JP3194410B2 - Manufacturing method of halftone type phase shift mask - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a halftone type phase shift mask mainly used as a photomask in a projection exposure apparatus .

[0002]

2. Description of the Related Art Conventionally, photomasks having various structures have been proposed. Recently, there has been known a phase shift mask capable of transferring a high-resolution pattern by giving a phase difference to projection exposure light passing through a photomask.
Various types of phase shift masks have been proposed in the past. For example, a Levenson-type phase shift mask having a structure in which a transparent film is provided so as to invert the phase on one side adjacent to the opening on the mask, or a phase shifter having a resolution equal to or less than the resolution limit is formed around the pattern to be formed. There are a phase shift mask with an auxiliary pattern having a structure, a self-aligned phase shift mask having a structure in which a chromium pattern is formed on a substrate, and an overhang of a phase shifter is formed by overetching, or the like.

The phase shift mask of each of the above structures is provided with a chromium pattern and a shifter pattern on a substrate. Apart from this structure, a phase shift mask formed of only a shifter pattern is used as a transmission type phase shift mask. Shift masks and halftone phase shift masks are also known. A transmissive phase shift mask is a phase shift mask that separates patterns by utilizing the fact that light intensity becomes zero at a boundary between light transmitted through a transparent part and light transmitted through a phase shifter. Therefore, it is also called a shifter edge-based phase shift mask.

A halftone type phase shift mask is formed by forming a so-called semi-transparent phase shifter pattern having partial transparency with respect to projection exposure light on a substrate, and forming a boundary between the phase shifter patterns. This is a phase shift mask that improves the resolution of a pattern in a portion where the formed light intensity is zero. Since the transmission type phase shift mask and the halftone type phase shift mask have a simple layer structure, the manufacturing steps are easy and the defects on the mask are few.

As a method of manufacturing a halftone type phase shift mask, a method schematically shown in FIG. 2 is conventionally known. In this method, a halftone material film, for example, a Mo.Si (molybdenum / silicon) -based halftone material film 2 is formed on a transparent substrate 1, and a resist film 3 is further formed thereon (a). Next, a desired pattern is formed by exposing and developing the resist film 3 (b), and the halftone material film 2 is etched and patterned using the patterned resist film 3 'as a mask (c). Thereafter, the resist film 3 'is peeled off, and the substrate 1
A halftone type phase shift mask on which a halftone material film 2 ′ having a desired pattern is formed is formed (d).

As another method of manufacturing a halftone type phase shift mask, a method schematically shown in FIG. 3 is conventionally known. In this conventional method, M
An o-Si halftone material film 2 is formed, and a Mo metal film 4 and a resist film 3 having the same etching characteristics as the halftone material film 2 are formed thereon (a). Next, the resist film 3 is subjected to electron beam exposure and development to form a desired pattern (b), and the metal film 4 and the halftone material film 2 are simultaneously etched using the patterned resist film 3 'as a mask. (C).

After that, the resist film 3 ′ and the patterned metal film 4 ′ are peeled off to form a halftone type phase shift mask having the desired pattern of the halftone material film 2 ′ formed on the substrate 1 ( d). In this conventional method, Mo is applied between the halftone material film 2 and the resist film 3.
The reason why the metal film 4 is formed is to prevent the substrate 1 from being charged at the time of electron beam exposure and making the traveling path of the electron beam unstable.

In the method of manufacturing the halftone type phase shift mask shown in FIGS. 2 and 3, a laminated structure before a patterning process such as etching is performed on the resist film 3, for example, FIG. A laminated structure in which a halftone material film 2 is uniformly laminated on a transparent substrate 1 and a laminated structure in which a resist film 3 is further uniformly laminated thereon are generally called blanks. FIG.
The halftone material film 2 on the transparent substrate 1
A laminated structure in which Mo metal films 4 having the same etching characteristics are uniformly laminated, and a laminated structure in which a resist film 3 is further uniformly laminated thereon are generally called blanks.
This blank may itself be treated as one product.

[0009]

In the conventional method for manufacturing a halftone type phase shift mask described above, when the halftone material film 2 is etched using the resist film 3 'as a mask, the resist film 3' itself has an edge. Since the halftone material film 2 is etched from the side, the dimensional control of the halftone material film 2 is not accurately performed. As a result, there is a problem that the halftone material film 2 cannot be patterned with high accuracy. In addition, various chemicals such as an acid and an alkali may be used in each processing step from the film formation to the completion of the phase shift mask. However, the action of these chemicals causes a change in the characteristics of the halftone material film, which is desired. There has also been a problem that halftone characteristics cannot be obtained.

A method of manufacturing a halftone type phase shift mask according to the present invention has been made in order to solve the above-mentioned problems in the conventional manufacturing method, and is capable of selectively etching a halftone material film. It is an object of the present invention to provide a metal film on the halftone material film and to perform an appropriate process so that patterning of the halftone material film by etching can be performed with high dimensional accuracy.

By the way, in many cases, a blank for a conventional halftone type phase shift mask is a laminated structure in which a halftone material film is uniformly laminated on a transparent substrate, or a resist film is further uniformly formed thereon. It was a laminated structure. Since such a blank does not include a metal film layer that can be selectively etched with respect to the halftone material film, it is not suitable for the method of manufacturing a halftone phase shift mask according to the present invention.

A phase shift mask having a different structure from the phase shift mask manufactured by the method for manufacturing a halftone type phase shift mask according to the present invention is Cr.
It is advantageous to provide a light-shielding metal such as (chrome) or the like in a pattern on the halftone material film in a pattern to improve the light-shielding property of the light-shielding region of the halftone phase shift mask. When manufacturing such a halftone phase shift mask, a blank which does not include a metal film layer which can be selectively etched with respect to a halftone material film as in the related art is not appropriate.

[0013]

[0014]

Means for Solving the Problems A half toe according to the present invention
The method for manufacturing a phase shift mask is as follows.
(2) halftone
Selective etching for the halftone material film on the material film
A metal film that can be coated, and the metal film is formed of Cr, Cr
O, CrN, CrON
(3) A resist film is laminated on the metal film, and (4)
Patterning the dying film, (5) patterned
Etching the metal film using the resist film as a mask
Patterned, (6) patterned resist film
And halftone material film using metal film as mask
(7) Half-toning the metal film of the desired pattern
The resist film is stripped off while leaving it on the
Sign.

[0015]

[0016]

As the halftone material film, for example, Mo
Si-based materials, more specifically, for example, the chemical symbol Mo
A material represented by SiO _X N _Y (X and Y are integers) can be used.

The phrase "selective etching is possible" with respect to the metal film means that only the metal film is removed by etching without removing the halftone material film by etching. As a metal capable of such selective etching, for example, if a halftone material film is formed of a Mo.Si-based material, Cr (chromium), CrO (chromium oxide),
CrN (chromium nitride), CrON (chromium nitride oxide), or a composite film in which these are laminated can be employed. When a composite film is employed, a two-layer structure as shown in FIGS. 4 and 5 or a three-layer structure as shown in FIG. 6 can be employed.

The thickness of the metal film is, for example, 300 to 150.
Set to about 0 °. However, it is desirable that the metal film be formed to have a relatively small thickness. If the metal film is too thick, when the metal film itself is patterned by etching, it may not be possible to finish the metal film itself into an accurate shape due to the influence of so-called side etching. If the metal film is thin, the influence of side etching can be suppressed to a small degree, so that precise patterning can be performed.

The metal film can be formed by a known film forming method. For example, with respect to CrO, sputtering is performed in an atmosphere containing O ₂ with Cr as a target, for example, in a gas containing Ar as a main component and slightly containing O ₂ . CrN
With respect to the above, in an atmosphere containing N ₂ with Cr as a target, for example, in a gas containing Ar as a main component and slightly containing N ₂ ,
To perform sputtering. Regarding CrON, in an atmosphere containing O ₂ and N ₂ by targeting Cr, for example, A
Sputtering is performed in a gas containing r as a main component and some O ₂ and N ₂ .

[0021]

The halftone phase shift mass according to claim 1
In the method of manufacturing the mask, the resist is
And the resist film is exposed by electron beam exposure and development.
And then patterned.
Pattern the metal film into the desired pattern using the
Training. The metal film patterned as described above is used as a mask for patterning the halftone material film.

However, the form of use of the metal film is not limited to such a mask for a halftone material film, but can be used for any other purpose. For example, on a halftone phase shift mask, a main pattern which is a portion to be exposed as an image on an exposure target such as a wafer is formed. The exposure light naturally passes through the main pattern, but must not pass through other portions. The halftone material film originally has a function of blocking the passage of such exposure light, but by its nature, some of the exposure light passes through the halftone material film. Normally, such weak transmitted light is not light of a sufficient amount to expose a wafer or the like,
For some reason, this light is double, triple, quadruple.
If they overlap as in the above, there is a possibility that an area on the wafer which should not be exposed to light may be exposed. As described above, when it is considered that the weak light transmitted through the halftone material film overlaps on the wafer or the like, a portion of the halftone type phase shift mask where the transmitted weak light is considered to overlap on the wafer or the like. Preferably, a light-shielding layer is formed first. The metal film of the blank for a halftone shift mask according to the present invention can also be used as such a light shielding layer.

In the method for manufacturing a halftone type phase shift mask according to the first and second aspects, the halftone material film is etched using the patterned metal film as a mask, and the metal film is formed on the halftone material film. On the other hand, it is made of a material that can be selectively etched.
Therefore, the metal film is not removed by etching during the etching process on the halftone material film.
Therefore, the halftone material film can be etched with high dimensional accuracy, and as a result, a half-Hahn type phase shift mask with high dimensional accuracy can be obtained.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1A, a transparent substrate 1 made of quartz is formed on a transparent substrate 1 by using a known film forming method.
o.Si halftone material film 2, Cr as metal film
The film 5 and the resist film 3 were sequentially laminated to form a phase shift mask blank. The thicknesses of the respective films are as follows.
0 to 1500 °, and the resist film 3 is 3,000 to 60
00 °.

Next, a resist film 3 'having a desired pattern was formed by electron beam exposure and development (b). Further, using the resist film 3 'as a mask, a conventional wet etching using an etching solution prepared by adding perchloric acid to ceric ammonium nitrate, or a dry etching using a chlorine-based gas, The film 5 was patterned into a Cr metal film 5 'having a desired pattern (c). Since the Cr metal film 5 and the halftone material film 2 are formed of materials that can be selectively etched with each other,
When etching the Cr metal film 5, the halftone material film 2 is not etched.

Thereafter, the halftone material film 2 was patterned into a desired pattern of the halftone material film 2 'by dry etching using a fluorine-based gas such as CF ₄ or C ₂ F ₆ (d). At this time, since the Cr metal film 5 'serving as a mask was not etched, the pattern of the halftone material film 2' was obtained with extremely high dimensional accuracy.

Next, the resist film 3 ′ is peeled off using oxygen plasma or sulfuric acid, and the Cr metal film 5 is formed by a conventional wet etching using an etching solution prepared by adding perchloric acid to ceric ammonium nitrate. 'Peeled off. As a result, a halftone type phase shift mask including the halftone material film 2 ′ having the desired pattern was obtained (e). When this phase shift mask is used in a projection exposure apparatus such as a stepper, the exposure light R is irradiated from the transparent substrate 1 side, and an exposure target, for example, a wafer, which is arranged at a position facing the halftone material film 2 ′, A light image having a pattern corresponding to the halftone material film 2 'is exposed.

The pattern of the halftone material film 2 'of the halftone type phase shift mask thus obtained has been finished with extremely high dimensional accuracy. In the manufacturing process from step a to step e in FIG. 1, a cleaning process using an acid, an alkali, or the like is performed in an appropriate step. At the time of this cleaning, the presence of the Cr metal film 5 prevents the halftone material film 2 from changing its characteristics due to the influence of an acid, an alkali or the like.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the embodiments and can be variously modified within the technical scope described in the claims. For example, the usage of the blank for a halftone phase shift mask according to claim 1 or 2 is not limited to the method for manufacturing a halftone phase shift mask according to claim 5 or 6. For example, if the metal film of the blank according to claim 1 or 2 is selectively etched with respect to the halftone material film so that the metal film of a desired pattern is left on the halftone material film, A light-shielding layer having a desired pattern can be formed on the film.

[0030]

According to the method for manufacturing a halftone type phase shift mask according to the first and second aspects, the patterning of
The halftone material film is etched using the
The halftone material film to the desired pattern.
Patterning with high precision. Also contains Cr
The metal film is formed by a light-shielding metal such as
Metal film of a desired pattern by etching
Is left on the halftone material film, a halftone phase shift mask having a light-shielding layer of a desired pattern can be manufactured.

Furthermore, according to the manufacturing method of claims 1 and halftone phase shift mask according to claim 2, the halftone material film a metal film which is not etched by an etchant for the halftone material film as a mask Since patterning can be performed by etching, a halftone pattern with higher dimensional accuracy can be obtained as compared with a case where the halftone material film is directly etched using a resist as a mask. Further, since the halftone material film is covered with the metal film, it is possible to prevent the halftone material film from being changed in characteristics by a chemical.

[0032]

[Brief description of the drawings]

FIG. 1 is a view schematically showing a method for manufacturing a halftone phase shift mask according to the present invention.

FIG. 2 is a diagram schematically showing a conventional manufacturing method for a halftone type phase shift mask.

FIG. 3 is a diagram schematically showing another conventional manufacturing method for a halftone type phase shift mask.

FIG. 4 is a diagram showing a partial cross-sectional structure of one embodiment of a metal film.

FIG. 5 is a diagram showing a partial cross-sectional structure of another embodiment of the metal film.

FIG. 6 is a diagram showing a partial cross-sectional structure of still another embodiment of the metal film.

[Description of Signs] 1 Transparent substrate 2 Halftone material film 2 'Patterned halftone material film 3 Resist 3' Patterned resist film 5 Cr metal film 5 'Patterned Cr metal film

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-6-175346 (JP, A) JP-A-58-54633 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (2)

(57) [Claims] 1. A half-tone pattern of a desired pattern on a transparent substrate.
Half-tone phase shift mass formed with
In the method for producing a click, (1) the halftone material film laminated on the transparent substrate, (2) the halftone material film on the halftone material film
A metal film that can be selectively etched with respect to
The composite film consists of Cr, CrO, CrN and CrON laminated.
Is constituted by a membrane, (3) a resist film is laminated on the metal film, (4) a gold resist film is patterned, (5) the patterned resist film as a mask
Patterning the metal film by etching; (6) masking the patterned resist film and metal film;
The halftone material film is etched as a step, and (7) a metal film having a desired pattern is formed on the halftone material film.
Characterized in that the resist film is peeled off while leaving the
A method for manufacturing a tone-type phase shift mask. (2) 2. The outermost surface layer of the metal film according to claim 1,
Is characterized by being composed of CrO
A method of manufacturing a phase shift mask.