JP2000039558A - Illuminator for spherical object - Google Patents

Abstract

PROBLEM TO BE SOLVED: To remove an effect of diffraction for an illuminator making a spherical object an illumination object and to enhance resolution and the depth of the focus of the illuminator for the spherical object (hereafter illuminator). SOLUTION: The illuminator consists of a light source part 1, a collimate lens 2, a rotary elliptic mirror 6, a spherical semiconductor 4 respectively making to coincide a center with the second focus F2 of the rotary elliptic mirror 6 to be arranged, a spherical microlens array 3 and a spherical mask 5. In this illuminator, luminous flux outgoing from the light source part 1 is converged on the first focus F1 of the rotary elliptic mirror 6 by the collimate lens 2, and the luminous flux outgoing from the first focus F1 is bent by a reflection surface 60, and collectively exposes nearly the whole surface of the spherical semiconductor 4 arranged on the second focus F2 through the spherical mask 5. For such a illuminator, the spherical microlens array 3 is arranged concentrically between the spherical mask 5 and the spherical semiconductor 4, and a beam divided by diffraction on the spherical mask 5 surface is functioned so as to overlap again on the spherical semiconductor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for irradiating a spherical object onto a spherical surface, and more particularly to an illumination device for a spherical object used in photolithography, which is a method of forming a pattern on an integrated circuit.

[0002]

2. Description of the Related Art Since a semiconductor exposure apparatus for realizing optical lithography is an optical apparatus, it cannot pass through without avoiding an optical phenomenon such as diffraction. Diffraction is a phenomenon in which light is transmitted in a direction different from the direction assumed in geometrical optics, and appears as "blur" of an image. One example of diffraction that poses a problem in a stepper (reduction projection type exposure apparatus) that illuminates a planar wafer is a case where light is split at the edge of a reticle pattern in the exposure optical system. As a countermeasure against such diffraction, a technique such as "proximity" in which a wafer and a mask are arranged close to each other on the order of micrometers is introduced to eliminate the influence of the diffraction.

[0003]

As a pioneer, a diffraction problem assumed by the applicant who is developing an illumination device for illuminating a spherical object is as shown in FIG. That is, if the light beam turned back on the reflecting surface 60 by the spheroidal mirror 6 constituting the illumination device as shown in FIG. Absent. However, in the above illuminating device, as shown in FIG. 2B, the light beam that is perpendicularly incident on the mask 5 is diffracted by the edge of the pattern P, and the zero-order light d0 is ±
Are divided into several-order diffracted lights d1,..., And these diffracted lights take an optical path different from the principal ray (zero-order light). Therefore,
It is expected that exposure to the spherical semiconductor 4 will be hindered. Therefore, the present invention takes a diffraction measure against an illumination device that illuminates a spherical object, eliminates the influence of diffraction, and further reduces the resolution and depth of focus of the illumination device (hereinafter, illumination device) for the spherical object. The purpose is to increase.

[0004]

In order to solve the above-mentioned problems, an illumination device according to the present invention is characterized in that a light beam emitted from a first focal point is reflected on a reflecting surface and then condensed on a second focal point. A spherical microlens array for converging a light beam split by diffraction with a mask on the spherical object with respect to a spheroidal mirror for illuminating the spherical object disposed at the second focal point; The present invention is characterized in that it is arranged between them (the invention according to claim 1).

The spherical object is an object having a spherical surface in whole or in part, and is, for example, the above-described spherical semiconductor. In addition, a ball bearing, a golf ball, or the like can be processed by the lighting device of the present invention. What is. When the mask is arranged concentrically with the spherical object, the mask is provided with a spherical surface on all or a part thereof in correspondence with the spherical object to be illuminated. The mask may be arranged at any position as long as it is between the light source unit and the spherical object. For example, the mask may be arranged between the light source unit of the illumination device and the collimator lens or between the collimator lens and the spheroid mirror.

In the above configuration, the spherical microlens array has a function of converging the light beam split by diffraction on the mask onto the spherical object, so that it is possible to prevent the pattern image from being "blurred" and the like. The resolution and depth of focus of the device can be increased.

In the above illuminating device, the pattern on the mask, each micro lens of the micro lens array, and the pattern image illuminated on the spherical object are:
A configuration corresponding to 1: 1: 1 may be adopted.
Invention described in (1).

According to this configuration, the influence of diffraction can be eliminated, and the light beam including the pattern information converges on the spherical object by the spherical microlens array.
A pattern image having a uniform intensity distribution can be printed on a spherical object.

In each of the above illumination devices, the mask and the microlens array may be respectively arranged concentrically with the spherical object (the invention according to claim 3).

According to this configuration, as compared with the case where the technique of “proximity” of a flat wafer is used, a gap for entering and exiting a spherical object into and out of the spherical microlens array and a gap between the spherical object and the spherical microlens array are provided. Since the mask can be provided, the exposure process can be performed smoothly, and the mask can be formed into a size that can be easily processed.

Further, in the above-mentioned illuminating device, the mask field of view X satisfies a relation of L ≧ X with respect to an illumination range L in which light beams corresponding to each microlens of the microlens array and contributing to image formation irradiate the mask. (The invention described in the claims).

According to this configuration, on the spherical object,
Overlap of pattern images can be avoided.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram illustrating a configuration of a lighting device according to the embodiment. As illustrated in FIG. 1, the illumination device according to the embodiment includes the light source unit 1, the collimator lens 2, the spheroid mirror 6, and the second focal point F <b> 2 of the spheroid mirror 6, each of which has its center aligned with the center. And a spherical microlens array 3 and a spherical mask 5.

In the above illuminating device, the light beam emitted from the light source unit 1 is focused by the collimator lens 2 at the first focal point F1 of the spheroid mirror 6, and the first focal point F
1 is bent at the reflecting surface 60,
Almost the entire surface of the spherical semiconductor 4 arranged at the second focal point F2 is exposed collectively through the spherical mask 5. For such an illuminating device, the spherical microlens array 3 is concentrically arranged between the spherical mask 5 and the spherical semiconductor 4, and the light divided by diffraction on the surface of the spherical mask 5,
It is configured to function to overlap on the spherical semiconductor 4 again. Due to the function of the spherical microlens array 3, it is possible to take measures against diffraction for an illumination device that targets the spherical semiconductor 4 as an illumination target.

Hereinafter, a specific configuration example of the spherical microlens array 3 will be described with reference to FIGS.
As shown in FIG. 2, the spherical microlens array 3 is formed in a hollow spherical shape, microlenses to be described later are arranged in the spherical portion 30, and front holes are respectively provided before and after in the direction of the rotation axis A of the spheroidal mirror 6. 31 and a rear hole 32 are provided.

The arrangement of the microlenses will be described with reference to FIGS. FIG. 3 is a one-side sectional view of the spherical microlens array 3 cut along a plane orthogonal to the rotation axis A of the spheroidal mirror 6 shown in FIG. 2, and FIG. 4 is a parallel plane including the rotation axis A and the spherical plane. FIG. 3 is a one-side cross-sectional view of the microlens array 3 cut. As shown in FIG. 3, the entire surface of the spherical surface 33 orthogonal to the rotation axis A is divided into 22 parts, excluding the non-use areas a and l as lenses.
Divided lens portions b to k and m to w are provided.
As shown in FIG. 4, six parts of lens units 1 to 6 are provided on a part of the spherical surface 34 along the rotation axis A.

The optical axes of the microlenses m1, m2,..., M120 formed by the intersections of the lens portions b to k, m to w and the lens portions 1 to 6 are all located at the center C of the spherical portion 30. It is configured to gather in. Then, the center C is set to the second focal point F2 of the spheroidal mirror 6.
When the spherical microlens array 3 is arranged in accordance with the above, the optical axis of each microlens is focused on the second focal point F2. Also, each lens m1, m2 ... m
The angles θ1 and θ2 that determine the incident range (irradiation range L) of the light beam incident on each of the lenses 120 are determined according to the size and shape of the circuit pattern P ′ formed on the spherical semiconductor 4, and each lens The array of m1, m2 ... m120 is also
It is determined according to the exposure range of the spherical semiconductor 4. Therefore, the arrangement method and the arrangement range of each microlens are not limited to the above configuration, and may be individually designed according to the shape of the spherical object to be illuminated and the illumination range. The holes 31 and 32 correspond to portions where the spherical semiconductor 4 does not need to be exposed (for example, an electrode extraction region), and the rear holes 32 also serve as entrances and exits of the spherical semiconductor 4.

The spherical microlens array 3 having the above configuration
As shown in FIG. 5, for example, the outer diameter φ1 is about 2.6 m.
m, the width w in the rotation axis direction is about 1.9 mm, and the diameter φ2 of the front hole 31
Is about 1.4 mm, and the diameter φ3 of the rear hole 32 is about 2 mm. This spherical microlens array 3 is desirably manufactured as a spherical shape. However, if it is difficult to integrally process the spherical microlens array 3, the lens surface may be divided into a plurality of parts and the lens surfaces may be processed and then combined.

In the hollow part 35 of the spherical microlens array 3, a spherical semiconductor 4 is arranged as shown in FIG. The spherical semiconductor 4 is made of, for example, single crystal silicon having a diameter of about 1 mm.

Next, based on FIG.
An example of the arrangement of the spherical microlens array 3 and the spherical mask 5 will be described. FIG. 7 shows patterns P, P, P... Of the spherical mask 5, microlenses m1, m2... M120 of the spherical microlens array 3 for imaging these patterns P, and the spherical semiconductor 4 is exposed. With respect to the circuit pattern images P ′, P ′,.
It is an enlarged view of a main part. As shown in the figure, the patterns P, P on the mask 5, the microlenses m10, m11 of the microlens array 3, and the pattern images P ′, P ′ exposed on the spherical semiconductor 4 are shown. , 1: 1: 1. This configuration allows a light beam which is not affected by diffraction and includes pattern information to be converged on the spherical semiconductor 4 by the spherical microlens array 3, and the pattern image P ', having a uniform intensity distribution.
P 'is to be baked.

In the above configuration, each micro lens m
The irradiation range L of the light beam incident on 1, m2.
When the mask pattern is larger than the field of view AB (X), the circuit pattern images P ′ and P ′ may overlap with each other.
It is necessary that ≧ X.

The gap g (see FIG. 6) between the spherical semiconductor 4 and the spherical microlens array 3 is about 0.5.
The spherical mask 5 is arranged at a distance of about 5 mm from the spherical semiconductor 4. Therefore, strict micro-order arrangement such as proximity to a planar wafer is not required. Also, the difficulty of the spherical semiconductor 4 in and out of the spherical microlens array 3 does not matter so that the rear hole 32 can be formed. Further, compared to the case where the proximity is diverted, the spherical semiconductor 4
There is an advantage that the mask 5 can be made large to some extent.

The light source unit 1 includes a semiconductor laser,
Various laser light sources, such as solid-state lasers, gas lasers, dye lasers, excimer lasers, and free electron lasers, or light sources such as LEDs (light emitting diodes) and other monochromatic lights, and parallel light sources that convert the beam from the light source into a parallel light beam It comprises a light beam generating means and the like. Although not shown, a driving device or the like corresponding to various lasers is connected to the light source.

Next, one lens mn of the above-mentioned spherical microlens array 3 is taken out, and its operation and effect will be described with reference to FIG. The light beam bent at the reflection surface 60 of the spheroidal mirror 6 and advanced to the edge A of the pattern P on the spherical mask 5 is split by diffraction to form a zero-order (d)
0), +1 order (d + 1), and -1 order (d-1) diffracted light. The zero-order light d0 is a micro lens m
The light is refracted by n, passes through the focal point, and reaches an image point a on the spherical semiconductor 4. The ± first-order lights d ± 1 are each refracted by the lens mn, pass through the focal point, and arrive at the image point a. Similarly, the diffracted lights divided by the diffraction at the edge B of the pattern P converge at the image point b on the spherical semiconductor 4, respectively. Therefore, the light illuminating the mask 5 can sufficiently contribute to the image formation, and a countermeasure against diffraction can be applied to an illuminating device for illuminating a spherical object.

The spherical microlens array 3 can superimpose the light split by diffraction on the spherical semiconductor 4 again.
If it is arranged between 0 and the spherical semiconductor 4, its function is exhibited. Therefore, as shown in FIG. 9, in the illumination device in which the planar mask 5 is arranged between the light source unit 1 and the collimator lens 2, the spherical microlens array 3
The same operation and effect as in the above-described embodiment can be obtained even if the are arranged concentrically outside the spherical semiconductor 4. Further, as shown in FIG. 10, in a lighting device in which a hemispherical mask 5 is arranged between a collimator lens 2 and a spheroidal mirror 6, even if the spherical microlens array 3 is arranged concentrically outside a spherical semiconductor, The same operation and effect as those of the above embodiment can be obtained. In FIGS. 9 and 10, what is indicated by “8” is
It is a pinhole as a spatial filter. With this pinhole 8, the passing light beam can be shaped.

Each of the above illuminating devices is an exposure device that enables simultaneous exposure of a spherical semiconductor. A ring beam generating device capable of changing a ring diameter of a ring beam between the light source unit 1 and the collimating lens 2 is provided. By arranging the means, scanning exposure on the spherical semiconductor 4 becomes possible.
That is, as shown in FIG. 11, the ring beam generating means 7 comprises an optical fiber 70 and a conical prism 71 movable along an optical axis A thereof. The optical fiber 70 has an incident end face 70a having an inclination angle θf, and when a parallel light beam enters from the direction of the light source unit 1, the light beam enters at a predetermined incident angle θin, is refracted by the incident end face 70a, and is refracted by the optical end face 70a. After repeating skew reflection at the boundary surface between the core portion and the cladding portion, the light is emitted from the emission end face 70b as a ring beam having a divergence angle (emission angle) θout.

The conical prism 71 is disposed so as to coincide with the optical axis A of the fiber 70 with the surface having the apex angle α as the second surface 71b. The vertex angle α is shaped such that the ring beam incident on the first surface 71a is emitted substantially parallel to the optical axis A at the refraction point of the second surface 71b. When the conical prism 71 is moved away from the emission end face 70b of the fiber 70, the ring beam is incident on the first face 71a at a position higher than the optical axis A, so that the second face 7
The ring diameter of the ring beam emitted from 1b can be increased. Conversely, the conical prism 71 is connected to the fiber 7
When the ring beam is moved closer to the zero emission end surface 70b, the ring beam enters the first surface 71a at a lower position from the optical axis A, so that the ring diameter of the ring beam emitted from the second surface 71b can be reduced. . The height of incidence on the collimator lens 2 is adjusted in accordance with such reduction and enlargement of the ring diameter, and thus the angle of incidence θ on the pinhole 3.
Is adjusted. That is, as the conical prism 71 is moved toward the emission end face 70b of the optical fiber 70 for removal, the emission angle θout becomes sharper, and the ring beam reflected by the reflection surface 60 is removed from the vicinity of one pole N of the spherical mask 5 by another. Pole S
The irradiation is performed while scanning the surface of the spherical mask 5 so as to cut the surface substantially vertically.

Therefore, in the illumination device capable of performing such scanning exposure, when the light is reflected at each of the reflection points Q1, Q2... Qn of the reflection surface 60 of the spheroidal mirror (see FIG. 12), the incident angle is changed. Even if unevenness of illuminance caused by the difference in reflectance due to the difference causes a problem, the output of the light source unit 1 can be adjusted in accordance with the scanning timing to make the illuminance uniform.

[0029]

According to the first aspect of the present invention, since the spherical microlens array has a function of converging the light beam divided by diffraction by the mask on the spherical object, "blur" of the pattern image is obtained. And the like can be prevented, and the resolution and the depth of focus of the illumination device can be increased.

According to the second aspect of the present invention, similarly to the above-described aspect, the influence of diffraction can be eliminated, and the light beam including the pattern information is converged on the spherical object by the spherical microlens array. In addition, a pattern image having a uniform intensity distribution can be printed on a spherical object.

According to the third aspect of the present invention, it is possible to provide a gap for allowing the spherical object to enter and exit the spherical microlens array in the exposure step, as compared with the case where the “proximity” of the flat wafer is used. Also, the mask can be made to a size that can be easily processed.

According to the fourth aspect of the present invention, it is possible to prevent the pattern images from overlapping on the spherical object.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a lighting device of the present invention,

FIG. 2 is a perspective view of a spherical microlens array used in the lighting device;

FIG. 3 is a sectional side view of the spherical microlens array,

FIG. 4 is a sectional side view of the spherical microlens array,

FIG. 5 is a side view of the spherical microlens array,

FIG. 6 is a perspective view of the spherical microlens array.

FIG. 7 is an explanatory view showing the relationship between a spherical mask, a spherical microlens array, and a spherical semiconductor of the illumination device;

FIG. 8 is an explanatory view for explaining the operation of the device.

FIG. 9 is a configuration diagram of another lighting device,

FIG. 10 is a configuration diagram of another lighting device;

FIG. 11 is a configuration diagram of a ring beam generating unit;

FIG. 12 is a configuration diagram of a lighting device using the generation unit;

FIG. 13A is a configuration diagram of a lighting device developed by the applicant before this application, and FIG. 13B is an explanatory diagram assuming a problem of the lighting device.

[Explanation of symbols]

 AA optical axis 1 light source unit 2 collimator lens 3 spherical micro lens array 30 spherical unit 31 front hole 32 back hole 33,34 spherical surface 35 hollow portion 4 spherical semiconductor 5 mask 6 spheroid mirror 60 reflecting surface 7 ring beam generating means 70 Optical fiber 71 Conical prism 8 Spatial filter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification Symbol FI Theme Court ゛ (Reference) H01L 21/30 515B (72) Inventor Eiji Nakano ^7- ball Semiconductor 4-1-1 Minamiruyama, Nagareyama City, Chiba Prefecture Inside (72) Inventor Jiro Mukai 167, Jujimachi, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Inside Kawaguchi Optical Industry Co., Ltd. (72) Inventor Yuka Kishimoto 167, Jujiamachi, Aoba-ku, Yokohama-shi, Kanagawa Prefecture Co., Ltd. (72) Inventor Kazuhiro Iwagami 167 Jeraka-cho, Aoba-ku, Yokohama-shi, Kanagawa Prefecture F-term in Kawaguchi Optical Industry Co., Ltd. CB24

Claims (4)

[Claims] 1. A light beam emitted from a first focal point is reflected by a reflecting surface and then condensed at a second focal point, thereby forming a second light beam.
For a spheroidal mirror that illuminates a spherical object placed at the focal point, a spherical microlens array that converges a light beam split by diffraction on a mask on the spherical object is disposed between the reflection surface and the spherical object. An illumination device for a spherical object, characterized in that: 2. The method according to claim 1, wherein the pattern on the mask, each microlens of the microlens array, and the pattern image irradiated on the spherical object correspond to 1: 1: 1. An illumination device for a spherical object according to claim 1. 3. The illumination device for a spherical object according to claim 1, wherein the mask and the microlens array are arranged concentrically with the spherical object. 4. A mask field of view X has a relationship of L ≧ X with respect to an illumination range L in which a light beam corresponding to each microlens of the microlens array and contributing to image formation irradiates the mask. The lighting device for a spherical object according to claim 3.