JPH06258817A - Phase shift mask and blank to be used for the same and their production - Google Patents

Abstract

PURPOSE:To provide the phase shift mask which has high reliability as the phase shift mask for an exposure device using i rays and KrF excimer laser as light sources at the time of using the phase shift mask using a silicon oxide film as a phase shift layer and enables the effective utilization of energy for exposure and the blank to be used for this mask and process for production of such mask and blank. CONSTITUTION:A phase shift film has at least a transparent substrate 1 and the phase shift layer 3 consisting of oxide of silicon. The phase shift layer 3 of this phase shift mask is subjected to a heat treatment under a reduced pressure, more preferably under the reduced pressure and in an inert gaseous atmosphere after formation of the phase shift layer 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, LSIs and VLSs.
When a very fine pattern represented by a semiconductor integrated circuit such as I is formed by applying photofabrication, a so-called photomask used as an original image loaded in a projection exposure apparatus and a blank used for manufacturing the same The present invention also relates to a manufacturing method thereof, and particularly to a method to which a so-called phase shift technique is applied.

[0002]

2. Description of the Related Art A conventional photomask merely has a pattern consisting of a light transmitting portion and a light shielding portion for the projection exposure light. However, there has been a problem that light leaking from the transparent portion of the mask interferes with each other, resulting in poor resolution. Therefore, a phase shift mask using a phase shift technique for reversing the phase of projection exposure light passing through an adjacent pattern by 180 degrees and improving the resolution of a fine pattern has been developed and attracted attention. That is, in the phase shift mask, by providing the phase shift portion on one side of the adjacent openings, when the transmitted lights are diffracted and interfere with each other, the light intensities at the boundaries are weakened against each other because the phases are inverted. ,
The intensity becomes zero, and as a result, the transfer pattern is separated and resolved. Since this relationship holds even before and after the focus position, the resolution is improved and the margin of the depth of focus is improved as compared with the conventional method even if the focus is slightly deviated.

As a conventional phase shift mask, it is known that an etching stopper layer, a phase shift layer and a light shielding layer are provided on a transparent glass substrate. The etching stopper layer is made of alumina, tin oxide or the like. Materials such as silicon oxide and the like have been used for the phase shift layer and chromium and the like for the light shielding layer. On the other hand, as a light source of an exposure apparatus (stepper) for performing reduction projection exposure on a silicon wafer or the like using such a phase shift mask, conventionally, g
Line (wavelength 436 nm) and i-line (wavelength 365 nm) have been used, but with the recent remarkable increase in density of semiconductor elements, further miniaturization of patterns is required, and exposure apparatus The light source of the KrF excimer laser (wavelength 248n is shorter than the conventional light source).
The use of m) has been considered.

By the way, the phase shift layer of the conventional phase shift mask has been produced by simply forming a silicon oxide film by using a sputtering method. However, this silicon oxide film emitted luminescence having a peak near a wavelength of 650 nm when irradiated with the KrF excimer laser.

Theoretically, this means that when the silicon oxide film is irradiated with light to generate luminescence, the energy of light is absorbed because the silicon oxide film itself has structural defects. Then, the electrons are excited from the valence band to the conduction band through the forbidden band, and then spontaneously emit luminescence to fall to the valence band. Such light energy will be lost due to the generation of luminescence. By the way, the cause of the luminescence having a peak near a wavelength of 650 nm is as described in 1st Annual Meeting of the Institute of Electrical Engineers of Japan, S, 4-5 (Oki, Nagasawa).

≡Si-O

In the SiO ₂ structure defect, NBOHC
(Non Bridging Oxygen Hole
Center).

That is, the conventional phase shift mask having a mere silicon oxide film as the phase shift layer emits luminescence to the KrF excimer laser, but this is unavoidable, and as a result, the projection exposure light is emitted. The energy is lost and the energy that should contribute to the exposure is reduced. Therefore, the conventional phase shift mask has a problem that the original exposure performance as a phase shift mask cannot be exhibited for a stepper using a KrF excimer laser as a light source for projection exposure.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above conventional problems, and an object thereof is to use a phase shift mask having a silicon oxide film as a phase shift layer for photofabrication. When doing i
It is possible to obtain a highly reliable phase shift mask for an exposure apparatus such as a stepper using a line as a light source and a blank thereof, and even when the projection exposure light source is a KrF excimer laser, the exposure energy is effectively used. What is needed is to provide a phase shift mask satisfying the above, a blank used therefor, and a manufacturing method thereof.

[0010]

[Means for Solving the Problems] Means provided by the present invention for solving the above-mentioned problems are as follows:
A phase shift mask comprising at least a phase shift layer made of silicon oxide, wherein the phase shift layer is heat-treated under reduced pressure after the formation of the phase shift layer. .

Preferably, the heat treatment is carried out under reduced pressure and in an inert gas atmosphere, and the phase shift mask is characterized in that.

Alternatively, in a blank used for a phase shift mask including at least a transparent substrate and a phase shift layer made of silicon oxide, the phase shift layer is heat-treated under reduced pressure after the formation of the phase shift layer. It is a blank used for a phase shift mask.

Preferably, the blank used for the phase shift mask is characterized in that the heat treatment is performed under reduced pressure and in an inert gas atmosphere.

Alternatively, in the method of manufacturing a phase shift mask, a phase shift layer made of at least a silicon oxide is provided on a transparent substrate, and the phase shift layer is patterned to form the phase shift layer. This is a method of manufacturing a phase shift mask, which is characterized by performing heating under reduced pressure later.

Preferably, the heat treatment is carried out under a reduced pressure and in an inert gas atmosphere, and the method for producing a phase shift mask described above is preferable.

In a method of manufacturing a blank used for a phase shift mask, a phase shift layer made of at least silicon oxide is provided on a transparent substrate, and the phase shift layer is patterned. After the layer is formed, heating is performed under reduced pressure, which is a method for manufacturing a blank used for a phase shift mask.

Further, preferably, the method for producing a blank used for the phase shift mask is characterized in that the heat treatment is performed under a reduced pressure and in an inert gas atmosphere.

Various layer structures are known as a so-called phase shift mask or a blank used therefor. However, as described above, the present invention is not limited as long as it has a phase shift layer made of silicon oxide. A preferable adaptation can be made with any layer structure.

That is, a phase shift mask having an etching stopper layer, a phase shift layer made of silicon oxide, and a light shielding layer in this order on a transparent substrate, or a blank used therefor is also an example. The step of patterning the phase shift layer and the light shielding layer made of silicon oxide may be before or after the step of heat treatment under reduced pressure (or at the same time in an inert gas atmosphere).

Alternatively, a phase shift mask having a patterned light-shielding layer and a phase shift layer made of silicon oxide in this order on a transparent substrate, or a blank used therefor is also a preferable example. Again, the step of patterning the phase shift layer made of silicon oxide may be before or after the step of heating under reduced pressure (or at the same time under an inert gas atmosphere).

Alternatively, a phase shift mask having an etching stopper layer and a phase shift layer made of silicon oxide in this order on a transparent substrate, or a blank used therefor is also a preferable example. The step of patterning the phase shift layer made of silicon oxide may be before or after the step of heat treatment under reduced pressure (or at the same time in an inert gas atmosphere).

A phase shift mask having a layer semitransparent to projection exposure light and a phase shift layer made of silicon oxide in this order on a transparent substrate, or a blank used therefor is also a preferred example. As a matter of course, the step of patterning the semitransparent layer or the phase shift layer may be before or after the step of heat treatment under reduced pressure (or at the same time in an inert gas atmosphere).

A preferred example is a phase shift mask having an etching stopper layer, a phase shift layer made of silicon oxide, and a layer semitransparent to projection exposure light in this order on a transparent substrate, or a blank used for the phase shift mask. After all, the step of patterning the phase shift layer or the semitransparent layer may be before or after the step of heat treatment under reduced pressure (or at the same time in an inert gas atmosphere).

The present invention will be described in more detail below with reference to the drawings and supplements.

FIG. 1 shows an embodiment of the present invention by using a sectional view. This structure has a transparent substrate 1.
An etching stopper layer 2 and a phase shift layer 3 are formed in this order on top of this, and then heat treatment for reducing luminescence is performed, and then a light shielding layer 4 is formed. The phase shift layer 3 and the light shielding layer 4 are selectively removed and formed in a predetermined pattern. here,
The heat treatment shown in FIG. 1D is performed after forming the light shielding pattern 4 ′ after forming the light shielding layer 4 or after forming the light shielding layer 4 and the light shielding pattern 4 ′ and the phase shift pattern 3 ′.
It may be performed any time after the formation of.

FIG. 2 is a sectional view showing another embodiment of the present invention. This configuration
On the transparent substrate 1, a pattern in which the light-shielding layer 4 is selectively removed, that is, a light-shielding pattern 4 ′ is formed, and then the phase shift layer 3 is formed, and thereafter, heat treatment for reducing luminescence is performed, and thereafter The phase shift pattern 3'is formed. The heat treatment shown in FIG. 2E may be performed after forming the phase shift layer 3 and forming the phase shift pattern 3 ′.

FIG. 3 shows another embodiment according to the present invention by using a sectional view. A blank for use as a phase shift mask, in which an etching stopper layer 2 and a phase shift layer 3 are sequentially formed on a transparent substrate 1 and then heat treatment for reducing luminescence is performed, and then a light shielding layer 4 is formed. Are manufactured.

FIG. 4 is a sectional view showing the structure of an embodiment of the phase shift mask of the present invention and its manufacturing method.
As is clear from (FIG. 4), in the structure of this embodiment, the etching stopper layer 2 and the phase shift layer 3 are sequentially formed on the transparent substrate 1, and then heat treatment for reducing luminescence is performed. . Then, the phase shift layer 3 is partially removed and formed into a predetermined pattern. Here (Fig. 4
The heat treatment shown in (d) may be performed after the phase shift pattern 3'is formed.

FIG. 5 is a sectional view showing the construction of another embodiment of the phase shift mask and the manufacturing method thereof according to the present invention.
In the structure of this embodiment, a layer 6 that is semi-transparent to the projection exposure light is formed on the transparent substrate 1, the phase shift layer 3 is formed, and then heat treatment for reducing luminescence is performed, and then the phase shift pattern is formed. 3'and a layer 6'semi-transparent to the patterned projection exposure light.
Here, the heat treatment shown in FIG. 5D is performed after forming the phase shift pattern 3 ′ after forming the phase shift layer 3 or after forming the phase shift layer 3 and forming the phase shift pattern 3 ′ and the patterned projection. It may be performed after forming the layer 6 ′ that is semitransparent to the exposure light.

FIG. 6 is a cross-sectional view showing the structure of another embodiment of the method for manufacturing a phase shift mask of the present invention. An etching stopper layer 2 and a phase shift layer 3 are formed on a transparent substrate 1 in this order. After film formation and heat treatment for reducing luminescence, a layer 6 that is semitransparent to projection exposure light is formed,
The layer 6'is semi-transparent to the patterned projection exposure light and the phase shift pattern 3'is formed.

FIG. 7 is a sectional view showing the structure of an embodiment of the method of manufacturing a phase shift mask blank of the present invention. An etching stopper layer 2 and a phase shift layer 3 are formed in this order on a transparent substrate 1. The film is formed, and then heat treatment for reducing luminescence is performed.

FIG. 8 is a sectional view showing the construction of another embodiment of the method of manufacturing a phase shift mask blank according to the present invention. The construction of this embodiment is such that the projection exposure light on the transparent substrate 1 is exposed. The semitransparent layer 6 is formed, and after the phase shift layer 3 is formed, heat treatment for reducing luminescence is performed.

FIG. 9 is a cross-sectional view showing the structure of another embodiment of the method of manufacturing a phase shift mask blank of the present invention. An etching stopper layer 2 and a phase shift layer 3 are formed on a transparent substrate 1. The film formation is performed in order, a heat treatment for reducing luminescence is performed, and then the layer 6 that is semitransparent to the projection exposure light is formed.

The layer 6 semitransparent to the projection exposure light is mainly composed of a metal compound containing chromium, silicon nitride or the like (this is also common to those skilled in the art). In addition, the wavelength of the KrF excimer laser that is the projection exposure light is 248 nm.
And the transmissivity of the semitransparent layer 6 at the i-line wavelength of 365 nm, the transmissivity of the projection exposure light in the transparent region is 1
The transmittance of the semi-transparent layer 6 is 1 to 5 when it is set to 00%.
It is in the range of 0%.

Under the above conditions, at least one layer 6 is semitransparent to the projection exposure light in the phase shift mask,
Furthermore, a composite layer structure including a transparent layer may be used. And this layer as a whole is semi-transparent, and its film thickness is The requirement is to meet.

Here, d _k and n _k are the thickness and the refractive index of the k-th film forming the layer 6 which is translucent to the projection exposure light. Further, m is the number of films forming the layer 6 that is semitransparent to the projection exposure light, and λ is the wavelength (nm) of the projection exposure light. And regarding φ, 3/4 ≧ φ ≧
It is 1/4. In particular, for the projection exposure light that passes through,
It suffices that the above-mentioned phase difference is relatively generated with respect to the transparent region. Further, the layer 6 which is semi-transparent to the projection exposure light passing therethrough,
It is preferable that patterning is easy.

Here, the material of the transparent substrate 1 may be arbitrarily selected as long as it has optical transparency and rigidity as a support and has a low coefficient of thermal expansion. For example, quartz glass, Quartz and the like are commonly used. A thickness of about 0.09 inch (about 2.3 mm) to 0.25 inch (about 6.35 mm) is widely used among those skilled in the art, but this thickness is of course the present invention.
Thicknesses other than these can be preferably applied.

The etching stopper layer 2 has a role of preventing the underlying transparent substrate 1 from being etched when the phase shift layer 3 is etched.
There is no reason to strictly limit the thickness, and the thickness is not particularly limited in view of the configuration of the present invention. However, if it is too thin, it becomes difficult to prevent the progress of etching to the transparent substrate 1 as the base, but at the same time,
There is a circumstance that the thinner the film thickness is, the shorter the film formation time is, and the higher the obtained transparency is (the thicker the transparency is, the lower the transparency is). Therefore, generally, a thickness of about 50 to 200 nm is desirable.

As the phase shift layer 3, a transparent material or the like which is usually made of silicon oxide is used. As described above, the phase shift layer 3 is for inverting the phase of the transmitted projection exposure light by 180 degrees. For that purpose, the thickness of the phase shift layer 3 is set so that the transmitted light has a phase difference of 180 degrees. Must be set to

The condition at this time is given by the following equation, that is, d = λ / {2 (n-1)}. Here, n is the refractive index of the phase shift layer 3, λ is the wavelength (nm) of the projection exposure light source, and d is the film thickness (nm) of the phase shift layer 3. For example, when n is 1.47 (material: SiO ₂ ) and λ is 248 nm (wavelength of KrF excimer laser), the thickness of the phase shift layer is about 250.
Given as nm.

The light-shielding layer 4 is generally made of a metal compound mainly containing chromium, silicon or the like as in the known technique, and has a wavelength of 248 nm of a KrF excimer laser.
It is necessary that a sufficient light-shielding property can be obtained with respect to the wavelength of 365 nm for the i-line and that patterning can be performed. Further, it is preferable that patterning is as easy as possible. Further, a layer for preventing reflection may be provided above, below, or above and below the light-shielding layer 4, whereby more preferable photofabrication can be carried out, as in the known art.

As a method for forming the thin films of the etching stopper layer 2, the light shielding layer 4 and the antireflection layer 5 on the transparent substrate 1, a sputtering method, an ion plating method, a vacuum evaporation method, or a CVD method is used. Conventionally known techniques such as the above can be appropriately adopted.

Then, the phase shift layer 3 is formed by the sputtering method. More specifically, by mixing oxygen gas or oxygen gas and argon gas,
Si or SiO ₂ is used as a target, and plasma is generated in the sputtering chamber to form a film.

The heat treatment after forming the phase shift layer is performed in a chamber capable of reducing the pressure. At this time, in order to further enhance the effect of the present invention, it is preferable to introduce a chemically inert gas, and therefore a chamber capable of introducing the chemically inert gas is desirable. Examples of the chemically inert gas include argon gas, helium gas and krypton gas.

The degree of vacuum in the chamber is preferably as high as possible so that a residual gas such as chemically active oxygen does not react with the phase shift layer. Also, when introducing the chemically inert gas, it is desirable to set the inside of the chamber to a sufficiently high vacuum in advance before introducing it for the same reason. Preferably, the degree of vacuum is about a back pressure at the time of performing an exhaust operation when forming the phase shift layer.

The heat treatment according to the present invention is carried out for the purpose of releasing excess oxygen in the phase shift layer from the phase shift layer into the chamber, and the heat treatment deteriorates the flatness of the substrate. It is sufficient that the temperature is not so high that the light-shielding film deteriorates. A more preferable temperature range is approximately 200 to 400 ° C.

The method of forming the phase shift pattern 3'and the light-shielding pattern 4'is also not particularly limited, and the resist pattern is formed by electron beam drawing and development, and then wet etching or dry etching is performed. You can achieve it, but there are no problems other than this. Well-known photolithography methods can of course be adopted arbitrarily.

[0048]

The present invention is based on the results of the inventors' earnest researches based on experiments, and heat treatment under reduced pressure (or at the same time in an inert gas atmosphere) after forming the phase shift layer. It has been confirmed that luminescence having a peak at a wavelength of 650 nm does not occur even when irradiated with a KrF excimer laser.

The precise and detailed cause and mechanism of this are
It is not known so far, but it is speculated as follows. That is, this means that the structural defects existing in the phase shift layer are eliminated by performing the treatment according to the present invention. After all, according to the present invention, the energy for the exposure of the KrF excimer laser can suppress (or reduce) the generation of luminescence, so that the energy for the exposure that has been wasted is effectively used. It will be possible.

[0050]

Example 1 An alumina film having a thickness of about 20 nm is formed as an etching stopper layer 2 on a cleaned 6-inch square and 0.25-inch thick photomask quartz substrate 1 by RF magnetron sputtering method. Filmed (See Figure 1)

Next, by using the RF magnetron sputtering method, a film was formed under the target of SiO ₂ , the flow rate ratio of argon and oxygen was 30/70, and the power was 100 W. As the phase shift layer 3, a silicon oxide film of about 250 is used.
The film was formed to a thickness of nm. Back pressure during film formation is approximately 2.0 x 10
^-4 Pa, and the sputtering pressure is about 2.0 × 10 ^-1 P
It was a.

Thereafter, as shown in FIG. 12, a KrF excimer laser is applied to the silicon oxide film portion of the substrate by 80
When irradiated at about 30 mJ / cm ² at 30 Hz (Fig. 1
As shown in 0), luminescence having a peak at a wavelength of 650 nm was observed.

Next, the substrate is placed in a vacuum chamber 5 and the inside is evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa. Then, a chemically inert argon gas is introduced into the chamber for about 20 SC.
Heating was performed at 300 ° C. for 1 hour while flowing CM. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After that, the substrate was taken out of the chamber and irradiated again with a KrF excimer laser at 80 Hz and about 30 mJ / cm ² as shown in (FIG. 12).
As shown in (FIG. 11), the luminescence having a peak at a wavelength of 650 nm disappeared almost completely, and no new luminescence having a peak at another wavelength occurred.

After that, a chromium film as a light-shielding film 4 is formed on the phase shifter layer 3 by DC sputtering to a thickness of about 100 n.
m film formation, light shielding pattern 4 ', phase shift pattern 3'
Was formed (FIG. 1 (e)) to complete a phase shift mask in which luminescence did not occur.

<Embodiment 2> Washed 6 inch square, 0.
A chrome film as a light shielding layer 4 of about 100 nm is formed on a 25-inch thick quartz substrate 1 for photomask by a DC sputtering method.
After forming a film, a light-shielding pattern 4 ′ was formed. (See Figure 2)

Then, a silicon oxide film as the phase shift layer 3 was formed to a thickness of about 250 nm by the same process as described above.

Thereafter, as shown in (FIG. 12), a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm was observed, similar to that shown in (FIG. 10).

Next, this film was placed in a vacuum chamber 5, the inside of the chamber was evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa, and then a chemically inert argon gas was introduced into the chamber for about 20 SC.
It was heated at 300 ° C. for about 1 hour while flowing CM.
The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
Similar to that shown in (FIG. 11), the luminescence having a peak at a wavelength of 650 nm disappeared almost completely, and no new luminescence having a peak at another wavelength occurred.

After this, a phase shift pattern 3'is formed to complete a phase shift mask as shown in FIG. 2 (f) in which luminescence does not occur.

<Embodiment 3> Washed 6 inch square, 0.
An etching stopper layer 2 is formed on a quartz substrate 1 for a photomask having a thickness of 25 inches by RF magnetron sputtering.
As an alumina film, a film having a thickness of about 20 nm was formed. (See Figure 3)

Then, a silicon oxide film was formed as the phase shift layer 3 to a thickness of about 250 nm by the same process as described above.

Thereafter, as shown in (FIG. 12), a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm was observed, similar to that shown in (FIG. 10).

Next, this film is put in a vacuum chamber 5 to make the inside of the chamber have a vacuum degree of about 2.0 × 10 ^-4 Pa, and then a chemically inert argon gas is put into the chamber for about 20 SCC.
Heating was performed at 300 ° C. for about 1 hour while flowing M. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
As shown in (FIG. 11), the luminescence having a peak at a wavelength of 650 nm disappeared almost completely, and no new luminescence having a peak at another wavelength occurred.

Thereafter, a chromium film was formed as a light-shielding film 4 on the phase shift layer 3 by DC sputtering to a thickness of about 100 nm to complete a phase shift mask blank without luminescence. (Fig. 3 (e))

<Embodiment 4> A washed 6 inch square having a size of 0.
An alumina film as an etching stopper layer 2 having a thickness of about 20 nm was formed on a 25-inch thick quartz substrate 1 for a photomask by a conventionally used method. (See Figure 4)

Then, a silicon oxide film was formed as the phase shift layer 3 to a thickness of about 250 nm by the same process as described above.

Thereafter, as shown in (FIG. 12), a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 10) was observed.

Next, this film is placed in a vacuum chamber 5 and the inside of the chamber is evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa. Then, a chemically inert argon gas is introduced into the chamber for about 20 SC.
It was heated at 300 ° C. for about 1 hour while flowing CM.
The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
The luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 11) disappeared almost completely, and no luminescence having a peak at another wavelength was newly generated.

After that, the phase shift pattern 3'is formed by a usual method, and the luminescence-free phase shift mask as shown in FIG. 4 (e) is completed.

<Embodiment 5> Washed 6 inch square, 0.
On the 25-inch-thick quartz substrate 1 for photomask, a chromium film of about 35 nm was formed as a semitransparent layer 6 for the projection exposure light by a conventionally used method. (See Figure 5)

Then, a silicon oxide film was formed to a thickness of about 250 nm as the phase shift layer 3 by the same process as described above.

Thereafter, as shown in (FIG. 12), a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 10) was also observed.

Next, this substrate is put into a vacuum chamber 5 and the inside of the chamber is evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa. Then, a chemically inert argon gas is introduced into the chamber for about 20 S.
The mixture was heated at 300 ° C. for about 1 hour while flowing CCM. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
The luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 11) disappeared almost completely, and no luminescence having a peak at another wavelength was newly generated.

Thereafter, a chromium film is formed in a thickness of about 35 nm as a layer 6 semitransparent to the projection exposure light by a conventional method, and the layer 6'semitransparent to the patterned projection exposure light is formed. To form a phase shift mask in which luminescence does not occur as shown in FIG. 5 (e).

<Embodiment 6> Again, an alumina film having a thickness of about 20 nm is formed as an etching stopper layer 2 on a cleaned 6 inch square, 0.25 inch thick quartz substrate 1 for a photomask by a conventionally used method. Filmed (See Figure 6)

Then, the same treatment as described above was performed to form a silicon oxide film as the phase shift layer 3 with a thickness of about 250 nm.

Thereafter, as shown in FIG. 12, a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 10) was also observed.

Next, this substrate is placed in a vacuum chamber 5 and the inside of the chamber is evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa. Then, a chemically inert argon gas is introduced into the chamber for about 20 S.
The mixture was heated at 300 ° C. for about 1 hour while flowing CCM. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
The luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 11) disappeared almost completely, and no luminescence having a peak at another wavelength was newly generated.

After that, a chromium film is formed in a thickness of about 35 nm as a layer 6 semitransparent to the projection exposure light by the usual method, and the layer 6'semitransparent to the projection exposure light patterned by the usual method is used. Form shift pattern 3 '(FIG. 6 (f))
A phase shift mask that does not generate luminescence as shown in (3) was completed.

<Embodiment 7> Again, an alumina film having a thickness of about 20 nm is formed as an etching stopper layer 2 on a cleaned 6 inch square, 0.25 inch thick quartz substrate 1 for a photomask by a conventionally used method. Filmed (See Figure 7)

Next, the same process as described above was performed to form a silicon oxide film as the phase shift layer 3 with a thickness of about 250 nm.

Thereafter, as shown in (FIG. 12), a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 10) was also observed.

Next, this substrate was placed in a vacuum chamber 5, the inside of the chamber was evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa, and then a chemically inert argon gas was introduced into the chamber for about 20 S.
The mixture was heated at 300 ° C. for about 1 hour while flowing CCM. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out from the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
The luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 11) disappeared almost completely, and no luminescence having a peak at another wavelength was newly generated. As a result, a phase shift mask blank in which luminescence does not occur, as shown in FIG. 7E, is completed.

<Embodiment 8> Again, a semi-transparent layer 6 for projection exposure light is formed on a cleaned 6-inch square, 0.25-inch thick quartz substrate 1 for photomask by a conventionally used method. A chromium film was formed to a thickness of about 35 nm.

Then, the same treatment as described above was performed to form a silicon oxide film as the phase shift layer 3 with a thickness of about 250 nm.

Thereafter, as shown in FIG. 12, a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 10) was also observed.

Next, this substrate is put into a vacuum chamber 5 and the inside of the chamber is evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa. Then, a chemically inert argon gas is introduced into the chamber for about 20 S.
The mixture was heated at 300 ° C. for about 1 hour while flowing CCM. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
The luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 11) disappeared almost completely, and no luminescence having a peak at another wavelength was newly generated. As a result, a phase shift mask blank in which luminescence does not occur as shown in (FIG. 8E) is completed.

<Embodiment 9> Again, an alumina film having a thickness of about 20 nm was formed as an etching stopper layer 2 on a cleaned 6 inch square, 0.25 inch thick quartz substrate 1 for a photomask by a conventional method. Filmed

Then, the same treatment as described above was performed to form a silicon oxide film as the phase shift layer 3 with a thickness of about 250 nm.

Thereafter, as shown in FIG. 12, a KrF excimer laser was applied to this film at 80 Hz and about 30 mJ / c.
Upon irradiation with m ² , luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 10) was also observed.

Next, this substrate was put into a vacuum chamber 5, the inside of the chamber was evacuated to a vacuum degree of about 2.0 × 10 ^-4 Pa, and then a chemically inert argon gas was introduced into the chamber for about 20 S.
The mixture was heated at 300 ° C. for about 1 hour while flowing CCM. The degree of vacuum at this time was about 2.0 × 10 ⁻¹ Pa.

After this, the film was taken out of the chamber,
As shown in FIG. 12 again, when the KrF excimer laser was irradiated at 80 Hz and about 30 mJ / cm ² ,
The luminescence having a peak at a wavelength of 650 nm similar to that shown in (FIG. 11) disappeared almost completely, and no luminescence having a peak at another wavelength was newly generated.

After that, a chromium film of about 35 nm is formed as a layer 6 semitransparent to the projection exposure light by a usual method, and a luminescence-free phase shift mask blank as shown in FIG. 6 (e) is produced. Was completed.

[0102]

As described above in detail, according to the prior art, the KrF excimer laser having a wavelength of 248 nm is applied to the phase shift layer formed of only the silicon oxide film on the substrate. Caused luminescence having a peak near a wavelength of 650 nm. That is, the exposure energy of the KrF excimer laser is not entirely consumed for the exposure, and a loss occurs as the luminescence occurs.

However, according to the phase shift mask of the present invention, the blank used therefor, and the manufacturing method thereof, the luminescence is not generated, and therefore the light energy required for exposure is consumed for the generation of luminescence. It has become possible to control the loss caused by things.

Therefore, K, which is a short-wavelength projection exposure light source, is used.
As a phase shift mask compatible with an exposure device using an rF excimer laser, it has become possible to exhibit the original exposure performance when used in photofabrication. Furthermore, since a phase shift layer having no structural defects can be formed, it is possible to manufacture a highly reliable phase shift mask for an exposure apparatus such as a stepper using i-line as a light source and a blank thereof. It was

[Brief description of drawings]

FIG. 1 is an explanatory view showing an outline of steps in order with reference to cross-sectional views regarding one embodiment of a phase shift mask and a manufacturing method thereof according to the present invention.

2A to 2C are explanatory views sequentially showing the outline of steps in another embodiment relating to the phase shift mask and the manufacturing method thereof according to the present invention, using sectional views.

3A to 3D are explanatory views sequentially showing the outline of steps of a blank used for a phase shift mask of the present invention and an embodiment of a method for manufacturing the blank, using sectional views.

4A to 4C are explanatory views sequentially showing the outline of steps of another embodiment of the phase shift mask and the manufacturing method thereof according to the present invention, using sectional views.

5A to 5C are explanatory views sequentially showing the outline of steps in still another example related to the phase shift mask and the manufacturing method thereof according to the present invention, using sectional views.

6A to 6C are explanatory views sequentially showing the outline of steps in another example related to the phase shift mask and the manufacturing method thereof according to the present invention, using sectional views.

FIG. 7 is an explanatory view showing the outline of steps in order with reference to sectional views, with respect to another embodiment relating to the blank used for the phase shift mask of the present invention and the manufacturing method thereof.

FIG. 8 is an explanatory diagram sequentially showing the outline of the steps with respect to another embodiment relating to the blank used for the phase shift mask of the present invention and the manufacturing method thereof, using sectional views.

FIG. 9 shows another embodiment relating to a blank used for the phase shift mask of the present invention and a manufacturing method thereof.
It is explanatory drawing which shows the outline of a process in order using a sectional view.

FIG. 10 is a spectrum curve of luminescence generated when a phase shift mask according to a conventional technique is irradiated with a KrF excimer laser on the phase shift layer.

FIG. 11 is a diagram showing an embodiment of a phase shift mask and a method of manufacturing the same according to the present invention, in which the phase shift layer has Kr.
It is a spectroscopic curve of luminescence generated upon irradiation with an F excimer laser.

FIG. 12 is an explanatory view schematically showing an example of a method for measuring luminescence.

[Explanation of symbols]

1 ... Transparent substrate 2 ... Etching stopper layer 3 ... Phase shift layer 4 ... Light-shielding layer 5 ... Vacuum chamber 6 ... Layer semi-transparent to projection exposure light 3 '... Phase shift pattern 4 '... Shading pattern 6' ... Layer semi-transparent to projection exposure light (patterned)

Claims (8)

[Claims] 1. A phase shift mask comprising at least a transparent substrate and a phase shift layer made of silicon oxide, wherein the phase shift layer is heat-treated under reduced pressure after the formation of the phase shift layer. Phase shift mask. 2. The phase shift mask according to claim 1, wherein the heat treatment is performed under reduced pressure and in an inert gas atmosphere. 3. A blank for use in a phase shift mask comprising at least a transparent substrate and a phase shift layer made of silicon oxide, wherein the phase shift layer is heat-treated under reduced pressure after the formation of the phase shift layer. A blank used for a phase shift mask, which is characterized in that 4. The blank for use in a phase shift mask according to claim 3, wherein the heat treatment is performed under reduced pressure and in an inert gas atmosphere. 5. A method of manufacturing a phase shift mask, comprising: forming a phase shift layer made of at least silicon oxide on a transparent substrate; and patterning the phase shift layer. A method of manufacturing a phase shift mask, which is characterized by performing heating under reduced pressure later. 6. The method of manufacturing a phase shift mask according to claim 5, wherein the heat treatment is performed under reduced pressure and in an inert gas atmosphere. 7. A method for manufacturing a blank used for a phase shift mask, comprising providing a phase shift layer made of at least silicon oxide on a transparent substrate and patterning the phase shift layer. A method for manufacturing a blank used for a phase shift mask, which comprises heating under reduced pressure after forming the layer. 8. The method for manufacturing a blank used for a phase shift mask according to claim 7, wherein the heat treatment is performed under a reduced pressure and in an inert gas atmosphere.