JPH09293662A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the effect of heat of an alignment light source and to conduct detection of the position of an exposure main body part with high accuracy when the alignment light source, which is used as a heating source like a plurality of wavelengths of laser beam sources, is used. SOLUTION: Laser beam sources 9 and 10, which respectively generate a plurality of wavelengths of laser beams LB1 and LB2 and are used as an alignment light source, are provided in a chamber 42 different from a chamber 41, wherein an exposure main body part is installed, separately from each other. Transmission of the beams LB1 and LB2 between the chambers 41 and 42 is conducted by optical fibers 31 and 32. The transmitted beams LB1 and LB2 are combined d by a dichroic mirror 15 in the vicinity of the exposure main body part in the chamber 41 and the combined beam is emitted on a wafer mark 3Y on a lattice provided on a wafer W. Interference light DS consisting of ± primary diffracted light diffracted on the mark 3Y is detected by a photoelectric detector 20 and a detection of the position of the exposure main body part is conducted on the basis of the phase of a beat signal detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention transfers a mask pattern onto a photosensitive substrate in a photolithography process for manufacturing, for example, a semiconductor element, an image pickup element (CCD or the like), a liquid crystal display element, a thin film magnetic head or the like. The present invention relates to an exposure apparatus used to do this.

[0002]

2. Description of the Related Art In a photolithography process for manufacturing a semiconductor device or the like, a transfer pattern formed on a reticle (or a photomask or the like) is coated with a photoresist, which is a photosensitive material, through a projection optical system. There is used an exposure apparatus such as a projection exposure apparatus such as a stepper that projects onto a wafer (or a glass plate or the like) that has been formed, or a proximity type exposure apparatus that directly transfers the pattern of the reticle onto the wafer.

In this type of exposure apparatus, since the process of transferring a fine pattern to a plurality of layers on each shot area on the same wafer is repeated, the reticle is aligned with each shot area on the wafer between shot exposures. (Alignment) must be performed with high precision prior to exposure. In order to perform this alignment, each shot area on the wafer is provided with a wafer mark as a position detection mark in the steps up to that point. By optically detecting the position of this wafer mark, each wafer The accurate position of the shot area is detected, and the next pattern is superimposed and exposed based on this position information.

A lattice alignment method is currently used as a typical alignment method. In this alignment method, a laser is used as an alignment light source and a lattice-shaped wafer mark having periodicity is used. The grating alignment method is divided as follows according to the configuration of the alignment optical system, the detection system, the number of alignment light beams, and the like. First, one laser beam is incident on the entire surface of the wafer mark, two diffracted lights generated from the mark are imaged on the reference grating, and the wafer mark and the reference grating are relatively scanned, In this method, the position is detected based on the change in the amount of transmitted light or reflected light from the reference grating.

Secondly, two laser beams are incident on the entire surface of the wafer mark from specific different diffraction order directions, and based on the phase of the interference light composed of diffracted light generated in the same direction from the mark. LIA (La to detect position
ser interferometric alignment method. This LI
The A method is further classified into two, one is a homodyne method in which a wafer mark is moved with respect to a stationary interference fringe formed by two laser beams having no frequency difference. The other one is to give a slight frequency difference between the two laser beams and photoelectrically detect the interference light (beat light) of the two diffracted light components generated from the wafer mark and the signal between the two laser beams. Is a heterodyne method in which a phase difference between the frequency difference of the above-mentioned and a reference signal of the same frequency is measured and detected as a positional deviation amount from the reference point in the pitch direction of the lattice-shaped wafer mark.

When the photoelectric conversion signal of the diffracted light by such a lattice mark is detected by using a monochromatic light source, the incident laser is affected by the asymmetry of the cross-sectional shape of the lattice mark, the thickness of the photoresist layer on the surface, etc. Depending on the wavelength of the beam, the diffracted light to be detected may not be generated, or the diffracted light generated may be so weak that it may be erroneously detected. In order to solve this problem and enable more accurate position detection, a heterodyne system using light sources of a plurality of wavelengths has been attempted.

In the heterodyne method using a light source of a plurality of wavelengths, laser beams having a plurality of different wavelengths are used as incident light on a wafer mark, and two laser beams having respective wavelengths are given a slight frequency difference. After that, the light is made incident on the wafer mark from a specific diffraction order direction, and beat light composed of a plurality of wavelength components generated therefrom is photoelectrically detected. Since each wavelength component is photoelectrically detected in the form that is added as the amount of light on the light receiving surface of the photoelectric element, the occurrence of diffracted light due to the influence of thin film interference in the resist layer and the asymmetry of the mark cross-sectional shape The influence of variations can be reduced.

As a method of detecting the diffracted light from the wafer mark as in the case of the lattice alignment method, one laser beam is focused on the wafer to form a laser spot, and the laser spot and the lattice-like wafer are formed. The position of the wafer on which the mark is formed is detected by relative scanning with the wafer stage on which the wafer is placed, and the position is detected based on the intensity change of the diffracted light generated when the wafer mark passes under the laser spot.
There is also SA (Laser Step Alignment) type alignment.

In any of the above-mentioned methods, the exposure light emitted from the exposure light source and the alignment light emitted from the alignment light source such as a laser must have different wavelengths. This is because the alignment light is made non-photosensitive so that it does not affect the photoresist. Therefore, it is necessary to install the alignment light source separately from the exposure light source. Conventionally, a laser light source as an alignment light source has been installed in the same chamber (a small chamber that separates the apparatus from the outside) as the exposure main body. The temperature inside the chamber is strictly controlled in order to improve the alignment accuracy and the exposure accuracy (overlap accuracy, etc.).

[0010]

However, He-
Alignment light sources such as Ne lasers and semiconductor lasers generate heat during laser irradiation, which can cause temperature changes and temperature gradients in the chamber. As a result, the exposure main body portion installed in the chamber and the wafer that is the exposed object are subject to deformation such as thermal expansion, which may lead to defects in alignment accuracy and exposure accuracy. In particular, when the alignment light source has a plurality of wavelengths as in the conventional multi-wavelength LIA method, the number of heat sources increases, so that the influence of heat generation increases.

When the alignment light is laser light, a method of transmitting the laser light through an optical fiber can be considered. However, since ordinary single-mode optical fibers are optimized for specific wavelengths, when using laser light of multiple wavelengths, the transmission efficiency of certain specific wavelengths is good, and at other wavelengths the transmission efficiency of light is good. Is bad. Therefore, if laser light of multiple wavelengths is all transmitted through the same optical fiber, the signal of light of wavelength with poor transmission efficiency becomes small,
There is a great risk of lowering the alignment accuracy.

In view of the above point, the present invention provides an exposure apparatus capable of eliminating the influence of heat generation of an alignment light source, particularly when using an alignment light source having a large heat generation amount such as a light source of a plurality of wavelengths. The purpose of 1. Further, it is a second object of the present invention to provide an exposure apparatus in which alignment accuracy is not deteriorated even when an optical fiber or the like is used when alignment is performed using light fluxes having a plurality of wavelengths.

[0013]

An exposure apparatus according to the present invention comprises an exposure main body (1, 2, R, PL, W, 4) for transferring a mask pattern (R) onto a photosensitive substrate (W), and A position detection system for detecting the position of the alignment mark (3Y) on the photosensitive substrate (W), and the mask pattern and the photosensitive substrate (W) based on the detection result of the position detection system.
In an exposure device that aligns with and exposes,
The position detection system uses laser light of a plurality of wavelengths (LB1, LB
The laser light source (9, 10) for generating 2) and the laser light (LB1, LB2) from the laser light source (9, 10) are applied to the alignment mark (3Y) on the photosensitive substrate (W). It has an irradiation optical system (13-18) and a light receiving optical system (19, 20) for receiving the return light (DS) from the alignment mark (3Y), and its laser light source (9, 20).
10) is the exposure main body (1, 2, R, PL, W, 4)
It was placed in isolation from. The term “separately arranged” means, for example, a state where the chambers are housed in independent chambers or partially forcedly air-conditioned in one chamber.

According to the present invention, laser light (L) of a plurality of wavelengths in the position detection system, which serves as a heat emission source from the exposure main body, is generated.
By separating the laser light sources (9, 10) that generate B1 and LB2), it is possible to eliminate adverse effects on the exposure main body portion and the photosensitive substrate (W) due to heat generation of the laser light sources (9, 10). Then, laser light of a plurality of wavelengths (LB1, LB2)
By performing the alignment by using, it is possible to perform highly accurate alignment without being significantly affected by the thin film interference of the photosensitive material and the shape of the alignment mark.

In this case, the exposure apparatus uses laser beams (LB1, L1) of a plurality of wavelengths from the laser light source (9, 10).
It is desirable to guide B2) to the irradiation optical system (13-18) through the light guides (31, 32) different for each wavelength. At this time, since it is possible to use an optical guide such as an optical fiber whose transmission efficiency is optimized for each wavelength, it is possible to effectively use each of the laser beams of a plurality of wavelengths, and by combining them in the vicinity of the exposure main body, Position detection is performed with high accuracy.

The light receiving optical system (19, 20) is
As an example, diffracted light (DS) generated in a predetermined direction from the alignment mark (3) is received by the laser light (LB1, LB2). This means that the present invention is applied to an exposure apparatus having an alignment system such as the lattice alignment method or the LSA method. in this case,
Further, the irradiation optical system (13 to 18) irradiates the point array mark (3YA) as the alignment mark with the laser light (LB1, LB2) of the plurality of wavelengths, and the light receiving optical system (19). , 20), the position of the dot array mark may be detected based on the amount of diffracted light (DS) received. This means that the LSA type alignment system is used with a plurality of wavelengths.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment of an exposure apparatus according to the present invention will be described below with reference to FIG. In this example, the present invention is applied to a stepper type projection exposure apparatus equipped with an LIA type alignment system having a plurality of wavelengths. FIG. 1 shows a projection exposure apparatus of this example.
At the time of exposure, the exposure illumination light IL generated from the exposure light source system 1 including an ultra-high pressure mercury lamp or a light source such as an excimer laser, a shaping lens, and an optical integrator is used for the reticle blind, the main condenser lens, and the like. The pattern area of the reticle R is illuminated with a substantially uniform illuminance distribution via the illuminating optical system 2 including the reticle. The illumination light that has passed through the pattern area of the reticle R is incident on the projection optical system PL that is telecentric on both sides or on one side, and the pattern image of the reticle R that has been reduced to, for example, 1/5 by the projection optical system PL has a photoresist on the surface. The layer is applied and projected onto a single shot area on the wafer W held so that its surface substantially coincides with the best image plane of the projection optical system PL.

Below, the Z axis is taken in the direction parallel to the optical axis AX of the projection optical system PL, and the X axis is taken in the plane parallel to the plane of FIG. The description will be given by taking the Y axis in the vertical direction. The wafer W is held on the wafer stage 4 via a wafer holder (not shown). Wafer stage 4 is a step-and-repeat type X
The wafer W is positioned in the Y and Y directions, and the wafer W can be moved in the Z direction by the autofocus method. The X-direction and Y-direction coordinates of the wafer stage 4 are constantly measured by the laser interferometer 101, and the measurement result is supplied to the main control system 100 that controls and controls the operation of the entire apparatus, and the main control system 100 is set to the supplied coordinates. Based on this, the operation of the wafer stage 4 is controlled via the stage drive system 102.

The main body portion (exposure main body portion) of the projection exposure apparatus described above is installed in a chamber 41 controlled to be constant temperature and constant humidity for the purpose of stabilizing the dimensional accuracy during alignment and during exposure. Has been done. Next, the alignment system of this example will be described. The alignment system of this example is
This is an LIA type and heterodyne type alignment system with a plurality of wavelengths. In FIG. 1, since the detection principle of the alignment system is the same in the X direction and the Y direction, only the Y direction detection system is shown. . Then, in each shot area of the wafer W of the present example, the X-axis and Y-axis are formed, respectively.
A diffraction grating wafer mark for the axis is attached. Here, the wafer mark 3Y on the Y axis is the detection target. As shown in FIG. 2, the wafer mark 3Y is an uneven diffraction grating mark formed along the Y axis at a predetermined pitch.

In FIG. 1, two laser light sources 9 and 10 for supplying an alignment light beam have different oscillation wavelengths λ.
A chamber 41 having an exposure main body part 1 and λ2.
Is installed inside another chamber 42 provided outside. The chambers 41 and 42 are independently air-conditioned. In the chamber 42, the laser beam LB1 having the wavelength λ1 and the laser beam having the wavelength λ2 emitted from the laser light sources 9 and 10 of the single mode optical fibers 31 and 32 pass through the coupling optical systems 11 and 12, respectively. The light enters the end portions 31a and 32a. The optical fibers 31 and 32 have laser beams LB1 and LB1, respectively.
The one having the transmission efficiency optimized for the wavelengths λ1 and λ2 of LB2 and having a small attenuation is used. The other ends 31b and 32b of the optical fibers 31 and 32, respectively.
Is inside the chamber 41, and the laser beams LB1, L
B2 is transmitted from the inside of the chamber 42 to the inside of the chamber 41 via the optical fibers 31 and 32, respectively, without being exposed to the air in the clean room.

Next, in the chamber 41, the optical fiber 3
Laser beam LB emitted from end portions 31a and 32b of 1, 32
1, LB2 are converted into parallel light by lenses 13 and 14, respectively, and are combined into one laser beam LB3 through a dichroic mirror 15 as a light beam combiner, and an acousto-optical element as a heterodyne beam generating system (hereinafter It is incident on “AOM”) 16. Since the driving frequency of the AOM is extremely high at present, for example, two AOMs are driven by a high frequency signal having a predetermined frequency difference to generate a laser beam (heterodyne beam) having a predetermined frequency difference. However, since this technique is well known, one AOM16 is shown below for simplicity.
Will be used to generate a heterodyne beam. That is, the AOM 16 is driven by the drive signal of the frequency fd, and has the function of changing the frequency of the diffracted light of each order diffracted inside by fd. The laser beam LB3 emitted from the dichroic mirror 15 is AOM
By passing through 16, a plurality of diffracted beams are obtained for the respective wavelengths λ1 and λ2. Here, ± 1 for simplification
Let us consider only the diffracted light.

Laser beam LB diffracted by AOM16
The ± first-order diffracted lights D ⁺¹ and D ⁻¹ of 3 are frequency-modulated by + fd and −fd with respect to the 0th-order diffracted lights, respectively. These diffracted lights D ⁺¹ and D ^-1 pass through the beam splitter 19 and then
The light beams are made parallel to each other by the lens 17, and the optical path is bent by the mirror 18 arranged between the projection optical system PL and the reticle R so as to be incident on the projection optical system PL, and after passing through the projection optical system PL. , Is focused on the lattice-shaped wafer mark 3Y formed on the wafer W.

FIG. 2 shows how the ± 1st-order diffracted lights D ⁺¹ and D ^-1 are incident on the wafer mark 3Y. In FIG.
Order diffracted light D ^{+ 1} is made of the diffracted light D2 ⁺¹ diffracted light D1 ^+1, and wavelength λ2 of the wavelength .lambda.1, -1 diffracted beam D1 ^-1 order diffracted light D ^-1 is also wavelength .lambda.1, and diffraction wavelength λ2 consisting of optical D2 ^-1. Here, the pitch of the wafer marks 3Y is selected so that the interference light DS composed of the ± first-order diffracted lights generated from the wafer mark 3Y by the irradiation of the ± first-order diffracted lights D ⁺¹ and D ⁻¹ is generated vertically upward. . Therefore, from the wafer mark 3Y, ⁺ of the diffracted lights D1 ⁺¹ and D1 ^-1 of the wavelength λ1 is obtained.
1-order diffracted light DS1 ^+1, and -1 interference light DS1 consisting order diffraction light DS1 ^-1, diffracted light D2 ^{+ 1} wavelength .lambda.2, D2 ^-1 of the respective order diffracted light DS2 ^+1, and -1-order diffracted light D
The interference light DS2 of S2 ⁻¹ is generated vertically upward.
The combined light flux of the interference lights DS1 and DS2 is an interference light D of two wavelengths.
Called S. Both laser beams of wavelengths λ1 and λ2 are +1
Since the second-order diffracted light D ⁺¹ and the -1st-order diffracted light D ^-1 have a frequency difference of 2fd, the interference light of two wavelengths generated from the wafer mark 3 by irradiation of the ± first-order diffracted lights D ⁺¹ and D ^-1. The optical beat component of frequency 2fd is included in DS. This optical beat component becomes an optical signal for heterodyne detection.

Returning to FIG. 1, the interference light DS is generated by the projection optical system P.
Laser beam LB in the order of L, mirror 18, lens 17
3 returns to the reverse of the optical path which has reached the wafer mark 3Y, and enters the photoelectric detector 20 formed of a photodiode or the like by the beam splitter 19. The wafer beat signal SW of frequency 2fd obtained by photoelectrically converting the interference light DS of two wavelengths by the photoelectric detector 20 is supplied to the alignment processing system 103. The alignment processing system 103 internally generates a reference beat signal having a frequency of 2fd using the drive signal for the AOM 16, and the reference beat signal and the wafer beat signal SW.
Of the wafer mark 3Y in the Y direction based on this phase difference and supplies it to the main control system 100. In the main control system 100, for example, the position shift amount (phase difference) is 0. When the wafer stage 4 is driven so that
Coordinates. Similarly, the coordinates of the wafer mark on the X axis are also detected. Then, the shot area is aligned and the pattern image of the reticle R is exposed based on the detected coordinates.

At this time, in this example, the two laser light sources 9 and 10 of the alignment optical system, which can be heat sources, are installed in the chamber 42 different from the chamber 41 in which the exposure main body is installed. , And the wafer W, which is the exposed object, is not adversely affected by thermal expansion or the like. Also,
Laser beam L between chamber 41 and chamber 42
Since the transfer of B1 and LB2 is performed by the optical fibers 31 and 32, the disturbance of the wavefronts of the laser beams LB1 and LB2 caused by the fluctuation of the outside air (air in the clean room) of the chambers 41 and 42 is prevented, and the accuracy is always high. The alignment is done.

Further, in this example, the laser beam LB1 having the wavelength λ1 and the laser beam LB2 having the wavelength λ2 generated in the chamber 42 have the single-mode optical fibers 31 having optimized transmission efficiencies at the corresponding wavelengths, Three
2, and the laser beam of each wavelength is used to perform position detection with a high SN ratio by combining the two laser beams in the chamber 41 in the vicinity of the exposure main body using the dichroic mirror 15. In addition, since a plurality of wavelengths are transmitted by the same optical fiber, it is possible to average and remove noise generated by disturbance of the optical fiber such as vibration occurring at the time of transmission at each wavelength, thereby improving alignment accuracy.

Next, a second embodiment of the present invention will be described with reference to FIG. In this example, a laser light source having a plurality of wavelengths for alignment is housed in a small chamber provided in the chamber housing the exposure main body. In FIG. 3, parts corresponding to those in FIG. 1 are the same. Reference numerals are given and detailed description thereof is omitted. The configuration of the exposure main body and the alignment system and the position detection method are the same as those in the first embodiment.

FIG. 3 shows a projection exposure apparatus of this example. In FIG. 3, the chamber 41A is a modification of the chamber 41 of FIG. 1 so that the chamber 42 can be housed therein. The same exposure main body and a small chamber 43 are housed. The internal structure of the chamber 43 is the same as that of the chamber 42 of FIG. Then, the two-wavelength laser beams LB1 and LB2 generated inside the chamber 43 are transmitted to the alignment optical system outside the chamber 43 via the optical fibers 31 and 32, respectively.

In FIG. 3, the present embodiment is different from the first embodiment in that the chamber 43 is provided inside the chamber 41A, so that the optical fibers 31 and 32 can pass through the air in the external clean room. There is no. Also, chamber 4
There is an air conditioner 51 outside 1A, and ventilation pipes 51a and 5a are provided.
It is connected to the chamber 43 through 1b. The inside of the chamber 43 is air-cooled by the air conditioner 51,
The heat generated from the laser light sources 9 and 10 is discharged to the outside of the chambers 41A and 43, and the heat is prevented from flowing into the chamber 41A through the partition wall of the chamber 43. Therefore, the alignment is performed with high accuracy.

Here, the chamber 43 has a sufficient heat insulating structure, and the heat conduction into the chamber 41A due to the air cooling of the chamber 43 can be ignored. Further, since the air conditioner 51 is installed outside the chamber 41A and sucks and exhausts air through a duct or the like having a high heat insulation effect, the influence of heat generation of the air conditioner 51 can also be ignored. Furthermore, in this example, the optical fibers 31 and 32 do not touch the outside air (air in the clean room) even for a moment, so that noise due to vibration of the optical fibers caused by fluctuations of air and the like is further reduced.

Next, a third embodiment of the present invention will be described with reference to FIGS. 4 and 5. In this example, the present invention is applied to a projection exposure apparatus having an LSA type alignment system, and in FIG. 4, parts corresponding to those in FIG. 1 are denoted by the same reference numerals and detailed description thereof will be omitted. FIG. 4 shows a projection exposure apparatus of this example. In FIG. 4, since the principle of alignment is the same in the X direction and the Y direction, only the alignment system in the Y direction is shown.

In FIG. 4, as in the example of FIG. 1, the wavelengths λ1 and λ1 are emitted from the laser light sources 9 and 10 in the chamber 42, respectively.
Laser beams LB1 and LB2 of λ2 are emitted.
The laser beam L introduced from the chamber 42 into the chamber 41 by the optical fibers 31 and 32, respectively.
B1 and LB2 are converted into parallel light fluxes through lenses 13 and 14, respectively, and then enter a dichroic mirror 15 to be combined into one laser beam LB3. The laser beam LB3 passes through the beam splitter 19 and enters the projection optical system PL via the mirror 18 provided between the projection optical system PL and the reticle R, and the vicinity of the wafer mark on the wafer W from the projection optical system PL. Is irradiated.

FIG. 5 shows a wafer mark 3XA in the form of an X-axis dot row for the LSA system, which is attached to one shot area SA on the wafer W, and dots formed at a predetermined pitch in the X-direction for the Y-axis. A row-shaped wafer mark 3YA and a laser beam LB3 that is a Y-axis alignment light beam focused into a slit in the X direction are shown. In FIG. 5, the wafers used in the first and second embodiments are shown. The mark 3Y is in the shape of a diffraction grating having a predetermined pitch, whereas the wafer mark 3YA of this example is composed of dot rows (point array shape) formed at a predetermined pitch. Here, when the wafer stage 4 of FIG. 4 is scanned in the Y direction and the wafer mark 3YA reaches a position where the wafer mark 3YA crosses the converging region of the laser beam LB3, a plurality of orders of diffracted light are generated from the wafer mark 3YA.

Returning to FIG. 4, for simplification, only the 0th-order diffracted light and the + 1st-order diffracted light from the wafer mark 3YA for the laser beams LB1 and LB2 having the wavelengths λ1 and λ2, which are the components of the laser beam LB3, will be considered. 0th-order diffracted light of laser beam LB1 having wavelength λ1 and +
The first-order diffracted lights are DY ¹⁰ and DY ¹¹ , respectively, and the 0th-order diffracted light and the + 1st-order diffracted light of the laser beam LB2 having the wavelength λ2 are DY ²⁰ and DY ²¹ , respectively. The diffracted light of each of these orders is guided to the beam splitter 19 via the projection optical system PL and the mirror 18, and the optical path of the diffracted light is deviated from the laser beam LB3 as the incident light toward the photoelectric detector 20. . Beam splitter 1
9 and the photoelectric detector 20 between the zero-order diffracted light DY ¹⁰ , DY ²⁰
Of the optical path is provided with the spatial filter 21, spatial filter 21 is 0 is generated regardless of the presence or absence of coincidence between the wafer mark 3YA the laser beam LB3-order diffracted light D ¹⁰ by the reflection on the wafer W, D ²⁰ is shaded.

[0035] Therefore, to detect a light beam that occurs when the wafer mark 3YA the laser beam LB3 are matched order diffracted light DY ^11, DY ²¹ only by the photoelectric detector 20, the detected order diffracted light DY ^11, DY ²¹ The position of the wafer mark 3YA is detected based on the intensity of the. That is, the detection signal SWA which is a photoelectric conversion signal from the photoelectric detector 20 is supplied to the alignment processing system 103A. Further, the main control system 100A, which controls the operation of the entire apparatus of this example, moves the wafer stage 4 in the Y direction via the stage drive system 102 based on the coordinates of the wafer stage 4 by the laser interferometer 101. The measurement value of the laser interferometer 101 is also supplied to the alignment processing system 103A. Then, in the alignment processing system 103A, for example, the detection signal SWA
The Y-coordinate of the wafer stage 4 when the value of is peaked is held as the Y-coordinate of the wafer mark 3YA, and the held coordinates are supplied to the main control system 100A. Similarly, the X coordinate of the LSA type wafer mark on the X axis is also detected.

At this time, in this example, since the laser light sources 9 and 10 as heat sources are housed in the chamber 42 independent of the chamber 41 of the exposure main body, the exposure main body is affected by heat. Position detection is performed with high accuracy. Furthermore,
In this example, since the laser beams LB1 and LB2 having a plurality of wavelengths are used as the alignment light in spite of the LSA method, the detection signal at a certain wavelength is small due to the influence of the thin film interference of the photoresist and the shape of the wafer mark. However, since the detection signal of another wavelength is effective, the alignment is always performed with high accuracy. In addition, the laser beams LB1 and LB are transmitted by the optical fibers 31 and 32 which are different for each wavelength.
Since 2 is transmitted, there is an advantage that the laser beams of each wavelength can be used with maximum efficiency.

In each of the above-mentioned three embodiments, the TTL alignment system is shown.
It is obvious that the present invention can be applied to a TR (through the reticle) system and an off-axis system alignment system. Also, regarding the wavelength of the alignment light,
Not only two wavelengths but also three or more wavelengths may be used.

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.

[0039]

According to the present invention, a position detecting system for aligning a mask pattern and a photosensitive substrate is provided with a laser light source for generating laser light of a plurality of wavelengths and a laser light from the laser light source on the photosensitive substrate. A heat emission source having an irradiation optical system for irradiating the alignment mark and a light receiving optical system for receiving the laser light from the alignment mark, and the laser light source being arranged separately from the exposure main body. There is an advantage that the adverse effect on the exposure main body portion and the photosensitive substrate due to the heat generation of the laser light source of a plurality of wavelengths, which becomes the above, can be eliminated and highly accurate position detection can be performed using the light fluxes of a plurality of wavelengths.

Further, when the laser light of a plurality of wavelengths from the laser light source is guided to the irradiation optical system through the optical guides which are different for each wavelength, the transmission efficiency of the laser light of each wavelength can be increased and the optical guide for vibrations and the like can be obtained. Even if noise is generated due to the disturbance of, the noise can be removed by averaging over the entire wavelength, and therefore highly accurate position detection can be performed. Further, when the light receiving optical system receives the diffracted light generated in the predetermined direction from the alignment mark by the laser light, for example, L
The position can be detected by the IA method.

Further, the irradiation optical system irradiates the dot-shaped mark as the alignment mark with laser light of a plurality of wavelengths, and the dot-shaped mark is generated based on the light amount of the diffracted light received by the light receiving optical system. When the position detection is performed, the position detection of the LSA method of a plurality of wavelengths becomes possible. Therefore, LSA
The method can also reduce the influence of thin film interference of the photosensitive material.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a projection exposure apparatus having an LIA type alignment system as a first embodiment of an exposure apparatus of the present invention.

FIG. 2 is an enlarged view showing a laser beam with which the wafer mark 3Y in FIG. 1 is irradiated and diffracted light from the wafer mark 3Y.

FIG. 3 is a configuration diagram showing a second embodiment of an exposure apparatus of the present invention.

FIG. 4 is a configuration diagram showing a third embodiment of an exposure apparatus of the present invention.

FIG. 5 is a wafer mark 3XA, 3Y on the wafer W of FIG.
It is a top view which shows A and the laser beam LB3.

[Explanation of symbols]

 1 exposure light source system 2 illumination optical system 3Y LIA type wafer mark 3YA LSA type wafer mark 4 wafer stage 9, 10 laser light source 11, 12 imaging optical system 13, 14, 17 lens 15 dichroic mirror 16 AOM (acoustic optics) Element) 18 mirror 19 beam splitter 20 photoelectric detector 31,32 optical fiber 41,41A chamber 42,43 chamber R reticle W wafer PL projection optical system

Claims (4)

[Claims] 1. An exposure main body for transferring a mask pattern onto a photosensitive substrate, and a position detection system for detecting the position of an alignment mark on the photosensitive substrate, and based on a detection result of the position detection system. In an exposure apparatus that performs exposure by aligning the mask pattern with the photosensitive substrate, the position detection system includes a laser light source that generates laser light of a plurality of wavelengths, and the laser light from the laser light source is applied to the photosensitive substrate. An irradiation optical system that irradiates the upper alignment mark and a light receiving optical system that receives the return light from the alignment mark, and the laser light source is arranged separately from the exposure main body. An exposure apparatus. 2. The exposure apparatus according to claim 1, wherein laser light of a plurality of wavelengths from the laser light source is guided to the irradiation optical system via light guides that are different for each wavelength. 3. The exposure apparatus according to claim 1, wherein the light receiving optical system receives diffracted light generated in a predetermined direction from the alignment mark by the laser light. Exposure equipment. 4. The exposure apparatus according to claim 3, wherein the irradiation optical system irradiates the dot-shaped marks as the alignment marks with the laser beams of the plurality of wavelengths, and The exposure apparatus is characterized in that the position of the dot array mark is detected based on the amount of diffracted light received.