture stop and an optical wedge; the third light beam contains zero-order diffraction light, positive first-order diffraction light and negative first-order diffraction light;
the first aperture stop is used for blocking the zero-order diffraction light in the third light beam and enabling the positive first-order diffraction light and the negative first-order diffraction light in the third light beam to pass through;
the optical wedge is used for adjusting the propagation angles of the second light beam and the third light beam and transmitting the positive first-order diffraction light and the negative first-order diffraction light in the second light beam and the third light beam to the first detector.
Optionally, in the overlay error measuring apparatus, the first signal is a light intensity distribution of the second light beam, and the second signal is a light intensity distribution of the positive first-order diffracted light and a light intensity distribution of the negative first-order diffracted light in the third light beam.
Optionally, in the overlay error measuring apparatus, the first detecting unit further includes an imaging relay and an imaging lens group, and the imaging relay, the pupil modulator, the imaging lens group, and the first detector are sequentially arranged;
the imaging relay to transmit the second and third light beams to the pupil modulator;
the imaging mirror group is used for imaging the second light beam and the third light beam which pass through the pupil modulator on the first detector.
Optionally, in the overlay error measuring apparatus, the illumination unit includes a light source, an illumination collimator, a second aperture stop, and an illumination relay; wherein the content of the first and second substances,
the light source is used for providing illumination;
the illumination collimator is used for modulating the wavelength of the illumination provided by the light source and adjusting the illumination mode of the illumination by matching with the second aperture diaphragm;
the illumination relay is used for transmitting illumination passing through the second aperture diaphragm to the first light splitting plate.
Optionally, in the overlay error measuring apparatus, a numerical aperture of the objective lens is greater than or equal to 0.9.
Optionally, in the overlay error measuring apparatus, a plurality of sample positions are selected on the substrate, each sample position includes at least four mark units, each mark unit is provided with a measurement mark, the measurement mark includes a first measurement mark and a second measurement mark, the first measurement mark corresponds to the second measurement mark, the first measurement mark is provided with a preset offset relative to the second measurement mark, the preset offset includes a preset offset in a first direction and a preset offset in a second direction, and the first direction is perpendicular to the second direction.
Optionally, in the overlay error measuring apparatus, the first measurement mark and the second measurement mark are both gratings, and the light transmitted by the objective lens is diffracted by the gratings to generate a multi-order diffracted light.
Optionally, in the overlay error measuring apparatus, the overlay error measuring apparatus further includes the second detecting unit, and the second detecting unit includes an angular spectrum imaging component and a second detector;
the first light beam is transmitted through the objective lens, the first light splitting plate and the second light splitting plate to form a fourth light beam, the fourth light beam is transmitted to the second detector through the angular spectrum imaging assembly, the second detector outputs a third signal to the data processor, and the data processor monitors the energy fluctuation of the substrate illumination according to the third signal.
Based on the same inventive concept, the invention also provides an overlay error measuring method, which comprises the following steps:
the method comprises the following steps: selecting a sample position on a substrate as a target to be detected, wherein a plurality of sample positions are preset on the substrate;
step two: the illumination unit provides illumination, the illumination is divided into a first light beam and a second light beam through a first light splitting plate of the light splitter, the first light beam is transmitted to the sample position of the substrate through an objective lens, is transmitted to the objective lens and the first light splitting plate after being reflected by the sample position, and forms a third light beam through a second light splitting plate of the light splitter, the third light beam is transmitted to a first detection unit, and the first detection unit acquires a second signal and transmits the second signal to the data processor; the second light beam is transmitted to the light path turning unit, reflected to the light splitting device through the light path turning unit and reflected to the first detection unit through the second light splitting plate, and the first detection unit acquires a first signal and transmits the first signal to the data processor;
step three: measuring another sample position of the substrate, and repeating the second step until all sample position measurements are completed; and the data processor calibrates the second signal according to the first signal, and calculates an overlay error by using the calibrated second signal.
Optionally, in the overlay error measurement method, the first signal and the second signal are measured for a plurality of times to obtain an average value.
Optionally, in the overlay error measuring method, in the second step, the first signal obtained by the first detector is the light intensity distribution of the second light beam, and the second signal is the light intensity distribution of the first-order diffracted light and the light intensity distribution of the second-order diffracted light at the sample position on the substrate.
Optionally, in the overlay error measuring method, in step one, a plurality of sample positions are preset on the substrate, each sample position includes at least four mark units, each mark unit is provided with a measurement mark, the measurement mark includes a first measurement mark and a second measurement mark, the first measurement mark corresponds to the second measurement mark, the first measurement mark is provided with a preset offset relative to the second measurement mark, and the preset offset includes a preset offset in a first direction and/or a preset offset in a second direction; the preset offset of at least two marking units is in the first direction, the preset offset directions are opposite, but the values of the preset offsets of at least two marking units are equal, and the preset offset directions are opposite, but the values of the preset offsets of at least two marking units are equal; the first direction and the second direction are perpendicular to each other.
Optionally, in the overlay error measuring method, the data processor calibrates the light intensity value of the first-order diffraction and the light intensity value of the second-order diffraction corresponding to the ith marking unit by using the light intensity distribution of the second light beam as a calibration variable, and obtains the asymmetry of the ith unit and the asymmetry of the (i + 1) th unit after calibration, where a calculation formula is as follows:
Aimarking the asymmetry of the cell for the ith;
Ai+1marking the asymmetry of the cell for the (i + 1) th cell;
the preset offset on the ith marking unit and the (i + 1) th marking unit is equal in value but opposite in direction in a first direction or a second direction, and the first direction and the second direction are perpendicular to each other.
Optionally, in the overlay error measuring method, the data processor calculates an overlay error of each marking unit in the first direction or the second direction at each sample position by using the following formula:
Aimarking the asymmetry of the cell for the ith;
Ai+1marking the asymmetry of the cell for the (i + 1) th cell;
delta is a preset offset;
epsilon is the overlay error.
In summary, the present invention provides an overlay error measurement apparatus and method, where the overlay error measurement apparatus includes an illumination unit, a beam splitter, a light path deflecting unit, an objective lens, a first detection unit, and a data processor. The light splitting device comprises a first light splitting plate and a second light splitting plate. Illumination provided by the lighting unit is divided into a first light beam and a second light beam through the first light splitting plate, the first light beam is transmitted to the substrate through the objective lens, is reflected to the light splitting device through the substrate, and forms a third light beam through the second light splitting plate, and the third light beam is transmitted to the first detection unit. The second light beam is transmitted to the light splitting device through the light path deflection unit and is reflected to the first detection unit through the second light splitting plate. The first detection unit comprises a pupil modulator and a first detector, the second light beam and the third light beam are imaged on the first detector respectively through adjustment of the pupil modulator, the first detector acquires a first signal and a second signal and transmits the first signal and the second signal to the data processor, and the data processor calibrates the second signal according to the first signal to obtain a more accurate alignment error, so that the detection performance of the alignment error measuring device is improved, and the working efficiency is improved.
Drawings
FIG. 1 is a schematic diagram of a one-dimensional grating diffraction diagram with zero overlay error according to an embodiment of the present invention;
FIG. 2 is a schematic diagram of one-dimensional grating diffraction with an overlay error less than zero according to an embodiment of the present invention;
FIG. 3 is a schematic diagram of one-dimensional grating diffraction with an overlay error greater than zero according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a two-dimensional grating diffraction pattern with an overlay error smaller than zero in the X-axis direction and smaller than zero in the Y-axis direction according to an embodiment of the present invention;
FIG. 5 is a schematic diagram of a two-dimensional grating diffraction pattern with an overlay error greater than zero in the X-axis direction and less than zero in the Y-axis direction according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a two-dimensional grating diffraction pattern with an overlay error smaller than zero in the X-axis direction and larger than zero in the Y-axis direction according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a two-dimensional grating diffraction pattern with an overlay error greater than zero in the X-axis direction and greater than zero in the Y-axis direction according to an embodiment of the present invention;
FIG. 8 is a schematic structural diagram of an overlay error measurement apparatus according to an embodiment of the present invention;
FIG. 9 is a schematic view of a lens and mirror combination according to an embodiment of the present invention;
FIG. 10 is a schematic view of a first detection unit imaging according to an embodiment of the present invention;
FIG. 11 is a schematic view of a marking unit of an embodiment of the present invention;
wherein the reference numbers indicate:
an M-substrate; 1-a first measurement mark; 2-a second measurement marker; 3-overlay error measuring device;
30-a lighting unit; 31-a light splitting device; 32-objective lens; 33-a second detection unit; 34-a first detection unit; 35-a data processing unit; 36-an optical path deflecting unit;
301-a second aperture stop; 302-a light source; 303-a lighting collimation unit; 304-a lighting relay unit;
311-a first light splitting plate; 312-a second light splitting panel; 331-a second detector; 332-an angular spectrum imaging component; 341-pupil modulator; 342-an imaging relay unit; 343-an imaging mirror group; 344 — a first detector; 361-right angle prism; 362-a combination of lenses and mirrors; 3621-lens; 3622-mirror;
40-a second beam intensity distribution; a positive first-order diffraction light distribution with a preset offset on the 41-X axis; the 42-X axis has the distribution of the negative first-order diffraction light with the preset offset; a positive first-order diffraction light distribution with a preset offset on the 43-Y axis; 44-Y axis has the distribution of the negative first order diffraction light with preset offset;
5-sample position; 51-a first marking unit; 52-second marking element; 53-third marking cell; 54-a fourth marking unit;
a-a first light beam; b-a second light beam; c-a third light beam; d-fourth beam.
Detailed Description
As described above, in a conventional apparatus or method for measuring overlay errors, the influence of the non-uniformity of the illumination spot on the overlay errors is often ignored, or the calibration overlay mark is moved to be located at a plurality of different positions of the illumination spot to be measured, and the apparatus is calibrated according to the measurement result of the sample.
Therefore, an overlay error measuring device and method are needed to achieve more accurate calibration of the nonuniformity of the measured illumination light spot, so that the detection performance of the lithography machine is improved, and more accurate overlay error is obtained.
The following describes an overlay error measurement apparatus and method in detail with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention. Further, the structures illustrated in the drawings are often part of actual structures. In particular, the drawings may have different emphasis points and may sometimes be scaled differently.
In the one-dimensional grating mark, the upper grating shown in fig. 1 is the first measurement mark 1, and is obtained by the second exposure, and is generally a photoresist. The intermediate layer is an intermediate process and can be Si3N4Film, etc., the lower grating being said second measurement mark 2, obtained by a first exposure, typically of the base material silicon. When the second exposure can not completely coincide with the first exposure, relative displacement is generated between the upper layer grating and the lower layer grating, and the displacement is the overlay error epsilon. The overlay error ε is 0 as shown in FIG. 1, ε is shown in FIG. 2<0, e as shown in FIG. 3>0. Incident light is reflected when it is projected into the grating, and the reflected light is diffracted when it passes through the grating layer with multiple slits, resulting in multiple orders of diffracted light. Wherein, I0Denotes zero-order diffracted light, I+、I-Respectively, represent + -1 st order diffracted light. When the alignment error epsilon is equal to 0, the light intensity of the plus or minus 1 order diffraction light is symmetrical, and when the alignment error epsilon is equal to 0, the light intensity of the plus or minus 1 order diffraction light is asymmetrical. Thus, the asymmetry a ═ I is defined+-I-. Within a certain range, the alignment error epsilon and asymmetry satisfy a linear relation, namely A is approximately in direct proportion to the position deviation x of the upper layer and the lower layer of marks, and the relation isIs a (x) kx, k is a constant related to the marking process.
In the two-dimensional grating marks, as shown in fig. 4-7, the first measurement mark 1 and the second measurement mark 2 are respectively provided with a preset offset Δ and an overlay error e on the X axis and the Y axis, where the overlay error is e in the X axis direction and the overlay error is e' in the Y axis direction. The preset offset set in the direction of the same axis is opposite. Therefore, as shown in fig. 4 and 5, the asymmetry a in the X-axis direction is: a. the1(-Δ+ε)＝k(-Δ+ε)，A2(Δ + ε) ═ k (Δ + ε); as shown in fig. 6 and 7, the asymmetry a in the Y-axis direction is: a. the3(-Δ+ε’)＝k(-Δ+ε’)，A4(Δ + ε ') -k (Δ + ε') where I is defined as--I-The following can be obtained:
in the X-axis direction:
in the Y-axis direction:
thus, by means of the apparatusMeasuring
The overlay error epsilon in the X-axis direction and the overlay error epsilon' in the Y-axis direction can be calculated.
However, the measurement illumination has the condition of uneven illumination, that is, the incident light intensities at different positions of the measurement field have different sizes, which can greatly affect the collection of the +/-1 st order diffracted light, and the accuracy of the overlay error can be directly affected. Therefore, when measuring the + -1 order diffraction light, the information of the uneven distribution of the incident light intensity needs to be collected in advance to be the most variable to be calibrated, and the accuracy of the overlay error is improved. Therefore, the alignment error measuring device provided by the embodiment calculates the alignment error value after data calibration by collecting incident light as a calibration variable for measuring illumination nonuniformity.
Referring to fig. 8, the present embodiment provides an overlay error measuring apparatus 3, where the overlay error measuring apparatus 3 includes an illumination unit 30, a light splitter 31, an objective lens 32, a first detection unit 34, a data processor 35, and a light path turning unit 36; wherein, the object to be measured is a substrate M. The lighting unit 30 is used to provide illumination. The light splitting device 31 includes a first light splitting plate 311 and a second light splitting plate 312, the illumination provided by the lighting unit 30 is split into a first light beam a and a second light beam b by the first light splitting plate 311, the first light beam a is transmitted to a substrate M through the objective lens 32, and after being reflected by the substrate M, the first light beam a is transmitted through the objective lens 32, the first light splitting plate 311 and the second light splitting plate 312 to form a third light beam c, and the third light beam c is transmitted to the first detection unit 34. The second light beam b is transmitted to the light path deflecting unit 36, reflected to the light splitting device 31 by the light path deflecting unit 36, and reflected to the first detecting unit 34 by the second light splitting plate 312. The first detection unit 34 comprises a pupil modulator 341 and a first detector 344, the pupil modulator 341 is configured to modulate the second light beam a and the third light beam b and transmit both to the first detector 344, and the first detector 344 outputs a first signal and a second signal to the data processor 35. The data processor 35 is configured to calculate an overlay error based on the first signal and the second signal.
Further, the light path deflecting unit 36 includes a mirror group. The reflector group may be a rectangular prism 361 coated with a light splitting film or a combination 362 of a lens 3621 and a reflector 2622 (as shown in fig. 9), and the illumination provided by the illumination unit 30 enters the optical path folding unit 36, is transmitted to the light splitting device 31 after multiple reflections, and is reflected to the first detection unit 34 by the second light splitting plate 312 in the light splitting device 31. The light intensity distribution of the second light beam b is the calibration variable of the overlay error measurement.
The first detection unit 34 can receive the second light beam b and the third light beam c and transmit them to the data processor 35. The first detection unit 34 comprises a pupil modulator 341, an imaging relay unit 342, an imaging mirror group 343 and a first detector 344. The pupil modulator 341 comprises a first aperture stop and a wedge. The third light beam c contains zero-order diffraction light, positive first-order diffraction light and negative first-order diffraction light, and the first aperture stop can block the zero-order diffraction light in the third light beam c so as to allow the positive first-order diffraction light and the negative first-order diffraction light to pass through.
The optical wedge is used for adjusting the propagation angles of the second light beam b and the third light beam c, transmitting the positive first-order diffraction light and the negative first-order diffraction light in the second light beam b and the third light beam c to the first detector, and respectively imaging at the same time to realize spatial separation of imaging. As shown in fig. 10, 40 is the light intensity distribution of the second light beam b, and 41 is the distribution of the positive first-order diffracted light with a preset offset in the first direction; 42 is the distribution of the minus first order diffracted light with a predetermined offset in the first direction, 43 is the distribution of the plus first order diffracted light with a predetermined offset in the second direction, and 44 is the distribution of the minus first order diffracted light with a predetermined offset in the second direction.
The imaging relay unit 343 is configured to deliver the second beam b and the third beam c to the pupil modulator 341. The imaging mirror group 343 is configured to image the second light beam b and the third light beam c passing through the pupil modulator 341 onto the first detector 344. The light intensity distribution of the second light beam b, which is used by the first detector 344 to obtain, is a first signal, the light intensity distribution of the positive first-order diffracted light and the light intensity distribution of the negative first-order diffracted light in the third light beam c are second signals, and the first detector 344 obtains the first signal and the second signal and transmits the first signal and the second signal to the data processor 35.
The illumination unit 30 comprises a light source 302, an illumination collimator 303, a second aperture stop 301 and an illumination relay 304. The light source 302 is configured to provide illumination, the light source 302 is configured to emit illumination, and the light source 302 may be a mercury lamp, a xenon lamp, or a mixed light source composed of a deuterium lamp and a halogen lamp, or may be a white LED or a plasma excitation light source. The illumination collimating unit 303 comprises a collimator, a filter and a polarizer (not shown), and the illumination collimating unit 303 is configured to modulate the illumination emitted from the light source 302, mainly to modulate the wavelength, the illumination mode, and the like, so as to improve the process adaptability and the signal-to-noise ratio of the apparatus. The second aperture stop 301 in cooperation with the illumination collimating unit 303 may implement different illumination modes.
The second aperture stop 301 may be implemented by driving a plurality of second aperture stops 301 through an electric turntable, or may be implemented by a shutter to perform high-speed switching. When in the first illumination mode, the first detector 344 obtains the first order diffracted light in the third light beam c that characterizes all the mark units on the substrate M. When in the second illumination mode, the first detector 344 obtains the negative first order diffracted light in the third light beam c that characterizes all the mark units on the substrate M. In an actual measurement process, the second aperture stop 301 may employ a shutter to implement a high-speed switching illumination mode, so that the positive first-order diffracted light and the negative first-order diffracted light are imaged on the first detector 344 synchronously. The illumination relay unit 304 is configured to transmit the light passing through the second aperture stop 301 to the first light splitting plate 311 in the light splitting device 31. Since the pupil plane of a typical microscope objective is located inside the objective, the illumination needs to be relayed through the illumination relay unit 304.
Further, the numerical aperture of the objective lens 32 is greater than or equal to 0.9.
Further, a plurality of sample positions are selected on the substrate M, each sample position includes at least four mark units, each mark unit is provided with a measurement mark, the measurement mark includes a first measurement mark 1 and a second measurement mark 2, the first measurement mark 1 corresponds to the second measurement mark 2, the first measurement mark 1 is provided with a preset offset relative to the second measurement mark 2, the preset offset includes a preset offset in a first direction and a preset offset in a second direction, the first direction is perpendicular to the second direction, the first direction is the X-axis direction, and the second direction is the Y-axis direction. The first measuring mark 1 and the second measuring mark 2 are both gratings, and illumination can be diffracted through the gratings to generate multi-level diffraction light.
The overlay error measuring apparatus 3 further comprises the second detection unit 33, which comprises an angular spectrum imaging component 332 and a second detector 331. The first light beam a is transmitted to the surface of the substrate M through the objective lens 32, is transmitted to the first light splitting plate 311 of the light splitting device 31 through reflection, and also forms a fourth light beam d after passing through the second light splitting plate, the fourth light beam d is transmitted to the second detector 331 through the angular spectrum imaging component 332, the second detector 331 obtains an angular spectrum of the fourth light beam d and calculates a corresponding light intensity distribution through fourier transform, and the corresponding light intensity distribution is output to the data processor 35 as a third signal. The third signal is used to characterize energy fluctuations of the illumination of the surface of the substrate M and to assist in optimizing the system configuration.
Based on the same inventive concept, the present embodiment further provides an overlay error measurement method, where the overlay error measurement method includes:
the method comprises the following steps: a sample position 5 on a substrate M is selected as a target to be measured, and a plurality of sample positions 5 are preset on the substrate M. Each of the sample positions includes at least four marking units, as shown in fig. 11, and more units may be designed to improve the measurement accuracy, but it is preferable to provide four marking units for cost reasons and test requirements. The first and third marking units 51, 53 have preset offset amounts Δ in the X-axis direction that are opposite in direction, i.e., preset offset amounts- Δ, Δ in the X-axis direction, respectively, and the second and fourth marking units 52, 54 have preset offset amounts Δ in the Y-axis direction that are opposite in direction, i.e., preset offset amounts- Δ, Δ in the Y-axis direction, respectively.
When the measurement mark is multi-layered, four or more marking units may be preset at the sample position 5 in order to ensure accuracy. For example, 9, the preset offset amount of each marking unit in the X-axis direction or the Y-axis direction may be: -4 Δ, -3 Δ, -2 Δ, - Δ, 0, Δ, 2 Δ, 3 Δ, 4 Δ.
Step two: the illumination unit 30 provides illumination, the illumination is divided into a first light beam a and a second light beam b by the first light splitting plate 311, the first light beam a is transmitted to a sample position 5 of the substrate M by the objective lens 32, is transmitted to the objective lens 32 and the first light splitting plate 311 after being reflected by the sample position 5, and forms a third light beam c by the second light splitting plate 312, a positive first-order diffraction light and a negative first-order diffraction light in the third light beam c are respectively imaged on the first detection unit 34, the first detection unit 34 obtains a positive first-order diffraction light intensity distribution in which an X axis of each marking unit is provided with an opposite preset offset, a negative first-order diffraction light intensity distribution in which an X axis is provided with an opposite preset offset, a positive first-order diffraction light intensity distribution in which a Y axis is provided with an opposite preset offset, and a negative first-order diffraction light intensity distribution in which a Y axis is provided with an opposite preset offset, to be transmitted as a second signal to the data processor 35. The second light beam b is transmitted to the light path deflecting unit 36, reflected to the light splitting device 31 by the light path deflecting unit 36, and reflected to the first detecting unit 34 by the second light splitting plate 312, and the first detecting unit 34 obtains the light intensity distribution of the second light beam b and outputs the light intensity distribution as a first signal to the data processor 35; the data processor 35 calibrates the second signal with the light intensity distribution of the second light beam a, i.e. the first signal, as a calibration variable, thereby obtaining a more accurate overlay error.
Step three: and moving the substrate M to another sample position 5, and repeating the second step until all the sample position 5 measurements are completed.
Further, for example, after the data processor 35 obtains the first signal and the second signal, the light intensity value of the first order diffraction and the light intensity value of the second order diffraction corresponding to the ith marking unit are calibrated according to the first signal, and after the calibration, the asymmetry of the ith unit and the asymmetry of the (i + 1) th unit are obtained, and the calculation formula is as follows:
the preset offset on the ith marking unit and the (i + 1) th marking unit is equal in value but opposite in direction in the X-axis or Y-axis direction. And then obtaining the alignment error epsilon of the sample position in the X-axis or Y-axis direction according to the following formula.
AiMarking the asymmetry of the cell for the ith;
Ai+1marking the asymmetry of the cell for the (i + 1) th cell;
delta is the preset offset of the ith marking unit;
epsilon is the overlay error.
In summary, according to the alignment error measurement device and method provided by the embodiment, the influence of the measurement light spot on the alignment error measurement is reduced by acquiring the incident light intensity distribution information in the measurement field as the calibration variable, the measurement precision is improved, the time cost is saved, and the working efficiency is improved.
The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.
Claims (16)
1. An overlay error measuring device is characterized by comprising an illumination unit, a light splitter, a light path deflection unit, an objective lens, a first detection unit and a data processor; wherein the content of the first and second substances,
the lighting unit is used for providing illumination;
the light splitting device comprises a first light splitting plate and a second light splitting plate, the illumination provided by the lighting unit is split into a first light beam and a second light beam through the first light splitting plate, the first light beam is transmitted to a substrate through the objective lens, is reflected by the substrate, and is transmitted through the objective lens, the first light splitting plate and the second light splitting plate to form a third light beam, and the third light beam is transmitted to the first detection unit;
the second light beam is transmitted to the light path deflection unit, reflected to the light splitting device by the light path deflection unit and reflected to the first detection unit by the second light splitting plate;
the first detection unit comprises a pupil modulator and a first detector, the pupil modulator is used for modulating the second light beam and the third light beam and transmitting the second light beam and the third light beam to the first detector, and the first detector outputs a first signal and a second signal to the data processor;
the data processor is configured to calculate an overlay error based on the first signal and the second signal.
2. The overlay error measuring apparatus according to claim 1, wherein the optical path deflecting unit comprises a mirror group, and the optical path deflecting unit is configured to transmit the second light beam to the light splitting device after multiple reflections.
3. The overlay error measurement apparatus of claim 1 wherein said pupil modulator comprises a first aperture stop and a wedge; the third light beam contains zero-order diffraction light, positive first-order diffraction light and negative first-order diffraction light;
the first aperture stop is used for blocking the zero-order diffraction light in the third light beam and enabling the positive first-order diffraction light and the negative first-order diffraction light in the third light beam to pass through;
the optical wedge is used for adjusting the propagation angles of the second light beam and the third light beam and transmitting the positive first-order diffraction light and the negative first-order diffraction light in the second light beam and the third light beam to the first detector.
4. The overlay error measuring apparatus according to claim 3, wherein the first signal is a light intensity distribution of the second light beam, and the second signal is a light intensity distribution of the plus first order diffracted light and a light intensity distribution of the minus first order diffracted light in the third light beam.
5. The overlay error measurement apparatus of claim 1 wherein the first detection unit further comprises an imaging relay and an imaging mirror group, the imaging relay, the pupil modulator, the imaging mirror group, and the first detector being arranged in sequence;
the imaging relay to transmit the second and third light beams to the pupil modulator;
the imaging mirror group is used for imaging the second light beam and the third light beam which pass through the pupil modulator on the first detector.
6. The overlay error measuring apparatus of claim 1 wherein the illumination unit comprises a light source, an illumination collimator, a second aperture stop, and an illumination relay; wherein the content of the first and second substances,
the light source is used for providing illumination;
the illumination collimator is used for modulating the wavelength of the illumination provided by the light source and adjusting the illumination mode of the illumination by matching with the second aperture diaphragm;
the illumination relay is used for transmitting illumination passing through the second aperture diaphragm to the first light splitting plate.
7. The overlay error measuring apparatus of claim 1 wherein the numerical aperture of the objective lens is greater than or equal to 0.9.
8. The overlay error measuring apparatus according to claim 1, wherein a plurality of sample positions are selected on the substrate, each of the sample positions includes at least four mark units, each of the mark units has a measurement mark disposed thereon, the measurement mark includes a first measurement mark and a second measurement mark, the first measurement mark corresponds to the second measurement mark, the first measurement mark has a predetermined offset with respect to the second measurement mark, the predetermined offset includes a predetermined offset in a first direction and a predetermined offset in a second direction, and the first direction and the second direction are perpendicular to each other.
9. The overlay error measuring apparatus of claim 8 wherein said first measuring mark and said second measuring mark are each a grating, said illumination transmitted by said objective lens being diffracted by said grating to produce diffracted light of multiple orders.
10. The overlay error measurement apparatus of claim 1 further comprising the second detection unit, the second detection unit comprising an angular spectrum imaging assembly and a second detector;
the first light beam is transmitted through the objective lens, the first light splitting plate and the second light splitting plate to form a fourth light beam, the fourth light beam is transmitted to the second detector through the angular spectrum imaging assembly, the second detector outputs a third signal to the data processor, and the data processor monitors the energy fluctuation of the substrate illumination according to the third signal.
11. An overlay error measurement method, characterized by comprising:
the method comprises the following steps: selecting a sample position on a substrate as a target to be detected, wherein a plurality of sample positions are preset on the substrate;
step two: the illumination unit provides illumination, the illumination is divided into a first light beam and a second light beam through a first light splitting plate of the light splitter, the first light beam is transmitted to the sample position of the substrate through an objective lens, is transmitted to the objective lens and the first light splitting plate after being reflected by the sample position, and forms a third light beam through a second light splitting plate of the light splitter, the third light beam is transmitted to a first detection unit, and the first detection unit acquires a second signal and transmits the second signal to the data processor; the second light beam is transmitted to the light path turning unit, reflected to the light splitting device through the light path turning unit and reflected to the first detection unit through the second light splitting plate, and the first detection unit acquires a first signal and transmits the first signal to the data processor;
step three: measuring another sample position of the substrate, and repeating the second step until all sample position measurements are completed; and the data processor calibrates the second signal according to the first signal, and calculates an overlay error by using the calibrated second signal.
12. The overlay error measurement method of claim 11 wherein the first signal and the second signal are averaged over a plurality of measurements.
13. The overlay error measuring method according to claim 11, wherein the first signal obtained by the first detector in the second step is the light intensity distribution of the second light beam, and the second signal is the light intensity distribution of the first order positive diffracted light and the light intensity distribution of the first order negative diffracted light at the sample position on the substrate.
14. The overlay error measuring method according to claim 11, wherein in the first step, a plurality of sample positions are preset on the substrate, each sample position includes at least four mark units, each mark unit has a measuring mark thereon, the measuring mark includes a first measuring mark and a second measuring mark, the first measuring mark and the second measuring mark correspond to each other, and the first measuring mark is provided with a preset offset with respect to the second measuring mark, the preset offset includes a preset offset in a first direction and/or a preset offset in a second direction; the preset offset of at least two marking units is in the first direction, the preset offset directions are opposite, but the values of the preset offsets of at least two marking units are equal, and the preset offset directions are opposite, but the values of the preset offsets of at least two marking units are equal; the first direction and the second direction are perpendicular to each other.
15. The overlay error measuring method according to claim 14, wherein said data processor calibrates the light intensity value of the first order diffraction and the light intensity value of the second order diffraction corresponding to the ith marking unit with the light intensity distribution of the second light beam as a calibration variable, and obtains the asymmetry of the ith unit and the asymmetry of the (i + 1) th unit after calibration, and the calculation formula is as follows:
Aimarking the asymmetry of the cell for the ith;
Ai+1marking the asymmetry of the cell for the (i + 1) th cell;
the preset offset on the ith marking unit and the (i + 1) th marking unit is equal in value but opposite in direction in a first direction or a second direction, and the first direction and the second direction are perpendicular to each other.
16. The overlay error measurement method of claim 15 wherein said data processor calculates the overlay error in the first direction or the second direction for each of the marker cells at each of the sample positions by:
Aimarking the asymmetry of the cell for the ith;
Ai+1marking the asymmetry of the cell for the (i + 1) th cell;
delta is a preset offset;
epsilon is the overlay error.
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Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110102753A1 (en) * | 2008-04-21 | 2011-05-05 | Asml Netherlands B.V. | Apparatus and Method of Measuring a Property of a Substrate |
| US20130258310A1 (en) * | 2012-03-27 | 2013-10-03 | Asml Netherlands B.V. | Metrology Method and Apparatus, Lithographic System and Device Manufacturing Method |
| CN105527794A (en) * | 2014-09-28 | 2016-04-27 | 上海微电子装备有限公司 | Overlay error measurement apparatus and method |
| CN106933046A (en) * | 2015-12-30 | 2017-07-07 | 上海微电子装备有限公司 | Device and survey calibration method for overlay error detection |
-
2020
- 2020-02-28 CN CN202010129746.8A patent/CN113325665A/en active Pending
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20110102753A1 (en) * | 2008-04-21 | 2011-05-05 | Asml Netherlands B.V. | Apparatus and Method of Measuring a Property of a Substrate |
| US20130258310A1 (en) * | 2012-03-27 | 2013-10-03 | Asml Netherlands B.V. | Metrology Method and Apparatus, Lithographic System and Device Manufacturing Method |
| CN105527794A (en) * | 2014-09-28 | 2016-04-27 | 上海微电子装备有限公司 | Overlay error measurement apparatus and method |
| CN106933046A (en) * | 2015-12-30 | 2017-07-07 | 上海微电子装备有限公司 | Device and survey calibration method for overlay error detection |
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