JP2001217180A - Alignment method, alignment device, aligner and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the time required for alignment of an alignment object. SOLUTION: Characteristic data, showing the relation of optical characteristics between a search measurement system including a camera 56 and a fine measurement system including a camera 58, are stored and held in advance in a memory 67 of a main control system 59. The main control system 59 acquires first illumination data, which are optimum data regarding illumination during search measurement by preliminary detection, for example. After search measurement is executed by illumination according to the first illumination data, the attitude of an object 11 is adjusted based on the result of the search measurement to enable fine measurement, first illumination data is changed according to characteristic data and second illumination data, which are optimum data regarding the illumination during fine measurement is acquired, by changing the first illumination data according to characteristic data, and after fine measurement is executed through illumination in accordance with the second illumination data, the attitude of the object 1 is adjusted so as to match a prescribed reference.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor integrated circuit,
The present invention relates to an alignment method and an alignment apparatus for aligning a mask and the like used when manufacturing a liquid crystal display element, an imaging element, a thin-film magnetic head, and other micro devices using a lithography technique, and an exposure apparatus and an exposure method.

[0002]

2. Description of the Related Art In the manufacture of microdevices, a fine pattern image formed on a photomask or reticle (hereinafter, these are collectively referred to as a reticle) is coated with a photosensitive agent such as a photoresist using an exposure apparatus. Projection exposure on a substrate such as a semiconductor wafer or a glass plate is repeatedly performed. When performing exposure, it is necessary to precisely match the relative position of the pattern formed on the reticle to be projected with the position of the substrate. In order to perform this alignment, alignment marks are respectively formed on the reticle and the substrate. The position of the alignment mark is detected by an alignment sensor, and the relative position is adjusted by adjusting the attitude of the reticle and / or the substrate. Reconcile relationships.

An alignment apparatus for aligning a reticle includes a position measuring system including an alignment sensor (for example, an image pickup device such as a CCD) for measuring the position of an alignment mark formed on the reticle, and an alignment detected by the alignment sensor. And a posture adjustment system for positioning the reticle based on the position of the mark.

In general, a position measuring system is a fine measuring system that performs fine (precision) measurement of the position of an alignment mark at a high magnification in order to perform a precise alignment (fine alignment) of a reticle, and a fine measuring system prior to the fine measurement by the fine measuring system. A search measurement system that performs rough (coarse) measurement of the alignment mark at a low magnification (also referred to as search measurement) in order to perform relatively coarse alignment (search alignment) so that the alignment mark can be measured by the fine measurement system. And

The reason why the fine alignment is performed after the search alignment is performed is as follows.
That is, since the alignment sensor of the fine measurement system has a high magnification, it is difficult to obtain a wide field of view. In addition, in order to avoid the influence of aberrations (distortion, etc.) of the optical system, measurement is performed without moving the position of the alignment mark. It is desirable to do. Therefore, after performing a rough alignment using a search measurement system having a relatively large magnification and a wide field of view, it is necessary to perform accurate and precise alignment.
This is because it is advantageous in terms of accuracy or speed. At present, the accuracy of search alignment is about 1 μm, and the precision of fine alignment is about 1 nm.

As described above, the search measurement system for search alignment and the fine measurement system for fine alignment differ in the required accuracy and the size of the field of view.
The magnification of the optical system used for each measurement and the sensitivity of the alignment sensor are different, so the optimum illumination power when measuring the alignment mark using the search measurement system and the optimum illumination power when measuring using the fine measurement system The optimal lighting power is different.

Therefore, conventionally, before performing the search measurement, the alignment mark is illuminated with an appropriate illumination power using the search measurement system, and preliminary detection (trial hitting) for obtaining a detection value by the search measurement system is performed. Then, based on this, the optimum illumination power for the search measurement is obtained, and then the search alignment is performed. Next, before performing the fine measurement, the alignment mark is illuminated with an appropriate illumination power using the fine measurement system, and preliminary detection (test hitting) for obtaining a detection value by the fine measurement system is performed again. On the basis of this, the optimum illumination power for fine measurement was obtained, and then fine alignment was performed.

[0008]

As described above, in the prior art, before performing search measurement for search alignment, the optimum illumination power for the search measurement is preliminarily detected, and fine alignment is performed. Before performing the fine measurement, the optimal illumination power for the fine measurement is preliminarily detected, and the preliminary detection, that is, the illumination by the illumination light, the detection by the alignment sensor, and the optimal illumination based on the detection result are performed. Processing such as power calculation must be performed twice, and it takes a long time to complete the alignment of the reticle, which has been one of the causes of a decrease in throughput (productivity).

The present invention has been made in view of the above problems, and has as its object to reduce the time required for alignment of an alignment object such as a reticle including search alignment and fine alignment, and to improve throughput. I do.

[0010]

Hereinafter, in the examples shown in this section, for ease of understanding, each constituent element of the present invention will be described with typical reference numerals shown in the drawings of the embodiments. The configuration of the present invention or each component requirement is not limited to those restricted by these reference numerals.

An alignment method according to the present invention for solving the above-described problems is directed to an object (for example, a mask or a substrate).
An alignment method for measuring the position of a mark (RMA, RMB) formed in (11) and aligning the object, wherein the first measurement system (51, 52, 53, 54) for rough measuring the mark. , 55, 56) and a second measurement system (51, 52, 57, 58) that performs fine measurement of the mark more accurately than rough measurement; A step (ST10) of acquiring first illumination data, which is optimal data relating to illumination at the time of rough measurement, and a step (ST12) of performing illumination and rough measurement according to the first illumination data;
Adjusting the posture of the object based on the result of the rough measurement so that fine measurement can be performed (ST13).
And a step (ST14) of converting the first illumination data according to the characteristic data to obtain second illumination data that is optimal data regarding illumination at the time of fine measurement, and performing fine measurement by illuminating according to the second illumination data. (ST15).

The alignment apparatus according to the present invention for solving the above-mentioned problem measures the position of a mark (RMA, RMB) formed on an object (for example, a mask or a substrate) (11) and measures the position of the object. An alignment apparatus for performing alignment of an object, comprising: an attitude adjustment apparatus (15, 18) for adjusting the attitude of the object; and a first measurement system (51, 52, 53, 54, 55, 55) for rough measuring the mark. 56)
A second measurement system (51, 5) for finely measuring the mark
2, 57, 58), a storage device (67) storing characteristic data indicating a relationship between optical characteristics between the first measurement system and the second measurement system, and optimal data relating to illumination during rough measurement. After obtaining the first illumination data and performing rough measurement by illuminating according to the first illumination data, the attitude adjustment device is controlled based on the result of the rough measurement to finely measure the attitude of the object. Adjustment is made as much as possible, and the optimal data relating to the illumination at the time of the rough measurement is converted according to the characteristic data to obtain second illumination data which is the optimal data at the time of the fine measurement. After performing the measurement, the control device (59) controls the posture adjustment device based on the result of the fine measurement, and adjusts the posture of the object so as to match the posture of the object to a predetermined reference. Characterized by comprising a and.

According to the present invention, the optimal data (first illumination data) relating to the illumination used in the fine measurement is converted in accordance with the characteristic data acquired in advance to obtain the optimal data (second illumination) relating to the illumination used in the rough measurement. Data), so as to obtain the optimal data on the illumination in the fine measurement at the time of the fine measurement as in the related art, based on the preliminary detection (illumination with the illumination light, detection by the alignment sensor, and the detection result based on the detection result). Since it is not necessary to carry out calculation and only simple calculation processing, fine measurement can be performed immediately after performing rough measurement, and thus the time required for alignment is reduced.

The optimal data (first illumination data, second illumination data) relating to the illumination is light power, illuminance, energy, or a physical quantity corresponding thereto, and the characteristic data is, specifically, the first data. And data on at least one of magnification, numerical aperture, and sensitivity of the second measurement system. The method of acquiring the first illumination data is not particularly limited, but can be obtained from a result measured by the first measurement system by preliminary illuminating the mark before the rough measurement. The reflectance of the alignment mark may be determined in advance, and the first illumination data may be determined based on the data.

According to the present invention, there is provided an exposure apparatus for exposing and transferring an image of a pattern formed on a mask onto a photosensitive substrate, wherein the exposure apparatus aligns at least one of the mask and the photosensitive substrate. The apparatus includes the above-described alignment apparatus. According to the present invention, the alignment of the reticle can be completed in a short time, so that it is possible to promptly shift to the exposure processing and improve the throughput (productivity).

According to the exposure method of the present invention for solving the above-mentioned problems, a mask on which a pattern is formed is aligned using the alignment method, and an image of the pattern formed on the aligned mask is exposed. Exposure transfer to substrate. According to the present invention, the same functions and effects as those of the above-described exposure apparatus of the present invention can be obtained.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on embodiments shown in the drawings.

FIG. 1 is an overall configuration diagram of a projection exposure apparatus according to an embodiment of the present invention, FIG. 2 is a schematic configuration diagram of an alignment system, and FIG. 3 is a detailed configuration diagram of an alignment system. FIGS. 4A and 4B are diagrams showing the images of the reticle alignment mark and the reference mark formed on the light receiving surface of the measuring camera and the photoelectric conversion signals thereof. FIG. 5 is a flowchart showing the alignment processing by the main control system.

As shown in FIG. 1, this exposure apparatus 30
This is a so-called step-and-scan type exposure apparatus in which a part of a pattern on a reticle 11 as a mask is reduced and projected through a projection optical system 13 onto a wafer 14 coated with a resist as a photosensitive substrate. By moving the reticle 11 and the wafer 14 synchronously with respect to the projection optical system 13, a reduced image of the pattern on the reticle 11 is sequentially transferred to each shot area of the wafer 14.

The exposure apparatus 30 uses K
An rF excimer laser (oscillation wavelength: 248 nm) is provided. The illumination light source 1 is not particularly limited, and may be a g-line (43
6 nm), i-ray (365 nm), ArF excimer laser (193nm), _{F 2} laser (157 nm), Ar
₂ excimer laser (wavelength 126 nm) or the like can be employed.

The laser beam LB pulsed from the exposure light source 1 enters the beam shaping / modulating optical system 2.
In this embodiment, the beam shaping / modulating optical system 2 includes a beam shaping optical system 2a and an energy modulator 2b. The beam shaping optical system 2a includes a cylinder lens, a beam expander, and the like, and the cross-sectional shape of the beam is shaped so as to efficiently enter the subsequent fly-eye lens 5.

The energy modulator 2b is composed of an energy coarse adjuster and an energy fine adjuster. The energy coarse adjuster has a transmittance (= (1) on a rotatable revolver.
A plurality of ND filters having different light attenuation rates) × 100 (%) are arranged, and the transmittance of the incident laser beam LB is switched from 100% in a plurality of steps by rotating the revolver. Is available. Note that a revolver similar to the revolver
The transmittance may be adjusted more finely by combining two sets of ND filters by arranging the ND filters. on the other hand,
The energy fine adjuster is a double grating method or a method in which two parallel flat glass plates with variable inclination angles are combined, and the like, and continuously and finely adjusts the transmittance of the laser beam LB within a predetermined range. However, instead of using this energy fine adjuster, the energy of the laser beam LB may be finely adjusted by the output modulation of the excimer laser light source 1.

The laser beam LB emitted from the beam shaping / modulating optical system 2 enters the fly-eye lens 5 via a mirror M for bending the optical path. Fly eye lens 5
Forms a number of secondary light sources to illuminate the subsequent reticle 11 with a uniform illumination distribution. Instead of the fly-eye lens 5, an optical integrator (homogenizer) such as a rod integrator can be adopted.

An aperture stop (so-called σ stop) 6 of an illumination system is arranged on the exit surface of the fly-eye lens 5, and a laser beam (hereinafter, “pulse illumination”) emitted from a secondary light source in the aperture stop 6 is provided. The light IL) is incident on the beam splitter 7 having a low reflectance and a high transmittance, and the pulse illumination light IL transmitted through the beam splitter 7 is incident on the condenser lens 10 via the relay lens 8.

The relay lens 8 includes a first relay lens 8A
, A second relay lens 8B, and these lenses 8A, 8B
It has a fixed illumination field stop (fixed reticle blind) 9A and a movable illumination field stop 9B interposed therebetween.

The fixed illumination field stop 9 A has a rectangular opening, and the pulse illumination light IL transmitted through the beam splitter 7.
Is a fixed illumination field stop 9A through a first relay lens 8A.
Through the rectangular opening. The fixed illumination field stop 9A is arranged near a conjugate plane with respect to the pattern surface of the reticle. The movable illumination field stop 9B has an opening whose position and width in the scanning direction are variable,
It is arranged near the fixed illumination field stop 9A. By further restricting the illumination field via the movable illumination field stop 9B at the start and end of the scanning exposure, exposure of unnecessary portions (other than the shot area on the wafer where the reticle pattern is transferred) is prevented. It has become.

The pulse illumination light IL that has passed through the fixed illumination field stop 9A and the movable illumination field stop 9B passes through the second relay lens 8B and the condenser lens 10, and has a rectangular illumination on the reticle 11 held on the reticle stage 15. The region 12R is illuminated with a uniform illuminance distribution. An image obtained by reducing the pattern in the illumination area 12R on the reticle 11 at a projection magnification α (α is, for example, ４ ，, ５, etc.) via the projection optical system 13 is converted to a wafer (photosensitive substrate) coated with a photoresist. ) 14 are projected and exposed to the illumination field field 12W. Hereinafter, the Z axis is taken in parallel with the optical axis AX of the projection optical system 13, and the scanning direction of the reticle 11 with respect to the illumination region 12R (that is, the direction parallel to the plane of FIG. 1) in a plane perpendicular to the optical axis AX. The Y direction and a non-scanning direction perpendicular to the scanning direction will be described as an X direction.

At this time, the reticle stage 15 is scanned in the Y direction by the reticle stage driving section 18. The Y coordinate of the reticle stage 15 measured by the external laser interferometer 16 is supplied to the stage controller 17,
The stage controller 17 controls the position and speed of the reticle stage 15 via the reticle stage driving unit 18 based on the supplied coordinates.

On the other hand, the wafer 14 is placed on a wafer stage 28 via a wafer holder (not shown). The wafer stage 28 has a Z tilt stage 19 and an XY stage 20 on which the Z tilt stage 19 is mounted.
The XY stage 20 positions the wafer 14 in the X direction and the Y direction, and scans the wafer 14 in the Y direction.

The Z tilt stage 19 moves the Z
Direction position (focus position)
It has a function of adjusting the inclination angle of the wafer 14 with respect to the Y plane. The moving mirror fixed on the Z tilt stage 19 and the X and Y coordinates of the XY stage 20 (wafer 14) measured by the external laser interferometer 22 are supplied to the stage controller 17, and the stage controller 1
7 controls the position and speed of the XY stage 20 via the wafer stage drive unit 23 based on the supplied coordinates.

The operation of the stage controller 17 is controlled by a main control system (not shown) which controls the entire apparatus. At the time of scanning exposure, the reticle 11 is moved through the reticle stage 15 in the + Y direction (or the −Y direction).
Synchronization to be scanned at a speed _{V R} in, via the XY stage 20 wafer 14 -Y direction with respect to the illumination field field 12W (or + Y direction) in velocity alpha · V
Scanning is performed at _R (α is a projection magnification from the reticle 11 to the wafer 14).

An uneven illuminance sensor 21 made of a photoelectric conversion element is permanently provided near the wafer 14 on the Z tilt stage 19, and the light receiving surface of the uneven illuminance sensor 21 is set at the same height as the surface of the wafer 14. As the uneven illuminance sensor 21, a PIN-type photodiode or the like having sensitivity in far ultraviolet and having a high response frequency for detecting pulsed illumination light can be used. A detection signal of the uneven illuminance sensor 21 is supplied to an exposure controller 26 via a peak hold circuit (not shown) and an analog / digital (A / D) converter.

The pulsed illumination light IL reflected by the beam splitter 7 is received by an integrator sensor 25 composed of a photoelectric conversion element via a condenser lens 24, and the photoelectric conversion signal of the integrator sensor 25 has a peak (not shown). The output DS is supplied to the exposure controller 26 via the hold circuit and the A / D converter. The correlation coefficient between the output DS of the integrator sensor 25 and the illuminance (exposure amount) of the pulse illumination light IL on the surface of the wafer 14 is obtained in advance and stored in the exposure controller 26. The exposure controller 26 controls the light emission timing and the light emission power of the illumination light source 1 by supplying the control information TS to the illumination light source 1. The exposure controller 26 further controls the dimming rate in the energy modulator 2b, and the stage controller 17 controls the opening and closing operation of the movable illumination field stop 9B in synchronization with the operation information of the stage system.

Next, an alignment system (alignment apparatus) of the projection exposure apparatus will be described with reference to FIGS.

Above the wafer stage 28, an off-axis type wafer alignment microscope 42 is fixed to the projection optical system 13. On the other hand, above the reticle 11, a TTR (Through The Reticle)
Pair of reticle alignment microscopes 43A, 43
B is arranged. On the wafer stage 28, a fiducial mark plate 40 on which fiducial marks RMA, RMB for a reticle alignment microscope and a fiducial mark 41 for a wafer alignment microscope are formed.
Has been fixed.

The wafer alignment microscope 42 can measure the positions of a wafer alignment mark (hereinafter, a wafer mark) WM formed on the wafer 14 and a reference mark 41 formed on the reference mark plate 40. Although not shown, an index serving as a reference when measuring a mark is provided inside the wafer alignment microscope 42.

Outside a region (pattern region) where the pattern of the reticle 11 is formed, a pair of reticle alignment marks (hereinafter, reticle marks) RMA and RMB observable by the reticle alignment microscopes 43A and 43B. Is formed. By observing these and the pair of reference marks FMA and FMB formed on the reference mark plate 40 on the wafer stage 28 at the same time, the reticle marks RMA and RMB of the reticle R and the reference marks FMA and RMB on the wafer stage 28 are obtained. Alignment with FMB can be performed.

Reference mark plate 40 on wafer stage 28
The positional relationship between the reticle alignment microscope reference marks FMA and FMB formed on the wafer and the wafer alignment microscope reference mark 41 is accurately measured in advance.
Remembered.

The reticle alignment microscope 43A is configured as shown in FIG. The reticle alignment microscope 43B has the same configuration as the reticle alignment microscope 43A, and is not shown in FIG. The reticle alignment microscope 43A includes a search measurement system (first measurement system) for performing relatively rough (coarse) measurement and a fine measurement system (first measurement system) for performing relatively fine (precision) measurement. 2 measurement systems) and an illumination system for alignment.

The search measurement system includes a search optical system including a deflection mirror 51, a first objective lens 52, a half mirror 53, a deflection mirror 54, a second objective lens 55, and the like, and a search measurement camera 56. The fine measurement system includes a deflection mirror 51, a first objective lens 52, and a second objective lens 57.
And the like, and a fine optical system including a fine optical system. As the search measurement camera 56 and the fine measurement camera 58, an image sensor such as a CCD can be used. In this embodiment, a low-sensitivity camera is used as the search measurement camera 56 and the fine measurement camera 5 is used.
As 8, one having high sensitivity is used. The search optical system has a low magnification and a small numerical aperture (NA), and the fine optical system has a high magnification and a large numerical aperture.

Detection signals (photoelectric conversion signals) from the search measurement camera 56 and the fine measurement camera 58 are supplied to a main control system (control device) 59. The main control system 59 is a device that controls the entire exposure apparatus, and a memory (storage device) 67 for storing and holding various programs and data, and for an operator to input various commands and data. (Input / output device) 68 and the like.

The alignment illumination system selectively emits illumination light IL emitted from the illumination light source 1 and whose energy, illuminance distribution and the like have been adjusted by the illumination optical system from the optical path of the illumination optical system. As illumination light for
The illumination system is for illuminating the reticle mark RMA and the reference mark FMA.
3, including an imaging lens 64, a deflection mirror 65, and the like, and is connected to a fine optical system and a search optical system by a half mirror 66.

The movable mirror 62 is a mirror provided between the fly-eye lens 5 and the beam splitter 7 of the illumination optical system shown in FIG. 1 for switching the optical path of the illumination light IL, and reflects the illumination light IL. Movable between a first position at which the illumination light IL is not reflected and a second position at which the illumination light IL is reflected,
When the movable mirror 62 is at the first position, an optical path for wafer exposure is obtained, and when the movable mirror is at the second position, an optical path for alignment measurement is obtained. The position of the movable mirror 62 is selected by the main control system 59.

When performing the alignment, the main control system 59
, The movable mirror 62 is set to the second position, the energy and frequency of the illumination light source 1 are set appropriately, and the light emission is started after the extinction rate in the energy modulator 2b is set appropriately. The illumination light reflected by the movable mirror 62 illuminates the reticle mark RMA of the reticle 11 and its vicinity through the alignment illumination systems 63, 64, 65, 66, 53, 52, and 51 as illumination light for alignment. . The illumination light further illuminates the reference mark (FMA) on the reference mark plate 40 and its vicinity via the projection optical system 13.

The light reflected by the reticle 11 and the reference mark plate 40 is incident on a search measuring camera 56 via search optical systems 51, 52, 53, 54 and 55, and the images of the reticle mark RMA and the reference mark FMA are formed. At the same time, an image is formed on the light receiving surface of the search measurement camera 56. The reflected light from the reticle 11 and the reference mark plate 40 is transmitted to the fine measurement camera 58 via the fine optical systems 51, 52 and 57.
Reticle mark RMA and reference mark FM
The image of A is simultaneously formed on the light receiving surface of the camera 58 for fine measurement.

FIGS. 4A and 4B show a reticle mark RMA and a reference mark FMA simultaneously formed on the light receiving surface of the search measurement camera 56 or the fine measurement camera 58.
FIG. 4 is a diagram showing an image of the image and its photoelectric conversion signal.

The specific shapes of the reticle mark RMA and the reference mark FMA are not particularly limited, but are a combination of marks that can detect the amount of positional displacement in a two-dimensional direction as shown in FIG. Is preferred.

FIG. 4A shows an example in which a rectangular reticle mark RMA is arranged inside a stripe-shaped reference mark FMA arranged on all sides. In FIG. 4 (B), reference marks FMA in which mutually perpendicular stripes are formed in a cross shape are arranged inside, and striped reticle marks RMA are arranged outside the reference marks FMA. . Reticle mark RMB has the same shape as reticle mark RMA, and reference mark FMB has the same shape as reference mark FMA.

As described above, in the search measurement camera 56 or the fine measurement camera 58 of each of the pair of reticle alignment microscopes 43A and 43B, the image of the reticle mark RMA and the image of the reference mark FMA, and the image of the reticle mark RMB and the reference The images of the mark FMB are simultaneously observed, and as shown in FIGS. 4A and 4B, a photoelectric conversion signal is detected in a two-dimensional direction, supplied to the main control system 59, and supplied to the main control system 59. But these marks RMA and FMA, R
The amount of displacement between MB and FMB is calculated.

The data on the positional deviation between the marks obtained by the main control system 59 is sent from the main control system 59 to the stage controller 17 so that the reticle 11 and the wafer 14 are accurately aligned. The position and orientation of 11 (and / or wafer 14) are adjusted.

FIG. 5 is a flowchart showing a schematic flow of the alignment processing by the main control system. The processing characteristic of the present invention will be described below.

The reticle 11 is conveyed by a reticle loader (not shown), and after being pre-aligned for roughly positioning the reticle 11 on the basis of the outer shape on the way, the reticle 11 is carried into the reticle stage 15 and held by negative pressure suction. . Thereafter, the search alignment process and the fine alignment process are started.

Prior to the alignment process,
In the memory 67 of the main control system 59, characteristic data is previously obtained and stored. The characteristic data is data indicating the relationship between the optical characteristics between the search measurement system and the fine measurement system (in this embodiment, the relationship between the optimum illumination power), and can be obtained as follows.

That is, for the search measurement system, the optimum illumination power is Ps, the characteristics of the optical system such as magnification and numerical aperture are Es, the sensitivity of the search measurement camera 56 is Rs, and the optimum illumination power is Pf for the fine measurement system. Assuming that the characteristics of the optical system such as magnification and numerical aperture are Ef, the sensitivity of the fine measurement camera 58 is Rf, and the appropriate values of the signal outputs of the search measurement camera 56 and the fine measurement camera 58 are the same, The following relationship exists between these parameters.

Ps × Es × Rs = Pf × Ef × Rf (1) In equation (1), since Es, Rs, Ef, and Rf are known, the relationship between Ps and Pf is given by the following equation (2). You can ask.

Pf = Ps × Es × Rs / (Ef × Rf) (2) The characteristic data is the relational expression (2) or an expression corresponding thereto and specific numerical values of the respective values Es, Rs, Ef, and Rf. Except for Ps and Pf, data other than Ps and Pf are input in advance by an operator using a console 68 provided in the main control system 59 and stored in the memory 67.

The alignment processing by the main control system 59 is performed as follows. That is, the main control system 59 performs the optimal illumination data acquisition processing of the search alignment (S
T10). This process is a process for obtaining the optimum illumination power (light energy per unit time) of the alignment illumination light at the time of performing the search measurement. In this embodiment, the process is performed by trial hitting. That is, the main control system 59 sets the movable mirror 62 to the second position, sets the dimming rate in the energy modulator 2b to a predetermined appropriate value, and starts illumination by the illumination light source 1. .

Next, when the detection value of the search measurement camera 56 under this illumination exceeds a predetermined upper limit, the illumination power is reduced. When the detection value is less than the predetermined lower limit, the illumination power is reduced. Is controlled to adjust the light attenuation rate in the energy modulator 2b. Search measurement camera 5
If the detected value of No. 6 falls within the predetermined upper and lower limit values, an optimum illumination power (Ps) for search measurement is calculated based on the detected value. Here, the optimum illumination power for the search measurement is an optical power that outputs the most appropriate detection value for the performance of the search measurement camera 56 in discriminating the mark.

Thereafter, the obtained optimum illumination power is stored and held in the memory 67 as optimum illumination data (first illumination data) for search measurement (ST11), and energy modulation is performed according to the optimum illumination data for search measurement. The dimming rate in the device 2b is controlled and adjusted so that the illumination light has the optimal illumination power for the search measurement. The reticle marks RMA, RMB and the reference marks F based on the detection values of the search measurement camera 56 under this illumination.
The positions of MA and FMB are obtained (ST12), and the corresponding marks RMA, FMA and RMB are determined based on the measurement results.
In order to minimize the amount of misalignment between the marks RM and FMB (that is, these marks RM
The reticle stage 15 is driven via the stage controller 17 to adjust the position and orientation of the reticle 11 so that A and FMA or RMB and FMB enter (ST).
13).

Next, the main control system 59 converts the illumination power as the optimal illumination data for search measurement stored in the memory 67 in accordance with the characteristic data also stored in the memory 67, thereby obtaining the fine power. Find the optimal illumination data (second illumination data) for measurement (S
T14). That is, by substituting the optimum illumination power for the search measurement acquired in ST1 into Ps of the above equation (2),
An optimum illumination power Pf for fine measurement is obtained.

The main control system 59 controls and adjusts the dimming rate in the energy modulator 2b so that the optimum illumination power Pf for the obtained fine measurement is obtained. Based on the detection value of the search measurement camera 58 under this illumination, the reticle marks RMA, RMB and the reference marks FMA, FMB
Is measured (ST15), and based on the measurement result, the reticle stage 15 is driven via the stage controller 17 to change the position and orientation of the reticle 11 so that the positional deviation between the corresponding marks is minimized. Adjust precisely (ST16).

After performing such alignment processing on the reticle 11, the wafer alignment microscope 4
By measuring the reference mark 41 of the reference mark plate 40 by 2, a base line that is the distance from the position of the reticle 11 represented by the reticle marks RMA and RMB to the index inside the wafer alignment microscope 42 is obtained.

Next, alignment of the wafer 14 is performed. Here, some wafer marks WM (see FIG. 2) formed in advance on the wafer 14 are selected, the wafer stage 28 is driven, and their positions are measured by the wafer alignment microscope 42. In this way, the shot arrangement formed on the wafer 14 can be obtained.

Thereafter, the wafer stage 28 is driven so that the pattern area of the reticle 11 and the shot area on the wafer 14 are accurately overlapped based on the measurement results of the baseline and the wafer alignment. Then, an exposure process is performed.

According to the present embodiment, the optimum illumination power Ps used in the fine measurement is converted by converting the optimum illumination power Ps used in the search measurement according to the characteristic data (Equation (2) or the like) acquired in advance. As described above, in order to obtain the optimum illumination power in the fine measurement at the time of fine measurement, a so-called trial shot (preliminary illumination by the illumination light, detection by the alignment sensor, adjustment of the illumination power) is performed. , And calculation of the optimum illumination power based on the detection result), and only the simplified calculation processing is performed, so that the fine alignment can be performed immediately after the search alignment is performed. Therefore, the time required for the alignment is reduced. Thereby, the productivity (throughput) of the exposure processing can be improved.

In the embodiment of the present invention described above,
In ST10 of FIG. 5, the optimal illumination power Ps for search measurement is obtained by so-called trial hitting, but the reticle marks RMA and RM of the reticle 11 are obtained.
If the reflectance of B is known, the optimum illumination power can be obtained. Therefore, such a reflectance may be input as data from the console 68 of the main control system 59. By doing so, test hitting is not required for search measurement, and the time required for alignment processing can be further reduced. In this case, the reflectivity of the marks RMA and RMB is set on the reticle 1
The identification mark may be set as information in the identification mark displayed in 1 or stored in advance in the memory 67 in relation to the identification mark, and the identification mark may be read by the automatic reading device when the reticle 11 is carried in. .

In the above-described embodiment, the adjustment of the illumination power of the illumination light used for the search measurement or the fine measurement is performed by changing the dimming rate in the energy modulator 2b. In addition or independently, the adjustment may be made by changing the output energy or the transmission frequency of the illumination light source 1.

Further, in the above-described embodiment, the case where the present invention is applied to the alignment of the reticle 11 is described. However, the alignment target is not limited to the reticle, and may be a wafer or another object.

The exposure apparatus (FIG. 1) according to the above-described embodiment has an illumination optical system and a projection optical system 1 so that exposure can be performed with high exposure accuracy while improving throughput.
3. Reticle stage 15 including drive unit 18, drive unit 2
3 including the wafer stage 28 and the laser interference systems 16 and 2
2, reticle alignment systems 51 to 58, 62 to 66,
After each element shown in FIG. 1 such as a wafer alignment system is electrically, mechanically, or optically connected and assembled,
It is manufactured by comprehensive adjustment (electrical adjustment, operation confirmation, etc.). It is desirable to manufacture the exposure apparatus in a clean room in which the temperature, cleanliness, and the like are controlled.

Next, the manufacture of a device using the exposure apparatus according to one embodiment of the present invention will be described.

FIG. 6 is a flowchart of micro device production using the exposure apparatus according to one embodiment of the present invention. As shown in FIG. 6, first, in step S20
In a (design step), a function design of a device (for example, a circuit design of a semiconductor device, etc.) is performed, and a pattern design for realizing the function is performed. Subsequently, in step S21 (mask manufacturing step), a mask on which the designed circuit pattern is formed is manufactured. On the other hand, in step S22 (wafer manufacturing step), a wafer is manufactured using a material such as silicon.

Next, in step S23 (wafer process step), actual circuits and the like are formed on the wafer by lithography using the mask and the wafer prepared in steps S20 to S22. Then
In step S24 (assembly step), step S24
The wafer is processed into chips by using the processed wafer.
Step S14 includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). Finally, in step S25 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S24 are performed. After these steps, the device is completed and shipped.

In the above-described embodiment, the scanning type exposure apparatus for sequentially transferring the mask pattern by synchronously moving the reticle and the substrate has been described as an example. However, the present invention is not limited to this. Alternatively, the present invention can also be applied to a static exposure apparatus that performs batch exposure in a state where the mask and the substrate are stationary while sequentially moving the mask. Further, the application of the exposure apparatus is not limited to the exposure apparatus for manufacturing semiconductors. For example, a display apparatus including a liquid crystal display element or a plasma display, a thin film magnetic head, an imaging element (CCD), and a mobile phone The present invention can also be applied to an exposure apparatus used for manufacturing a vibrator (vibrator) used in a game machine or a home game machine.

The light source of the exposure apparatus of this embodiment is a g-line (4
36 nm), i-line (365 nm), KrF excimer laser (248 nm), ArF excimer laser (193n)
m), an F ₂ laser (157 nm), an Ar ₂ excimer laser (wavelength 126 nm), as well as harmonics such as a metal vapor laser or a YAG laser. In addition, a single-wavelength laser in the infrared or visible range oscillated from a DFB semiconductor laser or fiber laser,
For example, harmonics amplified by a fiber amplifier doped with erbium (or both erbium and yttrium) and further converted to ultraviolet light using a nonlinear optical crystal may be used.

For example, the oscillation wavelength of a single wavelength laser is set to 1.
When the wavelength is in the range of 51 to 1.59 μm, the generated wavelength is 18
An eighth harmonic having a wavelength in the range of 9 to 199 nm or a tenth harmonic having a generation wavelength in the range of 151 to 159 nm is output. Especially the oscillation wavelength is 1.544 to 1.553 μm
m, 8 in the range of 193 to 194 nm.
A harmonic wave, that is, ultraviolet light having substantially the same wavelength as the ArF excimer laser is obtained, and the oscillation wavelength is set to 1.57 to 1.58 μm.
m, 1 in the range of 157 to 158 nm.
0 harmonic, i.e., ultraviolet light having almost the same wavelength as the F ₂ laser is obtained.

The oscillation wavelength is set to 1.03 to 1.12 μm
, A 7th harmonic whose output wavelength is in the range of 147 to 160 nm is output.
Assuming that the wavelength is in the range of 099 to 1.106 μm, the generated harmonic is the seventh harmonic in the range of 157 to 158 μm, that is, F _2.
Ultraviolet light having substantially the same wavelength as the laser is obtained. In addition,
As a single-wavelength oscillation laser, ytterbium-doped
A fiber laser is used.

Further, the illumination light is not limited to the above-mentioned far ultraviolet region or vacuum ultraviolet region (wavelength: 120 to 200 nm), but may be a laser plasma light source or a soft X-ray region (wavelength: about 5 to 15 nm) generated from an SOR. ), Eg wavelength 1
3.4 nm or 11.5 nm EUV (Extreme Ultr
a Violet) light or a hard X-ray region (wavelength of about 1 nm or less). In addition, EUV
In the exposure apparatus, a reflection type reticle (mask) is used, and the projection optical system is a reduction system that is telecentric only on the image plane side, and is a reflection system including only a plurality of (about 3 to 6) reflection optical elements. It is.

Further, in the above-described embodiment, the projection optical system 13 is a reduction system, but may be an equal magnification system or an enlargement system. And a catadioptric system consisting of a refracting element and a reflecting element.

When a linear motor is used for the wafer stage or reticle stage, either an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force may be used. Further, the stage may be of a type that moves along a guide, or may be a guideless type in which a guide is not provided. As the stage driving device, a planar motor that drives a stage by electromagnetic force with a magnet unit having two-dimensionally arranged magnets and an armature unit having two-dimensionally arranged coils opposed to each other may be used. In this case, one of the magnet unit and the armature unit may be connected to the stage, and the other of the magnet unit and the armature unit may be provided on the moving surface side of the stage.

The reaction force generated by the movement of the wafer stage may be mechanically released to the floor (ground) by using a frame member as described in Japanese Patent Application Laid-Open No. 8-166475. The reaction force generated by the movement of the reticle stage may be mechanically released to the floor (ground) using a frame member as described in JP-A-8-330224.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore,
Each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

[0082]

As described above, according to the present invention, the optimal data relating to the illumination used in the fine measurement is obtained by converting the optimal data relating to the illumination used in the rough measurement in accordance with the characteristic data obtained in advance. Therefore, fine measurement can be performed immediately after performing rough measurement, and the time required for alignment can be reduced. As a result, the throughput such as the exposure processing can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an overall configuration of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an alignment system of the exposure apparatus according to one embodiment of the present invention.

FIG. 3 is a diagram illustrating a detailed configuration of an alignment system of the exposure apparatus according to the embodiment of the present invention.

FIG. 4 is a diagram showing an image of a reticle mark and a reference mark formed on a light receiving surface of a measurement camera according to an embodiment of the present invention, and a photoelectric conversion signal thereof.

FIG. 5 is a flowchart showing an alignment process by a main control system of the exposure apparatus according to the embodiment of the present invention.

FIG. 6 is a flowchart of micro device production using the exposure apparatus according to one embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Illumination light source 11 ... Reticle (mask) 13 ... Projection optical system 14 ... Wafer (photosensitive substrate) 17 ... Stage controller 28 ... Wafer stage 30 ... Projection exposure apparatus 40 ... Reference mark plate 42 ... Wafer alignment microscope 43A, 43B ... Reticle Alignment microscope 56: Search measurement camera 58: Fine measurement camera 59: Main control system (control device) 57: Memory (storage device) RMA, RMB: Reticle mark FMA, FMB: Reference mark WM: Wafer mark

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F046 BA04 BA05 CB01 CB05 CB08 CB19 CB23 CC01 CC02 CC03 CC05 DA01 DA02 DB01 DC12 EA02 EA03 EA09 EB03 ED03 FA01 FA04 FA07 FA10 FA14 FA16 FA17 FA20 FB10 FC04 FC07

Claims (10)

[Claims] 1. An alignment method for measuring the position of a mark formed on an object and performing alignment of the object, comprising: a first measurement system for rough measuring the mark; Acquiring characteristic data indicating the relationship of optical characteristics between the second measurement system and the second measurement system for performing fine measurement with high accuracy; and acquiring first illumination data that is optimal data relating to illumination at the time of rough measurement. Performing rough measurement by illuminating in accordance with first illumination data; adjusting the posture of the object so that fine measurement can be performed based on the result of the rough measurement; and converting the first illumination data to the characteristic data. Calculating the second illumination data, which is the optimal data related to the illumination at the time of fine measurement, Performing an alignment measurement. 2. The method according to claim 1, wherein the characteristic data includes the first and second characteristics.
2. The alignment method according to claim 1, wherein the data is data on at least one of a magnification, a numerical aperture, and a sensitivity of the measurement system. 3. The apparatus according to claim 1, wherein the first illumination data is obtained from a result measured by the first measurement system by preliminary illuminating the mark before the rough measurement. Alignment method. 4. The alignment method according to claim 1, wherein the object is a mask on which a pattern is formed. 5. An alignment apparatus for measuring a position of a mark formed on an object to perform alignment of the object, comprising: an attitude adjusting apparatus for adjusting an attitude of the object; and rough measurement of the mark. A first measurement system; a second measurement system for finely measuring the mark; a storage device in which characteristic data indicating a relationship between optical characteristics between the first measurement system and the second measurement system are stored; After acquiring first illumination data that is optimal data regarding illumination at the time of measurement, performing illumination and rough measurement in accordance with the first illumination data, controlling the attitude adjustment device based on a result of the rough measurement, The posture of the object is adjusted so that fine measurement can be performed, and the first illumination data is converted according to the characteristic data to obtain second illumination data that is optimal data relating to illumination during fine measurement. And performing a fine measurement by illuminating according to the second illumination data, and then controlling the posture adjustment device based on the result of the fine measurement to adjust the posture of the object. An alignment apparatus characterized by the above-mentioned. 6. The characteristic data according to claim 1, wherein the characteristic data is the first and the second.
The alignment apparatus according to claim 5, wherein the data is data on at least one of a magnification, a numerical aperture, and a sensitivity of the measurement system. 7. The control device according to claim 1, wherein, prior to the rough measurement, the mark is preliminary illuminated and the first illumination data is obtained from a result measured by the first measurement system. 6. The alignment device according to 5. 8. The alignment apparatus according to claim 5, wherein the object is a mask on which a pattern is formed. 9. An exposure apparatus for exposing and transferring an image of a pattern formed on a mask onto a photosensitive substrate, wherein the alignment apparatus aligns at least one of the mask and the photosensitive substrate. An exposure apparatus comprising: the alignment apparatus according to item 1. 10. A mask on which a pattern is formed using the alignment method according to claim 4,
An exposure method comprising exposing and transferring an image of a pattern formed on the aligned mask to a photosensitive substrate.