WO2022114172A1 - Structure de transfert de chaleur pour élément lsi et procédé de fabrication d'élément lsi ayant une telle structure de transfert de chaleur - Google Patents

Structure de transfert de chaleur pour élément lsi et procédé de fabrication d'élément lsi ayant une telle structure de transfert de chaleur Download PDF

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WO2022114172A1
WO2022114172A1 PCT/JP2021/043578 JP2021043578W WO2022114172A1 WO 2022114172 A1 WO2022114172 A1 WO 2022114172A1 JP 2021043578 W JP2021043578 W JP 2021043578W WO 2022114172 A1 WO2022114172 A1 WO 2022114172A1
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substrate
lsi
thin film
heat transfer
transfer structure
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PCT/JP2021/043578
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English (en)
Japanese (ja)
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光治 加藤
兆 嶋田
孝幸 古澤
幹土 砂入
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有限会社Mtec
アスカコーポレーション株式会社
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Publication of WO2022114172A1 publication Critical patent/WO2022114172A1/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/12—Mountings, e.g. non-detachable insulating substrates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L23/00—Details of semiconductor or other solid state devices
    • H01L23/28—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection
    • H01L23/29—Encapsulations, e.g. encapsulating layers, coatings, e.g. for protection characterised by the material, e.g. carbon

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  • the present invention relates to a heat transfer structure of an LSI element and a method of manufacturing an LSI element having the heat transfer structure. More specifically, the present invention relates to a heat transfer structure of an LSI element that transfers heat generated by an LSI by a metal substrate bonded to a Si thin film to the outside, and a method of manufacturing an LSI element having the heat transfer structure.
  • the operating temperature range of the LSI element using Si is approximately 150 ° C. or less at the PN junction temperature of the element. Therefore, how to transmit the heat generated in the LSI formed on the surface layer portion of Si to the outside is important.
  • FIG. 9A shows a mounting example of a conventional typical high-performance LSI.
  • a chip-sized LSI element 300 in which the LSI 100 is formed on the surface layer portion on the main surface (lower surface in the drawing) side of the silicon (Si) substrate 310 is mounted on the printed circuit board 200 by a face-down technique.
  • the heat generated by the LSI 100 is dissipated from the main surface of the face-down mounted LSI element 300 to the printed circuit board 200 via the face-down bonding terminal 120.
  • a first heat spreader 410 or the like having a heat distribution function is provided on the back surface side of the printed circuit board 200, and heat is radiated to the outside.
  • heat is radiated to the outside from the back surface (upper surface in the drawing) of the LSI element 300 by the second heat spreader 430 provided via the heat transfer material 420 such as the heat transfer sheet and the heat transfer gel. .. Since the printed circuit board 200 connected to the main surface side of the LSI element 300 is generally made of resin, the thermal conductivity is not good. By providing a metal hole (thermal via) for heat transfer penetrating the printed circuit board 200, heat conduction is improved, but the effect is limited. As the heat generated by the LSI 100 increases, it becomes important to transfer heat from the back surface side of the LSI element 300 to the second heat spreader 430 via the heat transfer material 420.
  • the second heat spreader 430 also serves as the control system terminal of the LSI 100 and the housing of the case, and has a structure that easily radiates the heat generated by the LSI to the outside.
  • FIG. 9B shows an example of face-down mounting of a high-performance LSI having a fan-out structure.
  • the heat generated by the LSI 100 is transferred to the printed circuit board 200 via the fan-out substrate 320, which is joined to the main surface side of the LSI element 300 to form fan-out wiring, and the face-down bonding terminal provided on the lower surface thereof. Then, it is radiated to the outside by the first heat spreader 410 or the like.
  • the second heat spreader 430 also serves as the control system terminal of the LSI 100 and the housing of the case, and has a structure that easily radiates the heat generated by the LSI to the outside. As the heat generated by the LSI 100 increases, it becomes important to transfer heat from the back surface side of the LSI element 300 to the second heat spreader 430 via the heat transfer material 420.
  • FIG. 10 shows the case where a heat dissipation fan is used.
  • the LSI element 300 is face-down mounted on the printed circuit board 200.
  • the heat generated by the LSI 100 is transferred to the printed circuit board 200 via the face-down bonding terminal and radiated to the outside from the first heat spreader 410 or the like.
  • the heat generated in the LSI 100 is radiated from the back surface side of the LSI element 300 to the outside air by using the heat dissipation fan 440. Since the thermal conductivity of the printed circuit board 200 is generally not good, it is important to transfer heat from the back surface side of the LSI element 300 to the heat dissipation fan 440 as the heat generation of the LSI 100 increases.
  • molybdenum having a high melting point is bonded to a metal at a high temperature of 1000 ° C., and bonding is performed by mutual diffusion of molybdenum and Si at the interface.
  • a method of metallizing the bonded surface of the Si substrate using high melting point solder and bonding it to the copper substrate at about 400 ° C is conceivable, but face-down bonding is performed by soldering at about 220 ° C. Soldering the Si substrate and the copper substrate requires soldering using high melting point solder, which has a higher temperature.
  • the practical temperature of the face-down mounted element is generally-. Since the temperature is about 40 ° C. to + 85 ° C., stress is generated due to the difference between the temperature at the time of joining and the temperature in the practical state, and warpage occurs. Further, due to the stress generated at the bonding interface, it is not preferable for the connection life and the element life of the connection interface.
  • the operating temperature of the LSI element is generally about -40 ° C to + 85 ° C. Therefore, stress is generated at the joining interface due to the difference between the temperature at the time of joining and the temperature in the practical state, and warpage occurs. Further, due to the stress generated at the bonding interface, it is not preferable for the connection life and the element life of the connection interface. In particular, the thinner the Si layer, the greater the effect on the element on the Si surface due to the internal stress generated at the bonding interface.
  • An object of the present invention is to provide a heat transfer structure of an LSI element that transfers heat generated in an LSI by a metal substrate bonded to a Si thin film to the outside, and a method of manufacturing an LSI element having the heat transfer structure.
  • the point of view for solving the above problems is to set the bonding temperature between the Si substrate and the metal substrate to a temperature within the operating temperature range of the LSI element in order to reduce the stress at the bonding interface.
  • the stress generated at the joining interface is small when the LSI element is used, and a good effect can be obtained on the device life and the interface joining life.
  • a temporary substrate is attached to the main surface side of the Si substrate after the LSI is formed, and the Si layer is formed to the limit where the LSI function can be created. Is to be thinly polished and then joined to a metal substrate.
  • the substrate portion should be made of a metal (copper) material having good thermal conductivity. It is in. As a result, the heat generated by the LSI is quickly transmitted to the copper substrate portion, and the heat can be transferred from the copper substrate portion to the external heat spreader.
  • the present invention is as follows. 1. 1. The first joining step of joining the main surface side of the Si substrate on which the LSI is formed on the surface layer and the temporary substrate, and A Si thin film step of forming a Si thin film by removing the back surface side of the Si substrate while leaving a thickness corresponding to the depth of the surface layer portion. A second joining step of joining the back surface of the Si thin film and the metal surface of the second substrate whose surface layer is at least a metal substrate at a temperature not exceeding the upper limit of the operating temperature of the LSI. The peeling step for removing the temporary substrate and A method for manufacturing an LSI element having a heat transfer structure, which comprises. 2. 2.
  • a fan-out mounting step of mounting a fan-out board in which fan-out wiring is formed on the main surface side of the Si board is included.
  • the Si substrate and the temporary substrate are joined via the fan-out substrate.
  • a barrier metal layer forming step of forming a barrier metal layer made of a barrier metal on the back surface of the Si thin film is included.
  • the Si thin film and the second substrate are joined via the barrier metal layer.
  • the thickness of the Si thin film is 100 ⁇ m or less.
  • the metal substrate is a copper substrate.
  • An LSI is formed on the surface layer portion of the main surface thereof, and a Si thin film having a thickness corresponding to the depth of the surface layer portion is formed.
  • a second substrate whose surface layer is at least a metal substrate bonded to the back surface of the Si thin film is provided.
  • a heat transfer structure of an LSI element, characterized in that heat generated by an LSI is transferred to the outside through the metal substrate. 7.
  • a fan-out wiring is formed, and the fan-out substrate is provided on the main surface side of the Si thin film.
  • the thickness of the Si thin film is 100 ⁇ m or less. Or 7.
  • the metal substrate is a copper substrate. ⁇ 8.
  • the surface layer includes a second joining step of joining the metal surface of the second substrate made of a metal substrate and a peeling step of removing the temporary substrate, the surface layer on the main surface side of the Si substrate on which the LSI is formed is included.
  • a thin Si thin film is formed according to the depth of the portion, and the Si thin film and the metal substrate are joined in a normal temperature range.
  • an LSI is formed on the surface layer portion of the main surface thereof, and a Si thin film having a thickness corresponding to the depth of the surface layer portion is formed.
  • a second substrate having at least a surface layer made of a metal substrate bonded to the back surface of the Si thin film is provided, and heat generated by the LSI is transferred through the metal substrate, so that the heat generated by the LSI is rapidly made of the metal substrate. It is transmitted to the substrate portion, and heat can be transferred from the metal substrate portion to an external heat spreader or the like. By providing the function of the heat pipe to the external heat spreader or the like, the heat from the metal substrate can be transferred to the outside more efficiently.
  • the metal substrate As the metal substrate, a copper substrate having excellent thermal conductivity can be used. Further, since the metal substrate serves as a substrate, an LSI element suitable for face-down mounting can be configured. The generation of warpage is suppressed by the metal substrate, and further, by joining the metal substrate and the Si thin film on which the LSI is formed at a temperature below the upper limit of the temperature at which the element is used, the Si thin film and the metal when using the LSI element are used. Deterioration due to stress generated at the bonding interface with the substrate can be suppressed.
  • the LSI (1) is formed on the surface layer portion of the main surface (11), and the thickness is formed thin corresponding to the depth of the surface layer portion.
  • a second substrate (25) having a formed Si thin film (10) and a second substrate (25) having at least a surface layer bonded to the back surface (12) of the Si thin film (10) made of a metal substrate (20) is provided, and the metal substrate (20) is provided. It is characterized in that the heat generated in the LSI (1) is transferred to the outside through the LSI (1) (see FIG. 1).
  • the type of LSI is not particularly limited.
  • a fan-out wiring is formed, and a fan-out substrate (9) bonded to the main surface (11) side of the Si thin film (10) is further formed. It can be provided (see FIG. 3 (b)).
  • the thickness of the Si thin film (10) corresponds to the depth of the surface layer portion and is made as thin as possible to create an LSI function, and the metal substrate (20) serves as a substrate for the LSI element.
  • the depth of the surface layer portion is set according to the impurity concentration, withstand voltage, and the like of the impurity layer constituting the LSI. Usually, the depth of the impurity layer is several ⁇ m. Therefore, in the present embodiment, the thickness of the Si thin film (10) can be 100 ⁇ m or less (5 to 100 ⁇ m).
  • the thickness of the metal substrate (20) may be appropriately set according to the strength of the material and the thickness of the Si thin film (10). For example, when a copper substrate is used, it can be about 50 to 300 ⁇ m. .. Even when LSI is mounted on the ceramic package, it is effective to use a metal (copper) substrate for the base portion of the Si element as described above in order to improve the heat conduction from the Si element to the ceramic package. ..
  • the method for manufacturing an LSI element (50) having a heat transfer structure is a method of manufacturing a Si substrate (100) having an LSI (1) formed on a surface layer portion on the main surface (11) side and a temporary substrate (5).
  • the back surface (12) of the Si thin film (10) and the metal substrate (20) of the second substrate (25) whose surface layer is at least the metal substrate (20) at a temperature not exceeding the upper limit of the operating temperature of the LSI (1).
  • Another method of manufacturing the heat transfer structure (51) of the LSI element is to mount a fan-out board (9) in which fan-out wiring is formed on the main surface (11) side of the Si board (100).
  • the first joining step which includes an out-mounting step, joins the Si substrate (100) and the temporary substrate (5) via the fan-out substrate (9) (see FIG. 4).
  • the bonding between the metal substrate (20) on the surface layer of the second substrate (25) and the Si thin film (10) is performed at a temperature (normal temperature) that does not exceed the upper limit of the operating temperature of the LSI element, the metal substrate 20 and the Si thin film are bonded.
  • the stress generated at the bonding interface with 10 can be reduced, the warp of the substrate can be significantly reduced, and the stress generated at the bonding interface due to the temperature cycle or the like generated in a practical state can be reduced. It is possible to increase the reliability of joining.
  • FIG. 1A shows a structural example of an LSI element 50 having a heat transfer structure according to the present embodiment.
  • a multi-layer element structure in which a Si thin film 10 having a required thickness on which LSI 1 is formed and a second substrate (25) having a thickness required for mounting and having at least a surface layer made of a metal substrate (20) are joined.
  • the surface layer of the second substrate (25) refers to a portion having a constant plate thickness constituting the joint surface with the Si thin film 10.
  • the entire second substrate (25) is composed of one metal substrate (20).
  • the metal substrate (20) it is preferable to use a copper substrate having excellent thermal conductivity.
  • heat generated by an LSI formed on the surface layer of an LSI element is conducted to the outside from a Si substrate of the same material via a heat spreader.
  • the LSI element 50 of this example uses a metal (copper) substrate instead of a Si substrate in order to more efficiently conduct heat conduction in the substrate portion made of Si.
  • the heat generated by the LSI 1 can be efficiently conducted to the heat spreader provided outside via the metal substrate 20 made of copper.
  • This heat transfer structure can also be applied to a multi-terminal structure of an LSI called a fan-out structure, and a fan-out structure element 51 having a copper substrate can be configured (see FIG. 3 (b)).
  • the second substrate 25 having at least the surface layer made of a metal substrate may be configured by laminating the metal substrate 20 to be the surface layer and the adhesive tape 26.
  • the adhesive tape 26 is effective when the thickness of the metal substrate 20 is kept thin, and in addition, the adhesive tape 26 can also serve as a base adhesive tape when the LSI element is divided into chips.
  • the second substrate 25 may be formed by a metal substrate 20 as a surface layer and a solder layer 27.
  • the solder layer 27 can be used as a connecting means when the LSI element is mounted on the ceramic package.
  • the second substrate 25 may be formed of a metal substrate 20 as a surface layer and an insulating sheet 28.
  • the insulating sheet 28 can serve as an insulating layer when the metal substrate potential of the LSI element is different from the potential of the heat spreader.
  • various materials can be selected as the base layer of the metal substrate 20 as the surface layer.
  • the base layer constituting the second substrate 25 is omitted, and the entire second substrate 25 is composed of one metal substrate 20.
  • FIG. (A) shows a state in which the LSI 1 is formed on the surface layer portion on the main surface 11 side of the Si substrate 100.
  • the substrate is the same Si substrate as the LSI.
  • a bonding terminal 30 for face-down mounting is formed on the main surface 11 of the Si substrate 100.
  • the standard thickness of the Si substrate (100) is, for example, 725 ⁇ m in the case of an 8-inch wafer.
  • FIG. 2B shows a state in which the main surface 11 side of the Si substrate 100 on which the LSI 1 is formed on the surface layer portion and the temporary substrate 5 are joined by the first joining step.
  • the temporary substrate 5 for example, a transparent glass substrate can be used.
  • the main surface 11 side of the Si substrate 100 and the temporary substrate 5 can be bonded by applying a UV release resin that is peeled off by ultraviolet light as a bonding material to the bonding surface.
  • the flatness of the bonding is required in order to polish the Si substrate 100 thinly, but the flatness can be ensured by applying the UV release resin and then pressurizing it while keeping it parallel.
  • an adhesive resin tape is also possible to use an adhesive resin tape as the temporary substrate 5. Due to the rigidity of the resin tape, the Si substrate 100 can be thinly polished in the subsequent Si thinning step.
  • the Si thin film thinning step is a step of forming the Si thin film 10 by removing the back surface side of the Si substrate 100 while leaving a thickness corresponding to the depth of the surface layer portion.
  • FIG. 2C shows a state in which the Si thin film 10 using the Si substrate 100 as a base material is formed by removing the back surface side of the Si substrate 100 bonded to the temporary substrate 5 by the Si thin film step. ing.
  • the method of removing the back surface side of the Si substrate 100 is not particularly limited, and for example, the thickness can be reduced to about 5 ⁇ m by grinding and polishing the back surface side of the Si substrate 100 with the temporary substrate 5 as a support.
  • the thickness corresponding to the depth of the surface layer portion depends on the withstand voltage required for the element, and is about 5 ⁇ m for the low withstand voltage element. Therefore, the thickness of the Si thin film 10 may be 5 ⁇ m or more. can. Actually, it is selected based on the balance between the ease of thin film processing and the improvement of thermal conductivity, and the thickness of the Si thin film 10 may be 10 ⁇ m or more from the viewpoint of thin film processing technology. Therefore, for example, in the case of an 8-inch wafer, the surface layer portion having a thickness of 10 to 100 ⁇ m on the main surface side of the standard Si substrate 100 having a thickness of 725 ⁇ m is left as a Si thin film (10).
  • the back surface 12 of the Si thin film 10 is polished to a surface roughness Ra of about 0.5 nm for later bonding with the metal substrate 20.
  • the barrier metal layer forming step is a step of forming a barrier metal layer made of a barrier metal on the back surface of the Si thin film after performing the Si thinning step (not shown).
  • the barrier metal layer 8 may be formed on the back surface 12 of the Si thin film 10 in order to prevent the copper from diffusing into the Si layer after bonding.
  • Ni, Ta, or the like can be used as the barrier metal, and the barrier metal layer 8 having a thickness of about 10 nm can be formed on the back surface 12 of the Si thin film 10 by sputtering.
  • the second joining step is a step of joining the back surface of the Si thin film and the metal substrate of the second substrate at a temperature not exceeding the upper limit of the operating temperature of the target LSI element.
  • FIG. 2D shows a state in which the back surface 12 of the Si thin film 10 and the second substrate 25 whose surface layer is at least the metal substrate 20 are bonded in the second bonding step.
  • the second substrate 25 is a substrate whose surface layer is at least a metal substrate 20, but the illustration is omitted except for the metal substrate 20.
  • the operating temperature of the semiconductor element is about ⁇ 20 ° C. to + 85 ° C. Therefore, the Si thin film 10 and the metal substrate 20 are joined at 85 ° C.
  • the joining can be performed at room temperature.
  • the material of the metal substrate 20 is not particularly limited, but for example, a copper substrate that is inexpensive and has excellent thermal conductivity can be used.
  • the barrier metal layer 8 is formed on the back surface of the Si thin film, the Si thin film 10 and the metal substrate 20 are joined via the barrier metal layer 8.
  • the method of joining at room temperature is not particularly limited, but for example, a method of activating both sides to be joined by an argon beam using a FAB (fast atomic beam) gun can be applied.
  • a FAB fast atomic beam
  • the Si thin film 10 and the metal substrate (copper substrate) 20 can be joined by using a FAB gun.
  • the joining method using a FAB gun has become widespread in room temperature joining of semiconductor substrates.
  • both sides to be joined are activated by irradiating an argon beam obtained from an argon beam source 200, and then pressurized at room temperature for joining.
  • the feature of this joining method is that if the joining surface has a flatness of 0.5 nm level, it can be directly joined at room temperature.
  • the figure is a schematic diagram of the main part of the bonding device.
  • Two substrates to be bonded in a vacuum chamber are arranged so as to face each other at regular intervals, and the FAB gun 200 is placed on both surfaces from the side thereof.
  • the argon beam (201, 202) is scanned and irradiated.
  • the degree of vacuum in the vacuum chamber is about 1 ⁇ 10 -4 to 1 ⁇ 10 -6 Pa.
  • the surface layers (20b, 10b) of both substrates are activated and can be bonded at room temperature. It is also possible to activate and bond with an ion gun regardless of the FAB gun.
  • FIG. 6 shows a TEM (transmission electron microscope) image of the bonding interface between the Si thin film 10 and the copper substrate 20. It can be seen that the Si thin film 10 and the copper substrate 20 are bonded at the atomic level.
  • a method of forming a thin gold thin film with a thickness of about 10 nm on the surface for joining has also been developed.
  • the Si thin film 10 and the metal substrate 20 can also be joined via such a thin gold thin film.
  • FIG. 2 (e) shows a state in which the temporary substrate is removed by the peeling step.
  • the Si thin film 10 is bonded to the metal substrate 20 via the barrier metal layer 8 (not shown).
  • the temporary substrate 5 made of transparent glass and the main surface 11 of the Si thin film 10 are bonded with a UV release resin, the bonding interface can be separated by irradiating ultraviolet rays from the glass substrate side.
  • the LSI element has a multi-layer element structure composed of a thin Si layer on which the LSI is formed and a metal substrate as a support substrate thereof.
  • the transparent glass substrate can be reused.
  • a resin tape having adhesiveness is used as the temporary substrate 5, it can be peeled off from the end face of the resin tape, and the resin tape can be disposable.
  • the LSI element can have a fan-out structure.
  • Fan-out mounting is a mounting method that has been put into practical use as the terminal pitch has become finer due to the increase in the number of pins of LSI.
  • FIG. 3A shows how the conventional LSI element 300 is mounted on the fan-out substrate (Si substrate) 320 and the terminal pitch is widened. Terminals are formed on the LSI element 300 side of the fan-out board 320 at the same pitch as the LSI element 300, mutual wiring is made in the inner layer of the fan-out board, and terminals having a wide pitch on the external mounting surface terminal 13 of the fan-out board. Is formed.
  • the external mounting surface terminal 13 is a terminal having a wide pitch so that it can be face-down mounted on a printed circuit board.
  • the LSI element 300 is face-down mounted on the fan-out substrate 320 in the wafer state, then the resin 14 is filled, and the resin is molded in the wafer state.
  • the Si substrate of the element is exposed on the back surface side of the LSI element 300.
  • a resin substrate may be used in addition to the Si substrate.
  • FIG. 3B shows the LSI element 51 in which the fan-out substrate 9 having the fan-out wiring formed is bonded to the main surface 11 side of the Si thin film 10 in the method of manufacturing the LSI element of the present embodiment. ing.
  • a metal substrate 20 is bonded to the back surface of the Si thin film 10, and the metal substrate 20 is exposed on the back surface side of the LSI element 51.
  • the thickness of the Si thin film 10 is the minimum thickness necessary for the configuration and operation of the LSI, and the thickness of the metal substrate 20 which is the base portion thereof is necessary for face-down mounting of an element having a fan-out structure. It is said to be thick. According to this configuration, the heat generated by the LSI can be quickly conducted to the substrate portion having high thermal conductivity, and efficiently conducted and radiated to the outside via the heat spreader connected to the substrate portion.
  • the fan-out mounting step of mounting the fan-out board (9) in which the fan-out wiring is formed on the main surface (11) side of the Si board (100) is included, and the first joining step includes a fan-out mounting step. It can be configured to join the Si substrate (100) and the temporary substrate (5) via the fan-out substrate (9).
  • FIG. 4 each step in the manufacturing method of the LSI element which can be fan-out mounted will be described. Each manufacturing process is performed in an 8-inch wafer state, and each figure shows a cross section of a portion corresponding to an LSI element in one chip size package.
  • FIG. (A) shows a state in which the LSI 1 is formed on the surface layer portion on the main surface 11 side of the Si substrate 100.
  • the substrate is the same Si substrate as the LSI.
  • a bonding terminal 30 is formed on the main surface 11 of the Si substrate 100, and a fan-out substrate 9 made of Si is bonded to the main surface side of the bonding terminal 30.
  • Mutual wiring is made in the inner layer of the fan-out board 9, and bonding terminals 13 having a wide pitch are formed on the external mounting surface of the fan-out.
  • FIG. 4B shows a state in which the temporary substrate 5 is bonded to the upper surface of the fan-out substrate 9 by the first bonding step.
  • FIG. 3C shows a state in which the back surface side of the Si substrate 100 is removed by polishing or the like by the Si thin film step, and the Si thin film 10 remains. Since the temporary substrate 5 serves as a support, the thickness of the Si thin film 10 can be reduced to about 5 to 10 ⁇ m.
  • FIG. 3D shows a state in which the metal substrate 20 is bonded to the back surface 12 of the Si thin film 10 by the second bonding step. A room temperature joining technique such as using a FAB gun can be applied to this joining. It can also be bonded via a gold thin film having a thickness of about 10 nm.
  • FIG. 3E shows a state in which the temporary substrate 5 is peeled off by the peeling step. As described above, the fan-out structure element 51 having an element structure made of a metal (copper) substrate is completed. The specific contents of each step are the same as those of each step described with reference to FIG.
  • the LSI element 50 manufactured as described above and the LSI element 51 having a fan-out structure can be mounted on a printed circuit board by face-down and used.
  • FIG. 7A shows an example in which the LSI element 50 of the chip size package is face-down mounted on the printed circuit board 200.
  • FIG. 3B shows an example in which an LSI element 51 having a fan-out structure is face-down mounted on a printed circuit board 200.
  • a copper substrate is used as the metal substrate 20, and the thickness thereof is 300 ⁇ m.
  • the thickness of the Si thin film 10 on which the LSI is formed is 10 ⁇ m.
  • the thin Si thin film 10 and the metal substrate 20 can efficiently transfer the heat generated by the LSI.
  • the Si thin film 10 is bonded to the metal substrate 20, there is no warp, and stable soldering is possible even in face-down mounting.
  • the heat generated on the surface of the LSI is dissipated mainly by conduction from the copper substrate 20 which is a substrate to the heat spreader 430 which is a housing.
  • FIG. 8 describes a simulation of heat dissipation by heat conduction from the LSI element 50 mounted as described above to the housing.
  • the thickness of the Si thin film 10 constituting the LSI element 50 is 10 ⁇ m
  • the thickness of the copper substrate as a substrate is 300 ⁇ m.
  • the heat spreader portion D that also serves as a housing has a temperature of 30 ° C.
  • the heat spreader portion C has a temperature of 53 ° C.
  • the temperature is 76 ° C. in the heat conductive resin portion B and 90 ° C. in the LSI portion A.
  • the LSI unit A can be set to 150 ° C.
  • the heat spreader is provided with the function of a heat pipe, the heat conduction from the heat spreader portion D to the outside is further increased, and the temperatures in the heat conductive resin portion B and the LSI portion A are further lowered.
  • the element structure of a general Si substrate see FIG. 9A
  • the heat generation is 20 watts and the ambient temperature is 25 ° C.
  • the temperature is 75 ° C. at the point corresponding to the heat spreader portion C, 98 ° C. at the point corresponding to the heat conductive resin portion B, and 135 ° C. at the point corresponding to the LSI portion A.
  • the above temperature difference in the LSI unit A can be said to be an effect of the element structure according to the present embodiment, and by using the element as a copper substrate, the temperature can be lowered by 45 ° C. as compared with the case of the Si substrate. Conversely, it can be used up to a temperature range of 45 ° C. higher. If the operating temperature is the same, it means that a device with high heat generation of 20 watts or more can be used. This also applies to the LSI element 51 provided with the fan-out substrate.
  • the metal substrate and the Si layer (Si thin film) on which the LSI is formed are bonded at the bonding interface by performing the bonding at a temperature equal to or lower than the upper limit of the temperature at which the device is used.
  • the stress generated can be minimized. That is, the LSI element in which the Si layer is bonded to the metal substrate at room temperature significantly suppresses the influence of stress generated at the bonding interface when the LSI element is used, as compared with the case where the Si layer is bonded to the metal substrate at high temperature. be able to.
  • the thickness of the metal substrate made of copper is 300 ⁇ m
  • the thickness of the Si thin film is 10 ⁇ m
  • the operating temperature of the LSI element is 85 ° C.
  • the coefficient of linear expansion is 16.8 ⁇ 10-6 for copper and 2.4 ⁇ 10-6 for Si, and the difference is 14.4.
  • the Si layer and the copper substrate are bonded at a high temperature. Assuming that the Si layer and the copper substrate are bonded at 400 ° C., a temperature difference of 315 ° C. occurs between the temperature at the time of bonding and the temperature at 85 ° C. when the semiconductor element is used.
  • the Si layer (Si thin film) and the copper substrate are bonded at room temperature (25 ° C.), the temperature difference from the temperature of 85 ° C. when the LSI element is used is only 60 ° C.
  • the present invention is not limited to the embodiment detailed above, and various modifications or changes can be made within the scope shown in the claims of the present invention.
  • the base part of the LSI element may be a metal (copper) substrate. effective.
  • the multi-layered element structure of the present invention makes it possible to apply it to applications with a higher environmental temperature by effectively conducting heat with high heat generation, and it is also possible to mount a larger heat generating element.
  • LSI 5; temporary substrate, 8; barrier metal layer, 9; fan-out substrate, 10; Si thin film, 100; Si substrate, 20; metal substrate (copper substrate), 25; second substrate, 50-54; LSI element, 200; printed circuit board.

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  • Physics & Mathematics (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Computer Hardware Design (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Cooling Or The Like Of Semiconductors Or Solid State Devices (AREA)

Abstract

La présente invention concerne une structure de transfert de chaleur pour un élément LSI qui transfère la chaleur générée dans un LSI vers l'extérieur de celui-ci au moyen d'un substrat métallique joint à une couche mince de Si, et un procédé de fabrication d'un élément LSI ayant une telle structure de transfert de chaleur. Un procédé de fabrication d'un élément LSI ayant une structure de transfert de chaleur est caractérisé en ce qu'il comprend : une première étape de jonction pour relier un substrat provisoire 5 à un côté de surface principale 11 d'un substrat de Si 100 ayant une LSI 1 formée dans une partie de couche supérieure de celui-ci ; une étape d'amincissement de film de Si pour former un film mince de Si 10 par retrait d'un côté de surface arrière du substrat de Si tout en laissant une épaisseur correspondant à la profondeur de la partie de couche supérieure ; une deuxième étape de jonction pour la jonction, à une température ne dépassant pas une limite supérieure d'une température de fonctionnement LSI, de la surface arrière du film mince de Si à un second substrat 25 dont au moins une couche supérieure comprend un substrat métallique 20 ; et une étape de pelage pour retirer le substrat provisoire 5.
PCT/JP2021/043578 2020-11-30 2021-11-29 Structure de transfert de chaleur pour élément lsi et procédé de fabrication d'élément lsi ayant une telle structure de transfert de chaleur WO2022114172A1 (fr)

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JP2020198964A JP2022086775A (ja) 2020-11-30 2020-11-30 Ｌｓｉ素子の熱伝構造及びその熱伝構造を備えるｌｓｉ素子の製造方法

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JP2016063178A (ja) * 2014-09-22 2016-04-25 富士通株式会社 半導体装置及びその製造方法
JP2017195300A (ja) * 2016-04-21 2017-10-26 富士通株式会社 半導体装置及び半導体装置の製造方法
JP2018056285A (ja) * 2016-09-28 2018-04-05 富士通株式会社 電子装置、電子装置の製造方法及び電子機器

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2016063178A (ja) * 2014-09-22 2016-04-25 富士通株式会社 半導体装置及びその製造方法
JP2017195300A (ja) * 2016-04-21 2017-10-26 富士通株式会社 半導体装置及び半導体装置の製造方法
JP2018056285A (ja) * 2016-09-28 2018-04-05 富士通株式会社 電子装置、電子装置の製造方法及び電子機器

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