JP2005078693A - Magnetic memory device and its mounting structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic memory device comprised of an MRAM element or a memory element having a magnetic layer which can be magnetized, in which a magnetic shield layer magnetically shielding a magnetic memory element from an external magnetic field and sufficiently protecting the memory element even when large external magnetic field is operated and a heat radiating means preventing over-heating of the memory element by improving heat radiation efficiency are simply mounted, and the mounting structure of the magnetic memory device in which heat radiation efficiency is improved. <P>SOLUTION: A magnetic random access memory (MRAM) 30 consisting of a TMR element 10 on which magnetization fixed layers 4, 6 in which a magnetization direction is fixed and a magnetic layer (storage layer)2 in which a magnetization direction can be changed are laminated, is sealed by a sealing material 33 such as resin, a magnetic shield layer 34 for magnetically shielding the MRAM 30 is brought into contact with the upper plane (and the lower plane) of the sealing material 33 and fixed by adhesive or the like, and a heat spreader 41 being the heat radiation means is provided jointing to the magnetic shield layer 34. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an MRAM (Magnetic Random) which is a magnetic random access memory composed of a memory element in which a magnetization fixed layer with a fixed magnetization direction and a magnetic layer capable of changing the magnetization direction are stacked, that is, a so-called nonvolatile memory. The present invention relates to a magnetic memory device configured as an Access Memory, or a magnetic memory device including a memory element having a magnetizable magnetic layer, and a mounting structure thereof.

  With the rapid spread of information communication equipment, especially small personal devices such as portable terminals, the elements such as memory and logic that make it up are becoming more highly integrated, faster, and consume less power. Performance improvement is required.

  In particular, nonvolatile memories are considered essential in the ubiquitous era. The nonvolatile memory can protect important information including personal information even when power is consumed or trouble occurs or the server and the network are disconnected due to some trouble. In addition, recent portable devices are designed to reduce power consumption as much as possible by setting unnecessary circuit blocks to the standby state. However, if a non-volatile memory that can serve both as a high-speed work memory and a large-capacity storage memory can be realized. , Power consumption and memory waste can be eliminated. In addition, if a high-speed, large-capacity nonvolatile memory can be realized, an “instant-on” function that can be instantly started when the power is turned on becomes possible.

  Examples of the non-volatile memory include a flash memory using a semiconductor and an FRAM (Ferroelectric Random Access Memory) using a ferroelectric.

However, the flash memory has a drawback that the writing speed is as slow as the order of μ seconds. On the other hand, in FRAM, the number of rewritable times is 10 ¹² to 10 ¹⁴ , and the endurance is small to replace completely with SRAM (Static Random Access Memory) or DRAM (Dynamic Random Access Memory), and ferroelectricity It has been pointed out that microfabrication of body capacitors is difficult.

  For example, Wang et al., IEEE Trans. Magn., 33, 4498 (1997) are attracting attention as high-speed, large-capacity (highly integrated), low-power consumption non-volatile memories that do not have these drawbacks. The magnetic memory referred to as MRAM (Magnetic Random Access Memory) as described in (2)) has been attracting attention due to the recent improvement in characteristics of TMR (Tunnel Magnetoresistance) materials.

  The MRAM is a semiconductor magnetic memory using a magnetoresistive effect based on a spin-dependent conduction phenomenon peculiar to nanomagnets, and is a non-volatile memory that can hold a memory without supplying power from the outside.

  In addition, the MRAM has a simple structure and can be easily integrated. Further, since the recording can be performed by reversing the magnetic moment, the number of rewrites is large, and the access time is very high. It is anticipated and has already been reported in R.Scheuerlein et al., ISSCC Digest of Technical Papers, p.128-129, Feb.2000 that it can operate at 100 MHz.

  Describing in more detail about such an MRAM, as illustrated in FIG. 15, a TMR element 10 serving as a memory element of an MRAM memory cell is a memory layer provided on a support substrate 9 and whose magnetization is reversed relatively easily. 2 and the magnetization fixed layers 4 and 6.

  The magnetization fixed layer has two magnetization fixed layers of a first magnetization fixed layer 4 and a second magnetization fixed layer 6, and a conductor layer in which these magnetic layers are antiferromagnetically coupled between them. 5 is arranged. The memory layer 2 and the magnetization fixed layers 4 and 6 are made of a ferromagnetic material made of nickel, iron, cobalt, or an alloy thereof, and the material of the conductor layer 5 is ruthenium, copper, chromium, gold, silver Etc. can be used. The second magnetization fixed layer 6 is in contact with the antiferromagnetic material layer 7, and the second magnetization fixed layer 6 has a strong unidirectional magnetic anisotropy due to the exchange interaction acting between these layers. . As a material for the antiferromagnetic material layer 7, manganese alloys such as iron, nickel, platinum, iridium, and rhodium, cobalt, nickel oxide, and the like can be used.

  In addition, a tunnel barrier layer 3 made of an insulator made of an oxide or nitride such as aluminum, magnesium, or silicon is sandwiched between the storage layer 2 that is a magnetic layer and the first magnetization fixed layer 4. In addition to cutting off the magnetic coupling between the storage layer 2 and the fixed magnetization layer 4, it plays a role for flowing a tunnel current. Although these magnetic layers and conductor layers are mainly formed by sputtering, the tunnel barrier layer 3 can be obtained by oxidizing or nitriding a metal film formed by sputtering. The topcoat layer 1 has a role of preventing mutual diffusion between the TMR element 10 and wiring connected to the TMR element, reducing contact resistance, and preventing oxidation of the memory layer 2, and is usually made of a material such as Cu, Ta, or TiN. Can be used. The base electrode layer 8 is used for connection with a switching element connected in series with the TMR element. The underlayer 8 may also serve as the antiferromagnetic layer 7.

  In the memory cell configured as described above, as described later, information is read out by detecting a tunnel current change due to the magnetoresistive effect, and the effect depends on the relative magnetization directions of the storage layer and the magnetization fixed layer.

  FIG. 16 is an enlarged perspective view showing a part of a general MRAM in a simplified manner. Here, the read circuit portion is omitted for simplification, but includes, for example, nine memory cells, and has a bit line 11 and a write word line 12 that intersect each other. The TMR element 10 is disposed at these intersections, and writing to the TMR element 10 causes a current to flow through the bit line 11 and the write word line 12, and the bit line 11 is generated by a combined magnetic field generated therefrom. Is written with the magnetization direction of the storage layer 2 of the TMR element 10 at the intersection of the write word line 12 parallel or antiparallel to the magnetization fixed layer.

  FIG. 17 schematically shows a cross section of the memory cell. For example, a gate insulating film 15 formed in a p-type well region formed in the p-type silicon semiconductor substrate 13, a gate electrode 16, a source region 17, An n-type read field effect transistor 19 composed of the drain region 18 is disposed, and a write word line 12, a TMR element 10, and a bit line 11 are disposed thereon. A sense line 21 is connected to the source region 17 through a source electrode 20. The field effect transistor 19 functions as a switching element for reading, and a read wiring 22 drawn from between the word line 12 and the TMR element 10 is connected to the drain region 18 via the drain electrode 23. The transistor 19 may be an n-type or p-type field effect transistor, but various switching elements such as a diode, a bipolar transistor, and a MESFET (Metal Semiconductor Field Transistor) can be used.

  FIG. 18 shows an equivalent circuit diagram of the MRAM, which includes, for example, six memory cells, has a bit line 11 and a write word line 12 intersecting each other, and a storage element is formed at the intersection of these write lines. 10 includes a field effect transistor 19 and a sense line 21 which are connected to the memory element 10 and perform element selection at the time of reading. The sense line 21 is connected to the sense amplifier 21b and detects stored information. In the figure, 24 is a bidirectional write word line current drive circuit, and 25 is a bit line current drive circuit.

FIG. 19 is an asteroid curve showing the write condition of the MRAM, and shows the reversal threshold value of the storage layer magnetization direction by the applied easy axis magnetic field _HEA and hard axis magnetic field _HHA . When a corresponding synthetic magnetic field vector is generated outside the asteroid curve, magnetic field reversal occurs, but the synthetic magnetic field vector inside the asteroid curve does not invert the cell from one of its current bistable states. Also in cells other than the intersections of word lines and bit lines are a current flows, a magnetic field generated by the word line or bit line alone is applied, if their size is more than one direction reversal magnetic field H _K Since the magnetization direction of the cells other than the intersection is also reversed, the selected cell can be selectively written only when the combined magnetic field is in the gray region in the figure.

As described above, in the MRAM, by using two write lines, that is, a bit line and a word line, only a specified memory cell is written by reversal of the magnetic spin by utilizing the asteroid magnetization reversal characteristic. Is. Synthetic magnetization in a single storage area is determined by the vector combination of the magnetization hard axis magnetic field H _HA and the magnetization easy axis magnetic field H _EA applied thereto. The write current flowing through the bit line, the magnetic field H _EA easy magnetization axis direction is applied to the cell, and the current flowing through the word line applies a magnetic field H _HA hard magnetization axis direction cell.

  FIG. 20 illustrates the read operation of the MRAM. Here, the layer configuration of the TMR element 10 is schematically illustrated, the above-described magnetization fixed layer is shown as a single layer 26, and the components other than the storage layer 2 and the tunnel barrier layer 3 are not illustrated.

  That is, as described above, the information is written by inverting the magnetic spin of the cell by the combined magnetic field at the intersections of the bit lines 11 and the word lines 12 wired in a matrix and changing the direction to “1”, “0”. Record as information. In addition, the reading is performed using the TMR effect applying the magnetoresistive effect. The TMR effect is a phenomenon in which the resistance value changes depending on the direction of the magnetic spin. Information “1” and “0” are detected based on a low resistance state in which the magnetic spins are parallel. In this reading, a read current (tunnel current) is caused to flow between the word line 12 and the bit line 11 and an output corresponding to the level of the resistance is read to the sense line 21 via the read field effect transistor 19 described above. By doing.

As described above, MRAM is expected as a high-speed and nonvolatile large-capacity memory. However, since a magnetic material is used for storage, information is erased or rewritten due to the influence of an external magnetic field. There is a problem of end. The reversal magnetic field H _SW in the easy axis direction and the hard reversal axis direction H _SW described in FIG. 19 is 20 to 200 Oersted (Oe) depending on the material, and is several mA (RHKoch et al. Phys. Rev. Lett., 84, 5419 (2000), JZSun et al., 8th Joint Magnetism and Magnetic Material (2001)). Moreover, since the coercive force (Hc) at the time of writing is, for example, about several Oe to 10 Oe, it is impossible to selectively write to a predetermined memory cell if an internal leakage magnetic field due to an external magnetic field higher than that acts. It may become.

  Further, as a problem for practical use of MRAM, it is required to reduce a write current. In order to enable writing with a small write current of about 10 mA, more preferably about 1 mA, the external magnetic field acting on the element is preferably as small as possible.

  Therefore, as a step toward the practical use of MRAM, there is an urgent need to establish a countermeasure against external magnetism, that is, a magnetic shield structure that shields an element from an external magnetic field.

  The environment in which the MRAM is mounted and used is mainly on the high-density mounting substrate and inside the electronic device. Depending on the type of electronic equipment, due to the recent development of high-density mounting, semiconductor elements, communication elements, ultra-small motors, etc. are mounted with high density on high-density mounting boards. The antenna element, various mechanical parts, power supply, etc. are mounted with high density to constitute one device.

  Such mixed mounting is one of the features of MRAM as a non-volatile memory. However, an environment in which a magnetic field component in a wide frequency range from DC to low frequencies is mixed around MRAM. Therefore, in order to ensure the reliability of MRAM recording and holding, it is required to improve the resistance from an external magnetic field by devising the mounting method and shield structure of the MRAM itself.

As the magnitude of such an external magnetic field, for example, in a magnetic card such as a credit card or a bank cash card, it is defined that the magnetic field is resistant to a magnetic field of 500 to 600 Oe. For this reason, in the field of the magnetic card, a magnetic material having a large coercive force such as Co-coated γ-Fe ₂ O ₃ or Ba ferrite is used. Also in the field of prepaid cards, it is necessary to have resistance to a magnetic field such as 350 to 600 Oe. Since the MRAM element is a device that is mounted in an electronic device casing and is supposed to be carried, it must be resistant to the strong external magnetism equivalent to that of magnetic cards. Needs to be suppressed to 20 Oe or less, preferably 10 Oe or less.

  As a magnetic shield structure of the MRAM, a proposal has been made to provide magnetic shield characteristics by using an insulating ferrite (MnZn and NiZn ferrite) layer for a passivation film of an MRAM element (see Patent Document 1 described later). In addition, a proposal has been made to provide a magnetic permeability effect by attaching a high-permeability magnetic material such as permalloy from above and below the package to prevent magnetic flux from entering the internal elements (see Patent Document 2 described later). . Furthermore, a structure in which a shield cover is placed on the element with a magnetic material such as soft iron is disclosed (see Patent Document 3 described later).

US Pat. No. 5,902,690 specification and drawing (column 5, FIG. 1 and FIG. 3) US Pat. No. 5,939,772 specification and drawings (column 2, FIGS. 1 and 2) Japanese Patent Laid-Open No. 2001-250206 (right column on page 5, FIG. 6)

  In order to prevent the external magnetic flux from entering the memory cell of the MRAM, it is most important to provide a magnetic path that prevents the magnetic flux from entering the inside by circulating a magnetic material having a high magnetic permeability around the element. For this purpose, it is the best means to completely cover the element with a magnetic shield layer, but it is difficult to produce an actual shield structure, and a magnetic shield structure that can be easily produced is desired.

  However, when the element passivation film is formed of ferrite as in Patent Document 1 (US Pat. No. 5,902,690), the saturation magnetization of the ferrite itself is low (0.2 to 0.5 Tesla (T) with a general ferrite material). Therefore, it is impossible to completely prevent the external magnetic field from entering. The saturation magnetization of the ferrite itself is about 0.2 to 0.35 T for NiZn ferrite and about 0.35 to 0.47 T for MnZn ferrite, but the magnitude of the external magnetic field penetrating into the MRAM element is as large as several hundred Oe. At about the saturation magnetization, the magnetic permeability of the ferrite is almost 1, and the function is lost. In Patent Document 1, there is no description of the film thickness. However, since the passivation film is usually about 0.1 μm at most, it is too thin as a magnetic shield layer, so that almost no effect can be expected. Moreover, when ferrite is used for the passivation film, since the ferrite is a magnetic oxide, oxygen deficiency is likely to occur when the film is formed by sputtering, and it is difficult to use complete ferrite as the passivation film.

Patent Document 2 (US Pat. No. 5,939,772) describes a structure in which the top and bottom of a package are covered with a permalloy layer. By using permalloy, higher shielding performance than that of a ferrite passivation film can be obtained. However, although the magnetic permeability of Mu Metal disclosed in Patent Document 2 is as high as μ _i = 100,000, the saturation magnetization is as low as 0.7 to 0.8 T, and it can be easily applied to an external magnetic field. On the other hand, since μ = 1 is obtained by saturation, there is a disadvantage that the thickness of the shield layer must be considerably thick in order to obtain a complete magnetic shielding effect. Therefore, as a structure for preventing the magnetic field of several hundred Oe from penetrating practically, it is imperfect as a magnetic shield layer from the viewpoint that the saturation magnetization of permalloy is too small and its thickness is too thin.

Patent Document 3 (Japanese Patent Laid-Open No. 2001-250206) discloses a magnetic shield structure using soft iron or the like, but this only covers the upper part of the element, so that the magnetic shield is incomplete, Soft iron has a saturation magnetization of 1.7 T and a magnetic permeability of about 300 in μ _i, which is insufficient in magnetic properties. Therefore, even if the magnetic shield is performed with the structure described in Patent Document 3, it is extremely difficult to completely prevent the intrusion of the external magnetic field.

  In principle, the MRAM can rewrite the memory with low power consumption by the above-described mechanism. However, at present, it cannot be said that the low power consumption of the memory rewrite is sufficiently realized. In the future, high integration such as SIP (System In Package) and SOC (System On Chip) in which memories such as LSI (Large Scale Integration) and MRAM are integrated on one chip will progress. It is expected that the heat generation density from and the heat generation density of the chip itself will increase overall. On the other hand, since the size of the magnetic memory element has to be reduced as the capacity of the MRAM increases, there is a concern that the memory cannot be retained due to the magnetic aftereffect due to thermal fluctuation. A highly efficient heat dissipation means to prevent is needed.

  The present invention has been made in view of the above circumstances, and its purpose is to shield the magnetic memory element from an external magnetic field magnetically and sufficiently protect the memory element even when a large external magnetic field acts. Magnetic memory device comprising an MRAM element or a memory element having a magnetizable magnetic layer, and a heat dissipation efficiency improved by simply mounting a magnetic shield layer and a heat dissipation means for increasing heat dissipation efficiency to prevent overheating of the memory element, and improving heat dissipation efficiency Another object of the present invention is to provide a mounting structure for a magnetic memory device.

That is, according to the present invention, a magnetic random access memory including a memory element in which a magnetization fixed layer whose magnetization direction is fixed and a magnetic layer capable of changing the magnetization direction is laminated is sealed with a sealing material. ,
A magnetic shield layer for magnetically shielding the memory element; and a joined body of at least heat radiating means for radiating heat generated by the memory element;
The joined body is provided in contact with the surface of the sealing material,
The present invention relates to a magnetic memory device, and a memory element having a magnetizable magnetic layer is sealed with a sealing material,
A magnetic shield layer for magnetically shielding the memory element; and a joined body of at least heat radiating means for radiating heat generated by the memory element;
The joined body is provided in contact with the surface of the sealing material,
It also relates to a magnetic memory device.

  Further, the magnetic memory device may be mounted on a mounting substrate, and the magnetic shield device and / or the heat dissipation unit may be in contact with the mounting substrate.

  According to the magnetic memory device of the present invention, the magnetic shield layer and the heat dissipating means can be provided together by attaching the magnetic shield layer and the heat dissipating means integrally. Cost reduction can be achieved. Here, paying attention to the fact that the magnetic random access memory (MRAM) or the like is mainly used as a package molded with the sealing material such as resin, the magnetic shield layer and / or the heat dissipation means are molded. The magnetic shield layer and the heat dissipating means can be easily mounted by attaching them to the surface of the package with an adhesive or the like, and can also be made removable. This package has a suitable structure and shape even when mounted on a circuit board.

  At this time, the magnetic shield layer can be processed into a shape effective for the magnetic shield and fixed at a predetermined position, so that a high-performance magnetic shield can be easily realized. In addition, it is noted that the material constituting the magnetic shield layer is a material that is relatively excellent in thermal conductivity, and by utilizing the magnetic shield layer as a part of the heat dissipation means, heat transfer efficiency is improved. , Can promote the dissipation of heat. In addition, the heat dissipating means can be configured with a minimum number of members, which is advantageous for downsizing and cost reduction.

  Usually, heat generated in the memory element or the like sealed with the sealing material is mainly dissipated through two paths. The first path is a path through which heat is radiated from a die pad or the like on which the memory element is mounted to a wiring part or the like of the mounting substrate through a lead part due to heat conduction. The second path is a path through which heat transferred to the surface of the package through the sealing material around the memory element is dissipated by convection heat transfer of air around the package or radiant heat transfer from the package surface. is there. Since the magnetic shield layer is provided on the surface of the package close to the memory element, the heat radiating means provided integrally joined to the magnetic shield layer is provided from the memory element to the magnetic shield layer. The heat flow and / or the heat flow dissipated from the magnetic shield layer to the outside can be promoted, and the heat dissipation efficiency by the second path can be effectively increased.

  Further, the mounting structure of the magnetic memory device of the present invention creates a new heat dissipation path from the memory element to the mounting substrate, and can effectively assist the heat dissipation from the magnetic memory device. Structure.

  In the present invention, in order for the magnetic shield layer to exert its magnetic shielding effect effectively, the joined body is preferably provided in contact with the upper surface and / or the lower surface of the sealing material. It is particularly preferable that a sandwich structure is sandwiched from above and below by the magnetic shield layer.

  Further, as a condition for the magnetic shield layer to hardly cause magnetic saturation, the magnetic shield layer may have a shape in which the distance between the opposing sides is 15 mm or less.

  In the case where the magnetic random access memory or the magnetic memory is mixedly mounted on a substrate together with other elements and sealed, in order to suppress magnetic saturation of the magnetic shield layer, an upper area area occupied by the memory element and It is preferable to provide the magnetic shield layer only at the lower part. Even in such a case, it is preferable that the heat dissipating means is provided on substantially the entire upper surface and / or lower surface of the sealing material so that heat is radiated from the package surface to the maximum extent.

  The mechanism for transferring heat from an object is roughly divided into heat conduction, convection heat transfer, radiant heat transfer, and combinations thereof. When there is no special heat radiating means such as a heat sink, the heat generated in the memory device such as the MRAM sealed with the sealing material is usually dissipated mainly through the two paths described above.

  The first path is a path related to the basic structure of an element such as wiring, and is difficult to modify. On the other hand, the second path can be improved relatively easily, and the heat dissipating means made of a material and / or shape excellent in thermal conductivity can disperse the heat as evenly as possible over the entire surface of the package, and the convection heat transfer Or it is good to dissipate efficiently by the said thermal radiation means which consists of a material and / or shape which was excellent in radiant heat transfer.

Examples of the material having excellent thermal conductivity include metals and high thermal conductive ceramics. For example, metal such as aluminum (Al), copper (Cu), copper tungsten (Cu—W) alloy, aluminum oxide (alumina, Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN), silicon nitride Examples thereof include high thermal conductive ceramics such as (Si ₃ N ₄ ) and silicon carbide (SiC), Cu (or Al) -SiC alloy, Cu (or Al) -carbon (C) alloy, and the like. However, it is not limited to these.

  Further, the shape of the surface of the heat dissipation means or the magnetic shield layer is a convenient shape for increasing the contact area with air, promoting convection of the air layer, and increasing the heat dissipated to the air layer. Desirably, for example, one having a large number of grooves formed in parallel or in a lattice shape on the surface, or one having a porous surface on which a large number of irregularities and holes are formed is preferable.

  Moreover, it is desirable that the surface of the heat dissipation means or the magnetic shield layer is processed to increase the emissivity. For example, when the heat radiating means is made of aluminum, the emissivity can be increased by black anodizing the surface. In addition, a paint having a high emissivity of about 0.8 to 0.96 containing carbon black, ceramics such as oxide and carbide, etc. as a material that is easily provided and has excellent radiant heat transfer ( Hereinafter, it is referred to as a thermal radiation paint) (see JP 2002-226783 A and JP 6-7508 A). The emissivity from the surface can be increased by applying this thermal radiation coating to the surface of the heat dissipation means or the magnetic shield layer. Note that commercially available spray paints often contain ceramic materials having high emissivity, and these paints may be used. In this case, the color may be not only black but also white, red, blue, etc., and is not limited.

  The soft magnetic material forming the magnetic shield layer may be made of a soft magnetic material having high saturation magnetization and high permeability containing at least one of Fe, Co, and Ni. More specifically, materials for forming the magnetic shield layer include pure iron, Fe—Ni, Fe—Co, Fe—Ni—Co, Fe—Si, Fe—Al—Si, and Examples thereof include ferrite. Among them, it is a matter of course to have a certain permeability, but a material having a high saturation magnetization that does not easily saturate with respect to an external magnetic field is desirable.

  As such a material, a material having a saturation magnetization of 1.8 Tesla (T) or more as disclosed in Japanese Patent Application No. 2002-357807, in particular, Si: 2 to 4% by mass, Fe: remaining alloy , Co: 47-50 mass%, Fe: balance alloy, Co: 35-40 mass%, Fe: balance alloy, Co: 23-27 mass%, Fe: balance alloy, and Co: 48-50 mass %, V: 1 to 3% by mass, Fe: at least one soft magnetic material selected from the group consisting of the remaining alloys is desirable.

  In addition to the magnetic shield layer having a flat film shape or plate shape, in order to more effectively suppress the magnetic saturation, a film shape or plate shape with unevenness, or a mesh or slit is used. It is good to have a shape with a through hole. These shapes are also advantageous in increasing the contact area with air and increasing the heat dissipated into the air.

  The present invention is suitable for an MRAM. In such an MRAM, an insulator layer or a conductor layer is sandwiched between the magnetization fixed layer and the magnetic layer, and provided on the upper surface and the lower surface of the memory element. Information is written by magnetizing the magnetic layer in a predetermined direction by a magnetic field induced by passing currents through the wirings as the bit line and the word line, and this write information is used for the tunnel magnetoresistance effect (TMR effect) between the wirings. ).

  In the mounting structure on the mounting substrate, a thermal via may be provided through the mounting substrate, and the magnetic shield layer and / or the heat radiating means may be in contact with the via. It is preferable that heat dissipating means connected to the thermal via is provided on the surface (rear surface) of the mounting substrate opposite to the device. By such a thermal via and the heat dissipation means connected thereto, heat flow to the mounting substrate is promoted, and heat can be effectively radiated to the back side beyond the mounting substrate. .

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

Embodiment 1
FIG. 1 is a schematic diagram illustrating an MRAM element-containing semiconductor package according to the first embodiment, in which a magnetic shield layer 34 is attached to the upper surface of a sealing material 33 and a heat spreader 41 is bonded to the entire surface as a heat dissipation means. It is sectional drawing. Here, the heat spreader is a member made of a material having high thermal conductivity and reducing the temperature of a heating element such as an IC (Integrated Circuit) by dispersing heat.

  In the MRAM package shown in FIG. 1, the MRAM element (chip including the memory cell portion and peripheral circuit portion) 30 shown in FIGS. 15 to 17 is provided on the die pad 32 and connected to the mounting substrate 38. The entire portion excluding the lead 31 is sealed and packaged by a sealing material 33 such as a mold resin (for example, epoxy resin) (here, the MRAM element 30 has the same structure and structure as the MRAM described above). The explanation is omitted because it has an operating principle, and the lead frame including the die pad 32 is shown in a simplified manner, which is the same in the second to fourth embodiments described later.) .

  The magnetic shield layer 34 and the heat spreader 41 are fixed to a predetermined position on the upper surface of the sealing material 33 with an adhesive or the like after sealing with the sealing material 33 (after molding). The thickness of the magnetic shield layer 34 is about 100 to 500 μm, and the thickness of the heat spreader 41 is about 20 to 1000 μm. As described above, the magnetic shield layer 34 and the heat spreader 41 having the most effective shape for the structure can be easily provided by simply mounting the magnetic shield layer 34 and the heat spreader 41 in a later process after the package is manufactured.

  The package of FIG. 1 has a magnetic shield layer 34 and a heat spreader 41 integrated with an MRAM package, and is a desirable structure for mounting on a mounting board (circuit board) 38. Further, the magnetic shield layer 34 and the heat spreader 41 may be easily attached and detached.

  No underfill material is provided on the lower surface side of the package for heat dissipation to the air. Although not shown, if there is a space on the lower surface side of the package, a magnetic shield layer and a heat spreader are provided also on the lower surface of the sealing material 33, and the MRAM package is sandwiched between the magnetic shield layer and the heat spreader (sandwich structure). It is good to do. Thereby, a more reliable magnetic shielding effect and an improved heat dissipation effect are achieved.

  In both the case where the magnetic shield layers are provided on both upper and lower surfaces of the package and the case where the magnetic shield layers are provided only on the upper surface as shown in FIG. The For example, the magnetic shield layer 34 does not form a closed magnetic circuit with the outside, but still effectively collects an externally applied magnetic field and functions as a magnetic shield for the MRAM element 30.

  The role of the heat spreader 41 in the present embodiment is to assist the thermal conductivity of the magnetic shield layer 34 to disperse the heat as uniformly as possible, improve the heat dissipation efficiency, and partially increase the temperature of the MRAM element 30 to a high temperature. It is to prevent becoming.

Therefore, as the material of the heat spreader 41, a material having excellent thermal conductivity, that is, a metal such as aluminum (Al), copper (Cu), copper tungsten (Cu—W) alloy, aluminum oxide (alumina, Al ₂ O, etc.). ₃ ), high thermal conductive ceramics such as aluminum nitride (AlN), boron nitride (BN), silicon nitride (Si ₃ N ₄ ), silicon carbide (SiC), Cu (or Al) -SiC alloy, Cu (or Al ) -Carbon (C) alloy is preferred.

  The surface shape of the heat spreader 41 is preferably a shape that is convenient for increasing the contact area with air, promoting convection of the air layer, and increasing the heat dissipated into the air layer. Are preferably formed in parallel or in the form of a lattice, or have a porous surface on which a large number of irregularities and holes are formed. Further, as will be described later, a heat radiation coating or the like excellent in radiant heat transfer may be applied to the surface.

Embodiment 2
FIG. 2 is a schematic cross-sectional view illustrating the mounting structure of the MRAM package based on the second embodiment. In the present embodiment, the MRAM package has magnetic shield layers 34 and 35 on both upper and lower surfaces of the package, and is configured such that heat reaching the magnetic shield layer 35 can be dissipated through the mounting substrate 38. 2A shows an example in which the lower magnetic shield layer 35 is in direct contact with the mounting substrate 38, and FIG. 2B shows that the lower magnetic shield layer 35 is mounted via the heat spreader 42. An example in which the substrate 38 is thermally coupled is shown. The upper magnetic shield layer 34 is provided with a heat spreader 41 as in the first embodiment.

  As shown in FIG. 2A, even when the magnetic shield layer 35 is simply in contact with the mounting substrate 38, the heat of the MRAM package can easily escape to the mounting substrate 38. At this time, since the material of the magnetic shield layer 35 is a material having a higher thermal conductivity than the resin or the like that is the material of the package sealing material 33, the magnetic shield layer 35 serves not only as a magnetic shield but also as a heat conductive material. In addition, heat easily escapes to the mounting board 38.

  FIG. 2B shows an example in which the heat conductivity of the magnetic shield layer 35 is supplemented by the heat spreader 42 and the heat dissipation effect is further improved.

  FIGS. 3A and 3B respectively show the MRAM package through the thermal via 43 formed in the mounting structure shown in FIGS. 2A and 2B by forming a thermal via 43 penetrating the mounting substrate 38. This is an example in which a heat spreader 44 that is thermally coupled to the underside of the mounting substrate 38 is added.

  In the mounting structure shown in FIGS. 3A and 3B, the thermal via 43 and the heat spreader 44 promote the heat flow to the mounting board 38 and also dissipate heat to the back side beyond the mounting board 38. Can be effectively performed.

The material of the heat spreaders 42 and 44 and the thermal via 43 is, like the heat spreader 41, a metal having a high thermal conductivity or a high thermal conductive ceramic. Specifically, the materials described in the first embodiment, that is, aluminum ( Al), copper (Cu), copper tungsten (Cu-W) alloy and other metals, aluminum oxide (alumina, Al ₂ O ₃ ), aluminum nitride (AlN), boron nitride (BN), silicon nitride (Si ₃ N) ₄ ), high thermal conductive ceramics such as silicon carbide (SiC), Cu (or Al) -SiC alloy, Cu (or Al) -carbon (C) alloy and the like are preferable.

  Further, the surface of the heat spreader 41 or 44 is advantageous for increasing the heat dissipated into the air layer by increasing the contact area with the air and promoting the convection of the air layer, as described in the first embodiment. The shape is desirable, and for example, one having a large number of grooves formed in parallel or in a lattice shape on the surface, or one having a porous surface on which many irregularities and holes are formed is preferable. Further, as will be described later, a heat radiation coating or the like excellent in radiant heat transfer may be applied to the surface.

  The thermal via 43 is preferably formed by through-hole plating or application of copper or silver paste.

Embodiment 3
4 and 5 are respectively a plan view (FIG. 4) showing an example of the MRAM package based on the third embodiment and a schematic cross-sectional view taken along the line AA (FIG. 5) (however, in FIG. The heat spreader provided on the entire upper surface is not shown for easy understanding of the structure.) The MRAM package according to the present embodiment includes DRAM, EPROM (Erasable and Programmable Read Only Memory), MPU (Micro Processing Unit), DSP (Digital Signal Processor), RF (Radio Frequency) element, etc. in addition to the MRAM element 30. The other element 39 is a SIP (System In Package) that is mixedly mounted on the die pad 32 and sealed by the sealing material 33. This may be an SOC (System On Chip) in which each element is built on the same substrate.

  The MRAM element 30 is usually mounted on a substrate after being resin-sealed in a package such as QFP (Quad Flat Package), SOP (Small Outline Package), etc., and is put to practical use. The size is almost determined by the standard depending on the number of pins. For example, a device having 48 pins is called QFP-48PIN. The MRAM element is a non-volatile memory element, and a multi-pin package is required. In the case of an MRAM element having a storage capacity of 1 Mbit class, it is necessary to use a package of about QFP160PIN or QFP208PIN. FIG. 4 shows an example of the QFP package.

  As disclosed in Japanese Patent Application No. 2002-363199, in an MRAM element mixed package in which MRAM elements are mounted in a part of a semiconductor package, a magnetic shield layer is provided on the entire upper and / or lower part of the package. Thus, it is clear that it is more effective to partially provide a magnetic shield layer only in the upper part and / or lower part of the region where the MRAM element is mounted. The reason will be described below.

  In order to guarantee the normal operation of the MRAM element, it is necessary to reduce the magnetic field strength to 10 to 20 Oe or less at least in the MRAM element portion even when a large DC external magnetic field of 500 Oe is applied. The following experiment was conducted for the purpose of obtaining such magnetic shielding performance.

  FIG. 6A is a schematic sectional view thereof. In the experiment, two sheets (one side length Lmm, thickness t = 200 μm) made of a magnetic shield material are arranged in parallel at a distance d of 3.45 mm as magnetic shield layers 51 and 52, and two magnetic sheets are formed. A gauss meter 54 is arranged at the center in the vertical direction of the internal space 53 sandwiched between the shield layers 51 and 52. Then, while applying an external DC magnetic field of 500 Oe in parallel to the magnetic shield layers 51 and 52, the measurement position of the gauss meter 54 is moved from the sheet end to the center in the surface direction of the sheet, and the internal magnetic field strength (intrudes into the internal space 53). Measured magnetic field strength) and studied the material and shape of an effective magnetic shield layer.

For example, as a magnetic shield material, FeCoV having a saturation magnetization M _s = 2.3 T and an initial permeability μ _i = 1000 is used, and the length L of one side of the magnetic shield layers 51 and 52 is set to 10, 15, 20, and 28 mm. For the four types of samples, the internal magnetic field strength under an externally applied magnetic field strength of 500 Oe was measured. FIG. 6B shows a graph in which the internal magnetic field strength is plotted against the distance from the end.

  According to the graph of FIG. 6B, the magnetic field strength at the center is large in the sample having a side length of 28 mm or 20 mm. This is because magnetic saturation occurs near the center of the magnetic shield layer 51 (or 52), and the shielding effect is not sufficiently exhibited. On the other hand, in a sample having a side length of 15 mm or 10 mm, the magnetic field strength is sufficiently low to the center and is 10 to 20 Oe or less.

  Thus, the magnetic saturation of the magnetic shield layer is more likely to occur in the center in the plane direction, and the region where the shield effect of the magnetic shield layer effectively acts is limited by the magnetic saturation phenomenon of the magnetic shield layer, the characteristics of the magnetic material, It became clear that the thickness was determined by the length of one side.

  For example, in order to shield a high magnetic field strength of 500 Oe or more using FeCoV as the magnetic shield layer, when the thickness is 200 μm, the length of one side of the magnetic shield layers 51 and 52 (or the distance between the opposing sides) ) Of 15 mm or less, the shielding effect is effective even at the central portion in the surface direction, and can be used as a magnetic shield layer of the MRAM element. When the thickness is 150 μm, the same effect can be expected if the length of one side of the magnetic shield layer is 10 mm or less.

  However, even if the length of one side of the magnetic shield layer is too short, the external magnetic field that enters the internal space 53 from the opening increases, and the magnetic shield effect becomes poor. Accordingly, the length of one side (or the distance between the opposing sides) of the magnetic shield layer is preferably 3 mm or more, more preferably 5 mm or more, taking the size of the MRAM element into consideration.

  Considering the external magnetic field that enters the internal space 53 from the opening, if the length of one side of the magnetic shield layer is 10 mm, the effective magnetic shield region is a region having a side length of about 8 mm. Even if the MRAM element is of the 1 Mbit class, it is usually a few mm square size. Therefore, if the magnetic shield layer has a side length of 10 mm, the MRAM element can be formed without any problem by being disposed in the above-mentioned region. Can be magnetically shielded from an external magnetic field.

  As described above, in the MRAM element mixed package in which the MRAM element is mounted in a partial region in the semiconductor package, if the magnetic shield layer is provided only in the area occupied by the MRAM element 30, the size of the magnetic shield layer is reduced to one side. Can be made 15 mm or less, preferably 10 mm or less, and the magnetic saturation of the magnetic shield layer can be effectively suppressed to exhibit a sufficient magnetic shield effect. On the other hand, as shown in the above-mentioned Patent Document 2 (US Pat. No. 5,939,772), when a magnetic shield layer is provided on the entire upper and / or lower part of the package, the size exceeds 15 mm per side, and the magnetic shield layer Magnetic shield performance deteriorates due to the magnetic saturation phenomenon at the center. Therefore, it is desirable to provide the magnetic shield layer with a minimum and sufficient size only in the area occupied by the MRAM element 30.

  On the other hand, from the viewpoint of heat dissipation, it is necessary to dissipate heat from the package efficiently by quickly dispersing the heat generated in the MRAM element uniformly over the entire surface of the MRAM package and increasing the heat dissipation area.

  Therefore, in the MRAM element mixed package, as shown in FIG. 5A, the magnetic shield layers 34 and 35 are provided only in the area occupied by the MRAM element 30, while the heat spreaders 45 and 46 are formed on the upper surface of the molded MRAM package. It is good to provide on substantially the entire lower surface.

  Further, in order to suppress the overall thickness, as shown in FIG. 5B, a molded body in which the magnetic shield layer 34 and the heat spreader 47 covering only the area occupied by the MRAM element 30 are integrally formed in advance in a plate shape. It may be prepared and affixed to the package. In this molded body, the surface of the magnetic shield layer 34 may be exposed, or may be covered with a heat spreader 47 as shown in FIG. For example, when the heat spreader 47 is made of ceramics, the emissivity of the magnetic shield layer 34 is about 0.2 or less, whereas the emissivity of the heat spreader 47 is 0.6 to 0.7, which is much larger. The radiant heat transfer characteristics can be improved by simply covering the surface of 34 thinly.

  Here, the first role that the heat spreaders 45 to 47 should play is to quickly disperse the heat generated in the MRAM element uniformly over the entire surface of the MRAM package, so that the material is a metal having excellent thermal conductivity. And high thermal conductive ceramics, specifically, the materials described in Embodiment 1 are preferable. Further, the surfaces of the heat spreaders 45 to 47 are advantageous in increasing the contact area with the air, promoting the convection of the air layer, and increasing the heat dissipated into the air layer, as described in the first embodiment. The shape is desirable, and for example, one having a large number of grooves formed in parallel or in a lattice shape on the surface, or one having a porous surface on which many irregularities and holes are formed is preferable. Further, as will be described later, a heat radiation coating or the like excellent in radiant heat transfer may be applied to the surface.

  By adopting the structure as described above, the MRAM element mixed package can achieve both good magnetic shielding performance and heat dissipation performance.

Embodiment 4
FIG. 7A is a schematic cross-sectional view illustrating an MRAM package based on the fourth embodiment. In this MRAM package, magnetic shield layers 34 and 35 are provided on the upper and lower surfaces of the package, the upper magnetic shield layer 34 is provided with a heat spreader 41 as in the first embodiment, and a thermal radiation paint is provided on the surface thereof. The heat radiation material coating layer 48 is formed by the application of.

  As described above, from the package surface, heat transferred to the air layer in contact with the package surface is dissipated by convective heat transfer that is carried away by air convection, and infrared rays are radiated from the package surface. Heat release by radiant heat transfer from which heat is released is performed. If the surface temperature of the package is not so high compared to room temperature, heat dissipation by convective heat transfer is dominant, but the amount of heat released by thermal radiation increases rapidly as the temperature difference from the ambient temperature increases. As the value increases, the contribution of radiant heat transfer increases.

  The amount of heat released by thermal radiation increases in proportion to the heat dissipation area and emissivity, in addition to temperature. However, a material having luster such as metal has a very low emissivity of about 0.02 to 0.3. Therefore, in the present embodiment, by increasing the emissivity of the surfaces of the magnetic shield layer 34 and the heat spreader 41, heat dissipation by radiant heat transfer is promoted.

  FIG. 7A shows an example in which the heat radiating material coating layer 48 is formed by applying a heat radiating paint to the surface of the heat spreader 41. As another method, for example, when the heat spreader is made of aluminum, the emissivity can be increased by performing black alumite treatment. A commercially available spray paint or the like may be used instead of the heat radiation paint.

  If the coating film of the heat radiation paint becomes too thick, the heat radiation paint has a low thermal conductivity, so that heat dissipation may be reduced. Accordingly, the thickness of the coating film is desirably in the range of 10 μm to 100 μm. The same applies to the following examples.

  In FIG. 7B, the magnetic shield layers 34 and 35 are provided on the upper and lower surfaces of the package, the heat spreader 41 is not provided on the upper magnetic shield layer 34, and a heat radiation coating is directly applied to the surface of the magnetic shield layer 34. This is an example in which a thermal radiation material coating layer 48 is provided. This is a structure that can be applied when the heat spreader 41 is not provided because the package becomes too thick. By this treatment, the emissivity of the magnetic shield layer 34 can be improved from about 0.2 to about 0.9. Since the thermal conductivity of the magnetic shield layer 34 is about 14 to 40 W / mk, which is higher than the thermal conductivity of the resin package, the magnetic shield layer 34 functions as a heat spreader, and has excellent radiation by improving the emissivity. It also plays the role of a heat transfer material, increasing the overall heat dissipation efficiency.

  Although illustration is omitted, the heat radiating material coating layer 48 may be provided by applying a heat radiating paint on the surfaces of the heat spreaders 41, 45 to 47 and the magnetic shield layers 34 and 35 described in the first to third embodiments. Good.

  FIG. 8 is a schematic sectional view showing another example of the MRAM package based on the fourth embodiment. In this MRAM package, the magnetic shield layers are provided on both the upper and lower surfaces of the package. However, when the magnetic shield layer is the magnetic shield layer 36 having irregularities on the surface (a), or through holes such as nets and slits are provided. In the case (b), the surface of the magnetic shield layer 37 is coated with a heat radiation paint to form a heat radiation material coating layer 48.

  The magnetic shield layer 36 or 37 having such a shape generates a demagnetizing field with respect to an externally applied magnetic field due to shape anisotropy not only at the peripheral end portion but also at the concave and convex portions and the through-hole portion, and is not easily saturated. It has a characteristic shielding effect. The magnetic shield layer having such a shape can be prepared in the most effective shape and size for the magnetic shield, and can be easily fixed to the package with an adhesive or the like.

  Moreover, since the surface area is increased, the effect of heat dissipation by convective heat transfer and radiant heat transfer is also enhanced. Furthermore, since the thermal radiation material coating layer 48 is formed on the surface, the emissivity can be improved from about 0.2 to about 0.9, and the heat radiation by radiant heat transfer is improved.

Embodiment 5
In the first to fourth embodiments described above, the magnetic shield layer is provided in contact with the surface of the package and the heat spreader is provided on the outside thereof. However, in the present embodiment, the heat spreader is provided in contact with the surface of the package. An example in which a magnetic shield layer is provided on the outer side will be described.

  When arranged in this manner, the heat spreader having excellent thermal conductivity is provided at a position closer to the heat generation source, and thus there is an advantage that the action of the heat spreader that dissipates heat is more effectively exhibited. Further, as described above in the third embodiment, the size of the magnetic shield layer may be limited in order to enhance the magnetic shield effect. However, since the heat spreader has no such limitation, as described above. When arranged, the shape may be easier to manufacture.

  FIG. 9 shows a case where the present embodiment is applied to a SIP in which the MRAM element 30 described in the third embodiment is mixedly mounted with other elements 39, and heat spreaders 45 and 46 are provided on substantially the entire upper and lower surfaces of the package. This is an example in which the magnetic shield layers 34 and 35 are provided only in the upper and lower portions of the region where the MRAM element 30 is mounted.

  As the material of the heat spreaders 45 and 46, as in the above example, a metal having excellent thermal conductivity or a high thermal conductive ceramic is preferable. However, in the case of manufacturing using copper or aluminum, a method such as plating or vapor deposition is used. It can also be formed.

  The thickness of the heat spreader must be limited to a range that does not adversely affect the shielding effect of the magnetic shield layer, although the heat spreading effect is better as the thickness is larger. Therefore, in order to clarify an appropriate interval between the magnetic shield layers, the following examination was performed.

  That is, as already described with reference to FIG. 6A, a pair of magnetic shield layers 51 and 52 are arranged to face each other, an external magnetic field is applied, and the magnetic field strength entering the internal space 53 is measured. . At this time, the distance d between the magnetic shield layers was changed while the length of one side was fixed at 15 mm, and the change in the magnetic field strength at that time was measured, and the result shown in FIG. 10 was obtained. In the experiment, the magnetic shield layers 51 and 52 were formed of an Fe—Co—V alloy, the thickness of the magnetic shield layer was 200 μm, and the externally applied magnetic field strength was 500 Oe.

  From the results shown in FIG. 10, when the distance between the two magnetic shield layers 34-35 disposed on the upper and lower surfaces of the package exceeds 3.0 mm, the magnetic field strength entering the inside increases rapidly, and the allowable magnetic field strength of the MRAM is increased. Therefore, when forming a magnetic shield layer having one side of 15 mm, it is necessary to suppress the distance between the pair of magnetic shield layers to 3 mm or less.

  From the above, when the heat spreaders 45 and 46 are mounted inside the magnetic shield layers 34 and 35, it is desirable that the thickness of the heat spreader is such that the interval between the magnetic shield layers does not exceed 3 mm.

  FIG. 11 shows the present embodiment when the magnetic shield layer is a magnetic shield layer 36 having irregularities on the surface (a), or when the magnetic shield layer 37 is a magnetic shield layer 37 having a net-like or slit-like through hole (b). It is a schematic sectional drawing of the MRAM package to which is applied. Although illustration is omitted, as in the fourth embodiment, a heat radiation coating layer 48 may be formed on the surfaces of the magnetic shield layers 36 and 37 by applying a heat radiation paint.

  Hereinafter, as a preferred embodiment of the present invention, as shown in FIG. 12 (C), a magnetic multi-chip module (MCM) including an MRAM element is provided with magnetic shield layers 34 and 35 and a heat radiation material coating layer 48. An example in which the heat dissipation effect and the magnetic shielding effect are examined will be described.

  The size of the MCM was 30 mm in length and width, and the thickness was 3.5 mm, and an MRAM was provided at the center position inside. Magnetic shield layers 34 and 35 made of Fe—Si were provided at the center between the upper and lower surfaces so as to sandwich the MRAM in a sandwich shape. Its size is 14 mm in length and width, and 350 μm in thickness. A heat radiation coating was applied to the surfaces of the magnetic shield layers 34 and 35 to form a heat radiation material coating layer 48. 12A and 12B show comparative samples.

  FIG. 12 is a graph showing the relationship between the power consumption of the MRAM in the MCM and the temperature rise from room temperature. The measurement was performed according to A. For MCM only, B. When the magnetic shield layers 34 and 35 are provided on the upper and lower surfaces of the MCM, C.I. The test was performed in three states when the heat radiation material coating layer 48 was formed on the surfaces of the B magnetic shield layers 34 and 35. The temperature measurement position 60 is the center of the upper surface of the MCM in A, the center of the upper surface of the magnetic shield layer 34 in B, and the center of the upper surface of the magnetic shield layer 34 on which the thermal radiation coating layer 48 is formed in C. .

  As shown in FIG. 12, if the power consumption is the same, the degree of temperature increase from room temperature is A> B> C at any power consumption. One reason why the temperature rise of B is lower than that of A is considered to be that the heat from MRAM is dispersed by the Fe—Si magnetic shield layer 34 having good thermal conductivity, and the magnetic shield layer itself is part of the heat dissipation means. It can function as. The reason why the temperature rise of C is lower than that of B is considered to be the result of the heat radiation material accelerating the heat radiation by the radiant heat transfer.

  FIG. 13 is a comparison of the degree of temperature rise when power consumption is fixed at 1.0 W and various heat dissipation means are combined. From FIG. 13, it was found that a sufficient heat radiation effect can be expected by combining the magnetic shield layer and heat radiation means such as a heat spreader or a heat radiation material coating layer. In particular, by adopting the heat radiation means, the magnetic shield layer can always be kept below the Curie temperature and its magnetic characteristics can be maintained.

  FIG. 14 is a graph showing measured values of the internal magnetic field in the MCM. The Fe—Si magnetic shield layers 34 and 35 are 14 mm in length and width, 135 μm in thickness (FIG. 14A) or 270 μm (FIG. 14B), and the externally applied magnetic field is 100 Oe. In any case, the external magnetic field penetrates to the inside of about 4 mm from the end, but the magnetic field is sufficiently small in the region of distance of 4 to 10 mm from the left end, which is the size of a normal MRAM element. Considering that the length is about 5 mm each in length and width, it is considered that sufficiently good shield characteristics were obtained. Since magnetic flux concentrates at both ends of the magnetic shield layer, a magnetic field of 100 Oe or more is measured at both ends.

  According to the embodiments and examples of the present invention described above, it is possible to increase the heat radiation efficiency while magnetically shielding and protecting the MRAM element against a large external magnetic field. By using the present invention, it is possible to provide an environment in which operation can be ensured without problems with respect to a magnetic field from an environment to which an MRAM element is applied, and it is easy to mount and install a magnetic shield layer and a heat dissipation means. Therefore, it is possible to simplify the mounting process regarding the shield and the heat dissipation material. In addition, since the present invention can be applied to a mounting form such as SIP or SOC, it is a technique applicable to most of the environments where the MRAM is used.

  Although the present invention has been described based on the embodiments and examples, it is needless to say that the present invention is not limited to these examples and can be appropriately changed without departing from the gist of the invention. .

  For example, the composition and type of the above-described highly saturated magnetization material, the thickness and arrangement of the magnetic shield layer, the structure of the MRAM, and the like may be variously changed.

  The present invention is suitable for an MRAM, but can also be applied to other magnetic memory devices including a memory element having a magnetizable magnetic layer.

  MRAM is considered to be indispensable in the ubiquitous era as a high-speed and non-volatile large-capacity memory, and it is considered that all electronic devices, in particular, higher speed, lower power consumption, higher integration, etc. It is suitable for information communication equipment for which performance enhancement is required, particularly for personal small equipment such as a portable terminal.

  The present invention makes it possible to easily install a magnetic shield layer that magnetically shields and protects a memory element having a magnetizable magnetic layer such as an MRAM element from an external magnetic field, and a heat dissipation means with improved heat dissipation efficiency. This is an invention of a technology indispensable for practical use of an MRAM element or the like. In addition, since it can be applied to mounting forms such as SIP and SOC, it is a technology that can be applied to most of the environments where the MRAM is used, and contributes to the reduction in size and weight of electronic devices.

It is a schematic sectional drawing of the MRAM package based on Embodiment 1 of this invention. It is a schematic sectional drawing which shows the mounting form of the MRAM package based on Embodiment 2 of this invention. It is a schematic sectional drawing which shows the other mounting form of an MRAM package equally. It is a top view of the MRAM package based on Embodiment 3 of this invention. 2 is a schematic cross-sectional view of the MRAM package. FIG. The relationship between the schematic cross-sectional view (a) when measuring the magnetic field strength of the internal space sandwiched between the two magnetic shield layers, the size of the magnetic shield layer, and the internal magnetic field strength caused by the penetration of the externally applied magnetic field. It is a graph (b) shown. It is a schematic sectional drawing of the MRAM package based on Embodiment 4 of this invention. It is a schematic sectional drawing which shows the other example of an MRAM package same as the above. It is a schematic sectional drawing of the MRAM package based on Embodiment 5 of this invention. FIG. 6 is a graph showing the relationship between the size of the gap between magnetic shield layers and the internal magnetic field strength generated by the penetration of an externally applied magnetic field. It is a schematic sectional drawing which shows the other example of an MRAM package same as the above. It is a graph which shows the relationship between power consumption and the temperature rise degree in MCM of the Example of this invention. It is a graph which shows the relationship between the combination of a thermal radiation means, and a temperature rise degree similarly. It is a graph which shows the actual value of the internal magnetic field intensity produced by penetration | invasion of the externally applied magnetic field similarly. It is a schematic perspective view of the TMR element of MRAM. It is a schematic perspective view of a part of the memory cell portion of the MRAM. It is a schematic sectional drawing of the memory cell of MRAM. It is an equivalent circuit diagram of MRAM. It is a magnetic field response characteristic figure at the time of writing of MRAM. It is a read operation principle diagram of MRAM.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Topcoat layer, 2 ... Memory layer, 3 ... Tunnel barrier layer, 4 ... 1st magnetization fixed layer,
5 ... antiferromagnetic coupling layer, 6 ... second magnetization fixed layer, 7 ... antiferromagnetic material layer, 8 ... underlayer,
9 ... support substrate, 10 ... memory cell (TMR element), 11 ... bit line,
12 ... word line for writing, 13 ... silicon substrate, 14 ... well region,
15 ... Gate insulating film, 16 ... Gate electrode, 17 ... Source region, 18 ... Drain region,
19: Read-out field effect transistor (selection transistor), 20: Source electrode,
21... Sense line, 21 b... Sense amplifier, 22.
23 ... Drain electrode, 24 ... Word line current drive circuit, 25 ... Bit line current drive circuit,
26 ... Magnetization fixed layer, 30 ... MRAM element (embedded TMR element), 31 ... External lead,
32 ... Die pad, 33 ... Sealing material, 34, 35 ... Magnetic shield layer,
36 ... Magnetic shield layer having irregularities, 37 ... Magnetic shield layer having through holes,
38 ... mounting substrate, 39 ... other elements,
41, 42, 44 to 47 ... heat spreader, 43 ... thermal via,
48 ... thermal radiation material coating layer, 51, 52 ... magnetic shield layer,
53 ... Internal space, 54 ... Gauss meter, 60 ... Temperature measurement position

Claims (14)

A magnetic random access memory including a memory element in which a magnetization fixed layer whose magnetization direction is fixed and a magnetic layer capable of changing the magnetization direction is stacked is sealed with a sealing material,
A magnetic shield layer for magnetically shielding the memory element; and a joined body of at least heat radiating means for radiating heat generated by the memory element;
The joined body is provided in contact with the surface of the sealing material,
Magnetic memory device. A memory element having a magnetizable magnetic layer is sealed with a sealing material,
A magnetic shield layer for magnetically shielding the memory element; and a joined body of at least heat radiating means for radiating heat generated by the memory element;
The joined body is provided in contact with the surface of the sealing material,
Magnetic memory device.   The magnetic memory device according to claim 1, wherein the joined body is provided in contact with an upper surface and / or a lower surface of the sealing material.   The magnetic random access memory or the magnetic memory is mixed and sealed on a substrate together with other elements, and at least the magnetic shield layer is provided above and / or below the area area occupied by the memory element. The magnetic memory device according to claim 1.   The magnetic memory device according to claim 4, wherein the heat radiating means is provided on substantially the entire upper surface and / or lower surface of the sealing material.   The magnetic memory device according to claim 1, wherein the magnetic shield layer has a shape in which a distance between opposite sides is 15 mm or less.   3. The magnetic memory device according to claim 1, wherein the heat radiating means is made of a material and / or shape that promotes heat dissipation by at least one of heat conduction, convection heat transfer, radiation heat transfer, and a combination thereof.   The magnetic memory device according to claim 7, wherein the heat radiating means is made of metal, high thermal conductive ceramics, or thermal radiation paint.   3. The magnetic memory device according to claim 1, wherein the soft magnetic material forming the magnetic shield layer is made of a soft magnetic material having high saturation magnetization and high permeability including at least one of Fe, Co, and Ni.   3. The magnetic memory device according to claim 1, wherein the magnetic shield layer has a flat or uneven film shape or plate shape, or a shape having a through-hole such as a mesh or a slit.   An insulator layer or a conductor layer is sandwiched between the magnetization pinned layer and the magnetic layer, and the magnetic layer is induced by a magnetic field induced by passing current through wirings provided on the upper surface and the lower surface of the memory element. The magnetic memory device according to claim 1, wherein information is written by magnetizing in a predetermined direction, and the written information is read by a tunnel magnetoresistive effect between the wirings.   A magnetic memory having a structure in which the magnetic memory device according to claim 1 is mounted on a mounting board, wherein the magnetic shield layer and / or the heat dissipation means are in contact with the mounting board. Device mounting structure.   The mounting structure of the magnetic memory device according to claim 12, wherein the magnetic shield layer and / or the heat radiating means are in contact with a thermal via provided through the mounting substrate.   The mounting structure for a magnetic memory device according to claim 13, wherein a heat radiating means connected to the thermal via is provided on a surface of the mounting substrate opposite to the magnetic memory device.

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