JP2007144686A - Electro conductive multilayered film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enhance the performance capability of an element such as a high performance memory, a capacity element, etc., which is used in the electronic circuit in an electronic device, especially an extremely small-sized high speed operation memory circuit or an integrated circuit operated in a high frequency region and has a combination of a dielectric and a conductive multilayered film as a basic constitution. <P>SOLUTION: A first conductor thin film 103 is constituted of the first inclined function region 131 arranged on the side of a second conductor thin film 102 and the first conductor phase 132 arranged on the side of a dielectric phase 104. The first inclined function region 131, which constitutes the first conductor thin film 103, is gradually changed at least in one state among a chemically bonded state, an atomic arrangement structural state and an electrically specific state from the side of an electrode 101 to the side of a dielectric phase 104 and has an inclination function for realizing the enhancement of lattice alignment due to buffering action and the enhancement of diffusion controllability due to barrier action. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to dielectrics used in electronic circuits in a wide variety of electronic devices, in particular, ultra-compact high-speed memory circuits and integrated circuits that operate in a high-frequency region such as mobile communication, satellite communication, and satellite broadcasting. The present invention relates to a conductive multilayer film used for improving the performance of an element in a high performance memory / capacitor element having a combination of conductive multilayer films as a basic configuration.

  Conventionally, a high-frequency / high-speed operation (high-speed switching operation) circuit composed of a metal-oxide-semiconductor field-effect transistor (MOSFET) or a memory has an active element part and a passive element part composed of a capacitive element. Are assembled as individual independent element parts through an insulating substrate. In some cases, the passive element section itself is assembled by combining some capacitive elements as individual components.

  However, with such a method, it is difficult to reduce the size and speed, and the electrical characteristics such as the matching characteristics vary depending on the assembly position, so that it is difficult to mass-produce circuits with a certain quality with a high yield. In addition, the performance of existing capacitive elements that can be manufactured monolithically was inadequate, which limited the circuit design freedom. On the other hand, if individual parts having a large element volume are used instead in order to avoid this, there is a problem that it is difficult to reduce the size due to the high integration described above, to reduce the high speed and to change the electrical characteristics.

  In order to solve these problems, individual element parts must be monolithically constructed on a minimal substrate, or ultimately oriented toward highly integrated and high-density integrated circuits, so-called system-on-chip. It is indispensable to realize the device configuration.

  When considering a memory / capacitance element whose basic configuration is composed of a dielectric and a conductor, especially a non-volatile memory element that retains the memory effect, the first step is to reduce size, increase gain, and reduce power consumption. It is essential to realize a dielectric with a large quality factor (Q) value, low high-speed switching operation (high frequency) loss related to the improvement of the self-resonant frequency (f), and a large capacitance (capacitance: C) value. It becomes. In addition, it has a high conductivity (σ) and a small inductance (L) component, and it can also compensate for component element deficiencies associated with polarization inversion of the dielectric, and can serve as a base substrate when forming the dielectric. Realization of a conductive thin film is also essential.

  In addition, after using each thin film having the above-mentioned characteristics, as a combined element, firstly, a characteristic that a remanent polarization is large and a coercive electric field is small, a characteristic that a remanent magnetization is large and a squareness ratio is excellent. Is required. In addition, the fatigue characteristics associated with repeated pulse application are good, the leakage current related to hysteresis deterioration is small, and the hysteresis characteristics deterioration is small in the polarization generation / temperature rise state (imprint characteristics are excellent) ( Characteristics) is also required.

The basic components responsible for the memory function of memory circuit elements that require such performance, the so-called capacitor section, can be downsized and increased in capacity to realize higher performance such as higher density and higher integration of elements. Indispensable. In order to reduce the size and increase the capacity of this capacitor, it is necessary to increase the dielectric constant (ε) of the dielectric, improve the DC bias characteristics, and promote the thinning of the dielectric layer by increasing the breakdown voltage. . For example, xPb (Fe _2/3 W _1/3 ) O ₃ (1-x) Pb (Fe _1/2 Nb _1/2 ) O ₃ or Pb (Zn _1/3 ) may be used as an existing practical level dielectric. Nb _2/3 ) _y (Fe _1/2 Nb _1/2 ) _0.64-y (Fe _2/3 W _1/3 ) _0.36 O ₃ is applied, and the resistance capacitance product (CR product) is 6000 MΩ · μF [C = 10 to 400 (μF)], a dielectric loss (tan δ) of 0.6%, and a capacitance temperature change rate of about −70 to −80% are realized. However, in this configuration, the frequency dependency and temperature dependency of the capacitance are large, and in the GHz order, not only the capacitance is drastically reduced but also the dielectric loss is remarkably increased, so that a stable high-performance capacitor is obtained. It was difficult.

In particular, in order to realize high density and high integration of circuits, it is most important to increase the dielectric constant of the dielectric in the high frequency region. Taking a resonator as an example, the wavelength of an electromagnetic wave inside a dielectric is shortened in inverse proportion to the square root of the dielectric constant (ε ₀ ) in free space. The size of becomes smaller as the dielectric constant increases. On the other hand, as the dielectric constant increases, the dielectric loss increases and the Q value tends to decrease. Further, the temperature coefficient of the resonance frequency of the resonator has a positive correlation between the temperature coefficient of the dielectric constant and the thermal expansion coefficient. Therefore, as a dielectric, the dielectric constant is large and the value of the dielectric constant is stable, and both the temperature coefficient and the thermal expansion coefficient of the dielectric constant are both as small as possible, and their variations are also small. A high Q value in the order of GHz is required.

For example, the existing dielectric which can cope with practical level below the high frequency region 2 GHz, include _{BaO · Sm 2 O 3 · 5TiO} 2 or _{BaO-PbO-Nd 2 O 3} -TiO 2, the relative dielectric constant ( ε ′) is 75 or more and a Q value of about 4000 to 5000 is realized. Moreover, if it is 2 GHz or more, Ba (Zn _1/3 Nb _2/3 ) O ₃ —Ba (Zn _1/3 Ta _2/3 ) O ₃ , Ba (Ni _1/3 Ta _2/3 ) O ₃ − Ba (Zr _1/3 Zn _1/3 Ta _1/3 ) O ₃ , Ba (Co _1/3 Nb _2/3 ) O ₃ —Ba (Zn _1/3 Nb _2/3 ) O ₃ , Ba (Mg _{1 /} by 3 Ta _2/3) applying O _3, relative permittivity of about 30, Q values are achieved of about 10,000 to 35,000. However, as described above, since the permittivity and the Q value tend to conflict with each other, it is difficult to obtain a stable high-performance capacitor because both the permittivity and the Q value are large.

Dielectrics applied to MOSFETs and memories, which are more sophisticated elements composed mainly of capacitors, have a large dielectric constant and maintain stable characteristics even in the high frequency range, and are subject to secular changes such as characteristic deterioration. As a matter of course, the lattice matching and diffusion characteristics at the interface between the dielectric and the adjacent conductive thin film (electrode) are good, and the generation of interface states and fixed charges is suppressed as much as possible. High controllability of so-called interface characteristics is also essential. Up to now, considering this interface characteristic, application of Si ₃ N ₄ , Al ₂ O ₃ , Ta ₂ O ₅ film, etc. has been studied, but these have a relative dielectric constant of 10 (˜20) or less. small, the interface state density is large as 10 ¹¹ cm ^-2 eV ^-1 degree or more, not the dielectric properties obtained only exceeding the leakage current density 10 ^-6 Acm ^-2 (1V). In addition, the deterioration of these dielectric characteristics due to secular change is large, and the controllability of the interface characteristics is very poor, and it is extremely difficult to put into practical use a stable high-performance memory / capacitor element.

As a more specific example, high integration, high-speed operation, low power consumption, and high reliability equivalent to DRAM (dynamic random access memory), which are expected to be applied to main storage devices in future electronic devices, FeRAM (ferroelectrics random access memory), which is one of the non-volatile memories, is also required to have the following characteristics. First, there is a demand for fatigue characteristics that have a large remanent polarization, a low coercive electric field, excellent hysteresis in squareness ratio, and that do not deteriorate in polarization even when 10 ¹² or more repetitive pulses are applied. In addition, since the hysteresis deteriorates when leak current flows, it is also required to have characteristics such as low leak current and excellent imprint characteristics that do not shift hysteresis characteristics even when polarization is generated and kept in a heated state. .

Ferroelectric materials used in FeRAM that require such characteristics include lead zirconate titanate (Pb (Zr-Ti) O) and lanthanum-containing lead zirconate titanate ((Pb-La) ( Zr—Ti) O) and the like are known. However, in these dielectric thin films, when a platinum (Pt) conductive multilayer film is used as an electrode, reliability is deteriorated due to polarization fatigue that lowers remanent polarization when a repetitive pulse of 10 ⁶ times or more is applied. There was a problem. Since this polarization fatigue has been found to occur depending on the conductive thin film (electrode) material, as will be described later, in order to improve this, materials that do not easily cause polarization fatigue have been studied. Examples of materials that are less prone to polarization fatigue include Ir—O, Ru—O, Sr—Ru—O, (La—Sr) Co—O made of iridium (Ir) and ruthenium (Ru), and their conductivity. FeRAM using an oxide has been studied. However, these conductive oxides have a larger leakage current than Pt, and even in these materials, they result in problems caused by controllability of interface characteristics (deterioration of reliability, etc.) and are extremely serious in practical use. There was a serious problem.

  In this way, when electronic circuit elements are considered in mind, it is necessary to highly control the interface characteristics between the dielectric and the conductive thin film that have a decisive influence on the circuit characteristics in order to improve the element characteristics and ensure stability. In spite of being indispensable, a dielectric that can simultaneously satisfy both a dielectric constant and a Q value that exhibit opposite correlations is not easy to form a film. It is a difficult situation. Accordingly, it has been difficult to realize a stable and high-performance memory / capacitance element using a dielectric thin film having good interface characteristics.

  As for the above, if the focus is placed on the conductor (electrode) on the other side of the interface, it will not be reworked, and the interface characteristics will be good and stable high-performance electrical characteristics will be realized. In other words, it can be said that it has been extremely difficult to realize the conductor. Accordingly, the interface is considered as a constituent element of the conductive thin film, and hereinafter, the interface including the interface is defined as a conductor, and the interface characteristics are discussed in more detail below. In addition, when a conductive multilayer film in which a conductor is made into a multilayer film is used as an electrode, the layer (phase) interface between each conductor (layer) film constituting the multilayer film has the same influence (action / effect) as the above-described interface. ). Therefore, hereinafter, the layer (phase) interface between each conductor (layer) film constituting the conductive multilayer film is also included in the above-described interface.

  As interface property control methods, called buffer layer (phase) or barrier layer (phase) in the vicinity of the interface, improved lattice matching, diffusion controllability, electron tunneling controllability (potential-barrier-height-energy controllability), etc. For this purpose, a technique for forming a multilayer (film) has been studied. However, since these methods newly form a layer (phase) interface that is steep in terms of electrical characteristics, chemical bonding, or atomic arrangement, it cannot be an essential solution. . For example, as a single conductor (layer) film constituting a conductive multilayer film, a layer (phase) having a high dielectric constant or a low electrical conductivity but having a high buffer (buffering) effect and a barrier (shielding) effect is used. When it is inserted at the interface between the dielectric and a conductor (layer) film having a high electrical conductivity, a new interface is formed between the inserted conductor film. As a result, the inductance component increases in terms of electrical characteristics, and the electric neutrality is lost in the vicinity of the inserted layer (phase) due to the electrical neutralization due to the dielectric polarization mainly consisting of space charge polarization. As a result, the capacitance of the entire device is greatly reduced as compared with the capacitance expected for a dielectric film having a high dielectric constant, and the carrier (charge) mobility is also lowered.

  Here, in order to clarify the conventional situation regarding the interface characteristics (controllability thereof), the current situation and problems when the dielectric and the conductive multilayer film are individually viewed from the material viewpoint will be outlined below.

First, the dielectric will be described. As described above, it is not easy to form a dielectric that can simultaneously satisfy the dielectric constant and the Q value exhibiting opposite correlations. In particular, in a ferroelectric, spontaneous polarization (Ps) occurs below the Curie point corresponding to the structural phase transition temperature, and the dielectric constant tends to diverge near the Curie point (about 120 ° C. for BaTiO ₃ ). Spontaneous polarization is caused by dipole interaction, and it is considered necessary to ensure crystallinity of an appropriate (several tens) crystal lattice. Macroscopic dielectric polarization as a whole dielectric material is manifested by a set of ferroelectric domains (domain: the dipoles are aligned in the same direction and may be clusters). The size and number of domains is determined by a trade-off between electrostatic energy and the energy required to form and maintain domain (interface) walls.

In addition, in a ferroelectric, a complex perovskite structure such as Ba (Mg _1/3 Ta _2/3 ) O ₃ , Pb (Mg _1/3 Nb _2/3 ) O ₃ and Pb (Zn) The aspect of dielectric polarization differs significantly depending on the oxide crystal structure and the like, such as a complex perovskite structure of disordered ion arrangement such as _1/3 Nb _2/3 ) O ₃ . In particular, the dielectric of the latter structure has a so-called “Skanavi” type dielectric relaxation mechanism in which a low symmetric strain of a perovskite cell (cell) generates a plurality of shallow potential minimum points in each cell, and a ferroelectric phase. It exhibits a relaxed dielectric property combined with a transition mechanism, and the phase transition becomes very slow. The dielectric constants of these ferroelectrics are strong in frequency dependence, but the dielectric constant itself is large and the temperature dependence is small. In addition, since the fine domains are polarized relatively easily by applying an electric field, the ferroelectrics tend to have a large electric field induced strain.

In addition, many of the ferroelectrics are composed of diamagnetic ions, while many of the oxide magnetics have a nonpolar crystal symmetry, making it difficult for the appearance of ferroelectricity. Although it is difficult to coexist, some of the [disordered (disordered) ion arrangement type] perovskite oxides containing Pb ²⁺ or Bi ³⁺ have coexistence of both characteristics.

As described above, the dielectric exhibits various characteristics depending on the state and is very complicated. Currently, dielectrics having a high dielectric constant include Si ₃ N ₄ , Al ₂ O ₃ , Hfo ₂ —SiO ₂ , Sc ₂ O ₃ , ZrO ₂ —SiO ₂ , Y ₂ O ₃ , Gd ₂ O ₃ , 2La _2. O ₃ -3SiO ₂ , Gd ₂ O ₃ —SiO ₂ , La ₂ O ₃ , Ta ₂ O ₅ , ZrO ₂ , LaAlO ₃ , ZrTiO ₄ , HfO ₂ , SrZrO ₃ , Hf _0.2 Sn _0.05 Ti _0.75 O ₂ , Zr _{0.2 sn 0.2 Ti 0.6 O 2, TiO} 2, SrBi 2 Ta 2 O 9, SrTiO 3, (Ba x Sr 1-x) TiO 3, Pb (Zr y Ti 1-y) O 3, SrBi (TaNb), Bi 2 SiO ₅ , Bi ₄ Ti ₃ O ₁₂ , (BiLa) Ti ₃ O ₁₂ , (BiLa) (TiV) O and the like are known. However, these materials contain the structural and material characteristics as described above.

  In addition, these materials have very complex properties such as forming non-stoichiometric compounds that deviate from stoichiometric composition, including various defects or taking the form of mixed crystals. ing. In addition, in order to constitute an electronic circuit element, the formation of a dielectric (thin film) having a required performance with high reproducibility and reliability on a conductive multilayer film as a base substrate called a so-called lower electrode itself. Since a very advanced technique is required, the development of a practical formation technique is also a big issue.

  On the other hand, it is essential for the conductive multilayer film to have high conductivity, high melting point, excellent oxidation resistance, and good flatness. In other words, as described above, when considering a high oxide / ferroelectric thin film that is promising as a dielectric, formation of the dielectric thin film and a high temperature in an atmosphere containing oxygen after the formation (for example, about 600 It can withstand heat treatment (up to 800 ° C) and can suppress (barrier) oxygen diffusion from the dielectric. Moreover, it has good adhesion to the dielectric and provides a good adjacent interface without irregularities (hillocks). It must have the characteristics that can be done.

  Conventionally used conductive multilayer film materials for memory elements include Pt and other noble metals that are expected to have chemical reaction resistance in a high-temperature oxidizing atmosphere. However, Pt, for example, has a large diffusion coefficient of oxygen under high-temperature heat treatment, which not only causes a change in the composition of the dielectric, but also oxidizes adjacent layers, resulting in film peeling due to reduced adhesion and the development of thermal stress. There are problems such as causing hillock formation. In addition, when considering a stack cell structure in which a semiconductor transistor and a ferroelectric memory capacitor are connected by a plug such as polysilicon for high integration of a memory element, the plug polysilicon or the like is caused by oxygen diffusion described above. Since it is oxidized, there is a serious problem that the conductivity of the element circuit is reduced as a result of the above-described peeling or the like, and the electrical connection cannot be maintained in some cases.

As an attempt to improve such problems as diffusion, adhesion, and decrease in conductivity related to the use of such a noble metal, a conductive multilayer film structure in which Ti, TiO ₂ , and TiN layers (phases) are arranged adjacent to the noble metal. Has been proposed. By adopting these configurations, for example, the stress expressed in the Pt film is reduced by the Ti layer on the Pt film, and hillock formation is suppressed. However, suppression of oxygen diffusion by the Ti layer is generally effective only at a heat treatment temperature of about 600 ° C. or less, and cannot withstand the high temperature heat treatment at about 600 ° C. or more as described above. In a high temperature treatment exceeding 600 ° C., in some cases, the Ti or TiN layer is oxidized by the oxygen diffusion described above, causing new film peeling and hillock formation, which is a very serious problem.

  Instead of such noble metals, Ir, Ru, Zr, Nb, Hf, Ta, which have chemical stability at high temperatures, and these, and Mg, Al, Si, Co, Ni, Cu, Sr, Y, Compounds of Ba, La, and Pb and their oxides and nitrides, such as Ir—O, Ru—O, Ir—Al—O, Ir—Ti—O, Ir—Zr—O, Ir—Nb—O Ir-Hf-O, Ir-Ta-O, AlN, Ti-Al, ZrN, NbN, HfN, TaN, Sr-Ru-O, (La-Sr) Co-O, La-Ni-O, Pb ( Conductive oxide / nitrides such as Mg—Nb) Ti—O, Pb (Zr—Ti) O, HfSiN, TaSiN, Y—Ba—Cu—O have been applied.

  For example, Ir and Ru are more resistant to oxygen diffusion than Pt, and Ir—O and Ru—O maintain conductivity even when oxidized. At the same time, these have the property of replenishing oxygen to oxygen defects that appear near the conductive multilayer film (electrode) by polarization reversal, etc., and therefore have the effect of reducing the accumulation of defects and suppressing fatigue. is doing. In addition, these materials are considered to be promising conductive multilayer film materials because of their excellent diffusion barrier properties against Pb and the like, which are often contained in ferroelectric materials. Thus, although the conductive oxide has the potential to prevent oxygen deficiency of the ferroelectric material and improve the fatigue characteristics of the ferroelectric film, as described above, when compared with Pt, There is a problem that the leakage current is large due to defects caused by the steep interface state and relatively small potential barrier height energy.

  In addition, since the above-described materials are difficult to etch, if a thin film is formed so that it can be etched simultaneously with other layers for the convenience of patterning in the device manufacturing process, the leakage current further increases as a result. There was a problem that would end up. In order to suppress this leakage current, a configuration in which a layer of Ti or the like is used as a barrier is also conceivable. However, Ir, Ru, Ti, and the like may react with a high-temperature heat treatment as described above. There is a big problem that the biggest problem in realizing a high-performance memory / capacitance element is that it results in the problem of improving the interface characteristics described above.

  As described above, in order to put into practical use high-performance memories and capacitive elements using dielectrics, especially high-permittivity dielectrics (high-ferroelectrics), the controllability of the interface characteristics of the conductive multilayer film However, the most important issue at present is to improve the controllability of the interface properties of the former conductive multilayer film. Considering device development using a high-dielectric material, unless the improvement in controllability of the interface characteristics is solved, it is impossible to extract the performance of the dielectric effectively and make the maximum use. In particular, it is obvious that the improvement of the controllability of the interface characteristics becomes more and more important as the dielectric and the conductive multilayer film become thinner, the switching operation speeds up and the operating frequency becomes higher.

  However, as described above, there is no example in which the controllability of the interface characteristics is sufficiently realized in the conventional technology, and the adverse effect due to the formation of a layer (phase) interface that is steep in electrical characteristics, chemical bonding, or atomic arrangement structure. Therefore, it has been extremely difficult to put into practical use a memory / capacitance element having stable high characteristics. In other words, due to the influence caused by the steeply changing interface, the overall energy loss and characteristic degradation (aging) including dielectric loss and leakage current of the element are very large, and higher speed and higher frequency are promoted. As the process progresses, this effect becomes more conspicuous. Therefore, it has been very difficult to realize a device such as a high-performance memory / capacitance element that can achieve the required electronic circuit characteristics with low energy and little characteristic deterioration.

JP 54-148263 A JP 56-156688 A JP 58-015208 A JP 61-256702 A JP-A-63-194309 JP-A 64-001206 JP-A-1-273305

  As described above, in the prior art, the dielectric and the end of the conductive multilayer film constituting the memory and the capacitive element, more specifically, the interface between the conductive thin film (electrode) and the dielectric, Or due to or related to the formation of a sharp interface (phase) in terms of electrical characteristics, chemical bonding, or atomic arrangement at the interface with the buffer layer (phase) or barrier layer (phase) contained in the conductive thin film Insufficient lattice matching, diffusion controllability, electron tunneling controllability, etc., interface state, fixed charge, defects such as defects in constituent elements, etc. As a result, overall energy loss including leakage current and the like, and characteristic deterioration (aging) are increased.

  In some cases, electric charge is generated in the vicinity of a sharply changing interface due to the loss of electrical neutrality due to dielectric polarization mainly composed of space charge polarization, and as a result, the overall capacitance (capacitance). However, since the intrinsic (intrinsic) dielectric constant inherent in the dielectric is lower than the expected capacitance, it also causes adverse effects such as lowering carrier (charge) mobility, resulting in a stable high-performance element. The practical application was extremely difficult.

  In this way, high-performance memory based on a combination of dielectric and conductive multilayer film, which is used in electronic circuits in electronic devices, especially in ultra-compact high-speed memory circuits and integrated circuits that operate in high-frequency regions, etc. In the conventional conductive multilayer film in a capacitor element or the like, only insufficient characteristics are obtained and it is difficult to put it to practical use. For this reason, in the prior art, it has been extremely difficult to realize a device such as a small and high performance memory / capacitance element having a small and stable energy loss and characteristic deterioration and a required stable performance.

  The present invention has been made to solve the above problems, and is used in an electronic circuit in an electronic device, in particular, an ultra-compact high-speed memory circuit or an integrated circuit operating in a high-frequency region. An object of the present invention is to provide a conductive multilayer film capable of improving the performance of a high-performance memory / capacitor element or the like having a combination of a dielectric and a conductive multilayer film as a basic configuration.

  The conductive multilayer film according to the present invention is a conductive multilayer film composed of a first conductive phase having conductivity and a second conductive phase having conductivity arranged in contact with the first conductive phase. The first conductor phase has a gradient function in which at least one of a charge distribution state, a chemical bond state, and an atomic arrangement structure state is changed in the thickness direction of the first conductor phase. The region is provided on the second conductor phase side. The gradient functional region may be any region as long as the value of the atom-pair correlation distance changes in the thickness direction of the first conductor phase. Further, the gradient functional region may be any region as long as the barrier energy value against the movement of the charge is changed in the thickness direction of the first conductor phase. Further, the functionally graded region only needs to have a density where the level that becomes a metastable site of charge changes in the thickness direction of the first conductor phase. In addition, the gradient functional region only needs to have an amount that is an indicator of a chemical bonding state including chemical shift and electronegativity changing in the thickness direction of the first conductor phase. In addition, the functionally gradient region may be any region in which the atomic arrangement distribution changes in the thickness direction of the first conductor phase.

  With the structure of the conductive multilayer film for an electronic circuit as described in claim 1 and claims 8 to 12 described above, the required conductor phase or the aggregate region of the conductor phase of the conductive multilayer film can be electrically connected. Characteristic, chemical bonding, or atomic arrangement structure is not steep, and can be a region (gradient function region) that has a so-called gradient function (gradient function) that changes gradually and continuously. become. This makes it possible to reduce the influence of the lattice matching distortion that becomes more prominent near the interface between different phases having a steep phase interface, the occurrence of defects such as interface states, fixed charges, etc. By having a characteristic state, the total energy loss including dielectric loss and leakage current, etc., which are manifested by thinning the dielectric and conductive multilayer film, and increasing the switching operation speed and the use frequency, and , While reducing characteristics deterioration (aging) as much as possible (low energy and high reliability), functions such as the gradient functional area, such as improvement of diffusion controllability and functions such as reduction of space charge polarization By superimposing the effects, there is an effect that it is possible to realize a high-performance element such as a memory / capacitance element having dramatically improved dielectric characteristics, reliability, and the like.

  In the conductive multilayer film according to the present invention, the functionally gradient region may be arranged in an atomic arrangement chemically continuous with a part of the second conductor phase. Thus, by having the structure of the conductive multilayer film for an electronic circuit as described in claim 2, in addition to the functions and effects shown by the conductive multilayer film of claim 1, the gradient functional region has The electrical (conductive) bond between the two conductor layers (phases) is more firmly maintained by the atomic arrangement that is continuous in chemical bonds with at least a part of the adjacent conductor phases. Therefore, specific stabilization of electricity (conductivity) is promoted, and as a result, there is an effect that contributes to further improvement of the electrical (conductivity) characteristics of the entire conductive multilayer film.

  In the conductive multilayer film according to the present invention, the functionally graded region may be a state in which the movement of the substance passing through this region is reduced. In the conductive multilayer film, the functionally graded region may be composed of sites having dimensions smaller than the spatial region of the moving site required for the movement of the substance. In addition, the functionally gradient region may be configured from a moving site space having an electric field state that applies an electric repulsive force to a substance.

  Thus, by setting it as the structure of the electrically conductive multilayer film for electronic circuits as described in Claims 3-5, the effect of reducing the movement of the substance which consists of an atom, an electron, an ion, a molecule | numerator, etc. in a functional gradient area | region, Improvement of diffusion controllability due to the so-called barrier (shielding) effect described above is realized, and the time-dependent change and deterioration of the dielectric characteristics due to them are effectively reduced, so that the element characteristics can be drastically improved. There is. As a matter of course, the function / function shown in the conductive multilayer film according to claim 2 is achieved by aligning at least a part of the adjacent conductor phase with the atomic arrangement position chemically continuous with at least a part of the adjacent functional layer. There is also an effect that can achieve a synergistic effect with the effect. As a result of integrating these, there is an effect that it is possible to realize a high-functional device such as a memory / capacitance element that can achieve the required stable and highly reliable dielectric characteristics.

  Further, in the conductive multilayer film according to the present invention, the functionally gradient region has a function of reducing the expression of positive and negative charges due to a state including dielectric polarization in the vicinity of the interface with the second conductor phase, and the positive and negative charges do not appear. A function of controlling one of the electrical neutral states may be provided. The function of reducing the expression of positive and negative charges due to a state including dielectric polarization has a local charge transfer path consisting of an energy state in which the barrier energy value of the charge is smaller than the energy value where the dielectric polarization is expressed. What is necessary is just to be comprised from the structure.

  As described above, by adopting the structure of the conductive multilayer film as described in claims 6 and 7, in addition to the functions and effects shown by the conductive multilayer film according to claims 1 to 5, space charge polarization is mainly used. As a result, the electrical neutrality is lost due to the dielectric polarization or the like, and the occurrence of electric charges is reduced as much as possible. As a result, the capacitance (C) of the entire element is inherent (intrinsic) inherent to the dielectric. The dielectric constant (ε) can be very approximated to the expected capacitance, and the decrease in carrier (charge) mobility can be reduced. Further improvements in dielectric characteristics during high-speed switching and high-frequency operation are achieved. However, there is an effect that a highly functional device such as a memory / capacitance element having low energy and high reliability can be realized.

  In the conductive multilayer film according to the present invention, the first conductor phase and the second conductor phase only need to be made of an oxide conductor having a perovskite crystal structure. In this way, by forming the structure of the conductive multilayer film as described in claim 13, in addition to the functions and effects shown by the conductive multilayer film according to claims 1 to 12, the perovskite crystal structure oxide conductor Since the lattice matching with a dielectric having a similar perovskite crystal structure is good, the interface property controllability can be further improved. Of course, the perovskite-type crystal structure includes not only a simple perovskite structure but also a defect / layered / multiple perovskite structure, a composite perovskite structure, and a solid solution. In particular, when the conductive multilayer film of the present invention is used as a dielectric base substrate as a lower electrode, it is effective in improving the crystallinity of the dielectric and the film formation controllability. As a result of integrating these, there is an effect that a highly functional device such as a stubby / capacitance element can be realized with low energy and high reliability.

  In the conductive multilayer film according to the present invention, the first conductor phase and the second conductor phase are Pt, Ir, Ru, Zr, Nb, Hf, Ta, Mg, Al, Si, Co, Ni, Cu, What is necessary is just to be comprised from the oxide type conductor containing Sr, Y, Ba, La, Pb and at least one of a lanthanum type and an actinium type.

  Furthermore, by having the structure of the conductive multilayer film as described in claim 14, in addition to the action / effect shown in the conductive multilayer film according to claims 1 to 13, the inclusion of the above elements allows high temperature stability. It is empirically known that a conductor with high carrier density that contributes to conductivity can be formed, and a highly reliable device such as a memory / capacitance element having low energy and high reliability has been developed. There is an effect that can be realized. In particular, these lanthanum and actinium elements contribute more effectively to changes in the state of carriers and electric fields due to the large number of constituent electrons, and consequently control the electrical characteristics of the conductive multilayer film. Therefore, it is possible to realize a high-performance device such as a memory / capacitance element having low energy and high reliability.

  In the present invention, the configuration of the conductive multilayer film according to any one of claims 1 to 14 can realize improvement in controllability of the interface characteristics that strongly influence the dielectric characteristics of the dielectric in the functionally graded region. As a result, there is an effect that it is possible to realize a high-functional device such as a memory / capacitance element having low energy and high reliability while further improving various characteristics such as a dielectric constant.

  As described above, according to the present invention, at least one of the carrier distribution state, the chemical bonding state, and the atomic arrangement structure state is changed in the thickness direction of the first conductor phase. Since it has a functionally graded area, it is possible to improve the performance of elements such as high-performance memories and capacitors that have a basic configuration of a combination of dielectric and conductive multilayer film. It is done.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a configuration example of a conductive multilayer film according to an embodiment of the present invention. Here, a basic element structure using the conductive multilayer film 100 including the second conductor thin film 102 and the first conductor thin film 103 is shown as an example. The element shown in FIG. 1 is formed on the electrode 101 as a voltage application / charge transfer means, the second conductive thin film 102 and the first conductive thin film 103 formed thereon, and the first conductive thin film 103. The dielectric phase 104 is provided. In the element shown in FIG. 1, the first conductor thin film 103 is disposed on the first gradient functional region 131 disposed on the electrode 101 (second conductor thin film 102) side and on the dielectric phase 104 side. And the first conductor phase 132. The electrode 101 is, for example, a conductor wiring used for a normal electronic circuit element, and a power signal or the like is supplied to the conductor wiring.

  By the way, the first conductor phase 132 is composed of a single crystal, amorphous material, or extremely fine fine particle polycrystal of a conductive material (substance), and is a phase constituting the first conductor thin film 103. From the point of view, it is in a state that can be regarded as a pseudo-single phase. Therefore, in a broad sense, the first conductor phase 132 coincides with the first conductor thin film 103 and includes the first functional gradient region 131. For convenience of explanation, the first conductor phase 132 is included in the first conductor phase 132. As a phase other than the first functional gradient area 131, the following description will be given in a narrow sense. Similarly, the second conductive thin film 102 is a phase composed of a single crystal, an amorphous material, or an extremely fine fine particle polycrystal of a conductive material (substance). It is called a thin film.

  First, the conductive multilayer film 100 (second conductor thin film 102) is in contact with the electrode 101 as a voltage application / charge transfer means for applying an electric field to the conductor thin film 100 to supply / charge / discharge carriers (charges). Is formed. Further, the conductive multilayer film 100 (first conductor phase 132) is formed adjacent to the dielectric phase 104 made of a dielectric material. In addition, the first gradient functional region 131 constituting the first conductive thin film 103 is chemically bonded from the electrode 101 side to the dielectric phase 104 side (in the thickness direction of the first conductive thin film 103). At least one of the normal state, the atomic arrangement structural state, and the electrical specific (carrier distribution) state gradually changes, improving the lattice matching by the buffering action and the barrier (shielding) action It has a tilt function that improves the diffusion controllability.

  In the first functionally graded region 131, for example, the chemical bonding state including the lattice constant and the composition gradually changes from the second conductive thin film 102 side to the dielectric phase 104 side. For example, the first functional gradient region 131 is composed of a plurality of atomic layers having different compositions. In this case, the composition of the stacked atomic layers (phases) changes in the stacking direction. In this case, the first functional gradient region 131 is not completely separated into a plurality of phases, but for convenience of explanation, is a plurality of phases, and is actually limited to a single layer or a single layer. The tilt function may be expressed in a state close to zero.

  In the conductive multilayer film 100 shown in FIG. 1 configured as described above, the second conductor thin film 102 and the first conductor thin film 103 are phases that are produced with the aim of having the same composition and the same phase. In the second conductor thin film 102, a microscopic change occurs in the interatomic distance and composition due to strain and diffusion caused by contact with the electrode 101. On the other hand, in the second conductive thin film, the dielectric phase 104 for forming the capacitor is brought into contact with or infinitely close thereto, so that the same microscopic change as described above appears. Therefore, strictly speaking, the second conductor thin film 102 and the first conductor thin film 103 are in a state where microscopic different phases are adjacent to each other.

  In this state, in the conductive multilayer film 100 shown in FIG. 1, the first gradient functional region 131 is provided, and the steep functional state change is mitigated in the vicinity of the boundary of the first gradient functional region 131. The adverse effect at the interface between the second conductor thin film 102 and the first conductor thin film 103 is reduced, and the performance can be improved by forming a multilayer film. In addition to the inclination with respect to the first conductor phase 132, the first gradient functional region 131 is inclined with respect to the second conductor thin film 102 so that the above-described gradient function is more effectively realized. Yes. In addition, the effect mentioned above is made | formed by the simple capacitor produced as a structure shown in FIG.

  According to the conductive multilayer film 100 shown in FIG. 1, as described above, since the steep function / state change in the vicinity is alleviated by the first gradient functional region 131, there is a difference between the different phases having steep phase interfaces. It becomes possible to reduce the influence of the occurrence of defects such as lattice matching distortion, interface states, and fixed charges that become more prominent near the interface. In addition, the dielectric phase 104 and the conductive multilayer film 100 can be thinned by setting the first functional gradient region 131 to a state having the required characteristics.

  In addition, while reducing the overall energy loss including dielectric loss and leakage current that occur due to high-speed switching operation and high frequency of use, and characteristic degradation (aging) (low energy and high reliability) For example, it is possible to superimpose the functional effects such as improvement of characteristics of the first gradient functional region 131 such as diffusion controllability and electron tunneling controllability, and further reduction of space charge polarization. As a result, by using the conductive multilayer film 100 shown in FIG. 1, it is possible to realize a memory / capacitance element having dramatically improved dielectric characteristics, reliability, and the like.

  Next, the conductive multilayer film in the embodiment of the present invention will be described in more detail. Below, the case where the conductive multilayer film 100 is comprised from the fine particle polycrystal of the perovskite type crystal structure oxide conductor is demonstrated. Here, the distance of the atom pair constituting the first functional gradient 131 (the atom pair correlation distance) is closer to the second conductor thin film 102, and the atom pair correlation distance of the atom pair constituting the second conductor thin film 102 is closer to the second conductor thin film 102. It was made to change so that it might approximate or correspond to the value of. In addition, the first gradient functional region 131 is provided with a gradient function in which the diffusion coefficient (D) of oxygen or hydroxide ions decreases toward the second conductor thin film 102 side. In addition, the 1st gradient functional area | region 131 comprised with a polycrystal will be comprised from the aggregate | assembly of a some gradient functional area conductor phase.

For example, the second conductive thin film 102 and the first conductive thin film 103 are conductive fine particles (particle size) made of (La—Sr) Co—O (La _0.5 Sr _0.5 CoO ₃ composition) which is a perovskite crystal structure oxide. 0.1 μm or less). Even when the particle size was about 5 nm, the influence of the size effect could not be recognized. For example, a thin film made of conductive fine particles can be formed by the following sol-gel method. First, a precursor solution made of a liquid colloid generated by a polycondensation reaction is prepared from a metal organic compound, an organic metal compound, or a metal salt containing a conductor raw material constituting the conductor fine particles. For example, a mixed metal alkoxide having La—Sr, Co as the main element is prepared. Next, the prepared precursor solution is concentrated and formed into a thin film, and the thin film obtained by the gelation is heated (fired). By these things, the 2nd conductor thin film 102 and the 1st conductor thin film 103 which consist of conductor fine particles (polycrystal) can be formed.

  Moreover, the 1st functional gradient 131 contained in the 1st conductor thin film 103 can be formed as follows. For example, the region to be the first gradient functional region 131 of the first conductor thin film 103 is irradiated and supplied with active particles made of ions or radicals of oxygen, titanium, ruthenium, lanthanum, iridium, or a combination thereof, and the irradiation altitude region. The dangling bond concentration and the (oxygen excess) compound composition concentration in the fine particles (phase) may be changed in a gradient manner. The first functionally graded region 131 manufactured in this way has a composition / structural state in which the abundance ratio of a compound composed of oxygen, titanium, ruthenium, and iridium, or a combination thereof changes in the film thickness direction. The chemical bond state regarding these is inclined.

Hereinafter, exemplifying a case where the dielectric phase 104 having the Pb _0.9 La _0.1 Zr _0.2 Ti _0.8 O ₃ composition is formed, first, the atom-pair correlation distance of the first gradient functional region 131 is first from the dielectric phase 104 side. From the average value in the case of the stoichiometric composition of the dielectric phase 104 and the first conductor thin film 103 toward the two conductor thin film 102 side, so as to approximate or coincide with the atom-pair correlation distance of the second conductor thin film 102. Has changed. In the case of this example, the average value of the atom-pair correlation distance in the case of the stoichiometric composition of the dielectric phase 104 and the first conductor thin film 103 is about 0.3928 to 0.3983 nm, and the second conductor thin film The 102 atom-pair correlation distance is about 0.382 nm. In addition, the approximate value of the lattice constant in the biaxial direction selected in the short distance order of the unit cell (unit cell) was defined as the above-described atom-pair correlation distance.

In addition, the concentration of oxygen or hydroxide ions in the first functional gradient region 131 changes from the dielectric phase 104 side to the second conductor thin film 102 side so as to be higher.
By these things, in the 1st gradient functional area | region 131, it will be in the state from which the distance between each phase and a diffusion prevention capability change gradually. Thus, the first gradient functional region 131 is not only inclined with respect to the second conductor thin film 102, but also the effect of the gradient function described above is more effective in consideration of the first conductor thin film 103. So that it can be realized. Note that the diffusion stopping ability represents the diffusion controllability corresponding to the size of the diffusion coefficient that is one index of the effect of the buffer / barrier action in the region, and in this example, mainly corresponds to the diffusion controllability of oxygen. To do.

  Since the second conductive thin film 102 and the first conductive thin film 103 formed as described above are polycrystalline, first, a heterogeneous interface state is easily formed due to the influence of the crystal grain size and grain boundary. ing. Further, in the second conductive thin film 102, the interatomic distance and composition are microscopically changed from the original state due to distortion and diffusion caused by contact with the electrode 101. Similarly, the first conductor thin film 103 (first conductor phase 132) is microscopically changed from its original state due to the presence of the dielectric phase 104. For these reasons, the second conductor thin film 102 and the first conductor thin film 103 are strictly in a state where microscopic different phases are adjacent to each other. In contrast to this state, the first gradient functional region 131 having the above-described configuration is provided between the layers, so that adverse effects due to phase contact are reduced, and performance can be improved by forming a multilayer film. As a memory / capacitance element for characteristic evaluation, a simple capacitor having the configuration shown in FIG. 1 is manufactured, and the effects described above have been confirmed.

  According to the conductive multilayer film 100 described above, first, since a steep function / state change in the vicinity of the boundary of the first gradient functional region 131 is relieved, it becomes more prominent in the vicinity of the interface between different phases having a steep phase interface. It is possible to reduce the influence of lattice matching distortion, generation of defects such as interface states and fixed charges. In addition, the first functionally graded region 131 is in a state having required characteristics such as a reduction in diffusion coefficient due to effects such as reduction of dangling bonds and formation of (oxygen-excess) compound, so that the dielectric phase 104 or The conductive multilayer film 100 can be thinned.

  In addition, it is possible to reduce the overall energy loss including dielectric loss and leakage current that occur due to high-speed switching operation and high use frequency, and reduction of characteristic deterioration (aging) (low energy and high reliability). Further, as the characteristics of the first gradient functional region 131, for example, it is possible to superimpose functional effects such as improvement of diffusion controllability and electron tunneling controllability, and further reduction of space charge polarization and improvement of diffusion controllability. Thus, it becomes possible to realize a memory / capacitance element with dramatically improved dielectric characteristics and reliability. In addition, the effect was recognized in the 1st gradient functional area | region 131 even with the ultra-thin film thickness of about 2-50 nm.

  Next, another conductive multilayer film in the embodiment of the present invention will be described. FIG. 2 is a configuration diagram showing a configuration example of another conductive multilayer film 200 in the embodiment of the present invention. In FIG. 2, a basic element structure using the conductive multilayer film 200 including the second conductor thin film 202 and the first conductor thin film 103 is shown as an example. The element shown in FIG. 2 includes a second conductor phase 221 disposed on the electrode 101 side, and a second functional gradient area 222 disposed on the dielectric phase 104 (first conductor thin film 103) side. The second conductor thin film 202 is configured. The same reference numerals as those in FIG. 1 are the same.

  By the way, the second conductor phase 221 is composed of a single crystal, amorphous, or extremely fine fine particle polycrystal of a conductive material (substance), and is a phase constituting the second conductor thin film 202. From the point of view, it is in a state that can be regarded as a pseudo-single phase. Accordingly, in a broad sense, the second conductor phase 221 coincides with the second conductor thin film 202 and includes the second gradient functional region 222. However, for convenience of explanation, the second conductor phase 221 is included in the second conductor phase 221. As a phase other than the second functional gradient area 222, the following explanation will be given from a narrow sense.

  The second functionally graded region 222 extends from the electrode 101 side to the dielectric phase 104 side (in the thickness direction of the second conductor thin film 202), in a chemically bonded state, an atomic arrangement structural state, and electrical identification. At least one of the target (carrier distribution) states gradually changes, and it has a tilt function that improves the lattice matching by the buffering action and the diffusion controllability by the barrier action. is doing.

  In the second functionally gradient region 222, for example, the chemical bonding state including the lattice constant and the composition gradually changes from the electrode 101 side to the dielectric phase 104 side. For example, the second functional gradient area 222 is composed of a plurality of atomic layers having different compositions. In this case, the composition of the stacked atomic layers (phases) changes in the stacking direction. In this case, the second functional gradient area 222 is not completely separated into a plurality of phases, but is made into a plurality of phases for convenience of explanation, and is actually limited to a single layer or a single layer. The tilt function may be expressed in a state close to zero. In addition, the part which the 2nd gradient functional area | region 222 and the 1st gradient functional area | region 131 correspond was comprised so that the mutual gradient function might not be impaired.

  According to the conductive multilayer film 200 shown in FIG. 2 configured as described above, since the second gradient functional area 222 and the first gradient functional area 131 are provided, compared to the conductive multilayer film 100 shown in FIG. It is possible to increase the gradient function that can be imparted. Further, it is possible to easily realize a configuration in which atoms are arranged in chemical bonds continuously from the second gradient functional region 222 to the first gradient functional region 131. As a result, it is possible not only to realize more various actions and effects, but also to form the second conductor thin film because a part of the adjacent gradient functional regions has an atomic arrangement that is chemically continuous. The electrical (conductive) coupling between 202 and the first conductive thin film 103 is more firmly maintained. As a result, according to the conductive multilayer film 200 shown in FIG. 2, the stabilization of the electrical (conductive) characteristics is promoted, and as a result, the effect of contributing to further improvement of the electrical (conductive) characteristics of the conductor layer film as a whole. I was able to confirm that there is.

When the main electrical characteristics obtained with the simple capacitor having the configuration shown in FIG. 2 are exemplified, the resistivity of the conductive multilayer film 200 is about 90 μΩcm or less. In addition, as the dielectric characteristics of the conductive multilayer film 200, hysteresis characteristics excellent in squareness ratio such as a coercive electric field of about 40 kV / cm or less and a remanent polarization value of about 35 μC / cm ² or more can be obtained. Also, 10 and ¹² times more than the fatigue characteristic polarization even by applying a repetitive pulse does not deteriorate, and low leakage current characteristics, does not deviate hysteresis characteristics held in the polarization generated and Atsushi Nobori superior imprint characteristics Can be confirmed.

The first conductor thin film 103 and the second conductor thin film 202 are made of SrRuO ₃ , the dielectric phase 104 is made of Pb (Zr _0.52 Ti _0.48 ) O ₃ , and the second gradient functional region 222 and the first Even when the gradient functional region 131 is in a state where the average lattice constant is changed from about 0.3983 to 0.4038 nm to about 0.393 nm, the same effect and performance can be obtained.

Further, since the dielectric phase 104 is made of (Ba _x Sr _1-x ) TiO ₃ , the dielectric constant (ε) and the Q value can be obtained even in a high-speed switching / high-frequency region of several hundred MHz or more. Therefore, it is possible to easily realize a high-speed switching / high-frequency memory / capacitance element that can satisfy both of these requirements and permit dielectric loss. (Ba _x Sr _1-x ) TiO ₃ is a material having an extremely large dielectric constant and a low dielectric constant even under high-speed switching and high frequency. By making a Ba-rich solid solution with x of about 0.5 or more, Although the quality factor (Q) value is several hundred or less, the relative dielectric constant (ε ′) can be several hundred to several tens of thousands or more even in the high-speed switching / high-frequency region. Further, by using a Sr-rich solid solution with x of about 0.5 or less, although the relative dielectric constant is several tens to several hundreds, the Q value can be several thousand or more.

  Next, another conductive multilayer film in the embodiment of the present invention will be described. FIG. 3 is a configuration diagram showing a configuration example of another conductive multilayer film 300 in the embodiment of the present invention. In FIG. 3, a basic structure using a conductive multilayer film 300 including a first conductor thin film 302, a second conductor thin film 303, a third conductor thin film 304, a fourth conductor thin film 305, and a fifth conductor thin film 306 is used. An element structure is shown as an example. In FIG. 3, the dielectric phase is omitted.

  The element shown in FIG. 3 has a functional gradient region similar to the second functional gradient region 222 shown in FIG. 2 in each conductor thin film. First, the first conductor thin film 302 is composed of a first conductor phase 321 on the electrode 101 side and a first gradient functional region 322 on the fifth conductor thin film 306 side. The second conductor thin film 303 is composed of the second conductor phase 331 on the electrode 101 side and the second gradient functional region 332 on the fifth conductor thin film 306 side. Further, the third conductor thin film 304 is composed of the third conductor phase 341 on the electrode 101 side and the third functional gradient region 342 on the fifth conductor thin film 306 side. Further, the fourth conductor thin film 305 is composed of a fourth conductor phase 351 on the electrode 101 side and a fourth functional gradient area 352 on the fifth conductor thin film 306 side. It has been confirmed that by adopting such a configuration, the effect of the gradient function equivalent to or higher than that of the conductive multilayer film shown in FIGS. 1 and 2 can be realized.

  According to the conductive multilayer film 300 shown in FIG. 3, since the four gradient functional regions are provided, it is possible to dramatically increase the gradient function that can be imparted, and the adjacent conductive thin film It becomes easy to have a configuration in which atomic arrangement is continuous in a chemical bond. As a result, in the conductive multilayer film 300 shown in FIG. 3, since at least a part of the gradient functional region of the adjacent conductor thin film has a chemical bond continuous atomic arrangement, The target (conductive) bond is more firmly maintained. For this reason, according to the conductive multilayer film 300 shown in FIG. 3, the stabilization of the electrical (conductive) characteristics is promoted, and as a result, the electrical (conductive) characteristics of the conductive multilayer film 300 as a whole can be further improved. become.

  In the above description, (La—Sr) Co—O fine particles of a perovskite crystal structure oxide conductor are used as a material constituting the conductor thin film. However, the present invention is not limited to this, and Ir—O, Ru -O, Ir-Al-O, Ir-Ti-O, Ir-Zr-O, Ir-Nb-O, Ir-Hf-O, Ir-Ta-O, AIN, Ti-Al, ZrN, NbN, HfN , TaN, Sr—Ru—O, La—Ni—O, Pb (Mg—Nb) Ti—O, Pb (Zr—Ti) O, HfSiN, TaSiN, and Y—Ba—Cu—O. Needless to say, the required conductive characteristics similar to those described above can be realized.

  The conductive thin film can be made of Pt, Ir, Ru, Zr, Nb, Hf, Ta, Mg, Al, Si, Co, Ni, Cu, Sr, Y, Ba, La, and Pb, or other lanthanum-based materials. What is necessary is just to be comprised from the oxide type conductor which contains at least 1 or more types of actinium type elements. According to these materials, as is well known, it is possible to form a conductive thin film with good high-temperature stability and high carrier density that contributes to conductivity, and further improve the reduction in energy and reliability. Can improve the characteristics.

  By the way, in the manufacture of the conductive multilayer film described above, a dry method in which a single metal or oxide as a raw material is fired according to the final composition, a vacuum heating method such as a resistance heating method, a molecular beam epitaxy method, and an ion beam method, Sputtering methods such as multipole (2, 4 and so on) plasma type, magnetron type, electron cyclotron resonance excitation plasma type, counter target type, and ion beam type, chemical vapor deposition (CVD) method, laser method (PLD method or Ablation method) may be used.

  In addition, although the method using active particles has been exemplified for the formation of the functionally graded region of the perovskite crystal structure oxide conductive multilayer film, other than this, the size of the conductor phase is adjusted and the phase boundary of the conductor phase is modified. It goes without saying that various gradient function imparting methods using quality, diffusion reaction, solid solution reaction, precipitation reaction and the like can be applied.

  In the above description, the conductive thin film (conductor phase) is provided with the functional gradient region in which the value of the atom-pair correlation distance is changed in a tilted manner. However, the present invention is not limited to this. For example, the conductor thin film may be provided with an inclined functional region in which the barrier height energy value with respect to the movement of carriers such as electrons and vacancies is inclined (changes in the thickness direction). In addition, the interface states (density) in a broad sense related to impurity levels (density) and defects, etc., become metastable sites of carriers. The conductive thin film may be provided with a functional gradient region in which the amount to be shown is inclined (changes in the thickness direction).

  In addition, the conductive thin film may be provided with a functionally graded region having a structure that is a site having a smaller size than a spatial region of a moving site required for the movement of a substance including carriers, levels, and ions. Good. In addition, the conductive thin film may be provided with a functionally graded region having a structure composed of an electric field state in a space of a moving site that electrically applies a repulsive force to a target substance. As described above, the functionally graded region may be any as long as the movement of the substance passing through this region is reduced.

  Also, a local carrier movement path (path) having an energy state in which the barrier height energy value of the charge is smaller than the energy value expressed by the dielectric polarization so that the positive and negative charge coalescence annihilation is realized. The conductive thin film may be provided with a functionally graded region having a structure in which is disposed. This is a function to reduce the expression of positive and negative charges due to the state including dielectric polarization in the vicinity of the interface with another adjacent conductive thin film, and a function to control to one of the electrical neutral state where no positive and negative charges are expressed. It becomes. Further, the conductive thin film may be provided with an inclined functional region in which an amount serving as an index of a chemical bond (electron distribution) state such as chemical shift or electronegativity is inclined (changes in the thickness direction). . This amount of inclination is related to conductivity such as carrier density and mobility.

  Further, the conductive thin film may be provided with a functionally graded region in which the atomic distribution such as the dynamic distribution function and the intrusion / substitution solid solution is inclined (changes in the thickness direction). Assuming a crystal, focusing on a lattice point, the atomic arrangement can be changed microscopically even if the dynamic distribution function and concentration, which are indicators of the probability of the existence of an atom depending on the distance from the lattice point, are constant. Any solid solution may be used. Also, the conductive thin film is provided with a functionally graded region in which the size and shape of the phase, which are macro values such as the size and density of the conductive phase and grain boundary, are inclined (changes in the thickness direction). May be.

  As described above, the conductive multilayer film according to the present invention is provided with a gradient function, thereby maintaining the original excellent required conductive characteristics of the conductor film as much as possible, and further, particularly with high-speed switching and switching. While reducing the dielectric loss that appears more strongly with higher frequencies (lowering energy), for example, superimposing functional effects such as diffusion controllability and electron tunneling controllability, and reduction of space charge polarization on the gradient functional region As a result, it is possible to realize a high-speed switching / high-frequency memory / capacitance element in which the dielectric properties of the conductive multilayer film are dramatically improved.

  Note that the above is merely an example of the effectiveness of the present invention, and by implementing the present invention, in particular, dielectric characteristics that require low energy and high speed operation and almost no deterioration in characteristics are required. It goes without saying that other high-performance applied parts and devices can be realized. In the above description, the electronic circuit, particularly high-speed switching / high-frequency integrated circuit, has been described. However, the present invention can be applied to a wider variety of electronic circuits, particularly integrated circuits. Further, it goes without saying that the conductive multilayer film of the present invention can be applied to the realization of micromachining related apparatuses such as a recording device and a drive mechanism, and other various parts and devices using a fine conductive multilayer film. Furthermore, even when the conductive multilayer film of the present invention is constituted by a plurality of basic constituent materials, it does not depart from the gist of the present invention.

It is sectional drawing which shows the structural example of the conductive multilayer film in embodiment of this invention. It is a block diagram which shows the structural example of the other conductive multilayer film 200 in embodiment of this invention. It is a block diagram which shows the structural example of the other conductive multilayer film 300 in embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Conductive multilayer film, 101 ... Electrode, 102 ... 2nd conductor thin film, 103 ... 1st conductor thin film, 104 ... Dielectric phase, 131 ... 1st gradient functional area, 132 ... 1st conductor phase.

Claims (14)

A conductive multilayer film composed of a first conductive phase having conductivity and a second conductive phase having conductivity disposed in contact with the first conductive phase;
The first conductor phase is
A gradient functional region in which at least one of a charge distribution state, a chemical bonding state, and an atomic arrangement structure state changes in the thickness direction of the first conductor phase is defined as the second conductor phase. A conductive multilayer film characterized by comprising: The conductive multilayer film according to claim 1,
The gradient functional region has an atomic arrangement that is chemically continuous with a part of the second conductor phase. The conductive multilayer film according to claim 1 or 2,
The gradient functional region is a state in which the movement of a substance passing through this region is reduced. The conductive multilayer film, wherein The conductive multilayer film according to claim 3,
The gradient functional region is composed of sites having a size smaller than a space region of a moving site required for the movement of the substance. The conductive multilayer film according to claim 3,
The gradient functional region is composed of a moving site space having an electric field state that applies an electric repulsive force to the substance. In the conductive multilayer film according to claim 1 or 2,
The gradient functional region is controlled to one of a function of reducing the expression of positive and negative charges due to a state including dielectric polarization and an electric neutral state where no positive and negative charges are expressed in the vicinity of the interface with the second conductor phase. A conductive multilayer film characterized by having a function of: The conductive multilayer film according to claim 6, wherein
The function of reducing the expression of positive and negative charges due to the state including the dielectric polarization,
A conductive multilayer film comprising a structure having a local charge transfer path having an energy state in which a barrier energy value of charge is smaller than an energy value at which dielectric polarization occurs. In the conductive multilayer film according to claim 1 or 2,
In the functionally graded region, the value of the atom-pair correlation distance changes in the thickness direction of the first conductor phase. In the conductive multilayer film according to claim 1 or 2,
In the functionally graded region, a barrier energy value against charge transfer changes in the thickness direction of the first conductor phase. In the conductive multilayer film according to claim 1 or 2,
In the functionally graded region, a density of a level that becomes a metastable site of charge changes in a thickness direction of the first conductor phase. In the conductive multilayer film according to claim 1 or 2,
The conductive multilayer film, wherein the gradient functional region has an amount serving as an index of a chemical bonding state including chemical shift and electronegativity changing in a thickness direction of the first conductor phase. In the conductive multilayer film according to claim 1 or 2,
In the functionally graded region, the atomic distribution changes in the thickness direction of the first conductor phase. In the conductive multilayer film according to any one of claims 1 to 12,
The first conductor phase and the second conductor phase are made of an oxide conductor having a perovskite crystal structure. In the conductive multilayer film according to any one of claims 1 to 13,
The first conductor phase and the second conductor phase are Pt, Ir, Ru, Zr, Nb, Hf, Ta, Mg, Al, Si, Co, Ni, Cu, Sr, Y, Ba, La, Pb, And a conductive multilayer film comprising an oxide-based conductor containing at least one of lanthanum-based and actinium-based.

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