JP2003195474A - Phase shift mask blank and phase shift mask and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a phase shift mask blank which is small in the change in warpage before and after deposition and is small in the warpage of its surface, a phase shift mask obtained by forming a pattern to this phase shift mask blank and a method of manufacturing the same. <P>SOLUTION: The pattern is formed on the phase shift mask blank by dividing process steps for forming phase shift films to a process step of forming a foundation layer by sputtering and a process step of forming a surface layer by sputtering and setting the sputtering pressure in forming the foundation layer higher than the sputtering pressure in forming the surface film. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a phase shift mask blank and a phase shift mask used for manufacturing a semiconductor integrated circuit and the like and a manufacturing method thereof, and more particularly to a half for attenuating light having an exposure wavelength by a phase shift film. The present invention relates to a tone type phase shift mask blank, a phase shift mask, and manufacturing methods thereof.

[0002]

2. Description of the Related Art ICs,
Photomasks used in a wide range of applications including the production of semiconductor integrated circuits such as LSI and VLSI are basically photomask blanks having a light-shielding film containing chromium as a main component on a transparent substrate. A predetermined pattern is formed on the light shielding film by applying a photolithography method and using ultraviolet rays or electron beams. In recent years, pattern miniaturization has rapidly progressed in response to market demands such as higher integration of semiconductor integrated circuits, and this has been addressed by shortening the exposure wavelength.

However, while shortening the exposure wavelength improves the resolution, it causes a decrease in the depth of focus, which lowers the process stability and adversely affects the yield of products.

A phase shift method is one of the pattern transfer methods effective for such problems, and a phase shift mask is used as a mask for transferring a fine pattern.

This phase shift mask (halftone type phase shift mask) is, for example, as shown in FIGS. 6A and 6B, a phase shifter section (second phase shifter) having a pattern formed on a substrate. As shown in FIG. 6B, there is a light transmitting portion) 2a and a substrate exposed portion (first light transmitting portion) 1a where the phase shift film does not exist. By setting the angle to 180 °, the light intensity at the interfering portion becomes zero due to the light interference at the pattern boundary portion, and the contrast of the transferred image can be improved. Further, by using the phase shift method, it is possible to increase the depth of focus for obtaining the necessary resolution, and compared with the case of using a normal mask having a general light shielding pattern made of a chrome film, It is possible to improve the resolution and the margin of the exposure process.

The above-mentioned phase shift mask can be roughly divided into a complete transmission type phase shift mask and a halftone type phase shift mask in practical use, depending on the light transmission characteristics of the phase shifter portion. The complete transmission type phase shift mask is a mask in which the light transmittance of the phase shifter portion is the same as that of the exposed portion of the substrate and is transparent to the exposure wavelength. In the halftone type phase shift mask, the light transmittance of the phase shifter portion is about several percent to several tens percent of the exposed portion of the substrate.

FIG. 4 shows the basic structure of a halftone type phase shift mask blank, and FIG. 5 shows the basic structure of a halftone type phase shift mask. The halftone phase shift mask blank shown in FIG. 4 has a halftone phase shift film 2 formed on almost the entire surface of a transparent substrate 1. Also, FIG.
The halftone type phase shift mask is a patterned one of the above-mentioned phase shift film 2, and the light transmitted through the phase shifter portion 2a forming the pattern portion on the substrate 1 is different from the light transmitted through the substrate exposed portion 1a. The phase shift is performed, and the transmittance of the phase shifter portion 2a is set to a light intensity that does not expose the resist on the transfer substrate. Therefore, it has a light blocking function of substantially blocking the exposure light.

As the halftone type phase shift mask, there is a single layer type halftone type phase shift mask which has a simple structure and is easy to manufacture. This single-layer halftone phase shift mask is disclosed in Japanese Patent Application Laid-Open No. 7-140635.
Those having a phase shifter made of a MoSi-based material such as MoSiO and MoSiON described in Japanese Patent Publication have been proposed.

The phase shift film is usually formed by sputtering. When the phase shift film is formed, stress is generated as the film grows, which distorts the transparent substrate, resulting in a phase shift mask blank to be obtained. Warpage occurs.
When a phase shift mask is manufactured by patterning this phase shift mask blank, stress is released after patterning the phase shift film, so that the warp of the substrate returns to the state before film formation to some extent, and the flatness of the substrate changes. (Fig. 2
reference). Due to this change, the size of the pattern changes between the design at the time of pattern exposure and the actually completed mask. This dimensional change has a greater effect as the mask pattern becomes finer. Therefore, a phase shift mask blank formed with a phase shift film having a small film stress, that is, a change in warp before and after film formation is small, and a surface warp is small. A phase shift mask has been desired.

The present invention has been made to solve the above problems, and is a phase shift mask blank that provides a photomask with high pattern accuracy, that is, the change in warp before and after film formation is small and the surface warp is small. It is an object of the present invention to provide a phase shift mask blank, a phase shift mask formed by forming a pattern on the phase shift mask blank, and a manufacturing method thereof.

[0011]

Means for Solving the Problems and Modes for Carrying Out the Invention The present inventors have conducted extensive studies to solve the above problems, and as a result, when the phase shift film is formed on the substrate by sputtering, the sputtering pressure is controlled. When it is formed high, the stress is relieved and the warp can be reduced, that is, by forming the phase shift film with a small film stress on the substrate with a small warp, the warp can be achieved without changing the size of the warp of the substrate. It was found that a phase shift mask blank having a small value can be obtained.

However, the above-mentioned phase shift film has lower chemical resistance (acid resistance) than the film formed by lowering the sputtering pressure. , The step of forming the underlayer by sputtering and the step of forming the surface layer by sputtering, and by making the sputtering pressure during formation of the underlayer higher than the sputtering pressure during formation of the surface layer, the phase shift film We found that it is possible to obtain a phase shift mask blank with a small change in warp and a small surface warp while maintaining the chemical resistance (acid resistance) of By doing so, it was found that a highly accurate phase shift mask with little change in pattern dimension can be obtained,
The present invention has been completed.

That is, the present invention provides the following phase shift mask blank, phase shift mask, and manufacturing method thereof.

A first aspect of the present invention is a phase shift mask blank in which a phase shift film is formed on a substrate which is transparent to exposure light and has a surface warp of 0.5 μm or less. A warp afterwards is 1.0 μm or less, a phase shift mask blank. Claim 2: The phase shift mask blank according to claim 1, wherein the phase shift film is made of a metal silicide oxide, a metal silicide nitride, or a metal silicide oxynitride. Claim 3: The phase shift mask blank according to claim 2, wherein the phase shift film is made of molybdenum silicide oxide, molybdenum silicide nitride or molybdenum silicide oxynitride. (4) The phase shift mask blank according to any one of (1) to (3), wherein the phase shift film comprises an underlayer and a surface layer. (5) A phase shift mask, wherein the phase shift film of the phase shift mask blank according to any one of (1) to (4) is patterned. Claim 6: Transparent to exposure light and having a surface warp of 0.5
5. A method of manufacturing a phase shift mask blank in which a phase shift film is formed on a substrate of .mu.m or less, wherein the phase shift film is formed by sputtering. Item 2. A method for manufacturing a phase shift mask blank according to the item. Claim 7: Transparent to exposure light and having a surface warp of 0.5
A method of manufacturing a phase shift mask blank, comprising forming a phase shift film consisting of an underlayer and a surface layer on a substrate having a thickness of not more than μm, the underlayer and the surface layer being formed by sputtering, and the underlayer being the surface layer. The method for manufacturing a phase shift mask blank according to claim 4, wherein the phase shift mask blank is formed at a higher sputtering pressure. [8] The method of manufacturing a phase shift mask blank according to [7], wherein the sputtering pressure of the underlayer is 1.2 times or more the sputtering pressure of the surface layer. Claim 9: A resist pattern is formed on the phase shift film of the phase shift mask blank according to any one of claims 1 to 4 by a photolithography method, and then the resist film of the phase shift film is not covered by an etching method. A method for manufacturing a phase shift mask, which comprises removing a portion and then removing the resist film.

The present invention will be described in more detail below. As shown in FIG. 1, the phase shift mask blank of the present invention is provided with a phase shift film 2 on a substrate 1 such as quartz, CaF ₂ or the like having a warp of 0.5 μm or less through which exposure light is transmitted, by using a sputtering apparatus. The film is formed, and the warp after the film formation is 1.0 μm or less, preferably 0.5 μm or less, and more preferably 0.3 μm or less. As the phase shift film, particularly, as shown in FIG.
And a surface layer 2 ″ are preferred.

The term "warp" as used herein means the difference between the maximum value and the minimum value of the surface height (P-V value) with the least squares plane as a reference plane, which is calculated from all the measurement point data of the surface height without adsorption. 2 in the case of a phase shift mask blank.
(Shown in (B)). In FIG. 2, 1 is a substrate,
2 indicates a phase shift film.

Regarding the phase shift film, metal silicide oxide, metal silicide nitride or metal silicide oxynitride, especially molybdenum silicide oxide (MoSi).
O), molybdenum silicide nitride (MoSiN) or molybdenum silicide oxynitride (MoSiON).

Further, the phase shift mask of the present invention is formed by patterning the phase shift film of the above-mentioned phase shift mask blank, and as shown in FIG. 3, there is a space between the patterned phase shifter portions. The first light transmitting portion 1a (substrate exposed portion) and the patterned phase shifter portion 2 become the second light transmitting portion 2a.

As shown in FIG. 1, the phase shift film is formed by forming a base layer 2'on a transparent substrate 1 having a warp of 0.5 μm or less by sputtering, and then forming a surface layer on the transparent substrate 1 by sputtering. A film can be formed by forming 2 ″. in this case,
The sputtering pressure when forming the underlayer is set higher than the sputtering pressure when forming the surface layer. The underlayer 2'obtained by increasing the sputtering pressure has a small stress generated by the growth of the film, and the sputtering pressure is lowered on the underlayer 2'to provide a surface layer having high chemical resistance (acid resistance). Since the stress does not increase much even when formed, it is possible to obtain a phase shift mask blank having high chemical resistance, a small change in warpage, and a small surface warpage.

The sputtering pressure at the time of forming the surface layer varies depending on the required phase shift film characteristics such as chemical resistance of the surface, but is preferably 0.1 to 0.5 Pa. If it is lower than 0.1 Pa, discharge may not occur during sputtering, and if it is higher than 0.5 Pa, chemical resistance may be reduced.

The sputtering pressure at the time of forming the underlayer varies depending on the desired characteristics of the phase shift film, the required amount of change in warpage, etc., but is 1.2 times or more the sputtering pressure at the time of forming the surface layer. In particular, it is preferable to make it twice or more. If it is less than 1.2 times, the relaxation of the film stress becomes insufficient, and the warp of the obtained phase shift mask blank may not be reduced.

Further, the underlayer may be composed of two or more layers. In this case, if the sputtering pressure at the time of forming the underlying layer of the lower layer is made higher than that of the upper layer, it is more effective in relaxing the film stress, and a phase shift mask blank with a smaller amount of change in warp can be obtained. In addition, the same effect may be obtained by continuously changing the film forming conditions from the base layer to the surface layer during sputtering.

In the above, the phase shift mask blank is shown in which the phase shift film is composed of two layers of the underlayer and the surface layer, but the present invention is not limited to this, and it is composed of one layer of the phase shift film. May be. In this case, the sputtering pressure at the time of forming the phase shift film is 0.5 Pa or more, and particularly, 0.
It is preferably 8 Pa or more.

Although the thickness of the phase shift film varies depending on the exposure wavelength when the phase shift mask is used, the transmittance of the phase shift layer, the amount of phase shift, etc., it is usually 50 to 170 n.
m, particularly 70 to 120 nm is preferable, and when the phase shift film is separately formed into the underlayer and the surface layer, the thickness of the underlayer is 5 to 90 times the thickness of the phase shift film.
%, In particular 10-80%, especially 20-70% is preferred. If it is less than 5%, the relaxation of the film stress becomes insufficient, and the warp of the obtained phase shift mask blank may not be reduced in some cases, and if it exceeds 90%, the surface layer is thin,
There is a possibility that sufficient chemical resistance (acid resistance) may not be obtained.

The method for forming the phase shift film of the present invention (that is,
As a method for forming the underlayer and the surface layer), a reactive sputtering method is preferable, and in the case of forming a metal silicide oxide, a metal silicide nitride, or a metal silicide oxynitride on the sputtering target, the metal is used. A metal silicide target containing is used. In particular, a molybdenum silicide target is used when forming a film of molybdenum silicide oxide, molybdenum silicide nitride, or molybdenum silicide oxynitride.
Furthermore, in order to keep the composition of the film constant, either oxygen or nitrogen, or a metal silicide added by combining them may be used.

In the present invention, the sputtering method is
A DC power supply or a high frequency power supply may be used, and the magnetron sputtering method or the conventional method may be used. The film forming apparatus may be either a passage type or a single wafer type.

The composition of the sputtering gas is argon,
The film is formed by appropriately adding an inert gas such as xenon, nitrogen gas, oxygen gas, various nitrogen oxide gases, etc. so that the phase shift film to be formed has a desired composition.

In the present invention, the sputtering pressure can be increased or decreased by increasing the addition amount of the inert gas. However, if necessary, oxygen serving as an oxygen source or a nitrogen source forming the film is formed. The amount of gas containing nitrogen and nitrogen can be increased or decreased.

When it is desired to increase the transmittance of the phase shift film to be formed, a method of increasing the amount of gas containing oxygen or nitrogen to be added to the sputtering gas so that a large amount of oxygen or nitrogen is taken into the film, It can be adjusted by a method using a metal silicide in which a large amount of oxygen or nitrogen is added to the sputtering target in advance.

Further, a Cr-based light-shielding film is provided on the phase shift film, or C for reducing reflection from the Cr-based light-shielding film.
It is also possible to form the r-based antireflection film on the Cr-based light-shielding film.

In this case, as the Cr-based light-shielding film or the Cr-based antireflection film, it is preferable to use a film formed of chromium oxycarbide (CrOC), chromium oxynitride carbide (CrONC), or a laminate of these films.

Such a Cr-based light-shielding film or a Cr-based antireflection film is, for example, chromium alone, or chromium, oxygen, nitrogen,
It is possible to form a film by reactive sputtering using a sputtering gas in which carbon dioxide gas is added to an inert gas such as argon or krypton using a chromium compound added with any of carbon or a combination thereof as a target. it can.

The phase shift mask of the present invention can be obtained by patterning the phase shift film of the phase shift mask blank obtained as described above.

Specifically, when manufacturing a phase shift mask, a phase shift film is formed on a substrate as described above, a resist film is further formed, and the resist film is patterned by a lithography method. A method of removing the resist film after etching the phase shift film can be adopted. In this case, application of the resist film, patterning (exposure, development), etching, and removal of the resist film can be performed by known methods.

A Cr-based light-shielding film and / or a Cr-based antireflection film (hereinafter collectively referred to as Cr-based film) is formed on the phase shift film.
When the film is formed, the light-shielding film and /
Alternatively, the antireflection film is removed by etching, the phase shift film is exposed on the surface, and then the phase shift film is patterned in the same manner as above to obtain a phase shift mask in which the Cr-based film remains on the outer peripheral portion of the substrate. be able to. Also,
A resist is applied on the Cr-based film, patterning is performed, the Cr-based film and the phase shift film are patterned by etching, and only the Cr-based film in the region necessary for exposure is removed by selective etching to perform the phase shift. It is also possible to expose the pattern on the surface to obtain a phase shift mask.

[0036]

EXAMPLES The present invention will be specifically described below by showing Examples and Comparative Examples, but the present invention is not limited to the following Examples.

[Examples 1 to 4 and Comparative Example 1] By using molybdenum silicide as a target and sputtering on a 6025 synthetic quartz substrate (6 × 6 × 0.25 inch) under the conditions shown in Table 1 by the magnetron method. A base layer was formed, and then the conditions were changed as shown in Table 1 to form a surface layer to obtain a phase shift mask blank having a phase shift film made of MoSiON. Table 1 shows the layer thickness of each underlayer and surface layer.

The amount of change in warpage of the obtained phase shift mask blank before and after the formation of the phase shift film and the acid resistance of the phase shift film were evaluated by the following methods. The results are also shown in Table 1.

Evaluation method Warp change amount: The warp before and after the formation of the phase shift film was measured by a warp measuring device (FT-900 manufactured by NIDEK) to 142 mm.
It measured in the range of x142 mm, and calculated the amount of change in the warpage before and after film formation. Acid resistance: After measuring the phase difference of the phase shift mask blank on which the phase shift film is formed, the phase difference is measured again after being immersed in concentrated sulfuric acid heated to 100 ° C. for 2 hours, and the amount of change in phase difference before and after immersion. Was calculated.

[0040]

[Table 1]

In the above table, the warp change amount is the maximum value of the change in height before and after film formation at each measurement point from the least square plane which is the reference surface, and the warp of the substrate and the phase shift mask blank. It is different from the simple difference from warpage.

As is clear from Table 1, the phase shift mask blank of the present invention has a small warp and a small amount of change in the warp before and after film formation.

[0043]

According to the present invention, a phase shift mask blank having a small change in the warp before and after film formation and a small surface warp can be obtained. By forming a pattern on the phase shift mask blank, the warp can be prevented. It is possible to suppress the variation of the pattern dimension due to the change and to obtain a highly accurate phase shift mask.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a phase shift mask blank according to an embodiment of the present invention.

2A and 2B are explanatory diagrams of warpage of a phase shift mask blank, FIG. 2A is a substrate before a phase shift film is formed, FIG. 2B is a phase shift mask blank on which a phase shift film is formed, and FIG.
Represents a phase shift mask after pattern formation.

FIG. 3 is a sectional view of a phase shift mask according to an embodiment of the present invention.

FIG. 4 is a sectional view of a conventional phase shift mask blank.

FIG. 5 is a sectional view of a conventional phase shift mask.

6A and 6B are diagrams illustrating the principle of the halftone phase shift mask, and FIG. 6B is a partially enlarged view of the X portion of FIG.

[Explanation of symbols]

1 substrate 1a Board exposed part 2 Phase shift film 2'underlayer 2 ″ surface layer 2a Phase shifter section

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hideo Kaneko             28-1 Nishifukushima, Kubiki Village, Nakakubiki District, Niigata Prefecture             Shin-Etsu Chemical Co., Ltd.Research on new functional materials technology             In-house (72) Inventor Satoshi Tsukamoto             28-1 Nishifukushima, Kubiki Village, Nakakubiki District, Niigata Prefecture             Shin-Etsu Chemical Co., Ltd.Research on new functional materials technology             In-house (72) Inventor Masataka Watanabe             28-1 Nishifukushima, Kubiki Village, Nakakubiki District, Niigata Prefecture             Shin-Etsu Chemical Co., Ltd.Research on new functional materials technology             In-house (72) Inventor Satoshi Okazaki             28-1 Nishifukushima, Kubiki Village, Nakakubiki District, Niigata Prefecture             Shin-Etsu Chemical Co., Ltd.Research on new functional materials technology             In-house F term (reference) 2H095 BB03

Claims (9)

[Claims] 1. A phase shift mask blank obtained by forming a phase shift film on a substrate which is transparent to exposure light and has a surface warp of 0.5 μm or less. A phase shift mask blank having a warp of 1.0 μm or less. 2. The phase shift mask blank according to claim 1, wherein the phase shift film is made of metal silicide oxide, metal silicide nitride or metal silicide oxynitride. 3. The phase shift film is made of molybdenum silicide oxide, molybdenum silicide nitride or molybdenum silicide oxynitride.
The described phase shift mask blank. 4. The phase shift mask blank according to claim 1, wherein the phase shift film comprises an underlayer and a surface layer. 5. A phase shift mask, wherein the phase shift film of the phase shift mask blank according to claim 1 is patterned. 6. A method of manufacturing a phase shift mask blank, which comprises forming a phase shift film on a substrate which is transparent to exposure light and has a surface warp of 0.5 μm or less, wherein the phase shift film is sputtered. 5. The method for manufacturing a phase shift mask blank according to claim 1, wherein the film is formed by the following method. 7. A method of manufacturing a phase shift mask blank, which comprises forming a phase shift film composed of an underlayer and a surface layer on a substrate which is transparent to exposure light and has a surface warp of 0.5 μm or less. The method of manufacturing a phase shift mask blank according to claim 4, wherein the underlayer and the surface layer are formed by sputtering, and the underlayer is formed at a higher sputtering pressure than the surface layer. 8. The method of manufacturing a phase shift mask blank according to claim 7, wherein the sputtering pressure of the underlayer is 1.2 times or more the sputtering pressure of the surface layer. 9. The phase shift mask blank according to claim 1, wherein a resist pattern is formed on the phase shift film of the phase shift mask blank by photolithography, and then a resist film of the phase shift film is formed by etching. A method of manufacturing a phase shift mask, which comprises removing a covered portion and then removing a resist film.