JPH0831730A - Wafer-periphery exposure device - Google Patents

Abstract

PURPOSE:To enable exposure to the inner fringe of the peripheral section of a wafer with high accuracy, to improve exposure efficiency, to prevent the adhesion of dust and damage to an emission section and to attain uniform exposure to the whole peripheral section of the wafer. CONSTITUTION:A wafer-periphery exposure device has a short arc type discharge lamp, an elliptical condensing mirror converging light from the discharge lamp, and an optical fiber bundle 21, in which a plurality of optical fibers are bundled, and an optical incident end is arranged at the place of convergence of light converged by the elliptical condensing mirror. The wafer-periphery exposure device has a light guide fiber 20, in which the end face of the optical fiber bundle 21 in an optical outgoing end 23 is formed in a rectangular shape, an aperture plate 32 being disposed to the optical outgoing end 23 of the light guide fiber 20 through a gap and having an opening 33 for transmitting light, and projection lenses 34, 35 arranged so that the aperture plate 32 is positioned at the place of a focus, and light from the optical outgoing end 23 of the light guide fiber 20 is shaped by the opening 33 for transmitting light of the aperture plate 32 and the peripheral section of a wafer is irradiated rectangularly with light from the optical outgoing end 23 by projection lenses 34, 35.

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 apparatus for performing exposure for removing unnecessary resist on the periphery of a semiconductor wafer coated with a photosensitive resist.

[0002]

2. Description of the Related Art In the manufacturing process of ICs, LSIs, etc., a circuit pattern is formed by coating a photosensitive resist on the surface of a semiconductor wafer, exposing this coating layer through a mask and developing it. Is being done.
A spin coating method is generally used as a method for applying a resist to the surface of a semiconductor wafer. In this spin coating method, a wafer is placed on a rotating table, a resist is dropped near the center of the surface of the wafer and rotated, and the resist is applied to the entire surface of the wafer by centrifugal force.

However, it is not necessary to apply a resist to the peripheral portion of the wafer. This is because when a wafer is subjected to various processing steps, it is often carried or held by utilizing the peripheral portion of the wafer, and pattern distortion is likely to occur in the peripheral portion. This is because the peripheral portion is not used as the pattern forming portion.

However, in the spin coating method, as shown in FIG.
As shown in, the resist is applied not only to the pattern forming portion 2 of the wafer 1 but also to the peripheral portion 3 of the wafer 1. Furthermore, when the peripheral edge 4 of the wafer 1 is rounded, the resist protrudes from the peripheral edge 4 of the wafer 1 and further wraps around to the back surface side of the wafer 1,
The protruding portion 7 of the resist may occur.

Conventionally, such a resist protruding portion 7 is used.
Although a spin coating method has been proposed in which the problem does not occur, the resist is applied to the peripheral portion 3 of the wafer 1 even in this method. If such unnecessary resist, that is, the resist coating layer 6 on the peripheral portion 3 of the wafer 1 and the resist protruding portion 7 protruding from the peripheral edge of the wafer 1 are left as they are, various problems occur. This problem is remarkable when a positive resist is used.

That is, as the positive type resist, one made of a phenol novolac-quinone azide resin is usually used. However, since the phenol novolac-quinone azide resin is generally hard and brittle, the treatment During the process, when a mechanical shock is applied to the peripheral portion 3 of the wafer 1 by gripping the peripheral portion 3 for transferring the wafer 1 or rubbing the peripheral portion 3 during the transfer, the wafer 1 This is because a part of the resist coating layer 6 in the peripheral portion 3 may be lost, and this may become dust and have a bad influence. In particular,
When the protruding portion 7 of the resist is missing and adheres to the surface of the wafer 1 during the transfer of the wafer 1, the adhered portion is not etched, and a circuit pattern having a desired shape cannot be formed. However, the deposit may act as a mask during ion implantation, which may impede necessary ion implantation and reduce the yield. Further, when high-energy and high-concentration ion implantation is performed, resist cracks may occur due to thermal stress generated from the periphery of the wafer during ion implantation. It has been confirmed that this resist crack is generated from an irregular portion or a flawed portion of the resist coating layer 6 in the peripheral portion 3 of the wafer 1 and runs toward the center of the wafer 1.

In order to maintain a high yield density and high integration of semiconductor devices and to maintain the yield, the problem is to replace the exposure method using the conventional contact type or 1: 1 projection type aligner with the reduction projection type exposure. It is extremely important in the background that the method has been adopted and, along with it, the use of a positive resist has become obligatory in place of the negative resist that has been mainly used as a pattern forming material in the past. is there. For example, a high-density semiconductor element is subjected to a step of hardening by ultraviolet irradiation during the processing step in order to enhance heat resistance and plasma resistance of the resist. However, when there is a residual resist, the residual resist fragments are further scattered by performing the hardening process, which causes a bad influence on the pattern formation.

For the above reasons, the wafer 1 is generally used.
The unnecessary resist applied to the peripheral portion 6 is removed. As a method of removing unnecessary resist,
A solvent injection method is known in which a solvent is injected from the back surface side of the wafer 1 to dissolve and remove unnecessary resist. However,
In this method, the resist protruding portion 7 protruding from the peripheral edge 4 of the wafer 1 is removed, but the resist coating layer 6 on the peripheral portion 3 of the wafer 1 is not removed. Therefore, in order to remove the resist coating layer 6 on the peripheral portion 3 of the wafer 1 as well, it is necessary to spray the solvent from the front surface side of the wafer 1. In this case, the resist coating layer 5 of the pattern forming portion 2 is applied. There is a problem in practical use because it has an adverse effect.

Therefore, recently, separately from the exposure step of the resist coating layer 5 of the pattern forming portion 2 on the wafer 1, the resist coating layer 6 of the peripheral portion 3 of the wafer 1 is exposed by a wafer peripheral exposure device. This resist coating layer 6
Is used in the developing process.

FIG. 8 is an explanatory view showing a state in which the peripheral portion 3 of the wafer 1 is exposed by the conventional wafer peripheral exposure apparatus. This wafer peripheral exposure apparatus irradiates the peripheral portion 3 of the wafer 1 with the light guided from the light source device (not shown) to the emitting portion 9 by the light guide fiber 8 made of quartz, and rotates the wafer 1. The entire peripheral portion 3 is exposed. L is a light irradiation region in the peripheral portion 3 of the wafer 1.

However, in the above-described wafer edge exposure apparatus, as shown in FIG. 9, the light from the emitting portion 9 of the light guide fiber is emitted while being spread at an angle of about ± 15 °. As shown by the curve a, as the irradiation distance increases, the irradiation intensity decreases and the exposure efficiency for the wafer 1 decreases. Therefore, it is conceivable to expose the wafer 1 in the state where the exposed surface of the wafer 1 is brought close to the tip of the light-guiding fiber emitting portion 9. However, if it is brought too close to the light-guiding fiber emitting portion 9, the light-guiding fiber emitting portion 9 will be exposed. If dust is attached or damage occurs due to contact with the wafer 1,
Further, it may interfere with the loading and unloading of the wafer 1 to and from the processing position, so that it is not possible to expose the wafers too closely.
Therefore, it is necessary to maintain a certain distance (irradiation distance) between the exposure surface and the emitting portion 9 of the light guide fiber. However, as the irradiation distance increases, the irradiation intensity decreases, and it becomes necessary to lengthen the exposure time. However, there was a problem that productivity was low and productivity was low.

Further, as shown in FIG. 10, the light irradiation area L
Since the shape is circular, it is difficult to perform uniform exposure because the outer portion 3a and the inner portion 3c of the peripheral portion 3 of the wafer 1 and the central portion 3b have different integrated exposure amounts. However, the resist coating layer 6 on the peripheral portion 3 cannot be uniformly removed by the developing process. In particular, the inner peripheral edge 3d of the peripheral portion 3 of the wafer 1, that is, the pattern forming portion 2
It is required that the resist coating layer 5 is formed on the outer peripheral edge of the resist coating layer faithfully and sharply with respect to the outer peripheral edge. Therefore, in the above wafer edge exposure apparatus, the wafer 1
Since it is difficult to expose the inner peripheral edge 3d of the peripheral portion 3 with high accuracy, the resist coating layer 6 of the peripheral portion 3 is faithfully removed from the inner peripheral edge 3d of the peripheral portion 3 in the developing process. I can't.

[0013]

SUMMARY OF THE INVENTION The present invention has been made based on the above circumstances, and an object thereof is to perform exposure with high accuracy on the inner peripheral edge of the peripheral portion of a wafer. It is an object of the present invention to provide a wafer peripheral exposure apparatus that has high exposure efficiency, does not cause damage due to adhesion or contact of dust on the emitting portion, and achieves uniform exposure over the entire peripheral portion of the wafer.

[0014]

The wafer edge exposure apparatus of the present invention comprises a short arc type discharge lamp, an elliptical focusing mirror for collecting light from the discharge lamp, and a plurality of optical fibers bundled together. A light guide in which the light incident end is arranged at the light condensing position of the light condensed by the elliptical focusing mirror, and the end face of the optical fiber bundle at the light emitting end is formed in a rectangular shape. A fiber, an aperture plate having a light transmitting opening arranged at a light emitting end of the light guide fiber through a gap, and a projection lens arranged so that a position of the aperture plate becomes a focal position. The light from the light emitting end of the light guide fiber is shaped by the light transmitting opening of the aperture plate and is applied to the peripheral portion of the wafer in a rectangular shape by the projection lens.

[0015]

According to the above structure, the light from the light emitting end of the light guide fiber is applied to the peripheral portion of the wafer in a state of being shaped by the light transmitting opening of the aperture plate, so that the peripheral portion of the wafer is protected. The inner edge can be exposed sharply with high accuracy. In addition, since the distance between the light emitting portion and the wafer can be maintained, dust is prevented from adhering to the emitting portion and damage caused by contact between the two is prevented, and the wafer is appropriately irradiated to the emitting portion. Since it can be arranged at a position where strength can be obtained, high irradiation efficiency can be obtained. Also,
By making the shape of the light irradiation area irradiated to the wafer rectangular, the integrated exposure amount is uniform in the outer part, the inner part and the central part of the peripheral part of the wafer, thereby achieving uniform exposure. .

[0016]

Embodiments of the wafer edge exposure apparatus of the present invention will be described below. FIG. 1 is an explanatory diagram showing an outline of the configuration of a wafer peripheral exposure apparatus according to the embodiment. In this wafer edge exposure apparatus, a box-shaped lamp body 10 is provided, and in the lamp body 10, a short arc type discharge lamp (hereinafter,
It is called a "lamp." ) 11, an elliptical focusing mirror 12 that reflects the light from the lamp 11 downward and focuses it, and a plate-shaped flat surface that reflects the light from the elliptic focusing mirror 12 in the lateral direction (right in the figure). A reflecting mirror 13, a shutter 14, and a filter 15 that transmits light of a specific wavelength are provided. Specifically, the elliptical focusing mirror 12 is arranged so that its mirror surface faces downward, and the lamp 11 is placed at the position of the first focus of the elliptical focusing mirror 12.
Is arranged, and the flat reflecting mirror 13 is arranged below the lamp 11 in a state of being inclined at 45 °, for example, and the shutter 14 and the filter 15 are provided on the side (right side in the figure) of the flat reflecting mirror 13. They are arranged in this order.

A cylindrical holding member 16 is provided on one surface (right surface in the figure) of the lamp body 10, and a light guide fiber 20 is connected to the holding member 16.
More specifically, the light guide fiber 20 has an optical fiber bundle 21 in which thousands of optical fibers having a diameter of 0.3 mm are bundled, and the optical fiber bundle 21 covers the outer periphery thereof. A flexible tube 24 that is flexible is provided, and both ends of the optical fiber bundle 21 are exposed from the flexible tube 24. Then, one end portion of the optical fiber bundle 21 in the light guide fiber 20 is provided with a tubular mounting member 25 having an outer diameter that matches the inner diameter of the holding member 16 and is provided so as to cover the outer circumference thereof. One end surface of the optical fiber bundle 21, that is, the light incident end 22 of the light guide fiber 20 is disposed at the light collecting position of the light from the elliptical focusing mirror 12. The mounting member 25 is fixed to the holding member 16 with screws 17.

Optical fiber bundle 21 in the light guide fiber 20
The other end of is connected to the light emitting unit 30. More specifically, as shown in FIG. 2, the light emitting portion 30 is provided with a lens barrel 31, and a tubular holding member 40 is provided at the base end of the lens barrel 31. The other end of the optical fiber bundle 21 in 20 is inserted into the cylinder of the holding member 40 via a tubular mounting member 26 having an outer diameter that matches the inner diameter of the holding member 40 and is provided so as to cover the outer periphery thereof. , The attachment member 26 is attached to the holding member 4 by the screw 41.
It is fixed at 0. An aluminum plate 27 that has been subjected to black alumite treatment is provided on the end surface of the attachment member 26. Then, as shown in FIG. 3, the end face of the optical fiber bundle 21 at the light emitting end 23 of the light guide fiber 20 is formed in a rectangular shape.

In the lens barrel 31 of the light emitting portion 30, an aperture plate 32 having a light transmitting opening 33 and two plano-convex lenses 34, 35 arranged so that their convex surfaces face each other are arranged.
And a projection lens made of. More specifically, the aperture plate 32 is arranged with a gap of, for example, 1 mm from the light emitting end 23 of the light guide fiber 20, and the position of the light transmitting opening 33 of the aperture plate 32 becomes the focus position of the projection lens. Thus, the first plano-convex lens 34 is arranged, and the second plano-convex lens 35 is arranged through the ring-shaped spacer 36. The aperture plate 32 has a rectangular shape in which the light transmission opening 33 is substantially the same as or slightly larger than the end surface of the optical fiber bundle 21 at the light emitting end 23 of the light guide fiber 20,
As shown in FIG. 4, the center of the light transmission opening 33 is arranged so as to be located on the optical axis X of the light from the light incident end 23 of the light guide fiber 20. In addition, the opening edge 33a of the light transmitting opening 33 of the aperture plate 32 is preferably formed in a linear knife edge shape.

In the above wafer peripheral exposure apparatus, the wafer 1 is arranged so that its peripheral portion 3 is located at the focal position of the projection lens. Then, the light from the lamp 11 reflected downward by the elliptical focusing mirror 12 is further laterally reflected by the plane reflecting mirror 13, and passes through the shutter 14 and the filter 15 and the light incident end 22 of the light guide fiber 20. And is incident on the optical fiber bundle 21. The incident light is guided by the optical fiber bundle 21 and ± 1 from the other end face, that is, the light emitting end 23 of the light guide fiber 20.
The light is emitted in a rectangular shape while expanding at an angle of 5 °. The light emitted in the rectangular shape is shaped by the light transmitting opening 33 of the aperture plate 32, and is radiated to the peripheral portion 3 of the wafer 1 through the projection lens. As a result, as shown in FIG. In the peripheral portion 3 of the wafer 1, a rectangular light irradiation region L having a posture in which the tangential direction of the peripheral edge of the wafer 1 is the front direction can be formed. Then, by relatively moving the light irradiation region L along the peripheral portion 3 of the wafer 1,
The entire peripheral portion 3 of the wafer 1 is exposed.

According to the above wafer edge exposure apparatus, since the light emitting end 23 of the light guide fiber 20 is out of the focus position of the projection lens, it acts as a simple rectangular light source. Light from the optical fiber 20 projects a rectangular light image of the light transmission opening 33 of the aperture plate 32 arranged at the focal position of the projection lens on the peripheral portion 3 of the wafer 1, so that the light transmission opening is formed. By forming the opening edge 33a of the ridge 33 in a strict linear shape, the inner peripheral edge 3d of the peripheral portion 3 of the wafer 1 can be exposed in a sharp linear shape with high accuracy. On the other hand, when the light guide fiber 20 is arranged so that the position of the light emitting end 23 becomes the focus position without providing the aperture plate 32 as described above, even if the light guide fiber 20 is rectangular, its sides are The shape of the end face of the optical fiber bundle 21 that is not a straight line, that is, the circular contour of each optical fiber is projected on the peripheral portion 3 of the wafer 1, so that it is sharper than the inner peripheral edge 3d of the peripheral portion 3 of the wafer 1. Cannot be exposed in a straight line.

Further, since the light emitting portion 30 is provided with the first projection lens 34 and the second projection lens 35, the light from the light emitting end 23 of the light guide fiber 20 is first
The peripheral portion 3 of the wafer 1 is irradiated with the light through the projection lens 34 and the second projection lens 35, so that the distance between the wafer 1 and the light emitting portion 30 can be maintained, and as a result,
It is possible to prevent dust from adhering to the light emitting unit 30 and damage caused by contact between the two. Moreover, since the wafer 1 can be arranged at a position where a suitable irradiation intensity can be obtained with respect to the light emitting portion 30, high irradiation efficiency can be obtained. In addition, since the light irradiation region L has a rectangular shape, the integrated exposure doses of the outer portion 3a, the inner portion 3c, and the central portion 3b of the peripheral portion 3 of the wafer 1 are uniform, which results in uniform exposure. To be achieved.

In the above, it is not always necessary to make all the opening edges of the light transmitting opening 33 of the aperture plate 32 into a strict linear shape. That is, normally, only the inner peripheral edge 3d of the peripheral portion 3 of the wafer 1 needs to be exposed sharply, and it is sufficient to form only the opening edge of the light transmitting opening 33 corresponding thereto in a strict linear shape. is there.

When the relationship between the irradiation distance and the irradiation intensity with respect to the wafer 1 was measured in the above-described wafer edge exposure apparatus, the irradiation distance was 10 mm as shown by the curve B in FIG.
It was confirmed that the maximum irradiation intensity was obtained with a certain degree.

[0025]

According to the wafer edge exposure apparatus of the present invention,
The light from the light emitting end of the light guide fiber is radiated to the peripheral portion of the wafer in a state of being shaped by the light transmitting opening of the aperture plate, so that the inner peripheral edge of the peripheral portion of the wafer can be sharpened with high accuracy. It can be exposed. Further, since the projection lens is provided, it is possible to maintain a distance between the light emitting portion and the wafer, and therefore, it is possible to prevent dust from adhering to the emitting portion and damage caused by contact between the two, and Since the wafer can be arranged at a position where a suitable irradiation intensity can be obtained with respect to the emitting portion, high irradiation efficiency can be obtained. In addition, since the light irradiation area irradiated onto the wafer has a rectangular shape, the integrated exposure doses at the outer peripheral portion, the inner peripheral portion and the central portion of the peripheral portion of the wafer become uniform, which results in uniform exposure. To be achieved.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing an outline of an example of a wafer peripheral exposure apparatus of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of a light irradiation unit.

FIG. 3 is an explanatory diagram showing a shape of an end face of an optical fiber bundle at a light emitting end of a light guide fiber.

FIG. 4 is an explanatory diagram showing a state of arrangement of aperture plates.

FIG. 5 is an explanatory view showing the shape of a light irradiation area irradiated to the peripheral portion of the wafer by the wafer peripheral exposure apparatus of the present invention.

FIG. 6 is a curve diagram showing the relationship between irradiation distance and irradiation intensity.

FIG. 7 is an explanatory diagram showing a state in which a resist is applied on the surface of a wafer.

FIG. 8 is an explanatory diagram showing a state in which the peripheral portion 3 of the wafer 1 is exposed by the conventional wafer peripheral exposure apparatus.

FIG. 9 is an explanatory diagram showing a state of light from an emission part of a light guide fiber.

FIG. 10 is an explanatory diagram showing a shape of a light irradiation region irradiated to a peripheral portion of a wafer by a conventional wafer peripheral exposure apparatus.

[Explanation of symbols]

1 Wafer 2 Pattern Forming Part 3 Peripheral Part 4 Peripheral Edge 5, 6 Resist Coating Layer 7 Overhanging Part 8 Light Guide Fiber 9 Emitting Part 10 Lamp 11 Short Arc Type Discharge Lamp 12 Elliptical Condensing Mirror 13 Plane Reflecting Mirror 14 Shutter 15 Filter 16 , 40 holding member 17, 41 screw 20 light guide fiber 21 optical fiber bundle 22 light incident end 23 light emitting end 24 flexible tube 25, 26 mounting member 27 aluminum plate 30 light emitting part 31 lens barrel 32 aperture plate 33 for light transmission Aperture 34 First Plano-Convex Lens 35 Second Plano-Convex Lens 36 Spacer

Claims (1)

[Claims] 1. A short arc type discharge lamp, an elliptical focusing mirror for collecting light from the discharge lamp, and an optical fiber bundle formed by bundling a plurality of optical fibers, wherein the light incident end is the above-mentioned. A light guide fiber, which is arranged at a light collecting position of the light collected by the elliptical focusing mirror and has a rectangular end face of the optical fiber bundle at the light emitting end, and a gap at the light emitting end of the light guiding fiber. An aperture plate having a light transmitting opening, and a projection lens arranged so that the position of the aperture plate becomes a focal position, and the light from the light emitting end of the light guide fiber is provided. Is a wafer peripheral exposure apparatus, which is shaped by a light transmitting opening of the aperture plate and is irradiated to the peripheral portion of the wafer in a rectangular shape by the projection lens.