JP4838646B2 - Photomask, exposure apparatus and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve use efficiency of light in entire lithography by efficiently utilizing excessive spectra generating at shorter wavelengths than i-line without abandoning. <P>SOLUTION: A material having a band gap wavelength of near 365 nm between the conduction band and the valence band is disposed in a path from a light source to a substrate so that the material receives rays at wavelengths shorter than the band gap wavelength in the light emitting from the light source, exciting electrons in the valence band to one of energy levels in the conduction band and inducing emission of light at the band gap wavelength from the conduction band by the excited electrons. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a photomask, an exposure apparatus, and a method, and more particularly, to a photomask, an exposure apparatus, and a method that are suitable for efficiently using light emitted from a light source.

  2. Description of the Related Art Conventionally, an exposure apparatus used for manufacturing a semiconductor element projects and transfers a circuit pattern formed on a photomask onto a photosensitive substrate such as a wafer via a projection optical system. A resist is applied on the photosensitive substrate, and the resist is exposed by projection exposure through a projection optical system to obtain a resist pattern corresponding to the mask pattern. Usually, this resist is sensitive to ultraviolet rays and visible light.

  By the way, in recent years, the development of semiconductor microfabrication technology has realized semiconductor devices with a fine structure up to the size where the quantum mechanical effect appears prominently. Also, semiconductor devices using this quantum mechanical effect and nanometer size have been realized. Nanodevices such as miniaturized polarizing elements have also been proposed. When finely processing such a nanodevice, it can be said that it is desirable to use i-line having a shorter wavelength than g-line as an exposure light source because the resolution can be further improved. Conventionally, an apparatus for performing exposure using the i-line has been proposed (for example, see Patent Document 1).

FIG. 5 shows a spectrum analysis result of light emitted from an Hg lamp as a light source. A high-intensity spectrum is observed for i-line (365 nm), h-line (405 nm), and g-line (436 nm), and many spectra are generated at shorter wavelengths than this i-line (hereinafter referred to as “line”). The spectrum generated at a shorter wavelength than these i lines is referred to as an extra spectrum.) Conventionally, only the light component having a wavelength corresponding to the i-line among the light emitted from such an Hg lamp is used, and the extra spectrum is discarded without being particularly utilized. For this reason, there has been a problem that the light emitted from the Hg lamp cannot be utilized efficiently.
JP 2002-248338 A

  Therefore, the present invention has been devised in view of the above-described problems, and the object of the present invention is to efficiently use an unnecessary spectrum generated at a shorter wavelength than the i-line without throwing away the spectrum. An object of the present invention is to provide a photomask, an exposure apparatus and a method capable of improving the light use efficiency of the entire lithography.

  In order to solve the above-described problems, the photomask according to the present invention is made of a material having a band gap wavelength between a conduction band and a valence band of around 365 nm, and the band gap wavelength of the light emitted from the light source. In response to the following light, electrons in the valence band are excited to any one energy level in the conduction band, and light corresponding to i-line is emitted from the conduction band based on the excited electrons. It is characterized by that.

  In order to solve the above-described problems, the photomask according to the present invention is made of a material having a band gap wavelength between a conduction band and a valence band in the vicinity of 405 nm, and the band out of the light emitted from the light source. In response to light having a gap wavelength or less, electrons in the valence band are excited to any one energy level in the conduction band, and light corresponding to h-line is emitted from the conduction band based on the excited electrons. It is characterized by releasing.

  Furthermore, in order to solve the above-described problems, the photomask according to the present invention is made of a material having a band gap wavelength between the conduction band and the valence band of around 436 nm, and the band out of the light emitted from the light source. In response to light having a gap wavelength or less, electrons in the valence band are excited to any one energy level in the conduction band, and light corresponding to g-line is emitted from the conduction band based on the excited electrons. It is characterized by releasing.

  In order to solve the above-described problems, an exposure apparatus according to the present invention is an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate through a plurality of optical elements with light emitted from a light source. In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between the conduction band and the valence band near 365 nm is disposed, and the material is equal to or less than the band gap wavelength of the light emitted from the light source. In response to this light, the electrons in the valence band are excited to any one energy level in the conduction band, and light corresponding to i-line is emitted from the conduction band based on the excited electrons. It is characterized by.

  Further, an exposure apparatus according to the present invention is an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate through a plurality of optical elements by light emitted from a light source in order to solve the above-described problems. In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band in the vicinity of 405 nm is disposed, and the material is the band gap of the light emitted from the light source. Receiving light of a wavelength or less, the electrons in the valence band are excited to any one energy level in the conduction band, and light corresponding to the h-line is emitted from the conduction band based on the excited electrons. It is characterized by doing.

  Further, an exposure apparatus according to the present invention is an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate through a plurality of optical elements by light emitted from a light source in order to solve the above-described problem. In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band in the vicinity of 436 nm is disposed, and the material is the band gap wavelength of the light emitted from the light source. In response to the following light, electrons in the valence band are excited to any one energy level in the conduction band, and light corresponding to g-line is emitted from the conduction band based on the excited electrons. It is characterized by that.

  In order to solve the above-described problems, an exposure method according to the present invention is an exposure method in which a pattern image of a photomask is projected onto a photosensitive substrate through a plurality of optical elements with light emitted from a light source. In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between the conduction band and the valence band of around 365 nm is disposed, and the light emitted from the light source is not more than the band gap wavelength. Then, an electron in the valence band is excited to any one energy level in the conduction band, and light corresponding to i-line is emitted from the conduction band based on the excited electron. .

  Further, an exposure method according to the present invention is an exposure method in which a pattern image of a photomask is projected onto a photosensitive substrate through a plurality of optical elements by light emitted from a light source in order to solve the above-described problem. In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 405 nm is disposed, and light having a band gap wavelength equal to or smaller than the light emitted from the light source. In response, the electron in the valence band is excited to any one energy level in the conduction band, and light corresponding to the h-line is emitted from the conduction band based on the excited electron. And

  Furthermore, an exposure method according to the present invention is an exposure method in which a pattern image of a photomask is projected onto a photosensitive substrate via a plurality of optical elements with light emitted from a light source in order to solve the above-described problems. In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band near 436 nm is disposed, and light having a band gap wavelength equal to or smaller than the light emitted from the light source. In response, the electron in the valence band is excited to any one energy level in the conduction band, and light corresponding to g-line is emitted from the conduction band based on the excited electron. And

  In the present invention, a material having a predetermined band gap wavelength between the conduction band and the valence band is disposed in a path from the light source to the photosensitive substrate, and light having a band gap wavelength or less is emitted from the light source. In response, electrons in the valence band are excited to any one energy level in the conduction band, and light having a band gap wavelength is emitted from the conduction band based on the excited electrons.

  As a result, it is possible to effectively utilize the extra spectrum light that should normally be discarded, and to improve the light utilization efficiency of the entire lithography.

  Hereinafter, as the best mode for carrying out the present invention, an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate through a plurality of optical elements by light emitted from a light source will be described with reference to the drawings. While explaining in detail.

  As shown in FIG. 1, the exposure apparatus 1 to which the present invention is applied has a light source 11 for emitting light, an illumination optical system 12 for condensing the light emitted from the light source 11, and an integrated circuit pattern. The photomask 13 is provided. The exposure system 1 is provided with a substrate 21 made of, for example, a silicon oxide film and having a resist film 22 formed on the surface thereof. That is, a so-called photosensitive substrate is formed by the substrate 21 on which the resist film 22 is formed.

  The light source 11 is an Hg lamp that emits light having a wavelength profile as shown in FIG. 5 based on control by a driving power source (not shown). Incidentally, a cooling medium delivered from a cooling device (not shown) may be circulated around the light source 11.

  The illumination optical system 12 controls the beam diameter and beam shape with which the photomask 13 is irradiated. The illumination optical system 12 controls the incident angle of light with respect to the photomask 13 together with the light source 11.

  The photomask 13 is made of a glass plate made of quartz or the like in which a Cr thin film for shielding light is formed according to an integrated circuit pattern, and is irradiated with light whose beam diameter is controlled by the illumination optical system 12 described above. As a result, the pattern image formed on the photomask 13 is projected onto the resist film 22. Particularly when the nanodevice is finely processed, the resolution can be improved by using i-line on the resist film 22.

In the exposure apparatus 1, in order to easily perform mask alignment between the photomask 13 and the integrated circuit pattern in the previous process, a positioning mechanism using a high-precision stage or an interference system, an alignment mark reading optical system, etc. You may make it provide.
The resist film 22 is an organic photosensitive resin that causes a chemical reaction in response to light. The resist film 22 is a negative type that is polymerized and cross-linked in the region irradiated with light and becomes insoluble in the developer, or a positive type that decomposes in the region irradiated with light and becomes soluble in the developer. Any type of mold may be applied.

  Next, the detailed configuration of the photomask 13 will be described. A photomask 13 shown in FIG. 2A includes a glass plate 31, a zinc oxide layer 32 containing zinc oxide (ZnO) laminated on the glass plate 31, and Cr formed on the surface of the zinc oxide layer 32. A thin film 33. The light irradiated to the photomask 13 passes through the glass plate 31, passes through the zinc oxide layer 32, and the light irradiated to the region where the Cr thin film 33 is formed is shielded, and the Cr thin film 33 is formed. The light that has passed through the non-applied region illuminates the resist film 22 as it is. That is, the pattern can be transferred to the resist film 22 by irradiating the photomask 13 on which the integrated circuit pattern is drawn in advance with light as described above.

  The photomask 13 shown in FIG. 2 (b) has a glass plate 31 and a Cr thin film 33 formed on the surface of the glass plate 31, and in a region where the Cr thin film 33 is not formed, zinc oxide. The nanocrystallite 34 containing is formed. The light applied to the photomask 13 passes through the glass plate 31, the light applied to the region where the Cr thin film 33 is formed is shielded, and the light transmitted through the region where the Cr thin film 33 is not formed. Irradiates the resist film 22 as it is after passing through the nanocrystallites 34.

  That is, the light applied to the resist film 22 passes through the zinc oxide layer 32 or the nanocrystallite 34 containing zinc oxide.

  FIG. 3 shows an energy band diagram and an absorption spectrum of zinc oxide contained in the zinc oxide layer 32 and the nanocrystallite 34.

  The zinc oxide layer 32 or the nanocrystallite 34 is absorbed at a wavelength shorter than the emission wavelength. When such light enters, electrons in the valence band 41 in zinc oxide are excited to the conduction band 42.

The electrons excited in the conduction band 42 are finally recombined with holes in the valence band, and light is emitted at that time. The wavelength of the emitted light corresponds to the band gap wavelength between the valence band 41 and the conduction band 42 (energy level 42), and this example (Mg _x Zn _1-x O: x In the case of = 0), the wavelength is in the vicinity of 365 nm and becomes the wavelength of i-line.

  Thus, since the band gap wavelength between the conduction band 41 and the valence band 42 in zinc oxide is near 365 nm, when light having a shorter wavelength than this is incident, it is more energetically than the energy level 42. Electrons are excited once to the upper level (sideband, etc.). When this excited electron falls to the energy level 42, i-line light can be emitted based on this.

  Incidentally, in the above-described example, the case where the exciton is excited once in the side band existing in the energy level in the valence band 42 is described as an example, but other band gaps of 365 nm or less are described. Based on the same mechanism for energy levels having wavelengths, it is possible to excite electrons to the sideband and emit light having an i-line wavelength.

  That is, not only when light having a wavelength of 365 nm is incident, but also when light having a wavelength shorter than 365 nm is incident, this is excited once to the level of the sideband higher than the energy level 42, and the energy By dropping into the level 42, light having a wavelength of 365 nm can be emitted. This means that zinc oxide converted light having a wavelength shorter than 365 nm into light having a wavelength of 365 nm.

  As a result, the light having a wavelength of 365 nm or less has its extra spectrum removed as shown in FIG. 4A, and the added amount is added to the light having a wavelength of 365 nm. That is, the integral intensity of an extra spectrum that is shorter than the wavelength of 365 nm is added to the light of the i-line wavelength. As a result, it is possible to effectively utilize extra spectrum light that should normally be discarded as i-line light.

  In other words, in the present invention, it is possible to improve the light utilization efficiency of the entire lithography by efficiently utilizing an extra spectrum generated at a wavelength shorter than that of the i-line without throwing it away.

In the above description, the case where the zinc oxide layer 32 containing zinc oxide or the nanocrystallite 34 is used has been described as an example. However, the present invention is not limited to this case. As an alternative to this zinc oxide, Al _x Ga _1-x N, In _x Ga _1-x N (0 ≦ x ≦ 1) may be used. By changing the element ratio of Al and Ga or the element ratio of In and Ga, the band gap wavelength between the conduction band 41 and the valence band 42 can be freely controlled from around 200 nm to 365 nm. . As a result, the wavelength of emitted light can be adjusted to an arbitrary wavelength of light without being limited to 365 nm as i-line. For example, the light corresponding to the h-line may be emitted from the valence band by setting the band gap wavelength between the conduction band and the valence band to around 405 nm. Further, the light corresponding to the h-line may be emitted from the valence band by setting the band gap wavelength between the conduction band and the valence band in the vicinity of 436 nm. Furthermore, diamond may be applied as an alternative to these.

  When the bandgap wavelength is adjusted to λa in this way, light having a shorter wavelength can be absorbed, and the absorbed light can be emitted at the bandgap wavelength λa, greatly increasing the transmission efficiency. Can be increased.

  In the present invention, the case where a material containing zinc oxide is formed on the photomask 13 has been described as an example. However, the present invention is not limited to this case. For example, a material containing zinc oxide may be disposed in the path from the light source 11 to the substrate 21. For example, the lens in the illumination optical system 12 may be coated with a material containing zinc oxide. Moreover, you may make it produce the Hg lamp itself as the light source 11 with this zinc oxide.

  The light source 11 is not limited to the Hg lamp, and a xenon lamp may be used, or an LED or the like may be applied.

It is a block diagram of the exposure apparatus to which this invention is applied. It is a figure which shows the detailed structure of the photomask in the exposure apparatus to which this invention is applied. The energy band figure of the zinc oxide contained in a zinc oxide layer and a nano crystallite is shown. It is a figure for demonstrating the effect of the exposure apparatus to which this invention is applied. It is a figure which shows the spectrum analysis result of the light radiate | emitted from the Hg lamp as a light source.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exposure apparatus 11 Light source 12 Illumination optical system 13 Photomask 21 Substrate 22 Resist film 31 Glass plate 32 Zinc oxide layer 33 Cr thin film 34 Nanocrystal

Claims (12)

A band gap wavelength between a conduction band and a valence band is made of a material in the vicinity of 365 nm, and receives light having a band gap wavelength equal to or less than the band gap wavelength out of light emitted from a light source, and converts electrons in the valence band to the conduction band. A photomask, wherein the photomask is excited to any one of the energy levels in the above, and light corresponding to i-line is emitted from the conduction band based on the excited electrons. A band gap wavelength between the conduction band and the valence band is made of a material in the vicinity of 405 nm, receives light having a band gap wavelength shorter than the light emitted from the light source, and converts electrons in the valence band to the conduction band. A photomask, wherein the photomask is excited to any one of the energy levels, and light corresponding to h-rays is emitted from the conduction band based on the excited electrons. A band gap wavelength between the conduction band and the valence band is made of a material in the vicinity of 436 nm, and receives light of the band gap wavelength or less out of the light emitted from the light source, and converts the electrons in the valence band to the conduction band. A photomask, wherein the photomask is excited to any one of the energy levels and light corresponding to g-line is emitted from the conduction band based on the excited electrons. The material is any one of Al _x Ga _1-x N, Mg _x Zn _1-x O, In _x Ga _1-x N (0 ≦ x ≦ 1), and diamond. The photomask according to any one of 3. In an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate via a plurality of optical elements by light emitted from a light source,
In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 365 nm is disposed,
The material receives light of the band gap wavelength or less out of the light emitted from the light source, and excites electrons in the valence band to any one energy level in the conduction band. An exposure apparatus that emits light corresponding to i-line from the conduction band based on electrons. In an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate via a plurality of optical elements by light emitted from a light source,
In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 405 nm is disposed,
The material receives light of the band gap wavelength or less out of the light emitted from the light source, and excites electrons in the valence band to any one energy level in the conduction band. An exposure apparatus that emits light corresponding to h rays from the conduction band based on electrons. In an exposure apparatus that projects a pattern image of a photomask onto a photosensitive substrate via a plurality of optical elements by light emitted from a light source,
In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 436 nm is disposed,
The material receives light of the band gap wavelength or less out of the light emitted from the light source, and excites electrons in the valence band to any one energy level in the conduction band. An exposure apparatus that emits light corresponding to g-rays from the conduction band based on electrons. 6. The material according to claim 5, wherein the material is any one of Al _x Ga _1-x N, Mg _x Zn _1-x O, In _x Ga _1-x N (0 ≦ x ≦ 1), and diamond. The exposure apparatus according to any one of 7. In an exposure method for projecting a pattern image of a photomask onto a photosensitive substrate via a plurality of optical elements by light emitted from a light source,
In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 365 nm is disposed.
Based on the excited electrons, the electrons in the valence band are excited to any one energy level in the conduction band by receiving light of the band gap wavelength or less out of the light emitted from the light source. An exposure method characterized by emitting light corresponding to i-line from the conduction band. In an exposure method for projecting a pattern image of a photomask onto a photosensitive substrate via a plurality of optical elements by light emitted from a light source,
In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 405 nm is disposed,
Based on the excited electrons, the electrons in the valence band are excited to any one energy level in the conduction band by receiving light of the band gap wavelength or less out of the light emitted from the light source. An exposure method characterized by emitting light corresponding to h rays from the conduction band. In an exposure method for projecting a pattern image of a photomask onto a photosensitive substrate via a plurality of optical elements by light emitted from a light source,
In the path from the light source to the photosensitive substrate, a material having a band gap wavelength between a conduction band and a valence band of around 436 nm is disposed,
Based on the excited electrons, the electrons in the valence band are excited to any one energy level in the conduction band by receiving light of the band gap wavelength or less out of the light emitted from the light source. An exposure method characterized by emitting light corresponding to g-line from the conduction band. The material is any one of Al _x Ga _1-x N, Mg _x Zn _1-x O, In _x Ga _1-x N (0 ≦ x ≦ 1), and diamond. The exposure method according to any one of 11.

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