Diffractive-based overlay mark measurement apparatus, method and measurement system

Abstract

Provided are a diffraction-based overlay mark measurement device, method and measurement system. The device comprises a light source, an illumination module, a workpiece table and a detection module. The illumination module comprises an illumination optical fiber and an illumination unit. The illumination optical fiber is used to guide the light source into the illumination unit. The illumination unit is used to generate an incident light beam. The workpiece table is used to carry and move a wafer. The wafer has an overlay mark formed thereon. The incident light beam is incident on the overlay mark to diffract. The detection module comprises at least four detection units. Each detection unit is used to detect positive and negative order diffraction light in a first direction and a second direction. Each detection unit comprises a converging mirror, an adaptive adjustment mechanism, a detection optical fiber and a detector array. The adaptive adjustment mechanism is used to move the converging mirror and the detection optical fiber. The adaptive adjustment mechanism is used to adaptively adjust the converging mirror and the detection optical fiber to collect diffraction light at different angles according to different types of overlay marks. The detector array is used to detect diffraction light at different angles. Diffraction light in a large angle range is collected. Process adaptability is improved.

Description

Technical Field

[0001] This application relates to the field of semiconductor technology, and in particular to a diffraction-based overlay marking measurement device, method and measurement system. Background Technology

[0002] In high-precision overlay mark measurement technology, the overlay marks are small with large diffraction angles, generally requiring large numerical aperture (NA) objectives for diffraction light collection. However, the numerical aperture of the detector unit's objective is large (e.g., greater than 0.9), which places extremely high demands on the overlay mark measurement optical path, and the polarization aberration of the large numerical aperture objective can severely affect the measurement results. Specifically, a detector branch with a fixed collection angle can only be used under specific process conditions, exhibiting poor process adaptability. Furthermore, in high-precision overlay mark measurement, the size of a single measurement field of view is limited, affecting equipment yield. In addition, the same overlay mark requires multiple illumination modes for measurement to improve accuracy, and the constant switching between multiple illumination modes inevitably impacts equipment yield. Summary of the Invention

[0003] The purpose of this application is to provide a diffraction-based overlay marking measurement device, system and method to solve the problems of polarization aberration affecting measurement results and poor process adaptability of large numerical aperture objectives.

[0004] To address the aforementioned technical problems, this application provides a diffraction-based overlay marking measurement device, comprising:

[0005] The system includes a light source, an illumination module, a workpiece stage, and a detection module, among which:

[0006] The light source is used to provide light beams of different wavelengths;

[0007] The lighting module includes an illumination fiber and an illumination unit. The illumination fiber is used to guide the light source into the illumination unit, and the illumination unit is used to generate an incident light beam.

[0008] The workpiece stage is used to support the wafer and drive the wafer to move. Overlay marks are formed on the wafer. The incident light beam is incident on the overlay marks and diffracts.

[0009] The detection module includes at least four detection units for detecting positive and negative order diffracted light in the first and second directions, respectively. Each detection unit includes a converging mirror, an adaptive adjustment mechanism, a detection fiber, and a detector array. The adaptive adjustment mechanism drives the converging mirror and the detection fiber to move and adaptively adjusts according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at the different angles.

[0010] Optionally, the detection module further includes a polarization beam splitter located between the detection fiber and the detector array. The polarization beam splitter splits the diffracted light at different angles into diffracted light with different polarization states and different wavelengths. The detector array synchronously detects the diffracted light signals with different polarization states and different wavelengths.

[0011] Optionally, after the adaptive adjustment mechanism performs adaptive adjustment according to different types of overlay marks, it also adjusts the detection position based on the feedback of the diffraction signal intensity detected by the detector array.

[0012] Optionally, the adaptive adjustment mechanism is a five-dimensional electric adjustment mechanism capable of translation and rotation, wherein the five dimensions are x, y, z, Rx, and Ry.

[0013] Optionally, the adaptive adjustment mechanism is a six-dimensional electric adjustment mechanism capable of translation and rotation.

[0014] Optionally, the polarization beam splitter includes a birefringent prism and a diffraction beam splitter. The diffracted light is split into different polarization states by the birefringent prism and then enters the diffraction beam splitter to be split into diffracted light of different polarization states and different wavelengths.

[0015] Optionally, the polarization beam splitter includes a metalens, through which the diffracted light is simultaneously split in wavelength and polarization to form diffracted light of different polarization states and wavelengths.

[0016] Optionally, the metalens is used to simultaneously modulate the amplitude, phase, polarization, and frequency of the diffracted light.

[0017] Optionally, the detector array may include APD, PD, PMT or CMOS.

[0018] Optionally, the illumination unit includes a polarization switching component and an illumination pupil aperture switching component.

[0019] Optionally, the first direction is the X direction and the second direction is the Y direction.

[0020] Optionally, among the at least four detection units, the first detection unit is used to receive effective positive order diffraction light in the X direction, the second detection unit is used to receive effective negative order diffraction light in the X direction, the third detection unit is used to receive effective positive order diffraction light in the Y direction, and the fourth detection unit is used to receive effective negative order diffraction light in the Y direction.

[0021] Optionally, the effective positive order diffraction light includes the positive first order diffraction light and other effective positive order diffraction light, and the effective negative order diffraction light includes the negative first order diffraction light and other effective negative order diffraction light.

[0022] Optionally, the wavelength of the light source can be from 200nm to 1700nm.

[0023] Optionally, the adaptive adjustment mechanism can drive the converging mirror and the probe fiber to collect diffracted light at an angle ranging from 5° to 85°.

[0024] Optionally, the illumination unit and the detection unit are non-coaxial.

[0025] Based on the same inventive concept, this application also provides a diffraction-based overlay mark measurement method, employing the diffraction-based overlay mark measurement device as described in any of the preceding claims, comprising:

[0026] The light source provides beams of light at different wavelengths;

[0027] An optical fiber guides the light source into an illumination unit, which generates an incident beam and directs the incident beam onto the overlay mark to cause diffraction.

[0028] The detection module has at least four detection units that detect positive and negative order diffracted light in the X and Y directions, respectively. In each detection unit, an adaptive adjustment mechanism drives the converging mirror and the detection fiber to move, and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at the different angles.

[0029] Optionally, the method further includes a polarization beam splitter located between the probe fiber and the detector array to split the diffracted light at different angles into diffracted light with different polarization states and different wavelengths, and the detector array synchronously detects the diffracted light signals with different polarization states and different wavelengths.

[0030] Optionally, after the detector array synchronously detects diffracted light signals of different polarization states and different wavelengths, the intensity of the diffracted light signal of each detection channel of each detector array is analyzed to realize the synchronous detection of multiple overlay mark measurement signals under different polarization states and different wavelengths, and the overlay deviation is calculated based on the intensity of positive and negative order diffracted signals.

[0031] Optionally, the method further includes the adaptive adjustment mechanism adjusting the detection position based on the intensity of the diffraction signal detected by the detector array after adaptive adjustment according to different types of overlay marks.

[0032] Based on the same inventive concept, this application also provides a diffraction-based overlay mark measurement method, employing the diffraction-based overlay mark measurement device as described in any of the preceding claims, comprising:

[0033] S1: The workpiece stage moves the wafer to a position directly below the illumination unit, and the wafer has at least one overlay mark;

[0034] S2: The light source provides light beams of different wavelengths, and the illumination fiber guides the light source into the illumination unit. The illumination unit generates an incident light beam, which is incident on the overlay mark and diffracts.

[0035] S3: At least four detection units in the detection module detect positive and negative order diffracted light in the first and second directions respectively. The adaptive adjustment mechanism in each detection unit drives the converging mirror and the detection fiber to move, and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at the different angles and calculates the measurement results of a single overlay mark.

[0036] S4: Determine whether all overlay marks have been measured. If all overlay marks have not been measured, the workpiece stage moves to the next overlay mark area and repeats S2-S3 until all overlay marks have been measured.

[0037] S5: Output all overlay mark measurement results.

[0038] Based on the same inventive concept, this application also provides a diffraction-based overlay mark measurement system, including a plurality of diffraction-based overlay mark measurement devices as described in any of the above claims, each of the diffraction-based overlay mark measurement devices being fixed on a multi-axis motion mechanism for free movement.

[0039] In the diffraction-based overlay mark measurement device provided in this application, a light source is used to provide light beams of different wavelengths; the illumination module includes an illumination fiber and an illumination unit, the illumination fiber being used to guide the light source into the illumination unit, and the illumination unit being used to generate the incident light beam; a workpiece stage is used to support a wafer on which overlay marks are formed, and the incident light beam is incident on the overlay marks and diffracts; the detection module includes at least four detection units for detecting positive and negative order diffracted light in a first direction and a second direction, respectively. Each detection unit includes a converging mirror, an adaptive adjustment mechanism, a detection fiber, and a detector array. The adaptive adjustment mechanism drives the converging mirror and the detection fiber to move, and adaptively adjusts according to different types of overlay marks to collect diffracted light at different angles. The detector array detects diffracted light at different angles. This application, through the converging mirror, adaptive adjustment mechanism, and detection fiber, can flexibly adjust according to the characteristics of the overlay mark being measured, achieving diffracted light collection over a wide angle range, improving measurement accuracy and process adaptability. The use of a polarization beam splitter component to simultaneously measure diffracted light of different polarization states and wavelengths improves yield. By employing a non-coaxial scheme for the illumination and detection units, different orders of diffracted light are collected. Multiple converging mirrors and detection fibers achieve the detection effect of a single large numerical aperture objective lens, avoiding polarization aberration problems and crosstalk between different orders of diffracted light, thus reducing the complexity of optical path design. Multiple marking measurement devices, each equipped with a multi-axis motion mechanism, further enhance yield and process adaptability. Attached Figure Description

[0040] Those skilled in the art will understand that the accompanying drawings are provided to better understand this application and do not constitute any limitation on the scope of this application. Wherein:

[0041] Figure 1 This is a schematic diagram of a diffraction-based overlay marking measurement device according to an embodiment of this application;

[0042] Figure 2 This is a schematic diagram of the distribution of diffraction branches measured by overlay marks according to an embodiment of this application;

[0043] Figure 3 This is a schematic diagram of another diffraction-based overlay marking measurement device according to an embodiment of this application;

[0044] Figure 4 This is a flowchart of a diffraction-based overlay mark measurement method according to an embodiment of this application;

[0045] Figure 5 This is a schematic diagram of a diffraction-based overlay marking measurement system according to an embodiment of this application.

[0046] In the attached image:

[0047] 101-Light source; 102-Illumination fiber; 103-Polarization switching component; 104-Illumination pupil aperture switching component; 105-Illumination unit; 106-+1 or other effective positive order diffracted light; 107-First converging mirror; 108-First adaptive adjustment mechanism; 109-First detection fiber; 110-First birefringent prism; 111-First diffraction beam splitter; 112-First detector array; 113--1 or other effective negative order diffracted light; 114-Second converging mirror; 115-Second adaptive adjustment mechanism; 116-Second detection fiber; 117-Second birefringent prism; 118-Second diffraction beam splitter; 119-Second detector array; 120-Overlay mark; 121-Workpiece stage;

[0048] 201 - X-direction +1 or other effective positive order diffraction light detection unit; 202 - X-direction -1 or other effective negative order diffraction light detection unit; 203 - Y-direction +1 or other effective positive order diffraction light detection unit; 204 - Y-direction -1 or other effective negative order diffraction light detection unit; 205 - 0th order diffraction light;

[0049] 301 - First metalens; 302 - Second metalens;

[0050] 501 - Mechanical frame; 502 - First fixed bracket; 503 - Second fixed bracket; 504 - (n-1)th fixed bracket;

[0051] 505 - First set of marking measuring devices; 506 - Second set of marking measuring devices; 507 - Third set of marking measuring devices; 508 - Fourth set of marking measuring devices; 509 - (n-1)th set of marking measuring devices; 510 - nth set of marking measuring devices; 511 - First multi-axis motion mechanism; 512 - Second multi-axis motion mechanism; 513 - Third multi-axis motion mechanism; 514 - Fourth multi-axis motion mechanism; 515 - (n-1)th multi-axis motion mechanism; 516 - nth multi-axis motion mechanism. Detailed Implementation

[0052] To make the objectives, advantages, and features of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and specific embodiments. It should be noted that the drawings are all in a very simplified form and are not drawn to scale, used only to facilitate and clarify the illustration of the embodiments of this application. Furthermore, the structures shown in the drawings are often part of the actual structures. In particular, different figures may emphasize different aspects and sometimes use different scales.

[0053] As used in this application, the singular forms “a,” “an,” and “the” include plural objects; the term “or” is generally used to mean “and / or”; the term “a number” is generally used to mean “at least one”; and the term “at least two” is generally used to mean “two or more”. Furthermore, the terms “first,” “second,” and “third” are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as “first,” “second,” or “third” may explicitly or implicitly include one or at least two of that feature. Additionally, as used in this application, the phrase “an element disposed on another element” generally only indicates a connection, coupling, mating, or transmission relationship between the two elements, and this connection, coupling, mating, or transmission can be direct or indirect through an intermediate element. It should not be construed as indicating or implying a spatial positional relationship between the two elements, i.e., one element can be located arbitrarily inside, outside, above, below, or to one side of the other element, unless otherwise explicitly stated. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0054] Figure 1 This is a schematic diagram of a diffraction-based overlay marking measurement device according to an embodiment of this application. Figure 1 As shown, this embodiment provides a diffraction-based overlay marking measurement device, which includes four parts: a light source, an illumination module, a workpiece stage, and a detection module.

[0055] Light source 101 is used to provide light beams of different wavelengths. Specifically, light source 101 is a broadband illumination source that can cover 200nm to 1700nm, and can be optionally configured with illumination wavelengths such as deep ultraviolet, near ultraviolet, visible light, near infrared, and short-wave infrared.

[0056] The illumination module includes an illumination fiber 102 and an illumination unit 105. The illumination fiber 102 guides the light source 101 into the illumination unit 105, which in turn generates the incident beam. The illumination unit 105 may include a polarization switching component 103 and an illumination pupil aperture switching component 104 to adapt to different types of overlay marks. The polarization switching component 103 enables switching between different polarization modes, such as P-polarization (parallel polarization), S-polarization (vertical polarization), and C-polarization (circular polarization). The illumination pupil aperture switching component 104 enables switching between different illumination NAs and illumination pupil shapes. During application, by traversing the illumination modes, measurement accuracy and process adaptability can be improved.

[0057] The workpiece stage 121 is used to support the wafer and drive the wafer to move. Overlay marks 120 are formed on the wafer. The incident light beam is incident on the overlay marks 120 after passing through the illumination module and diffracts.

[0058] The detection module includes at least four detection units for detecting positive and negative order diffracted light in a first direction and a second direction, respectively. Preferably, the first direction is the X direction and the second direction is the Y direction. Figure 1 Only two detection units are shown in the X-direction, detecting the +1 or other effective positive order diffracted light and the -1 or other effective negative order diffracted light in the X-direction, respectively. Each detection unit includes a converging mirror, an adaptive adjustment mechanism, a probe fiber, and a detector array. The adaptive adjustment mechanism moves the converging mirror and probe fiber together, and adaptively adjusts according to different types of overlay marks to collect diffracted light at different angles. The detector array detects diffracted light at different angles. The converging mirror can collect light at certain angles, including but not limited to ±5°, ±7°, ±10°, etc. The angle range for collecting diffracted light by the adaptive adjustment mechanism is from 5° to 85°.

[0059] Preferably, the detection module further includes a polarization beam splitter, located between the detection fiber and the detector array. Diffracted light at different angles is split into diffracted light with different polarization states and different wavelengths by the polarization beam splitter, that is, diffracted light with different polarization states and multiple wavelengths. The detector array synchronously detects diffracted light signals with different polarization states and different wavelengths.

[0060] Preferably, after the adaptive adjustment mechanism performs adaptive adjustment according to different types of overlay marks, it also adjusts the detection position according to the intensity feedback of the diffraction signal detected by the detector array.

[0061] The adaptive adjustment mechanism includes, but is not limited to, five-dimensional or six-dimensional electrically operated adjustment mechanisms with translation and rotation functions, capable of automatically identifying the optimal detection position based on the intensity of the diffraction signal detected by the detector array. Specifically, the adjustment directions of the five-dimensional electrically operated adjustment mechanism are x, y, z, Rx, and Ry, and the adjustment directions of the six-dimensional electrically operated adjustment mechanism are x, y, z, Rx, Ry, and Rz. The detector array includes, but is not limited to, avalanche photodiodes (APDs), photodiodes (PDs), photomultiplier tubes (PMTs), and CMOS image sensors (Complementary Metal-Oxide-Semiconductor Image Sensors).

[0062] In this embodiment, the polarization beam splitting component includes a birefringent prism and a diffraction beam splitting element. The birefringent prism is used to split the diffracted light into diffracted light with different polarization states, and the diffraction beam splitting element is used to split the diffracted light with different polarization states into diffracted light with multiple wavelengths, that is, diffracted light with different wavelengths.

[0063] Figure 2 This is a schematic diagram illustrating the measurement of diffraction branch distribution using overlay marks, according to an embodiment of this application. (In conjunction with...) Figure 1 and Figure 2 The detection module includes a first detection branch and a second detection branch. The first detection branch receives effective positive-order diffraction light, which includes first-order positive diffraction light and other effective positive-order diffraction light. The second detection branch receives effective negative-order diffraction light, which includes first-order negative diffraction light and other effective negative-order diffraction light. The diffraction light of the overlay mark is generally divided into X-direction diffraction light and Y-direction diffraction light, which are used to measure the overlay deviation of the object under test in the X and Y directions, respectively. Therefore, the detection module of this embodiment includes four detection units: X-direction +1 or other effective positive-order diffraction light detection unit 201, X-direction -1 or other effective negative-order diffraction light detection unit 202, Y-direction +1 or other effective positive-order diffraction light detection unit 203, and Y-direction -1 or other effective negative-order diffraction light detection unit 204. In other words, the first detection branch includes an X-axis +1 or other effective positive order diffraction light detection unit 201 and a Y-axis +1 or other effective positive order diffraction light detection unit 203. The second detection branch includes an X-axis -1 or other effective negative order diffraction light detection unit 202 and a Y-axis -1 or other effective negative order diffraction light detection unit 204. Among them, the +1st order diffraction light or other effective positive order diffraction light in the X direction is collected by the X-direction +1 or other effective positive order diffraction light detection unit 201, the -1st order diffraction light or other effective negative order diffraction light in the X direction is collected by the X-direction -1 or other effective negative order diffraction light detection unit 202, the +1st order diffraction light or other effective positive order diffraction light in the Y direction is collected by the Y-direction +1 or other effective positive order diffraction light detection unit 203, the -1st order diffraction light or other effective negative order diffraction light in the Y direction is collected by the Y-direction -1 or other effective negative order diffraction light detection unit 204, and the 0th order diffraction light 205 is generally not involved in the measurement or used as a reference light for the detection light intensity.

[0064] This embodiment also provides a diffraction-based overlay mark measurement method, employing the diffraction-based overlay mark measurement device as described in any of the above embodiments, including:

[0065] The light source provides beams of light at different wavelengths;

[0066] The illumination fiber guides the light source into the illumination unit, which generates an incident beam and directs the incident beam onto the overlay mark to cause diffraction.

[0067] The detection module has at least four detection units that detect positive and negative order diffracted light in the first and second directions, respectively. In each detection unit, the adaptive adjustment mechanism drives the converging mirror and the detection fiber to move, and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles. The detector array detects diffracted light at different angles.

[0068] Preferably, the method further includes a polarization beam splitter located between the probe fiber and the detector array to split diffracted light at different angles into diffracted light with different polarization states and different wavelengths, and the detector array synchronously detects diffracted light signals with different polarization states and different wavelengths.

[0069] Specifically, the light source 101 emits light beams of different wavelengths, which are guided through the illumination fiber 102 into the illumination unit 105 to generate incident light beams. The illumination unit 105 includes a polarization switching component 103 and an illumination pupil aperture switching component 104, both configured to adapt to different types of overlay marks. The incident light beam is incident directly onto the overlay mark 120 placed on the workpiece stage 121. The incident light beam undergoes diffraction after passing through the overlay mark 120, wherein the +1 or other effective positive order diffracted light 106 passes through the first converging mirror 107 and is focused onto the first detection fiber 109. The first adaptive adjustment mechanism 108 drives the first converging mirror 107 and the first detection fiber 109 to move together, adaptively adjusting according to the test object of different process types to collect diffracted light at different angles. The diffracted light is split into two different polarization states, such as P-polarization and S-polarization, by the first birefringent prism 110. It then enters the first diffraction beam splitter 111, which further splits the light into diffracted light of different polarization states and wavelengths, i.e., multiple detection channels, such as six or more detection beams, which are ultimately collected by the first detector array 112. The -1 or other effective negative order diffracted light 113 passes through the second converging mirror 114 and the second adaptive adjustment mechanism 115, which drives the second converging mirror 114 to focus the diffracted light onto the second detection fiber 116, collecting diffracted light at different angles. This light then passes through the second birefringent prism 117 and the second diffraction beam splitter 118, which further splits the diffracted light at different angles into diffracted light of different polarization states and wavelengths, such as six or more detection beams, which are ultimately collected by the second detector array 119. By analyzing the signal intensity of each detection channel in the first detector array 112 and the second detector array 119, it is possible to simultaneously detect multiple overlay mark measurement signals under different polarization states and wavelengths. Based on a multi-wavelength correction algorithm, the measurement error of the overlay marks can be reduced. Multi-wavelength correction algorithms, for example, measure at least 5 to 6 wavelengths, with each wavelength corresponding to a measurement result of an overlay mark, and obtain the average value of the overlay mark measurement results of multiple wavelengths to approach the ideal overlay mark measurement value, thereby improving the overlay mark measurement accuracy.

[0070] Figure 3 This is a schematic diagram of another diffraction-based overlay marking measurement device according to an embodiment of this application. In this embodiment, the polarization beam splitting component includes a metalens. Specifically, Figure 1 The diffraction-based overlay marking measurement device achieves simultaneous detection of different polarization states and wavelengths through a birefringent prism and a diffraction beam splitter. However, the diffraction beam splitter has low splitting efficiency, which results in the loss of energy of the effective detection signal, affecting measurement accuracy. Furthermore, its complex structure increases the difficulty and space requirements of optomechanical design. Figure 3 Another diffraction-based overlay marking measurement device is provided to expand the multi-channel measurement function of the detection branch and improve measurement accuracy. Specifically, a metalens is used to simultaneously achieve wavelength and polarization separation. The metalens is designed and fabricated using subwavelength nanostructures to simultaneously control the optical field of physical quantities such as amplitude, phase, polarization, and frequency of light. Utilizing the small-size structure of the metalens, complex beam splitting functions can be achieved with a single element, resulting in high beam splitting efficiency and a smaller spatial size.

[0071] In detail, the +1 or other effective positive order diffracted light signal collected by the first detection fiber 109 passes through the first metalens 301, where the broadband signal is split into diffracted light signals with different polarization states and wavelengths, such as six or more detection beams with different polarization states and wavelengths. The detection diffracted light after passing through the first metalens 301 is independently detected by the first detector array 112 to obtain the detection light intensity. The -1 or other effective negative order diffracted light signal collected by the second detection fiber 116 passes through the second metalens 302, where the broadband signal is split into multiple diffracted light signals with different polarization states and wavelengths, such as six or more detection beams with different polarization states and wavelengths. The detection diffracted light after passing through the second metalens 302 is independently detected by the second detector array 119 to obtain the detection light intensity. Through the light intensity signal of each corresponding detection channel, the measurement results of multiple overlay marks under different polarization states and wavelengths can be calculated simultaneously. Based on the multi-wavelength correction algorithm, the function of reducing the measurement error of the overlay marks can be realized.

[0072] Figure 4 This is a flowchart of a diffraction-based overlay mark measurement method according to an embodiment of this application. Figure 4 As shown, the measurement method includes:

[0073] S1: The workpiece stage moves the wafer to directly below the illumination unit, and the wafer has at least one overlay mark;

[0074] S2: The light source provides beams of different wavelengths. The illumination fiber guides the light source into the illumination unit. The illumination unit generates an incident beam. The incident beam is incident on the overlay mark and diffracts.

[0075] S3: At least four detection units in the detection module detect positive and negative order diffracted light in the first and second directions respectively. The adaptive adjustment mechanism in each detection unit drives the converging mirror and the detection fiber to move, and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at the different angles and calculates the measurement results of a single overlay mark.

[0076] S4: Determine whether all overlay marks have been measured. If not all overlay marks have been measured, move the workpiece stage to the next overlay mark area and repeat S2-S3 until all overlay marks have been measured.

[0077] S5: Output all overlay mark measurement results.

[0078] It is worth noting that the illumination unit includes a polarization switching component and an illumination pupil aperture switching component. In step S2, different illumination modes are switched to illuminate the overlay marks. In step S3, the method for selecting the adaptive receiving angle based on the type of overlay mark is as follows: first, overlay marks of different process types are automatically scanned, and the angle with the strongest signal is obtained as the adaptive receiving angle of the adaptive adjustment mechanism. The method for calculating the measurement result of a single overlay mark employs a multi-wavelength correction algorithm. Specifically, for example, at least 5-6 wavelengths are measured, each wavelength corresponding to one overlay mark measurement result, and the average value of the overlay mark measurement results across multiple wavelengths is obtained to approximate the ideal overlay mark measurement value, thereby improving the overlay mark measurement accuracy.

[0079] Figure 5 This is a schematic diagram of a diffraction-based overlay marking measurement system according to an embodiment of this application, as shown below. Figure 5As shown, the measurement system includes multiple diffraction-based overlay mark measuring devices; each diffraction-based overlay mark measuring device is fixed on a multi-axis motion mechanism for free movement. Some diffraction-based overlay mark measuring devices have a detection unit including a birefringent prism and a diffraction beam splitter, while others have a detection unit including a metalens. Specifically, the diffraction-based overlay mark measuring system includes a mechanical frame 501 and a first fixed support 502, a second fixed support 503, and an (n-1)th fixed support 504 fixed to the mechanical frame 501. Each fixed support has two multi-axis motion mechanisms, and each multi-axis motion mechanism has one diffraction-based overlay mark measuring device. For example, the first fixed bracket 502 is equipped with a first multi-axis motion mechanism 511 and a second multi-axis motion mechanism 512. The first multi-axis motion mechanism 511 is equipped with a first set of marking measuring devices 505, and the second multi-axis motion mechanism 512 is equipped with a second set of marking measuring devices 506. The second fixed bracket 503 is equipped with a third multi-axis motion mechanism 513 and a fourth multi-axis motion mechanism 514. The third multi-axis motion mechanism 513 is equipped with a third set of marking measuring devices 507, and the fourth multi-axis motion mechanism 514 is equipped with a fourth set of marking measuring devices 508. The (n-1)th fixed bracket 504 is equipped with an (n-1)th multi-axis motion mechanism 515 and an nth multi-axis motion mechanism 516. The (n-1)th multi-axis motion mechanism 515 is equipped with an (n-1)th set of marking measuring devices 509, and the nth multi-axis motion mechanism 516 is equipped with an nth set of marking measuring devices 510. The diffraction-based overlay mark measurement system can simultaneously measure multiple overlay marks on a wafer. By setting up multiple overlay mark measurement devices, each equipped with a multi-axis motion mechanism, the yield and process adaptability can be further improved.

[0080] In this application, the structure of the diffraction-based overlay marking measurement system includes, but is not limited to, the following: Figure 5 As shown, the layout can be flexibly adjusted according to the different positions of the overprinted marks.

[0081] In this embodiment, the single-set marking measurement device uses one illumination unit and at least four detection units to perform marking measurement. The illumination unit generates a high-power broadband illumination source, and the at least four detection units detect ±1st order diffraction light or other effective order diffraction light in the X and Y directions of the marking, respectively. Simultaneously, by adding multiple marking measurement devices, two or more devices can perform simultaneous measurements, resulting in a significant increase in yield. Multiple marking measurement devices can use a single light source assembly to achieve switching between polarization and illumination modes. Furthermore, the illumination unit of the multiple marking measurement devices can be configured with illumination wavelengths such as deep ultraviolet, near ultraviolet, visible light, near infrared, and short-wave infrared, and can be configured with polarized imaging or non-polarized imaging modes. The detection unit can use a polarization beam splitter to achieve multi-spot measurement, with each spot employing a different filtering or polarization configuration. Combined with an energy detector array, synchronous measurement under different polarization states and wavelength configurations is achieved.

[0082] like Figure 1 and Figure 3 As shown, the illumination unit and the detection unit are non-coaxial. This embodiment achieves the collection of diffracted light of different orders through a non-coaxial scheme for the illumination and detection units. Multiple converging mirrors and detection fibers achieve the detection effect of a single large numerical aperture objective lens, avoiding polarization aberration problems and crosstalk between diffracted light of different orders, thus reducing the difficulty of optical path design. Through the converging mirror, adaptive adjustment mechanism, and detection fiber, adjustments can be made flexibly according to the characteristics of the object under test, achieving diffracted light collection over a wide angle range, improving measurement accuracy and process adaptability. Using birefringent prisms and diffraction beam splitters or metalenses simultaneously achieves measurements of different wavelengths and polarizations, improving yield. Furthermore, multiple sets of marking measurement devices, each equipped with a multi-axis motion mechanism, further enhance yield and process adaptability.

[0083] In summary, in the diffraction-based overlay mark measurement device provided in this application embodiment, the light source is used to provide light beams of different wavelengths; the illumination module includes an illumination fiber and an illumination unit, the illumination fiber is used to guide the light source into the illumination unit, and the illumination unit is used to generate the incident light beam; the workpiece stage is used to support the wafer and drive the wafer to move, overlay marks are formed on the wafer, and the incident light beam is incident on the overlay marks and diffracts; the detection module includes at least four detection units, used to detect the positive and negative order diffracted light in the first and second directions respectively, wherein each detection unit includes a converging mirror, an adaptive adjustment mechanism, a detection fiber, and a detector array, the adaptive adjustment mechanism drives the converging mirror and the detection fiber to move, and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles, and the detector array detects diffracted light at different angles. This application achieves the collection of diffracted light of different orders through a non-coaxial scheme of the illumination unit and the detection unit, and multiple converging mirrors and detection fibers achieve the detection effect of a single large numerical aperture objective lens, which can avoid polarization aberration problems, and at the same time avoid crosstalk between diffracted light of different orders, reducing the difficulty of optical path design. Furthermore, by employing a converging mirror, adaptive adjustment mechanism, and probe fiber, the system can be flexibly adjusted according to the characteristics of the measured object, achieving wide-angle diffraction light collection and improving measurement accuracy and process adaptability. Simultaneous measurement of different polarization states and wavelengths is achieved using birefringent prisms, diffraction beam splitters, or metalenses, increasing yield. In addition, multiple marking measurement devices, each equipped with a multi-axis motion mechanism, further enhance yield and process adaptability.

[0084] 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, the different parts between embodiments can also be combined with each other, and this application does not limit this.

[0085] Furthermore, it should be understood that although preferred embodiments have been disclosed above, these embodiments are not intended to limit this application. For any person skilled in the art, many possible variations and modifications can be made to the technical solutions of this application based on the disclosed technical content, or equivalent embodiments can be modified accordingly, without departing from the scope of the technical solutions of this application. Therefore, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of this application, without departing from the content of the technical solutions of this application, shall still fall within the scope of protection of the technical solutions of this application.

Claims

1. A diffraction-based overlay marking measurement device, characterized in that, It includes a light source, an illumination module, a workpiece stage, and a detection module, among which: The light source is used to provide light beams of different wavelengths; The lighting module includes an illumination fiber and an illumination unit. The illumination fiber is used to guide the light source into the illumination unit, and the illumination unit is used to generate an incident light beam. The workpiece stage is used to support the wafer and drive the wafer to move. Overlay marks are formed on the wafer. The incident light beam is incident on the overlay marks and diffracts. The detection module includes at least four detection units for detecting positive and negative order diffracted light in a first direction and a second direction, respectively. Each detection unit includes a converging mirror, an adaptive adjustment mechanism, a detection fiber, and a detector array. The adaptive adjustment mechanism drives the converging mirror and the detection fiber to move and adaptively adjusts according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at different angles, and the adaptive adjustment mechanism adjusts the detection position based on the intensity of the diffraction signal detected by the detector array.

2. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The detection module further includes a polarization beam splitter located between the detection fiber and the detector array. The polarization beam splitter splits the diffracted light at different angles into diffracted light with different polarization states and different wavelengths. The detector array synchronously detects diffracted light signals with different polarization states and different wavelengths.

3. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The adaptive adjustment mechanism is a five-dimensional electric adjustment mechanism capable of translation and rotation, wherein the five dimensions are x, y, z, Rx, and Ry.

4. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The adaptive adjustment mechanism is a six-dimensional electric adjustment mechanism capable of translation and rotation.

5. The diffraction-based overlay marking measurement device according to claim 2, characterized in that, The polarization beam splitter includes a birefringent prism and a diffraction beam splitter. The diffracted light is split into different polarization states by the birefringent prism and then enters the diffraction beam splitter to be split into diffracted light of different polarization states and different wavelengths.

6. The diffraction-based overlay marking measurement device according to claim 2, characterized in that, The polarization beam splitter includes a metalens, through which the diffracted light is simultaneously split in wavelength and polarization to form diffracted light of different polarization states and wavelengths.

7. The diffraction-based overlay marking measurement device according to claim 6, characterized in that, The meta-lens is used to simultaneously modulate the amplitude, phase, polarization, and frequency of the diffracted light.

8. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The detector array includes APD, PD, PMT or CMOS.

9. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The illumination unit includes a polarization switching component and an illumination pupil aperture switching component.

10. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The first direction is the X direction, and the second direction is the Y direction.

11. The diffraction-based overlay marking measurement device according to claim 10, characterized in that, Of the at least four detection units, the first detection unit is used to receive effective positive order diffraction light in the X direction, the second detection unit is used to receive effective negative order diffraction light in the X direction, the third detection unit is used to receive effective positive order diffraction light in the Y direction, and the fourth detection unit is used to receive effective negative order diffraction light in the Y direction.

12. The diffraction-based overlay marking measurement device according to claim 11, characterized in that, The effective positive order diffraction light includes the positive first order diffraction light and other effective positive order diffraction light besides the positive first order diffraction light, and the effective negative order diffraction light includes the negative first order diffraction light and other effective negative order diffraction light besides the negative first order diffraction light.

13. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The wavelength of the light source is from 200nm to 1700nm.

14. The diffraction-based overlay marking measurement device according to claim 1, characterized in that, The adaptive adjustment mechanism drives the converging mirror and the probe fiber to collect diffracted light at an angle ranging from 5° to 85°.

15. The diffraction-based overlay marking measuring device according to claim 1, characterized in that, The illumination unit and the detection unit are not coaxial.

16. A method for measuring overlay marks based on diffraction, characterized in that, The diffraction-based overlay marking measurement device as described in any one of claims 1 to 15 includes: The light source provides beams of light at different wavelengths; An optical fiber guides the light source into an illumination unit, which generates an incident beam and directs the incident beam onto the overlay mark to cause diffraction. The detection module has at least four detection units that detect positive and negative order diffracted light in the first and second directions, respectively. In each detection unit, an adaptive adjustment mechanism drives the converging mirror and the detection fiber to move and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at the different angles.

17. The diffraction-based overlay mark measurement method according to claim 16, characterized in that, The method further includes a polarization beam splitter located between the detection fiber and the detector array to split the diffracted light at different angles into diffracted light with different polarization states and different wavelengths, and the detector array synchronously detects the diffracted light signals with different polarization states and different wavelengths.

18. The diffraction-based overlay mark measurement method according to claim 17, characterized in that, After the detector array synchronously detects diffracted light signals of different polarization states and wavelengths, the intensity of the diffracted light signal of each detection channel of each detector array is analyzed to realize the synchronous detection of multiple overlay mark measurement signals of different polarization states and wavelengths, and the overlay deviation is calculated based on the intensity of positive and negative order diffracted signals.

19. The diffraction-based overlay mark measurement method according to claim 18, characterized in that, The method further includes the adaptive adjustment mechanism making adaptive adjustments based on different types of overlay marks, and then adjusting the detection position based on feedback from the intensity of the diffraction signal detected by the detector array.

20. A method for measuring overlay marks based on diffraction, characterized in that, The diffraction-based overlay marking measurement device as described in any one of claims 1 to 15 includes: S1: The workpiece stage moves the wafer to a position directly below the illumination unit, and the wafer has at least one overlay mark; S2: The light source provides light beams of different wavelengths, and the illumination fiber guides the light source into the illumination unit. The illumination unit generates an incident light beam, which is incident on the overlay mark and diffracts. S3: At least four detection units in the detection module detect positive and negative order diffracted light in the first and second directions respectively. The adaptive adjustment mechanism in each detection unit drives the converging mirror and the detection fiber to move, and performs adaptive adjustment according to different types of overlay marks to collect diffracted light at different angles. The detector array detects the diffracted light at the different angles and calculates the measurement results of a single overlay mark. S4: Determine whether all overlay marks have been measured. If all overlay marks have not been measured, the workpiece stage moves to the next overlay mark area and repeats S2-S3 until all overlay marks have been measured. S5: Output all overlay mark measurement results.

21. A diffraction-based overlay marking measurement system, characterized in that, It includes multiple diffraction-based overlay marking measurement devices as described in any one of claims 1 to 15, each of the diffraction-based overlay marking measurement devices being fixed on a multi-axis motion mechanism for free movement.

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