JP2007026982A - Solid state battery and battery-mounted integrated circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system-in-package of an integrated circuit and a solid state battery without causing characteristic deterioration or malfunction; and to provide a multilayer wiring board. <P>SOLUTION: Since diffusion of ions bearing charge/discharge of a solid state battery into an integrated circuit can be prevented by forming a protective film of the solid state battery into a multilayer structure and by providing a positive potential to one metal layer out of them, this system-in-package of the integrated circuit and the battery without causing characteristic deterioration or malfunction and this multilayer wiring board can be provided. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to prevention of ion contamination by a solid battery, and relates to a solid battery capable of preventing ion contamination and a battery-mounted integrated circuit device in which the solid battery coexists with an integrated circuit.

  In recent years, with the miniaturization of electronic devices, it is called system-in-package (hereinafter also referred to as SiP), and a plurality of IC chips are housed in the same package (see, for example, Patent Document 1). SiP is promising because it has the advantages of low power consumption, high performance, and reduced mounting area. FIG. 7 shows a structure called a chip stack type. In FIG. 7, three layers of semiconductor chips 41 are stacked in a package 43, and a wire (not shown) made of Au is connected therebetween, and is connected to the outside via a terminal 42.

As the mounting area is further reduced in the future, it is expected that even the battery will be taken into the SiP. Among them, SiP incorporating a lithium ion solid state battery that can be expected to have a high capacity is promising.
JP 2004-228323 A

  However, in lithium ion solid state batteries, it is known that lithium ions responsible for charging and discharging form an alloy with Si, which is a semiconductor material. Therefore, even in the case of a solid battery, when a lithium ion solid pond is incorporated, there is a concern about contamination of the semiconductor element by lithium ions responsible for charging and discharging. That is, lithium ions diffuse into the semiconductor substrate through the protective film of the lithium ion solid battery, and there is a concern that the semiconductor element formed on the silicon substrate may be deteriorated in characteristics or malfunction due to alkali metal contamination.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a solid state battery and a battery-mounted integrated circuit device capable of mounting a solid state battery and a semiconductor integrated circuit in the same package or substrate.

In order to solve the conventional problems, the solid battery of the present invention is
A power generation element including a positive electrode, a negative electrode, and a solid electrolyte;
A solid state battery having a protective film outside the power generation element,
The protective film has a multilayer structure, and at least one of them has a positive potential.

  With this configuration, it is possible to prevent ions (particularly lithium ions) responsible for charging and discharging from diffusing out of the solid battery via the protective film.

The battery-mounted integrated circuit device of the present invention is
A wiring board;
A solid state battery of the present invention mounted on a wiring board;
And a semiconductor chip mounted on the wiring board.

  With this configuration, the solid battery and the semiconductor integrated circuit can be mounted in the same package or substrate.

  According to the configuration of the present invention, it is possible to prevent diffusion of ions responsible for charging / discharging of the solid battery into the integrated circuit, so that the semiconductor element formed in the same package as the solid battery is responsible for charging / discharging of the solid battery. Will not be contaminated. Therefore, it is possible to prevent the deterioration of characteristics and malfunction of the semiconductor device.

  Furthermore, according to the configuration of the present invention, deterioration of the characteristics of the semiconductor device can be prevented even when a battery using not only a lithium ion battery but also hydrogen ions as ions responsible for charging and discharging is used.

  Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1)
1 and 2 are a schematic top view and a schematic cross-sectional view of a solid state battery having a multilayer protective film of the present invention, respectively.

  1 and 2, the solid state battery according to the present invention is formed on a substrate 11. As the substrate 11, a conductive material can be used as long as it can withstand the conditions for forming each layer constituting the battery, for example, low gas emission in a vacuum, or a temperature during film formation. Materials can also be used. Examples of the conductive substrate include a silicon wafer and a metal material such as copper, nickel, titanium, molybdenum, and tantalum. Insulating substrates include inorganic materials such as glass, silica and alumina, or heat-resistant plastic films such as polyimide and polyamide.

  When the material used as the substrate 11 has an alloying reaction with lithium, it is necessary to provide a barrier layer 12 for suppressing the reaction. For example, when a silicon wafer is used as a substrate, it is necessary to form a barrier layer 12 such as a silicon oxide layer on the surface by a technique such as plasma CVD.

  When an insulating substrate is used as the substrate 11, it is necessary to form a layer made of a conductive material as the first current collector layer 13 on the surface on which the solid battery is formed. On the other hand, when the substrate 11 is a conductive substrate, the first current collector 13 is formed as necessary, depending on the electrical conductivity of the substrate.

  A power generation element is formed thereon. First, after forming the first active material layer 14 of either the positive electrode active material or the negative electrode active material, the solid electrolyte layer 15 is formed, and the second active material layer 16 paired with the first active material layer formed thereon is formed. Form. Further, a second current collector layer 17 is formed thereon as necessary.

  A protective film is formed thereon. In the present invention, the protective film is formed of multiple layers, and at least one of them has a positive potential. 1 and 2 show an example in which the protective film is formed of two layers. After forming the lower protective layer 18, an upper protective layer 19 to which a positive potential is applied is formed from a conductive material. A protective layer may be further formed on the upper protective layer 19 with the material used for the lower protective layer 18. 1 and 2, the protective film covers only the battery portion formed on the substrate 11, but after ensuring insulation from the terminals connected to the positive and negative current collectors, The effect is the same even if the whole including is covered with a protective film. For example, an aluminum laminate film may be used to cover the entire power generating element, and a positive potential may be applied to the aluminum foil portion of the aluminum laminate film. Even if the positive potential applied to the upper protective layer 19 is in a range larger than 0 V and smaller than the potential of the positive electrode with respect to the negative electrode, an effect of suppressing diffusion of lithium ions through the protective film can be obtained. It is preferable that the positive electrode potential be equal to or higher than the negative electrode. If the potential is higher than that of the positive electrode, lithium ions will not diffuse through the protective film. The upper limit is not particularly limited as long as the semiconductor element does not cause dielectric breakdown.

  FIG. 3 shows an example in which the solid battery thus obtained is incorporated into a semiconductor device (SiP). A solid battery 22 is first installed on the lead frame 21, and a semiconductor chip 23 such as a microcomputer chip is installed thereon. These entire devices are protected by a semiconductor device protective layer 24 formed of an epoxy resin or the like.

  Each terminal (not shown) of the battery is connected to a power supply terminal (not shown) of the semiconductor device 23. Furthermore, the positive electrode terminal of the battery 22 is connected to a layer (upper protective layer 19) formed of a conductive material in the protective film. As a result, a layer having a positive potential is provided between the semiconductor device 23 and the solid state battery 22, thereby preventing lithium ions contributing to the battery reaction from passing through the protective film and diffusing into the semiconductor device 23.

As a battery that can be used in the present invention, a lithium ion solid battery having a high energy density is desirable. Applied as a material for forming a power generating element, lithium cobalt oxide as the positive electrode active material, lithium nickelate, lithium manganate or a complex compound such as a mixture thereof or _{LiNi x Co 1-x O 2} (0 <x <1) is it can. Active materials for the negative electrode include lithium ions batteries such as graphite, Sn, Si, alloys such as Ni ₃ Sn ₄ and Mg ₂ Sn, solid solutions, compounds such as SnO _x (0 <x <2), SnO _2, SiB ₄ and SiB _6. Generally used materials can be used.

As the solid electrolyte 14, a so-called polymer electrolyte layer containing an electrolyte solution in which a solute is dissolved in an organic solvent and made non-fluidized with a polymer, lithium nitride (Li ₃ N), lithium phosphate (Li ₃ PO ₄ ), silicon Examples thereof include lithium oxide (Li ₄ SiO ₄ ), lithium sulfide (Li ₂ S), phosphoryl lithium nitride (LIPON), and composites thereof.

  In order to form each layer constituting the power generation element, a dry thin film process such as a sputtering method, a vacuum deposition method, a laser ablation method, an ion plating method, or a CVD (Chemical Vapor Deposition) method, or a powder of an active material is used. A method of forming a paste by adding a binder and a solvent and forming the paste by a doctor blade method or the like can be applied.

  As a material constituting the protective film for protecting the power generation element, an inorganic material such as silicon nitride or an organic material such as an epoxy resin can be used. As a material for forming a layer to which a positive potential is applied, any material having electrical conductivity can be used. Specifically, a metal material such as aluminum or copper, or a conductive polymer material such as polypyrrole or polythiophene can be used. As a method for forming a layer to which a positive potential is applied, a dry thin film process, a doctor blade method, or the like can be applied as in the case of forming a power generation element.

  Hereinafter, the present invention will be described with reference to specific examples.

Example 1
The solid battery shown in FIG. 1 was produced by the following method. Using a silicon substrate having a size of 16 mm long × 19 mm wide, 525 μm in size, P type, and a specific resistance of 10 to 15 Ω · cm as the substrate 11, the barrier layer 12 was formed on the surface with a silicon oxide film by a plasma CVD method. The formation conditions SiH ₄ and _N 2 O as reaction gases, frequency 50 kHz, to generate RF plasma at output 4 kW, the reaction chamber and 380 ° C.. A metal copper film was formed thereon as a first current collector 13 in a pattern of 10 mm length × 13 mm width by a vacuum vapor deposition apparatus, and graphite was formed thereon as a first active material 14 with a thickness of 5 μm and a width of 8 mm. Further, a solid electrolyte layer 15 made of Li ₂ S—SiS ₂ —Li ₃ PO ₄ is formed thereon with a thickness of 2 μm and a length and width of 12 mm, and sequentially laser ablation (10-2 Torr, YAG laser: 266 nm, 2025 mJ / cm ² , frequency 10 Hz, the number of shots: 36000). Further thereon, LiCoO ₂ was formed as the second active material layer 16 by RF magnetron sputtering (20 mTorr, Ar: O 2 = 3: 1, introduced gas amount = 20 mSCCM, 200 W) with a thickness of 5 μm and a length and width of 8 mm and 64 mm 2. Each of these films is patterned using the metal mask (SUS304) having the above-described size. Thereafter, annealing was performed at 400 ° C. for 4 hours. Further, using a metal mask (SUS304) patterned thereon as the second current collector 17, a metal aluminum film having a thickness of 1 μm and a length of 10 mm × width of 14 mm was formed by vacuum deposition.

Next, a silicon nitride film having a thickness of 5000 mm and a length and width of 14 mm was formed as the lower protective layer 18 by plasma CVD. The formation conditions were SiH ₄ and N ₂ as reaction gases, RF plasma was generated at a frequency of 50 kHz, and an output of 4 kW, and the reaction chamber was set at 380 ° C. A metal aluminum film was formed thereon as an upper protective layer 19 in a pattern of 12 mm length × 14 mm width by a vacuum vapor deposition apparatus and connected to the positive electrode current collector 17. Each of the above film formations was patterned using the above-described metal mask (SUS304) having an empty size. Thus, the solid battery 22 according to the present invention was produced.

  Further, as a solid battery for comparison, the production method was the same as that of the solid battery 22, and the solid battery A without the metal aluminum film as the upper protective layer 19 was produced. 5 and 6 show a schematic top view and a schematic cross-sectional view of the solid state battery manufactured in Comparative Example 1. FIG. The same components as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof is omitted. The solid battery 22 and the solid battery A thus obtained each had a capacity of 200 μAh.

  Next, SiP with a built-in solid state battery shown in FIG. 3 was produced by the following method. An appropriate amount of Ag paste (manufactured by Dotite) was applied on a lead frame 21 (manufactured by Hirai Seimitsu Co., Ltd.) produced for this package, and the above-described solid battery 22 was further set thereon by heating at 200 ° C. An appropriate amount of a liquid epoxy resin (manufactured by Hitachi Chemical Co., Ltd .: CEL-C-1102) was applied thereon, and an n-type MOS transistor chip 23 (5 V specification, Vth: 0.7 V, Matsushita Electric) produced for this evaluation. A prototype manufactured by Sangyo Co., Ltd. was installed by thermosetting at 150 ° C. for 3 hours. Thereafter, the transistor 23 and the lead frame 21, the solid battery 22, and the lead frame 21 were wired using a soldering iron set at 200 ° C. with a 100 μm diameter gold wire coated with polyurethane. In the wiring, when the solid state battery 22 is charged, a voltage is applied to the drain of the transistor 23. At this time, when a voltage of 1.0 V or higher is applied to the gate of the transistor 23, the transistor 23 is turned on, current flows, and the solid state battery 22 is discharged. Further, an appropriate amount of a liquid epoxy resin (manufactured by Hitachi Chemical Co., Ltd .: CEL-C-1102) was applied thereon, and thermoset at 150 ° C. for 3 hours to prepare SiP.

  The system was evaluated based on whether the gate voltage fluctuated. According to such a configuration, since the surface of the solid battery is fixed at a high potential of the positive electrode, lithium ions contained in the solid battery can be prevented from diffusing into the transistor, and the characteristics of the semiconductor element deteriorate due to contamination. Therefore, the battery-mounted integrated circuit device is free from malfunction.

  For comparison, a SiP having the above-described solid battery A installed therein was also manufactured in exactly the same manner as the above-described SiP manufacturing method.

(Example 2)
Next, a multilayer wiring board incorporating the solid state battery shown in FIG. An n-type MOS transistor chip 32 (5 V specification, Vth: 0.7 V, manufactured by Matsushita Electric Industrial Co., Ltd.) manufactured for the present evaluation on the printed wiring board 31 manufactured for the present multilayer substrate (prototype manufactured by Matsushita Electric Industrial Co., Ltd.) The work) was placed with Ag paste (Dotite) heated at 200 ° C. Solder bumps are formed on the terminal pads of the n-type MOS transistor at that time, and the chip 32 is placed so as to be electrically connected to the wiring of the substrate 31. Furthermore, a suitable amount of liquid epoxy resin (manufactured by Hitachi Chemical Co., Ltd .: CEL-C-1102) is dropped onto it, and another printed wiring board 35 is installed thereon by thermosetting at 150 ° C. for 3 hours. The solid battery 33 having the same configuration as that of the solid battery 22 manufactured in Example 1 was installed on the solder.

  Here, the printed wiring boards 31 and 35 were connected by solder so as to be electrically connected. As for the connection of the wiring, when the solid battery 33 is charged, a voltage is applied to the drain of the transistor 32. At this time, when a voltage of 1.0 V or more is applied to the gate of the transistor 32, the transistor 32 is turned on, current flows, and the solid state battery 33 is discharged. Finally, a liquid epoxy resin (manufactured by Hitachi Chemical Co., Ltd .: CEL-C-1102) was added dropwise and thermally cured at 150 ° C. for 3 hours to coat the multilayer wiring board with the epoxy resin 34. The system was evaluated based on whether the gate voltage fluctuated. According to such a configuration, since the surface of the solid battery is fixed at a high potential of the positive electrode, lithium ions contained in the solid battery can be prevented from diffusing into the transistor, and the characteristics of the semiconductor element deteriorate due to contamination. Therefore, the battery-mounted integrated circuit device is free from malfunction.

  As a comparative example, a multilayer wiring board on which a solid battery having the same configuration as that of the solid battery A produced in Example 1 was installed in the same manner as the above production method.

(Evaluation)
The storage characteristics of the system-in-package and multilayer wiring board obtained above were determined as follows. First, when the gate threshold voltage (drain current was 1 μA) of the transistor was measured, it was 1.0 V. Next, charging was performed up to 4.2 V with a current of 40 μA. Thereafter, after storing in a thermostat at 150 ° C. for 1000 hours, the gate threshold voltage of the transistor was measured. The results are shown in Table 1.

  As is apparent from Table 1, in the system in package and the multilayer wiring board, the n-type MOS transistor integrated with the solid battery of the multilayer protective film is gated as compared with the case where it is integrated with the solid battery of the single protective film. The variation in threshold voltage is small. This is presumably because the surface of the protective film covering the power generating element of the solid battery is kept at a positive potential, so that lithium ions are difficult to diffuse outside the power generating element.

  The solid state battery according to the present invention can prevent diffusion of ions, which are responsible for charging and discharging of the solid state battery, into the integrated circuit, and thus can prevent deterioration in characteristics and malfunction of the semiconductor device.

  Moreover, since the battery-mounted integrated circuit device having the solid battery and the semiconductor chip according to the present invention can incorporate the solid battery into the SiP, it is possible to provide a battery-mounted integrated circuit device with a reduced mounting area.

Schematic top view of a solid state battery having a multilayer protective film of the present invention Schematic sectional view of a solid state battery having a multilayer protective film of the present invention Schematic sectional view of SiP incorporating a solid state battery according to Embodiment 1 of the present invention Schematic sectional view of a multilayer wiring board incorporating a solid state battery in Example 2 of the present invention Schematic top view of a conventional solid battery having a single layer protective film Schematic cross-sectional view of a conventional solid battery having a single-layer protective film Schematic cross section of conventional SiP

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Board | substrate 12 Barrier layer 13 1st electrical power collector layer 14 1st active material layer 15 Solid electrolyte layer 16 2nd active material layer 17 2nd electrical power collector layer 18 Lower protective layer 19 Upper protective layer 21 Lead frame 22 Solid battery 23 MOS transistor 24 Sealing resin 25 Au wire 31, 35 Printed wiring board 32 MOS transistor 33 Solid electrolyte film 34 Sealing resin 36 Solder 41 Semiconductor chip 42 Terminal 43 Package

Claims (2)

A power generation element including a positive electrode, a negative electrode, and a solid electrolyte;
A solid state battery having a protective film outside the power generation element,
The protective film has a multilayer structure, at least one of which has a positive potential;
Solid battery characterized by. A wiring board;
The solid state battery according to claim 1 mounted on the wiring board;
Having a semiconductor chip mounted on a wiring board;
A battery-mounted integrated circuit device characterized by the above.

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