TWI745933B - Wave aberration measuring device, measuring method and photoetching machine - Google Patents

Abstract

The present invention provides a wave aberration measuring device, a measuring method and a lithography machine. The wave aberration measuring device includes: an illumination system, which is set to generate an illumination light beam; On the cover table, a plurality of object surface small holes are arranged on the object surface small hole plate, and each object surface small hole contains g object surface small hole marks with different grating directions, and g is a positive integer greater than or equal to 2. A plurality of object surface small hole marks on the small hole plate are arranged in an array; the object surface small hole marks in the same array row have the same grating direction; along the array row direction, two adjacent object surface small hole marks in the same array row The distance between is h1; along the array row direction, the smallest distance between two small hole marks on the object surface in two array rows with the same grating direction is h2, h1=m×h2, m is greater than or equal to 2 A positive integer; any two rows of small hole marks on the object surface with the same grating direction are arranged in an array.

Description

Wave aberration measuring device, measuring method and photoetching machine

The present invention relates to lithography technology, for example, to a wave aberration measuring device, a measuring method and a lithography machine.

One goal of the semiconductor industry is to integrate more electronic components in a single integrated circuit (IC). To achieve this goal, it is necessary to continuously reduce the component size, that is, to continuously improve the resolution of the lithography projection system. The wave aberration of the objective lens is an important factor that limits the resolution of the projection system, and is also an important cause of linewidth changes. Although the objective lens has undergone strict inspection and optimization during the manufacturing and assembly processes to minimize the objective wave aberration, it is still necessary to perform on-line wave aberration measurement after the objective lens system is integrated into the lithography machine. This is because the aging of the lens material or the thermal effect of the objective lens will cause wave aberration. Therefore, it is necessary to frequently measure the wave aberration during the working process of the lithography machine, and adjust the position of the specific lens in the objective lens according to the measurement result to reduce the wave aberration. If the thermal effect of the objective lens needs to be corrected within a short time range, the wave aberration measurement needs to be performed more frequently. At this time, the immediacy of the wave aberration measurement is particularly important.

One method of measuring wave aberration online is phase-shifting shearing interferometry. This method uses an illuminating beam for measurement, uses a small hole on the object surface to generate a detection light source, and the small hole is imaged by the objective lens to the image surface shearing grating and produces shearing interference fringes in the far field. A two-dimensional array of photosensitive elements is used in the objective lens. The conjugate surface of the pupil records the interference image. In the measurement process, the relative position (phase shift) of the light source and the grating needs to be changed to obtain interference fringes under different phase shift conditions, and the wave aberration of the objective lens can be obtained by analyzing these interference images. In order to reconstruct the complete wavefront information, it is necessary to measure the phase information in two mutually perpendicular directions at each point of view at the same time. It can also measure the phase information in multiple directions, such as measuring the three directions with an angle of 120 degrees each other. Phase information. At the same time, in order to obtain the wave aberration information in the entire field of view of the objective lens, it is necessary to measure the selected field points one by one. In this way, the time taken to measure wave aberration for the entire field of view using this method is proportional to the following factors: 1. The number of field points Nf; 2. The number of measurement directions (at least 2) Nd; 3. Each direction If the number of phase shifting steps is Np, the theoretical measurement time Ttheory is proportional to Nf×Nd×Np. In order to ensure a certain measurement accuracy, the measurement quantity of each item mentioned above must be kept above a certain lower limit. The previous phase-shift shearing method used a serial measurement method to measure wave aberration, that is, measure each field of view point in turn, and measure the two directions of the field of view point in turn when measuring each field of view point. The phase shift operation is carried out in sequence during the direction. Therefore, the actual measurement time Tmeasure>=theoretical measurement time Ttheory. Since the time of wave aberration measurement cannot be further shortened, this serial measurement method will affect the productivity of the lithography machine and the instantaneity of wave aberration measurement.

In the related art, the phase-shifting shearing method is used to serially measure the wave aberration of each field of view point, which cannot meet the immediate requirements of the lithography device for the wave aberration measurement, and the detection efficiency is low. And when the wave aberration detection is performed on a projection objective with a large numerical aperture, signal crosstalk is prone to occur.

The embodiment of the present invention provides a wave aberration measuring device, a measuring method and lithography Machine to improve detection efficiency and avoid signal crosstalk.

The present invention provides a wave aberration measuring device, which includes:

The lighting system is set to generate an illuminating beam;

The object surface aperture plate is located on the light-emitting side of the aforementioned illumination system and is fixed on the mask stage. The object surface aperture plate is provided with a plurality of object surface apertures, and each of the aforementioned object surface apertures contains g different grating directions. The small hole mark on the object surface, g is a positive integer greater than or equal to 2, and the plurality of small hole marks on the object surface are arranged in an array on the small orifice plate of the object surface;

The aforementioned object-surface small hole marks in the same array row have the same grating direction; along the array row direction, the distance between two adjacent object-surface small hole marks in the same array row is h1; along the aforementioned array row direction, the grating The minimum distance between the two aforementioned small hole marks on the object surface in two array rows with the same direction is h2, h1=m×h2, where m is a positive integer greater than or equal to 2; any two rows with the same grating direction. Array arrangement of small hole marks on the object surface;

The projection objective lens is located on the side of the small orifice plate on the object surface away from the illumination system;

The image cutting grating plate is located on the side of the aforementioned projection objective lens away from the aforementioned small orifice plate of the object plane, and is fixed on the workpiece table;

A two-dimensional array photosensitive element and a data processing unit, the aforementioned two-dimensional array photosensitive element is located on the conjugate plane of the pupil of the aforementioned projection objective lens, and the aforementioned two-dimensional array photosensitive element is used to receive the shear formed on the aforementioned two-dimensional array photosensitive element The interference pattern, the data processing unit is used to calculate the wave aberration of the projection objective lens according to the shear interference pattern.

Optionally, the aforesaid object surface small holes include object surface small hole marks in the first grating direction And a small hole mark on the object surface in the second grating direction, the first grating direction is perpendicular to the second grating direction;

In the same aforementioned object surface small hole, the object surface small hole mark in the first grating direction and the object surface small hole mark in the second grating direction are arrayed at intervals of m-1; or,

In the same object surface small holes, the object surface small hole marks in the first grating direction and the object surface small hole marks in the second grating direction are sequentially arranged along the array column direction.

Optionally, the aforementioned first grating direction is parallel to the aforementioned array row direction; or, the angle between the aforementioned first grating direction and the aforementioned array row direction is 45°.

Optionally, a plurality of image-cutting gratings are arranged on the aforementioned image-cutting grating plate, each of the aforementioned image-cutting gratings includes g image-cutting grating marks of different grating directions, and the aforementioned image-cutting gratings A plurality of the aforementioned image-cutting grating mark arrays on the board are arranged; the aforementioned image-cutting grating marks in the same array row have the same grating direction; the same object surface hole has g different grating directions on the object surface. The hole marks correspond one-to-one with g image-cutting grating marks of different grating directions in the same image-cutting grating, and the grating direction of the corresponding small hole marks on the object surface is perpendicular to the grating direction of the image-cutting grating mark. .

Optionally, the number of the aforementioned image-cut raster marks in an array row is greater than or equal to the number of the aforementioned object-surface small hole marks in an array row.

Optionally, the aforementioned image-cutting grating plate includes a checkered grating array, and the aforementioned checkered grating array includes a plurality of light-transmitting cells and a plurality of non-light-transmitting cells; along the row direction of the aforementioned checker-shaped grating array And in the column direction, the light-transmitting unit cells and the non-light-transmitting unit cells are arranged at intervals.

Optionally, the row direction of the aforementioned checkered grating array is the same as the aforementioned small hole mark on the object surface. The angle between the row directions of the array is 45°.

Optionally, the numerical aperture of the aforementioned projection objective lens is greater than or equal to 0.85.

The present invention provides a lithography machine comprising the aforementioned wave aberration measuring device.

The present invention provides a wave aberration measuring method, which is executed by the aforementioned wave aberration measuring device, and the aforementioned method includes:

The illumination beam generated by the illumination system scans and illuminates the object surface small hole mark array of the object surface small hole plate by line to form a measurement beam. The aforementioned measurement beam passes through the projection objective lens and irradiates the image shearing grating plate to form a shearing interference pattern;

The two-dimensional array photosensitive element receives the aforementioned shearing interference pattern row by row and sends it to the data processing unit; the aforementioned data processing unit calculates the wave aberration of the aforementioned projection objective lens according to the aforementioned shearing interference pattern;

Wherein, along the array row direction, the illumination beam generated by the aforementioned illumination system irradiates and reads two small hole marks on the object surface with at least one field of view point.

Optionally, the illumination beam generated by the aforementioned illumination system scans and illuminates the object surface small aperture mark array of the object surface small aperture plate to form a measurement beam. Cut interference pattern; contains:

The illumination beam generated by the aforementioned illumination system irradiates an array of the object surface small hole marks on the object surface small hole mark array of the object surface small hole plate to form a measurement beam. The surface small hole marks correspond one-to-one and the image surface shearing grating marks perpendicular to the aforementioned object surface small hole mark grating direction of the array row to form a shearing interference pattern;

Move at least one of the following devices so that the aforementioned illumination beam scans the aforementioned small hole marks on the object surface in all array rows: the mask stage and the workpiece stage;

Wherein, the aforementioned image-cutting grating plate is provided with a plurality of image-cutting gratings, each of the aforementioned image-cutting gratings includes g image-cutting grating marks of different grating directions, and the aforementioned image-cutting grating plate The plurality of aforementioned image-cutting grating marks are arranged in an array; the aforementioned image-cutting grating marks in the same array row have the same grating direction; g object-face hole marks with different grating directions in the same object-face hole There is a one-to-one correspondence with g image-cutting grating marks of different grating directions in the same image-cutting grating, and the grating direction of the small hole mark of the corresponding object plane is perpendicular to the grating direction of the image-cutting grating mark.

Optionally, the illumination beam generated by the aforementioned illumination system scans and illuminates the object surface small aperture mark array of the object surface small aperture plate to form a measurement beam. Cut interference pattern; contains:

The illumination beam generated by the aforementioned illumination system irradiates an array of the object surface small hole marks on the object surface small hole mark array of the object surface small hole plate to form a measurement beam. Form a shear interference pattern;

Move at least one of the following devices so that the aforementioned illumination beam scans the aforementioned small hole marks on the object surface in all array rows: the mask stage and the workpiece stage;

Wherein, the aforementioned checkerboard grating array includes a plurality of light-transmitting unit cells and a plurality of non-light-transmitting unit cells; along the row direction and column direction of the aforementioned checkerboard grating array, the aforementioned light-transmitting unit cells and the aforementioned non-light-transmitting unit cells All are arranged at intervals.

The embodiment of the present invention provides a wave aberration measuring device, the object surface small hole plate of the wave aberration measuring device is provided with an array of object surface small hole marks, and the illumination light emitted by the illumination system The beam scanning illuminates a row of small hole marks on the object surface, thereby improving the detection efficiency. If a small hole mark on the object surface is set at each field of view point, when performing wave aberration detection for a projection objective with a large numerical aperture, the light spot formed by the illumination beam of the adjacent field of view point on the two-dimensional array photosensitive element is easy to produce Overlap, causing signal crosstalk. In the embodiment of the present invention, there are m-1 field points of view between two adjacent small hole marks on the object plane in the same array row, so as to avoid signal crosstalk during wave aberration detection for a projection objective with a large numerical aperture.

10: Lighting system

20: Mask stage

30: Small orifice plate on the surface

31: Small holes on the surface

40: Projection objective

41: Projection objective pupil

50: Workpiece table

60: Image cut grating plate

61: Image cut raster

70: Two-dimensional array photosensitive element

80: data processing unit

310: Small hole mark on the object surface

601: non-transparent cell

602: Translucent cell

610: Image cut raster mark

Fig. 1 is a schematic structural diagram of a wave aberration measuring device provided by an embodiment of the present invention.

[Figure 2] is a schematic diagram of a small orifice plate on an object surface provided by an embodiment of the present invention.

[Fig. 3] is a schematic diagram of another small orifice plate provided by an embodiment of the present invention.

[Fig. 4] is a schematic diagram of an image cutting grating plate provided by an embodiment of the present invention.

[Figure 5] is a schematic diagram of another small orifice plate provided by an embodiment of the present invention.

[Fig. 6] is a schematic diagram of another image shearing grating plate provided by an embodiment of the present invention.

[Fig. 7] is a schematic diagram of another image shearing grating plate provided by an embodiment of the present invention.

[Fig. 8] is a flowchart of a method for measuring wave aberration according to an embodiment of the present invention.

[Fig. 9] is a schematic diagram of another small orifice plate provided by an embodiment of the present invention.

The present invention will be further described in detail below with reference to the drawings and embodiments. FIG. 1 is a schematic structural diagram of a wave aberration measuring device provided by an embodiment of the present invention, and FIG. 2 is a schematic diagram of the present invention A schematic diagram of a small orifice plate on an object surface provided by the embodiment. Referring to FIGS. 1 and 2, the wave aberration measuring device includes an illumination system 10, a mask stage 20, an object surface orifice plate 30, a projection objective lens 40, and a workpiece stage 50. , Image cutting grating plate 60, two-dimensional array photosensitive element 70 and data processing unit 80. The illumination system 10 generates an illumination beam. The small aperture plate 30 on the object surface is located on the light emitting side of the lighting system 10 and is fixed on the mask stage 20. A plurality of object surface small holes 31 are provided on the object surface small hole plate 30, each object surface small hole 31 contains g object surface small hole marks 310 with different grating directions, g is a positive integer greater than or equal to 2, and the object surface A plurality of small hole marks 310 on the object surface are arranged in an array on the small hole plate 30. The row direction of the array formed by a plurality of object surface small hole marks 310 is parallel to the X direction, and the array column direction formed by a plurality of object surface small hole marks 310 is parallel to the Y direction. The small hole marks 310 on the object surface in the same array row have the same grating direction. Along the array row direction, the distance between two adjacent object surface small hole marks 310 in the same array row is h1; along the array row direction, the two closest object surface small hole marks 310 in the two array rows with the same grating direction The minimum distance between them is h2, h1=m×h2, and m is a positive integer greater than or equal to 2. Any two rows of small hole marks 310 on the object surface with the same grating direction are arranged in an array. Optionally, any two rows of small hole marks 310 on the object surface with the same grating direction are arranged in a staggered manner.

Exemplarily, referring to FIG. 2, g=2, m=2, an object surface small hole 31 includes two object surface small hole marks 310 with different grating directions. The grating directions of the object hole marks in the first array row and the object hole marks in the second array row are all along the X direction, and the object hole marks in the third array row and the objects in the fourth array row are The grating directions of the face hole marks are all along the Y direction. The object surface small hole marks in the first array row and the object surface small hole marks in the second array row are arranged in an array. The object surface small hole marks in the third array row and the object surface small hole marks in the fourth array row are arranged in an array. Object surface small hole mark O1U1 and object surface small hole mark O1V1 form an object surface small hole 31, object surface small hole The mark O5U1 and the small hole mark O5V1 on the object surface constitute another small hole 31 on the object surface. The distance along the X direction of the object surface hole mark O1U1 and the object surface hole mark O3U1 in the first array row is h1, the object surface hole mark O1U1 in the first array row and the object surface hole mark O1U1 in the second array row The distance of the hole mark O2U2 along the X direction is h2, h1=2×h2.

Referring to FIG. 1, the projection objective lens 40 is located on the side of the small aperture plate 30 of the object plane away from the illumination system 10. The image shearing grating plate 60 is located on the side of the projection objective lens 40 away from the small orifice plate 30 of the object surface, and is fixed on the workpiece table 50. The two-dimensional array photosensitive element 70 is located on the conjugate plane of the pupil 41 of the projection objective 40, and the two-dimensional array photosensitive element 70 is used to receive the shearing interference pattern formed on the two-dimensional array photosensitive element 70. The shearing interference pattern is illuminated by the illumination The light beam is formed after passing through the small aperture plate 30 on the object surface, the projection objective lens 40 and the image shearing grating plate 60. The data processing unit 80 is used to calculate the wave aberration of the projection objective lens 40 according to the shear interference pattern.

The object-plane orifice plate 30 is located below the illumination system 10 and on the object surface of the projection objective lens 40. The object-plane orifice plate 30 is connected to the mask stage 20 and can move together with the mask stage 20. The object surface aperture plate 30 receives the illumination light beam from the illumination system 10, generates an ideal point light source through the object surface aperture 31, and the measurement light beam emitted by the ideal point light source enters the projection objective lens 40. The measurement beam carrying the wave aberration information of the projection objective lens pupil 41 is condensed by the projection objective lens 40 to the image shearing grating plate 60. The image plane shearing grating plate 60 is located on the image plane of the projection objective lens 40, is connected to the workpiece table 50, and can move together with the workpiece table 50. The converged measuring beam passes through the image shearing grating plate 60 to form a shearing interference pattern, which is detected by the two-dimensional array photosensitive element 70 in the far field. Through the aforementioned measurement process, the interference patterns in different directions and different phase shift positions are measured at each field of view point, and transmitted to the data processing unit 80, and the wave aberration information of the projection objective pupil 41 is obtained through calculation processing. In the specific embodiment, by changing the aperture plate 30 on the object surface and the image shear grating plate 60 The relative position is phase-shifted, that is, by moving the mask stage 20 or the workpiece stage 50, or moving the mask stage 20 and the workpiece stage 50 at the same time, changing the orifice plate 30 connected to the moving mask stage 20 and the workpiece stage The image plane connected to 50 cuts the relative position of the grating plate 60. Since the two-dimensional array photosensitive element 70 is located on the far-field detection surface of the image shearing grating plate 60, that is, the Fraunhofer diffraction approximate area, the detection surface of the two-dimensional array photosensitive element 70 and the image shearing grating plate 60 are between It is the Fourier transform relationship. In this way, the change in the position of the measurement mark on the image shearing grating plate 60 is equivalent to the change in the phase of the received light beam on the two-dimensional array photosensitive element 70.

The embodiment of the present invention provides a wave aberration measuring device. The object surface small hole plate 30 of the wave aberration measuring device is provided with object surface small hole marks 310 arranged in an array, and the illumination beam emitted by the illumination system 10 scans and illuminates a row of objects. The face hole is marked 310, thereby improving the detection efficiency. If an object hole mark 310 is set at each field of view point, when the wave aberration detection is performed on the projection objective lens 40 with a large numerical aperture, the illumination beams of the adjacent field of view points are formed on the two-dimensional array photosensitive element 70. The light spots are prone to overlap and cause signal crosstalk. In the embodiment of the present invention, there are m-1 field points of view between two adjacent small hole marks 310 on the object surface in the same array row to avoid signal crosstalk during wave aberration detection for a projection objective with a large numerical aperture. The aforementioned field of view point is a virtual observation point on the small aperture plate of the object surface. For example, an object surface aperture mark 310 can be arranged at the position of each field of view point, so that the illumination beam irradiates the small object surface at the field of view point. The holes are marked to form an image of the detection spot. It is also possible not to arrange small hole marks on the object surface at some points of the field of view.

Referring to FIG. 2, the object surface aperture 31 includes an object surface aperture mark 310 in the first grating direction and an object surface aperture mark 310 in the second grating direction. The first grating direction is perpendicular to the second grating direction. In the same object surface small hole 31, the object surface small hole mark 310 in the first grating direction and the object surface small hole mark 310 in the second grating direction are spaced m-1 array rows. In other embodiments, the first The grating direction and the second grating direction may have an included angle greater than 0° and less than 90°, which is not limited in the embodiment of the present invention. In the embodiment of the present invention, setting the first grating direction to be perpendicular to the second grating direction can reduce the later calculation complexity, thereby reducing the difficulty of measurement.

Exemplarily, referring to Fig. 2, the object surface hole mark O1U1 is located in the first row (the row in the present invention refers to the row of the array, and the column in the present invention refers to the column of the array), and the object surface hole mark O1U1 It has a first grating direction, the object surface small hole mark O1V1 is located in the third row, the object surface small hole mark O1V1 has a second grating direction, the object surface small hole mark O1U1 and the object surface small hole mark O1V1 belong to the same object surface small hole 31, And the small hole mark O1U1 on the object surface and the small hole mark O1V1 on the object surface are separated by an array row.

FIG. 3 is a schematic diagram of another object surface small hole plate provided by an embodiment of the present invention. Referring to FIG. 3, the object surface small hole 31 includes the object surface small hole mark 310 in the first grating direction and the object surface small hole in the second grating direction. Mark 310, the first grating direction is perpendicular to the second grating direction. The first grating direction and the second grating direction may not be set perpendicularly, but correspondingly, the later calculation complexity will be increased. In the same object surface small holes 31, the object surface small hole marks 310 in the first grating direction and the object surface small hole marks 310 in the second grating direction are sequentially arranged along the array column direction.

Exemplarily, referring to Fig. 3, the object surface small hole mark O1U1 is located in the first row, the object surface small hole mark O1U1 has the first grating direction, the object surface small hole mark O1V1 is located in the second row, and the object surface small hole mark O1V1 has the first row. In the two grating directions, the object surface small hole mark O1U1 and the object surface small hole mark O1V1 belong to the same object surface small hole 31, and the object surface small hole mark O1U1 and the object surface small hole mark O1V1 are sequentially arranged along the Y direction. The object surface small hole mark O1U1 and the object surface small hole mark O1V1 are not separated from the object surface small hole mark 310 in the second grating direction.

Optionally, referring to FIGS. 2 and 3, the first grating direction is parallel to the X direction, The second grating direction is parallel to the Y direction. The first grating direction is parallel to the array row direction, and the second grating direction is parallel to the array column direction. In other embodiments, the angle between the first grating direction and the array row direction may also be 45°.

FIG. 4 is a schematic diagram of an image shearing grating plate provided by an embodiment of the present invention. Referring to FIG. 2, FIG. 3 and FIG. 4, the image shearing grating plate 60 is provided with a plurality of image shearing gratings 61, each The image cutting grating 61 includes g image cutting grating marks 610 in different grating directions, and a plurality of image cutting grating marks 610 on the image cutting grating plate 60 are arranged in an array. The array row direction of the object surface small hole marks 310 on the object surface small hole plate 30 is the same as the array row direction of the image surface cropping grating mark transparent array on the image surface cropping grating plate 60. The array direction of the array formed by the object surface small hole marks 310 on the object surface small hole plate 30 is the same as the array column direction of the image surface cut grating mark transparent array on the image surface cut grating plate 60. The image cut raster marks 610 in the same array row have the same raster direction. In FIG. 4 exemplarily, the array row direction of the image-cutting raster marks 610 forming an array is parallel to the X direction, and the array column direction of the image-cutting grating marks 610 forming an array is parallel to the Y direction. The g object surface small hole marks 310 with different grating directions in the same object surface small hole 31 correspond one-to-one to the g image surface cropping grating marks 610 with different grating directions in the same image surface cropping grating 61, one-to-one correspondence The grating direction of the small hole mark 310 on the object plane is perpendicular to the grating direction of the image cutting raster mark 610.

Exemplarily, referring to FIGS. 2 and 4, the same object surface small hole 31 includes two object surface small hole marks 310 with different grating directions, such as object surface small hole mark O1U1 and object surface small hole mark O1V1. The same image-cutting grating 61 includes two image-cutting grating marks 610 with different grating directions, for example, the image-cutting grating mark IV11 and the image-cutting grating mark IU12. The small hole mark on the object surface O1U1 corresponds to the image cutting grating mark IV11, and the small hole mark on the object surface Note that the grating direction of O1U1 is perpendicular to the grating direction of the image cut grating mark IV11. The object surface small hole mark O1V1 corresponds to the image surface cropping grating mark IU12, and the grating direction of the object surface small hole mark O1V1 is perpendicular to the image surface cropping grating mark IU12.

個物面小孔標記310，且

為大於或者等於2的正整數。為了對物面小孔板30上一陣列行的物面小孔標記310同時檢測，需要設置像面剪切光柵板60上一陣列行中像面剪切光柵標記610的數量至少為

個。即，一陣列行中像面剪切光柵標記610的數量大於或者等於一陣列行中物面小孔標記310的數量。另外，像面剪切光柵板60上一陣列行中像面剪切光柵標記610的數量最多可以佈置n個。 Referring to Figures 2, 3 and 4, along the X direction, the object surface small hole plate 30 is arrayed with n object surface small hole marks 310 in the first grating direction and n object surface small holes in the second grating direction. In the mark 310, n is a positive integer greater than or equal to 2. Each array row contains

A small hole on the surface is marked 310, and

It is a positive integer greater than or equal to 2. In order to simultaneously detect the object surface small hole marks 310 in an array row on the object surface small hole plate 30, it is necessary to set the number of image surface cropping grating marks 610 in an array row on the image surface cropping grating plate 60 at least

indivual. That is, the number of image-cutting raster marks 610 in an array row is greater than or equal to the number of object-surface aperture marks 310 in an array row. In addition, the number of image-cutting grating marks 610 in an array row on the image-cutting grating plate 60 can be arranged at most n.

FIG. 5 is a schematic diagram of another object surface small hole plate provided by an embodiment of the present invention, and FIG. 6 is a schematic diagram of another image shearing grating plate provided by an embodiment of the present invention. Referring to FIG. 5 and FIG. 6, object surface small hole The mark O1U1 has a first grating direction, and the object surface small hole mark O1V1 has a second grating direction. The object surface small hole mark O1U1 and the object surface small hole mark O1V1 belong to the same object surface small hole 31. In the embodiment of the present invention, the angle between the first grating direction and the array row direction is 45°, and the angle between the second grating direction and the array row direction is 45°. In other embodiments, the angle between the first grating direction and the array row direction can also be 10°, 20°, 30°, 40°, 50°, 60°, 70°, or 80°, depending on the product. The embodiment of the present invention does not limit the angle between the first grating direction and the array row direction. In the embodiment of the present invention, the measurement difficulty can be reduced by setting the angle between the second grating direction and the array row direction to be 45°.

The array row direction of the small hole marks 310 on the object plane is parallel to the X direction, and the array column direction of the small hole marks 310 on the object plane is parallel to the Y direction. The object surface small hole mark O1U1 corresponds to the image surface cropping grating mark IV11, and the grating direction of the object surface small hole mark O1U1 is perpendicular to the image surface cropping grating mark IV11. The object surface small hole mark O1V1 corresponds to the image surface cropping grating mark IU12, and the grating direction of the object surface small hole mark O1V1 is perpendicular to the image surface cropping grating mark IU12.

FIG. 7 is a schematic diagram of another image shearing grating plate provided by an embodiment of the present invention. Referring to FIG. 7, the image shearing grating plate 60 includes a checkered grating array, and the checkered grating array includes a plurality of light-transmitting cells. 602 and a plurality of non-transparent cells 601. Along the row direction and the column direction of the checkered grating array, the light-transmitting unit cells 602 and the non-light-transmitting unit cells 601 are arranged at intervals. The image-cutting grating plate 60 provided by the embodiment of the present invention no longer has g image-cutting grating marks 610 in different grating directions, but adopts a checkered grating array. The coordinated use of the checkerboard grating array and the array of small hole marks 310 on the object surface realizes the measurement of the wave aberration of the projection objective lens.

Referring to FIG. 7, the angle between the row direction of the checkerboard grating array and the array row direction of the small hole marks 310 on the object plane is 45°. The array row direction of the small hole marks 310 on the object plane is parallel to the X direction, the angle between the row direction of the checkerboard grating array and the X direction is 45°, and the angle between the column direction of the checkerboard grating array and the X direction is 45°.

Referring to FIG. 1, the numerical aperture of the projection objective lens 40 is greater than or equal to 0.85. In the field of lithography machines, the projection objective 40 with a numerical aperture greater than or equal to 0.85 is a projection objective with a large numerical aperture. It can be understood that the numerical aperture of the projection objective lens 40 in the embodiment of the present invention refers to the maximum numerical aperture that the projection objective lens 40 can achieve. For those with a numerical aperture greater than or equal to 0.85 The projection objective 40 can achieve any numerical aperture of the projection objective 40 less than 0.85 by adjusting the diaphragm and other elements in the projection objective 40, for example, a numerical aperture of 8 can be achieved. In other embodiments, the numerical aperture of the projection objective lens 40 may be less than 0.85, depending on the requirements of the product. Since the projection objective lens 40 with a large numerical aperture is prone to signal crosstalk during wave aberration detection, and the interference to the projection objective lens 40 with a numerical aperture greater than or equal to 0.85 is more likely to occur. Therefore, in the embodiment of the present invention, by setting the numerical aperture of the projection objective 40 to be greater than or equal to 0.85, signal crosstalk during wave aberration detection is avoided for a projection objective with a large numerical aperture.

An embodiment of the present invention also provides a lithography machine including the wave aberration measuring device in any of the foregoing embodiments. In the lithography machine provided in the embodiment of the present invention, the object surface small hole mark of the wave aberration measuring device is provided with an array of object surface small hole marks, and the illumination beam emitted by the illumination system scans and illuminates a row of object surface small hole marks, Thereby improving the detection efficiency. There are m-1 field of view points between two adjacent small hole marks on the object surface in the same array row to avoid signal crosstalk during wave aberration detection for projection objectives with large numerical apertures.

FIG. 8 is a flowchart of a method for measuring wave aberration according to an embodiment of the present invention. Referring to FIG. 1 to FIG. 8, the method for measuring wave aberration includes the following steps:

S110, the illumination beam generated by the illumination system 10 scans and illuminates the object surface small hole mark 310 array of the object surface small hole plate 30 to form a measuring beam. Shear the interference pattern.

S120, the two-dimensional array photosensitive element 70 receives the shearing interference pattern row by row, and sends it to the data processing unit 80. The data processing unit 80 calculates the wave aberration of the projection objective lens 40 based on the shear interference pattern.

Wherein, along the array row direction, the illumination beam generated by the aforementioned illumination system irradiates and reads two small hole marks on the object surface with at least one field of view point.

When the wave aberration measuring method is implemented by the wave aberration measuring device in any of the foregoing embodiments, each object surface aperture 31 includes g object surface aperture marks 310 with different grating directions, and g is a positive value greater than or equal to 2. An integer, the plurality of object surface small hole marks 310 on the object surface small hole plate 30 are arranged in an array. The row direction of the array formed by a plurality of object surface small hole marks 310 is the X direction, and the column direction of the array formed by a plurality of object surface small hole marks 310 is the Y direction. The small hole marks 310 on the object surface in the same array row have the same grating direction. Along the array row direction, the distance between two adjacent object surface small hole marks 310 in the same array row is h1; along the array row direction, the two closest object surface small hole marks 310 in the two array rows with the same grating direction The minimum distance between them is h2, h1=m×h2, and m is a positive integer greater than or equal to 2. Any two rows of small hole marks 310 on the object surface with the same grating direction are arranged in an array. In the embodiment of the present invention, along the array row direction, there is at least one field of view point between two adjacent small hole marks on the object surface. For each scan along the array row direction, the illumination beam generated by the illumination system illuminates one by one to read all the small hole marks on the object surface on the array row.

Optionally, the illumination beam generated by the illumination system 10 sequentially scans and irradiates the object surface small hole mark 310 array of the object surface small hole plate 30 to form a measurement beam, and the measurement beam passes through the projection objective lens 40 and then irradiates the image shearing grating plate 60. To form a shearing interference pattern; (ie, step S110) includes the following sub-steps:

S1111, the illumination beam generated by the illumination system 10 irradiates an array of the object surface small hole marks 310 on the object surface small hole plate 30 on the object surface small hole mark 310 array to form a measuring beam. The measuring beam passes through the projection objective lens 40 and then irradiates the The small hole marks 310 on the object surface of the array row correspond one-to-one and the grating marks 610 are cut from the image surface perpendicular to the grating direction of the small hole marks 310 on the object surface of the array row to form a scissor. Cut the interference pattern.

S1112, move at least one of the following devices, so that the illuminating beam scans the small hole marks 310 of the object surface of all the array rows: the mask stage 20 and the workpiece stage 50.

A plurality of image-cutting gratings 61 are provided on the image-cutting grating plate 60, and each of the image-cutting gratings 61 includes g image-cutting grating marks 610 with different grating directions, and the image-cutting grating plate 60 is A plurality of image plane cropping grating marks 610 are arranged in an array. The image cut raster marks 610 in the same array row have the same raster direction. The array row direction of the image-cutting raster marks 610 forming an array is parallel to the X direction, and the array column direction of the image-cutting grating marks 610 forming an array is parallel to the Y direction. The g object surface small hole marks 310 with different grating directions in the same object surface small hole 31 correspond one-to-one to the g image surface cropping grating marks 610 with different grating directions in the same image surface cropping grating 61, one-to-one correspondence The grating direction of the small hole mark 310 on the object plane is perpendicular to the grating direction of the image cutting raster mark 610.

Exemplarily, the process of using the object-plane small aperture plate 30 shown in FIG. 2 and the image-plane shearing grating plate 60 shown in FIG. 4 to perform wave aberration detection of the projection objective lens 40 is as follows:

In the first step, the illuminating beam passes through the object surface hole mark 310 (object surface hole mark O1U1, object surface hole mark O3U1, object surface hole mark O5U1... .) is irradiated on the image cut raster mark 610 (image cut raster mark IV11, image cut raster mark IV21...Image cut raster mark IVn1) whose grating direction is parallel to the Y direction. Measurement. In the second step, the illuminating beam passes through the second row of the object surface hole mark 310 whose grating direction is parallel to the X direction (object surface hole mark O2U2, object surface hole mark O4U2...object surface hole mark OnU2) The image cut raster mark 610 irradiated to the grating direction parallel to the Y direction (image cut grating mark IV11, image cut grating mark IV21...Image cut grating mark Record IVn1) on the measurement. In the third step, the illuminating beam passes through the third row of object surface hole marks 310 whose grating direction is parallel to the Y direction (object surface hole mark O1V1, object surface hole mark O3V1, object surface hole mark O5V1... ) Is irradiated on the image cut raster mark 610 (image cut raster mark IU12, image cut raster mark IU22...Image cut raster mark IUn2) whose grating direction is parallel to the X direction for measurement . In the fourth step, the illumination beam passes through the fourth row of the object surface hole mark 310 whose grating direction is parallel to the Y direction (object surface hole mark O2V2, object surface hole mark O4V2...object surface hole mark OnV2) It is irradiated on the image cutting raster mark 610 (image cutting raster mark IU12, image cutting raster mark IU22...image cutting raster mark IUn2) whose grating direction is parallel to the X direction for measurement.

Exemplarily, the process of using the small aperture plate 30 on the object plane as shown in FIG. 3 and the shearing grating plate 60 on the image plane as shown in FIG. 4 to perform the wave aberration detection of the projection objective lens is as follows:

In the first step, the illuminating beam passes through the object surface hole mark 310 (object surface hole mark O1U1, object surface hole mark O3U1, object surface hole mark O5U1... .) is irradiated on the image cut raster mark 610 (image cut raster mark IV11, image cut raster mark IV21...Image cut raster mark IVn1) whose grating direction is parallel to the Y direction. Measurement. In the second step, the illuminating beam passes the grating direction parallel to the Y direction. The second row of the object surface small hole mark 310 (object surface small hole mark O1V1, object surface small hole mark O3V1, object surface small hole mark O5V1...) It is irradiated on the image cutting raster mark 610 (image cutting raster mark IU12, image cutting raster mark IU22...image cutting raster mark IUn2) whose grating direction is parallel to the X direction for measurement. In the third step, the illumination beam passes through the third row of the object surface hole mark 310 whose grating direction is parallel to the X direction (object surface hole mark O2U2, object surface hole mark O4U2...object surface hole mark OnU2) The image plane irradiated to the grating direction parallel to the Y direction cuts the grating mark 610 (Image cutting raster mark IV11, image cutting raster mark IV21...Image cutting raster mark IVn1) for measurement. In the fourth step, the illuminating beam passes through the fourth row of the object surface small hole mark 310 in the Y direction (object surface small hole mark O2V2, object surface small hole mark O4V2...object surface small hole mark OnV2) to irradiate to the X direction Measured on the image cut raster mark 610 (image cut raster mark IU12, image cut raster mark IU22...Image cut raster mark IUn2).

Optionally, the illumination beam generated by the illumination system 10 sequentially scans and irradiates the object surface small hole mark 310 array of the object surface small hole plate 30 to form a measurement beam, and the measurement beam passes through the projection objective lens 40 and then irradiates the image shearing grating plate 60. To form a shearing interference pattern; (ie, step S110) includes the following sub-steps:

S1121: The illumination beam generated by the illumination system 10 irradiates an array of the object surface small hole marks 310 on the object surface small hole mark array of the object surface small hole plate 30 to form a measurement beam, and the measurement beam passes through the projection objective lens 40 and then irradiates the chess grid Shape grating array to form a shearing interference pattern.

S1122, move at least one of the following devices, so that the illuminating beam scans the small hole marks 310 of the object surface of all the array rows: the mask stage 20 and the workpiece stage 50.

The image shearing grating plate 60 includes a checkered grating array, and the checkered grating array includes a plurality of light-transmitting cells 602 and a plurality of non-light-transmitting cells 601. Along the row direction and the column direction of the checkered grating array, the light-transmitting unit cells 602 and the non-light-transmitting unit cells 601 are arranged at intervals.

Exemplarily, the process of using the small aperture plate 30 on the object plane as shown in FIG. 2 and the shearing grating plate 60 on the image plane as shown in FIG. 7 to perform the wave aberration detection of the projection objective lens is as follows:

In the first step, the illuminating beam passes through the object surface hole mark 310 in the first row whose grating direction is parallel to the X direction (object surface hole mark O1U1, object surface hole mark O3U1, object surface hole mark O5U1......) is irradiated on the checkerboard grating array for measurement. In the second step, the illuminating beam passes through the second row of the object surface hole mark 310 whose grating direction is parallel to the X direction (object surface hole mark O2U2, object surface hole mark O4U2...object surface hole mark OnU2) Illuminate to the checkered grating array for measurement. In the third step, the illuminating beam passes through the third row of object surface hole marks 310 whose grating direction is parallel to the Y direction (object surface hole mark O1V1, object surface hole mark O3V1, object surface hole mark O5V1... ) Is irradiated on the checkerboard grating array for measurement. The fourth step, the illumination beam passes through the grating direction parallel to the object surface hole mark 310 in the fourth row of the Y direction (object surface hole mark O2V2, object surface hole mark O4V2...Object surface hole mark OnV2) Illuminate to the checkered grating array for measurement.

In other embodiments, the wave aberration measurement method can also be performed by a wave aberration measurement device other than the foregoing embodiment. FIG. 9 is a schematic diagram of another object surface small hole plate provided by an embodiment of the present invention, and each field of view point is provided with an object surface small hole mark 310. Along the array row direction (that is, the X direction), there is at least one object surface small hole mark 310 between the two object surface small hole marks 310 that are irradiated and read twice by the illumination beam generated by the illumination system. In the embodiment of the present invention, along the array row direction, there is at least one field of view point between two adjacent small hole marks on the object surface. For each scan along the direction of the array row, the illumination beam generated by the illumination system irradiates and reads the small hole marks on the part of the object surface on the array row at intervals. All the small hole marks on the object surface on the array row need to be scanned and read multiple times.

Exemplarily, referring to FIG. 9, the process of using the small aperture plate 30 shown in FIG. 9 and the image shearing grating plate 60 shown in FIG. 7 to perform the wave aberration detection of the projection objective lens is as follows:

In the first step, the illumination beam passes through a part of the object surface hole mark 310 (object surface hole mark O1U1, object surface hole mark O3U1, object surface hole mark O5U1......) is irradiated on the checkerboard grating array for measurement. In the second step, the illumination beam passes through the other part of the object surface small hole mark 310 in the first row where the grating direction is parallel to the X direction (object surface small hole mark O2U1, object surface small hole mark O4U1...Object surface small hole The mark OnU1) is irradiated on the checkerboard grating array for measurement. In the third step, the illumination beam passes through a part of the object surface hole mark 310 (object surface hole mark O1V1, object surface hole mark O3V1, object surface hole mark O5V1... ..) irradiate the checkerboard grating array for measurement. In the fourth step, the illumination beam passes through the other part of the object surface small hole mark 310 (object surface small hole mark O2V1, object surface small hole mark O4V1, object surface small hole mark OnV1... ...) irradiate the checkerboard grating array for measurement.

The present invention claims the priority of a Chinese patent application filed with the Chinese Patent Office with an application number of 201910471627.8 on May 31, 2019. The entire content of the above application is incorporated into the present invention by reference.

31: Small holes on the surface

310: Small hole mark on the object surface

Claims (12)

A wave aberration measuring device, its characteristics include: The lighting system is set to generate an illuminating beam; The object surface aperture plate is located on the light-emitting side of the aforementioned illumination system and is fixed on the mask stage. The object surface aperture plate is provided with a plurality of object surface apertures, and each of the aforementioned object surface apertures contains g different grating directions. The small hole mark on the object surface, g is a positive integer greater than or equal to 2, and the plurality of small hole marks on the object surface are arranged in an array on the small orifice plate of the object surface; The aforementioned object-surface small hole marks in the same array row have the same grating direction; along the array row direction, the distance between two adjacent object-surface small hole marks in the same array row is h1; along the aforementioned array row direction, the grating The minimum distance between the two aforementioned small hole marks on the object surface in two array rows with the same direction is h2, h1=m×h2, where m is a positive integer greater than or equal to 2; any two rows with the same grating direction. Array arrangement of small hole marks on the object surface; The projection objective lens is located on the side of the small orifice plate on the object surface away from the illumination system; The image cutting grating plate is located on the side of the aforementioned projection objective lens away from the aforementioned small orifice plate of the object plane, and is fixed on the workpiece table; A two-dimensional array photosensitive element and a data processing unit, the aforementioned two-dimensional array photosensitive element is located on the conjugate plane of the pupil of the aforementioned projection objective lens, and the aforementioned two-dimensional array photosensitive element is used to receive the shear formed on the aforementioned two-dimensional array photosensitive element The interference pattern, the aforementioned data processing unit is used to calculate the wave aberration of the aforementioned projection objective lens according to the aforementioned shearing interference pattern. The wave aberration measuring device described in the first item of the scope of the patent application, wherein the object surface aperture includes the object surface aperture mark in the first grating direction and the object surface aperture mark in the second grating direction. The first grating direction is perpendicular to the aforementioned second grating direction; In the same aforementioned object surface small hole, the object surface small hole mark in the first grating direction and the object surface small hole mark in the second grating direction are arrayed at intervals of m-1; or, In the same object surface small holes, the object surface small hole marks in the first grating direction and the object surface small hole marks in the second grating direction are sequentially arranged along the array column direction. As for the wave aberration measuring device described in item 2 of the scope of patent application, wherein the first grating direction is parallel to the array row direction; or the angle between the first grating direction and the array row direction is 45°. The wave aberration measuring device described in item 1 of the scope of patent application, wherein the image shearing grating plate is provided with a plurality of image shearing gratings, and each of the image shearing gratings includes g different grating directions The image-cutting grating marks on the aforementioned image-cutting grating plate are arranged in an array of the aforementioned image-cutting grating marks; the aforementioned image-cutting grating marks in the same array row have the same grating direction; The g aperture marks of the object surface with different grating directions in the object surface aperture correspond one-to-one to the g image shearing grating marks with different grating directions in the same image surface shearing grating, and the corresponding object surface aperture marks are one-to-one. The raster direction of is perpendicular to the raster direction of the image cut raster mark. For the wave aberration measuring device described in item 4 of the scope of patent application, the number of the aforementioned image-cutting grating marks in an array row is greater than or equal to the number of the aforementioned object-surface aperture marks in an array row. For the wave aberration measuring device described in item 1 of the scope of patent application, wherein the image shearing grating plate includes a checkered grating array, and the checkered grating array includes a plurality of light-transmitting cells and a plurality of non-transmitting cells. Optical cell; along the row and column directions of the aforementioned checkerboard grating array Orientation, the aforementioned light-transmitting unit cells and the aforementioned non-light-transmitting unit cells are arranged at intervals. The wave aberration measuring device described in item 6 of the scope of patent application, wherein the angle between the row direction of the checkerboard grating array and the row direction of the array of small hole marks on the object plane is 45°. As the wave aberration measuring device described in any one of items 1 to 7 in the scope of the patent application, the numerical aperture of the aforementioned projection objective lens is greater than or equal to 0.85. A lithography machine is characterized in that it includes the wave aberration measuring device described in any one of items 1 to 8 in the scope of the patent application. A method for measuring wave aberration, its characteristics include: The illumination beam generated by the illumination system scans and illuminates the object surface small hole mark array of the object surface small hole plate by line to form a measurement beam. The aforementioned measurement beam passes through the projection objective lens and irradiates the image shearing grating plate to form a shearing interference pattern; The two-dimensional array photosensitive element receives the aforementioned shearing interference pattern row by row and sends it to the data processing unit; the aforementioned data processing unit calculates the wave aberration of the aforementioned projection objective lens according to the aforementioned shearing interference pattern; Wherein, along the array row direction, the illumination beam generated by the aforementioned illumination system irradiates and reads two small hole marks on the object surface with at least one field of view point. As the method described in item 10 of the scope of patent application, wherein the illumination beam generated by the aforementioned illumination system scans and illuminates the object surface aperture mark array of the object surface aperture plate to form a measurement beam, and the aforementioned measurement beam passes through the projection objective lens and irradiates it to The image plane cuts the grating plate to form a shearing interference pattern; including: The illumination beam generated by the aforementioned illumination system irradiates an array of rows of the object surface small hole marks on the object surface small hole plate on the object surface small hole mark array to form a measurement beam, and the aforementioned measurement beam passes through the projection objective lens. Irradiating the image plane cropping grating marks that correspond one-to-one to the aforementioned object surface small hole marks of the array row and perpendicular to the aforementioned object surface small hole mark grating direction of the array row to form a shearing interference pattern; Move at least one of the following devices so that the aforementioned illumination beam scans the aforementioned small hole marks on the object surface in all array rows: the mask stage and the workpiece stage; Wherein, the aforementioned image-cutting grating plate is provided with a plurality of image-cutting gratings, each of the aforementioned image-cutting gratings includes g image-cutting grating marks of different grating directions, and the aforementioned image-cutting grating plate The plurality of aforementioned image-cutting grating marks are arranged in an array; the aforementioned image-cutting grating marks in the same array row have the same grating direction; g object-face hole marks with different grating directions in the same object-face hole There is a one-to-one correspondence with g image-cutting grating marks of different grating directions in the same image-cutting grating, and the grating direction of the small hole mark of the corresponding object plane is perpendicular to the grating direction of the image-cutting grating mark. As the method described in item 10 of the scope of patent application, wherein the illumination beam generated by the aforementioned illumination system scans and illuminates the object surface aperture mark array of the object surface aperture plate to form a measurement beam, and the aforementioned measurement beam passes through the projection objective lens and irradiates it to The image plane cuts the grating plate to form a shearing interference pattern; including: The illumination beam generated by the aforementioned illumination system irradiates an array of the object surface small hole marks on the object surface small hole mark array of the object surface small hole plate to form a measurement beam. Form a shear interference pattern; Move at least one of the following devices so that the aforementioned illumination beam scans the aforementioned small hole marks on the object surface in all array rows: the mask stage and the workpiece stage; Wherein, the aforementioned checkerboard grating array includes a plurality of light-transmitting unit cells and a plurality of non-light-transmitting unit cells; along the row direction and column direction of the aforementioned checkerboard grating array, the aforementioned light-transmitting unit cell and the front The non-light-transmitting cells are all arranged at intervals.

Images