JPH0482048B2 - - 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 inherent straightness, non-coherence, and low diffraction properties of X-rays, and is superior to 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 the material,
Low-density inorganic and organic materials are being considered as materials for mask holders for X-ray lithography.
Examples of such materials include beryllium Be,
Inorganic substances such as titanium Ti, silicon Si, boron B units and their compounds, or polyimide,
Examples include organic materials such as polyamide, polyester, and parylene (manufactured by Union Carbide).

In order to actually use these materials as materials for mask holders for X-ray lithography, it is necessary to make them into thin films in order to maximize the amount of X-ray transmission. In the case of organic materials, it is required to form the layer to a thickness of 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, silicon nitride, silicon oxide, boron nitride, silicon carbide, etc. are deposited on a silicon wafer with excellent flatness. A method has been proposed in which the silicon wafer is removed by etching after forming a thin film.

On the other hand, X-ray lithography masks (i.e.,
A thin film of tungsten, tantalum, copper, nickel, etc., preferably with a thickness of 0.5 to 1 m, is preferred. Such a mask is, for example, the above-mentioned
After uniformly forming a thin film of the above-mentioned high-density substance on the line-transmitting film, a resist is applied, a desired pattern is drawn on the resist using an electron beam, light, etc., and then a desired pattern is formed using means such as etching. Created in a pattern.

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, it is an object of the present invention to provide a mask holder with good X-ray transparency, thereby enabling good lithography.

[Summary of the invention]

According to the present invention, the above object is to form a mask holder with a laminate of a film containing aluminum, nitrogen, and oxygen (hereinafter referred to as an Al-N-O film) and an organic film. achieved by.

〔Example〕

In the present invention, as the organic film constituting the laminate, one having at least film-forming properties and X-ray transparency can be used. Examples of such organic materials include polyimide, polyamide, polyester, parylene, etc. Among these, polyimide is particularly suitable because it has good overall performance such as heat resistance, impact resistance, and visible light transmittance. be.

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 organic film, or it may be composed of three or more layers using at least one of an Al-N-O film and an organic film. It may be something like that.

The thickness of the mask holder according to the present invention is not particularly limited and can be set to any appropriate 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 mm was formed on both sides of a circular silicon wafer 1 with a diameter of 10 cm.

Next, as shown in FIG. 1b, after spin-coating PIQ liquid (polyimide precursor, manufactured by Hitachi Chemical Co., Ltd.) on the silicon oxide film 2 on one side of the silicon wafer 1, A polyimide film 3 having a thickness of 2 m was formed by curing for a period of time.

Next _, as shown in FIG _.
= 1:3:0.1 gas, gas pressure 3 x 10 ^-4 Torr, discharge power 40 W, acceleration voltage 600 V, substrate temperature 80°C, film formation rate about 10 Å/sec, 2〓 on polyimide film 3.
An Al--N--O- based film 4 having a thickness of m was formed.

Next, as shown in Figure 1d, Al-N-O
A tar-based paint layer 10 was formed on the N--O based film 4 for protection.

Next, as shown in FIG. 1e, 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 6 of Apiezonx (manufactured by Ciel Chemical Co., Ltd.) is formed on that part for protection, and after removing the central part of the silicon oxide film, the wax is removed. Layer 6 was removed.

Next, as shown in Figure 1 f, 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. 1g, 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 polyimide film 3 and the Al--N--O film 4 were formed was adhered, and the tar-based paint layer 10 was removed.

In this way, the polyimide film 3 and the polyimide film fixed by the ring frame 7 and the silicon wafer 1 are
A lithography mask holder made of a laminate of Al--N--O based films 4 was obtained.

Polyimide film obtained in this example; Al
The mask holder having the structure of the -N-O film had particularly good strength.

Example 2: Silicon oxide film 2 on one side of silicon wafer 1
The same steps as in Example 1 were carried out, except that instead of the polyimide film 3, a 2 m thick polyester film was formed by vapor deposition.

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

The polyester film obtained in this example: The mask holder having the structure of the Al--N--O film had particularly good strength.

Example 3: The same steps as in Example 1 were performed except that a 2 μm thick parylene film was formed by vapor deposition on the silicon oxide film 2 on one side of the silicon wafer 1 instead of the polyimide film 3. Summer.

Thus, the parylene film and Al-N are fixed by the ring frame and the silicon wafer.
A lithography mask holder made of a laminate of -O-based films was obtained.

Parylene film obtained in this example; Al-
The mask holder having the structure of the N--O film had particularly good strength.

Example 4: In the process of Example 1, polyimide film 3 and
After forming the Al-N-O film 4, the Al-N-O
A layer of photoresist CMS (chloromethylated polystyrene, manufactured by Toyo Sota Co., Ltd.) was formed on the system film 4.

Next, a mask pattern was drawn using an electron beam drawing device, and then prescribed processing was performed to obtain a resist pattern.

Next, nickel was deposited to a thickness of 0.5 mm on the resist pattern using an electron beam evaporator.

Next, remove the resist using a remover,
A nickel film pattern was obtained.

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

Hereinafter, the same steps as in Example 1 were carried out to prepare a lithography mask using a mask holder made of a laminate of a polyimide film and an Al-N-O film fixed by a ring frame and a silicon wafer. Obtained.

The polyimide film in the lithography mask obtained in this example; the mask holder having an Al--N--O film structure had particularly good strength.

Example 5: In the process of Example 2, parylene film and Al
After forming the -N-O based film, a layer of photoresist CMS was formed on the Al-N-O based film.

Thereafter, the same steps as in Example 4 were performed.

Thus, the parylene film and Al-N are fixed by the ring frame and the silicon wafer.
A lithography mask using a mask holder made of a laminate of -O-based films was obtained.

The parylene film in the lithography mask obtained in this example; the mask holder having a structure of an Al--N--O film had particularly good strength.

Example 6: In the process of Example 3, parylene film and Al
After forming the -N-O based film, a layer of photoresist CMS was formed on the Al-N-O based film.

Thereafter, the same steps as in Example 3 were performed.

Thus, the parylene film and Al-N are fixed by the ring frame and the silicon wafer.
A lithography mask using a mask holder made of a laminate of -O-based films was obtained.

The parylene film in the lithography mask obtained in this example; the mask holder having a structure of an Al--N--O film had particularly good strength.

Example 7: As shown in FIG. 2a, a silicon oxide film 2 with a thickness of 1 μm was formed on both sides of a circular silicon wafer 1 with a diameter of 10 cm.

Next, as shown in FIG. 2b, after spin coating a PIQ liquid (polyimide precursor) on the silicon oxide film 2 on one side of the silicon wafer 1,
Curing was performed at 350° C. for 4 hours to form a polyimide film 3 with a thickness of 2 μm.

Next, as shown in FIG. 2c, an aluminum nitride AlN target, argon Ar: nitrogen N ₂ : oxygen O ₂ = 1:
1:0.5 gas, gas pressure 5×10 ^-3 Torr, discharge power
An Al--N--O film 4 having a thickness of 1 mm was formed on the polyimide film 3 at 150 W and a film formation rate of about 15 Å/min.

Next, as shown in Figure 2d, Al-N-O
A polyimide film 5 having a thickness of 2 μm was formed on the system film 4 in the same manner as described above.

Next, as shown in FIG. 2e, the exposed circular center portion of the silicon oxide film 2 having 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 6 of Apiezon wax (manufactured by Ciel Chemical Co., Ltd.) was formed for protection on that part, and the central part of the silicon oxide film 2 was removed. rear,
The wax layer 6 was removed.

Next, as shown in Figure 2 f, 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. 2g, 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. 2h, an epoxy adhesive 8 is applied to one side of the ring frame (manufactured by Pyrex, inner diameter 7.5 cm, outer diameter 9 cm, thickness 5 cm) 7, and the adhesive-applied surface is The surface of the silicon wafer 1 opposite to the surface on which the polyimide films 3 and 5 and the Al--N--O film 4 were formed was bonded.

In this way, the polyimide films 3 and 5 fixed by the ring frame 7 and the silicon wafer 1
A lithography mask holder made of a laminate of Al--N--O based films 4 was obtained.

Polyimide film obtained in this example; Al
-N--O film: The mask holder having a polyimide film structure had particularly good strength and chemical resistance.

Example 8: Same as Example 7, except that instead of the polyimide films 3 and 5, a 2-m thick parylene film was formed by vapor deposition on the silicon oxide film 2 on one side of the silicon wafer 1. The process was carried out.

Thus, the parylene film and Al-N are fixed by the ring frame and the silicon wafer.
A lithography mask holder made of a laminate of -O-based films was obtained.

Parylene film obtained in this example; Al-
The mask holder having the structure of N--O film; parylene film had particularly good strength and chemical resistance.

Example 9: Same as Example 7 except that instead of the polyimide films 3 and 5, a parylene film with a thickness of 2 μm was formed by vapor deposition on the silicon oxide film 2 on one side of the silicon wafer 1. A similar process was performed.

Thus, the parylene film and Al-N are fixed by the ring frame and the silicon wafer.
A lithography mask holder made of a laminate of -O-based films was obtained.

Parylene film obtained in this example; Al-
The mask holder having the structure of N--O film; parylene film had particularly good strength and chemical resistance.

Example 10: In the process of Example 7, polyimide films 3 and 5
After forming the Al--N--O film 4, a layer of positive photoresist AZ-1370 (manufactured by Shipley) was formed on the polyimide film 5 by spin coating to a thickness of 1 m.

Next, the resist is baked using deep ultraviolet light using a quartz mask, and then prescribed processing is performed.
A negative resist pattern was obtained for the mask.

Next, tantalum Ta was evaporated to a thickness of 0.5 μm on the resist pattern using an electron beam evaporator.

Next, remove the resist using a remover,
A tantalum film pattern was obtained by lift-off method.

Next, on the polyimide film 5, 2 layers are further added for protection.
A polyimide film of m thickness was formed.

Hereinafter, the same steps as in Example 7 were carried out to prepare a lithography mask using a mask holder made of a laminate of an Al-N-O film and a polyimide film fixed by a ring frame and a silicon wafer. Obtained.

Polyimide film in the lithography mask obtained in this example; Al-N-O based film;
The mask holder having a polyimide film structure had particularly good strength.

Example 11: Polyimide film (1〓m thickness); Al-N-O film (1〓m thickness); polyimide film (3〓m thickness); Al- N
-O-based film (1〓m thickness); Polyimide film (1〓m thickness)
A laminate consisting of five layers was formed.

Thereafter, the same process as in Example 7 was carried out to remove the circular central part of the silicon wafer and the silicon oxide film, and the exposed part of the polyimide film was removed using a hydrazine solvent. Glued the frame.

In this way, the Al-N-O film (1〓
A mask holder for lithography was obtained, which consisted of a three-layer laminate consisting of a polyimide film (3 m thick); an Al--N-O film (1 m thick).

The mask holder having the structure of Al-N-O film; polyimide film; and Al-N-O film obtained in this example had particularly good heat dissipation properties.

Example 12: The same steps as in Example 11 were performed except that a parylene film was formed by vapor deposition instead of the polyimide film.

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

The mask holder having the structure of Al--N--O film; parylene film; and Al-N--O film obtained in this example had particularly good heat dissipation properties.

Example 13: The same steps as in Example 11 were performed except that a parylene film was formed by vapor deposition instead of the polyimide film.

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

The mask holder having the structure of Al--N--O film; parylene film; and Al-N--O film obtained in this example had particularly good heat dissipation properties.

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

〔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) The thermal expansion coefficient of the Al-N-O film is almost the same as that of the silicon wafer-baked substrate in X-ray lithography (2 to 3 x 10 ^-6 /°C), so it can be used with extremely high accuracy. It becomes possible to print

(5) Because the Al-N-O film has high thermal conductivity,
It can prevent temperature rise due to radiation irradiation, and is particularly effective when baking in a vacuum.

(6) By using a laminate of an Al-N-O film and an organic film, a mask holder can be created that has the characteristics of the organic film in addition to the characteristics of the Al-N-O film as described above. can do. That is,
In addition to the effects of a mask holder made of an Al--N--O film, the mask holder according to the present invention has the advantage of being high in strength and virtually stress-free.

[Brief explanation of the drawing]

1A to 2H are diagrams showing the manufacturing process of a mask holder for lithography according to the present invention. 1: silicon wafer, 2: silicon oxide film,
3, 5: Polyimide film, 4: Al-N-O based film,
6: wax layer, 7: ring frame, 8: adhesive, 10: tar-based paint layer.

Claims (1)

[Scope of Claims] 1. A lithography method characterized by using a mask held by a holder made of a laminate of a film containing aluminum, nitrogen, and oxygen and an organic film. 2. A mask holder for lithography, comprising a laminate of a film containing aluminum, nitrogen, and oxygen and an organic film. 3. The lithography mask holder according to claim 2, wherein the organic film is a polyimide film.