JPH07220992A - X-ray exposure mask and x-ray exposure mask blank use for manufacturing the same - Google Patents

Abstract

PURPOSE:To provide an X-ray mask having excellent ultrafine pattern by improving adhesive properties between an X-ray absorber pattern and an X-ray transmission supporting film. CONSTITUTION:An X-ray exposure mask is formed by sequentially forming an X-ray transmission supporting film 13 made of a substance of light element, a close contact reinforcing layer 17 containing any one of chromium, tin and platinum as a constituent element, and an X-ray absorber layer 16 made of heavy metal on a base material 14 by a vapor growth method. The reinforcing layer contains 5-30& of at least one of oxygen, nitrogen and carbon, and a thickness (t) of the reinforcing layer is 0<t<=100nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to LSI, VLSI, U
Used in X-ray lithography and the like, in original images for reproduction required when forming extremely fine patterns, including semiconductor integrated circuits represented by LSI and the like.
So-called X-ray exposure mask (hereinafter referred to as X-ray mask)
And a mask blank for X-ray exposure (hereinafter referred to as an X-ray mask blank).

[0002]

2. Description of the Related Art Generally, an X-ray exposure mask (hereinafter, referred to as an X-ray mask) has an X-ray absorber pattern, an X-ray transmission support film for supporting the X-ray absorption pattern, and an X-ray transmission support film on the outer periphery. It is composed of a supporting base material supported on the side. Further, the X-ray mask blank is composed of an X-ray absorber layer, an X-ray transparent support film, and a support base material in a state before processing the X-ray absorber pattern. In addition, there is also one in which a pedestal is attached to the back surface of the supporting base material (not shown).

The X-ray absorber pattern is made of heavy metals such as gold, tungsten, tantalum, etc., which easily absorb X-rays, and is formed as a fine pattern with a thickness of about 0.2 to 1.0 μm.

The X-ray transparent support film is made of a light element such as silicon, silicon nitride, silicon carbide, or a diamond-like thin film that easily transmits X-rays and has a thickness of about 0.5 to 2.0 μm. It is formed in the state of a membrane.

In general, silicon is often used as the supporting base material. For the pedestal, 4 to 5 mm thick Pyrex glass, quartz glass, ceramics such as silicon carbide, or the like is used.

An example of a general method for manufacturing an X-ray mask will be described below.

First, as shown in FIG. 14, a supporting substrate (3
An X-ray transparent support film (33) is formed on the front surface of 4), and a protective film (35) is formed on the back surface thereof by a low pressure CVD method or the like. Further, an X-ray absorber layer (36) is formed on the X-ray transparent support film (33) by a sputtering method or the like to form an X-ray exposure mask blank (30a) (hereinafter referred to as an X-ray mask blank). Complete).

Next, in order to use the protective layer (35) as an etching mask for the opening of the X-ray mask, patterning is performed using a photolithography method or the like, and further the X-ray absorber layer (36). 2) is coated with a resist layer (not shown) for performing desired patterning.

Subsequently, a desired resist pattern is patterned on the resist layer by using a photolithography method or an electron beam exposure method.

Further, using the resist pattern as an etching mask, the X-ray absorber layer (36) is patterned by a reactive ion etching method or the like to obtain a desired X-ray absorber pattern (31).

Finally, the resist pattern is peeled off,
The support substrate (34) is subjected to etching (generally referred to as back etching) by using the protective layer (35) as an etching mask to provide an opening, and an X-ray mask (30) as shown in FIG. 13 is obtained. can get.

The X-ray mask (30) has a line width of 0.25.
It is a mask used for "X-ray lithography", which is a method capable of realizing a fine semiconductor integrated circuit pattern of less than μm, and a pattern with a line width of 0.25 μm or less is also formed in the mask because it is performed by equal-magnification exposure. Is required.

[0013]

However, in the conventional X-ray mask, due to the lack of adhesion between the X-ray absorber pattern (31) and the X-ray transparent support film (33), during manufacturing,
Especially during the reactive ion etching, the line width of 0.
A fine pattern of 2 μm or less meanders and overlaps with an adjacent pattern, which causes a problem that a desired pattern cannot be obtained. In the first place, if the stress of the X-ray absorber layer (36) is a very small value, the problem that the fine pattern meanders and overlaps with the adjacent pattern does not occur even when the adhesion is somewhat weak. However, it is very difficult to control the stress of the thin film formed by the vapor phase growth method with a very small value, which has been a cause of lowering the yield of the X-ray mask.

The object of the present invention is to
An object of the present invention is to provide an X-ray mask having an excellent ultrafine pattern by improving the adhesion between the X-ray absorber pattern and the X-ray transparent support film.

[0015]

Means provided by the present invention for solving the above-mentioned problems are as follows: between the X-ray absorber pattern (16a) and the X-ray transparent support film (13). The X-ray mask (20) is characterized in that an adhesion enhancing layer (17) is provided.

In the X-ray mask, the absorber pattern (16a) is made of either tantalum or tungsten.

The adhesion enhancing layer (17) is an X-ray mask characterized in that any one of chromium, tin and platinum is a main constituent element.

The film thickness t of the adhesion enhancing layer (17) is 0 <
The X-ray mask is characterized in that t ≦ 100 nm.

An X-ray mask characterized in that the adhesion enhancing layer (17) contains 5 to 30% of at least one of oxygen, nitrogen and carbon.

On the base material, an X-ray transparent support film (13) made of a light element, an adhesion enhancing layer (17) containing any one of chromium, tin and platinum as a constituent element, and a heavy metal are used. An X-ray mask blank formed by sequentially forming an X-ray absorber layer (16) formed by vapor phase epitaxy, wherein the adhesion enhancing layer contains at least one of oxygen, nitrogen and carbon in an amount of 5 to 30. %, And the thickness t of the adhesion strengthening layer is 0 <t
It is an X-ray mask blank (10a) for manufacturing an X-ray mask, wherein ≦ 100 nm.

[0021]

According to the X-ray mask (20) and the X-ray mask blank (10a) of the present invention, the X-ray absorber is provided between the X-ray absorber pattern (16a) and the X-ray transparent support film (13). By providing the adhesion-strengthening layer (17) which is extremely thin as compared with the pattern or the X-ray transparent support film, the meandering of the X-ray absorber pattern (16a) during the reactive ion etching is suppressed, and good X-ray absorption is achieved. It is possible to form a body pattern.

Chromium and platinum are used at room temperature to 200
It has a coefficient of thermal expansion close to that of tantalum or tungsten used as an X-ray absorber in the range of ℃ (see Tokyo Observatory compilation / Science chronology, published by Maruzen Co., Ltd. 1988), during reactive ion etching. In, the pattern distortion due to thermal stress is unlikely to occur.

Further, a substance composed of a light element such as silicon nitride or silicon carbide is generally used for the X-ray transparent support film (13), and the adhesion enhancing layer (17) contains oxygen and nitrogen which are light elements. , And by including at least one of carbon in an amount of 5 to 30%, the adhesion to the X-ray transparent support film (13) is improved.

Further, the adhesion enhancing layer (17) contains oxygen, nitrogen,
By including at least one of carbon in an amount of 5 to 30%, it becomes easy to control the stress of the adhesion strengthening layer itself, and
Since the visible light transmittance required for alignment is improved, it is not always necessary to completely remove the adhesion enhancing layer (17) in the non-patterned portion by etching.

[0025]

EXAMPLE An X-ray mask according to the present invention and the X-ray mask will be described below.
Regarding the X-ray mask blank used for manufacturing the X-ray mask,
It will be described in detail with reference to the drawings.

First, the X-ray mask (20) is provided with an X-ray transparent support film (13) on the surface of a support substrate (14) such as a silicon wafer, a protective film (15) on the back surface, and a low pressure CVD method or the like. The film is formed by using the well-known thin film forming method. After that,
An adhesion enhancing layer (17) is formed by a thin film forming method such as a sputtering method, and further, a thin film forming method such as a sputtering method is used to form X on the adhesion enhancing layer (17).
The X-ray mask blank (1
0a) is completed (see FIG. 5A).

Next, as shown in FIGS. 5 (B) to 5 (D), the X-ray mask is formed by forming the X-ray mask on the protective layer (15) on the back surface of the X-ray mask blank (10a). Patterning is performed by using a photolithography method or the like for use as an etching mask for the opening. Also,
A resist layer (18) for performing desired patterning is applied to the X-ray absorber layer (16).

Subsequently, a desired resist pattern (19) is patterned on the resist layer (18) by using a photolithography method or an electron beam exposure method.

Further, using the resist pattern (19) as an etching mask, the X-ray absorber layer (16) and the adhesion enhancing layer (1) are formed by reactive ion etching.
7) is simultaneously etched, and X-ray absorber pattern (16
a) and the adhesion enhancing layer pattern (17a) are obtained.

Finally, the resist pattern is peeled off,
The supporting base material (14) is back-etched using the protective layer (15) as an etching mask to provide an opening to obtain an X-ray mask (20) (see FIG. 1).

The X-ray mask blank (10a) used in the manufacture of the X-ray mask of the present invention has a surface of a supporting substrate (14) such as a silicon wafer, on the surface of which silicon, silicon nitride, silicon carbide, etc. which easily transmit X-rays. The X-ray transparent support film (13) made of the above thin film and the protective film (15) on the back surface are formed by a known thin film forming method such as a low pressure CVD method. Then, an adhesion enhancing layer (17) containing any one of chromium, tin and platinum as a constituent element is formed by a thin film forming method such as a sputtering method, and further, the adhesion enhancing layer (17) is formed. An X-ray absorber layer (16) made of either tantalum or tungsten is formed on the upper surface by a thin film forming method such as a sputtering method to complete the X-ray mask blank (10a) (FIG. See 6).

Specific examples of the X-ray mask of the present invention and the X-ray mask blank used for manufacturing the same will be described below.

<Example 1> X-ray mask (20) shown in FIG.
Is a silicon nitride (SiNx) having a thickness of 2 μm on a silicon support substrate (14) having a diameter of 3 inches and a thickness of 1 mm.
Is formed by a low pressure CVD method. This silicon nitride film is used as the X-ray transparent support film (13) on the front surface side of the support substrate and as the protective film (15) on the back surface side. Then, on the silicon nitride film, a chromium nitride film having a thickness of 10 nm is formed as an adhesion enhancing layer (17) by reactive sputtering using argon gas and nitrogen gas. Furthermore, on the chromium nitride film,
An X-ray mask blank (10a) is formed by forming a tantalum film with a thickness of 700 nm as the X-ray absorber layer (16) using a sputtering method.

Next, in order to provide an opening in the supporting base material (14), the silicon nitride film on the back surface is patterned by photolithography. Further, on the surface, electron beam drawing resist ZEP-520 (manufactured by Zeon Corporation)
To a thickness of 500 nm.

Then, using an electron beam drawing machine, 0.2 μ
m, 0.175 μm and 0.15 μm line and space patterns are drawn and developed to obtain a resist pattern.

Further, in the reactive ion etching using this resist pattern as an etching mask, the chlorine flow rate is 40 sccc / min and the oxygen flow rate is 10 sccc / mi.
n, total gas pressure 6 Pa, high-frequency output 200 W, the X-ray absorber layer (16) and the adhesion enhancing layer (17) were simultaneously etched to obtain a desired X-ray absorber pattern (16).
a) and the adhesion enhancing layer pattern (17a) are obtained.

Finally, the protective film (1) on the back surface of the supporting substrate (14) is formed in order to peel off the resist pattern and provide an opening.
Using 5) as an etching mask, back etching was performed with an aqueous potassium hydroxide solution at 30% and 90 ° C. to obtain an X-ray mask (20).

In the X-ray mask of the present invention produced in this way, it occurs during the etching of the X-ray absorber.
An X-ray mask having a desired pattern was obtained without causing meandering or overlapping in a fine pattern of 0.2 μm or less.

Example 2 A silicon nitride (SiNx) film having a thickness of 2 μm is formed by a low pressure CVD method on a silicon support substrate (14) having a diameter of 3 inches and a thickness of 1 mm. This silicon nitride film uses the front surface side of the support substrate as an X-ray transparent support film (13) and the back surface side as a protective film (15). A 30 nm thick tin oxide film is formed as an adhesion enhancing layer (17) on this silicon nitride film by reactive sputtering using argon gas and oxygen gas. Further, a 700 nm thick tantalum film is formed as an X-ray absorber layer (16) on the tin oxide film by a sputtering method to obtain an X-ray mask blank (10a).

Next, the silicon nitride film on the back surface is patterned by using a photolithography method in order to provide an opening in the supporting base material (14). Further, on the main surface, electron beam drawing resist ZEP-520 (manufactured by Zeon Corporation)
To a thickness of 500 nm.

Then, 0.2 .mu.
m, 0.175 μm and 0.15 μm line and space patterns are drawn and developed to obtain a resist pattern.

Further, in the reactive ion etching using this resist pattern as an etching mask, the chlorine flow rate is 35 sccc / min and the oxygen flow rate is 15 sccc / mi.
n, total gas pressure 6 Pa, high-frequency output 150 W, the X-ray absorber layer (16) was etched to obtain a desired X-ray.
A line absorber pattern (16a) is obtained.

Finally, the resist pattern is peeled off and the protective film on the back surface of the supporting substrate is used as an etching mask to form an opening, and back etching is performed with an aqueous potassium hydroxide solution at 30% and 90 ° C. to perform an X-ray mask. (20a)
Got

In the X-ray mask of the present invention produced in this way, it occurs during the etching of the X-ray absorber.
An X-ray mask having a desired pattern was obtained without causing meandering or overlapping in a fine pattern of 0.2 μm or less. Further, the tin oxide film does not need to be removed because it has high visible light transmittance, and since it has conductivity, it became an X-ray mask suitable for inspection by an electron microscope or the like.

Example 3 In Example 3, as shown in FIG. 3, the protective layer (1) on the back surface of the X-ray mask obtained in Example 1 was used.
An epoxy-based or acrylic-based adhesive is applied to 5) and a perforated glass pedestal (10) (Pyrex glass, quartz glass, ceramic, etc., hereinafter referred to as a glass pedestal) is attached in advance. This glass pedestal (10)
Is attached for the main purpose of reinforcing the X-ray mask.

<Example 4> In Example 4, the protective layer (15) on the back surface of the X-ray mask obtained in Example 2 was coated with an epoxy or acrylic adhesive and preliminarily opened. A glass pedestal (10) is attached. The glass pedestal (10) is attached mainly for the purpose of reinforcing the X-ray mask.

<Embodiment 5> Embodiment 5 shows an example of an X-ray mask blank used for manufacturing an X-ray mask, as shown in FIG. A silicon nitride (SiNx) film having a thickness of 2 μm is formed by a low pressure CVD method on a silicon support substrate (14) having a diameter of 3 inches and a thickness of 1 mm. This silicon nitride film has an X-ray transparent support film (1
3), the back side is used as a protective film (15). And
On the silicon nitride film, a chromium nitride film having a thickness of 10 nm is formed as an adhesion enhancing layer (17) by reactive sputtering using argon gas and nitrogen gas. Furthermore, an X-ray mask blank (10a) was obtained by forming a 700 nm thick tantalum film on the chromium nitride film as the X-ray absorber layer (16) by using a sputtering method.

<Example 6> Example 6 shows an example of an X-ray mask blank as shown in FIG. 7, and an opening is formed in the supporting base material (14) of the X-ray mask blank obtained in Example 5. This is an X-ray mask blank (10b) in which a silicon nitride film on the back surface is patterned by using a photolithography method in order to make a portion.

<Embodiment 7> Embodiment 7 shows an example of an X-ray mask blank as shown in FIG. 8, in which a reinforcing glass pedestal which is pre-opened on the back surface of the supporting substrate (14). (10) was attached to obtain an X-ray mask blank (10c).

<Example 8> Example 8 shows an example of an X-ray mask blank as shown in FIG. 9, and the supporting base material (1) of the X-ray mask blank (10b) obtained in Example 6 was used.
In order to provide an opening on the back surface of 4), back etching is performed with a 30%, 90 ° C. potassium hydroxide aqueous solution using the protective film on the back surface of the supporting base material as an etching mask, and X
A line mask blank (10d) was obtained.

<Example 9> Example 9 is an example of an X-ray mask blank as shown in FIG.
On the back surface of the X-ray mask blank (10d) obtained in step 1, a glass pedestal (10) for reinforcement, which has been pre-drilled, is attached and X is attached.
A line mask blank (10e) was obtained.

<Example 10> Example 10 shows an example of an X-ray mask blank as shown in FIG. 11, in which back etching is performed from the back surface so that about 20% of a supporting substrate such as a silicon wafer remains. That is, half back etching is performed. The half back etching is for further improving the positional accuracy of the pattern. Others were performed like Example 6 and the X-ray mask blank (10f) was obtained.

<Embodiment 11> Embodiment 11 shows an example of an X-ray mask blank as shown in FIG. 12. The X-ray mask blank (10f) obtained in Embodiment 10 is preliminarily opened. Attach the glass pedestal (10) for reinforcement and attach X
A line mask blank (10 g) was obtained.

[0054]

According to the X-ray mask and the X-ray mask blank according to the present invention, a space between the X-ray absorber pattern and the X-ray transmission support film is higher than that of the X-ray absorption pattern and the X-ray transmission support film. By providing an extremely thin adhesion enhancing layer, it is possible to suppress the meandering of the X-ray absorber pattern during reactive ion etching and to form a good X-ray absorber pattern.

That is, by using chromium or platinum as the main constituent element for the adhesion strengthening layer, the coefficient of thermal expansion has a value close to that of tantalum or tungsten used as an X-ray absorber in the range of room temperature to 200 ° C. (Refer to the Tokyo Observatory compilation and science chronology, published by Maruzen 1988).
During reactive ion etching, pattern distortion due to thermal stress is less likely to occur.

Further, a substance composed of a light element such as silicon nitride or silicon carbide is generally used for the X-ray transparent support film, and at least one of light elements such as oxygen, nitrogen and carbon is used for the adhesion strengthening layer. By including 5 to 30%, the adhesion with the X-ray transparent support film is improved.

Further, by containing 5 to 30% of at least one of oxygen, nitrogen and carbon in the adhesion enhancing layer, it becomes easy to control the stress of the adhesion enhancing layer itself, and the visible light transmission necessary for alignment is transmitted. Since the rate is improved, it is not necessary to completely remove the adhesion enhancing layer in the non-patterned portion by etching.

When the X-ray mask blank according to the present invention having the above structure is used to form the X-ray mask, the meandering of the X-ray absorber pattern of 0.2 μm or less, which is a fatal X-ray mask, Problems such as overlap can be prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of an X-ray mask according to an embodiment of the present invention.

FIG. 2 is a sectional view of an X-ray mask according to another embodiment of the present invention.

FIG. 3 is a sectional view of an X-ray mask according to another embodiment of the present invention.

FIG. 4 is a sectional view of an X-ray mask according to another embodiment of the present invention.

FIG. 5 is a method (A) for manufacturing an X-ray mask according to the present invention.
It is a section explanatory view showing (D) in order of a process.

FIG. 6 is a sectional view of an X-ray mask blank according to an embodiment of the present invention.

FIG. 7 is a sectional view of an X-ray mask blank according to another embodiment of the present invention.

FIG. 8 is a sectional view of an X-ray mask blank according to another embodiment of the present invention.

FIG. 9 is a sectional view of an X-ray mask blank according to another embodiment of the present invention.

FIG. 10 is a sectional view of an X-ray mask blank according to another embodiment of the present invention.

FIG. 11 is a sectional view of an X-ray mask blank according to another embodiment of the present invention.

FIG. 12 is a sectional view of an X-ray mask blank according to another embodiment of the present invention.

FIG. 13 is a sectional view showing an example of a conventional X-ray mask.

FIG. 14 is a sectional view showing an example of a conventional X-ray mask blank.

[Explanation of symbols]

10 ... Glass pedestal. 10a, 10b, 10c, 10
d, 10e, 10f, 10g, 30a ... X-ray mask blank, 20, 20a, 20b, 20c, 30 ... X-ray mask, 13 ... X-ray transparent support film, 14 ... Support base material, 14a ...
Half-back-etched support substrate, 15 ... Protective film, 16 ... X-ray absorber layer, 17 ... Adhesion strengthening layer, 16a ...
X-ray absorber pattern, 17a ... Adhesion enhancing layer pattern, 1
8 ... Resist layer, 19 ... Resist pattern

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Shoji Tanaka 1-5-1 Taito, Taito-ku, Tokyo Toppan Printing Co., Ltd.

Claims (6)

[Claims] 1. An X-ray transmissive support film in an X-ray exposure mask comprising an X-ray transmissive support film made of a light element substance and an X-ray absorber pattern made of a heavy metal formed on a substrate.
An X-ray exposure mask comprising an adhesion enhancing layer provided between layers of an X-ray absorber pattern. 2. An X-ray exposure mask, wherein the X-ray absorber pattern is made of one of tantalum and tungsten. 3. The mask for X-ray exposure according to claim 1, wherein the adhesion enhancing layer contains any one of chromium, tin and platinum as a main constituent element. 4. The film thickness t of the adhesion enhancing layer is 0 <t ≦ 10.
X is 0 nm, X of Claim 1 thru | or 3 characterized by the above-mentioned.
Line exposure mask. 5. The mask for X-ray exposure according to claim 1, wherein the adhesion enhancing layer contains 5 to 30% of at least one of oxygen, nitrogen and carbon. 6. An X-ray transparent support film made of a substance of a light element, an adhesion enhancing layer having any one of chromium, tin, and platinum as a constituent element, and an X-ray absorption made of a heavy metal on a substrate. A mask blank for X-ray exposure, which is formed by sequentially forming a body layer by a vapor phase growth method, wherein the adhesion enhancing layer contains 5 to 30% of at least one of oxygen, nitrogen and carbon, and X for producing a mask for X-ray exposure, wherein the film thickness t of the adhesion enhancing layer is 0 <t ≦ 100 nm
Mask blank for line exposure.