JP2882127B2 - X-ray mask manufacturing method - Google Patents

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 used for, for example, X-ray lithography.

[0002]

2. Description of the Related Art FIGS.
FIG. 2 is a cross-sectional configuration diagram illustrating a conventional method of manufacturing an X-ray mask described in Japanese Patent No. 188909 in the order of steps. In the figure, 1 is a silicon substrate, 2 is a SiC membrane, 3 is a support ring, and 4 is an X-ray absorber.

In a conventional X-ray mask, first, a polycrystalline or single-crystal SiC membrane 2 serving as a membrane is grown on a silicon substrate 1, and then the surface of the SiC 2 is flattened by mirror polishing (FIG. 6 (a)). )) Then, a mask pattern made of the X-ray absorber 4 is formed on the SiC 2 (FIG. 6).
(B)).

[0004]

SUMMARY OF THE INVENTION The conventional X as described above
The method of manufacturing a line mask has a problem that the surface is not flattened unless the surface of the membrane 2 is sufficiently polished. When the surface of the SiC membrane 2 is not completely flat, when the X-ray absorber 4 is formed thereon by sputtering, the crystal structure tends to become a columnar structure as shown in a micrograph of the crystal in FIG. There has been a problem that the X-ray blocking ability is reduced due to a decrease in the density of the body 4 and etching is easily performed in units of columns, which causes a reduction in processing accuracy at the time of patterning. Further, in the conventional example, there is also a problem that the transmittance of visible light is reduced because the antireflection film is not coated for antireflection, and the alignment efficiency is reduced. In FIG. 7, 10
KV is the accelerating voltage of the scanning electron microscope, 40.6K × is a magnification of 40,600, 246n is the line length just above it is 246.
It corresponds to nm. 0262 is a film number.

The present invention has been made to solve such a problem, and has an object to improve the X-ray blocking ability of an absorber,
Further, it aims at improving the processing characteristics and improving the alignment efficiency.

[0006]

According to the present invention, there is provided a method of manufacturing an X-ray mask, comprising: a step of spin-coating a liquid on an upper surface of an uneven membrane and baking the liquid to obtain a flat anti-reflection film; X on the antireflection film
The step of forming a mask pattern made of a line absorber is performed.

A step of forming a first anti-reflection film on the membrane having irregularities by sputtering or vapor deposition;
A step of spin-coating a liquid on the first anti-reflection film and curing it by baking to obtain a flat second anti-reflection film; and a mask comprising an X-ray absorber on the second anti-reflection film. The step of forming a pattern is performed.

[0008]

In the present invention, since a flat anti-reflection film is obtained by spin-coating a liquid and baking to obtain a flat anti-reflection film, a flat film can be easily formed on the upper surface of the membrane even if it has irregularities. Since the base is flat, it is possible to form an X-ray absorber that is unlikely to have a columnar structure, thereby improving processing accuracy.
Further, the X-ray blocking ability also increases. Further, the transmittance of the alignment light is increased by the antireflection film, so that the alignment performance of the stepper is improved.

Further, a first material obtained by sputtering or vapor deposition is used.
The anti-reflection film has a higher purity than the flat second anti-reflection film obtained by spin-coating a liquid and performing baking to thereby improve anti-reflection characteristics.

[0010]

[Embodiment 1] FIGS. 1A and 1B are cross-sectional views showing a method of manufacturing an X-ray mask according to an embodiment of the present invention in the order of steps, and reference numerals 1, 3, and 4 are exactly the same as those in the conventional example. Reference numeral 2 denotes a membrane having an uneven surface such as SiC or diamond, and reference numeral 5 denotes an antireflection film formed by spin coating, for example, a silicon ladder polymer, SOG (spin-on-glass), a resist, or the like.

In the X-ray mask constructed as described above, first, a film of a membrane 2 such as SiC or diamond is formed on a silicon substrate 1, and then the surface of the membrane 2 is lightly polished as shown in FIG. I do. FIG. 1 (a)
Although the surface of the membrane 2 is shown as flattened by polishing in the example, in practice, it is sufficient to eliminate large irregularities. Thereafter, back etching of the silicon substrate 1 is performed.
Then, a silicone ladder polymer or S on both sides of the membrane 2
A liquid such as OG is spin-coated and baked to form an anti-reflection film 5 having a flat surface. Next, an X-ray absorber 4 such as tungsten is formed thereon. Thereafter, resist coating, exposure, development, and etching are performed, and the X-ray absorber 4 is patterned to complete an X-ray mask as shown in FIG. 1B. The support ring 3 may be adhered to the wafer at any step. However, in consideration of the distortion of the mask, it is better to attach the support ring after polishing and to perform back etching later.

In the above process, the antireflection film 5 is coated on both surfaces of the membrane 2 after performing the back etching. However, in the case of performing the patterning in a wafer state, the back etching is performed after the patterning. After that, the back surface is coated with the anti-reflection film 5.

This method is effective when the surface irregularities are particularly large like a diamond film. At the time of polishing, it is not necessary to polish the surface completely completely. If the surface is slightly smoothed, the smooth antireflection film 5 can be formed by spin coating. The polishing debris may be removed by a cleaning device such as a brush scrubber. However, at the time of spin coating, the substrate 1 may be rotated at a high speed before being coated with a silicon ladder polymer or the like, and may be flushed with alcohol or acetone.

Embodiment 2 FIG. When the unevenness of the membrane 2 is small, the method shown in FIG. 2 can be used without polishing the surface of the membrane 2. First, SiC is placed on the silicon substrate 1.
A film of the membrane 2 is formed. Next, back etching of the silicon substrate 1 is performed. Then, a liquid such as a silicon ladder polymer or SOG is spin-coated on both surfaces of the membrane 2 and baked to form an anti-reflection film 5 having a flat surface. Next, an X-ray absorber 4 such as tungsten is formed thereon. When the subsequent steps are performed in the same manner as in the first embodiment, an X-ray mask having a structure as shown in FIG. 2 is completed.

Embodiment 3 FIG. In each of the above embodiments, the silicon ladder polymer or SOG is applied directly on the membrane 2, but there is also a method of forming an antireflection film on the membrane 2 by sputtering or vapor deposition as shown in FIG. First, a membrane 2 having an uneven surface such as SiC or diamond is formed on a silicon substrate 1. Next, the silicon substrate 1 is back-etched to form a membrane 2. afterwards,
For example, SiO ₂ is sputtered or vapor-deposited on both surfaces of the membrane 2 to form a first antireflection film 6. At that time, the first
Since the surface of the antireflection film has irregularities, a liquid such as a silicon ladder polymer or SOG5 is spin-coated thereon and baked to form the second antireflection film 5 having a flat surface. Next, an X-ray absorber 4 such as tungsten is formed thereon. When the subsequent steps are performed in the same manner as in the first embodiment, an X-ray mask having a structure as shown in FIG. 3 is obtained.

According to this method, since the first antireflection film is formed by a sputtering method or a vapor deposition method, a high-purity film containing no organic substance can be formed, and the stress of the film can be controlled by changing the gas pressure. There is also a feature that it is easy to perform.

Embodiment 4 FIG. In the above embodiment, the anti-reflection films 5 and 6 on the front side of the membrane 2 are double coated, but as shown in FIG. Is also good.
In this method, the thickness of the second antireflection film 5 containing a large amount of impurities can be reduced, so that the durability against X-rays is improved.

Embodiment 5 FIG. In Examples 3 and 4, the second anti-reflection film 6 obtained by spin coating is used on the first anti-reflection film 6 obtained by sputtering or vapor deposition, and further, the second anti-reflection film is used. Although the surface of the film 5 is etched to smooth the surface, the surface of the sputtered or vapor-deposited film 6 may be lightly polished to form the spin coating film 5 as shown in FIG. That is, first, as shown in FIG. 5A, the first antireflection film 6 is formed on the film membrane 2 by sputtering or vapor deposition. Next, as shown in FIG. 5B, the surface of the first antireflection film 6 is polished, and the subsequent steps are performed in the same manner as in Example 3, to obtain an X-ray mask as shown in FIG. .

For reference, in the above description, the present invention is used for an X-ray mask. However, this method is used when it is desired to improve the light transmittance of a photomask or the like, or when the surface of the substrate is uneven. Needless to say, it can also be used when it is desired to make

[0020]

As described above, according to the present invention, a flat anti-reflection film is obtained by spin-coating and baking a liquid on the upper surface of the membrane having irregularities to cure it .
This one step realizes anti-reflection and flattening.
The X-ray absorber formed on the flat anti-reflection film is less likely to have a columnar structure, and as a result, the density is improved. It is possible to improve the X-ray blocking ability and the precision of fine processing.

A step of forming a first antireflection film by sputtering or vapor deposition on the membrane having irregularities;
A step of spin-coating a liquid on the first anti-reflection film and curing it by baking to obtain a flat second anti-reflection film; and a mask comprising an X-ray absorber on the second anti-reflection film. By performing the step of forming a pattern, the first antireflection film has higher purity than the second antireflection film, and the antireflection characteristics are further improved.

[Brief description of the drawings]

FIG. 1 is a sectional configuration view showing a method for manufacturing an X-ray mask according to Embodiment 1 of the present invention in the order of steps.

FIG. 2 is a cross-sectional configuration diagram illustrating an X-ray mask obtained according to a second embodiment of the present invention.

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

FIG. 4 is a cross-sectional configuration diagram illustrating an X-ray mask obtained according to a fourth embodiment of the present invention.

FIG. 5 is a sectional view showing a method of manufacturing an X-ray mask according to Embodiment 5 of the present invention in the order of steps.

FIG. 6 is a sectional configuration view showing a conventional method of manufacturing an X-ray mask in the order of steps.

FIG. 7 is a micrograph showing a crystal structure of an X-ray absorber of an X-ray mask obtained by a conventional method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Silicon substrate 2 Membrane 3 Support ring 4 X-ray absorber 5 Antireflection film formed by spin coating 6 Antireflection film formed by sputtering or vapor deposition

Continuing on the front page (72) Atsushi Aya, Inventor 8-1-1 Tsukaguchi Honcho, Amagasaki City Inside Central Research Laboratory, Mitsubishi Electric Corporation (72) Inventor Motoko Hashimoto 8-1-1, Tsukaguchi Honmachi, Amagasaki City Mitsubishi Electric Corporation (72) Inventor Nobuyuki Yoshioka 4-1-1 Mizuhara, Itami Mitsubishi Electric Corporation In-LSE Research Institute (56) References JP-A-3-204919 (JP, A) JP-A-2- 241019 (JP, A) JP-A-2-241020 (JP, A) JP-A-2-188909 (JP, A) JP-A-61-32425 (JP, A) JP-A-63-137424 (JP, A) JP-A-2-51216 (JP, A) JP-A-62-20310 (JP, A) JP-A-3-35239 (JP, A) JP-A-2-6387 (JP, A) JP-A-2-158734 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H01L 21/027

Claims (2)

(57) [Claims] 1. A step of obtaining a flat antireflection film by spin-coating and baking a liquid on an upper surface of an uneven membrane, and forming a mask pattern made of an X-ray absorber on the antireflection film. X to perform the forming process
Manufacturing method of line mask. 2. A step of forming a first antireflection film on a membrane having irregularities by sputtering or vapor deposition.
A step of obtaining a flat second anti-reflection film by spin-coating a liquid on the anti-reflection film and performing baking to cure the liquid;
And a method of manufacturing an X-ray mask, which comprises a step of forming a mask pattern made of an X-ray absorber on the second antireflection film.