JP3645808B2 - Thin-film electronic component, its manufacturing method and substrate - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a thin film electronic component, for example, a high frequency thin film electronic component suitably used for a thin film capacitor, a manufacturing method thereof, and a substrate.
[0002]
[Prior art]
In recent years, with the downsizing and high functionality of electronic devices, there has been an increasing demand for downsizing, thinning, and high frequency compatibility for electronic components installed in electronic devices.
[0003]
In particular, in a high-speed digital circuit of a computer that needs to process a large amount of information at high speed, even at the personal computer level, the clock frequency in the CPU chip is 200 MHz to 1 GHz, the clock frequency of the inter-chip bus is 75 MHz to 133 MHz, and so on. The speedup is remarkable.
[0004]
As the degree of integration of LSIs increases and the number of elements in a chip increases, the power supply voltage tends to decrease in order to reduce power consumption. As these IC circuits increase in speed, density, and voltage, passive components such as capacitors have become essential to exhibit excellent characteristics for high-frequency or high-speed pulses in conjunction with downsizing and large capacity. Yes. In order to reduce the size and increase the capacity of the capacitor, it is effective to reduce the thickness of the dielectric layer and the electrode pattern, and various thin film capacitors have been proposed.
[0005]
As an adverse effect of thinning the dielectric layer, there is a concern about deterioration of insulation characteristics. Various techniques have been proposed to improve the insulation characteristics of these thin-film electronic components. For example, JP-A-7-183165 and JP-A-8-31951 disclose examples in which the microstructure of the insulator layer is improved and the leak characteristics of the insulator layer itself are improved. Japanese Patent Application Laid-Open No. 9-199373 discloses an example in which an air bridge structure is employed in which the upper electrode does not cover the end portion of the insulator layer to improve the insulation deterioration at the end portion of the insulator layer. .
[0006]
As the thin film capacitor, for example, as shown in FIG. 7, a plurality of thin film elements A having an insulating layer 43 (dielectric thin film), a lower electrode 45, and an upper electrode 47 are provided on a support substrate 41. It is conceivable that the insulator layer 43 is sandwiched between the electrodes 45 and 47 to form the thin film element A (capacitance element).
[0007]
The thin film element A is covered with an insulating protective film 49, and the insulating protective film 49 has a through hole 51 in which the upper electrode 47 is exposed on the bottom surface. In the through hole 51, an external terminal 55 made of a solder bump is formed via a solder barrier layer 53. In this thin film capacitor, the upper electrode 47 is annularly removed around the through hole 51 (indicated by x) to prevent conduction with the lower electrode 45, and a part of the upper electrode 47 is divided.
[0008]
In such a thin film capacitor, a lower electrode is formed on a supporting substrate using a vapor phase synthesis method such as a sputtering method or a CVD method, and a pattern processing is performed using a photolithography technique. An insulator layer is formed on the lower electrode by a vapor phase synthesis method or a sol-gel method, and a pattern process is performed using photolithography. An upper electrode is formed on the patterned insulator layer, and photolithography is performed. A step of performing pattern processing using a technique, a step of forming an insulating protective film on the upper electrode, a through hole is formed in the insulating protective film, and a lower electrode and an upper electrode are formed in the through hole. Each is manufactured through a step of forming external terminals that are electrically connected to each other.
[0009]
[Problems to be solved by the invention]
However, when a thin film electronic component is manufactured by the process as described above, after forming the upper electrode on the insulator layer, the excess upper electrode is patterned so that the upper electrode is not electrically connected to the lower electrode. As a result, an etching residue of the upper electrode is generated on the insulator layer, a surface leakage current is generated due to the etching residue on the insulator layer, and the insulating characteristics of the thin film electronic component are deteriorated. It was.
[0010]
An object of the present invention is to provide a small-sized thin-film electronic component having a high capacity and high insulation, a method for manufacturing the same, and a substrate.
[0011]
[Means for Solving the Problems]
The thin film electronic component of the present invention is provided with a thin film element in which an electrode is formed on an insulator layer on a support substrate, and the thin film element is covered with an insulating protective film. A thin-film electronic component formed by forming a through hole in which an external terminal electrically connected to the electrode is provided , and an annular insulating dam portion that divides the electrode on the insulator layer around the through hole Is formed. An annular raised portion is formed in the insulating protective film around the through hole.
[0013]
In such a thin film electronic component, a step of sequentially laminating a lower electrode and an insulator layer on a support substrate, and a first through hole and a second through hole in which the lower electrode is exposed in the insulator layer are formed. A step of forming an annular first insulating protective film on the surface of the insulator layer around the first through-hole, and the step of forming the first through-hole and the second through-hole on the insulator layer Forming an upper electrode on the inner surface; forming a second insulating protective film on the upper surface of the upper electrode and the first insulating protective film; and the first through-holes in the second insulating protective film; And a step of forming a through hole in which an external terminal electrically connected to the upper electrode is provided at a position where the second through hole is formed.
[0014]
The upper electrode is formed directly on the processed insulator layer by sputtering, and a part of the upper electrode on the insulator layer is removed by etching using a photoresist and formed on the same surface on the insulator layer. However, in the present invention, a portion from which a part of the upper electrode is removed, that is, the lower side, is prevented from being electrically connected between the electrodes having different polarities (between the upper electrode and the lower electrode). An annular first insulating protective film is formed in advance around a through hole (first through hole) for an external terminal that is electrically connected to the electrode, and then an upper electrode is formed on the insulator layer. Further, only the upper electrode on the first insulating protective film is etched so that the upper electrode is formed only on the inner surfaces of the first through hole and the second through hole. There is no need to etch parts (between electrodes of different polarity) And can reliably be insulated, it is possible to reduce the occurrence of surface leak current between electrodes of different polarities due to etching residues, insulation failure can be prevented due to this.
[0015]
The film thickness of the first insulating protective film is desirably thicker than that of the upper electrode. By making the film thickness of the first insulating protective film larger than that of the upper electrode, the height of the barrier between the electrodes is increased, and the occurrence of surface leakage current between electrodes of different polarities can be prevented.
[0016]
Thus, by making the film thickness of the first insulating protective film thicker than that of the upper electrode, an annular ridge is formed in the insulating protective film around the external terminal electrically connected to the lower electrode. It will be.
[0017]
It is desirable that the height of the annular raised portion or insulating dam portion formed on the insulating protective film is 2 μm or more. This is because the difference in height between the upper electrode and the first insulating protective film is large, and the electrodes having different polarities can be reliably insulated by the first insulating protective film, and the surface between the electrodes having different polarities can be obtained. Generation of leakage current can be prevented more reliably. Such a raised portion can be obtained by making the thickness of the first insulating protective film (insulating dam portion) 2 μm or more thicker than the upper electrode.
[0018]
Further, in the thin film electronic component of the present invention, since the external terminals made of solder bumps are formed in the insulator layer non-formation region, even if an external terminal that is very large relative to the thickness of the insulator layer contracts during reflow, reflow The insulator layer is not directly damaged by the stress caused by the thermal contraction of the external terminals that occur in the process, so that excessive stress is not generated in the insulator layer and cracks in the insulator layer can be prevented. In addition, solder does not flow into the crack, thereby ensuring insulation, maintaining device characteristics, and ensuring mounting reliability.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a thin film electronic component comprising a thin film capacitor of the present invention. This thin film capacitor has an insulating layer 3 (dielectric thin film), a lower electrode 5 and an upper electrode 7 on a support substrate 1. A plurality of thin film elements A are provided. The electrodes 5 and 7 are made of Au, and the insulator layer 3 is sandwiched between the electrodes 5 and 7 to form a thin film element A (capacitance element).
[0020]
The thin film element A is covered with an insulating protective film 9, and the insulating protective film 9 has a through-hole 11 in which the lower electrode 5 or the upper electrode 7 is exposed on the bottom surface. In the through hole 11, external terminals 15 a and 15 b made of solder bumps are formed so as to protrude through the solder barrier layer 13.
[0021]
The insulator layer 3 constituting the dielectric thin film of the thin film capacitor may be a dielectric made of a perovskite type oxide crystal having a high relative dielectric constant in a high frequency region. For example, Pb (Mg, Nb) O ₃ type, Pb (Mg) , Nb) O ₃ —PbTiO ₃ system, Pb (Zr, Ti) O ₃ system, Pb (Mg, Nb) O ₃ —Pb (Zr, Ti) O ₃ system, (Pb, La) ZrTiO ₃ system, BaTiO ₃ It may be a system, (Sr, Ba) TiO ₃ system, or a compound in which other additives are added or substituted thereto, and is not particularly limited.
[0022]
The film thickness of the insulator layer 3 is preferably 0.3 to 1.0 μm in order to ensure high capacity and insulation. This is because when the thickness is smaller than 0.3 μm, the covering property may be lowered and the insulating property may be lowered. When the thickness is larger than 1.0 μm, the capacity tends to be smaller. The film thickness of the insulator layer 3 is preferably 0.4 to 0.8 μm.
[0023]
The film thickness of the electrodes 5 and 7 made of Au is preferably 0.3 to 0.5 μm in consideration of impedance in the high frequency region and film coverage. This is because when the thickness of the electrodes 5 and 7 is thinner than 0.3 μm, there is a possibility that a portion that is not partially covered may occur, and when it is thicker than 0.5 μm, the skin of the conductor in the high frequency region. This is because the resistance of the conductor layer hardly changes in consideration of the effect.
[0024]
The support substrate 1 is not particularly limited as it is selected from alumina, sapphire, aluminum nitride, MgO single crystal, SrTiO ₃ single crystal, surface silicon oxide, glass, quartz and the like.
[0025]
The insulating protective film 9 is made of, for example, Si ₃ N ₄ , SiO ₂ , polyimide resin, BCB (benzocyclobutene), or the like.
[0026]
The solder barrier layer 13 is made of any one of Ti, Cr, Ni, Cu, Pd, Pt, and an alloy of two or more selected from these metals, and can be formed by sputtering, vapor deposition, plating, or the like. good. The thickness of the solder barrier layer 13 may be 0.3 μm or more in order to exhibit a function as a solder barrier.
[0027]
The lower electrode 5 is annularly etched so as to surround the external terminal 15b, and is divided into a lower electrode 5a that forms a capacitor and a lower electrode 5b that does not form a capacitor and is connected to the upper electrode 7. . Further, the upper electrode 7 has a portion which is not formed in an annular shape so as to surround the external terminal 15a on the insulator layer 3, and the upper electrode 7a which forms a capacitance, and the lower electrode 5a which does not form a capacitance. Is divided into upper electrodes 7b connected to each other. An insulating dam portion 16 is formed between the upper electrode 7a and the upper electrode 7b. The thin film element A is configured by sandwiching the insulator layer 3 between a lower electrode 5a and an upper electrode 7a. As shown in FIGS. 1 and 2, a ring-shaped raised portion 17 is formed on the insulating protective film 9 around the external terminal 15a (through hole 11) electrically connected to the lower electrode 5a. Yes. The shape of the raised portion 17 may be an annular shape, and is not particularly limited to a circular shape, a square shape, or the like. Further, the insulator layer 3 is a portion where the lower electrode (including the metal layer 5b) 5 and the upper electrode (including the metal layer 7b) 7 are annularly etched on the entire surface except the insulator layer non-forming region B. It is formed on the entire surface except for.
[0028]
The height h of the raised portion 17 is preferably 2 μm or more. This is because the height of the barrier between electrodes of different polarities can be made sufficiently high, so that the occurrence of surface leakage current can be reliably prevented.
[0029]
In such a thin film electronic component, for example, first, as shown in FIG. 3A, the lower electrode 5 is formed on the support substrate 1 by sputtering, and as shown in FIG. The lower electrode 5 is patterned using a technique, and a portion corresponding to the periphery of the external terminal 15b connected to the upper electrode 7 is annularly removed to form the lower electrodes 5a and 5b.
[0030]
Next, as shown in FIG. 3C, a coating solution synthesized by, for example, a sol-gel method is applied to the entire surface, dried, and then heat-treated and baked to form the insulator layer 3. As shown in FIG. 3D, the insulator layer 3 is processed using the photolithography technique so that the lower electrode 5 is exposed, and the lower electrode 5 is formed on the insulator layer 3. The 1st through-hole 21 and the 2nd through-hole 23 which are exposed are formed.
[0031]
Then, as shown in FIG. 3E, for example, photosensitive BCB resin is formed around the surface of the insulating layer 3 around the first through hole 21, that is, around the external terminal 15a connected to the lower electrode 5a. Is applied to form an annular first insulating protective film 25. The annular first insulating protective film 25 can be formed by applying BCB resin to the entire surface, exposing and developing, and becomes the insulating dam portion 16.
[0032]
Next, the upper electrode 7 is formed on the surface of the first insulating protective film 25, the surface of the insulator layer 3, and the inner surfaces of the first through hole 21 and the second through hole 23, and the upper side of the surface of the first insulating protective film 25. The electrode 7 is removed using a photolithography technique to form upper electrodes 7a and 7b as shown in FIG.
[0033]
Thereafter, as shown in FIG. 3G, for example, a photosensitive BCB resin is applied to the upper surfaces of the upper electrode 7 and the first insulating protective film 25 to form the second insulating protective film 9. As a result, the second insulating protective film 9 is raised at the portion where the first insulating protective film 25 is formed, and the raised portion 17 is formed. The first insulating protective film 25 and the second insulating protective film 9 are integrated.
[0034]
Thereafter, as shown in FIG. 3 (h), the through hole 11 in which the upper electrode 7 is exposed by exposure and development at the position where the first through hole 21 and the second through hole 23 are formed in the second insulating protective film 9. As shown in FIG. 3 (i), for example, a solder barrier layer 13 is formed on the inner surface of the through-hole 11 by vapor deposition, and eutectic solder paste is printed using screen printing, for example. The thin film capacitor of the present invention is manufactured by forming external terminals 15a and 15b made of solder bumps.
[0035]
As shown in FIG. 4, the substrate of the present invention is configured by connecting the external terminal 15 of the thin film electronic component 30 configured as described above to an electrode 33 formed on the surface of a base 31 made of an insulating material. Has been.
[0036]
In the above example, the example in which the present invention is applied to a thin film capacitor has been described. However, the present invention is not limited to the above example, and for example, a thin film inductor, a thin film LC filter, a thin film resistor, a thin film RC filter, The thin film capacitor, thin film inductor, thin film LC filter, thin film resistor, and thin film RC filter may be applied to a thin film composite component.
[0037]
In the above example, a single plate type in which one insulator layer is sandwiched between electrodes is shown, but a multilayer thin film capacitor in which a plurality of insulator layers and electrodes are alternately stacked may be used.
[0038]
Furthermore, in the thin film electronic component of the present invention, the example in which the external terminals 15a and 15b made of solder bumps are provided in the through hole 11 of the protective film 9 has been described. However, the present invention is not limited to the above example, and Can be changed without changing
[0039]
For example, when solder bumps are not formed, as shown in FIG. 5, the solder barrier layer 13 formed in the through hole 11 of the protective film 9 serves as an external terminal. Since FIG. 5 is the same as FIG. 1 except that an external terminal made of a solder bump is not provided, the same reference numeral is assigned.
[0040]
In this case, the surface electrode of the mother board and the solder barrier layer 13 are connected by the conductive member at the stage of mounting on the mother board. Examples of the conductive member include a bump shape, a foil shape, a plate shape, a wire, and a paste shape. The conductive member is not particularly limited, and a plurality of shapes may be combined. Moreover, there are materials such as Pb, Sn, Au, Cu, Pt, Pd, Ag, Al, Ni, Bi, In, Sb, and Zn, and any material may be used as long as it is conductive. good. A conductive resin may be used.
[0041]
When the solder barrier layer 13 is not formed, or when a solder adhesion layer is formed on the upper surface of the solder barrier layer 13, the layer exposed in the through hole of the protective film 9 becomes an external terminal.
[0042]
【Example】
The electrodes and the solder barrier layer were formed by a high-frequency magnetron sputtering method, and the insulator layer was formed by a sol-gel method.
[0043]
First, a 3 nm adhesion layer made of Ti was formed on a support substrate made of alumina, and a 0.3 μm Au layer was formed on the upper surface of the adhesion layer to form a lower electrode made of the adhesion layer and the Au layer.
[0044]
The lower electrode was patterned using photolithography technology. A Pb (Mg _1/3 Nb _2/3 ) O ₃ —PbTiO ₃ —PbZrO ₃ coating solution synthesized by a sol-gel method is applied to the processed lower electrode using a spin coating method and dried. Heat treatment was performed at 380 ° C. and firing was performed at 815 ° C. to form an insulator layer made of Pb (Mg _1/3 Nb _2/3 ) O ₃ —PbTiO ₃ —PbZrO ₃ having a thickness of 0.7 μm. Thereafter, the insulator layer was processed using a photolithography technique so that the lower electrode was exposed to form the first through hole and the second through hole.
[0045]
Next, a photosensitive BCB resin is applied and formed on the insulator layer, processed with a negative pattern that exposes the formation portion of the upper electrode, and a first insulating protective film (insulating dam portion) having a thickness of 2 μm is formed. Formed.
[0046]
Next, an adhesion layer made of Ti with a thickness of 30 nm and an Au layer with a thickness of 0.3 μm are formed on the surface of the insulator layer, the surface of the first insulating protective film, the inner surfaces of the first through hole and the second through hole. The Au layer and the Ti layer on the surface of the first insulating protective film were removed using a photolithography technique to form an upper electrode.
[0047]
Thereafter, a photosensitive BCB is again applied to the entire surface, exposed and developed, and a second insulating protective film having a through hole having a diameter of about 100 μm and a depth of 1 μm is exposed so that the Au layer of the upper electrode is exposed. Formed. At this time, an annular ridge having a height h of 2 μm was formed in the thin film capacitor.
[0048]
A solder barrier layer having a thickness of 1.5 μm is formed on the second insulating protective film and in the through hole, and thereafter, a solder adhesion layer Au having a thickness of 0.1 μm is formed, and the inner wall surface of the through hole, and The periphery of the through hole on the surface of the protective film was processed using photolithography into a shape having a diameter of 120 μm around the through hole.
[0049]
Finally, eutectic solder paste composed of 63% by weight of Pb and 37% by weight of Sn is transferred onto the solder adhesion layer using screen printing, and reflow is performed to form external terminals composed of solder bumps. A thin film capacitor as shown in FIG.
[0050]
The effective electrode area of the obtained thin film capacitor was 1.4 mm ² , and the capacitance at a frequency of 1 kHz was about 40 nF.
[0051]
As a comparative example, as shown in FIG. 7, the first insulating protective film was not formed, and a thin film capacitor in which electrodes having different polarities were separated by etching a part of the upper electrode was manufactured. This thin film capacitor did not have an annular ridge.
[0052]
In order to compare the difference in structure between the two, the relationship between leakage current and electric field strength in the atmosphere (room temperature and humidity 60%) was evaluated. The result is shown in FIG.
[0053]
According to FIG. 6, the electric field strength of the thin film capacitor of the present invention is broken at about 100 V / μm, whereas the thin film capacitor of the comparative example is at most as low as 50 V / μm and has a large variation. Thus, it can be seen that the thin film capacitor of the present invention can ensure high insulation.
[0054]
Further, when a thin film capacitor was produced in the same manner as described above except that the thickness of the first insulating protective film was 3 μm, it had a high breakdown voltage strength as described above.
[0055]
【The invention's effect】
As described above in detail, according to the present invention, the annular first insulating protective film (insulating dam portion) is formed in advance around the through hole for the external terminal that is electrically connected to the lower electrode. Thereafter, only the upper electrode on the first insulating protective film is etched so that the upper electrode is formed only on the insulator layer forming the passive element and on the inner surfaces of the first through hole and the second through hole. Because it is processed, it is not necessary to etch part of the upper electrode on the insulator layer (between electrodes of different polarities), it is possible to reliably insulate between electrodes of different polarities, Generation of surface leakage current between the electrodes can be prevented, and insulation failure caused by this can be prevented.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a thin film electronic component of the present invention.
2 is a plan view of FIG. 1. FIG.
FIG. 3 is a process diagram for explaining a method of manufacturing a thin film electronic component of the present invention.
FIG. 4 is a cross-sectional view showing a substrate of the present invention.
FIG. 5 is a cross-sectional view showing a thin film electronic component of the present invention when a solder barrier layer serves as an external terminal.
FIG. 6 is a graph showing the relationship between leakage current and breakdown voltage.
FIG. 7 is a cross-sectional view showing a thin film electronic component.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Support substrate 3 ... Insulator layer 5, 7, ... Electrode 9 ... 2nd insulating protective film 11 ... Through-hole 15 ... External terminal 17 ... Raised part 16 ... · Insulation dam portion 21 ··· first through hole 23 ··· second through hole 25 ··· first insulating protective film 30 ··· thin film capacitor 31 ··· substrate A · · · thin film element

Claims (7)

A thin film element in which an electrode is formed on an insulator layer is provided on a support substrate, and the thin film element is covered with an insulating protective film, and is electrically connected to the insulating protective film with the electrode. A thin-film electronic component formed with a through hole in which an external terminal is provided, wherein an annular insulating dam portion for dividing the electrode is formed on the insulator layer around the through hole. Thin film electronic components. 2. The thin film electronic component according to claim 1 , wherein an annular raised portion is formed in the insulating protective film around the through hole . 3. The thin-film electronic component according to claim 1, wherein an external terminal electrically connected to the electrode is formed in the through hole, and the external terminal protrudes from the insulating protective film. Thin film electronic component according to claim 2, wherein the height of the raised portion is 2μm or more. A step of sequentially laminating a lower electrode and an insulator layer on a support substrate, a step of forming a first through hole and a second through hole in which the lower electrode is exposed in the insulator layer, and the first through hole Forming an annular first insulating protective film on the surface of the insulator layer around a hole; and forming an upper electrode on the insulator layer and on the inner surfaces of the first and second through holes. A step of forming a second insulating protective film on the upper surface of the upper electrode and the first insulating protective film, and a position where the first through hole and the second through hole are formed in the second insulating protective film. And a step of forming a through-hole in which an external terminal electrically connected to the upper electrode is provided. 6. The method of manufacturing a thin film electronic component according to claim 5, wherein the thickness of the first insulating protective film is thicker than that of the upper electrode. 5. A substrate comprising the thin film electronic component according to claim 1 provided on a surface of a base made of an insulating material.

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