JPH05312541A - Pattern position measuring instrument - Google Patents

Abstract

PURPOSE:To obtain a pattern position measuring instrument which can arbitrarily change the bent state of its substrate. CONSTITUTION:A sealed soft bag 4 filled with a fluid under a prescribed pressure is put between a stage 8 which moves almost in a plane and a substrate 2 held between substrate holders 1 and 3 so that a uniform pressure can be applied to the lower surface of the substrate 2. The bent state of the substrate 2 can be arbitrarily changed by changing the pressure in the bag 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern position measuring device for measuring the position of a precision pattern formed on the surface of a substrate such as a mask or reticle used in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art An example of a conventional pattern position measuring device for measuring the position of a mask pattern is shown in FIG. The mask 2 is mounted on the suction unit 3 of the holder 1 arranged on the two-dimensional stage 8, and the measurement optical system 10 irradiates the pattern surface of the mask 2 with the focused light Bi. When the focused light Bi hits the pattern edge, scattered light is generated or specular reflection light occurs. Therefore, by processing these optical signals by the light receiving system built in the measurement optical system 10, the pattern Pm is formed. Can be detected. Further mask 2
Can be moved in the two-dimensional direction by the two-dimensional stage 8 and the amount of movement can be accurately measured by the laser interferometer 9 (the vertical direction on the paper surface is not shown). Therefore, the laser interferometer when the pattern Pm is detected. By reading the measured value of 9, the position of each pattern can be detected with high accuracy.

By the way, at this time, the mask 2 is bent downward due to gravity. Expanding and coordinating this situation,
Shown in. Since the mask 2 is mounted with the pattern surface facing upward, the distance between the patterns Pm is slightly shortened as compared with the free state (state without bending). Therefore, JP-A-6
In No. 3-233312, the amount of change in the distance between the patterns Pm caused by the bending of the mask 2 is corrected to a non-bending state by calculation by measuring the bending shape of the mask 2. Further, in FIG. 6, the mask 2 fixed to the holder 13 is shown.
Pattern Pm is illuminated with the illumination light Li, and the projection lens 11
1 shows an exposure apparatus for transferring a resist onto the coated wafer 12. The wafer 12 is placed on a stage 14 that can be moved two-dimensionally, and a plurality of shots of exposure are performed on the same wafer. The stage 14 is accurately positioned by a laser interferometer system 15 (not shown in the vertical direction on the paper surface). In order to manufacture an integrated circuit, it is necessary to transfer a plurality of mask patterns onto the same wafer, and these patterns must be accurately aligned with each other. Therefore, the position of each mask pattern must be precisely measured. As shown in FIG. 7, in the exposure apparatus, the mask 2 is mounted with the pattern surface facing downward and is bent downward. That is, in the pattern position measuring device, the position of the pattern is measured in a state where the pattern position measuring device is bent, contrary to when it is mounted on the exposure device.

[0004]

In the conventional pattern position measuring device as described above, it is necessary to accurately measure the bending shape in order to correct the distance between the patterns Pm to a state without bending by calculation. Further, even if the flexure shape can be accurately measured, the calculation for correction is complicated and cannot be completely corrected.

Further, since the mask 2 mounted on the pattern position measuring device is bent with the pattern surface facing upward, there is a problem in that the conventional deflection correction cannot correct the distance between patterns to the state of being mounted on the exposure device. It was The present invention is
The present invention has been made in view of such problems, and an object thereof is to provide a pattern position measuring device capable of arbitrarily changing a bending state of a mask when mounted on the pattern position measuring device.

[0006]

In order to solve the above problems, according to the present invention, a stage 8 that moves in a substantially flat surface and a substrate holder arranged on the stage 8 for holding the outer peripheral portion of the substrate 2 are provided. In the pattern position measuring device for measuring the position of a precision pattern on the surface of the substrate 2 held by the substrate holders 1, 1 ', 3, 3', A flexible airtight bag 4 filled with a fluid at a predetermined pressure is arranged between the substrate 2 held by the holders 1, 1 ′, 3, 3 ′ and the stage 8 so that the lower surface of the substrate 2 is evenly distributed. I tried to apply a great pressure.

[0007]

In the present invention, a flexible airtight bag filled with a gas or a liquid is arranged under the substrate, and a uniform force is applied to the entire lower surface of the substrate according to the principle of Pascal. Therefore, the bending state of the substrate can be arbitrarily changed by setting the pressure in the sealed bag to an arbitrary pressure.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of a main part of a first embodiment of the present invention. A holder 1 having the same shape as the holder 13 of the exposure apparatus shown in FIG. 6 is arranged on the stage 8. The holder 1 operates integrally with the stage 8. The mask 2 is fixed to the suction portion 3 of the holder 1 with the pattern surface facing upward. A soft rubber closed bag 4 is placed between the mask 2 and the stage 8. The airtight bag 4 is connected to a pressure control airtight bag 6 arranged outside the stage 8 via a hollow tube 5. Further, the hermetically sealed bag 4, the hermetically sealed bag 6 for pressure control
Is filled with air. A weight 7 whose weight per unit area is equal to that of the mask 2 is placed on the pressure control closed bag 6. At this time, the hermetically sealed bag 4 is in pressure contact with almost the entire lower surface of the mask 2. Further, the force of the air in the airtight bag 4 and the air in the airtight bag 6 for pressure control to push the inner surface of the bag is equal at any point according to the principle of Pascal. Further, since the mask 2 and the weight 7 have the same weight per unit area, the force of the sealing bag 4 pushing the mask 2 from the lower surface and the gravity applied to the mask are balanced. Therefore, the mask 2 is almost equivalent to the free state (state without bending). If the pattern position is measured in this state, it can be compared with the designed pattern position, and it can be inspected whether or not the pattern Pm is formed as designed. FIG. 2 shows a second embodiment of the present invention. The same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. When the two weights 7 shown in FIG. 1 are placed on the pressure control sealing bag 6, the force with which the sealing bag 4 pushes the mask 2 from the lower surface becomes twice the gravity applied to the mask 2, so When gravity acts from below, the state becomes almost the same, and the pattern surface side extends and bends. This state is shown in Figure 7.
It is almost the same as the bending state of the mask when mounted on the exposure apparatus shown in FIG.

However, comparing FIG. 2 and FIG. 7, the back surface of the pattern is adsorbed in FIG. 2 and the pattern surface is adsorbed in FIG. That is, strictly speaking, the force applied in the vicinity of the suction portion of the mask 2 is different. This point is resolved in the third embodiment of FIG. The same members as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. In the third embodiment, a suction unit 3'is provided below a holder 1'which moves integrally with the stage 8, and the mask 2 is suctioned on the pattern surface. In this state of adsorption, as in the second embodiment, two weights 7 are placed on the pressure control closed bag 6, and the pressure in the closed bag 4 causes a force equivalent to gravity to be applied to the mask 2 from the lower surface. Add to. The bending state of the mask 2 is completely equal to the state of FIG. 7 when it is mounted on the exposure apparatus. Therefore, it becomes possible to measure the pattern position of the mask 2 in a state equivalent to that used in the exposure apparatus.

In the above embodiment, in order to control the pressure of the gas in the sealed bag 4, the pressure controlled sealed bag 6 and the weight 7 are used.
However, it goes without saying that it is possible to use other pressure control means such as a pump. Also, although the air bag was filled with air, if a gas with high thermal conductivity such as He gas is enclosed, the mask in contact with the air bag can be quickly adjusted to the temperature inside the measuring device, and the pattern position The measurement can be performed more accurately.

[0011]

As described above, according to the present invention, the sealing bag filled with the fluid is arranged between the substrate and the stage so that a uniform force is applied to the lower surface of the substrate. Therefore,
By changing the pressure in the airtight bag, it is possible to arbitrarily change the bending state of the pattern surface of the substrate mounted on the pattern position measuring device, so that the pattern position can be measured in the bending state as needed.

[Brief description of drawings]

FIG. 1 is a sectional view of a main portion of a first embodiment of the present invention.

FIG. 2 is a sectional view of a main portion of a second embodiment of the present invention.

FIG. 3 is a sectional view of a main portion of a third embodiment of the present invention.

FIG. 4 is an overall view of a conventional pattern position measuring device.

5 is an enlarged view of a main part of FIG.

FIG. 6 is an overall view of an exposure apparatus.

FIG. 7 is an enlarged view of a main part of FIG.

[Explanation of symbols]

 1, 1'Holder 2 Substrate 3, Adsorption part of 3'holder 4 Sealing bag 5 Hollow tube 6 Pressure control sealing bag 7 Weight 8 Stage 9 Laser interferometer system 10 Measurement optical system 11 Projection lens 12 Wafer 13 Holder 14 Stage 15 Laser interferometer system 16 Adsorption part of holder Pm pattern Bi Focused light Li Illuminated light

Claims (2)

[Claims] 1. A stage which moves on a substantially flat surface, and a substrate holder which is disposed on the stage to hold an outer peripheral portion of the substrate, and a precision pattern of a substrate surface held by the substrate holder. In a pattern position measuring device for measuring the position, a flexible airtight bag filled with a fluid at a predetermined pressure is arranged between the central portion of the substrate held by the substrate holder and the stage, and the lower surface of the substrate is placed. A pattern position measuring device characterized in that uniform pressure is applied. 2. The pattern position measuring device according to claim 1, further comprising pressure control means for controlling the pressure inside the closed bag.