JPH01165116A - Exposure device - Google Patents

Abstract

PURPOSE:To illuminate a mask pattern in an exposure system in a constant state even through certain positional displacement because of vibrations and the like takes place in the exposure system, by providing separately an illuminating system which illuminates the mask pattern and the exposure system which projects and exposes the mask pattern on the wafer image plane, and providing a correction optical system which corrects positional displacement to the illumination system in a part of the exposure system. CONSTITUTION:Assume that vibrations and the like cause an exposure system 104 to rotate only by an angle theta around a central axis y relative to an illumination system 101. After a beam flux from the illumination system 101 is reflected by a mirror 106 at angles 2theta to impinge on a beam expander 109. The beam flux on the optical axis 102 of the illumination system 101 is reflected by the mirror 106 at the angles 2theta with respect to a vertical plane. The beam flux which is reflected with a slant is corrected by the angle theta by passing through the beam expander 109 and as a result, the axis of the beam coincides with the optical axis of an illumination lens 100.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to an exposure apparatus, and in particular, in the production of integrated circuits such as ICs and LSIs, a pattern on a mask or reticle surface is projected and exposed onto a wafer surface using a projection optical system. The present invention relates to an exposure apparatus suitable for use in the exposure process.

(Prior Art) Generally, in a so-called exposure apparatus for manufacturing integrated circuits such as ICs and LSIs, a mask pattern depicting an electronic circuit pattern is illuminated by an illumination system, and the mask pattern is transferred onto a wafer surface by an exposure system. Projected and exposed.

Light sources for lighting include ultra-high pressure mercury lamps, halogen lamps,
Lasers and the like are often used. In order to obtain high throughput, the illumination light source used in the exposure equipment must have a high enough output to provide sufficient illumination on the surface of the sea urchin, and the projection optical system that makes up the exposure system must have sufficient optical performance. There is a demand for emitting a luminous flux with as narrow a spectral width as possible.

A projection optical system usually has aberrations well corrected in a narrow wavelength range. For this reason, conventionally, in many cases, an interference filter that passes only a narrow wavelength range is disposed in a part of the illumination system to limit the spectral width of the light beam from the light source.

As described above, since the conventional exposure apparatus uses an interference filter or the like to limit the wavelength range of the light beam, there is a tendency for the intensity of the light beam to decrease.

An example of a light source that generally emits a light beam with high output and a narrow wavelength range is an excimer laser 1. By narrowing the band, this excimer laser can emit a light beam in an extremely narrow wavelength range.

However, since excimer lasers are generally extremely large and heavy, placing them in an exposure apparatus increases the size of the entire apparatus. For this reason, various exposure apparatuses have heretofore been proposed in which an illumination system and an exposure system are configured separately and independently.

When the illumination system and exposure system are configured separately, it is necessary to make the light beam from the illumination system's light source enter the light beam inlet of the exposure system under the same conditions and with high precision in order to uniformly illuminate the mask pattern. There is.

Generally, the exposure system includes a movable X-Y stage for step-and-repeat, for example, approximately 30 x 30 cm in size and approximately 20 kg in weight, and an autofocus mechanism that automatically performs focusing between the mask pattern and the wafer. It incorporates moving members, etc. In order to repeatedly perform focusing and exposure, movable members are constantly moving within the exposure system. For this reason, the exposure system constantly vibrates, albeit slightly.

Therefore, it becomes very difficult to make the light beam from the light source of the illumination system, which is provided separately from the exposure system, enter the exposure system at a predetermined position with high precision.

In particular, when an angular deviation occurs between the optical axis of the illumination system and the optical axis of the exposure system due to vibration, for example, as shown in FIG. It no longer matches. This makes it difficult to properly illuminate the upper part of the mask pattern surface, leading to errors such as changes in line width when projecting and exposing the mask pattern onto the wafer surface, resulting in an increase in the defective rate during the manufacture of integrated circuits. come.

(Problems to be Solved by the Invention) When the illumination system and the exposure system are configured separately, the present invention provides a gradient that minimizes the influence of vibrations generated within the exposure system, and the luminous flux from the illumination system is An object of the present invention is to provide an exposure apparatus that can always illuminate a mask pattern in a constant state even if the light enters an exposure system in different states.

(Means for solving the problem of unlucky points) An exposure apparatus is provided with an illumination system for illuminating a mask pattern and an exposure system for projecting and exposing the mask pattern onto a wafer surface, the exposure system comprising: A correction optical system for correcting relative positional displacement with respect to the illumination system caused by vibration of the system, etc. is provided such that at least a part of the correction optical system is fixed to a part of the exposure system. be.

(Embodiment) FIG. 1 and FIG. 2 are each a schematic diagram of an embodiment of the present invention. Figure 1 shows the case where the exposure system in the exposure device does not vibrate and is in the normal position relative to the illumination system, and Figure 2 shows the case where the exposure system vibrates and is tilted in one direction with respect to the illumination system. ing.

In the figure, 101 is an illumination system, which has a light source such as an excimer laser. 102 is the optical axis of the illumination system 101, 1
04 is an exposure system. The illumination system 101 and the exposure system +04 constitute one element of an exposure apparatus. Reference numeral 105 denotes an imaging absorbing member, which is attached to the exposure system 104. 106,1
07 and 108 are mirrors each attached to a part of the exposure system 104, and +09 is a beam expander, which has two cylindrical lenses +09a and +09b. The beam expander 109 has an angular magnification of 1/1 in one direction.
It has a refractive power of 2, and has no refractive power in the other direction. In addition, the beam expander 109 is connected to the exposure system 1.
04 or to the illumination system 101, that is, to be in a substantially stationary position relative to the illumination system 101.

In this embodiment, the beam expander 109 and the mirror 10
6 constitutes one element of the correction optical system.

Reference numeral 100 denotes an illumination lens that illuminates a mask pattern (not shown).

Next, the optical function of the correction optical system in this embodiment will be explained.

As shown in FIG. 1, when the exposure system +04 is at the regular reference position with respect to the illumination system 101, the light flux from the illumination system 101 is reflected by a mirror 106 provided in a part of the exposure system 104, and a beam The beam passes through an expander 109 and its diameter is doubled. After being reflected by mirrors 107 and 108, a mask pattern (not shown) is illuminated by an illumination lens 100.

On the other hand, suppose that the exposure system 104 is rotated by an angle θ about the y-axis with respect to the illumination system 101 due to vibration or the like, as shown in FIG. Then, the light flux from the illumination system 101 is a mirror! After being reflected at 06, the beam is reflected at an angle of 2θ and enters a beam expander 109.

FIG. 3 is an explanatory diagram schematically showing the light flux passing through the mirror 106 and the beam expander 109 at this time.

As shown in FIG. 3, the light beam on the optical axis 102 of the illumination system 101 is reflected by the mirror 106 at an angle of 2θ with respect to the vertical plane. (However, it is tilted at an angle θ with respect to the exposure system 104.) The tilted and reflected light flux is corrected by the angle θ by passing through the beam expander 109, and as a result, the illumination lens 00 as shown in FIG. becomes aligned with the optical axis of

That is, the optical axis 102 of the illumination system 101 and the optical axis 111 of the exposure system +04 can be made to coincide with each other.
The light flux can be made to enter the illumination lens 100 in the same state as before the lens 04 is tilted.

In this embodiment, when the correction optical system corrects the relative positional displacement between the illumination system +01 and the exposure system lθ4, a slight positional deviation of the optical axis occurs. So Dome Expander 1
09 is a Galileo type, and it is composed of at least two lenses, etc., so that the mirror 106 and the final lens surface of the beam expander 109 (cylindrical lens 1
09a (lens surface on the mirror 107 side) is made small to minimize positional deviation.

In this embodiment, when the exposure system 104 rotates about the X-axis, the optical axis does not shift even if there is no optical system between the mirrors 106 and 107. Therefore, in this embodiment, the beam expander 109 is constructed from an optical system that does not have refractive power in the X-axis direction.
It may be constructed from a simple spherical lens so as to have refractive power in the X-axis direction.

In this embodiment, by arranging the mirror 106 approximately near the rotation center of the exposure lens 96104, the optical axis deviation (parallel movement) due to the rotational component is minimized.

In this embodiment, the diameter of the beam is changed by passing through the beam expander 109, so if necessary, it may be fixed to the exposure system 104 behind the beam expander 109 or placed on the floor in front of the mirror 106. Fix it to the surface (
(in a relative static positional relationship with the illumination system 101)
A beam expander made of a cylindrical lens may be arranged.

In this embodiment, Z of the exposure system 104 shown in FIG.
Rotation with respect to the axial direction is actually extremely small, so this is dealt with by determining the direction in which the degree of mechanical rotation of the exposure system is small and arranging the entire apparatus.

5-8 show schematic diagrams of other embodiments of the invention.

FIG. 5 is a side view showing the features of the present invention, and FIG. 6 is a view seen from the direction of the arrow in FIG.

Further, FIG. 7 is shown as a drawing showing the details of the present invention, and FIG. 8 is shown as an explanation of the operation.

In FIGS. 5 and 6, 1 is a stepper body which is a wafer holding means, 1a is a reticle, 1b is a reticle holder, IC is a projection optical system for projecting the reticle onto the wafer, 2 is an installation frame, and 3 is a 2 An air spring configured in the frame and supporting the stepper main body 1 at four points; 4 a wafer stage on which a wafer is placed and moved in the x and y directions;
4a is a wafer placed on a wafer stage and held by suction, 5 is an illumination optical system including a lens mirror (not shown), 6 is a mirror serving as a light intake of the illumination optical system, and 7 is a light incidence position of the present invention. The correction mechanism 8a is an excimer laser light source.

The double-dashed line in the middle indicates the state of the device when vibration occurs.
state.

Since stepper body 1 is supported by several air springs 3 as shown in FIGS. 5 and 6, vibrations from the floor are difficult to transmit to stepper body 1. In the case of such a structure, the behavior of the wafer stage 4 causes tilting and tilting vibration of the apparatus in the direction shown in FIG. 9.

In this state, light emitted from a separately placed laser is irradiated toward the device from the direction 8, enters the light intake 6 via the mirror, and is transmitted to the wafer via the illumination optical system 5, reticle 1a, and projection optical system IC. 4a, but if the light is directly incident on the light intake of the illumination system without going through the light incidence correction mechanism of the present invention, the optical axis of the incident light will be shifted by the inclination angle of the stepper 1, and the light will enter the light intake 6. Due to mirror reflection, the light hits the illumination system 5 at an angle twice the inclination angle and is incident obliquely to the optical axis of the internal optical system, causing poor transmission of light within the illumination system.

In the present invention, the light incident on the stepper body 1 is arranged such that the light emitted from the laser enters the stepper body 1 from the direction of the arrow 9 through the light incidence correction mechanism 7, and the parallel movement mechanism 7 and the stepper body 1 Rotating mirror that corrects 1/2 of the angle of incidence deviation due to inclination in the direction of arrow 9, arrow 10
For tilting in the direction, the parallel movement mechanism 7 is swingably supported on an axis passing through the center point of the tilting rotation of the stepper body and extending radially to the axis of the body, so that the stepper body 1 and the By connecting the parallel movement mechanism to the side surface on the incident side of the main body 1 via a slider that can be slid in the i direction, the tilt vibration and vibration in two directions of the stepper main body 1 can be suppressed. Absorbing.

The light incident position correction mechanism will be explained below with reference to FIG. In the figure, 11 is a stand that supports the light incident position correction mechanism of the present invention.
12 is a bearing; 13 is a rotating shaft that engages with the bearing of 12; one end supports a rotating shaft 14a that is orthogonal to the axis; the other end has a fixed shaft 20 that is also orthogonal to the axis of 13. axis 1
The center of rotation of stepper body 1 is arranged so as to substantially coincide with the vibration central axis 13 which is unique to vibration around the X-axis of stepper main body 1 . or,
As shown in FIG. 7, the shaft 13 is bent in order to allow the mirror 14 to be rotatably positioned on this rotation center axis. 14,
16.18 is a mirror and a rotating shaft 14a.

16a and 18a. Reference numerals 15 and 19 are link rods having rotatable bearings at both ends, and the bearing spacing between each rod is the same.

The first frame is a horizontal link rod with rotatable bearings at both ends.
The distance between the bearings is the same as the distance between the rotating shafts 13. 21 is a fixed pulley connected to the shaft 20 fixed to one end of the rotating shaft 13, and 22 is the shaft +4a, 16a, 18 attached to the mirrors 14, 16, and 18 mentioned above.
A rotary pulley is fixed to A, and each related link rod is rotatably fixed between the pulley and the mirror. 2
3 is a belt connecting the fixed pulleys 21 and 22 attached to the shafts at both ends of the link rod 19; 24 is a belt connecting the rotary pulleys 22 attached to the shafts at both ends of the link rod 17; 25 is a belt connecting the shafts at both ends of the link rod 15. 26 is a rotating shaft attached to one end of the link rod 17, 27 is a stator 27a fixed to the stepper main body 1 by a slider mechanism that can move relatively only in two directions, and The slider 27b is movable relative to the rotating shaft 27a.
At 6, the link rod 17 is connected to the link rod 17 via a bottle.

Note that the ratio of the pulley diameters of the fixed pulley 21 and the rotating pulley 22 is 1:2.

The structure from 13 to 19 in the figure is a simple parallel motion link mechanism, and since it is connected to the slider 27 on the main body side by the rotating shaft 26, it moves in the direction of the arrow 9 about the axis A in FIG. This parallel movement link reproduces the inclination as it is at a position away from the rotation center of the stepper body 1, and the position of the mirror 18 is always maintained in relation to the intake port 6 of the illumination system 5 configured in the stepper body 1. is maintained.

Furthermore, since the parallel movement link mechanism is supported by bearings 12 against inclination in the direction of arrow 10 in FIG.
Since the center of inclination coincides with the axis B of the bearing 12, it is linked with the stepper body 1 in the same manner as described above.

One of the four joints of the parallel motion linkage is fixed shaft 2
0, has a fixed pulley 21, and the other joints consist of a rotating shaft and a pulley 21 fixed to it, and all the pulleys are connected by belts 23, 24, and 25, so that the link 19 of the parallel motion link mechanism The inclination (equivalent to the inclination in the direction of arrow 9 in FIG. 5) is interlocked with the mirror axes 14a, 16a, 1.
Rotate 8a. As mentioned above, since the ratio of the fixed pulley 21 to the rotating pulley 22 is 1:2, the mirrors 14, 16, 18 rotate by 1/2 of the inclination angle of the link 19.

This operation will be explained with reference to FIG. FIG. 8 shows how the laser beam incident from the direction of arrow 8 travels based on the behavior of the parallel movement link mechanism shown in FIG. 7 and the relationship between the mirrors 14, 16, and 18 that rotate with the behavior. As mentioned above, since the parallel motion link reproduces the tilting motion and angle of the stepper body 1 at a position away from the center of its behavior,
The link rods 15 and 17 extending in the vertical direction indicate an inclination angle θ from a certain reference plane. Therefore, the laser beam incident from the direction of arrow 8 may be routed along each link rod via mirrors 14, 16, and 18. However, when the mirror is rotated by the same angle as the tilt angle θ of the stepper main body 1, the laser beam incident on each mirror 14, 16, 18 has a reflected light of 2 due to the relationship between the incident light and the reflected light.
Because it exits at an angle of 0 minutes, it can become large.

In the present invention, the relationship between the pulleys 21 and 22 is set at a diameter ratio of 1:2 so that the mirror rotates by 1/2 of the inclination angle θ of the link rods 15 and 17, and when actually purchased, the reflected light is shifted by 0 minutes. Since the light reflected by each mirror is corrected and incident along each link rod 15, 17, 19, the incident position and incident angle are changed in accordance with the inclination of the stepper body 1. The light enters the light intake port 6 of the illumination system 5 without any interference.

By the way, each mirror 14, 16.18 is a belt 24.25
By the action of the rotating pulley 22, the respective reflecting surfaces are set to be parallel to each other.

In the above-mentioned embodiment, the angle of the mirror 20 was adjusted via the pulley in response to mechanical displacement. It is also possible to adjust the angle of the mirror 20 by an angle using an angle actuator that rotationally drives the mirror 20.

Furthermore, in the above-described embodiment, the behavior of the stepper body 1 is considered to be a tilted vibration, but if the device has horizontal vibration, a platform 33a may be provided at the bottom of the air spring 3 as shown in FIG. This is suspended from a support part 33b fixed to the floor with a wire 33c, and the installation base 11 of the parallel motion link mechanism is fixed to the base part 33a that only moves the horizontal vibration of the stepper main body 1, thereby correcting the light incident position. The behavior of the mechanism 7 almost completely matches the behavior of the horizontal vibration of the stepper main body 1 without receiving any resistance from the floor, making it possible to further improve the efficiency of the laser beam circulation.

In this case, the cross-sectional area of the beam is made sufficiently larger than the size of the mirror so that the mirror 14 on which the beam is incident will not be eclipsed due to parallel movement of the mirror with respect to the floor.

Further, although the above embodiment has been explained using a parallel motion link mechanism, there is also a method as shown in FIG. 10 as a means for reproducing the tilting vibration of the stepper body.

In FIG. 10, 28 is a fixed pulley, 29 is a mirror fixed to a rotating pulley 30, 31 is a belt, and 32 is an arm.

As mentioned above, the inclination angle θ of the stepper 1 is transmitted to the rotating pulley 30 via the fixed pulley 28 and the belt 31, and since the pulley ratio has a leap of 1:2, the mirror 29 only has an angle of 072. The rotating laser beam enters from the direction of the arrow 8 and is reflected by the mirror 29 with a deviation from the rotation by an angle θ, which is the same as the inclination of the stepper main body l.

The slider 2 is used to shift the center position of the fixed pulley 28, which is the connecting part, in the vertical direction with respect to the inclination of the stepper main body l.
The absorption at 7a and 7b is the same as in the case of FIG.

Also, in FIG. 9, the center of oscillation is placed on the axis that passes through the center of the inclination vibration of the stepper body 1 in the direction of arrow 10, so the inclination angle of arrow lO is the same as in the case of FIG. It follows and operates.

In the case of FIG. 'f119, the structure is easier and cheaper than that in FIG. 8.

Further, in the above embodiment, rotational vibration around the x and y axes was considered, but if rotational vibration around two axes becomes more problematic, for example, in the first embodiment, the light incidence position correction mechanism shown in FIG. By laying it horizontally, the influence of rotational vibration around the Z-axis can be removed.

(Effects of the Invention) According to the present invention, when the illumination system and the exposure system are configured separately and independently, by providing at least some elements of the correction optical system in a part of the exposure system, the illumination system can be exposed to light. It is possible to achieve an exposure apparatus that can always illuminate a mask pattern within the exposure system with a constant light flux from the illumination system even when the system is displaced due to vibration or the like.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing an exposure apparatus according to an embodiment of the present invention in its normal state and when the exposure system is tilted, respectively; FIG. 3 is an enlarged explanatory diagram of a portion of FIG. 2; FIG. 4 is a schematic diagram of a conventional exposure apparatus, FIG. 5 is a side view of an apparatus embodying the present invention, FIG. 6 is a rear view of an apparatus embodying the present invention, and FIG.
The figure is a detailed view of the light incident position correction mechanism according to the present invention, Figure 8 is an explanatory diagram of the mechanism operation in Figure 'fJ7, Figure 9 is a side view of another embodiment, and Figure 10 is a side view of still another embodiment. It is a diagram. Figure 1 Figure 2 Figure 3 7 Figure 5 UiU Kazu 7 Figure 8 [2] Figure 10 Procedure Netn official text (spontaneous) 1986 Patent Application No. 324326 2, Name of invention Exposure device 3, Make corrections Relationship with the case Patent applicant address 3-30-2 Shimomaruko, Ota-ku, Tokyo Name (+00
) Canon Co., Ltd. Representative Ryuzo Kaku
Part 4. Agent address: 301 Jiyugaoka, Belheim, 2-17-3 Okusawa, Setagaya-ku, Tokyo 158 (Telephone: 718-5614) Name:
(8681) Patent Attorney Yukio Takanashi j; -115, Subject of amendment 6, Contents of amendment (1) As shown in the attached sheet (2) (4) 4th handwritten specification, line 3.5.200 “Lighting system” Each is corrected as a "light source". Delete "Lighting system" in the 10th line of the same page. (0) Line 5 due east 2.9, 11, 16.19 of the specification 71 bu 1 is corrected to 1h (8) Due east 6 of the specification 6.7, 9, 10 .111th line “
"Illumination system" is corrected as "light source". In the 10th line of the same page, "It has a light source." is corrected to "It is a laser." (d) Specification No. 7 Handwriting 1.1-2. to, 11, 18.
"Illumination system" in the 19th and 20th lines is corrected to "light source". (ne) Specification No. 8, handwritten line 6.13.177 “Lighting system”
are corrected as "light sources". Correct “same state” on line 15 of the same page to “same state (same angle of incidence) J.” (f) Correct “illumination system” on line 1 of page 10 of the specification to “light source”
and correct it. (g) "Illumination system" in lines 2, 4, and 6 of the 20th line of the specification are corrected to "light source." 2. Scope of Claims (1) An exposure apparatus separately and independently provided with a light source for illuminating a mask pattern and an exposure system for projecting and exposing the mask pattern onto a wafer surface, the exposure system comprising: A correction optical system for correcting relative positional displacement with respect to the light source caused by vibration etc. is provided such that at least a part of the correction optical system is fixed to the -1 part of the exposure system. exposure equipment. (2) The correction optical system is comprised of a fixed mirror fixed to a part of the exposure system and an optical element having a relative stationary positional relationship with respect to the light source. Exposure apparatus according to item 1. (3) Claims characterized in that the optical element is constituted by a beam expander that has an angular magnification of 172 times in one direction and has no refractive power in the other direction. Exposure apparatus according to item 2. (4) The exposure apparatus according to claim 1, wherein the correction optical system is provided near the center of vibration of the exposure system.

Claims (4)

[Claims] (1) An exposure apparatus that is equipped with an illumination system for illuminating a mask pattern and an exposure system for projecting and exposing the mask pattern onto a wafer surface, and that is equipped with an illumination system for illuminating a mask pattern and an exposure system for projecting and exposing the mask pattern onto a wafer surface. An exposure apparatus characterized in that a correction optical system for correcting a relative positional displacement with respect to an illumination system is provided such that at least a part of the correction optical system is fixed to a part of the exposure system. (2) The correction optical system is composed of a fixed mirror fixed to a part of the exposure system and an optical element having a relative stationary positional relationship with respect to the illumination system. Exposure apparatus according to scope 1. (3) The optical element is constituted by a beam expander having an angular magnification of 1/2 in one direction and having no refractive power in the other direction. Exposure apparatus according to scope 2. (4) The exposure apparatus according to claim 1, wherein the correction optical system is provided near the center of vibration of the exposure system.