JPS5969929A - Method for manufacturing masks for X-ray lithography - Google Patents

Abstract

PURPOSE:To prevent the coating of Ni, etc. onto a resist pattern, and to form an X-ray absorber of high quality on a mask substrate through electroless plating by making the surface of the resist pattern hydrophobic and attaching a catalyst. CONSTITUTION:The polished surface of the Si single crystalline substrate 1 is coated with Si3N4 2 and BN 3, the resist pattern 4 is formed, and the resist 4 is also applied on the whole back. The resists 4 are photo-inactivated through heat treatment, and the resists 4 are made hydrophobic completely through CF4 plasma treatment. The whole is dipped in a catalyst liquid for electroless Ni plating, the catalyst is attached, and a Ni film 5 is formed on the substrate through Ni electroless plating. The resists 4 are removed, and Si 1 is etched while leaving a peripheral section. Since the resist patterns and a resist film on the back do not moisten with the catalyst liquid, a phenomenon in which the side surfaces of the resist are coated with the Ni film by an electric capillarity can be prevented, and an absorption pattern consisting of the Ni film conforming to the resist pattern can be formed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a method for manufacturing a mask for X-ray phosphorography;
More specifically, the present invention relates to a method of forming an absorber pattern in an X-ray mask used in soft X-ray lithography.

[Prior art]

Conventionally, Au and W have been used as absorber elements for the X-ray absorption pattern of X-ray phosphorography masks.

Heavy metals such as PB are used. However, according to the studies of the present inventors, in a certain limited X-ray wavelength range, light metals such as Ni also have X-ray absorption coefficients comparable to those of the conventionally used heavy metals, and these metals also have It has become clear that it can be used as an X-ray absorber like heavy metals.

There are roughly two types of absorber pattern formation.

One method is ion milling, reactive sputter etching, etc., in which a resist pattern is formed on an absorber layer previously formed on the entire surface of a mask substrate, and this is selectively ion milled as a protective film for ion milling, etc. etc.,
This is a method for forming a desired absorbent layer. The second method is plating, which includes electrolytic and electroless coating methods. In this case, a resist pattern is formed on the substrate in advance, plated on it, and Ni or the like is deposited on the portions where the resist film is not deposited to form an absorber pattern. be.

Of the two methods mentioned above, the plating method, especially the electroless plating method, is superior in terms of ease of operation and accuracy of the absorber and pattern formed, but the electroless plating method also has the following problems. However, practical application has been delayed.

Conventionally, to form an absorber pattern by electroless plating, polyimide and polycrystalline Si are deposited on an SJ wafer.

Using a mask thin film such as 8jsN+, a resist film is formed on this, and a resist pattern with a minimum thickness of 0.5 μm is formed by 1/10 reduction projection method or electron beam direct writing method, and the entire back side is coated with resist. , the Si surface should not be exposed.

A catalyst is applied to the exposed surface by immersing it in a solution (for example, H8l0IB manufactured by Hitachi Chemical Co., Ltd.), followed by washing with water, and then applying a non-4-carbon solution containing nickel sulfate and sodium citrate as main components.
It was plated at 80C±10C using 1PI' plating solution. At this time, since the plating solution had a pH of 1 BIJ tl, sulfurized ammoformium, aqueous ammonia, and the following sodium hydrogen phosphate were added as a reducing agent.

In this method, ■ Since the electroless plating catalyst remains on the resist pattern, there is a serious risk that absorbers such as Ni may be plated on the resist as well. To avoid this, the plating conditions must be limited to a narrow range. Therefore, (1) it is necessary to strictly control the plating conditions (pH, temperature, plating time), which has the disadvantage of making the process complicated.

It is clear that in order to eliminate this drawback, it is sufficient to form a resist pattern after performing catalyst impregnation with no <4 plating to prevent the catalyst from adhering onto the resist pattern. However, during processes such as resist application, exposure, development, and heat treatment, the previously applied catalyst tends to deactivate or flow out, and this causes the formation of a high-quality plating layer. It was difficult.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks and to provide a method for forming a high quality X-ray absorber on a mask substrate by non-straight plating.

[Summary of the invention]

In order to achieve the above object, the present invention impregnates a plating catalyst after depositing a hydrophobic resist pattern,
The catalyst is selectively attached only to the mask thin film to prevent Ni and the like from adhering to the resist pattern.

[Embodiments of the invention]

As described above, the present invention prevents Ni and the like from adhering to the resist pattern by making the surface of the resist pattern hydrophobic and adhering a catalyst thereto.

The above-mentioned hydrophobization treatment can be performed, for example, by plasma of a fluorine-containing compound (such as Cp4).

To actual 16 t211 As shown in Fig. 1(a), (100) Si single crystal substrate l
100% each of 5jsN42 and BH3 on the polished surface of
0 people, 1 μm deposited. S js N4 m 2 is C
VD method, BNjJ process 3 was formed by sputtering iA' layer method.

A resist butter/4 with a thickness of 1.2 μm made of a positive novolac resist (product name AZ1350J, Shipley Co., Ltd.) was applied using a normal resist process as shown in Figure 2.
It was formed as shown in b). At this time, resist 4 is also applied to the back side.
was applied to the entire surface. After performing heat treatment in air for 130 tl'-1 h to activate the resist 4 for light years, CF4 plasma treatment was performed. For CF4 plasma treatment, a barrel-type plasma generator is used, and the CF4 gas pressure is 0.5'.
The treatment was carried out for 3 minutes under the conditions of 1'orr and a plasma output of 100W.

This treatment completely rendered the resist 4 hydrophobic.

This is a one-component electroless Ni plating catalyst solution (product name: H8).
-101B (manufactured by Hitachi Chemical, except for the surfactant), and a catalyst was attached thereto. Thereafter, a 1 μm thick Ni film 5 was formed on the substrate by N1 non-thread plating. This state is shown in FIG. 1(C).

After removing the two resists j4 on the front and back surfaces by oxygen plasma treatment, the Si1
BNNa35isNa is etched from the back side.
Using the film 2 as a support film, an X-ray mask having an absorption pattern 5 made of a Ni absorber was formed on the BN film 3. This state is shown in FIG. 1(d).

According to this embodiment, when the catalyst is attached, the resist pattern and the resist film on the long surface are not wetted by the catalyst liquid due to the hydrophobic treatment by plasma, so the catalyst is not attached onto the resist. Moreover, since it does not get wet with the plating solution during electroless plating, Ni
It was also possible to prevent the film from adhering to the side surfaces of the resist, and it was possible to form an absorption pattern made of the Ni film that was faithful to the resist pattern. Figure 2 shows how the plating film adheres to one surface of the resist due to the electrocapillary phenomenon (based on a successful example). As a result, the edge of the plating film may become cracked, or in the worst case, adjacent plating films may become connected to each other. In the case of the resist 22', the formation of the plating film on the side surfaces of the resist is prevented, so that an absorber pattern with a good shape can be formed.
The thickness distribution of the m-thick Ni film is ±5 within the plane of the substrate with a diameter of 75 mm.
It was also confirmed that the film thickness uniformity characteristic of electroless plating was not impaired at all by the CF4 plasma treatment of the resist. In this embodiment, the resists on both sides were removed, but it is also possible to remove only the back side resist and leave the front side resist before etching the Si substrate.

Example 2 This example shows a case where Au is used as the main component of the absorber. First, the resist pattern was selectively hydrophobicized in the same manner as in Example 1 (Fig. 1(b)).
.

After this substrate was immersed in a one-component non-oxidizing Ni plating catalyst solution and a catalyst was attached thereto, a 0.1 μm thick Ni film was formed on the exposed portion of the BN film 3 by Ni electroless plating. After washing with water, it was further immersed in an Au electroless plating solution (trade name: Leftroless Au9, manufactured by Nippon Electroblating Co., Ltd.) to form a 0.6 μm thick Au film on the previously formed Ni film. The plating conditions in this case were a temperature of 75C and 1) H=10.0. After that, the resist was removed in the same manner as in Example 1, and S
Etching was performed from the back surface of the central part of the i-substrate, and an X-ray mask having an absorber pattern made of a laminated film of an Au film and a Ni film was formed on the BN film 3, using the BN film 3SjsN4 film 2 as a support film.

In the case of this example, as in Example 1, due to the effect of the CF4 plasma treatment, ■ there is no adhesion of Ni and Au on the resist, and ■ even in the case of a pattern of 1 μm or less, Ni and Au are deposited on the resist.
The film did not adhere to the side surfaces of the resist, and a laminated film of Au and Ni faithful to the resist pattern could be formed.

In addition, the film thickness uniformity is 7 mm in diameter in the case of electrolytic Au plating.
It was difficult to achieve a value of ±10% or less within the substrate surface between 5 and 5, but in this example, it was possible to achieve a value of ±5% or less, and the feature of tS-free plating is that Ni It became clear that there was no damage at all, just like the plating.

Example 3 In this example, a Ni absorber pattern was formed by the same process as in Example 1, but the plating catalyst was applied using a two-liquid type process instead of a one-liquid type process. For catalyst treatment, 5nCt2 aqueous solution (trade name: Pink Schumer,
Treatment with a PdCZ2 aqueous solution (trade name: Red Schumer, manufactured by Nippon Kanigen Co., Ltd.) and washing with water were performed. In this case as well, CF, s
The effect of hydrophobic treatment of resist using plasma is 1.
A Ni absorber pattern with a high nitric content was formed without any Ni film adhering to the side surfaces of the resist, which was completely the same as when a liquid catalyst solution was used.

Example 4 In Examples 1 to 3, CF4 gas was used as the fluorine-containing carbon compound gas, but in this example, a gas other than CF4 was used for hydrophobization treatment.

The gases used were CC15F, CCl2F2. CCI-Fz
It is CClFz. The plasma generation conditions were the same as in Example 1. SEM of Ni-plated pattern shows hydrophobic effect.
(scanning electron microscope) observation results are used as a practical scale.

As shown in Table 1, in the case of CCAsF, which has a low fluorine content, the hydrophobicity of the resist was somewhat insufficient after 3 minutes of treatment, but the hydrophobicity of the resist was obtained with no practical problems after 5 minutes of treatment. In the case of other gases, sufficient hydrophobization was achieved in the same treatment time as with CF4.

Table 1 Example 5 In Examples 1 to 4, a resist subjected to hydrophobic treatment was used for the plating process, but when the resist itself was hydrophobic, fluorine-containing carbon compound gas was used. Even without plasma treatment, the same effect can be obtained as with plasma treatment. Honta. FBM is a compound having a structural formula of 0-CsFeCHs, and has 96 fluorine atoms per monomer, making it an extremely hydrophobic polymer.

In this example, a substrate was prepared in the same manner as in Example 1, an FBM film with a thickness of 1.2 μm was formed on it, a pattern was drawn using an electron beam exposure method, and a methyl isobutyl ketone/isopropanol solution was used. A further development process was performed to form a resist pattern.

Next, heat t4 after impregnating the catalyst using a one-component catalyst liquid.
Ni plating was performed. Due to the strong hydrophobicity of the F'BM film, the catalyst was hardly attached to the resist pattern, and as a result, a good Ni absorber layer similar to that in Example 1 could be formed.

It has been confirmed that even if a resist pattern is formed using a hydrophobic resist according to this example, the same effect as gas plasma treatment using a fluorine-containing carbon compound is obtained.

Since this embodiment does not perform plasma treatment, it has the feature that it can be applied to an organic film such as polyimide as a transmission film of an X-ray mask.

Needless to say, gold that has been made hydrophobic may also be used.

〔Effect of the invention〕

As described above, according to the present invention, a mask for X1 condylar lithography having a fine pattern of 1 μm or less can be created with high coverage by non-layer plating, and its The effect is strong.

In addition, in the example, B on the absorber pattern gold 8ii plate
Although the case where it is formed on a laminated film of NM and Si3N4 film has been described, it goes without saying that the present invention is not limited to such a case, and the same effect can be obtained in the case of other materials and structures. It is clear that there is. Furthermore, in the above example, the case where Nr and hu were used as the absorber metal was shown, but it is clear that the same effect can be obtained in the case of electroless plating in which a material other than these metals is used for the absorber. .

In the above explanation, for convenience, the absorber is formed by electroless plating, but since the present invention uses a hydrophobic resist to prevent the electrocapillary phenomenon, electroless plating is also used in the case of electrolytic plating. It is clear that the effect is similar to that of plating.

Therefore, even if electrolytic plating is used as the plating in the present invention, a fine absorber pattern can be formed with high precision, and a good mask for xm lightning can be formed.

[Brief explanation of the drawing]

FIG. 1 is a process diagram for explaining a simple case of the present invention, and FIG. 2 is a sectional view showing the effects of the present invention. ■...3i substrate, 2...5jsN4 thin film, 3.
...BN thin film, 4...resist pattern, 5...N
i plating film, 21...substrate, 22...resist, 2
2'...Resist subjected to hydrophobization treatment, 23...Plated film. Figure 1 'l, 2? ? 3 Gogo? 3 1 111-z” ~zz’

Claims (1)

[Claims] 1. A step of forming a hydrophobic resist pattern having a desired shape on an Xa transparent film formed on a substrate, and forming an X-ray absorber on the exposed portion of the Xa transparent film. A method for manufacturing a mask for Xm lithography, comprising a step of selectively depositing the mask by plating. 2. The method for manufacturing an X-ray lithography mask according to claim 1, wherein the plating is electroless plating or electrolytic plating. 3. The method of manufacturing a mask for X-ray IJ lithography according to claim 1 or 2, wherein the hydrophobic resist pattern is formed by treating a hydrophilic resist with fluorine-containing plasma. 4. The hydrophobic resist pattern is formed from a hydrophobic resist. Method of manufacturing a ring graphite mask.