KR20090031567A - Glass flux assisted sintering of chemical solution deposited thin dielectric films - Google Patents

Abstract

A method of making dense dielectrics layers via chemical solution deposition by adding inorganic glass fluxed material to high dielectric constant compositions, depositing the resultant mixture onto a substrate and annealing the substrate at temperatures between the softening point of the inorganic glass flux and the melting point of the substrate. A method of making a capacitor comprising a dense dielectric layer.

Description

Chemical solution deposition thin film dielectric layer is sintered in the presence of glass flux {GLASS FLUX ASSISTED SINTERING OF CHEMICAL SOLUTION DEPOSITED THIN DIELECTRIC FILMS}

The present invention relates to a buried capacitor, in particular a capacitor having a thin dielectric layer.

Embedded capacitors in printed wiring boards (PWB) can reduce circuit size and improve circuit performance. Capacitors are generally stacked and embedded in panels connected by wiring circuitry, which panel laminate forms a printed wiring board.

Fired-on-foil thin-film capacitor technology is known. U.S. Pat.No. 7,029,971 to Borland et al. Discloses a chemical solution deposition (CSD) thin film thin-film process, wherein a thin capacitor dielectric layer precursor material layer is first deposited on a metal thin film substrate. The thin film calcined thin layer CSD capacitor is manufactured by depositing by spin coating. Several spin coated layers can be used. The metal thin film substrate may be a copper thin film, and generally its thickness may range from 12 to 36 micrometers. The deposited CSD thin film capacitor dielectric layer material is subjected to a calcination or annealing process to crystallize the dielectric layer and increase the dielectric constant by increasing particle growth. The firing process may be performed under a reduced oxygen atmosphere at a high temperature, for example, 900 ° C. to prevent the metal layer of the lower layer from being oxidized. After the firing process, the dielectric layer will generally be a uniform ceramic layer and the thickness will be about 0.6 micrometers.

A metal electrode is then deposited on the thin film calcined thin ceramic capacitor dielectric layer. The deposition method for the electrode may be any one of various deposition methods. Sputtering is generally the preferred method. After depositing the electrode, the thin layer capacitor can exhibit high capacitance density and other desirable properties.

Embedded ceramic capacitors require, for example, high capacitance densities, allowable breakdown voltages, low dielectric losses and high reliability.

Capacitors having a high capacitance density can be obtained by using a dielectric layer having a thin layer and a high dielectric constant in the capacitor. The requirement for high reliability and good breakdown voltage is generally a high level of densification close to 100% density, which isolates any voids in the thin layer. Firing a CSD dielectric layer deposited on a copper thin film limits the shrinkage in the "z" axis or in the vertical direction when sintering occurs and the high fire resistance exhibited by the high-k material coexists, resulting in very high levels of densification. It is difficult. When fired at 900 ° C., a CSD dielectric layer having up to six layers with a fired thickness ranging from 0.5 to 1.0 micrometers in total, typically achieves a densification rate of 60-80% and the remainder of the dielectric layer is porous Most of the voids are connected to one another. In addition to concerns about reliability, since the dielectric constant of air is 1, such high porosity will result in a lower dielectric constant.

Therefore, the current field of electronic circuit industry has a problem to manufacture a high-density CSD dielectric layer of a thin film plastic capacitor while maintaining other desirable characteristics, for example high capacitance density. Firing at higher temperatures may be one way to achieve high levels of density, but the firing temperature should be lower than the melting point of the metal thin film. In the case of a copper thin film, the firing temperature should be lower than about 1050 ° C. Therefore, one means to solve the problem of manufacturing a high density CSD dielectric layer is to add an inorganic glass flux to the dielectric layer precursor material, thereby lowering the annealing temperature of the dielectric layer so that the thin film does not melt. .

Summary of the Invention

The present invention relates to a method for producing a high density CSD dielectric layer of a thin film plastic capacitor, the method of the present invention

Adding a small amount of inorganic glass to the high dielectric constant precursor material;

Forming a dielectric layer on the metal thin film; And

Firing the dielectric layer at a temperature above the softening or melting point of the glass but below the melting point of the thin film.

The invention also relates to a method of manufacturing a capacitor comprising such a high density CSD dielectric layer.

The various shapes discussed in the accompanying drawings are not drawn to scale. In order to more clearly illustrate embodiments of the present invention, the scales of various shapes and components in the drawings may be somewhat enlarged or reduced. Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings. Like reference numerals in the drawings indicate like elements.

FIG. 1 is a block diagram illustrating a method for preparing a high density dielectric barium titanate precursor solution doped with barium borate flux.

2 is a block diagram illustrating a manufacturing process of a high density capacitor on a copper thin film.

Figure 3 shows a barium oxide-boron oxide (BaO-B ₂ O ₃ ) phase diagram, the composition of the boron oxide and barium borate flux used to observe the phase change and 100% boron oxide, 25 mol% barium oxide Figure showing melting points for -75 mol% boron oxide, 33 mol% barium oxide-67 mol% boron oxide, and 37 mol% barium oxide-63 mol% boron oxide.

FIG. 4 is a graph of dielectric constant and loss tangent versus temperature of a thin barium titanate layer containing boron oxide glass flux added at 0, 0.69 and 1.38 mol% to the dielectric layer.

FIG. 5 is a graph of electric field strength vs. relative permittivity and loss factor of a copper thin film thin layered barium titanate capacitor containing boron oxide glass flux added at 1.38 mol% in the dielectric layer.

6A-6C are a series of scanning electron micrographs of the cross section of a ruptured copper thin film barium titanate capacitor dielectric layer containing boron oxide added at 0.69, 1.38 and 2.76 mole percent in the dielectric layer.

7A-7C are a series of focused ion beam (FIB) images of a cross-section of a thin copper thin film barium titanate capacitor dielectric layer containing boron oxide added to the dielectric layer at 0, 1.5 and 3.0 mol%, wherein The dielectric layer was identified using marker 700.

FIG. 8 is a graph of dielectric constant and dielectric loss versus temperature of a barium titanate thin layer containing barium borate (25 mol% barium oxide-75 mol% boron oxide) added at 0, 0.5 and 1 mol% to the dielectric layer.

FIG. 9 is a graph of electric field strength versus capacitance density and loss factor of a thin copper thin layered barium titanate capacitor containing barium borate (25 mol% barium oxide-75 mol% boron oxide) added to the dielectric layer at 1 mol%.

FIG. 10 is a series of cross sectional views of a ruptured copper thin-film thin barium titanate capacitor dielectric layer containing barium borate (25 mol% barium oxide-75 mol% boron oxide) added to the dielectric layer at 0.5, 1.0, and 2.5 mol%. Scanning electron micrographs.

11 is a plot of dielectric loss and dielectric loss versus temperature of a thin copper thin barium titanate layer containing barium borate (33 mol% barium oxide-67 mol% boron oxide) glass flux added to the dielectric layer at 0.5, 1.0, and 2.5 mol%. It is a graph.

FIG. 12 is a series of cross sectional views of a ruptured copper thin-film thin barium titanate capacitor dielectric layer containing barium borate (33 mol% barium oxide-67 mol% boron oxide) glass flux added at 0.5, 1.0 and 2.5 mol%. Scanning electron micrographs.

FIG. 13 is a graph of dielectric constant and dielectric loss versus temperature of a barium titanate thin layer containing barium borate (37 mol% barium oxide-63 mol% boron oxide) glass flux added at 0, 0.5 and 1 mol%.

FIG. 14 is a series of cross sectional views of a ruptured copper thin-film thin barium titanate capacitor dielectric layer containing barium borate (37 mol% barium oxide-63 mol% boron oxide) glass flux added at 0.5, 1.0, and 2.0 mol%. Scanning electron micrographs.

FIG. 15 is a graph illustrating the effects of boron oxide and barium borate under various boron oxide contents on the particle size of a thin barium titanate-based layer.

FIG. 16 is a series of FIB images of a copper thin film barium strontium titanate (Ba _0.65 Sr _0.35 TiO ₃ ) capacitor dielectric layer containing boron oxide glass flux added at 0, 2.5 and 5 mol% to the dielectric layer, wherein The dielectric layer was identified by marker 1600.

17-20 are graphs showing capacitance densities and dielectric losses for barium titanate thin film capacitors added at 1.0, 1.5, 2.5, and 5 mole percent to the dielectric layer.

21 is a graph showing the effect of the addition of barium phosphate to the particle size of the barium titanate thin layer.

details

The term "high dielectric constant" as used herein has the same meaning as the high dielectric constant, it means a value greater than 2000.

As used herein, the term "flux" means a fluid material that promotes densification by increasing the mass transfer rate.

The term "glass flux" or "inorganic glass flux" as used herein refers to a glass composition that melts during annealing and acts as a flux to the dielectric layer.

The present invention relates to a method for producing a high density dielectric layer composition having a high capacitance density and deposited as a dielectric layer by chemical solution deposition by adding a small amount of inorganic glass flux to a high dielectric constant precursor material. The present invention also relates to a method of manufacturing a capacitor comprising the high density dielectric layer composition. The capacitance density of the dielectric layer is proportional to its permittivity divided by the dielectric layer thickness. Therefore, a capacitor with high capacitance density can be obtained by using a thin high-k dielectric layer composition for the capacitor.

During firing or annealing, the high dielectric constant material itself forms a lower density dielectric layer, so adding a small amount of inorganic glass flux is a technical solution of the present invention. Specifically, the addition of a small amount of inorganic glass flux facilitates high density of the high dielectric constant material by liquid phase sintering rather than solid phase sintering. Thus, the dielectric material more easily achieves a high sintered density while maintaining a high capacitance density.

The dielectric constant of the fired dielectric layer composition is affected by the content of any optional second phase that the composition contains. The permittivity of the calcined dielectric layer composition, which may be formed into a thin layer, can be approximately calculated when the volume and permittivity of the second phase are known. Several equations or methods can be used. An example of such an assay is shown in Equation 1 below:

Log DK (comp) = Vf (incl) * Log DK (incl) + Vf (hk mat) * Log DK (hk mat)

In the above formula, Log DK (comp) is a logarithm of the dielectric constant of the formed thin layer;

Vf (incl) is the volume fraction of the second phase;

Log DK (incl) is the logarithm of the dielectric constant of the second phase;

VF (hk mat) is the volume fraction of the high dielectric constant material;

Log DK (hk mat) is a logarithmic value of the dielectric constant of the high dielectric constant material.

In the above mathematical analysis, the second phase should be a separate phase distinguished from the high dielectric constant material. This second phase can be air or glass. Therefore, the dielectric constant of air is 1 and the glass used in the method has a dielectric constant higher than that of air, so if simply replacing the air with the glass flux, all remaining conditions remain the same, The dielectric constant can be raised. However, the use of small amounts of suitable glass flux can significantly reduce the porosity, so that the formed thin layer can have a significantly higher permittivity as long as all other factors, such as final particle size, remain constant.

One requirement for high dielectric constant materials is that they form a polar non-centerymmetric phase. To form such a phase (typically tetragonal, but may also be a rhombic, tetragonal or monoclinic), it should generally exceed the minimum crystal grain size in the dielectric layer. Perovskite, represented by the general formula ABO ₃ , has this crystal size requirement. The perovskite includes crystalline barium titanate (BT), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), lead magnesium niobate (PMN) and barium strontium titanate (BST). Included. For example, in polycrystalline BaTiO ₃ -based materials, the dielectric constant drops sharply when the average particle size is in the range of less than 0.1 micrometer. Therefore, it is preferable that the barium titanate average particle size exceed the above dimension. Therefore, such a structure is useful as a raw material, i.e., a precursor material, for producing a high dielectric constant or high dielectric constant composition forming the thin layer or layer of the present invention.

The thin dielectric layer of the present invention has a high density microstructure and can exhibit significantly higher dielectric constants or permittivity relative to the material in which the flux is not used, depending on the glass flux selected. This thin dielectric layer is deposited by up to six coatings in an economical manner, has a rigid plastic thickness in the range of about 0.5 to 1.0 micrometers, and exhibits acceptable capacitance stability and low dielectric loss rates over a range of temperatures.

Since crystalline barium titanate and barium strontium titanate films with appropriate particle sizes exhibit high dielectric constants and do not contain lead, they are particularly useful for making high density dielectric layers capable of fabricating devices with very high capacitance densities. In short, the composition of the present invention can be used as a high density dielectric layer formed on a thin metal film. Subsequently, by forming a conductive layer on the high density dielectric layer, the thin film, the high density dielectric layer and the conductive layer form a capacitor having a high capacitance density. Such capacitors have a high density dielectric layer microstructure and can be embedded into an innerlayer panel and then integrated into a printed wiring board. Depending on the composition of the inorganic glass flux that is added to the dielectric layer precursor material, the growth of particles can be minimized or promoted, thereby providing capacitors with lower or higher dielectric constants than corresponding capacitors without flux added.

Substituents and dopant cations can be added to the flux-added high-k material to improve dielectric properties. Desirable properties for the high density dielectric layer capacitor will depend on the particular combination of dopants added.

Small amounts of suitable dopants include rare earth cations with the preferred oxide stoichiometry of R ₂ O ₃ , wherein R is a rare earth cation such as Y, Ho, Dy, La, Eu. Rare earth dopants improve the insulation resistance properties in the dielectric layer formed.

Transition metal cation dopants such as Mn and Fe may also be used to improve resistance to dielectric layer reduction and to improve insulation resistance properties. Other transition metal cations with the preferred oxide stoichiometry of MO ₂ , for example Zr, Hf, Sn, Ce, may also be suitable dopant cations. These transition metal cations flatten the temperature dependence of the dielectric constant of the dielectric layer through a process of "pinching", ie, three phase transitions of BaTiO ₃ in close proximity to each other in the temperature space.

A metal cation having a preferred oxide stoichiometry of MO (wherein M is an alkaline earth metal such as Ca, Sr, Mg) is used to shift the dielectric layer maximum to a lower temperature, thereby further enhancing the temperature dependent response characteristics of the dielectric layer. You can even make it flat.

Dopants as described above, or mixtures thereof, may be used in various concentrations with fluxed perovskite, such as BaTiO ₃ . Preferred concentration ranges are from about 0 to 5 mole percent of the final formulation.

Chemical solution deposition (CSD) is used to form a high density dielectric layer prepared by the method described above. This is because the CSD technique is desirable because it is simple and economical.

Chemical precursor solution

The chemical precursor solution contains additives useful for achieving a predetermined amount of each component for a given high dielectric constant material as well as other purposes, such as crack removal. Thus, when the predetermined high dielectric constant material is barium titanate, the chemical precursor solution will comprise barium acetate and titanium isopropoxide. Upon heating, the solution initially decomposes to form very fine barium oxide or particles of barium carbonate and titanium dioxide. On subsequent heating, they react together to form the final barium titanate composition.

As an example for demonstrating the relationship between the chemical precursor solution and the predetermined high dielectric constant material, a chemical composition for obtaining barium titanate (BaTiO ₃ ) has been presented. BaTiO ₃ without flux (or pure) is preferably prepared by using the following chemicals in the corresponding amounts:

5.12 grams of barium acetate

5.68 grams of titanium isopropoxide

4.12 milliliters of acetylacetone

Acetic acid 43.52 milliliters

Acetic acid and acetylacetone are dissolution media for barium acetate and titanium isopropoxide.

Diethanolamine (DEA) may be added at 8-12% of the barium acetate weight to prevent cracking of the dielectric layer. Thus, for example, the amount of DEA added to the precursor solution as described above may be 0.58 g in total.

Once the desired precursor composition for the high dielectric constant material barium titanate is prepared, inorganic glass flux can be added to the precursor solution using the following materials: barium acetate; Triethylborate or tri-n-butylborate; Di-2-ethylhexyl phosphoric acid; And acetic acid.

The chemicals listed below may be added to the precursor solution described above to supply the corresponding cations. For example, manganese acetate tetrahydrate can be added to feed Mn: yttrium acetate hydrate to feed Y can be added; Zirconium propoxide can be added to feed Zr; Calcium acetate hydrate can be added to feed Ca; Strontium acetate hydrate can be added to feed Sr; Holmium acetate hydrate can be added to supply Ho; Dysprosium acetate hydrate can be added to supply Dy; Tetrakis (1-methoxy-2-methyl-3-propoxy) hafnium can be added to feed Hf; Iron acetate may be added to feed Fe; Magnesium acetate tetrahydrate can be added to feed Mg.

Common way

A general method of making the high density dielectric layer of the present invention includes providing a specific chemical precursor solution of certain compounds (described above for barium titanate) that can produce a high dielectric constant material that is free of flux upon firing. do. A glass plus material (and optionally a dopant) is added to the chemical precursor solution to produce a fluxed mixture, which is deposited on a substrate, generally a metal thin film, via chemical solution deposition. The coating can be heated to achieve drying at temperatures generally below the annealing temperature. The coated substrate is then annealed (ie calcined) to crystallize the chemical precursor solution and produce the desired dielectric layer. A feature of the process of the present invention is that the annealing temperature is within a predetermined range, that is, the annealing occurs at a temperature above the softening point of the glass flux additive but at a temperature range below the melting point of the metal thin film substrate.

As discussed earlier, barium titanate (BT), lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), lead magnesium niobate (PMN) and barium strontium titanate (BST) and these Mixtures of are useful for preparing the high dielectric constant or high dielectric constant layers or thin layers of the invention. Furthermore, crystalline barium titanate and barium strontium titanate produce particularly useful high density dielectric layers, from which high capacitance density devices can be fabricated.

1 is a block diagram illustrating a method of preparing a precursor solution that can be used to prepare a dielectric layer in accordance with the method of the present invention. In step S110, titanium isopropoxide is premixed with acetylacetone. The premixing step is, for example, can be carried out in the Pyrex (PYREX ^®) vessel. In step S120, acetic acid is added to barium acetate and stirred at room temperature to dissolve barium acetate. In step S130, barium acetate dissolved in acetic acid is added to the mixture of titanium isopropoxide and acetylacetone and stirred. In step S140, diethanolamine (DEA) is added to the solution and stirred. In step S150, a predetermined amount of flux composition, in this case barium borate, and a predetermined amount of any doping chemical selected from the above-listed chemicals are added to the vessel, and the solution is dissolved until the chemical is dissolved. Stir. In this way, a precursor solution for vapor deposition is provided.

deposition

2 is a block diagram of one method of manufacturing a capacitor in accordance with the present invention. The dielectric layer of the prepared capacitor can be prepared using the precursor solution described above with respect to FIG. 1. Modifications of the acetic acid, acetylacetone and titanium isopropoxide components in the precursor solutions described above may be used. For example, some of acetic acid can be replaced with methanol, ethanol, isopropanol, acetone, butanol and other alcohols. Instead of acetylacetone, for example ethanolamines such as 3-ethanolamine, diethanolamine or monoethanolamine can be used. Titanium butoxide may be used instead of titanium isopropoxide.

The solution deposition method shown in FIG. 2 is a spin coating method. Other solution deposition methods, such as dip coating, slot die coating, gravure coating or spray coating, may also be used to deposit the precursor solution. The method shown in FIG. 2 relates to the manufacture of a single capacitor. However, several capacitors can be manufactured batchwise using the method shown in FIG.

In step S210, the metal thin film is cleaned. The metal thin film may be made of copper. Copper thin films are preferred because they are inexpensive and easy to handle. The copper thin film is used as a substrate to produce a capacitor on the substrate. The thin copper film also acts as a capacitor "bottom" electrode in the final capacitor product. In one embodiment, the substrate is an electroless copper thin film having a thickness of 18 μm. Other untreated thin films, such as 1 oz copper thin films, are also suitable. Suitable washing conditions include etching the thin film in a dilute copper chloride solution in hydrochloric acid for 30 seconds. The etching solution can be diluted about 10,000 times from the concentrated form. The cleaning process removes accumulated foreign matter from excess oxide layers, fingerprints and other thin films. If the copper thin film is obtained substantially from a commercially available source or other source and is carefully handled and quickly used, the cleaning procedure recommended above may not be necessary.

The copper thin film is preferably not treated with an organic additive. In some cases, organic additives may be used to increase the adhesion of the metal substrate to the epoxy resin. However, organic additives can degrade the dielectric layer during annealing.

In step S220, a precursor solution as described above with respect to FIG. 1 is deposited on a copper thin film substrate. The precursor solution can be attached, for example, using a plastic syringe. The precursor solution is deposited on the drum side (or “smooth side”) of the copper thin film substrate.

In step S230, the substrate is rotated for spin coating. Suitable rotation times and speeds are for 30 seconds at 3000 revolutions per minute. In step S240, the substrate is heat treated. The heat treatment can be carried out, for example, at a temperature of 250 ° C. for 5 to 10 minutes. The precursor solution is dried by evaporating the solvent in the precursor solution using heat treatment. After heat treatment, the dried dielectric layer precursor is about 150 nm thick. Successive rotating steps can be used to coat the thin film substrate to a predetermined thickness. For example, six rotational steps can be used to produce the final dried dielectric layer precursor having a thickness of about 1 μm.

Annealing

In step S250, the coated substrate is annealed. Annealing first removes remaining organics and then crystallizes the dried dielectric layer precursor. Annealing can be performed on dielectric layers deposited on copper thin films under high oxygen partial pressure environments at high temperatures. Suitable total pressure environment is about 1 atmosphere. Suitable oxygen partial pressures for the dielectric layer on the copper thin film are 10 ^-10 to 10 ^-12 atmospheres.

In step S250, low oxygen partial pressure can be achieved by foaming high purity nitrogen through a temperature controlled water bath. It is also possible to add other gas combinations, such as small amounts of hydrogen containing synthesis gas, to the gas mixture. The annealing temperature should be higher than the softening point of the glass flux additive but below the melting point of the metal thin film substrate. In one embodiment, a thin copper film is used as a substrate, 1 mol% of a composition consisting of 25 mol% of barium oxide and 75 mol% of boron oxide is used as the flux, and the furnace temperature is about 900 ° C, and oxygen the partial pressure of about ^10-12 atmospheres. The bath may be present at a temperature of about 25 ° C. Annealing may be performed by inserting the coated thin film substrate into the urinary tract at a temperature below 250 ° C. The urinary tract is then raised to 900 ° C. at a rate of about 30 ° C./min. The urinary tract is kept at 900 ° C. for 30 minutes.

This annealing temperature of 900 ° C. allows the copper thin film to be used as a substrate while at the same time softening and flowing the glass flux to maximize density of the dielectric layer. In addition, annealing may crystallize the deposited dielectric layer.

It is also possible to obtain desirable results at annealing temperatures higher than 900 ° C. Higher temperatures, such as 1200 ° C., may be used in combination with a suitable atmosphere to prevent oxidation of the metal substrate and to facilitate the use of various metal substrates such as various glass fluxes and nickel. In addition, annealing may be performed in air without a reducing atmosphere, as the chemical properties of the substrate permit. The substrate may include a noble metal thin film or a ceramic oxide composition.

In general, the dielectric constant of polycrystalline BaTiO ₃ -based materials drops sharply when the average particle size is in the range of less than 0.1 micrometer. Depending on the choice of flux composition, an average particle size in the range of 0.1 micrometers to 0.2 micrometers is generally obtained in the glass fluxed dielectric layer, which can provide dielectric constant values above 2500.

If the particle size is larger, higher permittivity can be obtained. Larger particle sizes can be obtained by using additional flux of appropriate composition, using higher annealing temperatures, using longer annealing times, or using them in combination. However, it is desirable to have several particles across the dielectric layer (i.e. across the thin layer widths between the electrodes) because the particles provide an acceptable long term reliability of the capacitor. Therefore, the particle size can be adjusted to suit the desired thickness for the dielectric layer. For example, with a dielectric layer thickness in the range of 0.5-1.0 micrometers, approximately 5-8 particles may extend from one electrode to another when the average particle size is 0.1-0.2 micrometers. In general, the presence of five or more particles across the dielectric layer is desirable in view of the long term reliability of the acceptable capacitor. In the case of thicker dielectric layers, such as dielectric layers having a thickness of 2 micrometers, larger particle sizes in the range of 0.2 to 0.4 micrometers can be tolerated, thus providing higher permittivity. If a dielectric layer thinner than 0.5 micrometers is desired, smaller particle sizes can be used by selecting an appropriate flux composition that limits particle growth.

According to the annealing process for the dielectric layer on the copper thin film as described above, it is generally not necessary to oxidize the copper thin film to Cu ₂ O or CuO. The oxidation reaction is excluded by selecting an appropriately low oxygen partial pressure for the high processing temperature used during annealing in step S250. The oxygen partial pressure range that reliably excludes copper oxidation and does not deleteriously reduce the dielectric layer ranges from 1 × 10 ⁻⁹ to 1 × 10 ⁻¹⁴ atmospheres. Thus, a good BaTiO ₃ or other high dielectric constant layer can be produced without oxidizing the copper thin film or severely degrading the dielectric layer during annealing. Different air pressures may be required when using different metal thin films and annealing temperatures. This air pressure can be calculated from standard free energy of oxide formation as a function of temperature as described in FD Richardson and JHE Jeffes, J. Iron Steel Inst., 160: 261 (1948).

After annealing

In step S260, the thin film substrate is cooled. The cooling step may simply be switching off the urinary tract. Alternatively, the urinary tract temperature can be lowered at a certain rate. When the urinary tract temperature reaches about 450 ° C., the thin film substrate can be safely removed from the urinary tract without the risk of undesirable oxidation on the copper thin film. Alternatively, the urinary tract may be allowed to reach room temperature and then the thin film substrate may be removed from the urinary tract.

In step S270, the high-k dielectric layer or thin layer may be subjected to a reoxidation process to improve insulation resistance characteristics of the dielectric layer. Reoxidation may correspond to annealing at 450 ° C. for 30 minutes under an oxygen partial pressure of approximately 10 ⁻⁴ atmospheres. Reoxidation can be integrated, for example, into the cooling step S260, or performed as a separate step after the cooling step. If an appropriate receptor dopant is used, no reoxidation step may be required. Manganese, magnesium, etc. are mentioned as such a receptor dopant.

In step S280, an "top" electrode is formed on the formed dielectric layer. The thin film substrate serves as the bottom electrode of the capacitor manufactured by the above method. The top electrode can be formed by, for example, sputtering, combustion chemical vapor deposition, electroless plating, printing or other suitable deposition method. In one embodiment, sputtered platinum electrodes are used. Other materials suitable for the top electrode include nickel, copper and palladium. It is also possible to increase the thickness by plating the top electrode.

Hereinafter, useful properties of the dielectric layer composition manufactured according to the method of the present invention and a capacitor including the same will be described through examples. In the embodiments described below, where a content, concentration or other value or variable is given as a range, as one or more preferred ranges, or as a list of preferred upper and preferred lower limits, the range or list is specifically any upper or preferred value. And all ranges formed from any lower limit or any pair of desirable values, regardless of whether the corresponding pair is described separately.

Example 1-3

A barium titanate thin layer capacitor was fabricated on a thin copper film using the method shown in FIG. The precursor composition contained 0, 0.69 and 1.38 mol% boron oxide glass flux additive by adding the appropriate amount of triethylborate to the barium titanate solution. Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. The dielectric layer composition was reannealed at 450 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻⁴ atmospheres. The maximum or relative permittivity of the resulting barium titanate thin layer was slightly lower than approximately 1600, 2250, and 3000, respectively, at boron oxide concentrations of 0, 0.69, and 1.38 mol%, as shown in FIG. The relative permittivity and loss factor of the electric field strength of the barium titanate thin layer to which 1.38 mol% of boron oxide flux was added are shown in FIG. 5. Cross-sectional scanning electron micrographs of ruptured samples of thin barium titanate layers are shown in FIGS. 6A-6C. The effect of boron oxide flux on the particle size of barium titanate is shown in FIG. 15.

Example 4-6

A barium titanate thin layer capacitor was fabricated on a copper thin film using the method shown in FIG. The composition contained 0, 1.5 and 3.0 mol% boron oxide glass flux additive by adding the appropriate amount of tri-n-butylborate to the barium titanate solution. Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. A cross section of the dielectric layer was made and focused ion beam (FIB) images were taken from the cross section to observe porosity. Corresponding images are shown in FIGS. 7A-7C, where the dielectric layer is identified by marker 700.

Example 7-9

A barium titanate thin layer capacitor was fabricated on a copper thin film using the method shown in FIG. The composition contained 0, 0.5 and 1.0 mol% barium borate (25 mol% barium oxide-75 mol% boron oxide) glass flux additive by adding the appropriate amounts of barium acetate and triethylborate to the barium titanate solution. Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. The dielectric layer was annealed and then reoxidized at 450 ° C. for 30 minutes under an oxygen partial pressure of 10 ⁻⁴ atmospheres. The maximum dielectric constant or relative permittivity of the resultant thin barium titanate thin layer added with barium titanate and barium borate flux is 0 mol%, 0.5 mol% and 1.0 mol% of barium borate (25 mol%), as shown in FIG. 8. Barium oxide-75 mol% boron oxide) glass flux additives were approximately 1500, 2400, and approximately 3000, respectively. The field strength relative to the relative permittivity and loss factor of a thin barium titanate layer containing 1.0 mol% barium borate (25 mol% barium oxide-75 mol% boron oxide) glass flux additive is shown in FIG. 9. Cross-sectional scanning electron micrographs of ruptured samples of thin barium titanate layers are shown in FIGS. 10A-10C. The effect of the flux on the particle size of barium titanate is shown in FIG. 15.

Example 10-12

A barium titanate thin layer capacitor was fabricated on a copper thin film using the method shown in FIG. The composition contained 0, 0.5 and 1.0 mol% barium borate (33 mol% barium oxide-67 mol% boron oxide) glass flux additive by adding the appropriate amounts of barium acetate and triethylborate to the barium titanate solution. Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. The dielectric layer was annealed and then reoxidized at 450 ° C. for 30 minutes under an oxygen partial pressure of 10 ⁻⁴ atmospheres. The maximum permittivity or relative permittivity of the barium titanate thin layer to which the resultant pure barium titanate and barium borate (33 mol% barium oxide-67 mol% boron oxide) flux was added is 0 mol%, 0.5, as shown in FIG. For mol% and 1.0 mol% barium borate (33 mol% barium oxide-67 mol% boron oxide) glass flux additives were approximately 1500, 2200, and 2700, respectively. Cross-sectional scanning electron micrographs of ruptured samples of thin barium titanate layers are shown in FIGS. 12A-12C. The effect of the flux on the particle size of barium titanate is shown in FIG. 15.

Example 13-15

A barium titanate thin layer capacitor was fabricated on a copper thin film using the method shown in FIG. The composition contained 0, 0.5 and 1.0 mol% barium borate (37 mol% barium oxide-63 mol% boron oxide) glass flux additive by adding the appropriate amounts of barium acetate and triethylborate to the barium titanate solution. Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. The dielectric layer was annealed and then reoxidized at 450 ° C. for 30 minutes under an oxygen partial pressure of 10 ⁻⁴ atmospheres. The maximum permittivity or relative permittivity of the barium titanate thin layer to which the resultant pure barium titanate and barium borate (37 mol% barium oxide-63 mol% boron oxide) flux was added is 0 mol%, 0.5, as shown in FIG. For mol% and 1.0 mol% barium borate (37 mol% barium oxide-63 mol% boron oxide) glass flux additives were approximately 1500, 1900, and 2600, respectively. Cross-sectional scanning electron micrographs of ruptured samples of thin barium titanate layers are shown in FIGS. 14A-14C. The effect of the flux on the particle size of barium titanate is shown in FIG. 15.

Example 16-18

A barium strontium titanate (Ba _0.65 Sr _0.25 TiO ₃ ) thin layer capacitor was prepared on a copper thin film using the method shown in FIG. 2. The composition contained 0, 2.5 and 5.0 mol% boron oxide glass flux additive by adding the appropriate amount of tri-n-butylborate to the barium titanate solution. Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. A cross section of the dielectric layer was made and focused ion beam (FIB) images were taken from the cross section to observe porosity. Corresponding images are shown in FIGS. 16A-16C, where the dielectric layer is identified by marker 1600.

Example 19-22

A barium titanate thin layer capacitor was fabricated on a copper thin film using the method shown in FIG. The composition contained 1, 1.5 and 2.5 mol% barium phosphate (47.5 mol% barium oxide-52.5 mol% phosphorus pentoxide) glass flux additive by adding an appropriate amount of barium acetate and 2-ethylhexylphosphate to the barium titanate solution. . Annealing was performed at 900 ° C. for 30 minutes under an atmosphere of oxygen partial pressure of 10 ⁻¹² atmospheres. The dielectric layer was annealed and then reoxidized at 450 ° C. for 30 minutes under an oxygen partial pressure of 10 ⁻⁴ atmospheres. As a result, the maximum capacitance density of the obtained barium titanate thin layer added with barium phosphate flux was 1.0 mol%, 1.5 mol%, 2.5 mol% and 5.0 mol% of barium phosphate (47.5 mol%). Barium oxide-52.5 mol% phosphorus pentoxide) were approximately 0.75, 0.65, 0.6 and 0.3 μF / cm ² , respectively, for the glass flux additive. The effect of the addition of barium phosphate flux additive on the particle size of barium titanate is shown in FIG. 21.

As can be seen from the series of micrographs shown in FIGS. 6, 7, 10, 12, 14 and 16, small amounts of boron oxide or barium borate (25/75, 33-67 and 37-63 molar ratios of oxidation The addition of barium to boron oxide glass flux significantly improves the densification of the barium titanate thin layer. In general, as the amount of flux increases, the porous properties change into pores separated from the connected pores. Connected pores are undesirable because these pores can form moisture permeable channels and cause problems in terms of long term reliability. From the micrographs, it can be expected that a microstructure with separated pores can be obtained when the boron oxide or barium borate glass flux is approximately 1 to 2 mol%.

As can be seen from FIGS. 4, 8, 11 and 13, the addition of a small amount of boron oxide or barium borate increases the maximum dielectric constant. This suggests that the effect of diluting boron oxide or barium borate glass under the investigated concentration is lower than the effect of improving the dielectric constant due to high density. In addition, as can be seen from the figure, over a temperature range of -55 ° C to + 125 ° C, the dielectric constant varies no more than about 15%.

5 and 9 show the electric field strength versus the relative permittivity and loss factor of barium titanate using 1.38 mol% boron oxide and 1 mol% (25 mol% barium oxide-75 mol% boron oxide). As can be seen from the figure, the permittivity ranges from 2500 to 3000, comparable to the permittivity measured from the densified compacted thin layers exhibiting similar particle sizes made using powders. These results also suggest that the effect of diluting the barium borate glass under the investigated concentration is lower than the effect of improving the dielectric constant due to high density. In addition, the loss coefficient shows excellent values even for a fairly high electric field strength.

FIG. 15 shows the effect of the addition of barium borate on the particle size of barium titanate. As can be seen from the figure, the addition of barium borate promotes grain growth under the same annealing conditions. This is partly due to an increase in dielectric constant and an increase in density. Adding more than 3 mole% results in somewhat expanded particle growth, making it difficult to measure the average particle size.

Figure 17 to 20 is a first phosphoric acid to 5 mol% of barium shows a annealing a capacitance density and loss factor of the barium titanate thin layer under an oxygen partial pressure of 10 ^-12 atm. The thin layer exhibits the same densification characteristics as the thin layer added with barium borate, but as can be seen from the drawing, the capacitance density is reduced compared to the thin barium titanate layer or the barium titanate thin layer using the equivalent barium borate glass flux additive. do.

FIG. 21 shows the effect of the addition of barium phosphate on the particle size of the thin barium titanate layer. As can be seen from the figure, the particle size is significantly reduced to less than 0.08 micrometers, which explains why the capacitance density is low. It is believed that barium phosphate acts as a particle growth inhibitor, while barium borate acts as a particle growth enhancer. Therefore, the addition of barium phosphate flux would be very useful for capacitors where the dielectric layer is very thin, for example less than 0.5 micrometers, and where high density microstructures are needed.

Claims (11)

Mixing a solution comprising a high dielectric constant material with a solution comprising an amount of an inorganic glass flux material such that the inorganic flux material constitutes 0.5-5 mole percent of the dielectric layer composition; Coating the substrate with the mixture to form a substrate having a coating of identifiable thickness; Annealing the coated substrate at a temperature above the softening point of the inorganic glass flux material but below the softening point or melting point of the substrate to form a dielectric layer composition, Here, upon annealing, the increase in dielectric constant of the dielectric layer composition obtained by increasing the density of the dielectric layer composition is greater than the decrease in dielectric constant of the dielectric layer composition by dilution with the inorganic glass flux material, through a chemical solution deposition method. A method of making a dielectric layer composition having a high dielectric constant. Providing a metal thin film; Mixing a solution comprising a high dielectric constant material with a solution comprising an amount of an inorganic glass flux material such that the inorganic flux material constitutes 0.5-5 mole percent of the dielectric layer composition; Forming a dielectric layer comprising said mixture on said thin film; Annealing the dielectric layer at a temperature above the softening point of the inorganic glass flux material but below the melting point of the metal thin film to form a dielectric layer composition having a high dielectric constant; Forming a conductive layer on the dielectric layer, Wherein, in annealing, the increase in permittivity obtained by increasing the densification of the dielectric layer composition is greater than the decrease in permittivity of the dielectric layer composition by dilution with the inorganic glass flux material. The method of claim 1 or 2, further comprising optionally reoxidizing the coated substrate or the dielectric layer. The method of claim 1 or 2, wherein the high dielectric constant material comprises 0.05 to 0.5 mole percent dopant of the dielectric layer composition. 3. The method of claim 1 or 2, wherein the high dielectric constant material is selected from the group consisting of barium titanate, barium strontium titanate, lead zirconate titanate, lead magnesium niobate, lead lanthanum zirconate titanate, and mixtures thereof. The method selected. The method of claim 1 or 2, wherein the inorganic glass flux material is selected from the group consisting of metal borate salts, phosphates, fluorides, boron oxides, barium borate fluxes and mixtures thereof. The method of claim 1 or 2, wherein the substrate is a metal thin film. The method of claim 1 or 2, wherein the thickness of the coating ranges from 0.1 micrometers to 2.0 micrometers. A capacitor manufactured by the method of claim 2. A printed wiring board comprising a capacitor manufactured by the method of claim 2. A printed wiring board comprising a capacitor comprising a dielectric layer composition prepared by the method as defined in claim 1.

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