JPH10214782A - Aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform temperature control of a photosensitive substrate well by providing a gas jetting means disposed on a stage while surrounding the outer circumferential part of the photosensitive substrate and blowing temperature conditioned gas toward the photosensitive substrate. SOLUTION: A wafer 40 is mounted on a wafer stage 42 while being sucked to a vacuum sucking section. A cylindrical cooling gas duct 52 is disposed on the outside of a wafer holder 50 while surrounding the wafer holder 50. Gas jet ports 54a-54h are made, at a constant interval, on the wafer 40 side of the cooling gas duct 52. The gas jet ports 54a-54h are directed toward the center of the wafer 40 and jet cooling gas uniformly onto the entire surface of the wafer 40. The gas jet ports 54a-54h are coupled with an air supply section through a piping penetrating the cooling gas duct 52 and the wafer stage 42. The air supply section is coupled with a temperature conditioning section, e.g. a cooler, and supplies temperature conditioned air to the gas jet ports 54a-54h through piping. Temperature conditioned air supply and interruption thereof are controlled through a control section.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus for exposing an image of a pattern formed on a mask to a photosensitive substrate mounted on a movable stage.

[0002]

2. Description of the Related Art In an exposure apparatus used for manufacturing a semiconductor device, a liquid crystal display plate, or the like, a mask such as a reticle on which a predetermined pattern is formed is irradiated with light for exposure.
The image of the pattern is transferred to a photosensitive substrate such as a wafer via a projection optical system. Such an exposure apparatus is often housed in an environment-controlled chamber, thereby keeping the periphery of the exposure apparatus clean and at an appropriate temperature. Incidentally, the temperature control in the chamber is generally performed on the entire exposure apparatus and also on the periphery of the photosensitive substrate which is easily affected by heat. As a method for controlling the temperature of the photosensitive substrate, there is a method disclosed in JP-A-6-37172. That is, the temperature of the substrate (wafer) is kept constant by circulating the fluid whose temperature has been adjusted inside the substrate holding unit on which the substrate (wafer) is placed.

However, since the substrate (wafer) is vacuum-sucked by the vacuum suction unit formed in the substrate holding unit, the contact area between the substrate (wafer) and the substrate holding unit is small.
The above method is not always efficient, and it is difficult to perform highly accurate temperature adjustment. That is, since the temperature adjustment of the substrate (wafer) is performed indirectly through the substrate holding unit, it is difficult to exhaust the heat of the substrate (wafer) in a short time. Further, in order to set the temperature of the substrate (wafer) to a certain temperature, it is necessary to control the temperature of the substrate (wafer) based on the temperature of the substrate holding unit and the like. Is likely to occur.

[0004]

Therefore, the influence of heat such as exposure light cannot be completely removed, and the position of the alignment mark formed on the substrate (wafer) is shifted due to expansion and contraction of the substrate (wafer). As a result, there is a problem that the substrate (wafer) cannot be aligned with high accuracy. SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide an exposure apparatus capable of favorably controlling the temperature of a photosensitive substrate.

[0005]

In order to solve the above problems, an exposure apparatus according to the present invention is arranged on a stage (42) so as to surround an outer peripheral portion of a photosensitive substrate (40).
Gas blowing means (52, 54a to 54h, 56, 58, 60) for blowing a gas whose temperature has been adjusted to 0) is provided. As the gas ejection means, gas is supplied to the photosensitive substrate (4
0) to a plurality of jets (54a-
54h).

[0006] More preferably, there is provided control means (62) for controlling the gas ejection means between an operating state and a non-operating state.
For example, the control means (62) controls the gas ejection means (52, 54a to 54a) at least when exposure is being performed.
h, 56, 58, 60).

[0007]

When the exposure operation is performed in the present invention having the above configuration, the photosensitive substrate (40) is placed on the stage (42), and the alignment operation of the photosensitive substrate (40) is performed. Thereafter, the mask (36) is irradiated with light for exposure, and the image of the pattern of the mask (36) is transferred onto the photosensitive substrate (40). During such an exposure operation, a gas whose temperature has been adjusted is blown to the surface of the photosensitive substrate (40) to keep the temperature of the photosensitive substrate (40) constant. In the present invention, the gas ejection means (52, 54a to 54h, 56,
58, 60) on the stage (42), the gas ejection means (52, 54a to 54h, 56, 58, 60) also move with the movement of the stage (42). The photosensitive substrate (40) can always be kept at a constant temperature. That is, since the temperature around the exposure apparatus differs depending on the position, the gas ejection means (52, 54a
Until the stage (42), the temperature of the photosensitive substrate (40) becomes difficult to control properly. Further, since the temperature-adjusted gas is directly blown onto the photosensitive substrate (40), efficient and accurate control can be performed.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the following examples. In the present embodiment, the present invention is applied to a projection exposure apparatus for manufacturing a semiconductor device for projecting and exposing a pattern image formed on a reticle 36 on a wafer 40 by a step-and-repeat method.

[0009]

FIG. 1 shows the configuration of an exposure apparatus according to the present embodiment housed in an environment control chamber 12 in which temperature-controlled air (14) circulates. In the figure, an environment control chamber 12 is provided with an air cooler 16 for cooling air that has passed through the inside of the projection exposure apparatus main body 10, and an air reheater 18 for heating the cooled air to an appropriate temperature. ing. A temperature sensor 20 for detecting the temperature of the air near the exposure apparatus main body 10 is disposed on a side portion of the projection exposure apparatus main body 10, and a temperature controller 22 controls the air based on the temperature detected by the temperature sensor 20. Reheater 1
8 is controlled.

The air whose temperature is controlled by the air reheater 18 is sent to the projection exposure apparatus main body 10 by a blower 24. A chemical substance removal filter 26 is arranged near the blower opening of the blower 24 to remove reactive chemical substances in the air. Chemical substance removal filter 2
A dust removal filter 28 is disposed in front of (downwind of) 6 to remove dust in the air. Another chemical substance removal filter 30 is disposed in the environment control chamber 12 (upper left part of the figure) so as to remove a reactive chemical substance in the outside air taken into the chamber 12.

In the projection exposure apparatus 10, the exposure light emitted from a light source (not shown) is made uniform in illuminance by an illumination system 32, and the reticle 3 placed on a reticle stage 34.
6 is irradiated. The image of the pattern formed on the back surface of the reticle 36 is projected onto the wafer 40 by the projection optical system 38. The alignment microscope 39 is a so-called off-axis alignment microscope which is arranged at a predetermined distance from the optical axis of the projection optical system 38, and detects an alignment mark formed on the wafer 40. The wafer 40 is mounted on a wafer stage 42, and a movable mirror 44 is provided at an end of the wafer stage 42. The laser interferometer 46 is a movable mirror 44
The position of the wafer stage 42 is measured based on the reflected light from the camera. 1, illustration of a detailed configuration around the wafer stage 42 is omitted.

FIGS. 2 and 3 are a plan view and a side view (partial cross section) showing the structure of the wafer temperature adjusting mechanism according to the first embodiment of the present invention. In FIG. 3, for convenience of explanation, only the wafer stage 42 and the cooling gas duct 52 are shown in cross section. The wafer 40 has a wafer holder 50.
The wafer is mounted on the wafer stage 42 in a state of being vacuum-sucked by a vacuum suction unit (not shown) formed in the wafer stage. Therefore, the contact area between the wafer 40 and the wafer holder 50 is actually small. The wafer holder 50 is formed in a circular shape having a slightly larger outer diameter than the wafer 40, and is provided with the above-mentioned vacuum suction unit (not shown) inside. In the present embodiment, ceramic is used as the material of the wafer holder 50. Since ceramic is a material having a low thermal conductivity, the heat of the wafer 40 is not easily transmitted to the wafer holder 50.
For this reason, when ceramic is used for the wafer holder 50, the thermal expansion of the wafer 40 is larger than when SiC (silicon carbide) having good thermal conductivity is used for the wafer holder 50. However, as described later, in this embodiment, the temperature-controlled gas is directly blown onto the wafer 40, so that the thermal expansion of the wafer 40 can be reduced to a negligible level. Therefore, the degree of freedom in selecting the material of the wafer holder 50 is increased. As described above, the wafer holder 50
When ceramic is used as the material of the wafer 40, the heat of the wafer holder 50 is hardly transmitted to the wafer 40, and even if the temperature of the wafer holder 50 changes for some reason, the wafer
Are not affected by this temperature change. On the wafer stage 42, a cylindrical cooling gas duct 52 is provided outside the wafer holder 50 so as to surround the holder 50. The cooling gas duct 52 is designed to have a height that does not interfere with loading and unloading of the wafer 40. That is, when the wafer 40 is lifted and exchanged to a transfer mechanism (not shown) for replacement of the wafer 40, the cooling gas duct 52 is designed so as not to be obstructed by being too high. .

On the wafer 40 side of the cooling gas duct 52,
Eight gas outlets 54a, 54b, 54c, 54d, 5
4e, 54f, 54g, and 54h are provided at equal intervals. These gas outlets (54a to 54h) are arranged toward the center of the wafer 40, and are designed so as to uniformly inject a cooling gas over the entire surface of the wafer 40. As the cooling gas, for example, He, which is an inert gas, can be used. Gas outlet (54a
To 54 h) are connected to a blower 58 through a pipe 56 that passes through the cooling gas duct 52 and the wafer stage 42. The blower 58 is connected to a temperature adjuster 60 such as a cooler, and sends out the air whose temperature has been adjusted by the temperature adjuster 60 to the gas outlets (54a to 54h) via the pipe 56. I have. Gas outlet (54a-54
h), the pressure (power) of the gas ejected from the wafer 40
Is set to a relatively small value such that the residue of the resist adhering to the substrate does not blow off to become dust. On the other hand, it is necessary that the pressure be such that the temperature-adjusted gas spreads over the entire surface of the wafer 40.

The blower 58 is controlled by the controller 62 to send and stop the temperature adjusting gas. That is,
The control unit 62 controls the blowing unit 58 so that cooling air is blown onto the wafer 40 during the exposure operation, and stops the blowing operation when the exposure operation is not performed. The reason for this control is that the temperature of the wafer 40 is likely to rise due to exposure light during the exposure operation. Note that the control unit 62 can also perform control such that a gas for temperature adjustment is blown to the wafer 40 as necessary even when the exposure operation is not performed.

The control unit 62 controls the temperature adjustment unit 60 based on the detection result of the temperature sensor 20 (see FIG. 1) in the environment control chamber 12 to adjust the temperature of the gas blown to the wafer 40. Also, at least one temperature sensor (not shown) is embedded in the wafer holder 50,
Control of the temperature adjustment unit 60 may be performed based on the detection result of the temperature sensor.

In the present embodiment having the above-described structure, when performing an exposure operation, the wafer 40 is loaded onto the wafer holder 50 from a transfer system (not shown) and fixed on the wafer holder 50 by vacuum suction. Next, after performing the alignment operation of the wafer 40, the reticle 36 is irradiated with light for exposure from the illumination system 32, and the image of the pattern of the reticle 36 is projected onto the wafer 40 via the projection optical system 38. During such an exposure operation, the control unit 62 controls the sending unit 58.
In addition, the temperature controller 60 controls the temperature controller 60 to control the temperature of the wafer 40. That is, the gas whose temperature has been adjusted by the temperature adjusting unit 60 is supplied to the gas outlet (5
4a to 54h). The gas ejected from the gas ejection ports (54a to 54h) is sprayed substantially uniformly over the entire surface of the wafer 40,
Temperature can be kept constant.

When exposure of one shot area (unit exposure area) on the wafer 40 is completed, the wafer stage 42 moves stepwise to perform exposure of the next shot area. By repeating such an operation (step-and-repeat), the entire exposure area of the wafer 40 is exposed. In this embodiment, since the cooling gas duct 52 is provided on the wafer stage 42, the cooling gas duct 52 also moves with the movement of the wafer stage 42, so that the wafer 40 can always be kept at a constant temperature. it can. That is, since the temperature in the chamber 12 differs depending on the position, the gas ejection ports (54a to 54a)
h) the cooling gas duct 52 having the wafer stage 42
If not, it is difficult to control the temperature of the wafer 40 well. When the exposure of the wafer 40 is completed, the control unit 62 controls the air blowing unit 58 and the temperature adjustment unit 60, and stops the air conditioning operation of the wafer 40 until the next wafer is loaded.

In this embodiment, since the gas whose temperature is adjusted is blown to the wafer 40 under the control of the control unit 62, the position of the alignment mark formed on the wafer 40 does not shift. Therefore, the exposure apparatus of the present embodiment can accurately detect the alignment mark of the wafer 40. Further, in the present embodiment, since the pipe 56 is provided inside and near the wafer stage 42, for example, by running the pipe together with a vacuum pipe of a vacuum suction unit (not shown), the assembling and maintenance are improved. There is also an effect.

Although the embodiments of the present invention have been described above, the present invention is not limited to these embodiments and does not depart from the gist of the technical idea of the present invention shown in the claims. Various changes are possible within the scope.
For example, the wafer 40 is supplied from the gas ejection port (54a to 54h).
May be circulated in the wafer holder 50 to adjust the temperature of the wafer holder 50 simultaneously with the wafer 40. Instead of the gas outlets (54a to 54h), a continuous groove may be formed on the inner peripheral surface of the cooling gas duct 52, and the gas whose temperature has been adjusted may be blown from the groove to the wafer 40. . With this configuration, the temperature of the wafer 40 can be adjusted more uniformly and without unevenness.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating a configuration of a projection exposure apparatus and an environment control mechanism of the exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view showing a configuration around a wafer stage and a conceptual configuration of a wafer temperature adjusting mechanism in an embodiment of the present invention.

FIG. 3 is an explanatory view (side view) showing a configuration around a wafer stage and a conceptual configuration of a wafer temperature adjusting mechanism in the embodiment of the present invention, and a part of the configuration is shown in cross section.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Exposure apparatus 12 ... Environmental control chamber 36 ... Reticle 38 ... Projection optical system 40 ... Wafer 42 ... Wafer stage 52 ... Cooling gas duct 54a, 54b, 54c, 54d, 54e, 54f, 5
4g, 54h: Gas outlet 56: Piping 58: Blower 60: Temperature controller 62: Controller

Claims (4)

[Claims] 1. An exposure apparatus for exposing an image of a pattern formed on a mask to a photosensitive substrate mounted on a movable stage, wherein the exposure device is arranged on the stage so as to surround an outer peripheral portion of the photosensitive substrate. An exposure apparatus, comprising: gas blowing means for blowing a temperature-controlled gas onto a photosensitive substrate. 2. An exposure apparatus according to claim 1, wherein said gas ejection means has a plurality of ejection ports for ejecting said gas toward the center of said photosensitive substrate. 3. An exposure apparatus according to claim 1, further comprising control means for controlling said gas ejection means between an operating state and a non-operating state. 4. An exposure apparatus according to claim 3, wherein said control means activates said gas ejection means at least when said exposure is being performed.