CN107024185B - Method and device for measuring basal surface - Google Patents
Method and device for measuring basal surface Download PDFInfo
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- CN107024185B CN107024185B CN201610069182.7A CN201610069182A CN107024185B CN 107024185 B CN107024185 B CN 107024185B CN 201610069182 A CN201610069182 A CN 201610069182A CN 107024185 B CN107024185 B CN 107024185B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
- G01B11/00—Measuring arrangements characterised by the use of optical techniques
- G01B11/24—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures
- G01B11/2441—Measuring arrangements characterised by the use of optical techniques for measuring contours or curvatures using interferometry
Abstract
The invention relates to a method and a device for measuring basal profile, wherein the method comprises the following steps of S1: uploading a substrate to a substrate table, measuring the position of the substrate table through a substrate table position measuring device to obtain a substrate table position value, starting a focusing and leveling system, and enabling an mxn light spot matrix to be incident on the substrate, wherein the column pitch of the light spot matrix is d1, the row pitch is d2, n is more than or equal to 3, and m is more than or equal to 3; s2: planning a scanning path on a substrate, moving a substrate table, enabling a spot matrix to move relative to the substrate table along the scanning path, and recording a substrate position value measured by each sub-spot in the spot matrix during each movement, wherein the step length of the movement of the spot matrix in the X direction is d1, and the step length of the movement of the spot matrix in the Y direction is d 2; s3: and (5) finishing all the substrate position values measured by the sub light spots in the step S2, correcting the substrate position values according to the substrate position values and the substrate table position values, and finally calculating the surface type of the substrate according to the corrected substrate position values. Thereby eliminating measurement changes caused by substrate table height and tilt attitude.
Description
Technical Field
The invention relates to the technical field of projection lithography, in particular to a method and a device for measuring a basal plane.
Background
Projection lithography has been widely used in integrated circuit fabrication processes by transferring a designed mask pattern onto a photoresist by exposure through an optical projection device. One emerging vertical control method in lithography machines is the measurement of substrate profile, namely: the base surface type is obtained through the pre-measurement of the focusing and leveling system, and the vertical set value of the base platform of each exposure field is calculated according to the surface type value, so that the exposure field on the base is always within the focal depth of the objective lens system of the photoetching machine, and the pattern on the mask plate is ideally transferred to the base.
With the increasing resolution and decreasing depth of focus of projection lithography machines, the requirement for the vertical control accuracy of the lithography machines is increasing, and the requirement for the measurement accuracy of the substrate surface type is also increasing. At present, a high-precision projection photoetching machine system adopts a method that a substrate table bears the motion of a substrate, and simultaneously, measured values of a substrate table vertical sensor and a focusing and leveling system are recorded to obtain substrate surface type information, but because a reference surface (the upper surface of marble or the surface of an interferometer plane mirror) of the substrate table vertical sensor has processing and manufacturing errors and installation errors, the measured substrate surface type contains the errors, the vertical control precision is influenced, and finally an exposure field is out of focus.
For example, chinese patent publication No. CN101105389A discloses a non-contact three-dimensional surface type measuring device, in which a table top moves in an X direction on a base, and a Z-direction movement unit moves in a Y direction and a Z direction on a gantry. The laser measuring sensor fixed on the Z-direction moving unit is used for measuring the measured object on the working table, but certain errors exist in the flatness of the base and the gantry, the errors can directly influence the surface type of the measured object, and the measuring precision is not high; and a single laser measurement sensor is adopted, so that the measurement efficiency is low.
Therefore, it is an urgent technical problem to be solved by those skilled in the art to provide a method and a device for measuring a footprint with higher measurement accuracy and faster measurement speed.
Disclosure of Invention
The invention provides a measuring method and a measuring device for a basal plane, which aim to solve the technical problems.
In order to solve the above technical problem, the present invention provides a method for measuring a basal plane, comprising:
s1: uploading a substrate to a substrate table, measuring the position of the substrate table through a substrate table position measuring device to obtain a substrate table position value, starting a focusing and leveling system, and enabling an mxn light spot matrix to be incident on the substrate, wherein the column pitch of the light spot matrix is d1, the row pitch is d2, n is more than or equal to 3, and m is more than or equal to 3;
s2: planning a scanning path on the substrate, moving the substrate table, moving the spot matrix relative to the substrate table along the scanning path, and recording a substrate position value measured by each sub-spot in the spot matrix at each movement, wherein the step length of the movement of the spot matrix in the X direction is d1, and the step length of the movement of the spot matrix in the Y direction is d 2;
s3: and (5) finishing all the substrate position values measured by the sub-light spots in the step (S2), correcting the substrate position values according to the substrate position values and the substrate table position values, and finally calculating the surface type of the substrate according to the corrected substrate position values.
Preferably, the step S3 includes the following steps:
s31: when the light spot matrix moves along the scanning path relative to the substrate table, the position measured by each sub light spot is called a measuring point, the substrate position values of the sub light spots at the measuring points are arranged, then the measuring points at the central position or the position close to the central position on the substrate are taken as reference points, the m multiplied by n measuring points with the reference points as central points or the position close to the central points are taken as calculation matrixes, and the substrate position values of the measuring points are fitted into a datum plane;
s32: calculating the height of each measuring point in the reference surface and the calculation matrix relative to the reference surface according to the base position value of the measuring point covered by the calculation matrix and the position value of the base table, and converting the calculation result into a base coordinate system to obtain the position parameters of the measuring point in the base coordinate system;
s33: moving the calculation matrix in the positive Y-axis direction by a step length d1, wherein the measurement points covered by the current calculation matrix and the repeated points in the measurement points covered by the previous calculation matrix are called known points, the unrepeated points are called unknown points, and the base position values of the known points in the current calculation matrix are corrected by using the heights of the reference surfaces corresponding to the known points in the previous calculation matrix;
s34: fitting the corrected base position value of the known point to a new datum plane, calculating the height of the unknown point relative to the new datum plane, and converting the calculation result to obtain the position parameter of the unknown point in the base coordinate system;
s35: returning to the step S33, correcting the substrate position values of all the measurement points in the positive Y-axis direction to obtain position parameters of all the measurement points in the positive Y-axis direction in the substrate coordinate system;
s36: the calculation matrix moves along the Y-axis negative direction, the positive direction parallel to the X-axis and the negative direction parallel to the X-axis respectively, the substrate position values of all the measurement points are corrected according to the method of the steps S33 to S35, and the position parameters of the measurement points under the substrate coordinate system are obtained, wherein the step length of the movement of the calculation matrix along the direction parallel to the X-axis is d 2;
s37: and drawing the surface shape of the substrate by using the position parameters of all the measuring points under the substrate coordinate system.
Preferably, step S32 includes the following steps:
s321: base level values (Spot) of the measurement points covered by the calculation matrixij_x、SpotijY), and a base height value FLS _ ZijAnd a substrate table height value Z _ WS, calculating a height value Z _ ref and a tilt value (Rx _ ref, Ry _ ref) of the reference plane, wherein i is 0,1, …, m, j is 0,1, …, n:
s322: calculating the height Spot of each measuring point in the calculation matrix relative to the reference surfaceij_d0；
S323: converting the calculation result into the base coordinate system to obtain the base parameters of all the measurement points covered by the calculation matrix in the base coordinate system:
wherein (x)S，yS) Represents the horizontal parameter of the S-th measuring point on the substrate in the substrate coordinate system, zSAnd the height parameter of the S-th measuring point in the base coordinate system is represented.
Preferably, in step S33, the base position value of the known point in the current calculation matrix is corrected by using the height of the reference plane corresponding to the known point in the previous calculation matrix as:
wherein:
FLS_Zl,kthe base height value of a measurement point of the ith row and the kth column in the current calculation matrix is obtained;
FLS_Zl,kthe corrected base height value of the measurement point of the ith row and the kth column in the current calculation matrix is obtained;
Spotp,q_djumpand after the calculation matrix is stepped for the first jump along the positive direction of the Y axis, the height of a measurement point of the p row and the q column in the calculation matrix relative to the corresponding reference surface during the stepping for the first time.
Preferably, in step S34, the converting the calculation result to obtain the position parameter of the unknown point in the base coordinate system is performed by:
wherein (x)S，yS) Represents the horizontal parameter, z, of the S-th measuring point on the substrate in the substrate coordinate systemSRepresenting the height parameter of the Sth measuring point on the substrate under a substrate coordinate system; (X _ WS, Y _ WS) are substrate table level values of the substrate table.
Preferably, the scanning path is: two adjacent columns are connected end to end in sequence to form a snake-shaped path.
The invention also provides a device for realizing the method for measuring the basal plane, which comprises a basal table, a basal fixed on the basal table, an interferometer component used for measuring the position of the basal table, a focusing and leveling system and a data processing unit, wherein the focusing and leveling system enables a light spot matrix of m multiplied by n to be incident on the basal table, n is more than or equal to 3, m is more than or equal to 3, the light spot matrix scans the surface of the basal table in a stepping way and obtains a plurality of basal plane position values of the basal table by measurement, the step length of the light spot matrix in the X direction is equal to the row distance of the matrix light spots, the step length of the light spot matrix in the Y direction is equal to the row distance of the light spot matrix, the data processing unit corrects the basal plane position values according to a plurality of basal plane position values measured by the light spot matrix and the basal table position values measured by the interferometer component, and finally, calculating the surface type of the substrate according to the corrected position value of the substrate.
Preferably, the interferometer assembly comprises a Z-direction interferometer, an X-direction mirror, a Y-direction mirror, a 45 ° mirror and a Z-direction long mirror, the X-direction mirror and the Y-direction mirror are respectively attached to two adjacent side elevation surfaces of the substrate table, the 45 ° mirror is arranged at the bottom of the X-direction mirror, the Z-direction long mirror is arranged above the substrate table, and reference light emitted by the Z-direction interferometer perpendicularly enters the X-direction mirror and the Y-direction mirror and enters the Z-direction interferometer after being reflected; and the measuring light emitted by the Z-direction interferometer enters the 45-degree mirror, is deflected by 90 degrees and then enters the Z-direction long strip mirror, and finally returns to the Z-direction interferometer along the original path.
Preferably, the substrate is fixed to the substrate table by a suction cup.
The invention also provides another device for realizing the method for measuring the basal surface, which comprises a basal table, a basal fixed on the basal table, a grating ruler component used for measuring the position of the basal table, a focusing and leveling system and a data processing unit, wherein the focusing and leveling system enables an m multiplied by n light spot matrix to be incident on the basal table, n is more than or equal to 3, m is more than or equal to 3, the light spot matrix performs stepping scanning on the surface of the basal table to obtain a plurality of basal position values of the basal table through measurement, the step length of the light spot matrix in the X direction is equal to the row distance of the light spot matrix, the step length of the light spot matrix in the Y direction is equal to the row distance of the light spot matrix, and the data processing unit obtains a plurality of basal position values measured by the light spot matrix and the basal table position value measured by the grating ruler component, and correcting the position value of the substrate, and finally calculating the surface type of the substrate according to the corrected position value of the substrate.
Compared with the prior art, the method and the device for measuring the basal profile provided by the invention comprise the following steps of S1: uploading a substrate to a substrate table, measuring the position of the substrate table through a substrate table position measuring device to obtain a substrate table position value, starting a focusing and leveling system, and enabling an mxn light spot matrix to be incident on the substrate, wherein the column pitch of the light spot matrix is d1, the row pitch is d2, n is more than or equal to 3, and m is more than or equal to 3; s2: planning a scanning path on a substrate, moving a substrate table, enabling a spot matrix to move relative to the substrate table along the scanning path, and recording a substrate position value measured by each sub-spot in the spot matrix during each movement, wherein the step length of the movement of the spot matrix in the X direction is d1, and the step length of the movement of the spot matrix in the Y direction is d 2; s3: and (5) finishing all the substrate position values measured by the sub-light spots in the step (S2), correcting the substrate position values according to the substrate position values and the substrate table position values, and finally calculating the surface type of the substrate according to the corrected substrate position values. Therefore, in two adjacent scanning measurements, at least 6 light spots are repeatedly measured on the substrate, the change of the measured value caused by the change of the height and the inclined posture of the substrate table can be eliminated according to the information of the two adjacent measurements, and accurate substrate surface type information is further obtained.
Drawings
FIG. 1 is a schematic structural diagram of a substrate-type measuring apparatus according to a first embodiment of the present invention;
FIG. 2 is a layout diagram of an interferometer according to one embodiment of the present invention;
FIG. 3 is a layout diagram of light spots according to a first embodiment of the present invention;
FIG. 4 is a schematic diagram of a measurement path according to a first embodiment of the present invention;
FIG. 5 is a schematic diagram of a measurement of a non-base profile with a lens profile according to an embodiment of the present invention;
FIG. 6 is a schematic diagram of a measurement process of a non-lens surface type with a substrate surface type according to an embodiment of the present invention;
FIG. 7 is a schematic diagram of a measurement with both lens and base profiles according to one embodiment of the present invention;
FIG. 8 is a schematic diagram of a calculation path according to a first embodiment of the present invention;
FIGS. 9a to 9d are schematic diagrams sequentially illustrating a calculation path during scanning along a positive Y-axis direction, a negative X-axis direction, and a negative X-axis direction according to an embodiment of the present invention;
FIG. 10 is a flowchart of a method for measuring a substrate profile according to an embodiment of the present invention;
fig. 11 is a schematic structural diagram of a substrate-type measuring apparatus according to a second embodiment of the present invention.
In the figure: the system comprises a 10-substrate table, a 20-substrate, a 31-Z interferometer, a 32-X square mirror, a 33-Y square mirror, a 34-45-degree mirror, a 35-Z long strip mirror, a 40-focusing and leveling system, a 50-grating ruler component and a 60-marble table.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It is to be noted that the drawings are in simplified form and are not to precise scale, which is provided for the purpose of facilitating and distinctly claiming the embodiments of the present invention.
Example one
The invention provides a substrate surface type measuring device, as shown in fig. 1 and fig. 2, comprising a substrate table 10, a substrate 20 fixed on the substrate table 10 (preferably, the substrate 20 is fixed on the substrate table 10 by a suction cup), an interferometer component for measuring the position of the substrate table 10, a focusing and leveling system 40 and a data processing unit (not shown), wherein the focusing and leveling system 40 makes m × n light spot matrixes incident on the substrate 20, wherein n is greater than or equal to 3, m is greater than or equal to 3, the light spot matrixes scan the surface of the substrate 20 in a stepping manner, substrate position values of a plurality of substrates 20 are obtained by measurement, the step length of the light spot matrixes in the X direction is equal to the column pitch of the light spot matrixes, the step length of the light spot matrixes in the Y direction is equal to the row pitch of the light spot matrixes, the data processing unit obtains a plurality of substrate position values measured by the light spot matrixes and a substrate table position value measured by the interferometer component, and correcting the substrate position value, and finally calculating the surface type of the substrate 20 according to the corrected substrate position value.
Preferably, with continued reference to fig. 1 and fig. 2, the interferometer assembly includes a Z-direction interferometer 31, an X-direction mirror 32, a Y-direction mirror 33, a 45 ° mirror 34, and a Z-direction long mirror 35, the X-direction mirror 32 and the Y-direction mirror 33 are respectively attached to two adjacent side elevation surfaces of the substrate table 10, the 45 ° mirror 34 is disposed at the bottom of the X-direction mirror 32, the Z-direction long mirror 35 is disposed above the substrate table 10, and the reference light emitted from the Z-direction interferometer 31 is vertically incident to the X-direction mirror 32 and the Y-direction mirror 33 and then incident to the Z-direction interferometer 31; the measurement light emitted from the Z-direction interferometer 31 enters the 45 ° mirror 34, is deflected by 90 °, enters the Z-direction long mirror 35, and finally returns to the Z-direction interferometer 31 along the original path.
Referring to fig. 2, when the substrate stage 10 moves in the X direction, the measurement light from the Z-interferometer 31 is incident on different positions of the Z-elongated mirror 35, and thus the surface shape of the Z-elongated mirror 35 affects the measurement value of the Z-interferometer 31, which is called XTZ; meanwhile, the surface shape of the Y-square mirror 33 can also influence the measurement value of Rx, which is called XRX; similarly, when the substrate stage 10 moves in the Y direction, the measurement light of the Z-direction interferometer 31 may be incident on different positions of the 45 ° mirror 34, and the reference light may be incident on different positions of the X-direction mirror 32, so that the surface shapes of the 45 ° mirror 34 and the X-direction mirror 32 may also affect the measurement value of the Z-direction interferometer 31, which is referred to as YTZ; at the same time the surface shape of the X-cube 32 also influences the measured value of Ry, and the measured values are called YRY, XTZ, YTZ, XRX and YRY, which characterize the influence of the substrate table 10 on the vertical three degrees of freedom Z, Rx and Ry when moving in the XY direction. In order to obtain a more accurate measurement result of the substrate surface shape, it is necessary to remove the influence of XTZ, YTZ, XRX and YRY on the surface shape from the actual measurement values, but it is generally difficult to accurately measure the true values of XTZ, YTZ, XRX and YRY due to the measurement conditions.
In this embodiment, taking 9 sub-spots formed by the focusing and leveling system 40 incident on the upper surface of the substrate 20 as an example, that is, n is 3, m is 3, a spot layout diagram of the focusing and leveling system 40 is shown in fig. 3, a distance between two adjacent sub-spots in the X direction is d1, a distance between two adjacent sub-spots in the Y direction is d2, the substrate stage 10 can move in six degrees of freedom during measurement, and the measurement points are distributed over the entire substrate 20 by a path planning method shown in fig. 4, where the X-direction step distance is d1 and the Y-direction step distance is d 2. X, Y, Z measurements (X _ WS, Y _ WS) of the substrate table 10 are recorded at each measurement point,Z _ WS) and the measurement values of 9 sub-spots in the focus-leveling system 40 (FLS _ Z)1、FLS_Z2……FLS_Z9)。
The above-described spot layout can satisfy the requirement that 6 spots on the substrate 20 are repeatedly measured in two adjacent measurements. In both measurements, the base profile is invariant, and the cause of the change in the measured value is the lens profile of the Z-direction interferometer 31. Fig. 5 is a simplified schematic diagram of the measurement of the non-substrate surface type with the lens surface type, as shown in the figure, when the substrate 20 moves in the X direction or the Y direction, although the posture of the substrate 20 is different, the measurement points (M1, M2, M3 or M1 ', M2 ', M3 ') on the substrate 20 are always on a straight line (l1 or l 2); FIG. 6 is a simplified schematic diagram of the measurement of the basal surface type without lens surface type, as shown in the figure, the distance of M3 from the line l1 is equal to the distance of M3 ' from the line l2, and does not change with the horizontal position of the substrate table 10, and so on, the height of all points on the substrate 20 relative to the reference line connecting the measurement points M1(M1 ') and M2(M2 ') is constant, and this part is basal surface type, that is, the height of the same point on the three sub-spot measurement substrate 20 is constant without lens surface type; FIG. 7 is a simplified schematic diagram of the measurement of both the substrate surface type and the lens surface type, and as shown in the figure, when the substrate table 10 moves, the measured values of the same points M2 and M2 'and M3 and M3' on the substrate 20 are not equal, and it can be judged that this is caused by the change of the height and tilt posture of the substrate table 10 in conjunction with the conclusions of FIGS. 5 and 6, and the change of the measured values caused by the change of the height and tilt posture of the substrate table 10 can be eliminated by the following calculation:
1. calculating the height and inclination of the first measurement reference line l1 according to the measurement values of M1 and M2, and because M1 and M2 are reference points, the distance d1 of M1 to l1 and the distance d2 of M2 to l1 satisfy: d1 ═ d2 ═ 0;
2. calculating the distance d3 from the M3 to the first measurement reference line l 1;
3. correcting M2 'and M3' obtained in the second measurement by using d2 and d3 according to a correction method of M2 ═ M2 '-d 2 and M3 ═ M3' -d 3;
4. fitting the reference line l2 with the corrected M2 'and M3', wherein the change amount of l2 relative to l1 is the change amount of the attitude of the substrate table 10 of the second measuring point relative to the first measuring point;
5. finding the distance d4 of M4' relative to a reference line l 2;
d1, d2, d3 and d4 are base surface types.
From the above analysis, it can be seen that the core idea of the present application is: the height of each point on the substrate 20 is determined relative to a reference plane, which is an ideal plane (fitting plane) of a measurement point on the substrate 20 within the spot coverage of the focus and leveling system 40. The derived path shown in fig. 8 selects the reference point at the center of the substrate 20, and uses the fitting plane of the measurement values of the 9 sub-light spots of the focusing and leveling system 40 at the center of the substrate 20 as the reference plane of the whole substrate 20.
Referring to fig. 10, the present invention provides a method for measuring a basal profile, comprising:
s1: uploading a substrate 20 onto a substrate table 10, measuring the position of the substrate table 10 through a substrate table 10 position measuring device to obtain a substrate table position value, starting a focusing and leveling system 40, and enabling an m × n light spot matrix to be incident on the substrate 20, wherein the row spacing of the light spot matrix is d1, the row spacing is d2, n is more than or equal to 3, and m is more than or equal to 3;
s2: a scanning path is planned on the substrate 20, and in this embodiment, the scanning path is: moving the substrate table 10 along a serpentine path formed by two adjacent columns of consecutive heads and tails, so that the spot matrix moves along the scanning path relative to the substrate table 10, and recording a substrate position value measured by each sub-spot in the spot matrix during each movement, wherein the step length of the movement of the spot matrix in the X direction is d1, and the step length of the movement of the spot matrix in the Y direction is d 2;
s3: and (5) finishing all the substrate position values measured by the sub-light spots in the step (S2), correcting the substrate position values according to the substrate position values and the substrate table position values, and finally calculating the surface type of the substrate 20 according to the corrected substrate position values.
Preferably, the step S3 specifically includes the following steps:
s31: when the light spot matrix moves along the scanning path relative to the substrate table, the position measured by each sub light spot is called a measuring point, all measuring points are formed into an s × t measuring matrix, the substrate position values of the sub light spots at the measuring points are arranged, the measuring point at the central position or the position close to the central position on the substrate 20 is taken as a reference point, the measuring point at m × n with the reference point as the central point or the position close to the central point is taken as a calculation matrix, and the substrate position values of the measuring points are fitted into a datum plane;
s32: calculating the height of each measuring point in the reference surface and the calculation matrix relative to the reference surface according to the base position value of the measuring point covered by the calculation matrix and the position value of the base table, and converting the calculation result into a base coordinate system to obtain the position parameters of the measuring point in the base coordinate system;
preferably, step S32 specifically includes the following steps:
s321: base level values (Spot) of the measurement points covered by the calculation matrixij_x、SpotijY), and a base height value FLS _ ZijAnd a substrate table height value Z _ WS, calculating a height value Z _ ref and a tilt value (Rx _ ref, Ry _ ref) of the reference plane, wherein i is 0,1, …, m, j is 0,1, …, n:
s322: calculating the height Spot of each measuring point in the calculation matrix relative to the reference surfaceij_d0；
S323: converting the calculation result into the base coordinate system to obtain the base parameters of all the measurement points covered by the calculation matrix in the base coordinate system:
wherein (x)S，yS) Represents the horizontal parameter, z, of the S-th measurement point on the substrate 20 in the substrate coordinate systemSAnd the height parameter of the S-th measuring point in the base coordinate system is represented.
S33: moving the calculation matrix in the positive Y-axis direction (as shown in FIG. 9 a) by a step d1, designating the measurement points covered by the current calculation matrix and the repeated points in the measurement points covered by the previous calculation matrix as known points, and designating the unrepeated points as unknown points, and correcting the base position values of the known points in the current calculation matrix by using the heights of the reference surfaces corresponding to the known points in the previous calculation matrix;
preferably, in the step S33, the step of correcting the base position value of the known point in the current calculation matrix by using the height of the reference plane corresponding to the known point in the previous calculation matrix is specifically:
wherein:
FLS_Zl,kthe base height value of a measurement point of the ith row and the kth column in the current calculation matrix is obtained;
FLS_Zl,kthe corrected base height value of the measurement point of the ith row and the kth column in the current calculation matrix is obtained;
Spotp,q_djumpand after the calculation matrix is stepped for the first jump along the positive direction of the Y axis, the height of a measurement point of the p row and the q column in the calculation matrix relative to the corresponding reference surface during the stepping for the first time.
S34: fitting the corrected base position value of the known point to a new datum plane, calculating the height of the unknown point relative to the new datum plane, and converting the calculation result to obtain the position parameter of the unknown point in the base coordinate system;
preferably, in step S34, the converting the calculation result to obtain the position parameter of the unknown point in the base coordinate system includes the following steps:
wherein (x)S，yS) Represents the horizontal parameter, z, of the S-th measuring point on the substrate in the substrate coordinate systemSA height parameter representing the height of the S-th measuring point on the substrate 20 in a substrate coordinate system; (X _ WS, Y _ WS) are substrate table level values of the substrate table 10.
S35: returning to step S33, correcting the base position values of all the measurement points in the positive Y-axis direction (as shown in fig. 9 a) to obtain position parameters of all the measurement points in the positive Y-axis direction in the base coordinate system;
s36: the calculation matrix moves along the Y-axis negative direction (figure 9b), the positive direction (figure 9d) parallel to the X-axis, and the negative direction (figure 9c) parallel to the X-axis respectively, and the base position values of all the measurement points are corrected according to the method of the steps S33 to S35 to obtain the position parameters of the measurement points under the base coordinate system, wherein the step length of the movement of the calculation matrix along the direction parallel to the X-axis is d 2;
s37: and drawing the surface shape of the substrate 20 by using the position parameters of all the measuring points in the substrate coordinate system.
By adopting the method for measuring the substrate surface shape, no matter the light spot matrix moves along the X direction or the Y direction during measurement, at least 6 sub light spots on the substrate 20 are repeatedly measured in two adjacent scanning measurements, and the change of the measured value caused by the change of the height and the inclined posture of the substrate table 10 can be eliminated according to the information of the two previous and next measurements, so that the accurate substrate 20 surface shape information can be obtained.
Example two
Referring to fig. 11, the difference between the first embodiment and the second embodiment is: in this embodiment, a grating scale assembly 50 is used to control the substrate table 10 to move, and specifically, another substrate surface type measuring apparatus for implementing the substrate surface type measuring method provided in this embodiment includes a substrate table 10, a substrate 20 fixed on the substrate table 10, a grating scale assembly 50 for measuring the position of the substrate table 10, a focusing and leveling system 40, and a data processing unit, where the focusing and leveling system 40 irradiates an mxn light spot matrix onto the substrate 20, where n is greater than or equal to 3, m is greater than or equal to 3, the light spot matrix performs step scanning on the surface of the substrate 20 to obtain a plurality of substrate position values of the substrate 20 through measurement, where a step length of the light spot matrix in an X direction is equal to a column pitch of the light spot matrix, a step length in a Y direction is equal to a row pitch of the light spot matrix, and the data processing unit obtains the plurality of substrate position values measured by the light spot matrix and the substrate position values measured by the grating scale assembly 50 A base position value, correcting the base position value, and finally calculating the surface type of the base 20 according to the corrected base position value.
In the present embodiment, the upper surface of the marble table 60 is not an ideal plane due to manufacturing errors in the process, and in such a case, a large error must be introduced in measuring the surface profile of the substrate. By adopting the structure and the method, the test error caused by the uneven surface of the marble table 60 can be eliminated, and the test precision is improved.
In summary, the present invention provides a method and an apparatus for measuring a footprint, the method comprising: s1: uploading a substrate 20 onto a substrate table 10, measuring the position of the substrate table 10 through a substrate table position measuring device to obtain a substrate table position value, starting a focusing and leveling system 40, and enabling an m × n light spot matrix to be incident on the substrate 20, wherein the column pitch of the light spot matrix is d1, the row pitch is d2, n is more than or equal to 3, and m is more than or equal to 3; s2: planning a scan path on the substrate 20, moving the substrate table 10, moving the matrix of spots along the scan path relative to the substrate table 10, and recording the measured substrate position value for each sub-spot in the matrix of spots for each movement, wherein the matrix of spots is moved in the X-direction by a step size d1 and in the Y-direction by a step size d 2; s3: and (5) finishing all the substrate position values measured by the sub-light spots in the step (S2), correcting the substrate position values according to the substrate position values and the substrate table position values, and finally calculating the surface type of the substrate 20 according to the corrected substrate position values. Therefore, in two adjacent scanning measurements, at least 6 sub light spots on the substrate 20 are repeatedly measured, and the change of the measured value caused by the change of the height and the inclined posture of the substrate table 10 can be eliminated according to the information of the two previous and next measurements, so that accurate substrate surface type information is obtained.
It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.
Claims (10)
1. A method of determining a profile of a substrate, comprising:
s1: uploading a substrate to a substrate table, measuring the position of the substrate table through a substrate table position measuring device to obtain a substrate table position value, starting a focusing and leveling system, and enabling an mxn light spot matrix to be incident on the substrate, wherein the column pitch of the light spot matrix is d1, the row pitch is d2, n is more than or equal to 3, and m is more than or equal to 3;
s2: planning a scanning path on the substrate, moving the substrate table, moving the spot matrix relative to the substrate table along the scanning path, and recording a substrate position value measured by each sub-spot in the spot matrix at each movement, wherein the step length of the movement of the spot matrix in the X direction is d1, and the step length of the movement of the spot matrix in the Y direction is d 2;
s3: and (5) finishing all the substrate position values measured by the sub-light spots in the step (S2), correcting the substrate position values according to the substrate position values and the substrate table position values, and finally calculating the surface type of the substrate according to the corrected substrate position values.
2. The footprint measurement method of claim 1, wherein said step S3 comprises the steps of:
s31: when the light spot matrix moves along the scanning path relative to the substrate table, the position measured by each sub light spot is called a measuring point, the substrate position values of the sub light spots at the measuring points are arranged, then the measuring points at the central position or the position close to the central position on the substrate are taken as reference points, the m multiplied by n measuring points with the reference points as central points or the position close to the central points are taken as calculation matrixes, and the substrate position values of the measuring points are fitted into a datum plane;
s32: calculating the height of each measuring point in the reference surface and the calculation matrix relative to the reference surface according to the base position value of the measuring point covered by the calculation matrix and the position value of the base table, and converting the calculation result into a base coordinate system to obtain the position parameters of the measuring point in the base coordinate system;
s33: moving the calculation matrix in the positive Y-axis direction by a step length d1, wherein the measurement points covered by the current calculation matrix and the repeated points in the measurement points covered by the previous calculation matrix are called known points, the unrepeated points are called unknown points, and the base position values of the known points in the current calculation matrix are corrected by using the heights of the reference surfaces corresponding to the known points in the previous calculation matrix;
s34: fitting the corrected base position value of the known point to a new datum plane, calculating the height of the unknown point relative to the new datum plane, and converting the calculation result to obtain the position parameter of the unknown point in the base coordinate system;
s35: returning to the step S33, correcting the substrate position values of all the measurement points in the positive Y-axis direction to obtain position parameters of all the measurement points in the positive Y-axis direction in the substrate coordinate system;
s36: the calculation matrix moves along the Y-axis negative direction, the positive direction parallel to the X-axis and the negative direction parallel to the X-axis respectively, the substrate position values of all the measurement points are corrected according to the method of the steps S33 to S35, and the position parameters of the measurement points under the substrate coordinate system are obtained, wherein the step length of the movement of the calculation matrix along the direction parallel to the X-axis is d 2;
s37: and drawing the surface shape of the substrate by using the position parameters of all the measuring points under the substrate coordinate system.
3. The footprint measurement method of claim 2, wherein step S32 comprises the steps of:
s321: base level values (Spot) of the measurement points covered by the calculation matrixij_x、SpotijY), and a base height value FLS _ ZijAnd a substrate table height value Z _ WS, calculating a height value Z _ ref and a tilt value (Rx _ ref, Ry _ ref) of the reference plane, wherein i is 0,1, …, m, j is 0,1, …, n:
s322: calculating the height Spot of each measuring point in the calculation matrix relative to the reference surfaceij_d0；
S323: converting the calculation result into the base coordinate system to obtain the base parameters of all the measurement points covered by the calculation matrix in the base coordinate system:
wherein (xS, yS) represents the horizontal parameter of the S-th measuring point on the substrate under the substrate coordinate system, zSAnd the height parameter of the S-th measuring point in the base coordinate system is represented.
4. The method for measuring basal profile according to claim 2, wherein in the step S33, the base position value of the known point in the current calculation matrix is corrected by using the height of the reference plane corresponding to the known point in the previous calculation matrix as:
wherein:
FLS_Zl,kthe base height value of a measurement point of the ith row and the kth column in the current calculation matrix is obtained;
FLS_Zl,kthe corrected base height value of the measurement point of the ith row and the kth column in the current calculation matrix is obtained;
Spotp,q_djumpand after the calculation matrix is stepped for the first jump along the positive direction of the Y axis, the height of a measurement point of the p row and the q column in the calculation matrix relative to the corresponding reference surface during the stepping for the first time.
5. The method for measuring basal profile according to claim 4, wherein the step S34 of converting the calculation result into the position parameters of the unknown point in the basal coordinate system comprises the following steps:
wherein (x)S，yS) Represents the horizontal parameter, z, of the S-th measuring point on the substrate in the substrate coordinate systemSRepresenting the height parameter of the Sth measuring point on the substrate under a substrate coordinate system; (X _ WS, Y _ WS) are substrate table level values of the substrate table.
6. The footprint measurement method of claim 1, wherein in step S2, said scan path is: two adjacent columns are connected end to end in sequence to form a snake-shaped path.
7. A substrate surface type measuring device for realizing the substrate surface type measuring method according to claim 1, comprising a substrate table, a substrate fixed on the substrate table, an interferometer component for measuring the position of the substrate table, a focusing and leveling system and a data processing unit, wherein the focusing and leveling system makes m X n light spot matrixes incident on the substrate, wherein n is more than or equal to 3, m is more than or equal to 3, the light spot matrixes scan the surface of the substrate step by step, a plurality of substrate position values of the substrate are obtained by measurement, the step length of the light spot matrixes in the X direction is equal to the column pitch of the light spot matrixes, the step length of the light spot matrixes in the Y direction is equal to the row pitch of the light spot matrixes, the data processing unit measures a plurality of substrate position values according to the light spot matrixes and the substrate table position values measured by the interferometer component, and correcting the position value of the substrate, and finally calculating the surface type of the substrate according to the corrected position value of the substrate.
8. The substrate profile measuring apparatus according to claim 7, wherein the interferometer assembly comprises a Z-interferometer, an X-cube, a Y-cube, a 45 ° cube and a Z-cube long mirror, the X-cube and the Y-cube are respectively attached to two adjacent side elevation surfaces of the substrate table, the 45 ° cube is disposed at the bottom of the X-cube, the Z-cube long mirror is disposed above the substrate table, and the reference light emitted from the Z-interferometer is vertically incident to the X-cube and the Y-cube and then incident to the Z-interferometer after being reflected; and the measuring light emitted by the Z-direction interferometer enters the 45-degree mirror, is deflected by 90 degrees and then enters the Z-direction long strip mirror, and finally returns to the Z-direction interferometer along the original path.
9. A substrate profile measuring apparatus according to claim 7 or 8, wherein the substrate is secured to the substrate table by a suction cup.
10. A substrate surface type measuring device for realizing the substrate surface type measuring method according to claim 1, comprising a substrate table, a substrate fixed on the substrate table, a grating scale component for measuring the position of the substrate table, a focusing and leveling system and a data processing unit, wherein the focusing and leveling system makes m × n light spot matrixes incident on the substrate, wherein n is larger than or equal to 3, m is larger than or equal to 3, the light spot matrixes scan the surface of the substrate step by step, a plurality of substrate position values of the substrate are obtained by measurement, the step length of the light spot matrixes in the X direction is equal to the row distance of the light spot matrixes, the step length of the light spot matrixes in the Y direction is equal to the row distance of the light spot matrixes, the data processing unit measures a plurality of substrate position values according to the light spot matrixes and the substrate table position values measured by the grating scale component, and correcting the position value of the substrate, and finally calculating the surface type of the substrate according to the corrected position value of the substrate.
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| CN108801158B (en) * | 2018-08-17 | 2019-12-31 | 桂林电子科技大学 | Grating scale calibration device and calibration method |
| CN108731601B (en) * | 2018-08-17 | 2019-12-31 | 桂林电子科技大学 | Grating scale calibration device and calibration method for spatial light path |
| CN108827188B (en) * | 2018-09-07 | 2020-04-14 | 苏州瑞霏光电科技有限公司 | Three-dimensional profile microscopic measurement method based on maskless photoetching machine |
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