JP2020122811A - Projection exposure device, and light shield used for projection exposure device - Google Patents

Abstract

To perform properly exposure of a wafer having orientation flat.SOLUTION: A projection exposure device for exposing a substrate on which an orientation flat part is formed, includes an illumination optical system for uniformizing illuminance of outgoing light from a light source and irradiating it to reticle, a light shield provided in the illumination optical system, and a light shield moving mechanism for moving the light shield. In the projection exposure device, the light shield has a continuous edge comprising a straight line part and a curve part, and a position of the light shield is controlled by the light shield moving mechanism corresponding to a relative positional relation between the orientation flat part and a projection range.SELECTED DRAWING: Figure 2

Description

The present invention relates to a projection exposure apparatus that exposes a pattern on a wafer by step-and-repeat and a light-shielding plate used in the projection exposure apparatus.

The projection exposure apparatus is provided with a mechanism (WEM: wafer edge masking) that does not expose a predetermined width from the edge edge when the exposure area reaches the wafer edge. In a projection exposure apparatus that requires a highly accurate exposure result, a method of providing a WEM in an optical system is selected because of measures against particles and sharpness of light-shielding boundaries.

For example, a prior art in which a wafer periphery non-exposure is performed by providing a movable light shield plate at a position conjugate with a reticle of an illumination optical system, and moving the light shield plate according to an exposure position to block a predetermined portion of light (Patent Document 1) ) Exists. Some semiconductor wafers are provided with an orientation flat to indicate the direction of the crystal axis of the wafer. The orientation flat is, for example, a straight edge portion formed by cutting out a part of the wafer (hereinafter, this portion is referred to as an orientation flat portion). The technique of Patent Document 1 could not shield the orientation flat portion.

Further, a technique of providing a light shielding member on the wafer is known. In a method of providing a light-shielding member that covers the entire circumference of the wafer on the wafer, Patent Document 2 (FIG. 8) describes that the arc-shaped peripheral portion of the wafer and the orientation flat portion are shielded simultaneously.

JP, 2011-233781, A JP, 2005-200910, A

Since the WEM that shields light on the wafer has a light-shielding member provided on the wafer, there arise problems that particles originating from the light-shielding member adhere to the wafer and the shaded boundary becomes unclear. Further, when exposing a wafer having no orientation flat, it is necessary to replace it with a light-shielding member having no straight line portion (FIG. 3 of the prior art document 2), which makes the work complicated.

Therefore, an object of the present invention is to provide a projection exposure apparatus and a projection exposure apparatus including a WEM provided in an illumination optical system, which is capable of not exposing not only an arcuate portion but also an orientation flat portion when performing peripheral non-exposure of a wafer. An object of the present invention is to provide a light shielding plate used in an exposure apparatus.

The present invention provides an illumination optical system that uniformizes the illuminance of light emitted from a light source and irradiates a reticle with the illumination optical system.
A light shield provided in the illumination optical system,
A light shielding plate moving mechanism for moving the light shielding plate,
In a projection exposure apparatus that exposes a substrate on which an orientation flat portion is formed,
The light shielding plate has a continuous edge composed of a straight line portion and a curved portion,
This is a projection exposure apparatus in which the position of the light shielding plate is controlled by a light shielding plate moving mechanism according to the relative positional relationship between the orientation flat portion and the projection range.
Further, the present invention is a light-shielding plate arranged in an illumination optical system of a projection exposure apparatus,
It is a light shielding plate having a continuous edge composed of a straight line portion and a curved portion so as to form a non-exposure region for a wafer having an orientation flat portion.
Furthermore, the present invention provides an illumination optical system that uniformizes the illuminance of the light emitted from the light source and irradiates the reticle, and a light shielding plate provided in the illumination optical system,
And a light blocking plate moving mechanism for moving the light blocking plate,
The light blocking plate moving mechanism includes a linear movement mechanism that moves the light blocking plate in and out of the optical axis of the illumination optical system, a first θ-axis mechanism that rotates the light blocking plate around the optical axis of the illumination optical system, and a linear movement mechanism. Has a second θ-axis mechanism that rotates the light shield by
The light shielding plate has a continuous edge composed of a straight line portion and a curved portion,
This is a projection exposure apparatus in which the position of the light shielding plate is controlled by a light shielding plate moving mechanism according to the relative positional relationship between the orientation flat portion of the substrate and the projection range.

According to at least one embodiment, not only the arc-shaped portion but also the orientation flat portion can be made non-exposure when the peripheral non-exposure of the wafer is performed. Note that the effects described here are not necessarily limited, and may be any one of the effects described in this specification or an effect different from them.

FIG. 1 is a diagram showing the configuration of an exposure apparatus according to an embodiment of the present invention. FIG. 2 is a front view of an example of the light shielding plate according to the embodiment. FIG. 3 is a front view of another example of the light shielding plate according to the embodiment. FIG. 4 is a front view of still another example of the light shielding plate according to the embodiment. FIG. 5 is a front view of the light shielding plate moving mechanism according to the embodiment. FIG. 6 is a cross-sectional view of the light shielding plate moving mechanism according to the embodiment. FIG. 7 is a plan view used for explaining the exposure operation. FIG. 8 is a plan view showing the relationship between the wafer and the light shielding plate.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the embodiments and the like described below are preferred specific examples of the present invention, and the contents of the present invention are not limited to these embodiments and the like.

FIG. 1 is a schematic configuration diagram of an embodiment of a projection exposure apparatus of the present invention. Note that each element in FIG. 1 is shown in a sectional view along the main optical axis, and hatching at that time is omitted. The projection exposure apparatus has a light source 1 and an illumination optical system 4 that makes the light emitted from the light source 1 illumination light of uniform illuminance. Illumination light from the illumination optical system 4 is applied to the reticle (photomask) 8 which is the original plate of the pattern. The image of the reticle 8 is projected onto the wafer 13 by the projection optical system 12.

The wafer 13 is placed on an exposure stage (workpiece chuck) 14. The exposure stage 14 is moved by the stage moving mechanism 15. The stage moving mechanism 15 and the optical system (the light source 1, the illumination optical system 4, the projection optical system 12) are supported by the mount 16.

The light source 1 is, for example, a UV lamp. Further, an elliptical mirror 2 is provided, and collects light toward the entrance of the rod lens. The rod lens 5 is supported by the rod lens support portion 6. A mercury lamp, a laser or the like may be used as the light source 1.

The illumination optical system 4 includes a rod lens 5 and a critical illumination lens group 7. The rod lens 5 is a transparent body having a polygonal cross section and functions as an illumination light uniformizing means. The illumination light uniformizing means is not limited to the rod lens, but may be an internal reflection mirror (a polygonal tube in which a plurality of mirrors are stuck inward).

The critical illumination lens group 7 magnifies the image of the exit surface of the rod lens 5 at a predetermined magnification (for example, 2 times) and irradiates the reticle 8 with the magnified image. In addition, although the critical illumination lens group 7 is not shown as a quadrangle in the drawing, it is composed of a plurality of lenses (for example, 10 lenses). Further, the illumination optical system 4 includes a light blocking mechanism (WEM) 11 described later.

The reticle 8 is a transmissive photomask on which a predetermined pattern is drawn. The reticle 8 is supported by the reticle stage 9. The reticle 8 is made of quartz glass, for example, and is a transmissive photomask on which a predetermined pattern (for example, a circuit pattern) to be transferred is drawn.

The projection optical system 12 is, for example, a Dyson optical system. In one embodiment, the magnification of the projection optical system 12 is unity.

The wafer 13 has a circular shape and a diameter of 300 mm, for example. Also, orientation flats are formed. The wafer 13 is, for example, a silicon wafer in which a photoresist (photosensitive agent) is applied on the surface of single crystal silicon. In addition to the one made of single crystal silicon, it may be made of glass, sapphire, or a compound.

The photoresist is applied not only to the pattern exposure area but also to at least a part of the peripheral portion of the wafer 13. Photoresist is a photosensitive material that forms a pattern using ultraviolet rays. The photoresist may be either a positive type or a negative type. A predetermined non-exposure region is set in the peripheral portion of the wafer 13. For example, the non-exposure region has a width of 5 mm over the entire circumference of the edge of the wafer 13. The non-exposure area is also provided in the orientation flat portion.

The exposure stage 14 sucks and holds the wafer 13. The exposure stage 14 is moved in the X, Y, and θ directions by the stage moving mechanism 15. The surface (two-dimensional plane) of the wafer 13 is defined by the X direction and the Y direction, and the rotation direction is defined by θ. The stage moving mechanism 15 performs movement for step exposure and minute movement for wafer alignment. Further, for focusing the wafer 13, a mechanism for moving in the Z direction and adjusting the tilt of the exposure stage is provided.

The projection exposure apparatus includes an exposure stage 14 and a mount 16 for installing an optical system. The alignment camera 10 is attached to the mount 16.

In one embodiment, the light shielding plate 17 is installed on the conjugate surface of the wafer 13 of the illumination optical system 4. Further, the light blocking plate 17 is located at the exit of the rod lens 5. Specifically, the exit surface of the rod lens 5 is located near the light shield plate 17.

FIG. 2 shows an example of a light blocking plate 17 for blocking light along the peripheral non-exposed region of the wafer 13. The light blocking plate 17 is made of a material similar to that of the reticle 8, for example, a quartz glass plate, and a black light blocking agent applied thereto. As will be described later, a linear movement mechanism that moves the light shielding plate in and out of the optical axis, a first θ-axis mechanism that rotates the light shielding plate around the optical axis of the illumination optical system, and a light shielding plate that rotates with respect to the linear movement mechanism. A light shielding plate moving mechanism including a second θ-axis mechanism is provided.

The light-shielding plate 17 has a semicircular cutout 18 that serves as a relief for the second θ-axis mechanism in the center portion on the inner peripheral side. The outer peripheral side is generally mountain-shaped or convex along the notch 18. The light shielding plate 17 has a first light shielding portion 19a, a second light shielding portion 19b, and a third light shielding portion 19c on the outer peripheral side. A curved edge c1 is formed from the apex a1 on the left side to the upper apex a2 on the right side in the drawing, and a linear edge s1 is formed from the apex a2 to the upper apex a3 on the right side. The first light-shielding portion 19a is configured by a continuous edge composed of the curved edge c1 and the straight edge s1.

The apex a3 and the apex b3 are at substantially the same height position, and the curved edge c3 connecting these apices a3 and b3 constitutes the third light shielding portion 19c. Further, a straight edge s2 is formed from the vertex b3 toward the vertex b2 that is located on the right side, and a curved edge c2 is formed from the vertex b2 toward the lower vertex on the right side b1. The curved edge c2 and the straight edge s2 form the second light shielding portion 19b. On the wafer 13, the length of each of the linear edges s1 and s2 is longer than the length of one exposure range in the longitudinal direction. Note that the exposure range here refers to the maximum projected image that can be exposed on the wafer 13 in one exposure shot. For example, the image of the exit surface of the rod lens 5 can be defined as the critical lens system 7 and the projection optical system 12. It is represented by a shape enlarged (or reduced) according to the magnification of.

As described above, the light shielding plate 17 has a shape symmetrical with respect to a line extending vertically through the center of the semicircular cutout 18. The first light shielding portion 19a has a function of shielding the orientation flat portion and one curved portion that is continuous with the straight edge portion, and the second light shielding portion 19b is the orientation flat portion and the other that is continuous with the orientation flat portion. Has a light-shielding function for the curved portion, and the third light-shielding portion 19c has a light-shielding function other than the orientation flat portion. The edge portion of each light shielding portion has a tapered cross section according to the NA of the illumination optical system. The taper shape is for preventing a decrease in the amount of emitted light in areas other than the non-exposed area.

FIG. 3 shows a light blocking plate 17A as a modified example of the light blocking plate 17. The same reference numerals are added to the portions corresponding to those in FIG. The light shielding plate 17A has a first light shielding portion 19aa and a second light shielding portion 19ab, and has a configuration in which the third light shielding portion 19c is omitted. In the case of this light shielding plate 17A, light shielding other than the orientation flat portion is performed by the curved edge c1 of the first light shielding portion 19aa and the curved edge c2 of the second light shielding portion 19ab.

FIG. 4 shows a shading plate 17B as a modified example of the shading plate 17. Unlike the light shielding plate 17, the light shielding plate 17B has a valley shape or a concave shape as a whole on the outer peripheral side as opposed to the notch 18. A curved edge c4 is formed from the apex d1 on the left side toward the apex toward the apex to the apex d2. The vertex d2 reaches the vertex d3 through the straight edge s3 corresponding to the orientation flat portion. Furthermore, the vertex d3
A curved edge c5 is formed to the apex d4 in an upward direction.

In the light shield plate 17B, the curved edge c4 and the straight edge s3 configure a first light shield portion 19ba, and the curved edge c5 and the straight edge s3 configure a second light shield portion 19bb. The light shielding portions 19ba and 19bb shield the orientation flat portion and a curved portion continuous to the orientation flat portion. Further, the light blocking of the orientation flat portion and the curved portion other than the curved portion continuous to the orientation flat portion is performed by the curved edges c4 and c5.

5 and 6 are a front view and a side sectional view of a light blocking plate moving mechanism that moves the light blocking plate 17, for example. As shown in FIG. 6, a light blocking plate moving mechanism is provided so as to be adjacent to the side surface of the rod lens. The light shielding plate moving mechanism has a hollow structure, and the rod lens support portion is installed in the hollow portion. The light-shielding plate moving mechanism includes a linear movement mechanism 23 that moves the light-shielding plate in and out of the optical axis, a first θ-axis mechanism that rotates the light-shielding plate around the optical axis of the illumination optical system, and a light-shielding mechanism 23 A second θ-axis mechanism that rotates the plate 17 is provided.

As shown in FIG. 5, the arc of the arcuate cutout 18 inside the light shield 17 is attached to the rotary shaft of the light shield rotation motor 20. The light shielding plate rotation motor 20 is fixed to the base plate 21. The base plate 21 is attached to the linear motion mechanism 23 by the attachment and detachment screws 22a and 22b. The light shield plate rotation motor 20 is for rotating the light shield plate 17 with respect to the linear motion mechanism 23, and constitutes a second θ-axis mechanism.

The linear motion mechanism 23 is a single-axis actuator such as a ball screw, and is a mechanism that linearly displaces the light shielding plate 17 and the light shielding plate rotation motor 20. The linear movement mechanism 23 moves the edge of the light shielding plate 17 toward or away from the optical axis of the illumination optical system 4. The linear movement mechanism 23 sets the position of the edge of the light shielding plate 17 according to the width of the non-exposure region.

The first θ-axis mechanism is a rotating mechanism that rotates the light shielding plate 17 about the optical axis of the illumination optical system. As shown in FIG. 6, a hollow motor 24 is provided, and the hollow shaft 24 is rotated by the hollow motor 24. The hollow motor 24 includes a rotary cable portion 26 such as a slip ring.

The rod lens support 6 having the rod lens 5 is installed in the hollow shaft 25. For example, the center of the hollow shaft 25 and the optical axis of the rod lens 5 are aligned with each other. The rod lens support portion 6 is fixed to the housing on the inlet side of the rod lens 5, and is supported on the outlet side by a bearing 27 provided in the hollow shaft 25. However, a cantilever structure may be used in which the rod lens 5 and the rod lens support portion 6 are supported only on the inlet side without supporting the outlet side of the rod lens 5 by the bearing 27.

A rotary stage 28 is attached to the hollow shaft 25 on the outlet side of the rod lens 5. The rotary stage 28 has a disk shape, and the tip of the hollow shaft 25 is fixed to the center position thereof. The linear movement mechanism 23 is attached to the rotary stage 28 via an attachment portion. For example, the radial direction of the rotary stage 28 and the direction of the linear movement of the linear motion mechanism 23 are matched. As described above, the second θ-axis mechanism including the light blocking plate 17 and the light blocking plate rotation motor 20 is attached to the linear motion mechanism 23. Therefore, when the hollow shaft 25 is rotated by the hollow motor 24, the rotary stage 28, the linear movement mechanism 23, the second θ-axis mechanism, and the light shielding plate 17 are integrally rotated about the optical axis of the illumination optical system.

Although the rod lens is used as the illumination light uniformizing means in this embodiment, a fly-eye lens may be used. In that case, an image forming optical system may be provided after the fly-eye lens, and a light shielding plate moving mechanism may be provided so that the light shielding plate comes to the image forming surface.

Next, the light blocking operation of the embodiment of the present invention will be described. FIG. 7 is a diagram showing a step-and-repeat exposure operation for the wafer 13. In the example of FIG. 7, exposure is performed 41 times. A single exposure range is shown as a rectangle, and a cross represents the center of exposure (the position of the optical axis).

A non-exposure area MA is set along the outer circumference of the wafer 13. An example of shading by WEM is shown in the upper left. During the exposure operation at a position where the exposure area does not cover the non-exposure area MA, the light shielding plate 17 is retracted to a position retracted from the rod lens 5.

The light-shielding plate moving mechanism performs different operations depending on whether the orientation flat portion is shielded or not. First, the operation of shielding the non-exposure area other than the orientation flat portion will be described. In this case, the second θ-axis mechanism (light-shielding plate rotation motor 20) rotates so that the third light-shielding portion 19c of the light-shielding plate 17 comes to the center on the moving axis of the linear motion mechanism 23, and thereafter, the state is changed. maintain.

At positions (exposure ranges EA1 and EA2) where the exposure area covers the non-exposure area MA, the light blocking plate 17 advances toward the rod lens 5 by the amount of blocking the non-exposure area MA and blocks a part of the illumination light. .. Further, the first θ-axis mechanism rotates according to the angle of the non-exposure area MA in EA1 and EA2. As a result, the light shielding area SA is positioned according to the exposure position (exposure area EA1, EA2,...) And the non-exposure area MA.

Next, the light shielding operation of the orientation flat portion will be described. FIG. 8 is a diagram showing an image in which the WEM (light shielding plate 17) shields the non-exposure area MA of the orientation flat portion. The shading plate 17 shown in FIG. 8 represents an image enlarged by the magnification of the illumination optical system and the projection optical system.

As shown in FIG. 7, when exposing the exposure area EA3 including the right end portion of the orientation flat portion, the second light shielding portion 19b of the light shielding plate 17 is used. That is, both the straight edge s2 and the curved edge c2 are used to simultaneously shield light from both the circular arc and the straight line.

In order to shield the non-exposure area of the exposure area EA3, the second θ-axis mechanism rotationally moves so that the second light shield portion 19b of the light shield plate 17 is placed on the rod lens 5. At this time, the angle θ1 of the first θ-axis mechanism, the distance R of the linear motion mechanism 23, and the angle θ2 of the second θ-axis mechanism are interlocked and calculated, and the second light-shielding portion 19b of the light-shielding plate 17 is appropriately positioned on the orientation flat portion. Thus, the light shielding plate 17 is moved.

Similarly, when exposing the exposure area EA5, the light shielding plate 17 is moved so that the first light shielding portion 19a of the light shielding plate 17 is appropriately positioned on the orientation flat portion. Further, when the exposure area EA4 is exposed, light is shielded by using the first light shielding portion 19a or the second light shielding portion 19b. Therefore, the linear edge s1 of the first light shielding portion 19a and the linear edge s2 of the second light shielding portion 19b are longer than the length of the long side of the exposure range EA4.

Although one embodiment of the present technology has been specifically described above, the present invention is not limited to the above-described one embodiment, and various modifications based on the technical idea of the present invention are possible. .. Further, the configurations, methods, steps, shapes, materials, numerical values, etc. mentioned in the above-mentioned embodiments are merely examples, and different configurations, methods, steps, shapes, materials, numerical values, etc. may be used as necessary. Good.

1... Light source, 4... Illumination optical system, 5... Rod lens,
8... Reticle, 10... Alignment camera, 11... Shading mechanism,
12... Projection optical system, 13... Wafer, 14... Exposure stage,
17... Shading plate, 19a... 1st shading part, 19b... 2nd shading part,
19c... 3rd light-shielding part, 20... light-shielding plate rotation motor, 23... direct-acting mechanism,
24... Hollow motor, 28... Rotation stage,
c1, c2, c3...curved edge, s1,s2...straight edge

Claims (6)

An illumination optical system that uniformizes the illuminance of the light emitted from the light source and irradiates the reticle.
A light shielding plate provided in the illumination optical system,
A light blocking plate moving mechanism for moving the light blocking plate,
In a projection exposure apparatus that exposes a substrate on which an orientation flat portion is formed,
The light-shielding plate has a continuous edge composed of a straight line portion and a curved portion,
A projection exposure apparatus in which the position of the light shielding plate is controlled by the light shielding plate moving mechanism according to the relative positional relationship between the orientation flat portion and the projection range. The projection exposure apparatus according to claim 1, wherein the length of the linear portion on the wafer is longer than the length of the projection range in the longitudinal direction. The projection exposure apparatus according to claim 1, wherein the projection exposure apparatus has two continuous edges with a center line of the light shielding plate being symmetrical. The projection exposure apparatus according to claim 1, wherein the light shielding plate has a curved edge different from the continuous edge. A light-shielding plate disposed in the illumination optical system of the projection exposure apparatus,
A light-shielding plate having continuous edges including straight and curved portions so as to form a non-exposure region for a wafer having an orientation flat portion. An illumination optical system that uniformizes the illuminance of the light emitted from the light source and irradiates the reticle.
A light shielding plate provided in the illumination optical system,
A light shielding plate moving mechanism for moving the light shielding plate,
The light-shielding plate moving mechanism moves the light-shielding plate in and out of the optical axis of the illumination optical system, and a first θ-axis mechanism that rotates the light-shielding plate around the optical axis of the illumination optical system. A second θ-axis mechanism for rotating the light shielding plate with respect to the linear motion mechanism,
The light-shielding plate has a continuous edge composed of a straight line portion and a curved portion,
A projection exposure apparatus in which the position of the light shielding plate is controlled by the light shielding plate moving mechanism according to the relative positional relationship between the orientation flat portion of the substrate and the projection range.

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