JPH05291121A - X-ray mask and its manufacture and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily precisely correct a pattern, by a method wherein a region free from stress is formed on the periphery of a membrane to give it strechability, the edge of the membrane is made to approach a free end, and thereby an absorber pattern after strained and an original pattern are brought into a similar relation. CONSTITUTION:A region 5 free from stress which has a bellows shape along the inner periphery of a retaining frame 1 and uniformly stretchable is arranged on the peripheral part of a membrane 4. The edge of the membrane is almost able to freely move. As the result, a strained pattern 3B has a nearly similar relation to an original pattern 2. Hence, at the time of pattern writing, a mask pattern can be easily and precisely corrected by multiplication of the degree of shrinkage about strain amount, so that an X-ray mask having an absorber pattern which is highly precise and very fine can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-ray mask, a method of manufacturing the same, and a method of manufacturing a semiconductor device including a step of exposing using the X-ray mask.

Along with the increase in the density of VLSI, a lithography technique capable of processing an ultrafine pattern is required. For example, in order to form a pattern having a line width of 0.5 μm, distortion of a mask itself used for the lithography is required. Is required to be at least 0.05 μm or less. Therefore, there is a demand for a means for preventing the distortion of the X-ray mask used for the lithography.

[0003]

2. Description of the Related Art X-ray masks are generally manufactured by the following steps. That is, first, as shown in FIG.
On a silicon (Si) substrate 51 to be a supporting frame, for example, a thickness of 2 to 3
A silicon carbide (SiC) film 52 for a membrane of about μm is formed by a CVD method, and a SiC film 53 for an etching mask is further formed on the lower surface of the Si substrate 51. Then, an X-ray is formed on the SiC film for a membrane 52 by a sputtering method. It becomes an absorber, for example, thickness 0.5 ~
A tantalum (Ta) film 54 of about 1 μm is formed.

Next, as shown in FIG. 5 (b), after forming an etching window 55 for forming a light-transmitting window in the Si substrate 51 in the etching mask SiC film 53, the Si substrate 51 is formed in the above-mentioned manner. The SiC film 53 for an etching mask is faced down and adhered on the ceramic support frame 56. 57 indicates an adhesive.

Next, as shown in FIG. 5 (c), the fluorine is injected through the second transparent window 58 of the ceramic support frame 56 and through the etching window 55 using the etching mask SiC film 53 as a mask. Back etching 59 is performed on the Si substrate 51 with a nitric acid-based solution to form a first transparent window 60 on the Si substrate 51.
Here, the upper surface of the SiC film 52 for membrane and the X-ray absorber
The Si support frame 51F on which the Ta film 54 is stretched is replaced by the ceramic support frame 56
The mask blanks 61 fixed to the above are completed.

Next, as shown in FIG. 5 (d), an EB resist film 62 is formed on the Ta film 54 of the mask blanks 61, a pattern drawing exposure by an electron beam is performed, and then a Ta film is developed to develop the Ta film. A resist pattern 62P corresponding to the mask pattern is formed on 54.

Next, as shown in FIG. 5 (e), after the Ta film 154 is patterned by anisotropic dry etching means such as reactive ion etching using a chlorine-based gas by using the resist pattern 62P as a mask, the remaining resist film 62 is removed. And the resist pattern 62P was removed, and it was stretched on the Si support frame 51F bonded on the ceramic support frame 56.
The X-ray mask in which the Ta pattern 54P of the X-ray absorber is formed on the SiC membrane 52M is completed.

The main strain that occurs in the manufacturing process of such an X-ray mask occurs when the Ta film 54, which is an X-ray absorber, is patterned, and the cause is the Ta film of the X-ray absorber. This is because 54 has stress and the mask pattern 54P made of the Ta film is released from the stress by patterning.

Therefore, in order to make the stress at the time of forming the absorber film as close to zero as possible, efforts have been made to control various parameters during vapor phase growth of the absorber film.

[0010]

Generally, it is the gas pressure during film formation that is most effective in controlling the stress of the absorber. However, in the region where the stress is close to zero, the stress greatly changes even with a slight pressure change, and the controllability is extremely poor. Therefore, only the gas pressure during film formation makes the absorber film close to zero stress. Was extremely difficult to form. for that reason,
Considering the stress of the absorber, it was considered to correct the shape when drawing the pattern. However, with this method, for example, when the pattern is rectangular, the stress is released and the distorted pattern becomes barrel-shaped or saddle-shaped, which makes the calculation for correction very complicated. There was a problem.

Therefore, the present invention provides an X-ray mask having a structure in which a distorted figure becomes a shape similar to the original pattern shape and the pattern can be easily corrected, and a method for manufacturing the same, which uses X-ray exposure. It is an object of the present invention to improve pattern accuracy in a method of manufacturing a semiconductor device.

[0012]

Means for Solving the Problems To solve the above problems, in an X-ray mask in which a membrane is stretched on a cylindrical support frame and an absorber pattern serving as a mask is formed on the membrane, An X-ray mask according to the present invention in which a uniform de-stressed region having a mechanical stretchability larger than the exposed region of the membrane is provided along the inner periphery of the support frame in the peripheral portion, or on the surface of a silicon substrate. A step of forming a single or a plurality of grooves concentrically with respect to the substrate, a step of depositing a membrane material film on the surface of the silicon substrate having the grooves and the inner surface of the groove, and an absorber on the membrane material film The step of depositing the film, the central portion of the silicon substrate is selectively etched away from the rear surface so that the region outside the groove in the silicon substrate, which is separated from the groove, remains concentric with the groove. A cylindrical silicon support frame made of the silicon substrate having a peripheral portion of the membrane material film fixed to the upper surface is formed, and a laminated film of the X-ray absorber and the membrane material inside the silicon support frame is formed. A step of forming a single or a plurality of bellows-shaped bent portions along the inner surface of the silicon support frame, forming a resist film on the X-ray absorber film, and considering the expansion / contraction rate of the bellows-shaped bent portions in the resist film. And exposure of a pattern whose size and position are similarly corrected with an electron beam, and patterning of the X-ray absorber film by using the resist pattern formed by developing the resist film as a mask. A method of manufacturing an X-ray mask according to the present invention, comprising a step of forming a mask pattern made of a body film, or a resist film formed on a semiconductor substrate using the X-ray mask. It is achieved by a method of manufacturing a semiconductor device according to the invention comprising a step of performing X-ray exposure against.

[0013]

1A and 1B are explanatory views of the principle of the present invention. FIG. 1A shows a conventional mask, and FIG. 1B shows a mask of the present invention. In FIG. 1, 1 is a support frame and 2 is an original mask for drawing. Patterns, 3A and 3B are distorted patterns, 4 is a membrane, and 5 is a stretchable portion (destressed area).

FIG. 2 is a simulation result of the strain amount (S) at the time of stress release of the absorber film by the finite element method. In the figure, S is the strain amount, O is the center, and other symbols are those shown in FIG. 1 (b). ) Indicates the same object.

From the simulation results shown in FIG. 2, it can be seen that the strain amount of the absorber film deposited on the membrane by the sputtering method gradually increases from the central portion (O) toward the periphery at a uniform rate. .. Therefore, if the edge of the membrane can move freely, the absorber pattern formed at the center of the membrane should be distorted in a similar shape to the drawing pattern.

In the conventional mask shown in FIG. 1 (a), the original pattern 2 having a rectangular shape becomes a saddle-shaped distorted pattern 3A as shown in the figure because the periphery of the membrane 4 is fixed. Is.

Therefore, according to the present invention, as shown in FIG. 1 (b), the membrane 4 has a bellows-like shape along the inner circumference of the support frame 1 along the inner periphery thereof and has a uniform stretchability. The stress region 5 is provided to bring the edge of the membrane close to a state where it can move freely as described above. As a result, the distorted pattern 3B becomes almost similar to the original pattern 2 as shown in FIG.

Therefore, according to the present invention, the mask pattern can be easily and accurately corrected by multiplying the expansion / contraction ratio by the distortion amount at the time of pattern drawing, and a highly accurate ultrafine absorber is obtained. An X-ray mask having a pattern is provided.

Therefore, by performing X-ray exposure using the X-ray mask according to the present invention, it is possible to improve the performance and yield of VLSI having an ultrafine pattern and having a high density.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be specifically described below with reference to sectional views of manufacturing steps shown in FIGS.
It should be noted that the dimensions in the drawings do not show exact dimensional ratios.

Referring to FIG. 3A, in forming the X-ray mask according to the present invention, first,
At the position that hits the peripheral part of the membrane on the surface of the Si substrate 11,
For example, at a pitch of 20 to 30 μm, depth of 20 to 30 μm, width
For example, two grooves 23A and 23B of about 20 to 30 μm are formed in a concentric shape (see FIG. 1 (b)).

Next, as shown in FIG. 3 (b), a source gas is formed on the surface of the Si substrate 11 as in the conventional case.
A SiC film 12 for a membrane having a thickness of about 2 to 3 μm is formed by a CVD method using SiHCl ₃ and C ₃ H ₈ , and then this Si substrate is formed.
An etching mask SiC 13 having a thickness of about 2 to 3 μm is formed on the back surface of 11 by the same method as described above, and then a thickness of about 0.5 to 1 μm to be an X-ray absorber is formed on the above SiC film 12 for a membrane by a sputtering method. A Ta film 14 is formed.

Next, as shown in FIG. 3 (c), the SiC film 13 for the etching mask is formed as in the conventional case.
Etching window 15 for forming a window for light transmission on the Si substrate 11
After forming, the Si substrate 11 is used as the etching mask.
The SiC film 13 is faced down and bonded onto the ceramic support frame 16.
17 indicates an adhesive.

Next, as shown in FIG. 4 (a), the second transparent window of the ceramic support frame 16 is formed as in the conventional case.
18 and through the etching window 15 through the etching mask SiC film 13 as a mask, the Si substrate 11 is back-etched 19 with a fluorinated nitric acid-based solution, and the Si substrate 11 is formed into the concentric grooves 23A. The first transparent window 20 is formed on the Si substrate 11 by selectively removing the region having 23B in the peripheral portion.
To form. Here, a concentric bellows-shaped bent portion is provided in the peripheral portion.
A SiC membrane 12M having a de-stressed region 25 constituted by 24 is adhesively stretched on a ceramic support frame 16 via a Si support frame 11F.
The X-ray mask blanks 21 peculiar to the present invention having the film 14 deposited thereon are completed.

Next, referring to FIG. 4 (b), an EB resist film 22 is formed on the Ta film 14 of the mask blank 21, and the original pattern size and pattern space size to be formed on the resist film 22 are set. The Ta film 14 is subjected to drawing exposure of a pattern by an electron beam according to correction data obtained by multiplying a distortion rate (expansion / contraction rate) corresponding to each position based on the simulation result of FIG. A similar-shape correction resist pattern 22P corresponding to the correction data is formed on the top.

Next, referring to FIG. 4C, the Ta film 14 is patterned by anisotropic dry etching means, for example, reactive ion etching using a chlorine-based gas, using the resist pattern 22P as a mask. 22P removed and Si support frame 51 bonded on ceramic support frame 56
According to the present invention, the Ta pattern 14P of the X-ray absorber is formed on the SiC membrane 12M which is stretched over the F and has a de-stressed region 24 which is formed of concentric bellows-shaped bent portions 23 in the peripheral portion. The X-ray mask 26 is completed.

The Ta pattern 14P formed by patterning and being released from the stress of the Ta film 14 has a de-stressed region 25 composed of concentric bellows-shaped bent portions 24 at the periphery of the membrane 12M. Since the open end by the simulation shown in 2 is approached, the correction resist pattern 22P is distorted (expanded and contracted) in a similar shape to be well aligned with the original pattern size and the pattern space size to be formed. High-precision Ta pattern (mask pattern) 14
P.

In the above embodiment, an example in which Ta is used for the X-ray absorber has been described, but the present invention is applicable to other materials for the X-ray absorber, such as tungsten (W), gold (Au), or those materials. Of course, it also applies when using alloys.

Further, in the embodiment, the de-stressed region for giving stretchability to the peripheral portion of the membrane is constituted by the bellows-shaped bent portion of the membrane, but the de-stressed region is not limited to the constitution of the embodiment. Of course, other configurations, such as thinning the membrane thickness of that portion, may be used.

As described above, the X-ray mask according to the present invention has high pattern accuracy. Therefore, by using the X-ray mask according to the present invention, the resist film formed on the substrate to be processed is subjected to X-ray exposure of the mask pattern, and the resist pattern obtained by developing the resist film is used as a mask to perform etching means. By patterning various thin films on the substrate to be processed, it becomes possible to form a substrate to be processed having a highly precise ultrafine thin film pattern, and it is possible to improve the quality and manufacturing yield of VLSIs having an ultrafine pattern. ..

[0031]

As described above, in the present invention, the edge of the membrane is made closer to the free end by forming the de-stressed region in the peripheral portion of the membrane to give elasticity.
This made the relationship between the absorber pattern after distortion and the original pattern similar.

Therefore, according to the present invention, it is possible to easily and highly accurately correct a pattern only by multiplying the original pattern by the expansion / contraction rate when the pattern is drawn.
It is effective in improving the performance and manufacturing yield of a semiconductor device having an ultrafine pattern such as an LSI.

[Brief description of drawings]

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

FIG. 2 is a simulation diagram of the strain amount when the stress of the absorber film is released.

FIG. 3 is a process sectional view (1) of an embodiment of a manufacturing method according to the present invention.

FIG. 4 is a process sectional view of an example of the manufacturing method according to the present invention (No. 2)

FIG. 5 is a process sectional view of a conventional X-ray mask manufacturing method.

[Explanation of symbols]

 1 Support frame 2 Original patterns 3A, 3B Distorted pattern 4 Membrane 5 Stretchable area (de-stressed area) S Strain amount O center

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location G03F 7/20 521 7818-2H

Claims (4)

[Claims] 1. An X-ray mask in which a membrane is stretched on a cylindrical support frame, and an absorber pattern serving as a mask is formed on the membrane, wherein an inner periphery of the support frame is provided around the membrane. An X-ray mask having a uniform de-stressed region having a mechanical stretchability greater than that of the exposed region of the membrane. 2. The X-ray mask according to claim 1, wherein the de-stressed region is formed by a bellows-shaped bent portion formed in the membrane in a concentric shape along an inner circumference of the support frame. .. 3. A step of forming a single or a plurality of grooves concentrically on the surface of a silicon substrate, and depositing a membrane material film on the surface of the silicon substrate having the groove and on the inner surface of the groove. A step of depositing an absorber film on the membrane material film, a center of the silicon substrate so that a region of the silicon substrate outside the groove separated from the groove is left concentrically with the groove. Part is selectively removed from the back surface by etching to form a cylindrical silicon support frame made of the silicon substrate on the upper surface of which the peripheral portion of the membrane material film is fixed, and the X-ray inside the silicon support frame is formed. A step of forming a single or a plurality of bellows-shaped bent portions along the inner surface of the silicon support frame in a laminated film of an absorber and a membrane material; forming a resist film on the X-ray absorber film; And a step of drawing and exposing a pattern whose size and position are similarly corrected in consideration of the expansion and contraction rate of the bellows-shaped bent portion by an electron beam, using the resist pattern formed by developing the resist film as a mask. A method for manufacturing an X-ray mask, comprising a step of patterning the X-ray absorber film to form a mask pattern made of the X-ray absorber film. 4. A method of manufacturing a semiconductor device, which comprises a step of performing X-ray exposure on a resist film formed on a semiconductor substrate by using the X-ray mask according to claim 1.