KR102165217B1 - Cluster ion beam generation method and cluster ion beam irradiation method using the same - Google Patents

Abstract

It provides a cluster ion beam generation method capable of increasing the beam current value of the cluster ion beam than the conventional one.
The cluster ion beam generation method of the present invention is a cluster ion beam generation method in which a cluster ion beam having carbon and hydrogen as constituent elements is generated from a hydrocarbon-based compound raw material, and the hydrocarbon-based compound raw material comprises a side chain. And a branched chain saturated hydrocarbon, wherein the branched chain saturated hydrocarbon is branched only by tertiary carbon atoms.

Description

Cluster ion beam generation method and cluster ion beam irradiation method using the same

[0001] The present invention relates to a cluster ion beam generation method and a cluster ion beam irradiation method using the same.

[0002] A cluster ion beam is a group of atoms or molecules that are ionized by bonding to each other and form a solid surface of a plurality of (usually about 2 to 2000, in some cases hundreds to thousands). It is used in surface processing technology to collide with. In recent years, application of cluster ion beam technology has attracted attention in nano-processing processes for various devices such as semiconductor devices, magnetic/dielectric devices, and optical devices.

[0003] The basic principle of a method for generating a cluster ion beam will be schematically described with reference to FIG. 1. First, the raw material 1 is supplied, and electrons collide with the raw material 1 by an electron bombardment method to dissociate the bonds of the raw material 1 to generate ionized cluster ions 2. When generating cluster ions 2, it is common for monoatomic ions 4 and polyatomic ions 6 to be simultaneously formed. Further, the unstable polyatomic ions 6 may further dissociate. Next, in order to select the cluster ions 2 of the desired cluster size, mass separation of the generated ions is performed. Then, the cluster ions 2 selected by the mass separation are extracted by a predetermined acceleration voltage to form a cluster ion beam. The target T can be surface-processed by colliding the cluster ion beam thus obtained with the surface of the target T. For reference, in an environment of room temperature and pressure, the raw material 1 may be any of a gas, a liquid, and a solid. In the apparatus, the raw material 1 is gasified just before the electrons collide with the raw material 1.

[0004] In addition, in the present specification, the term "cluster ion" refers to a group in the form of an ionized mass, and the term "cluster ion beam" is obtained by accelerating and focusing the cluster ion in a vacuum, It shall mean a beam that translates into a bundle shape. In addition, "cluster size" means the number of atoms or molecules constituting one cluster.

[0005] Here, the applicant of the present application is a cluster in which, in Patent Document 1, a semiconductor wafer is irradiated with cluster ions to form a modified layer in which the constituent elements of the cluster ions are solid solution on the surface of the semiconductor wafer A method of manufacturing a semiconductor epitaxial wafer including an ion beam irradiation step and a step of forming an epitaxial layer on the modified layer of the semiconductor wafer has been proposed.

[0006] In the technique described in Patent Document 1, since cluster ions are irradiated on the surface of a semiconductor wafer, the constituent elements of the cluster ions are localized and precipitated at a high concentration compared to the ion implantation region formed by the monomer ion implantation technique. Areas can be formed. For this reason, by the technique described in Patent Document 1, it is possible to obtain a semiconductor epitaxial wafer having very excellent gettering ability compared to the prior art, and heavy metal contamination can be suppressed.

In addition, the applicant of the present application, in Patent Document 2, in order to provide a method for manufacturing a semiconductor epitaxial wafer having a high gettering ability and suppressing the occurrence of epitaxial defects, the following semiconductor epitaxial wafer The manufacturing method of That is, in the method for manufacturing a semiconductor epitaxial wafer disclosed in Patent Document 2, a modified layer in which the constituent elements of the cluster ions are solid solution is formed on the surface of the semiconductor wafer by irradiating cluster ions on the surface of the semiconductor wafer. A cluster ion beam irradiation step and a step of forming an epitaxial layer on the modified layer of the semiconductor wafer. In the cluster ion beam irradiation step, a part of the thickness direction in the modified layer is an amorphous layer In addition, the average depth of the surface of the amorphous layer on the surface of the semiconductor wafer is 20 nm or more from the surface of the semiconductor wafer.

[0008] 1. International Publication No. 2012/157162 2. Japanese Patent Laid-Open No. 2015-130402

[0009] Here, in performing the cluster ion beam irradiation process disclosed in Patent Documents 1 and 2, the cluster ion is also dependent on the dose amount and beam current value of the cluster ions to be irradiated, and the wafer diameter of the semiconductor wafer. It took a lot of time to do the beam irradiation. For this reason, in order to mass-produce a semiconductor epitaxial wafer by using the method of manufacturing a semiconductor epitaxial wafer included as a cluster ion beam irradiation step, an improvement in throughput is desired.

In the cluster ion beam irradiation process, if the dose amount is the same, the larger the beam current value of the cluster ion beam, the shorter the irradiation time can be. For example, Patent Document 2 discloses that C ₃ H ₅ clusters are generated from cyclohexane in the Examples, and that the beam current value is 400 μA. In order to improve the throughput of semiconductor epitaxial wafer fabrication, the inventors have recognized as a new subject to increase the beam current value.

Accordingly, an object of the present invention is to provide a cluster ion beam generation method capable of increasing the beam current value of the cluster ion beam compared to the prior art in view of the above problems. Further, an object of the present invention is to provide a cluster ion beam irradiation method and a semiconductor epitaxial wafer manufacturing method using the cluster ion beam generation method.

[0012] The inventors have studied hard to solve the above problems. As the inventor of the present invention eagerly studied, it was confirmed that the beam current value could be increased to some extent by changing the decomposition conditions of the raw material in the ion source, but there was a limit to the increase. Accordingly, the present inventors have paid attention to the raw material for the ion source, and in particular, the molecular structure of the hydrocarbon-based compound raw material. In the case of generating a beam of cluster ions containing carbon and hydrogen as a constituent element, by using a branched chain saturated hydrocarbon having a predetermined structure as a raw material for a hydrocarbon-based compound, the current value of the cluster ion beam is significantly increased. The inventors have found that improvement can be made, and the present invention has been completed. That is, the summary structure of the present invention is as described below.

(1) A cluster ion beam generation method for generating a beam of cluster ions having carbon and hydrogen as constituent elements from a hydrocarbon-based compound raw material, wherein the hydrocarbon-based compound raw material comprises a branched chain saturated hydrocarbon having a side chain And the branched chain saturated hydrocarbon is branched only by tertiary carbon atoms.

(2) The cluster ion beam generation method according to (1), wherein the branched chain saturated hydrocarbon has only one tertiary carbon atom.

(3) The branched chain saturated hydrocarbon has 2 or 3 or more tertiary carbon atoms, and the 2 or 3 or more tertiary carbon atoms are all through 1 or 2 or more secondary carbon atoms The cluster ion beam generation method according to the above (1) to combine.

(4) The cluster ion beam generation method according to (3), wherein the branched chain saturated hydrocarbon has two tertiary carbon atoms.

(5) The cluster ion beam generation method according to (4), wherein the two tertiary carbon atoms are bonded to each other through one secondary carbon atom.

(6) A cluster ion beam irradiation method comprising irradiating the surface of a semiconductor wafer with a cluster ion beam generated by using the cluster ion beam generation method according to any one of (1) to (5) above. .

According to the present invention, it is possible to provide a cluster ion beam generation method capable of increasing the beam current value of the cluster ion beam compared to the conventional one. Further, the present invention can provide a cluster ion beam irradiation method capable of increasing the beam current value compared to the conventional one.

1 is a schematic diagram for explaining the basic principle of cluster ion beam generation.
2A, 2B, and 2C are schematic cross-sectional views illustrating a method of manufacturing a semiconductor epitaxial wafer 100 using a cluster ion beam irradiation method according to an embodiment of the present invention.

[0021] (Cluster ion beam generation method)

A cluster ion beam generation method according to an embodiment of the present invention is a cluster ion beam generation method in which a beam of cluster ions having carbon and hydrogen as constituent elements is generated from a hydrocarbon-based compound raw material. Here, the hydrocarbon-based compound raw material contains a branched chain saturated hydrocarbon having a side chain, and the branched chain saturated hydrocarbon is branched only by a tertiary carbon atom. For reference, inevitable impurities may be included in the raw material of the hydrocarbon-based compound.

[0022] The basic principle of the cluster ion beam generation method is as already described with reference to FIG. 1. That is, first, the raw material 1 is supplied, and electrons collide with the raw material 1 by an electron bombardment method to dissociate the bonds of the raw material 1 to generate ionized cluster ions 2. Subsequently, mass separation of the generated ions is performed to select the cluster ions 2, and the cluster ions 2 are extracted by a predetermined acceleration voltage to form a cluster ion beam. In this way, a cluster ion beam can be generated. The cluster ion beam thus obtained can be irradiated onto the surface of an arbitrary target T. As a cluster ion implantation apparatus using such a principle, for example, CLARIS (registered trademark) manufactured by NISIN ION EQUIPMENT CO. LTD. can be used.

In this embodiment, the above-described hydrocarbon-based compound raw material gas is used as the raw material (1). The constituent elements of the cluster ions 2 constituting the resulting cluster ion beam have carbon and hydrogen, and in particular, the constituent elements of the cluster ions 2 can be composed of only carbon and hydrogen.

The hydrocarbon-based compound raw material used in the present embodiment will be described in more detail below. It is important that the hydrocarbon-based compound raw material is a branched chain saturated hydrocarbon having a side chain, and the branched chain saturated hydrocarbon is branched only by tertiary carbon atoms. Such a branched chain saturated hydrocarbon can be represented by the following formula (I).

[Formula 1]

Here, in the formula (I), R ₁ , R _2, and R ₃ bonded to a tertiary carbon atom are all independent straight chains having 1 or 2 or more carbon atoms, or It is a branched alkyl group. All of R ₁ , R ₂ and R ₃ may be the same alkyl group, any two may be the same alkyl group, or all may be different. In addition, the term "straight-chain" as used herein also includes the case of a hydrocarbon having 1 or more and 3 or less carbon atoms and which cannot be branched, and hereinafter, it is referred to as "linear" in the same meaning.

In addition, the branched chain saturated hydrocarbon used in this embodiment may be any of a gas, a liquid, and a solid in an environment of room temperature and pressure, and the raw material is converted to electrons in a chamber under vacuum (eg, 10 ^-2 Pa or less). Immediately before colliding with, the branched chain saturated hydrocarbon may have been gasified. That is, when the raw material is introduced into the chamber and collides with electrons, the liquid raw material may be vaporized and supplied into the chamber, or the solid raw material may be heated and vaporized in a vacuum in another device to be introduced into the chamber, and the gaseous raw material gas itself is introduced into the chamber. You may make it supply inside. As carbon number of such a branched chain saturated hydrocarbon, 4 or more and 16 or less can be illustrated. Moreover, it is preferable to use 5 or more carbon atoms of a branched chain saturated hydrocarbon, and it is more preferable to set it as 6 or more. On the other hand, the number of carbon atoms of the branched chain saturated hydrocarbon is preferably 10 or less, more preferably 8 or less, and particularly preferably 7 or less. For this reason, the total carbon number of R ₁ , R ₂ and R ₃ can be 3 or more and 15 or less. Moreover, it is preferable to make the total number of carbon atoms of these R ₁ , R ₂ and R ₃ 4 or more, and more preferably 5 or more. On the other hand, the total number of carbon atoms of these R ₁ , R ₂ and R ₃ is preferably 9 or less, more preferably 7 or less, and particularly preferably 6 or less.

In addition, the number of carbon atoms of R ₁ , R ₂ and R ₃ in the formula (I) is independently 1 or more, and can be 2 or more, as long as the total number of carbons already described is satisfied, and 3 It can be done above. Similarly, the number of carbon atoms of R ₁ , R _2, and R ₃ can each independently be 4 or less, 3 or less, and 2 or less while satisfying the total number of carbon atoms previously described. The number of carbon atoms of R ₁ , R _2, and R ₃ may all be the same, any two carbon number may be the same, or all may be different.

[0027] By the way, as the inventors eagerly studied, in order to increase the beam current value to a greater extent than before when generating a cluster ion beam from a hydrocarbon-based compound raw material, the decomposition condition of the raw material in the ion source is adjusted. There was a limit to it. By the way, in a saturated hydrocarbon (alkane), the bond between the tertiary carbon atom and the alkyl group is stable, so that the radical generated at the time of separation is stable, so that the primary carbon atom or the secondary carbon atom and The bond dissociation energy is small compared to the bond between alkyl groups. For this reason, when electrons collide with the branched chain saturated hydrocarbon represented by the above formula (I) by the electron bombardment method, a separation occurs preferentially in the bond between the tertiary carbon atom and the alkyl group to which it is bonded, and the radical and It is easy to generate ions. For this reason, the inventor thought that the generation efficiency of a cluster ion beam can be improved. Therefore, the present inventors pay attention to this point, and by using the branched chain saturated hydrocarbon represented by the above formula (I) as a hydrocarbon-based compound raw material, the beam current value of the generated cluster ion beam can be greatly increased compared to the prior art. Was found, and the effect was experimentally clarified.

As described above, by using the branched chain saturated hydrocarbon according to the present embodiment as a hydrocarbon-based compound raw material, the beam current value of the cluster ion beam can be greatly increased compared to the conventional one. According to the present embodiment, in a hydrocarbon-based cluster ion beam, the obtained beam current value can be 1000 μA or more, 1200 μA, 1500 μA or more, 1800 μA or more, and further, 2000 μA. It can be done above.

Here, it is preferable that the branched chain saturated hydrocarbon represented by the formula (I) has only one tertiary carbon atom. That is, it is preferable that all of R ₁ , R ₂ and R ₃ in formula (I) be a linear saturated alkyl group. For example, R ₁ may be a methyl group, an ethyl group, an n-propyl group, or an n-butyl group, and R ₂ and R ₃ may be either a methyl group or an ethyl group.

As such a branched chain saturated hydrocarbon, 2-methylpropane, 2-methylbutane, 2-methylpentane, 2-methylhexane, 2-methylheptane, and the like can be exemplified. By using these branched chain saturated hydrocarbons as a hydrocarbon-based compound raw material, the beam current value of the cluster ion beam can be more reliably increased.

On the other hand, the branched chain saturated hydrocarbon represented by the formula (I) has 2 or 3 or more tertiary carbon atoms, and all of these 2 or 3 or more tertiary carbon atoms are 1 or 2 or more second It is also preferred to bond via a grade carbon atom. In particular, it is preferable that the branched chain saturated hydrocarbon has two tertiary carbon atoms. The latter branched chain saturated hydrocarbon can be represented by the following formula (II).

[Formula 2]

Here, in the formula (II), R ₄ bonded to the tertiary carbon atom is a linear saturated alkylene group, and R ₅ , R ₆ , R ₇ and R ₈ are all linear saturated alkyl groups.

As already described, when tertiary carbon is present, carbon radicals are liable to be generated. However, according to the investigation of the present inventors, it was confirmed that when tertiary carbons are bonded to each other, the bond dissociation energy is too small, ionization is explosively generated by electron collision, and control becomes difficult. In this case, the beam current value of the cluster ion beam may become rather small. Therefore, in the branched chain saturated hydrocarbon used in this embodiment, when there are 2 or 3 or more tertiary carbon atoms, all of these 2 or 3 or more tertiary carbon atoms are 1 or 2 or more secondary carbon atoms. It is preferable to use what is combined through.

Here, the number of carbon atoms of the branched chain saturated hydrocarbon represented by the formula (II) is also the same as the number of carbon atoms of the branched chain saturated hydrocarbon of the formula (I), except that the lower limit is 7. For this reason, the total number of carbon atoms of R ₄ , R ₅ , R ₆ , R ₇ and R ₈ can be 5 or more and 14 or less. Further, the total number of carbon atoms of these R ₄ , R ₅ , R ₆ , R ₇ and R ₈ is preferably 5 or more, preferably 6 or more, and preferably 7 or more. On the other hand, the total number of carbon atoms of these R ₄ , R ₅ , R ₆ , R ₇ and R ₈ is preferably 9 or less, preferably 8 or less, and 7 or less.

And, the number of carbon atoms of R ₄ , R ₅ , R ₆ , R ₇ and R _{8 in} the above formula (II) is independently 1 or more, and 2 or more, while satisfying the total number of carbons already described. It can be done with 3 or more. Similarly, the number of carbon atoms of R ₄ , R ₅ , R ₆ , R ₇ and R ₈ can each independently be 4 or less, or 3 or less, while satisfying the total number of carbons already described, and 2 or less. can do. The number of carbon atoms of R ₄ , R ₅ , R ₆ , R ₇ and R ₈ may all be the same, any two, three, or four carbon atoms may be the same, or all may be different.

[0035] As such a branched chain saturated hydrocarbon, 2,4-dimethylpentane, 2,4-dimethylhexane, 2,4-dimethylheptane, 2,5-dimethylhexane, 2,5-dimethylheptane, and the like can be exemplified. have. By using these branched chain saturated hydrocarbons as a hydrocarbon-based compound source gas, the beam current value of the cluster ion beam can be more reliably increased.

In addition, when using the branched chain saturated hydrocarbon of the formula (II), it is preferable that two tertiary carbon atoms are bonded to each other via one secondary carbon atom. That is, it is preferable that R ₄ in formula (II) is a methylene group. For example, as the branched chain saturated hydrocarbon according to Formula (II), 2,4-dimethylpentane, 2,4-dimethylhexane, and 2,4-dimethylheptane may be used. By using such a branched chain saturated hydrocarbon as a hydrocarbon-based compound source gas, the beam current value of the cluster ion beam can be more reliably increased.

In addition, cluster ions exist in various types of clusters depending on the binding mode, and can be generated, for example, by a known method as described in the following documents.

(1) Charged particle beam engineering: Junzo Ishikawa: ISBN978-4-339-00734-3: CORONA PUBLISHING CO., LTD.

(2) Electron and Ion Beam Engineering: Electrical Society: ISBN4-88686-217-9: Ohmsha, Ltd.

(3) Cluster Ion Beam Fundamentals and Applications: ISBN4-526-05765-7: Daily Industrial Newspaper (NIKKAN KOGYO SHIMBUN, LTD.)

In general, a Nielsen-type ion source or a Kaufman-type ion source is used to generate positively charged cluster ions, and a high-current anion source using a volume generation method is used to generate negatively charged cluster ions.

In addition, the acceleration voltage per carbon atom of the generated cluster ions is greater than 0 keV/atom and 50 keV/atom or less, preferably 40 keV/atom or less. In addition, although the cluster size also depends on the branched chain saturated hydrocarbon constituting the hydrocarbon-based compound raw material, it can be 2 to 50 or less.

In addition, for the adjustment of the acceleration voltage, two methods of (1) electrostatic acceleration and (2) high-frequency acceleration are generally used. As the former method, there is a method in which a plurality of electrodes are arranged at equal intervals and the same voltage is applied between them to create an equivalent acceleration electric field in the axial direction. As the latter method, there is a linear linac method in which ions run in a linear shape while accelerating using high frequency. In addition, the cluster size and beam current value of the cluster ion beam can be adjusted by adjusting the pressure of the vacuum container (flow rate of the gas to be introduced) and the voltage applied to the filament during ionization. In addition, the cluster size can be performed by using a mass separation method using a quadrupole high-frequency electric field or a mono-converging linear magnetic field.

In the following, referring to Figure 2 (a), (b), (c) (hereinafter referred to as Figure 2 (a) to (c)), a cluster according to another embodiment of the present invention An ion beam irradiation method will be described. In addition, in principle, the same reference numerals are attached to the same components, and the description thereof is omitted. In addition, in FIGS. 2A to 2C, for convenience of explanation, different from the actual thickness ratio, the thickness of the epitaxial layer 20 is exaggerated with respect to the semiconductor wafer 10.

[0041] (cluster ion beam irradiation method)

As shown in Fig. 2A, in the cluster ion beam irradiation method according to one embodiment of the present invention, the cluster ion beam C generated using the embodiment of the cluster ion beam generation method is used as a semiconductor. The surface 10A of the wafer 10 is irradiated. In this embodiment, it is possible to perform cluster ion beam irradiation in which the beam current value is increased compared to the conventional one. For this reason, if the cluster ions of the same dose as in the prior art are irradiated, the irradiation time can be shortened compared to the prior art.

Further, the semiconductor wafer 10 includes, for example, a bulk single crystal wafer made of silicon or compound semiconductors (GaAs, GaN, SiC) and does not have an epitaxial layer on its surface. Further, as the semiconductor wafer 10, a silicon wafer obtained by slicing a single crystal silicon ingot grown by the Czochralski method (CZ method) or the floating band melting method (FZ method) with a jigsaw or the like can be used. In addition, carbon and/or nitrogen may be added to the silicon wafer. Moreover, it is good also as n-type or p-type by adding arbitrary impurity dopant. Further, as the semiconductor wafer 10, an epitaxial semiconductor wafer having a semiconductor epitaxial layer formed on the bulk semiconductor wafer surface may be used.

Further, the dose amount of cluster ions can be adjusted by controlling the beam current value and the ion irradiation time. The amount of carbon in the cluster ion can be, for example, 1×10 ^{13 to} 1×10 ¹⁶ atoms/cm ² . And, as already described, the beam current value can be 1000 μA or more, 1200 μA or more, 1500 μA or more, 1800 μA or more, and further, 2000 μA or more.

(Reference embodiment: manufacturing method of semiconductor epitaxial wafer)

2A to 2C, a cluster ion beam C generated using the embodiment of the cluster ion beam generation method is irradiated onto the surface 10A of the semiconductor wafer 10 ( 2(a)), a cluster ion beam irradiation step of forming a modified layer 18 in which constituent elements of cluster ions are solid solution on the surface of the semiconductor wafer 10 (FIG. 2(b)), By including the epitaxial layer forming process of forming the epitaxial layer 20 on the modified layer 18 of the semiconductor wafer 10 (Fig. 2(c)), the semiconductor epitaxial wafer 100 can be manufactured. have.

[0045] The modified layer 18 formed by the cluster ion beam irradiation process is a region in which carbon is dissolved locally at an interstitial position or a substitution position of a crystal in the surface portion of the semiconductor wafer 10 , Can act as a powerful gettering site.

In the epitaxial layer forming process, as the epitaxial layer 20 formed on the modified layer 18, a silicon epitaxial layer may be mentioned, and may be formed under general conditions. For example, a source gas such as dichlorosilane or trichlorosilane is introduced into the chamber using hydrogen as a carrier gas, and the growth temperature varies depending on the source gas used, but the CVD method is applied at a temperature in the range of approximately 1000 to 1200°C. Thus, epitaxial growth can be performed on the semiconductor wafer 10. The thickness of the epitaxial layer 20 is preferably in the range of 1 to 15 μm.

[0047] By using the cluster ion beam irradiation method according to the present embodiment, the throughput when manufacturing a semiconductor epitaxial wafer having excellent gettering ability can be improved than before.

Example

Hereinafter, the present invention will be described in more detail using examples, but the present invention is not limited to the following examples.

[0049] (Invention Example 1)

Using a cluster ion generator (manufactured by NISSIN ION EQUIPMENT CO. LTD., model number: CLARIS), using 2-methylpentane (C ₆ H ₁₄ ) as a raw material, cluster ionized C ₃ H ₅ cluster ions Was created. The beam current value of the obtained cluster ion beam was 2000 μA.

[0050] (Invention Example 2)

In Invention Example 1, in the same manner as In Invention Example 1, except that 2,4-dimethylpentane (C ₇ H ₁₆ ) was used as a raw material instead of 2-methylpentane, cluster ion of C ₃ H ₅ was cluster-ionized. Was created. The beam current value of the obtained cluster ion beam was 1800 µA.

[0051] (Conventional Example 1)

In Inventive Example 1, instead of 2-methylpentane, cyclohexane (C ₆ H ₁₂ ) was used as a raw material, in the same manner as in Inventive Example 1, cluster ionized C ₃ H ₅ cluster ions were generated. The beam current value of the obtained cluster ion beam was 800 µA.

[0052] (Comparative Example 1)

In Inventive Example 1, instead of 2-methylpentane, hexane (C ₆ H ₁₄ ) was used as a raw material, in the same manner as In Inventive Example 1, cluster ionized C ₃ H ₅ cluster ions were generated. The beam current value of the obtained cluster ion beam was 800 µA.

[0053] (Comparative Example 2)

In Inventive Example 1, in the same manner as In Invention Example 1, except that 2,3-dimethylbutane (C ₆ H ₁₄ ) was used as a raw material instead of 2-methylpentane, cluster ion of C ₃ H ₅ was cluster-ionized. Was created. The beam current value of the obtained cluster ion beam was 20 µA.

The results of the above, Inventive Examples 1 and 2, Conventional Examples 1, and Comparative Examples 1 and 2 are shown in Table 1 below.

[0055] [Table 1]

[0056] <Evaluation>

In Inventive Examples 1 and 2, it was confirmed that a beam current value equal to or more than twice that of the beam current value obtained by the conventional example 1 was obtained. Inventive Examples 1 and 2, unlike Conventional Examples 1 and 1, contain tertiary carbon atoms, so that bond separation is liable to occur, and as a result, cluster ions of C ₃ H ₅ are easily extracted. I think. On the other hand, in Comparative Example 2, although tertiary carbon atoms were contained, since there were many discharges and it was difficult to form a cluster ion beam, the beam current value was smaller than in Conventional Example 1. This is considered to be because the bond between the tertiary carbons in the center of 2,3-dimethylbutane is very weak, and the ion generation proceeded explosively to the extent that it is difficult to control the generation of cluster ions.

Industrial availability

According to the present invention, it is possible to provide a cluster ion beam generation method capable of increasing the beam current value of the cluster ion beam compared to the conventional one. Furthermore, the present invention can provide a cluster ion beam irradiation method capable of increasing the beam current value than the conventional one. Therefore, it is particularly useful in the semiconductor industry.

1: raw material
2: cluster ion
4: monoatomic ion
6: polyatomic ion
10: semiconductor wafer
10A: surface of semiconductor wafer
18: modified layer
20: epitaxial layer
100: semiconductor epitaxial wafer
C: cluster ion beam
T: target

Claims (6)

A cluster ion beam generation method for generating a beam of cluster ions having carbon and hydrogen as constituent elements from a hydrocarbon-based compound raw material,
The hydrocarbon-based compound raw material is at least one compound selected from the group consisting of 2-methylpropane, 2-methylbutane, 2-methylpentane, 2-methylhexane, and 2,4-dimethylpentane. delete delete delete delete A cluster ion beam irradiation method comprising irradiating the surface of a semiconductor wafer with a cluster ion beam generated using the cluster ion beam generating method according to claim 1.

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