CN111856894A - Calibration method of four-quadrant sensor, mask transmission subsystem and photoetching equipment - Google Patents
Calibration method of four-quadrant sensor, mask transmission subsystem and photoetching equipment Download PDFInfo
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- CN111856894A CN111856894A CN201910360970.5A CN201910360970A CN111856894A CN 111856894 A CN111856894 A CN 111856894A CN 201910360970 A CN201910360970 A CN 201910360970A CN 111856894 A CN111856894 A CN 111856894A
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- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
- G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
- G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
- G03F9/7088—Alignment mark detection, e.g. TTR, TTL, off-axis detection, array detector, video detection
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Abstract
The invention discloses a calibration method of a four-quadrant sensor, a mask transmission subsystem and a photoetching device. The calibration method of the four-quadrant sensor comprises the following steps: loading a workpiece to be tested on the motion unit to an alignment position; the coordinate value of the first direction given by the micro-motion unit to the first four-quadrant sensor, the coordinate value of the second direction given by the micro-motion unit and the coordinate value of the second direction given by the second four-quadrant sensor are all 0; keeping the coordinate of the motion unit in the first coordinate direction unchanged, moving the motion unit in the second coordinate direction to drive the workpiece to be measured to move between two linear area boundaries of the second four-quadrant sensor, wherein at least one section of linear area is included between the two linear area boundaries, and the linear area is an area where the light intensity received by the second four-quadrant sensor and the light intensity of the light source are in a linear relation; and completing the calibration of the second four-quadrant sensor based on a plurality of data acquired by the second four-quadrant sensor. The invention solves the problems of low mask pre-alignment precision and low efficiency.
Description
Technical Field
The embodiment of the invention relates to the technical field of mask pre-alignment, in particular to a calibration method of a four-quadrant sensor, a mask transmission subsystem and a photoetching device.
Background
The mask pre-alignment of the photoetching equipment is to pre-align the mask plate with the optical axis of the photoetching objective lens within a certain alignment precision range, so that the fine alignment mark of the mask plate is positioned within the capture range of the fine alignment system. The precision of the mask pre-alignment affects the efficiency of the fine alignment, and the efficiency of the mask pre-alignment affects the speed of the mask plate, so the mask pre-alignment affects the exposure production efficiency of the lithography equipment, and the improvement of the efficiency and the precision of the pre-alignment is an important ring for improving the production efficiency of the lithography equipment.
The existing mask pre-alignment device is provided with two paths of alignment light paths which are bilaterally symmetrical, two pre-alignment marks on a mask are respectively collected by using two four-quadrant sensors, and the position of the mask is represented by using the energy difference relation between each quadrant, so that the pre-alignment of the mask is realized. Therefore, the measurement accuracy of the four-quadrant sensor affects the mask pre-alignment accuracy. The machine constant measured when the measured mark is aligned with the center of the four-quadrant sensor is the most accurate, so the conventional calibration of the position of the four-quadrant sensor is to align each mark on the measured object with the center of each four-quadrant sensor respectively, and perform mask pre-alignment after obtaining the machine constant of each four-quadrant sensor. However, when the four-quadrant sensor is installed, there is a mechanical installation position deviation, when the mask plate is actually measured, only one mark on the mask plate can be aligned to the center of the four-quadrant sensor, and the other marks can be separated from the center of the four-quadrant sensor, so that the pre-alignment precision of the mask plate is reduced during actual measurement, and the mask pre-alignment needs to be performed for multiple times, thereby reducing the pre-alignment efficiency of the mask.
Disclosure of Invention
In view of this, the present invention provides a calibration method for a four-quadrant sensor, a mask transmission subsystem and a lithographic apparatus, so as to reduce a pre-alignment error of a mask and improve the accuracy and efficiency of the pre-alignment of the mask.
In order to achieve the purpose, the invention adopts the following technical scheme:
in a first aspect, an embodiment of the present invention provides a calibration method for a four-quadrant sensor, including loading a workpiece to be measured on a motion unit to an alignment position, where a first transparent pre-alignment mark and a second transparent pre-alignment mark are formed on the workpiece to be measured; calibrating the first four-quadrant sensor; calibrating a second four-quadrant sensor, wherein the step of calibrating the second four-quadrant sensor comprises:
jogging the motion unit to a first direction coordinate value and a second direction coordinate value given by a first four-quadrant sensor and a second direction coordinate value given by a second four-quadrant sensor are all 0;
keeping the coordinate of the motion unit in the first coordinate direction unchanged, moving the motion unit in the second coordinate direction to drive the workpiece to be measured to move between two linear area boundaries of the second four-quadrant sensor, wherein at least one linear area is included between the two linear area boundaries, and the linear area is an area where the light intensity received by the second four-quadrant sensor and the light intensity of the light source are in a linear relation;
And completing the calibration of the second four-quadrant sensor based on a plurality of data collected by the second four-quadrant sensor.
Optionally, the step of keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the second coordinate direction to drive the workpiece to be measured to move between two linear region boundaries of the second four-quadrant sensor includes:
keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the first direction of the second coordinate direction to drive the workpiece to be measured to move to the first linear area boundary of the second four-quadrant sensor;
keeping the coordinate of the motion unit in the first coordinate direction unchanged, moving the motion unit in a second direction of the second coordinate direction according to a set step length to drive the workpiece to be measured to move to a second linear area boundary of the second four-quadrant sensor, wherein the first direction is opposite to the second direction.
Optionally, completing calibration of the second four-quadrant sensor based on a plurality of data collected by the second four-quadrant sensor, including:
acquiring a plurality of data of the second four-quadrant sensor in the process that the workpiece to be measured moves between two linear area boundaries of the second four-quadrant sensor;
Determining linear zone coefficients and inflection point values of inflection points of each linear zone between the two linear zone boundaries based on the acquired plurality of data of the second four-quadrant sensor, wherein the inflection points are critical points when the ratio of the light intensity received by the second four-quadrant sensor to the light intensity of the light source changes;
and taking the linear zone coefficient and the inflection point numerical value as the machine constant of the second four-quadrant sensor.
Optionally, acquiring a plurality of data of the second four-quadrant sensor includes:
and after the motion unit moves each set step length, recording light intensity data collected by the second four-quadrant sensor.
Optionally, determining a linear region coefficient and an inflection point value of an inflection point of each linear region between the two linear region boundaries based on the acquired plurality of data of the second four-quadrant sensor, including:
determining the number of the linear zones based on the light intensity data and the distance moved by the motion unit;
if the linear area is one, the inflection point is absent, and the method is based on a fitting equation Yrs＝a1YmDetermining the linear region coefficient a1；
If the linear zones are N, the point connecting two adjacent linear zones is the inflection point, And taking a second direction coordinate value of the inflection point as the inflection point numerical value and based on a fitting equation Yrs＝a1YmDetermining the linear zone coefficient a of the first linear zone1Based on fitting equation Yrs＝aN…a2a1Ym+ b determining the linear area coefficient a of the Nth section of linear area1，a2，……aNAnd b; wherein N is more than or equal to 2, YrsIndicating the distance moved by the movement unit, YmRepresenting the light intensity data.
Optionally, after acquiring a plurality of data of the second four-quadrant sensor, the method further includes:
and correcting the plurality of data based on the original machine constant of the second four-quadrant sensor.
Optionally, the method further includes:
calibrating the second four-quadrant sensor for multiple times to obtain multiple machine constants;
and averaging the plurality of machine constants, and taking the average value of the plurality of machine constants as a final calibration result.
In a second aspect, an embodiment of the present invention provides a mask pre-alignment method, including:
the four-quadrant sensor is calibrated by using the calibration method of the four-quadrant sensor provided by the embodiment of the invention;
and pre-aligning the mask plate based on the machine constant of the four-quadrant sensor obtained by the calibration method of the four-quadrant sensor.
In a third aspect, an embodiment of the present invention provides a mask transmission subsystem, which includes at least two four-quadrant sensors, where the four-quadrant sensors are calibrated by using the calibration method for the four-quadrant sensors provided in the embodiment of the present invention.
Optionally, the mask transmission subsystem is a mask pre-alignment measurement system, a mask plate granularity detection system or a silicon wafer pre-alignment measurement system.
In a fourth aspect, embodiments of the present invention provide a lithographic apparatus including a mask delivery subsystem according to embodiments of the present invention.
The invention has the beneficial effects that: according to the technical scheme, a first direction coordinate value, a second direction coordinate value and a second direction coordinate value which are given by a first four-quadrant sensor are adjusted to be 0, then the coordinate of a motion unit in the first coordinate direction is kept unchanged, the motion unit moves in the second coordinate direction, the first direction coordinate value given by a second four-quadrant sensor is enabled to be unchanged, only the second direction coordinate value is changed, and further in the subsequent calibration process of the second four-quadrant sensor, the first direction coordinate value of the second four-quadrant sensor does not participate in position calculation of a mask, so that calibration is not needed for both rotation deviation of the second four-quadrant sensor and displacement sensitivity of the first coordinate direction, calibration parameters are reduced, and calibration steps are simplified; meanwhile, the first direction coordinate value and the second direction coordinate value given by the first four-quadrant sensor are both 0 when the calibration is started, namely one pre-alignment mark is aligned to the center of the first four-quadrant sensor uniformly during the calibration, the other marks can be staggered with the center of the second four-quadrant sensor, constant calibration is carried out according to the current position, one pre-alignment mark of a workpiece to be measured (such as a mask) is aligned to the center of the first four-quadrant sensor during actual measurement, the other pre-alignment marks are staggered with the center of the second four-quadrant sensor, the pre-alignment mark of the mask is measured under the machine constant of the calibrated four-quadrant sensor, the actual measurement working condition is the same as the mark measurement and correction working condition, the effect of 'error in and out' is achieved, the measurement error caused by the mechanical installation position deviation among the four-quadrant sensors is reduced, and the pre-alignment error of the mask is reduced, the mask pre-alignment precision is improved, the mask pre-alignment times can be reduced, and the mask pre-alignment efficiency is improved.
Drawings
The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings, in which:
FIG. 1 is a schematic diagram of left and right pre-alignment marks on a reticle fully aligned with the centers of left and right four-quadrant sensors, respectively, according to an embodiment of the invention;
FIG. 2 is a schematic flow chart of a calibration method for a four-quadrant sensor according to an embodiment of the present invention;
FIG. 3 is a front view of a mask pre-alignment measurement system provided by an embodiment of the present invention;
FIG. 4 is a side view of a mask pre-alignment measurement system provided by an embodiment of the present invention;
fig. 5 is a schematic flowchart of a calibration method of a four-quadrant sensor according to an embodiment of the present invention;
FIG. 6 is a schematic diagram illustrating a calibration condition of the second four-quadrant sensor according to the embodiment of the present invention.
Detailed Description
The technical scheme of the invention is further explained by the specific implementation mode in combination with the attached drawings. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.
Ideally, when the mask is pre-aligned, each pre-alignment mark on the mask is aligned with the center of the corresponding four-quadrant sensor, so that accurate alignment of the mask is realized. For example, referring to fig. 1, the reticle 10 is provided with a first prealignment mark 101 and a second prealignment mark 102, the first prealignment mark 101 being aligned with the center of the first four-quadrant sensor 11 and the second prealignment mark 102 being aligned with the center of the second four-quadrant sensor 12 when the mask is prealigned. However, when the four-quadrant sensor is installed, there is a mechanical installation position deviation, when the mask plate is actually measured, only one mark on the mask plate can be aligned to the center of the four-quadrant sensor, and the rest marks can be separated from the center of the four-quadrant sensor, so that the pre-alignment precision of the mask plate is reduced during the actual measurement. The machine constant obtained by the conventional calibration of the four-quadrant sensor is about the machine constant of the center of the four-quadrant sensor, when the mask plate is actually measured, a certain precision is lost when the pre-alignment mark in the four-quadrant sensor deviates, the accuracy of the measurement of the pre-alignment mark is reduced, the pre-alignment error of the mask plate is increased, and the precision and the efficiency of the pre-alignment of the mask plate are further reduced.
Based on the above technical problem, an embodiment of the present invention provides a calibration method for a four-quadrant sensor, in which only one of the pre-alignment marks is aligned with the center of the corresponding four-quadrant sensor, and when calibrating the other four-quadrant sensors respectively, the other pre-alignment marks are all deviated from the center of the corresponding four-quadrant sensor, so as to obtain a machine constant deviated from the center of the four-quadrant sensor correspondingly. Therefore, when a workpiece (mask plate) is actually measured, a corresponding prealignment mark (the prealignment mark corresponding to the position when the four-quadrant sensor is calibrated) on the workpiece is aligned with the center of the corresponding four-quadrant sensor, other prealignment marks deviate from the center of the corresponding four-quadrant sensor, and then the prealignment marks are measured according to the machine constants of the four-quadrant sensor obtained through calibration, so that the mask plate is adjusted to be prealigned. Meanwhile, in order to avoid the mark of the rotation deviation and reduce the calibration of the displacement sensitivity, the technical scheme of the invention only measures the pre-alignment mark in one coordinate direction. Specifically, fig. 2 is a schematic flow chart of a calibration method of a four-quadrant sensor according to an embodiment of the present invention. The method is suitable for an alignment system consisting of at least two four-quadrant sensors, and can realize accurate and rapid alignment of the workpiece to be measured by calibrating the four-quadrant sensors. As shown in fig. 2, the calibration method of the four-quadrant sensor includes: loading a workpiece to be tested on the motion unit to an alignment position; calibrating the first four-quadrant sensor; and calibrating the second four-quadrant sensor. Calibrating the second four-quadrant sensor may include steps 130 to 150. Specifically, the calibration method of the four-quadrant sensor comprises the following steps:
The workpiece to be measured can be a mask plate, a silicon wafer or a wafer and the like, a transparent first pre-alignment mark and a transparent second pre-alignment mark are formed on the workpiece to be measured, the first pre-alignment mark and the second pre-alignment mark correspond to the four-quadrant sensor in a one-to-one mode, and the positions and the shapes of the first pre-alignment mark and the second pre-alignment mark are matched with the pre-alignment mark on the workpiece to be measured in actual measurement; the motion unit can be a motion table (such as a mask table) or a reliable motion device such as a manipulator which can precisely move the workpiece to be measured.
For example, when the motion unit is a motion stage, the robot may be used to grasp and load the workpiece to be measured on the motion stage, and the robot may place the workpiece to be measured on the alignment position of the motion stage to facilitate alignment of the pre-alignment marks with the four-quadrant sensor. When the moving unit is a mechanical arm, the mechanical arm directly grabs the workpiece to be measured and sends the workpiece to be measured to the alignment position of the corresponding pre-alignment device, and at the moment, the mechanical arm can properly turn over the workpiece to be measured, so that the alignment surface of the workpiece to be measured is opposite to the measuring part of the four-quadrant sensor.
And 120, calibrating the first four-quadrant sensor.
Generally, when the first four-quadrant sensor is calibrated, the center of the first pre-alignment mark is aligned to the center of the first four-quadrant sensor, the movement unit is controlled to move so that the first four-quadrant sensor firstly moves along the negative direction of the first coordinate direction or the second coordinate direction and moves to the boundary of one measuring range, and then the first four-quadrant sensor firstly moves along the positive direction of the first coordinate direction or the second coordinate direction and moves to the boundary of the other measuring range; and acquiring data acquired in the moving process of the first four-quadrant sensor, and fitting the data to obtain calibration parameters of the first four-quadrant sensor.
Because the mechanical installation position deviation exists between the first four-quadrant sensor and the second four-quadrant sensor, when the coordinate values of the first direction and the second direction given by the first four-quadrant sensor are adjusted to be 0, only one of the coordinate values given by the second four-quadrant sensor is 0 at most. In this embodiment, the position of the workpiece to be measured is adjusted by the micro-motion unit, so that the first direction coordinate value and the second direction coordinate value given by the first four-quadrant sensor and the second direction coordinate value given by the second four-quadrant sensor are all 0, the first pre-alignment mark is aligned to the center of the first four-quadrant sensor, and the second pre-alignment mark is deviated from the center of the second four-quadrant sensor. Wherein, the coordinate value of the first direction is an X value, and the coordinate value of the second direction is a Y value; or the coordinate value of the first direction is a Y value, and the coordinate value of the second direction is an X value; the invention is not limited in this regard.
It should be noted that the number of the four-quadrant sensors is not limited to the first four-quadrant sensor and the second four-quadrant sensor, and the number of the four-quadrant sensors in the embodiment of the present invention is at least two, where one of the four-quadrant sensors is used as the first four-quadrant sensor, and the other four-quadrant sensors are used as the second four-quadrant sensor. When the second four-quadrant sensors are calibrated, each second four-quadrant sensor is respectively calibrated. In addition, in the actual calibration operation, the first direction coordinate value, the second direction coordinate value and the second direction coordinate value given by the first four-quadrant sensor and the second four-quadrant sensor can all be close to 0, and the upper and lower errors can be within a set value range.
And 140, keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the second coordinate direction to drive the workpiece to be measured to move between two linear area boundaries of the second four-quadrant sensor.
At least one section of linear area is arranged between the boundaries of the two linear areas, and the linear area is an area where the light intensity received by the second four-quadrant sensor and the light intensity of the light source are in a linear relation. The linear region boundary is used for defining the range of all linear regions, and a linear region can be included between two linear region boundaries, and a plurality of linear regions connected end to end can also be included.
Illustratively, based on step 130, when the X value and the Y value given by the inching motion unit to the first four-quadrant sensor and the Y value given by the second four-quadrant sensor are all 0, in this step, the coordinate of the motion unit in the X coordinate direction should be kept unchanged, and the moving motion unit moves in the Y coordinate direction, so as to drive the workpiece to be measured to move between two linear region boundaries of the second four-quadrant sensor along the Y coordinate direction. Therefore, in the subsequent calibration process of the second four-quadrant sensor, the X value of the second four-quadrant sensor does not participate in the position calculation of the mask, so that the rotation deviation and the X coordinate direction displacement sensitivity of the second four-quadrant sensor are not required to be calibrated, calibration parameters are reduced, and the calibration steps are simplified.
And 150, completing the calibration of the second four-quadrant sensor based on a plurality of data collected by the second four-quadrant sensor.
In this embodiment, the plurality of data collected by the second four-quadrant sensor may be light intensity data collected by the second four-quadrant sensor through the second pre-alignment mark, or may be current data correspondingly converted from the light intensity data. In this embodiment, based on a plurality of data collected by the second four-quadrant sensor, the machine constant of the second four-quadrant sensor about the deviation from the center of the second four-quadrant sensor in step 130 can be obtained, so as to complete calibration of the second four-quadrant sensor. In addition, the calibration of the first four-quadrant sensor can be realized by a conventional calibration method, namely, the machine constant of the first four-quadrant sensor relative to the center of the first four-quadrant sensor is measured by aligning the first pre-alignment mark with the center of the first four-quadrant sensor. Therefore, the calibration of each four-quadrant sensor is completed, the machine constant of each four-quadrant sensor is obtained, and further, when the workpiece to be measured is actually measured, the workpiece to be measured can be quickly and accurately pre-aligned based on the machine constant.
For example, based on the above technical solution, the present embodiment takes a mask pre-alignment measurement system as an example to describe the calibration method of the four-quadrant sensor, and the present embodiment may utilize the mask pre-alignment measurement system to calibrate its own four-quadrant sensor. Referring to fig. 3 and 4, the mask pre-alignment measuring system may include a mask stage 20, a first four-quadrant sensor 11 and a second four-quadrant sensor 12 positioned at one side of the mask stage 20 and symmetrically distributed, a first light source 201 and a second light source 202 positioned above the mask stage 20 and facing the first four-quadrant sensor 11 and the second four-quadrant sensor 12, respectively, the first light source 201 and the second light source 202 for providing an alignment light path.
When the four-quadrant sensor is calibrated by using the mask pre-alignment measuring system, the mask 10 can be grabbed by using a manipulator, and then the mask 10 is loaded on the mask table 20 and moved to the alignment position of the mask table 20; then, the calibration of the first four-quadrant sensor 11 can be realized by a conventional calibration method; then, the X value and the Y value given by the first four-quadrant sensor 11 and the Y value given by the second four-quadrant sensor 12 from the micro-motion mask stage 20 are all 0; then, the mask stage 20 keeps the coordinate in the X coordinate direction unchanged, and moves in the Y coordinate direction, thereby driving the mask 10 to move between two linear region boundaries of the second four-quadrant sensor 12; meanwhile, in the process that the mask 10 moves along the Y coordinate direction, the second four-quadrant sensor 12 acquires a plurality of data, and the mask pre-alignment measurement system (specifically, the control unit thereof) completes calibration of the second four-quadrant sensor based on the plurality of data acquired by the second four-quadrant sensor.
In summary, in the calibration method of the four-quadrant sensor provided in this embodiment, the first direction coordinate value, the second direction coordinate value and the second direction coordinate value given by the first four-quadrant sensor are all adjusted to be 0, and then the coordinate of the motion unit in the first coordinate direction is kept unchanged, and the motion unit is moved in the second coordinate direction, so that the first direction coordinate value given by the second four-quadrant sensor is unchanged, only the second direction coordinate value is changed, and further in the subsequent calibration process of the second four-quadrant sensor, since the first direction coordinate value of the second four-quadrant sensor does not participate in the position calculation of the reticle, calibration is not required for both the rotational deviation of the second four-quadrant sensor and the sensitivity of the displacement in the first coordinate direction, calibration parameters are reduced, and the calibration steps are simplified; meanwhile, the first direction coordinate value and the second direction coordinate value given by the first four-quadrant sensor are both 0 when the calibration is started, namely one pre-alignment mark is aligned to the center of the first four-quadrant sensor uniformly during the calibration, the other marks can be staggered with the center of the second four-quadrant sensor, constant calibration is carried out according to the current position, one pre-alignment mark of a workpiece to be measured (such as a mask) is aligned to the center of the first four-quadrant sensor during actual measurement, the other pre-alignment marks are staggered with the center of the second four-quadrant sensor, the pre-alignment mark of the mask is measured under the machine constant of the calibrated four-quadrant sensor, the actual measurement working condition is the same as the mark measurement and correction working condition, the effect of 'error in and out' is achieved, the measurement error caused by the mechanical installation position deviation among the four-quadrant sensors is reduced, and the pre-alignment error of the mask is reduced, the mask pre-alignment precision is improved, the mask pre-alignment times can be reduced, and the mask pre-alignment efficiency is improved.
Optionally, based on the foregoing embodiment, in this embodiment, the step of keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the second coordinate direction to drive the workpiece to be measured to move between two linear region boundaries of the second four-quadrant sensor is further optimized, and the step may specifically include: keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the first direction of the second coordinate direction to drive the workpiece to be measured to move to the first linear area boundary of the second four-quadrant sensor; and keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in a second direction of a second coordinate direction according to a set step length so as to drive the workpiece to be measured to move to a second linear area boundary of the second four-quadrant sensor.
Further, based on the plurality of data collected by the second four-quadrant sensor, completing calibration of the second four-quadrant sensor may include: acquiring a plurality of data of a second four-quadrant sensor in the process that a workpiece to be measured moves between two linear area boundaries of the second four-quadrant sensor; determining linear zone coefficients and inflection point numerical values of inflection points of each linear zone between two linear zone boundaries based on the obtained plurality of data of the second four-quadrant sensor; and taking the linear zone coefficient and the inflection point numerical value as the machine constant of the second four-quadrant sensor.
Optionally, in the above step, acquiring a plurality of data of the second four-quadrant sensor may include: and after the motion unit moves each set step length, recording light intensity data acquired by the second four-quadrant sensor.
Preferably, after acquiring a plurality of data of the second four-quadrant sensor, the method further comprises: the plurality of data are corrected based on the original machine constants of the second four-quadrant sensor.
Preferably, the calibration method of the four-quadrant sensor further includes: calibrating the second four-quadrant sensor for multiple times to obtain multiple machine constants; and averaging the multiple machine constants, and taking the average value of the multiple machine constants as a final calibration result.
Correspondingly, based on the above technical solution, a specific embodiment of the present invention provides a calibration method for a four-quadrant sensor. As shown in fig. 5, the calibration method of the four-quadrant sensor provided in this embodiment may specifically include:
And 240, keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the first direction of the second coordinate direction to drive the workpiece to be measured to move to the first linear area boundary of the second four-quadrant sensor.
Illustratively, the second coordinate direction is the Y coordinate direction, and the Y value of the first linear region boundary is typically-350 μm.
And 250, keeping the coordinate of the motion unit in the first coordinate direction unchanged, moving the motion unit in a second direction of the second coordinate direction according to the set step length to drive the workpiece to be measured to move to a second linear area boundary of the second four-quadrant sensor, and recording light intensity data acquired by the second four-quadrant sensor after the motion unit moves each set step length.
Wherein the first direction and the second direction are opposite. For example, the second coordinate direction is a Y coordinate direction, and the set step size may be 10 μm to ensure that a plurality of light intensity data are collected in each linear region, so as to calculate the linear region coefficient of each linear region.
And step 260, correcting the light intensity data based on the original machine constant of the second four-quadrant sensor.
Because the difference between the original components of the four-quadrant sensor is the same light intensity, the collected light intensity data can be different, and therefore after the light intensity data are recorded every time, the original machine constant of the second four-quadrant sensor is utilized to correct the light intensity data so as to eliminate the difference between the original components of the second four-quadrant sensor.
And step 270, determining linear zone coefficients and inflection point values of inflection points of each linear zone between the boundaries of the two linear zones based on the light intensity data.
The inflection point is a critical point when the ratio of the light intensity received by the second four-quadrant sensor to the light intensity of the light source changes. Specifically, determining linear zone coefficients and inflection point values of inflection points of each linear zone between two linear zone boundaries based on the obtained plurality of data of the second four-quadrant sensor includes:
A. the number of linear zones is determined based on the light intensity data and the distance moved by the motion unit.
The light intensity data and the moving distance of the moving unit are in a linear relation in the linear region, the linear coefficients of the light intensity data in the same linear region and the moving distance of the moving unit are the same, and the linear coefficients of the light intensity data in different linear regions and the moving distance of the moving unit are different, so that the linear coefficients between the light intensity data and the moving distance of the moving unit can be determined based on the light intensity data and the corresponding moving distance of the moving unit, and the number of the linear regions is determined according to the number of the linear coefficients.
B. If the linear area is one, the inflection point is absent, and the method is based on a fitting equation Y rs＝a1YmDetermining the coefficient of the linear region a1。
C. If the linear areas are N, the point connecting two adjacent linear areas is an inflection point, the second direction coordinate value of the inflection point is used as an inflection point numerical value, and the numerical value is based on a fitting equation Yrs＝a1YmDetermining linear area coefficient a of the first linear area1Based on fitting equation Yrs＝aN…a2a1Ym+ b linear area coefficient a of Nth section linear area1，a2，……aNAnd b.
Wherein N is more than or equal to 2, YrsIndicating the distance moved by the movement unit, YmRepresenting the light intensity data.
In this embodiment, a plurality of light intensity data and a corresponding moving distance of the moving unit after moving a set step length can be obtained in each section of linear area, and linear fitting is performed on a plurality of sets of light intensity data and corresponding moving distances of the moving unit in each section of linear area, so that a linear area coefficient of each section of linear area can be obtained.
Illustratively, the linear region includes a first linear region and a second linear region based on a fitting equation Yrs＝a1YmDetermining linear area coefficient a of the first linear area1Based on fitting equation Yrs＝a2a1Ym+ b linear area coefficient a of the second linear area1，a2And b.
And step 280, taking the linear zone coefficient and the inflection point numerical value as machine constants of the second four-quadrant sensor.
And 290, calibrating the second four-quadrant sensor for multiple times to obtain multiple machine constants.
And step 300, averaging the multiple machine constants, and taking the average value of the multiple machine constants as a final calibration result.
In the embodiment, a plurality of machine constants obtained by calibrating the second four-quadrant sensor for a plurality of times are averaged, and the average value is used as a final calibration result, so that the accuracy of the measured machine constant is improved.
The embodiment of the invention also provides a mask pre-alignment method, which comprises the following steps:
A. the four-quadrant sensor is calibrated by using the calibration method of the four-quadrant sensor provided by any embodiment of the invention.
B. And pre-aligning the mask plate based on the machine constant of the four-quadrant sensor obtained by the calibration method of the four-quadrant sensor.
In this embodiment, referring to fig. 6, when calibrating the second four-quadrant sensor 12, the first pre-alignment mark 101 is aligned with the center of the first four-quadrant sensor 11, and the second pre-alignment mark 102 is offset from the center of the second four-quadrant sensor 12, optionally, the Y value given by the second four-quadrant sensor 12 is 0, so as to complete calibration of the second four-quadrant sensor. When the mask is actually measured, the working condition is the same as that shown in fig. 6, that is, the first prealignment mark 101 on the mask is aligned to the center of the first four-quadrant sensor 11, the second prealignment mark 102 deviates from the center of the second four-quadrant sensor 12, and the mask is prealigned based on the calibrated machine constant.
Another embodiment of the present invention further provides a mask transmission subsystem, which includes at least two four-quadrant sensors, and the four-quadrant sensors can be calibrated by using the calibration method for the four-quadrant sensors provided in any of the above embodiments.
Optionally, the mask transmission subsystem may be a mask pre-alignment measurement system, a reticle granularity detection system, or a silicon wafer pre-alignment measurement system.
Because the four-quadrant sensor in the mask transmission subsystem is calibrated by using the calibration method of the four-quadrant sensor provided by the embodiment of the invention, the precision and the efficiency of pre-alignment can be improved when the mask transmission subsystem is used for pre-aligning workpieces such as a mask plate, a silicon wafer or a wafer.
In addition, the embodiment of the invention also provides a photoetching device which comprises the mask transmission subsystem provided by the embodiment.
The lithography equipment provided by the embodiment of the invention comprises the mask transmission subsystem provided by the embodiment of the invention, so that the exposure production efficiency of the lithography equipment can be improved.
It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious modifications, rearrangements, combinations and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.
Claims (11)
1. A calibration method of a four-quadrant sensor comprises the steps of loading a workpiece to be measured on a motion unit to an alignment position, wherein a first transparent pre-alignment mark and a second transparent pre-alignment mark are formed on the workpiece to be measured; calibrating the first four-quadrant sensor; calibrating a second four-quadrant sensor, wherein the step of calibrating the second four-quadrant sensor comprises:
jogging the motion unit to a first direction coordinate value and a second direction coordinate value given by a first four-quadrant sensor and a second direction coordinate value given by a second four-quadrant sensor are all 0;
keeping the coordinate of the motion unit in the first coordinate direction unchanged, moving the motion unit in the second coordinate direction to drive the workpiece to be measured to move between two linear area boundaries of the second four-quadrant sensor, wherein at least one linear area is included between the two linear area boundaries, and the linear area is an area where the light intensity received by the second four-quadrant sensor and the light intensity of the light source are in a linear relation;
and completing the calibration of the second four-quadrant sensor based on a plurality of data collected by the second four-quadrant sensor.
2. The calibration method of the four-quadrant sensor according to claim 1, wherein the step of moving the motion unit in the second coordinate direction to move the workpiece to be measured between two linear region boundaries of the second four-quadrant sensor while keeping the coordinates of the motion unit in the first coordinate direction unchanged comprises:
keeping the coordinate of the motion unit in the first coordinate direction unchanged, and moving the motion unit in the first direction of the second coordinate direction to drive the workpiece to be measured to move to the first linear area boundary of the second four-quadrant sensor;
keeping the coordinate of the motion unit in the first coordinate direction unchanged, moving the motion unit in a second direction of the second coordinate direction according to a set step length to drive the workpiece to be measured to move to a second linear area boundary of the second four-quadrant sensor, wherein the first direction is opposite to the second direction.
3. The calibration method of the four-quadrant sensor according to claim 2, wherein the calibration of the second four-quadrant sensor is completed based on a plurality of data collected by the second four-quadrant sensor, and comprises:
Acquiring a plurality of data of the second four-quadrant sensor in the process that the workpiece to be measured moves between two linear area boundaries of the second four-quadrant sensor;
determining linear zone coefficients and inflection point values of inflection points of each linear zone between the two linear zone boundaries based on the acquired plurality of data of the second four-quadrant sensor, wherein the inflection points are critical points when the ratio of the light intensity received by the second four-quadrant sensor to the light intensity of the light source changes;
and taking the linear zone coefficient and the inflection point numerical value as the machine constant of the second four-quadrant sensor.
4. The method for calibrating a four-quadrant sensor according to claim 3, wherein acquiring a plurality of data of the second four-quadrant sensor comprises:
and after the motion unit moves each set step length, recording light intensity data collected by the second four-quadrant sensor.
5. The calibration method of the four-quadrant sensor according to claim 4, wherein determining the numerical values of the linear zone coefficients and the inflection points of the linear zones between the two linear zone boundaries based on the obtained plurality of data of the second four-quadrant sensor comprises:
Determining the number of the linear zones based on the light intensity data and the distance moved by the motion unit;
if the linear area is one, the inflection point is absent, and the method is based on a fitting equation Yrs＝a1YmDetermining the linear region coefficient a1；
If the linear areas are N, the point connecting two adjacent linear areas is the inflection point, the second direction coordinate value of the inflection point is taken as the numerical value of the inflection point, and the numerical value is based on a fitting equation Yrs＝a1YmDetermining the linear zone coefficient a of the first linear zone1Based on fitting equation Yrs＝aN…a2a1Ym+ b determining the linear area coefficient a of the Nth section of linear area1，a2，……aNAnd b; wherein N is more than or equal to 2, YrsIndicating the distance moved by the movement unit, YmRepresenting the light intensity data.
6. The method for calibrating a four-quadrant sensor according to claim 3, further comprising, after acquiring a plurality of data of the second four-quadrant sensor:
and correcting the plurality of data based on the original machine constant of the second four-quadrant sensor.
7. The calibration method of the four-quadrant sensor according to claim 3, further comprising:
calibrating the second four-quadrant sensor for multiple times to obtain multiple machine constants;
And averaging the plurality of machine constants, and taking the average value of the plurality of machine constants as a final calibration result.
8. A method of pre-aligning a mask, comprising:
calibrating the four-quadrant sensor by using the calibration method of the four-quadrant sensor as claimed in any one of claims 1 to 7;
and pre-aligning the mask plate based on the machine constant of the four-quadrant sensor obtained by the calibration method of the four-quadrant sensor.
9. A mask transfer subsystem comprising at least two four-quadrant sensors calibrated using the method of calibrating a four-quadrant sensor according to any of claims 1 to 7.
10. The mask transmission subsystem of claim 9, wherein the mask transmission subsystem is a mask pre-alignment measurement system, a reticle granularity detection system, or a silicon wafer pre-alignment measurement system.
11. A lithographic apparatus comprising a mask delivery subsystem according to claim 9 or 10.
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| CN1940734A (en) * | 2005-09-28 | 2007-04-04 | 中国科学院自动化研究所 | Four-quadrant aligning device of mask transmission system |
| US7928409B2 (en) * | 2005-10-11 | 2011-04-19 | The United States Of America As Represented By The Secretary Of Commerce | Real-time, active picometer-scale alignment, stabilization, and registration in one or more dimensions |
| CN103425005A (en) * | 2012-05-22 | 2013-12-04 | 上海微电子装备有限公司 | Light-source-modulation-based mask pre-aligning system and pre-aligning method |
| TW201504776A (en) * | 2013-07-18 | 2015-02-01 | Univ Nat Formosa | Optical alignment measuring method and measuring device thereof |
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| CN1940734A (en) * | 2005-09-28 | 2007-04-04 | 中国科学院自动化研究所 | Four-quadrant aligning device of mask transmission system |
| US7928409B2 (en) * | 2005-10-11 | 2011-04-19 | The United States Of America As Represented By The Secretary Of Commerce | Real-time, active picometer-scale alignment, stabilization, and registration in one or more dimensions |
| CN103425005A (en) * | 2012-05-22 | 2013-12-04 | 上海微电子装备有限公司 | Light-source-modulation-based mask pre-aligning system and pre-aligning method |
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