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Heteroepitaxial structure and method for producing same, metal layered product containing heteroepitaxial structure and method for producing same, and nanogap electrode and method for producing nanogap electrode NEW

外国特許コード F200010270
整理番号 J1035-03TW
掲載日 2020年11月9日
出願国 台湾
出願番号 108131601
公報番号 202014556
出願日 令和元年9月3日(2019.9.3)
公報発行日 令和2年4月16日(2020.4.16)
優先権データ
  • 特願2018-187109 (2018.10.2) JP
  • 特願2019-005299 (2019.1.16) JP
発明の名称 (英語) Heteroepitaxial structure and method for producing same, metal layered product containing heteroepitaxial structure and method for producing same, and nanogap electrode and method for producing nanogap electrode NEW
発明の概要(英語) This heteroepitaxial structure includes: a first metal part having a polycrystalline structure; and a second metal part on the first metal part. The second metal part has an island-like structure on the first metal part. The second metal part is provided so as to correspond to at least one crystal grain that is exposed at the surface of the first metal part. The second metal part and at least one crystal grain form a heteroepitaxial boundary. The first metal part preferably contains at least one element selected from among platinum (Pt)). The second metal part is preferably gold (Au).
従来技術、競合技術の概要(英語) Background of the Invention]
One embodiment of the present invention relates to techniques for heteroepitaxial growth by electroless plating. And, One embodiment of the present invention relates to a nanometer slit electrode comprising regions that have been grown by electroless plating of heteroepitaxial crystals.
[Prior Art]
Electroplating and electroless plating is one of the techniques widely used in the industry, and is used for a variety of applications. For example, at the site of production of electronic parts, techniques for processing electrodes by gold plating are well known. Gold ( Au ) is a chemically very stable metal, which is widely used in electronic parts. For example, in electronic parts, is used as electrode material due to good wetting or wire bonding properties of solder,. The gold ( Au ) envelope may be formed by electroplating. However, gold ( Au ) is a soft metal, so in the case of forming a coating of gold ( Au ) by electroplating, a coating of cobalt ( Co ), nickel ( Ni ), etc. is formed on the substrate surface to seek hardening.
Plating is a technique known from time to time, but various studies have been carried out. For example, a study has been made on platinum ( Pt ) to grow the envelope of gold ( Au ) into layers by electroplating (refer to Non-Patent Document 1 ). And, there is disclosed a technique for precipitating gold ( Au ) reduced from gold chloride at the surface of spherical platinum ( Pt ) species (cf. patent document 1 ).
'Non-patent document' Non-patent document 1 Stephen Ambrozik , Corey Mitchell , and Nikolay Dimitrov, " The Spontaneous Deposition of Au on Pt ( 111 ) and Polycrystalline Pt " , Journal of The Electrochemical Society , 163 ( 12 ) , D3001-D3007 , ( 2016 )
'Patent Document' Patent Document 1 International Patent Publication No. 2010/016798
[Inventory]
However, Technology for the growth of precious metal heteroepitaxial growth by electroless plating, has not been reported to date. Method for causing metal to precipitate on the surface of a material with respect to an electroplating system, Electroless plating is a method for causing metal ions to precipitate on top of the material by a chemical reaction based on the reducing force of the metal ions and the reducing agent,. It is therefore, the case where electroless plating is difficult to grow the plating film due to the type of material, there is a problem that it is difficult to form a plating film having high tightness and low contact resistance.
One embodiment of the present invention relates to a heteroepitaxial structure, having "th 1 metal portion having a polycrystalline structure" and "th 2 metal portion on 1 th 1 metal portion " , th 2 metal portion having an island-like structure on th 1 metal portion, th 2 metal portion corresponding to at least one junction grain exposed on the surface of the 1 th 1 metal portion, th 2 metal portion forming a heteroepitaxial boundary with at least one junction grain.
One embodiment of the present invention relates to a metal stack comprising a heteroepitaxial structure, having "th 1 metal portion having a polycrystalline structure" and "th 2 metal portion " , th 2 metal portion having an island-like structure on th 1 metal portion, The 2 th metal portion corresponds to at least one junction grain; which is exposed on the surface of the 1 th metal portion and comprises the 3 th metal portion, which is disposed in such a manner that a portion of the 2 th metal portion forms a heteroepitaxial grain boundary with the at least one junction grain.
One embodiment of the present invention relates to a method of making a metal stack comprising a heteroepitaxial structure, comprising: immersing a 1 th metal portion having a polycrystalline structure in an electroless plating solution comprising a 2 th metal ion of a different species from the 1 th metal portion, an ion of a halide element as an oxidizing agent, and a reducing agent, The surface of the 1 th metal portion is reduced by an oxidizing agent and a reducing agent, while the metal reduced by electrochemical substitution reaction from the metal ion of the 2 th metal, is heteroepitaxial grown corresponding to the reduced surface of at least one junction crystal of the 1 th metal portion.
One embodiment of the present invention relates to a method of making a metal stack comprising a heteroepitaxial structure, comprising: immersing a 1 th metal portion having a polycrystalline structure in an electroless plating solution comprising a 2 th metal ion of a different species from the 1 th metal portion, an ion of a halide element as an oxidizing agent, and a reducing agent, Reducing the surface of the 1 th metal portion by oxidizing agent and reducing agent, while reducing the metal from the 2 th metal ion by electrochemical substitution, After heteroepitaxial growth corresponding to the reduced surface of at least one junction crystal of the 1 th metal portion, the 3 th metal portion is formed over the 1 th metal portion in such a manner that the 2 th metal portion is covered.
One embodiment of the present invention relates to a nanometer slit electrode, having a 1 -th electrode and a 2 -th electrode, said 1 -th electrode and 2 -th electrode comprising a 1 -th metal portion having a polycrystalline structure and a 2 -th metal portion on a 1 -th metal portion, respectively, wherein the 1 -th metal portion has a linear pattern having a width of less than 20 nm and the 2 -th metal portion is disposed at least at one end of the linear pattern of the 1 -th metal portion. The 2 th metal portion has an island-like structure on the 1 th metal portion, forming a heteroepitaxial grain boundary corresponding to at least one junction grain exposed on the surface of the 1 th metal portion, The 2 th metal portion belonging to the 1 th electrode is spaced from the 2 th metal portion belonging to the 2 th electrode by less than 5 nm.
One embodiment of the present invention relates to a nanometer slit electrode, having a 1 -th electrode and a 2 -th electrode, said 1 -th electrode and 2 -th electrode comprising a 1 -th metal portion having a polycrystalline structure and a 2 -th metal portion on a 1 -th metal portion, respectively, wherein the 1 -th metal portion has a linear pattern having a width of less than 15 nm and the 2 -th metal portion continuously covers the surface of the 1 -th metal portion. The 2 th metal portion includes a region corresponding to the exposed junction grains of the 1 th metal portion to form a heteroepitaxial interface, The 1 th electrode and the 2 th electrode are each disposed at one end opposite and having a gap, the length of the gap being made 5 nm or less.
One embodiment of the present invention relates to a method of making a nanometer slit electrode, comprising: forming a linear pattern having a width below 20 nm by a 1 th metal portion having a polycrystalline structure, a 1 th electrode pattern and a 2 th electrode pattern arranged opposite one end and spaced apart, immersing the 1 th electrode pattern and the 2 th electrode pattern in a metal ion comprising a 2 th metal of a different kind than the 1 th metal portion, and forming a thin film of a thin film of a thin film. Electroless plating solution as ions of halide group elements of oxidizing agent and reducing agent, The surfaces of the 1 -th electrode pattern and 2 -th electrode pattern are reduced by oxidizing agent and reducing agent, and the metal reduced by electrochemical substitution reaction from the 2 -th metal ions, is heteroepitaxial grown in such a manner that the surfaces of the 1 -th electrode pattern and the 2 -th electrode pattern are continuously covered, and the 1 -th electrode pattern is formed at intervals opposite to the respective ends of the 2 -th electrode pattern to be 5 nm or less.
According to one embodiment of the present invention, a heteroepitaxial structure comprising a 2 th metal portion grown heteroepitaxial on the surface of the 1 th metal portion can be obtained. By using the 2 th metal portion to grow heteroepitaxial on the surface of the 1 th metal portion, it is possible to improve the tightness of the 1 th metal portion and the 2 th metal portion, to reduce the contact resistance. And, a metal stack comprising such a heteroepitaxial structure and a nanometer gap electrode may be provided.
[Embodiment]
An embodiment of the present invention will now be described with reference to drawings and the like,. However, the present invention can be implemented in a variety of different states, without being limited by the description of the implementation modes of the following examples. The drawings are intended to make the description more clear, in the case of a schematic representation of the width, thickness, shape, etc. of the various parts compared to the actual state, but ultimately as an example, are not intended to limit the interpreter of the present invention. And, In this specification and in the figures, sometimes the same components as those already described above with respect to the figures that have been presented, the same symbols (or the symbols a, b, etc. after the numbers ) , will be omitted in due course. Further, The words labeled ", 1 ",", 2 " of each component, are used to distinguish between inexpensive indicia of each component, without any additional meaning unless otherwise specified,.
Article 1
This embodiment is described in detail with respect to the construction and method of making heteroepitaxial structures.
1. Heteroepitaxial structure
Figs.1 illustrate cross-sectional views of one example of a heteroepitaxial structure 200 ( 200 a, 200 b, 200 c ) associated with one embodiment of the present invention and one example of a metal stack 202 containing the heteroepitaxial structure. Fig.1 is a conceptual diagram of a heteroepitaxial structure 200 made by electroless plating associated with one embodiment of the present invention, based on a secondary electron image of atomic resolution through a scanning electron microscope ( Scanning Electron Microscope : SEM ). Further, Electroplating relating to one embodiment of the present invention, will be described in detail in this embodiment and in Examples 1.
Fig.1 depicts the 1 th metal portion 104 and 2 th metal portions 108 ( 108 a, 108 b, 108 c ). 1 Metal 104 series Polycrystal, contains a plurality of junction grains 106 ( 106 a ~ 106 e ). A plurality of junction grains 106 ( 106 a ~ 106 e ) are formed on the surface of the 1 th metal portion 104 to form crystal surfaces respectively oriented in a specific orientation. The 2 th metal portion 108 corresponds to at least one of the junction grains 106 ( 106 a ~ 106 e ). For example, th 2 -th 2 -th 108 a -th 108 b -th 108 b -th 106 b , -th 108 c -th 108 c -th 106 c -th 108 c -th 106 c -th 108 b -th 108 c -th 106 c -th 108 b -th 106 c
2 Metal sections 108 ( 108 a, 108 b, 108 c ) are crystalline in the region, where the surface of the 1 metal section 104 is grown by heteroepitaxial growth. For example,, th 2 th 108 a th 108 a th 108 a th 104 th. That is, th 2 th 2 th 108 a th 108 a The 2 th metal portion 108 a , grown from the junction crystal 106 a heteroepitaxial growth may also be called a single crystal region as a result of the formation of a single crystal,. 2 Metal 108 a forms a heteroepitaxial interface with junction grains 106 a. And, With respect to the 2 th metal portion 108 b and 2 th metal portion 108 c , heteroepitaxial interfaces are also formed with junction grains 106 b and junction grains 106 c, respectively. Thus, heteroepitaxial structure 200 a is composed of junction grains 106 a and 2 metal portion 108 a of 1 metal portion 104 and, heteroepitaxial structure 200 b is composed of junction grains 106 b and 2 metal portion 108 b of 1 metal portion 104 and, heteroepitaxial structure 200 c is composed of junction grains 106 c and 2 metal portion 108 c of 1 metal portion 104.
2 Metal 108 The surface of 1 Metal 104 has an island-like structure of nanoscale dimensions. In other words,, th 2 th 108 th 108 th Further, In the present embodiment, the so-called nanoscale island-like structure is as described later, refers to an individual having a size of about 50 nm or less, the so-called appearance shape is mountain or hemispherical, making sense for distinguishing from spheroid. And, The so-called appearance shape is a mountain shape or hemispherical shape, meaning a shape in which the cross-sectional area in the horizontal direction of the 2 th metal portion 108 becomes smaller with the contact surface of the junction grains 106 toward the upper end side. Further, The so-called hemispherical system is called a curved continuous spherical surface, which is not limited to a true spherical surface. As shown by an enlarged view of the area surrounded by the circles drawn in Fig.1, th 2 metal part 108 c The contact angle θ with respect to the surface of the junction grains 106 c does not reach 90 degrees, a smooth mountain or hemispherical protrusion is formed by heteroepitaxial growth in a state of high wettability,.
Size of the 2 th metal portion 108 ( 108 a, 108 b, 108 c ) having an island-like structure of a nanoscale dimension, In a top view (In the case of the 1 th metal portion 104 viewed from above ) , has a width of 50 nm or less, preferably, or less, preferably 10 nm or less, from one end to the other. And, The 2 th metal portion 108 ( 108 a, 108 c ) has a height from the surface of 1 th metal portion 104, having a size of 40 nm or less, preferably 20 nm or less. 2 Metal sections 108 ( 108 a, 108 c ) have such a size, Isolated above 1 Metal section 104 while maintaining the crystalline structure.
In order for the 2 th metal portion 108 to grow heteroepitaxial on the surface of the junction grains 106, there is a need for lattice matching. The proportion of lattice mismatch between the lattice constant of junction grains 106 and the lattice constant of 2 th metal portion 108 is desirably 4 % or less, preferably 1 % or less.
In this embodiment mode, platinum ( Pt ) may be exemplified as a suitable metal material for forming the 1 th metal portion 104. And, gold ( Au ) may be exemplified as a suitable metal material for forming the 2 th metal portion 108. The lattice constant of platinum ( Pt ) exemplified as the 1 th metal portion 104 is 0.39231 nm , The lattice constant of gold ( Au ) exemplified as the 2 th metal portion 108 is 0.407864 nm. Ratio of lattice mismatch of platinum ( Pt ) to gold ( Au ) (mismatch rate) 3.9 % , so that the surface heteroepitaxial crystal of junction grains 106 formed from platinum ( Pt ) becomes the 2 th metal portion 108 formed from gold ( Au ). For example, in the case where the face orientation of the junction grains 106 is ( 111 ), the 2 th metal portion 108 also forms crystals having the same face orientation.
Further, th 1 metal portion 104 may also have a solid melt for gold ( Au ) that is 2 th 108 metal portion, in which case, a solid melt may be formed at the interface of the 1 th 104 metal portion with the 2 th 108 metal portion, while the 2 th 108 metal portion is grown heteroepitaxial. Thus, As the 1 th metal portion 104 , In addition to platinum ( Pt ), transition elements such as palladium ( Pd ), rhodium ( Rd ), ruthenium ( Ru ), osmium ( Os ), iridium ( Ir ), etc. may also be applied.
Fig.1 illustrates the 2 th metal portion 108 a and 2 th metal portion 108 c formed in an abutting manner and the 2 th metal portion 108 b formed in isolation therefrom. In the portion of the 2 th metal portion 108 a adjacent to the 2 th metal portion 108 c, it is envisioned that the bulky 2 th metal portion 108 a will begin heteroepitaxial growth first. That is,, it is contemplated that nucleation occurs first in a portion of junction grains 106 a (nucleation ) , occurs later in a portion of junction grains 106 c. 2 Metal section 108 a It is contemplated that during growth of the heteroepitaxial crystal will grow in the longitudinal (thickness direction) and the transverse (width direction). During this growth, it can be confirmed that the 2 th metal portion 108 a exceeds the junction grain boundary between junction grains, extends to an area adjacent to junction grains 106 c of junction grains 106 a, where junction grains boundary with the 2 th metal portion 108 c is formed.
There is a junction junction between the 2 th metal portion 108 a and the 2 th metal portion 108 c, It will be appreciated that the junction junction 106 a due to the 1 th metal portion 104 is different from the crystallization axis of the junction junction 106 c in addition to the growth of the two. So, between the 2 th metal portion 108 a and the 2 th metal portion 108 c of heteroepitaxial growth, it is conceivable that junction grain boundaries such as extending junction grain boundaries 106 a with junction grains 106 c may occur. This means heteroepitaxial growth on the surface of the 1 th metal portion 104 formed of polycrystals.
Fig.1 also shows a state in which the 2 th metal portion 108 a and the 2 th metal portion 108 b are disposed apart. In other words, Fig.1 shows a state where the surface of the junction grains 106 d does not grow heteroepitaxial. This means that nuclear generation occurs discretely, heteroepitaxial growth is a pattern of island growth, rather than a laminator.
Fig.1 depicts another heteroepitaxial structure 200 b that is isolated from heteroepitaxial structure 200 a. Heteroepitaxial structure 200 b is composed of junction grains 106 b of 1 th metal portion 104 and 2 metal portion 108 b, but these configurations are similar to heteroepitaxial structure 200 a.
Heteroepitaxial structure related to the present embodiment state 200 , The contact resistance can be reduced by virtue of the 2 th metal portion 108 , on which the 1 th metal portion 104 forms the heteroepitaxial interface with the junction grains 106 by increasing the tightness,.
2. Platinum ( Pt ) \ gold ( Au ) heteroepitaxial structure
Fig. 2 A, Fig. 2 B and Fig. 2 C show the results of a heteroepitaxial structure formed by electron microscopy to form a platinum ( Pt ) film having a polycrystalline structure as the 1 th metal portion 104 and using gold ( Au ) as the 2 th metal portion 108.
Fig. 2 A depicts a secondary electron image of atomic resolution observed through SEM in a scanning penetration electron microscope, Fig. 2 B depicts a dark field of view observed through a penetration electron microscope ( Transmission Electron Microscope : TEM ), Fig. 2 C depicts a bright field of view through TEM. Samples, observed here were stacked on silicon dioxide ( SiO2 ) with 2 nm film thickness of titanium ( Ti ) film, 9 nm film thickness of platinum ( Pt ) film, plus gold ( Au ) growers by electroless plating as described later in connection with the present embodiment. Figs. 2 A, 2 B, and 2 C depict the results of a cross-sectional view of a sample of such a structure as a focused ion beam cut to a depth of 60 nm degrees.
In the TEM dark field image of Fig. 2 B and the TEM bright field image of Fig. 2 C, striped structures were observed at platinum ( Pt ). The orientation of the stripes observed varies from place to place, it can be confirmed that platinum ( Pt ) has a polycrystalline structure. From the secondary electron image of the atomic resolution of Fig. 2 A: The striped structure observed in the region of platinum ( Pt ) extends to the region of gold ( Au ). It is thus known that gold on platinum ( Pt ) film ( Au ) grows heteroepitaxial depending on the crystalline structure of platinum ( Pt ) of the substrate (striped structure).
Further, Since striped structures in the TEM dark field image of Fig. 2 B, the TEM bright field image of Fig. 2 C penetrate electron microscope images, are consistent with SEM secondary electron images representing the pattern of cross-sectional surfaces, gold ( Au ) also grows heteroepitaxial in the depth direction. Gold ( Au ) Growth Zone, As schematically depicted in Fig.1, the protrusions are grown in a manner that forms an island-like structure (of nanoscale dimensions or a mountain or hemispherical shape). Surface Expansion of Gold ( Au ) on junction grains of Platinum ( Pt ) Platinum ( Pt ) The surface of the film was observed to be at an angle of less than 90 degrees from the surface of Gold ( Au ). Thus it was observed that: gold grown by electroless plating related to the present embodiment ( Au ) , In the case of platinum ( Pt ) surface wetted,, the formation of protrusions of the underweep island-like structure (or of the mountain or hemispherical).
3. Metal stack comprising heteroepitaxial structures
Next, a metal stack comprising a heteroepitaxial structure is disclosed. Metal stack comprising heteroepitaxial structure, As explained below, comprising 1 th metal portion, 2 th metal portion, and 3 th metal portion.
3-1 . Construction of a metal stack comprising a heteroepitaxial structure
Fig.1 also depicts a metal stack 202 comprising a heteroepitaxial structure. A metal stack 202 , comprising a heteroepitaxial structure has a configuration above the 1 th metal portion 104 provided with the 3 th metal portion 110 in such a manner that the 2 th metal portion 108 is covered. 2 Metal 108 is a region grown from the junction grains 106 heteroepitaxial, so that a metal stack 202 containing heteroepitaxial structures can also be considered to have a structure with 3 metal 110 disposed in such a manner that heteroepitaxial structures 200 a, 200 b are covered.
A metal stack 202 , comprising a heteroepitaxial structure is comprised of a plurality of heteroepitaxial structures 200. Metal stack containing heteroepitaxial structure 202 , a plurality of 2 th metal portions 108 in a spaced arrangement between the 1 th metal portion 104 and the 3 th metal portion 110. As explained with reference to Figs.1, the 2 th metal portion 108 corresponds to the junction grain 106 contained in the 1 th metal portion 104 and the heteroepitaxial growth region, has an isolated island-like structure.
3 Metal section 110 is formed of the same or different kinds of metallic material as 2 Metal section 108. For example, in the case where the 2 th metal portion 108 is formed of gold ( Au ), the 3 th metal portion 110 may be formed of gold ( Au ) which is a metal material of the same kind. And, No.3 Metal 110 may also be formed using, for example, platinum ( Pt ) as a metallic material of a different kind than gold ( Au ). Further, The 3 th metal portion may also be formed using an alloy (such as gold, palladium alloy). And, The 3 th metal portion 110 may have a crystalline structure, may also have an amorphous structure. For example,, th 3 th 3 th 110 th 110 th 108 th 110
Metal stack laminated with metal film, Peel off occurring at the interface between the metal film of the upper layer and the metal film of the lower layer becomes a problem. Here, Since the junction grains 106 of the 2 -th metal portion 108 and the 1 -th metal portion 104 form a heteroepitaxial interface, and are dispersed on the surface of the 1 -th metal portion 104, the 3 -th metal portion 110 becomes provided with an area in contact with the 1 -th metal portion 104 and an area in contact with the 2 -th metal portion 108.
3 Metal section 110 In the case of a metal material of the same kind as 2 Metal section 108, high compactness can be expected due to the affinity of the material. And, th 3 th 3 th 110 th 110 th 108 th 108 th. Even assuming the case where the tightness of the 1 th metal part 104 and the 3 th metal part 110 is poor (the case where the tightness of the (th metal part 110 is small ) , the peeling of the 3 th metal part 110 stacked on the 1 th metal part 104 can be prevented by increasing the tightness of the 2 th metal part 108 and the 3 th metal part 110,. Thus, by increasing the tightness of the 3 th metal portion 110 with the 2 th metal portion 108, the 3 th metal portion 110 can be prevented from peeling off from the 1 th metal portion 104 reducing the contact resistance.
That is, The 2 th metal portion constituting the heteroepitaxial structure 200 a is in a structurally stable state due to the formation of the heteroepitaxial interface with the junction grains 106 a, in a state that the continuity of the crystalline structure is maintained,. Thus, by using a metal material having a high tightness to the 2 th metal portion 108 as the 3 th metal portion 110 ,, the tightness of the 3 th metal portion 110 for the 1 th metal portion 104 can be improved, reducing the contact resistance. In other words, th 3 th 110 th 110 th 108 th 104 th 104 th 2 th 108 th 2 th
In order to improve the tightness of the 3 th metal portion 110 for the 1 th metal portion 104, in the face of the 1 th metal portion 104, it is preferable that a plurality of 2 th metal portions 108 be dispersed. For example,, th 2 th 2 th 108 th 108 th 104 And, with respect to the surface area of the 1 th metal portion 104, th 2 The proportion of the combined area of the metal portion 108 in contact with the 1 th metal portion 104 is preferably 0.1 ( 10 % ) or more and 0.8 ( 80 % ) or less. Through the 2 th metal portion 108 arranged at this density in the face of the 1 th metal portion 104, a metal stack 202 comprising a heteroepitaxial structure improves the tightness of the 1 th metal portion 104 with the 3 th metal portion 110, reduces the contact resistance.
As shown in Fig.1, a metal stack 202 comprising a heteroepitaxial structure is provided on a substrate 100. Between the base plate 100 and the 1 th metal portion 104, a base metal film 102 may also be provided. Base metal film 102 Non-essential construction, is provided to improve the tightness of the 1 th metal portion 104 to the substrate 100 and to reduce the contact resistance. In the case where the 1 th metal portion 104 is formed of a platinum ( Pt ) film,, the base metal film 102 is preferably formed using a metal material such as titanium ( Ti ), chromium ( Cr ), nickel ( Ni ), and the like. As the substrate 100 , a silicon substrate (a silicon wafer), a silicon oxide ( SiO2 ) film or a silicon nitride ( Si3N4 ) film on the surface of the silicon substrate, a SOI ( Silicon on Insulator ) substrate, a sapphire substrate, yttrium stabilized zirconia ( YSZ ) substrate, and the like may be used.
3-2 . Contact resistance of a metal stack comprising a heteroepitaxial structure
Metal stack comprising heteroepitaxial structures 202 , comprising heteroepitaxial structures 200 a, 200 b and stacked with 3 th metal portion 110. 3 Metal section 110 is provided in such a manner that the 2 th metal section 108 above the 1 th metal section 104 is covered. 3 Metal section 110 and 2 Metal section 108 are formed of the same or different kinds of metallic material, but in the case where at least 2 Metal section 108 is formed of gold ( Au ) the contact resistance of, and 3 Metal section 110 becomes smaller. Thus, in a metal stack 202 comprising a heteroepitaxial structure comprising a structure having a 1 -th metal portion 104 and a 3 -th metal portion 110, the effect of the contact resistance of the 2 -th metal portion 108 and the 3 -th metal portion 110 on the overall contact resistance can be said to be low.
On the other hand, the 3 th metal portion 110 has an interface in contact with the 1 th metal portion 104. That is,, th 1 th 1 th 104 th 104 th 108 th 110 th 110 th. The 1 th metal portion 104 forming the heteroepitaxial interface and the 2 th metal portion 108 , have very low contact resistance due to the formation of metal bonds. On the other hand, the 1 -th metal portion 104 and the 3 -th metal portion 110 As the surface of the platinum ( Pt ) forming the 1 -th metal portion 104 is formed with platinum oxide ( PtO or Pt2O ) , it becomes a structure in which physical contact is not formed with metal bonds.
1 Metal 104 Interface in physical contact with 3 Metal 110, is also an important factor in reducing compactness. Further, Since platinum oxide ( PtO or Pt2O ) is an insulator that covers the surface of platinum ( Pt ), the electrical conduction of the portion of the 1 th metal portion 104 in physical contact with the 3 th metal portion 110 becomes due to tunneling effects. And, th 1 metal portion 104 part of the interface in physical contact with the 3 th 3 metal portion 110, the exposed area of platinum ( Pt ) having the 1 th 1 metal portion 104, In the case where the 3 th 3 metal portion 110 is formed of gold ( Au ), the platinum ( Pt ) is in ohmic contact with gold ( Au ) to form a low-resistance contact area.
In the metal stack 202 containing the heteroepitaxial structure, If "th 1 th 1 th 1 th 110 th 110 th 1 th 110 th 1 th And, the proportion of the physical contact interface of the ohmic contact in the physical contact interface, depends on the fabrication process of the stack of metals.
In the metal stack 202 comprising the platinum ( Pt ) \ gold ( Au ) heteroepitaxial structure, the resistance Rt between the platinum ( Pt ) film forming the 1 th metal portion 104 and the gold ( Au ) forming the 2 th metal portion 108 is as shown in formula ( 1 ), the sum of the resistance R1 of the 1 th metal portion 104 ( Pt film), the contact resistance Rc in the heteroepitaxial interface described above, and the resistance R2 of the 2 th metal portion 108 ( Au ). Rt = R1 + Rc + R2 ( 1 ) R1 =p1d1/S R2 =p2d2/S Rj =pj0/( S x a ) Rp =pp0/( S x ( 1 - a ) ) Rc = RjRp / ( Rj + Rp ) This , ρ1 : Volume resistivity of metal portion 104 ( Pt ) ( 1.04 x 10-7 ωm ) , d1 : film thickness of metal portion 104 ( Pt ) , S : area of metal stack , ρ2 : volume resistivity of gold ( Au ) ( 2.44 x 10-8 ωm ) , d2 : 2 Film thickness of metal portion 108 ( Au ), pj0: Resistances per unit area of heteroepitaxial interface (Units Qm2 ) , p0: Resistances per unit area of physical contact interface portion (Units Qm2 ) , a : Area Ratio (...)
特許請求の範囲(英語) [claim1]
1. A heteroepitaxial structure, characterized by having a: th 1 metal portion having a polycrystalline structure, and a 2 th 2 metal portion on the 1 th 1 metal portion, wherein the 2 th 2 metal portion has an island-like structure on the 1 th 1 metal portion, the 2 th 2 metal portion corresponding to at least one junction grain exposed on the surface of the 1 th 1 metal portion, the 2 th 2 metal portion forming a heteroepitaxial interface with the at least one junction grain.

[claim2]
2. The heteroepitaxial structure of claim 1 wherein said 1 th metal portion comprises a metal element selected from the group consisting of platinum ( Pt ), palladium ( Pd ), rhodium ( Rd ), ruthenium ( Ru ), osmium ( Os ), iridium ( Ir ), said 2 th metal portion is gold ( Au ).

[claim3]
3. The heteroepitaxial structure of claim 1 wherein said 1 th metal portion is palladium ( Pd ) , said 2 th metal portion is gold ( Au ) , The interface between said 1 th metal portion and said 2 th metal portion comprises a solid melt of said 1 th metal portion and said 2 th metal portion.

[claim4]
4. The heteroepitaxial structure of claim 1, wherein the island-like structure has a mountain or hemispherical shape.

[claim5]
5. A metal stack comprising a heteroepitaxial structure, characterized by a 3 th metal portion overlying the heteroepitaxial structure of any one of claims 1 and even 4.

[claim6]
6. The metal stack comprising a heteroepitaxial structure as recited in claim 5 wherein said 2 th metal portion is disposed a plurality of discrete surfaces of said 1 th metal portion.

[claim7]
7. The metal stack comprising a heteroepitaxial structure as recited in claim 6 wherein said 2 th metal portion is dispersed on a surface of said 1 th metal portion at a density of 50 or more/μm2 and 2000 or less/μm2 per unit area.

[claim8]
8. The metal stack comprising a heteroepitaxial structure as recited in Claim 6 wherein the surface area relative to the aforementioned 1 th metal portion, and the proportion of the combined area of the aforementioned 2 th metal portion in contact with the aforementioned 1 th metal portion is 0.1 or more and 0.8 or less.

[claim9]
9. The metal stack comprising a heteroepitaxial structure, as claimed in any one of claims 5 or even 8, wherein the aforementioned 3 th metal portion is a metal of the same kind or a metal of a different kind, or an alloy as the aforementioned 2 th metal portion.

[claim10]
10. A method of making a heteroepitaxial structure, characterized by: immersing a 1 th metal portion having a polycrystalline structure in an electroless plating solution comprising a 2 th metal ion of a different species from the 1 th metal portion, an ion of a halide group element as an oxidizing agent, and a reducing agent, Reducing the surface of the aforementioned 1 -th metal portion by the aforementioned oxidizing agent and the aforementioned reducing agent, while allowing heteroepitaxial growth of the metal reduced by the electrochemical substitution reaction from the metal ion of the aforementioned 2 -th metal, corresponding to the reduced surface of at least one junction crystal of the aforementioned 1 -th metal portion.

[claim11]
11. The method of making a heteroepitaxial structure as claimed in claim 10, wherein said at least one junction grain and heteroepitaxial interface is formed by said heteroepitaxial growth, and said 2 th metal portion having an island-like structure is formed on a surface of said 1 th metal portion.

[claim12]
12. The method for producing a heteroepitaxial structure as described in Claim 10 or Claim 11, wherein said 1 metal moiety is platinum, said metal ion is gold ion ( Au +, Au3 + ) , said halide ion is iodine ion ( I-, I3 - ) , said reducing agent is L ( + ) -ascorbic acid ( C6H8O6 ).

[claim13]
13. The method for producing a heteroepitaxial structure as claimed in claim 10, wherein the electroless plating solution is diluted 500 times more with pure water.

[claim14]
14. The method for producing a heteroepitaxial structure as described in claim 12, wherein the aforementioned 1 metal portion is impregnated with iodine and L ( + ) -ascorbic acid ( C6H8O6 ) prior to immersing the aforementioned 1 metal portion in the electroless plating solution.

[claim15]
15. A method of making a metal stack comprising a heteroepitaxial structure, characterized by forming a 3 th metal portion overlying said 1 th metal portion after forming a heteroepitaxial structure as described in any one of claims 11 and even 14.

[claim16]
16. The method of making a metal stack comprising a heteroepitaxial structure as recited in claim 15 wherein said 2 th metal portion is formed in a manner that is discrete from a surface of said 1 th metal portion.

[claim17]
17. The method of making a metal stack comprising a heteroepitaxial structure as recited in claim 16 wherein the aforementioned 2 th metal portion is formed in such a manner that the surface of the aforementioned 1 th metal portion is dispersed at a density of 50 or more/μm2 and 2000 or less/μm2 per unit area.

[claim18]
18. The method for manufacturing a metal stack comprising a heteroepitaxial structure as described in any one of claims 15 or even 17, wherein the aforementioned 3 th metal portion is formed from the same kind of metal or a different kind of metal as the aforementioned 2 th metal portion.

[claim19]
19. A nemeter-gap electrode, characterized by having a 1 th electrode and a 2 th electrode, said 1 th electrode and 2 th electrode comprising a 1 th metal portion having a polycrystalline structure and a 2 th metal portion on said 1 th metal portion, respectively, wherein said 1 th metal portion has a linear pattern having a width of 20 nm or less, said 2 th metal portion being disposed at least at one end of said linear pattern of said 1 th metal portion, The aforementioned 2 th metal portion has an island-like structure on the aforementioned 1 th metal portion, corresponding to at least one junction grain exposed on the surface of the aforementioned 1 th metal portion to form a heteroepitaxial grain boundary surface, The aforementioned 2 th metal portion belonging to the aforementioned 1 th electrode is spaced from the aforementioned 2 th metal portion belonging to the aforementioned 2 th electrode by 5 nm or less.

[claim20]
20. The nanometer gap electrode, as claimed in claim 19 wherein said 2 th metal portion comprises a plurality of crystalline regions having different crystal orientations.

[claim21]
21. The nanometer gap electrode, as claimed in claim 19 wherein said 2 th metal portion is hemispherical.

[claim22]
22. The nanometer gap electrode as claimed in Claim 19, wherein said 1 th metal portion comprises a metal element selected from the group consisting of platinum ( Pt ), palladium ( Pd ), rhodium ( Rd ), ruthenium ( Ru ), osmium ( Os ), iridium ( Ir ), and said 2 metal portion is gold ( Au ).

[claim23]
23. The nanometer gap electrode, as claimed in claim 19 wherein the aforementioned 1 metal portion is palladium ( Pd ) , the aforementioned 2 metal portion is gold ( Au ) , and the interface between the aforementioned 1 metal portion and the aforementioned 2 metal portion comprises a solid melt of the aforementioned 1 metal portion and the aforementioned 2 metal portion.

[claim24]
24. A nanometer slit electrode, as claimed in claim 19 wherein said 2 th metal portion is disposed on one end of a slightly central axis of said linear pattern of said 1 th metal portion.

[claim25]
25. A nemeter-gap electrode, characterized by having a 1 th electrode and a 2 th electrode, said 1 th electrode and 2 th electrode comprising a 1 th metal portion having a polycrystalline structure and a 2 th metal portion on said 1 th metal portion, respectively, wherein said 1 th metal portion has a linear pattern having a width of less than 15 nm. The aforementioned No.2 metal portion continuously covers the surface of the aforementioned No.1 metal portion, The aforementioned No.2 metal portion includes a region corresponding to the exposed junction grains of the aforementioned No.1 metal portion to form a heteroepitaxial interface, The respective ends of the aforementioned No.1 electrode and the aforementioned No.2 electrode are arranged opposite and have a gap, the length of the aforementioned gap is 5 nm or less.

[claim26]
26. The nanometer gap electrode, as claimed in claim 25 wherein said 2 th metal portion comprises a plurality of crystalline regions having different crystal orientations.

[claim27]
27. The nanometer gap electrode as claimed in Claim 25, wherein said 1 th metal portion comprises a metal element selected from the group consisting of platinum ( Pt ), palladium ( Pd ), rhodium ( Rd ), ruthenium ( Ru ), osmium ( Os ), iridium ( Ir ), and said 2 metal portion is gold ( Au ).

[claim28]
28. The nanometer gap electrode, as claimed in claim 25 wherein the aforementioned 1 metal portion is palladium ( Pd ) , the aforementioned 2 metal portion is gold ( Au ) , and the interface between the aforementioned 1 metal portion and the aforementioned 2 metal portion comprises a solid melt of the aforementioned 1 metal portion and the aforementioned 2 metal portion.

[claim29]
29. A method of making a Nemi slit electrode, characterized by: forming a 1 electrode pattern and a 2 electrode pattern having a linear pattern having a width of 20 nm or less, an opposite and spaced apart end of each electrode pattern, immersing said 1 electrode pattern and said 2 electrode pattern in an electroless plating solution comprising metal ions of 2 metal of a different species from said 1 metal portion, ions of a halide group element as an oxidizing agent and a reducing agent, Reducing the surface of the aforementioned 1 -th electrode pattern and the aforementioned 2 -th electrode pattern by the aforementioned oxidizing agent and the aforementioned reducing agent, while heteroepitaxial growth of the metal, reduced by electrochemical substitution reaction from the aforementioned 2 -th metal in such a manner as to continuously cover the surfaces of the aforementioned 1 -th electrode pattern and the aforementioned 2 -th electrode pattern, The aforementioned 1 -th electrode pattern and the aforementioned respective ends of the aforementioned 2 -th electrode pattern are separated by 5 nm or less.

[claim30]
30. The method of manufacturing a nanometer gap electrode as claimed in claim 29, wherein the 2 th metal portion forming the heteroepitaxial interface on the surface of the 1 th metal portion is grown into hemispherical shape by the heteroepitaxial growth,.
[claim31]
31. The method of manufacturing a nanometer slit electrode as claimed in claim 29, wherein the 2 th metal portion is grown by the heteroepitaxial growth, in such a way that the surface of the 1 th metal portion is coated.
[claim32]
32. The method of making a nanometer gap electrode as claimed in claim 29, wherein said 1 metal moiety is platinum, said metal ion is gold ion ( Au +, Au3 + ) , said halide ion is iodine ion ( I-, I3 + ) , said reducing agent is L ( + ) -ascorbic acid ( C6H8O6 ).
  • 出願人(英語)
  • JAPAN SCIENCE AND TECHNOLOGY AGENCY
  • 発明者(英語)
  • MAJIMA YUTAKA
  • CHOI YOON-YOUNG
  • SHIMADA IKUKO
  • TOYAMA RYO
  • YANG MING-YUE
国際特許分類(IPC)
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