TWI731523B - Projection objective lens wave aberration detection device and method, and photoetching machine - Google Patents

Abstract

The invention provides a device and method for detecting wave aberration of a projection objective lens, and a photoetching machine. The projection objective wave aberration detection device includes: a light source for providing a detection beam; an object grating marking unit for splitting the detection beam to obtain a first beam in a first direction and a second beam in a second direction ; Splitting and collimating unit, used to split and collimate the light beam passing through the projection objective unit; Diffraction unit, used to diffract the light passing through the splitting and collimating unit to obtain interference images in two directions Workpiece table, used for marking unit with animal surface grating, beam splitting and collimating unit, diffraction unit and imaging detection unit to step along a straight line unidirectionally in a predetermined direction between the first direction and the second direction, which can simultaneously collect the first The light intensity of the interference image at each step of the first beam and the second beam is used to obtain wave aberrations in the first direction and the second direction, respectively. Therefore, the detection time is shortened and the detection accuracy of wave aberration is improved.

Description

Projection objective lens wave aberration detection device and method, and photoetching machine

The present invention relates to the field of optical technology, in particular to a projection objective lens wave aberration detection device, a projection objective lens wave aberration detection method, and a lithography machine including the projection objective lens wave aberration detection device.

The lithography machine is one of the key equipment in the production process of integrated circuits (IC), which projects the pattern on the mask plate through the projection objective lens unit on a substrate (such as a wafer) spin-coated with photoresist. Image quality is an important factor that affects the lithography resolution and overlay accuracy of the lithography machine. With the continuous reduction of the lithography feature size (CD), the influence of the wave aberration of the projection objective lens of the lithography machine on the lithography quality is becoming more and more prominent. It is an important factor that limits the resolution of the projection system and also causes the line width. An important reason for the change. Therefore, it is necessary to detect the wave aberration of the projection objective lens unit of the lithography machine online to ensure the quality of the lithography.

One method of measuring wave aberration online is shearing interferometry. This method needs to measure in the two directions of 0° and 90°. A small hole is used on the object surface to generate a detection light source. The small hole is imaged by the projection objective lens to the grating mark on the image surface and generates shearing interference fringes in the far field. The three-dimensional array photosensitive element records the interference image on the conjugate plane of the pupil of the projection objective. The study found that since the 0° direction measurement and the 90° direction measurement are carried out separately during the measurement process, this will cause the position and fluctuation of the workpiece stage during the 0° phase shift process and the workpiece stage during the 90° phase shift process There is a deviation between the position and fluctuation of the, and this deviation affects the accuracy of the wave aberration detection; moreover, the separate test in the above two directions requires a long time and the test efficiency is low.

One of the objectives of the present invention is to provide a projection objective lens wave aberration detection device to solve the problem of low wave aberration detection accuracy in the 0° direction and the 90° direction.

Another object of the present invention is to provide a method for detecting wave aberration of a projection objective, so as to solve the problem of long wave aberration detection time and improve the test efficiency.

In order to solve the above technical problems, on the one hand, the present invention provides a projection objective lens wave aberration detection device for detecting the wave aberration of the projection objective lens unit, including: a light source, an object grating marking unit, a beam splitting collimation unit, and a diffraction unit , An imaging detection unit and a workpiece stage; the light source is used to provide a detection beam, and the detection beam is incident on the object surface grating marking unit; the object surface grating marking unit is used to divide the detection beam into a first party The upward first light beam and the second light beam in the second direction, the first light beam and the second light beam are incident on the projection objective lens unit and then enter the light splitting and collimating unit; the light splitting and collimating unit is used to pass through After the first beam and the second beam of the projection objective lens unit are subjected to splitting and collimation processing, a first direction imaging and a second direction imaging are formed on the diffraction unit; After the first direction imaging and the second direction imaging are subjected to diffraction processing, an interference image in the first direction and an interference image in the second direction are formed on the imaging detection unit respectively; the workpiece table is used to drive the The object surface grating marking unit, the light splitting collimation unit, the diffraction unit, and the imaging detection unit are stepped unidirectionally along a straight line in a predetermined direction between the first direction and the second direction, so that the imaging The detection unit simultaneously collects the first beam And the light intensity of the interference image formed at each step of the second light beam to obtain the wave aberrations in the first direction and the second direction respectively; wherein, the first direction and the second direction vertical.

Optionally, the object surface grating marking unit includes a first substrate and a two-dimensional grating mark, the two-dimensional grating mark is located on a side of the first substrate facing the projection objective lens unit, and the two-dimensional grating mark is used for To obtain the first light beam and the second light beam.

Optionally, the two-dimensional grating mark includes: first slit marks arranged along the first direction, and the first slit marks are used to obtain the first light beam; and the first slit marks arranged along the second direction Two slit marks, and the second slit marks are used to obtain the second light beam.

Optionally, the light splitting and collimating unit includes: a second substrate; a first one-dimensional grating mark group for performing light splitting processing on the first light beam and the second light beam incident on the light splitting and collimating unit, so as to be divided into the first light beam and the second light beam. Directional light beam and second directional light beam, the first one-dimensional grating mark group is located on the side of the second substrate facing the projection objective lens unit; the second one-dimensional grating mark group is used to transmit the first directional light beam Collimating the light beam in the second direction to obtain the first direction imaging and the second direction imaging, and the second one-dimensional grating mark group is located on the side of the second substrate facing away from the projection objective lens unit on.

Optionally, the first one-dimensional grating mark group includes a plurality of first one-dimensional grating marks with the same period, and the second one-dimensional grating mark group includes a plurality of second one-dimensional grating marks with the same period. Further, the diffraction angle of the first one-dimensional grating mark is 30°-60°, and the first one-dimensional grating mark The grating period of the one-dimensional grating mark is 100nm~300nm. Furthermore, the grating period of the first one-dimensional grating mark is the same as the grating period of the second one-dimensional grating mark.

Optionally, the diffraction unit includes: a third substrate; and a third one-dimensional grating mark group for performing diffraction processing on the imaging in the first direction and the imaging in the second direction. The dimensional grating mark group is located on the side of the third substrate facing the light splitting and collimating unit. Further, the third one-dimensional grating mark group includes at least a pair of third one-dimensional grating marks with the same period, and the grating period of the third one-dimensional grating mark is the same as the grating period of the two-dimensional grating mark. Furthermore, each pair of the third one-dimensional grating marks includes two mutually perpendicular third one-dimensional grating marks, and the two mutually perpendicular third one-dimensional grating marks are respectively used for imaging the first direction Imaging with the second direction to perform diffraction processing.

Optionally, the imaging detection unit includes: an image acquisition unit configured to perform image acquisition on the interference image in the first direction and the interference image in the second direction, and select the acquisition area; And a driving unit for driving the image acquisition unit to perform image acquisition. Wherein, the number of the image acquisition unit is one.

It also includes a processing unit, which is communicatively connected with the imaging detection unit, and is configured to process the data transmitted by the image acquisition unit to obtain the wave aberration in the first direction and the wave aberration in the second direction. Wave aberration.

On the other hand, the present invention also provides a lithography machine including a projection objective lens unit and the above-mentioned projection objective wave aberration detection device.

In yet another aspect, the present invention also provides a method for detecting wave aberration of a projection objective lens, which adopts the above-mentioned device for detecting wave aberration of a projection objective lens, and includes the following steps: The light source provides a detection beam which is incident on the object surface grating marking unit; the object surface grating marking unit splits the detection beam to obtain the first beam in the first direction and the second beam in the second direction. Two light beams, the first direction and the second direction are perpendicular; the first light beam and the second light beam enter the beam splitting and collimating unit after passing through the projection objective lens unit, and the beam splitting and collimating unit divides the first beam After performing the splitting and collimation processing with the second light beam, the first direction imaging and the second direction imaging are formed on the diffraction unit respectively; the diffraction unit performs the diffraction of the first direction imaging and the second direction imaging After processing, an interference image in the first direction and an interference image in the second direction are respectively formed on the imaging detection unit; and the workpiece table drives the object surface grating marking unit, the spectroscopic collimation unit, the diffraction unit, and the imaging detection unit. Stepping unidirectionally along a straight line in a predetermined direction between the first direction and the second direction, and the imaging detection unit simultaneously collects the interference formed by each step of the first light beam and the second light beam The light intensity of the image to obtain the wave aberration in the first direction and the second direction respectively.

Optionally, the step of obtaining the wave aberration in the first direction and the second direction includes: collecting, by an image acquisition unit, the interference image in the first direction and the second direction in each step. The light intensity of the interference image; the processing unit processes the data transmitted by the image acquisition unit, and calculates the pupil plane of the shearing interference spot in the first direction and the second direction at each step Interference light intensity; The wave aberrations in the first direction and the second direction are respectively calculated according to the pupil surface interference light intensity of the shearing interference spot in the first direction and the second direction.

Further, the first direction is a 0° direction, the second direction is a 90° direction, and the phase shift direction of the workpiece table step is any angular direction between 0° and 90°.

Furthermore, the calculation formula of the pupil surface interference light intensity of the shearing interference spot in the first direction and the second direction is as follows:

Among them, U ₀ ( x, y, d ) is the first direction pupil interference light intensity when the coordinates are (x, y) and the stepping distance is d, and U ₉₀ ( x, y, d ) is the coordinates of (x , Y), the pupil plane interference light intensity in the second direction when the step distance is d, n is the order of diffraction, p is the grating period of the third one-dimensional grating mark, and δ ( x ) is the intensity of the shearing interference spot The x-direction position of the center, δ ( y ) is the y-direction position of the intensity center of the sheared interference spot, λ is the wavelength of the detection beam generated by the light source, x is the coordinate in the first direction, and y is the coordinate in the second direction.

Optionally, the phase shift direction of the step of the workpiece table is a 45° direction.

Compared with the prior art, the wave aberration detection device of the projection objective of the present invention simultaneously images the first light beam in the first direction and the second light beam in the second direction to simultaneously detect the first direction and the second direction. Wave aberration, specifically, the first light beam and the second light beam obtained after the detection light beam passes through the object surface grating marking unit enters the beam splitting and collimating unit after passing through the projection objective lens unit, and the beam splitting and collimating unit separates the first beam and the second beam. After the two beams are split and collimated, they are respectively imaged on the diffraction unit. The diffraction unit performs diffraction processing on the image on it, and forms an interference image on the imaging detection unit respectively, thereby shortening the wave aberration Detection time and reduce When the wave aberration in the first direction and the wave aberration in the second direction are separately detected due to the influence of the inconsistency of the fluctuation of the workpiece stage, it is beneficial to improve the detection accuracy of the wave aberration.

11: First beam

12: Second beam

11': first direction beam

12': second direction beam

11": first direction imaging

12": second direction imaging

100: Object surface grating marking unit

110: First substrate

120: Two-dimensional raster marking

200: Projection objective lens unit

310: The first one-dimensional raster marking group

311, 312, 313: the first one-dimensional raster mark

320: second base

330: The second one-dimensional raster mark group

331, 332, 333: the second one-dimensional raster mark

400: Diffraction unit

410: The third one-dimensional grating mark group

411, 412: The third one-dimensional raster mark

420: Third Base

500: imaging detection unit

600: Workpiece table

a: stepping direction

Fig. 1 is a schematic structural diagram of a wave aberration detection device for a projection objective lens according to an embodiment of the present invention; Fig. 2 is a schematic diagram of a diffraction spot marked by a two-dimensional grating according to an embodiment of the present invention; Fig. 3 is a schematic diagram of an embodiment of the present invention The imaging detector collects the interferogram in the 0° direction; Fig. 4 is the 90° interferogram collected by the imaging detector of an embodiment of the present invention; Fig. 5 is the 0° and 90° grating mark phase shift direction of an embodiment of the present invention .

In order to make the objectives and features of the present invention more comprehensible, the specific embodiments of the present invention will be further described below with reference to the accompanying drawings. It should be noted that the drawings all adopt a very simplified form and all use imprecise ratios, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

This embodiment discloses a projection objective wave aberration detection device, for example, a projection objective wave aberration detection device of a lithography machine, which is used to detect the wave aberration of the projection objective lens unit. As shown in FIG. 1, the projection objective lens unit 200 is, for example, a projection objective lens.

The projection objective wave aberration detection device includes a light source (not shown in the figure), the light source is used to provide a detection beam, and the light source is, for example, a deep ultraviolet laser source.

The device for detecting wave aberration of the projection objective lens further includes an illumination system for adjusting the detection light beam. The detection light beam adjusted by the illumination system is incident on the object surface grating marking unit 100.

As shown in FIG. 1, the projection objective wave aberration detection device further includes an object surface grating marking unit 100, which is used to split the detection light beam to obtain a first (polarization) direction The first light beam 11 on the upper side and the second light beam 12 in the second (polarization) direction, wherein the first direction and the second direction are perpendicular, for example, the first direction is a 0° (polarization) direction, and the The second direction is a 90° (polarization) direction; or, the first direction is a 90° direction, and the second direction is a 0° direction. In the following description, the first direction is the 0° direction and the second direction is the 90° direction. As an example, the object surface grating marking unit 100 includes a first substrate 110 and a two-dimensional grating mark 120 formed on the first substrate 110. The material of the first substrate 110 is preferably a material with a relatively high light transmittance (the light transmittance is greater than 80%), for example, quartz glass. The side of the first substrate 110 facing away from the light source is, for example, the lower surface of the first base 110, and the lower surface of the first base 110 further has a light blocking layer (not shown in the figure). The light blocking layer covers the area outside the two-dimensional grating mark 120. For example, a light-blocking material is coated on the area outside the two-dimensional grating mark 120 on the lower surface of the quartz glass (the transmittance of the light-blocking material is preferably less than or equal to 2%, which can be approximately regarded as being able to block all Light), the light blocking material is, for example, chromium.

The two-dimensional grating mark 120 is used to obtain a first light beam 11 in a first direction and a second light beam 12 in a second direction, and the two-dimensional grating mark 120 is located on the lower surface of the first substrate 110, for example, It is located at the center of the lower surface of the first substrate 110. The duty ratio of the grating mark of the two-dimensional grating mark 120 is, for example, 50%, that is, the ratio of the area occupied by the light-transmitting area and the opaque area of the two-dimensional grating mark 120 is 1:1. The two-dimensional grating mark 120 includes a first slit mark and a second slit mark, and both the first slit mark and the second slit mark are in a grid shape (for example, a bar-shaped grid); The slit marks are slit marks arranged along the first direction, which are used to obtain the first light beam 11 in the first direction, and the grating mark duty ratio of the first slit marks is 50%; Two slit marks are slit marks arranged along the second direction for obtaining For the second light beam 12 in the second direction, the grating mark duty ratio of the second slit mark is 50%. FIG. 2 is a schematic diagram of a diffracted light spot marked by a two-dimensional grating according to this embodiment. As shown in FIG. 2, the detection light beam generated by the light source passes through the illumination system and passes through the two-dimensional grating mark 120 of the object surface grating marking unit 100 to obtain a first light beam 11 in a first direction and a second light beam 12 in a second direction. The diffraction order of the detection beam in the figure is -1, 0, +1.

Please continue to refer to FIG. 1, the projection objective lens wave aberration detection device further includes a beam splitting collimator unit and a diffraction unit 400, and the beam splitting collimator unit is used to transfer the first light beam 11 passing through the projection objective lens unit 200. After being split and collimated with the second light beam 12, they are respectively imaged on the diffraction unit 400, so that the detection light beam is imaged in the first direction and the second direction at the same time. As an example, the light splitting and collimating unit is used to perform light splitting processing on the first light beam 11 and the second light beam 12 to separate the first light beam 11 and the second light beam 12 (for example, 0° direction and 90° direction) After being separated, the separated first light beam 11 and the second light beam 12 are incident on the diffraction unit 400.

Specifically, the light splitting and collimating unit includes a second substrate 320, a first one-dimensional grating mark group 310, and a second one-dimensional grating mark group 330. The material of the second substrate 320 is preferably a material with a relatively high light transmittance (the light transmittance is preferably greater than 80%), for example, quartz glass. The surface of the second substrate 320 facing the projection objective lens unit 200 is, for example, the upper surface of the second substrate 320, and the surface of the second substrate 320 facing the diffraction unit 400 is, for example, the second substrate 320. On the lower surface of the second substrate 320, there is also a light blocking layer (not shown in the figure) on the upper surface of the second substrate 320, and the light blocking layer covers the area outside the first one-dimensional grating mark group 310. For example, a light-blocking material is coated on the upper surface of the quartz glass outside the first one-dimensional grating mark group 310 (the light-blocking material preferably has a light transmittance of less than or equal to 2%, which can be approximately regarded as Block all light), the light blocking material is, for example, chromium. The lower surface of the second substrate 320 also has a light blocking layer (not shown in the figure), and the light blocking layer covers the area outside the second one-dimensional grating mark group 330. In the same way, a barrier is applied to the area outside the second one-dimensional grating mark group 330 on the lower surface of the quartz glass. Light material (the light transmittance of the light blocking material is preferably less than or equal to 2%, which can be approximately regarded as being able to block all light), the light blocking material is, for example, chromium.

The first one-dimensional grating mark group 310 is used to perform splitting processing on the first beam 11 and the second beam 12 incident on the beam splitting and collimating unit, so as to be divided into a first direction beam 11' and a second direction beam 12'. Wherein, the first one-dimensional grating mark group 310 is located on the upper surface of the second substrate 320. In detail, the first one-dimensional grating mark group 310 includes a plurality of first one-dimensional grating marks with the same period, the first one-dimensional grating mark is, for example, a one-dimensional spectroscopic grating mark, and the first one-dimensional grating mark The duty cycle of the grating mark is, for example, 50%. The plurality of first one-dimensional grating marks with the same period are, for example, distributed on the upper surface of the second substrate 320, and further, distributed on the center position of the upper surface of the second substrate 320 and a plurality of concentric centers with the center position as the center. There are at least two first one-dimensional grating marks on the circumference of each concentric circle. In a preferred solution, the first one-dimensional grating mark group 310 divides the first beam 11 and the second beam 12 incident on the beam splitting and collimating unit into a first direction beam 11' and a second direction beam 12 with uniform light intensity. '. It can be seen from the above that after the first light beam 11 in the first direction and the second light beam 12 in the second direction pass through the projection objective unit 200, the first one-dimensional grating mark 310 of the light splitting and collimating unit is subjected to light splitting processing, so that the first The first beam 11 in the first direction and the second beam 12 in the second direction are separated, so that the first beam 11 in the first direction and the second beam 12 in the second direction can simultaneously perform wave aberration detection, which shortens The time for wave aberration detection is shortened, and the production efficiency is improved.

In this embodiment, the first one-dimensional grating mark group 310 includes three first one-dimensional grating marks 311, 312, 313 with the same period, wherein the first one-dimensional grating mark 312 is located on the second substrate 320 The first one-dimensional grating marks 311, 312, 313 are located on the same straight line, and the first one-dimensional grating marks 311, 313 are located on both sides of the first one-dimensional grating mark 312 at the same distance.

The second one-dimensional grating mark group 330 is used for collimating the first direction light beam 11' and the second direction light beam 12'. The second one-dimensional grating mark group 330 is located on a side of the second substrate 320 facing away from the projection objective lens unit 200. Wherein, the second one-dimensional grating mark group 330 includes a plurality of second one-dimensional grating marks with the same period, the second one-dimensional grating marks are, for example, one-dimensional collimated grating marks, and the second one-dimensional grating marks The duty cycle of the grating mark is, for example, 50%. The grating period of the first one-dimensional grating mark is the same as the grating period of the second one-dimensional grating mark. The plurality of second one-dimensional grating marks with the same period are, for example, distributed on the circumference of a plurality of concentric circles centered on the center of the lower surface of the second substrate 320, or the plurality of second one-dimensional grating marks with the same period The one-dimensional grating marks are, for example, distributed on the center position of the lower surface of the second substrate 320 and the circumference of multiple concentric circles centered on the center position, and each concentric circle has at least two second one-dimensional gratings on the circumference. Mark, so that most of the light in the first direction light beam 11' and the second direction light beam 12' can be emitted separately. Preferably, the number of the second one-dimensional grating marks for collimating the first direction light beam 11' is the same as the number of the second one-dimensional grating marks for collimating the second direction light beam 12', so as to pass the beam splitting The light intensity of the light beam 11' in the first direction of the collimating unit is the same as the light intensity of the light beam 12' in the second direction.

In this embodiment, the second one-dimensional grating mark group 330 may include three second one-dimensional grating marks 331, 332, and 333 with the same period. The second one-dimensional grating mark 332 is located on the second substrate. The second one-dimensional grating marks 331, 332, and 333 are located on the same straight line at the center of the lower surface of 320, and the second one-dimensional grating marks 331, 333 are located on both sides of the second one-dimensional grating mark 332 at the same distance.

In other embodiments, the second one-dimensional grating mark group may also include two second one-dimensional grating marks with the same period, and the two second one-dimensional grating marks are located from the lower surface to the center of the second substrate. Any position with the same distance. The two second one-dimensional grating marks are respectively used to collimate the first direction light beam 11' and the second direction light beam 12', so that after emission The light intensity of the light beam 11' in the first direction is the same as the light intensity of the light beam 12' in the second direction. In addition, the two second one-dimensional grating marks may also be located at other positions on the lower surface of the second substrate, and the positions of the two second one-dimensional grating marks only need to satisfy the requirements of the emitted light beam 11' in the first direction. The light intensity may be the same as the light intensity of the light beam 12' in the second direction.

其中，d為第一一維光柵標記的光柵周期，θ為第一一維光柵標記的繞射角度，為光源所產生的檢測光束的波長，x為分光準直單元分光及準直後所形成的光斑的直徑，n為第二基底的折射率，h為第二基底的厚度。 In order to avoid interference between the light spots after the first one-dimensional grating mark is split, the grating period of the first one-dimensional grating mark and the thickness of the second substrate 320 satisfy the following relationship: dnsinθ=λ;

Among them, d is the grating period of the first one-dimensional grating mark, θ is the diffraction angle of the first one-dimensional grating mark, is the wavelength of the detection beam generated by the light source, and x is the result of the splitting and collimation of the beam splitting and collimating unit The diameter of the spot, n is the refractive index of the second substrate, and h is the thickness of the second substrate.

It can be seen from the above that when the diffraction angle of the first one-dimensional grating mark is too large, the grating period of the first one-dimensional grating mark becomes smaller, and the thickness of the second substrate 320 is too thin, making the processing of the second substrate 320 more difficult. When the diffraction angle of the first one-dimensional grating mark is too small, the grating period of the first one-dimensional grating mark becomes larger, and the thickness of the second substrate 320 is too thick, which exceeds the expected demand range. Therefore, preferably, the diffraction angle of the first one-dimensional grating mark is 30°-60°, the grating period of the first one-dimensional grating mark is 100 nm to 300 nm, and the thickness of the second substrate 320 is 1 mm to 6 mm. It should be understood that during specific implementation, the diffraction angle of the first one-dimensional grating mark is other than 30°~60°, the grating period is other than 100nm~300nm, and the thickness of the second substrate 320 is 1mm~ Values other than 6mm can be changed according to actual needs.

The diffraction unit 400 is used to perform diffraction processing on the imaging thereon, and then form interference images on the imaging detection unit respectively. As an example, the diffraction unit 400 includes a first A three-substrate 420 and a third one-dimensional grating mark group 410. The material of the third substrate 420 is preferably a material with a relatively high light transmittance (the light transmittance is greater than 80%), for example, quartz glass. The surface of the third substrate 420 facing the light splitting and collimating unit is, for example, the upper surface of the third substrate 420, and the upper surface of the third substrate 420 further has a light blocking layer (not shown in the figure). The optical layer covers the area outside the third one-dimensional grating mark group 410. For example, a light-blocking material is coated on the area outside the third one-dimensional grating mark group 410 on the upper surface of the quartz glass (the transmittance of the light-blocking material is preferably less than or equal to 2%, which can be approximately regarded as Block all light), the light blocking material is, for example, chromium.

The third one-dimensional grating mark group 410 is used for diffracting the imaging on the diffraction unit 400, that is, diffracting the first light beam 11 and the second light beam 12 passing through the beam splitting and collimating unit Processing to generate a shearing interference spot in the first direction and a shearing interference spot in the second direction, that is, to form an interference image in the first direction and the second direction. The third one-dimensional grating mark group 410 is located on the upper surface of the third substrate 420.

The third one-dimensional grating mark group 410 includes at least one pair of third one-dimensional grating marks with the same period, the third one-dimensional grating marks are in a grid shape (for example, a bar-shaped grid), and each pair of the third one-dimensional grating marks The one-dimensional grating mark includes two third one-dimensional grating marks perpendicular to each other, which are used to perform diffraction processing on imaging in the first direction and imaging in the second direction, respectively. In other words, the third one-dimensional grating mark group 410 includes, for example, an even number of third one-dimensional grating marks, such as 2, 4, 6, and so on. Half of the third one-dimensional grating marks are used to diffract 11" in the first direction, and the other half of the third one-dimensional grating marks are used to diffract 12" in the second direction to make imaging detection The unit 500 can collect one or more sets of interference images in the first direction, and one or more sets of interference images in the second direction. Among them, the third one-dimensional grating used to diffract the image 11" in the first direction is marked as a strip grid arranged along the first direction, and the third one used to diffract the image 12" in the second direction is The dimensional grating marks are strip-shaped grids arranged along the second direction. Further, the grating period of the third one-dimensional grating mark is the same as the grating period of the two-dimensional grating mark 120 with. In this embodiment, the third one-dimensional grating mark group 410 includes two third one-dimensional grating marks 411, 412, wherein the third one-dimensional grating mark 411 is used to diffract the image 11" in the first direction. The three-dimensional grating mark 412 is used to diffract the image 12" in the second direction.

The device for detecting wave aberration of the projection objective lens further includes an imaging detection unit 500 for image collection of the interference image formed thereon. The first direction imaging 11" and the second direction imaging 12" respectively form interference images on the imaging detection unit 500 after passing through the diffraction unit, so that the interference images in the first direction and the second direction can be collected at the same time . As an example, the imaging detection unit 500 includes an image acquisition unit (not shown in the figure) and a driving unit (not shown in the figure). The image acquisition unit is used for image acquisition on the interference image and selection of the acquisition area. The image acquisition unit is, for example, a complementary metal oxide semiconductor (CMOS) acquisition chip, the upper surface of which is coated with a fluorescence conversion layer, that is, the surface facing the third substrate 420 A layer of fluorescence conversion layer is coated on it. Preferably, when the image acquisition unit performs image acquisition, the image acquisition unit is located directly below the diffraction unit 400. There is a gap between the image acquisition unit and the diffraction unit 400, and the gap makes the image imaged to the image acquisition unit a far-field image. The distance of the gap is greater than or equal to 1 mm, preferably 1 mm to 2 mm. In a preferred solution, the number of the image acquisition unit is one, so that one image acquisition unit can collect the interference image in the first direction and the interference image in the second direction at the same time, which is similar to that in the prior art. Compared with the use of two imaging detectors, it reduces the influence of dark current, nonlinearity, and bad pixel inconsistency between the two imaging detectors on the consistency of the final collected graphics, thereby improving the wave aberration Detection accuracy. The driving unit is, for example, a driving board, which is used to drive the image acquisition unit to perform image acquisition. The image acquisition unit is, for example, located on the drive unit.

Fig. 3 is an interferogram collected by the imaging detector of this embodiment in the 0° direction. Fig. 4 is an interferogram in the 90° direction collected by the imaging detector of this embodiment. As shown in Figures 3 and 4, the first direction The interference image of the first light beam 11 on the imaging detection unit 500 (that is, the 0° direction) is a sheared interference spot in the first direction, and the second light beam 12 in the second direction (ie, the 90° direction) is The interference image on the imaging detection unit 500 is a shearing interference spot in the second direction. Wherein, the diffraction order of the image collected by the image collecting unit is, for example, -1, 0, +1. In this embodiment, it is simultaneously imaged on the image acquisition unit, and is simultaneously acquired by the same image acquisition unit. Compared with the existing one that can only acquire one direction at a time, the detection time is shortened, and the wave image is also improved. Poor detection accuracy.

The projection objective wave aberration detection device also includes a processing unit (not shown in the figure), which is communicatively connected to the imaging detection unit 500, and is used to process the data transmitted by the graphics acquisition unit to calculate The wave aberration in the first direction and the wave aberration in the second direction are shown.

Continuing to refer to FIG. 1, the projection objective wave aberration detection device further includes a workpiece stage 600, which is used to drive the object surface grating marking unit 100, the light splitting collimation unit, the diffraction unit, and the imaging detection unit 500 Step unidirectionally along a straight line in a predetermined direction between the first direction and the second direction, so that the imaging detection unit 500 simultaneously collects the interference of the first light beam 11 and the second light beam 12 at each step The light intensity of the image to obtain the wave aberration in the first direction and the second direction respectively.

The detection light beam provided by the light source of this embodiment passes through the object surface grating marking unit to obtain a first light beam in a first direction and a second light beam in a second direction, and the first light beam and the second light beam pass through the projection objective lens unit After entering the light splitting and collimating unit, the light splitting and collimating unit splits and collimates the first light beam and the second light beam and then images on the diffraction unit respectively, and the diffraction unit images the image thereon After the diffraction processing is performed, interference images are respectively formed on the imaging detection unit to obtain the wave aberration in the first direction and the wave aberration in the second direction at the same time.

This embodiment also discloses a lithography machine, which includes a projection objective lens unit and the above-mentioned projection objective wave aberration detection device. Since the focus of the present invention is on the wave aberration of the projection objective Therefore, other known structures of the lithography machine will not be introduced in detail, and those skilled in the art should be aware of it.

This embodiment also discloses a method for detecting wave aberration of a projection objective lens, for example, a method for detecting wave aberration of a projection objective lens of a lithography machine. The method adopts the above-mentioned projection objective lens wave aberration detection device and includes the following steps: Step S1: Provide A detection beam, the detection beam is incident on an object surface grating marking unit; step S2: the object surface grating marking unit splits the detection beam to obtain a first beam in a first direction and a second direction Step S3: The first beam and the second beam enter the beam splitting and collimating unit after passing through the projection objective lens unit, and the beam splitting and collimating unit will After the light beam and the second light beam are split and collimated, they are respectively imaged on the diffraction unit; step S4: the diffraction unit performs diffraction processing on the image thereon and then forms an interference image on the imaging detection unit respectively; and Step S5: The workpiece table drives the object surface grating marking unit, the spectroscopic collimation unit, the diffraction unit and the imaging detection unit to step along a straight line unidirectionally in a predetermined direction between the first direction and the second direction, so The imaging detection unit simultaneously collects the light intensity of the interference image at each step of the first light beam and the second light beam to obtain the wave aberrations in the first direction and the second direction respectively.

Hereinafter, a method for detecting wave aberration of a projection objective lens of this embodiment will be described in detail with reference to FIG. 1 and FIG. 5.

First, step S1 is performed to provide a detection beam, and the light source is, for example, a deep ultraviolet laser source. The detection beam is incident on an object surface grating marking unit 100.

Next, step S2 is performed. The object surface grating marking unit 100 splits the detection light beam to obtain a first light beam 11 in a first direction and a second light beam 12 in a second direction. The two directions are perpendicular.

Then step S3 is executed, the first light beam 11 and the second light beam 12 enter the beam splitting and collimating unit after passing through the projection objective lens unit 200, and the beam splitting and collimating unit splits and collimates the first beam 11 and the second beam 12 After straight processing, they are respectively imaged on the diffraction unit.

Then, step S4 is executed, and the diffraction unit performs diffraction processing on the image thereon, and then forms interference images on the imaging detection unit 500 respectively.

Figure 5 shows the 0° and 90° grating mark phase shift directions of this embodiment. As shown in FIG. 5, please refer to FIG. 1 at the same time. Then, step S5 is executed. The workpiece stage 600 drives the object surface grating marking unit 100, the beam splitting collimation unit, the diffraction unit, and the imaging detection unit 500 in the first direction and the second direction. One-way stepping along a straight line in a predetermined direction between the directions, the imaging detection unit 500 simultaneously collects the light intensity of the interference image of each step of the first light beam 11 and the second light beam 12 to respectively The wave aberration in the first direction and the second direction is obtained. It can be seen that when the workpiece table 600 is stepped in a certain direction a between the first direction and the second direction, the light intensity of the collected interference image can be decomposed into the light intensity of the first direction and the second direction by calculation, so that the The light intensities of one direction and the second direction are collected at the same time, thereby shortening the time of image collection and improving the test efficiency.

Wherein, the first direction is, for example, a 0° direction, the second direction is, for example, a 90° direction, and the phase shift direction of the step of the workpiece table 600 is, for example, any angle between 0° and 90°, preferably Yes, the phase shift direction of the step of the workpiece stage 600 is 45°. As shown in FIG. 5, when the workpiece stage 600 is stepped, the first slit mark and the second slit mark in the two-dimensional grating mark 120 of the object surface grating marking unit 100 follow the workpiece stage 600 Step in the step direction a.

In this step, the specific steps of obtaining the wave aberration in the first direction and the second direction include:

Step S5a: Collect the light intensity of the interference image for each step by the imaging detection unit 500.

Step S5b: The processing unit processes the data transmitted from the graphics acquisition unit 500, and calculates the pupil interference light intensity of the shearing interference spot in the first direction and the second direction at each step.

In this embodiment, the calculation formula of the pupil surface interference light intensity of the shearing interference spot in the 0° direction and the 90° direction is as follows:

Among them, U ₀ ( x, y, d ) is the first direction pupil interference light intensity when the coordinates are (x, y) and the step distance is d, and U ₉₀ ( x, y, d ) is the coordinates of (x , Y), the pupil plane interference light intensity in the second direction when the step distance is d, n is the order of diffraction, p is the grating period of the third one-dimensional grating mark, and δ ( x ) is the intensity of the shearing interference spot The x-direction position of the center, δ ( y ) is the y-direction position of the intensity center of the sheared interference spot, λ is the wavelength of the detection beam generated by the light source, x is the coordinate in the first direction, and y is the coordinate in the second direction.

It can be seen from the above that by simultaneously collecting the light intensity of the interference image formed by the first light beam 11 and the second light beam 12, the wave aberration in the first direction and the second direction can be detected at the same time, which is compared with the prior art. Therefore, the problem of inconsistency in the fluctuation of the workpiece stage 600 when the image acquisition in the first direction and the image acquisition in the second direction are separated is eliminated, and the detection accuracy of wave aberration is improved.

Step S5c: According to the pupil surface interference light intensity of the shearing interference spot in the first direction and the second direction, respectively calculate the wave aberration in the first direction and the second direction.

In summary, a projection objective wave aberration detection device and method, and a lithography machine of the present invention, the projection objective wave aberration detection device, by simultaneously comparing the first beam in the first direction and the second beam in the second direction Second beam imaging to detect wave images in the first direction and the second direction at the same time In other words, the first light beam and the second light beam obtained after the detection light beam passes through the object surface grating marking unit enters the beam splitting and collimating unit after passing through the projection objective lens unit, and the beam splitting and collimating unit separates the first beam and the second beam. After the second light beam is split and collimated, it is imaged on the diffraction unit. The diffraction unit performs diffraction processing on the image on it, and forms an interference image on the imaging detection unit, thereby shortening The detection time of the wave aberration reduces the influence of the inconsistency of the wave aberration in the workpiece stage when the wave aberration in the first direction and the wave aberration in the second direction are detected separately, which is beneficial to improve the detection accuracy of the wave aberration.

In addition, it should be noted that, unless otherwise specified or pointed out, the description of the terms "first", "second", and "third" in the specification are only used to distinguish each component, element, step, etc. in the specification, and It is not used to indicate the logical relationship or sequence relationship between various components, elements, and steps.

It can be understood that although the present invention has been disclosed as above in preferred embodiments, the above-mentioned embodiments are not intended to limit the present invention. For any person skilled in the art, without departing from the scope of the technical solution of the present invention, the technical content disclosed above can be used to make many possible changes and modifications to the technical solution of the present invention, or modified into equivalent changes, etc. Efficacies. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments without departing from the technical solution of the present invention based on the technical essence of the present invention still fall within the protection scope of the technical solution of the present invention.

11: First beam

12: Second beam

11': first direction beam

12': second direction beam

11": first direction imaging

12": second direction imaging

100: Object surface grating marking unit

110: First substrate

120: Two-dimensional raster marking

200: Projection objective lens unit

310: The first one-dimensional raster marking group

311, 312, 313: the first one-dimensional raster mark

320: second base

330: The second one-dimensional raster mark group

331, 332, 333: the second one-dimensional raster mark

400: Diffraction unit

410: The third one-dimensional grating mark group

411, 412: The third one-dimensional raster mark

420: Third Base

500: imaging detection unit

600: Workpiece table

Claims (19)

A projection objective wave aberration detection device, which is used to detect the wave aberration of a projection objective lens unit. The projection objective wave aberration detection device is characterized by comprising: a light source, an object grating marking unit, a beam splitting collimation unit, and a diffraction Unit, imaging detection unit and workpiece stage; the light source is used to provide a detection light beam, the detection light beam is incident on the object surface grating marking unit; the object surface grating marking unit is used to divide the detection light beam into the first The first light beam and the second light beam in the second direction, the first light beam and the second light beam are incident on the projection objective lens unit and then enter the light splitting and collimating unit; the light splitting and collimating unit is used to After the first and second light beams of the projection objective unit are subjected to splitting and collimation processing, a first direction imaging and a second direction imaging are formed on the diffraction unit; the diffraction unit is used to After the first direction imaging and the second direction imaging are subjected to diffraction processing, an interference image in the first direction and an interference image in the second direction are respectively formed on the imaging detection unit; the workpiece table is used to drive The object surface grating marking unit, the light splitting collimation unit, the diffraction unit and the imaging detection unit are unidirectionally stepped along a straight line in a predetermined direction between the first direction and the second direction, so that the The imaging detection unit simultaneously collects the light intensity of the interference image formed at each step of the first light beam and the second light beam to obtain the wave aberrations in the first direction and the second direction respectively; The first direction is perpendicular to the second direction. The projection objective wave aberration detection device according to claim 1, wherein the object surface grating marking unit includes a first substrate and a two-dimensional grating mark, and the two-dimensional grating mark is located at the The first substrate faces a surface of the projection objective lens unit, and the two-dimensional grating mark is used to obtain the first light beam and the second light beam. The projection objective wave aberration detection device according to claim 2, wherein the two-dimensional grating marks include: first slit marks arranged along the first direction, and the first slit marks are used to obtain the first Light beam; and a second slit mark arranged along the second direction, the second slit mark is used to obtain a second light beam. The projection objective wave aberration detection device according to any one of claims 1 to 3, wherein the beam splitting and collimating unit includes: a second substrate; a first one-dimensional grating mark group for collimating the beam to the beam splitting The first light beam and the second light beam on the unit are subjected to light splitting processing to be divided into a first direction light beam and a second direction light beam, and the first one-dimensional grating mark group is located on the side of the second substrate facing the projection objective lens unit ; The second one-dimensional grating mark group, used to collimate the first direction light beam and the second direction light beam to obtain the first direction imaging and the second direction imaging, the second one-dimensional The grating mark group is located on the side of the second substrate facing away from the projection objective lens unit. The projection objective wave aberration detection device according to claim 4, wherein the first one-dimensional grating mark group includes a plurality of first one-dimensional grating marks with the same period, and the second one-dimensional grating mark group includes a plurality of The second one-dimensional grating mark with the same period. The projection objective wave aberration detection device according to claim 5, wherein the diffraction angle of the first one-dimensional grating mark is 30°~60°, and the grating period of the first one-dimensional grating mark is 100nm~300nm . The projection objective wave aberration detection device according to claim 6, wherein the grating period of the first one-dimensional grating mark and the grating period of the second one-dimensional grating mark are the same. The projection objective wave aberration detection device according to claim 2, wherein the diffraction unit includes: a third substrate; and a third one-dimensional grating mark group for imaging the first direction and the second The directional imaging is subjected to diffraction processing, and the third one-dimensional grating mark group is located on the side of the third substrate facing the light splitting and collimating unit. The projection objective wave aberration detection device according to claim 8, wherein the third one-dimensional grating mark group includes at least a pair of third one-dimensional grating marks with the same period, and the grating period of the third one-dimensional grating mark The grating period is the same as the two-dimensional grating mark. The projection objective wave aberration detection device according to claim 9, wherein each pair of the third one-dimensional grating marks includes two mutually perpendicular third one-dimensional grating marks, and the two mutually perpendicular third one-dimensional grating marks The grating marks are respectively used to perform diffraction processing on the imaging in the first direction and the imaging in the second direction. The projection objective wave aberration detection device according to any one of claims 1 to 3, wherein the imaging detection unit includes: an image acquisition unit configured to compare the interference image in the first direction and the second Two-direction interference images are used for image collection, and the collection area is selected; and a driving unit for driving the image collection unit to perform image collection. The device for detecting wave aberration of a projection objective lens according to claim 11, wherein the number of the image acquisition unit is one. The device for detecting wave aberration of a projection objective lens according to claim 11, which further includes a processing unit, which is communicatively connected with the imaging detection unit, and is configured to process The data transmitted by the image acquisition unit to obtain the wave aberration in the first direction and the wave aberration in the second direction. A photoetching machine is characterized by comprising: a projection objective lens unit and the projection objective lens wave aberration detection device according to any one of claims 1 to 13. A method for detecting wave aberration of projection objective lens, which adopts the device for detecting wave aberration of projection objective lens according to any one of Claims 1 to 13. The method for detecting wave aberration of projection objective lens is characterized in that it comprises the following steps: the light source is provided A detection light beam, the detection light beam is incident on the object surface grating marking unit; the object surface grating marking unit splits the detection light beam to obtain a first light beam in a first direction and a second light beam in a second direction , The first direction and the second direction are perpendicular; the first light beam and the second light beam enter the beam splitting and collimating unit after passing through the projection objective lens unit, and the beam splitting and collimating unit separates the first beam and the second beam After the two light beams are split and collimated, the first direction imaging and the second direction imaging are respectively formed on the diffraction unit; the diffraction unit performs the diffraction processing on the first direction imaging and the second direction imaging The interference image in the first direction and the interference image in the second direction are respectively formed on the imaging detection unit; and the workpiece table drives the object surface grating marking unit, the light splitting collimation unit, the diffraction unit and the imaging detection unit in the Step unidirectionally along a straight line in a predetermined direction between the first direction and the second direction, and the imaging detection unit simultaneously collects the interference image formed by each step of the first light beam and the second light beam In order to obtain the wave aberration in the first direction and the second direction respectively. The method for detecting wave aberration of a projection objective lens according to claim 15, wherein the step of obtaining the wave aberration in the first direction and the second direction includes: The light intensity of the interference image in the first direction and the interference image in the second direction for each step is collected by the image acquisition unit; the data transmitted by the image acquisition unit is processed by the processing unit, and Calculate the pupil surface interference light intensity of the shearing interference spot in the first direction and the second direction at each step; according to the pupil surface interference light of the shearing interference spot in the first direction and the second direction Strong, respectively calculate the wave aberration in the first direction and the second direction. The method for detecting wave aberration of a projection objective lens according to claim 16, wherein the first direction is a 0° direction, the second direction is a 90° direction, and the phase shift direction of the workpiece stage step is at 0° Any angle direction between ~90°. The method for detecting wave aberration of projection objective lens according to claim 16 or 17, wherein the calculation formula of the pupil surface interference light intensity of the shearing interference spot in the first direction and the second direction is as follows:

Among them, U ₀ ( x, y, d ) is the first direction pupil interference light intensity when the coordinates are (x, y) and the stepping distance is d, and U ₉₀ ( x, y, d ) is the coordinates of (x , Y), the pupil plane interference light intensity in the second direction when the step distance is d, n is the order of diffraction, p is the grating period of the third one-dimensional grating mark, and δ ( x ) is the intensity of the shearing interference spot The x-direction position of the center, δ ( y ) is the y-direction position of the intensity center of the sheared interference spot, λ is the wavelength of the detection beam generated by the light source, x is the coordinate in the first direction, and y is the coordinate in the second direction. The method for detecting wave aberration of a projection objective lens according to claim 18, wherein the phase shift direction of the step of the workpiece stage is a direction of 45°.

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