This application claims priorities from Japanese Patent Application No. 2010-260708 filed on Nov. 23, 2010, the entire contents of which are incorporated herein by reference.
The present invention relates to a semiconductor device manufacturing method, and a semiconductor device.
In electronic devices such as digital cameras and portable telephones, as realization of the functions, particularly in the image processing, advances, a so-called package-on-package (POP) form is often adapted in order to use two or more semiconductor packages. In the POP form, the semiconductor packages are stacked on each other.
There have been proposed various POP semiconductor packages.
For example, in U.S. Pat. No. 7,777,351-B, a semiconductor package is formed such that a molding resin layer as an insulating material is formed on a top surface of a lower circuit board, conical vias are formed in the insulating material, and solder balls are supplied in the vias so as to be connected with upper connection terminals on the lower circuit board. The top surfaces of the solder balls are exposed upwardly.
Alternatively, a semiconductor package may be formed such that solder balls are supplied to upper connection terminals on a lower circuit board, a molding resin layer as an insulating material is formed on the top surface of the lower circuit board to cover the solder balls, and conical vias are formed above the solder balls so as to upwardly expose the solder balls from the molding resin layer by performing a laser boring process on the molding resin layer.
In order to implement a POP structure, solder balls on the bottom surface of an upper circuit board are respectively arranged in the vias of the above-mentioned lower circuit board, and solder reflow processing is performed, thereby solder-connecting the upper circuit board and the lower circuit board with each other.
When the vias are formed in the lower circuit board by removing the molding resin layer with the laser boring process, it is extremely difficult to completely remove resin components from the surfaces of the solder balls.
If a resin component film remains on the surfaces of the solder balls, even when the solder reflow processing is performed, the solder balls of the lower circuit board will not be surely solder-connected with the solder balls of the upper circuit board. As a result, the reliability of the electrical connection between the boards in the semiconductor package will be deteriorated.
According to an aspect of the present invention, there is provided a semiconductor device manufacturing method, including: preparing a support plate having a mounting portion on which a mounting terminal is mountable; preparing a circuit board having a mounting surface on which a semiconductor chip is mounted and a connection pad is formed; bringing the support plate to face the mounting surface of the circuit board, and connecting the support plate to the connection pad through the mounting terminal; forming a resin layer between the support plate and the mounting surface of the circuit board to cover the mounting terminal; and removing the support plate, thereby forming a via in the resin layer along a shape of the mounting portion so as to expose the mounting terminal therethrough.
According to another aspect of the present invention, there is provided a semiconductor device, including: a circuit board having a mounting surface a semiconductor chip mounted on the mounting surface; a connection pad formed on the mounting surface; a mounting terminal formed on the connection pad; and a resin layer formed on the mounting surface to cover the mounting terminal, the resin layer having a via through which the mounting terminal is exposed, wherein the via is formed by removing a support plate which has abutted the mounting terminal at least when the mounting terminal was formed on the connection pad and the resin layer was formed on the mounting surface to cover the mounting terminal.
According to the above-mentioned aspects of the present invention, the mounting terminal of the semiconductor device is formed by being partly exposed through a via formed in the resin layer along the shape of the solder ball mounting portion on the support plate when the support plate is removed after the solder ball is connected to the connection pad, and the resin layer is formed between the mounting surface of the circuit board and the support plate. Thus, the surface of the solder ball serving as the mounting terminal is put into a clean state when the support plate is removed. Consequently, a residue of the molding resin can be surely prevented from remaining on the surface of the solder ball.
Accordingly, when a POP structure is formed by connecting the semiconductor package substrates to each other, the connection terminals thereof can surely be solder-connected to each other, thereby enhancing the reliability of the electrical connection therebetween.
Hereinafter, a semiconductor device according to a first embodiment is described with reference to
As illustrated in
A molding resin layer 7 is formed on the top surface of the circuit board 2 so as to cover the semiconductor chip 3 and to upwardly expose the solder balls 5 through vias 6, respectively. The top surfaces of the solder balls 5 are put into a clean state when a copper support plate (to be described below) is removed by etching. Thus, there is no resin residue of the molding resin layer 7.
Plural connection terminals 8 are formed on the bottom surface of the circuit hoard 2. A solder ball 9 is mounted on each connection terminal 8.
Next, a manufacturing method for the above-mentioned semiconductor device 1 is described hereinafter with reference to
Referring to
First, a copper thin plate K is prepared as illustrated in
Then, a so-called “half etching” is performed by immersing the copper thin plate K in copper etching solution. Consequently, the non-covered parts of the copper thin plate K are etched to be thin, while the covered parts of the copper thin plate K corresponding to the solder ball mounting portions 11 are maintained. Then, the resist film 12 is peeled. Thus, as illustrated in
Turning back to
Then, flip chip mounting is performed on the circuit board 2 (see
The copper support plate 10 is faced to the circuit board 2 so that the solder balls 5 respectively abut the connection pads 4, and solder reflowing is performed to thereby respectively solder-connect the solder balls 5 to the connection pads 4, as illustrated in
Then, as illustrated in
Thereafter, etching is performed using, e.g., alkali etchant (manufactured by Meltex Incorporated (trade name is “A Process”) to selectively remove only the copper support plate 10 (see
In this state, the vias 6 are formed in the molding resin layer 7 along the shapes of the solder ball mounting portions 11 formed on the copper support plate 10.
Further, the top surfaces of the solder balls 5 are brought into a clean state by the etchant when the copper support plate 10 is removed by etching, and there is no resin residue of the molding resin layer 7.
Solder reflowing may be additionally performed. Then, a solder ball 9 is mounted on each connection terminal 8 formed on the bottom surface of the circuit board 2, as illustrated in
Then, the circuit board 2 is cut at positions P illustrated in
As illustrated in
Hereinafter, a method for stacking another package substrate 13 on the semiconductor device 1 is described with reference to
As illustrated in
Then, the solder reflowing is performed so that the solder balls 14 on the package substrate 13 and the solder balls 5 on the semiconductor device 1 are respectively melt-connected to each other, as illustrated in
On this occasion, the solder balls 14 on the package substrate 13 can easily be arranged in the respective vias 6 formed in the molding resin layer 7 of the semiconductor device 1 because the inverted-cone-like vias 6 expose the respective solder balls 5. Consequently, the package substrate 13 can be mounted easily and surely on the semiconductor device 1.
According to the first embodiment, when the copper support plate 10 is removed by etching, the top portion of each solder ball 5, which is exposed from an associated one of the vias 6 formed in the molding resin layer 7 of the semiconductor device 1, is maintained in a clean state in which no residue of the molding resin layer 7 remains. Consequently, the wettability of each solder ball 5 is enhanced. Thus, the solder balls 5 and the solder balls 14 are surely connected, respectively, and the electrical connection between the semiconductor device 1 and the package substrate 13 is enhanced.
Next, a semiconductor device according to a second embodiment is described hereinafter with reference to
As illustrated in
A molding resin layer 27 is formed on the top surface of the circuit board 22 so as to cover the semiconductor chip 23 and to upwardly expose the solder balls 25 through vias 26, respectively. A metal plating film M formed by a method to be described below is formed on and covers the top surface of each solder ball 25 exposed from an associated one of the vias 26 formed in the molding resin layer 27.
Plural connection terminals 28 are formed on the bottom surface of the circuit board 22. A solder ball 29 is mounted on each connection terminal 28.
Next, a manufacturing method for the above-mentioned semiconductor device 2 is described hereinafter with reference to
Referring to
First, a copper thin plate K is prepared as illustrated in
Then, a so-called “half etching” is performed by immersing the copper thin plate K in copper etching solution. Consequently, the non-covered parts of the copper thin plate K are etched to be thin, while the covered parts of the copper thin plate K corresponding to the solder ball mounting portions 31 are maintained. Then, the resist film 32 is peeled. Thus, as illustrated in
Next, as illustrated in
Then, as illustrated in
In order to form such a metal plating film M, first, the copper support plate 30, on which the electrodeposited resist film 33 having the opening 34 is formed, is immersed in a gold plating bath for a given time.
A plating solution retained in the gold plating bath is made up of 50 grams (g)/liter (l) of potassium citrate, and 50 g/l of tripotassium citrate.
Consequently, a first layer formed of a gold plating film M1 is formed on the solder ball mounting portion 31.
Next, the copper support plate 30 with the gold plating film M1 is immersed in a palladium plating bath for a given time. A plating solution retained in the palladium plating bath is made up of 150 g/l of potassium phosphate, and 15 of Pd(NH3)4Cl2.
Consequently, a second layer formed of a palladium plating film M2 is formed on the gold plating film M1.
Next, the copper support plate 30 with the gold plating film M1 and the palladium plating film M2 is immersed in a nickel plating bath for a given time.
A plating solution retained in the nickel plating bath is made up of 320 g/l of nickel sulphamate.
Consequently, a third layer formed of a nickel plating film M3 is formed on the palladium plating film M2.
Finally, the copper support plate 30 with the first layer, i.e., the gold plating film M1, the second layer, i.e., the palladium plating film M2, and the third layer, i.e., the nickel plating film M3 is immersed in a palladium plating bath for a given time.
A plating solution retained in this palladium plating bath is made up of 150 g/l of potassium phosphate, and 15 g/l of Pd(NH3)4Cl2.
Consequently, a fourth layer formed of a palladium plating film M4 is formed on the nickel plating film M3.
After the metal plating film M configured by the gold plating film M1, the palladium plating film M2, the nickel plating film M3 and the palladium plating film M4 is formed on the solder ball mounting portion 31, the electrodeposited resist film 33 is removed by etching. Thus, the copper support plate 30 in which the metal plating films M are respectively formed on the solder ball mounting portions 31 is obtained, as illustrated in
Turning back to
In the copper support plate 30, as shown in
Then, flip chip mounting is performed on the circuit board 22 (see
The copper support portion 30 is faced to the circuit board 22 so that the solder balls 25 respectively abut the connection pads 24, and solder reflowing is performed to thereby respectively solder-connect the solder balls 25 to the connection pads 24, as illustrated in
Then, as illustrated in
Thereafter, etching is performed using, e.g., alkali etchant (manufactured by Meltex Incorporated (trade name is “A Process”) to selectively remove only the copper support plate 30 (see
At that time, as illustrated in
Solder reflowing may be additionally performed. Then, a solder ball 29 may be mounted on each connection terminal 28 formed on the bottom surface of the circuit board 22, as illustrated in
Then, the circuit board 22 is cut at positions P illustrated in
As illustrated in
Hereinafter, a method for stacking another package substrate 33 on the semiconductor device 21 is described with reference to
As illustrated in
Then, the solder reflowing is performed so that the solder balls 34 on the package substrate 33 and the solder balls 25 on the semiconductor device 21 are respectively melt-connected to each other with the gold plating film M1 and the nickel plating film M2, as illustrated in
On this occasion, the solder balls 34 on the package substrate 33 can easily be arranged in the respective vias 26 formed in the molding resin layer 27 of the semiconductor device 21 because the inverted-cone-like vias 26 expose the respective solder balls 25. Consequently, the package substrate 33 can be mounted easily and surely on the semiconductor device 21.
According to the second embodiment, the metal plating film M having at least three layers of the gold plating film M1, the nickel plating film M2, and the palladium plating film M3 are formed on the solder ball mounting portions 31. In addition, after the copper support plate 30 is removed by etching, the metal plating films M remain at the side of the solder balls 25. The nickel plating film M2 and the gold plating film M1 formed on the top portion of each solder ball 25, which is exposed from an associated one of the vias 26 formed in the molding resin layer 27, is maintained in a clean state in which there is no residue of the molding resin layer 27, when the copper support plate 30 is subjected to etching. Consequently, the wettability of each solder ball 25 is enhanced. Thus, the solder balls 25 and the solder balls 34 are surely connected, respectively, and the electrical connection between the semiconductor device 21 and the package substrate 33 is enhanced.
The above-described embodiments are not limited to the above-described devices/methods as they are, and various improvements and modifications can be made without departing from the scope of the invention.
For example, in the second embodiment, the metal plating films M (each having the four layer structure formed of the gold plating film M1, the palladium plating film M2, the nickel plating film M3, and the palladium plating film M4) are respectively formed on the solder ball mounting portions 31 of the copper support plate 30. After the solder balls 25 are connected to the metal plating films M by solder reflowing (see
As illustrated in
In addition, according to the so-called transfer molding method, the space between the mounting surface of the circuit board 22 and the copper support plate 30 is tilled with epoxy resin. Thus, the molding resin layer 27 is formed (see
The semiconductor device 21 and the manufacturing method therefor illustrated in
In the first and second embodiments, the solder balls 9, 29 are mounted on the connection terminals 8, 28 formed on the bottom surface of the circuit board 2, 22, respectively. However, if the semiconductor devices 1 and 21 are used in a land grid array (LGA) structure, it is unnecessary that the solder balls 9 and 29 are mounted on the connection terminals 8 and 28, respectively.
According to the first and second embodiments, the semiconductor chips 3, 23 are mounted on the circuit boards 2, 22 by flip chip mounting. The cases to which the first and second embodiments can be applied are not limited thereto. The first and second embodiments can be applied to the cases where the semiconductor chip is connected to the circuit hoard by wire bonding, and where the semiconductor device of the so-called chip stack type, in which two semiconductor chips are respectively stacked at upper and lower positions, is configured so that the upper semiconductor chip is mounted on the circuit board by wire bonding, and that the lower semiconductor chip is mounted thereon by flip chip mounting.
According to the first and second embodiments, the metal plating film M has the four layer structure formed of the gold plating film M1, the palladium plating film M2, the nickel plating film M3, and the palladium plating film M4. The structure of the metal plating film M is not limited thereto. The metal plating film M may have a three layer structure formed of e.g., a set of a gold plating film, a nickel plating film, and a palladium plating film, or a set of a gold plating film, a palladium plating film, and a gold plating film.
According to the first and second embodiments, the metal plating film is formed by plating. However, for example, the metal film may be formed by another method such as sputtering.
According to the first and second embodiments, the solder balls 5, 25 are formed as the mounting terminals on the copper support plate 10, 30 or on the circuit board 22 (connection pad 24) by solder reflowing. However, instead of the solder balls, mounting terminals may be formed, for example, by printing solder paste on the connection pad 24.
Instead of the solder balls 5, 25, Cu-core solder balls (solder coated Cu balls) may be used.
Number | Date | Country | Kind |
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2010-260708 | Nov 2010 | JP | national |