JPH11168043A - Exposure apparatus and exposure method - Google Patents

Abstract

(57) [PROBLEMS] To provide an exposure apparatus and an exposure method that can easily perform alignment between projection optical systems. SOLUTION: A projection optical system 10 in an exposure apparatus manufacturing stage.
The alignment tolerances of the projection optical system 30, the illumination field, the mask moving means, and the strokes of the mask blinds are enlarged to compensate for the positional tolerances of the projection optical system 30, and the positional errors of the projection optical system are reduced to the masks 24, 44 and the mask blinds 20, 4.
Correction is made by a position shift of 0. The position detection of the masks 24 and 44 is performed by the reference mark FM provided on the substrate stage 50.
1, FM2 to a mask alignment system 27, 28;
This is performed by detecting at 48.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step-and-repeat type exposure apparatus used in the manufacture of semiconductor devices, liquid crystal display panels, and the like.

[0002]

2. Description of the Related Art In a manufacturing process of a semiconductor device or a liquid crystal display panel, a photomask is applied to a photosensitive substrate (hereinafter simply referred to as a substrate) such as a wafer or a glass plate coated with a photosensitive agent such as a photoresist via a projection optical system. And a pattern of a reticle (hereinafter, referred to as a mask) is exposed. In recent years, in exposure of a liquid crystal display panel or the like, a substrate to be exposed has become increasingly larger, and accordingly, an improvement in the processing capability of an exposure apparatus has become indispensable. One of the techniques to meet this demand is to use an exposure apparatus having a plurality of projection optical systems. Two projection optical systems are arranged in an exposure apparatus, and a pattern of a different mask is simultaneously exposed on a substrate by each projection optical system. According to this exposure apparatus, the stroke of the movable stage on which the substrate is mounted only needs to cover half the area of the substrate, which can contribute to reducing the installation area of the apparatus. In addition, the processing ability can reduce the total time of the steps and the exposure to half as compared with the case where the exposure is performed by one projection optical system and one mask.

[0003]

However, in the case of an exposure apparatus in which a plurality of projection optical systems are arranged, alignment of the projection optical systems becomes a problem. For example, when exposing a shot a and a shot b simultaneously by an exposure apparatus having two projection optical systems is expressed as (a, b), FIG.
As shown in (a), (a1, b1), (a2, b2), ‥‥, (a1
In the case where one device C is formed by exposing shots one by one and performing screen splicing as in (2, b12), a projection optical system that exposes the area A on the substrate 51 and the area B are exposed. It is necessary to adjust the position of the projection optical system to an accuracy that does not affect the splicing performance.

[0004] Further, as shown in FIG.
In step and repeat mode (d1, h1),
(D2, h2), (e1, i1), (e2, i2), ‥
Expose the shots one set at a time as
In the case where E, F, G, and 多 are formed in multiple planes, even when the screen joining is not performed by two projection optical systems, a plurality of layers of one device can be exposed to different exposure apparatuses having a plurality of projection optical systems. In order to perform exposure, it is necessary to make the distance between the two projection optical systems of each exposure apparatus equal. In addition, it is necessary to consider exposure errors caused by mask manufacturing errors and mask positioning errors. The present invention has been made in view of such a problem in an exposure apparatus, and an object of the present invention is to provide an exposure apparatus and an exposure method that can accurately perform exposure using a plurality of masks.

[0005]

According to the present invention, a projection optical system, a projection optical system, an illumination field, a mask moving means, and a mask are used to predict the alignment tolerance of the projection optical system and the manufacturing error of the mask at the stage of manufacturing the exposure apparatus. The object is achieved by enlarging the stroke of the blind and correcting the exposure error by shifting the position of the mask and the blind. That is, the exposure apparatus according to the first aspect of the present invention provides the pattern of at least two masks (24, 44) on the substrate (5).
1) In an exposure apparatus for exposing on the top, a first mask (2
A first detection device (27, 28) for detecting the position of 4),
A second detector (47, 48) for detecting a position of the second mask (44); and a first mask and a second mask based on detection results of the first detector and the second detector. Position adjusting device (26, 4) for adjusting at least one position of
6, 55) and illumination optical systems (11, 23, 31, 43) for illuminating the first mask and the second mask almost simultaneously.

The substrate exposure illuminance by the first mask and the substrate exposure illuminance by the second mask do not always match. Therefore, the exposure apparatus according to the second aspect controls the illumination time of the first mask by the illumination optical system and the illumination time of the second mask by the illumination optical system. A second shutter (33, 34)
A control device (55) for independently controlling the first shutter and the second shutter is provided. An exposure apparatus according to claim 3, wherein a first reference device (FM1) serving as a position reference of a first mask and a second reference device (FM2) serving as a position reference of a second mask are mounted on a substrate. It is arranged on the substrate stage to be used. By providing the two reference devices in this manner, the stroke of the substrate stage when detecting the position of the first mask and the position of the second mask can be shortened.

According to a fourth aspect of the present invention, the light source for illuminating the first mask and the light source for illuminating the second mask are common light sources. For this reason, the light amount difference caused by the light source is eliminated, and the exposure amount control can be facilitated. The exposure apparatus according to claim 5, wherein the illumination optical system has a first blind (20) for defining an illumination area of the first mask;
Blind (4) defining the illumination area of the mask
0), and the first blind and the second blind are adjusted according to the position adjustment of at least one of the first mask and the second mask.
And a bride position adjusting mechanism (21, 41, 55) for adjusting at least one of the positions.

According to a sixth aspect of the present invention, in the exposure method for exposing a pattern of a plurality of masks (24, 44) on a substrate (51), a step of adjusting a relative position of the plurality of masks is provided. Irradiating the masks substantially simultaneously. The exposure method according to claim 7 includes a step of adjusting a position of at least one of the plurality of masks according to a change in the shape of the substrate (51). According to the present invention, it is possible to adjust the interval between a plurality of projection optical systems while keeping the alignment of the projection optical systems rough.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view showing an example of an exposure apparatus according to the present invention. This exposure apparatus includes two projection optical systems 10 and 30. Each projection optical system 10, 3
Reference numeral 0 designates an independent illumination optical system and mask stages 25 and 45 for holding a mask, respectively, and performs pattern exposure on one substrate 51 by two projection optical systems 10 and 30 simultaneously. Although not shown, desired masks are sequentially carried into the mask stages 25 and 45 by a mask changer that holds a plurality of masks, and processed masks are carried out.

First, the exposure by the projection optical system 10 will be described. Illumination light from an ultra-high pressure mercury lamp or a laser light source as an exposure light source 11 is condensed by an elliptical mirror 12 and enters a wavelength selection filter 16 via a shutter 13 that is opened and closed by a shutter driving device 14 and a reflecting mirror 15. . The wavelength selection filter 16 transmits only the wavelength necessary for exposure, and the illumination light transmitted through the wavelength selection filter 16 is converted into a light flux having a uniform illuminance distribution by the fly-eye integrator 17 and reaches the mask blind 20.
The mask blind 20 includes a mask blind driving device 21.
Has the function of adjusting the illumination range on the mask by the illumination light by changing the size of the opening. Further, a part of the light beam emitted from the fly-eye integrator 17 is reflected by the half mirror 18 and enters the integrated exposure meter 19.

The illumination light transmitted through the opening of the mask blind 20 is reflected by a reflecting mirror 22 and enters a lens system 23.
The lens system 23 forms an image of the opening of the mask blind 20 on the mask 24, and illuminates a desired area of the mask 24. The image of the pattern present in the illumination range of the mask 24 is formed on the substrate 51 such as a wafer or a rectangular glass plate by the projection optical system 10, and the pattern image of the mask 24 is exposed on a specific region on the substrate 51. You. Note that a semiconductor circuit pattern or a liquid crystal element pattern is formed on the mask 24.

The pattern exposure by the projection optical system 30 is performed in the same manner as the pattern exposure by the projection optical system 10. That is, the illumination light from the ultra-high pressure mercury lamp 31 or the laser light source as the exposure light source is condensed by the elliptical mirror 32 and the shutter 3 is controlled to be opened and closed by the shutter driving device 34
3. The light enters the wavelength selection filter 36 via the reflecting mirror 35. The wavelength selection filter 36 transmits only the wavelength necessary for exposure, and the illumination light transmitted through the wavelength selection filter 36 is converted into a light flux having a uniform illuminance distribution by the fly-eye integrator 37 and reaches the mask blind 40. The mask blind 40 has a function of changing the size of the opening by the mask blind driving device 41 and changing the size of the opening to adjust the illumination range on the mask by the illumination light. Further, a part of the light beam emitted from the fly-eye integrator 37 is reflected by the half mirror 38 and enters the integrated exposure meter 39.

The illumination light transmitted through the opening of the mask blind 40 is reflected by a reflecting mirror 42 and enters a lens system 43.
The lens system 43 forms an image of the opening of the mask blind 40 on the mask 44, and illuminates a desired area of the mask 44. The image of the pattern existing in the illumination range of the mask 44 is formed on the substrate 51 such as a wafer or a glass plate by the projection optical system 30, and a specific area on the substrate 51 is exposed to the image of the pattern of the mask 44.

The substrate 51 is fixed on the substrate stage 50. The substrate stage 50 has a well-known structure in which a pair of blocks movable in directions orthogonal to each other are overlapped, and is driven by a substrate stage driving device 54. A movable mirror 52 is fixed to the substrate stage 50, and the position of the substrate stage 50 is monitored by detecting the distance between the movable stage 52 and the laser interferometer 53.

The outputs of the integrated exposure meters 19 and 39 and the output of the laser interferometer 53 are input to the main control system 55, and the shutter driving devices 14 and 34 and the mask blind driving device 2
1, 41, the substrate stage driving device 54 includes a main control system 55
The shutter 13, the mask blinds 20 and 40, the substrate stage 50, and the like are driven in response to the driving signal from the controller 13. The main control system 55 controls the shutter driving device 14 based on information from the integrated exposure meter 19, and controls the exposure amount by the projection optical system 10 by controlling the opening and closing time of the shutter 13.

The position of the mask 24 can be detected by mask alignment systems 27 and 28, and the position of the mask 24 with respect to the projection optical system 10 can be adjusted by driving the mask stage driving device 26. Similarly, the position of the mask 44 is determined by the mask alignment systems 47 and 4.
The position of the mask 44 with respect to the projection optical system 30 can be adjusted by driving the mask stage driving device 46. The mask stage driving devices 26 and 46 drive the mask stages 25 and 45 in response to the control designation of the main control system 55.

A reference mark member F for positioning the projection optical systems 10 and 30 is provided on the substrate stage 50.
M1 and FM2 are provided. Although the exposure apparatus shown in FIG. 1 includes two reference mark members FM1 and FM2, the number of reference mark members may be one. However, when there is only one reference mark member, the stroke of the substrate stage at the time of positioning needs to be larger than when using two reference members. Projection optical systems 10, 3
The alignment of 0 will be described later.

Here, the exposure apparatus shown in FIG.
As shown in FIG. 1A, a screen composition for forming a desired pattern by connecting pattern images of a plurality of masks is performed.
An exposure procedure when exposing one device pattern C will be described. First, the mask 241 is positioned and held on the mask stage 25, and the mask 441 is held on the mask stage 45.
Is positioned and held. Then, the shot a1 is exposed on the substrate 51 by the projection optical system 10, and at the same time, the shot b1 is exposed by the projection optical system 30. At this time, the main control system 55 sets the shot a based on the output of the integrated exposure meter 19.
The exposure time control of the shot b1 is performed based on the output of the integrated exposure meter 39 independently of the exposure time control.

Next, after replacing the masks with 242 and 442, respectively, and moving the substrate stage 50 stepwise in the X direction,
A shot a2 is exposed on the substrate 51 by the projection optical system 10, and a shot b2 is simultaneously exposed by the projection optical system 30. Thereafter, similarly, the masks 24 and 44 are exchanged and the substrate stage 50 is step-moved, and the shots (a3, b3),.
2, b12) are sequentially exposed. Thus, the pattern C is exposed by the screen synthesis.

At this time, it is desired that the shots a9 by the projection optical system 10 and the shots b1 by the projection optical system 30, the shots a10 and b2, the shots a11 and b3, and the shots a12 and b4 are not screen-joined with high precision. Accuracy pattern cannot be obtained. For that purpose, the projection optical system 10 and the projection optical system 30 need to be accurately aligned.

Further, as shown in FIG.
In step and repeat mode (d1, h1),
(D2, h2), (e1, i1), (e2, i2), ‥
Expose the shots one set at a time as
Exposure procedures for cases where multiple E, F, G, and
This is the same as in the case of FIG. Devices D, E, F,
G, パ タ ー ン pattern exposure is handled by the projection optical system 10,
The pattern exposure of the devices H, I, J, K, and。 is performed by the projection optical system 30.

In this case, it is not necessary to screen-join the shot by the projection optical system 10 and the shot by the projection optical system 30. However, when a plurality of layers of each of the devices D, E, F, G, and す る are similarly exposed by a plurality of projection optical systems using different exposure apparatuses, each of the exposure apparatuses includes a pattern of the device D and a pattern of the device H. , Device E and device I
Must be aligned and exposed at the same time, it is necessary that the projection optical system 10 and the projection optical system 30 of the exposure apparatus be similarly accurately aligned.

Next, a method for aligning the projection optical system 10 and the projection optical system 30 will be described. Due to the configuration of the exposure apparatus, the mask alignment systems 27, 28; 47, 48 for detecting alignment marks formed on the mask are generally formed on members holding the projection optical systems 10, 30. Therefore, the position error of the projection optical system which occurs at the stage of manufacturing the apparatus is directly changed to the mask alignment systems 27 and 2.
8; a position error of 47, 48 is obtained. In the present invention, the position error of the projection optical systems 10 and 30 is corrected by mask alignment.

Here, the light emitting slits of the reference members FM1 and FM2 provided on the substrate stage 50 and the mask 24,
An image slit sensor signal obtained by detecting the alignment mark formed on the mask 44 with the mask alignment system 27, 28, 47, 48 is synchronized with the output of the laser interferometer 53 of the substrate stage 50 (substrate stage position signal). Then, the alignment mark positions of the masks 24 and 44 are determined based on the stage interferometer. The main control system 55 effectively instructs the projection optical systems 10 and 30 by instructing the mask stage driving devices 26 and 46 to drive the mask stages 25 and 45 so that the masks 24 and 44 have a specified positional relationship. Perform position adjustment.

FIG. 3 is an enlarged sectional view of the substrate stage 50 for explaining an example of the reference mark members FM1 and FM2.
The reference mark member is illuminated from below to form a light emitting slit image at a height position corresponding to the surface of the substrate 51.
This light emission slit image is detected by the mask alignment systems 27 and 28 via the projection optical system 10.

The substrate stage 50 is provided with a hole 60 in the vertical direction from the surface of the stage, in which a reference plate 61 provided with a reference mark and a relay lens system 62 and a reference plate 61 provided with a slit are provided. Is provided from below. The relay lens system 62 has an aperture 63 inside. The illumination light source used in the illumination system may be a light source 65 that generates illumination light having the same wavelength as the exposure light, or a light source 6 that generates illumination light having a different wavelength from the exposure light.
6 is acceptable. Further, both light sources 65 and 66 may be provided as shown in the figure, and either light source may be selected and used by the light source switching device 67. Illumination light from the illumination light source is transmitted, for example, by the optical fiber bundle 68 to the reference plate 61.
And uniformly illuminates the reference plate 61 via the illumination optical system 69.

The light transmitted through the reference mark (slit) formed on the reference plate 61 is formed by the relay lens system 62 as a spatial image at a position 64 substantially coincident with the surface of the substrate 51 placed on the substrate stage 50. Imaged. The mask alignment systems 27 and 28 detect the aerial image of the reference mark via the projection optical system 10. The relay lens system 62
The color is achromatized between the exposure light and the alignment light. When light having a different wavelength from the exposure light is used as the illumination light source, it is necessary to arrange a correction optical system in the optical path of the mask alignment system.

The fiducial mark member is not limited to the type that forms an aerial image as described above, and a member having a light emitting slit formed on the surface thereof from below is provided so as to be movable up and down with respect to the surface of the substrate stage 50. It can also be. In this case, when the reference mark member is used, the reference mark member is raised so that the light emitting slit is located at a height corresponding to the surface position of the substrate, and the reference mark member is not obstructed when mounting the substrate. Is lowered into the substrate stage and stored.

FIG. 4 shows the exposure fields 10F and 30F of the two projection optical systems 10 and 30, and the mask alignment systems 27 and 2.
8, 47, 48 observation fields 27F, 28F, 47F, 4
8F is a diagram schematically illustrating an example of a positional relationship between two reference members FM1 and FM2 provided on the substrate stage 50 and 8F. In this example, as shown in the figure, when the mask alignment system 27 observes the reference mark FM1 via the projection optical system 10, the mask alignment system 48 observes the other reference mark FM2 via the projection optical system 30. Two reference marks FM1 and FM2 are arranged so as to be able to. The reference mark FM1 is responsible for the mask alignment systems 27 and 28 of the projection optical system 10, and the reference mark FM2 is responsible for the mask alignment systems 47 and 48 of the projection optical system 30.

For example, in the state shown in FIG. 4, the reference mark FM1 is detected by the mask alignment system 27 and the reference mark FM2 is detected by the mask alignment system 48 at the same time. Next, the substrate stage 50 is
The mask alignment system 2 is moved by a distance L1 in the X direction.
8, the reference mark FM1 is detected. Subsequently, FIG.
Then, the substrate stage 50 is moved by the distance L2 in the + X direction from the state described above, and the mask alignment system 48 detects the reference mark FM1. If it is assumed that L1 <L2, the mask alignment system 47 can detect the reference mark FM2 on the way.

Since the two mask positions obtained by this method are based on the coordinates of one substrate stage interferometer, the relative positions of the two can be known. According to this result, at least one of the mask alignment systems 27, 28;
8 and the correction of the target positions of the mask blinds 20 and 40, the two projection optical systems 10 and
The alignment of 30 is completed. Mask alignment system 2
7, 28; 47, 48 are corrected by using a method using a movable harbing glass for the mask alignment system, or by separately measuring the positions of the mask stages 25 and 45 such as an interference system. A method of driving the correction amount by the stage driving devices 26 and 46 may be used.

The stroke of the substrate stage 50 required for this operation is a distance L1 in the -X direction and a distance L2 in the + X direction. On the other hand, when the reference mark provided on the substrate stage 50 is, for example, only FM1, two masks 2
The stroke of the substrate stage 50 required to map the positions of the alignment marks formed at the positions 4, 44 to one substrate stage interferometer coordinate is the distance L1 in the −X direction and the distance L1 + L2 in the + X direction from the state of FIG. Becomes

The masks 24 and 44 are provided with a light-shielding band having a predetermined width outside the pattern forming region. The mask blinds 20 and 40 perform their functions if the opening edge images of the mask blinds 20 and 40 formed on the mask are within this light-shielding band. Therefore, the mask blinds are controlled roughly. Is also good. When the movement amount of the masks 24 and 44 is small, after the mask position is driven for correction,
In some cases, the driving of the mask blinds 20 and 40 can be performed without performing. In the example shown in FIG. 1, the exposure light sources 11 and 3 are individually applied to the two projection optical systems 10 and 30.
1 was provided. However, it is also possible to use a common light source unit by adopting a configuration in which a light beam is split by an optical fiber bundle, for example. In this case, since there is no difference in light amount between the light source units, the exposure amount can be easily controlled.

When exposing the second and subsequent pattern layers, the substrate may expand and contract due to the post-exposure process. In this case, the magnification of the two projection optical systems 10 and 30 is adjusted according to the expansion and contraction of the substrate, and the alignment marks provided on the substrate 51 are replaced with the mask alignment systems 27 and 28 instead of the reference marks FM1 and FM2. , 4
By adjusting the positions (intervals) of the two masks 24 and 44 by detecting them with the reference numerals 7 and 48, pattern exposure can be performed by realizing high-accuracy superposition.

As the exposure apparatus of this embodiment, a step-and-repeat type exposure apparatus that exposes the mask pattern while the masks 24 and 44 and the substrate 51 are stationary and sequentially moves the substrate 51 stepwise is used. Although described in the example, the present invention can be applied to a scanning type exposure apparatus that exposes a mask pattern by synchronously moving a mask and a substrate.

The light sources 65 and 66 are also g-line (436n).
m), i-line (365 nm), KrF excimer laser (2
48 nm), ArF excimer laser (193 nm), F
Not only _two lasers (157 nm) but also charged particle beams such as X-rays and electron beams can be used. For example, when an electron beam is used, a thermionic emission type lanthanum hexaborite (LaB ₆ ) or tantalum (Ta) can be used as an electron gun.

The magnification of the projection optical systems 10 and 30 may be not only a reduction system but also any one of an equal magnification and an enlargement system. Further, as the projection optical systems 10 and 30, when excimer laser is used, quartz or fluorite is used as a glass material, and when X-rays are used, a catadioptric optical system is used. If an electron beam is used, an electron optical system including an electron lens and a deflector may be used as the optical system. It goes without saying that the optical path through which the electron beam passes is in a vacuum state. Further, the present invention provides a projection optical system 1.
The masks 24, 44 and the substrate 51 can be used without using 0, 30.
Can be applied to a proximity exposure apparatus that exposes the patterns of the masks 24 and 44 by bringing them into close contact with each other.

[0038]

According to the present invention, exposure using a plurality of masks can be achieved with high accuracy.

[Brief description of the drawings]

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

FIG. 2 is an explanatory view of an exposure method using an exposure apparatus having two projection optical systems.

FIG. 3 is an enlarged sectional view of a substrate stage illustrating an example of a reference mark member.

FIG. 4 is a diagram schematically showing an exposure field of view of a projection optical system, an observation field of view of a mask alignment system, and a positional relationship of a reference member.

[Explanation of symbols]

10.30: Projection optical system, 11, 31: Exposure light source, 1
2, 32 ... elliptical mirror, 13, 33 ... shutter, 14, 3
4 shutter drive device, 15, 35 reflecting mirror, 16,
36: wavelength selection filter, 17, 38: fly-eye integrator, 18, 38: half mirror, 19, 39 ...
Integrated exposure meter, 20, 40 ... mask blind, 21,
41: mask blind driving device, 22, 42: reflecting mirror, 23, 43: lens system, 24, 44: mask, 2
5, 45: mask stage, 26, 46: mask stage driving device, 27, 28, 47, 48: mask alignment system, 50: substrate stage, 51: substrate, 52: moving mirror, 53: laser interferometer, 54: Substrate stage driving device, 60: hole, 61: reference plate, 62: relay lens system,
63 ... stop, 65, 66 ... light source, 67 ... light source switching device, 68 ... optical fiber bundle

Claims (7)

[Claims] An exposure apparatus for exposing at least two mask patterns onto a substrate, comprising: a first detection device for detecting a position of a first mask; and a second detection device for detecting a position of a second mask. A position adjustment device that adjusts at least one of the first mask and the second mask based on detection results of the first detection device and the second detection device; and the first mask. And an illumination optical system for illuminating the second mask substantially simultaneously. 2. The exposure apparatus according to claim 1, wherein a first shutter for controlling an illumination time of the first mask by the illumination optical system, and an illumination time of the second mask by the illumination optical system are set. An exposure apparatus comprising: a second shutter for controlling; and a control device for independently controlling the first shutter and the second shutter. 3. The exposure apparatus according to claim 1, wherein the substrate is placed on a substrate stage, and wherein a first reference device serving as a position reference of the first mask and a position reference of the second mask are provided. An exposure apparatus, wherein a second reference device to be used is disposed on the substrate stage. 4. The exposure apparatus according to claim 1, wherein a light source for illuminating the first mask and a light source for illuminating the second mask are a common light source. 5. The exposure apparatus according to claim 1, wherein the illumination optical system has a first blind that defines an illumination area of the first mask and a second blind that defines an illumination area of the second mask. Adjusting the position of at least one of the first blind and the second blind according to the position adjustment of at least one of the first mask and the second mask. An exposure apparatus, comprising: a bridging position adjusting mechanism. 6. An exposure method for exposing a pattern of a plurality of masks on a substrate, comprising: adjusting a relative position of the plurality of masks; and irradiating the plurality of masks substantially simultaneously. Exposure method. 7. The exposure method according to claim 6, further comprising: adjusting a position of at least one of the plurality of masks according to a change in the shape of the substrate.