JPH05289305A - Phase-shift photomask - Google Patents

Abstract

PURPOSE:To obtain a phase-shift photomask by using a film consisting of a material excellent in etching selectivity as an etching stopper layer and capable of surely and automatically stopping etching. CONSTITUTION:The phase-shift photomask consists of at least a substrate 29 and a phase shifter pattern 44 consisting essentially of silicon oxide and provided on the surface through a light-shielding pattern 37 or directly on the surface. An etching stopper layer 30 consisting of CrOx, CrNy, CrCz, CrOxNy, CrOxCz or CrOxNyCz is provided on the substrate 29 surface, and hence the phase shifter transparent film is surely and precisely etched by the etching stopper action when a phase shifter pattern is formed by etching.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask used in the manufacture of high density integrated circuits such as LSI and VLSI, and more particularly to a phase mask having a phase shift layer for forming a fine pattern with high accuracy. Regarding a shift photomask.

[0002]

2. Description of the Related Art Semiconductor integrated circuits such as ICs, LSIs, and VLSIs are formed by applying a resist onto a substrate to be processed such as a Si wafer, exposing a desired pattern with a stepper, and then developing and etching it. It is manufactured by repeating the lithography process.

Photomasks called reticles used in such lithography processes tend to be required to have higher precision as semiconductor integrated circuits have higher performance and higher integration. DRA which is LSI
Taking M as an example, the dimensional deviation of a 5 × reticle for a 1 Mbit DRAM, that is, a reticle having a size 5 × that of a pattern to be exposed is an average value of ± 3σ (σ is a standard deviation). Also, a precision of 0.15 μm is required, and similarly, a quintuple reticle for a 4 Mbit DRAM has a dimensional precision of 0.1 to 0.15 μm of 16M.
5 times reticle for bit DRAM is 0.05-0.1 μm
Dimensional accuracy is required.

Further, the line width of the device pattern formed by using these reticles is 1 Mbit DRAM.
1.2 μm, 0.8 μm for 4M bit DRAM, 1
The 6 Mbit DRAM is required to be further miniaturized to 0.6 μm, and various exposure methods are being researched to meet such a demand.

However, when the next-generation device patterns of the 64 Mbit DRAM class are used, the resolution of resist patterns becomes the limit in the stepper exposure method using the reticle that has been used up to now, for example, Japanese Patent Laid-Open No. 58-1737.
A reticle having a new concept of a phase shift mask as disclosed in Japanese Patent Publication No. 44, Japanese Patent Publication No. 62-59296, etc. has been proposed. Phase shift lithography using this phase shift reticle is a technique for improving the resolution and contrast of a projected image by manipulating the phase of light passing through the reticle.

Phase shift lithography will be briefly described with reference to the drawings. FIG. 3 is a diagram showing the principle of the phase shift method,
FIG. 4 is a diagram showing a conventional method, which is shown in FIGS.
FIG. 3A is a cross-sectional view of the reticle, FIGS. 3B and 4B.
Is the amplitude of the light on the reticle, FIGS. 3 (c) and 4 (c) are the amplitudes of the light on the wafer, and FIGS. 3 (d) and 4 (d) are the light intensities on the wafer, respectively. Substrate 2, light-shielding film, 3 phase shifter, and 4 incident light.

In the conventional method, as shown in FIG. 4 (a), a light-shielding film 2 made of chromium or the like is formed on a substrate 1 made of quartz glass or the like to form a light transmitting portion having a predetermined pattern. However, in the phase shift lithography, as shown in FIG. 3A, a phase shifter 3 made of a transmissive film for inverting the phase (a phase difference of 180 °) to one of the adjacent light transmissive portions on the reticle is used. Is provided.
Therefore, in the conventional method, the amplitude of light on the reticle becomes in-phase as shown in FIG. 4B, and the amplitude of light on the wafer also becomes in-phase as shown in FIG. 4C. As shown in FIG. 4D, the pattern on the wafer cannot be separated, whereas in the phase shift lithography, the light transmitted through the phase shifter is
As shown in (b), since the adjacent patterns are in opposite phases to each other, the light intensity becomes zero at the boundary portion of the patterns, and the adjacent patterns are clearly separated as shown in FIG. 3 (d). be able to. As described above, in the phase shift lithography, it becomes possible to separate a pattern that could not be separated in the past, and the resolution can be improved.

Next, one of the manufacturing steps of the phase shift reticle
An example will be described with reference to the drawings. FIG. 5 is a sectional view showing a manufacturing process of the phase shift reticle. In the figure, 11 is a quartz substrate, 12 is a chrome film, 13 is a resist layer, 14 is ionizing radiation, 15 is a resist pattern, 16 is an etching gas plasma, Reference numeral 17 is a chrome pattern, 18 is an oxygen plasma, 19 is a transparent film, 20 is a resist layer, 21 is ionizing radiation, 22 is a resist pattern, 23 is an etching gas plasma, 24 is a phase shift pattern, and 25 is oxygen plasma.

First, as shown in FIG. 5 (a), a chromium film 12 is formed on an optically polished quartz substrate 11, and further,
Ionizing radiation resist such as chloromethylated polystyrene is uniformly applied by a conventional method such as spin coating,
A heat drying process is performed to form a resist layer 13 having a thickness of about 0.1 to 2.0 μm. The heat-drying treatment is usually ± 80 to 150 ° C., though it depends on the type of resist used.
Perform for 20 to 60 minutes.

Next, as shown in FIG. 1B, a pattern is drawn on the resist layer 13 by an ionizing radiation 14 by an exposure apparatus such as an electron beam drawing apparatus according to a conventional method, and an organic solvent such as ethyl cellosolve or ester is drawn. After developing with a developing solution containing the main component, rinsing with alcohol is performed to form a resist pattern 15 as shown in FIG.

Next, if necessary, heat treatment and descum treatment are performed to remove the resist scraps remaining on the edge portions of the resist pattern 15 and unnecessary resist such as whiskers. Then, as shown in FIG. As shown, resist pattern 1
The portion to be processed exposed from the opening of 5, that is, the chromium layer 12 is dry-etched by the etching gas plasma 16 to form the chromium pattern 17. It is apparent to those skilled in the art that the chrome pattern 17 may be formed by wet etching instead of dry etching by the etching gas plasma 16.

After etching in this way, as shown in FIG. 2E, the resist pattern 15, that is, the remaining resist is ashed and removed by oxygen plasma 18, and the photo resist shown in FIG. Complete the mask. Note that this treatment can be performed by solvent stripping instead of the ashing treatment by the oxygen plasma 18.

Subsequently, this photomask is inspected, and if necessary, pattern modification is performed, and after cleaning, SiO 2 is deposited on the chrome pattern 17 as shown in FIG.
_A transparent film 19 made of ₂ or the like is formed. Next, the same figure (h)
As shown in FIG. 2, an ionizing radiation resist layer 2 such as chloromethylated polystyrene is formed on the transparent film 19 in the same manner as described above.
0, and the resist layer 20 is formed as shown in FIG.
Then, an aligning process is performed according to a conventional method, a predetermined pattern is drawn by ionizing radiation 21 such as an electron beam exposure device, developed and rinsed to form a resist pattern 22 as shown in FIG.

Next, after performing a heat treatment and a descum treatment, if necessary, as shown in FIG. 3K, the transparent film 19 portion exposed from the opening of the resist pattern 22 is etched with an etching gas plasma. Dry etching is performed by using 23 to form a phase shifter pattern 24. The formation of the phase shifter pattern 24 may be performed by wet etching instead of dry etching by the etching gas plasma 23.

Next, the remaining resist is ashed and removed by oxygen plasma 25, as shown in FIG. Through the above steps, the phase shift mask having the phase shifter 24 as shown in FIG.

By the way, in the conventional method for manufacturing a phase shift reticle as described above, the etching control in the depth direction of the transparent film 19 forming the phase shifter must be accurately performed. Particularly, since the substrate 11 and the transparent film 19 are made of the same SiO ₂ -based material, if the etching is continued even after the etching of the transparent film 19 is completed, the substrate 11
Is also etched, the phase shift amount of the phase shifter becomes larger than 180 °, and it becomes difficult to accurately transfer the pattern.

Therefore, the present applicant has provided an etching stopper layer between the transparent film forming the phase shifter and the substrate,
To stop etching automatically by this layer, Japanese Patent Application Nos. 2-29801, 2-181795, and 3-
Proposed in 295610. The material proposed for the etching stopper layer in these applications was tantalum, molybdenum, tungsten, silicon nitride, a mixture of alumina and manganese oxide, zirconium oxide, tantalum oxide or hafnium oxide.

[0018]

However, in the etching stopper layer made of such a material, it is not always easy to stop the etching accurately and sufficiently, and the etching stopper layer is also formed in the manufacturing process. Therefore, it is necessary to introduce a special material into the film forming apparatus, which causes a problem of complicating the manufacturing process.

The present invention has been made in view of such a situation, and an object thereof is to provide excellent etching selectivity as an etching stopper layer, capable of reliably and automatically stopping etching, and reducing the light shielding film. An object of the present invention is to provide a phase shift photomask using a film made of the material used for the reflective chrome layer.

[0020]

In view of the above problems, the present invention has been researched to develop a phase shifter of a practical and highly accurate phase shift reticle. As a result, the present invention has been used for a low reflection chromium layer of a light shielding film. CrO _x , CrN _y , CrC _z , C
The inventors have found that rO _x N _y , CrO _x C _z , and CrO _x N _y C _z have excellent etching selectivity, and have completed the present invention based on such findings.

That is, the phase shift photomask of the present invention comprises at least a substrate and a phase shift photopattern formed on the surface of the substrate via a light-shielding pattern or directly, and a phase shifter pattern made of a material containing silicon oxide as a main component. In the mask, CrO _x , Cr on the substrate surface
N _y , CrC _z , CrO _x N _y , CrO _x C _z or Cr
It is characterized by comprising an etching stopper layer composed of O _x N _y C _z .

In this case, in the case where the phase shifter pattern is provided via the light shielding pattern, it is desirable to provide a silicon oxide layer between the etching stopper layer and the light shielding pattern.

[0023]

In the phase shift photomask of the present invention,
CrO _x , CrN _y , CrC _z , CrO _x N on the substrate surface
_Since an etching stopper layer made of _y , CrO _x C _z or CrO _x N _y C _z is provided, when the phase shifter pattern is formed by etching, CrO _x , CrN
_y , CrC _z , CrO _x N _y , CrO _x C _z or CrO
_{Since x} N _y C _z acts as an etching stopper layer, the transparent film for phase shifter can be reliably etched, and the etching can be automatically stopped, so that a higher quality phase shift photomask can be obtained. .. Further, since the above-mentioned layer is made of the material used for the low reflection chromium layer of the light-shielding film, it can be easily manufactured without using any special material or device in manufacturing and without significantly changing the process.

[0024]

EXAMPLE A phase shift photomask of the present invention comprises CrO _x , CrN _y , CrC _z and CrO as an etching stopper layer between a substrate and a transparent film for a phase shifter.
_{x N y, CrO x C z} , is characterized in providing the film made of CrO _x N _y C _z. Examples of the phase shift photomask of the present invention will be described below while describing the method of manufacturing the phase shift photomask.

FIG. 1 is a cross sectional view showing a step of a method of manufacturing a phase shift photomask of the type placed on the phase shifter according to the present invention, in the figure, 29 is a substrate, 30 CrO _x, C
rN _y , CrC _z , CrO _x N _y , CrO _x C _z or C
etching stopper layer made of rO _x N _y C _z , 31
Is a protective layer made of SiO ₂ , 32 is a light shielding layer, 33 is a resist layer, 34 is ionizing radiation, 35 is a resist pattern,
36 is an etching gas plasma, 37 is a light shielding pattern,
38 is oxygen plasma, 39 is a transparent film, 40 is a resist layer, 41 is ionizing radiation, 42 is a resist pattern, 43
Is a reactive ion, 44 is a phase shift pattern, and 45 is an oxygen plasma.

First, as shown in FIG. 1A, a uniform etching stopper layer 30 having a thickness of 5 to 30 nm and a protective layer 31 and 1 having a thickness of 5 to 100 nm are formed on an optically polished substrate 29.
A light-shielding layer 32 having a thickness of 0 to 200 nm is sequentially formed, and an ionizing radiation resist such as chloromethylated polystyrene is further added.
A resist layer 33 having a thickness of about 0.1 to 2.0 μm is formed by applying it uniformly by a conventional method such as spin coating and performing a heat drying treatment. Here, as the substrate 29, quartz or high-purity synthetic quartz is preferable in view of the fact that the phase shift mask is for short wavelength such as i-line and excimer laser, but in addition, low expansion glass, white plate, Blue plate (SL), MgF ₂ , CaF ₂ or the like can be used. The etching stopper layer 30 is made of CrO _x ,
It can be formed using CrN _y , CrC _z , CrO _x N _y , CrO _x C _z, or CrO _x N _y C _z . Here, _x of CrO _x is 0.01 to 3, _y of CrN y is 0.01 to 2, _z of CrC z is 0.01 to 1.5,
In CrO _x N _y , x is 0.01 to 3, y is 0.01 to 2, and CrO _x C _z is 0.01 to 2 and z is 0.01.
To 1.5, _x of CrO _x N _y C _z is 0.01 to 3,
It is desirable that y is in the range of 0.01 to 2 and z is in the range of 0.01 to 1.5. Further, the light shielding layer 32 can be formed of tungsten, molybdenum, molybdenum silicide, or the like, but since the etching stopper layer 30 is formed of a chromium-based material as described above, a chromium thin film is used as a single process. Whether to form multiple layers or multiple layers,
Alternatively, it is desirable to use a chromium-based material such as chromium nitride or chromium oxide. Further, the heat drying treatment of the resist layer 33 is usually ± 80 to, though it depends on the kind of the resist.
It is carried out at 150 ° C. for about 20 to 60 minutes.

Next, as shown in FIG. 2B, a predetermined pattern is drawn on the resist layer 33 by an exposure device using ionizing radiation 34 such as an electron beam drawing device in accordance with a conventional method, and ethyl cellosolve, ester, etc. are drawn. After developing with a developing solution containing an organic solvent as a main component, rinsing with alcohol forms a resist pattern 35 as shown in FIG.

Next, if necessary, heat treatment and descum treatment are carried out to remove unnecessary resist such as resist dust and beard remaining on the edge portion of the resist pattern 35, etc., as shown in FIG. The processed portion exposed from the opening of the resist pattern 35, that is, the light shielding layer 32 is dry-etched by the etching gas plasma 36 to form the light shielding pattern 37. At this time, unless a protective layer 31, an etching stopper layer 30 at the same time as the etching of the light shielding layer 32 is also etched but, SiO ₂
By providing the protective layer 31 made of, the etching stopper layer 30 remains as it is. The light shielding pattern 37 may be formed by wet etching instead of dry etching by the etching gas plasma 36.

After etching in this way, as shown in FIG. 6E, the remaining resist 35 is ashed and removed by oxygen plasma 38, and as shown in FIG.
An etching stopper layer 30 is formed on the substrate 29, and a photomask having a predetermined light shielding pattern 37 formed thereon is prepared. Note that this treatment can be performed by removing the solvent instead of the ashing treatment with the oxygen plasma 38.

Subsequently, this photomask is inspected, and if necessary, the pattern is modified, and after cleaning, it is vapor-deposited on the light-shielding pattern 37 by spin-on-glass (SOG) as shown in FIG. A transparent film 39 containing SiO ₂ as a main component is formed. The film thickness d of the transparent film 39 is a value given by d = λ / 2 (n−1), where n is the refractive index of the material forming the transparent film 39 and λ is the exposure wavelength.
The value of d is about 406 nm when SOG is used.

Next, as shown in FIG. 3H, the transparent film 3
In the same manner as described above, an ionizing radiation resist such as chloromethylated polystyrene is uniformly applied on 9 to form a resist layer 40. As shown in FIG. Alignment is performed, a predetermined pattern is drawn at a position where the phase is to be shifted by the ionizing radiation 41 such as an electron beam exposure device, developed with a predetermined developing solution, rinsed, and then, as shown in FIG. The pattern 42 is formed.

Subsequently, after performing heat treatment and descum treatment as required, the transparent film 39 portion exposed from the opening of the resist pattern 42 is CF-treated as shown in FIG.
_A phase shift pattern 44 is formed by dry etching by reactive ion etching using reactive ions 43 using ₄ , C ₂ F ₆ , CHF ₃ + O ₂ and a mixed gas thereof. The phase shift pattern 44 may be formed by wet etching using a hydrofluoric acid-based solution instead of reactive ion etching.

At this time, in the conventional method, the etching reaches the substrate 29, and it is difficult to determine the end point of the etching, or the substrate 29 is also etched, and the phase shift amount of the phase shifter is larger than 180 °. However, there is a problem that it becomes difficult to transfer an accurate pattern. However, in the present invention, Cr, which has a high etching resistance to reactive ions and an etching solution, is used.
O _x , CrN _y , CrC _z , CrO _x N _y , CrO _x C
_z or CrO _x N _y C _z as an etching stopper layer 30
Therefore, the transparent film 39 can be surely etched, and the etching can be automatically stopped, so that a higher quality phase shift photomask can be produced. At the time of this etching, the portion of the protective layer 31 located under the transparent film 39 is also etched away.

Next, as shown in FIG. 1L, the remaining resist is ashed and removed by oxygen plasma 45. This completes a highly accurate phase shift photomask as shown in FIG. Note that this treatment can be performed by removing the solvent instead of the ashing treatment with the oxygen plasma 45.

By the way, such an etching stopper layer can be applied not only to the phase shifter top type phase shift photomask as shown in FIG. 3 but also to the phase shifter bottom type phase shift photomask. Part 1
As an example, a case where this etching stopper layer is applied to a self-aligned phase shift photomask proposed by the present applicant in Japanese Patent Application No. 2-181795 will be briefly described below.

FIG. 2 is a cross-sectional view showing a manufacturing process of such a phase shift photomask, in which 50 is a substrate.
51 is CrO _x , CrN _y , CrC _z , CrO _x N _y ,
An etching stopper layer made of CrO _x C _z or CrO _x N _y C _z , 52 is a transparent film, 53 is a light-shielding thin film, 54
Is a resist layer, 55 is a resist pattern, 56 is ionizing radiation, 57 is an etching gas plasma, 58 is a light shielding pattern, 59 is an oxygen plasma, 60 is a resist layer, 61 is back exposure, 62 is reactive ion, 63 is a phase shifter. A pattern, 64 shows oxygen plasma.

First, as shown in FIG. 2A, a uniform etching stopper layer 51 having a thickness of 5 to 30 nm and a Si film having a thickness d = λ / 2 (n-1) are formed on an optically polished substrate 50.
A transparent film 52 containing O ₂ as a main component and a light shielding layer 53 having a thickness of 50 to 200 nm are sequentially formed to form a photomask blank.

Then, an ionizing radiation resist such as chloromethylated polystyrene is uniformly applied on the photomask blanks by a conventional method such as spin coating, and heat-dried to a thickness of about 0.1 to 2.0 μm. A resist layer 54 is formed.

In consideration of the fact that the phase shift mask of the present invention is usually used for a short wavelength such as i-line or excimer laser as the substrate 50, quartz, high-purity quartz,
It is preferable to use MgF ₂ , CaF ₂ or the like. However, when the wavelength is longer than that, low expansion glass, white plate glass, blue plate glass or the like may be used. Further, the etching stopper layer 51 is made of CrO _x , C as in the case of FIG.
rN _y , CrC _z , CrO _x N _y , CrO _x C _z or C
It is formed using rO _x N _y C _z . In addition, the transparent film 52
Is preferably a high-purity SiO ₂ film, and as a coating method for this film, a sputtering method, a CVD method, or spin-on-glass coating (for example, spin coating siloxane and heating to form a SiO ₂ film) is used. Adopted. Further, the light shielding layer 53 can be formed by forming a thin film of chromium, chromium nitride, chromium oxide, tungsten, molybdenum, molybdenum silicide or the like in a single layer or a multi-layer.

The heat-drying treatment of the resist is usually at 80 to 200 ° C. for 20 to 20 although it depends on the kind of the resist.
Do it for about 60 minutes.

Next, as shown in FIG. 2 (b), a predetermined pattern is drawn on the resist layer 54 by an exposure device using ionizing radiation 56 such as an electron beam drawing device in accordance with a conventional method, and ethyl cellosolve, ester or the like is formed. After developing with a developing solution containing an organic solvent as a main component, rinsing with alcohol forms a resist pattern 55 as shown in FIG.

Next, after performing heat treatment and descum treatment as needed to remove unnecessary resist such as resist dust and beard remaining on the edge portion of the resist pattern 55, as shown in FIG. In addition, the processed portion exposed from the opening of the resist pattern 55, that is, the light shielding layer 53.
Is dry-etched with an etching gas plasma 57 to form a light-shielding pattern 58 (FIG. (D)). In addition,
It is apparent to those skilled in the art that the light shielding pattern 58 may be formed by wet etching instead of dry etching by the etching gas plasma 57.

After etching in this manner, the remaining resist 55 is ashed and removed by oxygen plasma 59, as shown in FIG.
An etching stopper layer 51 is formed on the substrate 50, a phase shift layer 52 is formed on the etching stopper layer 51, and a photomask having a predetermined light shielding pattern 58 formed thereon is formed. The remaining resist 55 may be removed by solvent removal instead of the ashing treatment by the oxygen plasma 59.

Subsequently, this photomask is inspected, and if necessary, the pattern is modified and washed, and then the OFPR is formed on the light shielding pattern 58 as shown in FIG.
A photoresist such as -800 is uniformly applied by a conventional method such as spin coating, and heat-dried to give a thickness of 1
A resist layer 60 having a thickness of about 2 μm is formed.

Subsequently, the resist layer 60 is back-exposed 61 from the glass substrate 50 side, developed with an alkaline aqueous solution containing tetramethylammonium hydroxide as a main component, rinsed with pure water, and then on the light shielding pattern 58. A pattern with a resist pattern is formed.

Next, as shown in FIG. 2G, the processed portion exposed from the opening of the resist pattern, that is, the phase shift layer 52 is changed to CF ₄ , C ₂ F ₆ , and CHF ₃ +.
Dry etching is performed by reactive ion etching with reactive ions 62 using O ₂ and a mixed gas thereof to form a phase shifter pattern 63 ((h) in the figure).

Subsequently, this substrate is treated with an etching liquid containing ceric ammonium nitrate as a main component to side-etch the light shielding film 58 sandwiched between the phase shifter 63 and the resist 60. This side etching amount is usually 0.1 to 0.5, though it depends on the type and size of the pattern.
It is about μm.

After etching in this way, the remaining resist 60 is ashed and removed by oxygen plasma 64 as shown in FIG. 9I, and the self-aligned phase shown in FIG. The shift mask is completed.

Also in this case, as in the case of FIG. 1, CrO _x , CrN having a large etching resistance to the reactive ions.
_y , CrC _z , CrO _x N _y , CrO _x C _z or CrO
Since the _x N _y C _z is used as an etching stopper layer 51, it is possible to reliably etch the transparent film 52, it can be automatically stopped etching, creating a higher quality phase shift photomask can do. In the case of the phase shift photomask of the phase shifter underlaying type in which the phase shift layer is under the light shielding layer as described above, as in the case of the phase shifter overlaying type of FIG. On SiO
_It is not always necessary to provide a protective layer consisting of ₂ .

Although the phase shift photomask of the present invention has been described above based on the embodiments, the present invention is not limited to these embodiments and various modifications can be made. Also,
The type of the phase shift photomask to which the etching stopper layer made of the above material can be applied is not limited to the above examples, and any conventionally known type such as a halftone phase shift photomask can be applied.

[0051]

As a photomask used for manufacturing a semiconductor integrated circuit, a photomask on which a light-shielding film such as a chromium film is patterned on a glass substrate such as quartz is currently used. However, the conventional exposure technology using a photomask is approaching its limit, and is moving toward the use of a phase shift photomask.

The phase shift photomask according to the present invention is
As described above, CrO _x , CrN _y , Cr are formed on the substrate surface.
C _z , CrO _x N _y , CrO _x C _z or CrO _x N _y C
Since it has an etching stopper layer made of _z ,
When creating the phase shifter pattern by etching,
CrO _x , CrN _y , CrC _z , CrO _x N _y , CrO
_x C _z, or CrO _x N _y C _z acts as an etching stopper layer, with a phase shifter transparent film can be surely etched automatically because the etching can be stopped, higher quality of the phase It becomes a shift photomask. Further, since the above-mentioned layer is made of the material used for the low reflection chromium layer of the light-shielding film, it can be easily manufactured without using any special material or device in manufacturing and without significantly changing the process.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a step in a method for manufacturing a phase shift photomask according to the present invention.

FIG. 2 is a cross-sectional view showing a manufacturing process of another phase shift photomask according to the present invention.

FIG. 3 is a diagram showing a principle of a phase shift method.

FIG. 4 is a diagram showing a conventional method.

FIG. 5 is a cross-sectional view showing a manufacturing process of a conventional phase shift photomask.

[Explanation of symbols]

 29 ... Substrate 30 ... Etching stopper layer 31 ... Protective layer 32 ... Shading layer 33 ... Resist layer 34 ... Ionizing radiation 35 ... Is a resist pattern 36 ... Etching gas plasma 37 ... Shading pattern 38 ... Oxygen plasma 39 ... Transparent film 40 ... Resist layer 41 ... Ionizing radiation 42 ... Resist pattern 43 ... Reactive ions 44 ... Phase shift pattern 45 ... Oxygen plasma

Claims (2)

[Claims] 1. A phase shift photomask comprising at least a substrate and a phase shifter pattern composed of a silicon oxide provided or directly through the light-shielding pattern on the surface of a material composed mainly, CrO _x on the substrate surface,
A phase shift photomask comprising an etching stopper layer made of CrN _y , CrC _z , CrO _x N _y , CrO _x C _z or CrO _x N _y C _z . 2. The phase shift photomask according to claim 1, wherein the phase shifter pattern is provided via a light blocking pattern, and a silicon oxide layer is provided between the etching stopper layer and the light blocking pattern. ..