JPH05267130A - Manufacture of x-ray mask - Google Patents

Abstract

PURPOSE:To prevent a pin-dot fault by applying X-rays under the state, in which a membrane is inclined to an X-ray optical axis, from the side, where a first X-ray absorber pattern is formed, developing a resist, etching the X-ray absorber exposed and forming a second X-ray absorber pattern on another surface side of the membrane. CONSTITUTION:A first X-ray absorber pattern 2b is shaped onto an upper-layer X-ray absorber film 2b through a normal method. On the other hand, an Si substrate 1 is etched back and a window 10 is bored, and an X-ray resist 4 is applied. X-rays are applied from the first X-ray absorber pattern 20b side. Inclination of the perpendicular surface of a membrane 3 to an X-ray optical axis is set at 26.5 deg. maximally at that time, and X-rays are projected obliquely to the membrane 3. The X-ray resist 4 is developed, a resist pattern 40 is formed, a lower-layer X-ray absorber film 2a is etched while using the resist pattern 40 as a mask, and a second X-ray absorber pattern 20a is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an X-ray mask having no pinholes or pin dot defects in an X-ray absorber pattern or membrane.

[0002]

2. Description of the Related Art A mask structure is generally one in which an absorber pattern is formed on one side of a membrane, but recently, a double-sided absorber mask in which an absorber pattern is formed on both the front and back sides of the membrane is used on both sides of the membrane. The thickness of each individual absorber pattern formed is thinner than that of a single-sided absorber mask, and since it is formed on both the front and back sides of the membrane, it has the advantages of good stress balance and less strain. It suddenly came into the limelight.

The X-ray mask having such a double-sided absorber structure is a self-aligned second-layer absorption in which a desired absorber pattern formed first on one side of the membrane is transferred to the opposite side by X-ray irradiation. Forming a body pattern.
FIG. 6 is a process explanatory diagram showing a method for manufacturing a double-sided absorber X-ray mask that the present inventors have already proposed.

That is, (a) three layers of an X-ray absorber film 2a, a membrane 3 and another X-ray absorber film 2b are formed on a substrate 1. (b) A desired X-ray absorber pattern (first X-ray absorber pattern) 20b is formed on the front side X-ray absorber film 2b. (c) After back-etching the substrate 1 side and applying a resist 4 on the surface of the X-ray absorber film 2a opposite to the side where the X-ray absorber pattern 20b is formed, the X-ray absorber pattern 20b X-rays are radiated perpendicularly to the membrane 3 from the side where the film is formed. (d) After developing the resist 4, the resist pattern
The X-ray absorber film 2a is etched using 40 as a mask, and the second
The X-ray absorber pattern 20a is formed. (e) The resist pattern 40 is removed to obtain the double-sided absorber X-ray mask 5.

[0005]

In the mask in which the absorber is applied to the surface of the membrane as described above, the formed absorber pattern 20b has minute pinholes 21b and pin dots 22.
The defect of b (dimensionally, for example, 0.1 μm or less) is likely to occur. Therefore, it is necessary to inspect and repair defects, but it is difficult to inspect and repair such fine defects, and a large amount of time is required for processing. If defect correction is not performed, the yield of devices formed using this mask will be extremely reduced.

Particularly, in the X-ray mask having the double-sided absorber structure, when such a defect is present in the first X-ray absorber pattern 20b formed first, the membrane 3 is irradiated by the X-rays.
When the same pattern is transferred to the side opposite to the above, the same X-ray transfer ability is extremely high, so the same defect is transferred as it is to the obtained second X-ray absorber pattern 20a.
Therefore, the inspection / correction must be performed on both sides of the mask.

The present invention was devised in view of the above problems, and improves the method of manufacturing an X-ray mask so that an X-ray mask free of minute pinholes and pin dot defects can be obtained. Is.

[0008]

According to the present invention, a double-sided absorber X-ray mask manufacturing method, in which an X-ray absorber pattern is formed on both sides of a membrane by self-alignment, is applied to both sides without fine pinholes or pin dot defects. An X-ray mask having an absorber structure or a single-sided absorber structure is obtained. In the present invention, the second X-ray absorber pattern formed by self-alignment is designed to eliminate such defects, but the resist applied to one side of the membrane to form the pattern. Since the manufacturing method is different depending on whether it is a positive type or a negative type, description will be given separately for two structures.

First, in the first method of manufacturing an X-ray mask, an X-ray absorber film, a membrane, and a further layer of X-ray are formed on a substrate.
The three layers of the line absorber film are sequentially deposited, and the X-ray absorber film on one surface of the membrane is processed to form the first X-ray absorber pattern, and then the substrate side is back-etched or the substrate side. After back etching, the first X-ray absorber pattern is formed, and a resist (positive type) is applied to the surface of the X-ray absorber film opposite to the side where the first X-ray absorber pattern is formed. In addition, X-rays are radiated from the side on which the first X-ray absorber pattern is formed with the membrane tilted with respect to the X-ray optical axis, and the resist is further developed, and then the exposed X-ray absorption is absorbed. The basic feature is that the body film is etched to form a second X-ray absorber pattern on the other surface side of the membrane.

The other method for manufacturing an X-ray mask is that two layers of an X-ray absorber film and a membrane are sequentially deposited on a substrate, the substrate side is back-etched, and then the exposed X-ray absorber film is formed. A first X-ray absorber pattern is formed by treatment, and a resist (negative type) is applied to the membrane surface on the side opposite to the side on which the first X-ray absorber pattern is formed. From the side where the X-ray absorber pattern is formed, X
The resist pattern is formed by irradiating X-rays with the membrane tilted with respect to the line optical axis, and further developing the resist to form an X-ray absorber on the membrane surface exposed between the resist patterns. Is performed to form a second X-ray absorber pattern, and finally the resist pattern is removed.

In both of the above two inventions, X-ray irradiation is performed with the membrane set in a state of being inclined with respect to the X-ray optical axis.
Since such oblique incident light is used, as shown in FIG. 1, in the minute pinhole defect portion, the absorber patterns 23 and 24 around the pinhole serve as a light shield, and the defect absorbs the second X-ray absorption. It will not be transferred to the body pattern side. In the case of pin dots, as shown in FIG. 2, when X-rays cross diagonally, the effective thickness of the light shield 25 becomes sufficiently thin, and this defect is not transferred. From this, the second X-ray absorber pattern is free of minute defects.

However, in order to always obtain such an effect, when the minimum pattern interval is Δx and the thickness of the first X-ray absorber pattern is d, the oblique incident angle of X-rays, that is, X-rays The angle of the membrane vertical plane to the optical axis
The condition is (Δx / d) or less. When the X-ray irradiation is performed at an angle larger than this, the gap (empty area region) that should originally exist between the patterns is not transferred like the pin dots, and is desired for the second X-ray absorber pattern. This is because the pattern cannot be formed accurately.

When X-ray irradiation is performed by inclining the membrane with respect to the X-ray optical axis and rotating the membrane about the optical axis, the first X-ray is generated even when such oblique incidence is performed. The linear absorber pattern is accurately (symmetrically) transferred to the opposite surface side across the membrane without displacement (however, it goes without saying that the accuracy depends on the resolution of the resist. ).

Further, in both of the two inventions, after the second X-ray absorber pattern is formed, the first X-ray absorber pattern having a defect such as a pinhole or a pin dot is removed by etching to remove the single-sided absorber. It can be structured.

In addition, after removing the first X-ray absorber pattern, a second X-ray having no pinholes or pin dot defects is removed.
Based on the X-ray absorber pattern, the X-ray absorber film and the resist deposition process, the X-ray oblique incidence, the resist development, the X-ray absorber film etching and the X-ray absorber deposition process are performed again. If the first X-ray absorber pattern is formed again at the same position as the original first X-ray absorber pattern, there is no pin dot or pinhole defect in the X-ray absorber pattern on both sides of the membrane. An X-ray mask with a complete double-sided absorber structure will be obtained.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the accompanying drawings.

FIGS. 3 and 4 show a manufacturing process in the case where the resist applied to one side of the membrane for forming the second X-ray absorber pattern is a positive type, and FIG.
Shows a case where a second X-ray absorber pattern is formed on the membrane surface on the side where the substrate is back-etched (here, a double-sided absorber structure is used), and FIG. The X-ray absorber pattern is formed, and the first absorber pattern is later removed to form a single-sided absorber structure.

First, the process of FIG. 3 will be described.
As shown in (a), the lower X-ray absorber film 2 is formed on the Si substrate 1.
a, the X-ray membrane 3 thereon, and further the upper X-ray absorber film 2b thereon. At this time, both X-ray absorber films 2a and 2b
Both are 0.4 μm thick W and the membrane 3 is 2 μm thick SiN.
It is formed by x (however, the material and the thickness are not limited thereto).

Then, as shown in FIG. 2B, the first X-ray absorber pattern 20 is formed on the upper X-ray absorber film 2b by a usual method.
form b.

On the other hand, after the Si substrate 1 is back-etched to open the window 10, an X-ray resist 4 is applied to the back-etched surface as shown in FIG. Next, X-rays are emitted from the first X-ray absorber pattern 20b side. At this time, the inclination angle of the vertical surface of the membrane 3 with respect to the X-ray optical axis is 26.5 ° at the maximum [this angle was obtained by arctan (0.2 / 0.4) because the design dimension of the minimum pattern in this example is 0.2 μm] X-rays were obliquely incident on the membrane 3. Further, at the time of this oblique incidence, as shown in FIG. 3D, the entire mask was rotated around the X-ray optical axis to irradiate X-rays.

Next, after developing the X-ray resist 4 to form a resist pattern 40, as shown in FIG.
Lower layer X-ray absorber film using the resist pattern 40 as a mask
2a is etched to form a second X-ray absorber pattern 20a.

Finally, the resist pattern 40 is removed,
A double-sided absorber X-ray mask 5 as shown in FIG.

The second X formed through the above steps
The X-ray absorber pattern 20a includes the first X-ray absorber pattern 2
Minute pinhole 21b and pin dot 22b that existed in 0b
Was not transferred, and the desired pattern was accurately formed.

In the second embodiment shown in FIG. 4, the first X-ray absorber pattern 20a is formed on the back-etch side of the substrate 1, and the pattern 20a is removed by etching in the last step.
It differs from the previous embodiment in that it is manufactured as a single-sided absorber structure.

That is, as shown in FIG. 3A, the lower X-ray absorber film 2a, the membrane 3, and the upper X-ray absorber film 2b are sequentially laminated on the Si substrate 1. At this time, both X-ray absorber films 2a and 2b
Both are made of W having a thickness of 0.75 μm, and the membrane 3 is made of SiC.

In this embodiment, back etching is first performed on the substrate 1 side, and the first X-ray absorber is formed on the lower X-ray absorber film 2a on the back etch side as shown in FIG. The pattern 20a was created by the usual method.

Further, a resist 4 is applied on the upper X-ray absorber film 2b, and X-rays are irradiated from the back etch side. Also at this time, as shown in FIG. 6C, irradiation is performed with the membrane 3 tilted with respect to the X-ray optical axis. In this embodiment, since the minimum pattern design dimension is 0.2 μm, the membrane for the X-ray optical axis is
The maximum vertical angle of 3 is 14.9 ° [arctan (0.2 / 0.75)]
And At the same time, in this embodiment, as shown in FIG.
The entire mask is rotated around the X-ray optical axis to irradiate X-rays.

Next, the resist 4 is developed to form a resist pattern 40 as shown in FIG.

Subsequently, this resist pattern 40 is formed.
The upper X-ray absorber film 2b is etched by using as a mask to form a second X-ray absorber pattern 20b as shown in FIG. 7F, and then the resist pattern 40 is peeled off.

In this example, finally, as shown in FIG. 3G, the first X-ray absorber pattern 20a was removed by etching to obtain an X-ray mask 5 having a single-sided absorber structure.

The X-ray mask 5 created as described above
Was free of fine pin dots and pinholes.

FIG. 5 shows another embodiment of the method of the present invention for forming an X-ray mask having a double-sided absorber structure using a negative resist.

In this embodiment, as shown in FIG.
The X-ray absorber film 2 laminated on the substrate 1 is only one layer,
Further, the membrane 3 was laminated on it.

Then, the substrate 1 side is back-etched, and the same figure (b)
As shown in, X exposed by this back etch
The first X-ray absorber pattern 2 is formed on the X-ray absorber film 2 by a conventional method.
Form 0a.

Next, the surface of the membrane 3 is subjected to a pretreatment of a plating method required in the subsequent steps, and then a resist 4 is applied, and as shown in FIG.
Irradiate X-ray from the back etch side while inclining. At this time, the X-ray irradiation is continued while rotating the entire mask as shown in FIG. 7D with the X-ray optical axis as the axis.

Further, the resist 4 is developed to form a resist pattern 40 as shown in FIG.

After that, as shown in FIG. 3F, a second X-ray absorber pattern 20b is formed by plating on the surface of the membrane 3 where the resist pattern 40 is not deposited.

Finally, the resist pattern 40 is peeled off, and the first X-ray absorber pattern 20a formed on the back-etch side is slightly etched to remove the first X-ray absorber pattern 20a as shown in FIG. The fine pin dot 22a defect of the X-ray absorber pattern 20a was eliminated.

The X-ray mask 5 having the double-sided absorber structure produced as described above has no minute pin dot defects on both sides, and one of them has no minute pin hole defects.
It had a line absorber pattern.

[0040]

According to the method of the present invention described in detail above, an X-ray mask having an X-ray absorber pattern free of minute pin dots or pinhole defects is obtained on at least one side thereof. Such inspection and repair of defects becomes easy or unnecessary, and the yield of devices formed using the mask becomes good.

[Brief description of drawings]

FIG. 1 is an explanatory view of the principle of the method of the present invention.

FIG. 2 is an explanatory view of the principle of the method of the present invention.

FIG. 3 is an explanatory view showing the manufacturing process of the X-ray mask according to the first embodiment of the present invention.

FIG. 4 is an explanatory view showing the manufacturing process of the X-ray mask according to the second embodiment of the present invention.

FIG. 5 is an explanatory view showing a manufacturing process of an X-ray mask according to another embodiment of the present invention.

FIG. 6 is a process explanatory view of the method for manufacturing the double-sided absorber X-ray mask according to the present inventors' existing proposal.

[Explanation of symbols]

 1 Substrate 2, 2a, 2b X-ray absorber film 3 Membrane 4 Resist 5 X-ray mask 20a, 20b X-ray absorber pattern 40 Resist pattern

Claims (12)

[Claims] 1. An X-ray absorber film, a membrane, a substrate,
Further, three layers of the X-ray absorber film of another layer are sequentially deposited, and the X-ray absorber film on one surface of the membrane is processed to form the first X-ray absorber film.
After the line absorber pattern is formed, the substrate side is back-etched, or the substrate side is back-etched and then the first X-ray absorber pattern is formed. Applies a resist to the surface of the X-ray absorber film on the opposite side, and irradiates X-rays from the side on which the first X-ray absorber pattern is formed with the membrane tilted with respect to the X-ray optical axis. , The exposed X after further developing the resist
A method of manufacturing an X-ray mask, comprising: etching the line absorber film to form a second X-ray absorber pattern on the other surface side of the membrane. 2. An X-ray absorber film, a membrane, on a substrate
Further, three layers of the X-ray absorber film of another layer are sequentially deposited, and the X-ray absorber film on one surface of the membrane is processed to form the first X-ray absorber film.
After the line absorber pattern is formed, the substrate side is back-etched, or the substrate side is back-etched and then the first X-ray absorber pattern is formed. Applies a resist to the surface of the X-ray absorber film on the opposite side, and irradiates X-rays from the side on which the first X-ray absorber pattern is formed with the membrane tilted with respect to the X-ray optical axis. , The exposed X after further developing the resist
A method of manufacturing an X-ray mask, characterized in that the X-ray absorber film is etched to form a second X-ray absorber pattern on the other surface side of the membrane, and then the first X-ray absorber pattern is removed. .. 3. An X-ray absorber film, a membrane, on a substrate
Further, three layers of the X-ray absorber film of another layer are sequentially deposited, and the X-ray absorber film on one surface of the membrane is processed to form the first X-ray absorber film.
After the line absorber pattern is formed, the substrate side is back-etched, or the substrate side is back-etched and then the first X-ray absorber pattern is formed. Applies a resist to the surface of the X-ray absorber film on the opposite side, and irradiates X-rays from the side on which the first X-ray absorber pattern is formed with the membrane tilted with respect to the X-ray optical axis. , The exposed X after further developing the resist
The X-ray absorber film is etched to form a second X-ray absorber pattern on the other surface side of the membrane, and then the first X-ray absorber pattern is removed. Further, a resist was applied thereon, and X-rays were irradiated from the side where the second X-ray absorber pattern was formed with the membrane tilted with respect to the X-ray optical axis, and the resist was further developed. After that, the exposed X-ray absorber film is etched to form the first X-ray absorber pattern again on the membrane surface. 4. An X-ray absorber film, a membrane, on a substrate
Further, three layers of the X-ray absorber film of another layer are sequentially deposited, and the X-ray absorber film on one surface of the membrane is processed to form the first X-ray absorber film.
After forming the X-ray absorber pattern, the substrate side is back-etched, or the substrate side is back-etched and then the first X-ray absorber pattern is formed. Applies a resist to the surface of the X-ray absorber film on the opposite side, and irradiates X-rays from the side on which the first X-ray absorber pattern is formed with the membrane tilted with respect to the X-ray optical axis. , The exposed X after further developing the resist
The X-ray absorber film is etched to form a second X-ray absorber pattern on the other surface side of the membrane, subsequently the first X-ray absorber pattern is removed, and then a resist is applied again to the surface, From the side on which the second X-ray absorber pattern is formed, X
A resist pattern is formed by irradiating X-rays with the membrane tilted with respect to the line optical axis, and further developing the resist to form an X-ray absorber on the membrane surface exposed between the resist patterns. Is carried out to form the first X-ray absorber pattern again on the membrane surface, and finally the resist pattern is removed. 5. The method of manufacturing an X-ray mask according to claim 1, wherein the minimum pattern interval is Δx, X.
5. The X-rays according to claim 1, wherein an angle of the membrane vertical plane with respect to the X-ray optical axis is arctan (Δx / d) or less, where d is the thickness of the line absorber pattern. Mask manufacturing method. 6. The method for manufacturing an X-ray mask according to claim 1, wherein the membrane is tilted with respect to the X-ray optical axis upon irradiation with X-rays, and the membrane is rotated about the optical axis. The method of manufacturing an X-ray mask according to any one of claims 1 to 5, wherein the method is performed as follows. 7. A first X-ray absorber is formed by sequentially depositing two layers of an X-ray absorber film and a membrane on a substrate, back etching the substrate side, and processing the exposed X-ray absorber film. A body pattern is formed, a resist is applied to the surface of the membrane on the side opposite to the side on which the first X-ray absorber pattern is formed, and at the same time, from the side on which the first X-ray absorber pattern is formed, X The resist pattern is formed by irradiating X-rays with the membrane tilted with respect to the line optical axis, and further developing the resist to form an X-ray absorber on the membrane surface exposed between the resist patterns. Do the second X
A method of manufacturing an X-ray mask, which comprises forming a line absorber pattern and finally removing the resist pattern. 8. A first X-ray absorber is formed by sequentially depositing two layers of an X-ray absorber film and a membrane on a substrate, back etching the substrate side, and processing the exposed X-ray absorber film. A body pattern is formed, a resist is applied to the surface of the membrane on the side opposite to the side on which the first X-ray absorber pattern is formed, and at the same time, from the side on which the first X-ray absorber pattern is formed, X The resist pattern is formed by irradiating X-rays with the membrane tilted with respect to the line optical axis, and further developing the resist to form an X-ray absorber on the membrane surface exposed between the resist patterns. Do the second X
A method of manufacturing an X-ray mask, comprising forming a line absorber pattern, removing the resist pattern, and removing the first X-ray absorber pattern. 9. A first X-ray absorber is formed by sequentially depositing two layers of an X-ray absorber film and a membrane on a substrate, back etching the substrate side, and processing the exposed X-ray absorber film. A body pattern is formed, a resist is applied to the surface of the membrane on the side opposite to the side on which the first X-ray absorber pattern is formed, and at the same time, from the side on which the first X-ray absorber pattern is formed, X The resist pattern is formed by irradiating X-rays with the membrane tilted with respect to the line optical axis, and further developing the resist to form an X-ray absorber on the membrane surface exposed between the resist patterns. Do the second X
A line absorber pattern is formed, the resist pattern is removed, and the first X-ray absorber pattern is also removed, and then an X-ray absorber film is deposited on the surface, and a resist is further deposited on the X-ray absorber film. 2 is irradiated with X-rays from the side on which the X-ray absorber pattern is formed with the membrane tilted with respect to the X-ray optical axis, the resist is further developed, and then the exposed X-ray absorber film is etched. And again forming a first X-ray absorber pattern on the membrane surface.
Method of manufacturing line mask. 10. A first X-ray absorber is formed by sequentially depositing two layers of an X-ray absorber film and a membrane on a substrate, back-etching the substrate side, and processing the exposed X-ray absorber film. A body pattern is formed, a resist is applied to the surface of the membrane on the side opposite to the side on which the first X-ray absorber pattern is formed, and at the same time, from the side on which the first X-ray absorber pattern is formed, X The resist pattern is formed by irradiating X-rays with the membrane tilted with respect to the line optical axis, and further developing the resist to form an X-ray absorber on the membrane surface exposed between the resist patterns. Do the second X
A line absorber pattern is formed, the resist pattern is removed, and the first X-ray absorber pattern is also removed, and then a resist is applied again to the surface to form a second X-ray absorber pattern. From the side where the membrane is tilted with respect to the X-ray optical axis, and then the resist is developed to form a resist pattern, and the membrane surface exposed from between the resist patterns is exposed to the X-ray. A method for manufacturing an X-ray mask, which comprises depositing an absorber to form a first X-ray absorber pattern on the surface of the membrane again, and finally removing the resist pattern. 11. The method of manufacturing an X-ray mask according to claim 7, wherein the minimum pattern interval is Δ.
x, and the thickness of the X-ray absorber pattern is d, the angle of the membrane perpendicular plane to the X-ray optical axis is arctan (Δx /
d) The following are set forth in claims 7 to 1.
The method for manufacturing an X-ray mask according to item 0. 12. The method for manufacturing an X-ray mask according to claim 7, wherein the membrane is tilted with respect to the X-ray optical axis with respect to X-ray irradiation, and the membrane is rotated about the optical axis. The method of manufacturing an X-ray mask according to any one of claims 7 to 11, wherein the method is performed as follows.