JP2010010229A - Aligner and method of manufacturing device - Google Patents

Abstract

【Task】
Provided is an immersion exposure apparatus for detecting a watermark attached to a light receiving means mounted on a substrate stage.
[Solution]
An illumination optical system that illuminates an original on which a circuit pattern is formed by exposure light emitted from a light source, a projection optical system that projects the circuit pattern of the original onto a substrate, and a substrate stage that holds the substrate And an exposure apparatus that exposes the substrate through the projection optical system and an immersion medium, and a light receiving unit that is mounted on the substrate stage and receives exposure light, and the substrate below the projection optical system. Measuring means for measuring a position, and measuring the position of the light receiving surface of the light receiving means in contact with the immersion medium by the measuring means to detect an adhering matter adhering to the light receiving means. And
[Selection] Figure 1

Description

  The present invention relates to an exposure apparatus for projecting and exposing an original pattern onto a substrate through an immersion medium filled in a gap between the final optical element disposed closest to the substrate of the projection optical system and the substrate. .

Semiconductor devices such as ICs and LSIs, liquid crystal devices, imaging devices such as CCDs, and devices such as magnetic heads are manufactured using photolithography technology.
At that time, a circuit pattern of a reticle (mask) which is an original plate is projected directly or at a predetermined ratio, and a semiconductor wafer which is a substrate coated with a photosensitive material is exposed.
Conventionally, since the space between the projection optical system and the wafer is configured in the air, nitrogen, or the like, a device is manufactured using a projection exposure apparatus that performs exposure under a numerical aperture NA <1.0.
In general, the photosensitive material applied to the wafer has an appropriate exposure amount, so an optical member such as a half mirror is arranged in the illumination optical system of the projection exposure apparatus, and the optical member is branched. The amount of exposure light is monitored by a second light receiving means comprising an optical sensor or the like.
Based on the measurement value of the second light receiving means, exposure amount control is performed in order to perform exposure with the appropriate exposure amount.
Since the transmittances of the illumination optical system and the projection optical system change minutely, it is necessary to guarantee the second light receiving means on the basis of the illuminance on the wafer surface.
For this reason, the first light receiving means comprising an optical sensor or the like mounted on the wafer stage, which is a substrate stage, is used to transmit exposure light transmitted through an optical system such as an illumination optical system and a projection optical system for various exposure conditions. The variation is measured on the wafer surface.
As a result, the obtained fluctuation is fed back to the second light receiving means.
In addition to the function of measuring the fluctuation of the exposure light, the first light receiving means functions to align the wafer stage by detecting the exposure light transmitted through an optical system such as an illumination optical system and a projection optical system. Also, it has a function of measuring the optical characteristics of the projection optical system.
In recent years, with the miniaturization of semiconductor devices, excimer lasers that emit light in the far ultraviolet region have been used as light sources for projection exposure apparatuses.
However, in the conventional example of Japanese Patent Laid-Open No. 2000-150334 (Patent Document 1), when an excimer laser is used as the exposure light, the optical characteristics of the glass material and coating film of the optical component and the light reception of the detection system such as an optical sensor. It was found that the sensitivity changed gradually.
Furthermore, an immersion exposure apparatus (numerical aperture NA ≧ 1.0) that fills the space between the projection optical system and the wafer with an immersion medium having a refractive index n ≧ 1.0 has begun to be used.
JP 2000-150334 A

The first light receiving means of the immersion exposure apparatus measures in a state where it is in contact with the immersion medium when measuring through the immersion medium, and waits in a state where it is not in contact with the immersion medium during non-measurement. The light receiving means has a longer standby time during non-measurement than use during measurement.
Therefore, when the immersion medium is insufficiently collected after measurement in contact with the immersion medium, or when the immersion medium is scattered from the outside during standby, the first light receiving means is attached. A watermark may adhere.
The cause of the change in the measurement value when the exposure light is detected by the first light receiving means is a change due to the transmittance of an optical member such as an illumination optical system or projection optical system of the exposure apparatus, and the sensitivity of the light receiving element of the first light receiving means. There are changes due to fluctuations and changes due to the influence of watermarks.
For this reason, when the measurement value when the exposure light is detected by the first light receiving means changes, it is necessary to detect a change due to the influence of the watermark.
Therefore, an object of the present invention is to provide an immersion exposure apparatus that detects a watermark attached to a light receiving means mounted on a substrate stage.

An exposure apparatus of the present invention for solving the above-described problems includes an illumination optical system that illuminates an original plate on which a circuit pattern is formed by exposure light emitted from a light source, and a projection that projects the circuit pattern of the original plate onto a substrate. An exposure apparatus that includes an optical system and a substrate stage that holds the substrate, and that exposes the substrate via the projection optical system and an immersion medium, and is mounted on the substrate stage to receive exposure light A light receiving means, and a measuring means for measuring the position of the substrate below the projection optical system, and the measuring means measures the position of the light receiving surface of the light receiving means in contact with the immersion medium, The adhering matter adhering to the light receiving means is detected.
Furthermore, the exposure apparatus of the present invention includes an illumination optical system that illuminates an original plate on which a circuit pattern is formed by exposure light emitted from a light source, a projection optical system that projects the circuit pattern of the original plate on a substrate, and An exposure apparatus that exposes the substrate via the projection optical system and an immersion medium, and is mounted on the substrate stage, regardless of the presence or absence of the immersion medium. The apparatus has a light receiving means for receiving exposure light on the substrate, and detects adhered matter adhering to the light receiving means by measurement of the light receiving means.

  According to the present invention, the watermark attached to the light receiving means mounted on the substrate stage is detected.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
A scanning type liquid immersion exposure apparatus according to a first embodiment of the present invention will be described with reference to the schematic configuration diagram of FIG. 1, but the exposure apparatus may not be a scanning type.
The immersion exposure apparatus according to the first embodiment is an exposure apparatus used when manufacturing a semiconductor device such as an IC or LSI, a liquid crystal device, an imaging device such as a CCD, or a device such as a magnetic head.
The illumination optical system 2 is an optical system that illuminates the original reticle 3 with a beam 1a that is exposure light emitted from a light source 1 composed of an excimer laser or the like.
Next, the beam 2a shaped by the illumination optical system 2 is irradiated onto the reticle 3, which is an original plate held by the reticle stage 4, and a circuit pattern necessary for manufacturing a device is formed on the reticle 3. Yes.
The projection optical system 5 is an optical system that projects the circuit pattern of the reticle 3 onto a wafer 7 that is a substrate. The beam 3a that has passed through the reticle 3 is transmitted through the projection optical system 5 and onto a wafer stage 8 that is a substrate stage. The image is reduced and projected onto the wafer 7 that is attracted and held.
Since the first embodiment is an immersion exposure apparatus that exposes the wafer 7 through the projection optical system 5 and the immersion medium 6, a liquid having a refractive index n of 1 or more is provided between the projection optical system 5 and the wafer 7. Filled with the immersion medium 6, the resolving power is improved to 1 / n times, and the focal depth is improved to n times.
Reticle stage 4 and wafer stage 8 are controlled in scanning direction and scanning speed by controller 12.

The first light receiving means 13, which is a light receiving means composed of an optical sensor or the like, is mounted in the wafer stage 8, which is a plate stage, so as to be substantially the same height as the wafer 7, regardless of the presence or absence of the immersion medium 6. It is means for receiving exposure light corresponding to the surface of the wafer 7 on the substrate and detecting the light quantity and the light quantity distribution.
The first light receiving means 13 can measure regardless of the presence or absence of the immersion medium 6, that is, regardless of the numerical aperture NA, aligns the wafer stage 8, and measures the optical characteristics of the projection optical system 5. Also used for.
The second light receiving means 9 is a photodetector for constantly monitoring the amount of light exposed to the wafer 7. In the illumination optical system 2, a part of the beam 1a is divided by a half mirror 19 or the like, and the beam 1a is monitored.
The second light receiving means 9 is also in a conjugate relationship with the exposure surface of the wafer 7 and the first light receiving means 13, and the light quantity measured by the second light receiving means 9 using the light quantity calculation section 11 and the light source control section 10 is It is fed back and controlled as the light emission intensity of the light source 1.
Data stored in the light amount calculation unit 11 is displayed on the display unit 11a.
Here, the light receiving sensitivity of the second light receiving means 9 including an optical sensor or the like is calibrated using the first light receiving means 13 whose light receiving sensitivity is calibrated in the wafer stage 8. Since the transmittances of the illumination optical system 2 and the projection optical system 5 change minutely, this light reception sensitivity calibration ensures the light reception sensitivity of the second light receiving means 9 used during exposure with the illuminance on the wafer 7 as a reference. There is a need to.
The first measuring means 14, the second measuring means 15, and the third measuring means are measuring means, and the first measuring means 14, the second measuring means 15, the light source 16 that is the third measuring means, and the detector 17 are projected. A means for measuring the wafer 7 below the optical system 5. By this measurement, the wafer 7 is adjusted in position and aligned with high accuracy.
The first measuring means 14 is means for measuring a dedicated mark on the wafer 7 via the projection optical system 5 as shown in FIG.
The second measuring unit 15 is a unit that measures a dedicated mark on the wafer 7 without using a projection optical system.
The third measuring means comprises a light source 16 and a detector 17, and detects the diffracted light from the wafer 7 using the reflected light from the wafer 7 at the time of oblique incidence. The alignment of the wafer 7 is performed by this detection. Is called.

Next, an exposure method according to an embodiment of the present invention using the immersion exposure apparatus according to the first embodiment will be described with reference to FIG.
A first measurement unit 14 that measures a dedicated mark on the wafer 7 through the projection optical system 5 and aligns the wafer 7 is used as a watermark measurement unit.
First, in the first step, before the wafer 7 is exposed through the immersion medium 6 and before the output of the first light receiving means 13 is measured, the first process contacts the immersion medium 6 of the first light receiving means 13. This is a step of measuring the light receiving surface 13a.
That is, before exposing the first wafer 7 and before measuring the amount of exposure light that is the output of the first light receiving means 13, the first measuring means 14 is set in the absence of the immersion medium 6. The light receiving surface 13a is measured and an image (image 1) is taken and stored.
Thereafter, in the second step, an image of the light receiving surface 13a in contact with the immersion medium 6 of the first light receiving means 13 is taken using the first, second and third measuring means 14, 15, 16, and 17.
That is, the immersion medium 6 is injected, the exposure light quantity (light quantity 1) is measured by the first light receiving means 13 through the immersion medium 6, and the wafer 7 is exposed.
After the exposure to the wafer 7 is completed, the immersion medium 6 is removed and the wafer 7 is replaced.
In order to expose the next wafer 7, the immersion medium 6 is injected again, the amount of exposure light (light amount 2) is measured by the first light receiving means 13, and the wafer 7 is exposed.
When the immersion medium 6 is injected, when the wafer 7 is exposed via the immersion medium 6, or when the immersion medium 6 is removed, the watermark is attached.
Due to the attachment of the watermark, a difference occurs when measuring the amount of exposure light in the first light receiving means 13.
When the measurement value of the light amount of the exposure light is changed by the first light receiving unit 13 through the immersion medium 6, that is, when the light amount 1 and the light amount 2 are different, the immersion medium 6 is removed and the first light receiving unit 13 An image (image 2) of the light receiving surface 13a in contact with the immersion medium 6 is acquired.
Here, in the third step, the information obtained in the first step and the second step is compared, and the adhesion of the deposit is detected when the information obtained in the first step and the second step is different.
That is, the image 1 and the image 2 are compared, the watermark is detected, and when the watermark is detected, it is necessary to perform cleaning by the cleaning device 30.
When the watermark is not detected, the transmittance of the optical component such as the lens of the illumination optical system 2 or the projection optical system 5 has changed.

As shown in FIG. 3, the second measuring unit 15 that acquires the image of the light receiving surface 13 a that contacts the immersion medium 6 of the first light receiving unit 13 without using the projection optical system 5 is also the first measuring unit 14. Similarly, the watermark can be detected.
The detection of the watermark using the first measuring unit 14 and the second measuring unit 15 may be performed when the throughput of the exposure apparatus is not affected, or when it is periodically performed. .

Next, referring to the flowchart of FIG. 4, when the measurement value of the first light receiving means 13 changes, a watermark detection and maintenance determination method using the first measurement means 14 or the second measurement means 15. An embodiment for determining the determination time will be described.
Before the exposure of the wafer 7 through the immersion medium 6 and before the measurement by the first light receiving means 13, the first and second measurement means 14 and 15 are used without the immersion medium 6. Then, an image (image 1) of the light receiving surface 13a in contact with the immersion medium 6 of the first light receiving means 13 is acquired.
Next, the acquired image 1 is stored in the controller 12 (S101).
The immersion medium 6 is injected (S102), and the amount of exposure light is measured by the first light receiving means 13 (S103).
Next, after the wafer 7 is exposed (S104), the immersion medium is removed (S105), and the wafer 7 is replaced (S106).
After exchanging the wafer 7, the immersion medium 6 is injected (S107), and the amount of exposure light is measured by the first light receiving means 13 (S108).
At this time, if a watermark is attached in one of the steps S102, S104, and S105, the measurement value changes during the light amount measurement in S108 (S109).
Here, when the light quantity measurement value at the first light receiving means 13 does not change, the first light receiving means 13 can be used continuously (S117).

When the light quantity measurement value changes in S109, the immersion medium 6 is removed, and an image (image 2) of the light receiving surface 13a in contact with the immersion medium 6 of the first light receiving means 13 is acquired (S110).
Next, image 1 and image 2 are compared (S111).
When the image 1 and the image 2 are equal, the first light receiving means 13 can be used continuously (S117).
However, since the image 1 and the image 2 are different when the watermark is attached, the first light receiving means 13 is cleaned by the cleaning device 30 such as ultrasonic cleaning shown in FIG. 1 (S112).
The image 2 ′ of the light receiving surface 13a that contacts the immersion medium 6 of the first light receiving means 13 is acquired again after cleaning by the cleaning device 30 (S113).
The image 1 and the image 2 ′ are compared (S114).
When the image 1 and the image 2 ′ are equal, the first light receiving means 13 can be used continuously (S117).
However, when the image 1 and the image 2 ′ are different, the first light receiving means 13 is replaced (S115).
After the replacement of the first light receiving means 13, the first measuring means 14 or the second alignment light receiving means 15 acquires an image (image 1 ′) of the light receiving surface 13a in contact with the immersion medium 6 of the first light receiving means 13.
This image 1 ′ is acquired before the wafer 7 is exposed through the immersion medium 6 and before the measurement by the first light receiving means 13.
The image 1 ′ is stored in the controller 12 instead of the image 1 (S116).
The image acquisition process of S101 and S110 has been described as after the immersion medium 6 has been removed. However, when the first alignment light receiving unit 14 is used, the immersion medium 6 may be injected.
As described above, according to the first embodiment, the first light receiving unit 13 can measure an accurate exposure amount on the surface of the wafer 7, and the first light receiving unit 13 mounted on the wafer stage 8 can be measured. Detect the adhering watermark.
Further, the exposure can be performed without unnecessarily calibrating the light receiving sensitivity of the first light receiving means 13.

Next, Embodiment 2 of the present invention will be described with reference to FIG.
The overall schematic configuration diagram of the exposure apparatus according to the second embodiment is the same as that of the first embodiment, and is omitted.
The watermark is detected using third measuring means 16 and 17 that measure the mark on the wafer 7 mounted in the exposure apparatus. The wafer 7 is aligned by this measurement.
One of the third measuring means 16 and 17 is composed of a light source such as an LED, and one of them is an imaging element or a light receiving element.
An optical system for a light source (not shown), an imaging element, an optical system for a light receiving element, a dedicated mask, and the like are configured.
Using the third measuring means 16 and 17, the light is incident on the first light receiving means 13 at an oblique incidence.
The obliquely incident light is reflected by the light receiving surface 13a in contact with the immersion medium 6 of the first light receiving means 13, and the reflected light is received by the imaging elements and light receiving elements of the third measuring means 16 and 17.
Before the first wafer 7 is exposed and before the amount of exposure light is measured by the first light receiving means 13, the third measuring means 16 and 17 are used in the absence of the immersion medium 6. An image (image 1) of the light receiving surface 13a that contacts the immersion medium 6 of the one light receiving means 13 is acquired and stored.
Thereafter, the immersion medium 6 is injected, and the amount of exposure light (light quantity 1) is measured by the first light receiving means 13 through the immersion medium 6 to expose the wafer 7.
After the exposure to the wafer 7 is completed, the immersion medium 6 is removed and the wafer 7 is replaced. In order to expose the next wafer 7, the immersion medium 6 is injected again, the amount of exposure light (light amount 2) is measured by the first light receiving means 13, and the wafer 7 is exposed.

There is a high possibility that the watermark will adhere when the immersion medium 6 is injected, when the wafer 7 is exposed through the immersion medium 6, or when the immersion medium is removed.
Due to the attachment of the watermark, a difference may occur when measuring the amount of exposure light by the first light receiving means 13.
Therefore, when the measurement value of the light amount of the exposure light is changed by the first light receiving means 13 via the immersion medium 6, that is, when the light quantity 1 and the light quantity 2 are different, the immersion medium 6 is removed, and the first light receiving means. An image (image 2) of the light receiving surface 13a in contact with the 13 immersion medium 6 is acquired.
The two images 1 and 2 are compared, and a watermark is detected.
If a watermark is detected, it is necessary to perform cleaning with an ultrasonic cleaner 30.
When the watermark is not detected, the transmittance of the optical component such as the lens of the illumination optical system 2 or the projection optical system 5 has changed.
The detection of the watermark using the third measuring means 16 and 17 may be performed at a timing that does not affect the throughput, such as during maintenance of the apparatus, or periodically.
An example of a flowchart for determining the watermark detection, maintenance determination method, and determination timing using the third measuring means 16 and 17 is the same as the flowchart shown in FIG.

Next, Embodiment 3 of the present invention will be described with reference to FIG.
The overall schematic configuration of the exposure apparatus is the same as that in the first embodiment, and will not be described.
The watermark is detected by a method other than the first embodiment using the first measuring unit 14 that measures the mark on the wafer 7 mounted in the exposure apparatus and aligns the wafer 7.
FIG. 6 shows the configuration of the first alignment means 14 in detail.
Light reflected from the first light receiving means 13 is measured by the light receiving element 23 through the optical system 21 for fiber, the half mirror 20 and the mirror 18.
At this time, the first light receiving means 13 is formed in order to detect the presence or absence of a watermark using, for example, reflected light from a pinhole or a lattice pattern formed on the light receiving surface 13a of the first light receiving means 13. By irradiating light perpendicularly to the pattern, only regular reflection light (0th order light) from the pattern is detected.
By measuring the specularly reflected light (0th order light), it is possible to measure the image of the light receiving surface 13a that contacts the immersion medium 6 on the first light receiving means 13.
Further, light is incident on the first light receiving means from an oblique direction, and only the scattered light or diffracted light (n-order light) from the edge portion is detected by using the half mirror 20 among the reflected light from the pattern. An image of the light receiving surface 13a that is in contact with the immersion medium 6 on the means 13 is measured.

Before the exposure of the first wafer 7 with this exposure apparatus and before the measurement of the amount of exposure light with the first light receiving means 13, the first measuring means 14 is used in the absence of the immersion medium 6. An image (image 1) of the light receiving surface 13a that contacts the immersion medium 6 of the one light receiving means 13 is acquired and stored.
Thereafter, the immersion medium 6 is injected, and the amount of exposure light (light quantity 1) is measured by the first light receiving means 13 through the immersion medium 6 to expose the wafer 7. After the exposure to the wafer 7 is completed, the immersion medium 6 is removed and the wafer 7 is replaced.
In order to expose the next wafer 7, the immersion medium 6 is injected again, the amount of exposure light (light amount 2) is measured by the first light receiving means 13, and the wafer 7 is exposed.
There is a high possibility that the watermark will adhere when the immersion medium 6 is injected, when the wafer 7 is exposed through the immersion medium 6, or when the immersion medium is removed.
Due to the attachment of the watermark, a difference may occur when measuring the amount of exposure light by the first light receiving means 13.
Therefore, when the measurement value of the light amount of the exposure light is changed by the first light receiving means 13 via the immersion medium 6, that is, when the light quantity 1 and the light quantity 2 are different, the immersion medium 6 is removed, and the first light receiving means. An image (image 2) of the light receiving surface 13a in contact with the 13 immersion medium 6 is acquired.
The two images 1 and 2 are compared to detect a watermark.
If a watermark is detected, it is necessary to perform cleaning or the like with a cleaning device 30 such as an ultrasonic wave.
When the watermark is not detected, the transmittance of the optical component such as the lens of the illumination optical system 2 or the projection optical system 5 has changed.
As in the first embodiment, the detection of the watermark using the first measuring unit 14 may be performed at a timing that does not affect the throughput, such as during maintenance of the apparatus, or periodically.
An example of a flowchart for determining the watermark detection, the maintenance determination method, and the determination timing using the first measuring unit 14 is the same as the flowchart shown in FIG.

Next, Embodiment 4 of the present invention will be described with reference to FIG.
Since the entire schematic view of the exposure apparatus is the same as that of the first embodiment, a description thereof will be omitted.
The watermark is detected using the measured value when the exposure light of the first light receiving means 13 mounted on the wafer stage 8 is detected.
In FIG. 7, exposure light is incident on the second light receiving unit 9 using the half mirror 19 in the illumination optical system 2 and the first light receiving unit 13 via the projection optical system 5.
A detection method when the watermark is attached will be described below.
If exposure light is detected by the first light receiving means 13 when the watermark is attached, the measured value is considered to change.
Therefore, in order to detect the watermark, the watermark is detected by using a threshold (α) of the change amount of the measurement value.
Described below is the derivation of the threshold value α.
Experimentally, the amount of change in optical and physical information such as the transmittance of optical members such as the illumination optical system 2 and the projection optical system 5 with respect to the number of exposure pulses, exposure energy, exposure light distribution, etc. is A, the first light receiving means. The amount of change in the light receiving sensitivity of 13 is B.
Further, the conditions such as the number of exposure pulses A, the exposure energy and the exposure light distribution when the change amount A and the change amount B are derived do not necessarily match the exposure conditions used on the immersion type exposure apparatus.
Therefore, since it is necessary to correct the exposure conditions when the change amount A and the change amount B are obtained to the exposure conditions at the time of wafer 7 exposure, the conversion coefficient C is used. The conversion coefficient C may be measured and derived on the exposure apparatus.
Or you may theoretically derive from design values, such as illumination optical system 2 and projection optical system 5.
Using the change amount A, the change amount B, and the conversion coefficient C, the estimated value β of the measurement value change of the first light receiving means 13 mounted on the wafer stage 8 is derived as follows.
Here, since the conversion coefficient C varies depending on the exposure condition, the setting is changed according to the exposure condition when the watermark is detected.
β = A × B × C
The derived estimated value β is stored in the light amount calculation unit 11 and displayed on the display unit 11.

Next, the first light receiving means 13 and the second light receiving means 9 are used in the absence of the immersion medium 6 before the exposure of the wafer 7 with this exposure apparatus or before the exposure light is detected with the first light receiving means 13. To detect the exposure light.
At this time, the measurement value at the first light receiving means 13 is D, and the measurement value at the second light receiving means 9 is E. Using the estimated value β, the measured value D, and the measured value E, the threshold value α is obtained as follows.
Here, since the measurement value D and the measurement value E differ depending on the exposure condition, the setting of the conversion coefficient C is changed according to the exposure condition at the time of detecting the watermark.
α = (D / E) × β
Here, the reason for normalizing the measured value E by the second light receiving means 9 is to correct the variation in exposure energy of the light source 1 itself.
When the detection value of the exposure light at the first light receiving means 13 changes, the watermark is detected by comparing with the threshold value α.
Here, when the measured value changes, the measured value at the first light receiving means 13 is D ′, and the measured value at the second light receiving means 9 is E ′.
The measurement values D ′ and E ′ are measured under the same exposure conditions as when the measurement values D and E are measured.
If the exposure conditions are different, the setting of the conversion coefficient C is changed, and a new α is set as a threshold value.
(D ′ / E ′) ≦ α
If D ′ / E ′ is a measured value smaller than the threshold value α as shown in the above equation, it is determined that no watermark is attached.
(D '/ E')> α
Further, as shown in the above formula, if D ′ / E ′ has a measured value larger than the threshold value α, it is determined that the watermark is attached.
The detection of the watermark using the first light receiving means 13 may be performed at a timing that does not affect the throughput, such as during maintenance of the apparatus, or periodically.

FIG. 8 will be described with reference to an example of a flowchart for determining a watermark detection method, a maintenance determination method, and a determination timing using a measurement value of the first light receiving unit 13.
Before the exposure of the wafer 7 through the immersion medium 6 by the exposure apparatus and before the measurement by the first light receiving means 13, the first light receiving means 13 and the second light receiving means without the immersion medium 6 are used. The output is measured (S201).
A change amount of the transmittance of the optical member such as the illumination optical system 2 and the projection optical system 5 stored in the light amount calculation unit 11 and displayed on the display unit 11a is A, and a change amount of the light receiving sensitivity of the first light receiving unit 13 B and an estimated value β of the measured value change is derived using the conversion coefficient C in order to match the exposure conditions.
Further, the threshold value α of the change in the measured value of the first light receiving means 13 is derived from the measured value in S201 (S202).
The immersion medium 6 is injected (S203), and the amount of exposure light is measured by the first light receiving means 13 (S204).
Next, after the exposure of the wafer 7 (S205), the immersion medium is removed (S206), and the wafer 7 is replaced (S207).
After exchanging the wafer 7, the immersion medium 6 is injected (S208), and the amount of exposure light is measured by the first light receiving means 13 (S209).
At this time, the watermark may be attached in any one of steps S203, S205, and S206.
If the watermark is attached, the measurement value changes during the light quantity measurement in S209.

When the measured value of the first light receiving means 13 changes, it is compared with the previously derived threshold value α (S210).
At this time, if the change is smaller than the threshold value α, it is determined that the first light receiving means 13 can be used continuously (S217).
When the change is larger than the threshold value α, the first light receiving means 13 is cleaned by the cleaning device 30 such as ultrasonic cleaning (S211).
After cleaning by the cleaning device 30, the exposure light is again measured by the first light receiving means 13 (S212), and the measured value is again compared with the threshold value α (S213).
At this time, if the change is smaller than the threshold value α, the first light receiving means 13 can be continuously used (S217).
If the change is greater than the threshold value α, the first light receiving means 13 is replaced (S214). After the replacement, the exposure light is detected by the first light receiving means 13 (S215).
A change in the measured value of the first light receiving means 13 from the estimated value β of the measured value change when the exposure light is detected by the first light receiving means 13 stored in the light amount calculating section 11 and displayed on the display section 11a and the measured value of S215. The threshold value α is derived again (S216).

(Example of device manufacturing method)
A device (semiconductor integrated circuit element, liquid crystal display element, etc.) includes a step of exposing a substrate (wafer, glass plate, etc.) coated with a photosensitive agent using the exposure apparatus of any one of the embodiments described above, and the substrate The film is formed and manufactured through a process of developing the film and other known processes. Other well known processes include etching, resist stripping, dicing, bonding, packaging, and the like.

1 is an overall schematic block diagram of an exposure apparatus according to Embodiment 1 of the present invention. It is explanatory drawing of the detection method of the watermark of the 1st measurement means in Example 1 of this invention. It is explanatory drawing of the detection method of the watermark of the 2nd measurement means in Example 1 of this invention. 5 is a flowchart of watermark detection, maintenance determination method, and determination timing using the first, second, third, and fourth measuring means in the first, second, and third embodiments of the present invention. It is explanatory drawing of the detection method of the watermark of the 3rd measurement means in Example 2 of this invention. It is explanatory drawing of the detection method of the watermark of the 1st measurement means in Example 3 of this invention. It is explanatory drawing of the detection method of the watermark of the 1st light-receiving means 13 in Example 4 of this invention. It is a flowchart of the detection method of a watermark, the judgment method of a maintenance, and a judgment time using the measured value of the 1st light-receiving means 13 in Example 1 of this invention.

Explanation of symbols

1: light source, 2: illumination optical system, 3: reticle, 4: reticle stage, 5: projection optical system, 6: immersion medium, 7: wafer, 8: wafer stage, 9: second light receiving means, 10: light source Control unit, 11: light amount calculation unit, 12: controller, 13: first light receiving unit, 14: first measurement unit, 15: second measurement unit, 16, 17: third measurement unit, 18: mirror, 19, 20 : Half mirror, 21: optical system for fiber, 22: fiber, 23: light receiving element

Claims (16)

An illumination optical system that illuminates an original on which a circuit pattern is formed by exposure light emitted from a light source;
A projection optical system that projects the circuit pattern of the original onto a substrate;
An exposure apparatus that exposes the substrate through the projection optical system and an immersion medium, and a substrate stage that holds the substrate.
A light receiving means mounted on the substrate stage for receiving exposure light;
Measuring means for measuring the position of the substrate below the projection optical system,
An exposure apparatus characterized in that the measuring means measures the position of the light receiving surface of the light receiving means in contact with the immersion medium and detects adhering matter adhering to the light receiving means.   The measurement means performs measurement via the projection optical system, measurement not via the projection optical system, detection of reflected light when obliquely incident on the substrate, or detection of diffracted light from the substrate. The exposure apparatus according to claim 1, characterized in that: An exposure method using the exposure apparatus according to claim 1, wherein
A first step of measuring the position of the light receiving surface of the light receiving means that contacts the immersion medium before exposing the substrate through the immersion medium and before measuring the output of the light receiving means. When,
A second step of taking an image of the light receiving surface that contacts the immersion medium of the light receiving means using the measuring means;
A third step of comparing the information obtained in the first step and the second step,
An exposure method comprising: detecting adhesion of a deposit when the information obtained in the first step and the second step is different.   In the third step, information on the light receiving surface that contacts the immersion medium of the light receiving means derived in the first step is stored, and the information obtained in the first step and the second step is compared. The exposure method according to claim 3, which is sometimes used.   The said 3rd process WHEREIN: When the information of the said light-receiving surface which contacts the said immersion medium of the said light-receiving means differs, the said light-receiving surface which contacts the said immersion medium of the said light-receiving means is cleaned. 5. The exposure method according to 3 or 4.   6. The light receiving means is replaced when the light receiving surface of the light receiving means contacting the immersion medium differs from the information measured in the first step after the cleaning. The exposure method as described.   7. The exposure method according to claim 6, wherein after the light receiving means is replaced, the first step is performed to re-derived information on the light receiving surface in contact with the immersion medium of the light receiving means. An illumination optical system that illuminates an original on which a circuit pattern is formed by exposure light emitted from a light source;
A projection optical system that projects the circuit pattern of the original onto a substrate;
An exposure apparatus that exposes the substrate through the projection optical system and an immersion medium, and a substrate stage that holds the substrate.
A light receiving means mounted on the substrate stage for receiving exposure light on the substrate regardless of the presence or absence of the immersion medium;
An exposure apparatus for detecting a deposit adhered to the light receiving means by measurement of the light receiving means. An exposure method using the exposure apparatus according to claim 8,
A first step of measuring by the light receiving means in the absence of the immersion medium before exposing the substrate through the immersion medium and before measuring the output of the light receiving means;
A second step of deriving a threshold value of the measured value change of the light receiving means using the estimated value of the measured value change of the light receiving means derived experimentally and the measured value in the first step;
A third step of comparing the threshold value of the measurement value change derived in the second step with the measurement value of the light receiving means,
An exposure method characterized by detecting adhesion of an adhering substance when a change larger than the threshold value of the measurement value change of the light receiving means occurs.   In the second step, the measured value of the light receiving means is calculated from the experimentally derived change amount of the light receiving means and the change amounts of optical and physical information of the illumination optical system and the projection optical system. The exposure method according to claim 9, wherein an estimated value of change is derived.   10. The method according to claim 9, wherein in the second step, an estimated value of the measured value change of the light receiving unit derived experimentally is stored and used when the threshold value of the measured value change of the light receiving unit is derived. The exposure method as described.   In the third step, the threshold value of the measured value change of the light receiving means derived in the second step is stored, and the threshold value of the measured value change derived in the second step is compared with the measured value of the light receiving means. The exposure method according to claim 9, wherein the exposure method is used when performing.   The said 3rd process WHEREIN: When the measured value change of the said light-receiving means is larger than the said threshold value, the said light-receiving surface which contacts the said immersion medium of the said light-receiving means is cleaned. An exposure method according to any one of the above.   After cleaning the light receiving surface of the light receiving means contacting the immersion medium, the measured value change of the light receiving means is compared with the threshold, and if the change is larger than the threshold, the light receiving means is replaced. The exposure method according to claim 13, characterized in that:   After exchanging the light receiving means, the threshold of the change in the measured value of the light receiving means is derived again based on the measured value of the light receiving means without the immersion medium and the estimated value change of the measured value of the light receiving means. The exposure method according to claim 14, wherein: A step of exposing the substrate using the exposure apparatus according to claim 1,
Developing the substrate;
Forming a device using the developed substrate. A device manufacturing method comprising:

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