JP2001250763A - Aligner and exposure method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aligner and method which does not require a dedicated reticle for exfoliating a metal film or an insulating film formed on an alignment mask, can exfoliate a metal film or an insulating film without reducing the throughput, and enhances superposing accuracy by measuring the position information on the mark with high accuracy. SOLUTION: An aligner in which illuminating light from an illuminating source irradiates the reticle R, and a pattern image formed on the reticle R is reprinted on a wafer is installed on a mask stage 11 which supports the reticle R. The aligner is provided with openings 37 and 38 having the shape corresponding to the alignment mask formed on the wafer, and a reticle blind provided between the light source and the reticle stage 11. The illuminating light, being shaped by the reticle blind and the openings 37 and 38, exposes the alignment mask, and the metal film or the insulating film formed on the alignment mask is exfoliated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus and an exposure method used in a process of manufacturing a device such as a semiconductor device or a liquid crystal display device, and more particularly to a method for forming a metal wiring on an element on which a predetermined circuit is formed. The present invention relates to an exposure apparatus and an exposure method suitable for use in such a case.

[0002]

2. Description of the Related Art In the manufacture of devices such as semiconductor devices and liquid crystal display devices, a process for transferring and developing an image of a mask or reticle on which a circuit pattern is formed on a wafer coated with a photosensitive material is performed. Manufactured repeatedly. For example, in the manufacture of semiconductor devices, images of various patterns formed on a mask by an exposure device are transferred to a photoresist coated on a wafer to form a latent image, developed, and then etched and ion-implanted. Then, various processes such as a sputtering process are performed to form various electronic components such as transistors including a source, a drain, and a gate on the wafer. Thereafter, these are generally connected by a metal wiring such as aluminum, and finally, an oxidation prevention film is generally formed of silicon dioxide or the like in order to prevent deterioration of device characteristics due to oxidation.

[0003] The metal wiring is formed by the following steps. First, a film (hereinafter, referred to as a metal film) made of a metal material such as aluminum is formed on a semiconductor substrate on which electronic components such as transistors are formed by sputtering or the like, and a spin coater is used on the formed metal film. And apply photoresist. Next, the position of the reticle on which the metal wiring pattern is formed is accurately aligned with the position of the wafer on which the photoresist has been applied using an exposure apparatus, and exposure light is exposed on the reticle to form the reticle. The image of the formed metal wiring pattern is transferred onto the wafer coated with the photoresist. After that, the photoresist is developed, and a metal film such as aluminum at a portion where the photoresist has been removed by the development treatment is removed by etching. The metal wiring is formed by the above steps.

In forming the above-described metal wiring,
It is necessary to accurately align electronic components such as transistors formed on a wafer with wiring. The exposure device is
An alignment device is provided to accurately perform repeated superposition. The alignment apparatus includes an alignment sensor that detects a position of an alignment mark formed on a wafer, and a control system that performs alignment of the wafer based on the position of the alignment mark detected by the alignment sensor.

As described above with reference to the case of manufacturing a semiconductor device, since the surface state (roughness) of a wafer to be measured changes in the manufacturing process, the position of the wafer is determined by a single alignment sensor. It is difficult to detect accurately, and different sensors are generally used according to the surface condition of the wafer. The main alignment sensors are LSA (Laser Step Alignment)
Method, FIA (FieldImage Alignment) method, LIA
(Laser Interferometric Alignment) method. Hereinafter, outlines of these alignment sensors will be described.

The LSA type alignment sensor is an alignment sensor that irradiates a laser beam onto an alignment mark formed on a wafer and measures the position of the alignment mark by using diffracted and scattered light. Widely used for semiconductor wafers in the manufacturing process. The FIA type alignment sensor is an alignment sensor that illuminates the alignment mark using a light source having a wide wavelength bandwidth such as a halogen lamp and performs image processing on an image of the obtained alignment mark to perform position measurement. It is effective for measuring asymmetric marks formed on a layer or a substrate surface. The LIA type alignment sensor irradiates laser beams having slightly different wavelengths from two directions to a diffraction grating alignment mark formed on the substrate surface, and causes the resulting two diffracted lights to interfere with each other.
The alignment sensor detects the position information of the alignment mark from the phase of the interference light. This LIA type alignment sensor is effective when used for an alignment mark with a low step or a substrate having a large surface roughness.

[0007]

As described above, the FI
The A-type alignment sensor is suitable for measuring a mark formed on an aluminum layer, but a problem arises when a metal film such as aluminum covers an upper portion of the alignment mark. FIG. 12 is a cross-sectional view showing an alignment mark having a metal film formed on the surface. In FIG. 12, 100 is an alignment mark, and 102 is a metal film such as aluminum formed on the alignment mark 100. Irradiation light is irradiated on the alignment sensor 100,
An example of a measured waveform when the reflected light is measured by the FIA type alignment sensor is as shown in FIG.

FIG. 13 is a diagram showing an example of a measured waveform when an alignment mark having a metal film formed on the surface is measured. As shown in FIG. 13, the measurement waveform 104 is obtained by superimposing noise indicated by reference numerals 106a to 106c. This is mainly caused by grains of the formed metal thin film or the like. Here, the grain is a crystal grain such as a metal or an insulator. Although the surface of the formed metal film in FIG. 12 is smooth at first glance, many fine grains are formed. Further, the grains are formed not only in the metal film 102 but also in the metal film 102. Since the metal film 102 has a property of almost reflecting the illumination light, if the grain is formed, the illumination light is reflected in various directions. Therefore, the reflected light due to the grain is shown in FIG. Noise 10
6a to 106c.

FIG. 1 shows an FIA type alignment sensor.
The position information of the alignment mark 100 is measured based on the waveform 104 shown in FIG. 3 by using an algorithm such as an edge detection method. As shown in FIG.
04 is superimposed with the noises 106a to 106c,
An error occurs when the position information of the alignment mark 100 is measured. As described above, since it is necessary to accurately position electronic components such as transistors formed on a wafer and wirings, it is necessary to minimize such measurement errors.

Therefore, conventionally, the alignment mark 100
A step of removing the metal film 102 formed thereon is provided so that a measurement error of the alignment mark 100 due to the grain does not occur. FIG. 14 is a diagram illustrating a conventional method for reducing a measurement error caused by grains. In this method, first, a photoresist 108 is formed on the metal film 102 shown in FIG.
Is applied to the entire surface, and the reticle mounted on the reticle stage of the exposure apparatus is aligned with the alignment mark 100.
The reticle is replaced with a special reticle for peeling the metal film 102 formed on the upper portion of the substrate, and after exposure, development processing is performed.

By performing the above steps, FIG.
As shown in FIG. 1A, a photoresist having a shape in which only the upper part of the alignment mark 100 is removed is formed.
Then, the alignment mark 100 is etched.
The metal film 102 formed on the upper portion is peeled off. When the metal film 102 formed on the alignment mark 100 is peeled off, the upper part of the alignment mark 100 is opened, so that the above-described measurement error due to the grain does not occur, which is preferable for high accuracy.

However, by removing the metal film 102 above the alignment mark 100 through the above-described steps, the position measurement accuracy is improved, but a reticle dedicated to peeling the metal film 102 above the alignment mark 100 is manufactured. There is a problem that it is necessary. Also,
During the exposure process, the reticle on the reticle stage of the exposure apparatus is exchanged, and a photoresist 108 is applied on the metal film 102 to perform exposure, and after the exposure, the photoresist 108 is developed to perform an etching process. In addition, there is a problem in that the number of steps is increased, and the throughput, that is, the number of wafers that can be processed in a unit time is reduced.

The present invention has been made in view of the above circumstances, and does not require a special reticle for peeling off a metal film or an insulating film formed on an alignment mark, and furthermore, reduces the throughput. It is an object of the present invention to provide an exposure apparatus and an exposure method that can peel a metal film without inviting the mark and measure the position information of the mark with high accuracy to improve the accuracy of overlay.

[0014]

In order to solve the above-mentioned problems, an exposure apparatus according to the present invention irradiates an illumination light (IL) generated from an illumination light source (1) onto a mask (R) so as to illuminate the mask (R). An exposure apparatus for transferring an image of a pattern formed on a substrate (W) to a substrate (W), the exposure apparatus being provided on a mask stage (11) holding the mask (R), Marks for alignment (AM, AM _X , AM _Y )
Opening (37, 38) having a shape corresponding to the above, illumination light provided between the illumination light source (1) and the mask stage (11), and illuminated toward the mask stage (11). And a shaping means (9) for shaping the (IL) into a desired shape. In order to solve the above-mentioned problem, the exposure method of the present invention irradiates illumination light (IL) onto a mask (R) arranged on a mask stage (11), and irradiates the mask (R) with the illumination light (IL). An exposure method for transferring an image of a formed pattern onto a substrate (W) to which a predetermined film (40) is fixed, wherein an illumination light (IL) irradiated toward the mask stage (11) is provided. , shaping to a shape of the mask stage (11) is placed on and mark formed on the upper substrate _{(W) (AM, AM X} , AM Y) opening (37, 38) having a shape corresponding to the and the mark _{(AM, AM X, AM Y} ) prior to detecting, the said formatted and illumination light through said opening (37,38) (IL) mark (AM, AM _X, AM _Y )
It is characterized in that the predetermined film (40) is peeled off by irradiating the film upward. According to such an exposure apparatus and an exposure method, a dedicated mask for removing the formed film is not required, and the film is removed using the shaping means and the opening placed on the mask stage. I have. Therefore, since a dedicated mask is not required for removing the film, the cost required for manufacturing the mask can be reduced. Further, since a dedicated mask for removing the film is not required, there is no need to replace the mask with a dedicated mask during the processing step, so that the throughput can be improved. In the above exposure apparatus, the shaping means (9) may be configured so that the illumination light (IL) is shaped into a shape corresponding to the openings (37, 38).
The openings (37, 38).
Is a reference member (3) installed on the mask stage (11) for use in positioning the mask (R).
2) It is characterized by being provided above. Also,
In the exposure apparatus, a metal film or an insulating film (40) is formed on the mark (AM, AM _X , AM _Y ), and the mark (AM, AM _X , AM _Y ) is formed through the shaping means (9) and the openings (37, 38). The mark (AM, A)
M _X, is characterized by peeling the AM _Y) on the metal film (40). According to such an exposure apparatus, a dedicated mask is not required when the metal film or the insulating film formed on the mark is peeled off, and the film is formed by using the shaping means and the opening placed on the mask stage. Since the separation is performed, the above-described effect can be obtained, and also, it is possible to prevent the detection accuracy of the mark from being lowered due to noise caused by forming the metal film or the insulating film on the mark. Further, in the above-mentioned exposure method, the opening (37, 38) may be such that the mask (R)
In order to use the mask stage (1)
1) It is provided on a reference member (32) provided thereon, and the predetermined film (40) includes a metal film or an insulating film. According to such an exposure apparatus, similarly to the above-described exposure apparatus, a dedicated mask is not required when removing a metal film or an insulating film formed on a mark, and the mask is mounted on a shaping means and a mask stage. Since the film is peeled off using the opening, the above-described effect is obtained, and also the detection accuracy of the mark is prevented from being deteriorated due to noise caused by the metal film being formed on the mark. be able to.

[0015]

Hereinafter, an exposure apparatus and an exposure method according to an embodiment of the present invention will be described in detail. FIG.
1 is a diagram showing a schematic configuration of an exposure apparatus according to an embodiment of the present invention. In this embodiment, the present invention is applied to a step-and-repeat type exposure apparatus including an off-axis type alignment sensor. In the following description, the XYZ rectangular coordinate system shown in FIG. 1 is set, and the positional relationship of each member will be described with reference to the XYZ rectangular coordinate system. The XYZ rectangular coordinate system uses the Y axis and Z
The axis is set to be parallel to the paper surface, and the X axis is set to a direction perpendicular to the paper surface. XY in the figure
In the Z coordinate system, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set vertically upward.

In FIG. 1, reference numeral 1 denotes an excimer laser light source as an illumination light source, which emits a laser beam LB as illumination light. As the excimer laser light source 1, KrF (wavelength 2
An excimer laser light source such as 48 nm) or ArF (wavelength 193 nm) can be used. As the illumination light source, other than the above-described excimer laser light source, for example, g-line (436n)
m), a light source such as i-line (365 nm), F ₂ (wavelength 157
nm), a pulsed light source such as a metal vapor laser light source or a harmonic generator of a YAG laser, or a beam generator of extreme ultraviolet light (EUV light) such as soft X-rays.

Reference numeral 2 denotes a beam shaping optical system constituted by a cylinder lens, a beam expander, and the like, and a cross section of the laser beam LB to be incident so that the laser beam LB efficiently enters the subsequent fly-eye lens 5. Shape the shape. Reference numeral 3 denotes an energy coarse adjuster for adjusting the output energy of the laser beam LB that has passed through the beam shaping optical system 2. The energy rough adjuster 3 has a plurality of ND filters having different transmittances (= 1-dimming ratio) arranged on a rotatable revolver. By rotating the revolver, an incident laser beam is emitted. 1 transmittance for LB
It is configured to be able to switch from 00% in multiple stages. Incidentally, a revolver similar to the revolver may be arranged in two stages in series, and the transmittance may be more finely adjusted by a combination of two stages of ND filters.

Reference numeral 4 denotes a mirror for bending the optical path of the laser beam LB emitted from the energy rough adjuster 3. The fly-eye lens 5 forms a number of secondary light sources from a laser beam LB incident via the mirror 4 to illuminate a reticle R described later with a uniform illuminance distribution. An aperture stop (a so-called stop) 6 of an illumination system is provided on the exit surface of the fly-eye lens 5.
Is arranged. The laser beam emitted from the secondary light source in the aperture stop 6 is hereinafter referred to as illumination light IL. 7 is
The beam splitter has a small reflectance and a large transmittance, and divides the illumination light IL in two directions with an intensity corresponding to the reflectance and the transmittance.

Illumination light IL transmitted through the beam splitter 7
Passes through the opening of the reticle blind 9 as a shaping means via the first relay lens 8A. The reticle blind 9 transfers the image of the pattern formed on the reticle R to the wafer W
When transferring to the upper side, the illumination light IL is shaped and the illumination light IL is illuminated to a portion other than the pattern formed on the reticle, thereby preventing an unnecessary image from being transferred onto the wafer W. Also, as described later, reticle stage 1
When aligning the wafer 1 with the wafer 1 and when peeling off the metal film or the insulating film formed on the alignment mark AM of the wafer W, the illumination light is illuminated so as to illuminate only a necessary portion on the reticle. Shape the IL.

Illumination light I having passed through reticle blind 9
L is the second relay lens 8B and the condenser lens 1
After 0, the reticle R mounted on the reticle stage 11 is illuminated with a uniform illuminance distribution. When the reticle R is illuminated by the illumination light IL, the image of the pattern formed on the reticle R is reduced at a projection magnification α (α is, for example, ４ ，, ５) by passing through the projection optical system PL. The image of the reduced pattern is transferred to a shot area set on the wafer W coated with the photoresist.
The wafer W is, for example, silicon or SOI (Silicon On I
nsulator). Here, it is assumed that a metal film is formed on the surface of the wafer W, and that a photoresist is applied on the metal film.

An off-axis type alignment sensor 12 is provided beside the projection optical system PL. The alignment sensor 12 detects an alignment mark formed on the wafer, and a detection result is output to a main controller 30 described later. Main controller 30 performs arithmetic processing on this detection result, measures the position information of the alignment mark formed on wafer W, and controls the position of wafer W based on the measurement information. FIG.
In the above, reference numeral 12a denotes a halogen lamp that generates illumination light of the alignment sensor 12.

The reticle stage drive unit 18 drives the reticle stage 11 under the control of the stage controller 17
Drive in the direction. The position of reticle stage 11 is measured by laser interferometer 16. Although the illustration is simplified in FIG. 1, the movable mirror 13 is composed of a plane mirror having a mirror surface perpendicular to the X axis and a plane mirror having a mirror surface perpendicular to the Y axis. The laser interferometer 16 has two Y-axis laser interferometers that irradiate the movable mirror 11 with a laser beam along the Y-axis and an X-axis laser interferometer that irradiates the movable mirror 11 with a laser beam along the X-axis. The X coordinate and the Y coordinate of the reticle stage 11 are measured by one laser interferometer for the Y axis and one laser interferometer for the X axis. The X coordinate, the Y coordinate, and the rotation angle of the reticle stage 11 measured by the laser interferometer 16 are supplied to the stage controller 17, and the stage controller 17 transmits the reticle stage 11 via the reticle stage driving unit 18 based on the supplied coordinates and the like. , The position and speed of the reticle stage 11 are controlled.

On the other hand, the wafer W is mounted on a tilt stage 19 via a wafer holder (not shown), and the tilt stage 19 is mounted on an XY stage 20. The XY stage 20 positions the wafer W in the X and Y directions. Further, the tilt stage 19 has a function of adjusting the position (focus position) of the wafer W in the Z direction and adjusting the inclination angle of the wafer W with respect to the XY plane. The movable mirror 14 is placed on the tilt stage 19.
Is fixed, and the XY stage 2 is
The position of 0 in the XY plane is measured. Although not shown in FIG. 1, the movable mirror 14 is composed of a plane mirror having a mirror surface perpendicular to the X axis and a plane mirror having a mirror surface perpendicular to the Y axis. In addition, the laser interferometer 22
A Y-axis laser interferometer that irradiates the movable mirror 14 with a laser beam along the axis and an X-axis laser interferometer that irradiates the movable mirror 11 with a laser beam along the X-axis; With one laser interferometer for the X axis and one laser interferometer for the X axis, the X coordinate and Y
The coordinates are measured. This configuration is similar to that for measuring the position information of the reticle stage 11. The X coordinate, Y coordinate, and rotation angle of the XY stage 20 measured by the laser interferometer 22 are supplied to the stage controller 17, and the stage controller 17 sends the XY stage via the wafer stage driving unit 23 based on the supplied coordinates and the like. 20 position and speed are controlled.

On the tilt stage 19, a reference mark 15 for adjusting the relative positional relationship between the reticle R and the stage on which the wafer W is mounted is arranged. The operation of the stage controller 17 is controlled by a main controller 30 that controls the entire apparatus. The main controller 30 mainly performs the operation of the exposure apparatus during exposure, performs a batch exposure operation with the wafer W stationary, performs a position measurement operation of the reticle R, or moves the reticle stage 11 to move the wafer. It is controlled whether or not to perform an exposure operation for removing the metal film formed on W. Details of main controller 30 will be described later.

In FIG. 1, of the illumination light IL incident on the beam splitter 7, the illumination light IL reflected by the beam splitter 7 is transmitted through a condenser lens 24 from a photoelectric conversion element as an energy sensor. Is received by the integrator sensor 25, and the photoelectric conversion signal of the integrator sensor 25 is supplied to the exposure controller 26 as an output DS (digit) via a peak hold circuit and an A / D converter (not shown). The output DS of the integrator sensor 25 and the pulse energy (exposure amount) of the illumination light IL per unit area on the surface (image plane) of the wafer W
Is obtained in advance and stored in the exposure controller 26.

The exposure controller 26 includes a main controller 30
Under the above control, the control information TS is supplied to the excimer laser light source 1 in synchronization with the stage system operation information from the stage controller 17, thereby controlling the light emission timing and the light emission power of the excimer laser light source 1. Further, the exposure controller 26 controls the N
Controlling the transmittance by switching the D filter,
The stage controller 17 controls the opening and closing operation of the reticle blind 9 in synchronization with the operation information of the stage system.
The stage controller 17 also controls the operation at the time of measurement under the control of the main controller 30. Further, under the control of the main controller 30, the stage controller 17 controls the opening and closing operation of the reticle blind 9 when performing an exposure operation for peeling the metal film formed on the wafer W.

Next, the configuration of the reticle stage 11 will be described in more detail. FIG. 2 shows a reticle stage 11.
3A is a top view of the reticle stage 11, and FIG. 3B is a cross-sectional view of the reticle stage. As shown in FIG. 2B, the reticle R is placed on the opening 33 formed in the reticle stage 11, and is formed on the reticle R generated by illuminating the reticle R with illumination light from above. The configuration is such that the image of the pattern can be made incident on the projection optical system PL located below. The reticle stage 11 has
A reference plate 32 used for aligning the reticle stage 11 and the XY stage 20 is mounted. An opening 34 is formed at a position of the reticle stage 11 where the reference plate 32 is placed, and an image obtained when the reference plate 32 is illuminated from above with the illumination light IL shaped using the reticle blind 9 is projected. It is configured to be able to enter the optical system PL.

The reference plate 32 is, as shown in FIG.
Cross marks 35 and 36 for alignment are formed. Further, openings 37 and 38 used for peeling the metal film formed on the wafer W are formed. The reference plate 32 is made of a glass substrate, and the cross marks 35 and 36 for positioning and the openings 37 and 38 are formed by depositing chrome on the glass substrate. In the present embodiment, the wafer W shown in FIG. 3A and 3B are views for explaining a wafer W used in the present embodiment, wherein FIG. 3A is a top view of the wafer W, and FIG. 3B is a cross-sectional view of the wafer W. As shown in FIG. 3A, a plurality of shot areas, that is, areas D, D,... To which an image of a pattern formed on the reticle R is transferred are set on the wafer W, and each shot area D, Alignment marks AM, AM,... For position measurement of the wafer W are formed corresponding to D,.

[0029] In the present embodiment, the alignment mark shall be made of the alignment mark AM _Y for measuring the position on the alignment mark AM _X and Y axis to measure the position of the wafer W on the X-axis.
In the following description, when describing without distinguishing between the alignment marks AM _X and the alignment mark AM _Y is collectively referred to as the alignment marks AM. In addition, the wafer W
A metal film 40 is formed on almost the entire upper surface, and FIG.
It is assumed that the metal film 40 is also formed on the alignment mark AM as shown in FIG. Further, the metal film 40
It is assumed that a photoresist 41 is applied to the upper surface of the substrate.

[0030] As shown in FIG. 3 (a), the alignment mark AM consists the alignment mark AM _X and the alignment mark AM _Y, these are so-called Line
And space mark. Reference plate 32 described above
Openings 37, 38 formed in the alignment mark AM
It is formed in a shape conforming to the shape of _X and the alignment mark AM _Y. Figure 4 is a diagram for explaining a relationship between the shape of the opening 37, 38 and the alignment mark AM _X and the alignment marks AM _Y shape, (a) shows the opening 3
7 shows the relationship between the shape and the alignment mark AM _X shape, (b) the shape of the opening 38 and the alignment marks A
Is a diagram showing the relationship between the shape of M _Y. As shown in FIGS. 4A and 4B, the shapes of the openings 37 and 38 are images Im _X , obtained when the openings 37 and 38 are illuminated by the illumination light IL shaped by the reticle blind 9.
Im _Y is set to a shape of irradiating the whole of the alignment mark AM _X and the alignment mark AM _Y respectively.

Next, the positioning of the reticle stage 11 and the XY stage 20 using the reference plate 32 placed on the reticle stage 11 and the reference mark 15 placed on the tilt stage 19 will be described. FIG. 5 shows a reference mark 1 placed on the tilt stage 19.
FIG. 5 is a top view of FIG. As described above, the cross marks 35, 36 are formed on the reference plate 32, and the cross marks 42, 42 having a shape corresponding to the shapes of the cross marks 35, 36 are provided.
43 is formed on the reference mark 15. That is, the cross marks 42 and 43 have a shape obtained by substantially reversing the cross marks 35 and 36 vertically and horizontally at a reduction magnification of the projection optical system PL.

In this embodiment, the cross marks 35 and 36 formed on the reference plate 32 and the cross marks 42 and 43 formed on the reference mark 15 are arranged on an observation optical system (shown in FIG. 1) disposed above the reticle stage 11. The so-called TTR (through through) is used to observe the displacement by observing with
The reticle) method is used. FIG. 6 shows the reference plate 32.
FIG. 7 is a diagram showing an example of observation results of cross marks 35 and 36 formed on the reference mark 15 and marks 42 and 43 formed on the reference mark 15. In FIG. 6, for convenience of explanation, the cross mark 4
2 and 43 are shown as projected images projected on the reticle stage 11 via the projection optical system PL. In FIG. 6, L11 and L12 are cross marks 35 and 36, respectively.
L21 and L22 are observation images of the cross marks 42 and 43, respectively.

At the time of observation, first, the reticle blind 9 is controlled to shape the illumination light IL so as to illuminate the reference plate 32 and not to illuminate unnecessary portions, for example, the reticle R. Next, the reference plate 32 is positioned in a region where the shaped illumination light IL is illuminated, and the reference mark 15 arranged on the tilt stage 19 is also a region conjugate to the region where the shaped illumination light IL is illuminated. Is positioned below. When the reference plate 32 and the reference mark 15 are positioned as described above, the image shown in FIG. 6 is observed. Reference plate 3
When the positions of the reference mark 2 and the reference mark 15 match, as shown in FIG. 6, the observation image L11 and the observation image L21, and the observation image L12 and the observation image L22 are observed while overlapping each other. Note that the displacement between the reticle stage 11 and the XY stage 20 and the relative rotation between the reticle stage 11 and the XY stage 20 in the XY plane are determined by the displacement between the observation image L11 and the observation image L21 and the displacement between the observation image L12 and the observation image L22. Therefore, accurate positioning can be performed by eliminating the amount of positional deviation and the amount of relative rotation.

Next, an exposure method according to one embodiment of the present invention applied to the exposure apparatus according to one embodiment of the present invention described above will be described. FIG. 7 is a flowchart illustrating an exposure method according to an embodiment of the present invention. FIG. 7
The flowchart shown in FIG. 7 shows a flow of processing performed by the exposure apparatus for removing the metal film 40 after the metal film 40 is formed and the photoresist 41 is applied on the metal film 40. The metal film 40 is generally formed to form a wiring for electrically connecting electronic elements formed on the wafer W.

Conventionally, an alignment mark A on a wafer W
In order to peel the metal film 40 formed on the M, a reticle dedicated to peeling is placed on the reticle stage 11, and after the peeling is completed, a reticle used in the next step is placed on the reticle stage 11. I needed to. In the present embodiment, a dedicated reticle for removing the metal film 40 is not required, and the cost for manufacturing the dedicated reticle is reduced by removing the reticle, which is necessary when removing the metal film 40, Further, the throughput is improved.

When the process is started, first, a process of setting an opening formed by the reticle blind 9 of the illumination light IL to a shaped shape of the illumination light is performed (step S1).
0). That is, in this process, the stage controller 17
Controls the reticle blind 9, for example, the illumination light IL
Controls the shape of the opening of the reticle blind 9 so that the shape illuminates only the opening 37 formed in the reference plate 32.

When the processing in step S10 is completed, the stage controller 17 moves the reticle stage drive
Is driven to move the reticle stage 11, and the reticle blind 9 is arranged so that the opening 37 or the opening 38 is located in a region irradiated with the illumination light IL shaped by the reticle blind 9. (Step S12) Here, in the case of separation of the metal film 40 which is formed on the alignment mark AM _X is arranged an opening 37 in a region where the illumination light IL is irradiated, formed on the alignment mark AM _Y When the removed metal film 40 is to be stripped, the opening 38 is arranged in a region irradiated with the illumination light IL.

When the arrangement of the opening 37 or the opening 38 is completed, the stage controller 17 controls the XY stage 20 via the wafer stage driving unit 23 to move the wafer W to the X position.
The alignment mark AM for removing the metal film 40 by moving in the Y plane is moved to the transfer area of the projection optical system PL (step S14). Here, among the alignment marks AM, will be described as an example the case of performing the separation of the metal film 40 which is formed on the alignment mark AM _X. When performing the separation of the deposited metal film 40 on the alignment mark AM _Y, the illumination light IL of the reticle blind 9
Are different from each other in that the shaping shape of the reference plate 32 is different from that of the first embodiment.

The movement of the XY stage 20 is performed by the stage controller 17 based on the measurement result of the laser interferometer 22, but the measurement accuracy of the laser interferometer 22 is, for example, about 0.01 μm. Illumination light IL
The aligned with sufficient accuracy to perform alignment between the position and the alignment mark AM _X of the image obtained by irradiating the opening 37.

When the alignment of the wafer W is completed, the elementary control system 30 outputs a control signal to the excimer laser light source 1 to emit a laser beam LB. The laser beam LB passes through a beam shaping optical system 2 composed of a cylinder lens, a beam expander, etc., and an energy coarse adjuster 3, and its optical path is bent by a mirror 4. To the illumination light IL. The illumination light IL emitted from the fly-eye lens 5 passes through the opening of the reticle blind 9 via the first relay lens 8A.

Here, the manner in which the illumination light IL is shaped by the opening 37 formed in the reticle blind 9 and the reference plate 32 will be described. FIG. 8 is a perspective view illustrating a state where the illumination light IL is shaped by the opening 37 formed in the reticle blind 9 and the reference plate 32. still,
Among the members shown in FIG. 8, the same members as those shown in FIG. 1 are denoted by the same reference numerals. In FIG. 1,
A second relay lens 8 is provided between the reticle blind 9 and the reticle R, the reference plate 32, and the reticle stage 11.
B and the condenser lens 10 are provided.
Are omitted from the drawing for easy understanding.

First, the illumination light IL is applied to the reticle blind 9.
Is irradiated, the illumination light IL is shaped into the shape of the opening 9A of the reticle blind 9. Reticle blind 9A
The illumination light IL shaped by the second relay lens 8
The opening 37 is illuminated via B and the condenser lens 10 (not shown in FIG. 8). As shown in FIG. 8, the illumination light I shaped by the reticle blind 9
L has a substantially rectangular cross-sectional shape, and is large enough to surround the periphery of the opening 37. In addition, the opening 37 is the reference plate 3
2, the illumination light IL shaped by the reticle blind 9 is not set to be larger than the shape of the deposited metal, as shown in FIG. This is to prevent unnecessary illumination light IL from irradiating the wafer W.

Shaped by the reticle blind 9,
The illumination light IL transmitted through the opening 37 is transmitted through the projection optical system PL (FIG.
Is reduced at a predetermined reduction ratio by not shown) in the image Im _X of the opening 37 is irradiated on the alignment mark AM _X formed on the wafer W. As shown in FIG. 8, the dimensions of the image Im _X is set so surrounding the alignment mark AM _X. Since usually the alignment marks AM formed on the street line (scribe line) located between the shot areas D and another shot area D shown in FIG. 3 (a), the image Im _X and the alignment mark AM High alignment accuracy is not required. In this way, the image Im _X is transferred onto the photoresist 41 coated on the upper surface of the metal film 40 which is formed on the alignment mark AM _X (step S16).

[0044] When the transfer of the image Im _X of the opening 37 is completed,
Next, it is determined whether the transfer has been completed for all of the alignment marks to be processed (step S18). In this case, the processing target may be set to transfer to all the alignment marks AM formed on the wafer W, and several of the alignment marks AM among the alignment marks AM formed on the wafer may be set. It may be set only for AM. If it is determined in step S18 that there is an alignment mark that has not been processed among the alignment marks to be processed, that is, if the determination result in step S18 is "NO", the process returns to step S14, and the process returns to step S14. Is repeated. On the other hand, if it is determined that the processing has been completed for all the alignment marks to be processed, that is, step S1
If the result of the determination in step 8 is "YES", the process ends.

When the above processing is completed, the processed wafer W is unloaded from the exposure apparatus, developed, and the image Im of the photoresist 41 applied on the metal film 40 is developed.
Only the portion to which _X has been transferred is removed to expose the metal film 40 on the surface, and then the metal film 40 is peeled off by performing processing such as etching. By this processing, the alignment mark 40 itself appears on the surface.

After that, the wafer W having undergone the developing process and the etching process is carried into the exposure apparatus, and the reticle R mounted on the reticle stage 11 is replaced with a reticle R used in the next step. Further, the reticle stage 11 is driven to place the reticle R at a position at the time of exposure. Thereafter, the position information of the alignment mark AM formed on the wafer W is measured using the alignment sensor 12, and the stage controller 17 drives the XY stage 20 via the wafer stage driving unit 23 based on the measurement result, After aligning the shot area D set on the wafer W with the exposure position of the projection optical system PL, the exposure light IL is irradiated onto the reticle R to transfer the image of the pattern formed on the reticle R onto the wafer W. To perform exposure processing.

In the above-described exposure apparatus and exposure method according to an embodiment of the present invention, the case where the problem when the metal film is formed on the alignment mark AM has been described as an example. The present invention can be applied to a case where an insulating film is formed on the alignment mark AM. Next, a process used for element isolation will be described. FIGS. 9A to 9E are views for explaining steps used in element isolation. FIGS. 9A to 9E show wiring layers with a metal film or an insulating film remaining in a mark element am for forming an alignment mark AM. FIGS. 4E to 4I are diagrams illustrating steps in the case of forming a wiring layer after removing a metal film or an insulating film in a mark element am. FIGS.

In the steps from FIG. 9A to FIG. 9D, as shown in FIG. 9A, a metal film or an insulating film (hereinafter, referred to as FIG. In the description, a “film” 50 is formed (FIG. 9).
(B)). Thereafter, the film 50 formed on the surface of the wafer W is removed by performing CMP (chemical mechanical polishing). By performing such processing, the surface of the wafer W becomes flat, and the film 50 remains only in the mark element am. Then, the wiring layer 52 is formed on the wafer W on which the CMP process has been performed. Wiring layer 5
In the formation of 2, the position information is measured using the alignment mark AM in the state shown in FIG. 9C. After the wiring is formed, the position information is measured using the alignment mark AM in the state shown in FIG. 9D. Therefore, in these cases, since the surface of the wafer W is flat, it is not preferable to measure the position information with high accuracy.

In the steps from FIG. 9E to FIG. 9I, a film 50 is formed on the wafer W on which the mark element am is formed as shown in FIG. f)). Thereafter, CMP is performed to remove the film 50 formed on the surface of the wafer W. By performing such processing, the surface of the wafer W becomes flat, and the film 50 remains only in the mark element am (FIG. 9G). Next, a step of removing the film 50 remaining in the mark element am is performed on the wafer W that has been subjected to the CMP processing (FIG. 9H). 54 are formed. In forming the wiring layer 54, measurement of position information is performed using the alignment mark AM in the state shown in FIG. Also,
After the formation of the wiring, the position information is measured using the alignment mark AM in the state shown in FIG. Therefore, in these cases, since there is a step on the surface of the wafer W, it is preferable to measure the position information with high accuracy. After the formation of the wiring layer 54, if the wiring layer 54 of only the alignment mark AM in the formed wiring layer 54 is removed using the above-described embodiment of the present invention, further improvement in accuracy can be achieved. desired. The wiring layers 52, 54
Is generally formed using polysilicon (non-metal), but may be formed using a metal-based material.

In this embodiment, as shown in FIG. 8, the image Im _{X of the} opening 37 is aligned with the alignment mark AM _X.
And the magnitude of the same order but the dimensions of the opening 37 is set, the present invention is not limited thereto, the image Im _X of the opening 37 the dimensions of the opening 37 to the small circle size than the alignment mark AM _X It may be set. FIG. 10 is a diagram for explaining a method of exposing the entire alignment mark when the size of the opening 37 is set small. In FIG. 10A, Im1 shows an image of the opening 37 on the wafer W, and in FIG. 10B, Re shows an area occupied by the alignment mark AM formed on the wafer W. Note that the area Re is larger than the image Im1, and even if the image Im1 is simply transferred onto the area Re once, the entire area is not exposed. In such a case, the reticle stage 11 or the XY stage 20 is driven to perform scanning or stepping while FIG.
As shown in (1), by transferring the image Im1 to the entire region R, the metal film or the insulating film formed on the alignment mark AM can be removed. In addition, by repeating the operation of performing the transfer while performing such scanning or stepping, it is possible to transfer a wider area.

Although the exposure apparatus and the exposure method according to one embodiment of the present invention have been described above, the present invention is not limited to the above embodiment, and the design can be freely changed within the scope of the present invention. For example, in the above-described embodiment, the case where the position information of the alignment mark AM is measured using an FIA type alignment sensor which is an off-axis type is described as an example. However, the present invention is not limited to this, and an LSA type alignment sensor is used. And an LIA type alignment sensor may be used.

Further, for example, the present invention is applicable not only to a step-and-scan type reduction projection exposure apparatus but also to an exposure apparatus such as a step-and-scan type exposure apparatus, a mirror projection type, a proximity type and a contact type. It is possible to apply. Further, not only an exposure apparatus used for manufacturing a semiconductor element and a liquid crystal display element, but also an exposure apparatus used for manufacturing a plasma display, a thin-film magnetic head, and an imaging element (such as a CCD)
The present invention can also be applied to an exposure apparatus that transfers a circuit pattern onto a glass substrate, a silicon wafer, or the like in order to manufacture a reticle or a mask. That is, the present invention is applicable irrespective of the exposure method and application of the exposure apparatus.

The exposure apparatus (FIG. 1) according to the above-described embodiment of the present invention can precisely control the position of the wafer W at high speed, and can perform exposure with high exposure accuracy while improving throughput. Excimer laser light source 1,
Beam shaping optical system 2 Energy rough adjuster 3, mirror 4, fly-eye lens 5, mask alignment system including reticle stage 11, laser interferometer 16, reticle stage drive unit 18, tilt stage 19, XY stage 20, laser Interferometer 22 and wafer stage driver 2
After the components shown in FIG. 1 such as the wafer alignment system including the optical system 3 and the projection optical system PL are electrically, mechanically or optically connected and assembled, comprehensive adjustment (electric adjustment, operation confirmation, etc.) It is manufactured by doing. It is desirable that the manufacture of the exposure apparatus be performed in a clean room in which the temperature, cleanliness, and the like are controlled.

Next, the manufacture of a device using the exposure apparatus and the exposure method according to one embodiment of the present invention will be described.
FIG. 11 is a flowchart of production of devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.) using the exposure apparatus according to one embodiment of the present invention. As shown in FIG.
First, in step S20 (design step), a function design of a device (for example, a circuit design of a semiconductor device) 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. Next, in step S24 (assembly step), step S23
Into chips using the wafer processed in the above. In this step S24, an assembly process (dicing,
Bonding), a packaging process (chip encapsulation), and the like. Finally, in step S25 (inspection step), inspections such as an operation confirmation test and a durability test of the device manufactured in step S25 are performed. After these steps, the device is completed and shipped.

The exposure apparatus of the present embodiment can be applied to a scanning exposure apparatus (US Pat. No. 5,473,410) for exposing a pattern of a mask by synchronously moving a mask and a substrate. Further, the exposure apparatus of the present embodiment can be applied to a proximity exposure apparatus that exposes a mask pattern by bringing a mask and a substrate into close contact without using a projection optical system. Further, the application of the exposure apparatus is not limited to an exposure apparatus for manufacturing a semiconductor. For example, an exposure apparatus for a liquid crystal that exposes a liquid crystal display element pattern to a square glass plate, or a thin film magnetic head is manufactured. Widely applicable to the exposure apparatus. The light source of the exposure apparatus of the present embodiment includes g-line (436 nm), i-line (365 nm), Kr
Not only an F excimer laser (248 nm), an ArF excimer laser (193 nm), and an F ₂ laser (157 nm) but also a charged particle beam such as an X-ray or an electron beam can be used. For example, when an electron beam is used, a thermionic emission type lanthanum hexaborite (LaB ₆ ) or tantalum (Ta) can be used as an electron gun.

The magnification of the projection optical system may be not only a reduction system but also any one of an equal magnification and an enlargement system. As the projection optical system,
When far ultraviolet rays such as an excimer laser are used, a material that transmits far ultraviolet rays such as quartz or fluorite is used as the glass material.
_{2 When} using a laser or X-ray, use a catadioptric or refracting optical system (use a reflective type mask). When using an electron beam, use an electron lens and deflector as the optical system. An electron optical system may be used. It goes without saying that the optical path through which the electron beam passes is in a vacuum state.

When a linear motor (see US Pat. No. 5,623,853 or US Pat. No. 5,528,118) is used for the wafer stage and the mask stage, either an air levitation type using an air bearing or a magnetic levitation type using Lorentz force or reactance force is used. May be used. The stage may be of a type that moves along a guide or a guideless type that does not have a guide. 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 is disclosed in JP-A-8-166475 (US Pat. Nos. 5,528,118).
As described in the above, a frame member may be used to mechanically escape to the floor (ground). The reaction force generated by the movement of the mask stage is mechanically released to the floor (ground) by using a frame member, as described in JP-A-8-330224 (US S / N 08 / 416,558). Is also good.

[0059]

As described above, according to the present invention, a special mask for removing the formed film is not required, and the opening placed on the shaping means and the mask stage can be formed. Is used to peel off the film. Therefore, since a dedicated mask is not required for removing the film, the cost required for manufacturing the mask can be reduced. In addition, since a dedicated mask for removing the film is not required, there is no need to replace the mask with a dedicated mask during a processing step, so that there is an effect that throughput can be improved. Further, since the metal film or the insulating film formed on the mark is peeled, it is possible to prevent the detection accuracy of the mark from being deteriorated due to noise caused by the metal film or the insulating film being formed on the mark. There is an effect that can be.

[Brief description of the drawings]

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

FIGS. 2A and 2B are diagrams for explaining a configuration of a reticle stage 11; FIG. 2A is a top view of the reticle stage 11;
(B) is a sectional view of the reticle stage.

3A and 3B are views for explaining a wafer W used in the present embodiment, and FIG. 3A is a top view of the wafer W;
(B) is a sectional view of the wafer W.

[Figure 4] is a diagram for explaining a relationship between the shape of the shape of the opening 37, 38 and the alignment mark AM _X and the alignment mark AM _Y, (a) is the shape of the shape of the opening 37 and the alignment mark AM _X shows the relationship, which is a diagram showing the relationship between (b) the shape of the opening 38 and the alignment mark AM _Y shape.

FIG. 5 is a top view of the reference mark 15 arranged on the tilt stage 19;

6 is a cross mark 35, 3 formed on the reference plate 32. FIG.
FIG. 9 is a diagram showing an example of observation results of No. 6 and marks 42 and 43 formed on the reference mark 15.

FIG. 7 is a flowchart illustrating an exposure method according to an embodiment of the present invention.

FIG. 8 is a perspective view illustrating a state in which the illumination light IL is shaped by an opening 37 formed in the reticle blind 9 and the reference plate 32.

FIG. 9 is a diagram for explaining a process used in element isolation.

FIG. 10 is a diagram for explaining a method of exposing the entire alignment mark when the size of an opening 37 is set small.

FIG. 11 is a flowchart when a device is manufactured using the exposure apparatus according to the embodiment of the present invention.

FIG. 12 is a cross-sectional view showing an alignment mark having a metal film formed on the surface.

FIG. 13 is a diagram illustrating an example of a measured waveform when an alignment mark having a metal film formed on a surface is measured.

FIG. 14 is a diagram illustrating a conventional method for reducing a measurement error caused by a grain.

[Explanation of symbols]

Reference Signs List 1 excimer laser light source (illumination light source) 9 reticle blind (shaping means) 11 reticle stage (mask stage) 32 reference plate (reference member) 37 opening (opening) 38 opening (opening) 40 metal film (film) R reticle ( mask) W wafer (substrate) IL illumination light AM, AM _X, AM _Y alignment mark (mark)

Claims (7)

[Claims] 1. An exposure apparatus that irradiates an illumination light generated from an illumination light source onto a mask and transfers an image of a pattern formed on the mask onto a substrate, wherein the exposure apparatus includes a mask stage that holds the mask. An opening having a shape corresponding to the alignment mark of the substrate, provided between the illumination light source and the mask stage,
An exposure apparatus comprising: a shaping unit configured to shape illumination light illuminated toward the mask stage into a desired shape. 2. The illumination device according to claim 1, wherein the shaping unit shapes the illumination light into a shape corresponding to the opening.
Exposure apparatus according to the above. 3. The apparatus according to claim 1, wherein the opening is provided on a reference member provided on the mask stage for use in positioning the mask. Exposure equipment. 4. A metal film or an insulating film is formed on the mark, and the metal film or the insulating film on the mark is peeled off by the illumination light through the shaping means and the opening. The exposure apparatus according to claim 1, wherein the exposure apparatus includes: 5. An exposure method for irradiating an illumination light onto a mask disposed on a mask stage and transferring an image of a pattern formed on the mask onto a substrate on which a predetermined film is fixed. And shaping the illumination light irradiated toward the mask stage into a shape of an opening provided on the mask stage and having a shape corresponding to a mark formed on the substrate, and detecting the mark. Exposing the predetermined film by irradiating the mark with the shaped and illuminating light through the opening before the predetermined film is formed. 6. The exposure method according to claim 5, wherein the opening is provided on a reference member provided on the mask stage for use in positioning the mask. 7. The exposure method according to claim 5, wherein the predetermined film includes a metal film or an insulating film.