JPH11236686A - Dry etching method and production of x-ray mask - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a dry etching method capable of easily manufacturing patterns having extremely high perpendicularity with good reproducibility even in design rule of 0.1 μm and a process for producing an X-ray mask, etc. SOLUTION: This dry etching method consists in executing dry etching while forming a protective film to hinder the progression of the etching on pattern flanks on the pattern flanks at the time of forming the pattern by dry etching of a thin-film consisting essentially of tantalum or the like. A substrate stage 21 having a portion 21a consisting of a solid material for forming the protective film together with the substrate 27 to be etched which has the thin film as mentioned above is arranged within the dry etching apparatus and the dry etching of the above-mentioned thin film is executed. The dry etching is executed while the protective film is formed on the pattern flanks by depositing the reactant of the solid material for forming the protective film and an etching gas on the pattern flanks.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a dry etching method, an X-ray mask manufacturing method, and the like.

[0002]

2. Description of the Related Art Conventionally, in the semiconductor industry, as a technique for transferring a fine pattern necessary for forming an integrated circuit having a fine pattern on a silicon substrate or the like, a fine pattern using visible light or ultraviolet light as an exposure electromagnetic wave is used. Photolithography techniques for transferring patterns have been used.

However, in recent years, with the advancement of semiconductor technology, the integration of semiconductor devices such as VLSIs has been remarkably advanced, and high precision exceeding the transfer limit of visible light or ultraviolet light used in the conventional photolithography method has been used. The technology for transferring fine patterns has been required.

[0004] In order to realize the transfer of such a fine pattern, the development of an X-ray lithography method using X-rays having a shorter wavelength than visible light or ultraviolet light has been promoted.

FIG. 1 shows the structure of an X-ray mask used for X-ray lithography.

As shown in FIG. 1, an X-ray mask 1 comprises an X-ray transmitting film (membrane) 12 for transmitting X-rays, and an X-ray absorber pattern 13a for absorbing X-rays.
These are a support substrate (support frame) 11a made of silicon.
Supported by.

FIG. 2 shows the structure of an X-ray mask blank.
The X-ray mask blank 2 includes an X-ray transmission film 12 and an X-ray absorber film 13 formed on a silicon substrate 11.

As the X-ray transmitting film, silicon carbide or the like having a high Young's modulus and excellent resistance to X-ray irradiation is generally used, and the X-ray absorbing film is excellent in X-ray irradiation. An amorphous material containing Ta having a high resistance is often used.

As a process for manufacturing the X-ray mask 1 from the X-ray mask blank 2, for example, the following method is used.

A resist film having a desired pattern formed thereon is arranged on the X-ray mask blank 2, and dry etching is performed using the resist pattern as a mask to form an X-ray absorber pattern. Thereafter, the film in the region of the X-ray transmission film formed on the back surface located in the window area (back surface concave portion) is removed by reactive ion etching (RIE) using CF ₄ or Cl ₂ as an etching gas, and the remaining film is removed. Using the resulting film as a mask, the X-ray mask 1 is obtained by etching the back surface of the silicon substrate with an etching solution comprising a mixture of hydrofluoric acid and nitric acid.

In this case, an electron beam (EB) resist is generally used as a resist, and pattern formation (exposure) is performed by an EB drawing method.

When patterning an X-ray absorber film,
The thickness of the etching mask layer needs to be as small as possible in order to eliminate the size shift between the resist pattern and the X-ray absorber pattern (referred to as a pattern conversion difference). Thus, when the thickness of the etching mask layer is reduced, X
It is necessary that the etching rate of the etching mask layer is sufficiently small (has a high etching selectivity) with respect to the etching rate of the line absorber film.

On the other hand, the etching of the X-ray absorber film is required for etching the X-ray absorber film in order to secure a uniform pattern shape on the wafer surface without causing partial etching residue in the mask surface. It is necessary to perform so-called over-etching, in which etching is performed longer than time, to some extent. Further, when a pattern having a size of 0.2 μm or less is included, a phenomenon (microloading effect) that the etching rate sharply decreases when the pattern size becomes 0.2 μm or less occurs. It is necessary to perform over-etching in accordance with the time required for etching a pattern of 0.2 μm or less with respect to the time required for etching.

However, since the etching of the X-ray absorber film made of a high melting point metal such as Ta is isotropic etching, an undercut 30 occurs in the pattern 31 as shown in FIG. It is difficult to obtain a highly reliable pattern. Further, by performing the above-described over-etching, the undercut is further increased, so that it is more difficult to obtain a pattern with high perpendicularity.

As a technique for solving such a problem, for example, a method described in Japanese Patent Laid-Open No. Hei 4-247719 has been proposed. In this method, a protective film is provided on a pattern side wall by introducing a hydrocarbon gas as a protective film forming gas together with an etching gas into an etching apparatus,
This is to prevent undercut of the pattern.

[0016]

However, the method for providing a protective film by introducing a hydrocarbon gas as a protective film forming gas into the etching apparatus together with the above etching gas has the following problems.

First, when a hydrocarbon gas is introduced into the etching apparatus, the chamber is contaminated, and the hydrocarbon adhering to the chamber is easily polymerized when exposed again to the plasma. There is a problem that maintenance is not easy and reproducibility is poor.

Second, when the gas introduced into the etching apparatus is a mixed gas, the plasma is generally difficult to stabilize,
There is a problem that reproducibility is poor.

Third, since hydrocarbon gas is a flammable gas, there is a problem that safety measures such as a gas alarm device are required for handling the hydrocarbon gas.

The present invention has been made under the above-mentioned background, and it is possible to easily produce a pattern with extremely high perpendicularity with good reproducibility even under a 0.1 μm design rule while solving the above problems. An object of the present invention is to provide a dry etching method and an X-ray mask manufacturing method that can be performed.

[0021]

In order to achieve the above object, the present invention has the following arrangement.

(Structure 1) A dry etching method for dry-etching a thin film while forming a protective film on the side surface of the pattern when forming a pattern by dry-etching the thin film.
Placing a solid material for forming a protective film together with the substrate to be etched having the thin film in a dry etching apparatus, performing dry etching of the thin film and depositing a reactant of the solid material for forming a protective film and an etching gas on a pattern side surface. And performing dry etching while forming a protective film on the side surface of the pattern.

(Structure 2) The dry etching method according to Structure 1, wherein over-etching is performed when forming a pattern by dry etching of the thin film.

(Structure 3) A material such that the vapor pressure of a reactant of the protective film forming solid material and the etching gas is lower than the vapor pressure of a reactant of the material for forming the thin film and the etching gas. The dry etching method according to Configuration 1 or 2, wherein the dry etching method is used as a solid material for forming a protective film.

(Structure 4) The deposition of the protective film is controlled by controlling the flow rate of the introduced etching gas, controlling the exhaust speed,
The dry etching method according to any one of Configurations 1 to 3, wherein the dry etching is performed by controlling an exposed area of the solid material for forming a protective film.

(Structure 5) The dry etching method according to any one of Structures 1 to 4, wherein the thin film is made of a material containing tantalum as a main component.

(Structure 6) A chlorine-based gas is used as the etching gas, and a heavy metal that reacts with chlorine is used as the solid material for forming the protective film, and the protective film is a reactant of the heavy metal and chlorine. 6. The dry etching method according to any one of the first to fifth aspects.

(Structure 7) The heavy metal is Cr, Mo,
7. The dry etching method according to Configuration 6, wherein W is a compound containing a heavy metal or an alloy thereof.

(Structure 8) A mixed gas containing oxygen is used as the etching gas, a material containing silicon is used as the solid material for forming the protective film, and the protective film is a reactant of silicon and oxygen. The dry etching method according to any one of Configurations 1 to 5, further comprising:

(Structure 9) The solid material for forming a protective film comprises:
Configuration 1 characterized by being disposed at least at an exposed portion when a substrate is mounted on a substrate mounting surface of a substrate mounting table.
9. The dry etching method according to any one of items 1 to 8.

(Structure 10) A method of manufacturing an X-ray mask, comprising performing dry etching of an X-ray absorber film containing tantalum as a main component by using the dry etching method described in Structures 1 to 9.

(Configuration 11) An ICP dry etching apparatus having two reaction chambers is used, and another reaction chamber different from the reaction chamber used for etching the etching mask layer is used for etching the X-ray absorber film. 13. The method for manufacturing an X-ray mask according to Configuration 10, wherein:

(Structure 12) Structure 10 or 10 characterized in that an etching mask layer and an etching stop layer made of chromium or a material containing chromium and carbon and / or nitrogen are formed above and below the X-ray absorber film. 12. The method for manufacturing an X-ray mask according to item 11.

[0034]

According to the dry etching method and the X-ray mask manufacturing method of the present invention, the protective film is formed by depositing a reactant of the protective film forming solid material and the etching gas on the side of the pattern without using a hydrocarbon gas. Is formed, so that the above-mentioned problem can be solved, and a pattern having extremely high perpendicularity without undercut can be easily produced with good reproducibility. Further, according to the method of manufacturing an X-ray mask of the present invention, a pattern having extremely high perpendicularity can be easily manufactured with good reproducibility even with a design rule of 0.1 μm.

Hereinafter, the present invention will be described in detail.

The operation of the present invention is considered to take place on the following principle. That is, the plasma gas generated by the etching gas introduced into the dry etching apparatus contacts a thin film containing tantalum as a main component and reacts with tantalum to progress the etching, and at the same time, forms a protective film disposed in the apparatus. Reacts with solid materials. The reactant of the solid material for forming a protective film and the etching gas selectively adheres to the side surface of the thin film pattern mainly composed of tantalum to form a protective film. At this time, by using a material such that the vapor pressure of the reactant of the protective film forming solid material and the etching gas is lower than the vapor pressure of the reactant of the tantalum and the etching gas as the protective film forming solid material. Then, the reactant of the protective film forming solid material and the etching gas is selectively deposited on the side surface of the pattern, and the reactant of the tantalum and the etching gas is selectively exhausted. And since the film deposited on the side of the pattern acts as a protective film,
Even when over-etching is performed, etching of the side surface of the pattern hardly proceeds, and as a result, undercut of the pattern can be prevented. The present invention can be applied to dry etching of a thin film other than a thin film containing tantalum as a main component according to the same principle as described above.

In the present invention, the deposition of the protective film is controlled by
The control can be performed by controlling the flow rate of the introduced etching gas, controlling the pumping speed, controlling the exposed area of the solid material for forming the protective film, controlling the substrate temperature, and the like. That is, to increase the flow rate of the etching gas to be introduced, to increase the pumping speed,
Alternatively, by reducing the exposed area of the solid material for forming the protective film, the deposition of the protective film can be reduced. In the present invention, the control of the deposition of the protective film is applied,
By controlling the undercut of the pattern, the inclination angle of the pattern can be arbitrarily set.

In the present invention, the protective film forming solid material may be disposed at a place where a reaction with the etching gas occurs, but is preferably disposed at an exposed portion of a mounting table on which a substrate to be etched is mounted. Specifically, for example, the mounting table of the substrate is coated with a solid material for forming a protective film, or, as shown in FIGS. 3 and 4, a portion 21 a of the substrate mounting table 21 on which the substrate 27 to be etched is mounted. What is necessary is just to form with a solid material for protective film formation.

The dry etching gas is appropriately selected so as to etch the thin film material to be etched and to form a protective film by depositing a reactant of the solid material for forming the protective film and the etching gas on the side surface of the pattern. I do.
For example, when etching a material containing tantalum as a main component, a chlorine-containing gas or a fluorine-containing gas containing chlorine capable of etching a material containing tantalum as a main component is used as a dry etching gas. Is preferred. Examples of the chlorine-based gas include Cl ₂ , C
l ₂ + O ₂ , Ar + Cl ₂ , Cl ₂ + BCl _{3 and the} like. SF ₆ , Ar + SF ₆ , SF
₆ + CHF _{3 and the} like.

Examples of the material mainly containing tantalum include tantalum alone and tantalum compounds such as tantalum boride.

The solid material for forming the protective film may be any material as long as the reactant with the etching gas to be used can be deposited on the side of the pattern to form the protective film. For example, when a gas containing chlorine is used as an etching gas, heavy metals such as Cr, Mo, W, etc., which react with chlorine, or compounds containing these heavy metals (for example, CrN, CrC,
CrO), an alloy of these heavy metals, a solid material containing C, and the like. When a mixed gas containing oxygen is used as an etching gas, a solid (etched) material (eg, Si, SiN, SiC, SiO, or the like) containing silicon that reacts with oxygen can be used.

As a dry etching apparatus, ICP
(Inductive Coupled Plasma) dry etching equipment,
Plasma etching equipment, light etching equipment, RIE
(Reactive Ion Etching) equipment, reactive ion beam etching (RIBE) equipment,
Sputter etching equipment, ion beam etching equipment and the like can be used. FIG. 5 shows an ICP (Inductive Coupled).
Plasma: shows an example of a dry etching apparatus. In the figure, an ICP dry etching apparatus 20 includes a substrate mounting table 21, an electrode 22, an ICP coil 2
3. It is composed of an introduction gas system 24 and an exhaust system 25, etc.
A high frequency of 13.56 MHz is applied to each of the electrode 22 and the coil 23 to generate a high frequency induction plasma 26. The substrate mounting table 21 can be cooled by a cooling gas (such as He gas). The exhaust is performed by a turbo pump or the like, and the amount of exhaust can be appropriately adjusted (for example, about 1000 l / s). The flow rates of the introduced gas and the exhaust gas can be adjusted by a control system (not shown).

The above-described dry etching method of the present invention can be suitably used as a method of manufacturing an X-ray mask including a step of performing dry etching of an X-ray absorber film containing tantalum as a main component. Hereinafter, a method for manufacturing an X-ray mask of the present invention will be described.

The X-ray mask blank used in the method of manufacturing an X-ray mask of the present invention is obtained by forming at least an X-ray transmission film and an X-ray absorber film mainly composed of tantalum on a substrate. Accordingly, an etching stop layer, an adhesion layer, an antireflection layer, a conductive layer, and the like are provided below the X-ray absorber film, and a mask layer, a protective layer, a conductive layer, and the like are provided on the X-ray absorber film. It is provided. These films are usually formed on a substrate by a sputtering method. The sputtering method is not particularly limited, and examples thereof include an RF magnetron sputtering method, a DC sputtering method, and a DC magnetron sputtering method. As the sputtering gas,
In addition to an inert gas such as argon, xenon, krypton, and helium, a reactive gas may be used depending on the composition of the film.

As a material for the X-ray absorber film, a material containing tantalum as a main component is used. Specifically, for example, T
Compound of a and B [eg, Ta ₄ B (Ta: B = 8: 2)
Or tantalum boride having a composition other than Ta ₄ B],
Examples include metal Ta, an amorphous material containing Ta, and a Ta-based material containing Ta and other substances.

The X-ray absorber material containing tantalum as a main component preferably contains at least B in addition to Ta. This is because the X-ray absorber film containing Ta and B has advantages such as low internal stress, high purity, no impurities, and high X-ray absorption. Also, the internal stress can be easily controlled by controlling the gas pressure when forming a film by sputtering.

B in the X-ray absorber film containing Ta and B
Is preferably 15 to 25 atomic%. X
If the proportion of B in the line absorber film exceeds the above range, the grain size of the microcrystal becomes large, and it becomes difficult to perform sub-micron order fine processing. The applicant of the present invention has already filed an application for the ratio of B in the X-ray absorber film (Japanese Patent Application Laid-Open No. 2-192116).

The X-ray absorber material mainly composed of tantalum preferably has an amorphous structure or a microcrystalline structure. This is because, if the crystal structure (metal structure) is used, it is difficult to perform fine processing on the order of submicrons, and the internal stress is large, causing distortion in the X-ray mask.

Incidentally, the film stress of the X-ray absorber film is 10MPa.
It is preferable that it is not more than a. The thickness of the X-ray absorber film is preferably about 0.3 to 0.8 μm.
Further, the product of the film stress and the film thickness of the X-ray absorber film is 0 to ± 1.
It is preferably within the range of × 10 ⁴ dyn / cm,
More preferably, it is within the range of 0 ± 5 × 10 ³ dyn / cm. This eliminates pattern distortion due to non-uniform stress distribution and contributes to realizing high positional accuracy. When the film stress or the product of the film stress and the film thickness exceeds the above range, even if a vertical sidewall pattern is obtained, the positional distortion due to the stress is large, and X having extremely high positional accuracy is obtained.
No line mask is obtained.

As the substrate, a known substrate such as a silicon substrate (silicon wafer) can be used. Examples of the X-ray transmission film include SiC, SiN, and a diamond thin film. SiC is preferred from the viewpoints of increasing the rigidity of the membrane and resistance to X-ray irradiation. Note that the film stress of the X-ray transmission film is:
It is preferably 50 to 400 MPa or less. Also,
The thickness of the X-ray transmission film is preferably about 1 to 3 μm.

As the material of the etching stop layer and the etching mask layer, for example, chromium or a material containing chromium and carbon and / or nitrogen, and oxygen as long as they do not affect the etching selectivity or the film stress. And a material to which another element such as fluorine is added.

The thickness of the etching mask layer is 10 to 20
0 nm, preferably 15-60 nm, more preferably 3 nm.
0 to 50 nm. When the thickness of the etching mask layer is reduced, an etching mask pattern on a vertical side wall can be obtained and the influence of the microloading effect can be reduced.
The pattern conversion difference at the time of dry-etching the line absorber material layer can be reduced.

The thickness of the etching stopper layer is 5 to 100 n.
m, preferably 7 to 50 nm, more preferably 10 to 3
0 nm. When the thickness of the etching stop layer is reduced,
Since the etching time can be shortened, it is possible to reduce a change in shape of the X-ray absorber pattern due to etching when removing the etching stop layer.

The product of the film stress and the film thickness in the etching stop layer and the etching mask layer is ± 1 × 10 ⁴ dyn / c.
m or less. If the product of the film stress and the film thickness exceeds the above range, even if a vertical side wall pattern is obtained, positional distortion due to the stress is large, and an X-ray mask having extremely high positional accuracy cannot be obtained.

In the method of manufacturing an X-ray mask of the present invention, an X-ray mask is manufactured using the above-described X-ray mask blank. At this time, the above-described dry etching method of the present invention is used for etching the X-ray absorber film mainly containing tantalum.

Other manufacturing steps of the X-ray mask are not particularly limited, and a conventionally known X-ray mask manufacturing step can be used.

For example, the etching mask layer is patterned by a lithography method using a resist (photo, electron beam) (resist coating, exposure, development, etching, resist peeling, washing, etc.), a multi-layer resist method, a multi-layer mask (metal A known patterning technique such as a film / resist film method can be used. When using resist,
The thickness of the resist is preferably as thin as 50 to 1000 n.
m, preferably 100 to 300 nm.

The etching gas for dry-etching the etching mask layer and the etching stop layer is as follows.
It is preferable to use a mixed gas of chlorine and oxygen. This is because the etching rate (etching rate) of a material containing tantalum as a main component can be extremely reduced by performing etching using a mixed gas in which oxygen is mixed with chlorine as an etching gas. It is possible to increase the etching selectivity (Cr / Ta) of a material containing Cr and carbon and / or nitrogen with respect to a material containing as a main component. This is because the relative etching rate can be reversed (1 or more) as compared with 1).

[0059]

The present invention will be described below in more detail with reference to examples.

Embodiment 1 Manufacturing of X-ray Mask Blank FIG. 6 is a sectional view showing a manufacturing process of an X-ray mask blank according to one embodiment of the present invention.

First, a silicon carbide film was formed on both surfaces of the silicon substrate 11 as the X-ray transmission film 12 (FIG. 6).
(A)). Here, as the silicon substrate 11, a silicon substrate having a size of 3 inches φ, a thickness of 2 mm and a crystal orientation (100) was used. The silicon carbide film as the X-ray transmission film 12 was formed to a thickness of 2 μm by a CVD method using dichlorosilane and acetylene. Next, the surface of the silicon carbide film was flattened by mechanical polishing to obtain a surface roughness of Ra = 1 nm or less.

Next, an X-ray absorber film 13 made of tantalum and boron was formed on the X-ray transmission film 12 to a thickness of 0.5 μm by RF magnetron sputtering (FIG. 6B). At this time, the sputter target was a sintered body containing tantalum and boron at an atomic ratio (Ta / B) of 8/2. The sputtering conditions were as follows: sputtering gas: A
r, RF power density: 6.5 W / cm ² , sputtering gas pressure: 1.0 Pa.

Subsequently, the above substrate was heated at 250 ° C. for 2 hours.
Time annealing is performed to obtain a low stress X of 5 MPa or less.
A line absorber film 13 was obtained.

Next, on the X-ray absorber film 13, a film containing chromium and carbon was formed as an etching mask layer 14 to a thickness of 0.05 μm by RF magnetron sputtering. As a result, an etching mask layer 14 having a low stress of 100 MPa or less was obtained (FIG. 6C). At this time, Cr was used as a sputtering target, and sputtering conditions were as follows: sputtering gas: a gas in which methane was mixed with 7% in Ar, RF power density: 6.5 W / cm ² , and sputtering gas pressure: 1.2.
Pa.

Production of X-Ray Mask An X-ray mask was produced using the X-ray mask blank obtained above.

Specifically, first, an electron beam resist (ZEP: manufactured by Zeon Corporation) applied on an X-ray mask blank
Then, a line and space (hereinafter, referred to as L & S) pattern including a minimum line width of 0.10 μm was drawn by an electron beam, and an electron beam resist pattern was formed by wet development.

Using this electron beam resist pattern as a mask, using an ICP (inductively coupled plasma) etching apparatus shown in FIG. 5, etching conditions of coil power: 200 W, bias: 0 to 0.3 × 10 ⁻³ W / cm ² . A mixed gas of chlorine and oxygen (gas flow rate; chlorine: 25 sccm, oxygen: 5 scc) while cooling the substrate to 10 ° C.
In step m), the etching mask layer was etched to obtain an etching mask pattern.

Using this etching mask pattern as a mask, using an ICP dry etching apparatus, coil power: 500 to 800 W, bias: 6.0 × 10 ⁻³ W /
Chlorine (Cl ₂ ) (gas flow rate: 40 to 100 sccc) while cooling the substrate to 10 ° C. under the etching condition of cm ^2.
The x-ray absorber film was etched using m) as an etching gas. At this time, 100% over-etching was performed with respect to the just etching time of the pattern of 0.2 μm or more (the etching time was twice the just etching time). Further, as the ICP dry etching apparatus, an ICP dry etching apparatus having two reaction chambers was used, and a reaction chamber different from the reaction chamber used for etching the etching mask layer was used. This is because the etching gas and the material to be etched used in each process are different, and in dry etching, delicate environmental contamination of the reaction chamber greatly affects the reproducibility of the etching rate and etching selectivity. It is necessary to pay sufficient attention to management, and it is preferable to provide a reaction chamber for each step. In the reaction chamber for etching the X-ray absorber film, a mounting table coated with Cr was used as a mounting table for the substrate. Thereby, the X-ray absorber film (Ta ₄
In the etching of B), Cr on the mounting table is also etched to generate a Cr reactant, and Cr is selectively formed on the pattern side wall.
The reactants were redeposited to suppress isotropic etching of the pattern sidewalls and control the pattern undercut.
The balance between the etching and re-deposition of Cr was mainly controlled by the flow rate of the introduced gas, the pumping speed, and the exposed area of Cr.

Finally, an unnecessary film such as an etching mask pattern was removed to obtain an X-ray mask.

Evaluation The cross section of the pattern of the X-ray mask obtained above was examined by SEM (Sc
As a result of observing the shape with an anning electron microscope, it was found that there was no pattern undercut and the sidewalls were formed vertically (the verticality of the sidewalls, the surface condition of the sidewalls,
The formation of a 0.10 μm L & S X-ray absorber pattern with line linearity and the like was confirmed.

The position distortion of the X-ray mask obtained above was evaluated by a coordinate measuring machine, and as a result, 1 Gbit-DR was obtained.
The positional distortion required for the AM X-ray mask was 22 nm or less, and it was confirmed that high positional accuracy could be realized.

Although the present invention has been described with reference to the preferred embodiments, the present invention is not limited to the above embodiments.

For example, the solid material for forming the protective film is not limited to Cr, and similar effects can be obtained by using Si, Mo, W, carbon or the like.

In the above embodiment, Cl ₂ is used as the etching gas. However, the present invention is not limited to this, and a fluorine-based gas such as SF ₆ may be used. However, when SF ₆ or the like is used, the vapor pressure of the reactant between the solid material for forming the protective film and the etching gas, and the chemical species of the reactant deposited on the side surface of the pattern as the protective film are taken into consideration. Select a material.

Further, the dry etching conditions of the X-ray absorber film are not limited to the values of the embodiment, for example, the coil power is 0 to 800 W, the substrate bias is 0 to 300 W, the substrate temperature is -10 to 30 ° C. Pressure is 0.1-40mTorr
Can be adjusted in the range. The over-etching is 10
It is not limited to 0%, and can be appropriately selected within a range of, for example, 50 to 120%.

The ICP dry etching apparatus used for etching the X-ray absorber film may be a separate apparatus from the ICP dry etching apparatus used for etching the etching mask layer.

In the present invention, the thickness of the thin film to be etched is not particularly limited, and the present invention includes a case where the material to be etched is etched.

[0078]

As described above, according to the dry etching method and the X-ray mask manufacturing method of the present invention, a reactant between a solid material for forming a protective film and an etching gas is patterned without using a hydrocarbon gas. Since the protective film is formed by depositing on the side surface, the problem of the conventional method using hydrocarbon gas as the protective film forming gas can be solved, and an extremely vertical pattern without undercut can be easily reproduced with good reproducibility. Can be manufactured.

Further, according to the method of manufacturing an X-ray mask of the present invention, a pattern having extremely high perpendicularity can be easily manufactured with good reproducibility even with a design rule of 0.1 μm.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view for explaining a structure of an X-ray mask.

FIG. 2 is a cross-sectional view illustrating an X-ray mask blank.

FIG. 3 is a perspective view showing an example of a substrate mounting table.

FIG. 4 is a plan view showing an example of a substrate mounting table.

FIG. 5 is a perspective view showing an example of an ICP dry etching apparatus.

FIG. 6 is a cross-sectional view showing a manufacturing process of the X-ray mask blank according to one embodiment of the present invention.

FIG. 7 is a cross-sectional view for explaining an undercut of a pattern.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 X-ray mask 2 X-ray mask blank 11 Silicon substrate 11a Support substrate (support frame) 12 X-ray transmission film 13 X-ray absorber film 13a X-ray absorber pattern 14 Etching mask layer 20 ICP dry etching apparatus 21 Substrate mounting table 22 Electrode 23 Coil 24 Introduced gas system 25 Exhaust system 26 High frequency induction plasma 27 Substrate to be etched 30 Undercut

Claims (12)

[Claims] 1. A dry etching method for dry-etching a thin film while forming a protective film on the side surface of the pattern when forming a pattern by dry-etching the thin film. Placing a protective film forming solid material together with the substrate to be etched having the thin film in the apparatus, performing dry etching of the thin film and depositing a reactant of the protective film forming solid material and an etching gas on a pattern side surface. A dry etching method comprising performing dry etching while forming a protective film on a pattern side surface. 2. The dry etching method according to claim 1, wherein over-etching is performed when the pattern is formed by dry etching of the thin film. 3. A protective film is formed by using a material such that a vapor pressure of a reactant of the etching gas and the solid material for forming the protective film is lower than a vapor pressure of a reactant of the etching gas and the material forming the thin film. The dry etching method according to claim 1, wherein the dry etching method is used as a forming solid material. 4. The method according to claim 1, wherein the deposition of the protective film is controlled by controlling a flow rate of an etching gas to be introduced, controlling a pumping speed, and controlling an exposed area of the solid material for forming the protective film. 4. The dry etching method according to 3. 5. The dry etching method according to claim 1, wherein the thin film is made of a material containing tantalum as a main component. 6. The protective film is a reactant of the heavy metal and chlorine, using a chlorine-based gas as the etching gas, and using a heavy metal that reacts with chlorine as the solid material for forming the protective film. The dry etching method according to claim 1, wherein: 7. The dry etching method according to claim 6, wherein the heavy metal is Cr, Mo, W, a compound containing these heavy metals, or an alloy thereof. 8. The protective film is a reaction product of silicon and oxygen, using a mixed gas containing oxygen as the etching gas and using a material containing silicon as the solid material for forming the protective film. 6. The dry etching method according to claim 1, wherein: 9. The apparatus according to claim 1, wherein the solid material for forming a protective film is disposed at least at an exposed portion when the substrate is mounted on the substrate mounting surface of the substrate mounting table.
3. The dry etching method according to 1. 10. A method of manufacturing an X-ray mask, comprising performing dry etching of an X-ray absorber film containing tantalum as a main component by using the dry etching method according to claim 1. 11. An ICP having two reaction chambers.
The manufacturing of the X-ray mask according to claim 10, wherein a dry etching apparatus is used, and a reaction chamber different from the reaction chamber used for etching the etching mask layer is used for etching the X-ray absorber film. Method. 12. An etching mask layer and an etching stop layer made of chromium or a material containing chromium and carbon and / or nitrogen are formed on and under the X-ray absorber film. 3. The method for manufacturing an X-ray mask according to 1.