JPH0729817A - Leveling detector for sequential shift aligner - Google Patents

Abstract

PURPOSE:To enhance the leveling detection accuracy in a region to be exposed by providing a diaphragm mechanism for varying the spot size of leveling detection light. CONSTITUTION:A diaphragm constricts a leveling detection light 4 emitted from a light source 3 and collimated through a collimate lens 5. Constriction can be controlled by rotating a movable piece 9a. Consequently, the spot size of the leveling detection light 4 irradiating an exposure region 6 can be varied by the diaphragm 9 depending on the size of a region being exposed by one shot which differs depending on the type of semiconductor chip. This constitution avoids the problem that the detection accuracy is lowered by conducting the leveling detection based on a leveling detection light irradiating a region wider than the region to be exposed actually.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a leveling detection apparatus for a stepwise exposure type exposure apparatus, and more particularly to a light source for emitting leveling detection light to a wafer placed on a leveling stage, and the above-mentioned wafer emitted from the light source. The present invention relates to a leveling detection device for a sequential movement type exposure apparatus, which has a leveling detector that receives the above-described leveling detection light and detects the leveling.

[0002]

2. Description of the Related Art As an exposure apparatus, a desired pattern formed on a reticle is reduced and projected onto a portion of a semiconductor wafer to be exposed, and when the exposure of that portion is completed, the reduced projection portion of the pattern is moved and exposed. There is a sequential movement type exposure apparatus that sequentially moves the exposure region by using a stepper, which is called a stepper. Further, such a sequential movement type exposure apparatus is usually equipped with a leveling detection device. The leveling detection device is for detecting an inclination of the exposure area from a direction perpendicular to the exposure optical axis, and when the inclination is detected, the orientation of the leveling stage is adjusted to eliminate the inclination.

As described above, the leveling detection device is provided to detect the inclination between the exposure area and the direction perpendicular to the exposure optical axis, and to eliminate the inclination, the surface orientation is different for each exposure area. If the exposure process is performed without changing the orientation of the leveling stage on the entire surface of one chip, ignoring the difference in orientation, the image of the image passing through the reticle will be blurred and the line width will vary. This is because such a phenomenon occurs.

FIG. 3 is a perspective view showing the outline of a conventional example of a leveling detection device. In the drawing, reference numeral 1 is a leveling stage, which supports a semiconductor wafer 2 which is automatically conveyed.
1a is a fixed point of the leveling stage 1, and 1b,
Reference numeral 1c is a drive point of the leveling stage 1. And
The drive points 1b, 1c are moved up and down by a drive mechanism (not shown), and the orientation of the leveling stage 1 with respect to the exposure optical axis (not shown) can be changed by the up and down movement.

Reference numeral 3 is a light source for generating the leveling detection light 4 toward the exposure area of the semiconductor wafer 2, 5 is a collimating lens for converting the leveling detection light 4 into parallel light, 6 is an exposure area of the semiconductor wafer 2, and 7 is an exposure area. Is a condenser lens for condensing the leveling detection light 4 reflected by the exposure area 6 of the semiconductor wafer 2, and 8 is a leveling detection light for receiving the leveling detection light 4 condensed by the condenser lens 7. It is a leveling detector. The leveling detector 8 has a light receiving surface divided into four regions, and the leveling can be detected from the ratio of the amount of received light in each divided region.

[0006]

In the conventional exposure apparatus, the spot size of the leveling detection light is determined by the size of the exposure area, and the spot size cannot be changed. For example, in the case of an exposure device having an exposure area of 15 mm square, the spot size is 15 mmφ, and in the case of an exposure device having an exposure area of 20 mm square, the spot size is 20 mm.
mmφ. However, as shown in FIG. 4, the actual size of the area exposed in one shot is slightly different depending on the chip size. For example, even if an exposure device for 15 mm square is used, the size of the area exposed in one shot is small. It becomes smaller than 15 mm, and how small it is depends on the chip size.

Despite this, in the case of the exposure device for 15 mm square, the spot size of the leveling detection light was fixed at 15 mmφ, and the spot size did not change even though the actual exposure area was narrower than the 15 mm square. However, it was not possible to irradiate the exposure light beam perpendicularly to the surface of the area to be actually exposed. That is, since the leveling detection is performed based on the leveling detection light by irradiating a wider area than the area to be actually exposed, the detection accuracy cannot be increased. However, as ICs and LSIs have become highly integrated, wiring films and the like have become finer, and there has been a strong demand for higher precision in photolithography. To meet such demands, it has become essential to increase the leveling detection precision. There is.

The present invention has been made to solve such a problem, and an object thereof is to improve the leveling detection accuracy of an area to be exposed.

[0009]

According to another aspect of the present invention, there is provided a leveling detection device for a stepwise movement type exposure apparatus, wherein a leveling mechanism for changing the spot size of the leveling detection light is provided. A leveling detection device for a sequential movement type exposure apparatus according to claim 2 is the leveling detection device according to claim 1, wherein
It is characterized in that the diaphragm mechanism makes the shape of the spot rectangular and the aspect ratio of the rectangle is variable.

[0010]

According to the leveling detection device of the stepwise movement type exposure apparatus of claim 1, since the spot size of the leveling detection light can be changed by the diaphragm mechanism, the leveling detection can be performed according to the size of the area to be exposed. By changing the spot size of the working light, it is possible to avoid the problem that the leveling detection is performed on the basis of the leveling detection light irradiated on the area wider than the area to be actually exposed and the detection accuracy is lowered.

According to the leveling detection device of the stepwise movement type exposure device of the second aspect, since the spot shape can be made rectangular by the diaphragm mechanism, the shape of the spot is rectangular and the area to be actually exposed is formed. Since they can be matched and the aspect ratio of the spots can be changed, the aspect ratio of the rectangular spot can be changed according to the aspect ratio of the chip. Therefore, the leveling accuracy can be further improved.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A leveling detection device for a sequential movement type exposure apparatus of the present invention will be described in detail below with reference to the illustrated embodiments. Figure 1
(A) and (B) show one embodiment of a leveling detection device of a sequential movement type exposure apparatus of the present invention, (A) is a perspective view and (B) is a front view of a diaphragm. This leveling detection device is completely different from the leveling detection device shown in FIG. 3 in that it has a diaphragm mechanism, but it is the same in all other respects, and since the common points have already been described, the description thereof will be omitted and the difference will be made. Only the points to be described will be described. Further, the same reference numerals are given to the portions common to FIG. 3 of FIG.

A stop 9 is a leveling detection light 4 emitted from the light source 3 and collimated by a collimator lens 5.
The aperture can be strengthened or weakened by rotating the movable piece 9a. Therefore, the spot size of the leveling detection light 4 with which the exposure area 6 is irradiated by the diaphragm 9 is changed according to the size of the area exposed by one shot, which is different in size depending on the type of the semiconductor chip. be able to.

Therefore, it is possible to avoid the problem that the detection accuracy is lowered by performing the leveling detection based on the leveling detection light irradiated on the area wider than the area to be actually exposed, and by extension, the leveling. The detection accuracy can be improved.

Since a large number of semiconductor chips of the same type may be produced or a large number of semiconductor chips of various types may be produced, the spot size can be set to an arbitrary size by a program used for automatic control by a computer. Create a mode to set and a mode to synchronize the spot size each time the size of the area to be exposed changes according to the size of the area to be exposed. It is advisable to be able to perform stable and highly accurate exposure in response to small-volume production of various types.

Further, the spot size may be changed so as to be the same as the size of the region to be exposed in synchronization with the change in the size of the region to be exposed, but it is changed with a constant offset. Alternatively, the spot size may be changed in advance, and the spot size may be changed according to the setting. Various modes of application can be considered.

FIG. 2 is a front view showing a modified example 9b of the diaphragm. The diaphragm 9b has a rectangular spot shape and a variable aspect ratio of the rectangular spot shape. As described above, when the spot shape is rectangular, the chip shape is rectangular, and the area to be exposed including one or more of the spots is also rectangular. Therefore, the leveling of the rectangular area to be exposed is most appropriate. This is because the shape of the spot of the leveling detection light that is suitable for detection is rectangular.

Further, the aspect ratio of the rectangular spot can be changed because the aspect ratio of the chip is not constant but varies depending on the product type, and accordingly, the aspect ratio of the area to be exposed in one shot is changed. This is to make it possible to deal with the difference because a difference occurs.

In FIG. 2, 11a and 11a are rectangular shield plates which are vertically spaced from and approaching the center O in synchronization with each other, and 11b and 11b are horizontally spaced from the center O in synchronization with each other. It is a rectangular shielding plate that moves in and out. Driving the shield plates 11a, 11a, and 11b, 11
By performing the driving of b separately, the spot shape can be made rectangular and the aspect ratio can be arbitrarily changed. By using such an aperture mechanism, leveling detection can be performed with high detection accuracy regardless of the size of the exposure area and the aspect ratio.

Although the diaphragm 9 is provided between the collimator lens 5 and the exposure area 6 in the leveling detection apparatus shown in FIG. 1, it is not always necessary to do so, and the exposure area 6 and It may be provided between the condenser lens 7, the collimator lens 5 and the light source 3, or between the condenser lens 7 and the leveling detector 8. You may do it.
In short, the leveling detector 8 reflected by the exposure area 6
Spot size of the leveling detection light 4 incident on
The positions of the diaphragms 9 and 9b may be anywhere as long as the shape of the spot can be changed by the diaphragms 9 and 9b. Further, instead of changing the size of the aperture through which the light passes as the diaphragm, the strength of the diaphragm is changed by moving the diaphragms 9 and 9b along the axial direction of the leveling detection light. It can be changed. this is,
The diaphragms 9 and 9b are provided between the light source 3 and the collimating lens 5,
Alternatively, it may be provided between the condenser lens 7 and the Levesang detector 8.

[0021]

According to the leveling detection device of the stepwise movement type exposure apparatus of the first aspect of the invention, a diaphragm mechanism for changing the spot size of the leveling detection light is provided. Therefore, according to the leveling detection device of the first aspect, since the spot size of the leveling detection light can be changed by the diaphragm mechanism, the spot size of the leveling detection light is changed according to the size of the area to be exposed. As a result, it is possible to solve the conventional problem that the leveling detection is performed on the basis of the leveling detection light irradiated on a region wider than the region to be actually exposed and the detection accuracy is lowered.

According to another aspect of the leveling detection device of the stepwise movement type exposure apparatus, the diaphragm mechanism makes the shape of the spot rectangular, and the aspect ratio of the rectangular can be made variable. It is what Therefore,
According to the leveling detection device of the second aspect, since the shape of the spot can be made rectangular by the diaphragm mechanism, the shape of the spot can be made to coincide with the shape of the region to be actually exposed in the rectangular shape, and the spot can be formed. Since the aspect ratio of can be changed, the aspect ratio of the spot can be changed according to the aspect ratio of the chip. Therefore, the leveling accuracy can be further improved.

[Brief description of drawings]

1 (A) and 1 (B) show one embodiment of a leveling detection device of a sequential movement type exposure apparatus of the present invention.
(A) is a perspective view and (B) is a front view of the diaphragm.

FIG. 2 is a front view showing a modified example of a diaphragm.

FIG. 3 is a perspective view of a conventional example.

FIG. 4 is an explanatory diagram of a spot size showing a problem to be solved by the invention.

[Explanation of symbols]

 1 Leveling Stage 2 Wafer 3 Light Source 4 Leveling Detection Light 6 Exposure Area 8 Leveling Detector 9, 9b Aperture

Claims (2)

[Claims] 1. A leveling detection is performed by receiving a light source for emitting leveling detection light to a wafer mounted on a leveling stage, and receiving the leveling detection light emitted from the light source and reflected on the wafer. In a leveling detection device of a stepwise movement type exposure apparatus having a leveling detector, a stepping mechanism for changing the spot size of the leveling detection light received by the leveling detector is provided. Leveling detector for exposure equipment 2. The leveling detection device for a sequential movement type exposure apparatus according to claim 1, wherein the diaphragm mechanism has a rectangular spot shape and the aspect ratio of the rectangle is variable.