JPH0922121A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To precisely measure the position of an XY stage by allowing air whose temperature is adjusted to blow nearly in parallel with the upper surface of the XY stage to optical paths for measuring length in directions X and Y from an oblique direction. SOLUTION: A wafer 3 is placed and a reflection mirror 12 measuring length in a direction X and a reflection mirror 14 measuring length in a direction Y are stuck on the upper surface of the XY stage 5. An air conditioner 17 is set obliquely to the directions X and Y, respectively. Air flow blowing from the air conditioner IT to the XY stage 5 forms various passages. Namely, the air flow passes through a gap between the reflection mirrors 12 and 14 or it hits against the side surface of the stage 5 to cross the optical path 11' or the optical path 13' or it directly crosses the optical path 11' or the optical path 13', which occurs frequently. In any case, the flow of the air is smooth and turbulence is hardly caused. Therefore, the fluctuation of the air and irregular temperature are hardly caused, and the adverse influence such as the irregular refractive index in the air around the XY stage is eliminated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to air conditioning around an XY stage of an exposure apparatus for semiconductor manufacturing.

[0002]

2. Description of the Related Art As the integration of ICs increases, it is necessary to position the XY stage on which a wafer is placed with extremely high accuracy. For this reason, the conventional exposure apparatus is used by being placed in a chamber in which the temperature is constant and adjusted in temperature, or by providing an air conditioner around the XY stage and blowing in temperature-controlled air. It was used by partially controlling the temperature.

The structure of the main part of a conventional exposure apparatus having such an air conditioner will be described with reference to FIG. The exposure apparatus includes an illumination system 1, a mask 2, a projection optical system 4 for projecting a pattern of the mask 2 onto a wafer 3, an XY stage 5 on which the wafer 3 is placed, and an X for driving the XY stage 5 in the X direction.
Direction driving motor 6 and X direction feed screw 7, Y direction driving motor 8 for driving in the Y direction and Y direction feed screw 9, laser interferometer light source 10, X direction for measuring the X direction position of XY stage 5. Interferometer 11 and X-direction length measuring reflecting mirror 12, as well as Y-direction interferometer 1 for Y-direction position measurement
3 and a Y-direction length measuring reflecting mirror 14, an X-direction air conditioner 15, a Y-direction air conditioner 16, and the like. In the apparatus of FIG. 3, the light emitted from the laser interferometer light source 10 is split into two and introduced into the X-direction interferometer 11 and the Y-direction interferometer 13, and the X-direction length measurement is fixed to the XY stage. Is reflected by the reflection mirror 12 and the Y-direction length measurement reflection mirror 14,
Measurements in the XY directions are made. After the wafer 3 is positioned based on this position measurement result, the pattern of the mask 2 is projected onto the wafer 3.

As shown in the arrangement of FIG. 3, the X-direction air conditioner 15 is located behind the X-direction interferometer 11, and the direction of the air flow from the X-direction air conditioner 15 is substantially parallel to the X-direction of the XY stage 5. The directional air conditioner 16 is behind the Y-direction interferometer 13, and the direction of the air flow from the Y-direction air conditioner 16 is XY.
It is almost parallel to the Y direction of the stage 5.

[0005]

However, this type of exposure apparatus has various heat sources such as an XY stage drive motor and a laser light source, and is placed in a chamber as in the first conventional example described above. However, partial temperature unevenness occurs.

Further, as in the second conventional example shown in FIG. 3, in the method in which temperature-controlled air is blown in parallel to the X and Y directions, this air flow hits the XY stage and the reflecting mirror and becomes a turbulent flow. Fluctuation and temperature unevenness occur. If such air fluctuations and temperature unevenness occur on the laser length measurement optical path, this may cause a position measurement error of the XY stage.
Furthermore, if dust generated around the XY stage floats in the air for a long time due to the vortex of air, the cleanliness of the substrate (wafer) to be exposed deteriorates.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a stage movable in orthogonal XY axes,
In an exposure apparatus having a laser interferometer for measuring the position of the stage in the X and Y directions,
There is an air conditioning unit for blowing air, which is kept at a constant temperature, toward the stage from an oblique direction to the direction and substantially parallel to the upper surface of the stage.

[0008]

According to the present invention, when the temperature-controlled air is blown substantially parallel to the upper surface of the XY stage from the oblique direction with respect to both the X-direction and Y-direction length measuring optical paths, the air flow is X-ray.
It flows along the side surface of the Y stage, making it difficult for turbulence to occur. Therefore, fluctuations of air and temperature unevenness due to turbulent flow are almost eliminated, and adverse effects on the laser beam for length measurement, such as unevenness of refractive index in space, can be avoided, and as a result, highly accurate measurement of the XY stage position. Is possible. Further, since dust generated around the XY stage does not float in the air for a long time due to the vortex of air, the cleanliness of the wafer and its periphery is not deteriorated.

[0009]

1 is a perspective view showing a schematic structure of a main part of an exposure apparatus according to an embodiment of the present invention. The basic configuration of the exposure apparatus of the present invention shown in FIG. 1 is the same as that shown in FIG. 3 except for the number and arrangement of air conditioners. In other words, the improvement related to this air conditioning system constitutes the present invention.

In FIG. 1, the exposure apparatus of the present invention comprises an illumination system 1, a mask 2, a projection optical system 4 for projecting the pattern of the mask 2 onto a wafer 3, an XY stage 5 for mounting the wafer 3, and an XY stage 5. X-direction drive motor 6 and X-direction feed screw 7 for driving in the X-direction, Y-direction drive motor 8 and Y-direction feed screw 9 for driving in the Y-direction, laser interferometer light source 10, and X of XY stage 5. From the X-direction interferometer 11 and the X-direction length-measuring reflecting mirror 12 for measuring the directional position, similarly, from the Y-direction interferometer 13, the Y-direction length-measuring reflecting mirror 14 and the air conditioner 17 for measuring the Y-direction position. Composed. Further, in the length measurement system for measuring the position of the XY stage 5, the light emitted from the laser interferometer light source 10 is
The X-direction interferometer 11 and the Y-direction interferometer 13 are branched into two.
X, which have been introduced into the
The light is reflected by the direction-measuring reflection mirror 12 and the Y-direction length-measuring reflection mirror 14, and measurement is performed in the XY directions. After the wafer 3 is positioned based on this position measurement result, the pattern of the mask 2 is projected onto the wafer 3.

Regarding the air conditioning, as shown in FIG. 1, the air conditioner 17 is arranged so as to be inclined with respect to the X and Y directions of the XY stage 5, respectively. With this arrangement, the airflow blown from the air conditioner 17 toward the XY stage 5 flows along the side surface of the XY stage 5 or the upper surface of the XY stage 5, so that turbulence is less likely to occur. Become

The flow of this air will be described with reference to FIG.
FIG. 2 is a plan view showing the periphery of the XY stage 5 of FIG. The wafer 3 is placed on the upper surface of the XY stage 5,
The X-direction length measurement reflection mirror 12 and the Y-direction length measurement reflection mirror 14 are fixed to each other. The air conditioner 17 is installed obliquely with respect to the X direction and the Y direction, for example, at an angle of 45 °. The airflow blown out from the air conditioner 17 toward the XY stage 5 is schematically shown by a line with an arrow in the drawing.
Although this air flow forms various flow paths, it passes through a gap between the X-direction length measurement reflection mirror 12 and the Y-direction length measurement reflection mirror 14 or hits the side surface of the XY stage 5 to reach the optical path 11 ′ or the optical path 13. It is often the case that either the optical path 11 'is crossed or the optical path 11' or the optical path 13 'is directly crossed. In any case,
The air flow is smooth and turbulence is less likely to occur.
Therefore, fluctuations in air and temperature variations are almost eliminated,
Space around XY stage, especially optical path 11 ', optical path 13'
Since adverse effects such as unevenness of the refractive index in
Highly accurate measurement of stage position is possible. Furthermore, XY
Since the dust generated around the stage does not float in the air for a long time, the cleanliness of the wafer 3 and its periphery does not deteriorate.

The air blowing direction from the air conditioner 17 is not necessarily limited to 45 ° with respect to the X direction and the Y direction, and the angle may be changed within a range that does not adversely affect the measurement accuracy. Also, the number of air conditioners is not limited to one, but X
Since the Y stage has four diagonal directions, up to several Y stages may be arranged.

[0014]

As described above, according to the present invention,
Air-conditioning means is provided to blow the temperature-controlled air into the X-direction and Y-direction length-measuring optical paths obliquely in parallel to the upper surface of the XY stage, so that the air flow is smooth along the side surface of the XY stage. Turbulence is less likely to occur. Therefore, fluctuations in air and temperature unevenness are almost eliminated, and it is possible to avoid a space around the XY stage, especially unevenness in the refractive index on the length measurement optical path. As a result, it is possible to measure the XY stage position with high accuracy. Furthermore, since air is hardly retained, dust generated around the XY stage does not float in the air for a long time, so that the cleanliness of the wafer and its periphery is improved.

Further, since the air conditioner is installed obliquely with respect to the XY stage, the air conditioner can be arranged inside the length measuring optical path (close to the XY stage), which contributes to downsizing of the exposure apparatus.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of a main part of an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing an air flow around the XY stage of the exposure apparatus according to the embodiment of the present invention.

FIG. 3 is a perspective view showing a schematic configuration of a main part of a conventional exposure apparatus.

[Explanation of symbols]

 1 ... Illumination system 2 ... Mask 3 ... Wafer 4 ... Projection optical system 5 ... XY stage 6, 8 ... Drive motor 7, 9 ... Feed screw 10 ... Laser Interferometer light source 11, 13 ... Interferometer 11 ', 13' ... Length measuring optical path (optical path) 12, 14 ... Length measuring reflecting mirror 15, 16, 17 ... Air conditioner

Claims (1)

[Claims] 1. A stage movable along orthogonal XY axes, a first laser interferometer for measuring the position of the stage in the X direction, and a second laser interferometer for measuring the position of the stage in the Y direction. And an air conditioner for blowing air maintained at a constant temperature toward the stage from an oblique direction with respect to the X direction and the Y direction and substantially parallel to the upper surface of the stage. An exposure apparatus characterized by the above.