JP2001085666A - Microstructure and its formation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a highly definite structure stably by providing a substrate, an extra-thin film pattern composed of an organic compound having amino groups or thiol groups formed on the substrate, and a layer pattern based on the extra-thin film pattern. SOLUTION: A Si wafer with a patterned trimethylsilyl(TMS) layer 12 is cleaned with pure water and then ethanol, and is immersed in a liquid mixture prepared by mixing aminopropyltriethoxysilane with pure water. In addition the Si wafer is cleaned with ethanol and then pure water. Thus an organic extra-thin film containing as part of its structure amino groups only in the region from which the TMS layer 12 is removed is obtained, and an extra-thin film pattern 20 is obtained. The portions of the pattern other than the thin film portion are provided with the TMS layer. In this case, the amino groups are formed at the terminal of the molecular chain of the organic compound thin film.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a fine structure.

[0002]

2. Description of the Related Art In recent years, with the miniaturization of device sizes,
The demand for improving the precision of micromachining is increasing. The processing accuracy used for manufacturing semiconductor devices has been reduced to about 0.2 μm or less, but processing of several tens of nanometers is expected in the future. In recent years, a scanning probe microscope technique has attracted attention as a method for performing fine processing of several tens of nanometers. With a scanning probe microscope, a probe whose curvature radius is sharpened to about several tens of nanometers is brought close to the vicinity of the sample surface, and the interaction between the probe tip and the sample causes
This is for detecting information on the sample surface locally. Depending on the type of probe, it has an ultra-high resolution feature that can be obtained up to atomic-level resolution. Attempts have been made to apply this scanning probe microscope technique to microfabrication, and scanning probe lithography (Scanning Pr) has been attempted.
ob Lithography, hereinafter referred to as “SPL”. A field of technology called) is being formed. Since this SPL technique can be operated in the atmosphere, the apparatus configuration is very simple, so that there is an advantage that high-definition processing can be performed at low cost.

The present inventor has proposed a method for manufacturing a fine structure in Japanese Patent Application No. 11-94102. In this method, an ultrathin molecular layer is patterned on a substrate, and thereafter, a plating film is selectively grown according to the patterning shape. As a result, high-definition patterning or formation of a structure can be realized at high speed, and high-definition fine processing of a large-area substrate can be performed. However, a higher-definition fine structure and a processing method thereof are demanded. ing.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fine structure having a higher definition and a high aspect ratio, and to produce the fine structure easily and stably with good reproducibility without fluctuation in process conditions. Is to provide a way.

[0005]

According to the present invention, a substrate, an ultrathin film pattern comprising an organic compound having an amino group or a thiol group on the substrate, and a layer pattern based on the ultrathin film pattern are formed. A microstructure characterized by having is provided.

Here, the "layer pattern based on the ultra-thin film pattern" is a layer pattern formed so as to conform to the shape of the line or space portion of the ultra-thin film pattern. It may be formed in either the line portion (thin film portion) or the space portion of the ultra-thin film pattern.

Further, according to the present invention, as a method for suitably producing the microstructure, there is provided a first step of forming an ultrathin film pattern made of an organic compound having an amino group or a thiol group on the surface of a substrate, A second step of forming a plating layer on the surface of the base material using an electroless plating method based on the ultrathin film pattern, and a method for producing a microstructure having a plating layer pattern, the method comprising: You.

According to the method of the present invention, an electroless plating film is formed stably in a region where an organic compound ultra-thin film having an amino group or a thiol group is selectively formed. The mechanism by which a stable electroless plating film is formed in a region where an organic compound ultra-thin film having a chemical structure having an amino group or a thiol group is selectively formed is unknown, but at present, It is considered as follows. It is considered that palladium, which is the core of electroless plating, coordinates with an amino group or a thiol group. Palladium is adsorbed on the amino group or thiol group formed at the terminal of the molecular chain of the organic compound thin film on the substrate surface. Since this bond is stronger than ordinary physical adsorption, stable selective adsorption of palladium becomes possible, and it is considered that the electroless plating film having this as a nucleus is formed stably. In consideration of such a mechanism, it is desirable that the amino group or the thiol group is formed at the terminal of the molecular chain of the organic compound.

The raw material of the compound having an amino group or a thiol group constituting the ultra thin film pattern used in the present invention is preferably a methoxysilane compound, an ethoxysilane compound or a chlorosilane compound having an amino group or a thiol group. It is more desirable to use either triethoxysilane or mercaptopropyltriethoxysilane.

It is known that any one of a methoxysilane compound, an ethoxysilane compound and a chlorosilane compound reacts with a silicon substrate to form a self-assembled molecular film on the substrate surface. By using a raw material having an amino group or a thiol group at the terminal of the molecular chain of these compounds, a self-assembled film having an amino group or a thiol group can be formed on a silicon substrate.

[0011] Aminopropyltriethoxysilane or mercaptopropyltriethoxysilane can be uniformly formed on a substrate with a uniform film thickness, and an amino group is added to a part of the chemical structure in the formed organic ultra-thin film pattern. Alternatively, it has a thiol group as a functional group.

In the above method of the present invention, an organic compound electrode containing neither an amino group nor a thiol group may be formed in a region other than the thin film portion of the ultra-thin film pattern comprising an organic compound having an amino group or a thiol group. It is preferable to provide a thin film.

In this way, the selectivity is improved in electroless plating between the presence and absence of a thin film made of an organic compound having an amino group or a thiol group in an extremely thin film pattern, and a finer and higher aspect ratio plating layer is provided. Is formed.

Further, in the above electroless plating method, it is preferable to form a plating layer containing cobalt, nickel, copper, gold or palladium as a main component. These plating materials (metal materials) are used as materials for wirings, electrodes, and other various members in various electronic devices, and facilitate the production of small devices having finer structures.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail based on examples.

First, the microfabrication process used in this embodiment will be described. The Si wafer 10 was washed with a mixed solution of sulfuric acid and hydrogen peroxide solution. The liquid temperature is 80 ° C. for 10 minutes. After washing and drying, the Si wafer and hexamethyldisilazane (HMDS) are placed in a closed container, and the entire container is heated, so that the trimethylsilyl (TMS) monomolecular layer 12 is formed on the surface of the Si wafer 10. It is formed (FIG. 1A). The heating condition is 70 ° C. for 3 hours.
The thickness of the formed monomolecular layer 12 was 1 nm or less.

Using this as a sample, an atomic force microscope (AF)
M) was used for patterning. The probe 14 used in the AFM is a probe in which a sharpened protrusion is formed near the tip of a silicon cantilever doped with boron at a high concentration, and the tip has a radius of curvature of about 20 nm. there were. In this configuration, a voltage can be applied to the tip of the probe. The sample is arranged on a piezo scanner that is movable in the x, y, and z-axis directions, and a voltage is applied only to the sample. Further, a control mechanism for moving the probe to an arbitrary position on the sample is provided. A voltage of up to 50 V can be applied between the probe and the sample, and a voltage can be applied in a pulsed manner. Further, a voltage can be applied between the probe and the sample while scanning the sample with the piezo scanner. This A
The sample was processed in the first step using FM. With the scanning speed of the sample with respect to the probe (hereinafter, referred to as the scanning speed) kept constant at 20 μm / sec, a 100 μm square area was scanned at a 1 μm pitch. At that time, a DC voltage of 9 V was applied between the probe and the sample (FIG. 1).
(B)). Where a voltage is applied, the TMS layer on the surface of the Si wafer is selectively removed to form an opening 16, and the TMS layer 12 remains at other locations (FIG. 1 (c)). Here, the formed TMS layer pattern had a line (opening) pitch of 1 μm and a line width of 0.2 μm.

After the Si wafer on which the TMS layer 12 has been patterned as described above is washed in the order of pure water and ethanol, 2 vol% aminopropyltriethoxysilane and 4 vol% pure water are added to ethanol. It was immersed in the mixture for 5 minutes. Further, in order of ethanol and pure water,
The i-wafer was cleaned. This process allows TM
An organic ultra-thin film containing an amino group as a part of the structure is formed only in the region where the S12 layer has been removed,
0 was obtained (FIG. 1 (d)). The TMS layer is provided in a portion other than the thin film portion of the pattern. In this case, the amino group is formed at the terminal of the molecular chain of the organic compound thin film.

Through the above-described process, an organic compound ultra-thin film containing an amino group is formed only in a region to which a voltage is applied by the probe 14, and a TM region is formed in other regions.
The S monolayer 12 is left. Here, the TMS molecular layer does not contain an amino group.

Next, a process of performing electroless nickel plating is performed. When electroless nickel plating is performed on a Si or SiO ₂ substrate, a pretreatment called an activator for forming palladium, which is a nucleus of plating, on the substrate surface is performed. Thereafter, by immersing the substrate in an electroless nickel plating solution, a nickel thin film can be obtained on the substrate.

The sample on which the organic ultra-thin film pattern was formed was subjected to electroless nickel plating. First, as an activator, a mixture obtained by adding 30 mL of a mixed solution containing a palladium salt compound and hydrogen chloride (4% of hydrogen chloride, 0.2% of a palladium salt compound, and the balance of water) to 1 L of water was used. An aqueous sodium hydroxide solution was added to adjust the pH to 5.2 at room temperature. In this liquid, about 2
By submerging, palladium was attached to the substrate surface. After removing the sample from the aqueous sodium hydroxide solution, the sample was washed in running water for 3 minutes. Apply electroless nickel plating solution to 7
The sample was maintained at 0 ° C. and pH 4.6, and the washed sample was immersed for about 1 minute.

The electroless nickel plating solution used herein contained a nickel salt compound and hypophosphorous acid in a composition of a nickel salt compound: 30 g / L and sodium hypophosphite: 10 g / L. Then, after taking out from the liquid, it was washed in running water and dried. When this sample was observed by AFM and SEM, it was confirmed that the substrate 18 on which the nickel film 22 was patterned was obtained only in the region where the voltage was applied by the probe (FIG. 1).
(E)). The nickel film thickness was about 800 Å. Also, the pattern width is about 0.2 μm,
It was a stable shape with almost no fluctuation in width.

Further, it was confirmed that the shape and selectivity of the electroless plating film did not change even when the pH of the solution at the time of activation was changed from 4.0 to 6.5 by the above method. At this time, the pH of the electroless plating solution was 4.6.
Met. Further, even if the pH of the solution during electroless plating is changed from 4.0 to 5.2 (the pH of the solution for activation is set to 5.2) by the above method, the shape and selection of the electroless plating film There was no change in gender.

Conventionally, selective electroless plating cannot be easily performed under a wide range of electroless plating conditions. However, according to the above embodiment, a fine structure is stably formed by electroless plating. It was confirmed that it was possible. That is, first, it is possible to stably form a high-definition structure by performing patterning of an ultrathin organic compound film corresponding to the presence or absence of an amino group and subsequently performing electroless nickel plating. confirmed.

As described above, in this embodiment, aminopropyltriethoxysilane is used as a raw material for forming an organic compound ultra-thin film containing an amino group. However, the present invention is not limited to this. It goes without saying that any material that can form an organic ultra-thin film having a group as a part of the structure is effective. Also, when the raw material of the organic compound ultra-thin film was changed to mercaptopropyltrimethoxysilane, it was confirmed that almost the same electroless plating patterning was possible, and it was stable even when the organic compound ultra-thin containing thiol group was used. It is possible to form a structure.

In this embodiment, the obtained pattern width is about 0.2 μm, but it was confirmed that a desired size could be obtained in a range of about 30 nm to 1 μm or more by controlling the processing voltage by the AFM. are doing. Further, in the removal of the organic compound ultra-thin film, the removal of the organic compound ultra-thin film could be realized in the same manner as the processing by the AFM even by local irradiation of ultraviolet rays. Therefore, the present invention
However, the present invention is not limited to the fine processing method using In the present invention, the present invention is not limited to electroless nickel plating, and it is effective to use cobalt, copper, palladium, gold, or the like.

[0027]

As described in detail above, according to the present invention,
It is possible to stably form a high-definition structure.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a method according to an embodiment of the present invention along its steps.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Si substrate 12 TMS layer 14 Probe 16 Opening (TMS layer removal area) 18 Substrate on which fine structure was formed 20 Ultra-thin pattern of organic compound thin film 22 Electroless plating film (nickel film)

Claims (8)

[Claims] 1. A microstructure comprising: a base material; an ultrathin film pattern formed of an organic compound having an amino group or a thiol group on the base material; and a layer pattern based on the ultrathin film pattern. 2. The microstructure according to claim 1, wherein the layer pattern based on the ultrathin film pattern is a plating layer. 3. The organic compound having an amino group or a thiol group is formed from any one of a methoxysilane compound, an ethoxysilane compound, and a chlorosilane compound having an amino group or a thiol group as a part of the structure. The microstructure according to claim 2, wherein: 4. The microstructure according to claim 2, wherein the organic compound having an amino group or a thiol group is formed from one of aminopropyltriethoxysilane and mercaptopropyltriethoxysilane. body. 5. A first step of forming an ultrathin film pattern made of an organic compound having an amino group or a thiol group on the surface of a base material, and using an electroless plating method on the surface of the base material based on the ultrathin film pattern. And a second step of forming a plating layer by a method of manufacturing a fine structure having a plating layer pattern. 6. The organic compound having an amino group or a thiol group is formed from any one of a methoxysilane compound, an ethoxysilane compound, and a chlorosilane compound having an amino group or a thiol group as a part of the structure. The method for manufacturing a microstructure according to claim 5, wherein 7. An ultrathin organic compound film having neither an amino group nor a thiol group is provided in a region other than the thin film portion of the ultrathin film pattern comprising an organic compound having an amino group or a thiol group. Claim 5
A manufacturing method of the microstructure according to the above. 8. The fine pattern according to claim 1, wherein a plating layer containing cobalt, nickel, copper, gold or palladium as a main component is formed by electroless plating based on the ultrathin film pattern. The method of manufacturing the structure.