JPS6139518A - Projecting and exposing device - Google Patents

Abstract

PURPOSE:To enable to perform an accurate position detection by a method wherein an optical path length changing means, with which the optical path length of the optical system to be used for alignment can be changed in accordance with the thickness of a substrate, is provided. CONSTITUTION:The quantity of movement calculated by an arithmetic unit 22 based on the thickness value of the original drawing pattern substrate 13, which is set in advance, is picked out from a memory storage 27 by a memory storage selecting circuit 28, and the material 10 to be exposed which is installed on a Z-axis positioning mechanism 21, is set at the appropriate position using the Z- axis positioning mechanism 21, a Z-axis driving motor 20, and a Z-axis position detector 19 which are controlled by a controlling circuit 29. Subsequently, the reference pattern 11 located on the material to be exposed, which is illuminated by a detecting illumination system 17, a detecting illumination system 15 and projection optical system 12, is precisely coincided with the position of focus of the detecting optical system 15, and a clear image can be obtained on a photoelectric detector. The signal of said image is inputted to an arithmetic operating unit 22, and the relative position detection for the original drawing of pattern 13 and the material to be exposed 10 can be performed accurately.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a projection exposure apparatus, and particularly to a projection exposure apparatus for accurately projecting and exposing an original pattern onto a desired position on an object to be exposed.
This invention relates to a projection exposure apparatus capable of detecting relative positional deviation between an original pattern and an exposed object.〇 [Background of the Invention] Through a projection optical system, the original pattern and the exposed object are directly detected.
! II! For example, in a conventional projection exposure apparatus as shown in Japanese Patent Laid-Open No. 111355-162227 for detecting positional deviation and positioning, a detection optical system is generally used more than that shown in FIG. That is, a reference pattern 2 on an object (wafer) 1 to be exposed is illuminated through a projection optical system 3, and conversely, the image is projected onto a base i provided on an original pattern reference (reticle) 4 via the projection optical system 3. The pattern is imaged onto the slit (slit) 5 - the composite image is guided to the photoelectric detector 7 via the detection optical system 6, and the amount of relative deviation between the exposed object (multi-evaporator) 11 and the original pattern (reticle) 4 is detected. is being detected. Now placed in the detection optical system 6,
When replacing the original/figure pattern substrate (reticle) 4 and attempting to expose a different original pattern, if the thickness of this original pattern substrate is different from the thickness of the previous original pattern substrate, the focus of the slit will be It no longer connects to the bottom surface of the reticle 4. That is, since the optical path length of the detection optical system 6 changes, the focal point of the detection optical system 6 is lowered, resulting in a blurred detection image on the photoelectric detector 7, which has the disadvantage that detection accuracy cannot be obtained. That is, it has the disadvantage that accurate position detection cannot be performed. .

[Purpose of the invention]

An object of the present invention is to provide a projection exposure apparatus that can perform accurate position detection.

[Summary of the invention]

The principle of the present invention will be explained using FIGS. 2 and 3. That is, FIG. 2 shows an optical path diagram of the detection optical system for two original pattern substrates (reticles) 4 having different thicknesses. Assuming that the focal position of the detection optical system is now adjusted to the original pattern substrate of thickness io, the focal position is at point ho on the bottom surface of the substrate. However, when exchanging the original pattern substrate and exposing a different original, the thickness of the original pattern substrate is not constant, so when the thickness of the substrate changes from 10 to t, the focal position changes to 110 points. Move from to point A1. The moving distance A.

For Al, let the angle of incidence with respect to the original pattern substrate be θ, and the angle of refraction be ψ.
)tanθ. On the other hand, as shown in Figure 3, the unveiling object (
Since the focus position of the reference pattern on the wafer 1 by the projection optical system 3 is at one point on the lower surface A of the original pattern substrate, the image on the photoelectric detector 7 is blurred, giving an error to the detection result. , it is necessary to match the focal position of the reference pattern projection optical system 3 on the object to be exposed (wafer 1) with A1.

In order to match their focal positions, the distance between the projection optical system 3 and the object 1 to be exposed 1 may be changed by Δb.

The separation Δb is equal to the thickness of the substrate 1o! 1 lil! ! In the projection optical system 3, the distance between the reference 4 and the principal point of the projection optical system 3 is 31, the object to be exposed 1 and the projection optical system 3-! When the distance at i is b1 and the focal length of the projection optical system 3 is f, it is expressed as follows. According to this equation (2), when detecting the relative positional deviation of the reference pattern, the distance between the exposed object 1 and the projection optical system 3 is changed by Δb shown in the above equation (2). That is, by lowering the exposed object 1 by Δb, an accurate detection value can be obtained even if the thickness of the original pattern substrate 4 differs from the adjustment reference value. By returning the distance between the object 1 to be exposed and the projection optical system 3 to the normal position immediately before projection exposure after detecting the relative deviation, the exposed pattern will not be affected in any way.

Therefore, the present invention selects the optical path length of the alignment optical system corresponding to the thickness of the original pattern substrate from a storage device storing drive signals for driving the two-axis positioning mechanism according to the thickness of the original pattern substrate, The idea is to perform accurate position detection by moving the object to be exposed in a direction in which the optical path length changes.

[Embodiments of the invention]

Examples of the present invention will be described below.

FIG. 1 shows an embodiment of the present invention.

In the figure, a two-axis positioning mechanism 21 is provided above an X-Y positioning mechanism 24. This two-axis positioning mechanism 2
An object to be exposed (Ueno) 10 is mounted on the substrate 1 .

The object to be exposed 1 has a reference notch turn 11 formed therein, and this -°° quasi-notch turn is passed through a projection optical system 12 to an original pattern substrate 130 and a reference pattern (slit) 1.
4. This imaged state is bent by a mirror 18 and supplied to a photoelectric detector 16 via a detection optical system 15. A detection illumination system 17 is provided between the detection optical systems 150.

On the other hand, a lens is provided above the original pattern board 13, and a shutter 25 is provided above the lens. An exposure illumination system 26 is supplied to the lens through this shutter 25. Further, the Z-axis positioning mechanism 21 is provided with a Z-axis drive morph 20 and is configured to perform control in the Z-axis direction. Further, a two-axis position detector 19 is installed in this two-axis positioning mechanism 21 .

A control circuit 29 is connected to this Z-axis position detector 19, and this control circuit 29 controls the two-axis drive motor 2.
0 is controlled.

A computing unit 22 is connected to this control circuit 20 .

``A photoelectric detector is connected to this arithmetic unit 22 via an A/D converter 23. Further, a storage device selection circuit 28 is connected to this arithmetic unit 22, and a plurality of storage devices are connected to this storage device selection circuit 28.

A Z-axis positioning mechanism 21 for focusing is vertically driven by a two-axis drive motor 20. Further, the two-axis positioning mechanism 21 is each subjected to feedback control by a computing unit 23 based on the values detected by the two-axis position detector 19.

The exposed object 10 mounted on the two-axis positioning mechanism 21 is
Based on the thickness value of the original pattern board 13 set in advance, the movement amount calculated by the calculator 22 from the above equations (1) and (2) is sent to the storage device selection circuit 28, and the corresponding storage device @
27, remove the screw from the side, place it in the proper position, and move the two-axis positioning mechanism 21 controlled by the control circuit 29, the z-axis drive motor 20,
It is set by the z-axis position detector 19. Thereafter, the reference pattern 11 on the object to be exposed illuminated by the detection illumination system 17, the detection optical system 15, and the projection optical system 12 correctly matches the focal position of the detection optical system 15, and a clear image appears on the photoelectric detector 16. An image is obtained. The signal of this image is transmitted to the photoelectric detector 16,
The data is input to the arithmetic unit 22 by the A/D converter 23, and the relative position between the original pattern 13 and the object 10 to be exposed is accurately detected.

After that, the Z-axis drive motor 20XZ-axis position detector 19
．． The two-axis positioning mechanism 21 sets the focal position tK of the projection optical system 12 and the object 10 to be exposed, and the X-Y positioning mechanism 24 moves the object 1o to the designated position and opens the shutter of the exposure illumination system 26. 25 is opened and closed to perform exposure.

Therefore, according to this embodiment, even if original pattern substrates with different thicknesses are used, there is no change in the pattern signal obtained when detecting the relative position of the original pattern and the exposed object, so accurate relative positioning is always possible. This has the effect of not having any effect on the light pattern exposed on the object to be exposed.

〔Effect of the invention〕

As described above, according to the present invention, accurate position detection can be performed.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing an embodiment of the present invention, Fig. 2 is an optical path diagram of the detection optical system in the original pattern board portion, Fig. 3 is an optical path diagram of the projection portable system, and Fig. 4 is a conventional projection exposure method. FIG. 2 is a schematic diagram showing the device. 10...Exposed object, 11...Reference pattern, 12.
...Projection optical system, 13...Original pattern board, 14.
...Reference pattern, 15...Detection optical system, 16...
Optical τti detector, 17... Detection illumination system, 18... Mirror, 19... Z-axis position detector, 20... 2-axis drive motor, 21... 2-axis positioning mechanism, 22... - Arithmetic unit, 23... A/D converter, 24... X-Y positioning mechanism, 25... 7-layer, 26... Exposure illumination system, 27... Storage device, 28... storage device selection circuit;
29...control circuit.

Claims (1)

[Claims] 1. A substrate on which a pattern and an alignment mark are formed, a transfer means for transferring the pattern to an exposed object having the alignment mark by irradiation with light, and superposition of both the marks using light transmission of the substrate. It is characterized by comprising an alignment optical system for forming a combined image at a predetermined position, and an optical path length variable means for changing the optical path length of the alignment optical system according to the thickness of the substrate. Projection exposure equipment.