JPH0722304A - Fine pattern forming material and pattern forming method - Google Patents

Abstract

(57) [Abstract] [Purpose] The present invention relates to a fine pattern forming material and a forming method using a photolithography technique for fine processing of a semiconductor device, which facilitates silylation for performing highly selective dry development. A good fine pattern is formed. [Structure] A latent image 15 is formed by irradiating ultraviolet rays 14 on a film 13 to be processed on a semiconductor silicon substrate 11. When this is immersed in the solution of the liquid-phase silylating agent forming the hydrophobic micelle 16, the hydrophobic micelle 16 is adsorbed only on the unexposed portion 17. When this is dry-developed with O ₂ gas, a resist pattern 18 is formed. Then, by using the pattern 18 as a mask and etching with CF ₄ gas, the fine pattern 19 could be formed accurately and vertically.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fine pattern forming material used for patterning and manufacturing a semiconductor element or an integrated circuit by using a photolithography technique such as ultraviolet rays.
It also relates to a fine pattern forming method using the same material.

[0002]

2. Description of the Related Art Conventionally, when patterning a resist,
Wet development is carried out by immersing the exposed part in an alkaline solution in the case of a positive type resist and by dissolving the unexposed part in an organic solvent in the case of a negative type resist, but in the wet method the resist is exposed and unexposed. Since the dissolution rate ratio of the part is used, it is necessary to improve the dissolution rate ratio in order to obtain a vertical pattern. However, at present, there is no resist having a dissolution rate ratio capable of forming a sufficient pattern by the wet method, and patterning the resist causes a problem that the pattern has an inclination, which makes microfabrication difficult.

Therefore, in recent years, in order to solve this problem,
Dry development using a dry etching method has been devised. The dry development method is a pattern formation method in which the resist surface on which a latent image is formed by exposure is converted into a silicon compound having high etching resistance (called silylation), and this is used as a mask for dry etching. The silylation increases the difference in speed between the exposed and unexposed areas with respect to dry etching, and the unexposed areas can be easily developed using O ₂ gas, leaving only the pattern of the silylated exposed areas. Is possible. Since such a silylated resist can be easily dry-developed, it causes problems such as swelling and taper of the resist pattern as in wet development, and environmental and human problems caused by the organic solvent developer. It is considered that it is possible to form an accurate and high-resolution fine pattern.

As one of the silylation methods, dimethylsilyldimethylamine, 1,1,3, is used as a gas phase silylation method.
There is a method in which 3-tetramethyldisilazane, hexamethyldisilazane, N, N-dimethylaminotrimethylsilane, etc. are made into a gas under a nitrogen stream and sprayed on the upper part of the resist pattern for coating.

Further, recently, bis (dimethylamino)
A liquid-phase silylation method in which the resist pattern is applied to the upper portion of the resist pattern by immersing it in a solution of dimethylsilane, 1,1,3,3,5,5-hexamethylcyclotrisilazane, or the like.

The conventional silylation forming material and resist pattern forming method will be described below.

The silylating agents used as conventional silylating materials are dimethylsilyldimethylamine, 1,1,3,3-tetramethyldisilazane, hexamethyldisilazane, N, N in the gas phase silylation method. -Dimethylaminotrimethylsilane (Chemical formula 1) and the like.

[0008]

[Chemical 1]

FIG. 4 shows a method of gas phase silylation. First, a resist 41 is applied to the film to be processed 13 on the semiconductor silicon substrate 11 (FIG. 4A). It is exposed to ultraviolet rays 14 to form a latent image 42 (FIG. 4).
(B)). Next, the unexposed portion 43 of the resist after exposure is heated to about 150 ° C. by the hot plate 44 and cured to prevent the silylating agent from binding to the unexposed portion (FIG. 4).
(C)). Further, the above-mentioned silylating agent is converted into the vapor phase silylating agent 45 under a nitrogen stream, and is sprayed onto the exposed portion to be vapor-deposited (FIG. 4D). Then, the unsilylated portion is dry-developed with O ₂ gas using the silylated portion 46 as a mask to form a resist pattern 47 (FIG. 4E).
Then, using this resist pattern 47 as a mask, CF
_The fine pattern 48 is formed by etching the film 13 to be processed with ₄ gases (FIG. 4D).

In the liquid phase silylation method, bis (dimethylamino) dimethylsilane and 1,1,3,3,5,5-hexamethylcyclotrisilazane (Chemical Formula 2) are used as silylating agents.

[0011]

[Chemical 2]

FIG. 5 shows a liquid phase silylation method. First, a resist 51 is applied on the film 13 to be processed on the semiconductor silicon substrate 11 (FIG. 5A). It is exposed to ultraviolet light 14 to form a latent image 52 (FIG. 5).
(B)). Next, in the beaker 53, the semiconductor silicon substrate is immersed in the solution 54 of the liquid-phase silylating agent described above, and while the resist is heated at about 50 ° C. by the hot plate 45, the silylating agent is applied only to the exposed portion. Adsorb (Fig. 5
(C)). Then, using the silylated portion 55 as a mask, the resist in the unsilylated portion is dry-developed with O ₂ gas to form a resist pattern 56 (FIG. 5).
(D)). Then, the resist pattern 56 is used as a mask to etch the film to be processed 13 with CF ₄ gas to form a fine pattern 57 (FIG. 5E).

With the conventional silylation method and resist pattern forming method configured as described above, the current line width of 0.
A pattern of up to 30 μm is formed.

[0014]

However, in the conventional resist pattern type method described above, in the vapor phase silylation method, the silylating agent is sprayed onto the upper portion of the resist pattern in a gaseous state, and the liquid phase silylation method is also used. However, since it is immersed in a solution and silylated by adsorption, it is difficult to apply it only to an exposed area or an unexposed area, and there is a problem in terms of selectivity in dry etching. Furthermore, the vapor phase silylation method has a very complicated process and tends to use a simple liquid phase silylation method.

The present invention solves the above-mentioned conventional problems of selectivity, and an object thereof is to improve the selectivity of the silyl compound by chemically adsorbing the silyl compound.

Further, by applying the liquid phase silylation method,
It is intended to simplify the process.

[0017]

To achieve this object, the fine pattern forming material of the present invention comprises a hydrophobic group and a hydrophilic group, and the surfactant is rapidly associated with each other by increasing the concentration. It is characterized in that a silicon-based surfactant that easily forms micelles that are molecular aggregates is used as a material for silylating the upper part of the resist. Also preferably, the silicone-based surfactant is ionic,
When the micelles are formed, they become spherical micelles, and the hydrophobic part of the spherical micelle facing outward in a hydrophobic solvent is adsorbed to the hydrophobic part of the resist. Further, desirably, the silicone-based surfactant is ionic and becomes spherical micelles when micelles are formed, and the hydrophilic portion of the spherical micelle facing outward in a hydrophilic solvent is chemically bonded to the hydrophilic portion of the resist ( It is also characterized by adsorbing with (hydrogen bond).

The fine pattern forming method of the present invention is
A step of applying a photosensitive polymer film on a film to be processed on a semiconductor substrate to form a resist film, a step of exposing the resist to form a latent image, and a step of forming the latent image on the resist film. A step of immersing in a solution of a silicon-based surfactant consisting of a hydrophobic group and a hydrophilic group, and adsorbing a silicon-based hydrophilic spherical micelle on the resist upper part of the exposed portion; A step of dry-developing a non-adsorbed portion to form a resist pattern, and a step of etching a film to be processed to form a fine pattern using CF ₄ gas using the resist pattern as a mask Is.

The fine pattern forming method of the present invention is
The step of applying a photosensitive polymer film on the film to be processed on the semiconductor substrate to form a resist film, the step of exposing the resist to form a latent image, and the resist film having the latent image formed thereon A step of immersing the silicon-based hydrophobic spherical micelle in a solution of a silicon-based surfactant composed of a hydrophobic group and a hydrophilic group, and adsorbing the silicon-based hydrophobic spherical micelle on the resist in the unexposed area; And a step of forming a resist pattern by dry developing the non-adsorbed portion of the film and a step of forming a fine pattern by etching the film to be processed with CF ₄ gas using the resist pattern as a mask. It is a thing.

That is, by applying a micelle having a hydrophobic property and a hydrophilic property, and further having a property that the hydrophobic part is adsorbed to the hydrophobic part and the hydrophilic part is adsorbed to the hydrophilic part, as a silylation material of the resist pattern, When the ends of the positive resist molecule are converted to hydroxyl groups that are hydrophilic only in the exposed areas and hydrophobic micelles are used, the hydrophobic areas outside the micelles are the unexposed areas of the resist and the hydrophilic micelles. In the case of using, the hydrophilic part outside the micelle is adsorbed to the exposed part of the resist along with hydrogen bonding. Since the bond in this case uses a chemical bond, the selectivity becomes extremely high, and an accurate fine pattern can be obtained.

[0021]

According to the present invention, by the above method, the hydrophobic or hydrophilic micelle reacts with the exposed or unexposed portion of the resist in the liquid phase with high chemical selectivity, so that the silylated mask can be easily formed. Will be formed.

[0022]

EXAMPLES Before describing the examples of the present invention, the outline of the present invention will be described.

According to the present invention, a resist is applied on a semiconductor silicon substrate and is irradiated with ultraviolet rays to form a pattern. The resist used at this time is a positive type resist, which can be alkali-developed by being irradiated with ultraviolet rays and converted into a substance having a hydrophilic hydroxyl group at the terminal of the molecule. When it is immersed in a micelle solution, which is a molecular assembly of hydrophobic surfactants, and then spin-dried, the silicon-containing micelles are adsorbed only on the hydrophobic, unexposed resist portion. In addition, when immersed in a micelle solution that is hydrophilic and treated by spin drying in the same manner, the silicon-containing micelles are adsorbed with hydrogen bonds only in the exposed areas that are hydrophilic, which cannot be obtained by the conventional method. The present invention also provides a method of highly selectively silylating unexposed areas or only exposed areas.

Here, the surfactant is a substance that gathers at the interface between two phases and changes the properties of the interface.
As shown in (1), it is composed of a hydrophobic portion 31 and a hydrophilic portion 32, and is used as an emulsifier and a detergent. When the concentration of this surfactant exceeds a certain level, it rapidly associates with each other to form a molecular assembly (called a micelle). At this time, the arrangement in which the hydrophilic portions 32 are oriented toward the micelle surface and the hydrophobic portions 31 are oriented toward the inside of the micelles is called a positive micelle (FIG. 3B) and is formed in a hydrophilic solvent. The reverse is called reverse micelle (FIG. 3 (c)), which is formed in a hydrophobic solvent. Applying this principle,
When the hydrophilic micelle 21 is adsorbed to the portion 33 that has been converted into a hydrophilic group by exposure, it becomes as shown in FIG. 3 (d),
Further, when the hydrophobic micelles 16 are adsorbed to the unexposed portion 35, it becomes as shown in FIG.

(Embodiment 1) An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a method of forming a fine pattern by silylating the resist of the first embodiment.

First, a chemically amplified positive type resist 12 is applied on a film 13 to be processed formed on a semiconductor silicon substrate 11 (FIG. 1A). The high molecular weight organic compound used as the main polymer used in the resist 12 and the acid generator capable of generating an acid upon irradiation with ultraviolet rays have a structure shown in (Chemical Formula 3).

[0028]

[Chemical 3]

Then, the applied resist is irradiated with ultraviolet rays 14 to change the polarity of the main polymer to convert the terminal to a hydrophilic hydroxyl group (chemical formula 3) and form a latent image 15 (FIG. 1 (b)). .

Next, a silicon-based surfactant having a structure as shown in Chemical formula 4 was added to n-heptane at 5 mol / cm ² × 1.
The exposed resist was immersed for 2 minutes in a solution that was dissolved at a concentration of 0 ¹⁰ or more to form hydrophobic micelles (see FIG. 1).
(C)). At this time, the hydrophobic micelle 16 is adsorbed to the unexposed portion 17 of the hydrophobic resist.

[0031]

[Chemical 4]

Then, in order to dry the solvent n-heptane, spin drying was performed at 3000 rpm for 30 seconds.

Then, the resist in the unsilylated portion is dry-developed using O ₂ gas using the hydrophobic micelle 16 as a mask to form a resist pattern 18 (FIG. 1 (d)). After that, by using the resist pattern 18 as a mask and etching the film to be processed using CF ₄ gas, a vertical and accurate fine pattern 19 with no change in the pattern dimension could be obtained by an easy process. (FIG. 1 (e)).

At this time, an i-ray resist may be used as the resist, or the resist may be exposed by an electron beam other than ultraviolet rays.

(Embodiment 2) FIG. 2 shows a fine pattern forming method by silylation of a resist of the second embodiment.

First, a chemically amplified positive type resist 12 is applied on the film to be processed 13 formed on the semiconductor silicon substrate 11 (FIG. 2A). A high molecular weight organic compound as a main polymer used in this resist and an acid generator capable of generating an acid upon irradiation with ultraviolet rays have a structure shown in (Chemical Formula 3).

After that, the applied resist is irradiated with ultraviolet rays 14 to change the polarity of the main polymer, and the terminal is converted into a hydrophilic hydroxyl group (chemical formula 3) to form a latent image 15 (FIG. 2 (b)). ).

Then, the exposed resist is added with a silicon-based surfactant having a structure as shown in (Chemical Formula 4) in water at 5 mol / c.
It was dissolved at a concentration of m ² × 10 ¹⁰ or more and immersed in a solution in which hydrophilic micelles were formed for 2 minutes (FIG. 2 (c)). At this time, the hydrophilic micelle 21 is adsorbed to the exposed portion 22 of the hydrophilic resist. After that, in order to dry water as a solvent, spin drying was performed at 3000 rpm for 30 seconds.

Then, the resist in the unsilylated portion is dry-developed using O ₂ gas using the hydrophobic micelle 21 as a mask to form a resist pattern 23 (FIG. 2 (d)). After that, the resist pattern 23 is used as a mask and etching is performed by using CF ₄ gas, so that the pattern dimensions are not changed by an easy process.
A vertical and accurate fine pattern 24 could be obtained (FIG. 2E).

At this time, an i-ray resist may be used as the resist, or the resist may be exposed to an electron beam other than ultraviolet rays.

[0041]

As described above, according to the present invention, since the silylation of the resist is carried out by utilizing the property of the micelle, the selectivity of the silylation between the exposed portion and the unexposed portion becomes extremely high.
The dry etching resistance also increases accordingly. Therefore,
It is possible to easily form a highly accurate vertical and accurate fine resist pattern without dimensional shift during pattern transfer during etching. In addition, since it can be silylated in a solution, the process is simplified, and since the wet etching method by organic solvent development is not used, swelling of the resist pattern is not seen, and the environment caused by using an organic solvent is not observed. Also, the problems on the human body are eliminated.

Therefore, by using the present invention, it is possible to easily form an accurate and vertical high-resolution resist pattern with few defects, which can greatly contribute to the manufacture of an ultrahigh-density integrated circuit.

[Brief description of drawings]

FIG. 1 is a process diagram of a method for forming a fine pattern according to a first embodiment of the present invention.

FIG. 2 is a process diagram of a method for forming a fine pattern according to a second embodiment of the present invention.

3A is a schematic diagram of a surfactant, FIG. 3B is a schematic diagram of a positive micelle, FIG. 3C is a schematic diagram of a reverse micelle, and FIG. 3D is a schematic diagram of a hydrophilic micelle during silylation of an exposed part. Schematic diagram (e) is a schematic diagram of adsorption of hydrophobic micelles during silylation of exposed areas.

FIG. 4 is a process diagram showing a method for forming a fine pattern in a conventional vapor phase silylation method.

FIG. 5 is a process diagram showing a method for forming a fine pattern in a conventional liquid phase silylation method.

[Explanation of symbols]

 11 Semiconductor Silicon Substrate 12 Chemically Amplified Positive Resist 13 Processed Film 14 Ultraviolet 16 Hydrophobic Micelle 21 Hydrophilic Micelle 31 Hydrophobic Part 32 Hydrophilic Part

Claims (5)

[Claims] 1. A silicon-based surfactant comprising a hydrophobic group and a hydrophilic group, wherein increasing the concentration facilitates rapid association of the surfactant to form micelles, which are molecular aggregates. Characteristic fine pattern forming material. 2. The silicon-based surfactant is ionic,
The fine pattern forming material according to claim 1, wherein when the micelles are formed, the micelles become spherical micelles, and the hydrophobic portion of the spherical micelle facing outward in the hydrophobic solvent is adsorbed by the hydrophobic portion of the resist. 3. The silicon-based surfactant is ionic,
The fine pattern forming material according to claim 1, wherein when forming micelles, the micelles become spherical micelles, and the hydrophilic portion of the spherical micelle facing outward in a hydrophilic solvent is adsorbed to the hydrophilic portion of the resist. 4. A step of applying a photosensitive polymer film on a film to be processed on a semiconductor substrate to form a resist film, a step of exposing the resist to form a latent image, and a step of forming the latent image. The formed resist film is immersed in a solution of a silicon-based surfactant composed of micelle-forming hydrophobic groups and hydrophilic groups,
The step of adsorbing the silicon-based hydrophilic spherical micelle on the resist upper part of the exposed portion, the step of dry-developing the non-adsorbed part of the silicon-based hydrophilic spherical micelle to form a resist pattern, and the resist pattern is masked And a step of etching the film to be processed as a fine pattern forming method. 5. A step of applying a photosensitive polymer film on a film to be processed on a semiconductor substrate to form a resist film, a step of exposing the resist to form a latent image, and a step of forming the latent image. The formed resist film is immersed in a solution of a silicon-based surfactant composed of micelle-forming hydrophobic groups and hydrophilic groups,
The step of adsorbing the silicon-based hydrophobic spherical micelles on the unexposed portion of the resist, the step of dry developing the non-adsorbed portion of the silicon-based hydrophobic spherical micelles to form a resist pattern, and the resist pattern A fine pattern forming method comprising a step of etching a film to be processed as a mask.