JPH04291912A - Magnification correction mechanism - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnification correction mechanism for correcting the exposure magnification of a projection lens in an exposure optical system of a semiconductor exposure apparatus.

0002

2. Description of the Related Art Conventional exposure magnification correction mechanisms are comprised only of static pressure mechanisms using air. In other words, a static pressure bearing mechanism is installed before and after the optical system (up and down), and by adjusting the difference between the upper and lower pressures, the flying height of the optical system is adjusted and its position is changed, thereby correcting the exposure magnification. was.

Such a magnification correction mechanism requires a certain degree of positioning accuracy and rigidity to maintain the optical system at the determined position.

0004

In recent years, the magnification correction range required of exposure optical systems has become larger, and the movable range of the optical systems must be increased. However, the conventional configuration using only a static pressure mechanism has problems such as requiring a special air regulator or using a large air valve in order to increase the performance of the air valve, regulator, etc.

The present invention has been made in view of the problems of the prior art described above, and it is possible to maintain a predetermined positioning accuracy and rigidity without using a special regulator or a large air valve, and to adjust the movable adjustment range of the optical system. The purpose of this invention is to provide a magnification correction mechanism that expands the .

[0006]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides a magnification correction mechanism that moves the projection lens of a semiconductor exposure apparatus along the optical axis to change its magnification. a fine adjustment means having a predetermined variable range for positioning the projection lens at a desired target position; and a coarse adjustment means for moving the projection lens so that the target position is located within the variable range of the fine adjustment means. There is.

[0007]

[Operation] After the projection lens is moved to a target position within a finely adjustable range by the coarse adjustment means, the projection lens is positioned at the target correction position by the fine adjustment means.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a perspective view of a semiconductor exposure apparatus to which the present invention is applied. In FIG. 1, 1 is a mask, and this mask 1 is mounted on a mask stage 2 that is movable in the X, Y, and θ directions. A reduction projection lens 3 is arranged below the mask stage 2, and further below it a wafer stage 5 on which a wafer 4 is mounted. The wafer stage 5 is movable in the X, Y, θ, and Z directions.

A housing 6 houses an alignment scope 6a for TTL alignment and observation. Reference numeral 7 denotes an objective lens for television alignment, and the obtained image is captured by an imaging tube 8 for television pre-alignment.

The image pickup tube 9 observes the wafer 4 through a reduction projection lens. 10 is an exposure light source for illuminating the mask; 11a and 11b are carriers for supplying wafers; 12a,
12b is a wafer recovery carrier. 13 is a monitor TV, which includes an image pickup tube 8 for pre-alignment and a TTL
Images captured by the observation imaging tube 9 are selectively displayed. 1
4 is an operation panel having a joystick, switches, etc., and 15 is a console that controls the device in conjunction with the CRT screen.

The joystick of the operation panel 14 has multiple functions, such as moving the mask stage 2 and wafer stage 5 in the X, Y, and θ directions, moving the alignment scope 6a in the X, Y directions, and the focus Z direction. and zoom operations. These functions are set in advance so that, at a specific point in the sequence, a function related to that point is automatically selected.

Specifically, in the start waiting state, the mask stage 2 and alignment scope 6a can be driven, and after pre-alignment and auto-alignment, the wafer stage 5 can be driven, and the corresponding functions are automatically activated. selected.

The atmospheric pressure magnification correction operation is performed for each wafer, and at the timing when the wafer is moved to the supply carrier 11a, the atmospheric pressure magnification correction of the projection lens is automatically performed based on the atmospheric pressure data at that time.

In FIG. 2, the atmospheric pressure magnification correction mechanism adjusts the position of the lens 23 within the projection lens 3. This control operation is performed by the static pressure levitation mechanism 24 and the piezo levitation mechanism 2.
This is done by controlling 5. Reference numeral 22 denotes a masking blade that shields the exposure area of the exposure beam from the illumination system 21 according to a mask pattern.

The operation of the pressure magnification correction mechanism according to the present invention will be explained below with reference to FIGS. 3 and 4.

In FIG. 3, the exposure magnification is controlled by adjusting the flying height of the lens unit 28 that supports the projection lens. When the control range of the flying height increases, its rigidity and positioning accuracy must be maintained, but first of all, the range of flying height expands from the flying height of 0 to the maximum flying height L of the static pressure levitation mechanism alone. Therefore, it is necessary to increase the upper pressure. The upper air pressure has more leeway than the lower pressure because the weight of the lens and the support part is added to it. Due to the surplus of this upper pressure, pressure is increased when the flying height increases. Therefore, in the range of the flying height from 0 to L, it is possible to control the static pressure floating mechanism alone.

That is, in FIG. 3, an upper pressure bearing section (thrust pressure section) 27, a lower pressure bearing section (thrust bearing section) 30,
And due to the air pressure in each part of the radial bearing part 29,
It supports the lens unit 28 and controls the flying height of the lens unit 28 by adjusting the vertical pressure. The floating position is measured by the displacement sensor 26, and the position is set with high precision. At this time, as shown in FIG. 4, the coarse adjustment mechanism (piezo element) 31 is in an OFF state.

Next, a case will be described in which the maximum flying height L of the static pressure floating mechanism alone is exceeded from the flying height reference position 35 (FIG. 4).

In this case, it is necessary to increase the lower pressure. As shown in FIG. 4(b), the coarse adjustment mechanisms (piezo elements) 31 provided at three locations at the bottom of the lower pressure bearing part 30 are turned on to raise the lower pressure bearing part 30, and the static pressure drive control is performed. The lower pressure bearing portion 30 is held at a position l1 where it is possible. At this position, the position of the lens unit 28 is controlled within the range of the flying height from 0 to L by the static pressure floating mechanism. Therefore, the flying position can be controlled from the displacement reference position 35 to the flying height L+l1. The amount of displacement is measured by the displacement sensor 26, and the tilt of the lens unit is adjusted to achieve highly accurate positioning.

[0020]

[Effects of the Invention] As explained above, in the present invention, by using a pressure magnification correction mechanism (static pressure levitation mechanism) and a coarse adjustment mechanism using piezo elements, positioning accuracy and rigidity are not reduced. The range of magnification correction can be expanded.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a semiconductor exposure apparatus to which the present invention is applied.

FIG. 2 is a configuration diagram of main parts of a semiconductor exposure apparatus to which the present invention is applied.

FIG. 3 is a configuration diagram of a magnification correction mechanism according to the present invention.

FIGS. 4(a) and 4(b) are explanatory views of the operation of the magnification correction mechanism according to the present invention, respectively.

[Explanation of symbols]

3 Projection lens 23 Lens 24 Static pressure levitation mechanism 25 Piezo levitation mechanism 26 Displacement sensor 28 Lens unit 30 Lower pressure bearing part 31 Piezo element

Claims (3)

[Claims] 1. In a magnification correction mechanism for moving a projection lens of a semiconductor exposure apparatus along an optical axis to change its magnification, a fine adjustment mechanism having a predetermined variable range for positioning the projection lens at a target position to be corrected is provided. A magnification correction mechanism comprising: an adjustment means; and a coarse adjustment means for moving the projection lens so that the target position is located within a variable range of the fine adjustment means. 2. The magnification correction mechanism according to claim 1, wherein the fine adjustment means comprises a static pressure mechanism that moves the lens based on a pressure difference before and after the projection lens. 3. The magnification correction mechanism according to claim 1, wherein the coarse adjustment means comprises a piezo element that drives the support of the projection lens.