JPH10116771A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an aligner which restrains the thermal deformation of a reference member used to calibrate an exposure condition such as a baseline amount or the like and by which the exposure condition is calibrated always with high accuracy. SOLUTION: A cooling pipe 24C is installed on the bottom part of a reference mark member 8 as a reference member on which reference marks 17A, 17B for an alignment sensor are formed, and a cooling liquid is circulated in the cooling pipe 24C from an external temperature-regulating apparatus. Temperature sensors 25A, 25B which are used to measure the temperature of the reference mark member 8 are installed on the bottom part of the reference mark member 8, and the temperature or the like of the cooling liquid supplied to the cooling pipe 24C is controlled in such a way that measured values of the temperature sensors 25A, 25B become a prescribed desired value. When the temperature of the reference mark member 8 is made nearly constant, the thermal deformation of the reference mark member 8 is suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for transferring a pattern on a mask onto a photosensitive substrate in a photolithography process for manufacturing, for example, a semiconductor device, a liquid crystal display device, an imaging device (CCD or the like), a thin film magnetic head, or the like. More specifically, the present invention relates to an exposure apparatus having a function of calibrating exposure conditions such as a baseline amount of an alignment sensor.

[0002]

2. Description of the Related Art Conventionally, for example, when manufacturing a semiconductor device or the like, a pattern of a reticle (or a photomask or the like) as a mask is transferred onto a wafer (or a glass plate or the like) as a photosensitive substrate via a projection optical system. For this purpose, a projection exposure apparatus such as a stepper is used. In such a projection exposure apparatus, in order to accurately overlay a reticle pattern on a circuit pattern formed in each shot area on a wafer in the previous process, and to perform exposure, design values of various exposure conditions are used. It is necessary to accurately measure the amount of deviation, that is, perform calibration. “Calibration” in this specification includes high-precision measurement of the exposure condition.

One of the exposure conditions to be calibrated is a so-called baseline amount of an alignment sensor used for detecting the position of a wafer mark as a positioning mark on a wafer. The baseline amount is a relative distance between the measurement center of the alignment sensor and the image of the pattern center of the reticle projected on the wafer via the projection optical system. By performing the amount correction, the exposure can be performed by accurately aligning the center of each shot area of the wafer with the image of the pattern center.

Conventionally, in order to calibrate the baseline amount, a reference mark member having a plurality of reference marks formed thereon is provided on a wafer stage for positioning a wafer. Then, in a state where the reticle alignment mark formed on the reticle is aligned with the corresponding reference mark on the reference mark member, the position of another reference mark on the reference mark member is measured by the alignment sensor, thereby obtaining the baseline. The quantity is required.

Other exposure conditions requiring calibration include a reticle magnification error including a magnification error of the projection optical system. What is the reticle magnification error?
The deviation error from the design value of the pattern drawn on the reticle means that the magnification error of the reticle is provided on the wafer stage in a state where images of a plurality of evaluation patterns formed on the reticle are projected on the wafer stage. It can be measured by measuring the position of each evaluation pattern image via the reference aperture plate. That is, for example, a slit-shaped opening is formed in the reference opening plate, and the pattern images for evaluation are scanned by the opening of the reference opening plate by driving the wafer stage, and the light beam passing through the opening is received by the photoelectric detector. By doing so, the positions of the evaluation pattern images are detected, and the reticle magnification error is determined from the positional relationship between the plurality of evaluation pattern images.

[0006]

In the prior art as described above, if the position of a reference member such as a reference mark member or a reference aperture plate changes during the exposure process, exposure conditions such as a base line amount and a reticle magnification error will occur. Calibration is not performed accurately. Therefore, these reference members are held so as not to be displaced as much as possible.

However, the temperature of each wafer conveyed to the projection exposure apparatus rises due to the irradiation energy of the exposure light at the time of exposure, and the temperature of the reference member on the wafer stage also rises as a result, causing thermal deformation. Further, since the wafer stage also incorporates a driving device such as a linear motor and heat sources such as various sensors, the reference member may be thermally deformed by the influence of these heat sources. When the reference member is thus thermally deformed, the interval between the plurality of reference marks changes, or the position of the reference opening changes, so that the calibration of the exposure condition is not performed accurately.
As a result, there is a disadvantage that the overlay accuracy is reduced.

Further, in order to reduce thermal deformation, the reference member is formed of a material having a low expansion coefficient such as quartz glass or a glass ceramic having a low expansion coefficient (for example, a trade name of Zerodur manufactured by Schott). I have. However,
As the degree of integration of recent semiconductor devices is increasing, and the required overlay accuracy is also increasing,
Even if such a material having a low expansion coefficient is used, desired overlay accuracy cannot be obtained due to thermal deformation of the reference member.

In view of the above, the present invention suppresses thermal deformation of a reference member for calibrating exposure conditions such as a base line amount and the like, so that the exposure conditions can always be calibrated with high precision. It is intended to provide a device.

[0010]

An exposure apparatus according to the present invention comprises a substrate stage (6) for positioning a photosensitive substrate (5) to which a mask pattern (1) is transferred under exposure light (IL). A reference member (8) fixed on the substrate stage, wherein calibration of predetermined exposure conditions is performed using the reference member.
Temperature control means (20, 20) for controlling the temperature of the reference member (8).
24A to 24C).

According to the exposure apparatus of the present invention, the temperature of the reference member (8) is controlled by the temperature control means (20, 24A to 24A).
By controlling to a substantially constant state by C), thermal deformation of the reference member (8) is suppressed. Thus, the calibration of the predetermined exposure condition can always be performed with high accuracy. In this case, a temperature measuring means (25A, 25B) for measuring the temperature of the reference member (8) is provided, and the temperature control means (20, 24A to 24C) based on the temperature measured by the temperature measuring means. It is desirable to control the temperature of 8). For example, temperature measuring means (25A,
By controlling the temperature of the reference member (8) measured by 25B) to a desired value, the temperature of the reference member (8) can be constantly maintained at the desired value.

An alignment sensor (12Y, 1) for detecting the position of the alignment mark on the photosensitive substrate (5).
When 3) is provided, an example of the reference member is a reference mark (17) for the mask pattern on a predetermined substrate.
A, 17B) and alignment sensor (12Y, 13)
Is a reference mark member (8) on which reference marks (15X, 15Y, 16X, 16Y) are formed, and an example of a predetermined exposure condition to be calibrated is a substrate stage (6) of the mask pattern. The relative distance (baseline amount) between the above transfer position and the measurement center of the alignment sensor (12Y, 13). Temperature control means (2
0, 24A to 24C), the temperature of the reference mark member (8) is controlled to be substantially constant, so that the baseline amount of the alignment sensor (12X, 13) is constantly calibrated with high accuracy. , The mask pattern is transferred onto the photosensitive substrate (5) with high overlay accuracy.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an exposure apparatus according to the present invention will be described below with reference to the drawings. In this embodiment, the present invention is applied to a stepper type projection exposure apparatus. FIG. 1 is a schematic configuration diagram of the projection exposure apparatus of the present embodiment, with a part cut away. In FIG. 1, a light source during exposure, a fly-eye lens for uniformizing the illuminance distribution on the reticle, and a reticle of exposure light Exposure light IL emitted from an illumination optical system EL including a field stop that defines an upper field of view, a condenser lens, and the like is irradiated onto the reticle 1 with a uniform illuminance distribution. Under the exposure light IL, an image of the pattern on the reticle 1 is transferred to each shot area of the wafer 5 via the projection optical system 4 at a projection magnification β (β is １ ／ or ５). . As the exposure light IL, a bright line (g line, i line, etc.) in the ultraviolet region of a mercury lamp, KrF excimer laser light,
rF excimer laser light, or copper vapor laser or YAG
A harmonic of a laser or the like is used. Hereinafter, the Z axis is taken parallel to the optical axis AX of the projection optical system 4, the X axis is taken parallel to the plane of FIG. 1 and the Y axis is taken perpendicular to the plane of FIG. 1 in a two-dimensional plane perpendicular to the Z axis. explain.

The reticle 1 is mounted on a reticle stage 2 which can be finely moved in the X, Y and rotation directions. At the ends of the reticle stage 2 in the X direction and the Y direction, movable mirrors 3XM for reflecting laser beams from an external X-axis laser interferometer 3X and two Y-axis laser interferometers (not shown), respectively. And 3YM are fixed.
The X coordinate of the reticle stage 2 is measured by the laser interferometer 3X for X-axis and the moving mirror 3XM, and the reticle stage 2 is measured by two laser interferometers for Y-axis and the moving mirror 3YM.
Are measured. The measured values of these laser interferometers are supplied to a main control system 9, and the main control system 9 controls the positioning operation of the reticle stage 2 via a stage drive system (not shown) based on the measured values. Also,
A reticle alignment mark for reticle alignment is formed on reticle 1.

FIG. 2 is a plan view of the reticle 1. In FIG. 2, a pair of cross-shaped reticle alignment marks are provided in the vicinity of the light-shielding band TA surrounding the pattern area PA of the reticle 1 in the X direction. RMA and RMB are formed. The center of the reticle alignment marks RMA and RMB is set at the pattern center RC of the reticle 1.

Returning to FIG. 1, reticle alignment microscopes 11A and 11A are provided above reticle 1 corresponding to reticle alignment marks RMA and RMB of FIG.
1B is arranged. The reticle alignment microscopes 11 </ b> A and 11 </ b> B of the present example use the reticle alignment marks RM under illumination light having the same wavelength as the exposure light IL.
This is a microscope that captures images of A and RMB and corresponding fiducial marks, which will be described later. The reticle 1 is aligned by processing the captured signals.

On the other hand, the wafer 5 is placed on a wafer stage 6 which is movable in the X and Y directions via a wafer holder (not shown) and which can be finely moved in the Z and rotation directions. The operation of moving the center of each shot area of the wafer 5 to the position of the image of the pattern center of the reticle 1 by the wafer stage 6 and the exposure operation are repeated in a step-and-repeat manner, and the pattern image of the reticle 1 is sequentially formed. The image is transferred to each shot area on the wafer 5. At the ends of the wafer stage 6 in the X and Y directions, laser beams from an external laser interferometer 7X for the X axis and two laser interferometers (not shown) for the Y axis are respectively reflected. Moving mirrors 7XM and 7YM are fixed. The X coordinate of wafer stage 6 is measured by laser interferometer 7X for X axis and movable mirror 7XM, and the Y coordinate and rotation angle of wafer stage 6 are measured by two laser interferometers for Y axis and movable mirror 7YM. . The measured values of these laser interferometers are supplied to a main control system 9, which controls the positioning operation of the wafer stage 6 via a stage drive system such as a linear motor (not shown) based on the measured values. I do.

Further, wafer marks for positioning are formed in each shot area on the wafer 5, and the positions of these wafer marks are measured by an alignment sensor described later. Based on this measurement result, the arrangement coordinates of each shot area are determined by, for example, a so-called enhanced global alignment (EGA) method, and the wafer stage 6 is driven based on the coordinates obtained by correcting the arrangement coordinates by the baseline amount of the alignment sensor. Thus, the center of each shot region matches the image of the pattern center of the reticle 1, respectively.

The projection exposure apparatus of this embodiment has a TTL (through-the-lens) system and a LIA (Laser Interferometric Alignment) system for detecting the position of a wafer mark. The illustrated X-axis alignment sensor and the off-axis type FIA (Field Image Alignment) type alignment sensor 13 are provided. What is LIA system?
A diffraction grating wafer mark is irradiated with a pair of laser beams having coherent and slightly different frequencies, and a heterodyne beam composed of, for example, a pair of diffracted lights generated in the same direction from the wafer mark is photoelectrically converted. In this method, the position of the wafer mark is detected based on the phase of the obtained beat signal. The FIA method is a method of performing image processing on an image obtained by irradiating a wafer mark with illumination light of a relatively wide wavelength range from a halogen lamp or the like, and detecting the position of the wafer mark.

First, from the heterodyne beam generation system inside the Y-axis alignment sensor 12Y of the LIA system,
A pair of laser beams A in a wavelength range in which the photoresist applied to the wafer 5 is non-photosensitive and slightly different in frequency.
L1 is emitted. After being emitted from the alignment sensor 12Y, the laser beam AL1 is bent downward by the mirror M1 and enters the projection optical system 4, and the laser beam AL1 that has passed through the projection optical system 4 is applied to each shot area on the wafer 5. Irradiation is performed on the attached diffraction grating wafer mark (not shown) for the Y axis. A pair of diffracted lights from the wafer mark enter the photoelectric conversion element in the alignment sensor 12Y via the projection optical system PL and the mirror M1, and a wafer beat signal is output from the photoelectric conversion element. The alignment sensor 12Y also outputs a reference beat signal, and the wafer beat signal and the reference beat signal are supplied to the main control system 9.

The main control system 9 drives the wafer stage 6 so that the phase difference between the wafer beat signal and the reference beat signal becomes, for example, 0, and the Y coordinate measured by the laser interferometer of the wafer stage 6 at that time is changed. It becomes the Y coordinate of the wafer mark. As described above, the LIA type alignment sensor for the X axis is also provided, and the X coordinate of the X axis wafer mark is measured by the X axis alignment sensor.

Next, an FIA type alignment sensor 1
The illumination light AL3, which is not photosensitive to the photoresist on the wafer 5 and is emitted from the wafer 3, is directly applied to the wafer mark in the shot area on the wafer 5 to be detected. The reflected light from the wafer mark once forms an image of the wafer mark on the index mark plate on which the predetermined index mark is formed inside the alignment sensor 13. Then, the illumination light AL3 passing through the index mark plate forms an image of the wafer mark and the index mark on an image sensor such as a two-dimensional CCD in the alignment sensor 13. The imaging signal from the imaging device is supplied to the main control system 9, which calculates the position shift amount between the image of the wafer mark and the image of the index mark and the coordinates of the wafer stage 6 at that time. The X coordinate or the Y coordinate of the wafer mark is calculated.

Now, on the wafer stage 6 of the projection exposure apparatus of this embodiment, a reference mark member 8 having a plurality of reference marks formed thereon is fixed in order to calibrate the baseline amount of the alignment sensor. ing. The reference mark member 8 is formed by forming various reference marks on a rectangular plate-shaped light-transmitting substrate that is long in the Y direction, for example, by vapor deposition of a chromium film. As the substrate of the reference mark member 8, for example, quartz glass having a low expansion coefficient can be used. The height of the surface of the reference mark member 8 is set to be the same as the surface of the wafer 5.

FIG. 3 is a perspective view of the reference mark member 8. As shown in FIG. 3, the end of the reference mark member 8 in the -X direction is a Y-axis alignment sensor of the LIA type shown in FIG. A reference mark 16Y in the form of a diffraction grating having a predetermined pitch is formed in the Y direction for 12Y. In addition, a reference mark 16X in the form of a diffraction grating for the X-axis is formed at the end of the reference mark member 8 in the + Y direction corresponding to the LIA-type X-axis alignment sensor. Further, the reference mark member 8
At the end in the −Y direction, a reference mark 15X having a predetermined pitch in the X direction and a reference mark 15X for the FIA type alignment sensor 13 of FIG.
A rotated Y-axis reference mark 15Y is formed.

FIG. 6 is an enlarged plan view of the X-axis reference mark 15X for the FIA type alignment sensor 13,
In FIG. 6, the reference mark 15X is a line-and-space pattern in which light-shielding patterns extending in the Y direction are arranged at a constant pitch P in the X direction. In this example, L
Reference mark 16X for IA type alignment sensor
Also has a line of pitch P similar to the fiducial mark 15X.
And space pattern.

Returning to FIG. 3, a frame-shaped reference mark 17B is formed near the inside of the reference mark 16Y of the reference mark member 8, and the end of the reference mark member 8 in the + X direction corresponds to the reference mark 17B. A reference mark 17A is formed. These fiducial marks 17A and 17B have the same shape, and each of them has a reticle alignment microscope 11 shown in FIG.
Reference marks for A and 11B.

FIG. 5 is an enlarged plan view showing one reference mark 17A.
Is a pair of light-shielding patterns 18XA and 18XB formed at a predetermined pitch d1 and extending in the Y-direction, and a pair of similar light-shielding patterns 18XC and 18XC extending in the Y-direction and spaced from the light-shielding patterns by an interval d2 in the X-direction. 18XD and four light-shielding patterns 18YA to 18Y obtained by rotating these light-shielding patterns 18XA to 18XD by 90 degrees around their centers.
D.

In FIG. 3, reference marks 17A and 17B are shown.
For example, the center becomes a reference point KC, the amount of displacement of the other X-axis reference marks 15X, 16X in the X direction with respect to this reference point KC, and the Y of the Y-axis reference marks 15Y, 16Y.
The amount of displacement in the direction is accurately measured in advance. These displacement amounts are stored as design values in, for example, the storage unit of the main control system 9 in FIG.

Returning to FIG. 1, an end of a light guide 19A for guiding a part of exposure light from an external light source (not shown) is provided inside the wafer stage 6 at the bottom of the reference mark member 8. Is installed, and when performing calibration of a baseline amount described later, illumination light IL1 having the same wavelength as the exposure light IL is emitted from the end of the light guide 19A. The illumination light IL1 is condensed by the lens 19B and enters the half mirror 19C. The illumination light reflected by the half mirror 19C illuminates the reference mark 17B (see FIG. 3) of the reference mark member 8 from the bottom, and The illumination light transmitted through the mirror 19C is reflected by the mirror 19D, and the reference mark 17A
(See FIG. 3) from the bottom.

Also in this embodiment, the wafer 5 is exposed to the exposure light IL.
The irradiation energy is absorbed by the irradiation, and the irradiation energy is transmitted to the reference mark member 8 via the wafer holder or the like, and the thermal energy generated in the drive system of the wafer stage 6 is also transmitted to the reference mark member 8. ,
If no countermeasures are taken, the temperature of the reference mark member 8 will increase. Therefore, in order to suppress a rise in the temperature of the reference mark member 8, the cooling coil 24C through which the coolant flows inside the bottom of the reference mark member 8 in this embodiment in a state of being in close contact therewith.
Is installed.

One end of the cooling coil 24C is connected to the wafer stage 6 via a flexible heat insulating pipe 24A.
Is connected to an external temperature control device 20, and the other end is also connected to the temperature control device 20 via a flexible heat insulating pipe 24B. The cooling liquid whose temperature is controlled by the temperature control device 20 is introduced into the cooling coil 24C through the heat insulating pipe 24A, and the cooling liquid that has absorbed the heat of the reference mark member 8 is transmitted to the temperature controlling device 20 through the heat insulating pipe 24B. Then, the temperature is adjusted again and returned to the cooling coil 24C.

FIG. 4 is a bottom view of the reference mark member 8,
In FIG. 4, the cooling coil 24C is arranged in a meandering manner so as to uniformly contact almost the entire bottom surface of the reference mark member 8. However, the reference mark 1 on the reference mark member 8
Cooling coil 24C is provided with reference marks 17A and 17B so that 7A and 17B are illuminated by illumination light IL1 of FIG.
It is arranged in a shape that avoids the bottom part. Further, temperature sensors 25A and 25A for detecting the temperature of the reference mark member 8 are provided.
5B are attached to both ends of the bottom of the reference mark member 8 in the Y direction. The measured values of the temperatures of the temperature sensors 25A and 25B are supplied to the temperature control device 20 of FIG. 1, and the temperature control device 20 calculates the average value of the temperatures measured by the temperature sensors 25A and 25B in a predetermined target. The temperature and the flow rate of the cooling liquid supplied into the cooling coil 24C are controlled so as to reach the temperature. As the target temperature, for example, the average value of the measured values of the temperature sensors 25A and 25B when the projection exposure apparatus of this example is left unexposed for a while is used.

As the cooling liquid supplied to the cooling coil 24C, for example, water can be used. Also, the cooling coil 24
As the material of C, copper, a metal having a high thermal conductivity such as stainless steel having a high thermal conductivity, a resin having a high thermal conductivity, or the like can be used. On the other hand, as the heat insulating pipes 24A and 24B, a flexible material such as synthetic rubber or synthetic resin having low thermal conductivity can be used. Note that a gas such as cooled air may be supplied to the cooling coil 24C instead of the cooling liquid. In addition, fiducial mark member 8
May be lowered by using a thermoelectric element such as a Peltier element.

In FIG. 1, a light transmitting optical system 14A and a light receiving optical system for detecting the position (focal position) of the surface of the wafer 5 in the Z direction are provided close to the left and right side surfaces of the projection optical system 4. An oblique incidence type focus position detection system composed of 14B is provided. Information on the focus position of the wafer 5 from the focus position detection system is supplied to the main control system 9, which controls the height and the tilt angle of the wafer stage 6 based on the information.

Next, an example of the operation of calibrating the baseline amount of the LIA type alignment sensor and the FIA type alignment sensor 13 of this embodiment will be described. In this case, in FIG. 1, the wafer stage 6 is positioned such that the center reference point KC (see FIG. 3) of the reference marks 17A and 17B of the reference mark member 8 substantially matches the optical axis AX of the projection optical system 4. . In this state, the reference marks 17A and 17B of the reference mark member 8 are illuminated from the bottom by the illumination light IL1 via the optical fiber bundle 19A, and the illumination light I that has passed through the reference marks 17A and 17B.
L1 illuminates the area including reticle alignment marks RMA and RMB of FIG. 2 via projection optical system 4, respectively. Since the illumination light IL1 has the same wavelength as the exposure light IL, images of the reference marks 17A and 17B are formed on the formation surfaces of the reticle alignment marks RMA and RMB.

Then, the illumination light IL1 that has passed through the region including the reticle alignment marks RMA and RMB in FIG.
Are the reticle alignment microscopes 11 of FIG.
A, a reference mark 17 is provided on the two-dimensional image sensor in 11B.
A and 17B and corresponding reticle alignment marks RMA and RMB are formed. The imaging signals of these image sensors are supplied to the main control system 9, and based on the supplied imaging signals, the amount of displacement of the reticle alignment mark RMA with respect to the reference mark 17 </ b> A and the reticle alignment mark R with respect to the reference mark 17 </ b> B are determined.
The position shift amount of the MB is obtained. Then, in the main control system 9, these positional deviation amounts indicate the reticle alignment marks RMA.
The reticle stage 2 shown in FIG. 1 is driven to perform reticle alignment so as to be symmetric with respect to RMB. As a result, as shown in FIG.
C substantially matches image RCW of pattern center RC of reticle 1 in FIG.

Next, in such a state that the reticle alignment is performed, the Y-axis alignment sensor 12Y of the LIA system in FIG.
The position of the axis reference mark 16Y is detected. Then, for example, the driving amount Δ in the Y direction when the wafer stage 6 is driven in the Y direction such that the phase difference between the wafer beat signal from the alignment sensor 12Y and the reference beat signal becomes zero.
_Ask for Y _LIA . At this time, the reference marks 17A, 17B
The distance BY _LIA between the center reference point KC and the reference mark 16Y in the Y direction is accurately obtained in advance, and this distance BY
By adding the measured drive amount [Delta] Y _LIA to _LIA, baseline amount of alignment sensor 12Y in the Y direction is determined. Similarly, the baseline amount of the LIA X-axis alignment sensor in the X direction is determined by the reference mark 16X.
Is obtained by performing position detection.

Further, in the state where the reticle alignment is performed as described above, the X-axis reference mark 15X and the Y-axis reference mark on the reference mark member 8 in FIG. 3 by the FIA type alignment sensor 13 in FIG. 15Y position detection is performed. Then, values ΔX _FIA and ΔY _FIA obtained by converting the positional deviation of the reference marks 15X and 15Y from the corresponding index marks on the wafer stage 6 are obtained. At this time, the distance BX _FIA between the reference point KC and the reference mark 15X in the X direction and the distance BY _FIA between the reference mark 15Y in the Y direction are accurately obtained in advance, and these distances BX _FIA and BY _FIA are _calculated . The measured value ΔX
By adding _FIA and ΔY _FIA , the base line amounts of the alignment sensor 13 in the X and Y directions are obtained. By detecting the position of the reference mark on the reference mark member 8 as described above, the alignment sensor 12
Calibration, which is an accurate measurement of the baseline amounts such as Y and 13, is completed.

In this case, a cooling coil 24C through which a cooling liquid flows is disposed at the bottom of the reference mark member 8 of this embodiment, and a temperature sensor 25 attached to the reference mark member 8 is provided.
The temperature controller 20 controls the temperature and flow rate of the coolant based on the measured values of A and 25B so that the temperature of the reference mark member 8 always becomes a predetermined target temperature. Therefore, since the temperature of the reference mark member 8 is maintained at a substantially constant temperature,
The thermal deformation of the reference mark member 8 does not occur, and the LIA
The calibration of the baseline amount of the alignment sensor of the FIA system and the alignment sensor 13 of the FIA system is always performed accurately. By correcting the measurement value of the corresponding alignment sensor based on the accurately obtained baseline amount, the pattern image of the reticle 1 is superimposed on each shot area on the wafer 5 with high overlay accuracy. Can be transcribed.

In the above-described embodiment, the reference marks 17A and 17B on the reference mark member 8 and the corresponding reticle alignment marks RMA and RMB are illuminated by the illumination light from inside the wafer stage 6. In addition, for example, in FIG. 1, a half mirror is provided so as to be retractable above the reticle 1, and reticle alignment marks RMA, RMB,
The reticle alignment may be performed by illuminating the corresponding reference marks on the reference mark member 8 and receiving the exposure light from these reference marks and the reticle alignment marks RMA and RMB by the corresponding reticle alignment microscope. .

In the above embodiment, the temperature sensors 25A, 25A for measuring the temperature of the reference mark member 8 are provided.
Although B is arranged at the bottom of the reference mark member 8, it is not always necessary to provide a temperature sensor in contact with or in proximity to the reference mark member 8. When a temperature sensor in contact with or in proximity to the reference mark member 8 is not provided as described above, a cooling liquid having a constant temperature may be supplied from the temperature control device 20 into the cooling coil 24C. In this case, a temperature sensor for measuring the temperature of the coolant is installed near the coolant supply port of the temperature controller 20, and the temperature of the coolant is controlled based on the measured value of the temperature sensor. You may.

Further, in the above-described embodiment, the alignment sensor of the TTL type and the LIA type as the alignment sensor and the off-axis type and the FI
A type of alignment sensor 13 is used,
In addition, even when using an alignment sensor of the TTL type or the off-axis type and the LSA (laser step alignment) type, the calibration of the baseline amount can be performed by using the reference mark member whose temperature is controlled. Done exactly. Furthermore, TTR
Even when the (through-the-reticle) type alignment sensor is used, the calibration of the baseline amount is accurately performed by using the temperature-controlled reference mark member.

In the above-described embodiment, the present invention is applied to the case where the calibration of the baseline amount is performed. However, the case where the calibration of the reticle magnification error including the projection magnification error is performed is performed. The present invention can also be applied to FIG. 7A shows an example of an aerial image measurement sensor provided on a wafer stage of a projection exposure apparatus when measuring a reticle magnification error.
3A, a reference aperture plate 3 made of a light-transmitting substrate.
A slit-shaped opening 3 long in the Y direction in the light-shielding film
A slit-like opening 32Y long in the 2X and X directions is formed. The reference aperture plate 31 is fixed on a wafer stage similar to the wafer stage 6 in FIG. The condenser lens 33X and the photoelectric detector 34X are arranged inside the wafer stage at the bottom of the opening 32X.
The condenser lens 33Y and the photoelectric detector 34Y are arranged inside the wafer stage at the bottom of Y. Further, a temperature sensor 36 is attached to the bottom of the reference opening plate 31, and a cooling coil 35 is arranged in an area of the bottom except for the bottoms of the openings 32X and 32Y. Also in this example, the temperature sensor 3
A cooling liquid is supplied to the cooling coil 35 from a temperature control device (not shown) so that the temperature measured at 6 becomes the target temperature.

In FIG. 7 (a), when measuring the magnification error of the reticle, the wafer stage is driven so that the image of the evaluation pattern formed on the reticle is moved through the openings 32X and 32Y in the X direction and Y direction, respectively. By scanning in the directions, the detection signals SX and SY from the corresponding photoelectric detectors 34X and 34Y are captured. Then, for example, the position of the image of each evaluation pattern is detected based on the change of the detection signals SX and SY and the coordinates of the wafer stage, and the magnification error of the reticle determines the projection magnification from the positional relationship between the images of each evaluation pattern. It is required in a form that includes it. That is, calibration of the reticle magnification error is performed. At this time, since the temperature of the reference aperture plate 31 is kept constant, the calibration of the reticle magnification error is always performed accurately.

FIG. 7B shows another example of a sensor for measuring an aerial image. In FIG. 7B, a square is formed in a light-shielding film on the surface of a reference aperture plate 37 made of a light-transmitting substrate. Opening 38 is formed. Then, a condenser lens 39 and a photoelectric detector 40 are arranged inside the wafer stage at the bottom of the opening 38. Further, a temperature sensor 36 is attached to the bottom of the reference opening plate 37, and a cooling coil 35 is disposed in a region other than the bottom of the opening 38 at the bottom. Also in this example, a cooling coil 35 is provided from a temperature controller (not shown) so that the temperature measured by the temperature sensor 36 becomes the target temperature.
Is supplied with a cooling liquid.

In FIG. 7B, when measuring the magnification error of the reticle, the wafer stage is driven to move the image of the evaluation pattern formed on the reticle at the edge of the opening 38 in the X and Y directions. , The detection signal SE from the photoelectric detector 40 is fetched. Then, the position of the image of each evaluation pattern is detected based on the differential signal of the detection signal SE and the coordinates of the wafer stage, and the magnification error of the reticle is used to calibrate the projection magnification from the positional relationship between the images of each evaluation pattern. Is performed. At this time, since the temperature of the reference aperture plate 37 is kept constant, the calibration of the reticle magnification error is always performed accurately.

The exposure conditions required for calibration include, for example, the above-mentioned baseline amount and reticle magnification error, as well as the state of the imaging surface of the projection optical system and the illuminance of the exposure light on the wafer. is there. In some cases, a reference flat member having a high flatness is used for monitoring the state of the image forming surface, and a so-called irradiation amount monitor or the like is used for monitoring the illuminance of the exposure light. Therefore, the temperature of the reference plane member and the irradiation amount monitor may be controlled. As a result, the calibration of those exposure conditions can always be performed accurately.

Further, according to the present invention, while a part of the reticle pattern is projected onto the wafer via the projection optical system, the reticle and the wafer are synchronously scanned with respect to the projection optical system so that the reticle pattern is projected onto the wafer. The present invention can be similarly applied to a scanning exposure type projection exposure apparatus such as a step-and-scan method that sequentially exposes each shot area, a proximity type exposure apparatus, and the like.

As described above, the present invention is not limited to the above-described embodiment, and can take various configurations without departing from the gist of the present invention.

[0050]

According to the exposure apparatus of the present invention, the temperature of the reference member for calibrating the predetermined exposure condition can be controlled to a predetermined state by the temperature control means, and the thermal deformation of the reference member can be controlled. Can be suppressed. Thereby, there is an advantage that the calibration of the exposure condition can always be performed with high accuracy.

Further, when a temperature measuring means for measuring the temperature of the reference member is provided, and the temperature control means controls the temperature of the reference member based on the temperature measured by the temperature measuring means, the reference member Can be accurately set to a desired temperature. Further, an alignment sensor for detecting the position of the alignment mark on the photosensitive substrate is provided, and its reference member is a reference mark for forming a reference mark for a mask pattern and a reference mark for the alignment sensor on a predetermined substrate. If the predetermined exposure condition to be calibrated is the relative distance between the transfer position of the mask pattern on the substrate stage and the measurement center of the alignment sensor, the base of the alignment sensor Calibration of the line amount is always performed accurately. Then, there is an advantage that the mask pattern can be transferred onto the photosensitive substrate with high overlay accuracy based on the baseline amount at which the calibration has been performed.

[Brief description of the drawings]

FIG. 1 is a partially cutaway schematic configuration view showing an example of an embodiment of an exposure apparatus according to the present invention.

FIG. 2 is a plan view showing a reticle alignment mark on the reticle 1 of FIG.

FIG. 3 is an enlarged perspective view showing an arrangement of fiducial marks of the fiducial mark member 8 of FIG.

FIG. 4 is a bottom view showing a cooling coil 24C and the like arranged on the bottom surface of the reference mark member 8 of FIG. 1;

FIG. 5 is an enlarged plan view showing a reference mark 17A of FIG. 3;

FIG. 6 is an enlarged plan view showing a reference mark 15X of FIG.

FIG. 7A is an enlarged perspective view showing an example of the aerial image sensor with a part cut away, and FIG. 7B is an enlarged perspective view partly showing another example of the aerial image sensor.

[Explanation of symbols]

Reference Signs List 1 reticle 4 projection optical system 5 wafer 6 wafer stage 8 reference mark member 9 main control system 11A, 11B reticle alignment microscope 12Y LIA type Y-axis alignment sensor 13 FIA type alignment sensor RMA, RMB reticle alignment mark 15X, 15Y FIA Reference mark for system 16X, 16Y Reference mark for LIA system 17A, 17B Reference mark for reticle alignment microscope 20 Temperature control device 24A, 24B Insulated pipe 24C Cooling coil 25A, 25B Temperature sensor

Claims (3)

[Claims] 1. A substrate stage for positioning a photosensitive substrate to which a mask pattern is transferred under exposure light, and a reference member fixed on the substrate stage, and a predetermined member is fixed using the reference member. An exposure apparatus for performing calibration of exposure conditions, comprising: a temperature control unit for controlling a temperature of the reference member. 2. The exposure apparatus according to claim 1, further comprising: a temperature measuring unit configured to measure a temperature of the reference member, wherein the temperature control unit controls the temperature of the reference member based on the temperature measured by the temperature measuring unit. An exposure apparatus characterized by controlling the temperature of the light. 3. The exposure apparatus according to claim 1, further comprising an alignment sensor configured to detect a position of an alignment mark on the photosensitive substrate, wherein the reference member is provided on a predetermined substrate. A reference mark member on which a reference mark for a mask pattern and a reference mark for the alignment sensor are formed; and the predetermined exposure condition to be calibrated is a transfer position of the mask pattern on the substrate stage. An exposure apparatus, wherein the distance is a relative distance between the alignment sensor and a measurement center of the alignment sensor.