KR20210080192A - Holding device, lithography apparatus, and manufacturing method of article - Google Patents

Abstract

The present invention provides a technique advantageous for high-precision determination of the detachment of a plate from a holding surface. A holding device for holding the plate includes: a holding unit holding the plate on the holding surface; an imaging unit capturing an image of a mark formed on the plate held on the holding surface; and a processing unit for judging whether or not the plate has disengaged from the holding surface based on the image of the mark obtained by the imaging unit in a state where a force is applied to the plate.

Description

HOLDING DEVICE, LITHOGRAPHY APPARATUS, AND MANUFACTURING METHOD OF ARTICLE

The present invention relates to a holding apparatus, a lithographic apparatus, and a method of manufacturing an article.

In recent years, with the improvement of the superimposition precision of a lithographic apparatus for forming a pattern on a substrate, the flatness of the original plate or the substrate and the chuck holding it is improved, and the adhesion between the original plate or the substrate and the chuck is improved. In a lithographic apparatus, as a method of holding an original plate or a substrate, there are a vacuum adsorption method and an electrostatic adsorption method.

In the vacuum adsorption method, a foreign material may enter between the substrate and the chuck and the foreign material may adhere to the substrate, or the substrate and the chuck may be firmly in close contact. Also in the electrostatic adsorption method, there is a possibility that a residual adsorption force is generated on the substrate when the power is turned off due to charging of the electrostatic chuck or the substrate, and the substrate and the chuck may be stuck.

Patent Document 1 describes detecting the distance between the chuck and the substrate and the displacement of the plane of the substrate using a plurality of non-contact sensors provided on the chuck side. Patent document 2 describes that a force is applied to a board|substrate using a lift pin, and the detachment of a board|substrate is detected by the position change of a lift pin.

Japanese Patent Laid-Open No. 2006-332519 Japanese Patent Laid-Open No. 2005-123422

However, in the prior art, the state in which the substrate (plate) is locally fixed or the state in which the substrate is locally separated is erroneously determined that the substrate is detached from the chuck. Further, in the prior art, only a large displacement in the direction along the surface of the substrate can be detected, and a minute displacement cannot be detected.

SUMMARY OF THE INVENTION The present invention provides a technique advantageous for high-precision determination of whether a plate has detached from a supporting surface.

According to one aspect of the present invention, there is provided a holding device for holding a plate, comprising: a holding unit for holding the plate on a holding surface; an imaging unit for capturing an image of a mark formed on the plate held on the holding surface; and a processing unit for judging whether or not the plate has detached from the holding surface, based on the image of the mark obtained by the imaging unit in a state in which a force for disengaging from the holding surface is given to the plate. A retaining device is provided.

According to the present invention, it is possible to provide a technique advantageous for high-precision determination of that the plate has detached from the holding surface.

1 is a diagram showing the configuration of an exposure apparatus.
Fig. 2 is a diagram showing an example of arrangement of marks for reticle alignment.
3 is a view showing an example of arrangement of marks for performing wafer alignment.
4 is a diagram showing the configuration of a holding device.
5 is a diagram for explaining a reticle collection operation.
6 is a diagram showing an example of arrangement of marks for reticle alignment.
It is a figure explaining position measurement using the mark at the time of reticle collection|recovery.
8 is a flowchart of a reticle retrieval operation.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. At this time, the following embodiment does not limit the invention concerning a claim. Although a plurality of features are described in the embodiment, not all of these plurality of features are essential to the invention, and a plurality of features may be arbitrarily combined. Moreover, in the accompanying drawings, the same reference numerals are assigned to the same or similar components, and duplicate descriptions are omitted.

<First embodiment>

1 is a schematic diagram of an exposure apparatus 100 that is an example of a lithographic apparatus to which a holding apparatus of the present invention is applied. In this specification and drawings, a direction is displayed in the XYZ coordinate system which makes a horizontal plane XY plane. Generally, the reticle 1 is placed on the reticle stage 3 so that its surface is parallel to the horizontal plane (XY plane), and the wafer 4 is placed on the wafer stage 6 so that its surface is parallel to the horizontal plane. placed on top Accordingly, hereinafter, directions perpendicular to each other on a plane along the surface of the reticle 1 or wafer 4 are referred to as X and Y axes, and directions perpendicular to the X and Y axes are referred to as Z axes. In the following, directions parallel to the X-axis, Y-axis, and Z-axis in the XYZ coordinate system are referred to as X-direction, Y-direction and Z-direction, and the rotational direction around the X-axis, the rotational direction around the Y-axis, The rotational directions around the axis are referred to as the θx direction, the θy direction, and the θz direction, respectively.

The exposure apparatus 100 is an exposure apparatus that transfers a circuit pattern onto a wafer 4 serving as a substrate using a reticle 1 (original plate, mask) on which a circuit pattern of a semiconductor device is formed. The exposure apparatus 100 may be, for example, an exposure apparatus that exposes a substrate without interposing a liquid between the projection optical system 7 and the wafer 4 . Alternatively, the exposure apparatus 100 may be an immersion exposure apparatus that exposes a substrate with a liquid interposed between the projection optical system 7 and the wafer 4 .

In the present embodiment, an example in which the holding device for holding the reticle 1 which is a plate is applied to the exposure apparatus 100 will be described. The exposure apparatus 100 includes a reticle stage 3 , an illumination optical system 8 for illuminating a reticle 1 held by the reticle stage 3 , a wafer stage 6 , and a pattern of the reticle 1 . A projection optical system (7) for projecting the image to the wafer (4) on the wafer stage (6) is provided. The exposure apparatus 100 further includes a surface position detector 14 for detecting the height (position in the Z direction) of the surface of the wafer 4 , and a wafer alignment detector 16 for aligning the wafer 4 . ) can be provided. The surface position detector 14 includes a light projecting portion 14a that emits light on the surface of the wafer 4 and a light receiving portion 14b that receives reflected light reflected from the surface of the wafer 4 . The exposure apparatus may further include a control unit C for controlling the exposure process. The reticle 1 and the wafer 4 are held by a reticle chuck 2 (original plate holding part) and a wafer chuck 5 (substrate holding part), respectively, and are optically substantially conjugated via a projection optical system 7 , respectively. (the object plane and the image plane of the projection optical system 7) of The reticle chuck 2 holds the reticle 1 by, for example, vacuum suction or electrostatic suction, and the reticle stage 3 is accompanied by the reticle chuck 2 and the reticle 1, for example, XY can be moved in the direction Similarly, the wafer chuck 5 holds the wafer 4 by, for example, vacuum suction or electrostatic suction, and the wafer stage 6 is accompanied by the wafer chuck 5 and the wafer 4, for example. For example, it can move in the XY direction.

A laser interferometer 10 provided in the lateral direction of the reticle stage 3 measures the position of the reticle stage 3 . The control unit C controls the actuator that drives the reticle stage 3 to control the position of the reticle stage 3 in the Y direction. On the reticle stage 3 , a reticle reference plate 12 is arranged. The height of the pattern surface of the reticle reference plate 12 is substantially equal to the height of the pattern surface of the reticle 1 . A bar mirror 11 that reflects the beam emitted from the laser interferometer 10 is fixed to the reticle stage 3 , and the position and movement amount of the reticle stage 3 are sequentially measured by the laser interferometer 10 .

Similarly, the laser interferometer 10 provided in the lateral direction of the wafer stage 6 measures the position of the wafer stage 6 . The control unit C controls the actuator that drives the wafer stage 6 to control the position of the wafer stage 6 in the Y direction. A wafer reference plate 13 is disposed on the wafer stage 6 . A bar mirror 11 that reflects the beam emitted from the laser interferometer 10 is fixed to the wafer stage 6 , and the position and movement amount of the wafer stage 6 are measured by the laser interferometer 10 .

The light source 9 may be, for example, a KrF excimer laser that generates light of a wavelength of 248 nm, but instead, for example, a mercury lamp, an ArF excimer laser (193 nm), an EUV light source, etc. may also be employed. . The light beam emitted from the light source 9 enters the illumination optical system 8 and illuminates the reticle 1 after being shaped into a set shape, coherence, and polarization state. The light diffracted from the delicate circuit pattern formed on the underside of the reticle 1 is imaged on the wafer 4 placed on the wafer stage 6 by the projection optical system 7 .

In order to measure the displacement of the reticle 1, a reticle alignment detector 15 is used. The reticle alignment detector 15 is an image pickup unit that images a mark formed on the reticle 1 on the holding surface for holding the reticle of the reticle chuck 2 . The control unit C drives the reticle stage 3 above the reticle alignment detector 15 . The reticle alignment detector 15 captures images of the alignment mark 18 (reference mark) on the reticle stage 3 and the alignment mark 17 on the reticle 1 as shown in FIG. 2 . The control unit C can function as a processing unit that determines whether or not the reticle 1 has detached from the holding surface based on the image of the mark obtained by the reticle alignment detector 15 . For example, the control unit C obtains the position of the alignment mark 17 with respect to the alignment mark 18 from the image obtained by the reticle alignment detector 15 , and thereby the amount of position shift of the reticle 1 with respect to the reticle stage 3 . save As shown in FIG. 2 , a plurality of alignment marks 18 on the reticle stage 3 and alignment marks 17 on the reticle 1 are respectively arranged in the X direction, so that the X of the reticle 1 with respect to the reticle stage 3 is , Y, and θz directions can be measured.

The wafer alignment detector 16 detects a plurality of alignment marks provided in each of a plurality of predetermined sample shot regions among a plurality of shot regions formed on the wafer 4 . The control unit C obtains the position of the sample shot based on the detection result.

At this time, in Fig. 1, the reticle alignment detector 15 and the wafer alignment detector 16 are each provided as an off-axis detection unit that detects the alignment mark without passing through the projection optical system 7, but is not limited thereto. . For example, the reticle alignment detector 15 and the wafer alignment detector 16 may each be provided as a TTL (Through The Lens) detection unit that detects an alignment mark via the projection optical system 7 .

In Fig. 3, an example of arrangement of marks for performing wafer alignment is shown. 3A shows a plurality of shot regions formed in a grid shape on the wafer 4, and FIG. 3B shows an enlarged view of one sample shot region among the plurality of shot regions. As shown in Fig. 3B, a plurality of alignment marks MX, MY, and PM are formed in the sample shot region. The wafer stage 6 is driven so that these plurality of alignment marks MX, MY, and PM are located in the detection area of the wafer alignment detector 16 . Thereafter, the position of each alignment mark is detected by the wafer alignment detector 16 , and the amount of displacement of the wafer 4 with respect to the wafer stage 6 is measured by the control unit C . Thus, in the present embodiment, the wafer alignment detector 16 and the control unit C constitute a measurement unit that measures the amount of position shift of the wafer 4 .

Fig. 4 is a diagram showing the configuration of a holding device for holding the reticle 1 serving as a plate in the present embodiment. In Fig. 4, a reticle hand 21 constituting the reticle carrying unit holds the reticle 1 and performs a collection or supply operation. The reticle hand 21 can be retracted to a position that does not affect the driving of the reticle stage 3 after the collection operation or the supply operation is completed.

The holding device ejects a gas toward the reticle 1 from a holding surface holding the reticle 1 of the reticle chuck 2 when the reticle 1 is retrieved, thereby releasing the reticle 1 from the holding surface. A gas injection unit 30 that applies a force to the reticle 1 may be provided. When the reticle 1 is recovered, the gas ejection unit 30 injects a gas to the back surface of the reticle 1 , thereby assisting the reticle 1 from detaching from the reticle chuck 2 . The gas injection unit 30 may include a gas supply unit 20 and a gas supply path 19 that is a flow path for the gas from the gas supply unit 20 . The gas supply path 19 is formed in the reticle stage 3 . A plurality of gas injection ports 19a for injecting gas toward the reticle 1 are formed on the holding surface of the reticle chuck 2 , and the plurality of gas injection ports 19a communicate with a gas supply path 19 , respectively. .

At this time, instead of applying an external force to the reticle 1 by gas injection, a pin driving actuator for driving a lift pin capable of retracting and retracting with respect to the holding surface may be provided. A pin drive actuator can apply a force to disengage the reticle 1 from the holding surface of the reticle chuck by pushing up the lift pins. However, the external force applied to the reticle 1 by the lift pin is a force that does not cause damage to the reticle 1 or the reticle chuck 2 even when the reticle 1 is fixed to the reticle chuck 2 . .

Note that the position at which the reticle 1 is retrieved and supplied is a position where the reticle alignment detector 15 is located below the reticle stage 3 . Accordingly, the images of the alignment mark 18 on the reticle stage 3 and the alignment mark 17 on the reticle 1 are captured by the reticle alignment detector 15 , and the control unit C can measure their relative positions.

The configuration of the exposure apparatus in the present embodiment is substantially as described above. Next, a method for detecting separation of the reticle chuck 2 from the reticle 1 according to the present embodiment will be described.

With reference to FIG. 5, the reticle collection operation by the holding device will be described.

5A shows a state before the reticle 1 is detached from the reticle chuck 2 . The alignment mark 18 on the reticle stage 3 and the alignment mark 17 on the reticle 1 are imaged by the reticle alignment detector 15, and the relative position is measured by the control unit C. At this time, the reticle hand 21 is not in contact with the reticle 1 .

Fig. 5B shows a state in which the reticle hand 21 is lowered from the state shown in Fig. 5A and the reticle hand 21 is in contact with the reticle 1 . The reticle hand 21 holds the reticle 1 for reticle recovery, and the reticle chuck 2 releases the vacuum holding force or the electrostatic holding force to release the holding state of the reticle 1 .

FIG. 5C shows a state in which a force for releasing the reticle 1 from the holding surface of the reticle chuck 2 is applied by the gas injection unit 30 from the state of FIG. 5B . While the reticle 1 is held by the reticle hand 21, the gas 22 is ejected from the reticle chuck 2 to the reticle 1 by the gas ejection unit 30, whereby the reticle 1 is The reticle chuck 2 is in a detachable state.

As shown in Fig. 6, reticle alignment marks 17a and 17b are formed at, for example, both ends of the reticle 1 in the X direction. Further, on the reticle stage 3, alignment marks 18a and 18b serving as reference marks are formed at corresponding positions of the reticle alignment marks 17a and 17b, respectively. When the reticle chuck 2 has a divided configuration, for example, two pairs of alignment marks as shown in FIG. 6 are provided on each of the divided chucks. At this time, the mark arrangement|positioning shown in FIG. 6 is an example, for example, arrangement|positioning of three or more marks, etc. other mark arrangement|positioning may be employ|adopted.

The control unit C as a processing unit receives a first image which is an image of a mark obtained by the reticle alignment detector 15 which is an imaging unit at a first timing before a force for detaching the reticle 1 from the holding surface is applied to the reticle 1 acquire Further, the control unit C receives a second image which is an image of the mark obtained by the reticle alignment detector 15 at a second timing while the force for releasing the reticle 1 from the holding surface is applied to the reticle 1 acquire The control unit C determines that the reticle 1 has detached from the holding surface based on the acquired first image and the second image. For example, the control unit C changes at least one of the position of the mark in the first direction (XY direction) along the holding surface and the position of the mark in the second direction (Z direction) orthogonal to the holding surface. When this is done, it is determined that the reticle 1 has detached from the holding surface. Hereinafter, specific examples thereof will be described.

The relative position measurement of the alignment mark 18a on the reticle stage 3 and the alignment mark 17a on the reticle using the reticle alignment detector 15 at the time of reticle collection with reference to FIG. 7 is demonstrated. At this time, the relative position measurement of the alignment marks 17b and 18b is also performed similarly.

Fig. 7A shows the relative position measurement in the state before the reticle 1 is detached from the reticle chuck 2 (Fig. 5A, first timing). At this time, the relative positions dx1 of the alignment marks 17a and 18a in the X direction and the relative positions dy1 in the Y direction are measured. Moreover, the contrast 1 which is the contrast of the alignment mark 17a is also measured.

Fig. 7B) shows the relative position measurement in a state in which the reticle 1 is detached from the reticle chuck 2 (Fig. 5C, second timing). At this time, the relative positions dx2 of the alignment marks 17a and 18a in the X direction and the relative positions dy2 in the Y direction are measured. Moreover, the contrast 2 which is the contrast of the alignment mark 17a is also measured. If the reticle 1 and the reticle chuck 2 during contrast measurement have a large gap when the reticle 1 and the reticle chuck 2 are stuck locally, the reticle 1 and the reticle chuck 2 may break. Therefore, the range of the displacement of the relative position to be measured is, for example, 100 µm or less.

The control unit C, from the difference between the relative positions dx1 and dx2 in the X direction of the alignment marks 17a and 18a, and the relative positions dy1 and dy2 in the Y direction of the alignment marks 17a and 18a, the reticle 1 and the horizontal direction (XY direction) Calculate the amount of position change of Further, the control unit C calculates the amount of change in the vertical direction (Z direction) of the reticle 1 from the difference between the contrast 1 and the contrast 2 .

Similarly, the control unit C confirms a change in the horizontal direction and the vertical direction of the reticle 1 of the other alignment marks 17b and 18b. When the two pairs of alignment marks change in at least one of the horizontal direction and the vertical direction of the reticle 1 at the same time, the control unit C determines that the reticle 1 is detached from the holding surface of the reticle chuck 2 . .

In the above example, the XY position in the horizontal direction of the reticle 1 was measured by measuring the relative positions of the alignment mark 17 on the reticle and the alignment mark 18 (reference mark) on the reticle stage. However, the same effect can be obtained by confirming with the change of the relative position with respect to the reference position of the reticle alignment mark detection system.

Fig. 8 is a flowchart showing the reticle collection operation in the present embodiment. S102 is a state in which, before the reticle 1 is separated from the reticle chuck 2 , a force for releasing the reticle 1 from the holding surface of the reticle chuck 2 is not applied by the gas injection unit 30 . It is a pre-measurement process executed in (state of Fig. 5A). At the first timing in this state, by the reticle alignment detector 15, a first image including the image of the alignment mark 17 on the reticle 1 and the image of the alignment mark 18 as the reference mark on the reticle stage 3 is is acquired The control unit C measures the relative position and contrast of both marks from the acquired first image by the method described with reference to FIG. 7A.

In S103 , the control unit C releases the holding force of the reticle 1 by the reticle chuck 2 to hold the reticle 1 on the reticle chuck 2 in the reticle hand 21 , and further, the gas injection unit By (30), an external force is applied to the reticle (1). In S104, at the second timing in this state, the image of the alignment mark 17 on the reticle 1 and the image of the alignment mark 18 as the reference mark on the reticle stage 3 are included by the reticle alignment detector 15 A second image is acquired. The control part C measures the relative position and contrast of both marks from the acquired 2nd image by the method demonstrated with reference to FIG. 7B.

In S105, the control unit C determines a change in the horizontal position (position in the XY direction) of the reticle 1 based on the relative positions measured in S102 and S104. When it is determined that the horizontal position of the reticle 1 has not changed, in S107, the control unit C determines that there is a deviation abnormality, that is, the reticle is not normally detached from the holding surface. When it is determined that the horizontal position of the reticle 1 has changed, in S106, the control unit C determines the change in the position in the vertical direction (Z direction) of the reticle 1 based on the contrast measured in S102 and S104. Conduct. If it is determined that the contrast has not changed, then, in S107, the control unit C determines that the deviation is abnormal, that is, the reticle is not normally detached from the holding surface. When it is determined that the deviation is abnormal, in S108, the control unit C notifies, such as displaying a warning for notifying the user of the deviation abnormality. If it is determined in S106 that the position in the vertical direction of the reticle 1 has changed, in S109, the control unit C determines that the separation is normal, that is, the reticle 1 is normally separated from the holding surface. When it is determined that the deviation is normal, the control unit C controls the reticle hand 21 to convey the reticle 1 to a predetermined recovery position.

According to the embodiment described above, it is possible to accurately determine that the reticle has detached from the holding surface.

<Second embodiment>

In the above-described first embodiment, the exposure apparatus 100 having a holding device for holding the reticle 1 which is a plate has been described, but the above description is an exposure having a holding device for holding the wafer 4 which is a plate. The same can be applied to devices. In that case, by using the wafer alignment detector 16 instead of the reticle alignment detector 15 as an image pickup unit for imaging a mark, it is determined whether the wafer 4 has detached from the holding surface of the wafer chuck 5 or not. can

In the above-described embodiment, an embodiment in which the present invention is applied to an exposure apparatus has been described. However, the present invention is also applicable to lithographic apparatuses other than exposure apparatuses, such as an imprint apparatus and a drawing apparatus. In the imprint apparatus, the imprint material supplied on the substrate and the mold are brought into contact, and energy for curing is applied to the imprint material to form a pattern of the cured product onto which the pattern of the mold is transferred. A drawing apparatus forms a pattern (latent image pattern) on a board|substrate by drawing on a board|substrate with a charged particle beam (electron beam) or a laser beam.

<Embodiment of article manufacturing method>

The article manufacturing method in the embodiment of the present invention is suitable for manufacturing articles such as microdevices such as semiconductor devices and elements having microstructures, for example. The article manufacturing method of the present embodiment includes a step of transferring a pattern of an original plate onto a substrate using the lithographic apparatus (exposure apparatus, imprint apparatus, drawing apparatus, etc.) includes In addition, this manufacturing method includes other well-known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method of the present embodiment is advantageous compared to the conventional method in at least one of the performance, quality, productivity, and production cost of the article.

The present invention is not limited to the above embodiments, and various changes and modifications are possible without departing from the spirit and scope of the invention. Accordingly, the claims are appended to clarify the scope of the invention.

1: reticle, 2: reticle chuck, 3: reticle stage, 15: reticle alignment detector, 17, 8: alignment mark, 19: gas supply path, 20: gas supply unit, 21: reticle hand, 30: gas injection unit

Claims (10)

A retaining device for holding a plate, comprising:
a holding part for holding the plate on a holding surface;
an imaging unit for imaging a mark formed on the plate held on the holding surface;
having a processing unit that determines whether or not the plate has detached from the holding surface based on the image of the mark obtained by the imaging unit in a state where a force for releasing the plate from the holding surface is given to the plate Characteristic retaining device.
The method of claim 1,
The processing unit includes: a first image that is an image of the mark obtained by the imaging unit at a first timing before the force is applied to the plate, and the imaging at a second timing while the force is being applied to the plate Based on the second image that is the image of the mark obtained by , at least the position of the mark in a first direction along the holding surface and the position of the mark in a second direction orthogonal to the holding surface and determining that the plate has detached from the holding surface when either one is changed.
3. The method of claim 2,
and a conveying unit configured to supply and retrieve the plate with respect to the holding unit, wherein at the second timing, the holding force of the plate by the holding unit is released, the plate is held by the conveying unit, and and the timing during which the force is being applied to the plate.
3. The method of claim 2,
The first image and the second image each include an image of the mark and an image of a reference mark formed in the holding portion,
The processing unit, when at least one of a position shift amount in the first direction of the mark with respect to the reference mark, and a contrast of the mark changes between the first image and the second image, the plate A holding device, characterized in that it is determined that the is separated from the holding surface.
The method of claim 1,
and a gas ejection portion for imparting the force to the plate by ejecting gas from the holding surface toward the plate.
The method of claim 1,
and a pin drive actuator that applies the force to the plate by pushing the plate from the holding surface to a lift pin.
A lithographic apparatus for forming a pattern on a substrate using an original plate, comprising:
A lithographic apparatus comprising the holding device according to any one of claims 1 to 6, which holds the original plate.
A lithographic apparatus for forming a pattern on a substrate, comprising:
A lithographic apparatus comprising the holding device according to any one of claims 1 to 6, which holds the substrate.
A step of forming a pattern on a substrate using the lithographic apparatus according to claim 7;
having a process of treating the substrate on which the pattern is formed in the process;
and manufacturing an article from the treated substrate.
A step of forming a pattern on a substrate using the lithographic apparatus according to claim 8;
having a process of treating the substrate on which the pattern is formed in the process;
and manufacturing an article from the treated substrate.

Images