JPH08279460A - Aligner - Google Patents

Abstract

PURPOSE: To enable removal of foreign mater and to carry out exposure with a high yield by returning a substrate having a foreign matter attachment preventing film to a magazine when the foreign matter exists. CONSTITUTION: After cleaning, in a state without foreign matter, a substrate 39 equipped with a foreign matter attachment preventing film 23 via a frame 24 is received in a magazine 6 as it remains in a cassette. Inspection of foreign matter on the foreign matter attachment preventing film 23 mounted on an image surface of the substrate 39 is carried out by an upper side foreign matter inspection apparatus 1 and a lower side foreign matter inspection apparatus 2 provided above and under the transporting arm 3. If foreign matter exists on the foreign matter attachment preventing film 23, that substrate is returned into the original cassette, and the foreign matter is removed. On the other hand, if foreign matter does not exist, the transporting arm 3 is rotated by a rotary machine 8 in the direction of an arrow 7a and placed at the exposure position 9, and the transfer onto the wafer 11 is effected via an exposure optical system 10 for one chip at a time. When this exposure process using the substrate is completed, the substrate 39 is received in the cassette within the magazine again. Thus, the substrate to be exposed can be exposed with a high yield.

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention uses a reduction projection exposure apparatus or a 1: 1 reflection type projection exposure apparatus to prevent a decrease in yield due to adhesion of foreign matter. The present invention relates to an exposure apparatus that exposes a circuit pattern formed on a substrate on which a frame having a foreign matter adhesion prevention film is attached, onto a substrate to be exposed. 2. Description of the Related Art For example, in a reduction projection exposure apparatus (hereinafter abbreviated as RA), a circuit pattern formed on a substrate such as a reticle or a photomask is reduced, transferred onto a wafer, and exposed one by one. When foreign matter is present on the substrate, the foreign matter image is transferred, and all the chips on the wafer are defective. Therefore, the inspection of foreign matter on the substrate before exposure is indispensable for improving the yield of the exposure process. Examples of related devices of this type include JP-A-57-80546, JP-A-58-79240, and JP-A-59-82727. In a mass production line that requires RA for these devices, huge cost is required in terms of investment. On the other hand, recently, a pellicle for preventing foreign matter from adhering (a transparent thin film of nitrocellulose attached to a metal frame) so that the foreign matter does not directly adhere to the surface of the substrate. I am wearing. After attaching the foreign matter adhesion prevention film to the substrate, in principle, new foreign matter can be prevented from adhering to the substrate. Further, since the foreign matter adhesion prevention film is separated from the surface of the substrate, the foreign matter image is not transferred onto the wafer even if a relatively small foreign matter is present on the foreign matter adhesion prevention film. Therefore, the steps from substrate cleaning to exposure when using the foreign matter adhesion prevention film are as follows. First, the substrate is washed and inspected for foreign matter such as dust on the surface where the circuit pattern is present and the surface where the circuit pattern is not present. If there is no foreign matter such as dust, attach a foreign matter adhesion prevention film by using a jig. This foreign matter adhesion prevention film is
It is also attached to the surface where the circuit pattern exists. Whether or not there is a foreign matter on the surface of the substrate after the foreign matter adhesion prevention film is applied
It inspects using the method of 9-82727. If there is no foreign matter, it is stored in a cassette and sent to a reduction exposure device to start an exposure process. By attaching a foreign matter adhesion prevention film,
Since the foreign matter attached to the film of 0 to 30 μm or less can be ignored, the yield could be improved. Since it is generally said that the establishment of foreign matter adhesion is inversely proportional to the square of the foreign matter size, the establishment of foreign matter adhesion of 20 to 30 μm or more cannot be completely ignored. Therefore,
In order to further improve the yield, it has become necessary to inspect the presence or absence of relatively large foreign matter on the foreign matter adhesion prevention film. An object of the present invention is to attach a foreign matter adhesion prevention film to a foreign matter adhesion prevention film which is attached to a substrate such as a reticle or photomask used for exposure through a frame when the foreign matter interferes with the exposure. The foreign matter can be removed by returning the substrate to the magazine, and the substrate with the foreign matter adhesion prevention film can be carried into the exposure position from the magazine while the foreign matter adhesion prevention film is not always present on the foreign matter. An object of the present invention is to provide an exposure apparatus capable of exposing an exposure substrate with a high yield. In order to achieve the above object, the present invention stores a reticle, a photomask or the like used for exposure with a frame having a foreign matter adhesion preventing film attached thereto. And a foreign matter detection device that is installed between the magazine and the exposure position and that detects a large foreign matter that is attached to the foreign matter adhesion prevention film and is attached to the substrate through the frame and that interferes with the exposure. A substrate with a foreign matter adhesion prevention film
When a large foreign matter that interferes with the exposure is detected on the foreign matter adhesion preventing film on the foreign matter adhesion preventing film by being conveyed from the magazine to the exposure position via the position where the foreign matter detecting apparatus is installed, A transport mechanism that returns the substrate with the foreign matter adhesion prevention film to the magazine from the position where the foreign matter detection device is installed, and the above foreign matter detection device does not detect a large foreign matter that interferes with exposure on the foreign matter adhesion prevention film. A projection exposure apparatus for projecting and exposing a circuit pattern on the substrate, which is transported to an exposure position by a mechanism, to a substrate with a foreign matter adhesion prevention film onto a substrate to be exposed by a projection exposure optical system. It is a device. According to the present invention, in the above-described exposure apparatus, the foreign matter detection device includes a light irradiation optical system for irradiating a band-shaped light beam on the foreign matter adhesion prevention film over one width of the foreign matter adhesion prevention film. The scattered light from the edge of the circuit pattern formed on the substrate is detected by the light irradiation optical system so as not to detect scattered light, and passes through the center of the width d of the substantially band-shaped light flux on the foreign matter adhesion prevention film, and adheres the foreign matter. The detection optical axis is tilted by an angle ψ or more with respect to the irradiation band-shaped light beam so that the detection light axis does not intersect with the band-shaped light beam on the surface of the substrate due to the light that has passed through the prevention film (however, the relationship of angle ψ = tan to ¹ d / 2t). And
t is the distance between the substrate surface and the foreign matter adhesion prevention film, and d is the width of the irradiation band-shaped light beam. ) A detection optical system for detecting scattered light from only the foreign matter adhered on the foreign matter adhesion prevention film due to the band-shaped light flux radiated and irradiated by the light irradiation optical system; and a foreign matter adhesion prevention film by the light irradiation optical system. A foreign matter adhered on the foreign matter adhesion prevention film, which is composed of a linear sensor having a light receiving portion corresponding to a band-shaped light beam irradiated over one width of the foreign matter adhesion prevention film, and which is detected by the detection optical system. And a photoelectric conversion means for receiving the scattered light from and converting it into a signal. Further, the present invention is characterized in that, in the exposure apparatus, the transport mechanism is configured to return from the exposure position in the projection exposure apparatus to the magazine in order to store the substrate with the foreign matter adhesion prevention film in the magazine. To do. Further, the present invention is characterized in that, in the magazine of the exposure apparatus, the substrate with the foreign matter adhesion prevention film is put in a cassette and accommodated therein. DETAILED DESCRIPTION OF THE INVENTION The present invention will be described below with reference to FIGS. 1 to 12. FIG. 1 shows the configuration of a first embodiment of a reduction projection exposure apparatus equipped with a foreign substance inspection device on a foreign substance adhesion prevention film. First, after cleaning, the substrate 39 having the foreign matter adhesion prevention film 23 attached thereto via the frame 24 is stored in the magazine 6 in a cassette in a state where no foreign matter exists. In the exposure step, the substrates are taken out of the cassette one by one, and after exposure, they are returned to their original positions. That is, the substrate 39
Is pulled out from the cassette in the magazine 6 in the direction of arrow 5a, and is moved in the direction of arrow 4a by the transport arm 3.
The foreign matter inspection on the foreign matter adhesion prevention film 23 mounted on the surface of the substrate 39 is performed by the upper foreign matter inspection apparatus 1 and the lower foreign matter inspection apparatus 2 installed above and below the transfer arm 3. if,
If a foreign substance (for example, 20 to 30 μm or more) is present on the foreign substance adhesion prevention film 23, the substrate is returned to the original cassette and the foreign substance is removed. On the other hand, if there is no foreign matter, the carrier arm 3 is rotated by the rotating machine 8 in the direction of the arrow 7a, placed at the exposure position 9, and one chip is placed on the wear (substrate to be exposed) 11 via the exposure optical system 10. Are transcribed one by one. When the exposure process using this substrate is completed, the substrate 39 is stored in the cassette in the magazine 6 again. Also, in FIG.
It shows a second embodiment according to the present invention. Here, the substrate 39 is transported by a transport mechanism that is driven by the motor 13 and uses the belt 12, for example. An embodiment of the foreign matter inspection apparatus used in the embodiment of the present invention described above will be described below. FIG. 3 shows a foreign matter adhesion prevention film (pellicle film) 2 attached to a substrate 39 such as a photomask or a reticle via a frame 24.
3 shows an apparatus for detecting foreign matter on the surface.
According to this, the laser light from the laser oscillator 14 is sequentially passed through the polarizing plate 16 and the condenser lens 15, and then is totally reflected by the galvano mirror 17 which is reciprocally rotated and oscillated by the triangular wave signal, and then the collimator lens 18 is used. A laser spot is formed on the surface of the foreign matter adhesion prevention film 23 via the oblique direction. In this case, the galvanometer mirror 17 is driven by a triangular-wave electric signal and rotationally oscillates at a constant period, so that the laser spot is a foreign matter adhesion prevention film 23.
The surface is scanned reciprocally in the X direction at a constant speed, whereby a linear scanning line 22 is formed. On the other hand, the means for detecting the scattered light 21 from the foreign matter 20 is an imaging lens 26, a light shielding plate (not shown), a one-dimensional linear sensor (CCD, photodiode array, etc.).
, Which is a self-scanning storage type photoelectric conversion element 27, and is provided so that the scanning line 22 of the laser spot can be seen obliquely from above. That is, the image of the scanning line 22 of the laser spot scanning the surface of the foreign matter-attached film 23 in a straight line by the imaging lens 26 is formed on the photoelectric conversion element 27. Therefore, the motor 48
When the glass substrate 39 is constantly fed in the Y direction at a constant speed by the feed screw 49 and the surface of the foreign matter adhesion prevention film 23 is scanned over the entire area, if the foreign matter 20 is present on the scanning line 22, the foreign matter is present. The intensity of scattered light 21 from 20 is accumulated,
It is what is detected. Now, the laser light irradiation system will be described in more detail with reference to FIG. 4. After the laser light from the laser oscillator 14 passes through the polarizing plate 16, (when using a polarized laser such as a semiconductor laser, the polarizing plate is (Unnecessary) Although it is condensed on the surface of the galvano mirror 17 by the condenser lens 15, this laser light is condensed on the surface of the galvano mirror 17,
The laser light is totally reflected on the surface of the galvanometer mirror 17 and reaches the collimator lens 18. Since the collimator lens 18 is installed so that its focal point is located on the rotation center axis of the galvanometer mirror 17, the laser beam 19 transmitted through the collimator lens 18 is used.
Becomes a parallel light flux, and reciprocally vibrates in the direction 35 as shown by the rotational vibration of the galvano mirror 17, and as a result, linearly reciprocally scans on the surface of the foreign matter adhesion prevention film 23. In this case, if the focal length of the collimator lens 18 is f, the deflection angle of the laser beam is θ, and the scanning amount of the laser spot is h, the scanning amount h is expressed by the following equation (1). h = f.tan.theta..apprxeq.f..theta. (tan.theta..apprxeq..theta. when .theta. is small) (Equation 1) Assuming that the rotation speed of the galvanomirror 17 is constant, the laser spot focused in parallel by this is the foreign matter adhesion prevention film 23. It is to move at a constant velocity on the surface. FIG. 5 shows a triangular wave signal as a signal for driving the galvanometer mirror 17 and a light quantity accumulation time per one photoelectric conversion element 27. As shown in the figure, the scanning time T of the photoelectric conversion element 27 is set to an integral multiple in synchronization with the cycle t of the galvano mirror 17, thereby obtaining the light amount accumulated in the photoelectric conversion element 27. Since the scanning conditions of are the same, FIG.
As shown in FIG. 5, the scattered light intensity from the foreign matter existing near the center on the surface of the foreign matter adhesion prevention film 23 and the scattered light intensity from the foreign matter present at the edge are the same, and a substantially uniform scattered light intensity distribution 28 is obtained. It is a thing. Therefore, it is not necessary to change the threshold level depending on the location as in the past, and even if the foreign matter adhesion prevention film 23 moves up and down, stable foreign matter detection can be performed only with the constant threshold level 43. FIG. 7 shows factors that generate scattered light from other than foreign matter. The scattered light 21 from the foreign matter 20 is apt to be erroneously detected as scattered light 31 from the frame 24 to which the foreign matter adhesion preventing film 23 is attached and the foreign matter adhesion preventing film 2
Scattered light 30 generated when the light passing through 3 hits the pattern (circuit pattern) 29 formed on the surface 5 of the glass substrate 39 is considered. By the way, as shown in FIGS. 8A and 8B, in general, when a transparent material such as a glass substrate is obliquely irradiated with light such as a laser beam, it varies with respect to the substrate surface 5 depending on the irradiation angle α. The wave (s-polarized wave) 44 in which the magnetic field surface oscillates in a direction parallel to the horizontal direction (s-polarized wave) has many reflection components. In the case of (wave) 45, there is a property that the transmission component increases. Due to this fact, in order to prevent the influence of scattered light from the pattern 29 formed on the substrate surface 5 as much as possible, the polarizing plate 16 irradiates the foreign matter adhesion prevention film 23 with an s-polarized wave and passes through the foreign matter adhesion prevention film 23. It may be desirable to minimize light. However, the foreign matter adhesion prevention film 23
Pattern 2 even with an extremely small amount of laser light that has passed through
Since scattered light from 9 is generated, by setting the optical axis 42 of the scattered light detection system to be tilted by ψ with respect to the perpendicular 41 of the substrate surface 5 as shown in FIGS. It is desirable not to look at the location where the scattered light 30 is generated. Incidentally, FIG. 9 shows a pattern 29 when inspecting the foreign matter adhesion prevention film 23, and FIG. 10 shows a pattern 29 when inspecting a relatively thick glass substrate 39 surface having the same function as the foreign matter adhesion prevention film 23. Scattered light 3
The generated states of 0 are shown respectively. Further, the symbol d in the drawing is the beam diameter of the irradiation laser light, t is the thickness of the glass substrate 39 or the thickness of the frame 24 to which the foreign matter adhesion prevention film 23 is attached, and φ is the refraction angle with respect to ψ. Show. In any case, the scattered light detection system has the pattern 29.
The condition for not detecting the scattered light 30 from is that after the optical axis 42 of the detection system passes through the substrate surface 5 or the surface of the foreign matter adhesion prevention film 23, it is refracted or goes straight to form a pattern forming surface on the glass substrate 39. The intersection point is the beam diameter d of the irradiation laser beam 19.
Is not included in. That is, it is necessary to set ψ that satisfies the following equation (2). ^{ψ ≧ sin ~ 1 {nsin (} tan ~ 1 (d / 2t))} ... ( Equation 2) where, n is the refractive index. In the case shown in FIG. 9, the foreign matter adhesion prevention film 23 is thin and goes straight, so n is 1. Thus, when n is set to 1, the angle ψ is ψ ≧
tan to ¹ (d / 2t), and when the optical axis 42 of the detection optical system and the center vertical line 41 of the beam width d of the band-shaped light beam 19 intersect on the foreign matter adhesion prevention film 23, the light of the detection optical system Axis 4
2 is a band-shaped light beam 1 on the pattern formation surface of the substrate 39.
The scattered light 30 from the pattern 29 is less likely to be incident on the imaging lens 26 of the detection optical system, and the scattered light from the foreign matter existing on the foreign matter adhesion prevention film 23 Only the incident light is incident and can be detected by the photoelectric conversion element 27. However, in reality, the amount of aberration of the imaging lens 26 and the like also affect the angle .psi., Which varies slightly from the angle .psi. Obtained by the above equation (2), but the angle .psi.
It is necessary to satisfy the equation (2) within the following range. Therefore, when the angle ψ is close to 0 °, the above equation (2) cannot be satisfied, so that it is clear that the angle ψ is set to the side close to 20 °.
The angle ψ is set to 20 ° or less because the laser spot is irradiated by being linearly scanned by the collimator lens 18 from the lateral direction, and the scattered light from the foreign matter existing on the foreign matter adhesion prevention film 23 is detected by the optical system. This is for facilitating detection by the image forming lens 26. On the other hand, the scattered light 31 generated from the frame 24 to which the foreign matter adhesion prevention film 23 is attached is shown in FIG.
As shown in, it is possible to block light by additionally installing the light blocking device 32 at the image forming position of the photoelectric conversion element 27. When a light shielding device is appropriately provided near the imaging lens 26, the scattered light 31 from the frame 24 cannot be detected by the photoelectric conversion element 27. As for the structure of the foreign matter inspection device, the structure of Japanese Patent Laid-Open No. 57-80546 may be considered.
It is also possible to provide a TV camera or the like during transportation to visually observe in a state where foreign matter is unlikely to adhere. As the installation location of the foreign matter inspection apparatus, it is possible to provide an inspection station on the reduction projection exposure apparatus and install it not only while the substrate is being conveyed. Further, the present invention can be used not only in the reduction projection exposure apparatus but also in the 1: 1 reflection type projection exposure apparatus. According to the present invention, when there is a foreign substance that interferes with the exposure on the foreign substance adhesion preventing film mounted on the substrate such as the reticle or photomask used for the exposure through the frame, By returning the substrate with the foreign substance adhesion prevention film to the magazine, it is possible to remove the foreign matter, and the substrate with the foreign substance adhesion prevention film is always moved from the magazine to the exposure position while there is no foreign substance on the foreign matter adhesion prevention film that interferes with the exposure. The substrate to be exposed can be exposed to light by a projection exposure optical system with a high yield, and as a result, semiconductors can be produced with a high yield.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram showing one embodiment according to the present invention. FIG. 2 is a diagram showing another embodiment according to the present invention. FIG. 3 is a diagram showing a configuration of an embodiment of a foreign matter detection device according to the present invention. FIG. 4 is a diagram for explaining the operation of the laser light irradiation system in the configuration shown in FIG. 5 is a diagram for explaining a relationship between a drive signal of a galvanometer mirror and a light amount accumulation time of a photoelectric element in the configuration shown in FIG. FIG. 6 is a diagram for explaining foreign matter detection processing according to the present invention. FIG. 7 is a diagram showing factors that generate scattered light from other than foreign matter. 8A and 8B are diagrams showing the reflection states of s-polarized wave and p-polarized wave on the substrate surface, respectively. FIG. 9 is a diagram for explaining a desirable setting state of an optical axis of a scattered light detection system that makes it impossible to detect unnecessary scattered light. FIG. 10 is a diagram for explaining a desirable setting state of an optical axis of a scattered light detection system that makes it impossible to detect unnecessary scattered light. FIG. 11 is a diagram showing a desirable configuration of a scattered light detection system which similarly makes unnecessary scattered light undetectable. [Explanation of Reference Signs] 1, 2 ... Foreign matter inspection device, 3 ... Transport arm, 10 ... Exposure optical system 14 ... Laser oscillator, 15 ... Condensing lens, 16 ... Polarizing plate 17 ... Galvano mirror, 18 ... Collimator lens, 26
... Imaging lens 27 ... Photoelectric conversion element, 32 ... Shading device

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location H01L 21/30 502J 514E

Claims (1)

[Claims] 1. A magazine that stores a reticle or photomask used for exposure with a frame with a foreign substance adhesion prevention film attached to the substrate, and is installed between the magazine and the exposure position, and is attached to the substrate via the frame The foreign matter detection device that detects a large foreign matter that adheres to the foreign matter adhesion prevention film and interferes with exposure, and the substrate with the foreign matter adhesion prevention film through the position where the foreign matter detection device is installed from the magazine. When the foreign matter detection device detects a large foreign matter that interferes with exposure on the foreign matter adhesion prevention film, the substrate with the foreign matter adhesion prevention film is placed at the position where the foreign matter detection device is installed. From the transport mechanism for returning the magazine to the magazine and the foreign matter detection device, no large foreign matter that interferes with the exposure is detected on the foreign matter adhesion prevention film, and the transport mechanism transports the foreign matter to the exposure position. Exposure apparatus comprising the projection exposure apparatus for projection exposure on a substrate to be exposed by the foreign matter-preventing film with the projection exposure optical system, the circuit pattern on the substrate relative to the substrate that is. 2. The foreign matter detection device comprises a light irradiation optical system for irradiating a band-shaped light beam on the foreign matter adhesion prevention film over one width of the foreign matter adhesion prevention film, and an edge of a circuit pattern formed on the substrate. A band-like shape on the surface of the substrate due to the light passing through the center of the width d of the substantially band-shaped light flux on the foreign matter adhesion prevention film irradiated by the light irradiation optical system so as not to detect scattered light and passing through the foreign matter adhesion prevention film. Of the detection optical axis with respect to
Inclined as above (however, the relationship is such that angle ψ = tan to ¹ d / 2t, where t is the distance between the substrate surface and the foreign matter adhesion prevention film, d
Is the width of the light beam in the irradiation band shape. ) A detection optical system for detecting scattered light from only the foreign matter adhered on the foreign matter adhesion prevention film due to the band-shaped light flux radiated and irradiated by the light irradiation optical system; and a foreign matter adhesion prevention film by the light irradiation optical system. A foreign matter adhered on the foreign matter adhesion prevention film, which is composed of a linear sensor having a light receiving portion corresponding to a band-shaped light beam irradiated over one width of the foreign matter adhesion prevention film, and which is detected by the detection optical system. The exposure apparatus according to claim 1, further comprising: a photoelectric conversion unit that receives scattered light from the device and converts it into a signal. 3. 2. The transport mechanism is configured to return from the exposure position in the projection exposure apparatus to the magazine so that the substrate with the foreign matter adhesion prevention film can be stored in the magazine. Exposure equipment. 4. 2. The exposure apparatus according to claim 1, wherein in the magazine, the substrate with the foreign matter adhesion preventing film is put in a cassette and accommodated therein.