JP4872306B2 - Method for manufacturing substrate for thin film electronic component and method for manufacturing thin film electronic component using the same - Google Patents

Description

  The present invention relates to a substrate for forming a thin film layer such as an electrode layer or a dielectric layer as a thin film electronic element on a substrate made of a ceramic polycrystalline body or a glass ceramic body, a thin film electronic component thereof, and a method for manufacturing the same.

  2. Description of the Related Art Conventionally, electronic components in which passive elements such as capacitors are formed on a ceramic polycrystalline substrate such as alumina or a glass ceramic substrate (low temperature fired substrate, LTCC) are widely known. Since thin-film device manufacturing technology is used to manufacture such thin-film electronic components, the surface of the substrate on which the passive elements are formed needs to be sufficiently smooth. (See Patent Document 1).

  However, since there are a large number of pores in a substrate made of a ceramic polycrystalline body or a glass ceramic body, a large number of open pores are exposed on the surface of the substrate when it is mirror-finished by polishing. Such a pore tends to be particularly large in a glass ceramic substrate in which a glass component (frit material) is contained in the substrate. This is presumed to be because the glass component is melted during the firing of the glass ceramic substrate and gas is generated, and the encapsulated bubbles are not completely removed. For this reason, especially in a glass ceramic substrate, the depth of the exposed pore may reach about 3 μm or more. If such a deep pore is exposed on the surface of the substrate, it is formed using a thin film device manufacturing technique. May cause defects in passive elements. For example, when a thin film capacitor is formed, there is a possibility that the lower electrode layer and the upper electrode layer are short-circuited at the pore portion.

In order to suppress such defects on the surface of the substrate, for example, it is conceivable to apply the technique disclosed in Patent Document 2 in which a coat film is formed on the surface of the substrate by a sol-gel method. The technique disclosed in Patent Document 2 is as follows. A green sheet made of alumina or the like is formed by a doctor blade method, wiring is formed on the green sheet by a thick film device manufacturing technique, a plurality of green sheets are laminated, and then fired to obtain a multilayer wiring board. Here, voids are formed inside and on the surface of the substrate due to the gas generated during the firing of the green sheet. In particular, voids that appear near the surface become pores (surface defects) on the surface, and are formed on the surface of the fired substrate after firing. Cause wiring failure of fine wiring. Therefore, in order to prevent the occurrence of wiring defects while using the surface of the fired substrate as a smooth surface, and to ensure sufficient conduction such as via holes, a coat film is formed on the surface of the fired substrate by the sol-gel method, thereby smoothing the surface of the substrate. It aims to make it easier.
JP-A-10-98158 JP-A-5-74979

The substrate surface has irregularities in a wide region due to waviness caused by shrinkage during baking of the substrate, but this type of irregularities can be smoothed by polishing. However, in a glass ceramic substrate, for example, Al ₂ O ₃ is present as dispersed particles in a glass phase mainly composed of SiO ₂ , but since the Al ₂ O ₃ particles are harder than the glass phase, the substrate is polished. The exposed surface of the Al ₂ O ₃ particles is slightly convex than the surface of the glass phase. FIG. 1 shows a schematic sectional view of the vicinity of the surface of the glass ceramic substrate. As shown in FIG. 1, according to the inventors' investigation, it was found that the step between the exposed surface of the Al ₂ O ₃ particles and the surface of the glass phase is at least 5 to 60 nm, although it depends on the polishing technique. Such a step in a narrow region about the particle diameter of Al ₂ O ₃ particles causes defects when applying a highly accurate thin film device manufacturing technique. Furthermore, the above-mentioned pore exists in the surface of a glass phase, According to inventors' investigation, the depth is 0.5-10 micrometers. Since the pore diameter is almost the same as the depth, a recess of 0.5 to 10 μm in the region of 0.5 to 10 μm causes a defect when applying a highly accurate thin film device manufacturing technique.

In a ceramic polycrystalline substrate or a glass ceramic substrate, only by providing a coat layer as exemplified in Patent Document 2 on the surface of the substrate, a pore of the coat layer communicating with the pore of the substrate occurs at the location of the pore, or the substrate The unevenness of the coating layer corresponding to the exposed surface of the pores or Al ₂ O ₃ particles occurs. Accordingly, it has been found that when such unevenness is present in the coat layer, when a highly accurate thin film device manufacturing technology is applied, problems such as short circuits that can be solved when the thick film device manufacturing technology is applied are still not solved.

  In order to manufacture thin-film electronic components by forming passive elements on a ceramic polycrystalline substrate or glass-ceramic substrate that has irregularities in a minute area on the surface by applying high-precision thin-film device manufacturing technology in this way Therefore, it is necessary to give the substrate smoothness with higher accuracy than when a thick film electronic component is manufactured by forming a passive element by a thick film device manufacturing technique.

  An object of the present invention is to apply a highly accurate thin film device manufacturing technique for forming a thin film having a thickness of several nanometers to several μm, and to provide a ceramic polycrystalline substrate or a glass ceramic substrate having high precision smoothness and its production. Is to provide a method. Furthermore, it aims at providing the thin film electronic component which formed the passive element on the ceramic polycrystalline substrate and glass ceramic substrate which have high precision smoothness, and its manufacturing method.

A thin film electronic component substrate (hereinafter simply referred to as a thin film electronic component substrate according to the present invention or a thin film electronic component substrate according to the present embodiment) obtained by the method for manufacturing a thin film electronic component substrate according to the present invention is described below. In a substrate in which a coating layer is provided on at least one surface of a plate-like ceramic polycrystalline body or glass ceramic body, the coating layer is made of a metal oxide thin film, and the thickness of the metal oxide thin film is 0.1 μm or more and 20 μm or less. The surface roughness Ra is 0.5 nm or more and 20 nm or less.

  The substrate for a thin film electronic component according to the present invention is a substrate in which a coating layer is provided on at least one surface of a plate-like ceramic polycrystalline body or glass ceramic body, and the coating layer comprises a metal oxide thin film, The thickness of the object thin film is 0.1 μm or more and 20 μm or less, and the total opening area of pores opened on the surface of the metal oxide thin film is 150 ppm or less with respect to the surface area of the metal oxide thin film. .

  The substrate for a thin film electronic component according to the present invention is a substrate in which a coating layer is provided on at least one surface of a plate-like ceramic polycrystalline body or a glass ceramic body, and the coating layer comprises a metal oxide thin film, The thickness of the thin film is 0.1 μm or more and 20 μm or less, and the number of coating layer pores opened on the surface of the metal oxide thin film is 30% or less of the number of substrate pores opened on the surface of the substrate. .

Furthermore , the thin film electronic component using the thin film electronic component substrate obtained by the method for manufacturing the thin film electronic component substrate according to the present invention (hereinafter simply referred to as the thin film electronic component according to the present invention or the thin film electronic component according to the present embodiment). ) Provided a lower electrode layer on the coating layer made of the metal oxide thin film, a thin film dielectric layer on the lower electrode layer, and an upper electrode layer on the thin film dielectric layer. It is characterized by.

The method for manufacturing a substrate for a thin film electronic component according to the present invention comprises flattening by grinding at least one surface of a plate-like ceramic polycrystalline body or glass ceramic body, and then performing a mirror surface treatment by CMP (Chemical Mechanical Polishing). Then, after obtaining the smooth mirror substrate, a coating layer is formed on the polished surface of the smooth mirror substrate by applying a raw material liquid containing a raw material that becomes a metal oxide by heating, and the metal oxide thin film layer is heated by heating the coating layer. Forming a coating layer by coating the raw material liquid on the surface of the metal oxide thin film layer, and then forming the metal oxide thin film layer by heating the coating layer at least once. by laminating, to form a coating layer made of 20μm or less of the film thickness of the metal oxide thin film or 0.1 [mu] m, the metal oxide thin film, gold The surface roughness Ra of the oxide thin film is 0.5 nm or more and 20 nm or less, or the total opening area of pores opened on the surface of the metal oxide thin film is 150 ppm or less with respect to the surface area of the metal oxide thin film Alternatively, at least one of the number of coating layer pores opened on the surface of the metal oxide thin film is 30% or less of the number of substrate pores opened on the surface of the substrate .

  In the method for manufacturing a substrate for a thin film electronic component according to the present invention, it is preferable that the coating layer is formed by coating the raw material liquid once or a plurality of times.

  In the method for manufacturing a thin film electronic component substrate according to the present invention, the firing temperature of the coating layer is preferably 500 ° C. or higher and lower than 1000 ° C.

  In the method for manufacturing a thin film electronic component substrate according to the present invention, it is preferable to use a raw material mainly composed of Si as the raw material.

  The method of manufacturing a thin film electronic component according to the present invention includes a lower electrode layer provided on a coating layer made of a metal oxide thin film provided on a substrate for a thin film electronic component according to the present invention, and a thin film dielectric formed on the lower electrode layer. A body layer is provided, and an upper electrode layer is provided on the thin film dielectric layer. Here, the lower electrode layer and the upper electrode layer are preferably formed by a vapor phase method such as a PVD method.

  According to the present invention, it is possible to provide a ceramic polycrystalline substrate or a glass ceramic substrate having high-precision smoothness to which a high-precision thin film device manufacturing technique for forming a thin film having a thickness of several nm to several μm can be applied. Furthermore, a thin film electronic component in which a passive element is formed on a ceramic polycrystalline substrate or a glass ceramic substrate having high-precision smoothness can be provided.

  Hereinafter, although an embodiment is shown to the present invention and the present invention is explained in detail, the present invention is limited to these descriptions and is not interpreted. The substrate for a thin film electronic component according to this embodiment is a substrate in which a coating layer is provided on at least one surface of a plate-like ceramic polycrystalline body or glass ceramic body, and the coating layer is made of a metal oxide thin film, The film thickness is 0.1 μm or more and 20 μm or less, and the surface roughness Ra is 0.5 nm or more and 20 nm or less.

  The base of the thin film electronic component substrate is a plate-like ceramic polycrystalline body or glass ceramic body. Glass substrates and silicon single crystal substrates can be applied to thin film device technology because the surfaces are sufficiently smooth, but ceramic polycrystalline substrates and glass ceramic substrates are used because the surfaces are polished to a mirror surface. As described in the problem, there are protrusions on the exposed surface of the pores and alumina particles in FIG. Therefore, high-precision smoothing of the surface is necessary. Therefore, in this embodiment, these substrates are targeted.

The ceramic polycrystalline body may be appropriately selected based on the intended relative dielectric constant and firing temperature, and alumina (Al ₂ O ₃ ), magnesia (MgO), forsterite (2MgO · SiO ₂ ), steatite ( MgO · _SiO 2), mullite _{(3Al 2 O 3 · 2SiO 2} ), beryllia (BeO), zirconia _(ZrO 2), aluminum nitride (AlN), silicon nitride _{(Si 3 N} 4), silicon carbide (SiC) is exemplified it can.

  Further, the glass ceramic body may be appropriately selected based on the intended relative dielectric constant and firing temperature, and is a substrate made of alumina (crystal phase) and silicon oxide (glass phase) obtained by firing at 1000 ° C. or less. Can be illustrated. In addition, magnesia, spinel, silica, mullite, forsterite, steatite, cordierite, strontium feldspar, quartz, zinc silicate, zirconia and the like can be used as ceramic components. As the glass component, borosilicate glass, lead borosilicate glass, borosilicate barium glass, strontium borosilicate glass, zinc borosilicate glass, potassium borosilicate glass, and the like can be used. Since it can be fired at 1000 ° C. or lower, Ag, Ag—Pd alloy, Au, Pt, and Cu can be used when wiring the internal conductor. Further, since the dielectric constant is lower than that of the alumina substrate, the signal delay is small. Furthermore, it has a feature that its thermal expansion coefficient is close to that of silicon, and direct die bonding and flip chip (FC) connection to the substrate is easy. As a result, the substrate is advantageous for downsizing the module. Since it is used as a substrate, the shape of the ceramic polycrystalline body or glass ceramic body is a plate. The glass component is preferably 60 to 80% by volume, and the ceramic component as an aggregate is preferably 40 to 20% by volume. This is because if the glass component is out of the above range, it is difficult to form a composite composition, and the strength and formability are reduced. By setting it within the above range, it is possible to significantly reduce defects due to grain boundaries and improve smoothness while ensuring substantially the same strength and formability as a ceramic substrate.

  At least one surface of the substrate is subjected to substrate grinding (lapping), and the baking warp generated in the substrate baking process is removed and planarized. After the substrate is planarized, a mirror surface (polishing) process is performed. The polishing process is preferably performed using CMP (Chemical Mechanical Polishing). At this stage, pores opened on the surface of the substrate and convex portions on the exposed surface of the ceramic particles are generated.

A coating layer is provided on said grinding | polishing surface. The coating layer is made of a metal oxide thin film. The metal oxide thin film is preferably the same as the substrate composition or has the substrate composition as a main component. Furthermore, in order to obtain high-precision smoothness of the surface, an amorphous material is more preferable. A SiO ₂ thin film is particularly preferable. A thin film in which alumina is contained in SiO ₂ may be used. Or you may suppress the generation | occurrence | production of the crack of a thin film electronic component by forming the metal oxide thin film which has a thermal expansion coefficient of the intermediate value of the thermal expansion coefficient of a board | substrate and a thin film electronic component. The film thickness of the metal oxide thin film is set to 0.1 μm or more and 20 μm or less in order to reduce unevenness on the substrate surface. If the film thickness of the metal oxide thin film is less than 0.1 μm, pores in the coating layer communicating with the pores of the substrate are likely to occur at the pores, and the steps of the convex portions on the exposed surface of the ceramic particles cannot be eliminated. Unevenness of the coating layer corresponding to the exposed surface of the particles occurs. On the other hand, when the thickness of the metal oxide thin film exceeds 20 μm, it is possible to sufficiently relieve the unevenness of the surface and suppress the internal pressure of the pore, but the coating layer is liable to crack and excessive film thickness. Is wasted. Furthermore, the surface roughness Ra (arithmetic average roughness) of the coating layer is 0.5 nm or more and 20 nm or less. Here, the surface roughness Ra is determined by a measuring device based on JIS B 0601. Ra of less than 0.5 nm is difficult because of the unevenness at the atomic level that constitutes the substrate. On the other hand, when Ra exceeds 20 nm, a thin film having a minute film thickness of about 40 to 100 nm may be formed by application of the thin film device technology, so that defects such as a short circuit are likely to occur.

  In this embodiment, the metal oxide thin film satisfies the film thickness condition of 0.1 μm or more and 20 μm or less, and the total opening area of pores opened on the surface of the metal oxide thin film is 150 ppm or less with respect to the surface area of the metal oxide thin film. It is also good. Typically, the total aperture area of the mirrored substrate pores occupies about 0.02 to 0.2% of the substrate surface. At this time, when a thin film electronic component such as a capacitor is formed, a short circuit occurs with a considerable probability. By making the total opening area of the pores opened at the surface of the metal oxide thin film 150 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less with respect to the surface area of the metal oxide thin film, the short-circuit rate is almost 0%, The leakage current density can be made equal to that in the case of forming a single crystal silicon substrate.

  In this embodiment, the metal oxide thin film satisfies the film thickness condition of 0.1 μm or more and 20 μm or less, and the number of coating layer pores opened on the surface of the metal oxide thin film is opened on the surface of the ceramic polycrystalline substrate or the glass ceramic substrate. It may be 30% or less of the number of substrate pores. If the number of pores is reduced to 30% or less, the total opening area of the pores opened on the surface of the metal oxide thin film becomes 150 ppm or less with respect to the surface area of the metal oxide thin film, and the pores are filled with the metal oxide thin film. Since the number is also reduced, the short-circuit rate is almost 0%, and the leakage current density can be made equal to that in the case of forming a single crystal silicon substrate. The number of coating layer pores can be determined by surface observation using a microscope, and the number of substrate pores can be determined by surface observation before forming the coating layer or after removing the coating layer.

  In this embodiment, several nanometers to several micrometers of a thin film electronic component substrate in which a coating layer having high-precision smoothness that satisfies the above-described conditions is provided on the surface of a substrate made of a ceramic polycrystalline body or a glass ceramic body. Thin film electronic components may be formed by applying thin film device technology for forming a thin film. FIG. 2 is a schematic cross-sectional view showing one embodiment of the thin film electronic component according to this embodiment. The thin film electronic component of FIG. 2 is provided with a coating layer 2 having high-precision smoothness made of a metal oxide thin film on the surface of a substrate 1 made of a ceramic polycrystalline body or glass ceramic body subjected to lapping and polishing. The lower electrode layer 3 is provided on the coating layer 2, the thin film dielectric layer 4 is provided on the lower electrode layer 3, and the upper electrode layer 5 is provided on the thin film dielectric layer 4.

  The lower electrode layer 3 and the upper electrode layer 5 are preferably formed of a material having low resistance. For example, a low resistance conductor such as Au, Ag, Ag—Pd, Pt, Cu, or an alloy thereof is formed in a thin film. It is a thing. The film thickness is not particularly limited, but is preferably set to 50 nm or more and 500 nm or less. An adhesion layer may be provided between the coating layer 2 and the lower electrode layer 3.

The thin film dielectric layer 4 is an insulating layer serving as a capacitor. Examples of such a high dielectric constant material include BST (barium strontium titanate), BaTiO ₃ , (Ba _x Ca _1-x ) TiO ₃ , ( _{Ba x Sr 1-x) TiO} 3, PbTiO 3, Pb (Zr x Ti 1-x) with a perovskite structure _3, such as (strong) or a dielectric _{material, Pb (Mg 1/3 Ni 2/3)} O Composite perovskite relaxor type ferroelectric materials represented by ₃ etc., bismuth layered compounds represented by Bi ₄ Ti ₃ O ₁₂ , SrBi ₂ Ta ₂ O ₉ , (Sr _x Ba _1-x ) Nb ₂ O ₆ A tungsten bronze type ferroelectric material represented by PbNbO ₆ or the like is used. Among these, ferroelectric materials having a perovskite structure such as BST, BaTiO ₃ and PZT are preferable because they have a high dielectric constant and can be easily synthesized at a relatively low temperature. The film thickness is not particularly limited, but is preferably set to 30 nm or more and 500 nm or less. If the film thickness is 30 nm or less, a sufficient relative dielectric constant may not be obtained, and the leakage current may exceed the allowable range. On the other hand, if the film thickness exceeds 500 nm, a sufficient capacitance value may not be obtained.

A protective layer such as TiO ₂ or polyimide may be provided on the upper electrode layer 5 for the purpose of electrode protection.

  By providing a coating layer made of a metal oxide thin film on the substrate surface, it may be possible to prevent the impurities contained in the substrate from diffusing into the electrode or the thin film dielectric. On the other hand, it may be possible to prevent impurities from diffusing from the electrode or the thin film dielectric to the substrate.

  Next, the manufacturing method of the board | substrate for thin film electronic components which concerns on this embodiment is demonstrated, referring FIGS. First, as shown in FIG. 3, a coating layer 11 is formed by applying a raw material liquid containing a raw material that becomes a metal oxide by heating on at least one surface of a substrate 10 made of a plate-like ceramic polycrystalline body or glass ceramic body. To do. Here, the raw material liquid is not particularly limited as long as it contains a raw material that becomes a metal oxide by heating. Examples of the raw material include metal alkoxides, metal alcoholates, organic metal acid salts, inorganic metal salts, metal trifluoroacetates, silica sols, alkyl silicates, inorganic siloxanes, and the like. Two or more kinds of raw materials may be mixed and used. As a raw material, it is preferable to use a raw material containing Si as a main component and forming a glass layer. If the viscosity is high, the film thickness exceeds the limit film thickness (that is, the film thickness at which cracks start to be generated by one application / heat treatment), and cracks occur in the coating layer. Therefore, it is preferable to add a solvent to the above raw material to obtain a raw material liquid whose viscosity has been adjusted. Here, the schematic diagram of the coating film once was shown in FIG. As shown in FIG. 8, when the coating layer 26 having a thickness of submicron to several microns is formed, the step 23 of the convex portion of the exposed surface of the ceramic particles 22 is relaxed and the raw material liquid is placed inside the pore 24 of the substrate 20. Penetrates. Therefore, by adjusting the viscosity and applying repeatedly until there are no irregularities on the substrate surface, it is possible to relieve the step of the convex part of the exposed surface of the ceramic particles and almost fill the pores of the substrate with high accuracy. It becomes possible to form a coating layer having smoothness. In this embodiment, for example, 2000 r. p. m. In the spin coating conditions, a raw material liquid having a viscosity of less than 3.94 mPa · s is preferable. Or 2000r. p. m. A raw material solution having a viscosity such that the film thickness of the coating layer is 800 nm or less, preferably 700 nm, and more preferably 550 nm or less under the conditions of spin coating with 1 coating. 2000r. p. m. There is no limitation on the lower limit of the coating layer thickness under the conditions of spin coating with 1 coating, but if the film thickness is too small, the number of coatings will increase and the manufacturing cost will increase. Is preferably 50 nm or more. There are no particular limitations on the raw material dilution solvent for imparting such viscosity as long as the raw material can be stably diluted, and a solvent having good wettability with respect to the substrate to be used is preferable. In addition, it is preferable to filter a raw material liquid using foreign material removal means, such as a syringe filter, before application | coating of a raw material liquid. Examples of the application of the raw material liquid include spin coating, dip coating, inkjet coating, and brush coating. Here, the coating layer is preferably formed by coating the raw material liquid once or a plurality of times. That is, it is preferable that the raw material liquid is repeatedly applied with a thickness not exceeding the limit film thickness, for example, about 5 to 10 times, and more preferably using a low-viscosity raw material liquid. FIG. 4 shows a case where the coating layers 11 and 12 are formed by two times of coating for easy illustration.

  In addition, you may enlarge a limit film thickness by adding additives, such as PVP (polyvinyl pyrrolidone), in a raw material liquid.

  Next, as shown in FIG. 5, the coating layers 11 and 12 are heated to form the metal oxide thin film layer 13. In the heating step, baking is performed at 500 ° C. or higher and lower than 1000 ° C., preferably 600 to 900 ° C. Before firing, the coating layer may be dried and calcined. The metal oxide thin film layer is densified by firing. The heating of the coating layer in the present embodiment is a concept including baking. If the firing is less than 500 ° C., the metal oxide thin film layer may not be densified or may be formed of a film in an intermediate reaction state that becomes a metal oxide. On the other hand, if the baking is performed at 1000 ° C. or higher, the glass ceramic substrate may be thermally deformed. When the coating layer is glass, it is difficult to confirm the boundary between the coating layers even by cross-sectional observation with an electron microscope.

  Next, as shown in FIG. 6, the coating layer 14 is formed by coating the raw material liquid on the surface of the metal oxide thin film layer 13. The raw material liquid and the coating method are the same as when the coating layers 11 and 12 are formed. Here, the coating layer is preferably formed by coating the raw material liquid once or a plurality of times. The coating layer 14 shown in FIG. 6 shows a case where the coating is performed twice for easy illustration (the boundary line between the first coating and the second coating is not shown). Next, as shown in FIG. 7, the coating layer 14 is heated to form a metal oxide thin film layer 15. This application and heating are repeated to deposit the metal oxide thin film layer. The firing temperature is preferably 500 ° C. or higher and lower than 1000 ° C. Finally, a metal oxide thin film 16 having a thickness of 0.1 μm or more and 20 μm or less is formed. In FIGS. 3 to 7, for convenience of understanding, each coating layer is illustrated separately for the purpose of understanding. However, when the metal oxide thin film 16 is formed using the same raw material liquid, the coating layer A clear boundary (for example, a boundary indicated by a dotted line in FIG. 7) by overpainting cannot always be identified. Through the above steps, a substrate for a thin film electronic component is manufactured.

  In forming the coating layer, as described above, there is a form in which the raw material liquid is applied once or a plurality of times. For example, a raw material liquid is applied to the surface of a substrate made of a ceramic polycrystalline body or a glass ceramic body several times, and then a metal oxide thin film layer is formed by heating, and further, the raw material liquid is applied several times and heated. By repeating the above, a metal oxide thin film having a desired thickness is formed. Furthermore, this embodiment includes the following forms. That is, a raw material liquid is applied once on the surface of a ceramic polycrystalline substrate or a glass ceramic substrate, and then a metal oxide thin film layer is formed by heating, and further, the raw material liquid is applied once and heated. May be formed into a metal oxide thin film having a desired film thickness. Furthermore, it is possible to combine heating by applying the raw material liquid once and heating by applying the raw material liquid a plurality of times.

  In the metal oxide thin film 16, the surface roughness Ra of the metal oxide thin film is 0.5 nm or more and 20 nm or less, or the total opening area of pores opened on the surface of the metal oxide thin film is the surface area of the metal oxide thin film. The number of coating layer pores opened at the surface of the metal oxide thin film is 150 ppm or less, or at least 30% or less of the number of substrate pores opened at the surface of the ceramic polycrystalline substrate or the glass ceramic substrate. It is preferable to form one so as to provide high-precision smoothness.

  Next, a method of manufacturing a thin film electronic component using the thin film electronic component substrate will be described with reference to FIG. On the metal oxide thin film, which is the coating layer 2 formed on the substrate 1, the lower electrode layer 3 is formed into a thin film by a vapor phase method such as a PVD method. PVD methods include resistance vapor deposition or vacuum deposition such as electron beam heating, DC sputtering, high frequency sputtering, magnetron sputtering, various sputtering methods such as ECR sputtering or ion beam sputtering, high frequency ion plating, activated vapor deposition, or arc. Examples include various ion plating methods such as ion plating, molecular beam epitaxy method, laser ablation method, ionized cluster beam evaporation method, and ion beam evaporation method.

The thin film dielectric layer 4 is formed using a solution coating and firing method such as a sol-gel method or a MOD method (organometallic compound deposition method), a PVD method such as a sputtering method, or a thin film device manufacturing technique such as a CVD method. According to these film forming methods, when a perovskite ferroelectric such as BaTiO ₃ or PZT is taken as an example, a normal ceramic powder sintering method requires a high temperature process of 900 to 1000 ° C. or more, but 400 to 400 ° C. It can be formed at a low temperature of about 850 ° C.

Next, the upper electrode layer 5 and the lower electrode layer 3 are formed on the thin film dielectric layer 4 by the vapor phase method such as the PVD method. A protective layer such as TiO ₂ or polyimide may be provided on the upper electrode layer 5 for the purpose of electrode protection.

  Examples of the present invention will be specifically described below.

Example 1
First, a smooth mirror surface substrate that has been lapped and polished is prepared for an Al ₂ O ₃ —SiO ₂ glass ceramic substrate. Next, a coating solution for forming a SiO ₂ coating film manufactured by Tokyo Ohka Kogyo Co., Ltd., trade name OCD T-7, is spin-coated on a glass ceramic substrate by changing the dilution factor (Mikasa Co., Ltd., 1H-D7). The coating layer was formed, and drying, calcination, and baking were performed to form a SiO ₂ coating layer. Here, the rotation speed in the spin coating is 2000 r.s. p. m. The drying temperature was 150 ° C., the calcining temperature was 500 ° C., and the firing temperature was 750 ° C. OCD T-7 was a methylsiloxane polymer methanol / propylene glycol / water, and the viscosity was 3.94 mPa · s.

Dilution of the coating solution for forming a SiO ₂ film was performed using butanol as a solvent. For OCD T-7, the dilution factor was 1 (ie, not diluted), 2 times, 3 times, or 4 times. The film thickness was an optical film thickness. FIG. 9 shows the relationship between the dilution ratio of OCD T-7 and the optical film thickness. OCD T-7 was 70 to 850 nm at a dilution factor of 1 to 4, and the film thickness decreased as the dilution factor increased. Here, when OCD T-7 was coated as it was (dilution rate was 1 and viscosity was 3.94 mPa · s), cracks occurred in the coating layer. No cracks occurred in the coating layers of other samples. 2000r. p. m. It is preferable to use a raw material solution having a viscosity such that the film thickness of the coating layer is 800 nm or less, preferably 700 nm or less, and more preferably 550 nm or less under the conditions of spin coating with 1 coating.

(Example 2)
For the alumina polycrystalline substrate, a smooth mirror surface substrate subjected to lapping and polishing is prepared. The surface roughness Ra of the alumina polycrystalline substrate was 35.7 nm. Here, the Ra type measuring device used a needle type surface shape measuring device Dektak 3 (manufactured by Nippon Vacuum Technology Co., Ltd.). Measurement conditions are shown in FIG. Hereinafter, the measurement of the surface roughness Ra performed in Example 2 was performed under these conditions. The raw material solution was a coating solution for forming a SiO ₂ film manufactured by Tokyo Ohka Kogyo Co., Ltd., trade name OCD T-2 (solute concentration 5.91 wt%, 1-fold dilution), OCD T-7 (solute concentration 15.98). Three types were prepared: weight%, 1-fold dilution) and OCD T-7 (1.5-fold dilution with butanol). OCD T-2 was ethyl silicate polymer ethanol / ethyl acetate, and the viscosity was 1.02 mPa · s. The rotation speed (r.p.m.) of the spin coat was 2000, 3000, 4000 or 5000. The film thickness of the SiO ₂ coating layer, the surface roughness Ra, and the presence or absence of cracks were evaluated when the process of forming the coating layer by one coating, drying the coating layer, calcining, and firing was performed. The film thickness was measured with an optical film thickness meter (manufactured by Filmetrics Co., Ltd.). The results are shown in Table 1.

  The following can be seen from the results in Table 1. OCD T-7 (concentration 15.98% by weight, 1-fold dilution) has high viscosity and high viscosity, and the coating layer thickness obtained by one application is too large, causing cracks. Even when the spin coat rotation speed was increased to reduce the film thickness, cracks occurred.

  On the other hand, OCD T-7 (1.5-fold dilution with butanol) is applied and heated once, butanol is added to the concentration and viscosity of OCD T-7 (concentration 15.98 wt%, 1-fold dilution). , So 2000-5000 r. p. m. Cracks did not occur in the coating layer obtained at any of the rotational speeds. The surface roughness Ra was 15.2 to 23.8 nm, and the smoothness was increased as compared with the surface roughness Ra 35.7 nm of the substrate. In addition, it turns out that surface roughness Ra is so small that the rotation speed of a spin coat is small. Next, the coating layer obtained by applying and heating OCD T-7 (diluted 1.5 times with butanol) twice did not cause cracks. The surface roughness Ra was 11.5 to 17.7 nm, and the smoothness was further increased compared to the case of the first coating. Even in the case of the second coating, it can be seen that the surface roughness Ra is smaller as the spin coating speed is smaller.

  Furthermore, OCD T-2 (concentration 5.91% by weight, 1-fold dilution) has a coating layer thickness smaller than that of OCD T-7 (1.5-fold dilution with butanol). p. m. Cracks did not occur in the coating layer obtained at any of the rotational speeds. The surface roughness Ra was 20.0 to 27.8 nm, and had smoothness almost equivalent to that of the coating layer obtained from OCD T-7 (diluted 1.5 times with butanol). Here too, it can be seen that the surface roughness Ra is smaller as the rotational speed of the spin coat is smaller. Next, the coating layer obtained by applying OCD T-2 twice (concentration 5.91% by weight, 1-fold dilution) was not cracked. The surface roughness Ra was 15.2 to 18.2 nm, and the smoothness was further increased than in the first coating. From the above, Ra was able to be further reduced by using a low-concentration raw material liquid and repeatedly applying and heat-treating it.

(Example 3)
Next, coating (once) and firing were repeated 5 times on the surface of the Al ₂ O ₃ —SiO ₂ glass ceramic substrate by using a raw material liquid in which OCD T-7 was diluted with butanol at a dilution ratio of 2 or 3 times, An SiO ₂ coating layer was formed and a smoothed glass ceramic substrate was obtained. A platinum lower electrode layer is formed on the SiO ₂ coating layer of this substrate by sputtering, a thin film dielectric layer made of BST is formed thereon, and a platinum upper electrode layer is further formed thereon, thereby forming a thin film electron I got the parts. The electrode diameter of the upper electrode was 0.1 mmφ. The electrical characteristics of this thin film electronic component were evaluated. Observation of the presence or absence of cracks in the coating layer and measurement of surface roughness Ra, short-circuit rate, capacity density C / A, leakage current density J and tand were performed. The surface roughness Ra is measured using a probe microscope (SPI3800N, manufactured by Seiko Instruments Inc.). The measurement conditions are deflection amount -1.0, I gain 0.5, P gain 0.1, A gain 0, The scanning area was 20 μm, and the scanning frequency was 1 Hz. The short-circuit rate was calculated based on the proportion of 10 upper electrodes arbitrarily selected that did not short-circuit with the lower electrode.

表２から、Ａｌ_２Ｏ_３−ＳｉＯ_２系ガラスセラミックス基板の上にコーティング層を設けずに形成した薄膜電子部品では、ショート率が７０％と高く、ショートしていないサンプルにおいてもリーク電流密度が大きい。一方、希釈倍率を２倍としてＳｉＯ_２コーティング層を形成したサンプルは、コーティング層にクラックが生じていた。ここで希釈倍率を２倍としてＳｉＯ_２コーティング層を形成したサンプルの場合、塗布（１回）・焼成を１回行なったときにはクラックは生じなかったが５回繰り返しを行なうとクラックが生じた。希釈倍率を３倍としてＳｉＯ_２コーティング層を形成したサンプルでは、コーティング層にクラックは生じておらず、ショート率は０％でリーク電流密度も高く、高電気特性を有していた。すなわち、シリコン単結晶基板状に形成した薄膜電子部品とほぼ同等の電気特性を有していた。以上のことから、濃度の薄い原料液をスピンコートして重ね塗りにより基板の上に金属酸化物薄膜からなるコーティング層を形成することで、基板のポアが塞がれると共にセラミックス粒子の露出表面での段差が緩和され、薄膜デバイス製造技術を適用しうる高精度の平滑性を有する薄膜電子部品用基板を提供できることがわかった。 For comparison, a thin film electronic component was directly formed on the surface of an Al ₂ O ₃ —SiO ₂ glass ceramic substrate without providing a coating layer, and the same evaluation was performed. Further, a thermal oxide film was formed on the surface of the silicon single crystal substrate, and a thin film electronic component was formed on the thermal oxide film as it was, and the same evaluation was performed. The results are shown in Table 2.

Table 2 shows that the thin film electronic component formed on the Al ₂ O ₃ —SiO ₂ glass ceramic substrate without providing the coating layer has a high short-circuit rate of 70%, and the leakage current density is high even in a sample that is not short-circuited. large. On the other hand, in the sample in which the SiO ₂ coating layer was formed with the dilution factor being 2 times, the coating layer was cracked. Here, in the case of the sample in which the SiO ₂ coating layer was formed with a dilution factor of 2 times, cracks did not occur when coating (one time) and firing were performed once, but cracks occurred when repeated five times. In the sample in which the SiO ₂ coating layer was formed with a dilution factor of 3 times, no crack was generated in the coating layer, the short-circuit rate was 0%, the leakage current density was high, and it had high electrical characteristics. In other words, it had substantially the same electrical characteristics as a thin film electronic component formed on a silicon single crystal substrate. From the above, by spin-coating a low-concentration raw material solution and forming a coating layer made of a metal oxide thin film on the substrate by overcoating, the pores of the substrate are blocked and the exposed surface of the ceramic particles Thus, it was found that a thin film electronic component substrate having high-precision smoothness to which the thin film device manufacturing technology can be applied can be provided.

Example 4
Next, when the coating to baking is performed five times and the coating layer made of SiO ₂ is provided on the Al ₂ O ₃ —SiO ₂ glass ceramic substrate, the total opening area of the pores opened on the substrate We evaluated how much the number of pores decreased. A raw material liquid in which OCD T-2 was diluted 1-fold, 1.5-fold or 2-fold, and a raw liquid in which OCD T-7 was diluted 2-fold or 3-fold were prepared. Spin coat rotation speed 2000r. p. m. The drying temperature was 150 ° C, the calcination temperature was 500 ° C, and the firing temperature was 750 ° C. The total opening area and the number of pores of the opened pores were measured using a laser microscope (VH2000, manufactured by Lasertec Corporation). The measurement visual field was 500 μm × 1000 μm. The ratio of the total opening area of the open pores to the surface area of the substrate was determined by dividing the total opening area of the pores before coating by the surface area of the substrate. Further, the ratio of the total opening area of the opened pores to the surface area of the substrate was determined by dividing the total opening area of the pores after coating by the surface area of the substrate. Three levels were measured for each, and the average was calculated. Furthermore, the pore area reduction rate was calculated by dividing the ratio of the average total opening area after coating by the ratio of the average total opening area before coating. In addition, the number of coating layer pores opened on the surface of the metal oxide thin film and the number of substrate pores opened on the surface of the substrate before forming the coating layer were each measured at three levels, and the average was calculated. Further, the pore number reduction rate was calculated by dividing the number of coating layer pores by the number of substrate pores. The results are shown in Table 3.

  The total opening area before coating varied depending on the substrate and was 163 to 966 ppm. As can be seen from the pore area reduction rate, the ratio of the total opening area of the pores was greatly reduced by forming the coating layer by performing the coating to firing five times. The substrate for a thin film electronic component according to this embodiment has a total opening area of pores opened on the surface of the metal oxide thin film of 150 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less with respect to the surface area of the metal oxide thin film. To do. The pore area reduction rate is 25% or less, preferably 15% or less. Moreover, the pore number is reduced by forming the coating layer, and the pore number reduction rate is 30% or less. When the dilution ratio is increased for both OCD T-2 and OCD T-7, the pore area reduction rate and the pore area reduction rate increase, that is, the pores cannot be reduced because the thickness of the resulting coating layer is small. This is because it cannot be completely filled. However, if the thickness of the coating layer is small, the number of repeated coatings can be increased when the coating layer is overcoated to form the desired thickness. We believe that it can be reduced as the layers are overcoated.

It is a section schematic diagram of the surface of a glass ceramics substrate. It is a schematic sectional drawing which shows one form of the thin film electronic component which concerns on this embodiment. It is the schematic which shows one form of the process of the manufacturing method of the board | substrate for thin film electronic components which concerns on this embodiment, Comprising: The case where an application layer (1st layer) is formed is shown. It is the schematic which shows 1 form of the process of the manufacturing method of the board | substrate for thin film electronic components which concerns on this embodiment, Comprising: The case where an application layer (2nd layer) is formed is shown. It is the schematic which shows one form of the process of the manufacturing method of the board | substrate for thin film electronic components which concerns on this embodiment, Comprising: The case where a coating layer (1st layer and 2nd layer) is heated and used as a metal oxide thin film layer Show. It is the schematic which shows one form of the process of the manufacturing method of the board | substrate for thin film electronic components which concerns on this embodiment, Comprising: The case where a coating layer (3rd layer and 4th layer) is formed on a metal oxide thin film is shown. . It is the schematic which shows 1 form of the process of the manufacturing method of the board | substrate for thin film electronic components which concerns on this embodiment, Comprising: The case where a coating layer (3rd layer and 4th layer) is heated and used as a metal oxide thin film layer Show. The schematic diagram of a coating film once is shown, and the case where the coating layer 26 with a thin film thickness is formed is shown. It is a diagram showing the relationship between dilution and the optical thickness of the raw material solution when forming the metal oxide thin film using SiO ₂ film-forming coating liquid (OCD T-7). The measurement conditions of the surface roughness Ra of the needle type surface shape measuring instrument Dektak 3 are shown.

Explanation of symbols

1, 10, 20, glass ceramic substrates 2, 16, 26, metal oxide thin film 3, lower electrode layer 4, thin film dielectric layer 5, upper electrode layer 11, first coating layer 12, second coating layer 14 , Third and fourth coating layers 13, first metal oxide thin film layer 15, second metal oxide thin film layer 22, ceramic particles 23, step 24 due to the convex portion of the exposed surface of the ceramic particles, pore (substrate portion)

Claims (5)

At least one surface of a plate-like ceramic polycrystalline body or glass ceramic body is ground and flattened, and then subjected to a mirror surface treatment by CMP (Chemical Mechanical Polishing) to obtain a smooth mirror surface substrate. On the polished surface, a coating layer is formed by applying a raw material liquid containing a raw material that becomes a metal oxide by heating, a metal oxide thin film layer is formed by heating the coating layer, and on the surface of the metal oxide thin film layer, Formation of a coating layer by application of the raw material liquid, and then formation of a metal oxide thin film layer by heating the coating layer at least once, thereby laminating the metal oxide thin film layer to a film thickness of 0.1 μm or more and 20 μm or less the coating layer is formed of a metal oxide thin film, the metal oxide thin film, the surface roughness Ra of the metal oxide thin film 0.5nm or more 2 nm or less, or the total opening area of pores opened on the surface of the metal oxide thin film is 150 ppm or less relative to the surface area of the metal oxide thin film, or opened on the surface of the metal oxide thin film A method of manufacturing a substrate for a thin film electronic component , wherein at least one of the number of coating layer pores is 30% or less of the number of substrate pores opened on the surface of the substrate . Method of manufacturing the thin-film substrate for electronic devices according to claim 1, characterized by forming the coating layer by applying one or more times the material solution. Claim 1 or 2 thin film electronic component manufacturing method of the substrate, wherein the said calcination temperature of the coating layer is less than 500 ° C. or higher 1000 ° C.. As the raw material, according to claim 1, 2 or 3 thin film electronic component manufacturing method of a substrate wherein the use of raw materials mainly composed of Si. A lower electrode layer is provided on the coating layer made of a metal oxide thin film provided on the thin film electronic component substrate according to claim 1, 2, 3 or 4 , and a thin film dielectric layer is provided on the lower electrode layer, A method of manufacturing a thin film electronic component, comprising providing an upper electrode layer on the thin film dielectric layer.

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