JP2010225849A - Thin film capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin film capacitor that does not absorb moisture in a peripheral environment, and has excellent reliability, and has improved moisture resistance. <P>SOLUTION: A capacitor portion 8 has a first electrode film 4 formed on a lower surface of a dielectric thin film 5, a second electrode film 6 formed on an upper surface of the dielectric thin film 5, and an insulator thin film 7 made of the same material as the dielectric thin film 5 and formed on an upper surface of the second electrode film 6. The capacitor portion 8, a tight-contact layer 3, and an oxide layer 1 made of SiO2 are coated with two layers of insulating films 9, i.e. an inorganic protective film 10 and an organic protective film 11. First and second lead-out electrodes 12 and 13 are electrically insulated from each other, and penetrate the protective film 10 to be electrically connected to the first and second electrode films 4 and 6. Then a part except external connection electrodes 14 and 15 is coated with an inorganic protective film 16, which is coated with an organic protective film 17. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a thin film capacitor, and more particularly to a thin film capacitor formed on a substrate and connected to an external electronic component such as a large scale integrated circuit element (LSI).

  In recent years, various electronic components such as LSIs have been increased in density and the operating speed has been increasing.

  When the operation speed of the electronic component increases as described above, voltage noise and voltage fluctuation are likely to occur due to the switching operation of the electronic circuit.

  Therefore, conventionally, thin film capacitors have been widely used for the purpose of suppressing the occurrence of signal errors due to these voltage noises and voltage fluctuations.

  For example, in Patent Document 1, in a thin film capacitor having a dielectric layer made of a metal oxide and a protective insulating layer made of a resin material, a non-conductive inorganic substance is interposed between the capacitor and the protective insulating layer. A thin film capacitor provided with a barrier layer made of a material has been proposed.

  Specifically, in the thin film capacitor of Patent Document 1, a capacitor in which first and second electrode layers 102 and 103 are formed on both upper and lower surfaces of a dielectric layer 101 is provided on a substrate 104 as shown in FIG. At the same time, the first electrode layer 102 is connected to the first bump 108 via the first extraction electrode 107, and the second electrode layer 103 is connected to the second bump 106 via the second extraction electrode 105. Has been. The capacitor is covered with an inorganic protective film (barrier layer) 109 formed of silicon nitride or the like and an organic resin film (protective insulating layer) 110 formed of polyimide resin or the like.

  That is, in Patent Document 1, mechanical stress from the first and second bumps 106 and 108 is absorbed by the organic resin film 110, and moisture released from the organic resin film 110 reaches the dielectric layer 101. This is blocked by the inorganic protective film 109, thereby ensuring the shock resistance and moisture resistance of the capacitor.

  Further, Patent Document 2 includes a substrate, a capacitor portion formed on the substrate, including at least two electrode layers and at least one dielectric thin film, and formed to cover the capacitor portion. And a lead conductor that penetrates the protective layer and connects to one of the electrode layers of the capacitor unit, and the lead conductor is at least an adhesion layer in order from the side in contact with the electrode layer. And an under bump metal layer, wherein the adhesion layer is thinner than the under conductor layer and the under bump metal layer, and an outer peripheral edge of the under bump metal layer is shifted from an outer peripheral edge of the under bump metal layer. In addition, a thin film capacitor is proposed in which the outer peripheral edge of the adhesion layer is formed to extend to the outer side of the outer peripheral edges of the base conductor layer and the under bump metal layer.

  Specifically, as shown in FIG. 5, Patent Document 2 includes a first electrode layer 113, a dielectric thin film 114, and a second electrode layer 115 on an adhesion layer 112 formed on the surface of a substrate 111. A capacitor portion 116 is formed, and a diffusion suppression layer 117 is formed on the capacitor portion 116. The first electrode layer 113 is electrically connected to the first under bump metal layer (first lead electrode) 120 through the adhesion layer 118 and the underlying conductor layer 119, and the first under bump metal. The layer 120 is electrically connected to the first bump 121. The second electrode layer 115 is electrically connected to the second under bump metal layer (second lead electrode) 124 through the adhesion layer 122 and the underlying conductor layer 123, and the second under bump metal layer. 124 is electrically connected to the second bump 125.

  The capacitor part 116 is covered with an inorganic protective film 126 and an organic protective film 127, and the organic protective film 127 is further covered with an organic resin film 128. The organic resin film 128 has a function as a solder resist, and when the external electronic component is solder-connected to the first and second bumps 120 and 125, the solder is outside the first and second bumps 120 and 125. The flow is stopped.

JP 2004-214589 A JP 2007-81325 A

  However, in each of Patent Documents 1 and 2, the outermost layer is covered with an organic resin film, that is, organic resin films 110 and 128, and therefore, these organic resin films 110 and 128 are exposed to the surrounding environment. . For this reason, when the organic resin films 110, 127, and 128 absorb moisture from the surrounding environment and expand, stress may be generated. Due to this stress, the first extraction electrodes 105 and 120 and the second extraction electrodes 107 and 124 are peeled off from the inorganic protective films 109 and 126 and the organic protective films 110 and 127. As a result, the extraction electrodes 105, There is a possibility that moisture may permeate from the interfaces between the protective films 107, 120, and 124 and the inorganic or organic protective films 109, 126, 110, and 127 to deteriorate the characteristics of the thin film capacitor.

  Moreover, since the extraction electrode is also exposed to the surrounding environment (Patent Document 1) or is covered with an organic resin film (Patent Document 2), the moisture absorbed from the surrounding environment causes electrode corrosion and interface deterioration, resulting in a thin film capacitor. There is a risk of deteriorating the characteristics.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a thin film capacitor with improved moisture resistance having good reliability without absorbing moisture in the surrounding environment.

  In order to achieve the above object, a thin film capacitor according to the present invention includes a capacitor portion having at least one capacitance generating portion in which electrode films are formed on both upper and lower surfaces of a dielectric thin film, and an outer surface formed of an organic material. And at least one insulating protective film covering the capacitor portion and electrically connected to one of the electrode films that penetrate the insulating protective film and constitute the capacitance generating portion The other electrode film is provided with a pair of extraction electrodes electrically insulated, and the extraction electrode is characterized in that a portion excluding a connection portion with an external electronic component is covered with an inorganic protective film.

  The thin film capacitor of the present invention is characterized in that the inorganic protective film is covered with an organic protective film.

  Furthermore, the thin film capacitor of the present invention is characterized in that the capacitor portion is formed with an insulator thin film made of the same material as the dielectric thin film on the upper surface of the uppermost electrode film.

  According to the thin film capacitor, at least one capacitor generating portion having electrode films formed on both upper and lower surfaces of the dielectric thin film, and at least an outer surface formed of an organic material covering the capacitor portion. One or more insulating protective films, and electrically connected to one electrode film of the electrode films that penetrate the insulating protective film and constitute the capacitance generating portion and electrically connect to the other electrode film A pair of insulated extraction electrodes, and the extraction electrode is covered with an inorganic protective film except for a portion connected to an external electronic component, so that a protective film whose outer surface is formed of an organic material There is no exposure to the environment. Therefore, it is possible to avoid the occurrence of stress due to moisture absorption and expansion of the organic insulating film, and it is possible to prevent the extraction electrode from peeling from the insulating film.

  And since moisture resistance improves in this way, it can suppress effectively that a water | moisture content permeates into a capacitor part, and can prevent electrode corrosion and interface degradation.

  Since the inorganic protective film is covered with the organic protective film, corrosion of the extraction electrode by the solder used during mounting can be more effectively prevented.

  In addition, since the capacitor part is formed with an insulator thin film made of the same material as the dielectric thin film on the upper surface of the uppermost electrode film, the components of the insulating film diffuse to the dielectric thin film and the characteristics are degraded. Therefore, it is possible to prevent the insulation resistance of the capacitor portion from being lowered.

1 is a cross-sectional view schematically showing an embodiment of a thin film capacitor according to the present invention. It is a manufacturing process figure (1/2) which shows the manufacturing method of the said thin film capacitor. It is a manufacturing process figure (2/2) which shows the manufacturing method of the said thin film capacitor. 1 is a cross-sectional view of a thin film capacitor described in Patent Document 1. FIG. It is sectional drawing of the thin film capacitor described in patent document 2. FIG.

  Next, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a sectional view schematically showing an embodiment of a thin film capacitor according to the present invention.

In this thin film capacitor, an adhesion layer 3 is formed on a Si single crystal substrate (hereinafter simply referred to as “Si substrate”) 2 on which an oxide layer 1 made of SiO ₂ is formed, and an upper surface of the adhesion layer 3 is formed. The first electrode film 4, the dielectric thin film 5, and the second electrode film 6 are sequentially formed, and the insulator thin film made of the same material as the dielectric thin film 5 is further formed on the surface of the second electrode film 6. 7 is formed. The first electrode film 4, the dielectric thin film 5, and the second electrode film 6 form a capacitance generating portion, and the capacitance generating portion and the insulating thin film 7 form a capacitor portion 8.

  The capacitor unit 8 is covered on the upper surface and side surfaces with an insulating film 9 having a two-layer structure, that is, an inorganic insulating film 10 having a thickness of 200 to 1000 nm and an organic insulating film 11 having a thickness of 2000 to 10,000 nm. Then, the organic insulating film 11 absorbs mechanical stress from first and second external connection electrodes, which will be described later, and moisture released from the organic insulating film 11 enters the capacitor unit 8 by the inorganic insulating film 10. Is preventing.

  The first extraction electrode 12 and the second extraction electrode 13 are electrically insulated from each other and penetrate the insulating film 9, and the first extraction electrode 12 is electrically connected to the first electrode film 4. The second extraction electrode 13 is electrically connected to the second electrode film 6.

  First and second external connection electrodes 14 and 15 are formed on the top surfaces of the first and second extraction electrodes 12 and 13 so that external electronic components such as LSI can be connected by soldering.

  As the conductive material used for the first and second electrode films 4 and 6, it is preferable to use a high melting point noble metal material having good conductivity and excellent oxidation resistance, for example, Pt and Au. it can. The film thicknesses of the first and second electrode films 4 and 6 are not particularly limited as long as they are appropriate thin films, but are preferably set to 100 to 500 nm.

Moreover, as a thin film material used for the dielectric thin film 5 and the insulator thin film 7, a dielectric material having a high dielectric constant is used. Specifically, bismuth layered compounds such as (Ba, Sr) TiO ₃ (hereinafter referred to as “BST”), SrTiO ₃ , BaTiO ₃ , Pb (Zr, Ti) O ₃ , SrBi ₄ Ti ₄ O ₁₅ , etc. Of these, BST is preferably used.

  The thickness of the dielectric thin film 5 is not particularly limited as long as a desired electrostatic capacity can be ensured, but is preferably set to about 80 to 150 nm.

  Further, the thickness of the insulator thin film 7 is not particularly limited as long as the component of the insulator film 9 is diffused to the dielectric thin film 5 and does not cause deterioration in characteristics. Like the thin film 5, it is preferably set to about 80 to 150 nm.

  The first and second extraction electrodes 12 and 13 have a two-layer structure including a first layer formed of Ti or the like and a second layer formed of Cu or the like. The first layer has a thickness of, for example, 100 nm. The second layer is formed to have a thickness of 1000 nm, for example.

  The external connection electrodes 14 and 15 have a two-layer structure including a first layer formed of Ni or the like and a second layer formed of Au or the like, and the first layer is formed to 2000 nm, for example. The two layers are formed to 200 nm, for example.

  In this thin film capacitor, the inorganic protective film 16 having a thickness of 200 to 1000 nm is formed so as to cover the upper surface of the first and second extraction electrodes 12 and 13 excluding the site where the external connection electrodes 14 and 15 are formed, and An organic protective film 17 having a thickness of 2000 to 10,000 nm is formed on the surface of the inorganic protective film 16.

SiN _x , SiO ₂ , Al ₂ O ₃ , TiO ₂ or the like can be used as the inorganic insulating film 10 and the inorganic protective film 16, and polyimide resin or organic protective film 17 can be used as the organic insulating film 11 and the organic protective film 17. An epoxy resin or the like can be used.

  Next, a method for manufacturing the thin film capacitor will be described in detail with reference to FIGS.

First, as shown in FIG. 2A, a thermal oxidation process is performed on the Si substrate 2 to form an oxide layer 1 made of SiO ₂ having a thickness of 500 to 1000 nm.

Next, an adhesion layer 3 having a thickness of 10 to 100 nm is formed on the oxide layer 1 by a chemical solution deposition (hereinafter referred to as “CSD”) method. As the adhesion layer 3, BST, SrTiO ₃ , BaTiO ₃ , perovskite compounds such as Pb (Zr, Ti) O ₃ , bismuth layered compounds such as SrBi ₄ Ti ₄ O _15, etc. can be used. The same material as the layer is desirable. For example, when forming a BST film, a film forming raw material solution in which Ba, Sr, and Ti are mixed at a molar ratio of, for example, Ba: Sr: Ti = 7: 3: 10 is prepared. And this film-forming raw material solution is applied on the oxide layer 1, dried on a hot plate at 300 to 400 ° C., and subjected to heat treatment at a temperature of 600 to 700 ° C. for 10 to 60 minutes for crystallization, A BST film is formed.

  Next, a first conductive layer 4 ', a first insulator layer 5', a second conductive layer 6 ', and a second insulator layer 7' are sequentially formed. Specifically, a first conductive layer 4 ′ made of Pt or Au having a film thickness of 100 to 500 nm is formed by RF magnetron sputtering, and then a film thickness 80 made of BST or the like is formed by CSD as in the case of the adhesion layer 3. A first insulator layer 5 'having a thickness of ˜150 nm is formed, and then a second conductive layer 6 ′ made of Pt or Au having a thickness of 100 to 500 nm is formed by RF magnetron sputtering as in the case of the first conductive layer 4 ′. Form. Further, a second insulator layer 7 'having a film thickness of 80 to 150 nm made of BST or the like is formed by the CSD method.

  Next, using the photolithography technique and the argon ion milling method, as shown in FIG. 2B, the insulator thin film 7, the second electrode film 6, the dielectric thin film 5, and the first electrode film 4 are formed. Make it. That is, after a photoresist is applied and prebaked, the photoresist is irradiated with ultraviolet light through a photomask, and exposure, development, and postbaking are performed to transfer the photomask pattern to the resist pattern. Next, argon ions are made to collide with the etching surface by an argon ion milling method so that the second insulator layer 7 ', the second conductive layer 6', the first insulator layer 5 ', the first conductive layer 4', A predetermined region of the adhesion layer 3 is etched to sequentially form the insulator thin film 7, the second electrode film 6, the dielectric thin film 5, and the first electrode film 4, whereby the capacitor unit 8 is manufactured.

  Thereafter, the capacitor portion 8 is heat-treated at a temperature of 800 to 900 ° C. for about 30 minutes.

  Next, an insulating layer made of an inorganic material having a film thickness of 200 to 1000 nm is formed by a sputtering method so as to cover the upper surface and the side surface of the capacitor unit 8 and the side surface of the adhesion layer 3, and then a photosensitive resin is formed by a spin coating method. The material is applied so as to cover the insulating layer, and then heated at a temperature of 125 ° C. for 5 minutes, exposed and developed, and then heated at 350 ° C. for about 1 hour. An insulating layer made of an organic material having a predetermined pattern is formed.

Next, using the insulating layer made of an organic material as a mask, the insulating layer 9 made of an inorganic material and the oxide layer 1 made of SiO ₂ are dry-etched using CHF ₃ gas, and as shown in FIG. An insulating film 9 composed of the insulating film 10 and the organic insulating film 11 is formed, and parts of the first electrode film 4 and the second electrode film 6 are exposed on the surface.

  Next, using RF magnetron sputtering, two metal layers to be the first and second extraction electrodes 12 and 13 are formed, and then electroplating is performed to form a two-layered plating film Then, the first and second external connection electrodes 14 and 15 are formed. Thereafter, the photomask pattern is transferred to the resist pattern using the photolithography technique described above, and etched using an argon ion milling method. As a result, as shown in FIG. First and second extraction electrodes 12 and 13 having second external connection electrodes 14 and 15 on the upper surface are formed.

Next, as shown in FIG. 3E, the upper surfaces of the first and second external connection electrodes 14 and 15, the upper and side surfaces of the insulating film 9, and the side surface of the oxide layer 1 made of SiO ₂ are formed by sputtering. An insulating layer 16 'made of an inorganic material having a thickness of 200 to 1000 nm is formed so as to cover it. Next, a photosensitive resin material is applied by spin coating so as to cover the insulating layer, and then heated at 125 ° C. for 5 minutes, exposed and developed, and then heated at 350 ° C. for about 1 hour. Then, the organic protective film 17 having a film thickness of 2000 to 10000 nm is formed.

Next, using the organic protective film 17 as a mask, the insulating layer 16 'made of an inorganic material is dry-etched using CHF ₃ gas, whereby the external connection electrodes 14 and 15 are exposed to the surface as shown in FIG. And the inorganic protective film 16 is formed and a thin film capacitor is obtained.

  As described above, in the present embodiment, the first and second extraction electrodes 12 and 13 are covered with the inorganic protective film 16 except for the connection portion with the external electronic component. There is no exposure to the environment. Therefore, it is possible to avoid the occurrence of stress due to moisture absorption / expansion of the organic insulating film 11, and the first and second extraction electrodes 12, 13 are peeled off from the protective film 9 to cause moisture in the capacitor unit 8. Can be prevented from entering. Further, since the moisture resistance is improved as described above, electrode corrosion and interface deterioration can be prevented.

  And since the inorganic protective film 16 is coat | covered with the organic protective film 17, the corrosion of the 1st and 2nd extraction electrodes 12 and 13 by the solder used at the time of mounting can be prevented more effectively.

  In addition, since the insulating thin film 7 is formed on the upper surface of the second electrode film 6 in the capacitor unit 8, it is avoided that components of the inorganic insulating film 10 are diffused into the dielectric thin film 5 and the characteristics are deteriorated. Therefore, it is possible to suppress a decrease in the insulation resistance of the capacitor unit 8.

  The present invention is not limited to the above embodiment. For example, the film thickness, formation method, formation conditions, and the like of each layer shown in the above embodiment are merely examples, and it goes without saying that the thin film capacitor can be arbitrarily changed within a range that does not impair the intended function. Absent.

  Further, in the above embodiment, the case where the capacitor unit 8 has a single layer structure having one capacitance generation unit has been described. However, the present invention can be similarly applied to a multilayer structure having two or more capacitance generation units. Needless to say.

  Next, examples of the present invention will be described.

  Example samples were produced in accordance with the above-described embodiment for carrying out the invention.

  Table 1 shows the forming material, film thickness, and forming method of each layer.

  Moreover, the comparative example sample was produced with the method and procedure similar to an Example sample except not having formed the inorganic protective film and the organic protective film.

  Then, PCT (Pressure Cooker Test) was performed on each of the five examples and comparative samples, and the reliability was evaluated. That is, it was left for 48 hours under a high temperature and humidity of 121 ° C. and a relative humidity of 85%, and the reliability was evaluated by the presence or absence of a short circuit, the decrease rate of capacitance, and the decrease rate of resistance value.

  Here, the short-circuit test evaluation was performed by conducting a continuity check between the external connection electrodes. For the evaluation of the capacitance, the capacitance before and after the PCT was measured with a capacitance meter, and a product whose capacitance decreased by 10% or more was determined as a defective product. For the evaluation of the resistance value, the resistance value before and after the PCT was measured with an ohmmeter, and the resistance value was determined to be defective if it decreased by 10% or more.

  Table 2 shows the number of defective products among the five.

  As is clear from Table 2, in the example sample and the comparative example sample, no short circuit occurred, and the rate of decrease in capacitance was good within 10%.

  However, the resistance value of the comparative sample decreased by 10% or more at 2 out of 5 samples.

  On the other hand, the sample of the example of the present invention has no sample whose resistance value has decreased by 10% or more, and it was found that the moisture resistance can be improved.

  Since it does not absorb moisture or expand depending on the surrounding environment, a thin film capacitor suitable for use under high temperature and high humidity can be provided.

4 First electrode film 5 Dielectric thin film 6 Second electrode film 7 Insulator thin film 8 Capacitor portion 9 Insulating film 10 Inorganic insulating film 11 Organic insulating film 12 First extraction electrode 13 Second extraction electrode 14 First extraction film 14 External connection electrode 15 Second external connection electrode 16 Inorganic protective film 17 Organic protective film

Claims (3)

A capacitor portion having a first electrode film formed on the lower surface of the first dielectric thin film and a second electrode film formed on the upper surface of the first dielectric thin film, and an outer surface formed of an organic material. And at least one insulating protective film covering the capacitor portion, and electrically connected to one of the first and second electrode films through the insulating protective film and electrically connected to each other. First and second extraction electrodes electrically insulated,
The first and second extraction electrodes are covered with an inorganic protective film except for a connection portion with an external electronic component.   2. The thin film capacitor according to claim 1, wherein the inorganic protective film is covered with an organic protective film.   3. The capacitor part, wherein a second dielectric thin film made of the same material as the first dielectric thin film is formed on an upper surface of the second electrode film. The thin film capacitor described.

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