JP2001272769A - Photomask and method for manufacturing the same as well as method for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form mask patterns having partially different thicknesses. SOLUTION: Fullerene is first deposited by evaporation on the surface of a glass substrate 11 to form a vapor deposited fullerene film 13. The vapor deposited fullerene film 13 is irradiated with beams of a prescribed quantity by each of respective regions 13a, 13b and 13c and thereafter an organic solvent is supplied to the vapor deposited fullerene film 13 and the unreacted fullerene is dissolved away, by which the mask patterns 12 having the partially different thicknesses are obtained on the glass substrate 11. A resist film 36 on a semiconductor substrate 31 is exposed by using the thus resulted mask patterns 12 and the resist film 36 after the exposure is developed, by which the resist patterns 37 having the thicknesses partially varying in correspondence to the mask patterns 12 are obtained on an insulating film 32.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a photomask used for photolithography and a method for manufacturing the same, and a method for manufacturing a semiconductor device using the photomask.

[0002]

2. Description of the Related Art A semiconductor device manufacturing process includes a patterning process for processing an insulating film or the like formed on a semiconductor substrate into a fine pattern. This patterning step is performed by, for example, forming a resist pattern on an insulating film to be processed by a photolithography technique, etching the insulating film using the resist pattern as a mask, and removing unnecessary portions of the insulating film. Achieved.

In forming a resist pattern by photolithography, a photomask having a pattern corresponding to the desired resist pattern is used. That is, in the photolithography technique, after applying a photoresist on the entire surface of the insulating film, a photomask is arranged between the semiconductor substrate and an exposure light source provided opposite thereto, and in this state, The photoresist is exposed by emitting light from an exposure light source, and the exposed photoresist is developed with a developing solution to obtain a resist pattern.

[0004]

A typical photomask has a structure in which a light-shielding portion made of a metal such as Cr is pattern-formed on a transparent glass substrate, and a portion where the glass substrate is exposed is provided. Only the light incident on the light-shielding portion is transmitted, and the light incident on the light-shielding portion is blocked. Therefore, when such a photomask is used, only the light that reaches the exposed portion of the glass substrate is incident on the photoresist applied on the insulating film, and the incident portion of the light is substantially uniform. Exposed. Therefore, for example, when a positive photoresist is applied, the exposed portions are dissolved and removed with a developing solution, and a resist pattern having a substantially uniform thickness is formed on the insulating film.

When a semiconductor substrate on which a resist pattern is formed is subjected to, for example, reactive ion etching, the insulating film on the semiconductor substrate is etched into a shape corresponding to the resist pattern formed on the surface. Therefore, if the resist pattern is formed to have a partially different thickness, the insulating film on the semiconductor substrate is deeply etched in a region not masked by the resist pattern, and is masked by a relatively thin portion of the resist pattern. The region near the surface is thinly etched near the surface. By utilizing this, for example, a trench for embedding wiring and a contact hole communicating with the trench can be formed almost simultaneously in an insulating film on a semiconductor substrate, and the manufacturing process of the semiconductor device can be simplified. it can.

However, in the above-described photomask,
Since the amount of light incident on the photoresist on the insulating film cannot be partially changed, it is impossible to form a resist pattern having a partially different thickness. Accordingly, an object of the present invention is to provide a photomask capable of forming a resist pattern having a partially different thickness, a method for manufacturing the same, and a method for manufacturing a semiconductor device using the photomask.

[0007]

According to a first aspect of the present invention, there is provided a photomask for use in a photolithography technique, wherein a fullerene polymer is provided on a surface of a transparent substrate. Is a photomask characterized in that a mask pattern made of is formed. According to the present invention, the mask pattern on the transparent substrate is formed using a fullerene polymer that is a polymer of fullerene.

[0008] When a fullerene is irradiated with a UV (ultraviolet) laser beam or the like, a polymerization reaction occurs in a region irradiated with the beam, thereby forming a fullerene polymer insoluble in an organic solvent. And the polymerization reaction amount depends on the beam irradiation amount, and as the beam irradiation amount increases,
Many fullerene polymers are formed in the beam irradiation area, and the color (black) of the area is deepened. Therefore, by using fullerene (fullerene polymer) as a material for the mask pattern, a mask pattern having a light-shielding portion for blocking light and a semi-transmissive portion for semi-transmitting light can be formed. If the mask pattern has a light-shielding portion and a semi-transmissive portion, the photoresist film is exposed through a photomask on which the mask pattern is formed, and the exposed photoresist film is exposed. By developing, a resist pattern having different thicknesses in a portion corresponding to the light shielding portion and a portion corresponding to the semi-transmissive portion can be obtained.

Furthermore, if the resist pattern can be formed so as to have a partially different thickness, for example, a trench for wiring burying in an insulating film on the semiconductor substrate and a contact hole reaching from the trench to the semiconductor substrate. When a pattern is formed, a resist pattern corresponding to the pattern to be formed is formed, and a reactive ion etching process is performed on the semiconductor substrate on which the resist pattern is formed, so that the wiring embedding groove and the contact hole are formed. They can be formed almost simultaneously.

According to a second aspect of the present invention, there is provided a method of manufacturing a photomask used in a photolithography technique,
A photomask comprising: a step of attaching fullerene to the surface of a transparent substrate; and a step of polymerizing carbon atoms in the fullerene attached to the surface of the substrate to form a mask pattern made of a fullerene polymer. It is a manufacturing method of. According to this method, a photomask having the structure described in claim 1 can be manufactured.

According to a third aspect of the present invention, there is provided a method of manufacturing a semiconductor device by processing a film to be processed formed on a semiconductor substrate into a desired pattern. Forming a resist pattern corresponding to the desired pattern on the surface of the film to be processed by photolithography, and etching the semiconductor substrate on which the film to be processed and the resist pattern are formed after forming the resist pattern. Performing a process.

According to the present invention, by using the photomask according to the first aspect, it is possible to form a wiring embedding groove and a contact hole almost simultaneously in an insulating film as a film to be processed on a semiconductor substrate. become. Therefore, for example, it is possible to simplify the manufacturing process of a semiconductor device as compared with a method of forming a wiring embedding groove in a first photolithography process and then forming a contact hole in a second photolithography process. it can.

[0013]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an illustrative sectional view showing a method for manufacturing a photomask according to an embodiment of the present invention in the order of steps. This photomask 1
Is used, for example, in a photolithography technique performed in a manufacturing process of a semiconductor device, and has a structure in which a mask pattern 12 made of a fullerene polymer is formed on one surface 11a of a transparent glass substrate 11.

In the manufacturing process of the photomask 1, first, a fullerene vapor deposition film 13 is formed on one surface 11 a of the glass substrate 11. The formation of the fullerene vapor deposition film 13 is performed in the vapor deposition device 2 as shown in FIG. The vapor deposition apparatus 2 includes a processing chamber 2 that houses a material container 21 in which a fullerene powder is stored, and a heater 22 that heats and vaporizes the fullerene in the material container 21.
3 is provided. When depositing fullerene on the glass substrate 11, the glass substrate 11 is carried into the processing chamber 23, and is set above the material container 21 with the surface 11a on which fullerene is to be deposited facing downward. You. The fullerene in the material container 21 is vaporized by heating from the heater 22, and the vaporized fullerene adheres and deposits on the one surface 11 a of the glass substrate 11, so that fullerene vapor deposition occurs on the one surface 11 a of the glass substrate 11. A film 13 is formed.

Next, a step of processing the fullerene vapor-deposited film 13 thus formed on the glass substrate 11 into a mask pattern 12 is performed. Here, fullerene is a molecule composed of only carbon atoms represented by the chemical formula Cn (n is an even number of 32 or more), and is irradiated with a beam such as a UV (ultraviolet) laser beam, an electron beam, a proton beam, or an ion beam. Then, the carbon atoms polymerize in the irradiated region, and have a property of forming a carbon polymer (fullerene polymer) insoluble in an organic solvent such as toluene, benzene, hexane or carbon disulfide. The amount of polymerization reaction of carbon atoms depends on the amount of beam irradiation. As the amount of beam irradiation increases, more fullerene polymer is formed in the beam irradiation region, and the color (black) of the beam irradiation region changes. Darkens.

By utilizing such a property of fullerene, the fullerene vapor-deposited film 13 on the glass substrate 11 can be partially processed into a mask pattern 12 having a different thickness (and color). That is, the fullerene deposited film 13
A predetermined amount of fullerene is changed into a fullerene polymer in each region by adjusting the beam irradiation amount to each predetermined region. Thereafter, when unreacted fullerene is dissolved and removed with an organic solvent, a mask pattern 12 having a partially different thickness on the glass substrate 11 can be obtained.

For example, in FIG. 1B, a region of the fullerene vapor-deposited film 13 denoted by reference numeral 13a is irradiated with a beam of an amount necessary to convert all the fullerene in this region into a fullerene polymer. And reference numeral 13
The region indicated by b is irradiated with a smaller amount of beam than the beam irradiation amount on the region 13a. No beam is applied to the area indicated by reference numeral 13c. Then, in the region 13a, all the fullerenes are transformed into the fullerene polymer, and a relatively thick fullerene polymer film is formed on the glass substrate 11. In the area 13b,
Some fullerenes are transformed into fullerene polymers,
A relatively thin fullerene polymer film is formed on the glass substrate 11. In the region 13c, no reaction from fullerene to fullerene polymer occurs.

After the beam irradiation on the fullerene vapor-deposited film 13 is performed in this way, an organic solvent is supplied to the fullerene vapor-deposited film 13, and the fullerene remaining unreacted on the glass substrate 11 is dissolved with the organic solvent. Remove. Then, as shown in FIG. 1C, one side 1 of the transparent glass substrate 11 is formed.
A mask pattern 12 having a relatively thick portion 12a, a relatively thin portion 12b, and an opening 12c can be obtained in 1a.

The fullerene forming the fullerene vapor-deposited film 13 is, for example, buckminsterfullerene having the most stable structure among fullerenes (chemical formula: C
Preferably, ₆₀ ) is used. As a specific method of adjusting the beam irradiation amount to the fullerene vapor deposition film 13 for each predetermined region, for example, the fullerene vapor deposition film 1
In the case of scanning the upper surface 3 with an Nd-YAG (neodymium-yttrium-aluminum-garnet) laser beam, the scanning speed is adjusted for each region, and a beam irradiation amount per unit area in each region is controlled. Can be mentioned. In addition, by performing multiple exposure using a plurality of apertures having different opening patterns, the beam irradiation amount on the fullerene vapor deposition film 13 can be adjusted for each predetermined region.

Further, the manufacturing method in the case of forming the mask patterns 12 having two kinds of thickness on the glass substrate 11 has been described as an example, but the fullerene vapor deposition film 13 is formed on the glass substrate 11 and this fullerene vapor deposition film is formed. According to the method according to the present invention of forming a mask pattern by irradiating the beam 13 with a beam, it is also possible to form a mask pattern having three or more types of thicknesses on the glass substrate 11. FIG. 2 is an illustrative sectional view showing a method for manufacturing a semiconductor device using the photomask 1 in the order of steps. The manufacturing method shown in FIG. 2 is a so-called damascene method, in which a fine wiring embedding groove 33 is formed in an insulating film 32 laminated on a semiconductor substrate 31 by photolithography technology. This is a method in which a wiring 34 made of a metal such as copper is buried in the wiring 33. In this embodiment, in the step of forming the wiring embedding groove 33 by the photolithography technique, by using the photomask 1 having the structure as shown in FIG.
And the diffusion layer 31a of the semiconductor substrate 31 from the bottom of the groove 33.
And the contact hole 35 that has reached.

More specifically, after a positive photoresist is applied to the entire surface of the insulating film 32, a pre-exposure bake process is performed to form a resist film 36 on the insulating film 32. You. Next, the semiconductor substrate 31
Is carried into an exposure apparatus provided with an exposure light source (not shown) and the photomask 1, and a resist film 36 is formed on the glass substrate 11 of the photomask 1 as shown in FIG.
Are arranged so as to face each other. The exposure light source is disposed on the side of the photomask 1 facing the mask pattern 12 and irradiates the photomask 1 with substantially uniform UV (ultraviolet) light.

The portion 12a where the thickness of the mask pattern 12 is relatively large has a light-shielding property due to the dark black color.
The UV light applied to the light shielding portion 12a is
1 does not reach the resist film 36. Further, the portion 12b where the thickness of the mask pattern 12 is relatively small has a semi-transparent property due to the thin black color. %, And is incident on the resist film 36 on the semiconductor substrate 31. Further, the openings 12c of the mask pattern 12,
That is, the UV light applied to the portion of the photomask 1 where the glass substrate 11 is exposed passes through the glass substrate 11 almost completely, and enters the resist film 36 on the semiconductor substrate 31.

As a result, when the resist film 36 after the UV exposure is developed, the unexposed area (the area corresponding to the light shielding portion 12a of the mask pattern 12) of the resist film 36 is removed, and As shown in FIG. 2B, a resist pattern 37 having a shape corresponding to the mask pattern 12 is obtained. That is, a resist pattern 37 having a relatively thick thick film portion 37a, a relatively thin thin film portion 37b, and an opening 37c is formed on the semiconductor substrate 31.

Next, the semiconductor substrate 31 on which the resist pattern 37 has been formed is carried into an etching apparatus,
The semiconductor substrate 31 is subjected to, for example, a reactive ion etching process. In the etching process, first, the thick film portion 37a and the thin film portion 37b of the resist pattern 37 are etched substantially uniformly. At the same time, the insulating film 3
The region not covered by the second resist pattern 37, that is, the region facing the opening 37c of the resist pattern 37 is etched. Then, the etching process proceeds, and the thin film portion 37b of the resist pattern 37 is removed, thereby newly exposing the surface of the insulating film 32.
The newly exposed area is also etched. This etching process is performed on the thick film portion 37 of the resist pattern 37.
The process is completed when all of the “a” are removed. At this time, the wiring burying groove 33 and the contact hole 3 are formed in the insulating film 32.
5 is completed.

Thereafter, the wiring material such as copper is buried in the wiring buried groove 33 and the contact hole 35 thus formed, thereby forming the wiring buried groove 33 as shown in FIG. In this state, the wiring 34 connected to the diffusion layer 31a of the semiconductor substrate 31 through the contact hole 35 is obtained. As described above, according to this embodiment, the insulating film 32 on the semiconductor substrate 31 is provided with the groove 33 for embedding the wiring and the contact hole 35 communicating with the groove 33.
Can be formed almost simultaneously. Thus, for example, a first resist pattern having an opening corresponding to the wiring burying groove 33 is formed on the insulating film 32, and this first resist pattern is formed.
The trench 33 for wiring embedding is formed by performing an etching process using the resist pattern as a mask, and then the second trench having an opening corresponding to the contact hole 35 is formed.
The manufacturing process of the semiconductor device can be simplified as compared with the method of forming the contact hole 35 by forming the resist pattern and performing an etching process using the second resist pattern as a mask.

In this embodiment, the case where the wiring burying groove 33 and the contact hole 35 are formed in the insulating film 32 is taken as an example. However, for example, as shown in FIG. The present invention can also be applied to the case where the microlenses 42 are formed on the semiconductor substrate 41 that has been inserted. That is, after the fullerene vapor deposition film is formed on the glass substrate 51, the inside of the circular region set in the fullerene vapor deposition film is scanned with, for example, an Nd-YAG laser beam. At this time, a larger amount of beam is applied as the position approaches the center of the circular region. Thus, when the unreacted fullerene remaining on the glass substrate 51 is dissolved and removed with an organic solvent, a mask pattern 52 having a convex arc-shaped cross section is obtained on the glass substrate 51.

On the other hand, an SiO ₂ film 43 is formed on a semiconductor substrate 41.
Is formed, and a positive photoresist is applied to the entire surface of the SiO ₂ film 43, and then a pre-exposure bake process is performed to form a resist film 44. Then, as shown in FIG. 3A, the semiconductor substrate 41 on which the resist film 44 is formed is disposed so as to face the photomask 50 on which the mask pattern 52 is formed as described above. Thereafter, the resist film 44 is exposed through the photomask 50, and the exposed resist film 44 is developed, thereby forming a mask pattern 5 as shown in FIG.
2 can be obtained. Then, by performing a reactive ion etching process on the semiconductor substrate 41 on which the resist pattern 45 is formed, the SiO ₂ film 43 on the semiconductor substrate 41 corresponds to the resist pattern 45 as shown in FIG. After being processed into a shape, the micro lens 4 is formed on the semiconductor substrate 41.
2 can be obtained.

Although the embodiment of the present invention has been described above, the present invention can be embodied in other forms. For example, the material of the resist films 36 and 44 is not limited to a positive photoresist, and a negative photoresist may be used. In addition, various design changes can be made within the scope of the matters described in the claims.

[Brief description of the drawings]

FIG. 1 is an illustrative sectional view showing a method for manufacturing a photomask according to an embodiment of the present invention in the order of steps.

FIG. 2 is an illustrative sectional view showing a method for manufacturing a semiconductor device using the photomask in the order of steps;

FIG. 3 is an illustrative sectional view showing a method for manufacturing a semiconductor device having a microlens in the order of steps;

[Explanation of symbols]

Reference Signs List 1 photomask 11 glass substrate (transparent substrate) 11a one surface (transparent substrate surface) 12 mask pattern 12a light-shielding portion 12b semi-translucent portion 12c opening 13 fullerene vapor-deposited film 31 semiconductor substrate 32 insulating film (processed film) 37 resist pattern 41 semiconductor substrate 43 SiO ₂ film (film to be processed) 45 resist pattern 50 photomask 51 glass substrate (transparent substrate) 52 mask pattern

Claims (3)

[Claims] 1. A photomask used for a photolithography technique, wherein a mask pattern made of a fullerene polymer is formed on a surface of a transparent substrate. 2. A method for manufacturing a photomask used in a photolithography technique, the method comprising: attaching fullerene to a surface of a transparent substrate; and polymerizing carbon atoms in the fullerene attached to the surface of the substrate, Forming a mask pattern made of a fullerene polymer. 3. A method for manufacturing a semiconductor device by processing a film to be processed formed on a semiconductor substrate into a desired pattern, wherein the desired film is formed by a photolithography technique using a photomask according to claim 1. Forming a resist pattern corresponding to the pattern on the surface of the processed film; and, after forming the resist pattern, performing an etching process on the semiconductor substrate on which the processed film and the resist pattern are formed. A method for manufacturing a semiconductor device, comprising: