JP2003308796A - Liquid polyatomic ion beam generator - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To develop surface reforming, and appreciably stable surface reforming, by controlling chemical properties such as a hydrophilic property and a hydrophobic property, and an addition/substitution reaction. <P>SOLUTION: An ionization part 8 can inject a substance in a liquid phase at ordinary temperature into a vacuum from a small hole to ionize the substance, which is extracted as an ion beam 16, and a mass separator 13 can sort the ionized substance by mass magnitude. The mass-separated ion beam 16, after acceleration and control of acceleration energy, irradiates a surface of a substrate 19 to reform the surface of the substrate 19. The small hole is shaped, for example, into a nozzle 1. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid polyatomic ion beam generator capable of forming a polyatomic ion beam from an organic compound which is liquid at room temperature and irradiating the surface of a substrate for surface modification.

[0002]

2. Description of the Related Art Conventionally, in the ion beam method used for modifying the surface of a substrate, a solid or gaseous substance at room temperature has been used as a material for an ion generating source. In addition, conventionally,
When a liquid organic compound is used as an ion, it has been used for mass spectrometry, so the ion current value is extremely small, on the order of nanoampere, and since it is not formed into a beam, the ion is deposited on the substrate surface. Irradiation could not be done to modify the surface.

[0003]

Generally, when changing the chemical properties of a solid surface, for example, when imparting hydrophilicity or hydrophobicity, it is necessary to specify a hydroxyl group having hydrophilicity or an alkyl group having hydrophobicity. A chemical method of cleaning a solid surface using an atomic group having the chemical property of i.e., a liquid polyatomic particle having a functional group as a constituent component is used. However, only by cleaning the surface with the particles, the adhesion of the particles on the solid surface is weak, and there is a drawback that the stability of hydrophilicity and hydrophobicity is lacking.

Therefore, in order to eliminate the above-mentioned drawbacks, it was necessary to use an ion beam method capable of changing the characteristics of the solid surface by freely controlling the incident energy of particles on the solid surface. However, when a gas material is used in the above conventional ion beam method, there are few kinds of particles having an atomic population showing a specific chemical property as a constituent component,
For example, there is a drawback that functional groups having various chemical properties such as aldehyde groups and carboxyl groups cannot be added. Further, in the case of the ion beam method using a solid material, there is a drawback that the characteristics of the surface are lost because the material is deposited and coated on the surface, and further, there is no fluidity like a liquid, so There is a drawback that the source material cannot be continuously supplied.

The present invention has been made in view of the above-mentioned conventional ion beam method, and can perform surface modification by controlling chemical properties such as hydrophilicity, hydrophobicity or lubricity of the surface and addition / substitution reactions. Another object of the present invention is to provide a liquid polyatomic ion beam generator capable of surface modification with further excellent stability.

[0006]

According to the present invention, substances that are liquid at room temperature and have various structures are injected into a vacuum through small holes, the substances are ionized, and the generated ion beam is mass-separated. It is a liquid polyatomic ion beam generator characterized in that it can be accelerated by irradiation to control the kinetic energy of the ion beam to irradiate the surface of the substrate.

Further, the present invention is a liquid polyatomic ion beam generator characterized in that a substance injected into a vacuum through the small holes can be ionized by electron impact or field emission. Furthermore, the present invention has a mass separator capable of selecting an ionized substance according to the size of mass, and further accelerates the ion beam subjected to mass separation by applying an acceleration voltage, and controls the acceleration energy to irradiate the substrate surface. In addition, the liquid polyatomic ion beam generator is characterized in that the surface of the substrate can be modified.

The liquid polyatomic ion beam generator of the present invention can generate an ion beam from various liquid organic compounds in a vacuum or in a low gas pressure region. Further, in the liquid polyatomic ion beam generator of the present invention, the shape of the nozzle for injecting the liquid organic compound into a vacuum is a capillary tube and a structure in which a needle is inserted into the tube. The feature is that it is possible to form a neutral beam by jetting a high-pressure vapor of a liquid and to generate an ion beam by a high electric field applied to the needle.

Furthermore, the liquid polyatomic ion beam generator of the present invention is characterized by having an ionization section capable of ionizing the substance of the vapor injected into a vacuum by electron impact. Further, the liquid polyatomic ion beam generator of the present invention has a mass separator capable of generating an electromagnetic field in which an electric field and a magnetic field are orthogonal to each other for mass-separating an ion beam, and the magnetic field generating portion is a neodymium permanent magnet. It is characterized by its compact size, easy operation, and accurate mass separation.

Furthermore, the liquid polyatomic ion beam generator of the present invention irradiates the polycarbonate substrate with ion beams of ethanol and decane, which are liquid organic compounds having different chemical properties, and the surface of the substrate is hydrophilic with ethanol ions. Decane ions can be made hydrophobic.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described specifically and in detail with reference to the drawings.
In the embodiment of the present invention, a substance of high-pressure vapor such as alcohol, acetone, or decane injected in a vacuum is ionized by electron impact, and the extracted ion beam is mass-separated in an electromagnetic field in which an electric field and a magnetic field are orthogonal to each other, and the mass separation is performed. A liquid polyatomic ion beam generator capable of accelerating the generated ion beam to irradiate the surface of a substrate of silicon or polycarbonate is shown.

FIG. 1 is a schematic view of a liquid polyatomic ion beam generator, in which a nozzle 1 for injecting a liquid material such as an organic compound into a vacuum has a capillary shape made of stainless steel. It has a structure in which a thin tube 2 and a needle 3 made of stainless steel are inserted into the thin tube. Like alcohol and acetone, vapor pressure at room temperature is tens of Tor
With a liquid material from which a high pressure of r to several hundred Torr can be easily obtained, it can be injected as a vapor into a vacuum through the gap between the thin tube 2 and the needle 3. Further, in the case of a liquid material having a low vapor pressure such as tridecane, a liquid is supplied to the tip of the needle 3 and the liquid ions of the material can be released by ionization by field emission. The needle 3
Is longer than the tip of the thin tube 2 by 1 mm to 3 mm, and the length of the tip can be freely changed by replacing the needle 3. The capillary thin tube 2 into which the needle 3 is inserted is attached to a pipe 4 made of stainless steel, and the pipe 4 is connected to a liquid supply measuring cylinder provided outside the vacuum. Further, the members for introducing the liquid material into the pipe 4 are the X-axis, the Y-axis, and the Z-axis.
It is mounted on a stage 5 that can be moved independently in the three axial directions, and can be moved within a range of ± 3 mm for the X axis and the Y axis and ± 5 mm for the Z axis by using a micrometer 6. Evacuation of the surroundings of the needle 3 is performed by an oil diffusion pump, and the degree of vacuum before vapor injection is 2 × 10 ^−6.
Torr.

The vapor of the liquid material ejected from the nozzle 2 passes through the collimator 7 having an opening with a diameter of 1 mm and is introduced into the ionization section 8. The axis of the tip of the needle 3 and the opening of the collimator 7 can be aligned with the micrometer 6 that can move the stage in the X-axis and Y-axis directions. The ionization section 8 is composed of an electron emission filament 9 for ionization and a grid 10 made of a tungsten mesh. The filament 9 is made of a tungsten wire having a diameter of 0.5 mm. The electrons emitted from the filament 9 have a maximum voltage of 500
It is accelerated by V and captured by the grid 10. The electrons that have passed through the gaps in the mesh of the grid 10 are ionized by the ionization part 8
Collide with the vapor of the liquid material introduced into the chamber and ionize the vapor. The generated ions are extracted by applying a maximum extraction voltage of 10 kV to the extraction electrode 11 on the grid. The extraction electrode 11 is held at the ground potential, and the opening of the electrode 11 has a diameter of 1 mm.
It is 5 mm.

The extracted ion beam passes through the first slit 12 and is introduced into the mass separator 13 by the orthogonal electromagnetic field. The magnetic field of the mass separator 13 is generated using a neodymium permanent magnet 14 having a bottom surface dimension of 50 mm × 50 mm and a thickness of 13 mm, and a surface magnetic flux density of about 4000 Gauss is obtained. On the other hand, an electric field is generated by using a non-magnetic parallel plate electrode 15 made of non-magnetic stainless steel having a size of 20 mm × 50 mm, the distance between the electrodes can be adjusted between 10 mm and 20 mm, and a voltage of 10 kV at the maximum can be applied to the electrode. It can be applied between.

The mass-separated ion beam 16 has a second
The substrate holder 1 is accelerated after passing through the slit 17.
The substrate 19 mounted on the substrate 8 is irradiated. A mask 20 made of silicon having a size of 10 mm × 10 mm is placed on the beam incident side of the substrate 19, and the mask 20 limits the ion irradiation region of the substrate 19. A suppressor electrode 21 is provided to suppress secondary electron emission from the substrate 19 due to ion irradiation. The maximum acceleration voltage applied to the substrate 19 is −10 k.
V. A shutter 22 is provided between the substrate 19 and the mass separator 13, and the irradiation time can be controlled by opening and closing the shirt 22. The substrate 19
The surroundings are vacuum-exhausted by a turbo molecular pump, and the degree of vacuum before the ion beam irradiation is 8 × 10 ⁻⁷ Torr.

FIG. 2 is an enlarged view of the nozzle 1 of the liquid polyatomic ion beam generator of this embodiment. The shape of the nozzle 1 in which a liquid material such as an organic compound is sprayed in a vacuum has an outer diameter of 0.31 mm to 0.35 mm and an inner diameter of 0.
A capillary tube 2 made of stainless steel having a length of 1 mm to 0.17 mm and a length of 15.5 mm, and a diameter of 0.
It has a structure in which a 1 mm stainless steel needle 3 is inserted. The needle 3 is supported by a needle holder 23. Furthermore, by exchanging the needles 3 of various lengths, the length of the needles protruding from the thin tube 2 can be adjusted.

[0017]

EXAMPLE Next, an experiment was conducted in which ethanol and decane were used as liquid materials, and the vapor of the liquid material ejected from the nozzle was ionized by electron impact, and the extracted ion beam was mass-separated and irradiated on the substrate surface. Hereinafter, the experimental results according to the embodiment will be described with reference to FIGS. 3 to 7.

FIG. 3 is a graph showing the characteristics of ion vaporization of ethanol vapor and mass separation of the extracted ion beam according to this embodiment. Here, the ion extraction voltage (Vext) = 2 kV, the ionization electron voltage (Ve) =
100 V, ionized electron current (Ie) = 100 mA,
The data is obtained for the extraction current (Iext) = 58 μA. According to this, the mass-to-charge ratio (m /
It can be seen that the peak of e) = 31 is the maximum and the peak is a polyatomic ion represented by the chemical symbol CH ₂ OH.
In addition, a peak with a mass-to-charge ratio (m / e) of 45 also appears, which indicates that the peak is a polyatomic ion represented by the chemical symbol CH ₃ CHOH. It can be seen that each ion has a hydroxyl group (OH group) and is a polyatomic ion having 5 or more atoms.

FIG. 4 is a graph showing the characteristics of ionizing the decane vapor and mass-separating the extracted ion beam according to this embodiment. Here, the ion extraction voltage (Vext) = 4 kV and the ionization electron voltage (Ve) = 1
The data was obtained at 00 V, ionized electron current (Ie) = 100 mA, and extraction current (Iext) = 26 μA. According to this, the mass-to-charge ratio (m / e)
= 29, 43, 57 peaks appear, which are polyatomic ions represented by the chemical symbols C ₂ H ₅ , C ₃ H ₇ , and C ₄ H ₉ , respectively. It can be seen that any polyatomic ion is an ion having an alkyl group represented by a C _m H _n group (n and m are natural numbers and m <n).

FIG. 5 shows CH ₃ produced according to this embodiment.
6 is a graph in which a silicon substrate is irradiated with a CHOH ion beam at an incident energy of 6 keV, the silicon substrate is taken out of a vacuum container, and the extent of irradiation damage to the silicon substrate is measured by the Rutherford backscattering (RBS) method. The irradiation amount was 1 × 10 ¹⁵ ions per unit area of 1 cm ² . For comparison, argon ions were irradiated under the same conditions. According to the graph, in the CH ₃ CHOH ion irradiation, the area of the peak near the 230 channel is smaller than that in the argon ion irradiation, but it is slightly larger than in the silicon substrate not irradiated with ions. According to this, immediately after irradiating the silicon substrate, CH ₃ CHOH ions are decomposed into carbon (C) atoms, hydrogen (H) atoms, hydroxyl (OH) groups, etc., and the incident energies of the ions are changed. It can be seen that they are distributed into atoms and hydrogen radicals and are injected into the silicon substrate.

Further, CH₃By CHOH ion irradiation
The depth of damage of the silicon substrate is around 230 channels
It is 1.2 nm when calculated from the width of the peak. In addition,
CH ₃Immediately after irradiating the silicon substrate with CHOH ions
In addition, carbon (C) atom, hydrogen (H) atom, hydroxyl (OH) group
Assuming that the C atom or OH group is decomposed into
Computer simulation of the depth to be injected into the control board
Therefore, the calculated value is 1.2 nm to 1.4 nm. The de
The damage depth of the data and the calculation result are in good agreement.
From CH₃CHOH ions irradiate the silicon substrate
Immediately after that, carbon (C) atom, hydrogen (H) atom, hydroxy (O)
It can be seen that the H) group is decomposed.

FIG. 6 shows CH ₃ produced by the embodiment.
It is a graph which measured the optical characteristic of this silicon substrate with an ellipsometer after taking out a silicon substrate from a vacuum container after irradiating a silicon substrate with a CHOH ion beam by changing an irradiation amount. Here, the incident energy of the ions is 6 keV. The thickness of the damaged layer (T _d ) and the thickness of the oxide layer (T _ox ) formed in the vicinity of the surface layer of the silicon substrate are determined from the delta angle on the vertical axis of the graph and the psi angle on the horizontal axis. Can be calculated. The calculation result is shown by a wavy line in the graph. According to this, it is understood that the thickness of the damaged layer or the oxide layer increases as the ion irradiation amount increases.

FIG. 7 shows CH ₃ produced according to this embodiment.
6 is a graph showing the irradiation dose dependence of the contact angle of the polycarbonate substrate after the polycarbonate substrate was irradiated with a CHOH ion beam and a C ₃ H ₇ ion beam while changing the irradiation dose, and then the polycarbonate substrate was taken out of the vacuum container. . Here, the incident energy of the ions is 6 keV
And According to this, it is understood that in the CH ₃ CHOH ion irradiation, the contact angle decreases with an increase in the irradiation amount, and the hydrophilicity of the polycarbonate substrate increases. Also, C
_{In 3} H ₇ ion irradiation, the contact angle is 1 × 10 ¹³ io.
It takes a minimum value in ns / cm ² , and it can be seen that the contact angle increases as the irradiation amount increases with the irradiation amount higher than the minimum value. Further, it is understood that when the irradiation amount is 1 × 10 ¹⁵ ions / cm ² , the contact angle of the polycarbonate substrate, that is, the hydrophobicity is increased as compared with the case where it is not irradiated. According to this, the increase in hydrophilicity is due to defects formed by ion irradiation on the surface of the polycarbonate substrate and hydroxyl (O
It can be seen that the increase in the H) group and the increase in the hydrophobicity are due to the increase in the alkyl group such as CH ₃ .

According to the embodiment, as shown in the above data, various polyatomic ion beams can be generated by ionization by electron impact method from an organic compound which is liquid at room temperature in vacuum or in a low gas pressure region. In the liquid polyatomic ion beam generator of the example, since the shape of the nozzle for injecting the liquid organic compound into the vacuum is a capillary tube and a structure in which a needle is inserted into the tube. Liquid ions can be generated by a high electric field formed by applying a voltage of 2 kV or more to the needle.

The mass separator may be a mass separator using a fan-shaped electromagnet or a mass separator using a quadrupole high frequency electric field.

Further, the surface of various substrates is irradiated with a polyatomic ion beam generated from various liquid organic compounds,
Surface modification of the polyatomic ion can alter the chemistry of the substrate surface. The surface modification of the substrate can also be applied to physical surface processing using only the kinetic energy of a polyatomic ion beam incident on the surface of the substrate. Further, a reactive gas such as oxygen or nitrogen may be introduced around the substrate, and a substitution reaction or an addition reaction of the reactive gas may be brought about by the assisted irradiation of the polyatomic ion.

[0027]

INDUSTRIAL APPLICABILITY The liquid polyatomic ion beam generator of the present invention can generate an ion beam from various liquid materials in a vacuum or in a low gas pressure region, so that a liquid organic material having a specific atomic group or atomic structure can be produced. It is possible to control the chemical properties of the substrate surface by irradiating the substrate surface with an ion beam of a compound.

Further, in the liquid polyatomic ion beam generator of the present invention, since a small neodymium permanent magnet is used for the mass separator, it is lightweight and easy to handle, and mass separation can be performed accurately.

In the liquid polyatomic ion beam generator of the present invention, 1 × 10 ¹⁵ ions / cm ^{2 is obtained} by irradiating the polycarbonate substrate with ion beams of ethanol and decane as liquid organic materials having different chemical properties.
By the above ion irradiation, the substrate surface can be made hydrophilic with ethanol ions and hydrophobic with decane ions.

Furthermore, the liquid polyatomic ion beam generator of the present invention controls the surface reaction such as addition reaction or substitution reaction of the substrate surface atoms by controlling the size and structure of the polyatomic ion, at the atomic / molecular level. It can be applied to surface functionalization process controlled by.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a liquid polyatomic ion beam generator of the present invention.

FIG. 2 is an enlarged view of a nozzle of the liquid polyatomic ion beam generator of the same embodiment.

FIG. 3 is a graph showing the analysis results of ethanol ions mass-separated according to an example of the present invention.

FIG. 4 is a graph showing the analysis results of decane ions mass-separated according to the example.

FIG. 5 is a graph showing R of a silicon substrate irradiated by accelerating and irradiating ethanol ions and argon ions mass-separated by the example.
It is a graph which shows the channeling spectrum by BS method.

FIG. 6 is a graph in which the optical characteristics of the silicon substrate irradiated with accelerated mass-separated ethanol ions according to the example are measured by an ellipsometer.

FIG. 7 is a graph showing the dose dependence of the contact angle of a polycarbonate substrate irradiated with accelerated mass-separated ethanol ions and decane ions according to the example.

[Explanation of symbols]

1 nozzle 2 thin tubes 3 needles 4 pipes 5 stages 6 micrometer 7 Collimator 8 Ionizer 9 filament 10 grid 11 Extraction electrode 12 First slit 13 Mass separator 14 permanent magnet 15 Parallel plate electrode 16 ion beam 17 Second slit 18 PCB holder 19 board 20 masks 21 suppressor electrode 22 shutter 23 Needle holder

Claims (6)

[Claims] 1. An ionization part capable of ejecting a substance, which is liquid at room temperature, into a vacuum through a small hole, and ionizing the substance to extract it as an ion beam, and mass separation capable of selecting the ionized substance according to the magnitude of mass. A liquid polyatomic ion beam generator characterized in that it has a chamber and accelerates the mass-separated ion beam and controls the acceleration energy to irradiate the substrate surface to modify the substrate surface. 2. The liquid polyatomic ion beam generator according to claim 1, wherein the small hole has a nozzle shape. 3. The liquid polyatomic ion beam generator according to claim 1, wherein the mass separator can mass-select ions by an electromagnetic field in which an electric field and a magnetic field are orthogonal to each other. 4. A liquid polyatomic ion beam generator according to claim 2, wherein the substance injected into the vacuum from the nozzle can be ionized by electron impact. 5. The liquid polyatomic ion beam according to claim 2, wherein ions can be extracted by inserting a needle into the small hole and applying a high electric field to the needle. Generator. 6. A liquid polyatomic ion beam generator according to claim 3, wherein the mass-separated ions can utilize ions having 5 or more constituent atoms.