JPH02254712A - Wafer circumference aligner - Google Patents

Abstract

PURPOSE:To make it possible to sharply remove a resist from the boundary between a pattern- formed part and the circumferential part of a wafer by a method wherein the angle of the segment linking the optical axis of the image-forming lens located at the edge part of the light-emission end face of a light guide fiber, the center point of a wafer and the incidence point of the optical axis is set at the prescribed acute angle. CONSTITUTION:Strands are tied up in a bundle in such a manner that the light-emission end face 3a of a light guide fiber 3 is formed in a square. The optical axis of an image- formation lens 5 is brought in coincidence with the straight line linking the outside end part of a wafer against its center line of the light-emission end face 3a of the light guide fiber 3, the pattern forming part of the wafer 1 and the boundary 1bt between the pattern forming part of the wafer 1. Besides, the angle Q of the segment, linking the optical axis of the image-forming lens 5, the center point of the wafer 1 and the incidence point of the optical axis, is constituted in such a manner that it becomes the prescribed acute angle. Accordingly, after a light has been reflected by the wafer 1, the light reflected again by the image-forming lens 5 is not projected on the pattern forming part, and as the optical axis of the image-forming lens is located on the boundary 1bt, the boundary of the pattern forming part of the wafer 1 and its circumferential part can be exposed sharply. As a result, the resist on the circumferential part of the wafer can be removed clearly.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention is applicable to semiconductor substrates such as silicon wafers,
Or a dielectric. The present invention relates to a wafer periphery exposure apparatus for removing unnecessary resist from the periphery of a resist coated on a substrate such as a metal or an insulator through a development process.

[Prior Art] In the manufacturing process of ICs, LSIs, etc., in order to form fine patterns, a resist is applied to the surface of a silicon wafer, etc., and then exposed and developed to form a resist pattern. Processing such as ion implantation, etching, and lift-off is performed using this resist pattern as a mask.

Usually, resist is applied by a spin code method. In the spin code method, the wafer is rotated while resist is poured onto the center of the wafer surface, and the resist is applied to the wafer surface using centrifugal force. However, according to this spin code method, the resist sometimes protrudes from the periphery of the wafer and wraps around the back side of the wafer.

FIG. 3 is a partial cross-sectional view showing the resist that has gone around to the back side of the wafer, where l is the wafer, la is the resist in the pattern forming area, lb is the resist on the surface around the wafer,
lc indicates the resist that has gone around from the edge of the wafer l to the back side.The resist lc that has gone around to the back side is not irradiated in the exposure process for pattern formation, and in the case of a positive resist, it remains even after development.

FIG. 4 is a diagram showing the shape of a circuit pattern exposed on a wafer, and 10 is an orientation flat. One region indicated by T corresponds to one circuit pattern. The resist ib on the surface of the wafer periphery, in which a circuit pattern cannot be drawn correctly in most cases on the wafer periphery, and even if it can be drawn, the yield is poor, is almost unnecessary in forming the circuit pattern. Furthermore, the fourth
Even if the periphery of the wafer is exposed as shown in the figure, the resist remains after development.

Remaining unnecessary lenses 1 to 1 which have gone around from the surface and edge of the wafer periphery to the back side of the wafer periphery cause the following problems. That is, wafers coated with resist are transported through various processing steps and in various ways. At this time, the peripheral portion of the wafer may be mechanically grabbed and held, or the peripheral portion of the wafer may rub against the wall of a container such as a wafer cassette.

At this time, if unnecessary resist from the periphery of the wafer comes off and adheres to the pattern forming area of the wafer, correct pattern formation will not be possible and the yield will be lowered.

Unwanted lenses 1- remaining on the periphery of the wafer become "dust" and reduce yield, which is a serious problem especially now that integrated circuits are becoming more sophisticated and smaller.

Therefore, in order to remove unnecessary resist remaining at the periphery of the wafer even after such development, a technique of removing it by a solvent spraying method has been put into practical use.

This method involves spraying a solvent from the back side of the wafer periphery to which resist has been applied to dissolve unnecessary resist. However, with this method, the resist IC that has gone around from the edge of the wafer to the back side as shown in Figure 3 can be removed, but the unnecessary resist ib on the surface of the wafer periphery is not removed. Even if the solvent is preferably sprayed from the surface of the wafer l, not only will the problem of solvent splash occur, but also the resist 1b on the surface of the unnecessary periphery of the wafer and the mask layer for later etching, ion implantation, etc. It is not possible to remove only the unnecessary resist sharply and with good controllability at the border between the pattern forming portion and the resist la, which is a necessary resist.

Therefore, in recent years, apart from the exposure process for pattern formation, separate exposure (hereinafter referred to as wafer peripheral exposure) has been carried out in order to remove unnecessary resist at the periphery of the wafer in a development process.

FIG. 5 is a schematic explanatory diagram of the main parts of the wafer periphery fogging device that performs the above-mentioned wafer periphery exposure, in which 3 is a light guide fiber, 5 is an imaging lens, and 6 is a turntable on which the wafer l is placed and rotates. , 7 is a lamp, 8 is an elliptical condenser mirror, and 9 is a flat reflecting mirror.

The wafer 1 is rotated and the resist lb at the periphery of the wafer is irradiated with light.

When an imaging lens is provided on the output side of the light guide fiber to form an image of the output end face of the light guide fiber,
The resist can be removed more sharply at the boundary between the pattern forming area and the wafer periphery.

In addition, in an application filed by the present applicant, a proposal has been made to make even sharper resist removal obstructed by aligning the boundary with the optical axis of the lens (Japanese Patent Application No. 63-7
However, there is a risk that some of the light irradiated on the surface of the resist coated on the wafer will be reflected back to the lens, and further reflected on the surface of the lens, irradiating the resist in the pattern forming area. be.

FIG. 6 is a diagram schematically explaining a state in which an imaging lens is provided on the output end face of such a lie 1 guide fiber.

As shown in FIG. 6, the light reflected on the surface of the wafer 1 is re-reflected on the surface of the imaging lens 5 and irradiates the resist la in the pattern forming area as shown by the dotted line (hereinafter referred to as "re-reflected light"). The illuminance distribution of the re-reflected light is as shown in the figure. In the periphery exposure, if even a small amount of light is irradiated onto the pattern forming area 1a, "film peeling" of the resist may occur after development, and pattern defects may occur during etching, ion implantation, etc.

[Problems to be Solved by the Invention] As described above, by providing an imaging lens on the output side of the light guide fiber, an image of the output end face of the light guide fiber is formed, and the pattern forming area and the wafer peripheral area are imaged. The method of sharply removing the resist at the boundary between the wafer and the wafer lens has the problem that the pattern forming area is irradiated by the light re-reflected between the wafer lenses.

This invention was made to solve this problem, and it is possible to eliminate the re-reflected light between the wafer lenses from irradiating the pattern forming area, and sharply remove the resist at the boundary between the pattern forming area and the wafer periphery. The purpose of the present invention is to provide an exposure device for exposing the periphery of sea urchins.

[Means for Solving the Problems] In order to achieve the above object, the peripheral exposure device for sea urchins of the present invention includes a light guide fiber in which strands are bundled so that the output end face thereof forms a rectangle, and The optical axis of the lens coincides with or almost coincides with a straight line connecting the outer end of the output end face of the rectangular light guide fiber with respect to the wafer center line and the boundary between the pattern forming part of the wafer and the wafer peripheral part. , furthermore, the angle formed by the optical axis of the imaging lens and a line segment connecting the center point of the wafer and the incident point of the optical axis is
It is configured to form a predetermined acute angle.

[Function] With the above configuration, after being reflected by the wafer,
The light reflected from the imaging lens does not illuminate the pattern formation area, and since the optical axis of the imaging lens is on the boundary, the boundary between the pattern formation area and its surrounding area on the sea urchin is exposed sharply. It is.

Resist around the wafer is clearly removed.

[Embodiment] Fig. 1 is a diagram showing a periphery exposure device for unihachi according to an embodiment of the present invention, and fig. 3a is a diagram schematically showing the main parts of the device, and (c) is a diagram for explaining the irradiation state.
3b shows the output end face of the light guide fiber 3, and by bundling each element into a rectangular shape, the cumulative exposure amount of each part of the resist lb at the periphery of the wafer is made almost uniform.
indicates an irradiation pattern irradiated from the imaging lens 5 onto the wafer l. By using a plurality of lenses, this imaging lens 5 can be a lens with a small diameter.Furthermore, if the diameter of the lens is small, the lens barrel 4 can also be made compact, and when the lens barrel 4 is controlled by a servo mechanism. has advantages. Further, the same reference numerals as in FIGS. 5 and 6 indicate the same or corresponding parts.

In addition, Figure 2 (A) is a diagram for explaining the re-reflected light and its distribution state when the optical axis intersects the wafer surface at right angles, and Figure 2 (B) is a diagram for explaining the re-reflected light and the distribution state of the light when the optical axis intersects the wafer surface at right angles. FIG. 6 is a diagram for explaining an example of re-reflection and the distribution state of the light.

In FIG. 1, when the wafer 1 is rotated by the rotation of the turntable 6, the irradiation pattern 3b follows the edge of the wafer 1 and exposes the unnecessary resist lb at the periphery of the wafer once by a servo mechanism (not shown). At this time, the angle formed by the optical axis of the imaging lens located at the end of the output end surface 3a of the light guide fiber 3 and the line segment connecting the center point of the wafer and the incident point of the optical axis is a predetermined acute angle (angle It is tilted so that the angle is θ). Therefore, as shown in Figure 2 (a), the re-reflected light between the wafer lenses is distributed from the wafer periphery to the outside, and does not irradiate the resist la in the pattern forming area. Since the optical axis of the good lens was set to be at the boundary 1bt between the resist 1a in the pattern forming area and the unnecessary resist 1b in the peripheral area,
Sharp resist removal is possible.

[Effects of the Invention] As explained above,5 according to the periphery exposure apparatus of the present invention, when the reflected light on the wafer is re-reflected by the imaging lens, the pattern forming area of the wafer is not irradiated and Since the optical axis of the imaging lens is located at the boundary between the pattern forming area and the peripheral area, the resist can be removed by sharp exposure, and there is no "film peeling" of the resist at the pattern forming area.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the periphery exposure device for UNI-Hachi according to an embodiment of the present invention, (a) is a diagram showing the overall outline of the periphery exposure device for uni-hachi, and (b) is a diagram showing the main parts of the device. A diagram showing the outline, Figure 382 (C) is a diagram for explaining the irradiation state, and Figure 382 (B) explains the re-reflected light and the distribution state of the light when the optical axis intersects at right angles to the wafer surface. Figure (B) is a diagram for explaining the re-reflection and the distribution of light in the embodiment shown in Figure 1, and Figure 3 is a diagram showing the resist that has gone around to the back side of the wafer. FIG. 4 is a diagram showing the shape of the circuit pattern exposed on the wafer. FIG. FIG. 6 is a diagram schematically explaining a state in which an imaging lens is provided on the output end face of such a light guide fiber. In the figure. 1: Wafer 1a: Resist in the pattern forming area 1b: Resist on the periphery of the wafer lc: Resist that has gone around from the edge of the wafer to the back side Image lens 6: Turntable 7: Lamp 8: Elliptical condenser mirror 9: Plane reflector Representative Patent attorney 1) Haru Kitatake (A) (C) Figure 1 Figure 1 (A) (B) Figure 2 Figure Figure Figure No. V2-2 Akinari's remains p.

Claims (1)

[Claims] A rotation stage on which a wafer coated with resist is placed and rotates the wafer, a light guide fiber that guides and irradiates light from a lamp to the peripheral area of the rotating wafer, and a light guide fiber on the output side of the light guide fiber. In a wafer peripheral exposure apparatus having an imaging lens provided with
The strands of the light guide fiber are bundled so that the output end surface thereof is square, and the optical axis of the imaging lens is aligned with the end of the output end surface of the rectangular light guide fiber outside the wafer center line. , a line segment that coincides with or almost coincides with a straight line connecting the boundary between the pattern forming part of the wafer and the peripheral area of the wafer, and further connects the optical axis of the imaging lens, the center point of the wafer, and the incident point of the optical axis. A wafer peripheral exposure apparatus characterized in that the angle formed by the wafer periphery is configured to be a predetermined acute angle.