JPH0588355A - Reflection type mask and exposure device using the same - Google Patents

Abstract

PURPOSE:To easily form a projection pattern with a good contrast on a resist surface by providing a phase member which shifts the phase of a reflected radiation beam at part of a circuit pattern. CONSTITUTION:The reflection type mask having a circuit pattern for exposure transfer to the resist surface by utilizing the reflection of the reflected beam is provided with the phase member (phase shifter) 3, which shifts the phase of the reflected radiation beam, at part of the circuit pattern. Thus, the constitution of the circuit pattern for transfer of the reflection type mask used for the radiation beam such as X rays and ultraviolet rays is properly set. Consequently, the influence of diffraction is reduced without making the numerical aperture of a projection system so large and the excellent-contrast projection pattern can easily be formed on the resist surface while the depth of focus is held deep.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflective mask, an exposure apparatus and a device manufacturing method using the same, for example, X
A reflective mask suitable for a lithographic apparatus for manufacturing a semiconductor device, which irradiates a reflective mask with lines or vacuum ultraviolet rays, and reduces and projects a pattern on the reflective mask surface onto a resist on a wafer surface by a reflecting mirror, and the same. The present invention relates to an exposure apparatus using.

[0002]

2. Description of the Related Art In recent years, in lithography in which a fine structure is optically transferred to a resist in order to manufacture a semiconductor device, X-rays having a higher resolution are required as the semiconductor device is highly integrated and miniaturized. Alternatively, an exposure apparatus using vacuum ultraviolet rays has come into use.

In such an exposure apparatus, X-rays or vacuum ultraviolet rays from a light source such as a synchrotron or laser plasma are applied to a reflection type mask on which a circuit pattern for transfer is formed, and X reflected by the circuit pattern is reflected. Lines or vacuum ultraviolet rays are reduced and projected onto the resist on the wafer surface by a projection system including a plurality of reflecting mirrors.

As a reflection type mask used in such an exposure apparatus, there is one in which an absorber corresponding to a transfer circuit pattern or an antireflection film is provided on a reflecting mirror. Further, the reflecting mirror as a projection system uses a multilayer film, a crystal, or the like in which a plurality of substances are alternately laminated on the surface thereof.

FIG. 22 is a partial cross-sectional view of a part of a conventional reflective mask for X-rays or vacuum ultraviolet rays. In the figure, 1 is a substrate, which is made of, for example, quartz. Reference numeral 2 denotes a multilayer film, which is formed on the surface of the substrate 1 to form the reflection portion 2a. Reference numeral 4 is a non-reflecting portion that absorbs X-rays or vacuum ultraviolet rays. A circuit pattern to be transferred is formed by the reflective portion 2a and the non-reflective portion 4.

[0006]

The conventional reflective mask shown in FIG. 22 has a problem that when the transfer circuit pattern becomes fine, the contrast of the transfer circuit pattern decreases due to diffraction of light or X-rays. It was

FIG. 23 is an amplitude distribution of a projection pattern projected on a predetermined surface by the projection system when the reflective mask of FIG. 22 is used. FIG. 24 is an intensity distribution of the projection pattern of FIG. As shown in FIGS. 23 and 24, at the intermediate positions of the adjacent patterns, the phases of X-rays or vacuum ultraviolet rays diffracted from these patterns (hereinafter may be typically referred to as “X-rays”) are the same. Since the X-ray intensity is high, the contrast is low. Therefore, as shown in FIG. 25, the accuracy of the transferred resist shape is lowered.

On the other hand, if the numerical aperture of the projection system for projecting the reflective mask onto the resist on the wafer surface is increased, it is possible to reduce the influence of the contrast reduction of the transfer circuit pattern due to diffraction. However, in this case, the depth of focus of the projection system becomes shallow. For this reason, there is a problem in that the effect of defocusing is greatly affected by wafer alignment errors, wafer warpage, etc., and the contrast of the transfer circuit pattern is reduced.

According to the present invention, by appropriately setting the structure of the circuit pattern for transferring the reflection type mask for the radiation beam such as X-rays and ultraviolet rays, the diffraction can be performed without increasing the numerical aperture of the projection system. It is an object of the present invention to provide a reflective mask capable of easily forming a projection pattern of good contrast on a resist surface while reducing the influence of ..

[0010]

A reflection type mask of the present invention is a reflection type mask having a circuit pattern for exposing and transferring to a resist surface by utilizing reflection of a radiation beam,
It is characterized in that a phase member for changing the phase of the radiation beam reflected is provided on a part of the circuit pattern.

In addition, the reflective mask of the present invention includes: (a) The reflective mask changes the phase and light intensity of the reflected radiation beam.

(B) When the phase change δ of the radiation beam reflected through the phase member is n is an integer of 0 or more.

[0013]

[Equation 3] I made it so that

(C) The phase member is formed by providing a step on the surface of the substrate.

(D) When the height of the step portion is h, the wavelength of the radiation beam is λ, the angle of incidence of the radiation beam on the reflective mask is θ, and n is an integer of 0 or more.

[0016]

[Equation 4] It is characterized by the fact that

Further, as an exposure apparatus using the reflective mask of the present invention, a pattern composed of a reflecting portion for reflecting the radiation beam and a non-reflecting portion for absorbing and / or transmitting the radiation beam is provided on the substrate surface. Irradiating a radiation beam on a reflection mask provided with a phase member for changing the phase of reflection on a part of the reflection portion, and guiding the radiation beam reflected from the reflection mask to the wafer surface, In addition, the pattern on the reflective mask surface is exposed and transferred.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a sectional view of the essential parts of a reflective mask of the present invention.

In the figure, reference numeral 1 denotes a substrate, which is made of, for example, quartz. Reference numeral 2 denotes a multilayer film, which forms the reflection portion 2a. Reference numeral 4 is a non-reflecting portion made of an absorber that absorbs a radiation beam such as X-rays and vacuum ultraviolet rays. The reflective portion 2a and the non-reflective portion 4 form a circuit pattern that is projected and transferred onto the resist surface. Reference numeral 3 denotes a phase member (phase shifter), which is provided in a part of the reflection part 2a (every other reflection part 2a in the figure) and the phase of the X-ray reflected by the reflection part 2a is, for example, π.
(180 degrees).

In this embodiment, as shown in FIG. 1, a phase shifter 3 having a thickness of ¼ wavelength is provided on the surface of a substrate 1, and a reflective layer 2a made of a multilayer film 2 is formed on the phase shifter 3. An absorber pattern serving as the non-reflective portion 4 is further provided on the reflective layer 2a. Phase shifter 3 with thickness of 1/4 wavelength
The X-rays reflected by the upper multilayer film 2a and the X-rays reflected by the multilayer film 2a where there is no phase shifter 3 are out of phase with each other by π.

The amplitude distribution when the X-ray reflected by such a reflective mask is projected and imaged on the wafer (resist) by the projection system (imaging optical system) is as shown in FIG. The phase of the X-ray reflected by the reflection part 2a of the multilayer film on the phase shifter 3 having a thickness of 1/4 wavelength and the phase of the X-ray reflected by the reflection part 2a of the multilayer film in the part without the phase shifter 3 are deviated by π. Therefore, there is a portion where the amplitude becomes 0 between the two.

FIG. 3 is an intensity distribution of the projected pattern on the resist surface of the reflection type mask of FIG. 1, and FIG. 4 is an explanatory view of the pattern shape when the circuit pattern of the reflection type mask of FIG. 1 is transferred to the resist.

According to this embodiment, as shown in FIGS. 3 and 4, the contrast of the X-ray intensity is increased, and as a result, the accuracy of the transfer pattern is improved.

The structure of the multilayer film in this embodiment is properly selected according to the wavelength used. For example, when the wavelength of X-ray is 13 nm, the thickness is made of molybdenum and silicon, and the thickness is 3.1 nm for molybdenum and 3.6 n for silicon.
m, and the total number of layers is 50 layers.

Any material can be used as the material of the phase shifter 3 as long as it can be formed by controlling the film thickness. For example, a film of silicon, silicon dioxide, aluminum, chromium, molybdenum, nickel, carbon, tungsten, gold, platinum, or the like can be used. The patterning method may be an etching method, a lift-off method, or the like.

In addition to the method of forming a film on a substrate as described above, a method of removing a part of the substrate by etching or the like can be used as means for providing a step as a phase member on the substrate. Here, the case where the X-ray is vertically incident on the substrate 1 is shown, but when the incident angle is different from 0, the size of the step may be changed according to the angle. For example X
When the wavelength of the line is 13 nm, the step size is 3.25 nm and π / 4 if the X-ray is incident vertically on the reflective mask.
If it is incident at, 4.6 nm is appropriate.

FIG. 5 is a schematic view of a main part of an exposure apparatus using the reflective mask of the present invention.

In this embodiment, the beam from the undulator 6 for generating soft X-rays having a wavelength of 13 nm is expanded by the two reflecting mirrors, the convex mirror 7 and the concave mirror 8, to illuminate the reflective mask 9. Soft X with intensity and phase changed by the reflective mask 9
The line is reduced by a projection system (imaging optical system) consisting of two reflecting mirrors, a convex mirror 10 and a concave mirror 11.
2 is projected onto the resist applied. When a Schwarzschild optical system with a reduction ratio of 1/10 and a numerical aperture of 0.06 was used, a pattern with a line width of 150 nm could be resolved on the resist by using a conventional reflective mask that does not change the phase for each pattern. ..

On the other hand, when an exposure apparatus having the same image forming optical system uses a reflection type mask for changing the phase as shown in FIG. 1 of this embodiment, a pattern having a line width of 90 nm can be resolved, and It became possible to transfer fine patterns.

FIGS. 6, 7 and 8 are sectional views of the essential portions of Embodiments 2, 3 and 4 of the reflective mask of the present invention. 6, FIG.
8, the same elements as those shown in FIG. 1 are designated by the same reference numerals.

In the second embodiment of FIG. 6, the non-reflective portion 61 is not formed with the multilayer film 2 or is removed, and a circuit pattern is formed from this. In this case, the circuit pattern of the non-reflecting portion 61 can be formed by a usual semiconductor processing process such as electron beam drawing and a lift-off method or an etching method.

In the third embodiment of FIG. 7, the non-reflecting portion 71 is used as a non-reflecting portion for X-rays or vacuum ultraviolet rays by destroying the multilayer film structure with an ion beam or the like.

In Example 4 of FIG. 8, the pattern of the phase shifter 3 having a thickness of ¼ wavelength is provided on the surface of the substrate 1,
A reflective layer 2 made of a multilayer film is formed on the surface. In this embodiment, there is no non-reflecting portion and the entire surface is covered with the multilayer film 2. The amplitude distribution when the X-ray reflected by the reflective mask is projected and imaged on the wafer by the projection system (imaging optical system) is as shown in FIG. Since the X-ray reflected by the multilayer film 81 on the phase shifter 3 having a thickness of ¼ wavelength and the X-ray reflected by the multilayer film 82 in the portion without the phase shifter 3 are out of phase with each other, There is a part where the amplitude becomes 0.

FIG. 10 shows the intensity distribution of the projected pattern of the reflective mask of FIG. 8 on the wafer surface. FIG. 11 shows the pattern shape when the circuit pattern of the reflective mask of FIG. 8 is transferred to a resist.

According to this embodiment, the intensity distribution of the projected pattern has a high contrast of the X-ray intensity as shown in FIG. 10, and as a result, the accuracy of the transferred pattern is improved.

In this embodiment, the thickness of the phase shifter 3 is such that the phase of the reflected X-ray is changed by π.
This value does not necessarily have to be exactly π. In the experiment, if the amount δ of changing the phase is π / 2 <δ <3π / 2, it is confirmed that the accuracy of the transfer pattern is improved as compared with the conventional reflection type mask which does not change the phase. Therefore, the thickness of the phase shifter 3 is the amount δ that changes the phase of the reflected soft X-ray.
Is (2 × n + 1/2) × π <δ <(2 × n + 3/2) × π
The thickness may be within the range of n: an integer of 0 or more. As described above, the thickness of the phase shifter is not strictly set, but may be within a certain range, as in the other embodiments.

FIG. 12 shows Example 5 of the reflective mask of the present invention.
FIG.

In this embodiment, a step for changing the phase, that is, a phase shifter 3 is provided inside the region 121 where the reflection pattern of the substrate 1 is provided, and the multilayer film 2 is provided on the phase shifter 3 and the surface around it. .. This forms a reflection pattern.

The phase of the X-ray reflected by the inside 121a of the reflection pattern 121 and the periphery 121b is changed.
13 and 14 show the amplitude distribution and the intensity distribution when the X-ray reflected by the reflective mask is imaged on the wafer by the projection system (imaging optical system). In this way, the X-ray intensity is reduced between the reflection patterns, so that the contrast is improved and, as a result, the accuracy of the transfer pattern is improved.

FIG. 15 shows a pattern shape when the circuit pattern of the reflection type mask of FIG. 12 is transferred to a resist.

16 and 17 are cross-sectional views of the essential parts of Embodiments 6 and 7 of the reflective mask of the present invention. The sixth embodiment of FIG. 16 is different from the fifth embodiment of FIG. 12 in that the phase shifter 3 is provided in the peripheral portion 161b of the reflection pattern 161.

In Example 7 of FIG. 17, the absorber pattern 4 is provided on the multilayer film 2 to form the non-reflecting portion. Then, a predetermined phase difference is given to the reflected light from the reflective portion 4a and the reflected light from the reflective portion 2a in the peripheral region of the non-reflective portion 4. As a result, the same effect as that of the fifth embodiment shown in FIG. 12 is obtained.

FIG. 18 shows a reflective mask of Example 8 of the present invention.
FIG.

In this embodiment, the phase shifter 3 for changing the phase is provided inside the non-reflection area of the substrate 1 where the reflection pattern is not provided, and the reflection pattern 181 by the multilayer film 2 is formed thereon. .. 13 and 14 show the amplitude distribution and the intensity distribution when the X-ray reflected by the reflective mask is imaged on the wafer by the projection system (imaging optical system).
become that way. By thus reversing the phase of the X-rays between the reflection patterns, the intensity of the X-rays is reduced, the contrast is improved, and as a result, the accuracy of the transfer pattern is improved.

FIG. 21 shows a pattern shape when the circuit pattern of the reflection type mask of FIG. 18 is transferred to a resist.

In the present invention, a highly integrated semiconductor device can be easily manufactured by using the above-described reflective mask and exposing and transferring the circuit pattern formed on the surface thereof onto a wafer coated with a resist. be able to.

[0047]

As described above, according to the present invention, the numerical aperture of the projection system is increased to a large value by appropriately setting the configuration of the circuit pattern for transfer of the reflection type mask for X-rays or vacuum ultraviolet rays. A reflective mask and an exposure apparatus using the same that can easily form a projection pattern with good contrast on a resist surface while reducing the influence of diffraction and maintaining a deep depth of focus without doing so. Can be achieved.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of a reflective mask according to a first embodiment of the present invention.

FIG. 2 is an X-ray amplitude distribution of a projection pattern by the reflective mask according to the first embodiment of the present invention.

FIG. 3 is an X-ray intensity distribution of a projection pattern by the reflective mask of Example 1 of the present invention.

FIG. 4 is a shape of a resist pattern transferred by a reflective mask according to Example 1 of the present invention.

FIG. 5 is a schematic view of a main part of an exposure apparatus according to a first embodiment of the present invention, which uses a reflective mask of the present invention.

FIG. 6 is a sectional view of an essential part of a reflective mask according to a second embodiment of the present invention.

FIG. 7 is a sectional view of a reflective mask of Example 3 of the present invention.

FIG. 8 is a sectional view of a reflective mask according to a fourth embodiment of the present invention.

FIG. 9 is an X-ray amplitude distribution of a projection pattern by a reflective mask according to Example 4 of the present invention.

FIG. 10 is an X-ray intensity distribution of a projection pattern by the reflective mask of Example 4 of the present invention.

FIG. 11 is a shape of a resist pattern transferred by a reflective mask of Example 4 of the present invention.

FIG. 12 is a sectional view of a reflective mask of Example 5 of the present invention.

FIG. 13 is an X-ray amplitude distribution of a projection pattern by a reflective mask of Example 5 of the present invention.

FIG. 14 is an X-ray intensity distribution of a projection pattern by the reflective mask of Example 5 of the present invention.

FIG. 15 is a shape of a resist pattern transferred by a reflective mask of Example 5 of the present invention.

FIG. 16 is a sectional view of a reflective mask according to Example 6 of the present invention.

FIG. 17 is a sectional view of a reflective mask according to Example 7 of the present invention.

FIG. 18 is a sectional view of a reflective mask according to Example 8 of the present invention.

FIG. 19 is an X-ray amplitude distribution of a projection pattern by the reflective mask of Example 8 of the present invention.

FIG. 20 is an X-ray intensity distribution of a projection pattern by the reflective mask of Example 8 of the present invention.

FIG. 21 is a shape of a resist pattern transferred by a reflective mask of Example 8 of the present invention.

FIG. 22 is a sectional view of a conventional reflective mask.

FIG. 23 is an X-ray amplitude distribution of a projection pattern by the reflection type mask of the conventional example.

FIG. 24 is an X-ray intensity distribution of a projection pattern using a conventional reflective mask.

FIG. 25 is a shape of a resist pattern transferred by a conventional reflective mask.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Substrate 2 Reflective multilayer film 2a Reflecting part 3 Phase member (phase shifter) 4 X-ray absorber (non-reflecting part) 6 Undulator light source 7,8 Reflecting mirror 9 Reflective mask 10,11 Reflecting mirror (projection system) 12 Wafer

Claims (8)

[Claims] 1. A reflection type mask having a circuit pattern for exposing and transferring to a resist surface by utilizing the reflection of a radiation beam, wherein a phase member for changing the phase of the radiation beam reflected on a part of the circuit pattern is provided. A reflective mask. 2. A reflection type mask having a pattern comprising a reflecting portion for reflecting a radiation beam and a non-reflecting portion for absorbing and / or transmitting the radiation beam on a surface of a substrate and reflecting on a part of the reflecting portion. A reflective mask comprising a phase member for changing the phase of a radiation beam. 3. The reflective mask according to claim 1, wherein the reflective mask changes a phase and a light intensity of a reflected radiation beam. 4. A phase change δ of a radiation beam reflected through the phase member, where n is an integer of 0 or more. The reflective mask according to claim 1, wherein 5. The reflective mask according to claim 1, wherein the phase member is formed by providing a step on the surface of the substrate. 6. When the height of the step portion is h, the wavelength of the radiation beam is λ, the incident angle of the radiation beam on the reflective mask is θ, and n is an integer of 0 or more, The reflective mask according to claim 5, wherein 7. A pattern comprising a reflecting portion for reflecting the radiation beam and a non-reflecting portion for absorbing and / or transmitting the radiation beam is provided on the substrate surface, and the radiation beam for reflecting a part of the reflection portion is provided. A radiation beam is applied to a reflective mask provided with a phase member that changes the phase, the radiation beam reflected from the reflective mask is guided to the wafer surface, and the pattern on the reflective mask surface is exposed and transferred to the wafer surface. An exposure apparatus using a reflective mask. 8. A method of manufacturing a semiconductor device, wherein the circuit pattern formed on the reflective mask according to claim 1 or 2 is exposed and transferred onto a wafer coated with a resist to manufacture a semiconductor device.