JPH056850A - Exposure equipment - Google Patents

Abstract

(57) [Summary] [Object] To reduce the position measurement error due to the temperature rise of the stage in the exposure apparatus and the position measurement error due to the fluctuation of air accompanying the movement of the stage. An exposure apparatus that exposes an object to be exposed placed on a stage while relatively moving it based on position measurement by a laser interferometer, in which a vent hole is provided in a reflecting mirror and the like of the laser interferometer. thing. A ventilation means for sucking or blowing air from the ventilation hole, and a control means for controlling the suction amount or the temperature of the blown air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for projecting and exposing a circuit pattern such as an IC or LSI or a pattern for a liquid crystal display element, and more specifically to measuring the position and distance of a movable body equipped with a laser interferometer. Regarding the device.

[0002]

2. Description of the Related Art Conventionally, this type of exposure apparatus has a structure as shown in FIG. In this device, illumination light from a mercury discharge lamp 62, which serves as a light source, passes through a fly-eye lens 61 that makes the illuminance distribution on a reticle 58 uniform, a dichroic mirror 60 that reflects illumination light having an exposure wavelength, and a condenser lens 59. The reticle 58 is irradiated. Then, a predetermined pattern image on the reticle 58, which is an object to be projected, is transferred via the projection lens 57 to the wafer 54 to be an object to be exposed.
It is projected onto and exposed.

By the way, in this apparatus, the wafer 54 is adsorbed by the chuck 55 and placed on the wafer stage 56, and the wafer 54 is moved together with the wafer stage 56 to change the exposure position on the wafer 54 to perform projection exposure. It employs a so-called step-and-repeat method in which work is repeated.

Therefore, in order to measure the relative position of the wafer 54, the reflecting mirror 53 fixed to the wafer stage 56.
The stage position is measured by the laser interferometer 51 that projects the laser beam 52 whose frequency is stabilized.

By the way, the wafer stage 56 is used for the wafer 5.
Since it is necessary to move 4 over the entire surface, several hundred mm
The moving path length of the interferometer beam 52 varies in the range of several mm to several hundred mm.

[0006]

In the prior art as described above, while the wafer stage 56 itself repeats the stepping operation, it gradually warms up due to the influence of moving friction and the like, and thermal expansion occurs. There is a problem in that the distance between the mirror and the reflecting mirror 53 is changed, and an accurate wafer (stage) position cannot be measured.

There is also a problem that the heat is transmitted to the reflecting mirror 53 on the wafer stage 56 and the reflecting mirror 53 itself is distorted, resulting in a measurement error.

Further, the exposure illumination light warms the wafer 54, and the heat is transmitted from the wafer holder 55 to the wafer stage 56, causing the same phenomenon.

On the other hand, in the measurement by the laser interferometer 51, the influence of air fluctuation in the light transmission path of the beam 52 has been present, but the movement of the wafer stage 56 causes the air on the light path of the beam 52 to be disturbed. However, there is a problem that this fluctuation or a measurement error due to it becomes large.

The present invention has been made in view of such conventional problems, and an object thereof is to reduce the influence of heat generation of the wafer stage and to reduce the occurrence of measurement errors due to air fluctuations.

[0011]

In order to achieve the above object, in the invention according to claim 1 of the present application, an image of an object to be projected through a projection optical system is projected onto an object to be exposed mounted on a stage. Together with an exposure apparatus that exposes the exposed body while relatively moving the exposed body in a direction perpendicular to the optical axis based on position measurement by a laser interferometer, the stage for measuring the relative position of the exposed body With a laser interferometer reflector,
Vents are provided in this reflecting mirror or its support.

Further, in the invention according to claim 2 of the present application, the opening direction of the ventilation hole is arranged so as to coincide with the measurement optical axis direction of the laser interferometer.

Further, in the invention according to claim 3 of the present application, the vent hole is provided in the second stage in advance.
It is connected to the ventilation holes.

On the other hand, in the invention according to claim 4 of the present application, a ventilation means for sucking or blowing air from the ventilation hole is provided.

In addition, in the invention according to claim 5 of the present application, the ventilation means is provided with a control means for performing control for varying the suction amount or the blowing amount depending on the stage position and the moving distance in the suction or blowing action.

Further, in the invention according to claim 6 of the present application, the ventilation means includes a temperature varying means for changing the temperature of the air to be blown.

[0017]

[Operation] Since the invention according to the present application is configured as described above, it has the following effects. That is, the invention according to claim 1 of the present application secures a sufficient heat radiation area by providing a ventilation hole in the reflecting mirror or its supporting portion, and reduces the temperature rise thereof.

Further, in the invention according to claim 2 of the present application, since the opening direction of the ventilation hole is aligned with the measurement optical axis direction of the laser interferometer, the movement of the reflecting mirror (stage)
By letting air in the measurement optical axis direction escape through the ventilation hole,
The occurrence of air fluctuations on the optical path of measurement light is reduced.

According to the third aspect of the present invention, the second vent hole is provided in the stage and the vent hole is connected to the second vent hole to secure the heat dissipation area of the stage itself.

On the other hand, in the invention according to claim 4 of the present application, by providing the ventilation means, the heat radiation effect of the ventilation hole is improved. Further, in response to the turbulence of the air due to the movement of the reflecting mirror, the ventilation hole itself of the reflecting mirror performs suction or blowing operation, thereby further reducing the fluctuation of air on the optical path of the measurement light.

Here, in the invention according to claim 5 of the present application, since the control means for controlling the amount of suction or the amount of blown air in accordance with the stage position and the moving distance in the above-mentioned suction or blowing operation is provided, the reflecting mirror is provided. In addition, since the ventilation is performed with an appropriate amount of air with respect to the difference in the influence of the turbulence of the air according to the change in the moving state of the stage, it is always possible to prevent the appropriate fluctuation of the air.

Further, in the invention according to the sixth aspect of the present invention, since the temperature varying means for changing the temperature of the air to be blown is provided, they are effectively corrected for the temperature change of the reflecting mirror or the stage. That is, with respect to the temperature rise, by ventilating the cool air, the temperature rise of the reflecting mirror and the like can be suppressed appropriately.

On the other hand, if the temperature of the ventilated air changes with the temperature change of the reflecting mirror or the like, air having a temperature different from that of the outside air is discharged onto the measurement optical path, and as a result, fluctuations due to the temperature distribution of the air may occur. . In the present invention, the temperature of the air discharged from the ventilation hole can be kept constant by the temperature varying means, so that the fluctuation of the air due to the temperature change of the air on the measurement optical path is prevented.

[0024]

The present invention will be described in more detail with reference to the following examples. FIG. 2 shows an exposure apparatus according to the first embodiment of the present invention. Illumination light emitted from a lamp house 12 passes through a fly-eye lens 11, a dichroic mirror 10 and a condenser lens 9 to illuminate a reticle 8. By this illumination light, an image of a predetermined pattern provided on the reticle 8 is formed on the wafer 4 by the reduction projection lens 7.

The wafer 4 is mounted on the wafer holder 5, and the wafer holder 5 is fixed to the wafer stage 6. Although not shown in FIG. 1, the wafer stage 6 can be moved in the vertical (optical axis) direction, and has two degrees of freedom in the Y direction and the Z direction in the horizontal plane (plane perpendicular to the paper surface). have. Then, a step-and-repeat operation is performed by the wafer stage 6, and the pattern of the reticle 8 is reduced and projected and exposed on the entire surface of the wafer 4.

Here, the reflecting mirror 3 is fixed on the wafer stage 6 for measuring the position of the wafer stage 6, and the position can be obtained in a non-contact manner by the laser beam 2 emitted from the laser interferometer 1. .

The reflecting mirror 3 is provided with a ventilation hole 101 at a position not in contact with the reflecting portion of the laser beam 2, and the opening direction thereof coincides with the optical axis direction of the laser beam 2.

Next, the stage portion of this embodiment will be described in more detail with reference to FIG. As is clear from this figure, in the present embodiment, as an example of the ventilation hole 101, ventilation holes 101a, 101b and 101c are provided in the X-axis reflecting mirror 3a, and Y is also used.
Vent holes 101d, 101e and 101f are arranged in the axial reflecting mirror 3b.

The number, arrangement, size, shape, etc. of these vent holes are determined by the interferometer laser beams 2a (X-axis side), 2
It is determined by the size and position of b (Y-axis side), the sizes of the reflecting mirrors 3a and 3b, and the like. In this embodiment, the above-mentioned ventilation hole 101 is provided below the reflecting portion 30 of the X-axis reflecting mirror 3a.

Further, in the wafer stage 6, the uppermost X stage 6x slides along a VF groove 60a, 60B provided on the lower Y stage 6y via a needle bearing (not shown). Then, the driving lead screw 20
It is moved in the X-axis direction by the motor 22 via. Further, the Y stage 6y is also provided with a V-
It slides on the F guides 61a and 61b. Then, the wafer 4 mounted on the wafer stage 6 is relatively two-dimensionally moved horizontally in the horizontal direction to sequentially move the exposure area SA on the wafer 4 and perform the exposure operation on the entire surface of the wafer 4. . The other driving means, the moving means in the vertical direction, and the like are the same as those in the well-known conventional example, and a description thereof will be omitted.

By the way, when the exposure operation is started in this embodiment, each VF guide section 60 of the wafer stage 6 is started.
The wafer stage 6 is warmed and the temperature rises due to heat generated from a, 60b, a nut screwed with the drive system feed screw 20, and the like. The heat from the X stage 6x to the reflecting mirror 3
When the temperature of the reflecting mirror 3 rises, the surface accuracy of the mirror surface (reflecting portion) 30 deteriorates, causing a measurement error in the laser interferometer 1.

Here, since the reflecting mirror 3 has the vent holes 101, the heat radiation area is significantly expanded as compared with the conventional example, and the temperature rise rate is significantly smaller than that of the conventional example.
Measurement errors due to temperature changes are significantly reduced.

Further, since the ventilation hole 101 is opened along the optical axis of the laser beam 2 of the laser interferometer 1, heat radiation by air passing through the ventilation hole 101 by movement of the wafer stage 6 itself in the X or Y direction. There is also an effect.

On the other hand, the ventilation hole 101 reduces the projected area of the laser beam 2 on the wafer stage 6 in the direction of the optical axis, and further serves as an air ventilation path near the mirror surface (reflecting portion) 30 (the ventilation hole 101. The presence of the opening reduces the turbulence of air near the optical axis due to the movement of the wafer stage 6. For this reason, the measurement error due to the fluctuation of the air accompanying this is reduced.

Next, a second embodiment will be described with reference to FIG. In this embodiment, the vent holes 103 are provided in the wafer stage 306 to reduce the temperature rise of the wafer stage itself. This ventilation hole 103 is
The ventilation holes 101 are connected via a connecting pipe 102, and these ventilation holes 101 and 103 are connected to an intake / blowing unit 201 via a connecting pipe 104.

In this embodiment, the wafer stage 3
Heat is generated by the stepping operation of 06, and the stage 30
6 and the reflection mirror 3 are expected to be deformed, the intake / blower unit 201 is operated to forcibly force the ventilation hole 1
01, 103 to move the air inside the vent holes 101, 1
It is possible to increase the heat radiation effect in 03 and suppress the thermal deformation of the reflecting mirror. Further, in this case, a laminar flow is given to the optical path of the laser beam 2 through the ventilation hole 101, which is effective for slow air fluctuation.

Here, the intake / blower unit 201 can not only change its wind speed and flow rate, but can also control the temperature, so that the effect of suppressing the temperature change can be further enhanced.

On the other hand, the measurement error due to the fluctuation of air in the laser interferometer 1 is also caused by the stepping operation of the wafer stage 306.

In order to prevent this, one example is as follows:
When the wafer stage 306 moves toward the interferometer 1 side, if the air (disturbed air) pushed away by the wafer stage 306 and the reflecting mirror 3 is sucked from the ventilation light 101,
The influence of air turbulence on the optical path of the laser beam 2 is reduced.

Therefore, the influence of air fluctuation can be appropriately reduced by changing the air volume from the intake air blowing unit 201 according to the position of the wafer stage 306 before and after the stepping operation, the stepping speed, the moving amount, and the like. It is possible.

In this embodiment, the ventilation controller 202 is provided,
Speed information Vd from the stage driver circuit 205 that controls the motor 22 of the wafer stage 306,
The position information Pd is received from the interferometer 1, and the wafer stage 3
The amount of heat accumulated in 06, the air flow received by the reflecting mirror 3 and the like are statistically analyzed, and the ventilation flow rate, direction and temperature are changed.

The temperature of the outside air (outside of the device, for example, on the optical path), the inside of the vent hole, the reflecting mirror itself, and the stage itself is measured by an individual temperature sensor (not shown), and each temperature information is measured. Is sent to the ventilation controller 202.

Although the connection pipe 104 is connected to the ventilation hole 101 of the mirror 3 through the ventilation hole 103 in the stage in FIG. 3, the connection pipe 104 may be directly connected to the ventilation hole 101.

Next, a third embodiment will be described with reference to FIG. In this embodiment, the air holes 103a are provided in the wafer holder 405 and the wafer stage 406, and like the second embodiment, the air intake / blowing unit 201.
From a to the ventilation hole 101 installed in the reflecting mirror 3 is connected.

In the present embodiment, the accumulation of heat on the wafer stage 406 by the stepping operation and the exposure operation is
The air intake / blower unit 201a actively tries to hold down the temperature, and also considers the temperature rise of the wafer holder 405 due to the influence of exposure illumination light.

In this embodiment, it is possible to expect a reduction in air fluctuations as in the second embodiment, but there is a possibility that the distance between the wafer 4 and the reflecting mirror 3 may change due to heat, resulting in a measurement error. By using the vent holes 103a to keep the entire temperature constant, a measurement error due to this is less likely to occur.

Therefore, the control unit 202 controls the speed information V
In addition to d and position information Pd, information Ed representing the change characteristic of the amount of thermal energy accumulated in the stage is also input.
The exposure apparatus may be proximity exposure other than projection exposure.

[0048]

As described above, according to the present invention, it is possible to significantly reduce the position measurement error such as the high speed movement of the stage and the deformation of the reflecting mirror and the expansion of the stage caused by the heat due to the exposure operation. Becomes

Further, there is an advantage that the problem of air fluctuation in the measurement system using the laser interferometer can be solved at the same time.

Further, the present invention can be used in the same manner in a processing device or a measuring device in which a reflecting mirror for an interferometer is fixed to a movable body to measure position and distance. Therefore, the applicable range of the present invention is not limited to the exposure apparatus.

[Brief description of drawings]

FIG. 1 is a perspective view showing a peripheral portion of a wafer stage of an exposure apparatus according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the configuration of the exposure apparatus according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a configuration around a wafer stage of an exposure apparatus according to a second embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a configuration around a wafer stage of an exposure apparatus according to a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a configuration of a conventional exposure apparatus.

[Explanation of symbols]

1 ... Laser interferometer, 2 ... Laser beam, 3, 3a, 3b
... Reflector, 4 ... Wafer, 5 ... Wafer holder, 6, 30
6,406 ... Wafer stage, 101, 101a to 10
1f ... Vent hole, 103, 103a ... Vent hole (inside wafer stage), 201 ... Intake / blower unit

Claims (6)

[Claims] 1. An image of an object to be projected via a projection optical system is projected onto an object to be exposed mounted on a stage, and the object to be exposed is set as an optical axis based on position measurement by a laser interferometer. An exposure apparatus that performs relative movement in a vertical direction to perform exposure, wherein the stage has a reflecting mirror of a laser interferometer for measuring the relative position of the exposed object, and the reflecting mirror or a supporting portion thereof is provided. An exposure apparatus having a vent hole. 2. The exposure apparatus according to claim 1, wherein the ventilation hole is arranged so that an opening direction thereof coincides with a measurement optical axis direction of the laser interferometer. 3. The exposure apparatus according to claim 1, wherein the ventilation hole is connected to a second ventilation hole installed in advance in the stage. 4. The exposure apparatus according to claim 1, further comprising a ventilation means for sucking or blowing air from the ventilation hole. 5. The exposure apparatus according to claim 4, wherein the ventilating means is provided with a control means for performing control for varying the suction amount or the blowing amount depending on the stage position and the moving distance in the suction or blowing action. . 6. The exposure apparatus according to claim 4, wherein the ventilation unit includes a temperature changing unit that changes the temperature of the blown air.