WO2011114407A1

WO2011114407A1 - Method for measuring wavefront aberration and device of same

Info

Publication number: WO2011114407A1
Application number: PCT/JP2010/007178
Authority: WO
Inventors: 達雄針山; 実 ▲吉▼田; 康裕吉武
Original assignee: 株式会社日立製作所
Priority date: 2010-03-18
Filing date: 2010-12-10
Publication date: 2011-09-22
Also published as: JP2011196732A

Abstract

Since the pupil diameter of the objective lens used for a semiconductor inspection device or a laser machining device sometimes exceeds the field of view detected by a Shack-Hartmann sensor, the aberration of the whole pupil cannot be measured by a single image-pickup. In order to measure the aberration of the whole pupil, the large field of view is detected by scanning the Shack-Hartmann sensor.

Description

Wavefront aberration measuring method and apparatus

The present invention relates to a method and apparatus for measuring wavefront aberration of a lens mounted on an optical apparatus such as a semiconductor optical inspection apparatus or a printed board laser processing apparatus.

The semiconductor wafer optical inspection device is a device for detecting foreign matter on the wafer, and manages the number of foreign matters. Since the size of foreign matter to be managed differs according to the semiconductor manufacturing process, the inspection apparatus has an optical magnification variable function. When the optical magnification is increased, a smaller foreign object can be detected. On the other hand, the field of view that can be detected by the sensor is also reduced, and thus the throughput is reduced. Therefore, in a semiconductor line, inspection is performed with a magnification increased only in a process that requires particularly fine foreign matter management. The detection system of the inspection apparatus includes an objective lens and an imaging lens, and the magnification change is generally performed by changing the focal length of the imaging lens.

In a line that manufactures a large number of wafers, a plurality of optical inspection apparatuses are used. In each manufacturing process, an allowable value of the number of foreign matters is set in advance. When the allowable value is exceeded, countermeasures such as cleaning of the manufacturing apparatus are taken. Here, if the optical inspection apparatuses A and B have different sensitivities (detectable foreign material sizes), an allowable value must be set for each inspection apparatus, which is a major obstacle to the operation of the inspection apparatus. The sensitivity of the optical inspection device largely depends on the imaging performance of the detection system lens. Therefore, in order to reduce the sensitivity difference of the optical inspection apparatus, it is necessary to manage the imaging performance of the lens alone, particularly the wavefront aberration.

As a method for measuring the wavefront aberration of a lens, a method using a Shack-Hartmann sensor is known as described in Patent Document 1. The principle of the Shack-Hartmann sensor will be described with reference to FIG. The Shack-Hartmann sensor is a sensor that divides and condenses the wavefront (phase distribution) of light incident on the sensor with an array lens, and picks it up with a two-dimensional sensor as an array image of multiple spots. An aberration coefficient is calculated. FIG. 4A shows the relationship between the wavefront, the array lens, and the sensor surface. From the geometrical relationship, the wavefront can be obtained as shown in Equation 1.

A spot array image displaced in accordance with Equation 1 is shown in FIG. With respect to FIG. 7B, the coefficient for each wavefront aberration can be calculated by obtaining the center of gravity of the spot, calculating the amount of spot position deviation, and fitting to a polynomial expressing the wavefront aberration.
Here, typical aberrations are shown in FIGS. (C) shows the defocus aberration expressed by Equation 2, (d) shows the third-order astigmatism expressed by Equation 3, and (e) shows the third-order astigmatism expressed by Equation 4. FIG. 5 (f) shows the third-order spherical aberration expressed by Equation 5.

Wavefront aberration measurement by the Shack-Hartmann sensor is less susceptible to environmental changes such as air temperature changes and vibrations in the optical path, and can cope with local wavefront changes beyond the measurement wavelength generated by aspherical lenses, etc. This is advantageous compared to the conventional interferometer method. In this known example, the projection lens of the exposure apparatus is the measurement object. On the other hand, the detection system lens of the optical inspection apparatus includes an objective lens and an imaging lens.

As mentioned above, the focal length of the imaging lens changes because the magnification is variable. This is realized by replacing the imaging lens or using a zoom lens. The wavefront aberration can be measured with one set of the objective lens and the imaging lens as in the case of the projection lens, but the obtained aberration is the positive aberration generated by the objective lens and the negative aberration of the imaging lens. In this case, if the lens is changed to an imaging lens having a different focal length, the aberration may change greatly. Therefore, it is desirable to measure the aberration of the objective lens alone. However, since the objective lens alone does not form an image (it is an infinite system), a measurement method with a configuration different from the above known example is required.

In the laser processing apparatus for printed boards, an infinite fθ lens is used as in the objective lens of the above-described semiconductor optical inspection apparatus. In this apparatus, parallel light is deflected by a galvanometer mirror installed at the pupil position of an fθ lens and incident on the fθ lens, thereby scanning the printed circuit board with a condensed beam. The fθ lens is a lens that is intentionally distorted so that the beam position on the printed circuit board is determined by the product fθ of the light deflection angle θ by the galvano mirror and the focal length of the fθ lens. Since the fθ lens is not an imaging lens, a measurement method different from the conventional imaging type is required. In the laser processing apparatus, the aberration of the fθ lens affects the processing shape for each scanning position of the focused beam. Therefore, in order to obtain a uniform processing shape in the scanning range, it is necessary to manage the aberration (wavefront aberration). .

In the wavefront aberration measurement using the above Shack-Hartmann sensor, in addition to the aberration of the measurement target lens, the aberration including the aberration of the lens array of the measurement optical system and the relay lens is measured. Therefore, in Patent Document 1, the measurement target lens is subjected to single measurement by another means such as an interferometer, and the measurement optical system is subtracted from the data including measurement optical system aberrations. A method for calculating the aberration is disclosed.

On the other hand, in Patent Document 2, only the lens to be measured is measured twice by changing its orientation, such as rotation, and the difference between the measured values is obtained to cancel the aberration of the measuring optical system, and the aberration of only the lens to be measured. A method of calculating is disclosed.

JP 2004-14764 A JP 2006-30016 A

However, in the case of an objective lens used in a semiconductor inspection apparatus or a laser processing apparatus, the pupil diameter may exceed the detection field of view of the Shack-Hartmann sensor. There is a problem that it cannot be measured.

One of the objects of the present invention is to solve the above-mentioned problems, and a wavefront aberration measurement method and wavefront aberration measurement capable of measuring aberration even for a lens having a large pupil that exceeds the visual field range of a Shack-Hartmann sensor that could not be measured conventionally. To provide an apparatus.
Other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

大 Large field of view is detected by scanning the Shack-Hartmann sensor to measure the wavefront aberration of the entire pupil. As a scanning method of the Shack-Hartmann sensor, there are a method of scanning a two-dimensional sensor two-dimensionally by step and repeat, and a method of scanning one-dimensionally by a one-dimensional sensor that covers the pupil diameter.

When performing stage scanning with a Shack-Hartmann sensor, the stage yawing, pitching, and straightness affect the spot condensing position error during the entire pupil composition. Therefore, it is necessary to measure the yawing, pitching, and straightness of the stage with high accuracy and correct the acquired data. For measuring yawing, pitching, and straightness, there are a method using a laser length measuring device and a method using an autocollimator.

Hereinafter, a procedure for measuring aberrations in a large visual field that exceeds the visual field range of the Shack-Hartmann sensor will be described. As a first step, a stage movement command for scanning the stage is input. As a second step, the stage is moved to a predetermined position in accordance with the input stage movement command. As a third step, the pupil is imaged by the Shack-Hartmann sensor at the predetermined stage position moved in the second step. As a fourth step, the value of the laser length measuring device is recorded at the predetermined stage movement location moved in the second step. As a fifth step, the yaw amount, pitching amount, and straightness of the stage are calculated from the recorded laser length measurement value, and the stage error is corrected for the data imaged by the Shack-Hartmann sensor. As a sixth step, the corrected data are joined together to create imaging data in a large field of view and perform aberration analysis.

Further, a summary of typical ones of the inventions disclosed in the present application will be briefly described as follows.
(1) A wavefront aberration measuring method characterized in that aberration measurement is performed in a visual field that exceeds the visual field of the Shack-Hartmann sensor by moving the Shack-Hartmann sensor in a plane, imaging, and joining acquired data. .
(2) A wavefront aberration measuring method for measuring the wavefront aberration of a lens having a pupil diameter larger than the visual field of the Shack-Hartmann sensor, wherein the stage on which the Shack-Hartmann sensor is mounted is irradiated with light while the lens is irradiated with light. Scanning at the pupil position to image a plurality of regions, calculating a plurality of spot displacement data from the obtained plurality of spot luminance images, and measuring a moving amount and an inclination amount of the stage by a laser side lengther; Correcting and joining the plurality of spot displacement data using the measured stage movement amount and tilt amount, creating spot coordinate data, and performing wavefront analysis on the created spot coordinate data And measuring the wavefront aberration of the lens.
(3) A wavefront aberration measuring apparatus for measuring a wavefront aberration of a lens, the light irradiating means for irradiating the lens with light, the Shack-Hartmann sensor for scanning a pupil position of the lens and imaging a plurality of areas, and the shack A stage mounted with a Hartmann sensor for scanning, spot displacement data calculating means for calculating a plurality of spot displacement data from a plurality of spot luminance images obtained by imaging a plurality of regions by the Shack-Hartmann sensor, and a moving amount of the stage And a plurality of spot displacement data obtained by the laser side length measuring device for measuring the tilt amount and the spot displacement data calculating means are corrected by using the moving amount and the tilt amount of the stage measured by the laser side length measuring device. The spot coordinate data creating means for creating the spot coordinate data, and the created The pot coordinate data is wavefront aberration measuring apparatus characterized by having a wavefront aberration measuring means for measuring a wavefront aberration of the lens by analyzing leaf surface.
(4) The wavefront aberration measuring apparatus according to (3), further comprising display means for displaying the wavefront aberration measured by the wavefront aberration measuring means.
(5) Wavefront aberration on the array lens by moving the one-dimensional line sensor on the array lens, imaging, arranging the acquired luminance data of each line, and calculating the spot displacement amount from the arranged luminance data It is a wavefront aberration measuring method characterized by performing measurement.
(6) A wavefront aberration measuring method for measuring a wavefront aberration of a lens, wherein a plurality of regions are obtained by scanning a stage equipped with an array lens and a one-dimensional line sensor at a pupil position of the lens while irradiating the lens with light. , Calculating a plurality of luminance data from the obtained plurality of spot luminance images, measuring a moving amount and a tilt amount of the stage by a laser side lengther, and the plurality of luminance data, A step of calculating luminance data at a plurality of ideal imaging positions by correcting using the measured movement amount and tilt amount of the stage, and calculating the luminance data at the plurality of ideal imaging positions. To calculate spot displacement data at a plurality of ideal imaging positions, and connect the spot displacement data at the plurality of ideal imaging positions. And creating a a wavefront aberration measuring method characterized by comprising the steps of: measuring a wavefront aberration of the lens spot coordinate data created in the above with wavefront analysis.
(7) A wavefront aberration measuring apparatus for measuring a wavefront aberration of a lens, the light irradiating means for irradiating the lens with light, a one-dimensional line sensor that scans a pupil position of the lens and images a plurality of regions, An array lens disposed at a pupil position of the lens independently of the one-dimensional line sensor, a stage that mounts and scans the one-dimensional line sensor, and a plurality of images obtained by imaging a plurality of regions by the one-dimensional line sensor Luminance data calculating means for calculating a plurality of luminance data from a spot luminance image, a laser side length measuring means for measuring the amount of movement and inclination of the stage, and a plurality of luminance data obtained by the luminance data calculating means, Means for calculating brightness data at a plurality of ideal imaging positions by correcting using the moving amount and tilting amount of the stage measured by the laser side lengther; Using the luminance data at the plurality of ideal imaging positions, the spot displacement data at the plurality of ideal imaging positions is calculated, and the spot displacement data at the plurality of ideal imaging positions is connected, Wavefront aberration measurement, comprising: spot coordinate data creating means for creating spot coordinate data; and wavefront aberration measuring means for measuring the wavefront aberration of the lens by analyzing a leaf surface of the created spot coordinate data. Device. (8) The wavefront aberration measuring apparatus according to (7), further comprising display means for displaying the wavefront aberration measured by the wavefront aberration measuring means.

According to the present invention, it is possible to provide a wavefront aberration measuring method and a wavefront aberration measuring apparatus capable of measuring aberration even for a lens having a large pupil that exceeds the visual field range of a Shack-Hartmann sensor, which could not be measured conventionally.

FIG. 3 is a diagram showing a schematic configuration of the apparatus when viewed from the zx plane of the wavefront aberration measuring apparatus in the first embodiment. It is a figure which shows the structure of the vicinity of a Shack-Hartmann sensor when it sees from xy plane of a wavefront aberration measuring apparatus. FIG. 3 is a diagram showing a flowchart of large field of view measurement in the first embodiment. FIG. 4 is a movement image diagram of a sensor when a pupil is divided into nine images by a Shack-Hartmann sensor in the first embodiment. The movement amount (x, y axis) of the sensor stage input to the apparatus interface and the schedule of the movement order are shown. It is an image figure of the spot luminance image imaged based on the input schedule. The result of calculating the spot center of gravity from the captured spot luminance image and calculating the reference coordinates of the spot and the displacement amount from the spot is shown. The value of the laser length measuring device at each imaging position is shown. FIG. 5 is a diagram illustrating a method of calculating a stage error (xy in-plane rotation amount, x, y direction offset amount) from a laser length measuring device value measured when the stage is moved in the first embodiment. It is the figure which showed the calculation method of the x direction offset amount which generate | occur | produces with xy in-plane stage rotation. It is the figure which showed the calculation method of the y direction offset amount generated with xy in-plane stage rotation. FIG. 6 is a diagram illustrating a method of calculating a stage error (zx in-plane rotation amount) from a laser length measuring device value measured during stage movement in the first embodiment. It is the figure which showed the calculation method of the x direction offset amount generated with zx in-plane stage rotation. FIG. 5 is a diagram illustrating a method of calculating a stage error (in-plane rotation amount) from a laser length measuring value measured when the stage is moved in the first embodiment. It is the figure which showed the calculation method of the y direction offset amount generated with a yz in-plane stage rotation. FIG. 6 is a list of offset amounts and rotation amounts of spot positions of Shack-Hartmann sensors calculated from stage movement errors in the first embodiment. It is a figure which shows the positional relationship of the spot coordinate actually imaged, and the ideal coordinate which should be imaged when there is no stage movement error. It is a figure which shows the spot displacement amount in the ideal coordinate derived | led-out by interpolation from the imaged spot coordinate. The data which coordinate-integrated all the data imaged by dividing the visual field is shown. FIG. 3 is a diagram showing an apparatus GUI in the first embodiment. FIG. 10 is a diagram showing a schematic configuration of the apparatus when viewed from the zx plane of the wavefront aberration measuring apparatus in the second embodiment. It is a figure which shows the structure of a line sensor vicinity when it sees from xy plane of a wavefront aberration measuring apparatus. It is a figure which shows the positional relationship of a line sensor and an array lens when it sees from xy plane of a wavefront aberration measuring apparatus. FIG. 10 is a diagram showing a flowchart of large-field measurement in the second embodiment. FIG. 10 is a movement image diagram of a sensor when a line sensor performs one-dimensional scanning on the pupil and picks up an image in the second embodiment. It is a figure which shows the coordinate by which the sensor images ideally. It is an image figure of the spot luminance image imaged based on the input schedule. It is a figure which shows the luminance data of each pixel imaged with the sensor. The value of the laser length measuring device at each imaging position is shown. FIG. 10 is a diagram illustrating a method of calculating a stage error (xy in-plane rotation amount, x, y direction offset amount) from a laser length measuring value measured during stage movement in the second embodiment. It is the figure which showed the calculation method of the x direction offset amount which generate | occur | produces with xy in-plane stage rotation. It is the figure which showed the calculation method of the y direction offset amount generated with xy in-plane stage rotation. FIG. 10 is a diagram illustrating a method of calculating a stage error (zx in-plane rotation amount) from a laser length measuring device value measured during stage movement in the second embodiment. It is the figure which showed the calculation method of the x direction offset amount generated with zx in-plane stage rotation. FIG. 10 is a list of offset amounts and rotation amounts of spot positions of Shack-Hartmann sensors calculated from stage movement errors in the second embodiment. It is a figure which shows the positional relationship of the spot coordinate actually imaged, and the ideal coordinate which should be imaged when there is no stage movement error. It is a figure which shows the spot displacement amount in the ideal coordinate derived | led-out by interpolation from the imaged spot coordinate. FIG. 10 is a diagram showing a method of calculating luminance at ideal coordinates by interpolation from the luminance of coordinates actually captured in the second embodiment. It is the figure which showed the method of determining in which triangle the point which should be interpolated is contained. It is the figure which showed the method of performing brightness | luminance interpolation from coordinate relationship. It is a figure which shows the spot displacement amount in the ideal coordinate derived | led-out by interpolation from the imaged spot coordinate. FIG. 10 is a diagram showing an apparatus GUI in the second embodiment. In the Shack-Hartmann sensor, it is the figure which showed the relationship between an incident wave front, an array lens, and a sensor surface. It is a figure which shows the spot image of a lens. It is a figure which shows a defocus aberration. It is a figure which shows astigmatism. It is a figure which shows a coma aberration. It is a figure which shows spherical aberration.

In a Shack-Hartmann type measuring apparatus that measures the wavefront aberration of an infinite objective lens using a point light source, the aberration is measured in a large field of view by scanning the Shack-Hartmann sensor at the pupil position of the objective lens. The wavefront aberration analysis in a large field of view is performed by correcting the pitching and yawing of the sensor mounting stage during scanning, correcting the focused spot position, and connecting the correction data. Embodiments of the present invention will be described below with reference to the drawings.

A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 is an overall configuration diagram of the present embodiment. FIG. 4A shows a device configuration diagram viewed from the zx plane, and FIG. 4B shows a device configuration diagram of the periphery of the sensor 200 viewed from the top surface of the xy plane. The parallel light emitted from the light source 100 is adjusted in beam diameter by the beam expander 101, bent by the mirror 102, and incident on the condenser lens 103. The light source 100, the beam expander 101, the mirror 102, and the condensing lens 103 are mounted on the xyz stage 104 and have a configuration that can move along the x-axis, the y-axis, and the z-axis. The light emitted from the condensing lens 103 is condensed once, becomes divergent light, and then enters the non-detection lens 400. The non-detecting lens 400 is fixed by a stage 209. The wavefront of the light that has passed through the non-detecting lens 400 is measured by the Shack-Hartmann sensor 200. The Shack-Hartmann sensor 200 is fixed to the xy stage 208 and can be scanned in the xy direction in order to measure the aberration of the entire pupil surface of the non-analyzing lens 400. Laser

length measuring devices

201 and 202 are mounted on the stage 209 to measure the amount of movement of the stage 208 in the x-axis direction, the straightness when moving in the y-axis direction, and the tilt in the zx plane. A mirror 203 is mounted on the stage 208. Laser

length measuring instruments

204, 205, and 206 are mounted on the stage 209 to measure the amount of movement of the stage in the y-axis direction, straightness when moving in the x-axis direction, tilt in the xy plane, and tilt in the yz plane. The length measuring reflection mirror 207 is mounted on the stage 208.

The device input interface 500 inputs a schedule such as a light source position, an imaging position of the Shack-Hartmann sensor, and a moving order from the outside. A light source stage movement command 501 is transmitted to the light source stage controller 300, and the light source stage 104 moves. Next, a sensor stage movement command 502 is transmitted to the sensor stage control device 301, and the sensor stage 208 moves. Next, a sensor imaging command 503 is transmitted to the sensor control device 302, and the sensor 200 performs imaging. Next, a laser length measuring device value recording command 504 is transmitted to the laser length measuring device control device 303, and the values of the laser

length measuring devices

201, 202, 204, 205, 206 are recorded. 502 to 504 are repeatedly executed according to the imaging schedule. Next, in coordinate integration calculation 505, the stage movement error correction is performed on the imaging data using the values of each laser length measuring instrument recorded at each imaging position, and the data obtained by joining the large field of view. Is created. Aberration analysis is performed on the large visual field data, and the result of the analysis is output to the apparatus output interface screen 506.

Fig. 2 shows the details of the flowchart for large-field image integration.

Reference numerals

500, 501, 502, 503, 504, and 506 are the same as those described in FIG. Here, the details of the coordinate integration calculation 505 will be described. In 5051, the center of gravity of the spot is calculated from the spot luminance image captured by the sensor, and the amount of displacement from the reference position of the spot is calculated. In 5052, the yawing amount, pitching amount, and straightness of the stage are calculated from the values of the laser length measuring device, and the offset amount and the rotation amount from the ideal imaging position of the sensor that accompany it are calculated. In 5053, based on the offset and rotation calculated by 5052, the spot displacement at the ideal imaging position when no stage error occurs is calculated by interpolation using the spot displacement calculated in 5051. To do. In 5054, the image pickup positions are connected using the spot displacement amount at the ideal image pickup position calculated by 5053. Thus, 505 coordinate integration calculations are possible.

FIG. 3 is a diagram showing an example of an input imaging schedule, acquired spot displacement data, and recorded laser length measuring device values. FIG. 4A shows a moving image diagram of the sensor when the pupil is imaged by dividing it into nine. Numbers (1) to (9) in the figure indicate the imaging order. FIG. 4B shows the movement coordinates (X, Y) of the sensor stage center input to the apparatus interface based on FIG. FIG. 2C shows an image diagram of a spot luminance image captured based on an input schedule. FIG. 4D shows the result of calculating the center of gravity of the spot from the captured spot luminance image, and calculating the reference coordinates of the spot and the amount of displacement from the spot. Here, the coordinate origin is taken as the sensor center. Each sheet shows data at each imaging position, and nine sets of data are created. FIG. 4 (e) shows the value of the laser length measuring device at each imaging position. In the figure, x1, x2, y1, y2, and y3 respectively correspond to the output values of the laser

length measuring devices

201, 202, 203, 204, 205, and 206 shown in FIG. In addition, although the example which imaged by dividing into 9 was shown here, it is not restricted to this, You may divide | segment and image in arbitrary numbers.

FIG. 4 is a diagram for explaining a method for calculating an offset amount and a rotation amount generated in the xy plane using laser

length measuring devices

202, 205, and 206 as an example. In FIG. 6A, values measured by the laser length measuring device are 202 = x2, 205 = y2, and 206 = y3, respectively. Assume that x ′ and y ′ are the movement amounts of the stage actually moved in response to the stage movement command (X, Y) shown in FIG. The enlarged view of the figure shows the relationship between the laser

length measuring devices

205 and 206 and the rotation amount θ. The amount of rotation in the xy plane is expressed by Equation 6 using y2 and y3 and the mounting interval d between the laser length measuring devices. Further, the amount of movement of the laser length measuring device in the y direction is an average value of y2 and y3 as shown in Equation 7.

FIG. 5B shows the x-direction offset amount generated when the stage rotates, and FIG. 6C shows the y-direction offset amount similarly generated when the stage rotates. The x-direction offset amount Δx and the y-direction offset amount Δy are expressed by

Equations

8 and 9, respectively.

From

Equations

8 and 9, the relationship between the laser length measuring device values x2 and y (average of y2 and y3) and the actual movement amounts x ′ and y ′ of the stage are

Equations

10 and 11.

By solving the simultaneous equations of

Equations

10 and 11, the actual movement amounts x ′ and y ′ of the stage can be obtained from

Equations

12 and 13 from the values x2, y2, and y3 of the laser length measuring device. Become.

The offset amount generated at this time is expressed by

Equations

14 and 15 based on the difference between the stage movement command (X, Y) in FIG. 3B and the actual movement amount (x ′, y ′) of the stage. It can be obtained.

FIG. 5 is a diagram for explaining a calculation method of an offset amount in the xy plane generated by rotation in the zx plane by calculating the rotation amount generated in the zx plane using the laser

length measuring devices

201 and 202. In FIG. 2A, values measured by the laser

length measuring devices

201 and 202 are assumed to be x1 and x2, respectively. The enlarged view of the figure shows the relationship between the laser

length measuring devices

201 and 202 and the rotation amount θ ₂ . rotational amount in zx plane is x1, x2 and, using a mounting distance d ₂ between the laser measurement device, shown as Formula 16.

As shown in FIG. 5B, when the distance between the array lens 210 and the CCD light receiving surface 211 is f, the offset amount in the xy plane is expressed by Equation 17.

FIG. 6 is a diagram for explaining a calculation method of an offset amount in the xy plane generated by the rotation in the yz plane by calculating the rotation amount generated in the yz plane using the laser

length measuring devices

204 and 206. In FIG. 4A, values measured by the laser

length measuring devices

204 and 206 are y1 and y3, respectively. Indicating the amount of rotation theta ₃ the relationship between the laser

length measuring machine

204 and 206 in FIG enlarged view. rotational amount in the yz plane y1, y3 and, using a mounting distance d ₃ between the laser measurement device, shown as Formula 18.

As shown in FIG. 5B, when the distance between the array lens 210 and the CCD light receiving surface 211 is f, the offset amount in the xy plane is expressed by Equation 19.

4, 5, and 6, the rotation amount of the imaging position resulting from the yawing, pitching, and straightness of the stage is expressed by Equation 6, and the offset amounts are expressed by Equation 20 and Equation 21.

FIG. 7 shows the amount of spot displacement at an ideal imaging position with no stage error based on the offset amount and rotation amount obtained above, using the spot displacement amount data shown in FIG. A method of obtaining by interpolation will be shown. The ideal imaging position without any stage error is derived from the offset amount and the rotation amount at each imaging position shown in FIG.

Here, x _off and y _off indicate the offset amount, and θ indicates the rotation amount. X _pos and y _pos indicate spot coordinates actually _captured , and x and y indicate ideal coordinates when there is no stage error. FIG. 4B shows the positional relationship between the captured spot coordinates and ideal coordinates. The black circles in the figure indicate the spot positions actually captured, and the solid line arrows indicate the amount of spot displacement at those positions. A white circle indicates a spot position in ideal coordinates, and a dotted arrow indicates a spot displacement amount at the position. A method of calculating the spot displacement amount at the ideal coordinates by linear interpolation will be described below using the enlarged view of FIG. Assuming that the ideal coordinates of the spot are x and y, it is possible to calculate the x-direction spot displacement by Equation 23 and the y-direction spot displacement by Equation 24 using the spot displacement actually captured at the four surrounding points.

Nine sets of spot displacement data at ideal coordinates are created by the linear interpolation as shown in FIG. By adding the offset of the stage movement command (X, Y) in Fig. 3 (b) to this data (because the origin of the imaging data at each position is at the sensor center) and integrating the coordinates, Fig. 7 It becomes possible to create spot coordinate data in a large visual field shown in (d). For example, by performing Zernike polynomial fitting or the like on this data, it becomes possible to perform wavefront analysis of spherical aberration, coma aberration, astigmatism, spherical aberration, and the like.

FIG. 8 shows a GUI display example of the device output interface 506. The input is the coordinate setting parameter of the light source position and the sensor stage imaging schedule, and the output is the result of wavefront analysis performed in a large field of view. The wavefront aberration as a result of the wavefront analysis may be a gradation of light and shade according to the amount of aberration, or may be displayed in different colors.

Next, a second embodiment of the present invention will be described with reference to FIGS.
FIG. 9 is an overall configuration diagram of the second embodiment. FIG. 4A shows a device configuration diagram viewed from the zx plane, and FIG. 4B shows a device configuration diagram of the periphery of the sensor 212 viewed from the xy plane. The apparatus configuration is similar to the configuration described with reference to FIG. 1, and the description of the same part is omitted, and different parts are mainly described. The main differences are that the sensor is a one-dimensional line sensor 212 and that the array lens 213 is set on the non-detecting lens pupil independently of the sensor. FIG. 4C shows the relationship between the array lens 213 and the line sensor 212 on the pupil plane. The array lens 213 is sized to cover the entire pupil surface. The line sensor 212 captures an image while moving in the y-axis direction with the array lens 213 kept at a constant height away from the focal length of the array lens. With this method, it is possible to measure aberrations in a large field of view. Since the line sensor has only one pixel in the y-axis direction and is not affected by the pitching of the stage in the y-axis direction, the laser length measuring device 204 used in FIG. 1 can be omitted in this configuration.

The device input / output interface and control are also similar to the configuration described in FIG. 1, and the description of the same part is omitted, and different parts will be mainly described below. In particular, since the coordinate integration calculation of 605 in FIG. 9A is different from 505 in FIG. 1A, the details will be described with reference to FIG.

Fig. 10 shows the details of the flowchart for large-field image integration. 600, 601, 602, 603, 604, and 606 are the same as the contents of 500, 501, 502, 503, 504, and 506 in FIGS. Here, details of the coordinate integration calculation 605 will be described. In 6051, an offset amount and a rotation amount of the sensor at each imaging position are calculated from the values measured by the laser length measuring device. In 6052, based on the offset amount and the rotation amount calculated in 6051, luminance data at an ideal imaging position when no stage error occurs is calculated by interpolation from the luminance data obtained by imaging in 603. In 6053, the spot centroid is calculated from the luminance data at the ideal imaging position calculated by 6052, and the spot displacement is calculated. As described above, 605 coordinate integration calculations can be performed.

FIG. 11 is a diagram showing an example of an imaging schedule to be input, acquired spot displacement data, and recorded laser length measuring device values. FIG. 4A shows an image of movement of the sensor when performing stage scanning in the y direction. The center coordinate of the sensor is set to X_pos, data acquisition starts from the y-axis coordinate Ys_pos, images are taken at the movement interval Ds, and acquisition ends at Ye_pos. FIG. 4B shows ideal imaging coordinates obtained based on the schedule of FIG. Here, a column of sensor center coordinates surrounded by a dotted line in the figure is referred to as (X ₀ , Y ₀ ). FIG. 2C shows an image diagram of spot luminance images picked up based on the schedule of FIG. FIG. 4D shows the captured luminance data. FIG. 4 (e) shows the value of the laser length measuring device at each imaging position. In the figure, x1, x2, y2, and y3 respectively correspond to the laser

length measuring devices

201, 202, 205, and 206 shown in FIG.

FIG. 12 is a diagram for explaining a method for calculating an offset amount and a rotation amount generated in the xy plane using, for example, laser

length measuring devices

202, 205, and 206. The same calculation method as that described in FIG. 4 can be applied to this calculation method. In FIG. 12 (a), values measured by the laser

length measuring devices

202, 205, and 206 are x2, y2, and y3, respectively. Assume that the movement amounts of the stage actually moved with respect to the sensor center movement (X ₀ , Y ₀ ) shown in FIG. 11B are x ′ and y ′, and the rotation amount is θ. The enlarged view of the figure shows the relationship between the laser

length measuring devices

205 and 206 and the rotation amount θ. It is possible to obtain the movement amounts x ′ and y ′ of the actual movement of the stage from the values x2, y2 and y3 of the laser length measuring device as in Expressions 25 and 26.

Here, θ and y are obtained by Expression 27 and Expression 28, respectively.

The offset amount generated at this time is given by Equations 29 and 30 based on the difference between the ideal imaging coordinates (X ₀ , Y ₀ ) at the sensor center in FIG. 11B and the actual stage movement amounts (x ′, y ′). It becomes possible to ask.

FIG. 13 is a diagram for explaining a method of calculating the amount of offset in the xy plane generated by the rotation in the zx plane by calculating the amount of rotation generated in the zx plane using the laser

length measuring devices

201 and 202. In FIG. 2A, values measured by the laser

length measuring devices

201 and 202 and the rotation amount θ ₂ . rotational amount in zx plane is x1, x2 and, using a mounting distance d ₂ between the laser measurement device, shown as Formula 31.

As shown in FIG. 5B, when the distance between the array lens 213 and the CCD surface 212 is f, the offset amount in the xy plane is expressed by Equation 32.

12 and 13, the rotation amount of the imaging position resulting from the yawing, pitching, and straightness of the stage is expressed by Equation 27, and the offset amounts are expressed by Equation 33 and Equation 34.

FIG. 14 shows a method of calculating an actually imaged position from an ideal imaged position in a state where there is no stage error based on the offset amount and the rotation amount obtained above. From the list of offset amount and rotation amount at each imaging position shown in FIG.

Here, x _off and y _off indicate the offset amount, and θ indicates the rotation amount. Also, x ₀ and y ₀ indicate ideal coordinates, and x and y indicate coordinates actually captured. FIG. 2B is a diagram showing the relationship between the captured ideal coordinates and the actual captured coordinates. FIG. 11C shows coordinate data actually captured by performing coordinate transformation of Expression 35 with respect to the ideal coordinates in FIG.

FIG. 15 shows an embodiment for calculating the luminance at the ideal coordinates by interpolation from the luminance of the actually captured coordinates. Three-point interpolation is used for interpolation. As shown in Fig. 3 (a), in selecting three points, one triangle corresponding to the value of the grid point of the ideal coordinate and four triangles formed by the four points above and below are candidates, and which triangle has the grid point. It is determined by determining whether it is included. The determination is made based on whether the line segment connecting the center of the triangle and the lattice point intersects the side of the triangle. For example, in the case of the triangles (1, 2), (2, 1), and (2, 2), the center of the triangle is obtained by Equations 36 and 37, respectively.

Next, a method for determining the intersection of line segments will be described with reference to FIG. The shaded portion satisfies y> ax + b. If you move it to the left, y-ax-b> 0. On the other hand, y-ax-b <0 in the case of non-shaded area. The condition that the line segment connecting (x3, y3) and (x4, y4) intersects with the straight line is expressed by Equation 38.

Actually, the equation representing the straight line is Equation 39,

Therefore, when corresponding to Equation 38,

Next, a method for obtaining the luminance of a lattice point from each triangular point including the lattice point found by Equation 40 by linear interpolation will be described with reference to FIG. Linear interpolation is performed by Equation 41.

Here, V represents the luminance vector from the points constituting the triangle to the grid point to be obtained, V1 represents the luminance vector from the points constituting the triangle to other component points, and V2 is already from the points constituting the triangle. The luminance vector to one constituent point is shown. For interpolation, the coefficients α and β may be obtained.
As for the calculation of α and β, a vector projected on the xy coordinates is considered so as to be obtained without including the value of the luminance value z (even if projected, α and β take the same value because they are linear).

Multiplying by W1 from the left gives Formula 43, and multiplying by W2 from the left gives Formula 44.

From equations 43 and 44, α and β are obtained as equations 45 and 46, respectively.

Here, it becomes like Formula 47, Formula 48, Formula 49, Formula 50, Formula 51,

Since the luminance value z is given by Equation 41, Equation 52 is obtained.

As described above, the luminance value of the lattice point included in the triangle is obtained by interpolation.
The center of gravity of the spot is calculated from the obtained luminance image, and the displacement amount of the spot shown in FIG. For example, Zernike polynomial fitting is performed on this data, and wavefront analysis such as spherical aberration, coma aberration, astigmatism, and spherical aberration is performed.

FIG. 16 shows a GUI display example of the device output interface 606. The input is the light source position setting parameter and the line sensor stage movement schedule, and the output is the result of wavefront analysis performed in a large field of view. The wavefront aberration as a result of the wavefront analysis may be a gradation of light and shade according to the amount of aberration, or may be displayed in different colors.

As mentioned above, although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Needless to say. Further, the effects obtained by the representative ones of the inventions disclosed in the present application are summarized as follows.
(1) According to the present invention, it is possible to measure the aberration of a lens having a large pupil that exceeds the visual field range of the Shack-Hartmann sensor, which could not be measured conventionally.
(2) According to the present invention, the wavefront aberration of the lens can be managed, the foreign matter detection sensitivity and the processing shape of the semiconductor optical inspection apparatus and the printed circuit board laser processing apparatus are made uniform, and a plurality of optical components in the semiconductor line The operational efficiency of the inspection apparatus is improved, and the effects of improving the quality of laser processing are obtained.

DESCRIPTION OF SYMBOLS 100 ... Light source, 101 ... Beam expander, 102 ... Mirror, 103 ... Condensing lens, 104 ... Light source xyz stage, 200 ... Shack-Hartmann sensor, 201, 202, 204 , 205, 206 ... laser length measuring device, 203, 207 ... laser length measuring device reflecting mirror, 208 ... xy stage for Shack-Hartmann sensor, 209 ... non-detecting lens fixed stage, 210 ... Array lens, 211 ... Shack-Hartmann sensor light receiving surface, 212 ... Line sensor, 213 ... Array lens, 300 ... xyz stage controller for light source, 301 ... xy stage controller for sensor, 302 ... Shack-Hartmann sensor control device, 303 ... Laser length measuring device control device, 400 ... Non-detection lens, 500 ... Device input interface, 501 ... Xyz stage movement command for light source, 502 ...・ Xy stay for Shack-Hartmann sensor Move command, 503 ... Shack-Hartmann sensor imaging command, 504 ... Laser length measurement value reading command, 505 ... Coordinate integration calculation processing, 5051 ... Spot displacement calculation processing, 5052 ... Stage offset amount , Rotation amount calculation processing, 5053 ... spot displacement calculation processing by interpolation, 5054 ... coordinate integration processing, 506 ... device output interface, 600 ... device input interface, 601 ... xyz stage movement for light source 602 ... Line sensor xy stage move command, 603 ... Line sensor imaging command, 604 ... Laser length measuring device value read command, 605 ... Coordinate integration calculation processing, 6051 ... Stage offset Amount, rotation amount calculation processing, 6052 ... luminance calculation processing by interpolation, 6053 ... spot coordinate calculation processing from luminance, 606 ... device output interface,

Claims

A wavefront aberration measuring method, comprising: moving a Shack-Hartmann sensor in a plane, taking an image, and connecting acquired data to measure aberrations in a field of view greater than that of the Shack-Hartmann sensor.
2. The wavefront according to claim 1, wherein a movement amount and an inclination amount of a stage on which the Shack-Hartmann sensor is mounted are measured, and correction is performed using measurement data obtained by the measurement at the time of joining. Aberration measurement method.
The stitching is performed by using the measured stage movement amount and inclination amount from the spot displacement data at the coordinates imaged by the Shack-Hartmann sensor in a state including stage movement error and inclination error. 3. The wavefront aberration measuring method according to claim 2, wherein spot displacement data at ideal coordinates imaged by the Shack-Hartmann sensor when there is no tilt error is calculated by interpolation.
A wavefront aberration measuring method for measuring the wavefront aberration of a lens having a pupil diameter larger than the visual field of a Shack-Hartmann sensor,
While irradiating the lens with light, the stage equipped with the Shack-Hartmann sensor is scanned at the pupil position of the lens to image a plurality of areas, and a plurality of spot displacement data is calculated from the obtained plurality of spot luminance images. Steps,
Measuring the amount of movement and tilt of the stage by a laser side lengther;
Correcting and connecting the plurality of spot displacement data using the measured movement amount and inclination amount of the stage, and creating spot coordinate data;
Wavefront analysis of the created spot coordinate data to measure the wavefront aberration of the lens;
A wavefront aberration measuring method comprising:
The wavefront aberration measuring method according to claim 4,
In the step of creating the spot coordinate data, spot displacement data at an ideal imaging position is calculated by an interpolation method using the plurality of spot displacement data based on the measured movement amount and tilt amount of the stage. The wavefront aberration measuring method, wherein the spot coordinate data is created using spot displacement data at the calculated ideal imaging position.
The wavefront aberration measuring method according to claim 4 or 5,
In the step of measuring the moving amount and the tilt amount of the stage, the wavefront aberration measuring method is characterized in that the measuring is performed using a plurality of laser side lengthers arranged at different positions.
A wavefront aberration measuring apparatus for measuring a wavefront aberration of a lens,
A light irradiation means for irradiating the lens with light;
A Shack-Hartmann sensor that scans at the pupil position of the lens and images a plurality of areas;
A stage mounted with the Shack-Hartmann sensor for scanning;
Spot displacement data calculating means for calculating a plurality of spot displacement data from a plurality of spot luminance images obtained by imaging a plurality of regions by the Shack-Hartmann sensor;
A laser length measuring device for measuring the amount of movement and tilt of the stage;
A spot for creating spot coordinate data by correcting and joining a plurality of spot displacement data obtained by the spot displacement data calculating means using the moving amount and tilt amount of the stage measured by the laser side length device Coordinate data creation means;
Wavefront aberration measuring means for measuring the wavefront aberration of the lens by performing leaf surface analysis on the created spot coordinate data;
A wavefront aberration measuring apparatus comprising:
The wavefront aberration measuring apparatus according to claim 7,
2. A wavefront aberration measuring apparatus, wherein a plurality of the laser length measuring devices are arranged at different positions.
The wavefront aberration measuring apparatus according to claim 7 or 8,
And display means for displaying the wavefront aberration measured by the wavefront aberration measuring means;
A wavefront aberration measuring apparatus comprising:
The wavefront aberration measuring apparatus according to claim 9, wherein
The wavefront aberration measuring apparatus, wherein the display means also displays an imaging schedule in which the Shack-Hartmann sensor images a plurality of regions.
A one-dimensional line sensor moves on the array lens, picks up an image, arranges acquired luminance data of each line, calculates a spot displacement amount from the arranged luminance data, and measures wavefront aberration on the array lens. And a wavefront aberration measuring method.
The amount of movement and inclination of the stage on which the line sensor is mounted is measured, and correction is performed using measurement data obtained by the previous measurement when arranging the acquired luminance data of each line. The wavefront aberration measuring method according to claim 11.
The acquired luminance data of each line is arranged using the measured stage movement amount and inclination amount from the luminance data of each line imaged by the line sensor in a state including stage movement error and inclination error. 13. The wavefront aberration measuring method according to claim 12, wherein luminance data of each line is calculated by interpolation using ideal coordinates imaged by the line sensor when there is no stage movement error and tilt error.
A wavefront aberration measuring method for measuring the wavefront aberration of a lens,
While irradiating the lens with light, a stage equipped with an array lens and a one-dimensional line sensor is scanned at the pupil position of the lens to capture a plurality of areas, and a plurality of luminance data are obtained from the obtained plurality of spot luminance images. A calculating step;
Measuring the amount of movement and tilt of the stage by a laser side lengther;
Correcting the plurality of luminance data using the measured movement amount and inclination amount of the stage, and calculating luminance data at a plurality of ideal imaging positions;
Using the calculated luminance data at the plurality of ideal imaging positions, spot displacement data at the plurality of ideal imaging positions is calculated, and the spot displacement data at the plurality of ideal imaging positions is connected. To create spot coordinate data,
Wavefront analysis of the created spot coordinate data to measure the wavefront aberration of the lens;
A wavefront aberration measuring method comprising:
A wavefront aberration measuring apparatus for measuring a wavefront aberration of a lens,
A light irradiation means for irradiating the lens with light;
A one-dimensional line sensor that scans at a pupil position of the lens and images a plurality of areas;
An array lens arranged at a pupil position of the lens independently of the one-dimensional line sensor;
A stage for mounting and scanning the one-dimensional line sensor;
Luminance data calculating means for calculating a plurality of luminance data from a plurality of spot luminance images obtained by imaging a plurality of areas by the one-dimensional line sensor;
A laser length measuring device for measuring the amount of movement and tilt of the stage;
The plurality of luminance data obtained by the luminance data calculating means is corrected using the moving amount and the tilt amount of the stage measured by the laser length measuring device, and the luminance data at a plurality of ideal imaging positions is corrected. Means for calculating
Using the calculated luminance data at the plurality of ideal imaging positions, spot displacement data at the plurality of ideal imaging positions is calculated, and the spot displacement data at the plurality of ideal imaging positions is connected. In addition, spot coordinate data creating means for creating spot coordinate data,
Wavefront aberration measuring means for measuring the wavefront aberration of the lens by performing leaf surface analysis on the created spot coordinate data;
A wavefront aberration measuring apparatus comprising:
The wavefront aberration measuring apparatus according to claim 15,
2. The wavefront aberration measuring apparatus according to claim 1, wherein a plurality of the laser side lengthening devices are arranged at different positions.
The wavefront aberration measuring device according to claim 15 or 16,
And display means for displaying the wavefront aberration measured by the wavefront aberration measuring means;
A wavefront aberration measuring apparatus comprising:
The wavefront aberration measuring apparatus according to claim 17,
The wavefront aberration measuring apparatus, wherein the display unit also displays an imaging schedule for imaging a plurality of regions by the one-dimensional line sensor.