Overlay mark scatterometry method, apparatus, and lithography machine

Abstract

The application provides a device for overlay mark scatterometry, comprising: an illumination unit, an objective, a light splitting unit, a first detection unit and a second detection unit; wherein the illumination unit is used for providing a measuring beam; the first detection unit is located at a pupil plane of the objective, and the second detection unit is located at an image plane of the objective; the measuring beam provided by the illumination unit is transmitted to a substrate with an overlay mark through the light splitting unit and the objective, and forms a first beam after being reflected by the substrate with the overlay mark; the first beam is transmitted to the objective and the light splitting unit, and forms a second beam and a third beam after being split by the light splitting unit; the second beam is transmitted to the first detection unit, and the third beam is transmitted to the second detection unit; and an overlay error of the overlay mark on the substrate is obtained according to a signal detected by the first detection unit and a signal detected by the second detection unit.

Description

Technical Field

[0001] This invention relates to the field of integrated circuit manufacturing technology, and in particular to a method, apparatus and lithography machine for measuring the scattering of overlay marks. Background Technology

[0002] DBO (Diffraction Base Overlay) markings refer to overlay markings based on diffraction. A DBO marking consists of an upper grating marking and a lower grating marking. The lower grating marking has already been etched, and there are intermediate process layers between the upper and lower grating markings. The upper grating marking is the photoresist marking after processing. The positional deviation between the upper and lower grating markings reflects the positional deviation of the actual pattern.

[0003] When Overlay≠0, the magnitudes of the + / -1 diffraction light intensity generated on the upper and lower grating marks are asymmetrical.

[0004] The difference between + / -1 level light intensity is the asymmetry. When both the Overlay and the preset offset Δ are small, the asymmetry A is proportional to the magnitude of the deviation between the upper and lower layer marks, with a scaling factor of k.

[0005]

[0006] in and Let i and y be the light intensities measured at the +1 and -1 levels on the i-th pad, respectively, where i = 1, 2. Then the overlay can be obtained as:

[0007]

[0008] Formula (2) is the traditional formula for calculating overlay based on scattering measurements. Calculating the overlay requires knowing the relevant information independently. and There are a total of 4 light intensities. If all of them are expanded into the form of light intensities, formula (2) can be written as:

[0009]

[0010] With the increasing demands of overlay measurement processes, overlay markers based on scattering measurements are evolving towards smaller sizes, leading to the emergence of a diffraction-based micro overlay measurement marker (μDBO marker, Micro DiffractionBase Overlay). This diffraction-based micro overlay measurement marker consists of four pads: the pads in quadrants 1 and 3 measure the overlay in the Y direction, while the pads in quadrants 2 and 4 measure the overlay in the X direction. Markers along the same line direction have opposite preset offsets.

[0011] Common optical paths for overlay mark scattering measurement, such as Figure 1 As shown, the basic principle remains the same: calculating the overlay using the asymmetry of the + / -1 order light intensity. The diffraction-based miniature overlay measurement uses a camera in the imaging optical path to acquire the image plane signal. Dark-field measurement is employed, and aperture 21 filters the 0th order light, leaving the remaining +1 or -1 order light to image on the image plane. Aperture 13 allows selection of either the +1 or -1 order light for imaging. Since a single overlay measurement must measure the intensity asymmetry of the +1 and -1 order lights, each measurement requires switching the illumination aperture 13 at least once and taking separate images, significantly impacting yield. Summary of the Invention

[0012] The purpose of this invention is to provide a method, apparatus and lithography machine for measuring the scattering of overlay marks, so as to solve the problems of long time consumption and low yield caused by multiple aperture switching.

[0013] To solve the above-mentioned technical problems, the present invention provides an apparatus for measuring the scattering of overlaid marks, comprising: an illumination unit, an objective lens, a beam splitting unit, a first detection unit, and a second detection unit; wherein,

[0014] The illumination unit is used to provide a measuring beam;

[0015] The first detection unit is located on the pupil plane of the objective lens, and the second detection unit is located on the image plane of the objective lens;

[0016] The measurement beam provided by the illumination unit is transmitted to the substrate with overlay marks via the beam splitting unit and the objective lens, and is reflected by the substrate with overlay marks to form a first beam. The first beam is transmitted to the objective lens and the beam splitting unit, and is split by the beam splitting unit to form a second beam and a third beam. The second beam is transmitted to the first detection unit, and the third beam is transmitted to the second detection unit. The overlay error of the overlay marks on the substrate is obtained based on the signals detected by the first detection unit and the second detection unit.

[0017] Optionally, the first beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light.

[0018] Optionally, the second detection unit includes an imaging lens and an imaging camera. The third beam passes through the imaging lens and reaches the imaging camera. The imaging lens only images the positive first-order diffracted light.

[0019] Optionally, an imaging aperture stop is provided between the imaging lens and the beam splitting unit, the imaging aperture stop being used to block zero-order reflected light and negative first-order diffracted light.

[0020] Optionally, the beam splitting unit includes a first beam splitting prism and a second beam splitting prism, both of which are semi-transparent and semi-reflective mirrors.

[0021] Optionally, the first beam splitter is a semi-transparent and semi-reflective mirror, and the second beam splitter is divided into two parts: the first part is a semi-transparent and semi-reflective mirror used for semi-transmission and semi-reflection of the positive first-order diffracted light; the second part is a full lens used for full transmission of the zero-order reflected light and the negative first-order diffracted light.

[0022] Optionally, the first detection unit is an angular spectrum camera, which detects the diffraction spectrum of the diffracted light collected by the objective lens and transmitted through the single-light unit.

[0023] Optionally, the overlay markings on the substrate are μDBO.

[0024] Optionally, the illumination unit includes an illumination source and an illumination stop, the illumination stop having a central opening, the size of which is less than one-third of the numerical aperture of the objective lens.

[0025] Optionally, a first magnification scaling optical path is provided between the illumination unit and the beam splitting unit, a second magnification scaling optical path is provided between the beam splitting unit and the first detection unit, and a third magnification scaling optical path is provided between the beam splitting unit and the second detector.

[0026] Optionally, the device further includes a data processing unit for receiving signals detected by the first detection unit and signals detected by the second detection unit, and calculating the overlay error of the overlay marks on the substrate based on the signals detected by the first detection unit and the signals detected by the second detection unit.

[0027] Optionally, the second image formed by the second detection unit detecting the first-order diffracted light includes a first region, a second region, a third region, and a fourth region; the first image formed by the first detection unit detecting the diffraction spectrum includes a left region, a right region, an upper region, and a lower region; and the formula for calculating the overlay error of the overlay marks on the substrate is as follows:

[0028]

[0029] Where ε is the overlay error of the overlay mark on the substrate, Δ is the preset offset, and I 1x + I is the average light intensity in the first region. 1y + I represents the average light intensity within the second region. 2y + I is the average light intensity within the third region. 2x + The average light intensity in the fourth region is... The light intensity of the light spot in the left-side region is marked in the X direction. The right-hand region represents the light intensity marked in the X direction. The lower region represents the light intensity marked in the Y direction. The upper region is the light intensity marked in the Y direction.

[0030] Based on the same inventive concept, the present invention also provides a method for measuring the scattering of overlaid marks, comprising:

[0031] The illumination unit provides the measuring beam;

[0032] The measurement beam is transmitted to the substrate with overlay marks via a beam splitter and an objective lens, and is reflected by the substrate with overlay marks to form a first beam;

[0033] The first beam is split into a second beam and a third beam by a beam splitting unit. The second beam is transmitted to the first detection unit, and the third beam is transmitted to the second detection unit.

[0034] The overlay error of the overlay mark on the substrate is obtained based on the signals detected by the first detection unit and the second detection unit.

[0035] Optionally, the first beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light; the second image formed by the second detection unit detecting the positive first-order diffracted light includes a first region, a second region, a third region, and a fourth region; the first image formed by the first detection unit detecting the diffraction spectrum includes a left region, a right region, an upper region, and a lower region; and the overlay error of the overlay marks on the substrate is:

[0036]

[0037] Where ε is the overlay error of the overlay mark on the substrate, Δ is the preset offset, and I 1x + I is the average light intensity in the first region. 1y +I represents the average light intensity within the second region. 2y + I is the average light intensity within the third region. 2x + The average light intensity in the fourth region is... The light intensity of the light spot in the left-side region is marked in the X direction. The right-hand region represents the light intensity marked in the X direction. The lower region represents the light intensity marked in the Y direction. The upper region is the light intensity marked in the Y direction.

[0038] Based on the same inventive concept, the present invention also provides a lithography machine, including the apparatus for measuring the scattering of overlay marks as described in any one of the above claims.

[0039] Compared with existing technologies, the overlay mark scattering measurement device provided by this invention calculates the overlay error of the overlay mark on the substrate by detecting signals from the first and second detection units. Furthermore, the second detection unit detects a second image formed by the positive first-order diffracted light, while the first detection unit detects a first image containing the diffraction spectrum of the zeroth-order reflected light, the positive first-order diffracted light, and the negative first-order diffracted light. The overlay error of the overlay mark on the substrate can be calculated by simultaneously capturing two images of the pupil plane and the image plane. Through optimization of the scattering measurement calculation algorithm, it achieves a good match with traditional algorithms and obtains repeatability almost identical to traditional algorithms. In addition, the imaging aperture design in this invention is simple, eliminating the need to switch apertures on the measurement device to simultaneously acquire the required positive and negative first-order diffracted light information. No additional sensors are required, and the material and design costs are comparable to existing technologies, but the yield is superior to traditional overlay mark scattering measurement methods. This solves the problems of multiple aperture switching, long processing time, and low yield in existing technologies. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the optical path for overlay mark scattering measurement in existing technology;

[0041] Figure 2 This is a schematic diagram of the overlay mark scattering measurement device according to Embodiment 1 of the present invention;

[0042] Figure 3 This is a schematic diagram of light incident on a substrate and reflected and diffracted on a diffraction overlay measurement mark according to Embodiment 1 of the present invention;

[0043] Figure 4 This is a schematic diagram of an imaging camera according to Embodiment 1 of the present invention;

[0044] Figure 5 This is a schematic diagram of an angular spectrum camera image according to Embodiment 1 of the present invention;

[0045] Figure 6 This is a schematic diagram of the scattering measurement overlay measurement principle of Embodiment 1 of the present invention;

[0046] Figure 7 This is a diagram showing the matching results of the X-direction measurement configuration in Embodiment 1 of the present invention on a real machine;

[0047] Figure 8 This is a diagram showing the matching results of the Y-direction measurement configuration in Embodiment 1 of the present invention on a real machine;

[0048] Figure 9 This is a schematic diagram of the overlay mark scattering measurement device according to Embodiment 2 of the present invention;

[0049] Figure 10 This is a schematic diagram of the overlay mark scattering measurement device according to Embodiment 3 of the present invention;

[0050] In the picture,

[0051] 1-Illumination source; 2-Illumination aperture; 3-Substrate with overlay markings; 3a-First overlay markings; 3b-Intermediate layer; 3c-Second overlay markings; 4-Objective lens; 5-Beam splitting unit; 5a-First beam splitter prism; 5b-Second beam splitter prism; 5b1-First part of the second beam splitter prism; 5b2-Second part of the second beam splitter prism; 6-Imaging aperture stop; 7-Imaging lens; 8-Imaging camera; 9-Data processing unit; 10-First detection unit; 11a-First magnification scaling optical path; 11b-Second magnification scaling optical path; 11a-Third magnification scaling optical path. Detailed Implementation

[0052] The following detailed description, in conjunction with the accompanying drawings and specific embodiments, provides a further detailed account of the overlay mark scattering measurement method, apparatus, and lithography machine proposed in this invention. The advantages and features of this invention will become clearer from the following description and claims. It should be noted that the drawings are all in a very simplified form and use non-precise proportions, and are only used to facilitate and clarify the illustration of the embodiments of this invention.

[0053] Example 1

[0054] For details, please refer to Figure 2 A schematic diagram of the overlay mark scattering measurement device according to an embodiment of the present invention. Figure 2 As shown, this embodiment of the invention provides an apparatus for measuring the scattering of overlaid marks, comprising: an illumination unit, an objective lens 4, a beam splitting unit 5, a first detection unit 10, and a second detection unit; wherein,

[0055] The lighting unit is used to provide illumination;

[0056] The first detection unit 10 is located on the pupil plane of the objective lens 4, and the second detection unit is located on the image plane of the objective lens 4.

[0057] The beam-splitting unit 5 includes a first beam-splitting prism 5a and a second beam-splitting prism 5b;

[0058] The measurement beam provided by the illumination unit is transmitted to the substrate 3 with overlay marks via the first beam splitter 5a and the objective lens 4. After reflection and diffraction by the substrate 3 with overlay marks, a first beam is formed. The first beam is transmitted to the objective lens 4 and the first beam splitter 5a to the second beam splitter 5b. After being split by the second beam splitter 5b, a second beam and a third beam are formed. The second beam is transmitted to the first detection unit 10, and the third beam is transmitted to the second detection unit. The data processing unit calculates the overlay error of the overlay marks on the substrate based on the signals detected simultaneously by the first detection unit 10 and the second detection unit.

[0059] The illumination unit includes, for example, an illumination source 1 and an illumination stop 2. The illumination stop 2 has a central opening. In this embodiment, the size of the opening of the illumination stop 2 is, for example, less than one-third of the numerical aperture of the objective lens 4, to match the size of the subsequent optical path of the device for measuring the scattering of the overlay marks. The size of the opening of the illumination stop 2 can also be other values, and this embodiment does not limit this.

[0060] Furthermore, a first scaling optical path 11a is provided between the illumination aperture 2 of the illumination unit and the beam splitting unit 5 to scale the illumination of the illumination unit.

[0061] The beam splitting unit 5 is, for example, a beam splitting prism group, specifically including a first beam splitting prism 5a and a second beam splitting prism 5b. Both the first beam splitting prism 5a and the second beam splitting prism 5b can be semi-transparent and semi-reflective mirrors, that is, they can transmit light or reflect light.

[0062] The first detection unit 10 is, for example, an angular spectrum camera, which detects the diffraction spectrum of the diffracted light collected by the objective lens 4 and transmitted through the spectrometer unit 5. The first detection unit 10 is located on the pupil plane of the objective lens 4. On the detection plane of the first detection unit 10, the 0th order spot of the incident light and the higher order diffraction spectrum can be collected. The higher order diffraction spectrum includes a set of spectra representing the X direction and a set of spectra representing the Y direction, and the two sets of spectra are perpendicular to each other.

[0063] Furthermore, a second magnification scaling optical path 11b is provided between the beam splitting unit 5 and the first detection unit 10 for scaling the second beam.

[0064] In this embodiment, the second detection unit includes an imaging lens 7 and an imaging camera 8. The imaging lens 7 only images the positive first-order diffracted light. An imaging aperture stop 6 is provided between the imaging lens 7 and the second split prism 5b to block the zeroth-order reflected light and the negative first-order diffracted light.

[0065] Furthermore, a third magnification scaling optical path 11c is provided between the beam splitting unit 5 and the second detector for scaling the third beam.

[0066] In this embodiment, the device further includes a data processing unit 9, which is, for example, a PU (Processing Unit) for receiving a first signal detected by the first detection unit 10 and a second signal detected by the second detection unit, and calculating the overlay error of the overlay mark on the substrate based on the first signal and the second signal.

[0067] Please refer to Figure 2 and Figure 3 , Figure 3 This is a schematic diagram illustrating the reflection and diffraction of light incident on a substrate based on diffraction overlay measurement marks, according to an embodiment of the present invention. Light emitted from the illumination unit is reflected by the first beam splitter 5a to the objective lens 4, and then incident on the substrate 3 with overlay marks. After reflection and diffraction by the substrate 3 with overlay marks, a first beam is formed, such as... Figure 3 As shown, the first beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light, i.e., 0th-order reflected light and +1 / -1st-order diffracted light. The first beam is transmitted through the first beam splitter 5a to the second beam splitter 5b to form the second beam and the third beam. Specifically, the first beam is transmitted through the second beam splitter 5b to form the second beam, which contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The second beam is transmitted to the first detection unit 10 through the second magnification scaling optical path 11b, and the first detection unit 10 obtains an image containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The first beam is reflected by the second prism 5b to form a third beam. The third beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The third beam is transmitted to the imaging aperture stop 6 through the third magnification scaling optical path 11c. The imaging aperture stop 6 blocks light except for the positive first-order diffracted light. Therefore, only the positive first-order diffracted light in the third beam can be transmitted to the imaging lens 7, and then the imaging camera 8 can obtain an image containing the positive first-order diffracted light.

[0068] In this embodiment, the data processing unit 9 calculates the overlay error of the overlay mark on the substrate based on the signals simultaneously detected by the first detection unit and the second detection unit. The formula for calculating the overlay error of the overlay mark on the substrate is as follows:

[0069]

[0070] Where ε is the overlay error of the overlay mark, Δ is the preset offset, the second detection unit detects the second image formed by the positive first-order diffracted light, the second image includes a first region, a second region, a third region and a fourth region, and the average light intensity in the first region is I. 1x+ The average light intensity in the second region is I. 1y + The average light intensity in the third region is I. 2y + The average light intensity in the fourth region is I. 2x + ;

[0071] The first detection unit detects a first image of the diffraction spectrum. This first image includes a left region, a right region, an upper region, and a lower region. The light spot in the left region is an X-axis marked light intensity of... The right-hand region is marked with light intensity in the X direction. The lower region is marked with light intensity in the Y direction. The upper region is marked with light intensity in the Y direction.

[0072] Based on the same inventive concept, embodiments of the present invention also provide a method for measuring the scattering of overlaid marks, including:

[0073] The illumination unit provides the measuring beam;

[0074] The measurement beam is transmitted through the beam splitter and objective lens to the overlay mark on the substrate 3 with overlay mark, and forms the first beam after reflection and diffraction;

[0075] The first beam is split into a second beam and a third beam by the beam splitting unit 5. The second beam is transmitted to the first detection unit 10, and the third beam is transmitted to the second detection unit.

[0076] The overlay error of the overlay mark on the substrate is calculated based on the signals detected simultaneously by the first detection unit 10 and the second detection unit.

[0077] In this embodiment, the first beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light; the overlay marks are the first overlay mark 3a and the second overlay mark 3c.

[0078] The second detection unit detects the second image formed by the positive first-order diffracted light. The second image includes a first region, a second region, a third region, and a fourth region. The average light intensity in the first region is I. 1x + The average light intensity in the second region is I. 1y + The average light intensity in the third region is I. 2y + The average light intensity in the fourth region is I. 2x + ;

[0079] The first detection unit detects the first image of the diffraction spectrum. The first image includes four regions. The light spot in the left region is marked with an intensity of X-axis light. The right-hand region is marked with light intensity in the X direction. The lower region is marked with light intensity in the Y direction. The upper region is marked with light intensity in the Y direction.

[0080] The overlay error of the overlay marks on the substrate is

[0081]

[0082] Calculation of overprinting error of overprinting marks on substrate in X direction This is equal to the difference between the positive and negative first-order optical regions in the first detection unit. It can be obtained from the light intensity of the first region and the light intensity of the second region of the second detector;

[0083] The overlay error of the overlay mark on the substrate in the Y direction is calculated using the same method as that in the X direction;

[0084] Where ε is the overprinting error of the overprinting mark, and Δ is the preset offset.

[0085] Figure 4 This is a schematic diagram of an imaging camera according to an embodiment of the present invention. Figure 5 This is a schematic diagram of an angular spectrum camera image according to an embodiment of the present invention. The following is based on... Figure 4 and Figure 5 A detailed analysis of how formula (4) was obtained.

[0086] Please refer to Figure 4 The principle of calculating the overlay mark based on the image signal from imaging camera 8 is shown in Figure 4. The area within the dashed circle is the illumination field of view. The signal of the overlay mark is divided into four regions. Imaging camera 8 measures the image formed by the +1st order diffracted light, with XP in the upper left corner. 1+ It is the image of the marked area with a positive preset offset Δ in the X direction, and the average light intensity in the area is I. 1x + That is, I1 in the X direction + YP in the upper right corner 1+ It is the image of the marked area with a preset offset Δ in the Y direction that is positive, and the average light intensity in the area is I. 1y + That is, I1 in the Y direction + The YP2+ in the lower left corner is the image of the marked area with a negative preset offset Δ in the Y direction, and the average light intensity within the area is I. 2y + That is, I2 in the Y direction +; The XP2+ in the upper left corner is the image of the marked area where the preset offset Δ in the X direction is negative, and the average light intensity in the area is I 2x + , that is, I2 in the X direction + .

[0087] The image collected by the first detection unit 10 is as Figure 5 shown. The first detection unit 10 obtains an image containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The central area is the 0-order diffracted light, and the light spot in the left area is the The right area is the The lower area is the The upper area is the

[0088] Figure 6 is the schematic diagram of the scattering measurement overlay measurement principle of the first embodiment of the present invention. In this embodiment, the calculation method of this embodiment is introduced by taking the overlay mark in the X direction as an example. As Figure 6 shown, the substrate 3 has an overlay mark, which includes a first overlay mark 3a and a second overlay mark 3c. There is an intermediate layer 3b between the first overlay mark 3a and the second overlay mark 3c. The vertical distance between the two layers of the first overlay mark 3a and the second overlay mark 3c is T. The offset of the two-layer gratings of the first overlay mark 3a and the second overlay mark 3c is d. The complex amplitude of the diffracted light of the first overlay mark 3a is Ae ik α , and the complex amplitude of the diffracted light of the second overlay mark 3c is and is caused by the offset d of the two-layer overlay mark gratings. The pitch is the grating constant, and d << pitch. Considering the complex amplitude after the interference of the upper and lower two-layer overlay marks, the positive first-order diffracted light is, for example, The negative first-order diffracted light is, for example,

[0089] Converting the complex amplitude into light intensity and replacing the angle θ d with the offset, there will be the following relationship:

[0090]

[0091]

[0092]

[0093]

[0094] From formulas (4-1) to (4-4), we can find that:

[0095]

[0096]

[0097] According to thin-film interference theory, Let λ be the wavelength of light. Considering the periodicity of the sine function, let α - β ∈ (-π, π]. If α - β ≈ 0, then... They are very close and difficult to distinguish, so measurement processes often aim to prevent α-β from becoming small quantities. Considering that pitch is generally on the order of micrometers (μm), and ε and Δ are generally less than 20 nm, it can be assumed that:

[0098] and,

[0099] Therefore, I 1+ -I 2+ ≈-(I 1- -I 2- Substituting into formula (3), we can derive:

[0100] That is, formula (4).

[0101] in, This equals the pupil plane signal of the objective lens, i.e., the difference between the positive and negative first-order light regions of the image from the first detection unit. For the overlay calculation in the X direction, this is... Figure 5 The right-side light spot minus the left-side light spot. 1+ -I 2+ The overlay can be obtained from the light intensity of the XP1+ and XP2+ regions on the image plane of the imaging camera in the second detection unit. The overlay measurement in the Y direction is the same as that in the X direction. In the entire measurement process, the measurement of an overlay vector only requires taking two images, one on the pupil plane and one on the image plane, simultaneously to obtain the result.

[0102] Through optimization of this method, the yield will be significantly improved. Table 1 shows the expected single-point measurement time for the same sample using existing methods and the expected single-point measurement time for this embodiment. It can be seen that the single-point measurement time of the measurement method in this embodiment is significantly reduced compared to existing methods, thus improving measurement efficiency.

[0103] Table 1: Expected Single-Point Measurement Time Comparison between Existing Methods and This Embodiment

[0104]

[0105] The overlay marker scattering measurement method and device provided in this embodiment can be applied to DBO measurement and uDBO measurement by simultaneously acquiring diffraction signals from a single pupil plane and image plane, while shortening the measurement time and improving the measurement efficiency.

[0106] Simulations can be used to determine the imaging performance of imaging camera 8. The simulation considers only the X-direction markers, with a marker grating period of 800 nm, a preset offset of 10 nm, and an illumination mode of σ = 0.2 through-hole. The simulation yields images from the spectral camera and the imaging camera, displaying two light intensity signal regions containing overlay information. The calculated overlay matches the set overlay with a deviation of less than 0.1 nm, thus verifying the feasibility of this method.

[0107] Please refer to Figure 7 and Figure 8 , Figure 7 This is a diagram showing the matching results of the X-direction measurement configuration on a real machine according to Embodiment 1 of the present invention. Figure 8 This is a matching result diagram of the Y-direction measurement configuration on the actual machine according to Embodiment 1 of the present invention. This embodiment also verifies the correctness of formula (4) using DBO measured data. The verification employs a comparison of the matching results calculated using both the old and new methods for overlay calculation. Figure 7 and Figure 8 The measurement results, based on a grating constant (pitch) of 1µm and a wavelength of 550nm, were verified on a real machine. Figure 7 and Figure 8 As can be seen, the vertical axis represents the new method (i.e., the measurement method in this embodiment), and the horizontal axis represents the old method (i.e., existing technology). The overlay calculated by the new and old methods shows better linearity. The X-direction results show a slope of 0.997, an intercept of -0.061 nm, and a fitted R-squared value. 2 =0.9994, the mean of the residuals is 0.05nm. Y-direction results: slope 0.986, intercept -0.0047nm, fitted R0 2 =0.9998, and the mean of the residual is 0.019nm.

[0108] As shown in Table 2, for repeatability in the X and Y directions, the results of both the old and new methods are <0.04nm, which meets the preset requirements.

[0109] Table 2. Comparison of repeatability between existing methods and patented methods

[0110] X-axis repeatability (nm) Y-axis repeatability (nm) Existing methods 0.025 0.037 Method of this embodiment 0.026 0.023

[0111] Based on the same inventive concept, embodiments of the present invention also provide a lithography machine, including the above-described apparatus for measuring the scattering of overlay marks.

[0112]

Example 2

[0113] Figure 9 This is a schematic diagram of the overlay mark scattering measurement device according to Embodiment 2 of the present invention. Please refer to... Figure 9 This embodiment provides a marker scattering measurement device, which includes: an illumination unit, an objective lens 4, a beam splitting unit 5, a first detection unit 10, and a second detection unit; wherein,

[0114] The lighting unit is used to provide illumination;

[0115] The beam-splitting unit 5 includes a first beam-splitting prism 5a and a second beam-splitting prism 5b;

[0116] The illumination provided by the illumination unit is transmitted to the substrate 3 with overlay marks via the first beam splitter 5a and the objective lens 4. After diffraction by the substrate 3 with overlay marks, a first beam is formed. The first beam is transmitted to the second beam splitter 5b via the objective lens 4 and the first beam splitter 5a. After passing through the second beam splitter 5b, a second beam and a third beam are formed. The second beam is transmitted to the first detection unit 10, and the third beam is transmitted to the second detection unit. The overlay error of the overlay marks on the substrate is calculated based on the signals detected simultaneously by the first detection unit 10 and the second detection unit.

[0117] In this embodiment, the light emitted by the illumination source 1 is reflected by the illumination aperture 2 and the first beam splitter 5a to the objective lens 4, and then incident on the substrate 3 with overlay markings. The substrate 3 with overlay markings diffracts to form a first beam containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The first beam is transmitted through the first beam splitter 5a to the second beam splitter 5b to form a second beam and a third beam. The first beam is transmitted through the second beam splitter 5b to form a second beam containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The second beam is transmitted to the first detection unit 10 through the second magnification scaling optical path 11b. The first detection unit 10 obtains an image containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The first beam is reflected by the second prism 5b to form the third beam. The third beam contains zero-order reflected light, positive first-order diffracted light and negative first-order diffracted light. The third beam is transmitted to the imaging lens 7 through the third magnification scaling optical path 11c. The imaging lens 7 only images the positive first-order diffracted light, and then the imaging camera 8 obtains an image containing the positive first-order diffracted light.

[0118] The difference between this embodiment and Embodiment 1 is that the imaging lens 7 in this embodiment only images the positive first-order diffracted light and does not image the zeroth-order reflected light and the negative first-order diffracted light. Therefore, there is no need to set the imaging aperture stop 6. The imaging aperture stop 6 and the part of the third magnification scaling optical path 11c corresponding to the imaging aperture stop 6 are omitted in this embodiment, which reduces the optical structure and lowers the cost.

[0119] The overlay mark scattering measurement method and overlay calculation method in this embodiment are the same as those in Embodiment 1, and will not be repeated here.

[0120]

Example 3

[0121] Figure 10 This is a schematic diagram of the overlay mark scattering measurement device according to Embodiment 3 of the present invention. Please refer to... Figure 10 This embodiment provides a marker scattering measurement device, comprising: an illumination unit, an objective lens 4, a beam splitting unit 5, a first detection unit 10, and a second detection unit; wherein,

[0122] The lighting unit is used to provide illumination;

[0123] The beam-splitting unit 5 includes a first beam-splitting prism 5a and a second beam-splitting prism 5b;

[0124] The illumination provided by the illumination unit is transmitted to the substrate 3 with overlay marks via the first beam splitter 5a and the objective lens 4. After diffraction by the substrate 3 with overlay marks, a first beam is formed. The first beam is transmitted to the second beam splitter 5b via the objective lens 4 and the first beam splitter 5a. After passing through the second beam splitter 5b, a second beam and a third beam are formed. The second beam is transmitted to the first detection unit 10, and the third beam is transmitted to the second detection unit. The overlay error of the overlay marks on the substrate is calculated based on the signals detected simultaneously by the first detection unit 10 and the second detection unit.

[0125] The difference from Embodiment 1 is that in this embodiment, the first beam-splitting prism 5a is a semi-transparent, semi-reflective mirror, and the second beam-splitting prism 5b is divided into two parts: the first part 5b2 is a semi-transparent, semi-reflective mirror used for semi-transmission and semi-reflection of the positive first-order diffracted light; the second part 5b1 is a full lens used for full transmission of the zero-order reflected light and the negative first-order diffracted light. Therefore, in this embodiment, there is no need to set up an imaging aperture stop 6 and a portion of the third-magnification scaling optical path 11c corresponding to the imaging aperture stop 6, reducing the optical structure and lowering the cost.

[0126] In this embodiment, the light emitted by the illumination source 1 is reflected by the illumination aperture 2 and the first beam splitter 5a to the objective lens 4, and then incident on the substrate 3 with overlay markings. The substrate 3 with overlay markings diffracts to form a first beam containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The first beam is transmitted through the first beam splitter 5a to the second beam splitter 5b to form a second beam and a third beam. The first beam is transmitted through the second beam splitter 5b to form the second beam, which contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The second beam is transmitted to the first detection unit 10 through the second magnification scaling optical path 11b, and the first detection unit 10 obtains an image containing zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. The first beam is reflected by the second beam splitter 5b2 to form a third beam, which contains only positive first-order diffracted light. The third beam is transmitted to the imaging lens 7 through the third magnification scaling optical path 11c, and then the imaging camera 8 obtains an image containing positive first-order diffracted light.

[0127] The overlay mark scattering measurement method and overlay calculation method in this embodiment are the same as those in Embodiment 1, and will not be repeated here.

[0128] In summary, the overlay mark scattering measurement method, apparatus, and lithography machine provided in this invention utilize signals simultaneously detected by the first and second detection units. Furthermore, the second detection unit detects the image formed by the positive first-order diffracted light, while the first detection unit detects the image of the diffraction spectrum including zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light. By simultaneously capturing two images of the pupil plane and image plane, the overlay error of the substrate can be calculated. Through optimization of the scattering measurement calculation algorithm, it achieves excellent matching results compared to traditional algorithms and obtains repeatability almost identical to traditional algorithms. The aperture design in this invention is simple, eliminating the need to switch apertures on the measurement device to simultaneously acquire the required positive and negative first-order diffracted light information. No additional sensors are required, and the material and design costs are comparable to existing technologies, but the yield is superior to traditional overlay mark scattering measurement methods. This solves the problems of multiple aperture switching, long processing time, and low yield in existing technologies.

[0129] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to mutually. In addition, different parts between embodiments can also be combined with each other, and this invention does not limit this.

[0130] The above description is merely a description of preferred embodiments of the present invention and is not intended to limit the scope of the present invention in any way. Any changes or modifications made by those skilled in the art based on the above disclosure shall fall within the protection scope of the claims.

Claims

1. A device for measuring the scattering of overlaid marks, characterized in that, include: Illumination unit, objective lens, beam splitting unit, first detection unit, and second detection unit; among which, The illumination unit is used to provide a measuring beam; The first detection unit is located on the pupil plane of the objective lens, and the second detection unit is located on the image plane of the objective lens. The second detection unit includes an imaging lens, which images only positive first-order diffracted light. The measurement beam provided by the illumination unit is transmitted to the substrate with overlay marks via the beam splitting unit and the objective lens, and is reflected by the substrate with overlay marks to form a first beam. The first beam is transmitted to the objective lens and the beam splitting unit, and is split by the beam splitting unit to form a second beam and a third beam. The second beam is transmitted to the first detection unit, and the third beam is transmitted to the second detection unit. The overlay error of the overlay marks on the substrate is calculated based on the signals detected simultaneously by the first detection unit and the second detection unit. The beam splitting unit includes a first beam splitting prism and a second beam splitting prism. The first beam splitting prism is a semi-transparent and semi-reflective mirror. The second beam splitting prism includes a first part and a second part. The first part is a semi-transparent and semi-reflective mirror used for semi-transmission and semi-reflection of the positive first-order diffracted light. The second part is a full lens used for full transmission of the zero-order reflected light and the negative first-order diffracted light.

2. The apparatus for measuring overlay-marked scattering as described in claim 1, characterized in that, The first beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light.

3. The apparatus for measuring overlaid mark scattering as described in claim 2, characterized in that, The second detection unit also includes an imaging camera, and the third beam reaches the imaging camera after passing through the imaging lens.

4. The apparatus for measuring overlay-marked scattering as described in claim 3, characterized in that, An imaging aperture stop is provided between the imaging lens and the beam splitting unit. The imaging aperture stop is used to block the zero-order reflected light and the negative first-order diffracted light.

5. The apparatus for measuring overlay mark scattering as described in any one of claims 1 to 4, characterized in that, The first detection unit is an angular spectrum camera, which detects the diffraction spectrum of the diffracted light collected by the objective lens and transmitted through the spectrometer.

6. The apparatus for measuring overlay mark scattering as described in any one of claims 1 to 4, characterized in that, A first magnification scaling optical path is provided between the illumination unit and the beam splitting unit, a second magnification scaling optical path is provided between the beam splitting unit and the first detection unit, and a third magnification scaling optical path is provided between the beam splitting unit and the second detection unit.

7. The apparatus for measuring overlay mark scattering as described in any one of claims 1 to 4, characterized in that, The device further includes a data processing unit for receiving signals detected by the first detection unit and signals detected by the second detection unit, and calculating the overlay error of the overlay marks on the substrate based on the signals detected by the first detection unit and the signals detected by the second detection unit.

8. The apparatus for measuring overlay-marked scattering as described in claim 2, characterized in that, The second image formed by the second detection unit detecting the first-order diffracted light includes a first region, a second region, a third region, and a fourth region. The first image formed by the first detection unit detecting the diffraction spectrum includes a left region, a right region, an upper region, and a lower region. The formula for calculating the overlay error of the overlay marks on the substrate is as follows: Where ε is the overlay error of the overlay mark on the substrate, Δ is the preset offset, and I 1x + I is the average light intensity in the first region. 1y + I represents the average light intensity within the second region. 2y + I is the average light intensity within the third region. 2x + The average light intensity within the fourth region is... The light intensity of the light spot in the left-side region is marked in the X direction. The area on the right represents the light intensity marked in the X direction. The lower region represents the light intensity marked in the Y direction. The upper region is the light intensity marked in the Y direction.

9. A method for measuring the scattering of overlaid marks, characterized in that, include: The illumination unit provides the measuring beam; The measurement beam is transmitted to the substrate with overlay marks via a beam splitter and an objective lens, and is reflected by the substrate with overlay marks to form a first beam; The first beam is split into a second beam and a third beam by a beam splitting unit. The second beam is transmitted to a first detection unit, and the third beam is transmitted to a second detection unit. The overlay error of the overlay mark on the substrate is calculated based on the signals detected simultaneously by the first detection unit and the second detection unit. The imaging lens in the second detection unit images only the positive first-order diffracted light; the beam splitting unit includes a first beam splitting prism and a second beam splitting prism, the first beam splitting prism being a semi-transparent and semi-reflective mirror; the second beam splitting prism includes a first part and a second part, the first part being a semi-transparent and semi-reflective mirror used for semi-transmission and semi-reflection of the positive first-order diffracted light, and the second part being a full lens used for full transmission of the zeroth-order reflected light and the negative first-order diffracted light.

10. The overlay mark scattering measurement method as described in claim 9, characterized in that, The first beam contains zero-order reflected light, positive first-order diffracted light, and negative first-order diffracted light; The second image formed by the second detection unit detecting the positive first-order diffracted light includes a first region, a second region, a third region, and a fourth region. The first image formed by the first detection unit detecting the diffraction spectrum includes a left region, a right region, an upper region, and a lower region. The overlay error of the overlay marks on the substrate is: Where ε is the overlay error of the overlay mark on the substrate, Δ is the preset offset, and I 1x + I is the average light intensity in the first region. 1y + I represents the average light intensity within the second region. 2y + I is the average light intensity within the third region. 2x + The average light intensity within the fourth region is... The light intensity of the light spot in the left-side region is marked in the X direction. The area on the right represents the light intensity marked in the X direction. The lower region represents the light intensity marked in the Y direction. The upper region is the light intensity marked in the Y direction.

11. A lithography machine, characterized in that, The apparatus includes the overlay mark scattering measurement device as described in any one of claims 1 to 8.

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