JPH05241324A - Photomask and exposing method - Google Patents

Abstract

PURPOSE:To obtain a high-contrast image by controlling a polarization state. CONSTITUTION:Line-and-space (L/S) patterns arranged in the longitudinal direction of the plane of Fig. are formed in a region C and L/S patterns arranged in the vertical direction of the plane of Fig. are formed in a region D and phase shift films are provided in alternately every other space parts (transparent parts). E is an isolated pattern of a square shape. A polarizing film 15 corresponding to a half-wave plate is provided in the L/S pattern part of the region D and a polarizing film 16 corresponding to a quarter-wavelength plate is provided in the part E. The mask is illuminated with linearly polarized light vibrating in the direction parallel with the side of the L/S patterns in the region C, by which the pattern image is stepped onto a wafer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask (also called a reticle) used as a projection original plate in a lithography process for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art In a lithography process for manufacturing a semiconductor device, a photomask used as a projection original plate generally has a structure in which a light-shielding pattern made of metal such as chromium is formed on a transparent substrate. A desired circuit pattern is transferred onto the wafer surface by illuminating the photomask through transmission and forming an image of the light-shielding pattern on the wafer surface by the projection optical system.

In addition, various phase shift masks have recently been proposed in which a phase shift portion for changing the phase of transmitted light is provided at a specific portion of a transparent portion in order to increase the contrast of a projected image. For example, Japanese Patent Publication No. Sho 62-50811 discloses a technique relating to a spatial frequency modulation type phase shift mask.

[0004]

However, the conventional technique as described above has a problem that it cannot cope with the miniaturization of circuit patterns accompanying the recent high integration of semiconductor elements. That is, in a photomask that is composed only of a substrate bare surface portion (transparent portion) and a light shielding portion that has been conventionally used,
Projection transfer of a pattern image is performed using information on the amplitude of light. In a recently developed phase shift mask, the contrast of the pattern image is enhanced by adding the information on the phase of light to the information on the amplitude of light. However, these methods have their own limitations in imaging performance, and satisfactory high-contrast images cannot be obtained for fine patterns.

The present invention has been made in view of the above points, and provides a photomask capable of realizing high-resolution and high-contrast imaging performance by controlling the polarization state in addition to the phase of light. It is intended to be provided.

[0006]

According to a first aspect of the present invention, there is provided a photomask in which a pattern to be projected and transferred is formed on a transparent substrate. , A phase shift member for changing the phase of transmitted light is provided at a predetermined position, and at least a part of a polarizing member for transmitting only light in a predetermined polarization state according to the arrangement direction of the pattern is provided. is there.

In the photomask of the second aspect, the polarizing member transmits only light whose electric vector oscillates in a direction parallel to the longitudinal direction of the sides of the pattern. In the photomask of claim 3, a light amount control member for controlling the amount of transmitted light is provided in a portion of the transparent portion where the polarizing member is not provided. The photomask according to claim 4, wherein the pattern includes a first portion arranged in a certain direction and a second portion having a different arrangement direction from the first portion, and the polarizing member is provided in at least the second portion. It is provided.

According to a fifth aspect of the exposure method, a photomask having a predetermined pattern formed on a transparent substrate is illuminated with the exposure light, and the light transmitted through the transparent portion of the photomask is used.
In an exposure method of projecting and exposing the pattern onto a substrate through a projection optical system, in order to achieve the above-mentioned object, a phase shift member that changes the phase of the transmitted light is specified as the transparent portion as the photomask. A polarizing member that is provided at the location and that converts a light in a predetermined polarization state according to the arrangement direction of the pattern into at least a part of the transparent portion is used, and the predetermined polarization is applied to the photomask. The exposure light of the state is illuminated to project and expose the pattern of the photomask on the substrate.

[0009]

The operation of the present invention will be described with reference to FIGS. In the general exposure apparatus shown in FIG. 2, when the photomask 21 is illuminated with light from the illumination optical system 24, diffracted light is generated according to the pattern on the photomask 21.
These diffracted lights (in the figure, 0-th order diffracted lights and ± 1st-order diffracted lights are shown) are again collected on the image plane 23 by the projection optical system 22, whereby the pattern image of the photomass 21 is transferred onto the wafer surface. It

Next, FIGS. 3 (a) and 3 (b) schematically show the state of the diffracted light in the vicinity of the image plane 23. Figure 3 (a) shows
This is a state called TE (transverse electric) polarized light, in which the vibration direction of the electric vector is light perpendicular to the incident surface (the inner surface of the paper). On the other hand, Fig. 3 (b) shows TM (transverse mag
This is a state called netic) polarization, in which the vibration direction of the magnetic vector is perpendicular to the incident surface, that is, the vibration direction of the electric vector is in the incident surface. In a conventional photomask without a polarizing member, the average state of TE polarized light in Fig. 3 (a) and TM polarized light in Fig. 3 (b) is observed, but the photochemical reaction of the photosensitive material such as photoresist is caused by electromagnetic waves. Since it proceeds by the action of an electric field of a certain light, the vibration direction of the electric vector becomes a problem in the lithography process.

As can be seen by comparing FIGS. 3 (a) and 3 (b), in the case of TE polarization, the vibration directions of the electric vectors of the 0th order, ± 1st order ... Diffracted lights are all perpendicular to the paper surface. The images are aligned in the same direction, and the interference effect between the diffracted lights is maximized, resulting in a high-contrast image. In the case of TM-polarized light, the vibration direction of the electric vector of diffracted light of different orders is shifted by an amount corresponding to the angle formed by the traveling directions of the diffracted lights, and the interference effect between the diffracted lights decreases, and It works to reduce the contrast.

The general description has been given above, but to make it easier to understand, as a concrete example, a line-and-space pattern extending in the direction perpendicular to the paper surface of the photomask 21 (a light-shielding portion and a transparent portion have the same width alternately). Consider a case in which a pattern image is formed by the 0th-order diffracted light and the ± 1st-order diffracted light of the diffracted light from the photomask 21. In this case, the amplitude of the 0th-order diffracted light is 1/2, and the amplitude of the ± 1st-order diffracted light is 1 / π.

As shown in FIG. 3, x (horizontal direction of paper), y (vertical direction of paper), z (vertical direction of paper) coordinate axes are set, and the direction cosine of the 0th-order diffracted light is (0, 0, 1). ), ±
Letting the direction cosine of the first-order diffracted light be (± α, 0, γ), the wave (vector amount) of the _0th-order diffracted light and the ± first-order diffracted light is ψ ₀ , ψ
Assuming ± ₁ , the wave motion of each diffracted light in case of TE polarization is
It is represented by. In the formula, k is a constant (= 2π / λ).

[0014]

[Equation 1]

Waves ψ _{0 of 0th-order} diffracted light and ± 1st-order diffracted light,
The wave field Ψ _TE that combines ψ ± ₁ is given by Equation 4, and the intensity distribution I
_TE (x, z) = | Ψ | ² is given by Equation 5.

[0016]

[Equation 2]

On the other hand, the waves of each diffracted light in the case of TM polarized light are represented by equations 6-8.

[0018]

[Equation 3]

Waves ψ _{0 of 0th-order} diffracted light and ± 1st-order diffracted light,
The wave field Ψ _{TM that} is a combination of ψ ± ₁ is Equation 9, and the intensity distribution I _TM (x, z) = | Ψ | ² is Equation 10.

[0020]

[Equation 4]

Now, consider a log slope value as an image evaluation index. And the log slope value, a differential value when the logarithm of the intensity I of the geometric bright-dark limit, i.e. the value of ∂log I / ∂ _X. The larger this value is, the higher the contrast of the image. From Equation 5 and Equation 10,
It is possible to calculate log slope values for TE polarized light and TM polarized light, respectively. Assuming that the best focus plane is considered for the sake of simplicity, if Z = 0 is calculated, the log slope value LS _{TE for TE} polarized light is given by equation 11, and the log slope value for TM polarized light is given by equation LS _TM. Twelve. The log slope value when non-polarized light is an average state of TE polarized light and TM polarized light.

[0022]

[Equation 5]

Considering the term multiplied by 4λ / α in expression 12, it is understood that the value of expression 12 is smaller than the value of expression 11 as a whole because the numerator is smaller than 1 and the denominator is larger than 1. To be done. This indicates that the image with TE polarization has a higher log slope than the image with TM polarization. Further, since α corresponds to the diffraction angle, the superiority of the TE polarized light increases as the fine pattern has a larger diffraction angle.

Further, since the non-polarized state is an average state of TE polarized light and TM polarized light, the image formation by TE polarized light is naturally
The so-called high-contrast image having a higher log slope value is achieved than the image formation by non-polarized light. That is, a polarizing member is provided on the transparent portion of the photomask,
The contrast of the fine pattern image can be increased by converting the exposure light in the non-polarized state (average state of TE polarized light and TM polarized light) into the TE polarized state and forming an image with only the TE polarized light. Then, by combining the phase shift pattern and the polarizing member, the interference effect of the phase shift pattern is enhanced, and an image with high resolution and high contrast is realized.

Here, in the mask used for manufacturing the integrated circuit, there are many portions in which the arrangement directions of the patterns are aligned in a certain direction, and in many cases, there are patterns partially having different arrangement directions or isolated patterns. In such a case, the mask is illuminated by light whose electric vector oscillates in a direction parallel to the longitudinal direction of the pattern of the portion (first portion) where the arrangement directions are aligned, and the portion where the arrangement direction of the mask is different (first portion) It is sufficient to provide a polarizing member in the transparent part (2 part) and change the polarization state of the light transmitted through that part. By doing this, a high-resolution, high-contrast image can be obtained over the entire projection area,
In addition, since the type of the polarizing member on the mask side and the area for forming the polarizing member can be reduced, the mask can be easily manufactured.

[0026]

1 (a) and 1 (b) are a plan view and a sectional view showing the structure of a photomask according to a first embodiment of the present invention. In the figure, a light-shielding film 11 made of chromium or the like is provided on a lower surface of a transparent substrate 10 made of quartz or the like at a predetermined pitch. The light shielding film 11 in this embodiment is formed sufficiently long in the direction perpendicular to the paper surface (compared to the pitch in the paper surface direction), and forms a so-called line and space pattern in which the transparent portions 2 and the light shielding portions 1 are alternately repeated. is doing. The phase of the transmitted light is λ
A phase shift film 12 that changes by / 2 is provided. In addition, on the upper surface of the transparent substrate 11, a polarizing film 13 that transmits only light having a vibrating surface of an electric vector in a direction parallel to the side of the light shielding film 11 (that is, a direction perpendicular to the paper surface) is provided. It is provided so as to cover the entire space pattern. In the example of FIG. 1, the light shielding film 13 is the transparent substrate 1
Although it is attached to the upper side of 1, it is also possible to attach it to the lower side (side of the light shielding pattern formation surface).

Image formation when the photomask of FIG. 1 is used in the exposure apparatus described in FIG. 2 will be described next. First, when the photomask 21 is transilluminated with the exposure light from the illumination optical system 24, the exposure light is diffracted by the line and space pattern extending in the direction perpendicular to the paper surface, and the diffracted light spreads in the paper surface. At this time, the photomask 2 of FIG.
Since the polarizing film 13 that transmits only the light whose electric vector oscillates in the direction perpendicular to the paper surface is provided on the upper surface of the transparent substrate 1 of FIG. 1, only the TE-polarized diffracted light is emitted from the photomask 21. The diffracted light from the photomask 21 is collected again by the projection optical system 22, an image of the line-and-space pattern of FIG. 1 is formed on the image forming surface 23, and the image is held horizontally on the image forming surface 23. The circuit pattern is transferred onto the wafer (not shown) surface.

In this embodiment, since the electric vector is imaged only by the light oscillating in the direction parallel to the sides of the pattern, the interference effect between the diffracted lights is enhanced as described in the section of the action. Since the phase of the transmitted light is different by λ / 2 between the adhered part and the non-adhered part of the phase shift film 12, the light sneaks into the light shielding part 1 from the adjacent transparent part and the light is canceled out, and the image plane 23 is shielded. A clear dark line is formed at a position corresponding to the film 11. Further, as the pattern pitch becomes smaller, the diffraction angle of the diffracted light of the first order or more becomes larger, so that the non-polarized state (T
When the image is formed by the light of the E-polarized light + the TM-polarized light, the contrast of the image is reduced by the amount of deviation of the vibration direction of the TM-polarized light, but the image is formed only by the TE-polarized light as in the present embodiment. In that case, since the vibration direction of the electric vector does not change even if the diffraction angle changes, high contrast is maintained. That is, by using the photomask having the structure as shown in FIG. 1, it is possible to obtain a high-contrast image even if the pitch of the line-and-space pattern is extremely small, and the finer pattern is superior to the conventional photomask. Becomes clear.

Next, FIGS. 4A and 4B show a second embodiment of the present invention.
3A and 3B are a plan view and a cross-sectional view of a photomask according to an example.
This example is a so-called edge enhancement type, and has an effect of reducing side lobes when forming an isolated line. In the figure, a narrow transparent portion 2a different from the transparent portion 2 is provided at the edge portion of the light shielding portion 1. This transparent portion 2a
Is a phase shift film 12 that changes the phase of transmitted light by λ / 2.
Is provided. Further, on the upper surface of the transparent substrate 10, a polarizing film 13 for transmitting only light having an oscillating surface of an electric vector in a direction parallel to the side of the light shielding film 11 is provided so as to cover between the light shielding portions 1. In such a photomask, the light that circulates from the transparent portion 2 to the edge portion of the light shielding portion 1 interferes with the light from the narrow transparent portion 2a provided at the edge portion and is canceled, so that a pattern image with a sharp edge is obtained. can get. In this example as well, the contrast of the pattern can be enhanced by not only providing the phase shift film but also aligning the polarization directions.

Next, FIG. 5A is a plan view of a photomask according to a third embodiment of the present invention, and FIG. 5B is a plan view of a corresponding conventional example. In the figure, the first part A is
Line-and-patterns similar to those in FIG. 1 in which the light-shielding portions 1 and the transparent portions 2 are alternately repeated are arranged in the lateral direction of the drawing.
On the other hand, in the second portion B, line and patterns arranged in the vertical direction of the paper surface are formed. Further, every other transparent portion 2 is provided with a phase shift film (not shown) so that the phase difference of the light from the adjacent transparent portions 2 via the light shielding portion 1 becomes λ / 2. ..

Here, in the conventional example of FIG. 5B, the light from the transparent portion 2 of the first portion A and the light from the transparent portion 2 of the second portion B interfere with each other to cause distortion in the pattern image. In order to avoid this, it is necessary to change the phase between the first portion A and the second portion B. That is, as shown in the figure, if the phase of the transparent portion 2 of the first portion A is 0, π, 0, π ...
The phase of the transparent part is 3π / 2, π / 2, 3π / 2, π / 2
.., which requires four kinds of phase shift films, which makes it very difficult to manufacture a mask.

On the other hand, in FIG. 5A of the embodiment of the present invention, the first and second portions A and B respectively have a polarizing film (FIG. 5) which transmits only light oscillating in the direction parallel to the sides of the pattern. (Not shown) is provided so that the transmitted light from the first portion and the transmitted light from the second portion do not interfere with each other. Therefore, it is not necessary to change the phase of the transmitted light between the first part A and the second part B (the phase of the transparent part 2 may be 0, π, 0, π ... In both parts), and the phase shift film is 2 There are only types.

Next, an example in which an isolated pattern is included (fourth embodiment) will be described with reference to FIGS. 6 (a) and 6 (b). One mask may include not only the line-and-space pattern shown in FIG. 5 but also an isolated circular or square pattern. In the line-and-space pattern, it is desirable to form an image by linearly polarized light that vibrates in the direction parallel to the sides of the pattern as described above, but for isotropic patterns such as circles and squares, random polarized light with good symmetry is used. It is better to form an image in (non-polarized state) or circularly polarized light.

However, for example, when randomly polarized light is used as the illumination light and a polarizing film is provided only for the line and space pattern portion so that the vibration directions are aligned, the amount of light in the line and space pattern portion that transmits only light in a specific polarization state Will decrease. Therefore, the amount of light is relatively increased in the isolated pattern portion.
The inconvenience arises that the optimum exposure time differs for three different pattern portions. In order to avoid such an inconvenience, it is desirable to reduce the transmittance of the portion where the polarization state is not controlled. FIG. 6 also shows this example.

In FIG. 6A, the same line and space pattern (light-shielding film 11 and phase shift film 12) as in FIG. 1 is formed in the region on the right side of the transparent substrate 10,
A polarizing film 13 that transmits only linearly polarized light vibrating in a direction parallel to the sides of the pattern is provided in this portion.
Further, an isotropic isolated pattern is formed in the region on the left side of the transparent substrate 10 in the figure, and a density filter 14 is provided in the transparent portion of this part. By adjusting the transmittance of the isolated pattern portion by the density filter 14, it is possible to match the light amounts of the line and space pattern portion and the isolated pattern portion.

FIG. 6B shows an example in which the transmittance of the isolated pattern portion is adjusted without using the density filter. In this example, a fine pattern 17 exceeding the resolution limit of the projection lens is formed on the transparent portion of the isolated pattern, and the transmitted light is scattered to reduce the light amount. The amount of transmitted light is adjusted by controlling the size, array pitch, and number of the fine patterns 17. Fine pattern 17 of FIG.
May be formed of a light shielding film or a phase shift film.

Next, FIG. 8 is a perspective view showing a schematic structure of an exposure apparatus used in the exposure method according to the fifth embodiment of the present invention. In this embodiment, a polarizing plate 36 is provided in the illumination optical system. .. In the figure, the illumination light emitted from a light source 31 such as a mercury lamp is an elliptical mirror 32, a mirror 33, and a condenser lens 3.
4. The light enters the polarizing plate 36 through the optical integrator 35. The polarizing plate 36 is supported by a support 37 and is rotatable about the optical axis A _x or an axis parallel to the optical axis A _x . This rotation is performed by the support 37
It is performed by a motor (not shown) provided above. Therefore, the illumination light flux passing through the polarizing plate 36 is
Is a light beam having a polarization direction (linearly polarized light) according to the rotation direction of.

The light flux passing through the polarizing plate 36 is guided to condenser lenses 38 and 40 and a mirror 39 to illuminate a pattern (on the lower surface) on a photomask (reticle) 41. The transmitted and diffracted light from the photomask 41 is condensed and imaged by the projection optical system 43 to form an image of the mask pattern 12 on the wafer 14. At this time, if the mirror 39 in FIG. 8 is displaced from the position perpendicular or parallel to the vibration direction of the illumination light, the linearly polarized light will be converted into the elliptically polarized light. .. The polarizing plate 36 is
It may be arranged between the condenser lens 34 and the optical integrator 35 or between the condenser lens 38 and the photomask.

Here, FIG. 7 shows a plan view and a sectional view of a mask pattern in this embodiment. In the figure, the pattern of the area C (first portion) is the same as that described in FIG.
It is a dimensional line-and-space pattern, and the arrangement direction is the lateral direction of the paper (see FIG. 7A). Although only a part of the mask pattern is shown in the drawing, many regions of the mask of this embodiment have the same arrangement direction as the pattern of the C region. Further, the pattern of the area D (second portion) in the drawing has a different arrangement direction from the area C, and is a line-and-space pattern arranged in the vertical direction of the paper. The phase shift film 12 is provided in every other space portion (transparent portion) of the patterns in the regions C and D. In the figure, E is a square isolated pattern,
Different polarizing films (described later) are provided in the regions D and E, respectively.
Is provided.

In this embodiment, the polarization direction of the illumination light is aligned in parallel with the longitudinal direction of the pattern C of the mask 41 by the polarizing plate 36 of the exposure device shown in FIG. This allows
According to the same principle as that of the embodiment of FIG. 1 described above, the contrast of the fine line-and-space pattern image of the C portion occupying most of the mask can be improved. At this time, in the area D, the illumination light vibrates in a direction orthogonal to the sides of the pattern, but in the present embodiment, the area D is provided with the polarizing film 15 corresponding to a half-wave plate. Thus, the vibration direction of the transmitted light in the area D is changed by 90 degrees. As a result, the pattern of the region D is also imaged by the linearly polarized light vibrating in the direction parallel to the side of the pattern, and an image with high contrast can be obtained. Further, in the non-directional E portion, the polarizing film 16 corresponding to the quarter wavelength plate is provided to convert the illumination light, which is linearly polarized light, into circularly polarized light.

As described above, in this embodiment, good image formation is realized for the entire mask pattern. In the present embodiment, in accordance with the most array direction in the mask pattern, the illumination light itself is linearly polarized, and on the mask side, the array direction is different, so that the polarizing film is provided only on the part having no directivity. The mask is easy to manufacture. Further, when the randomly polarized light is illuminated and only the light vibrating in a specific direction is transmitted by the polarizing film provided for each region, the polarizing film absorbs the illumination light. It is also advantageous in avoiding the influence of heat absorption on the image formation.

Although the light source 31 is a mercury lamp in FIG. 8, it may be another lamp or a laser light source. Particularly when the light source is a laser which emits linearly polarized light or circularly polarized light, a ½ wavelength plate or a ¼ wavelength plate can be used as the polarization means (polarizing plate 36) on the exposure apparatus side.

Next, FIG. 9A is an explanatory view showing an example of the polarization means when a laser is used as a light source. In the figure, incident light L ₀ (light flux from the light source) that is linearly polarized light (the polarization direction is the vertical direction on the paper surface) is incident on the ½ wavelength plate 36 a. At this time, it is assumed that the direction of the reference axis of the half-wave plate 36a (two-dot chain line in the figure) is inclined by θ with respect to the polarization direction of the incident light L ₀ . As a result, the polarization direction of the emitted light L ₁ is inclined by 2θ with respect to the polarization direction of the incident light L ₀ . Therefore, by rotating the half-wave plate 36a in the plane perpendicular to the illumination light by the holder 37, the polarization direction of the emitted light L ₁ can be set to an arbitrary direction.

The reference axis of the half-wave plate 36a is, as shown in FIG. 9B, l ₁ = m for transmitted light in the polarization direction parallel to the reference axis (two-dot chain line). An optical path length difference of ₁ λ + α is given, and l ₂
= M ₂ λ + α + λ / 2 as an axis giving an optical path length. However, m ₁ and m ₂ are integers.

When the light emitted from the light source is circularly polarized light instead of linearly polarized light, the quarter wave plate is used instead of the half wave plate, and the emitted light is emitted in the same manner as described with reference to FIG. The polarization direction of can be controlled. In this case, the emitted light beam becomes linearly polarized light according to the rotational position direction of the quarter-wave plate.

As described above, a laser that emits linearly polarized light or circularly polarized light is used as the light source, and 1/2 is used as the polarization means.
If a wave plate or a quarter wave plate is used, the polarization direction can be converted to an optimum direction and guided to the mask without loss of the light amount from the light source. On the other hand, when a lamp is used as the light source (when unpolarized light is emitted from the light source), the amount of light after passing through the polarizing film is theoretically halved, so it is necessary to pay attention to this point. is there.

As the polarization means, a quarter wavelength plate, a 1 /
When a two-wave plate is used, it is desirable that the incident light flux be close to a parallel light flux. Therefore, it is preferable that the quarter-wave plate and the half-wave plate are set, for example, on the light source (laser light source) side of the relay lens 34, not after the optical integrator 35 in FIG. This arrangement may be applied to the case where a light source such as a mercury lamp is used. Further, in the photomask used in this example, the polarizing film was not provided in the portion C (first portion) in which the alignment directions were aligned, but the polarization state of the illumination light was controlled, and then the first portion was further formed. Needless to say, a polarizing film may be provided.

[0048]

As described above, in the photomask of the present invention, the phase shift member changes the phase of the transmitted light at a specific portion, and a polarizing film is further provided so that the polarization state of the transmitted light is parallel to the sides of the pattern. Since it is aligned with the direction, an image with very high contrast can be obtained. Also,
In the exposure method of the present invention, the polarization state of the illumination light is controlled in accordance with the pattern of the aligned parts in the array direction, and the polarizing film is provided in the parts in the array direction of the mask pattern. Good image formation can be realized in the entire pattern.

[Brief description of drawings]

1A and 1B are a plan view and a cross-sectional view of a photomask according to a first embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a general exposure apparatus.

3A and 3B are conceptual diagrams for explaining the operation of the present invention.

4A and 4B are a plan view and a sectional view of a photomask according to a second embodiment of the present invention.

5A is a plan view of a photomask according to a third embodiment of the present invention, and FIG. 5B is a plan view of a conventional photomask.

6A and 6B are a plan view and a sectional view of a photomask according to a fourth embodiment of the present invention.

7A and 7B are a plan view and a sectional view of a photomask according to a fifth embodiment of the present invention.

FIG. 8 is a perspective view showing a configuration of a main part of an exposure apparatus used in a fifth embodiment of the present invention.

9A and 9B are conceptual diagrams for explaining a polarization unit of an exposure apparatus.

[Explanation of symbols]

1 ... Shading part, 2 ... Transparent part, 10 ... Transparent substrate, 12 ... Phase shift part, 13, 15, 16 ... Polarizing film, 14 ... Density filter, 31 ... Light source, 32 ... Elliptic mirror, 33, 39 ... Mirror, 34 ... Condensing lens, 35 ... Optical integrator, 36 ... Polarizing plate, 36a ... 1/2 wavelength plate, 37 ... Support tool, 38, 40 ... Condenser lens, 41 ... Photomask, 43 ... Projection optical system, 44 ... Wafer

[Procedure amendment]

[Submission date] September 11, 1992

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] 0003

[Correction method] Change

[Correction content]

In addition, the contrast of the projected image is increased.
Therefore, for example, Japanese Patent Publication No. 62-50811 discloses that
Change the phase of the transmitted light to a specific part of the transparent part of the mask.
Techniques for phase shift masks with a phase shift unit
The technique is disclosed.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

[0006]

Means for Solving the Problems A photomask according to claim 1, in the photomask of the pattern to be projected to be transferred is formed on a transparent substrate, in order to achieve the above object, the transparent portion of said transparent substrate , A phase shift member for changing the phase of transmitted light is provided at a predetermined position, and at least a part of a polarizing member for transmitting only light in a predetermined polarization state according to the arrangement direction of the pattern is provided. is there.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Correction content]

Next, FIGS. 3 (a) and 3 (b) schematically show the state of the diffracted light in the vicinity of the image plane 23. Figure 3 (a) shows
This is a state called TE (transverse electric) polarized light, in which the vibration direction of the electric vector is light perpendicular to the incident surface (inner surface of the paper). On the other hand, FIG. 3 (b) shows TM (transverse m
This is a state called polarized light, in which the vibration direction of the magnetic vector is perpendicular to the incident surface, that is, the vibration direction of the electric vector is in the incident surface. Conventional photo without a polarizing member
In the mask , the average state of TE polarized light of FIG. 3 (a) and TM polarized light of FIG. 3 (b) is observed, but the photochemical reaction of the photosensitive material such as photoresist proceeds by the action of the electric field of light which is an electromagnetic wave. Therefore, the vibration direction of the electric vector becomes a problem in the lithography process.

[Procedure amendment 4]

[Document name to be amended] Statement

[Item name to be corrected] 0040

[Correction method] Change

[Correction content]

In this embodiment, the polarization direction of the illumination light is aligned in parallel with the longitudinal direction of the pattern C of the mask 41 by the polarizing plate 36 of the exposure device shown in FIG. This allows
According to the same principle as that of the embodiment of FIG. 1 described above, the contrast of the fine line-and-space pattern image of the C portion occupying most of the mask can be improved. At this time, in the region D, the illumination light vibrates in the direction orthogonal to the sides of the pattern, but in this embodiment, the polarized light corresponding to the half-wave plate is present in the region D. By providing the film 15, the vibration direction of the transmitted light in the region D is changed by 90 degrees. As a result, the pattern of the area D is also imaged by the linearly polarized light vibrating in the direction parallel to the sides of the pattern, and an image with high contrast is obtained. Further, in the non-directional E portion, the polarizing film 16 corresponding to the quarter wavelength plate is provided to convert the illumination light, which is linearly polarized light, into circularly polarized light.

Claims (5)

[Claims] 1. A photomask in which a pattern to be projected and transferred is formed on a transparent substrate, and a phase shift member for changing a phase of transmitted light is provided at a predetermined position in a light transmitting portion of the transparent substrate. A photomask, wherein at least a part of the photomask is provided with a polarizing member that transmits only light having a predetermined polarization state according to the arrangement direction of the pattern. 2. The photomask according to claim 1, wherein the polarizing member transmits only light whose electric vector oscillates in a direction parallel to the longitudinal direction of the sides of the pattern. 3. The photomask according to claim 1, wherein a light amount control member for controlling the amount of transmitted light is provided in a portion of the light transmitting portion where the polarizing member is not provided. 4. The pattern includes a first portion arranged in a certain direction and a second portion having an arrangement direction different from that of the first portion, and the polarizing member is provided at least in the second portion. The photomask according to claim 1, wherein the photomask is a photomask. 5. An exposure method in which a photomask having a predetermined pattern formed on a transparent substrate is illuminated with exposure light, and the pattern is projected and exposed on the substrate by light transmitted through a transparent portion of the photomask. As the photomask, a phase shift member that changes the phase of the transmitted light is provided at a specific location of the transparent portion, and a polarization member that converts light into a predetermined polarization state according to the arrangement direction of the pattern is provided. An exposure characterized by using a photomask provided on at least a part of a transparent portion, illuminating the photomask with exposure light in a predetermined polarization state, and projecting and exposing the pattern of the photomask onto the substrate. Method.