JPH07287388A - Mask for exposure - Google Patents

Abstract

PURPOSE:To make it possible to pattern a photoresist layer in such a manner that its sectional shape has a trapezoidal shape, etc., by forming refractive faces on one surface of a parallel flat planar transparent substrate and forming patterns of light shielding films on one surface or another flat surface. CONSTITUTION:The layer of a photoresist 2 of a 'positive type' is formed on the flat surface of a device material 1. This mask 10 for exposure is constituted by forming >=1 'positive' refractive faces 10A on one surface of the parallel flat planar transparent substrate 1 and forming the patterns of the light shielding films 10B regulating luminous fluxes on the other surface in correspondence to the refractive faces 10A so that parallel luminous fluxes are made incident from the side of the surface formed with the refractive faces 10. The luminous flux parts made incident on the refractive faces 10A are condensed by the effect of the refractive faces when the mask 10 for exposure is arranged in proximity to or tight contact with the surface of the layer of the photoresist 2 and is irradiated with the parallel luminous fluxes having uniform light intensity from the side of the refractive faces 10A. The condensed luminous fluxes expose the layer of the photoresist 2 to a 'downward convergent wedge shape'.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure mask, and more particularly to an exposure mask having a refracting surface and a light-shielding film pattern.

[0002]

2. Description of the Related Art Recently, a cylindrical photoresist layer is formed by patterning the shape of a microlens on a photoresist layer formed on a flat surface of a transparent optical material by photolithography, and heat-treated by heating. Then, the photoresist surface is made to have a convex curved surface by the action of heat flow and surface tension, and then the "curve" of the convex curved surface shape of the photoresist is made on the optical material by "etching".
Then, a microlens manufacturing method has been proposed in which a microlens is formed by forming a minute refracting surface having a positive refracting power (JP-A-5-173003).

In the above publication, the photoresist layer is irradiated with light having a predetermined intensity distribution to make the surface of the photoresist layer into a concave curved surface, and this concave curved surface shape is optically etched by anisotropic etching. It has also been proposed that a negative microlens be formed by engraving on a material to form a minute refracting surface having a negative refractive power. By the way, when the photoresist layer is irradiated with light, the thickness of the photoresist that can be exposed to light is at most about several tens of μm. This means that when a "columnar photoresist layer" is obtained by the above method,
It means that the height of the photoresist cylinder is limited to about several tens of μm.

In this way, when the height of the cylinder of the photoresist is low, it becomes difficult to form the curved surface of the photoresist by heat treatment when the diameter of the cylinder becomes large, and therefore,
When the shape of the refracting surface becomes large, the curvature of the refracting surface also becomes small, and it becomes difficult to form a “comparatively large refracting surface having a large refracting power”.

Further, as a method of making the surface of the photoresist layer into a concave curved surface, the above publication discloses that the light intensity gradually changes from the central portion of the pattern to the peripheral portion by irradiating a circular pattern with defocusing. However, it is not easy to accurately form a desired concave curved surface shape on the photoresist surface by exposure with such light intensity.

Further, when patterning the photoresist layer, in photolithography, exposure is usually performed using a mask. However, when the opening pattern in the mask is small or narrow, the exposure light beam is diffracted at the opening, and the opening is opened. Accurate patterning is difficult because the area other than the area is exposed.

[0007]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances. The photoresist layer is patterned so that its cross-sectional shape is trapezoidal, triangular, inverted trapezoidal, or inverted triangular. The present invention aims to provide a novel exposure mask.

Another object of the present invention is to provide a novel exposure mask capable of accurately patterning a desired concave curved surface shape on the surface of a photoresist layer.

Another object of the present invention is to provide a novel exposure mask which can effectively reduce the influence of the above diffraction when the photoresist layer is exposed.

[0010]

The exposure mask of the present invention is "an exposure mask for performing patterning exposure on a photoresist layer formed on a flat surface of a device material". The device material is a material capable of forming a desired curved surface shape by engraving the curved surface shape formed on the photoresist layer by etching, and may be used without particular limitation as long as it can be etched. it can. The "desired curved surface shape" formed on the device material
Is the refractive surface shape (when the device material is transparent)
Alternatively, a reflection film is formed and used as a reflection surface shape.

The exposure mask of the present invention is a "light-shielding film that regulates a light flux on one or more flat surfaces of one or more positive or negative refraction surfaces formed on one surface of a parallel plate-shaped transparent substrate. Pattern is formed corresponding to the refracting surface, and a parallel light beam can be incident from one surface side. ”
It is characterized by (claim 1).

The shape of the refracting surface formed on the transparent substrate can be various. For example, one or more refracting surfaces can be "powered in only one direction." At this time, the pattern of the light-shielding film that regulates the light flux may be formed so as to "shield the portion other than the slit-shaped region including the optical axis surface of each refraction surface (the slit-shaped portion serves as an opening)". (Claim 2), it may be formed so as to “shield the slit-shaped region including the optical axis surface of each refracting surface” (Claim 3). In the case of the invention according to claim 2, the light shielding film is
It may be formed on either surface of the transparent substrate, but in the case of the third aspect of the invention, it is formed on the surface opposite to the surface on which the refraction surface is formed.

The above-mentioned "refractive surface having power only in one direction"
Is a convex or concave cylinder surface, but the cross-sectional shape of the cylinder surface is not limited to a circular arc shape, and may be a shape specified by a conic constant / aspherical surface coefficient that gives a so-called aspherical surface shape.

The shape of the refracting surface may also be "spherical or coaxial aspherical". in this case,
The power of the refracting surface can be positive or negative, but when the power of the refracting surface is positive, "the light beam incident from the refracting surface side is condensed on the other surface of the transparent substrate".
For power, the light-shielding film is formed on the surface opposite to the refracting surface, and the pattern of the light-shielding film can be "a pattern in which a pinhole is provided at the intersection of the refracting surface and the optical axis". 4).

When the shape of the refracting surface is "spherical or coaxial aspherical", the pattern of the light-shielding film is "a circular opening or light-shielding portion centered on the intersection of the refractive surface and the optical axis. According to claim 5).

Refractive surfaces are also "having different powers in two directions orthogonal to each other", ie, "anamorphic".
In this case, the pattern of the light shielding film is
It is also possible to use "a pattern of elliptical openings or light-shielding portions centering on the intersection of the refracting surface and the optical axis" (claim 6).

In the case of the fifth and sixth aspects of the present invention, the light-shielding film having the opening may be formed on either surface of the transparent substrate. Is formed on the surface opposite to that on which the is formed.

In the case of the exposure mask according to claim 1 or 2 or the exposure mask according to claim 5 or 6, when the light-shielding film and the refraction surface are formed on opposite surfaces of the transparent substrate, A positive or negative refracting surface can be formed in the "pattern portion by the opening" on the surface on the side where the pattern of the light shielding film is formed, corresponding to one or more refracting surfaces on one surface ( Claim 7). That is, when the pattern of the light-shielding film is “a pattern of an opening including the optical axis of the refraction surface formed on one side of the transparent substrate”, a refraction surface is also formed on this opening, and the surface on one side is formed. A lens action can be provided in combination with the refracting surface of.

The "refractive surface having power in only one direction" formed on the transparent substrate in the second and third aspects of the present invention is a convex or concave linder surface. It can be expressed as a "surface having power in a direction orthogonal to a straight line" which is a direction without curvature. By further generalizing this expression, the above "line" is not limited to a straight line, and can be a curved line or a broken line, and a refracting surface "having a positive or negative refractive power in a direction orthogonal to a predetermined line" Is possible.

The exposure mask according to the invention of claim 8 is
"Positive or negative refractive power in the direction orthogonal to the prescribed line"
The "predetermined line" on one or more refracting surfaces has a ring shape, and the light shielding film is formed so as to shield the area inside the ring. The above-mentioned "ring shape" can be circular, elliptical, rectangular, polygonal, or the like.

In the exposure mask according to any one of claims 1 to 8, one or more refracting surfaces are "arrayed in one row in one direction".
It is possible to use the one that has been arranged or the "two-dimensional array arrangement" (claim 9).

[0022]

As described above, in the exposure mask of the present invention, a parallel light beam is incident from one side of the mask, but the incident light beam is subjected to the refraction effect of the refracting surface and the light shielding effect of the pattern of the light shielding film, and these effects are exerted. By the combination of the above, the photoresist layer can be irradiated with “oblique light” and “light with a spherical wavefront”.

[0023]

EXAMPLES Specific examples will be described below. Figure 1
A method for manufacturing a cylinder lens array is schematically shown by using one example of the exposure mask according to claims 1, 2, and 9.

In FIG. 1A, reference numeral 1 indicates a transparent device material. A layer of “positive type” photoresist 2 is formed on the flat surface of the device material 1. An exposure mask shown by reference numeral 10 in the figure has one or more "positive" refracting surfaces 10A on one surface of a parallel plate-shaped transparent substrate 11.
Is formed, and on the other surface, the light-shielding film 10 that regulates the light flux is formed.
The pattern B is formed corresponding to the refracting surface 10A, and the parallel light flux can be made incident from the surface side on which the refracting surface 10A is formed (claim 1).

The one or more refracting surfaces 10A are "convex cylinder surfaces" that have positive power only in one direction (left and right direction in the drawing) and have no power in the direction orthogonal to the drawing. Are arrayed in one row at a predetermined pitch (claims 2 and 9).

The pattern of the light-shielding film 10B is the same as that of each refraction surface 10.
It is formed so as to shield portions other than the "slit-like region" that is long in the direction orthogonal to the drawing, including the optical axis plane of A (a plane in which the optical axes shown by the chain lines are connected in the direction orthogonal to the drawing). Claim 2).

The exposure mask 10 is provided on the surface of the layer of the photoresist 2 in close proximity or in close contact therewith, and the refraction surface 10
When a parallel light flux having a uniform light intensity is applied from the A side, the light flux portion incident on the refracting surface 10A is condensed by the action of the refracting surface, and the layer of the photoresist 2 is exposed in a "wedge-like shape with a lower recess". To do.

Therefore, if the photoresist layer 2 is developed after exposure and the exposed portion is removed, as shown in FIG. 1 (b), "the cross section is trapezoidal (the same shape in the direction orthogonal to the drawing)". An array arrangement of the photoresists 2 is obtained, and the arrangement pitch is the refraction surface 10A of the exposure mask 10.
The arrangement pitch is the same as the arrangement pitch (the phase is shifted by 90 degrees).

When the "heat treatment" is performed on the layer of the photoresist 2 in the state of FIG. 1B, the surface of the photoresist 2 becomes curved and becomes a cylinder surface shape as shown in FIG. 1C. . Since the photoresist 2 to be heat-treated has a “trapezoidal” cross-sectional shape in each part, even if the width in the left-right direction is large, it can easily be curved into a cylinder surface shape. If the cross-sectional shape is “rectangular” and the width in the left-right direction is large, the photoresist 2 will be curved though it is curved.
The surface shape of is a flat "dashing" shape, and it is difficult to form a clean cylinder surface.

From the state of FIG. 1C, "anisotropic etching" is performed on the device material 1 and the photoresist 2.
Then, the “cylinder surface shape” of the photoresist 2 is engraved on the device material 1 to obtain a cylinder lens array in which the cylinder surfaces are arrayed in one direction. Alternatively, a convex cylinder surface mirror array can be realized by forming a reflection film on the arrayed surface of the cylinder surface.

FIG. 2 is a diagram for explaining one embodiment of the exposure mask according to the first and third aspects. Reference numerals 1 and 2 are
Device materials and photoresists are shown as in FIG.

In FIG. 2A, the exposure mask 20 is used.
Has a "negative" refracting surface 20A formed on one surface of a parallel plate-shaped transparent substrate 21, and a pattern of a light shielding film 20B that regulates a light beam is formed on the other surface corresponding to the refracting surface 20A. Therefore, the parallel light flux can be made incident from the side on which the refraction surface 20A is formed (claim 1).

The refracting surface 20A is in one direction (left and right in the figure).
It is a "concave cylinder surface" which has negative power only in and has no power in the direction orthogonal to the drawing (claim 3).

The pattern of the light-shielding film 20B is formed by each refraction surface 20.
It is formed so as to shield the portion of the "slit-like region" that is long in the direction orthogonal to the drawing, including the optical axis plane of A (shown by the chain line) (claim 3).

The exposure mask 20 is provided close to or in close contact with the surface of the layer of the photoresist 2 and the refraction surface 20A
When a parallel light flux with uniform light intensity is radiated from the side of
The portion of the light beam incident on the refracting surface 20A is expanded in the left-right direction in the drawing by the action of the refracting surface, and the layer of the photoresist 2 is exposed in the "upper wedge shape".

Therefore, if the photoresist layer 2 is developed after the exposure and the exposed portion is removed, as shown in FIG. 2B, "the cross section is trapezoidal (the same shape in the direction orthogonal to the drawing)". Photoresist 2 is obtained.

When the "heat treatment" is performed on the layer of the photoresist 2 in the state of FIG. 2 (b), the surface of the photoresist 2 is easily curved to form a cylinder, as shown in FIG. 1 (c). It becomes a surface shape. Therefore, as in the embodiment of FIG. 1, a desired cylinder surface can be formed on the surface of the device material by anisotropically etching the photoresist and the device material whose surface is deformed into the cylinder surface shape.

Refractive surface 20A of exposure device 20
Needless to say, by arranging the patterns of the light shielding film 20B in one row in the left-right direction in the drawing, the cylinder lens array and the cylinder surface mirror array similar to the embodiment of FIG. 1 can be realized.

FIG. 3 is a modification of the embodiment shown in FIG. In FIG. 3A, an exposure mask 100 has one or more “positive” refracting surfaces 1 on one surface of a parallel plate-shaped transparent substrate 110.
00A is formed, and the pattern of the light shielding film 100B that regulates the light flux is formed on the other surface in correspondence with the refraction surface 100A, and the parallel light flux is formed from the side of the surface on which the pattern of the light shielding film 100B is formed. It can be made incident.

The one or more refracting surfaces 100A are convex cylinder surfaces having positive power only in one direction (horizontal direction in the drawing) and no power in the direction orthogonal to the drawing, and are predetermined in the lateral direction in the drawing. Arrayed in one row at a pitch of.

The pattern of the light-shielding film 100B is formed by each refraction surface 1.
It is formed so as to shield a portion other than the "slit-like region (equal to the effective width of the refracting surface 100A in the left-right direction)" that is long in the direction orthogonal to the drawing, including the optical axis plane of 00A (shown by a chain line). .

The surface of the exposure mask 100 on which the refraction surface 100A is formed is arranged in the vicinity of the surface of the layer of the photoresist 2, and uniform light is emitted from the surface of the surface on which the light shielding film 100B is formed. When a parallel light beam having a high intensity is irradiated, the light beam portion which is separated by the pattern of the light shielding film 100B and is incident on the refraction surface 100A is condensed by the refraction action, and the layer of the photoresist 2 is exposed in a "lower wedge shape". .

Therefore, if the photoresist layer 2 is developed after the exposure and the exposed portion is removed, an array arrangement of the photoresist 2 having a "trapezoidal cross section" is obtained as shown in FIG. 3 (b). . Thereafter, similarly to the embodiment of FIG. 1, a cylinder lens array can be obtained by performing heat treatment and anisotropic etching.

FIG. 4 is a view for explaining one embodiment of the exposure mask according to claims 1, 4, and 9. Figure 4 (a)
In the exposure mask 30, one or more “positive” refracting surfaces 30A are formed on one surface of the parallel plate-shaped transparent substrate 31, and the pattern of the light shielding film 30B that regulates the light flux is formed on the other surface. It is formed so as to correspond to the refracting surface 30A, and a parallel light flux can be made incident from the refracting surface 30A side.

The one or more refracting surfaces 30A have a convex spherical shape or a convex coaxial aspherical shape, and have a positive power for condensing the light beam incident from the refracting surface side on the position of the other surface of the transparent substrate, The two-dimensional array is formed (claim 9). The pattern of the light-shielding film 30B is made up of
"Pinhole" at the intersection with the optical axis of 0A (shown by the chain line)
Is a pattern provided with.

As shown in FIG. 4 (a), when a parallel light beam is irradiated from the refracting surface 30A side, the light beam is emitted from each refracting surface 30A.
As a result, the light is condensed at the position of the pinhole in the pattern of the light shielding film 30B, and is emitted as a spherical wave from the pinhole.

As shown in the figure, if the surface of the layer of the photoresist 2 formed on the device material 1 and the exposure mask 30 are appropriately exposed, the layer of the photoresist 2 is exposed to a spherical wave. Exposed. Therefore, if the photoresist 2 is developed after exposure, a two-dimensional array array of spherical concave surfaces is formed as the surface shape of the layer of the photoresist 2, as shown in FIG. 4B.

Hereinafter, the photoresist 2 and the device material 1
On the other hand, if “anisotropic etching” is performed and the “spherical surface shape” of the photoresist 2 is engraved on the device material 1, a concave lens array in which spherical concave surfaces are arranged in a two-dimensional array is obtained. Obtainable. Alternatively, a concave mirror array can be realized by forming a reflection film on the surface where the spherical concave surfaces are arrayed.

The shape of the refracting surface 30A in FIG. 4 (a) is a cylinder surface having no curvature in the direction orthogonal to the drawing, and the pinhole is a "linear slit" long in the direction orthogonal to the drawing. (This is the case in the embodiment of FIG.
The opening of the light shielding film 10B is formed into a linear slit, and the refraction surface 10
It is easily understood that the concave cylinder lens array and the concave cylinder mirror array can be realized as described above, which is equivalent to the case where the focal plane of A is aligned with the surface of the light shielding film 10B.

FIG. 5 is a view for explaining one embodiment of the exposure mask according to the first and fifth aspects. In FIG. 5A, the exposure mask 40 is a parallel plate-shaped transparent substrate 41.
A "positive" refracting surface 40A is formed on one surface, and a pattern of a light-shielding film 40B that regulates the light flux is formed on the other surface corresponding to the refracting surface 40A. A parallel light beam can be made incident.

The refracting surface 40A has a convex spherical shape or a convex coaxial aspherical shape, and has a positive power for condensing a light beam incident from the refracting surface side to a position outside the transparent substrate. Light-shielding film 4
The pattern 0B is a pattern of circular openings centered on the intersection with the optical axis of each refracting surface 40A (shown by the chain line).

As shown in FIG. 5A, when a parallel light beam is irradiated from the refracting surface 40A side, the light beam is emitted from each refracting surface 40A.
The light is condensed by and is emitted while being regulated by the pattern of the light shielding film 40B. As shown, the surface of the layer of photoresist 2 formed on the device material 1 and the exposure mask 4
When the exposure is performed by appropriately setting the interval of 0, the layer of the photoresist 2 is exposed in the "inverse cone shape" by the condensed light flux.

Therefore, if the photoresist 2 is developed after the exposure, as shown in FIG. 5B, a "inverted truncated conical surface" shape whose bottom is the surface of the device material 1 is formed.

Hereinafter, the photoresist 2 and the device material 1
When “isotropic etching” is performed on, a concave surface shape of a concave spherical surface can be formed as the surface shape of the device material 1. A concave lens array can be obtained by arraying the refracting surfaces 40A. Alternatively, a concave mirror array can be realized by forming a reflection film on the surface on which the concave shapes are arrayed.

The shape of the refracting surface 40A in FIG. 5A is "ellipsoidal with the major axis in the direction orthogonal to the drawing", and the pattern of the light-shielding film 40B is "centering on the intersection with the optical axis of the refracting surface." Assuming that an elliptical opening pattern having a major axis in the direction orthogonal to the drawing is used, the result of exposure / development is that the layer of the photoresist 2 has a “reverse truncated surface” as shown in FIG. It is possible to form a surface having an “elliptical cone surface” shape, that is, a surface having an inverted trapezoidal cross section.

By performing “isotropic etching” on the photoresist 2 and the device material 1, a spheroidal concave shape can be formed as the surface shape of the device material 1. A concave lens array can be obtained by arraying the refracting surfaces 40A. Each concave lens in this concave lens or concave lens array is an anamorphic lens having different negative powers in the directions orthogonal to each other (corresponding to the left-right direction in FIG. 5A and the direction orthogonal to the drawing). Of course, it is also possible to realize an anamorphic concave mirror or concave mirror array by forming a reflecting film in the above concave shape.

In the exposure mask of the embodiment of FIG. 5, the parallel light flux may be made incident from the surface of the light shielding film 40B on the side where the pattern is formed.

FIG. 6 is a diagram for explaining one embodiment of the exposure mask according to the first and sixth aspects. In FIG. 6A, the exposure mask 50 is a parallel plate-shaped transparent substrate 51.
A negative refraction surface 50A is formed on one surface, and a pattern of a light shielding film 50B that regulates the light flux is formed on the other surface in correspondence with the refraction surface 50A, and is parallel to the refraction surface 50A side. The light flux can be made incident.

The refracting surface 50A has a concave spherical shape or a concave coaxial aspherical shape, and has a negative power for diverging a light beam incident from the refracting surface side. The pattern of the light-shielding film 50B is a pattern of a circular light-shielding portion centered on an intersection with the optical axis (shown by a chain line) of each refracting surface 50A.

As shown in FIG. 6A, when a parallel light beam is irradiated from the refraction surface 50A side, the light beam is diverged by the refraction surface 50A and the layer of the photoresist 2 formed on the device material 1 is formed into a conical shape. To expose. Therefore, if the photoresist 2 is developed after exposure, as shown in FIG.
A "conical" photoresist shape can be formed.

Thereafter, the photoresist 2 is heat-treated to make the surface shape curved, and "anisotropic etching" is performed on the device material 1 and the photoresist 2, so that a convex spherical surface is formed on the surface shape of the device material 1. Can be formed as. Refraction surface 5
A convex lens array can be obtained by arraying 0A. Alternatively, a convex mirror array can be realized by forming a reflection film on the surface on which the concave shapes are arrayed.

The shape of the refracting surface 50A in FIG. 6A is an elliptical shape whose major axis is in the direction orthogonal to the drawing, and the pattern of the light shielding film 50B is centered on the intersection with the optical axis of the refracting surface. Assuming an elliptical light-shielding part pattern whose major axis is in the direction orthogonal to the drawing, the result of exposure and development is
When a “conical elliptical cone” shape as shown in FIG. 6C can be formed on the layer of the photoresist 2, and “anisotropic etching” is performed on the photoresist 2 and the device material 1, A spheroidal convex shape can be formed as the surface shape of the device material 1.

A convex lens array can be obtained by arraying the refracting surfaces 50A in an array. Each convex lens in this convex lens or convex lens array has different anamorphic powers of different convex powers in the directions orthogonal to each other (corresponding to the left-right direction in FIG. 5A and the direction orthogonal to the drawing).
It is a great lens. Of course, it is also possible to realize a anamorphic convex mirror or convex mirror array by forming a reflective film in the above convex shape.

In the embodiments of FIGS. 2 and 6, the light-shielding film pattern is replaced with a light-shielding portion and an opening is replaced with a light-shielding portion so that photoresist 2 is used so that the negative and positive are reversed. Even if a "negative type" photoresist is used, a photoresist having a trapezoidal cross section can be obtained on the transparent substrate, as in the embodiments of FIGS.

FIG. 7 shows an exposure mask according to a seventh aspect of the present invention.
It is a figure for explaining an example. In FIG. 7, one or more “positive” refraction surfaces 60A are formed on one surface (upper surface) of the transparent substrate indicated by reference numeral 60, and on the other surface, a pattern of a light shielding film 60B that regulates a light flux. But refraction surface 60A
Corresponding to one or more refracting surfaces 60A on one surface, a positive refracting surface 60C is formed in a portion of the pattern of the light shielding film 60B by the opening. The light flux for exposure is made incident from the side on which the refraction surface 60A is formed.

The one or more refracting surfaces 60A are convex cylindrical surfaces having positive power only in one direction (horizontal direction in the drawing) and no power in the direction orthogonal to the drawing, and are predetermined in the lateral direction in the drawing. Arrayed in one row at a pitch of. Light-shielding film 6
The pattern of 0B is a pattern in which a portion including the optical axis surface of the refracting surface 60A is used as a slit-shaped opening, and the pattern portion formed by the slit-shaped opening has one or more refracting surfaces 60A on one side. Correspondingly, a refracting surface 60C, which is a cylinder surface, having a positive power in the left-right direction in the drawing is formed.

The exposure mask 60 is provided close to or in close contact with the surface of the layer of the photoresist 2, and the refraction surface 60A
When a parallel light flux with uniform light intensity is radiated from the side of
The light flux portion incident on the refracting surface 60A is
The light is focused by the action of C, and the layer of the photoresist 2 is exposed in the shape of "a wedge-shaped bottom".

Therefore, if the photoresist layer 2 is developed after the exposure and the exposed portion is removed, the photoresist 2 having a "trapezoidal cross section" is formed as in FIG. 1 (b) in the embodiment of FIG. An array array is obtained, and the array pitch is the same as the array pitch of the refracting surfaces in the exposure mask 60.

In FIG. 7, the power of the refracting surface 60C can be set to "negative", and in this case, the convergence of the light beam emitted from the exposure mask becomes loose, and the cross section of the photoresist after exposure and development is reduced. The slope of the trapezoidal slope in the shape becomes more "steep".

Of course, as a modification of the embodiment of FIG. 7, the refracting surfaces 60A and 60B can be spherical surfaces, coaxial aspherical surfaces, spheroids, etc., and the array can be a one-dimensional or two-dimensional array array.

In the embodiments shown in FIGS. 1, 2, 3, 5, and 6, the case where the refracting surface and the light shielding film are formed on the surfaces of the transparent substrate which are opposite to each other has been described. However, the refraction surface and the light shielding film can be formed on the same surface of the transparent substrate.

Referring to FIG. 8 (a), in the exposure mask 10 ', an array of refraction surfaces 10A is formed on one surface of the transparent substrate 11 in FIG. 1, and the refraction surfaces 10A are formed. A light-shielding film 10C is formed on the same surface as.

The light-shielding film 10C has a slit-shaped opening including the optical axis of the refracting surface, and regulates the light beam refracted by the refracting surface. Even with this configuration, the exposure mask 1 shown in FIG.
It will be easily understood that an exposure effect similar to 0 can be realized. Also in the case of the embodiment of FIG. 8A, the exposure situation similar to that of the embodiment of FIG. 3 is achieved by turning the figure upside down and letting the light beam enter from the flat surface side of the transparent substrate 10. realizable. Even in the case of the embodiment shown in FIG. 5, the light shielding film may be formed on the same side as the refracting surface 40A.
It is clear from the similarity between the embodiment of (a) and the embodiment of FIG.

Referring to FIG. 8B, the exposure mask 20 'has an array of refracting surfaces 20A arrayed on one surface of the transparent substrate 21 in FIG.
A light-shielding film 20C is formed on the same surface where A is formed.

The light-shielding film 20C has a slit-shaped opening including the optical axis of the refracting surface 20A, and regulates the light beam refracted by the refracting surface. It will be easily understood that the exposure effect similar to that of the exposure mask 20 of FIG. 2 can be realized even in this way. Even in the case of the embodiment shown in FIG. 6, it is clear from the similarity between the embodiment of FIG. 8B and the embodiment of FIG. 2 that the light shielding film may be formed on the same side as the refracting surface 50A. Is.

FIG. 9 is a view for explaining one embodiment of the exposure mask of the invention described in claim 8. The exposure mask 70 has, on one surface of a transparent substrate 71, a refracting surface 70A having a positive refracting power in a direction orthogonal to a "predetermined line" forming a circular ring. The refracting surface 70A is simply a ring donut shape cut along a plane orthogonal to its central axis.

The inner portion of the refracting surface 70A (the portion hatched with a broken line in the figure) is shielded by the light shielding film 70B. In this embodiment, the light-shielding film is also formed in the area outside the refracting surface.

When a positive type photoresist (formed in layers on the flat surface of the optical device) is exposed and developed using such an exposure mask 70, as shown in FIG.
As shown in (b) and FIG. 9C showing the CC ′ cross section, a circular V-shaped groove can be formed in the layer of the photoresist 2. Therefore, the same shape as that shown in FIG. 6B can be formed on the photoresist. By making the ring shape of the refracting surface into an elliptical shape, the photoresist shown in FIG. 6C can be formed.

Needless to say, the ring-shaped refracting surface can be arrayed in one or two dimensions.

The invention according to claim 7 is the same as the embodiment of FIG.
It goes without saying that the embodiment of FIG. 6 can also be applied to a structure in which the opening of the pattern of the light shielding film and the light shielding portion are inverted. In this case, the shape of the refraction surface formed in the opening of the pattern of the light-shielding film corresponds to the shape of the opening, corresponding to the refraction surfaces 40A and 50A formed on one surface of the transparent substrate. .

Although not specifically stated in each of the embodiments described above, when the curved surface shape formed on the surface of the device material is small, that is, the microlens, the microlens array, the microcylinder lens, the microcylinder lens array, or the micro It is particularly suitable for manufacturing mirrors and micromirror arrays.

Finally, a concrete example of each embodiment described with reference to FIGS. 3 and 7 will be described. The specific example described first is a specific example of the embodiment described with reference to FIG. Therefore, the same reference numerals as in FIG. 3 are used.

Thickness: 0.09 inch, refractive index: 1.48
On one side of the parallel plate-shaped transparent substrate 110 made of quartz, a photoresist is spin-coated and pre-baked to have a thickness:
The photoresist layer has a thickness of 3.5 μm. Pattern this photoresist layer by photolithography,
A stripe-shaped photoresist having a rectangular cross section with a width of 20 μm and a height of 3.5 μm has a pitch of 4
They were arranged in a grid pattern with 0 μm.

The pattern of this photoresist is heat-treated to transform the surface shape of each stripe-shaped photoresist into a cylinder surface, and this cylinder surface shape is subjected to anisotropic etching with an ECR etching device at a selection ratio of 1 to obtain the transparent substrate 110. Width: 2 by engraving on the surface of
0 μm, lens surface height: 4.0 μm, pitch: 40 μm
A refracting surface 100A having m cylindrical surfaces arranged in a one-dimensional lattice was formed. The focal length of the refracting surface 100A is 15
μm.

Photoresist is applied to the other surface of the transparent substrate 100, a stripe pattern corresponding to the pattern of the refraction surface is patterned, a metal thin film is vapor-deposited on the stripe pattern, and the photoresist is removed. The metal film of is lifted off. In this way,
As shown in (a), a pattern of the light-shielding film 100B made of a metal film was obtained in which openings having a width of 20 μm (equal to the width of the refracting surface 100A) were arranged at a pitch of 40 μm.

The exposure mask 1 thus formed
00, when a parallel light flux is entered from the side where the pattern of the light-shielding film 100B is formed, the outgoing light flux is about 2
It converged at an angle of 7.8 degrees.

Transparent glass (refractive index: 1.83) is used as the device material 1, a layer of photoresist 2 is provided thereon with a thickness of 10 μm, and the exposure mask is placed on the surface of the photoresist layer. When exposure was carried out, a photoresist pattern having a trapezoidal cross section as shown in FIG. 3B could be obtained. The trapezoidal shape of the cross section has an upper side width of 21.2 μm, a lower side width of 33.6 μm, an angle of a slope of about 32 degrees, and a convergence angle of a light beam emitted from the exposure mask (the above-mentioned about 27.8). However, this is considered to be the effect of diffraction at the edge of the light shielding film.

The photoresist was heat-treated at 200 ° C. for 30 minutes to make the surface shape a cylinder surface, and then the photoresist surface shape was engraved on the glass surface by anisotropic etching to obtain a refraction surface width of 33 μm. so,
A micro cylinder lens array having a pitch of 40 μm was obtained. The focal length of each micro cylinder lens is about 20.
It is 15 μm.

Using the same exposure mask 100 as described above, transparent glass having a refractive index of 1.48 is used as the device material 1, and a layer of photoresist 2 is provided thereon with a thickness of 2 μm. When the steps were performed, after exposure, the trapezoidal shape of the cross section formed by the photoresist 2 had an upper side width of 21.2 μm, a lower side width of 23.6 μm, and a slope angle of about 32 degrees. Although slightly larger than the convergence angle of the light beam emitted from the mask 100 (about 27.8 degrees above), after the heat treatment and etching, the width of the refraction surface is 23 μm,
A micro cylinder lens array having a pitch of 40 μm was obtained. The focal length of each micro cylinder lens is about 5
It was 9.9 μm.

Next, a specific example of the embodiment shown in FIG. 7 will be described.
The reference numerals used in FIG. 7 are used. A positive photoresist is spin-coated on one surface of a parallel plate-shaped transparent substrate 61 having a thickness of 0.5 mm and made of SF60 material having a refractive index of 1.78, and prebaked to form a layer having a thickness of 10.68 μm. And Pattern this photoresist layer,
Width: 200 μm stripe-shaped photoresist (rectangular cross section) is arranged at a pitch of 250 μm to form a pattern arranged in one direction, and then at 200 ° C. for 30 minutes.
The photoresist was heat-treated to transform the surface of each stripe of photoresist into a convex cylinder surface. The height of the convex cylinder surface formed by the deformation is 15.91 μm.
Met.

Anisotropic dry etching with a selection ratio of 0.85 was performed, and the array of cylinder surface shapes was engraved on the surface of a transparent substrate of SF60 material to form refraction surface 60A in FIG. This refracting surface has a width of 200 μm, a radius of curvature of 0.31 mm, and a focal length of 0.397 mm.

A photoresist is applied to the other surface (back surface) of the transparent substrate to a thickness of 2.7 μm, and the intersection between the optical axis surface of the refraction surface and the other surface is centered by photolithography. Width: 70 μm stripe-shaped photoresist (rectangular cross-section) is formed at a pitch of 250 μm, and then the photoresist is heat-treated at 200 ° C. for 30 minutes to make the surface of each stripe-shaped photoresist a convex cylinder surface. Transformed. The height of the convex cylinder surface formed of photoresist at this time was 3.55 μm.

Anisotropic dry etching with a selection ratio of 0.59 was performed, and the above array of cylinder surface shapes was engraved on the back surface of the transparent substrate to form refraction surface 60C in FIG. This refracting surface has a width of 70 μm and a radius of curvature of −0.80 mm,
The focal length converted into the plano-convex shape is 1.026 mm.

An exposure mask 60 was obtained by forming a pattern of the light-shielding film 60B so that the refraction surface 60C was used as an opening. The light shielding film 60B is a metal film and is formed by using photolithography and sputtering.

Exposure mask 6 thus formed
When a parallel light flux of 0 is entered from the side where the refracting surface 60A is formed, the outgoing light flux is approximately 1 with respect to the optical axis.
The light is converged at an angle of 8 degrees, and the convergence position is the refractive surface 60.
The position was 0.105 mm outside C.

Transparent synthetic quartz material (refractive index: 1.48)
As the device material 1, and a layer of photoresist 2 having a thickness of 40 μm is provided on the device material 1, and the exposure mask 60 is aligned with the photoresist layer surface by an alignment amount (the top of the refraction surface 60C of the exposure mask 50 and the photomask). The distance from the surface of the layer of the resist 2 can be controlled in the order of 10 μm depending on the performance of the exposure apparatus. When the mask 50 and the refracting surface 60C are in contact with each other, the alignment amount is 0), and the exposure is performed A photoresist pattern having a trapezoidal cross section could be obtained. The trapezoidal shape of the above cross section has an upper side width of 208 μm and a lower side width of 234 μm.
Is.

After exposing the photoresist twice,
Heat treatment is performed at 200 ° C. for 30 minutes to make the surface shape a cylinder surface having a height of 54.2 μm, and then the selection ratio:
A photoresist surface shape is engraved on the device material surface by 0.50 anisotropic etching to form a micro cylinder lens having a refraction surface width of 230 μm, a pitch of 250 μm, and a cylinder surface height of 27.1 μm. An array was obtained. The focal length of each micro cylinder lens is approximately 0.357 μm.

The surface shape of the photoresist, which became the cylinder surface having the height of 54.2 μm, was engraved on the surface of the device material by anisotropic etching with a selectivity of 1:
A microcylinder lens array having a refraction surface width of 230 μm, a pitch of 250 μm, and a cylinder surface height of 54.2 μm was obtained. The focal length of each microcylinder lens was approximately 0.304 μm.

[0099]

As described above, according to the present invention, a novel exposure mask can be provided. Since the present invention has the above-described structure, when patterning the photoresist layer, exposure is performed with appropriate light (divergence, convergence, or spherical wave) according to the pattern to be patterned. be able to.

[Brief description of drawings]

FIG. 1 is a diagram for explaining an embodiment of the invention described in claims 1, 2, and 9.

FIG. 2 is a diagram for explaining an embodiment of the invention described in claims 1 and 3;

FIG. 3 is a diagram for explaining a modified example of the embodiment of FIG.

FIG. 4 is a diagram for explaining an embodiment of the invention described in claims 4 and 9;

FIG. 5 is a diagram for explaining an embodiment of the invention described in claims 5 and 6;

FIG. 6 is a diagram for explaining an embodiment of the invention described in claims 5 and 6;

FIG. 7 is a diagram for explaining an embodiment of the invention according to claim 7;

FIG. 8 is a diagram for explaining a modified example of the embodiment described in FIGS.

FIG. 9 is a diagram for explaining one embodiment of the invention according to claim 8;

[Explanation of symbols]

 1 Device Material 2 Photoresist 10 Exposure Mask 10A Refractive Surface 10B Light-shielding Film

Claims (9)

[Claims] 1. An exposure mask for performing patterning exposure on a photoresist layer formed on a flat surface of a device material, comprising one or more positive or negative electrodes on one surface of a parallel plate-shaped transparent substrate. A refracting surface is formed, and a pattern of a light-shielding film that regulates the light flux is formed on the one surface or the other surface in correspondence with the refraction surface, and a parallel light flux can be incident from one surface side. Characteristic exposure mask. 2. The exposure mask according to claim 1, wherein at least one refracting surface has power in only one direction, and the pattern of the light shielding film is other than a slit-shaped region including the optical axis surface of each refracting surface. An exposure mask, which is formed so as to shield the above portion from light. 3. The exposure mask according to claim 1, wherein the one or more refracting surfaces have power in only one direction, and the light-shielding film is on a side of the transparent substrate opposite to the surface on which the refracting surface is formed. The mask for exposure, wherein the pattern of the light-shielding film is formed so as to shield the slit-shaped region including the optical axis surface of each refraction surface from light. 4. The exposure mask according to claim 1, wherein the at least one refracting surface is a convex spherical surface or a convex coaxial aspherical surface, and a light beam incident from the refracting surface side is formed on the other surface of the transparent substrate. It has a positive power to focus light at a position, and the light-shielding film is formed on the surface of the transparent substrate opposite to the surface on which the refraction surface is formed, and the pattern of the light-shielding film is the optical axis of the refraction surface. An exposure mask having a pattern in which pinholes are provided at intersections with. 5. The exposure mask according to claim 1, wherein at least one refracting surface has a spherical shape or a coaxial aspherical shape, and the pattern of the light shielding film is centered on an intersection of the refracting surface and the optical axis. An exposure mask having a pattern of circular openings or light-shielding portions. 6. The exposure mask according to claim 1, wherein the one or more refracting surfaces have different powers in two directions orthogonal to each other, and the pattern of the light-shielding film has a crossing portion with the optical axis of the refracting surface. An exposure mask, which is a pattern formed by an oval opening or a light-shielding portion having a center. 7. The exposure mask according to claim 1, 2 or 5 or 6, wherein the light-shielding film is formed on the surface of the transparent substrate opposite to the surface on which one or more refraction surfaces are formed, A positive or negative refracting surface is formed on the surface of the substrate on the side where the pattern of the light-shielding film is formed, corresponding to one or more of the refracting surfaces on one side, in the portion of the pattern formed by the opening. An exposure mask that is characterized by 8. The exposure mask according to claim 1, wherein the at least one refracting surface has a positive or negative refracting power in a direction orthogonal to a predetermined line, and the predetermined line has a ring shape. The light-shielding film is formed so as to shield the region inside the ring from light. 9. The exposure mask according to claim 1, 2 or 3 or 4 or 5 or 6 or 7 or 8, wherein one or more refracting surfaces are arranged in one row in one direction or two-dimensionally. An exposure mask, which is arranged in an array.