JPH11297604A - Charged particle beam aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent deterioration of exposure-precision by restraining the influence of radiation heat from a pump for maintaining the inside of a chamber in the state of vacuum, in a charge particle beam aligner. SOLUTION: This aligner is equipped with a chamber 12 in which exposure process is performed, a stage 11 mounting a specimen 10 to be exposed in the chamber 12, a column 13 including an electronic optical means which generates a charged particle beam EB and converges, deflects and casts it on the specimen 10, and a pump 14 for maintaining the inside of the chamber 12 in the state of vacuum at the time of exposure. In the vicinity of an aperture in the lower part of the chamber 12, a heat reflecting plate 16 for shielding the radiation heat RH from the pump 14 is installed at a position separated by a specified distance from the inner wall of the chamber 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure apparatus using a charged particle beam such as an electron beam, and more particularly to an electron beam exposure apparatus having a pump for evacuating a chamber in which an exposure process is performed. A technology effective in reducing the influence of the radiant heat from the pump.

[0002]

2. Description of the Related Art The basic operation of an electron beam exposure apparatus is as follows.
An electron beam is generated, converged, and deflected in a column connected to a chamber where an exposure process is performed. The beam is irradiated onto a sample to be exposed (specifically, a wafer) mounted on a stage in the chamber. By exposing and moving the stage, a pattern is drawn on the entire surface of the wafer. At this time, the point of the performance of the exposure apparatus is the exposure accuracy (that is, accurate drawing of a desired pattern). At this time, what is important is to accurately know the drawing position on the column and the wafer. That is.

On the other hand, in an electron beam exposure apparatus, it is necessary to maintain a high vacuum in a chamber during exposure. A pump is typically used as a means for bringing the inside of the chamber into a vacuum state, and among them, it is particularly effective to use a turbo-molecular pump. FIG. 2 schematically shows a configuration of a conventional electron beam exposure apparatus using such a turbo-molecular pump in a partially sectional view.

In the figure, reference numeral 10 denotes a wafer (sample to be exposed), 11
Is a stage on which the wafer 10 is mounted and the movement of which is controlled in the horizontal direction. 12 is a chamber in which the exposure processing of the wafer 10 is performed. 13 is coupled to the chamber 12 so as to cover the upper opening of the chamber 12, and A column incorporating electron optical means (electron gun, main deflector, sub deflector, etc.) for generating, converging, deflecting, and irradiating the wafer 10, 14 includes the lower opening of the chamber 12. Turbo molecular pumps 15a and 15b are connected to the chamber 12 for sucking air in the chamber 12 during exposure to make a vacuum, and reference numerals 15a and 15b denote legs supporting the chamber 12, respectively. In addition, EB schematically shows an electron beam irradiated on the wafer 10, and RH schematically shows a flow of heat (radiant heat) generated by the turbo molecular pump 14. The chamber 12 has two legs 15 in the illustrated example.
Although they are supported by a and 15b, they are actually supported by four or more legs.

[0005] As shown in FIG.
Are mounted “bare” to the interior of the vacuum chamber 12. Therefore, the turbo molecular pump 14
Is transmitted directly to the stage 11 and the column 13 as shown in the figure.

[0006]

As described above, in the conventional configuration, since the radiant heat RH from the turbo molecular pump 14 is directly transmitted to the stage 11 and the column 13, the temperature of the stage 11 and the column 13 rises. Causes thermal expansion. This makes it difficult to accurately measure the drawing position. This is because the measurement of the position of the stage 11 is actually performed at a position away from the drawing position, and when the stage 11 expands due to heat, the distance between the measurement position and the drawing position changes. is there.

As described above, in the configuration of the electron beam exposure apparatus using the conventionally known turbo-molecular pump, the position where the pattern should be drawn due to the radiation heat from the turbo-molecular pump directly hitting the stage or the like. There is a problem that cannot be measured accurately. This leads to a decrease in the accuracy of pattern alignment at the time of exposure and, consequently, a decrease in exposure accuracy, and there is room for improvement.

The present invention has been made in view of the above-mentioned problems in the prior art, and is a charged particle capable of suppressing the influence of radiant heat from a pump for evacuating the chamber and preventing a decrease in exposure accuracy. It is an object to provide a beam exposure apparatus.

[0009]

According to the present invention, there is provided a chamber in which an exposure process is performed on a sample to be exposed, a chamber in which the sample to be exposed is mounted, and which is mounted in the chamber. A stage whose movement is controlled in the horizontal direction, and an electron coupled to the chamber so as to cover the opening at the top of the chamber, for generating, converging, deflecting and irradiating the charged particle beam onto the sample to be exposed. A charged particle beam exposure apparatus, comprising: a column having a built-in optical unit; and a pump coupled to the chamber so as to include an opening at a lower portion of the chamber, and a pump for evacuating the chamber during exposure. A heat reflecting plate for shielding radiant heat from the pump is provided near the opening at the lower portion of the chamber and at a predetermined distance from the inner wall of the chamber in the chamber. The charged particle beam exposure device is provided, characterized in that the.

[0010] According to the configuration of the charged particle beam exposure apparatus of the present invention, the heat reflecting plate is provided near the opening of the chamber to which the pump is connected. Radiant heat from the pump can be prevented from being directly transmitted to the stage and the column. As a result, a rise in the temperature of the stage and the column is suppressed, and thermal expansion can be prevented. Therefore, it is possible to accurately measure the drawing position of the pattern and prevent a decrease in exposure accuracy.

In the above charged particle beam exposure apparatus, a support leg for fixing the heat reflection plate to a lower portion of the chamber may be provided, and the support leg may be formed of a material having good heat conductivity. According to this configuration, the heat generated by itself in the process of shielding the radiant heat by the heat reflecting plate is partially transmitted into the chamber, but most is effectively transmitted to the chamber through the support legs, Finally released to the outside of the chamber. This further contributes to suppressing the temperature rise of the stage and the column.

[0012]

FIG. 1 schematically shows a configuration of an electron beam exposure apparatus according to an embodiment of the present invention in a partially sectional view. The illustrated example shows a state at the time of exposure. In the figure, 10 to 14, 15a, 15b, EB and RH are the same as the corresponding elements shown in FIG. 2 respectively, and the description thereof will be omitted.

The structure of the electron beam exposure apparatus according to the present embodiment is characterized in that the chamber 1 is located near the lower opening of the chamber 12 to which the turbo molecular pump 14 is connected.
A heat reflection plate 16 that shields radiant heat RH from the turbo molecular pump 14 is disposed at a predetermined distance from the inner wall of the chamber within the chamber 2. Further, the heat reflection plate 16 is fixed to a lower portion of the chamber 12 by two support legs 17a and 17b in the illustrated example.

The heat reflection plate 16 can be formed of, for example, stainless steel, but it is not necessary to necessarily form the heat reflection plate 16 in principle because it is sufficient to have a function of shielding the radiant heat RH. The distance between the heat reflecting plate 16 and the lower inner wall of the chamber 12 (the predetermined distance) is
For example, it is selected within a range of 40 mm to 50 mm. On the other hand, the support legs 17a and 17b are desirably formed of a material having good thermal conductivity, such as metal (eg, copper), and more preferably have a large cross-sectional area. Because the heat reflection plate 16 itself becomes hot in the process of shielding the radiant heat RH, the heat generated by the heat reflection plate 16 may be more or less released into the chamber 12 and affect the temperature of the stage 11. If possible, it is desirable to escape to the outside of the chamber 12 if possible. According to the present embodiment, most of the heat generated by the heat reflecting plate 16 is effectively transmitted to the chamber 12 through the support legs 17 a and 17 b having good heat conductivity, and finally is transmitted to the outside of the chamber 12. Released.

According to the configuration of the apparatus of this embodiment,
A heat reflection plate 16 for shielding the radiant heat RH from the turbo-molecular pump 14 is provided near the opening at the lower part of the chamber 12 to which the turbo-molecular pump 14 is connected, so that the radiant heat RH from the turbo-molecular pump 14 is provided. Can be prevented from being directly transmitted to the stage 11 and the column 13. Accordingly, a rise in the temperature of the stage 11 and the column 13 is suppressed, and thermal expansion can be prevented. Therefore, accurate measurement of the drawing position can be performed, and a decrease in exposure accuracy can be prevented.

Further, since the supporting legs 17a and 17b are formed of a material having good heat conductivity, most of the heat generated in the process of shielding the radiant heat RH by the heat reflecting plate 16 is mostly used for the supporting legs. It is effectively transmitted to the chamber 12 via 17a and 17b and finally discharged outside the chamber 12. This is the stage 11 and column 13
This further contributes to the suppression of temperature rise.

In the above embodiment, the heat reflecting plate 1
6 is fixed by the two supporting legs 17a and 17b, but the number of supporting legs may be appropriately selected according to the shape of the heat reflecting plate 16.

[0018]

As described above, according to the charged particle beam exposure apparatus of the present invention, the influence of the radiant heat from the pump provided to make the inside of the chamber where the exposure processing is performed a vacuum state is suppressed. This makes it possible to accurately measure the drawing position of the pattern, thereby preventing a decrease in exposure accuracy.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a configuration of an electron beam exposure apparatus according to an embodiment of the present invention in a partially sectional view.

FIG. 2 is a diagram schematically showing a configuration of an electron beam exposure apparatus as an example of a conventional technique in a partially sectional view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Wafer (sample to be exposed) 11 ... Stage 12 ... Chamber 13 ... Column 14 ... Turbo molecular pump 15a, 15b ... Support leg of a chamber 16 ... Heat reflection plate 17a, 17b ... Support leg of a heat reflection plate EB ... Electron beam ( Charged particle beam) RH: radiant heat

Claims (2)

[Claims] 1. A chamber in which an exposure process of a sample to be exposed is performed, a stage on which the sample to be exposed is mounted and which is controlled to move in the chamber in a horizontal direction, and an opening at an upper portion of the chamber. A column containing electron optical means for generating, converging, deflecting and irradiating the charged particle beam onto the sample to be exposed, and a lower opening of the chamber. A charged particle beam exposure apparatus coupled to a chamber and provided with a pump for evacuating the inside of the chamber during exposure, wherein a predetermined distance from an inner wall of the chamber in the chamber near an opening at a lower portion of the chamber. A charged particle beam exposure apparatus, wherein a heat reflection plate for shielding radiant heat from the pump is provided at a distance. 2. The charged particle beam exposure apparatus according to claim 1, further comprising a support leg for fixing the heat reflection plate to a lower portion of the chamber, wherein the support leg is formed of a material having good thermal conductivity. A charged particle beam exposure apparatus.