JPH05217885A - Wafer edge exposure apparatus - Google Patents

Abstract

PURPOSE:To provide a wafer edge exposure apparatus which eliminates problems such as the occurrence of dusts or foreign materials caused by the movement of a fiber and also forms the cross section of a developed resist at the boundary of exposure with a sharp inclination. CONSTITUTION:An edge exposure apparatus is provided with an optical system for exposing a wafer 1 on which a resist 2 is applied to light and a stop 3b incorporated in the optical system. An interval which is necessary for the transfer of a wafer is established between the exit end of the optical system and the wafer, and the optical system is arranged so that the stop and a resist- applied surface of the wafer can be conjugate. The shape of the stop includes a linear portion, and the stop is arranged with its linear portion facing toward the center of the wafer. An image of the linear portion of the stop is formed on a boundary between an exposed region locating at the periphery side of the wafer and a non-exposed region locating at the interior of the wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer peripheral exposure method and apparatus in a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art A conventional wafer edge exposure apparatus is disclosed in, for example, Japanese Patent Laid-Open Nos. 58-139144 and 61-7922.
No. 7 publication.

10 to 12 are views showing a conventional example. In the conventional technique, the fiber is brought close to the upper side of the wafer to directly irradiate the wafer with light from the fiber to perform exposure, and after the exposure is completed, the fiber is allowed to escape to a position that does not interfere with the wafer transfer when the wafer is transferred.

When the fiber is thus brought close to the upper side of the wafer for direct exposure, the cross-sectional shape of the resist edge portion after development has a gentle inclination as shown in FIG. The reason why the sectional shape becomes like this is that the shape of the exposure light flux is a circle as shown in FIG. 10, and the illuminance distribution is as shown in FIG. 11a.
As shown in Fig. 10, the center of the circle is highest and becomes lower toward the periphery, and the other is due to the difference in the length of exposure time on the wafer as shown in a and b of Fig. 10. is there. Effectively, the product of the illuminance distribution and the exposure time is effective, so the integrated exposure amount is as shown in FIG. 11b. When the cross-sectional shape of the resist is as shown in FIG. 12, the portion where the resist film thickness is thin becomes very fragile, and it is damaged or missing due to some mechanical shock during the process and adheres to the wafer surface as a foreign substance to form an integrated circuit. Reduces manufacturing yield.

[0005]

As described above, in the above conventional example, in order to expose the periphery of the wafer by 2 to 3 mm,
The distance from the exit end of the fiber to the wafer was about several mm. Therefore, during wafer transfer other than exposure,
It was configured so that the fiber could escape to a remote position by a movable mechanism so as not to interfere. Therefore, there are the following drawbacks. That is, when the movable mechanism is operated on the upper portion of the wafer before exposure by the stepper, foreign matter is generated from the movable portion and causes foreign matter to adhere to the wafer, leading to a reduction in yield in manufacturing integrated circuits.

Further, in the prior art, as shown in FIG. 12, there is a drawback in that the cross-sectional shape of the resist after development has a gentle inclination. When the cross-sectional shape of the resist after development becomes as shown in FIG. 12, a place where the resist film thickness is thin becomes very fragile and damaged due to some mechanical shock during the process, resulting in missing dust. As a result, foreign matter adheres to the wafer.

The present invention has been made in view of the above-mentioned drawbacks of the prior art. It is an object of the present invention to provide a peripheral exposure apparatus which eliminates the problem of dust and foreign matter generation due to fiber movement and sharpens the inclination of the developing resist cross section at the exposure boundary. To aim.

[0008]

In order to achieve the above object, according to the present invention, in a wafer peripheral exposure apparatus for exposing a peripheral portion of a resist-coated wafer by irradiating light guided by a fiber, And an optical system portion for irradiating light for exposure including a wafer, a gap necessary for wafer transfer is secured, and the diaphragm and the wafer surface are configured to have a conjugate relationship, and the diaphragm is a straight line. Have parts,
The optical system including this diaphragm is arranged between the fiber and the wafer, and the image of the linear portion of the diaphragm is arranged closer to the center of the wafer than the images of other portions, and the boundary between the exposed area and the non-exposed area around the wafer is arranged. By adjusting the above, the cross-sectional shape of the resist after development can be made to have a steep slope with less risk of damage to the resist. Further, during wafer transfer, the optical system portion that irradiates light for exposure does not interfere with wafer transfer.

[0009]

1 to 6 show an embodiment of the present invention. FIG. 1 is a diagram showing a schematic configuration of a main part of a peripheral exposure apparatus according to an embodiment of the present invention. In the figure, 1 is a wafer, 6 and 6 ′ are cassettes for storing wafers, 7 and 7 ′ are loaders and unloaders for arranging cassettes 6 and 6 ′, and 7a and 7′a are loaders 7 respectively. And an unloader drive unit for sequentially driving the unloader 7 ′ downward. Reference numeral 8 is a conveyor belt that is integrally driven and can be moved up and down, 9 is a rotatable processing stage having a vacuum suction hole (not shown),
Reference numeral 10 is a wafer centering arm that moves in and out of a predetermined position on the wafer transfer line by rotation, 11 is a controller that drives and controls the processing stage 9 and the transfer belt 8, 12 is an irradiation device including a light source, 4 Is the light source 12
Fiber 3 attached to the optical system, 3 is an optical system including a diaphragm for irradiating the light guided by the fiber 4 onto the wafer, 3
Reference numeral c is an exposure light emitting end portion, and 13 is an apparatus mount.

FIG. 2 is a view showing the details of the optical system 3 including a diaphragm. In FIG. 2, 2 is a resist, 3b is a diaphragm, and 3a.
Is an imaging optical system that makes the diaphragm and the wafer surface conjugate.

FIG. 3 is a diagram showing the shape of the diaphragm 3b.

FIG. 4 is a diagram showing a cross-sectional shape of exposure light on a wafer.

FIG. 5A is a diagram showing the illuminance at the boundary between the peripheral exposure region and the non-exposure region, and FIG. 5B is a diagram showing the integrated exposure amount.

FIG. 6 is a view showing the sectional shape of the resist after development.

The operation of one embodiment of the peripheral exposure apparatus of the present invention will be described with reference to FIG. First, a cassette 6 containing a large number of wafers 1 is placed and fixed on a loader 7. Next, the loader driving mechanism 7a operates to lower the loader 7 by a predetermined distance, and the wafer 1 to be processed is placed on the transfer belt 8. Then, the transport belt 8 is driven to transport the wafer 1 above the processing stage 9.

In the meantime, the wafer centering arm 10 is rotated from the retracted position so that the side wall 10a of the centering arm 10 is placed at a predetermined position on the wafer transfer line. Then, the wafer 1 is transferred by the transfer belt 8 and comes into contact with the side wall 10 a of the centering arm 10. This automatically causes the center of the wafer 1 and the center of the processing stage 9 to substantially coincide with each other.

In this state, the transfer belt 8 descends, the processing stage 9 vacuum-adsorbs the wafer 1, and then moves slightly below the wafer transfer line.

The exposure of the exposure light is started by the operation of a shutter (not shown) of the light source 12, and the stage is rotated to perform a predetermined exposure on the peripheral portion of the wafer 1.

When the predetermined exposure of the peripheral portion of the wafer is completed, the transfer belt 8 is lifted, the wafer 1 is placed on the transfer belt 8 again, and the vacuum suction of the processing stage 9 is released. Then, the conveyor belt 8 conveys the wafer 1 and carries it into the cassette 6'mounted and fixed on the unloader 7 '. Thus, the wafer edge exposure of this embodiment is completed.

At this time, there is a space of 10 mm or more between the exposure light emitting end 3c and the processing stage 9, and even if the conveyor belt 8 moves up by several mm when the wafer 1 is conveyed, the exposure light emitting end 3c remains on the wafer. It does not hinder the transportation.

FIG. 2 is a diagram showing details of the optical system 3.

The light emitted from the fiber 4 is the diaphragm 3b.
An image is formed on the wafer 1 by the imaging optical system 3a.

In the present invention, as shown in FIG. 2, by arranging the diaphragm 3b at the exit portion of the fiber 4, the illuminance of the peripheral portion of the exposure light beam is increased. The shape of the diaphragm 3b is shown in FIG.
As shown in FIG. 4, the semi-circular shape is imaged by directing the image of the straight line portion of the semi-circle toward the center of the wafer 1, thereby increasing the length of contact with the wafer 1 as shown in FIG. As shown in FIG. 5B, when the present invention is carried out, the integrated exposure amount is the highest at the boundary between the peripheral exposed region and the non-exposed region, and the resist cross section after development is as shown in FIG. Therefore, it is possible to remove the resist at a sharp angle which is almost perpendicular to the wafer surface at the boundary.

7 to 9 are diagrams showing a second embodiment of the present invention. FIG. 7 is a diagram showing the shape of the diaphragm, and 3b 'shows an example of the shape of the diaphragm in the second embodiment.

FIG. 8A shows the exposure amount at the boundary between the peripheral exposure region and the non-exposure region when the peripheral exposure of the wafer is performed using the diaphragm 3b ', and FIG. 8B shows the integrated exposure amount. FIG. In the first embodiment, since half of the light source light amount is shielded, the light source light amount loss is large. In this embodiment, the stop has a straight line portion, and the straight line portion is separated from the fiber optical axis, and is arranged so that the fiber optical axis passes through the stop. As a result, as shown in FIG. 8, the integrated exposure amount at the boundary between the peripheral exposure region and the non-exposure region is not the maximum, but the exposure amount at the boundary of the present invention is sufficiently high and sharp as compared with the conventional example. It is possible to remove various resists. The use of the diaphragm 3b 'has an advantage that the average exposure amount in the exposure area becomes higher than that in the case of using the diaphragm 3b.

In the first and second embodiments, the peripheral exposure apparatus is described as a single system. However, the peripheral exposure apparatus is required between the time when the resist is applied to the wafer by the spin coater and the like and the development processing. Originally, an exposure process for manufacturing a semiconductor device is an important process by an exposure apparatus for exposing a pattern in the process of manufacturing a semiconductor device. This exposure apparatus is disclosed in Japanese Patent Laid-Open No. 2-309.
As described in Japanese Laid-Open Patent Publication No. 624, it has a pre-alignment portion that aligns the position of the orientation flat with the center of the wafer. This pre-alignment section is roughly divided into a contact method of pressing the outer circumference of the wafer to align the wafer center, and the wafer is placed on an X, Y, θ stage, and the outer circumference of the wafer is measured by a non-contact sensor, X, Y, θ.
There is a non-contact method in which pre-alignment is performed by driving the stage. In the latter non-contact type pre-alignment mechanism, as in the first and second embodiments, the light source 12 for peripheral exposure, the projection optical system 3 and the like are provided X, Y, θ.
Peripheral exposure can be performed by fully considering the stroke of the stage. In this case, since pre-alignment is originally required, the processing can be performed with only an increase in the exposure time, and the mechanism itself originally has X, Y, and
Since it has a θ stage, it is very effective with a small increase in space and cost.

FIG. 13 is a flowchart showing a method of performing peripheral exposure in the exposure apparatus. First, the wafer is transferred from the wafer carrier to the pre-alignment unit by the robot hand (step 31). Then, the wafer is roughly positioned (step 32), and then the peripheral exposure is performed by the means of the first and second embodiments (step 33). Next, the position of the wafer is confirmed (step 34), the wafer is transferred from the pre-alignment unit to the wafer stage (step 35), and the mask pattern is exposed on the wafer (step 36). After the exposure, the wafer is stored in the wafer carrier (step 37).

[0028]

As described above, according to the present invention, in the wafer edge exposure apparatus, a space necessary for wafer transfer is provided between the portion for emitting light for exposure and the wafer, and the diaphragm and the resist of the wafer are provided. By arranging the optical system including the diaphragm between the fiber and the wafer so that the coated surface has a conjugate relationship, the fiber does not obstruct the wafer transfer unlike the conventional example, and thus the fiber is It is not necessary to move the wafer to a distant position. Therefore, the dust generated from the movable part does not adhere to the wafer, and the wafer periphery exposure in a clean state can be realized.

Further, the image of the linear portion of the semicircular diaphragm is directed toward the center of the wafer, and the image is formed in conformity with the boundary between the peripheral exposed portion and the non-exposed portion, whereby the sectional shape of the resist after development is formed. Can be formed into a tightly sloped shape with less risk of resist damage. As a result, it is possible to realize the peripheral exposure in which the foreign matter does not adhere to the wafer due to the damage of the resist during the wafer processing process, and it is possible to prevent the reduction in the yield in the integrated circuit manufacturing.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a main part of a wafer peripheral exposure apparatus according to the present invention.

FIG. 2 is a configuration diagram of an imaging optical system including a diaphragm.

FIG. 3 is a plan view showing the shape of a diaphragm.

FIG. 4 is an explanatory diagram of an exposure state on the peripheral portion of the wafer.

FIG. 5A is a graph showing the relationship between the illuminance and the distance from the wafer edge when the present invention is carried out, and FIG.
Is a graph showing the integrated exposure amount.

FIG. 6 is a cross-sectional view of a resist according to this example.

FIG. 7 is a plan view showing the shape of a diaphragm according to a second embodiment.

FIG. 8A is a graph showing the relationship between the illuminance and the distance from the wafer edge according to the second embodiment, and FIG. 8B is a graph showing the integrated exposure amount.

FIG. 9 is an explanatory diagram of an exposure state on the wafer edge in the second example.

FIG. 10 is an explanatory diagram of an exposure state on the wafer edge according to the related art.

FIG. 11 is an explanatory diagram of a relationship between integrated exposure and a distance from an edge according to a conventional technique.

FIG. 12 is a cross-sectional view of a resist according to the related art.

FIG. 13 is a flowchart showing a peripheral exposure method in the exposure apparatus according to the present invention.

[Explanation of symbols]

1; Wafer, 2; Cassette, 3; Optical system, 3a; Lens, 3b; Aperture, 3c; Exposure light emitting end, 4; Fiber, 6; Loader, 6 '; Unloader, 7; Loader drive section, 7 '; Unloader drive, 8; conveyor belt,
9; processing stage, 10; wafer centering arm, 10
a; Side wall of arm, 11; Controller, 12; Light source, 13; Device stand.

Claims (4)

[Claims] 1. An optical system for exposing a wafer coated with a resist, and a diaphragm incorporated in the optical system, which is required for carrying a wafer between a light emitting end of the optical system and the wafer. The optical system is arranged so that the aperture and the resist coating surface of the wafer have a conjugate relationship with each other, and the aperture has a linear portion, and the linear portion side is directed toward the center side of the wafer. A peripheral exposure apparatus, wherein the peripheral exposure apparatus is arranged and an image of a linear portion of a diaphragm is formed on a boundary between an exposure area on a wafer peripheral side and a non-exposure area on a wafer internal side. 2. The shape of the diaphragm is a shape in which a part of a substantially circular shape is linearly cut out.
Edge exposure equipment. 3. The peripheral exposure apparatus according to claim 2, wherein the shape of the diaphragm is a semicircular shape. 4. The peripheral exposure apparatus according to claim 2, wherein the shape of the diaphragm is a partial circular shape in which a part of an arc is cut out leaving the center side of the circle.