1. Field of the Invention
The present invention relates to a semiconductor device. More specifically, the present invention relates to a semiconductor element unit with a multistage, stacked structure with a high connection reliability that constitutes a mounting system with low parasitic inductance and capable of high-speed signal transmission, which are necessary for a high-speed memory implementation, a complex thereof, a semiconductor device, a module thereof, an assembled structure thereof and a film substrate connection structure.
Priority is claimed on Japanese Patent Application No. 2007-22400, filed Jan. 31, 2007, the content of which is incorporated herein by reference.
2. Description of Related Art
In the case of mounting a semiconductor element on a substrate, Japanese Patent No. 3809125 discloses a conventional structure of electrical joining by melting and solidifying a solder layer that is provided on a mounting substrate via projection electrodes that are provided on the semiconductor element.
However, in memory or large-scale logic chips of a large chip size with a high speed and large capacity, since there is large difference in the thermal expansion coefficients of the semiconductor element and the mounting substrate, there are cases of the solder joints being damaged until the solder solidifies from the melted state, becoming one cause that brings about a drop in the mounting yield.
As a countermeasure, a method has been developed of distributing the force that concentrates on solder joints by putting a thermosetting resin between the semiconductor element and the mounting substrate and hardening the resin simultaneously with the solder bonding.
Also, in the case of stacking a plurality of semiconductor elements in the middle of one semiconductor device, a stacked semiconductor device is manufactured by a method such as wire bonding the semiconductor element to the mounting substrate, moreover stacking the semiconductor element thereon, and wire bonding.
This issue has conventionally been resolved by mounting a semiconductor element on a multilayer substrate that has a microstrip structure and a low resistance power supply layer to constitute a semiconductor device.
However, in the prior art, in the case of stacking semiconductor devices, since it was essential to form connections via solder, stacked assembly could not be realized under the solder melting temperature. Also, as far as making connections at a high temperature using molten solder, due to the large difference in the thermal expansion coefficients of the semiconductor element and the mounting substrate, the solder joints are susceptible to breakage, and it has not been possible to improve the mounting yield.
The present invention was achieved in view of the above circumstances, and has as its object to provide a semiconductor element unit that lowers resistance of the power supply and hinders unnecessary electromagnetic radiation from outside, has low parasitic inductance and allows assembly at low temperatures, as well as a complex thereof, and a semiconductor device, and a module thereof, and assembled structure thereof and a film substrate connection structure.
Also, another object of the present invention is to provide a structure that enables stacking of semiconductor devices at a temperature lower than the solder melting temperature.
According to the present invention, by using film wiring substrates that allow circuit formation on the front and rear, wiring suitable for high speed signal transmission (for example, microstrip configuration) is formed, and by ultrasonically bonding projection terminals formed on the semiconductor element, electrical connections with low parasitic inductance are achieved.
Moreover, by having through-vias that electrically connect the front and rear of the film substrate, and by essentially filling those through-vias with a metal by a method such as plating or the like, ultrasonic vibration is easily transmitted. Because of this structure, it is possible to achieve ultrasonic bonding between the multilayer substrate which is the next mounting state at a temperature that is close to room temperature, which is lower than the solder melting temperature. By utilizing this ultrasonic joining means via through-vias, it is possible to comparatively easily constitute even film substrate multi-stage stacked structures comparatively easily without concern to temperature hierarchy.
In the case of performing ultrasonic bonding, bonding via Au and Au of portions to be bonded have the most reliable and favorable bonding.
Accordingly, in the case of bonding a film substrate to a multilayer substrate with high rigidity such as a rigid substrate or the like and not a film substrate, if the film substrate side has through-vias, ultrasonic bonding is possible via the through-vias that are provided in the film-shaped substrate body even if the multilayer substrate side is any of wiring, terminals, or vias.
In the case of a constitution that stacks a plurality of semiconductor element units which are bonded to a mounting substrate, it is possible to obtain a semiconductor element unit complex that uses only conforming articles of semiconductor element units. The conforming articles of semiconductor element units can be selected, for instance, by performing a high frequency driving test, that is, a high speed test close to the actual use state for each unit of the semiconductor element unit.
Also, if adopting a structure that stacks only the required number after making a semiconductor element unit complex with a flat top face with the semiconductor element surrounded by spacer substrates, it is possible to readily stack through-vias of the film substrates of semiconductor element unit complexes that are vertically stacked. This makes it possible to realize ultrasonic bonding of a plurality of semiconductor element unit complexes via the stacked through-vias, and possible to obtain a semiconductor device module of a structure in which a plurality of the semiconductor element unit complexes are bonded and integrated.
Since this semiconductor device module is integrated by bonding of through-vias that are vertically stacked, the bondability of the semiconductor element unit complexes is good. Even when the low rigidity of flexibility such as a film substrate is stacked, the handling as a whole exhibits rigidity of a sufficient extent, and is excellent in handling.
The semiconductor element unit or semiconductor device and the like according to one embodiment of the present invention shall be described with reference to the drawings, however, the present invention is not limited to the embodiment described hereinbelow.
In
The semiconductor element 1 is a package component that is provided with a plate-shaped sealed body 1A that includes within functional elements consisting of circuits represented by various kinds of ICs (integrated circuits), LSI (large scale integration) and the like, or an MPU (Micro Processing Unit), an MCU (Micro Controller Unit), a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), or a gate array and the like mounted individually or compositely in the inner portion, with those functional devices sealed with a sealing material such as resin or ceramic. The semiconductor element 1 has a basic shape of a plurality of terminal members 1D being formed on the bottom side of the sealed body 1A, with each terminal member 1D consisting of a convex-shaped terminal base portion 1B and a projection terminal 1C that is formed in a projecting shape from the terminal base portion 1B. Note that a structure in which a plurality of the terminal members 1D are provided on the bottom side of the sealed body 1A is shown as an example of the semiconductor element 1 in the present embodiment. However, package-type semiconductor elements come in other various shapes, such as a structure of a plurality of leg-shaped terminals being provided from the side surface of the plate-shaped sealed body 1A, a shape of a plurality of needle-shaped or pin-shaped terminals being provided on the bottom surface of the sealed body 1A, a structure of providing solder balls that have a terminal action, and the like. The present invention can be widely applied to a semiconductor element of any shape, provided it has a constitution in which terminal members are provided projecting from the sealed body 1A.
Also, the semiconductor device B that is provided with the semiconductor element 1 and the film base substrate 2 of the present embodiment may be an internal substrate (interposer) that is enclosed within a semiconductor package. The mounting substrate 5 can also be regarded as a memory module, a module substrate of a so-called SiP (System in Package) or SoP (Small Outline Package), or package substrate.
The projection terminal 1C of the terminal member 1D is a pin type that consists of a metal conductor with a round shape (R shape). At the distal end portion of this projection terminal 1C, it is preferable that an Au-plated layer be formed having Au as a main body via an Ni foundation layer. A layer having Au (gold) as a main body in the present invention means Au with a concentration of at least 50% and for example it is possible to apply a layer of any concentration such as a deposition plated type Au plate layer with a high purity of 99% or greater, a 24K plate layer of 98% purity, a 14K Au alloy plate layer with a purity of approximately 56% to 60% provided it is a layer with Au as the main body.
The film substrate 2 is constituted by being equipped with a substrate body 2A that consists of a thermoplastic resin film having flexure (such as (PI) polyimide film etc.), a through-via 2C at each of a plurality of through-holes 2B that pass through the substrate body 2A in the thickness direction that are filled with a conductive metal material such as plated copper, a wiring 2D or terminal 2d on the top face side that are formed on the top face side of the substrate body 2A and connected to the through-via 2C, and wiring 2E on the rear face side that is formed on the rear face side of the substrate body 2A and connected to the through-via 2C.
The through-via 2C is formed so as to fill the through-hole 2B with a conductive metal material such as plated copper as shown up close in
Note that the through-via 2C has in this embodiment a structure of being formed in a rivet shape and retained. However, the shape of the through-via 2C is not limited to a rivet shape, with a shape of being continuous with the wiring or terminal, or a column shape that is simply filled in the through-hole 2B also acceptable.
The mounting substrate 5 has a structure that is known as a multilayer wiring printed circuit board, and so is configured by bonding and integrating internal printed circuit boards of a plurality of layers. Field-vias 11 of a type that pass through the internal printed circuit boards at each layer and internal wiring 12 that is provided on the top face portion side and rear face portion side of the internal printed circuit boards are provided. On the top face side of the mounting substrate 5, among the field-vias 11 that pass through the internal printed circuit boards, front face side wiring 13 and top face side terminals 13a that are connected to those field-vias 11 that reach the top face of the mounting substrate 5 are provided. On the rear face side of the mounting substrate 5, among the field-vias 11 that pass through the internal printed circuit boards, rear face side wiring 14 and rear face side terminals 14a that are connected to those field-vias 11 that reach the rear face of the mounting substrate 5 are provided. Also, a bonding layer 19 that consists of a foundation layer 17 of Ni plate and a covering layer 18 having Au as the main component is formed on the front face side wiring 13 and top face side terminals 13a of the mounting substrate 5.
This mounting substrate 5 has a rigid structure, and is made to have a higher rigidity than the film-shaped substrate body 2A by mixing a filler or the like in a thermoplastic resin and hardening.
The projection terminals 1C of the semiconductor element 1 are electrically connected by a bonding material such as solder at a portion that is connected to the wiring 2D of the film substrate 2. However, those connected to the through-via 2C at the projection terminal 1C are ultrasonically bonded.
To join the semiconductor element 1 to the film substrate 2 using an ultrasonic bonding tool 15 as shown in
It is possible to reliably perform ultrasonic bonding under the conditions of a bonding frequency of 50 kHz, a bonding temperature of 25 degrees C., a bonding load of 5 to 10 N, amplitude of 8 to 16 μm, bonding time of 0.2 seconds, polyimide film substrate thickness of 50 μm, and copper though-via diameter of 30 μm.
Also, ultrasonic bonding is performed for the portion of the through-via 2C of the film substrate 2 to be bonded to the mounting substrate 5. For the portions that position the through-via 2C of the film substrate 2 on the field-vias 11 positioned on the front face portion of the mounting substrate 5, by pressing the ultrasonic bonding tool 15 from above, it is possible to perform ultrasonic bonding under the conditions given above. Also, for the portions that position the through-via 2C of the film substrate 2 on the front face side wiring 13 positioned on the front face portion of the mounting substrate 5, by pressing the ultrasonic bonding tool 15 from above, it is possible to perform ultrasonic bonding under the conditions given above.
In order to perform ultrasonic bonding with the ultrasonic bonding tool 15, it is necessary to accurately transmit ultrasonic waves to a bonding region while applying the necessary pressure with the ultrasonic bonding tool 15. Here, when interposing something that causes vibration attenuation such as resin or a flexible material between the ultrasonic bonding tool 15 and the bonding region, ultrasonic bonding becomes extremely difficult. For example, when ultrasonic bonding is attempted with a bonding tool on two film substrates in which wiring is formed on polyamide film substrate bodies by abutting the wiring together and adding pressure so as to sandwich them, the thermoplastic resin such as polyamide that is held between the wiring attenuates the ultrasonic vibration and changes the vibration frequency that is transmitted to the sections to be joined, and so satisfactory ultrasonic bonding cannot be performed.
In contrast, in a case of performing ultrasonic bonding as in the structure above by abutting the projection terminal 1C of the semiconductor element 1 and the through-via 2C of the film substrate 2 while transmitting ultrasonic waves to the projection terminal 1C and the through-via 2C with the ultrasonic bonding tool 15, it is possible to directly transmit ultrasonic waves to the metal projection terminal 1C from the metal through-via 2C, and so it is possible to perform ultrasonic bonding without attenuation of the vibrations.
Also, in the case of performing ultrasonic bonding on the mounting substrate 5 that is a rigid substrate and that can more favorably transmit vibrations than resin such as polyamide, if the film substrate 2 is stacked on the mounting substrate 5 as shown in
Next, since a coating having Au as the main component is formed at the portion at which the projection terminal 1C of the semiconductor element 1 is ultrasonically bonded, that is, on the upper face side of the through-via 2C of the film substrate 2, and a coating layer having Au as the main component is formed on the upper face side of the through-via 2C of the film substrate 2 of the side at which the projection terminal 1C is joined, the interface that is ultrasonically bonded undergoes bonding by Au and Au, and so electrical conduction and mechanical bonding force are obtained with sufficient bonding strength and conductivity due to the ultrasonic bonding. Note that the Ni layer that serves as the foundation of the coating layer having Au as the main body is applied in the case of the metal that constitutes the projection terminal 1C or the metal that constitutes the through-via 2C leading to a problem in the mechanical bonding power with the Au, however, it may be omitted in the case of the projection terminal 1C and the through-via 2C consisting of a material having a high bonding power with Au.
Also, similarly to the portion where the through-via 2C of the film substrate 2 is ultrasonically bonded to the wiring 13 of the mounting substrate 5 or the portion where the through-via 2C is ultrasonically bonded on the field-via 11 of the mounting substrate 5, since a covering layer 18 which has Au as a main component is formed on the wiring 13 of the mounting substrate 5, and the covering layer 18 which has Au as a main component is formed on the field-via 11, the interface that is ultrasonically bonded undergoes bonding by Au and Au, and so electrical conduction and mechanical bonding force are obtained with sufficient bonding strength and conductivity due to the ultrasonic bonding.
The semiconductor device B in which the film substrate 2 provided with the semiconductor element 1 is joined on the mounting substrate 5 is provided for practical use by additionally attaching to an aggregate board 20 such as a large motherboard as shown for example in
In the structure of the embodiment explained above, by using the film substrate 2 in which formation of circuits such as wiring is possible on the front and rear, wiring that is suitable for high speed signal transmission (for example, microstrip configuration) is formed, and by ultrasonically joining various lines with the projection terminals 1C formed on the semiconductor element 1, electrical connections with low parasitic inductance are achieved. Also, a bonding state with high mechanical strength is obtained at the bonded portions where ultrasonic connection is performed.
Moreover, by providing through-vias 2C that enable electrical connection of the front and rear of the film substrate 2, ultrasonic vibration is easily transmitted, and for that reason joining with the mounting substrate 5, which is the next mounting stage, can be achieved at a temperature that is lower than the solder melting temperature. By utilizing this ultrasonic joining means, it is possible to form stacked structures comparatively easily without temperature hierarchy, even if it is multi-stage stacked structure.
Also, when attaching the semiconductor element unit A to the mounting substrate 5, it is possible to perform inspection of the semiconductor element 1 using the wiring 2D that is formed on the film substrate 2, and if only the semiconductor element unit A that passes this inspection is attached to the mounting substrate 5, it is possible to prevent the attachment of defective articles. Note that in the wiring 13 of the semiconductor element unit A, it becomes not a single component of the semiconductor element 1, but a wiring expanded staged structure, and so it is possible to perform precise tests including speed operation tests. On this point, if a single component of the semiconductor element 1, it is possible to some perform tests with a tester or a probe of a survey instrument, but high speed tests of the high speed signal input and the like are difficult, but if high speed test in the state of the semiconductor element unit A, it is possible to perform testing in a state that is closer to the actual usage state, and so it is possible to select a perfectly conforming article.
The semiconductor element unit A that is applied to this embodiment, similarly to the previous embodiment, has a structure of the semiconductor element 1 being attached to the film substrate 2, with the constitution of the film substrate 2 having a through-via 2C formed in the substrate body 2A, and the constitution of the through-via 2C having a flange portion 2F and having a bonding layer 9 that consists of a foundation layer 7 and a covering layer 8 being equivalent.
The characteristic point of the semiconductor element unit complex F of this embodiment is, along with two of the semiconductor element units A being stacked, the film-shaped substrate body 2A of the upper stage side semiconductor element unit A is placed on the semiconductor element 1 of the lower stage side semiconductor element unit A, both ends of the substrate body 2A being flexed to the lower stage side semiconductor element unit A, both end portions of the substrate body 2A being aligned on the substrate body 2A of the lower stage side semiconductor element unit A, and the upper and lower semiconductor element units A, A being joined by performing ultrasonic bonding of the required portions of the through-vias 2C of the upper stage side substrate body 2A to the required portions of the through-vias 2C of the lower stage side substrate body 2A.
Also, in the semiconductor element unit complex F of the present embodiment, the through-vias 2C that are disposed at the end portion side in the film shaped substrate body 2A of the upper stage side semiconductor element unit A are stacked on the through-vias 2C that are disposed at the end portion side in the film shaped substrate body 2A of the lower stage side semiconductor element unit A, and both semiconductor element units A, A are bonded and integrated by ultrasonically bonding the required through-vias 2C among those that are vertically stacked.
It is acceptable to perform ultrasonic bonding under the aforesaid welding conditions using the ultrasonic bonding tool 15 that was used in the previous embodiment.
According to the structure of this embodiment, it is possible to perform electrical and mechanical bonding at a temperature that is close to room temperature, which is below the temperature of soldering the top and bottom semiconductor element units A, A, and so cubic integration of the semiconductor element unit A can be readily done. Also, by electrically and mechanically bonding at a temperature that is close to room temperature, which is below the soldering temperature, it is possible to integrate without adding thermal stress to the semiconductor elements 1, 1 that are mounted on the semiconductor element unit A, and so it is possible to obtain a high bonding strength by ultrasonic bonding of the through-vias 2C.
The mounting substrate 5 shown in
In the present embodiment, among the through-vias 2C that are formed in the substrate body 2A of the lowest stage semiconductor element unit A in the semiconductor element unit complex F, the required ones are ultrasonically bonded to the front face side wiring 13 that is disposed on the top face side of the mounting substrate 5, and so bonded and integrated to the mounting substrate 5.
The mounting substrate 5 in this structure is a rigid substrate with a high degree of hardness. By arranging the through-vias 2C of the semiconductor element unit A side on the front face side wiring 13 of the mounting substrate 5 and impressing ultrasonic vibrations while applying pressure from the top with the ultrasonic bonding tool 15, it is possible to bond them.
In this case, as shown in
Also, in the case of performing three-stage ultrasonic bonding, ultrasonic bonding may be performed in the order of ultrasonic bonding with the through-vias 2C of the lower stage side semiconductor element unit A stacked on the field-vias 11 of the mounting substrate 5, followed by ultrasonic bonding with the through-vias 2C of the upper stage side semiconductor element unit A stacked thereon.
The semiconductor device 25 that is constituted as described above of course may further be attached to the aggregate board 20 having a structure shown in
In the semiconductor element unit complex G of this embodiment, the spacer substrates 27 of a thickness equal to the semiconductor element 1 or greater are disposed on the film shaped substrate body 2A of the semiconductor element unit A so as to be positioned around the semiconductor element, and through-vias 2G in which a conductive material is filled in through-holes that are provided in the front and rear of the spacer substrates 27 are formed, and the through-vias 2G that are formed in the spacer substrates 27 are installed on the through-vias 2C that are provided on the film shaped substrate body 2A, and the spacer substrates are bonded to the substrate body by ultrasonically bonding both of the through-vias 2G; 2C.
Each of the through-vias 2G of this structure has the same structure as the though vias 2C described in the preceding embodiment.
The semiconductor element unit complex G of this embodiment has the characteristic of having a flat top surface, with the top surface of the semiconductor element 1 and the top surface of the spacer substrates 27 being approximately flush.
As a result, even in the case of stacking a plurality of this semiconductor element unit complexes G having this flat top face structure, a structure that can be vertically stacked with no unevenness is achieved.
A semiconductor device module J of this embodiment has structure consisting of three of the semiconductor element unit complexes G being stacked, and in this embodiment, the through-vias 2G, 2C of each semiconductor element unit complex G that is stacked vertically are all arranged in a vertical row, and so the through-vias 2C, 2G that make vertical contact are ultrasonically bonded to each other.
The semiconductor element unit complex G that is provided with the spacer substrates 27 as in this embodiment can be stacked to a required number. In that case, all of the film-shaped base plate bodies 2A can be bonded in a parallel and well-settled manner.
Even in the assembled structure of the semiconductor device module J of this embodiment, similarly to the structure of the semiconductor structure B shown in
Even in the structure of this embodiment, similarly to the case of the preceding embodiment, for the portions that position the through-vias 2C of the film substrate 2 on the field-vias 11 positioned on the top face portion of the mounting substrate 5, by pressing the ultrasonic bonding tool 15 from above, it is possible to perform ultrasonic bonding under the conditions given above. Also, for the portions that position the through-vias 2C of the film substrate 2 on the front face side wiring 13 positioned on the top face portion of the mounting substrate 5, by pressing the ultrasonic bonding tool 15 from above, it is possible to perform ultrasonic bonding under the conditions given above.
To assemble the semiconductor device module J on the mounting substrate 5 in the structure of
This example shows an embodiment in which, after obtaining the semiconductor device module J shown in
It is acceptable to employ a means other than ultrasonic bonding in the case of bonding to the mounting substrate 5 as described above.
Even in the assembled structure of the semiconductor device module J shown in either
A semiconductor element unit complex K of this second embodiment is a two-storied structure of the semiconductor element unit A of the first embodiment described previously.
The semiconductor element unit A that is applied to this embodiment, similarly to the previous embodiment, has a structure of the semiconductor element 1 being attached to the film substrate 2, with the constitution of the film substrate 2 having through-vias 2C formed in the substrate body 2A, and the constitution of the through-vias 2C being equivalent.
The characteristic point of the semiconductor element unit complex K of this embodiment is, along with two of the semiconductor element units A being stacked on the mounting substrate 5, the film-shaped substrate body 2A of the upper stage side semiconductor element unit A is placed on the semiconductor element 1 of the lower stage side semiconductor element unit A, one end side of the substrate body 2A (the left end portion side in
Also, the semiconductor element units A, A on the mounting substrate 5 are covered by a sealing portion that consists of a sealing material, and a required number of solder balls 31 are formed as connection terminals on the bottom surface of the mounting substrate 5.
A semiconductor element unit complex L of this second embodiment is a two-storied structure of the semiconductor element unit A of the first embodiment described previously.
The semiconductor element unit A that is applied to this embodiment, similarly to the previous embodiment, has a structure of the semiconductor element 1 being attached to the film substrate 2, with the constitution of the film substrate 2 having through-vias 2C formed in the substrate body 2A, and the constitution of the through-vias 2C being equivalent.
The characteristic point of the semiconductor element unit complex L of this embodiment is, along with two of the semiconductor element units A being stacked on the mounting substrate 5, the film-shaped substrate body 2A of the upper stage side semiconductor element unit A is placed on the semiconductor element 1 of the lower stage side semiconductor element unit A, one end side of the substrate body 2A (the left end portion side in
Also, the semiconductor element units A, A on the mounting substrate 5 are covered by a sealing portion that consists of a sealing material, and a required number of solder balls 31 are formed as connection terminals on the bottom face side of the mounting substrate 5.
Since these semiconductor element unit complexes K, G, in
While preferred embodiments of the invention have been described and illustrated above, it should be understood that these are exemplary of the invention and are not to be considered as limiting. Additions, omissions, substitutions, and other modifications can be made without departing from the spirit or scope of the present invention. Accordingly, the invention is not to be considered as being limited by the foregoing description, and is only limited by the scope of the appended claims.
Number | Date | Country | Kind |
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2007-022400 | Jan 2007 | JP | national |