JP7054167B2 - Exposure device - Google Patents

Description

Application of Article 30, Paragraph 2 of the Patent Law Publication date: October 16, 2017 Publication: Optics & Photonics Japan 2017 Lecture Proceedings, p. 310, Optical Society of Japan

The present invention relates to an exposure apparatus for exposing the outer surface of an object to be exposed.

The main application of light exposure technology (photolithography) used in the manufacture of semiconductors is the formation of two-dimensional circuit patterns, but since the 1990s, microoptical elements, actuators, sensors, waveguides, printer heads, and various types have been used. It is also applied to the processing of microdevices having a three-dimensional three-dimensional shape such as MEMS (Micro Electro Mechanical Systems). As a main exposure apparatus in the photolithography process, a mask aligner that performs batch exposure by bringing a photomask and an exposure substrate close to each other is used. As an exposure device in a finer processed area, a stepper is used in which a mask pattern is exposed on an exposure substrate at the same magnification or reduced by a projection optical system, and an exposure area is expanded by a step-and-repeat operation by an XY stage. ing.

In ordinary lithography processing, when the mask pattern is transferred to the exposure substrate, the exposure light is irradiated perpendicularly to the exposure substrate.

In recent years, in exposure formation to a three-dimensional structure such as MEMS, a pattern is formed on the side surface of a high step structure. Further, in a three-dimensional circuit device, a pattern is exposed and formed on the side surface of the substrate in order to save space in the horizontal plane of the substrate. However, in an exposure device that irradiates an exposure substrate vertically with exposure light, there is a problem that a pattern cannot be formed depending on the shape and arrangement of the three-dimensional structure, and the intensity of the exposure light differs between the horizontal plane pattern and the side surface pattern. Therefore, there is a problem that non-uniform exposure occurs.

In order to solve such a problem, Patent Document 1 describes a method of inclining the exposure light with respect to the normal direction of the substrate surface in the exposure of a three-dimensional pattern having a three-dimensional shape. There is. According to this exposure method, it is possible to bring the exposure conditions of the horizontal plane and the slope of the three-dimensional sample close to each other.

Patent Document 2 describes a method of exposing the side surface of an exposure object by changing the optical path of the exposure light passing through the projection lens by a diffraction grating, a mirror, or the like in an exposure method using a projection optical system. Most of the conventional examples of side pattern exposure are those by an aligner including Patent Document 1, and the deterioration of the exposure pattern image due to the gap between the mask and the exposure substrate is large. Patent Document 2 shows an exposure method using a projection optical system, and can generally form a good pattern image with a deep depth of focus. Further, in implementing the exposure method, it is not necessary to tilt the substrate stage or the illumination optical system, and it is not necessary to make major changes or modifications to the structure of a normal exposure apparatus.

In addition, as an image formation on an exposed substrate surface with an inclination, it is based on the Scheimpflug principle (the principle that when the image plane and the main surface of the lens intersect on one straight line, the object surface also intersects on the same straight line). The Shineproof camera designed by the company is known.

Japanese Unexamined Patent Publication No. 2008-091793 Japanese Unexamined Patent Publication No. 2014-066818

In order to carry out the oblique exposure shown in Patent Document 1, it is necessary to tilt the light source and the illumination optical system, or to tilt the exposure substrate with respect to the exposure light. When the optical system is tilted, it tends to cause destabilization of optical performance. Further, when the exposed substrate is tilted, the structure is complicated due to the addition of the rotation mechanism to the substrate stage, which tends to cause a decrease in rigidity and a deterioration in performance.

In carrying out the exposure to the side surface of the three-dimensional sample shown in Patent Document 2, it is necessary to introduce an optical path changing element between the projection optical system and the three-dimensional sample, which imposes restrictions on the structure and arrangement of the three-dimensional sample. Further, since the optical path changing element is composed of a diffraction grating, a micromirror, or the like, the introduction of the element imposes restrictions on the configuration of the exposure apparatus and increases the cost.

On the other hand, although the method using the Scheimpflug principle is excellent in principle, it cannot be said to be practical because it requires an inclination mechanism including a mask surface.

The present invention has been made in view of the above problems, and a diffraction grid, a mirror, a prism, etc. are newly provided in the optical path from the exposure optical system to the exposure substrate without tilting the exposure optical system or the exposure substrate. It is an object of the present invention to provide an exposure apparatus capable of easily exposing a mask pattern to the outer surface of an exposure object by using tilted illumination as an illumination optical system without introducing an optical path changing means. The exposed object includes, for example, a substrate processed into a plate shape from a material such as silicon, crystal, glass, or film, a three-dimensional structure processed and formed on the substrate, and a single three-dimensional structure.

In the present invention, the illumination having an inclination angle with respect to the mask pattern is "tilted illumination", and the aperture diaphragm that realizes inclined illumination by providing an aperture outside the optical axis is "opening diaphragm for inclined illumination", and the optical axis. Means for realizing tilted lighting such as an outer aperture are referred to as "tilted lighting means".

In order to achieve the above object, the exposure apparatus of the present invention is an exposure apparatus that exposes a mask pattern to the outer surface of an object to be exposed, and includes a light source, an illumination optical system, and a projection optical system. It has tilted lighting means.

In the exposure apparatus of the present invention having the above configuration, the exposure light emitted from the light source passes through the aperture diaphragm set outside the optical axis in the illumination optical system, and then tilts the mask pattern. The image of the mask pattern illuminated by the tilt is transmitted through the projection optical system and then transferred as an exposure pattern to the outer surface of the object to be exposed by a luminous flux having a tilt angle.

According to the exposure apparatus of the present invention, in the illumination optical system, it is possible to change the tilt angle of the illumination by changing the position of the aperture stop and the distance between the optical axes. The tilt angle of the exposure light flux after transmission through the projection optical system can be changed according to the tilt angle of the illumination system, and it is possible to form an exposure pattern on the side surface according to the three-dimensional shape of the exposure target. Further, as a means for realizing tilted lighting, only the aperture diaphragm for vertical lighting, which is standard equipment in a normal illumination optical system, is changed to support tilted lighting, which is described in Patent Documents 1 and 2 described above. It is not necessary to add or change the mechanism such as the substrate stage or the tilt of the optical system, and it is not necessary to add new optical elements such as a diffraction grid, a mirror, and a prism for changing the optical path before and after the projection optical system.

Therefore, according to the present invention, the existing exposure apparatus can be used by arranging the aperture diaphragm for tilted illumination at a predetermined position off the optical axis according to the specifications of the existing exposure apparatus and the three-dimensional shape of the object to be exposed. Side exposure of the exposed object becomes possible. In the present invention, since the pattern transfer to the exposed object is performed by using the projection optical system, it is possible to form a good pattern image with a deep depth of focus as compared with the pattern transfer using the conventional aligner. Further, the configuration of the present invention is an exposure object using an existing aligner or a projection optical system without modification or modification for inclined exposure, and from a mask to an exposure object via a projection optical system. Since side exposure can be performed without adding a new optical element in the optical path leading to the above, it is possible to solve all the above-mentioned conventional problems.

Preferably, instead of the aperture diaphragm, it is possible to use an optical path selection element composed of a two-dimensional array such as a digital micromirror device in which a large number of movable micromirrors that reflect illumination light at a predetermined angle are arranged. Is.

According to the present invention, in the illumination optical system, it is possible to change the tilt angle of the illumination by changing the position of the aperture diaphragm and the distance between the optical axes. It is necessary to have multiple apertures.

Therefore, by using an optical path selection element composed of a two-dimensional array such as a digital micromirror device and electrically controlling ON / OFF of the mirror element in a predetermined region, the light reflected in the ON region is transmitted from the aperture stop. By treating it as the luminous flux of, the size and position can be arbitrarily set according to the three-dimensional shape of the object to be exposed.

Preferably, the orientation of the side surface of the exposed object and the arrangement of the aperture diaphragm of the illumination optical system are configured to face each other with the optical axis as the center. Even when two or more side surfaces having different orientations are exposed in the object to be exposed, the orientation of each side surface and the arrangement of the corresponding aperture diaphragms may be configured to face each other with the optical axis as the center.

According to the present invention, in the exposure to the side surface of the object to be exposed, a gradient light flux from the projection optical system corresponding to the direction of the side surface is required, and the illumination that irradiates the mask surface corresponding to the gradient light flux of the projection optical system. Inclined illumination from the optical system is required.

Therefore, when exposing a plurality of different sides, the orientation of each side and the arrangement of the corresponding aperture diaphragms are configured to face each other with the optical axis as the center, so that the orientations can be directed to the plurality of sides. Exposure is possible.

Preferably, the width W and the portrait L of the mask pattern are set so that the width w of the side exposure pattern exposed on the side surface of the object to be exposed satisfies the following formula (1) and the portrait l satisfies the formula (2) below. It is good to configure it.
w = β ・ W (1)
l = β ・ L ・ cosθ / cos (θ－δ) (2)
However, β is the projection magnification of the projection optical system, θ is the incident angle of the projected light of the projection optical system, and δ is the inclination angle of the side surface of the exposed object from the horizontal plane. The incident angle θ of the projected light of the projection optical system corresponds to the inclination angle of the exposure light speed with respect to the exposed object after the transmission of the projection optical system.

According to the present invention, regarding the size of the formed exposure pattern, the width W and the vertically long L of the mask pattern change depending on the magnification β of the projection lens, and the vertically long L is the incident angle θ of the projected light of the projection optical system. And it changes depending on the inclination angle δ from the horizontal plane of the side surface of the exposed object.

Therefore, the width W and the height L of the mask pattern are set so that the width w of the side exposure pattern projected on the side surface of the object to be exposed satisfies the above formula (1) and the vertically long l satisfies the above formula (2). Therefore, it is possible to project a side surface exposure pattern having a desired size and shape on the resist film on the side surface, and it is possible to freely process the side surface at an arbitrary angle including vertical.

Preferably, when two or more exposure objects are arranged on the surface of the exposure substrate, the projection of the projection optical system is performed at the minimum arrangement interval D and the vertical distance H from the upper surface of the exposure object to the lower end of the side exposure pattern. It is preferable that the incident angle θ of the light is satisfied by the following equation (3).
tanθ ≤ D / H (3)

According to the present invention, when there are a plurality of exposure objects, the exposure light flux having an inclination angle is blocked depending on the arrangement interval of the exposure objects and the distance from the upper surface to the lower end of the side exposure pattern.

Therefore, the incident angle of the projected light of the projection optical system satisfying the above equation (3) corresponding to the minimum arrangement interval D of the plurality of exposed objects and the distance H from the upper surface of the exposed object to the lower end of the side exposure pattern. By setting θ, it is possible to form a predetermined pattern on the side surface of the exposed object without blocking the exposed light beam.

Preferably, different transmittance distributions are set for two or more mask patterns by arranging fine light-shielding dot patterns which are two or more mask patterns and which are not resolved by the projection optical system of the exposure apparatus with different density distributions. Is possible.

In the present invention, the light intensity (the amount of light per unit area) on the pattern irradiation surface of the exposed object changes depending on the tilt angle in the side exposure pattern, and therefore, in the horizontal plane exposure pattern and the side exposure pattern, the light intensity of the irradiation surface is changed. The light intensity is different. Further, in a resist coater (resist coating machine) that is usually used, when a resist is applied to an exposed object having a three-dimensional pattern, the resist film thickness is often different between the horizontal surface area and the side surface area of the pattern, and the horizontal surface exposure is performed. The required exposure energy differs between the pattern and the side exposure pattern.

Therefore, in response to the difference in exposure intensity from the projection optical system and the difference in resist film thickness in the exposure formation of the horizontal plane exposure pattern and the side exposure pattern, the fine light-shielding dot pattern is introduced in the pattern surface on the mask. By giving different transmission rates to the horizontal surface exposure pattern and the side surface exposure pattern, it is possible to obtain the optimum exposure amount for each of the horizontal surface exposure pattern and the side surface exposure pattern on the outer surface of the exposed object.

In the present invention, when an exposure pattern is formed on the horizontal plane and the side surface of an exposed object, the focus position of the incident light flux from the projection optical system is the same in the pattern plane in the horizontal plane exposure pattern, but the incident light flux is the same in the side exposure pattern. The focus position is different in the pattern plane in the optical axis direction, and the in-plane exposure intensity distribution of the side exposure pattern tends to be non-uniform as compared with the horizontal plane exposure pattern.

Therefore, in response to the non-uniform exposure intensity distribution in the pattern surface projected on the exposed object, the fine light-shielding dot pattern is introduced in the mask pattern surface to control the density distribution of the fine light-shielding dot pattern. It is possible to form a transmittance distribution that cancels out the non-uniformity of the exposure intensity distribution, and to make the pattern obtained after exposure development uniform and appropriate.

Preferably, the aperture selection mechanism that allows selection of aperture apertures having different shapes and arrangements in the illumination optical system, the mask blind mechanism that allows exposure to only a specific area in the mask pattern, and the ability to move the exposed object in a horizontal plane. It has an XY stage mechanism and a Z stage mechanism that allows the exposed object to move in the vertical direction, and it is possible to individually expose the horizontal plane exposure pattern and the side surface exposure pattern of the exposed object under different exposure conditions.

In the present invention, regarding the optimum exposure condition in the horizontal plane exposure pattern and the optimum exposure condition in the side exposure pattern of the object to be exposed, the best due to the difference in the shape and arrangement of the aperture diaphragm that affects the resolution performance and the difference in the height of the pattern surface. There is a difference in the focus position and a difference in the optimum exposure amount.

Therefore, according to the configuration of the present invention, by individually exposing the horizontal plane exposure pattern and the side surface exposure pattern of the object to be exposed, it is possible to expose under the optimum exposure conditions for both patterns.

Specifically, the horizontal surface exposure pattern is exposed with the settings shown in 1 to 5 below.
1. 1. The mask blind mechanism shields the mask pattern corresponding to the side exposure pattern from light, and limits the irradiation of the mask to the mask pattern corresponding to the horizontal surface exposure pattern.
2. 2. By the XY stage mechanism, the above 1. The horizontal surface exposure pattern of the exposed object is positioned with respect to the mask pattern limited by.
3. 3. The aperture selection mechanism selects the optimum aperture aperture for the horizontal plane exposure pattern.
4. The Z stage mechanism performs best focus positioning with respect to the horizontal surface exposure pattern.
5. The exposure is performed by setting the exposure amount to the optimum value of the horizontal plane exposure pattern.

Specifically, the side exposure pattern is exposed with the settings shown in 6 to 10 below.
6. The mask blind mechanism shields the mask pattern corresponding to the horizontal surface exposure pattern from light, and limits the irradiation of the mask to the mask pattern corresponding to the side surface exposure pattern.
7. With the XY stage mechanism, the above 6. The side exposure pattern of the exposed object is positioned with respect to the mask pattern limited by.
8. The aperture selection mechanism selects the optimum aperture aperture for the side exposure pattern.
9. The Z stage mechanism performs best focus positioning with respect to the side exposure pattern.
10. The exposure is performed by setting the exposure amount to the optimum value of the side exposure pattern.

The individual exposure of the horizontal surface exposure pattern and the side surface exposure pattern shown above enables exposure under the optimum exposure conditions for both patterns, and both the horizontal surface exposure pattern and the side surface exposure pattern are better than the case where both patterns are exposed at the same time. It is possible to form various patterns.

According to the exposure apparatus of the present invention described above, it is possible to process the side surfaces constituting microdevices such as micro optical elements, actuators, sensors, waveguides, printer heads, and various MEMS having a three-dimensional three-dimensional shape. An optical, mechanical or electrical structure can be provided on the side surface at any angle including vertical.

Further, according to the exposure apparatus of the present invention, there is no need to modify or change the existing exposure apparatus for inclined exposure, and a new optical path changing means in the optical path from the exposure optical system to the exposed object. It is possible to expose the side surface of the object to be exposed by simply equipping the illumination optical system of the exposure device with tilted lighting means without introducing the above, and it is possible to freely process the side surface at any angle including vertical. Become.

It is a perspective view which shows the arrangement of the exposure object which has a three-dimensional shape. It is a top view which shows the pattern exposed on the horizontal plane and the side surface of the object to be exposed. The optical principle relating to the exposure of the side exposure pattern is shown, (a) is a schematic diagram of an aligner method, and (b) is a schematic diagram of a projection exposure method. It is a schematic diagram which shows the general projection type exposure apparatus. It is a schematic diagram which shows the projection type exposure apparatus corresponding to the exposure of the side exposure pattern which concerns on embodiment of this invention. (A), (b), and (c) are schematic views for explaining the projection exposure of the side exposure pattern according to the embodiment of the present invention. The relationship between the exposure pattern of the exposed object and the aperture diaphragm of the illumination optical system according to the present invention is shown, (a) is a plan view of the exposure pattern, and (b) is a plan view of the aperture diaphragm. (A), (b), and (c) are outlines showing a projection type exposure apparatus corresponding to the exposure of the side exposure pattern according to the embodiment of the present invention, the shape of the mask pattern, and the shape of the side exposure pattern of the exposed object. It is a figure. It is an end view which shows the relationship between the three-dimensional shape of the exposure object which concerns on embodiment of this invention, and the oblique projection angle of a projection optical system. It shows the revolver type lighting system aperture diaphragm which concerns on 1st Embodiment of this invention, (a) is an end view, (b) is a plan view. A lighting system aperture diaphragm configured by the digital micromirror device according to the second embodiment of the present invention is shown, where (a) is an end view and (b) and (c) are schematic views. (A), (b), and (c) are a plan view of a mask pattern and an end view of an exposed object according to a third embodiment of the present invention. The plan view of the mask pattern which concerns on 3rd Embodiment of this invention is shown, (a) is a normal pattern which does not perform transmittance correction, (b) is a fine shading dot pattern for transmittance correction. (C) shows a pattern in which fine shading dot patterns are randomly arranged for transmittance correction. It shows the light intensity distribution of the exposure pattern when the exposure light flux is vertically incident on the horizontal exposure substrate which concerns on 4th Embodiment of this invention, (a) is the arrangement diagram of the projection optical system, (b) is It is a figure which shows the two-dimensional light intensity distribution by the optical simulation when the focus position is changed. It shows the light intensity distribution of the exposure pattern when the exposure light flux is incident on the side surface of the exposure object according to the 4th embodiment of the present invention with an inclination, (a) is an arrangement diagram of a projection optical system, (b). Is a diagram showing a two-dimensional light intensity distribution by optical simulation when the focus position is changed. The plan view of the exposure pattern and the mask pattern which concerns on 4th Embodiment of this invention is shown. FIG. The mask pattern corrected by the density control of the fine light-shielding dot pattern is shown. The mask blind mechanism according to the 5th Embodiment of this invention is shown, the figure (a) is a front view which shows the projection type exposure machine which incorporated the mask blind mechanism, and the figure (b) is a mask blind mechanism. It is a plan view. It is a figure for demonstrating the exposure method which concerns on 5th Embodiment of this invention. The mask pattern plan view used in the case of forming in the above, (c) shows the mask pattern plan view used in the case of separately exposing the horizontal plane exposure pattern and the side surface exposure pattern according to the fifth embodiment. It is a schematic diagram showing the relationship between the mask pattern and the mask blind setting in the case where the horizontal plane exposure pattern and the side surface exposure pattern according to the fifth embodiment of the present invention are formed by different exposures, and FIG. Corresponding mask blind setting, (b) shows the mask blind setting corresponding to the exposure of the horizontal plane pattern.

Hereinafter, embodiments of the exposure apparatus according to the present invention will be described with reference to the drawings.

<Object to be implemented>
First, the exposed object of the exposure apparatus of the present embodiment will be described with reference to FIG. FIG. 1 illustrates a three-dimensional structure 101 formed on the exposed substrate 100. The objects to be exposed are the upper surface of the three-dimensional structure 101, the side surfaces around the upper surface, and the substrate surface of the exposed substrate 100. A resist film is applied to the entire surface of the three-dimensional structure 101 and the exposure substrate 100. The exposure apparatus of the present embodiment processes the upper surface, the side surface, and the surface of the exposure substrate 100 of the three-dimensional structure 101.

FIG. 2 shows a top view of four of the three-dimensional structures 101 taken out. The pattern exposed and formed by the exposure apparatus of the present embodiment is shown by a rectangular gray region. Each exposure pattern includes a top exposure pattern 102E formed on the upper surface of the three-dimensional structure 101, side exposure patterns 102A, 102B, 102C, 102D formed on the side surface, and a bottom exposure formed on the surface of the exposure substrate 100. It is a pattern 102F.

The shape of the three-dimensional structure 101 shown in FIGS. 1 and 2 is merely a convenient example for explaining the aspect of the side surface to be exposed. It can be applied to the processing of the side surface of an exposed object of any shape. Further, the exposure apparatus of the present embodiment is not limited to an inclined surface such that the side exposure patterns 102A, 102B, 102C, 102D shown in FIG. 2 are formed, but an arbitrary inclined surface including a vertical surface, a curved surface, a stepped surface, etc. Can be exposed. Further, the resist film applied to the exposed object may be either a positive resist in which the exposed portion disappears in development or a negative resist in which the exposed portion remains in development.

<Overview of exposure equipment and exposure method>
Next, with respect to the exposure apparatus and the exposure method relating to the exposure to the side surface of the three-dimensional structure 101, the difference between the generally used aligner method and the projection optical method according to the embodiment of the present invention is shown with reference to FIG. I will explain while. FIG. 3A shows a mask pattern formed on the mask 20 transferred and exposed on the side surface 103a of the exposure object 103 by tilted illumination in the aligner method. FIG. 3B shows a mask pattern formed on the mask 20 transferred and exposed on the side surface 103a of the exposure object 103 by tilted illumination in the projection optical method.

In the mask 20, a light-shielding region 21 and a transmitted light region 22 of a chromium thin film are formed on a transparent substrate such as glass or quartz, and various mask patterns 23 are formed by combining both.

In any of FIGS. 3A and 3B, diffracted light is generated in the lower right direction of FIGS. 3A and 3B from the mask pattern 23 irradiated by the inclined illumination. The luminous flux shown by the thick line in the figure is the 0th-order diffracted light traveling straight, and ± 1st-order diffracted light, ± 2nd-order diffracted light, ± 3rd-order diffracted light, and the like are generated around the light flux according to the shape of the mask pattern 23.

In the aligner method shown in FIG. 3A, the exposed object 103 is placed close to the mask 20, and the image of the mask pattern 23 transferred to the side surface 103a of the exposed object 103 is blurred due to the spread of diffracted light. It becomes a thing. On the other hand, in the projection optical method shown in FIG. 3B, the diffracted light from the mask 20 is taken into the opening of the projection optical system 50 and focused toward the side surface 103a of the exposure object 103. Therefore, in the projection optical system method, the image of the mask pattern 23 is sharply transferred to the side surface 103a of the exposed object 103. Further, when the exposed object 103 has a position error in the left-right direction in FIG. 3, the projection optical method shown in FIG. 3 (b) has less blurring of the image than the aligner method shown in FIG. 3 (a). When a fine pattern of μm to several tens of μm is required as the exposure pattern on the side surface, the projection optical method according to the embodiment of the present invention is advantageous in addition to the resolution performance and the depth of focus.

FIG. 4 shows a configuration in which the projection optical system method according to the embodiment of the present invention irradiates an exposed object vertically, which is used in a normal exposure machine. In the figure, the illumination optical system 30 including the light source 31A, the illumination system field diaphragm 32, the illumination system aperture diaphragm 33, and the projection optical system 50 composed of the mask 20 and the projection system aperture diaphragm 55 and the like. The exposure substrate 100 is provided.

In FIG. 4, the irradiation region of the mask 20 by the light source 31A is defined by the illumination system field diaphragm 32 arranged immediately after the secondary light source 31B on which the image of the light source is formed. The NA (numerical aperture numerical aperture) of the illumination system, which indicates the degree of light collection of the light beam irradiating the mask 20, is defined by the illumination system aperture diaphragm 33. As shown in FIG. 4, since the illumination system aperture diaphragm 33 is open symmetrically with respect to the optical axis, the luminous flux toward the mask 20 is also symmetrical, and the illumination flux is perpendicular to the mask 20. The diffracted light generated from the irradiated mask pattern 23 is taken into the projection optical system 50, and the pattern image is transferred to the exposure substrate 100 by the focused light flux from the projection optical system 50. The NA of the projection system, which indicates the degree of light flux collected from the projection optical system 50 toward the exposure substrate 100, is defined by the projection system aperture stop 55.

The illumination optical system 30 and the projection optical system 50 shown in FIGS. 4 and the following are shown by two convex lenses for explaining the aspect of the optical system, but they are merely examples for convenience, and from several lenses. It also includes an optical system composed of dozens of lenses and mirrors. Similarly, in the illumination optical system 30 and the projection optical system 50 shown in FIGS. 4 and the following, the NAs of the optical systems themselves are both equal and the magnifications are both shown as 1x, but this is just an example for convenience. However, any NA and magnification are included.

The light source 31A emits exposure light for exposing the resist film on the exposure substrate 100. As the light source 31A, for example, exposure light such as a semiconductor laser, a metal halide lamp, a high-pressure mercury lamp, or an excimer laser can be used. Further, as a light source, it can be applied regardless of wavelengths such as X-rays such as extreme ultraviolet rays (EUV) and electron beams, and the effect of the present invention can be obtained.

Next, in the projection optical system method according to the embodiment of the present invention, FIG. 5 shows a configuration in which the side surface of the exposed object is exposed by tilted illumination. In the figure, the illumination system aperture diaphragm 33 is installed outside the optical axis, and the luminous flux from the illumination optical system 30 toward the mask 20 has an inclination angle, and becomes inclined illumination. Diffracted light having an inclination angle is generated from the irradiated mask pattern 23, is taken into the projection optical system 50, and the pattern image is transferred to the side surface 103a of the exposed object 103 by the condensed light flux from the projection optical system 50. Will be done. The configuration of the tilted illumination system shown in FIG. 5 can be accommodated only by changing the illumination system aperture diaphragm 33 in the general projection optical system shown in FIG. FIG. 5 schematically shows a side surface on the optical axis. The actual lens diameter is sufficiently larger than the exposure area. Therefore, in the configuration of the illumination optical system 30 and the projection optical system 50 shown in the figure, the inclination angle of the light flux toward the mask 20 is the same at any illumination location on the mask 20, and the light flux toward the exposure object 103 is the same. The tilt angle is the same at any exposure location. In the embodiment of the present invention, the same applies to the figures shown in FIGS. 5 and later.

A case where the mask pattern 23 by inclined illumination according to the embodiment of the present invention is transferred to the side surface 103a of the exposed object 103 will be described with reference to FIG. FIG. 6A shows how the right end of the mask pattern 23 is illuminated by tilted illumination and transferred to the side surface 103a of the exposed object 103 via the projection optical system 50. FIG. 6B also shows how the left end of the mask pattern 23 is irradiated and transferred to the side surface 103a of the exposed object 103. Depending on the pattern width in the left-right direction on the mask 20, the left edge of the pattern is transferred lower than the right edge on the side surface 103a of the exposed object 103. FIG. 6C is a view of the pattern exposed on the side surface 103a of the exposure object 103 as viewed from the right side of the exposure object. A vertical surface exposure pattern 102G is formed on the side surface 103a of the exposure object 103 corresponding to the mask pattern 23.

<Relationship between the orientation of the side pattern and the aperture stop of the lighting system>
The relationship between the orientation of the side surface 103a of the exposed object 103 according to the present invention and the illumination system aperture stop 33 will be described with reference to FIG. In the figure, the illumination system aperture diaphragm 33 arranged outside the optical axis is on the left side with respect to the optical axis, and the direction of the side exposure pattern to be exposed is on the opposite right side. Even when two or more side surfaces having different orientations are exposed, the orientation of each side surface and the arrangement of the corresponding aperture diaphragms may be configured to face each other with the optical axis as the center.

FIG. 7 shows a specific example of the direction of the side exposure pattern and the arrangement of the illumination system aperture diaphragm. The side exposure patterns 102A, 102B, 102C, and 102D shown in FIG. 7A are obtained by exposure by tilted illumination using the side illumination system aperture diaphragms 33A, 33B, 33C, and 33D shown in FIG. 7B, respectively. Be done. Further, the top exposure pattern 102E and the bottom exposure pattern 102F shown in FIG. 7A are obtained by exposure by normal illumination using the illumination system aperture stop 33EF for the horizontal plane shown in FIG. 7B. The horizontal surface exposure pattern can be obtained by exposure not only with the horizontal aperture stop 33EF used for normal lighting but also with the side illumination aperture diaphragms 33A, 33B, 33C, 33D.

<Relationship between mask pattern and exposure pattern shape>
The relationship between the mask pattern according to the present invention and the pattern exposed on the side surface of the exposed object will be described with reference to FIG. FIG. 8A shows a side exposure pattern 102H projected and exposed on the right side surface 104a of the exposed object 104 made of a three-dimensional structure by tilted illumination by the projection optical system 50. In the figure, θ is the angle of incidence of the projected light from the projection optical system, and δ is the angle of inclination of the side surface 104a of the exposed object 104 from the horizontal plane. FIG. 8B shows the shape of the mask pattern 23, and the mask pattern 23 has a horizontal width W and a vertically long L. FIG. 8C shows the shape of the side surface exposure pattern 102H projected and exposed on the side surface 104a of the exposure object 104 as viewed from the normal direction of the pattern surface, and the side surface exposure pattern 102H has a width w and a vertical length. Have l. As shown by the following equation (2), the width W of the mask pattern 23 is expanded and contracted by the projection magnification β of the projection optical system, and becomes w in the side exposure pattern 102H. As shown in the following equation (3), the vertically long L of the mask pattern 23 is expanded and contracted by the projection magnification β of the projection optical system, and the incident angle θ of the projected light of the projection optical system and the horizontal plane of the side surface of the exposed object. Depending on the inclination angle δ from, the expansion and contraction is performed by cos θ / cos (θ − δ), and becomes l in the side exposure pattern 102H.
w = β ・ W (1)
l = β ・ L ・ cosθ / cos (θ－δ) (2)

That is, in the present embodiment, the width w and the portrait l of the side exposure pattern 102H are first determined, and then the mask 20 is obtained from the values of the width w and the portrait l based on the relationships of the above equations (1) and (2). The horizontal width W and the vertically long L of the mask pattern 23 formed in the above are calculated back. By using the mask pattern 23 having a horizontal width W and a vertical length L, it is possible to transfer the desired horizontal width w and vertically long side surface exposure pattern 102H to the side surface 104a of the exposed object 104.

<Relationship between the 3D shape of the exposed object and the oblique projection angle of the projection optical system>
The relationship between the three-dimensional shape of a plurality of exposed objects and the oblique projection angle of the projection optical system according to the present invention will be described with reference to FIG. In the plurality of exposed objects 105, 106, and 107 shown in the figure, the minimum allocation replacement interval is the interval D between the exposed objects 105 and 106. Regarding the side exposure pattern 102I of the exposure object 105, when the distance from the upper surface of the exposure object 105 to the lower end of the side exposure pattern 102I is H, it is incident on the lower end in order to expose the entire upper and lower sides of the side exposure pattern. It is required that the luminous flux reaches without being blocked by the upper end of the exposed object 106 shown on the right side of the figure. Therefore, the incident angle θ of the projected light of the projection optical system needs to satisfy the following equation (3).
tanθ ≤ D / H (3)

FIG. 8A shows a projection type exposure apparatus corresponding to the exposure of the side exposure pattern according to the embodiment of the present invention. The incident angle θ of the projected light of the projection optical system 50 corresponds to the tilted illumination angle of the illumination optical system 30 that irradiates the mask 20. Further, the tilted illumination angle corresponds to the distance between the aperture and the optical axis in the illumination system aperture diaphragm 33. The larger the distance between the aperture and the optical axis, the larger the tilted illumination angle, and the larger the incident angle θ of the projected light of the projection optical system 50 that exposes the side surface 104a of the exposure object 104. That is, in the present embodiment, as shown in FIG. 9, first, the minimum arrangement interval D of the three-dimensional shape of the exposed object 105 and the distance H to the lower end of the side exposure pattern 102I are determined, and then the above equation (3). ), The incident angle θ of the projected light is calculated back, and the arrangement of the illumination system aperture diaphragm 33 from the optical axis is determined. By using such an incident angle θ of the projected light, it is possible to expose the desired side exposure pattern 102I on the side surface 105a of the exposure target 105.

<First Embodiment>
Next, the exposure apparatus according to the first embodiment of the present invention will be described with reference to FIG. This embodiment illustrates a specific configuration of the illumination system aperture diaphragm 33 of the exposure apparatus shown in FIG. 5, and the illustration of the projection optical system 50, the projection system aperture diaphragm 55, and the exposure object 103 is omitted.

In the present embodiment, in FIG. 10A, a turntable 34 having a rotating pivot 35 outside the optical axis of the illumination optical system 30 is configured, and a plurality of installed turntables 34 on the turntable 34 shown in FIG. 10B. The lighting system aperture diaphragms 33A, 33B, 33C, 33D, 33AC, 33BD, 33G, and 33EF are configured to be selectable by the revolver method.

The aperture diaphragms 33A, 33B, 33C, 33D shown in FIG. 10B correspond to the aperture diaphragms 33A, 33B, 33C, 33D shown in FIG. 7B, and the side exposure pattern shown in FIG. 7A. It corresponds to the exposure formation of 102A, 102B, 102C, 102D. Similarly, the aperture stop 33EF shown in FIG. 10 (b) corresponds to the aperture stop 33EF shown in FIG. 7 (b), and the top exposure pattern 102E and the bottom exposure pattern 102F shown in FIG. 7 (a), respectively. Further, the aperture diaphragm 33AC shown in FIG. 10 (b) has the aperture diaphragms 33A and 33C shown in FIGS. 10 (b) and 7 (b) in one aperture diaphragm, and is shown in FIG. 7 (a). The side exposure patterns 102A and 102C shown are simultaneously exposed and formed. Similarly, the aperture diaphragm 33BD shown in FIG. 10 (b) has the illumination system aperture diaphragms 33B and 33D shown in FIGS. 10 (b) and 7 (b) in one aperture diaphragm, and is shown in FIG. 7 (b). The side exposure patterns 102B and 102D shown in a) are simultaneously exposed and formed. The lighting system aperture diaphragm 33G shown in FIG. 10B has the lighting system aperture diaphragms 33A, 33B, 33C, 33D shown in FIGS. 10B and 7B in one aperture diaphragm. The side exposure patterns 102A, 102B, 102C, and 102D shown in FIG. 7A are simultaneously exposed and formed. The horizontal surface exposure pattern can be obtained not only by exposure with the horizontal aperture stop 33EF used for normal lighting, but also by exposure with the side aperture apertures 33A, 33B, 33C, 33D, 33AC, 33BD, 33G. can. Therefore, it is possible to form an exposure of a horizontal surface exposure pattern at the same time by using an aperture diaphragm for any of the side exposure patterns shown in FIG. 10 (b).

According to the exposure apparatus of the present embodiment, the illumination optical system of a normal exposure apparatus is changed by installing a revolver type aperture stop mechanism outside the illumination optical system in response to an exposure request of a side exposure pattern. It is possible to expose the side exposure pattern without doing this. Further, even when the exposure specifications such as the inclination and arrangement of the side exposure pattern are changed due to the change of the exposure target, the exposure specifications can be easily changed by exchanging the aperture stop on the turntable. Therefore, when dealing with exposed objects having different three-dimensional structures and specifications in the mass production process, it is possible to reduce the process downtime due to changes in the illumination optical system, etc., and suppress the decrease in productivity that becomes a problem in the mass production process. It becomes.

<Second Embodiment>
Next, the exposure apparatus according to the second embodiment of the present invention will be described with reference to FIG. This embodiment illustrates a specific configuration in which the illumination system aperture diaphragm 33 of the exposure apparatus shown in FIG. 5 is configured by a digital micromirror device and can be switched to an arbitrary aperture diaphragm by electronic control. .. In FIG. 11, the projection optical system 50, the projection system aperture diaphragm 55, and the exposure object 103 shown in FIG. 5 are not shown. In the present embodiment, instead of the digital micromirror device, the optical elements are arranged in a two-dimensional matrix, and the actuator attached to each element is electrically controllable. May be good. Similarly, the elements may be arranged in a two-dimensional matrix, and each element may be configured to have a transmission area as an aperture stop by switching between a transmission function and a shielding function by electrical control.

In the present embodiment, in FIG. 11A, a digital micromirror device 36 is installed in place of the illumination system aperture diaphragm in the illumination optical system 30, and the illumination luminous flux incident from the light source 31A via the illumination system field diaphragm 32 is , When the digital micromirror device 36 is in an uncontrolled state, it is bent downward. FIG. 11B shows a plan view of the digital micromirror device 36, and has a configuration in which a large number of movable micromirrors 36a shown by small squares are arranged in a matrix. The inside of the circular secondary light source 31B shown by the broken line in the figure corresponds to the maximum luminous flux of the illumination optical system 30. In the figure, 49 movable micromirrors 36a consisting of an array of 7 rows and 7 columns are shown, but this is just an example for convenience, and the size of one mirror is around 10 μm, from several hundred thousand. It consists of millions of micromirrors.

Each movable micromirror 36a has an electrode and a support shaft (not shown), and can be tilted at a predetermined angle by individually applying a voltage. In FIG. 11A, when the voltage is not applied (control is OFF), the movable micromirror 36a does not operate, the illumination light flux incident from the left direction is reflected downward, and the mask 20 is attached via the illumination optical system 30. Irradiate. When a voltage is applied (control ON), each movable micromirror 36a tilts at a predetermined angle, and the illumination flux incident from the left direction is reflected downward 45 ° and guided to the outside of the illumination optical system 30. Therefore, only the light flux from the mirror surface to which no voltage is applied passes through the illumination optical system 30 and tilts the mask 20.

In FIG. 11C, the specific movable micromirror 36a shown in gray is controlled off in the mirror surface of the digital micromirror device 36, and only the light flux in the gray region is transmitted through the illumination optical system 30. The luminous flux reflected in the gray region has the same function as the luminous flux transmitted through the illumination system aperture diaphragm 33 shown in FIGS. 4, 5, 6, 8 and 10, and the luminous flux in the selection region shown in gray is the illumination optical system. After passing through 30, the mask surface is irradiated as inclined illumination. In FIG. 11C, a gray square area composed of one to several mirrors is selected, but this is merely an example for convenience, and the actual digital micromirror device is described above. As shown above, since it is composed of hundreds of thousands to millions of micromirrors, any shape including a circular shape can be selected as in the lighting system aperture diaphragm 33 shown in FIGS. 4, 5, 6, 8 and 10. It is possible.

In the digital micromirror device 36 having the eight types of gray square areas shown in FIG. 11 (c), the luminous flux areas 36C, 36G, 36BD, 36AC, 36D, 36B, and 36A for the side surface select the luminous flux. As a function, it corresponds to the side illumination system aperture diaphragms 33C, 33G, 33BD, 33AC, 33D, 33B, 33A shown in FIG. 10B, respectively, and the illumination light flux area 36EF for the horizontal plane shown in FIG. 11C. Corresponds to the illumination system opening diaphragm 33EF for the horizontal plane shown in FIG. 10 (b).

According to the exposure apparatus of the present embodiment, it is easy to select the illumination luminous flux by electrical control by installing the digital micromirror device 36 in the illumination optical system 30 in response to the exposure request of the side exposure pattern. It is possible to correspond to. Further, even if the exposure specifications such as the inclination and arrangement of the side exposure pattern are changed due to the change of the exposure target, the exposure specifications can be easily changed at high speed by electrical control. Therefore, when dealing with exposed objects having different three-dimensional structures and specifications in the mass production process, it is possible to reduce the process downtime due to changes in the illumination optical system and suppress the decrease in productivity that is a problem in the mass production process. It will be possible.

The digital micromirror device 36 in the present invention has a response time of several milliseconds to several tens of milliseconds for selecting a micromirror by electrical control. In an exposure machine (stepper) that divides one exposure substrate into small areas and repeatedly exposes them by a step-and-repeat method, the exposure time for each small exposure area is usually required to be around 1 second, but it is digital. By controlling ON / OFF of the micromirror device 36, it is possible to change the angle, arrangement, etc. of the inclined illumination for each small exposure area. This makes it possible to increase the productivity when producing a device having a plurality of types of structures in one exposure substrate.

<Third Embodiment>
Next, the relationship between the mask pattern and the exposure amount to the exposed object according to the third embodiment of the present invention will be described with reference to FIG. FIG. 12A shows the mask pattern 23F corresponding to the horizontal plane exposure pattern 102K of the exposure object 108 made of the three-dimensional structure, and FIG. 12B corresponds to the side exposure pattern 102L of the exposure object 108. The mask pattern 23G is shown. For convenience, both masks have the same shape and area on the mask surface.

As shown in FIG. 12 (c), the light intensity (light amount per unit area) of the exposed object 108 on the pattern irradiation surface is the light intensity I1 of the horizontal plane and the light intensity I1 of the side surface exposure pattern 102L with respect to the horizontal plane exposure pattern 102K. The light intensity I2 on the side surface is the light intensity I2 on the side surface, and the light intensity I2 on the side surface changes according to the inclination angle of the side surface exposure pattern. As shown in FIG. 12 (c), the resist (photosensitive) film thickness in the exposed object 108 is the film thickness T1 of the resist 110 in the horizontal plane region and the film thickness T2 of the resist 111 in the side surface region. Generally, the film thickness differs between the horizontal plane region and the side surface region.

In resist exposure, there is an optimum exposure amount to secure a desired pattern shape after development, but the optimum exposure amount is determined by the light intensity (light amount per unit area) on the pattern irradiation surface and the resist film thickness. .. When the mask pattern 23F shown in FIG. 12A and the mask pattern 23G shown in FIG. 12B have the same shape and the same area, the luminous flux after passing through the mask pattern is the same for both patterns. However, as shown in FIG. 12 (c), the light intensity I1 for the horizontal surface exposure pattern 102K and the light intensity I2 for the side surface exposure pattern 102L of the exposed object 108 are different. As shown in FIG. 12 (c), the resist film thickness T1 of the resist 110 in the horizontal plane region and the film thickness T2 of the resist 111 in the side surface region are different. Therefore, it is not possible to give the optimum exposure amount for each of the horizontal surface exposure pattern 102K and the side surface exposure pattern 102L in the exposure object 108.

When the optimum exposure amount differs between the horizontal plane exposure pattern and the side exposure pattern of the object to be exposed, the optimum exposure amount required for each pattern is secured by changing / correcting the transmittance of the corresponding mask pattern on the mask. It is possible to do. FIG. 13 shows various mask patterns formed on the mask 20. FIG. 13A shows a mask pattern 23 in which the transmitted light region 22H of the mask 20 is a general glass pattern, and FIGS. 13B and 13C show fine transmitted light regions 22I and 22J of each mask 20. The mask pattern 23 by the light-shielding dot pattern is shown.

The fine light-shielding dot pattern is a miniaturized chrome pattern used for the light-shielding region 21 on the mask 20, and a dot pattern having a size equal to or smaller than the limit resolution of the projection optical system is used. As a convenient example, when the NA (numerical aperture) of the projection optical system is 0.15 and the wavelength is 0.365 μm, the limit resolution is approximately 1.5 μm. Therefore, if the magnification of the projection optical system is 1 times, The dot size on the mask is about 0.5 μm × 0.5 μm to 1 μm × 1 μm. Since this dot pattern is smaller than the limit resolution of the projection optical system, the shape of the dots is not transferred or imaged on the exposed object, and the original pattern shape of the exposed object is not affected.

Since the fine light-shielding dot pattern arranged in the mask pattern 23 blocks the irradiation light to the mask 20 according to the area of the dots, it is possible to reduce the amount of light from the mask pattern 23 toward the projection optical system. By increasing or decreasing the number of dots in the mask pattern 23, it is possible to change or correct the amount of transmitted light in the mask pattern 23. In the transmitted light region 22I of FIG. 13B, the number of fine light-shielding dot patterns required for transmittance correction is uniformly arranged. The transmitted light region 22J in FIG. 13C is a random number of fine light-shielding dot patterns required for transmittance correction. In the transmitted light region 22I, diffracted light may be generated due to the pattern periodicity due to the even arrangement. Therefore, in order to avoid unnecessary pattern transfer due to diffracted light, the transmitted light region 22J by random arrangement is effective.

According to the exposure apparatus of such an embodiment, even when the exposure conditions of the horizontal plane exposure pattern and the side exposure pattern are different, the fine light-shielding dot pattern is arranged in the corresponding mask pattern and the dot density is controlled to transmit the light. The rate can be corrected and the optimum exposure amount for each exposure pattern can be secured. Therefore, it is possible to form a good exposure pattern after exposure and development. In a commonly used mask drawing device, the formation and arrangement of a dot pattern of about 0.5 μm is a standard specification, and a mask with corrected transmittance as in the present embodiment is easily available. ..

<Fourth Embodiment>
Next, the exposure apparatus according to the fourth embodiment of the present invention will be described with reference to FIGS. 14 and 15. The figure shows the projection angle of the incident luminous flux from the projection optical system and the in-plane light intensity distribution (exposure unevenness) of the exposure pattern. FIG. 14 (a) shows the arrangement of the projection optical system 50 corresponding to the exposure of the horizontal plane exposure pattern by ordinary vertical illumination, and FIG. 14 (b) shows the rectangular pattern on the mask 20 as the projection optical system 50. The two-dimensional light intensity distribution of the pattern image when transferred and imaged on the exposure substrate 100 is shown. Each figure of FIG. 14B corresponds to the two-dimensional light intensity distribution in each when the focus position of the exposure substrate 100 is shifted up and down from −250 μm to +250 μm. FIG. 15A shows the arrangement of the projection optical system 50 corresponding to the exposure of the side exposure pattern by the inclined illumination, and FIG. 15B shows the rectangular pattern on the mask 20 exposed by the projection optical system 50. The two-dimensional light intensity distribution of the pattern image when transferred and imaged on the side surface 103a of the object 103 is shown. Each figure of FIG. 15B corresponds to the two-dimensional light intensity distribution in each of the cases where the focus position of the side surface 103a of the exposed object 103 is shifted to the left and right from −250 μm to +250 μm. In calculating the two-dimensional light intensity distribution, CYBERNET's optical calculation software "CODE V" was used.

In the horizontal plane exposure pattern shown in FIG. 14B, the light intensity distribution of the pattern image due to defocus is substantially uniform in the plane, and there is little change due to defocus. Regarding the side exposure pattern shown in FIG. 15B, the light intensity distribution near the best focus is almost uniform, but the in-plane non-uniformity is remarkably expanded due to defocus. When the horizontal exposure pattern and the side exposure pattern are exposed at the same time, when the best focus position of the projection optical system 50 is aligned with the horizontal plane, the side exposure pattern is formed in the vertical direction and is inevitably affected by defocus. It will be. Therefore, when the side exposure pattern is required to have the same uniformity as the horizontal surface exposure pattern, the resolution performance of the side exposure pattern after exposure and development becomes a problem.

A method of correcting the non-uniformity of the in-plane intensity distribution of the exposure pattern by arranging the fine light-shielding dot pattern in the corresponding mask pattern will be described with reference to FIG. FIG. 16A shows the in-exposure surface intensity distribution of the exposed side surface pattern 102J at a predetermined defocus position, and FIG. 16B shows fine shading dots arranged in the transmitted light region 22k of the corresponding mask pattern 23. Shows the pattern. The transmittance of the mask pattern 23 is reduced by increasing the number of fine light-shielding dot patterns in the corresponding area in the mask pattern 23 with respect to the area having a high light intensity in the side exposure pattern 102J.

According to the exposure apparatus of the present embodiment, when the in-plane intensity distribution is non-uniform in the exposure pattern, the fine light-shielding dot pattern is arranged in the plane of the corresponding mask pattern to obtain the dot density distribution. By controlling the transmittance, the transmittance is corrected and the in-plane non-uniformity is improved, so that a good exposure pattern can be formed. This correction is not limited to the side exposure pattern, and can be applied to any exposure pattern in which in-plane non-uniformity exists, the in-plane non-uniformity is improved, and good pattern formation becomes possible.

<Fifth Embodiment>
Next, see FIGS. 17, 18, and 19 for an exposure method for separately exposing the horizontal surface exposure pattern and the side surface exposure pattern of the exposed object according to the fifth embodiment of the present invention under the respective optimum exposure conditions. I will explain while doing it. There are the following differences between the optimum exposure conditions for exposing the horizontal surface exposure pattern and the optimum exposure conditions for exposing the side surface exposure pattern.
(1) Difference in shape and arrangement of optimum aperture diaphragm (2) Difference in best focus position due to difference in height of pattern surface (3) Difference in optimum exposure amount

Differences in exposure conditions can be dealt with by separately exposing the horizontal surface exposure pattern and the side surface exposure pattern. FIG. 17 shows a mask blind mechanism 25 provided on the mask 20 so that the horizontal surface exposure pattern or the side surface exposure pattern can be exposed separately. FIG. 17A is a side view of the projection type exposure apparatus, in which the mask blind mechanism 25 is installed directly above the mask 20. FIG. 17B is a plan view in which only the mask blind mechanism 25 is taken out. In the figure, the mask 20 is indicated by a broken line, and two light-shielding blades 25XL and 25XR that can be driven in the X direction (left-right direction in the figure) are installed directly above the mask 20. Two light-shielding blades 25YU and 25YD that can be driven in the Y direction (the same vertical direction) are installed directly above the light-shielding blades 25XL and 25XR in the X direction. Each of the four light-shielding blades can be driven independently.

The mask blind mechanism 25 is a mechanism generally incorporated in a projection type exposure machine. Usually, it is used when a plurality of mask patterns having different exposure conditions are exposed in one element in an exposure such as an ASIC (Application Specific Integrated Circuit). Therefore, even in the exposure of the three-dimensional structure by the projection type exposure shown in the present invention, it is not necessary to significantly change or modify the exposure machine due to the use of the mask blind mechanism 25.

FIG. 18A is a plan view of the object to be exposed, and is composed of a top surface exposure pattern 102E and a side surface exposure pattern 102A, 102B, 102C, 102D. FIG. 18B is a plan view of the mask 20 when the top surface exposure pattern and the side surface exposure pattern are simultaneously exposed in one exposure. The mask pattern 22E1 corresponds to the top surface exposure pattern 102E, and the mask patterns 22A1,22B1 22C1,2D1 correspond to the side exposure patterns 102A, 102B, 102C, 102D, respectively. FIG. 18C is a plan view of the mask 20 when the top surface exposure pattern and the side surface exposure pattern are separately exposed. The mask pattern 22E2 corresponds to the top surface exposure pattern 102E, and the mask patterns 22A2, 22B2, 22C2, 22D2. Corresponds to the side exposure patterns 102A, 102B, 102C, 102D, respectively.

A method of separately exposing the top surface exposure pattern 102E and the side surface exposure patterns 102A, 102B, 102C, and 102D will be described with reference to FIG. First, the top surface exposure pattern is exposed with the settings shown in 1 to 5 below.
1. 1. By driving the light-shielding blade 25YU of the mask blind mechanism 25 in the Y-direction (lower direction in the figure), the mask patterns 22A2, 22B2, 22C2, 22D2 on the mask 20 are shielded from light, and the exposure irradiation is limited to the mask pattern 22E2. do.
2. 2. The top surface exposure pattern 102E of the exposure target is positioned with respect to the mask pattern 22E2 by the XY stage mechanism.
3. 3. The aperture selection mechanism selects the optimum aperture aperture for the top exposure pattern 102E.
4. The Z stage mechanism performs best focus positioning with respect to the top exposure pattern 102E.
5. The exposure is performed by setting the exposure amount to the optimum value of the top surface exposure pattern 102E.

Next, the side exposure pattern is exposed with the settings shown in 6 to 10 below.
6. By driving the light-shielding blade 25YD of the mask blind mechanism 25 in Y + (upward in the figure), the mask pattern 22E2 on the mask 20 is shielded from light, and the exposure irradiation is limited to the mask patterns 22A2, 22B2, 22C2, 22D2.
7. The side exposure patterns 102A, 102B, 102C, 102D of the exposure target are positioned with respect to the mask patterns 22A2, 22B2, 22C2, 22D2 by the XY stage mechanism, respectively.
8. The aperture selection mechanism selects the optimum aperture aperture for the side exposure patterns 102A, 102B, 102C, 102D.
9. The Z stage mechanism performs best focus positioning on the side exposure patterns 102A, 102B, 102C, 102D.
10. The exposure amount is set to the optimum value of the side exposure patterns 102A, 102B, 102C, 102D, and the exposure is performed.

According to the exposure apparatus of the present embodiment as described above, by individually exposing the horizontal plane exposure pattern and the side surface exposure pattern of the object to be exposed, it is possible to expose both patterns under the optimum exposure conditions. Therefore, better pattern formation is possible for both the horizontal surface exposure pattern and the side surface exposure pattern as compared with the case where both patterns are exposed at the same time.

By individually exposing the horizontal plane exposure pattern and the side exposure pattern of the object to be exposed, optimum exposure can be performed for both patterns. Therefore, on a mask as shown in the third and fourth embodiments of the present invention. It is not necessary to arrange fine light-shielding dot patterns on the horizontal plane pattern and the side surface pattern to correct the transmittance of both patterns.

20 Mask 21 Light-shielding area 22 Transmitted light area 22A1,22B1,22C1,22D1 Mask pattern for side exposure 22E1 Mask pattern for top exposure 22A2, 22B2, 22C2, 22D2 Mask pattern for side exposure 22E2 Mask pattern for top exposure 22H Transmitted light area 22I Transmitted light area 22J Transmitted light area 22K Transmitted light area 23 Mask pattern 23F Mask pattern 23G Mask pattern 25 Mask blind mechanism 25XL, 25XR Light-shielding blade in X direction 25YU, 25YDY Light-shielding blade in Y direction 30 Illumination optical system 31A Light source 31B Secondary light source 32 Lighting system field aperture 33 Lighting system opening aperture 33EF Lighting system opening aperture for horizontal plane 33A, 33B, 33C, 33D, 33AC, 33BD, 33G Side illumination system opening aperture 34 Turntable 35 Rotating pivot 36 Digital Micromirror device 36a Movable micromirror 36EF Illuminated light beam area for horizontal plane 36A, 36B, 36C, 36D, 36AC, 36BD, 36G Illuminated light beam area for side surface 50 Projection optical system 55 Projection system Opening aperture 100 Exposure substrate 101 Three-dimensional structure 102A, 102B, 102C, 102D Side exposure pattern 102E Top exposure pattern 102F Bottom exposure pattern 102G Vertical surface exposure pattern 102H Side exposure pattern 102I Side exposure pattern 102J Side exposure pattern 102K Top surface exposure pattern 102L Side exposure pattern 103, 104, 105, 106 , 107, 108 Exposed object 103a, 104a, 105a Side surface of the exposed object 110 Resistor in the horizontal plane region 111 Resistor in the side surface region β Projection magnification of the projection optical system θ Incident angle of the projected light of the projection optical system δ Side surface of the exposure object Inclination angle from the horizontal plane L Vertical length of the mask pattern W Horizontal width of the mask pattern l Vertical length of the exposure pattern w Horizontal width of the exposure pattern H Distance from the upper surface of the exposure object to the lower end of the side exposure pattern D Minimum placement interval of the exposure object I1 Light intensity on the horizontal plane I2 Light intensity on the side surface T1 Resist film thickness on the horizontal plane T2 Resist film thickness on the side surface

Claims (9)

Light source and
Illumination system Illumination optics with aperture diaphragm and illumination lens,
A mask with a mask pattern and
Projection system with aperture aperture and projection optics with projection lens,
The lighting system aperture diaphragm is installed at a position off the optical axis of the light source.
The luminous flux that has passed through the illumination system aperture diaphragm is provided with an inclination angle by the illumination lens installed between the illumination system aperture diaphragm and the mask.
The mask is irradiated with the luminous flux having the inclination angle to generate diffracted light from the mask pattern.
The diffracted light is condensed by the projection system aperture diaphragm and the projection lens to form a light beam directed from the side facing the illumination system aperture diaphragm around the optical axis toward the optical axis side, and is exposed to the side surface of the exposure object. Exposure device. The exposure apparatus according to claim 1, wherein the light flux collected by the projection system aperture diaphragm and the projection lens is inclined with respect to the optical axis. The illumination optical system arranges a digital micromirror device in which a large number of movable micromirrors that reflect illumination light at a predetermined angle are arranged at an arrangement position of an aperture diaphragm of the illumination optical system, and the digital micromirror device is used. The exposure apparatus according to claim 1 or 2, which is the illumination system aperture diaphragm. A claim that the horizontal width W of the mask pattern is set by the following formula (1) and the vertical length L is set by the following formula (2) with respect to the horizontal width w and the vertical length l of the side exposure pattern exposed to at least the side surface of the exposure object. Item 1. The exposure apparatus according to Item 1.
w = β ・ W (1)
l = β ・ L ・ cosθ / cos (θ－δ) (2)
However, β is the projection magnification of the projection optical system, θ is the incident angle of the projected light of the projection optical system, and δ is the inclination angle of the side surface of the exposed object from the horizontal plane. The exposure apparatus according to claim 4 , wherein the fine light-shielding dot pattern is arranged in the mask pattern corresponding to the light intensity distribution of the exposure pattern exposed on the side surface of the exposure object. The exposure apparatus according to claim 5 , wherein the exposure apparatus has two or more mask patterns, and the density of the fine light-shielding dot patterns arranged in each mask pattern is different for each mask pattern. The exposure apparatus according to claim 5 , wherein the fine shading dot patterns are arranged at different densities in the mask pattern. The exposure apparatus according to any one of claims 5 to 7 , wherein the fine light-shielding dot pattern is a pattern that cannot be resolved by a projection optical system. A diaphragm selection mechanism that allows the shape and arrangement of the illumination system opening diaphragm to be selected, a mask blind mechanism that allows exposure to only a specific area in the mask pattern, and an XY stage mechanism that allows the exposure object to be moved in a horizontal plane. The first aspect of the invention, wherein the Z stage mechanism for moving the exposed object in the vertical direction is provided, and the horizontal plane exposure pattern and the side exposure pattern exposed on the side surface of the exposed object are individually exposed. Exposure device.

Images