JP2001066111A - Position measuring method and device and exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce an error caused by sampling even in the state where a wide visual field is required to be secured, by receiving light generated from an illuminated mark, and by generating plural signals having different phases of sampling, and by determining the position of the mark based on the plural signals. SOLUTION: A stage control system 36 executes movement control of a stage 13 by controlling a driving means 21 based on a control signal outputted from a main control system 37. A detection result of a laser interferometer 20 is supplied from the stage control system 36 to the main control system 37, and the main control system 37 outputs a control signal to the stage control system 36 based on the information. A reticle alignment sensor 31 for detecting an alignment mark formed on a reticle 10, and a wafer alignment sensor 32 for detecting a reference mark on a reference mark member 33 or an alignment mark formed on a wafer 12, are provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a position measuring method and a position measuring device, and more particularly to a position measuring method for measuring a position of an object using a position measuring mark formed on the object such as a semiconductor substrate or a liquid crystal display element. The present invention relates to a position measurement device, an exposure method using the same, and an exposure method.

[0002]

2. Description of the Related Art In the manufacture of semiconductor devices and liquid crystal display devices, various planar technologies are used. In the planar technology, an image of a fine pattern formed on a photomask or a reticle (hereinafter, referred to as a reticle) using an exposure apparatus is converted into a substrate such as a semiconductor wafer or a glass plate coated with a photosensitive agent such as a photoresist. , A wafer).

[0003] The reticle pattern is, for example, a step
The position of the reticle and the position of the wafer are adjusted (aligned) with high accuracy using an exposure apparatus of the AND-repeat method, and the wafer is projected and exposed so as to overlap a pattern already formed on the wafer. In recent years, semiconductor circuits in particular have been required to have higher densities. Therefore, in the alignment of the exposure apparatus, along with the miniaturization of patterns of semiconductor circuits and the like,
There is an increasing demand for more accurate alignment, and various devices have been devised for alignment.

In general, reticle alignment uses exposure light. The reticle alignment method uses a VRA (Visual Reticle Alignment) method that irradiates exposure light onto the alignment mark drawn on the reticle, processes the image data of the alignment mark captured by a CCD camera, etc., and measures the mark position. Etc.

There are the following types of wafer alignment sensors. (1) LSA (Laser Step Alignment) This sensor is a sensor that irradiates a laser beam onto a dot row alignment mark on a wafer and detects the mark position using light diffracted or scattered by the mark. (2) FIA (Field Image Alignment) This sensor irradiates a dot row alignment mark with light having a wide wavelength band using a halogen lamp or the like as a light source, and obtains image data of the alignment mark captured by a CCD camera or the like. This is a sensor that processes and measures the mark position. (3) LIA (Laser Interferometric Alignment) This sensor irradiates a laser beam with a slightly changed frequency on a diffraction grating alignment mark on a wafer from two directions, causes the two generated diffracted lights to interfere with each other, and adjusts the phase. Is a sensor for measuring the position of the alignment mark from.

In these optical alignments,
First, detect and process alignment marks on the reticle.
Measure the position coordinates. Next, the position of the shot to be superimposed is obtained by detecting and processing the alignment mark on the wafer and measuring the position coordinates. Based on these results, the wafer is moved by a wafer stage so that the pattern image of the reticle overlaps the shot position, alignment is performed, and the reticle pattern image is projected and exposed on the wafer.

[0007] Some of the above-mentioned alignment methods are processed after obtaining a one-dimensional image or a two-dimensional image as an alignment signal. For two-dimensional images,
By integrating the mark portion in the direction to be measured, it can be handled as a one-dimensional signal.

[0008] These signals are originally distributed continuously with respect to the position, but are extracted as signals sampled at certain intervals for the sake of signal transmission of the imaging apparatus. For example, as an imaging device,
When an image processing sensor such as a CCD camera or a line sensor is used, since the pixel size is finite, sampling is performed at intervals determined by the pixel size. Ideally, the signal output from the imaging device is desirably sampled by the sampling device at intervals corresponding to the pixel size of the imaging device. The mark position is measured by using an edge detection, a correlation method, or the like with respect to these sampled signals.

In general, the accuracy required for an alignment sensor is extremely high as compared with the minimum resolution unit of an imaging device. Therefore, the position must be finally determined with an accuracy smaller than the sampling interval. Conventionally,
In edge detection and correlation methods, when processing the sampled signal and calculating the final position result,
The resolution between sampling points has been obtained by fitting an appropriate function such as a linear or quadratic function between the sampling points and solving the function. Usually, the finer the sampling interval, the better the accuracy.

On the other hand, if the magnification of the optical system is increased to reduce the sampling interval on the object, the field of view becomes narrow due to the limitation of the number of pixels of the CCD camera. Due to the configuration of the apparatus, the field of view of the sensor must be ensured to some extent depending on conditions such as the size of the alignment mark and the accuracy of pre-alignment (pre-alignment) performed before alignment measurement. Heretofore, in order to simultaneously solve two contradictory propositions of reducing sampling errors as much as possible and securing a wide field of view, the apparatus has been designed with a compromise.

Next, the details of the above-described edge detection processing will be described. FIG. 10 is a diagram for explaining a process when performing edge detection. A typical algorithm for edge detection first finds local maxima and minima by climbing and descending. This is used as the maximum value and the minimum value of the edge. Sampling point P ₁ in the example of FIG. 10 is the maximum value of the edge, the sampling point P ₂ is the minimum value of the edge. After obtaining the maximum value and the minimum value of the edge, the slice level SL is set as, for example, a middle value between them, and the edge positions (mark positions) E ₁ and E _{2 at} positions crossing the slice level.

When the sampling period is increased to some extent, the maximum value and the minimum value of the above-mentioned values vary depending on the relationship between the sampling position and the signal edge position. Therefore, the slice level SL varies, and as a result, the measurement result varies. Further, when the edge positions E ₁ and E ₂ are determined, fitting is performed by using a linear or quadratic function or the like, so that an error also occurs here. Also in the correlation method, depending on the positional relationship between the sampling position and the signal, the mark signal deforms such that the center of gravity is changed, and the measurement result varies. Also in the correlation method, a result having a resolution smaller than the sampling interval is calculated by fitting to a quadratic function or the like, so that an interpolation error also occurs here. Further, conventionally, the shutter speed of the CCD camera is fixed at 16 ms, and the shutter is released four times in one measurement, and the obtained image is added in a direction perpendicular to the scanning direction of the CCD camera, thereby reducing time. The error was reduced by taking the average and canceling the fluctuation of the stage.

[0013]

By the way, the demand for alignment accuracy today has become more severe. For example, taking a semiconductor device as an example, the integration of the semiconductor device has been improved, and a device manufactured with a wiring pitch of about 0.2 μm has been realized at present. It is thought to be done. Under such circumstances, as in the past, the device was designed with a compromise between the two conflicting propositions of reducing sampling errors as much as possible and securing a wide field of view at the same time. Therefore, it has become difficult to perform alignment in accordance with the required accuracy.

The present invention has been made in view of the above circumstances, and reduces the errors due to sampling even in a situation where a wide field of view must be secured, thereby reducing the position measurement error. It is an object to provide a measuring method and a position measuring device.

[0015]

In order to solve the above-mentioned problems, a position measuring method according to the present invention is a position measuring method for measuring the position of a mark formed on an object. The method is characterized in that the generated light is received, a plurality of signals having different sampling phases are generated, and the position of the mark is determined based on the plurality of signals. Further, in the position measurement method according to the present invention, the plurality of signals are divided in a non-measurement direction of a two-dimensional imaging unit that is in a relationship rotated by a predetermined amount relative to an image of the mark on a light receiving surface of the object. It is characterized in that it includes each image signal corresponding to the region that has been set. Further, the position measurement method of the present invention,
The position of the mark includes an average of the position of each mark obtained based on each image signal for each of the divided areas. Further, in the position measuring method according to the present invention, when the predetermined amount is set such that a measurement range in the longitudinal direction of the mark is arranged over a predetermined range in a non-measurement direction of the two-dimensional imaging means, the measurement is performed. One end and the other end of the range are shifted by a predetermined pixel with respect to the measurement direction of the two-dimensional imaging means. Further, in the position measuring method according to the present invention, the predetermined pixel is 1
It is characterized by including pixels. Further, in the position measuring method according to the present invention, the plurality of signals are configured such that a relative position relationship between a light receiving unit that receives light generated from the mark and an image of the mark on the light receiving unit in a predetermined direction is changed. It is characterized by being generated by Further, the position measurement method of the present invention is characterized in that the light receiving section includes one-dimensional imaging means or two-dimensional imaging means. Further, in the position measuring method according to the present invention, the predetermined direction is a measuring direction of the imaging unit. Also,
The position measurement method according to the present invention is characterized in that the position of the mark includes an average of the position of each mark obtained for each of the signals or for each integrated signal obtained by integrating some of the signals. Further, the position measurement method of the present invention is characterized in that the relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving section by the total number of the signals every time the signals are taken. Further, in the position measuring method according to the present invention, the position of the mark is determined based on one composite signal created based on the plurality of signals and having a sampling period smaller than a sampling period of each signal. It is characterized by: Further, the position measuring method of the present invention is characterized in that the combined signal is obtained by combining the signals while shifting the relative positional relationship by an amount of change. Further, the position measuring method of the present invention is characterized in that the plurality of signals are generated while continuously changing the relative positional relationship. Further, the position measurement method of the present invention is characterized in that the relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving section by the total number of the signals every time the signals are taken. An exposure method according to the present invention is characterized in that the mark is formed on a substrate, and a pattern on a mask is exposed on the aligned substrate based on the position information measured by the position measurement method described above.

A position measuring method according to the present invention is a position measuring device for measuring a position of a mark formed on an object, comprising: illuminating means for illuminating the mark with detection light; Signal generating means for receiving the generated light and generating a plurality of signals having different sampling phases; and determining means for determining the position of the mark based on the plurality of signals. . Further, in the position measuring device according to the present invention, the signal generation unit includes a two-dimensional imaging unit, and the two-dimensional imaging unit and the mark image on the two-dimensional imaging unit are relatively rotated by a predetermined amount. The image signals from regions divided in the non-measurement direction of the two-dimensional imaging means have different phases. Further, in the position measuring device according to the present invention, the determining means obtains a position of the mark based on each image signal for each of the divided areas, and obtains an average of the positions of the obtained marks. And Further, in the position measuring device of the present invention, the predetermined amount is:
When the measurement range in the longitudinal direction of the mark is disposed over a predetermined range in the non-measurement direction of the two-dimensional imaging unit, one end and the other end of the measurement range are connected to the two-dimensional imaging unit. It is characterized in that the amount is shifted by a predetermined pixel with respect to the measurement direction. Further, the position measuring device of the present invention is characterized in that the non-measuring direction is a direction orthogonal to the measuring direction of the two-dimensional imaging means. Further, in the position measuring device according to the present invention, the two-dimensional imaging unit is installed such that a line of the image of the mark on the two-dimensional imaging unit rotates by the predetermined amount with respect to an array of imaging elements. It is characterized by. Further, in the position measuring device of the present invention, the signal generation unit includes a light receiving unit, and the signal generation unit determines a relative positional relationship between the light receiving unit and the image of the mark on the light receiving unit in a predetermined direction. By being changed, a plurality of signals having different phases are generated. Further, in the position measuring device according to the present invention, the light receiving unit includes one-dimensional imaging means or two-dimensional imaging means. Further, the position measuring device according to the present invention is characterized in that the predetermined direction is a measuring direction of the imaging unit. Further, in the position measuring device according to the present invention, the determining means obtains the position of the mark for each of the signals, or for each of the integrated signals obtained by integrating some of the signals, and determines the position of each of the obtained marks. It is characterized by finding the average. Further, in the position measuring device according to the present invention, the relative positional relationship is changed by moving a stage on which the object is mounted. Further, the position measurement device of the present invention is characterized in that the relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving unit by the total number of the signals every time the signals are taken. In addition, the position measuring device of the present invention includes the synthesizing unit, wherein the determining unit generates one synthesized signal having a sampling period smaller than a sampling period of each of the signals based on the plurality of signals. , Wherein the determining means determines the position of the mark based on the synthesizing means. Further, the position measuring device of the present invention is characterized in that the synthesized signal is generated by synthesizing the respective signals while shifting the respective signals by an amount of change in the relative positional relationship. Further, the position measuring device of the present invention is characterized in that the signal generating means generates the plurality of signals while continuously changing the relative positional relationship. Further, the position measurement device of the present invention is characterized in that the relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving unit by the total number of the signals every time the signals are taken. Further, in the position measuring device according to the present invention, the object includes at least one of a mask and a substrate. An exposure apparatus according to the present invention is characterized in that the mark is formed on a substrate, and a pattern on a mask is exposed on the aligned substrate based on the position information measured by the position measurement apparatus.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a position measuring method and a position measuring device according to an embodiment of the present invention will be described in detail with reference to the drawings. First Embodiment [Position Measuring Apparatus] First, a position measuring apparatus according to a first embodiment of the present invention to which the position measuring method according to the first embodiment of the present invention is applied will be described. FIG. 1 is a diagram showing a schematic configuration of a position measuring device according to a first embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a light source such as an ultrahigh pressure mercury lamp or an excimer laser. Reference numeral 4 denotes a reflecting mirror that reflects illumination light emitted from the light source 1. Reference numeral 5 denotes a wavelength / wavelength selection filter that passes only light having a wavelength necessary for exposure. Reference numeral 6 denotes a fly-eye integrator 6, which adjusts the illumination light passing through the wavelength selection filter 5 into a light beam having a uniform intensity distribution.

Reference numeral 7 denotes a reticle blind having an opening S.
The illumination range of the illumination light with respect to 0 is adjusted. The wavelength selection filter 5, the fly-eye integrator 6, and the reticle blind 7 are sequentially arranged on the same optical axis C1. Reference numeral 8 denotes a reflecting mirror for bending the optical axis C1, and reference numeral 9 denotes a lens system for irradiating the reticle with illumination light reflected by the reflecting mirror 8.

The reticle 10 is arranged on the optical axis C2 on which the lens system 9 is arranged. On the reticle 10, a shot pattern to be transferred to the wafer 12 described later and an alignment mark for position measurement are formed. Reference numeral 11 denotes a projection optical system arranged on the optical axis C2, which focuses the illumination light transmitted through the reticle 10.

The wafer 12 is a semiconductor substrate such as silicon, and a resist (not shown) is applied to the surface thereof. Reference numeral 13 denotes a stage, which holds the wafer 12 by vacuum suction. The stage 13 has a well-known structure in which a pair of blocks movable in directions perpendicular to each other are stacked. Numeral 21 denotes a driving means such as a motor for moving the stage 13 in a stage movement coordinate system formed by the above-mentioned directions orthogonal to each other. Therefore, when the driving unit 21 moves the stage 13, the shot position on the wafer 12 that overlaps the exposure field of the projection optical system 11 is adjusted.

A movable mirror 14 is fixed at a predetermined position on the stage 13. Reference numeral 20 denotes a laser interferometer, which detects the position of the stage 13 in the stage movement coordinate system by irradiating the movable mirror 14 arranged on the stage 13 with laser light 15. The driving means 21 and the laser interferometer 20 described above are controlled by a stage control system 36. A reference mark member 33 having the same height as the surface of the wafer 12 is fixed at a predetermined position of the stage 13. A mark serving as a reference for alignment is formed on the surface of the reference mark member 33. By measuring the mark, the reference position of the alignment sensor can be determined, and the positional relationship between the stage 13 and the reticle 10 can be measured.

The stage control system 36 controls the movement of the stage 13 by controlling the driving means 21 based on a control signal output from the main control system 37. The stage control system 36 supplies the main control system 37 with the laser interferometer 2.
The detection result of 0 is supplied, and the main control system 37 outputs a control signal to the stage control system 36 based on the information.

The position measuring device according to the present embodiment includes a reticle alignment sensor 31 for detecting an alignment mark formed on the reticle 10 and a reference mark member 3.
3 and a wafer alignment sensor 32 for detecting an alignment mark formed on the wafer 12. The reticle alignment sensor 31 is, for example, a TTR (through-the-reticle) type alignment sensor, and the wafer alignment sensor 32 is an off-axis type alignment sensor.

The TTR reticle alignment sensor 31 is preferably an LSA type alignment sensor using a He-Ne laser or an exposure light alignment type alignment sensor using exposure light. In particular,
The projection optical system 11 is made of KrF (krypton fluoride), ArF
In the case of an (argon fluoride) excimer laser, the difference in wavelength between the He-Ne laser and the KrF or ArF excimer laser is large, so that the exposure light alignment method is preferable in view of the chromatic aberration of the projection optical system 11. . In addition, when the exposure light alignment method is used, there is no need to consider an offset, and there is no need to manage a so-called baseline.

The reticle alignment sensor 31 detects an alignment mark on the reticle 10 using, for example, light having the same wavelength as illumination light (exposure light) from a light source (not shown). The detection origin (for example, the center of the index mark) of the reticle alignment sensor 31 and the optical axis AX of the projection optical system are set in advance.
And the relative position between the center of the circuit pattern area drawn on the reticle and the alignment mark are determined, the alignment mark is detected, and the amount of deviation from the detection origin is determined. The center of the pattern and the optical axis AX of the projection optical system can be aligned. In the exposure light alignment method, the positional relationship can be directly observed by displaying the image on a monitor using an image sensor (for example, a CCD camera).

The wafer alignment sensor 32 is a so-called off-axis alignment sensor separately provided outside the projection optical system 11, and the optical axis of the wafer alignment sensor 32 and the optical axis of the projection optical system 11 on the projection image plane side. And are parallel. Wafer alignment sensor 32
By detecting a reference mark provided on the reference mark member 33 or an alignment mark formed on the wafer 12, a relative position between the detected mark and an index mark formed inside the wafer alignment sensor 32 is detected. Measure the relationship. As the alignment method of the off-axis wafer alignment sensor 32, the above-described FIA method, LSA method, LIA method, or an exposure light alignment method using exposure light can be applied.

At the time of alignment, the reticle alignment sensor 31 and the wafer alignment sensor 32
The position of the alignment mark formed on the wafer 12 is detected using any one of the methods described above, and the pattern formed in the previous step on the shot area of the wafer 12 and the pattern on the reticle 10 are accurately determined based on the detection result. Position.

The mark image formed on the imaging device is sent as an electrical signal to a sampling device (not shown), and is sent as a digital image signal to a processing system (not shown). In the present embodiment, a line sensor or a CCD camera can be used as an imaging device provided in the wafer alignment sensor 32. In the former case, the digital image signal is one-dimensional, and in the latter case, the digital image signal is two-dimensional. . Also,
It is desirable that the sampling period of the digital image signal output from the sampling device match the minimum division unit of the imaging device. By doing so, the resolution of the imaging device can be used efficiently. In this embodiment, a case where a CCD camera is used as an imaging device will be described.

FIG. 2 is a diagram schematically showing the imaging surface of the imaging device. The imaging surface (light receiving surface) L of the imaging device is composed of a large number of pixels. In the present embodiment, these pixels are arranged in a measurement direction (scanning direction) and a non-measurement direction (non-scanning direction) as shown in FIG. Are arranged in a lattice pattern on a plane composed of two axes orthogonal to. That is, pixels are provided at intersections where rows R1 to R5,... And columns G1 to G7,. In this embodiment, rows R1 to R5,.
.. Will be described as an example, but the present invention is not limited to this.

The scanning direction is a direction that determines the order in which light received by each pixel is converted into an electric signal. That is,
When the light received by the pixel in row R1 and column G1 is converted into an electrical signal, the light received by the pixel in row R1 and column G2 is converted into an electrical signal, and the light received by the pixel in row R1 and column G3 is converted to an electrical signal. It is converted into a signal, and so on. When the light received by all the pixels in one row is converted into an electric signal,
Light received by pixels in adjacent rows in the non-scanning direction is converted into an electric signal. In FIG. 2, an electric signal output from each pixel in a certain row is indicated by an arrow. That is, for example, an electric signal output from each pixel arranged in the row R1 is supplied from a signal output terminal (not shown) to the electric signal S1 in FIG.
Is output as An electric signal output from each pixel arranged in the row R2 is output from a signal output terminal (not shown) as a potential signal S2 in FIG. Similarly,
The light received by each pixel in each row is converted into an electric signal and output. The shutter speed of the CCD camera used in the present embodiment is 16 ms.

FIGS. 3A and 3B are schematic views showing an example of the alignment marks formed on the wafer 12, wherein FIG. 3A is a top view and FIG. 3B is a cross-sectional view taken along line AA in FIG. . The alignment marks shown in FIG.
3 is formed. In this embodiment, the alignment mark in which the strip-shaped groove shown in FIG. 3 is formed is considered. However, the present invention is not limited to the case of measuring the alignment mark shown in FIG. Is applicable, for example, in a cross shape.

Next, the positional relationship between the imaging plane L of the imaging device and the image of the alignment mark formed on the wafer 12 will be described. FIGS. 4A and 4B are diagrams for explaining the positional relationship between the imaging surface L of the imaging device and the image of the alignment mark formed on the wafer 12. In FIG. 4A, symbols M1 to M3 indicate images of strip-shaped grooves m1 to m3 forming alignment marks, respectively, and these images M1 to M3 are formed on the imaging surface L. Images M1 to M
3 and the scanning direction of the imaging device are arranged so as to have a predetermined angle in the imaging plane L. In the present embodiment, the image pickup device is rotated with respect to the image of the alignment mark in the image pickup plane L and arranged so as to have the above-mentioned angle. In FIG. 4A, the angle between the longitudinal direction of the images M1 to M3 and the scanning direction of the image pickup device is exaggerated for easy understanding. Is an angle at which each pixel in an adjacent row of the imaging surface L is shifted by about one pixel with respect to the scanning direction in the longitudinal direction.

The above-described wafer alignment sensor 32 can be applied to any of the above-described types of sensors. In this embodiment, the wafer alignment sensor 32 as an FIA alignment sensor will be described as an example.
Reference numeral 35 denotes an alignment control system, which is connected to the reticle alignment sensor 31 and the wafer alignment sensor 32, processes alignment signals output from the alignment sensors 31, 32, and outputs the processed signals to the main control system 37.

In the above configuration, illumination light emitted from a light source 1 such as an ultrahigh pressure mercury lamp or an excimer laser is reflected by a reflecting mirror 4 and enters a wavelength selection filter 5. The wavelength selection filter 5 allows only light having a wavelength necessary for exposure to pass, and the illumination light having passed through the wavelength selection filter 5 is adjusted to a light flux having a uniform intensity distribution by the fly-eye integrator 6 and reaches the reticle blind 7.

The reticle blind 7 changes the size of the opening S to adjust the illumination range on the reticle 10 by the illumination light. The illumination light that has passed through the opening S of the reticle blind 7 is reflected by the reflecting mirror 8 and enters the lens system 9. The lens system 9 forms an image of the opening S of the reticle blind 7 on the reticle 10, and the reticle 10 Is illuminated.

An image of a shot pattern or an alignment mark existing in the illumination range of the reticle 10 is formed on a wafer 12 coated with a resist by a projection optical system 11, whereby a specific area of the reticle 10 The pattern image is exposed. Reticle alignment sensor 31 detects the position of an alignment mark formed on reticle 10, and wafer alignment sensor 32 detects a reference mark position on reference mark member 33 fixed to stage 13 and outputs an alignment signal. This alignment signal is output to alignment control system 35, and a reference position between reticle 10 and stage 13 is set.

Next, the main control system 37 outputs a control signal to the stage control system 36 so that the alignment mark formed on the wafer 12 is detected by the wafer alignment sensor 32. The stage control system 36 drives the stage 13 based on this control signal, and supplies a detection signal output from the laser interferometer 20 to the main control system 37, and controls the main control system 37 by applying feedback. In this way, the main control system 37 controls and moves the stage 13, measures the position of the alignment mark formed on the wafer 12, measures the position of the reticle 10 and the position of the wafer 12, and performs alignment. When the alignment is completed, the shot pattern formed on the reticle 10 is transferred to the resist applied to the wafer 12.

Next, a procedure for determining an alignment mark position from an alignment signal output from the reticle alignment sensor 31 and the wafer alignment sensor 32 will be described in detail. The mark image formed on the imaging device is sent to the sampling device as an electric signal and sent to the processing system as a digital image signal. In addition, it is usually desirable that the sampling period of the digital image signal output from the sampling device match the minimum division unit of the imaging device. By doing so, the resolution of the imaging device can be used efficiently.

[Position Measurement Method] Next, the position measurement method according to the first embodiment of the present invention will be described in detail. FIG.
As shown in (a), in the position measuring device according to the first embodiment of the present invention, the imaging surface L of the imaging device and the image of the alignment mark formed on the wafer 12 are arranged at a predetermined angle. . Therefore, each row R1 to R
.. Output electrical signals S1 to S5,... Having a phase shift corresponding to the angle, to the sampling device.
Here, as shown in FIG. 4B, the relative inclination angle θ between the imaging surface L of the imaging device and the mark image is a predetermined range (used for measurement) in the non-scanning direction (non-measuring direction) of the imaging device. If the pixel range K1 is Y and the shift amount (number of pixels) in the measurement direction is n, a relationship represented by tan θ = n / Y is obtained. Incidentally, in FIG.
The range marked with is the measured range of the alignment mark, and the direction denoted by the symbol K3 is the longitudinal direction of the mark image of the alignment mark. FIG. 5 shows electric signals S1 to S5 output from each row R1 to R5,.
It is a figure showing an example of ....

In FIG. 5, the horizontal axis represents the position in the scanning direction of the imaging device, and the vertical axis represents the reflectance of the light incident on the wafer. In FIG. 5, a portion indicated by reference numeral D1 is a detection result obtained by measuring the mark m1, and portions indicated by reference characters D2 and D3 are detection results obtained by measuring the marks m2 and m3. The marks m1 to m3 in the present embodiment are shown in FIG.
As shown in (b), since a strip-shaped groove is formed in the wafer, the reflectance is high at the portion where no mark is formed and at the bottom of the groove, but the light is incident at the wall of the groove. Since some of the light is not reflected vertically, the overall reflectivity is low. Therefore, two minimum locations appear for one mark. Further, since the longitudinal direction of the images M1 to M3 and the scanning direction of the imaging device are arranged so as to have a predetermined angle in the imaging plane L, the signals output from the elements in each row of the imaging device have a phase shift. Occurs.

In the position measuring method according to the present embodiment, the electric signals obtained from the image pickup device are processed separately according to which row of the image pickup device. Expressed simply, the imaging device is divided into a plurality of regions, and the electric signal output for each region is processed. For example, the electric signal S1 and the electric signal S2 in FIG. 4A belong to the same region, and the electric signal S4 and the electric signal S5 belong to the same region, but are different from the electric signals S1 and S2 and the electric signals S3 and S4. It belongs to the area.

In the present embodiment, first, a process of integrating the electric signal output from each of the above-described regions for each of the regions is performed. To explain this processing in the above example, the electric signal S1 and the electric signal S2 are integrated in the non-measurement direction, and separately from this, the electric signal S3 and the electric signal S4 are integrated in the non-measurement direction. The integrated signal is sent to a sampling device and sampled. Next, with respect to the electric signal subjected to the integration processing and the sampling processing for each region, FIG.
The processing of performing the edge detection described using 0 is performed, or the processing is performed using the correlation method to calculate the position of the mark.
Finally, the average value of the calculation results of the positions of the marks obtained in each area is obtained to obtain the final measurement result.

Thus, in this embodiment,
An electric signal having a phase shift corresponding to the magnitude of the angle is arranged from each row R1 to R5,... Of the imaging surface L of the imaging device and the image of the alignment mark formed on the wafer 12 at a predetermined angle. S1 to S5, ...
Furthermore, the imaging device is divided into a plurality of regions in the non-scanning direction,
After integrating electric signals having a phase shift for each region, sampling is performed to calculate the position of the mark for each region, and finally, an average value of the position of the mark calculated for each region is obtained to obtain the final value. It is the measurement result. Therefore, in the present embodiment, since the error due to the sampling can be reduced, the measurement accuracy of the position of the mark is improved.

In the present embodiment, the above-mentioned predetermined angle is set within the image pickup plane L of the image pickup apparatus.
However, the present invention is not limited to this. For example, an optical member (such as an image rotator or “Dove Prism”) for rotating the image may be provided on the optical path until the image reaches the imaging surface L of the imaging device, and the mark image may be rotated. Furthermore, in the present embodiment, the shutter is released four times in one measurement, the obtained images are integrated, a temporal average is taken, and the fluctuation of the stage is canceled to further reduce the error. Good. Further, in the above-described embodiment, the region in which the imaging apparatus is divided is described as an example including two rows. However, the present invention is not limited to this, and the number of rows constituting the region is arbitrary. Preferably, one area includes one to five rows.

<Second Embodiment> [Position Measuring Apparatus] Next, a position measuring apparatus according to a second embodiment of the present invention to which the position measuring method according to the second embodiment of the present invention is applied will be described. The basic configuration of the position measuring device according to the second embodiment of the present invention is substantially the same as the position measuring device according to the first embodiment of the present invention described with reference to FIG. The position measuring device according to the present embodiment is the first
The difference from the position measurement device according to the embodiment is that the imaging device is rotated and arranged like the imaging device of the first embodiment, and the longitudinal direction of the images M1 to M3 and the scanning direction of the imaging device are within the imaging plane L. The point is that the imaging device is not arranged so as to have a predetermined angle, and the imaging device is arranged so that the longitudinal direction of the images M1 to M3 is perpendicular to the scanning direction of the imaging device.

The positional relationship between the imaging plane L of the imaging device and the image of the alignment mark formed on the wafer 12 is as shown in FIG. FIG. 6 is a diagram for explaining the positional relationship between the imaging plane L of the imaging device and the image of the alignment mark formed on the wafer 12 according to the second embodiment. In the present embodiment, the longitudinal direction of the alignment mark formed on the wafer 12 and the images M1 to M3
The imaging device is arranged such that the longitudinal direction of the imaging device is perpendicular to the scanning direction of the imaging device. In the present embodiment,
The stop position accuracy of the stage 13 is 10 nm, and the pixel size of the pixel of the image device is 300 nm.

In the above-described configuration, the illumination light emitted from the light source 1 such as an ultrahigh pressure mercury lamp or an excimer laser is reflected by the reflecting mirror 4, and the wavelength selection filter 5, the fly-eye integrator, as in the first embodiment. 6. Reaching the reflecting mirror 8 via the reticle blind 7, reflected and incident on the lens system 9, the image of the opening S of the reticle blind 7 is formed on the reticle 10 by the lens system 9, and the reticle 10 The desired area is illuminated. Reticle 1
The image of the shot pattern or the alignment mark existing in the illumination range of 0 is formed on the wafer 12 coated with the resist by the projection optical system 11, and
The pattern image of the reticle 10 is exposed to the second specific region. Reticle alignment sensor 31 detects the position of an alignment mark formed on reticle 10, and wafer alignment sensor 32 detects a reference mark position on reference mark member 33 fixed to stage 13 and outputs an alignment signal. This alignment signal is output to the alignment control system 35, and the reticle 10 and the stage 1
3 is set.

The main control system 37 determines that the alignment mark formed on the wafer 12
Control signal to be detected by the stage control system 36.
Output to The stage control system 36 drives the stage 13 based on the control signal, and also controls the laser interferometer 2.
The detection signal output from 0 is supplied to the main control system 37 and is controlled by applying feedback. In this way, the main control system 37 controls and moves the stage 13, measures the position of the alignment mark formed on the wafer 12, measures the position of the reticle 10 and the position of the wafer 12, and performs alignment. When the alignment is completed, the shot pattern formed on the reticle 10 is transferred to the resist applied to the wafer 12. next,
The procedure for determining the alignment mark position from the alignment signals output from the reticle alignment sensor 31 and the wafer alignment sensor 32 will be described in detail.

[Position Measurement Method] Next, the position measurement method according to the second embodiment of the present invention will be described in detail. FIG.
FIG. 7 is a diagram for explaining a position measurement method according to a second embodiment of the present invention. In the present embodiment, the wafer 12
When measuring the position of the alignment mark formed in the stage, the stage control system 36 moves the stage 13,
An imaging surface L of the imaging device and images M1 to M1 formed on the imaging surface L
The position relative to M3 in the scanning direction of the imaging device is changed. The example shown in FIG. 7 shows the image M for easy understanding.
Although the moving amount of the relative position of the imaging device with respect to the scanning direction with respect to 1 to M3 is shown large, the moving amount of the stage 13 is the amount by which the images M1 to M3 have moved by 1/4 pixel in the scanning direction of the imaging device. Is preferred.

The operation will be specifically described with reference to FIG.
First, as shown in FIG. 7A, when the mark images M1 to M3 have a positional relationship shifted toward the right side of the imaging plane L in the figure, the electric signals output from each row of the imaging apparatus are output to the non- An averaging process is performed by adding the marks in the scanning direction, and the mark image M
An electric signal is obtained when 1 to M3 are at positions closer to the right side of the imaging plane L in the drawing. Hereinafter, the electric signal on which the averaging process has been performed is referred to as an electric signal SS1.

Next, the stage control system 36
Is moved by a predetermined amount, and the relative positions of the imaging surface L of the imaging device and the images M1 to M3 formed on the imaging surface L with respect to the scanning direction of the imaging device are changed to the image M1 of the mark shown in FIG. ~
M3 is changed so as to have a positional relationship based on the center of the imaging plane L. When the positional relationship shown in FIG. 7B is obtained, the stage control system 36 stops the stage 13. Stage 1
3 stops, the averaging process is performed by adding the electric signals output from each row of the imaging device in the non-scanning direction of the imaging device, and the positional relationship in which the mark images M1 to M3 are shifted toward the center of the imaging surface L Obtain the electric signal in the case of Hereinafter, this electric signal is referred to as an electric signal SS2.

Similarly, the stage control system 36 controls the stage 1
3 is moved, and the relative positions of the imaging surface L of the imaging device and the images M1 to M3 formed on the imaging surface L with respect to the scanning direction of the imaging device are changed to the mark images M1 to M1 shown in FIG. M3
Is changed so as to be located on the left side of the imaging plane L.
When the positional relationship shown in FIG. 7C is obtained, the stage control system 36 stops the stage 13, performs an averaging process by adding the electric signals output from each row of the imaging device in the non-scanning direction of the imaging device. , The mark images M1 to M3 are on the imaging surface L
Obtain an electrical signal when located at the center of the. Hereinafter, this electric signal is referred to as an electric signal SS3.

FIG. 8 shows an electric signal obtained by the above processing. FIG. 8 is a diagram illustrating an example of an electric signal obtained by the position measurement method according to the second embodiment of the present invention. In FIG. 8, the horizontal axis represents the position in the scanning direction of the imaging device, and the vertical axis represents the reflectance of light incident on the wafer.
In FIG. 8, a portion indicated by reference numeral DD1 is a detection result obtained by measuring the mark m1, and portions indicated by reference characters DD2 and DD3 are detection results obtained by measuring the marks m2 and m3. The sampling values SS1 to SS3 obtained by the position measurement method according to the present embodiment are signals similar to the signals obtained by the position measurement method according to the first embodiment of the present invention illustrated in FIG. Causes a phase shift. In this embodiment, after obtaining the electric signals SS1 to SS3,..., Each electric signal SS1 to SS3,.

Next, with respect to the electric signal subjected to the integration processing and the sampling processing, the processing for performing the edge detection described with reference to FIG. 10 is performed for each position of the images M1 to M3.
Alternatively, the position of the mark is calculated by performing processing using a correlation method. Finally, the average value of the calculation results of the mark positions obtained for each position is obtained, and the result is used as the final measurement result.

As described above, in this embodiment,
The relative position in the scanning direction between the imaging surface L of the imaging device and the image of the alignment mark formed on the wafer 12 is changed, and electric signals SS1 to SS3,... Having a phase shift at each position, are obtained. After integrating the electric signals having these phase shifts for each position, sampling is performed to calculate the position of the mark for each region, and finally, the average value of the position of the mark calculated for each region is obtained to obtain the final value. It is the measurement result.
Therefore, in the present embodiment, since the error due to the sampling can be reduced, the measurement accuracy of the position of the mark is improved.

In this embodiment, the two-dimensional imaging device is used as the imaging device, and the averaging process is performed by adding the sampling signals output from the respective rows in the non-scanning direction. The imaging device used may be a one-dimensional imaging device. When a one-dimensional imaging device is used, a process of averaging the sum of the sampling signals output from each row in the non-scanning direction is omitted.

In the above embodiment, the stage 13 is stopped to obtain an electric signal for one screen. However, this is a case where a high S / N is sufficiently obtained. When the S / N is low, when obtaining an electric signal for one screen, the S / N can be improved by obtaining electric signals for a plurality of screens, integrating them, and then sampling. For example, to obtain images for eight screens when performing position measurement, the positions of the imaging plane L of the imaging device and the images M1 to M3 are determined, and then images for two screens are obtained. Is first integrated to improve S / N. Then, an electric signal obtained by adding the integrated image in the non-scanning direction of the imaging device is obtained, and then sampling is performed. Then, after moving the stage 13 to shift the relative position between the imaging plane L of the imaging device and the images M1 to M3 by １ ／ pixel in the operation direction, the stage 1
3 is stopped to obtain an image for two screens. Such an operation is repeated until images for eight screens are obtained.

When the stage 13 is moved, the position of the stage 13 is measured by the laser interferometer 20, and the position is corrected for each measurement result of each image. In addition, since the error due to sampling is a periodic function having a period of one pixel at the relative position between the mark images M1 to M3 and the imaging device, the error is reduced by integrating the sampled signal within one pixel. .

In the above embodiment, when obtaining the electric signal, the stage 13 is stopped to obtain an image. However, stopping and stopping the stage 13 causes a decrease in measurement throughput. Therefore, the stage 13 is not stopped when capturing an image,
The stage 13 may be continuously moved so that the relative position in the scanning direction with respect to 1 to M3 changes at a predetermined speed to capture an image. For example, the electric signal output from the imaging signal is NTSC (National Television Standard).
Committee) signal is 1 in 1/30 second from the imaging signal
Since an image for the screen is output, the stage 13 is moved at a speed at which the relative position in the scanning direction between the imaging device and the images M1 to M3 is shifted by 1/8 pixel during 1/30 seconds, and the image is continuously displayed. It may be obtained. When images are continuously obtained, blurring smaller than the pixel size occurs, but the deterioration rate of the position measurement error is small. However, the measurement result of the position in this case is the stage 1 while the image used for the measurement was captured.
The average position of three places.

In the above embodiment, the image pickup apparatus and the images M1 to M3 are moved by moving the stage 13.
To change the relative position in the scanning direction with
The change of the relative position is not limited to that performed by moving the stage (substrate stage or mask stage). For example, an optical member (such as a rubbing or a parallel plate glass) for shifting the images M1 to M3 may be used for the images M1 to M3. Marks M1 to M are provided on the optical path until reaching the imaging surface L of the imaging device.
The image of No. 3 may be shifted. Further, the imaging device may be moved.

Third Embodiment [Position Measuring Apparatus] Next, a position measuring apparatus according to a third embodiment of the present invention to which the position measuring method according to the third embodiment of the present invention is applied will be described. The basic configuration of the position measuring device according to the third embodiment of the present invention is substantially the same as the position measuring device according to the second embodiment of the present invention. The position measuring device according to the present embodiment differs from the position measuring device according to the second embodiment in that an interpolation operation device that performs an interpolation process on a sampling signal is provided.

In the configuration shown in FIG. 1, the process of exposing the pattern image of the reticle 10 on a specific area of the wafer 12 with the illumination light emitted from the light source 1 is the same as in the second embodiment. The present embodiment is characterized in that it has a process of interpolating the obtained sampling signal. Hereinafter, the position measurement method according to the present embodiment will be described in detail.

[Position Measurement Method] Next, the position measurement method according to the second embodiment of the present invention will be described in detail. In the present embodiment, as shown in FIG. 6, the scanning direction of the imaging device and the longitudinal direction of the mark images M1 to M3 are arranged to be perpendicular as in the second embodiment. Then, when obtaining an image, the relative position between the imaging surface L of the imaging device and the images M1 to M3 of the mark in the scanning direction is changed as in the second embodiment. In the second embodiment, after obtaining an image for one screen and adding them in the non-measurement direction to obtain an electric signal, the electric signal is sampled to determine the position of the mark at a certain position. Although the final measurement result was obtained by averaging those positions, in the present embodiment, the sampled electric signal is synthesized without obtaining the position of the mark at a certain position after sampling the electric signal. The difference from the second embodiment is that interpolation is performed.

Hereinafter, a specific description will be given. The process of acquiring an image in the present embodiment is the same as in the second embodiment.
That is, first, as shown in FIG.
When M3 is closer to the right side of the imaging plane L in the figure, the averaging process is performed by adding the electric signals output from the respective rows of the imaging apparatus in the non-scanning direction of the imaging apparatus, and performing averaging processing. An electric signal is obtained when M1 to M3 are at positions closer to the right side of the imaging plane L in the figure. Hereinafter, the electric signal on which the averaging process has been performed is referred to as an electric signal SS1.

Next, the stage control system 36
Is moved by a predetermined amount, and the relative positions of the imaging surface L of the imaging device and the images M1 to M3 formed on the imaging surface L with respect to the scanning direction of the imaging device are changed to the image M1 of the mark shown in FIG. ~
M3 is changed so as to have a positional relationship based on the center of the imaging plane L. When the positional relationship shown in FIG. 7B is obtained, the stage control system 36 stops the stage 13. Stage 1
3 stops, the averaging process is performed by adding the electric signals output from each row of the imaging device in the non-scanning direction of the imaging device, and the positional relationship in which the mark images M1 to M3 are shifted toward the center of the imaging surface L Obtain the electric signal in the case of Hereinafter, this electric signal is referred to as an electric signal SS2.

Similarly, the stage control system 36 controls the stage 1
3 is moved, and the relative positions of the imaging surface L of the imaging device and the images M1 to M3 formed on the imaging surface L with respect to the scanning direction of the imaging device are changed to the mark images M1 to M1 shown in FIG. M3
Is changed so as to be located on the left side of the imaging plane L.
When the positional relationship shown in FIG. 7C is obtained, the stage control system 36 stops the stage 13, performs an averaging process by adding the electric signals output from each row of the imaging device in the non-scanning direction of the imaging device. , The mark images M1 to M3 are on the imaging surface L
Obtain an electrical signal when located at the center of the. Hereinafter, this electric signal is referred to as an electric signal SS3.

By the above processing, the electric signal shown in FIG. 8 is obtained as in the second embodiment. The electric signal obtained by this processing is an electric signal in which a phase shift occurs between the signals as in the second embodiment. Next, when these electric signals SS1 to SS3,... Are obtained, a process of sampling each of the electric signals SS1 to SS3,.

In this embodiment, the electrical signals subjected to the sampling process are combined. Hereinafter, the processing will be described in detail. FIG. 9 is a diagram for explaining an interpolation process used in the position measurement method according to the third embodiment of the present invention. In short, the interpolation process is a process of synthesizing the above-described phase-shifted electric signals to artificially shorten the sampling period. Hereinafter, the method will be described.

FIG. 9 is a diagram for explaining the interpolation processing. In FIG. 9, a part of the signal shown in FIG. 8 is enlarged for easy understanding. Now, sampling is to take place in the same cycle as the minimum periodic component P _s of the image pickup device. That is, each pixel of the image pickup apparatus are arranged at a period P _s in the scanning direction. At this time, the signal SS
1 is sampled at a period P _s. In FIG. 9, points indicated by black circles are sampled values. Similarly, the signal SS2 is also sampled at a period P _s, the sampled values are shown by triangles. Although not shown, the signal SS3～SS5, ... are also sampled in the same periodic P _s.

After sampling, the sampling period is shortened in a pseudo manner by superimposing the sampled signals in the non-scanning direction. In FIG.
An example is shown in which the sampling value of the signal SS1 and the sampling value of the signal SS2 are combined to artificially shorten the sampling period. The black circles and the triangles arranged on the curve with the symbol SA are the synthesis results. Now, assuming that the curve denoted by the symbol SA is a signal obtained when the mark is continuously measured, as shown in the figure, the signal is sampled at a pseudo period P _s ′ shorter than the sampling period P _s. The same result as is obtained. Thus, in the present embodiment, the sampling period is shortened in a pseudo manner.

Next, the processing of performing edge detection described with reference to FIG. 10 or the processing of using a correlation method is performed on the sampled electric signal obtained by performing the synthesis processing described above. Calculate the position. Finally, the average value of the calculation results of the mark positions obtained for each position is obtained, and the result is used as the final measurement result. In this manner, in the present embodiment, the position of the mark is obtained by shortening the sampling period in a pseudo manner, and the position of the mark is used as the final measurement result. Therefore, in the present embodiment, since the error due to the sampling can be reduced, the measurement accuracy of the position of the mark is improved.

Although the third embodiment of the present invention has been described above, the present invention is limited to the third embodiment, and can be freely changed within the scope of the present invention. Further, in the above embodiment, when obtaining the electric signal, the stage 13 is stopped to obtain an image.
Stopping and stopping the measurement causes a decrease in measurement throughput. Therefore, when capturing an image, the stage 13 is not stopped, and the image is captured by moving the stage 13 continuously so that the relative position in the scanning direction between the imaging device and the images M1 to M3 changes at a predetermined speed. You may.

In the above embodiment, the image pickup apparatus and the images M1 to M3 are moved by moving the stage 13.
To change the relative position in the scanning direction with
The change of the relative position is not limited to that performed by moving the stage (substrate stage or mask stage). For example, an optical member (such as a rubbing or a parallel plate glass) for shifting the images M1 to M3 may be used for the images M1 to M3. Marks M1 to M are provided on the optical path until reaching the imaging surface L of the imaging device.
The image of No. 3 may be shifted. Further, the imaging device may be moved.

In the present embodiment, if the stability of the illumination light quantity is a problem, the average luminance may be calculated and corrected for each image. In actual measurement, it is difficult to stop or scan the stage 13 with high accuracy. In such a case, after arranging the obtained data in the order of the position coordinates, an interpolation operation may be performed to obtain a sampling signal having a constant period. As a method of the interpolation calculation, for example, a function of a quadratic or a cubic may be fitted using values of sampling points near a position where interpolation is to be performed.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above embodiments, and can be freely modified within the scope of the present invention. When the position measuring method and position measuring apparatus of the above embodiment are applied to an exposure apparatus, a scanning type exposure apparatus that exposes a pattern of a mask by synchronously moving a mask and a substrate (for example, US Pat.
473, 410). Further, when the position measuring method and position measuring apparatus of the above embodiment are applied to an exposure apparatus, a pattern of the mask is exposed in a state where the mask and the substrate are stationary, and a step and repeat step of sequentially moving the substrate is performed. It can also be applied to a mold type exposure apparatus. Further, when the position measuring method and position measuring apparatus of the above embodiment are applied to an exposure apparatus, the mask and the substrate are brought into close contact with each other without using the projection optical system 11 (see FIG. 1) to expose the pattern of the mask. The present invention can also be applied to a proximity exposure apparatus.

Further, the application of the position measuring method and the position measuring apparatus according to the above-described embodiment or the exposure apparatus to which the method or the apparatus is applied is not limited to semiconductor manufacturing. The present invention can be widely applied to an exposure apparatus for a liquid crystal for exposing a display element pattern and an exposure apparatus used for manufacturing a thin film magnetic head.

The light source 1 used in the above embodiment
(See FIG. 1) for g-line (436 nm) and i-line (365n).
m), KrF excimer laser (248 nm), ArF excimer laser (193 nm), F ₂ laser (157 n)
Not only m) but also charged particle beams such as X-rays and electron guns can be used. For example, when an electron gun is used, a thermionic emission type lanthanum hexaborite (La) is used as the electron gun.
B ₆ ) and tantalum (Ta) can be used.

Further, the magnification of the projection optical system 11 may be not only a reduction system but also any one of an equal magnification and an enlargement system. Projection optical system 1
The 1, using a material which transmits far infrared quartz and fluorite as the glass material when using a far ultraviolet ray such as an excimer laser, the optical system of the catadioptric system or refraction system in the case of using the F ₂ laser or X-ray (A reticle of a reflection type is also used.) When an electron beam is used, an electron optical system including an electron lens and a deflector may be used as an optical system. It goes without saying that the optical path through which the electron gun passes is set to a vacuum state.

Note that the semiconductor device has the functions and functions of the device.
A step of performing performance design, a step of producing a reticle based on this design step, a step of producing a wafer from a silicon material, a step of exposing a reticle pattern to the wafer with the above-described exposure apparatus, and a step of assembling a device (dicing step, bonding Process, including a package process), an inspection step, and the like.

[0081]

As described above, according to the present invention, the error due to sampling can be reduced even in a situation where a wide field of view must be ensured, so that the position measurement error can be reduced as a result. This has the effect.

[Brief description of the drawings]

FIG. 1 is a diagram showing a schematic configuration of a position measuring device according to a first embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating an imaging surface of an imaging device.

FIG. 3 is a schematic diagram illustrating an example of an alignment mark formed on a wafer 12;

FIG. 4 is a diagram for explaining a positional relationship between an imaging surface L of an imaging device and an image of an alignment mark formed on a wafer 12;

FIG. 5 is a diagram illustrating an example of electric signals S1 to S5,... Output from each row R1 to R5,.

FIG. 6 is a diagram for explaining a positional relationship between an imaging surface L of an imaging device and an image of an alignment mark formed on a wafer 12 according to a second embodiment.

FIG. 7 is a diagram for explaining a position measurement method according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating an example of an electric signal obtained by a position measurement method according to a second embodiment of the present invention.

FIG. 9 is a diagram for explaining an interpolation process used in a position measurement method according to a third embodiment of the present invention.

FIG. 10 is a diagram for describing processing when performing edge detection.

[Explanation of symbols]

 Reference Signs List 1 light source 5 wavelength selection filter 6 fly's eye integrator 7 reticle blind 10 reticle 11 projection optical system 12 wafer 13 stage 20 laser interferometer 21 driving means 31 reticle alignment sensor 32 wafer alignment sensor 35 alignment control system 36 stage control system 37 main control system

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F065 AA03 AA07 BB27 CC20 DD00 DD03 DD04 FF04 FF51 GG03 GG04 JJ02 JJ03 JJ19 JJ25 JJ26 LL12 LL22 MM03 PP12 PP23 QQ01 QQ03 QQ14 QQ42 5F046 EB03 FA03 EB03 FA03 EB03 FA03 EB09 FA16 FA17 FB09 FB19 FC04 FC06

Claims (33)

[Claims] 1. A position measuring method for measuring a position of a mark formed on an object, comprising: receiving light generated from the illuminated mark; generating a plurality of signals having different sampling phases; A position measuring method, wherein the position of the mark is determined based on the plurality of signals. 2. The plurality of signals correspond to a region divided in a non-measurement direction of a two-dimensional imaging unit that is rotated by a predetermined amount relative to an image of the mark on a light receiving surface of the object. 2. The method according to claim 1, wherein each image signal is included.
The position measurement method described. 3. The position measuring method according to claim 2, wherein the position of the mark includes an average of the position of each mark obtained based on each image signal for each of the divided areas. 4. When the measurement range in the longitudinal direction of the mark is arranged over a predetermined range in the non-measurement direction of the two-dimensional imaging means, the predetermined amount is different from one end of the measurement range. 4. The position measuring method according to claim 2, wherein the end is shifted by a predetermined pixel with respect to the measurement direction of the two-dimensional imaging unit. 5. The position measuring method according to claim 4, wherein said predetermined pixel includes one pixel. 6. The plurality of signals are generated by changing a relative positional relationship between a light receiving unit that receives light generated from the mark and an image of the mark on the light receiving unit in a predetermined direction. The position measuring method according to claim 1, wherein: 7. The position measuring method according to claim 6, wherein said light receiving section includes one-dimensional imaging means or two-dimensional imaging means. 8. The position measuring method according to claim 7, wherein the predetermined direction is the measurement direction. 9. The apparatus according to claim 6, wherein the position of the mark includes an average of the position of each mark obtained for each of the signals or for each integrated signal obtained by integrating some of the signals. A position measuring method according to claim 8. 10. The apparatus according to claim 6, wherein the relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving unit by the total number of the signals each time the signals are taken. The position measurement method according to any one of the above. 11. The position of the mark is determined based on one composite signal generated based on the plurality of signals and having a sampling period smaller than a sampling period of each signal. The position measuring method according to claim 6. 12. The position measuring method according to claim 11, wherein the synthesized signal is obtained by synthesizing the respective signals while shifting the signals by an amount of change in the relative positional relationship. 13. The system according to claim 6, wherein the plurality of signals are generated while continuously changing the relative positional relationship.
The position measurement method according to claim 12. 14. The apparatus according to claim 6, wherein the relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving unit by the total number of the signals each time the signals are taken. The position measurement method according to any one of the above. 15. The mask is formed on a substrate, and is formed on a mask on a substrate that is aligned based on position information measured by the position measurement method according to any one of claims 1 to 14. An exposure method comprising exposing a pattern. 16. A position measuring device for measuring a position of a mark formed on an object, comprising: an illuminating means for illuminating a detection light on the mark; and receiving light generated from the mark based on the detection light. And a signal generating means for generating a plurality of signals having different sampling phases; and a determining means for determining a position of the mark based on the plurality of signals. 17. The signal generating unit includes a two-dimensional imaging unit, wherein the two-dimensional imaging unit and the image of the mark on the two-dimensional imaging unit are relatively rotated by a predetermined amount,
17. The position measuring apparatus according to claim 16, wherein each image signal from a region divided by the two-dimensional imaging unit in a non-measurement direction has a different phase. 18. The apparatus according to claim 17, wherein said determining means obtains a position of said mark based on each image signal for each of said divided areas, and obtains an average of said obtained position of each mark. The position measuring device as described. 19. The method according to claim 17, wherein the predetermined amount is equal to one end of the measurement range when the measurement range in the longitudinal direction of the mark is arranged over a predetermined range in the non-measurement direction of the two-dimensional imaging unit. 19. The position measuring device according to claim 17, wherein the other end is shifted by a predetermined pixel with respect to the measurement direction of the two-dimensional imaging unit. 20. The position measuring device according to claim 17, wherein the non-measurement direction is a direction orthogonal to a measurement direction of the two-dimensional imaging unit. 21. The two-dimensional imaging means, wherein the line of the image of the mark on the two-dimensional imaging means is installed so as to rotate by the predetermined amount with respect to an array of imaging elements. The position measuring device according to any one of claims 17 to 20. 22. The signal generating unit includes a light receiving unit, wherein the signal generating unit changes a relative positional relationship between the light receiving unit and an image of the mark on the light receiving unit in a predetermined direction. 17. The position measuring device according to claim 16, wherein the plurality of signals having different phases are generated. 23. The position measuring apparatus according to claim 22, wherein said light receiving section includes one-dimensional imaging means or two-dimensional imaging means. 24. The position measuring device according to claim 23, wherein the predetermined direction is the measurement direction. 25. The determining means obtains the position of the mark for each of the signals or for each of the integrated signals obtained by integrating some of the signals, and obtains the average of the obtained positions of the respective marks. Claims 22 to 2 characterized by the above-mentioned.
5. The position measuring device according to any one of 4. 26. The position measuring apparatus according to claim 22, wherein the relative positional relationship is changed by moving a stage on which the object is placed. 27. The relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving unit by the total number of the signals each time the signals are taken.
27. The position measuring device according to claim 26. 28. The determining unit includes a synthesizing unit that creates one synthesized signal having a sampling period smaller than a sampling period of each of the plurality of signals based on the plurality of signals. 23. The position measuring apparatus according to claim 22, wherein the position of the mark is determined based on the combining unit. 29. The composite signal according to claim 28, wherein the composite signal is generated by synthesizing the respective signals while shifting the signals by an amount of change in the relative positional relationship.
The position measuring device as described. 30. The position measurement according to claim 22, wherein said signal generation means generates said plurality of signals while continuously changing said relative positional relationship. apparatus. 31. The relative positional relationship is changed by an amount obtained by dividing one pixel of the light receiving unit by the total number of the signals each time the signals are fetched.
31. The position measuring device according to claim 30. 32. The position measuring apparatus according to claim 16, wherein the object includes at least one of a mask and a substrate. 33. The mark is formed on a substrate, and the mark is formed on a substrate on a substrate which is aligned based on position information measured by the position measuring device according to any one of claims 16 to 32. An exposure apparatus for exposing a pattern.