JP3684978B2 - SEMICONDUCTOR DEVICE, ITS MANUFACTURING METHOD, AND ELECTRONIC DEVICE - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device wherein semiconductor chips can be laminated without intervention of an interposer and the chips can be electrically connected regardless of their sizes, a method of manufacturing the semiconductor device, and electronic equipment. SOLUTION: Semiconductor chips 10a, 10b, 10c and 10d are formed with a through hole 12. And a conductive film 16 of an eutectic alloy of silver and tin is formed on an inner peripheral surface of the through hole 12 and on the vicinities of openings of the hole. The conductive film 16 is electrically connected to electrode pads 14a, 14b, 14c and 14d of the chips 10a, 10b, 10c and 10d. Thus, only when a terminal or the like of an external device (not shown) is connected to an end 18a or 18b of the film 16, the external device can be electrically connected to the chips.

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor device, a method for manufacturing the same, and an electronic apparatus, and more particularly to a device suitable for stacking and using a plurality of semiconductor chips.
[0002]
[Prior art]
In the field of semiconductor devices, in recent years, for the purpose of reducing the size and weight of semiconductor devices, many semiconductor chips are provided in a single package, in particular, each semiconductor chip is provided in a stacked state. Such a semiconductor device is called a multichip package (MCP) or a multichip module (MCM). A specific example of such an apparatus is the invention of Japanese Utility Model Laid-Open No. 62-158840. That is, a plurality of chips are stacked in a single ceramic package, and the electrodes of each chip are connected by wires. As another example, as in the invention of JP-A-11-135711, a semiconductor chip is mounted on a wiring board called an interposer, the interposers are connected to each other, and stacked to form a single semiconductor device. Is.
[0003]
[Problems to be solved by the invention]
However, when the semiconductor chips to be stacked are substantially the same size, in the invention of Japanese Utility Model Publication No. 62-158840, the semiconductor chip other than the semiconductor chip located at the uppermost part is a semiconductor chip whose electrode is located at the upper level. Since it is in a hidden state, bonding becomes difficult. In the invention of Japanese Patent Application Laid-Open No. 11-135711, it is easy to stack semiconductor chips of substantially the same size to form a single semiconductor device. However, each semiconductor chip is mounted on an interposer, and further, the interposer In order to secure the electrical connection between them, a more complicated manufacturing process is required than the invention of Japanese Utility Model Laid-Open No. 62-158840.
[0004]
Accordingly, the present invention has been made to solve the above-described disadvantages of the prior art, and is a semiconductor that can be stacked without using an interposer and can electrically connect stacked semiconductor chips regardless of their sizes. An object of the present invention is to provide an apparatus, a manufacturing method thereof, and an electronic apparatus.
[0005]
[Means for Solving the Problems]
Accordingly, in order to achieve the above object, the present invention provides a method of manufacturing a semiconductor device in which a plurality of semiconductor chips are stacked, a step of forming a through hole in the plurality of stacked semiconductor chips, and the through Forming an insulating film on the inner periphery of the hole; forming a first metal film on the insulating film; forming a second metal film on the first metal film; And a step of forming a eutectic alloy of the first metal and the second metal leaving the through hole.
[0006]
In the present invention configured as described above, the conductive means can be easily provided on the inner peripheral surface of the through hole formed in the stacked semiconductor chips. Further, if the conductive means is used, it is possible to ensure electrical continuity of the stacked semiconductor chips without using auxiliary means such as an interposer.
[0007]
In addition, after forming a through-hole, the process of forming an insulating film in the internal peripheral surface of a through-hole may be performed, and a metal film | membrane may be formed after that. In the case of forming an insulating film, the stacked semiconductor chips can be heated in an oxidizing atmosphere to thermally oxidize the silicon substrate. In this case, a material that is not thermally oxidized may be used for the electrode pad of the semiconductor chip. The insulating film can be formed by depositing a silicon oxide film, a silicon nitride film, or the like on the inner surface of the through hole by CVD or the like.
[0008]
When a metal film is formed on the insulating film and this metal film is electrically connected to the electrode pad of the semiconductor chip, if the insulating film is formed by thermal oxidation, the electrical connection between the metal film and the electrode pad is reduced. Therefore, the process of removing the insulating film is not required, and the process can be simplified. On the other hand, when an insulating film is formed on the inner peripheral surface of the through hole by CVD or the like and a metal film is provided on the insulating film to electrically connect the metal film and the electrode pad of the semiconductor chip, the electrode pad is covered. A metal film is formed after removing at least a part of the insulating film. In this case, a step of removing the insulating film is required. However, since there is no possibility that the electrode pad is oxidized, the electrode pad can be formed of a metal that is easily oxidized, such as copper, and the choice of materials can be widened.
[0009]
The through hole is preferably formed so as to drill at least a part of the electrode pads of the stacked semiconductor chips.
[0010]
In the method of manufacturing a semiconductor device, the first metal film and the second metal film are formed by plating.
[0011]
In the present invention configured as described above, another electrode can be appropriately formed according to the interval, arrangement, etc. between the electrodes of the adjacent semiconductor chips, so that the electrical connection between the semiconductor chips can be more reliably ensured. .
[0012]
In the method of manufacturing a semiconductor device, the first metal film and the second metal film are also formed in the vicinity of the opening of the through hole.
[0013]
In the present invention configured as described above, the first metal film and the second metal film formed in the vicinity of the opening of the through hole are provided for electrical connection with an external device such as a substrate. As a result, electrical continuity with the external device can be ensured more reliably.
[0014]
In the semiconductor device manufacturing method, the first metal film and the second metal film are heated by irradiating at least the inner peripheral surface with laser light, and the first metal and the second metal film are heated. A eutectic alloy with the second metal is formed.
[0015]
In the present invention configured as described above, the eutectic of these metals is formed on the first metal film and the second metal film formed on the inner peripheral surface of the through-hole or the like by being heated with the laser beam. An alloy can be easily formed.
[0016]
Further, in the method of manufacturing a semiconductor device, the plurality of stacked semiconductor chips are heated while being pressed in the stacking direction to form a eutectic alloy of the first metal and the second metal. It was supposed to be a feature.
[0017]
In the present invention configured as described above, by heating while applying pressure, the first metal film and the second metal film formed on the inner peripheral surface or the like of the through-hole are shared by these metals. The formation of a crystal alloy can be promoted, and the semiconductor chips can be bonded more firmly.
[0018]
In the method of manufacturing a semiconductor device, the eutectic alloy of the first metal and the second metal is formed while irradiating the plurality of stacked semiconductor chips with ultrasonic waves. To do.
[0019]
In the present invention configured as described above, formation of a eutectic alloy is promoted by ultrasonic waves.
[0020]
Further, the semiconductor device is manufactured by any one of the above-described semiconductor device manufacturing methods.
[0021]
In the present invention configured as described above, auxiliary means such as an interposer is not required to ensure electrical conduction between the stacked semiconductor chips, and the semiconductor device can be miniaturized.
[0022]
In addition, an electronic apparatus includes the semiconductor device described above.
[0023]
In the present invention configured as described above, a semiconductor device smaller than the conventional one can be used, so that the electronic device itself can be easily reduced in size.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, preferred embodiments of a semiconductor device, a manufacturing method thereof, and an electronic apparatus according to the present invention will be described in detail with reference to the accompanying drawings.
[0025]
FIG. 1 is a cross-sectional view schematically showing a semiconductor device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view (1) illustrating the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 3 is a cross-sectional view (2) illustrating the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 4 is a cross-sectional view (3) illustrating the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 5 is a cross-sectional view for explaining the manufacturing process of the semiconductor device according to the embodiment of the present invention. FIG. 6 is a cross-sectional view schematically showing a modification of the semiconductor device according to the embodiment of the present invention.
[0026]
A semiconductor device according to an embodiment of the present invention will be described with reference to FIG. In the semiconductor device 100 according to this embodiment, the semiconductor chips 10a, 10b, 10c, and 10d have the same active element formation surface (hereinafter referred to as an active surface) provided with the respective electrode pads 14a, 14b, 14c, and 14d. They are stacked in a state aligned in the direction. The electrode pads 14a, 14b, 14c, and 14d are connected to circuits (not shown) formed in the semiconductor chips 10a, 10b, 10c, and 10d, respectively. The stacked semiconductor chips 10a, 10b, 10c, and 10d are bonded by adhesives 20a, 20b, and 20c interposed between these semiconductor chips.
[0027]
Further, the semiconductor chips 10a, 10b, 10c, and 10d are provided with through holes 12 that penetrate these in the stacking direction. A conductive film 16 is formed on the inner peripheral surface of the through hole 12. The conductive film 16 is made of silver (Ag) and tin (Sn) and their eutectic alloys. A method for forming the eutectic alloy will be described later. Alternatively, an insulating film such as a silicon oxide film may be formed on the inner peripheral surface of the through hole 12 and the conductive film 16 may be formed on the insulating film.
[0028]
Further, the end portions 18 a and 18 b of the conductive film 16 are exposed to the outside from the through hole 12. In addition, a part of the end 18a is connected to the electrode pad 14d. The conductive film 16 is connected to the electrode pads 14 a, 14 b, and 14 c inside the through hole 12. Therefore, the end portions 18a, 18b and the electrode pads 14a, 14b, 14c, 14d are electrically connected.
[0029]
According to the embodiment of the present invention described above, if a terminal or the like of an external device is connected to one of the end portions 18a and 18b of the conductive film 16, the semiconductor chips 10a, 10b, 10c, It is connected to the electrode pads 14a, 14b, 14c, and 14d of 10d. Therefore, the stacked semiconductor chips and the external device can be electrically connected regardless of the size of the stacked semiconductor chips. Also, no auxiliary means such as an interposer is required.
[0030]
Note that the number of stacked semiconductor chips is not limited to four, and may be any other number. Moreover, the size of the stacked semiconductor chips may be different. Further, a plurality of, for example, all of the through holes 12 may be provided corresponding to the electrode pads as long as the circuit of each semiconductor chip to be stacked is not impaired. Furthermore, a heat sink may be provided between the semiconductor chips 10a, 10b, 10c, and 10d.
[0031]
The conductive film 16 is made of silver and tin, and is made of gold (Au), copper (Cu), zinc (Zn), bismuth (Bi), indium (In), nickel (Ni), etc. and tin. It can be formed. In order to ensure electrical continuity between the electrode pads 14a, 14b, 14c and the conductive film 16, a conductive material such as tin or a tin-based alloy is provided on the electrode pads 14a, 14b, 14c, and the electrode pad 14a , 14b, and 14c, the conductive film 16 and the conductive material may be connected. Further, the through holes 12 may be filled with an organic conductive material such as a conductive paste or an inorganic conductive material such as a zuzu alloy. In this way, electrical continuity between the terminal of the external device and the conductive film 16 can be reliably ensured.
[0032]
Furthermore, the electrode pads 14a, 14b, 14c, and 14d are generally semiconductor chips such as aluminum (Al), aluminum-silicon (Al-Si), copper (Cu), and aluminum-silicon-copper (Al-Si-Cu). Any material may be used as long as it is used as an electrode or wiring. Further, on the electrode pads 14a, 14b, 14c, and 14d, a metal layer generally known as an under bump metal (for example, Ti-W, so as to be able to stably connect to the conductive film 16). Pt—Au, Ni, Cu—Au, etc.) are preferably formed.
[0033]
In addition, an insulating film for protecting the active surface is preferably provided on the active surface of the semiconductor chips 10a, 10b, 10c, and 10d. Specifically, a silicon oxide film (SiO ₂ ) or a silicon nitride film (SiN) is preferably provided as the insulating film. In addition, what is necessary is just to form this insulating film in the semiconductor wafer manufacturing stage as what is mentioned later formed in a semiconductor wafer manufacturing process. Alternatively, the semiconductor wafer may be provided after being divided into semiconductor chips. Further, an insulating film may be formed on the side surfaces and the back surface of the semiconductor chips 10a, 10b, 10c, and 10d by a post-processing method such as potting, vapor deposition, or transfer molding.
[0034]
Next, a method for manufacturing a semiconductor device according to an embodiment of the present invention will be described.
[0035]
First, as shown in FIG. 2A, the semiconductor wafer 40 that has completed the semiconductor chip process is bonded in a laminated state, and laser light is applied to a portion that penetrates at least part of the electrode pads 14a, 14b, 14c, and 14d. Irradiation forms the through-hole 12. Note that the laser beam irradiation must be performed carefully so as not to damage the active element.
[0036]
The through hole 12 may be provided by etching using a wet method or a dry method. When etching by the dry method, the drilling requires more time than the method using laser light, but the roughness of the inner peripheral surface of the through hole 12 is small. As a specific etching method, a wet etching method such as an alkaline solution such as KOH, a dry etching method using an etching gas such as CF _4, a method using plasma, etc. should be used. It ’s fine.
[0037]
In addition, after forming the through-hole 12, you may perform the process of forming an insulating film in the internal peripheral surface of a through-hole, and may form a metal film | membrane after that. In the case of forming an insulating film, the stacked semiconductor chips can be heated in an oxidizing atmosphere to thermally oxidize the silicon substrate. In this case, a material that is not thermally oxidized may be used for the electrode pad of the semiconductor chip. The insulating film can be formed by depositing a silicon oxide film, a silicon nitride film, or the like on the inner surface of the through hole by CVD or the like.
[0038]
Next, as shown in FIG. 2B, a photoresist film 30 is provided by applying a photoresist on both surfaces of the stacked semiconductor chips 10a, 10b, 10c, and 10d, and a portion where a conductive film is provided in a later step. Remove.
[0039]
Next, as shown in FIG. 2C, silver plating is applied to both surfaces of the stacked semiconductor chips 10a, 10b, 10c, and 10d to provide a silver thin film 16a.
[0040]
Subsequently, as shown in FIG. 3A, tin plating is performed to provide a tin thin film 16b on the silver thin film 16a.
[0041]
Next, as shown in FIG. 3B, the photoresist film 30 is removed. The method of providing the conductive material in the connection hole 18 is not limited to the plating method, and may be formed by other methods such as filling a conductive paste or solder and forming a protrusion.
[0042]
Next, as shown in FIG. 4, the inside of the through-hole 12 is irradiated with a laser beam 32 and heated to melt the silver thin film 16a and the tin thin film 16b, thereby forming a eutectic alloy of silver and tin. Form. It is preferable to heat the silver thin film 16a and the tin thin film 16b so that the eutectic alloy is reliably formed at 221 ° C. or higher. The eutectic alloy can be formed by using tin and a metal other than silver as described above, but when heated at a relatively low temperature to prevent excessive thermal stress from being applied to the semiconductor chip. However, it is preferable to use a metal capable of forming a eutectic alloy.
[0043]
Moreover, instead of irradiating and heating with laser light, as shown in FIG. 5, the semiconductor chips 10a, 10b, 10c, and 10d stacked with a heating and pressing tool may be sandwiched and heated while being pressed. Thus, when heated under pressure, formation of a eutectic alloy with these metals can be promoted on the silver thin film 16a and the tin thin film 16b formed on the inner peripheral surface of the through-hole 12, and each semiconductor chip. They can be joined together more firmly.
[0044]
When an insulating film is formed on the inner peripheral surface of the through hole 12 and a conductive film 16 is provided thereon, and the conductive film 16 and the electrode pad of the semiconductor chip are electrically connected, the insulating film is thermally oxidized. When formed, the process of removing the insulating film is not required for electrical connection between the conductive film 16 and the electrode pad 14, and the process can be simplified. On the other hand, when an insulating film is formed on the inner peripheral surface of the through-hole 12 by CVD or the like, a conductive film 16 is provided on the insulating film, and the conductive film 16 and the electrode pad of the semiconductor chip are electrically connected, After removing at least part of the covering insulating film, a metal film (conductive film 16) is formed. In this case, a step of removing the insulating film is required. However, since there is no possibility that the electrode pad is oxidized, the electrode pad can be formed of a metal that is easily oxidized, such as copper, and the choice of materials can be widened.
[0045]
In the above-described embodiment, the through hole and the conductive film are formed to electrically connect the stacked semiconductor chips. However, the stacked semiconductor chips are not electrically connected. In order to secure an electrical conduction path between the upper surface and the lower surface of the chip, the following configuration is preferable.
[0046]
That is, as shown in FIG. 6, a through hole 36 is provided in a portion that does not penetrate the electrode pads of the semiconductor chips 10a, 10b, 10c, and 10d. Then, the insulating film 22 is formed on the inner peripheral surface of the through hole 36, and the conductive film 16 is formed on the insulating film 22. The configuration of the conductive film 16 is the same as that described above.
[0047]
With the configuration as described above, the semiconductor chips 10a, 10b, 10c, and 10d and the conductive film 16 are insulated by the insulating film 22, and therefore, only electrically between the end portions 18a and 18b of the conductive film 16. Conductivity can be ensured.
[0048]
The insulating film 22 can be formed, for example, by heating the laminated semiconductor chips 10a, 10b, 10c, and 10d in an oxidizing atmosphere and oxidizing the silicon substrate exposed on the inner peripheral surface of the through hole 36. In this case, a material that is not thermally oxidized may be used for the electrode pad of the semiconductor chip. The insulating film 22 can be formed by depositing a silicon oxide film, a silicon nitride film, or the like by CVD or the like.
[0049]
As described above, since the mounting area of the semiconductor device 100 in FIG. 1 can be reduced to the area where it is mounted with a bare chip, if the semiconductor device 100 is used in an electronic device, the electric device itself can be downsized. .
[0050]
【The invention's effect】
As described above, according to the present invention, in a method of manufacturing a semiconductor device in which a plurality of semiconductor chips are stacked, a step of forming a through hole in the plurality of stacked semiconductor chips, Forming an insulating film on an inner peripheral surface; forming a first metal film on the insulating film; forming a second metal film on the first metal film; And a step of forming a eutectic alloy of the first metal and the second metal, so that the semiconductor chips can be electrically connected to each other only by stacking the semiconductor chips. Therefore, a process for electrically connecting the semiconductor chips is not necessary. In addition, since the layers can be stacked without using an auxiliary means such as an interposer, it contributes to downsizing of the semiconductor device and significantly contributes to cost reduction of the semiconductor device.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view schematically showing a semiconductor device according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view (1) illustrating a manufacturing step of the semiconductor device according to the embodiment of the present invention.
FIG. 3 is a cross-sectional view (2) illustrating the manufacturing process of the semiconductor device according to the embodiment of the present invention;
FIG. 4 is a cross-sectional view (3) illustrating the manufacturing process of the semiconductor device according to the embodiment of the present invention.
FIG. 5 is a cross-sectional view (4) illustrating a manufacturing step of the semiconductor device according to the embodiment of the present invention.
FIG. 6 is a cross-sectional view schematically showing a modified example of the semiconductor device according to the embodiment of the present invention.
[Explanation of symbols]
10a ... Semiconductor chip 10b ... Semiconductor chip 10c ... Semiconductor chip 10d ... Semiconductor chip 12 ... Through-hole 14a ... Electrode pad 14b ... Electrode pad 14c ... Electrode pad 14 ... ...... Electrode pad 16 ...... Conductive film 16 a ...... Silver thin film 16 b ...... Tin thin film 18 a ...... End 18 b ...... End 20 a ...... Adhesive 20 b ...... Adhesive 20 c …… Adhesive 22 ...... Insulating film 30 ...... Photoresist film 32 ...... Laser beam 34 ...... heating and pressing tool 36 ...... through hole 40 ...... laminated semiconductor wafer 100 ...... semiconductor apparatus

Claims (8)

In a method for manufacturing a semiconductor device in which a plurality of semiconductor chips are stacked,
A step of forming a through hole in the semiconductor chip laminated a plurality of;
Forming an insulating film on the inner periphery of the through hole;
Forming a first metal film on the insulating film;
Forming a second metal film on the first metal film;
And a step of forming a eutectic alloy of the first metal and the second metal leaving the through hole.   2. The method of manufacturing a semiconductor device according to claim 1, wherein the first metal film and the second metal film are formed by plating.   3. The method of manufacturing a semiconductor device according to claim 1, wherein the first metal film and the second metal film are also formed in the vicinity of the opening of the through hole. At least the inner peripheral surface is irradiated with laser light to heat the first metal film and the second metal film to form a eutectic alloy of the first metal and the second metal. the method of manufacturing a semiconductor device according to any one of claims 1 to 3, characterized in that. 4. The eutectic alloy of the first metal and the second metal is formed by heating the plurality of stacked semiconductor chips while pressing them in the stacking direction. A method for manufacturing a semiconductor device according to any one of the above. Manufacturing a semiconductor device according to claim 5, characterized in that forming said plurality stacked semiconductor chip eutectic alloy of said second metal and said first metal while ultrasonic waves Method.   A semiconductor device manufactured by the method for manufacturing a semiconductor device according to claim 1.   An electronic apparatus comprising the semiconductor device according to claim 7.

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