JPH10198018A - Attenuation type phase shift mask and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the exposure of the circumference of a normal exposure region by providing attenuation type auxiliary phase shift patterns with patterns smaller than the resolution threshold of an exposure device and randomly arranging transmissive parts and phase shifter parts. SOLUTION: Attenuation type phase shift patterns consisting of square regions are formed in approximately the central part on a photomask substrate. The attenuation type auxiliary phase shift patterns are formed in the regions of the entire circumference at the peripheral edges of these attenuation type phase shift patterns. The transmissive parts 37 and the phase shifter parts 34 are randomly arranged in the attenuation type auxiliary phase shift patterns. Then, the images on the semiconductor wafer of the light transmitted through the attenuation type auxiliary phase shift pattern are smaller than the resolution threshold and are, therefore, not imaged. The light rays transmitted through the transmissive parts 37 and the phase shifter parts 34 overlap on each other and since the phases are inverted, these light rays interfere and negate each other, by which the light intensity on the semiconductor wafer may be weakened.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an attenuated phase shift mask and a method of manufacturing the same, and more particularly, to a pattern formed on the attenuated phase shift mask.

[0002]

2. Description of the Related Art In recent years, high integration and miniaturization of semiconductor integrated circuits have been remarkable. with this,
The miniaturization of circuit patterns formed on semiconductor substrates has also been rapidly progressing. Above all, the photolithography technology is widely recognized as a basic technology in pattern formation. Therefore, although various developments and improvements have been made to date, it is not known that pattern miniaturization has stopped, and the demand for improved pattern resolution has become stronger.

In general, a resolution limit R (nm) in a photolithography technique using a reduction exposure method is expressed as follows: R = K ₁ λ / (NA) (1) Here, λ is the wavelength of the light to be used (n
m), NA is the numerical aperture of the lens, and k ₁ is a constant depending on the resist process.

As can be seen from the above equation, in order to improve the resolution limit, the values of k ₁ and λ may be reduced and the value of NA may be increased. In other words, it is only necessary to reduce the constant depending on the resist process and to shorten the wavelength and increase the NA. However, it is technically difficult to improve the light source and the lens, and the depth of focus δ (δ = k ₂ · λ / (N
A) There is also a problem that ² ) becomes shallow and the resolution is rather lowered.

Referring to FIGS. 9 (a), 9 (b) and 9 (c), when a conventional photomask is used, the cross section of the mask, the electric field of the exposure light on the mask, and the exposure light on the wafer Will be described.

First, the structure of the cross section of the photomask will be described with reference to FIG. Quartz glass substrate 10
A metal mask pattern 20 made of chrome or the like is formed thereon. Next, referring to FIG. 9B, the electric field of the exposure light on the photomask is an electric field along the photomask pattern. However, regarding the light intensity of the exposure light on the wafer, especially when considering transfer of a fine pattern, as shown in FIG. 9C, the exposure light transmitted through the photomask causes the light diffraction phenomenon and the light diffraction phenomenon. Due to the light interference effect, adjacent pattern images in which light is superimposed strengthen each other. As a result, there is a problem that the difference in light intensity on the wafer is reduced, and the resolution is reduced.

To solve this problem, for example, Japanese Patent Laid-Open No.
7-62052 and JP-A-58-173744.
Discloses a phase shift exposure method using a phase shift mask. Next, FIGS. 10 (a), (b),
A phase shift exposure method using a phase shift mask disclosed in JP-A-58-173744 will be described with reference to FIG. FIG. 10A shows a cross section of the phase shift mask. FIG. 10B shows the electric field of the exposure light on the mask. FIG. 10C shows the light intensity of the exposure light on the wafer.

First, referring to FIG. 10A, this phase shift mask is formed at every opening of a chrome mask pattern 20 formed on a glass substrate 10 by a transparent insulating film such as a silicon oxide film. A phase shifter 60 is provided.

Next, referring to FIG. 10B, the electric field of the exposure light on the photomask by the light transmitted through the phase shift mask is alternately inverted by 180 °.
Therefore, adjacent pattern images where light overlaps due to the light interference effect cancel each other out. As a result, as shown in FIG. 10C, the difference between the light intensities of the exposure light on the wafer becomes sufficient, and the resolution of the pattern image can be improved.

However, the above phase shift mask is very effective for a periodic pattern such as line and space, but when the pattern is complicated, it is very difficult to arrange a phase shifter. Therefore, there is a problem that it cannot be set to an arbitrary pattern.

Therefore, as a phase shift mask which further solves the above problem, for example, “JJAP Seri”
es5 Proc. of 1991 Intern.
Micro Process Conference
pp. 3-9 and JP-A-4-136854 disclose an attenuated phase shift mask. Hereinafter, the attenuated phase shift mask disclosed in JP-A-4-136854 will be described.

FIG. 11A is a diagram showing a cross section of the attenuating type phase shift mask 500. As shown in FIG. FIG. 11 (b)
FIG. 3 is a diagram illustrating an electric field of exposure light on a mask. FIG. 11 (c)
FIG. 4 is a diagram showing the light intensity of exposure light on a wafer.

First, referring to FIG. 11A, the structure of a phase shift mask 500 is a quartz substrate 1 that transmits exposure light.
0, a transmission portion 100 formed on the main surface of the quartz substrate 10 and exposing the main surface of the quartz substrate 10, and a phase of the exposure light transmitted therethrough with respect to a phase of the exposure light transmitted through the transmission portion 100. Shift pattern 30 which is a predetermined exposure pattern including
0 is provided.

The phase shifter 200 described above has a phase difference between the chromium layer 20 in which the transmittance of the exposure light transmitted through the transmission part 100 is 2 to 20% and the exposure light transmitted through the transmission part 100. This is an absorption type shifter film having a dual structure with the shifter layer 30 having an angle of 180 °.

It should be noted that the transmittance of the above-described phase shifter section 200 with respect to exposure light is set to a value suitable for lithography.
The reason for setting it to 20% is to adjust the film thickness of the resist film after development according to the transmittance as shown in FIG.

The electric field on the mask of the exposure light transmitted through the phase shift mask having the above structure is as shown in FIG. Therefore, the light intensity of the exposure light on the wafer is as shown in FIG.
Since the phase is inverted at the edge of the exposure pattern as shown in FIG. 1C, the light intensity at the edge of the exposure pattern always becomes 0 as shown in the figure. As a result, the difference between the light intensities of the exposure light transmitted through the transmission portion 100 of the exposure pattern and the phase shifter 200 becomes sufficient, and the resolution of the pattern image can be increased.

However, in the above prior art,
It has the following problems.

FIG. 13A is a diagram showing a positional relationship between an attenuated phase shift mask in an exposure apparatus such as a reduced projection exposure type and a blind 70 for determining an exposure area of the exposure apparatus. FIG. 13B is a diagram illustrating an electric field of exposure light immediately below the attenuation type phase shift mask and the blind 70. FIG. 13C is a diagram showing the intensity of light transmitted through the attenuation type phase shift mask and the blind 70 on the material to be exposed. FIG. 13D is a diagram illustrating an exposure region of light transmitted through the attenuation type phase shift mask and the blind 70.

First, referring to FIG. 13A, the chip pattern forming region (L _c ) of the attenuated phase shift mask
The other area is covered with the absorption type shifter film 20 on which the pattern has not been processed. In the reduction projection type exposure apparatus, a blind 70 for blocking light for determining an exposure area is provided at a predetermined position below the attenuation type phase shift mask.

The width of the opening of this blind 70 is
Turn area (L_c) Only needs to be exposed.
Turn area (L_c). But bra
Position control of India 70 is about 1000 μm (about 1 mm
Degree), and the blind 70 is an attenuated phase shifter.
Blinds because they are not on the same focal plane as the mask
The edge portion 70 is in a state where the focus is shifted.
For this reason, as shown in FIG.
Opening width (L_b) Indicates the chip pattern area (L _c)
To prevent the blinds 70 from overlapping,
Turn area (L _c) About 1000μm wider than
There is a need to.

In the above state, in a normal photomask using a light-shielding film of chromium or the like for a chip pattern, light transmitted through chromium is 1 / 1,000 or less.
Light passing between the chip pattern region and the blind 70 does not expose the resist film on the semiconductor wafer.

However, in the case of an attenuated phase shift mask,
The transmittance of the absorption type shifter film as the chip pattern material is 2
Since it is about 20%, it is instructed to the part A in FIG.
Between the chip pattern area and the blind 70
2 to 20% of the exposure light passes. As a result, FIG.
3 (c), the attenuation type phase shift mask and
As can be seen from the intensity distribution of the light transmitted through the
Chip pattern area L _cAnd the area L of the blind 70_b
Between the transmitted light I₀2-20% light intensity
An area I 'occurs. For this purpose, FIG.
, The chip pattern region 30 (L_c× L_c)of
Around the width L_dThe region 50 of the light intensity (I ') of
I will.

Next, a reduced projection type exposure having the above configuration
Pattern of the attenuated phase shift mask using the
When transferring in a reduced size on a conductor wafer, the chip pattern
Size L_cExposure is performed sequentially at a pitch of FIG.
The size of the top pattern is (L _c× L_c) Attenuated phase shifter
Using a reduction projection type exposure device with a
Exposure area on semiconductor wafer when exposure on wafer
The state of the area is shown.

[0024] In this case, in order to perform the exposure at a pitch L _c in both vertical and horizontal directions, as shown in FIG. 13,
As described above, the area 50 of the light intensity (I ′) is generated around the chip pattern of one exposure shot. This area 50 overlaps with an area generated by another adjacent exposure shot. Further, when the exposure is repeated in sequence, three adjacent regions 50 overlap and are exposed at the corners of the exposure region. For this reason,
In the exposure region, a region 31 in which the region of the light intensity (I ′) of 2 to 20% overlaps the appropriate exposure amount I _O and a region 32 in which the region of the light intensity (I ′) of 2 to 20% overlaps three times. Will occur.

As described above, in the regions 31 and 32 where the exposure light overlaps and is exposed, for example, when the positive resist film is exposed, the resist film after development is reduced. When the transmittance of the absorption type shifter film is high, there has been a problem that the resist film is completely exposed and the resist film is removed by development.

As an attenuated phase shift mask for solving this problem, JP-A-6-175347 and JP-A-7-175347.
There is a technique disclosed in Japanese Patent Publication No. 181669.

Here, an attenuated phase shift mask disclosed in Japanese Patent Application Laid-Open No. 7-181669 will be described with reference to FIG. 15A is a diagram viewed from the pattern forming side of the conventional attenuated phase shift mask, and FIG. 15B is a cross-sectional view taken along line XX in FIG. 15A. is there.

In the attenuated phase shift mask 10, the attenuated phase shift pattern 2 composed of a square area is formed substantially at the center on the photomask substrate 4. In addition, an attenuated auxiliary phase shift pattern 3 is formed in a region around the entire periphery of the attenuated phase shift pattern 2.

The attenuated phase shift pattern 2 includes a phase shifter section 24 and a transmission section 27. The phase shifter section 24 includes a chromium film 2a having a transmittance of 2 to 20% and an SiO ₂ film 2b providing a phase difference of 180 °.

The attenuated auxiliary phase shift pattern 3 includes a chromium film 3a having a transmittance (T) of 2 to 20% and a phase difference of 180%.
It has a phase shifter portion 34 made of a SiO ₂ film 3b for imparting an angle and a transmission portion 37, and has a pattern size smaller than the resolution limit of the exposure apparatus.

As shown in FIG. 2, the phase shifter 3
The planar area of 4 and S _H, if the planar area of the transmissive portion 37 consisting of a square and the S _O, the planar area of the phase shifter portion 34 (S _O), a planar area of the transmissive portion 37 (S _H), The relationship between the transmittance and the transmittance (T) of the phase shifter unit 34 is set so as to satisfy S _O / S _H ≒ √T.

By setting to satisfy this condition,
The light intensity of the light transmitted through the transmission portion 37 on the material to be exposed overlaps the light intensity of the light transmitted through the phase shifter portion 34 on the material to be exposed, and the light intensity substantially cancels out on the material to be exposed. The light intensity is 3% or less of the light intensity before transmitting through the transmission part 37 and the phase shifter part 34.

Therefore, according to the above-mentioned attenuated phase shift mask, the image of the light transmitted through the attenuated auxiliary phase shift pattern 3 on the semiconductor wafer is not resolved because it is smaller than the resolution limit of the exposure apparatus. . Furthermore, since the light transmitted through the transmission part and the phase shifter part overlap each other and the phase is inverted, they interfere with each other and cancel each other out.
The light intensity on the semiconductor wafer can be reduced.

Thus, when the semiconductor wafer is regularly and sequentially exposed using the above-mentioned attenuated phase shift pattern, the light transmitted through the outer edge of the attenuated phase shift pattern is exposed twice or more times. Disappears,
Exposure can be performed without causing exposure failure.

[0035]

However, the above-mentioned attenuated phase shift mask has the following problems.

Generally, when a photomask is manufactured, shipped, and used, a foreign substance (parti) is formed on the photomask.
As shown in FIG. 7, the presence or absence of cle) is inspected using a particle detector (foreign matter inspection machine).

Particle detector (foreign matter inspection machine)
Means that the light L ₁ and L ₂ reflected on the photomask (scattered light) L ₂ and L ₃ are detected by several photodetectors 110, and the reflected light L ₂ and L ₃ are detected by the substrate 4 and the mask. reflected light L from the reflected light L ₂ or foreign object 111 from the pattern 2
₃ is determined. This is because the reflected light L ₃ from the foreign substance 111
Utilizes the fact that the light intensity is higher than other reflected light.

Such a particle detector (different type)
Object inspection machine), as described above,
Square or straight line pattern at regular intervals
Inspection of properly arranged attenuation type auxiliary pattern area
Incident, particle detector (foreign matter inspection machine)
Light L₁Diffracts in a certain direction as shown in FIG.
You. As a result, the incident light L₁Diffraction light (0th-order diffraction light L_Ten,
First order diffracted light L₁₁, Second-order diffracted light L₁₂) Has strong light intensity
Will do. Therefore, the zero-order diffracted light L _Ten~ N
Next order diffracted light L_1nIs incident on the photodetector 110,
It is difficult to distinguish the reflected light from the
Erroneous detection of the data (foreign matter inspection machine).

When the detection sensitivity of the particle detector (foreign matter inspection device) is set low in order to prevent erroneous detection, foreign matter that should be detected (for example, when the size of the foreign matter is 0. 1).
(3 μm to 1.0 μm) cannot be detected.

Therefore, the present invention has been made in order to solve the above-mentioned problems, and in the case where reduced exposure is performed using an attenuated phase shift mask, it is possible to prevent the area around a regular exposure area from being exposed. In particular, an attenuated phase shift mask having a pattern for preventing exposure to a region adjacent to a regular region when performing continuous exposure while moving, and capable of reliably detecting foreign matter; and It is an object of the present invention to provide a manufacturing method thereof.

[0041]

An attenuated phase shift mask according to the present invention comprises an attenuated phase shift pattern formed at a predetermined position on a photomask substrate;
An attenuated auxiliary phase shift pattern including a transmission part and a phase shifter part is formed at a predetermined position on the periphery of the attenuated phase shift pattern. Further, the attenuation type auxiliary phase shift pattern has a pattern smaller than the resolution limit of the exposure apparatus, and the transmission part and the phase shifter part are randomly arranged.

Therefore, according to this attenuated phase shift mask, the image of the light transmitted through the attenuated auxiliary phase shift pattern on the semiconductor wafer is not formed because it is smaller than the resolution limit. Furthermore, since the light transmitted through the transmission part and the phase shifter part overlap with each other and are inverted in phase, they interfere with each other and cancel each other, so that the light intensity on the semiconductor wafer can be reduced. Further, since the transmission portion and the phase shifter portion are randomly arranged, the direction of light (stray light) scattered by the phase shifter portion is made random, and the deterioration of the transfer pattern caused by the light scattered in a specific direction is reduced. It becomes possible.

[0043] Also preferably, the attenuated auxiliary phase shift pattern, the plane area of the transmissive portion (S _O), the value of the ratio S _O / S _H of the planar area of the phase shifter portion (S _H) is the phase shifter It is set to be substantially the same as the value of ΔT of the transmittance (T) of the section. Accordingly, it is possible to control the light intensity on the semiconductor wafer by adjusting the intensity of light passing through the phase shifter portion and the intensity of light passing through the transmission portion in the attenuation type auxiliary phase shift pattern region. .

Thus, when the semiconductor wafer is regularly and sequentially exposed using the attenuated phase shift pattern, the light transmitted through the outer edge portion of the attenuated phase shift pattern overlaps twice or more to expose the region. And exposure can be performed without causing exposure failure.

[0045]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an attenuated phase shift mask according to the present invention will be described.

FIG. 1A is a diagram of the attenuation type phase shift mask 1 according to this embodiment as viewed from the pattern forming side. FIG. 1B is a cross-sectional view taken along line XX in FIG.

In the attenuated phase shift mask 1, an attenuated phase shift pattern 2 composed of a square area is formed substantially at the center on the photomask substrate 4. In addition, an attenuated auxiliary phase shift pattern 3 is formed in a region around the entire periphery of the attenuated phase shift pattern 2.

The attenuated phase shift pattern 2 is composed of a phase shifter section 24 and a transmission section 27. The phase shifter section 24 is composed of a chromium film 2a having a transmittance of 2 to 20% and a SiO ₂ film 2b giving a phase difference of 180 °.

The attenuation type auxiliary phase shift pattern 3 is composed of a chromium film 3a having a transmittance of 2% to 20%, a phase shifter portion 34 made of a SiO ₂ film 3b giving a phase difference of 180 °, and a transmission portion 37, Has a pattern size smaller than the resolution limit of

Further, as shown in FIG. 2, when the area of 10 μm × 10 μm is used as a reference in the attenuation type auxiliary phase shift pattern 3, the plane area (S _H ) of the phase shifter section 34 and the plane area of the transmission section 37. The sum of (S _i ) (S _O : S _O = ΣS _i ) is S _O / S _H = √T (transmittance).
Are satisfied, the transmission part 37 and the phase shifter part 34 are randomly arranged.

As a result, as disclosed in Japanese Patent Application Laid-Open No. 7-181669, the image on the semiconductor wafer of the light passing through the attenuation type auxiliary phase shift pattern 3 is not formed because it is smaller than the resolution limit. . Further, the light transmitted through the transmission part and the phase shifter part overlap each other, and the phases are inverted, so that they interfere with each other and cancel each other, thereby making it possible to weaken the light intensity on the semiconductor wafer.

Further, as shown in FIG. 3, in the attenuation type auxiliary phase shift pattern 3 in which the transmission section 37 and the phase shifter section 34 are randomly arranged, the incident light L ₁
As shown in the figure, the diffracted light (L
_{10 to} L _1n ). Therefore, the inspection using the particle detector (foreign matter inspection machine) does not erroneously detect the phase shifter section 34 as a foreign matter, and the detection sensitivity of the particle detector (foreign matter inspection machine) does not need to be set low.

As a result, it is possible to manufacture an attenuated phase shift mask free from defects due to foreign matter, and it is possible to improve the yield in manufacturing a semiconductor device using this attenuated phase shift mask.

Next, a method of manufacturing the attenuated phase shift mask will be described with reference to FIGS. First, referring to FIG. 4, a film thickness of about 200
A chromium film 23a is formed. Thereafter, an SiO ₂ film 23b having a thickness of about 4000 ° is formed on the chromium film 23a. Further, an electron beam resist film (for example, ZEP-810) 25 is formed on this SiO ₂ film 23b to a thickness of about 5000 °.

Next, referring to FIG. 5, EB lithography is performed on the electron beam resist film 25 using a variable-shaped electron beam exposure apparatus (for example, JEOL JBX-7000MV, 6AIII). When performing this EB drawing,
In order to accurately finish the attenuation type auxiliary phase shift pattern, EB writing is performed as described below.

First, the exposed figure of the attenuated auxiliary phase shift pattern is subjected to a processing of a dimensional bias smaller than the finished dimension of the exposed figure, or the dose of the electron beam in the attenuated auxiliary phase shift pattern area is attenuated. Either processing is performed with a larger dose than the mold phase shift pattern area, or both processings are performed. After that, the electron beam resist film 25 after the EB drawing is developed to complete a predetermined pattern.

Next, referring to FIG. 6, using the electron beam resist film 25 on which a predetermined pattern is formed as a mask,
The SiO ₂ film 23b is etched. The etching at this time was performed using a magnetron RIE apparatus and CHF ₃ + O ₂ (CHF ₃ : O ₂ =
90:10), using RF power of 200 W and magnetic field of 1
The process is performed under the conditions of 00G and a gas pressure of 50 mtorr. Thereby, the SiO ₂ film 2b having a pattern of a predetermined shape in the attenuation type phase shift pattern region 200 and the S 2 having a predetermined shape in the attenuation type auxiliary phase shift pattern region 300.
An iO ₂ film 3b is formed.

Next, referring to FIG. 7, the chromium film 23a is etched again using the electron beam resist film 25. For the etching at this time, a magnetron RIE device is used as in the case of the SiO ₂ film, and Cl ₂ + O ₂ (Cl ₂ : O ₂ = 80: 20) is used as an etching gas.
At 100 W of RF power, 100 G of magnetic field, and 50 mtorr of gas pressure. Thereby, the chromium film 2a having a predetermined shape is formed in the attenuated phase shift pattern region 200.
Are formed, and the attenuation type auxiliary phase shift pattern region 300 is formed.
Then, a chrome film 3a having a predetermined shape is formed. Next, referring to FIG. 8, by removing electron beam resist film 25, attenuated phase shift mask 1 according to the present embodiment is removed.
Is completed.

In the above embodiment, the SiO ₂ film for controlling the phase and the chromium film for controlling the transmittance are used.
It has a layer structure, but is a single layer made of one material selected from the group consisting of chromium oxide, chromium oxynitride, chromium oxynitride carbide, molybdenum silicide oxide, and molybdenum silicide oxynitride Even if a film is used, the phase and the transmittance can be controlled to predetermined values. In this case, the thickness of the chromium oxide or the like is about 1200
1600 °, which is thinner than the two-layer structure described above, and the phase shift pattern can be easily formed.

As described above, according to the attenuated phase shift mask and the method of manufacturing the same according to the present invention, the image of the light transmitted through the attenuated auxiliary phase shift pattern on the semiconductor wafer is smaller than the resolution limit. Do not image. Also, the light transmitted through the transmission part and the phase shifter part overlap each other,
Further, since the phases are inverted, they interfere with each other and cancel each other out, thereby making it possible to weaken the light intensity on the semiconductor wafer.

As a result, it is possible to prevent portions other than the exposure region from being exposed at the time of exposure, to improve the exposure state at the time of manufacturing the semiconductor device, and to improve the yield at the time of manufacturing the semiconductor device. Become.

Further, by randomly arranging the transmission portion and the phase shifter portion, the direction of light (stray light) scattered by the phase shifter portion is made random, and a transfer pattern (chip pattern) generated by light scattered in a specific direction is formed. ) Can be reduced.

As a result, even if the inspection using the particle detector (foreign substance inspection machine) is performed, the phase shifter section is not erroneously detected as foreign matter, and the detection sensitivity of the particle detector (foreign substance inspection machine) needs to be set low. Is also gone.

As a result, it is possible to manufacture an attenuated phase shift mask free from defects due to foreign matter, and it is possible to improve the yield in manufacturing a semiconductor device using this attenuated phase shift mask.

In the above-described embodiment, the attenuated auxiliary phase shift pattern is formed so as to be provided around the chip. By using the method, it is also possible to provide an attenuated auxiliary phase shift pattern. Further, the attenuated auxiliary phase shift pattern is provided not only on the entire circumference of the attenuated phase shift pattern as shown in FIG.
The attenuated auxiliary phase shift pattern may be provided only in other necessary areas.

Further, according to the exposure method using the attenuated phase shift mask in the above embodiment, 4M, 16
M, 64M, 256M, etc. can be effectively used in the manufacturing process of semiconductor devices such as DRAM, SRAM, flash memory, ASIC, microcomputer, GaAs, etc.
Further, it can be sufficiently used in a manufacturing process of a semiconductor device or a liquid crystal display.

It should be understood that the embodiments disclosed this time are illustrative in all aspects and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

[0068]

According to the attenuated phase shift mask according to the present invention, an attenuated phase shift pattern formed at a predetermined position on a photomask substrate and a predetermined portion of a peripheral portion of the attenuated phase shift pattern are provided. And an attenuated auxiliary phase shift pattern including a transmission portion and a phase shifter portion formed at the position. Further, the attenuation type auxiliary phase shift pattern has a pattern smaller than the resolution limit of the exposure apparatus, and the transmission part and the phase shifter part are randomly arranged.

Therefore, the image of the light transmitted through the attenuation type auxiliary phase shift pattern on the semiconductor wafer is not formed because it is smaller than the resolution limit. Furthermore, since the light transmitted through the transmission part and the phase shifter part overlap with each other and the phases are inverted, they interfere with each other and cancel each other out.
The light intensity on the semiconductor wafer can be reduced.

Preferably, an attenuated auxiliary phase shift is used.
The plane area (S _O) And the phase shifter
Area (S_H) And the ratio S_O/ S_HOf the phase shift
The transmittance (T) of the lid portion should be substantially equal to the value of ΔT.
Is set to

Thus, it is possible to control the light intensity on the semiconductor wafer by adjusting the intensity of light transmitted through the phase shifter portion and the intensity of light transmitted through the transmission portion in the attenuation type auxiliary phase shift pattern region. It becomes possible.

Further, when a semiconductor wafer is regularly and sequentially exposed using this attenuated phase shift mask, light which passes through the outer edge of the attenuated phase shift pattern overlaps twice or more to expose the region. And exposure can be performed without causing exposure failure.

Further, since the transmission portion and the phase shifter portion are randomly arranged, the direction of light (stray light) scattered by the phase shifter portion is made random, and a transfer pattern (chip) generated by light scattered in a specific direction is formed. Pattern) can be reduced.

As a result, even when the inspection using the particle detector (foreign substance inspection machine) is performed, the phase shifter portion is not erroneously detected as foreign matter, and the detection sensitivity of the particle detector (foreign substance inspection machine) needs to be set low. Is also gone.

As a result, it is possible to manufacture an attenuated phase shift mask free from defects due to foreign matter, and it is possible to improve the yield in manufacturing a semiconductor device using this attenuated phase shift mask.

[Brief description of the drawings]

FIG. 1A is a diagram viewed from a pattern forming surface of an attenuated phase shift mask according to an embodiment based on the present invention, and FIG. 1B is a cross-sectional view taken along line XX in FIG. FIG.

FIG. 2 is a diagram showing a pattern shape of an attenuated auxiliary phase shift pattern in an embodiment according to the present invention.

FIG. 3 is a schematic diagram showing an inspection state of an attenuation type auxiliary phase shift pattern by a particle detector (foreign matter inspection machine) in the embodiment based on the present invention.

FIG. 4 is a first manufacturing step of the attenuated phase shift mask in the embodiment based on the present invention.

FIG. 5 shows a second manufacturing step of the attenuation type phase shift mask in the embodiment based on the present invention.

FIG. 6 shows a third manufacturing step of the attenuation type phase shift mask in the embodiment according to the present invention.

FIG. 7 shows a fourth manufacturing step of the attenuated phase shift mask in the embodiment based on the present invention.

FIG. 8 is a fifth manufacturing step of the attenuation type phase shift mask in the embodiment based on the present invention.

FIG. 9A is a cross-sectional view illustrating a structure of a conventional photomask. (B) is a diagram showing an electric field of exposure light on a mask. (C) is a diagram showing the intensity of exposure light on the wafer.

FIG. 10A is a cross-sectional view illustrating the structure of a conventional phase shift mask. (B) is a diagram showing an electric field of exposure light on a mask. (C) is a diagram showing the intensity of exposure light on the wafer.

FIG. 11A is a diagram showing a structure of a conventional attenuated phase shift mask. (B) is a diagram showing an electric field of exposure light on a mask. (C) is a diagram showing the intensity of exposure light on the wafer.

FIG. 12 is a diagram showing the relationship between transmittance and the thickness of a resist film after development.

FIG. 13A is a cross-sectional view showing a positional relationship between a conventional attenuated phase shift mask and a blind. (B)
FIG. 4 is a diagram illustrating an electric field of exposure light immediately below a photomask substrate. (C) is a diagram showing the intensity of exposure light on the semiconductor wafer. (D) is a figure which shows the state of the exposure on a semiconductor wafer.

FIG. 14 is a diagram showing a problem when a conventional attenuated phase shift mask is used.

FIG. 15A is a diagram viewed from a pattern formation surface of an attenuated phase shift mask according to a conventional technique, and FIG.
FIG. 3A is a sectional view taken along line XX in FIG.

FIG. 16 is a diagram showing a pattern shape of an attenuated auxiliary phase shift pattern according to the related art.

FIG. 17 is a first schematic diagram showing an inspection state of a photomask by a particle detector (foreign matter inspection machine).

FIG. 18 is a second schematic diagram showing an inspection state of a photomask by a particle detector (foreign matter inspection machine).

[Explanation of symbols]

1 attenuated phase shift mask, 2 attenuated phase shift pattern, 3 attenuated auxiliary phase shift pattern, 4 photomask substrate.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Junji Miyazaki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Sanyo Electric Co., Ltd. (72) Inventor Shinichiro Tanaka 4-1-1 Mizuhara, Itami-shi, Hyogo Ryoden Semiconductor System Engineering Co., Ltd.

Claims (7)

[Claims] 1. An attenuated phase shift pattern formed at a predetermined position on a photomask substrate, and a transmission portion and a phase shifter portion formed at a predetermined position on a peripheral portion of the attenuated phase shift pattern. An attenuated auxiliary phase shift pattern, wherein the attenuated auxiliary phase shift pattern has a pattern smaller than the resolution limit of the exposure apparatus, and the transmission unit and the phase shifter unit are arranged irregularly. Attenuated phase shift mask. 2. The attenuated auxiliary phase shift pattern includes a light intensity of light transmitted through the transmission portion on a material to be exposed and a light intensity of light transmitted through the phase shifter portion on a material to be exposed. Are overlapped and cancelled, so that the substantial light intensity on the material to be exposed is 3% or less of the light intensity before transmitting through the transmission portion and the phase shifter portion. The attenuation type according to claim 1, wherein three values of a plane area (S _O ), a plane area (S _H ) of the phase shifter section, and a transmittance (T) of the phase shifter section are set. Phase shift mask. 3. The attenuated auxiliary phase shift pattern,
The value of the ratio S _O / S _H between the plane area (S _O ) of the transmission section and the plane area (S _H ) of the phase shifter section is the value of ΔT of the transmittance (T) of the phase shifter section. 3. The attenuated phase shift mask according to claim 2, which is substantially the same as. 4. A light transmittance of 2 to 20% on a transparent substrate.
Forming an attenuated phase shifter film that converts the phase of transmitted light by 180 °; an attenuated phase shift pattern region on the attenuated phase shifter film; and a periphery of the attenuated phase shift pattern region. Forming a resist film including an attenuated auxiliary phase shift pattern region formed at a predetermined position of the portion, and patterning the attenuated phase shifter film by etching using the resist film as a mask. Manufacturing the attenuation type phase shift mask, wherein the attenuation type auxiliary phase shift pattern region has a pattern smaller than the resolution limit of the exposure apparatus, and the transmission portion and the phase shifter portion are arranged irregularly. Method. 5. The step of forming the attenuated phase shifter film includes the steps of forming a semi-shielding film having a light transmittance of 2 to 20%, and a phase shifter film for converting the phase of transmitted light by 180 °. 5. The method of manufacturing an attenuated phase shift mask according to claim 4, comprising the step of: 6. The method according to claim 5, wherein forming the semi-light-shielding film includes forming a chromium film, and forming the phase shifter film includes forming a silicon oxide film. A method for manufacturing an attenuation type phase shift mask. 7. The step of forming the attenuated phase shifter film includes the step of forming a chromium oxide, a chromium oxynitride, a chromium oxynitride carbide, a molybdenum silicide oxide, and a molybdenum silicide oxynitride. 5. The method for manufacturing an attenuated phase shift mask according to claim 4, comprising a step of forming one type of film selected.