TWI704432B - Aberration measuring device and method - Google Patents

Abstract

The present invention provides an aberration measurement device and method. The aberration measurement method includes: a mask marking unit is moved to the center position of the field of view of the projection objective lens unit to be tested; the mask alignment unit measures that the mask marking unit is at a predetermined Upward the predetermined position and Z position of all the marks, and calculate the predetermined position difference and the Z position difference of two adjacent marks in the predetermined upward direction. The predetermined direction is the X direction and/or the Y direction; The predetermined-direction position difference and the Z-direction position difference of all two adjacent marks obtain the distortion and field curvature of the predetermined V line or H line of the objective field of view. During the measurement, two identical pre-directional detectors measure the marks at the same time. The calculation is based on the pre-determined position difference and the Z-direction position difference of two adjacent marks in the predetermined upward direction. Therefore, this measurement is not affected by the drift of the workpiece table and The influence of the movement error of the work table greatly improves the measurement accuracy of the low-order aberration of the objective lens.

Description

Aberration measuring device and method

The invention relates to the technical field of integrated circuit manufacturing equipment, in particular to an aberration measuring device and method.

Lithography machine is a kind of equipment used in integrated circuit manufacturing. The equipment using this equipment includes but not limited to: integrated circuit manufacturing lithography device, liquid crystal panel lithography device, photomask engraving device, MEMS (Micro Electro Mechanical System) /MOMS (Micro Optical Machine System) lithography equipment, advanced packaging lithography equipment, printed circuit board lithography equipment and printed circuit board processing equipment, etc.

The distortion of the projection objective is an important factor affecting the image quality of the lithography machine. The distortion of the projection objective lens can not only cause the deformation of the image of the objective lens, but also cause the pattern exposed on the silicon wafer to be displaced relative to its ideal position, thereby causing overprinting errors. Modern integrated circuits are generally composed of dozens of layers of circuits, so the matching error requirements of the photoetching machine are extremely strict. The distortion of the projection objective is a key factor that affects the matching of engraving between photoetching machines. Therefore, the detection of the distortion of the projection objective lens is indispensable for ensuring the engraving error of the lithography machine.

The prior art discloses a marking structure for measuring the distortion of a projection objective. The marking structure is formed on a mask. The mask defines a first direction and a second direction perpendicular to the first direction. The marking structure includes a first pattern. Area and a second pattern area, an independent mark is set at the center of the first pattern area, the second pattern area is composed of array marks, and the first pattern area and the second pattern area are arranged along the second direction . The invention also discloses a method for measuring the distortion of a projection objective, which includes making the independent mark coincide with the center position of the field of view of the projection objective; setting the position of the workpiece stage as x _ws = xM×X _{i , j} , y _ws = yM×Y _i , the independent mark is exposed, where M is the magnification of the projection objective lens, and x and y are the center position of the silicon wafer exposure field; make the center of the second pattern area or the center of the mask and the projection objective lens The field center positions are coincident, and the workpiece stage position is set to x _ws = x, y _ws = y and then exposed; detect the position error of the engraved mark Δx _{i , j} , Δy _{i , j} ; calculate the distortion of the projection objective. In this method, the measurement result is affected by the movement error of the workpiece stage, which leads to the low-order aberration measurement accuracy of the objective lens.

The problems in the method for measuring the distortion of the projection objective in the prior art described above will also directly affect the final performance of the lithography equipment. Therefore, a method is urgently needed to overcome the deficiencies of the existing methods.

The object of the present invention is to provide an aberration measuring device and method to solve the problem that the method of measuring the distortion of the projection objective in the prior art is affected by the movement error of the workpiece stage, resulting in the low-order aberration measurement accuracy of the objective lens.

In order to solve the above technical problems, the present invention provides an aberration measuring device, the aberration measuring device comprising: an alignment lighting unit, a mask marking unit, and a mask aligning unit that are sequentially distributed from top to bottom along a space, wherein, The mask marking unit and the mask aligning unit are used to set a projection objective lens unit to be tested, and the mask aligning unit includes at least two identical X-directional detectors and/or at least two identical In the Y-direction detector, the distance between a pair of adjacent X-direction detectors and/or the distance between a pair of adjacent Y-direction detectors is the first distance.

Optionally, in the aberration measuring device, the mask marking unit includes at least two X-direction marks and/or at least two Y-direction marks, and the distance between adjacent pairs of X-direction marks and /Or the interval between a pair of adjacent Y-direction marks is the second interval.

Optionally, in the aberration measuring device, the numerical ratio of the first distance to the second distance is m, where m is the objective lens magnification of the projection objective lens unit to be tested.

Optionally, in the aberration measuring device, the size ratio between the mark in the mask marking unit and the detector in the mask alignment unit is m, where m is the objective lens of the projection objective unit to be measured Magnification.

The present invention also provides a method for aberration measurement, the method for aberration measurement using the aberration measurement device as described above includes the following steps:

S1: The mask marking unit is moved to the center of the field of view of the projected objective lens unit to be tested;

S2: Under the illumination of the aligning lighting unit, the mask aligning unit measures the predetermined position and Z position of all the marks of the mask mark unit in the predetermined direction, and calculates the predetermined position difference of two adjacent marks in the predetermined upward direction Value and Z-direction position difference, the predetermined direction is X-direction and/or Y-direction;

S3: Obtain the distortion and curvature of field of the objective lens field of view in the predetermined direction V line or H line according to the predetermined position difference and the Z position difference of all two adjacent marks in the predetermined direction.

Optionally, in the aberration measurement method, when the predetermined direction is the X-direction, the mask alignment unit includes two identical X-direction detectors, and the two same X-direction detectors are simultaneously The X-direction position and the Z-direction position of the mark of the mask marking unit in a predetermined upward direction are measured.

Optionally, in the aberration measurement method, when the predetermined direction is the Y direction, the mask alignment unit includes two identical Y-direction detectors, and the two same Y-direction detectors are simultaneously The Y-direction position and the Z-direction position of the mark of the mask marking unit in a predetermined upward direction are measured.

Optionally, in the aberration measurement method, in step S3, the predetermined direction V line of the objective lens field of view is obtained according to the predetermined position difference and the Z position difference of all two adjacent marks in the predetermined direction Distortions include:

Calculate the predetermined direction distortion of the objective lens corresponding to two adjacent marks based on the predetermined position difference of each pair of adjacent two marks, and obtain the predetermined direction distortion of the objective field of all two adjacent marks according to the predetermined direction The field of view of the objective lens is intended to be distorted to the V line.

Optionally, in the method for aberration measurement, when the predetermined direction is the X direction, the calculation of the predetermined direction position difference of each pair of adjacent two marks corresponding to the predetermined direction The formula for the distortion of the objective field of view is as follows: DT0=0; DT1=DT0+x1; DT2=DT1+x2; … DTn=DT(n-1)+xn;

Among them, DT0 is the initial value of X-direction distortion, DT1 is the distortion of the first pair of adjacent two marks in X-direction, DT2 is the distortion of the second pair of adjacent two marks in X-direction, and DTn is the x-direction n-th adjacent pair of two adjacent marks. Distortion of a mark, n is a positive integer greater than 2; x1 is the difference between the first mark and the second mark in the X direction, x2 is the difference between the second mark and the third mark in the X direction, and xn is the nth mark And the (n+1)-th mark X-direction position difference.

Optionally, in the method for aberration measurement, obtaining the X-direction V-line distortion of the objective field of view according to the X-direction distortion of all the marked objective lens fields in the X direction includes:

Array the distortion of X to all two adjacent marks, and remove the first-order quantity.

Optionally, in the aberration measurement method, in step S3, the predetermined direction V line of the objective lens field of view is obtained according to the predetermined position difference and the Z position difference of all two adjacent marks in the predetermined direction The song includes:

Calculate the field curvature of the field of view of the objective lens corresponding to the two adjacent marks based on the Z-direction position difference of each pair of adjacent marks in the predetermined direction, and calculate the predetermined field of the field of view of the objective lens of all two adjacent marks according to the predetermined direction The curve obtains the field curvature of the objective lens to the V line.

Optionally, in the method of aberration measurement, when the predetermined direction is the X direction, the calculation of the Z direction position difference of each pair of adjacent two marks corresponding to the predetermined direction The formula for the field curvature of the objective field of view is as follows: FC0=0; FC1=FC0+z1; FC2=FC1+z2; … FCn=FC(n-1)+zn;

Among them, FC0 is the initial value of field curvature in the X direction, FC1 is the field curvature of the first pair of adjacent two marks in the X direction, FC2 is the field curvature of the second pair of adjacent marks in the X direction, and FCn is the nth pair in the X direction The field curvature of two adjacent marks, n is a positive integer greater than 2; z1 is the Z position difference between the first mark and the second mark, z2 is the Z position difference between the second mark and the third mark, zn Is the difference between the nth mark and the (n+1)th mark in the Z direction.

Optionally, in the method for measuring aberrations, obtaining the line curvature of the field of view of the objective lens in the X direction according to the field curvature of the field of view of all the marked objectives in the X direction in the X direction includes:

The field curvatures of all two adjacent markers are grouped in X, and the first-order quantity is removed.

In the aberration measurement device and method provided by the present invention, the aberration measurement method includes: a mask marking unit is moved to the center position of the field of view of the projection objective lens unit to be measured; the mask alignment unit measures the mask marking unit According to the predetermined direction, all the marks in the predetermined direction are at the predetermined position and the Z position, and the predetermined position difference and the Z position difference of the two adjacent marks in the predetermined direction are calculated, and the predetermined direction is the X direction and/or the Y direction; The predetermined direction position difference and the Z direction position difference of all two adjacent marks in the predetermined upward direction obtain the distortion and field curvature of the predetermined direction V line or H line of the objective lens field of view. During the measurement, two same pre-orientation detectors measure the marks at the same time. The calculation is based on the pre-determined position difference and the Z-direction position difference of two adjacent marks in the predetermined upward direction. Therefore, this measurement is not affected by the workpiece stage (such as interferometer). ) The influence of drift and movement error of the workpiece table (such as the shape of the plane mirror of the interferometer) can greatly improve the measurement accuracy of the low-order aberration of the objective lens.

The aberration measuring device and method proposed by the present invention will be further described in detail below in conjunction with the drawings and specific embodiments. According to the following description and the scope of patent application, the advantages and characteristics of the present invention will be more clear. It should be noted that the drawings are in a very simplified form and all use imprecise proportions, which are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

Please refer to FIG. 1, which is a schematic diagram of the structure of an aberration measuring device according to an embodiment of the present invention. As shown in FIG. 1, the aberration measuring device includes: alignment lighting units and masks distributed sequentially from top to bottom in space A marking unit, a projection objective unit to be tested, and a mask aligning unit, the mask aligning unit including at least two identical X-direction and/or Y-direction detectors (that is, at least two identical X-direction detectors, Or at least two identical Y-directional detectors, or at least two identical X-directional detectors and at least two identical Y-directional detectors), the distance between two identical X- and/or Y-directional detectors is The first distance D (that is, the distance between a pair of adjacent X-direction detectors and/or the distance between a pair of adjacent Y-direction detectors is the first distance). When the aberration measuring device is in use, the mask marking unit is placed on a mask stage, the mask stage is arranged between the alignment illumination unit and the projection objective lens unit to be measured, and the mask alignment unit is placed on the workpiece stage on. The alignment lighting unit is used to provide a light source for the alignment of the mask, and the mask marking unit is used to obtain the position of the mark aerial image.

Wherein, the mask marking unit includes at least two X-direction and/or Y-direction marks (that is, at least two X-direction marks, or at least two Y-direction marks, or at least two X-direction marks and at least two Y-direction marks. Mark), the distance between the two X-direction and/or Y-direction marks is the second distance d (that is, the distance between a pair of adjacent X-direction marks and/or a pair of adjacent Y-direction marks The distance between is the second distance), the numerical ratio of the first distance to the second distance is m (the formula is expressed as m=D/d), and m is the objective lens magnification of the projection objective lens unit to be tested.

In this embodiment, the shape of the mask marking unit is the same as the shape of the mask alignment unit, specifically the shape of the mark in the mask marking unit is the same as the shape of the detector in the mask alignment unit, The size ratio of the mark to the detector is m, and m is the objective lens magnification of the projection objective lens unit to be tested.

Please refer to FIGS. 2a to 2d. FIG. 2a is a layout diagram of the mask alignment unit in an embodiment of the present invention including a combination of detectors for measuring X-to-V line distortion and field curvature of the objective field of view; FIG. 2b is the present invention In an embodiment of the present invention, the mask alignment unit includes a layout diagram of a detector used to measure line distortion and field curvature of the field of view X to H of the objective lens; FIG. 2c is a layout diagram of the mask alignment unit in an embodiment of the present invention. The layout of the detector combination for measuring the Y-to-V line distortion and field curvature of the objective field of view; Figure 2d is an embodiment of the present invention. The mask alignment unit includes the Y-to-H line distortion and field for measuring the objective field of view. The layout of the song’s detectors. The mask alignment unit in this embodiment includes four detector combinations, and each detector combination includes two identical X-direction or Y-direction detectors. Preferably, the detectors can be grating measurement sensors; The four detector combinations include detector combination 1, detector combination 2, detector combination 3, and detector combination 4; among them, detector combination 1 (shown as a rectangle in Figure 2a) is used to measure the X direction of the objective field of view V line (vertical line) distortion and field curvature; detector combination 2 (shown by triangles in Figure 2b) is used to measure the X-direction H line (horizontal line) distortion and field curvature of the objective field of view; detector combination 3 (as shown in the figure) 2c is used to measure the Y-to-V line distortion and field curvature of the objective field of view; the detector combination 4 (shown as a triangle in Figure 2d) is used to measure the Y-to-H line distortion and field curvature of the objective field of view. In this embodiment, the detector is preferably a grating measurement sensor. As shown in FIG. 2a, the detector combination 1 is composed of two identical X-direction grating measurement sensors GXX1 and a grating measurement sensor GXX2. The distance between the grating measurement sensor GXX1 and the grating measurement sensor GXX2 in the X direction is D (here the distance between the center of the grating measurement sensor GXX1 and the grating measurement sensor GXX2 in the X direction is D); as shown in Figure 2b As shown, the detector combination 2 is composed of two identical Y-direction grating measurement sensors GXY1 and GXY2. The X-direction distance between the grating measurement sensors GXY1 and GXY2 is D (that is, the X distance of the grating measurement sensors GXY1 and GXY2). As shown in Figure 2c, the detector assembly 3 consists of two identical X-direction grating measurement sensors GYX1 and GYX2. The Y-direction distance between the grating measurement sensors GYX1 and GYX2 is D (That is, the distance between the center of the grating measurement sensor GYX1 and GYX2 in the Y direction is D); as shown in Figure 2d, the detector assembly 4 consists of two identical Y-direction grating measurement sensors GYY1 and GYY2, and the grating measurement The distance between the sensors GYY1 and GYY2 in the Y direction is D (that is, the distance between the centers of the grating measurement sensors GYY1 and GYY2 in the Y direction is D).

Please refer to FIGS. 3a to 3d. FIG. 3a is a layout diagram of a mark combination 1 included in a mask marking unit in an embodiment of the present invention; FIG. 3b is a layout of a mark combination 2 included in a mask mark unit in an embodiment of the present invention Figure 3c is a layout diagram of the mark combination 3 included in the mask marking unit in an embodiment of the present invention; Figure 3d is a layout diagram of the mark combination 4 included in the mask marking unit in an embodiment of the present invention. In this embodiment, the mask mark unit contains four mark combinations, and each mark combination corresponds to a set of detector combinations (the shape of the mark in the mark combination is exactly the same as the shape of the detector in the detector combination, and the size ratio of the two is m, m is the magnification of the objective lens). Preferably, when the detector is a grating measurement sensor, the mark is a grating. The four mark combinations include mark combination 1, mark combination 2, mark combination 3, and mark combination 4; where the detector is a grating measurement sensor and the mark is a grating as an example, as shown in Figure 3a, mark combination 1 It is composed of a group of X-direction gratings GX with the same shape as the X-direction grating measurement sensor GXX1 (or GXX2), and its size is m times (m is the objective lens magnification). The X-direction distance between every two gratings is d ( That is, the distance between the centers of two adjacent gratings in the X direction is d), and the total length of the mark combination 1 in the X direction is l; as shown in Figure 3b, the mark combination 2 is composed of a group and the Y-direction grating measurement sensor GXY1 (or GXY2). ) It is composed of Y-direction grating GY with exactly the same shape and m times its size. The X-direction distance between every two gratings is d (that is, the distance between the centers of two adjacent gratings in the X-direction is d). Mark the X of combination 2 The total length is l; as shown in Figure 3c, the mark combination 3 is composed of a group of X-direction gratings GX whose shape is exactly the same as the X-direction grating measurement sensor GYX1 (or GYX2), and the size is m times that of the X-direction grating. The Y-direction distance between the two adjacent gratings is d (that is, the Y-direction center distance of two adjacent gratings is d), and the Y-direction total length of the mark combination 3 is k; as shown in Figure 3d, the mark combination 4 is composed of a group and the Y-direction grating The measuring sensor GYX1 (or GYX2) has exactly the same shape and is composed of a Y-direction grating GY whose size is m times. The Y-direction distance between every two gratings is d (that is, the Y-direction center distance of two adjacent gratings is d) The total Y-direction length of the mark combination 4 is k; the total X-direction length l of the mark combination 1 and the mark combination 2 is the same as the size of the objective field of view of the objective lens; the total Y-direction length of the mark combination 3 and the mark combination 4 is k Same size as the Y direction of the objective field of view.

In addition, the present invention is not limited to the shape of the mark in the mask marking unit and the detector in the mask alignment unit being the same, but also allows the mark in the mask marking unit to be aligned with the mask. The shapes of the detectors in the unit are different, as long as the detection end of the detector can cover the marking pattern to meet the detection requirements.

Correspondingly, this embodiment also provides a method for aberration measurement. The aberration measurement method of the present invention will be described in detail below with reference to FIGS. 1 to 5 and FIG. 10.

The aberration measurement method adopts the aberration measurement device described above, and specifically includes the following steps:

First, perform step S1, the mask marking unit is moved to the center position of the field of view of the projection objective lens unit to be tested;

Next, referring to Figure 5, perform step S2, the mask aligning unit measures all the marks of the mask mark unit in the predetermined direction and the Z position, and calculates the predetermined position difference between two adjacent marks in the predetermined direction And Z-direction position difference, the predetermined direction is X-direction and/or Y-direction;

Wherein, when the predetermined direction is the X-direction, the mask alignment unit includes two identical X-direction detectors, and the two same X-direction detectors simultaneously measure the predetermined upward marking of the mask marking unit. X-direction position and Z-direction position; when the predetermined direction is Y-direction, the mask alignment unit includes two identical Y-direction detectors, and two identical Y-direction detectors simultaneously measure the mask marking unit The Y position and Z position of the predetermined upward mark.

When the first distance D between the detectors is relatively large (for example, the first distance D is n times the second distance d), multiple measurement methods can be used. That is, start with the first mark on the leftmost (or rightmost), and measure a spline with the first distance D as the step (shown as the distance D of the mask alignment unit in the X direction under the movement of the workpiece table) Start with the second mark on the leftmost (or rightmost), and measure the second spline array with the first spacing D as the step; and so on to complete the measurement of all splines. As shown in Figure 5, the second distance d is 1/4 of the first distance D, and all the marks can be measured by dividing into 4 splines, and then after spline offset, spline difference and filtering, a set of Measurement results with dense measurement points.

Then, step S3 is executed to obtain the distortion and curvature of field of the objective lens with the predetermined V line or H line of the field of view according to the predetermined position difference and the Z position difference of all two adjacent marks in the predetermined direction.

In order to better understand the implementation process of step S3, take the predetermined direction as the X direction, and obtain the X-direction V line distortion sum of the objective lens according to the X-direction position difference and the Z-direction position difference of all two adjacent marks in the X direction The field music is explained in detail as an example, and the specific process is as follows:

S30: Calculate the X-direction distortion of the objective lens corresponding to the two adjacent marks based on the X-direction position difference of each pair of adjacent two marks in the X direction, and calculate the X-direction distortion of the objective lens of all two adjacent marks in the X direction Distortion to obtain the X-to-V line distortion of the objective lens field of view;

Among them, the formula for calculating the X-direction distortion of the objective lens corresponding to two adjacent marks based on the X-direction position difference of each pair of adjacent two marks is as follows: DT0=0; DT1=DT0+x1; DT2=DT1+x2; … DTn=DT(n-1)+xn;

In the formula, DT0 is the initial value of X-direction distortion, DT1 is the distortion of the first pair of adjacent two marks in X-direction, DT2 is the distortion of the second pair of adjacent two marks in X-direction, and DTn is the nth adjacent pair of X-direction Distortion of the two marks, n is a positive integer greater than 2; x1 is the difference between the first mark and the second mark in the X direction, x2 is the difference between the second mark and the third mark in the X direction, and xn is the nth mark The difference between the X position of the mark and the (n+1)th mark.

Then, the distortions (DT0, DT1, DT2...DTn) of all two adjacent marks in the X direction are arrayed, and the first-order quantity is removed, and the distortion appearance of the X-to-V line of the objective lens can be obtained.

S31: Calculate the field curvature of the objective lens corresponding to the two adjacent marks in the X direction based on the Z position difference of each pair of adjacent two marks in the X direction, and calculate the X direction of the objective lens field of view of all two adjacent marks according to the X direction The field curvature of the objective lens obtains the line field curvature of the objective field of view from X to V;

Among them, please refer to Figure 4, the formula for calculating the field curvature of the objective lens corresponding to the two adjacent marks based on the Z-direction position difference of each pair of adjacent marks in the X direction is as follows: FC0=0; FC1=FC0+z1; FC2=FC1+z2; … FCn=FC(n-1)+zn;

In the formula, FC0 is the initial value of field curvature in the X direction, FC1 is the field curvature of the first pair of adjacent two marks in the X direction, FC2 is the field curvature of the second pair of adjacent two marks in the X direction, and FCn is the nth field curvature in the X direction. For the field curvature of two adjacent marks, n is a positive integer greater than 2; z1 is the Z position difference between the first mark and the second mark, that is, z1=z2'-z1', z1' is the first mark Z position, z2' is the Z position of the second mark; z2 is the Z position difference between the second mark and the third mark, that is, z2=z3'-z2', z2' is the Z position of the second mark , Z3' is the Z position of the third mark; zn is the Z position difference between the nth mark and the (n+1)th mark.

Please continue to refer to Figure 4, the distance between FC0 and FC1 in the X direction is D; the distance between FC0 and FC1 in the Y direction is d1, and the distance between FC1 and FC2 in the Y direction is d2.

Then, the field curvatures (FC0, FC1, FC2...FCn) of all two adjacent marks in the X direction are arrayed, and the first-order quantity is removed to obtain the field curvature of the X-to-V line of the objective lens.

In the same way, the measurement and calculation methods for distortion and field curvature of the objective lens field of view X to H line, objective lens field of view Y to V line, and objective lens field of view Y to H line are similar to the above process, and will not be repeated.

Since at least two identical X- or Y-direction detectors in the mask alignment unit measure the position of space at the same time during the test, the difference between the measurement results of the two detectors is used in the calculation, so this test is not affected by the workpiece table (such as The influence of the drift of the interferometer and the movement error of the workpiece table (such as the shape of the plane mirror of the interferometer) can greatly improve the measurement accuracy. For the 28nm node lithography equipment, the above method is used for accuracy analysis and simulation. As shown in Figure 6, the distortion measurement error is less than 1nm; as shown in Figure 7, the field curvature measurement error is less than 7nm.

In another embodiment, the mask alignment unit shown may be a CCD-type mask alignment sensor. At this time, the layout of the CCD-type mask alignment sensor is shown in FIG. 8; correspondingly, the mask When the mask alignment unit is a CCD-type mask alignment sensor, the layout diagram of the mask marking unit is shown in FIG. 9. At this time, the specific measurement and calculation methods are the same as the previous embodiment.

The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.

As for the method disclosed in the embodiment, since it corresponds to the structure disclosed in the embodiment, the description is relatively simple, and the relevant parts can be referred to the description of the structure part.

In summary, in the aberration measurement device and method provided by the present invention, the aberration measurement method includes: moving the mask marking unit to the center of the field of view of the projection objective unit to be measured; and the mask alignment unit measures the mask The predetermined position and the Z position of all the marks in the predetermined upward direction of the mask marking unit, and the predetermined position difference and the Z position difference of the two adjacent marks in the predetermined upward direction are calculated, and the predetermined direction is the X direction and/or Y Direction; According to the predetermined direction position difference and the Z direction position difference of all two adjacent marks in the predetermined direction, the distortion and field curvature of the objective lens field of view in the predetermined direction V line or H line are obtained. During the measurement, two same pre-orientation detectors measure the marks at the same time. The calculation is based on the pre-determined position difference and the Z-direction position difference of two adjacent marks in the predetermined upward direction. Therefore, this measurement is not affected by the workpiece stage (such as interferometer). ) The influence of drift and movement error of the workpiece table (such as the shape of the plane mirror of the interferometer) can greatly improve the measurement accuracy of the objective lens low-order aberration.

The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention in any way. Any changes or modifications made by persons of ordinary skill in the field of the present invention based on the above disclosure shall fall within the protection scope of the patent application.

S1~S3‧‧‧Step

FIG. 1 is a schematic structural diagram of an aberration measuring device in an embodiment of the present invention; 2a is a layout diagram of a mask alignment unit including a combination of detectors for measuring X-to-V line distortion and field curvature of the objective lens in an embodiment of the present invention; 2b is a layout diagram of a mask alignment unit including a combination of detectors for measuring X-to-H line distortion and field curvature of the objective lens in an embodiment of the present invention; 2c is a layout diagram of a mask alignment unit including a combination of detectors for measuring Y-to-V line distortion and field curvature of the objective lens in an embodiment of the present invention; FIG. 2d is a layout diagram of the mask alignment unit in an embodiment of the present invention when a combination of detectors for measuring Y-to-H line distortion and field curvature of the objective field of view is included; Fig. 3a is a layout diagram of a mark combination 1 included in a mask mark unit in an embodiment of the present invention; 3b is a layout diagram of the mark combination 2 included in the mask mark unit in an embodiment of the present invention; Fig. 3c is a layout diagram of the mark combination 3 included in the mask mark unit in an embodiment of the present invention; FIG. 3d is a layout diagram of the mark combination 4 included in the mask mark unit in an embodiment of the present invention; 4 is a schematic diagram of field curvature measurement in an embodiment of the present invention; Figure 5 is a schematic diagram of multiple strip measurement in an embodiment of the present invention; 6 is a simulation diagram of distortion measurement accuracy in an embodiment of the present invention; Figure 7 is a simulation diagram of field curvature measurement accuracy in an embodiment of the present invention 8 is a layout diagram when the mask alignment unit is a CCD type mask alignment sensor in an embodiment of the present invention; 9 is a layout diagram of the mask marking unit when the mask alignment unit is a CCD-type mask alignment sensor in an embodiment of the present invention; FIG. 10 is a flowchart of a method of aberration measurement in an embodiment of the present invention.

S1~S3‧‧‧Step

Claims (13)

An aberration measuring device, which is characterized by comprising: an alignment lighting unit, a mask marking unit, and a mask aligning unit that are sequentially distributed from top to bottom along a space, wherein the mask marking unit is aligned with the mask A projection objective lens unit to be measured is arranged between the units, and the mask alignment unit includes at least two identical X-direction detectors and/or at least two identical Y-direction detectors to form a lens for measuring the objective lens. A combination of the distortion of the V line or the H line in the field X or Y direction and the field curvature detector. The aberration measuring device according to claim 1, wherein the distance between a pair of adjacent X-direction detectors and/or the distance between a pair of adjacent Y-direction detectors is the first distance; The mask marking unit includes at least two X-direction marks and/or at least two Y-direction marks, and the distance between a pair of adjacent X-direction marks and/or the distance between a pair of adjacent Y-direction marks is the second spacing. The aberration measuring device according to claim 2, wherein the numerical ratio of the first pitch to the second pitch is m, and m is the objective lens magnification of the projection objective lens unit to be tested. The aberration measuring device according to claim 2, wherein the size ratio between the mark in the mask marking unit and the detector in the mask alignment unit is m, and m is the objective lens magnification of the projection objective lens unit to be tested . A method for aberration measurement, using the aberration measurement device according to any one of claims 1 to 4, characterized in that it comprises the following steps: S1: the mask marking unit is moved to the center of the field of view of the projection objective lens unit to be tested Position; S2: Under the illumination of the aligning lighting unit, the mask aligning unit measures the predetermined position and Z position of all the marks of the mask mark unit in the predetermined direction, and calculates the predetermined direction of two adjacent marks in the predetermined direction The position difference value and the Z direction position difference value, the predetermined direction is the X direction and/or the Y direction; S3: Obtain the objective lens field of view according to the predetermined direction position difference value and the Z direction position difference value of all two adjacent marks in the predetermined direction The distortion and field curvature of the predetermined V line or H line. The method for aberration measurement according to claim 5, wherein when the predetermined direction is the X-direction, the mask alignment unit includes two identical X-direction detectors, and the two same X-direction detectors measure simultaneously The mask marking unit is at the X-direction position and the Z-direction position of the mark in a predetermined upward direction. The method for aberration measurement according to claim 5, wherein when the predetermined direction is the Y direction, the mask alignment unit includes two identical Y-direction detectors, and the two same Y-direction detectors measure simultaneously The mask marking unit is at the Y-direction position and the Z-direction position of the predetermined upward marking. The method for aberration measurement according to claim 5, wherein in step S3, the distortion of the V line of the objective field of view in the predetermined direction is obtained according to the predetermined position difference and the Z position difference of all two adjacent marks in the predetermined direction Including: Calculate the distortion of the field of view of the objective lens corresponding to the two adjacent marks based on the predetermined position difference of each pair of adjacent two marks, according to the predetermined direction of the objective field of all two adjacent marks The distortion obtains the predetermined V-line distortion of the objective field of view. The method for aberration measurement according to claim 8, wherein when the predetermined direction is the X direction, the objective lens corresponding to the two adjacent marks is calculated based on the predetermined position difference of each pair of adjacent two marks in the predetermined direction The formula for the distortion of the field of view is as follows: DT0=0; DT1=DT0+x1; DT2=DT1+x2; . . DTn=DT(n-1)+xn; where DT0 is the initial value of X-direction distortion, DT1 is the distortion of the first pair of adjacent two marks in X direction, and DT2 is the distortion of the second pair of adjacent two marks in X direction , DTn is the distortion of the nth pair of adjacent marks in the X direction, n is a positive integer greater than 2; x1 is the X-direction difference between the first mark and the second mark, x2 Is the X-direction difference between the second mark and the third mark, and xn is the X-direction difference between the nth mark and the (n+1)th mark. The method of aberration measurement according to claim 8, wherein obtaining the line distortion of the objective field of view in X direction V according to the distortion of the field of view of all marked objectives in X direction includes: distorting arrays of all two adjacent marks in X direction And remove the first-order quantity. The method for aberration measurement according to claim 5, wherein in step S3, the field of the objective lens field of view is obtained in the predetermined direction V line according to the predetermined position difference and the Z position difference of all two adjacent marks in the predetermined direction The curve includes: calculating the predetermined field curvature of the field of view of the objective lens corresponding to the two adjacent marks based on the Z-direction position difference of each pair of adjacent two marks in the predetermined direction. The field curvature of the objective lens obtains the field curvature of the predetermined V line of the objective lens. The method for aberration measurement according to claim 11, wherein when the predetermined direction is the X direction, the objective lens corresponding to the two adjacent marks is calculated based on the Z-direction position difference of each pair of adjacent two marks in the predetermined direction The formula of the field curvature of the field of view is as follows: FC0=0; FC1=FC0+z1; FC2=FC1+z2; . . FCn=FC(n-1)+zn; where FC0 is the initial value of X-direction curvature of field, FC1 is the field curvature of the first pair of adjacent two marks in X direction, and FC2 is the second pair of adjacent two marks in X direction FCn is the field curvature of the n-th pair of adjacent marks in the X direction, n is a positive integer greater than 2; z1 is the Z position difference between the first mark and the second mark, and z2 is the second mark and The Z position difference of the third mark, zn is the Z position difference of the nth mark and the (n+1)th mark. The method for aberration measurement according to claim 11, wherein obtaining the line curvature of the field of view of the objective lens in the X direction V according to the field curvature of the field of view of all the marked objectives in the X direction includes: The field curvature is grouped and the first-order quantity is removed.

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