JPH0482049B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a lithography method and a mask holder used therein.

[Conventional technology]

X-ray lithography has many advantages over conventional lithography using visible light and ultraviolet light, based on the straightness, non-coherence, and low diffraction properties unique to X-rays, and it has many advantages over submicron lithography. It is attracting attention as a powerful means of

Although X-ray lithography has many advantages over lithography using visible light and ultraviolet light, it suffers from insufficient power of the X-ray source, low sensitivity of the resist,
Due to difficulties in alignment, selection of mask materials, and processing methods, there are disadvantages of low productivity and high cost, and practical application has been delayed.

Looking at masks for X-ray lithography, in visible light and ultraviolet lithography, glass plates and quartz plates have been used as mask holders (i.e., light transmitting bodies); The available wavelength of light is 1 in
200 Å, and conventional glass plates and quartz plates have large absorption in this X-ray wavelength range and have to be thick, 1 to 2 mm, so they do not transmit enough X-rays. is unsuitable as a material for a mask holder for X-ray lithography.

Since X-ray transmittance generally depends on the density of a substance, inorganic and organic materials with low density are being considered as materials for mask holders for X-ray lithography. Examples of such materials include inorganic materials such as beryllium (Be), titanium (Ti), silicon (Si), and boron (B) alone and their compounds, and organic materials such as polyimide, polyamide, polyester, and parylene. It will be done.

In order to actually use this material as a material for a mask holder for X-ray lithography, it is necessary to make it a thin film in order to maximize the amount of X-ray transmission, and in the case of inorganic materials, it is less than a few meters. In the case of organic materials, it is required that the thickness be several tens of meters or less. For this reason, for example, when forming a mask holder made of an inorganic thin film or a composite film thereof, a thin film of silicon nitride, silicon oxide, boron nitride, silicon carbide, etc. is deposited on a silicon wafer with excellent flatness. A method has been proposed in which the silicon wafer is removed by etching after forming the silicon wafer.

On the other hand, as a mask for X-ray lithography (i.e., an X-ray absorber) held on the above-mentioned holder, a thin film of a material with high density, such as gold, platinum, tungsten, tantalum, copper, or nickel, is generally used. A thin film having a thickness of 0.5 to 1 m is preferable. Such a mask is made by, for example, uniformly forming a thin film of the high-density material on the X-ray transparent film, applying a resist, and drawing a desired pattern on the resist using an electron beam, light, etc.
Thereafter, a desired pattern is created using means such as etching.

However, in conventional X-ray lithography as described above, the X-ray transmittance of the mask holder is low, so in order to obtain a sufficient amount of X-ray transmission, the mask holder must be made considerably thinner. There was a problem that it became difficult to manufacture.

[Purpose of the invention]

SUMMARY OF THE INVENTION In view of the above-mentioned prior art, an object of the present invention is to provide a mask holder with good X-ray transparency so that lithography can be performed satisfactorily.

[Summary of the invention]

According to the present invention, the above object is to form a mask holder by a laminate of a film containing at least aluminum, nitrogen, and oxygen (hereinafter referred to as an Al-N-O film) and an inorganic substance. It is achieved by doing so.

〔Example〕

In the present invention, the inorganic film constituting the laminate may be at least film-forming and X-ray transparent. Examples of such inorganic substances include aluminum nitride, boron nitride,
Examples include silicon nitride, silicon oxide, silicon carbide, and titanium.

Among these, aluminum nitride is particularly suitable because it has the following characteristics: high X-ray transmittance and visible light transmittance, low coefficient of thermal expansion, high thermal conductivity, and good film formability. .

The laminate constituting the mask holder according to the present invention is
It may be composed of two layers, an Al-N-O film and an inorganic film, or it may be composed of two or more layers of at least one of an Al-N-O film and an inorganic film, resulting in a total of three or more layers. It may also be

Further, the laminate constituting the mask holder according to the present invention may be composed of three or more layers using an Al--N--O film, an inorganic film, and an organic film. As the organic material, it is possible to use at least a material having film formation and X-ray transparency, and examples of such organic material include polyimide, polyamide, polyester, parylene (manufactured by Union Carbide), etc. can.

The thickness of the mask holder according to the present invention is not limited and can be set to any suitable thickness, but it is advantageous to set it to about 2 to 20 m, for example.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Example 1: As shown in FIG. 1a, a silicon oxide film 2 with a thickness of 1 m was formed on both sides of a circular silicon wafer 1 with a diameter of 10 cm.

Next, as shown in Figure 1b, the plasma
After forming a silicon nitride film 3 with a thickness of 0.5 m on the silicon oxide film 2 on one side of the silicon wafer 1 by the CVD method, an aluminum (Al) target and an argon film were formed using a thermionic impact ion plating device. (Ar): Nitrogen (N ₂ ): Oxygen (O ₂ ) = 1:3:0.1 mixed gas, gas pressure 3×
10 ^-4 Torr, discharge power 40W, acceleration voltage 600V, substrate temperature 80℃, film formation rate of 10Å/sec, 1〓m thickness.
An Al--N--O based film 4 was formed.

Next, as shown in Figure 1c, Al-N-O
A protective tar-based paint layer 6 was formed on the film 4.

Next, as shown in FIG. 1d, the exposed circular center portion of the silicon oxide film 2 with a diameter of 7.5 cm was removed using a mixed solution of ammonium fluoride and hydrofluoric acid. At this time, in order to leave the ring-shaped silicon oxide film 2, a layer 7 of Apiezon wax (manufactured by Ciel Chemical Co., Ltd.) for protection is formed on that part, and after removing the central part of the silicon oxide film. , the wax layer 7 was removed.

Next, as shown in Figure 1e, electrolytic etching was performed in a 3% hydrofluoric acid aqueous solution (current density 0.2 A/dm ² ).
The exposed circular center portion of silicon wafer 1 with a diameter of 7.5 cm was removed.

Next, as shown in FIG. 1f, the exposed portion of the silicon oxide film 2 was removed using a mixed solution of ammonium fluoride and hydrofluoric acid.

Next, as shown in FIG. The surface of the silicon wafer 1 opposite to the surface on which the silicon nitride film 3 and the Al--N--O based film 4 were formed was bonded.

Next, as shown in FIG. 1h, the tar-based paint layer 6 was removed with acetone.

In this way, a lithography mask holder consisting of a laminate of the silicon nitride film 3 and the Al--N--O film 4 fixed by the ring frame 8 and the silicon wafer 1 was obtained.

The silicon nitride film obtained in this example: The mask holder having the structure of the Al--N--O based film had particularly good light transmittance.

Example 2: On one side of a circular silicon wafer with a diameter of 10 cm
After forming a 0.5 m thick silicon oxide film by CVD, a 1 m thick Al-N-O film was formed on the silicon oxide film in the same manner as in Example 1.

Next, in the same manner as in Example 1, a protective tar-based paint layer was formed on the Al--N--O based film.

Next, in the same manner as in Example 1, the circular center portion of the silicon wafer having a diameter of 7.5 cm was removed by electrolytic etching. At this time, in order to leave the silicon wafer in the form of a ring, a protective tar-based paint layer was formed on that part, and after removing the central part of the silicon wafer, the paint layer was removed.

Next, in the same manner as in Example 1, a ring frame was adhered to the surface of the silicon wafer opposite to the surface on which the silicon oxide film and the Al--N--O film were formed, and the tar-based material layer was removed.

In this way, the silicon oxide film and Al fixed by the ring frame and the silicon wafer
A lithography mask holder made of a laminate of -N-O based films was obtained.

Silicon oxide film obtained in this example;
The mask holder having the structure of the Al--N--O film had particularly good light transmittance.

Example 3: In the process of Example 1, after forming the silicon nitride film 3 and Al-N-O film 4, Al-N-
A tar-based paint layer was formed on the O-based film 4 for protection.

Thereafter, in the same manner as in Example 1, a predetermined portion of the silicon oxide film 2 and the circular center portion of the silicon wafer 1 were removed.

Next, the tar-based paint layer was removed with acetone.
Next, a photoresist AZ is applied on the Al-N-O film 4.
−1370 (manufactured by Shipley) was applied.

Next, the mask pattern was reduced and projected using a stepper, the resist was baked, and predetermined processing was performed to obtain a resist pattern.

Next, the above resist pattern is coated by vapor deposition.
A tantalum Ta layer was formed to a thickness of 0.5〓m.

Next, the resist was removed using acetone to obtain a tantalum film pattern.

Thereafter, the ring frame was bonded in the same manner as in Example 1, and the silicon nitride film and Al
A lithography mask using a mask holder made of a laminate with a -N-O film was obtained.

The mass silicon nitride film obtained in this example; the mask holder having the structure of an Al--N--O based film had particularly good light transmittance.

Example 4: In the process of Example 2, silicon oxide film and
After forming the Al-N-O film, a protective tar-based paint layer was formed on the Al-N-O film.

Thereafter, the same steps as in Example 3 were performed. In this way, the silicon oxide film and Al-N-O are fixed by the ring frame and the silicon wafer.
A lithography mask using a mask holder made of a laminate with a system film was obtained.

The silicon oxide film of the mask obtained in this example; the mask holder having a structure of an Al--N--O film had particularly good light transmittance.

Example 5: As shown in FIG. 2a, a silicon oxide film 2 with a thickness of 1 m was formed on both sides of a circular silicon wafer 1 with a diameter of 10 cm.

Next, as shown in Figure 2b, the plasma
After forming a silicon nitride film 3 with a thickness of 0.5 m on the silicon oxide film 2 on one side of the silicon wafer 1 by the CVD method, an aluminum nitride (AlN) target and an argon (Ar):nitrogen target were formed by the reactive sputtering method. (N ₂ ):Oxygen (O ₂ )=1:1:
0.5 mixed gas, gas pressure 5×10 ^-3 Torr, discharge power
1〓m thick Al− at 150W and deposition rate of about 15Å/min
An N--O film 4 was formed, and a silicon nitride film 5 having a thickness of 0.5 μm was further formed thereon by the plasma CVD method in the same manner as described above.

Next, as shown in FIG. 2c, a tar-based paint layer 6 was formed on the silicon nitride film 5 for protection.

Next, as shown in FIG. 2d, the exposed circular center portion of the silicon oxide film 2 with a diameter of 7.5 cm was removed using a mixed solution of ammonium fluoride and hydrofluoric acid. At this time, in order to leave the ring-shaped silicon oxide film 2, a layer 7 of Apiezon wax (manufactured by Ciel Chemical Co., Ltd.) for protection is formed on that part, and after removing the central part of the silicon oxide film. , the wax layer 7 was removed.

Next, as shown in Figure 2e, electrolytic etching was performed in a 3% hydrofluoric acid aqueous solution (current density 0.2 A/dm ² ).
The exposed circular center portion of silicon wafer 1 with a diameter of 7.5 cm was removed.

Next, as shown in FIG. 2f, the exposed portion of the silicon oxide film 2 was removed using a mixed solution of ammonium fluoride and hydrofluoric acid.

Next, as shown in Figure 2g, an epoxy adhesive 9 is applied to one side of the ring frame (manufactured by Pyrex, inner diameter 7.5 cm, outer diameter 9 cm, thickness 5 mm) 8, and the adhesive-applied surface is The surface of the silicon wafer 1 opposite to the surface on which the silicon nitride films 3 and 5 and the Al--N--O film 4 were formed was bonded.

Next, as shown in FIG. 2h, the tar-based paint layer 6 was removed with acetone.

Thus, the silicon nitride film 3 fixed by the ring frame 8 and the silicon wafer 1,
A lithography mask holder consisting of a laminate of No. 5 and Al--N--O film 4 was obtained.

Silicon nitride film obtained in this example;
The mass holder having a structure of an Al--N--O film; a silicon nitride film had particularly good light transmittance.

Example 6: After forming the Al-N-O film in the process of Example 2, a 0.5 m thick silicon oxide film was further formed by CVD, and a protective tar-based paint layer was applied on the silicon oxide film. The same steps as in Example 2 were carried out except for forming.

Thus, the silicon oxide film fixed by the ring frame and the silicon wafer;
A lithography mask holder consisting of a laminate having a structure of an N--O film and a silicon oxide film was obtained.

Silicon oxide film obtained in this example;
The mask holder having a structure of an Al--N--O film; a silicon oxide film had particularly good light transmittance.

Example 7: In the process of Example 1, before forming the silicon nitride film 3, a 1 μm film was deposited in the same manner as in Example 1.
Except for forming a thick Al-N-O film,
The same steps as in Example 1 were carried out.

In this way, a lithography mask holder consisting of a laminate having a structure of an Al-N-O film; a silicon nitride film; and an Al-N-O film fixed by the ring frame and the silicon wafer was obtained.

Al-N-O film obtained in this example;
The mask holder having a structure of a silicon nitride film; an Al--N--O film had particularly good heat dissipation properties.

Example 8: In the process of Example 2, except that an Al-N-O film with a thickness of 1㎜ was formed in the same manner as in Example 2 before forming the silicon oxide film.
The same steps as in Example 2 were carried out.

In this way, a lithography mask holder consisting of a laminate having a structure of an Al-N-O film; a silicon nitride film; and an Al-N-O film fixed by the ring frame and the silicon wafer was obtained.

Al-N-O film obtained in this example;
The mask holder having a structure of a silicon nitride film; an Al--N--O film had particularly good heat dissipation properties.

Example 9: In the process of Example 5, silicon nitride film 3,
After forming the silicon nitride film 5 and the Al--N--O film 4, a protective tar-based paint layer was formed on the silicon nitride film 5.

Thereafter, in the same manner as in Example 5, a predetermined portion of the silicon oxide film 2 and a circular center portion of the silicon wafer were removed.

Next, the tar-based paint layer was removed with acetone.

Next, a layer of photoresist RD-200N (manufactured by Hitachi Chemical) was formed on the silicon nitride film 5 by spin coating to a thickness of 1.2 m.

Next, the resist was baked using deep ultraviolet light using a quartz-chrome mask, and then prescribed processing was performed to obtain a negative resist pattern on the mask.

Next, tantalum Ta was evaporated to a thickness of 0.5 m on the resist pattern using an electrobeam evaporator.

Next, remove the resist using a remover,
Tantalum film turns were obtained by lift-off method.

Thereafter, the ring frame was bonded in the same manner as in Example 5, and the silicon nitride film fixed by the ring frame and silicon wafer was bonded.
A lithography mask was obtained using a mask holder made of a laminate with an Al--N--O film.

The mask holder having the structure of a silicon nitride film, an Al--N--O film, and a silicon nitride film of the mask obtained in this example had particularly good light transmittance.

Example 10: After silicon oxide films were formed on both sides of a silicon wafer in the same manner as in Example 5, an Al-N-O film was formed on one side thereof in the same manner as in Example 5.

Next, a protective tar-based paint layer was formed on the Al--N--O based film.

Thereafter, in the same manner as in Example 5, a predetermined portion of the silicon oxide film 2 and the circular center portion of the silicon wafer 1 were removed.

Next, the tar-based paint layer was removed with acetone.

Next, a chromium (Ct) film with a thickness of 300 Å was uniformly formed on the Al-N-O based film using a resistance heating evaporator, and then a gold (Au) film with a thickness of 0.5 μm was uniformly formed on the Al-N-O film. .

Next, photoresist AZ is uniformly applied on the metal film.
-1350 was applied to a thickness of 0.5〓m.

Next, a master mask was brought into close contact with the resist, and after the resist was baked using deep ultraviolet light, prescribed processing was performed to obtain a positive resist pattern for the master mask.

Next, metal was etched using an iodine (I ₂ )-based gold etchant to obtain a positive gold film pattern on the master mask.

Hereinafter, a ring frame was bonded in the same manner as in Example 5, and a lithography using a mask holder made of a laminate of an Al-N-O film and a chromium film fixed by the ring frame and a silicon wafer was performed. Obtained a mask for Yi.

Al-N- of the mask obtained in this example
The screen holder having the structure of O-based film and chromium film had particularly good X-ray transparency.

Example 11: In the process of Example 2, PIQ liquid (polyimide precursor, manufactured by Hitachi Chemical Co., Ltd.) was further applied on the Al-N-O film.
The same steps as in Example 2 were carried out, except that after spin coating, curing was performed at 50 to 350° C. for 4 hours to form a 2 μm thick polyimide film.

Thus, the silicon oxide film fixed by the ring frame and the silicon wafer;
A lithography mask holder consisting of a laminate having a structure of an N--O film and a polyimide film was obtained.

Silicon oxide film obtained in this example;
The mask holder having a structure of an Al--N--O film; a polyamide film had particularly high strength.

Example 12: A state fixed by a ring frame and a silicon wafer was obtained by using the same method as in Example 11, but by reversing the order of forming the silicon oxide film and forming the Al-N-O film. Al
A lithography mask holder was obtained, which was a laminate having a structure of -N-O film; silicon oxide film; and polyimide film.

Al-N-O film obtained in this example;
The mask holder having a structure of silicon oxide film and polyimide film had particularly high strength.

Example 13: By the same method as Example 11, except that Al-N-
By reversing the order of forming the O-based film and the polyimide film, a silicon oxide film fixed by the ring frame and the silicon wafer; a polyimide film; and an Al-N-O film are formed. A lithography mask holder made of a laminate was obtained.

The mask holder having the structure of silicon oxide film, polyimide film, and Al--N--O film obtained in this example had particularly high strength.

Example 14: When forming the Al-N-O film in Example 1, an aluminum nitride (AlN) target, argon (Ar):nitrogen ( _N2 ):oxygen (O ₂ )=1:1:0.5 gas, gas pressure 5×10 ^-3 Torr, discharge power 150W, film formation rate approx. 15
A mask holder for lithography was obtained by carrying out the same steps as in Example 1 except that the steps were carried out at a rate of Å/min.

Example 15: When forming the Al-N-O film in Example 1, an oxidized aluminum (7Al ₃ O ₇ :3AlN) target, argon (Ar):nitrogen ( N ₂ ):=1:1 gas, gas pressure 5×10 ^-3 Torr, discharge power 200W, film formation rate approx. 10
A mask holder for lithography was obtained by carrying out the same steps as in Example 1 except that the steps were carried out at a rate of Å/min.

Example 16: Instead of performing the step of forming a silicon nitride film in Example 1, an aluminum (Al) target and a mixed gas of argon (Ar):nitrogen (N ₂ )=1:1 were used by the reactive sputtering method. The same process as in Example 1 was carried out, except that the process of forming an aluminum nitride film 4 at a pressure of 0.5 m at a gas pressure of 8 x 10 ^-3 Torr and a discharge power of 200 W was carried out to form a lithography mask holder. Obtained.

The mask holder having the structure of the aluminum nitride film obtained in this example; Al-N-O film has X-ray transparency, visible light transparency, thermal conductivity,
Overall performance such as film formability was sometimes good.

Example 17: After the step of forming the aluminum nitride film in Example 16, a PIQ liquid (polyimide) precursor (manufactured by Hitachi Chemical Co., Ltd.) was spin coated and
Cure was carried out for 4 hours at .degree. C. to form a 2 .mu.m thick polyimide film.

Thus polyimide: aluminum nitride film;
A lithography mask holder having an Al--N--O film structure was obtained. The mask holder obtained in this example had particularly good strength and chemical resistance.

Example 18: After the step of forming the aluminum nitride film in Example 16, a reactive sputtering method was used to form the aluminum nitride film.
A step of forming a boron nitride film with a thickness of 0.5㎜ was performed.

Thus boron nitride; aluminum nitride; Al
A lithography mask holder having a -N-O film structure was obtained. The mask holder obtained in this example had particularly good X-ray transmittance and visible light transmittance.

〔Effect of the invention〕

According to the present invention as described above, the Al-N-O film used as a component of the mask holder has high X-ray transmittance and visible light transmittance (optical density of about 0.1 at a thickness of 1㎜), Low coefficient of thermal expansion (3~4×
10 ^-6 /°C), high thermal conductivity, and good film formability, so the following effects can be obtained.

(1) Since the Al-N-O film has high X-ray transmittance, a relatively high amount of X-ray transmission can be obtained even if it is relatively thick, so the mask holder can be manufactured easily and efficiently. .

(2) Since the Al-N-O film has good film formability, it is possible to manufacture a mask holder made of an extremely thin film, which increases the amount of X-ray transmission and improves the baking throughput. can.

(3) Since the Al-N-O film has a high transmittance to visible light, alignment can be easily and accurately performed visually using visible light in X-ray lithography. (4) Al-N-O film Since the coefficient of thermal expansion is approximately the same as the coefficient of thermal expansion (2 to 3 x 10 ^-6 /°C) of a silicon wafer printing substrate in X-ray lithography, extremely high precision printing is possible.

(5) Because the Al-N-O film has high thermal conductivity,
Ray irradiation can prevent temperature rise, and is particularly effective when baking in a vacuum. Also, Al
Since the -N-O film has high electrical conductivity, it can prevent the mask holder from being charged.

(6) By using a laminate of an Al-N-O film and an inorganic film, a mask holder can be created that has the properties of the inorganic film in addition to the properties of the Al-N-O film as described above. can do. That is,
The mask holder according to the present invention has the features of an inorganic film, such as excellent light transmittance and thermal conductivity, as well as relatively high strength and chemical resistance.

Furthermore, when an organic film is further laminated, the advantages of the organic film are added, such as high strength and virtually no stress.

[Brief explanation of the drawing]

1A to 2H are diagrams showing the manufacturing process of a mask holder for X-ray lithography according to the present invention. 1... Silicon wafer, 2... Silicon oxide film,
3, 5...Silicon nitride film, 4...Al-N-O based film,
6...Tar-based paint layer, 7...Wax layer, 8...Ring frame, 9...Adhesive.

Claims (1)

[Claims] 1. A mask held by a holder made of a laminate of a film containing at least aluminum, nitrogen, and oxygen and an inorganic film is used.
Lithography method. 2. A lithography mask holder comprising a laminate of a film containing at least aluminum, nitrogen, and oxygen and an inorganic film.