JP4058182B2 - Resin sealing method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention clamps a molded product printed with a sealing resin by a printing process so as to fill a space between the metal pillars in which a plurality of metal pillars are erected on a wiring layer formed on a semiconductor wafer with a mold. The present invention also relates to a resin sealing method in which the resin is molded by heat curing in a transfer molding process.
[0002]
[Prior art]
In order to manufacture a semiconductor integrated circuit (LSI) such as a chip size package, a semiconductor wafer process and a package process are combined. That is, in the semiconductor wafer process, a well is formed in a bare wafer, a transistor is formed through an insulating film, a wiring layer is formed through an insulating film, a passivation film is formed, and an electrode pad is formed. It was broken. In the package process, after performing a wafer test, it is cut into chips, die-bonded to a substrate in which a wiring layer is previously formed on a base film, and electrically connected to the substrate by wire bonding or the like, and then a semiconductor The chip mounting surface was sealed with resin, solder balls were joined as external connection terminals, marking and trimming were performed, functional tests were performed, and chip size packages were manufactured.
[0003]
In recent years, the miniaturization of semiconductor chips has progressed as LSIs are mounted with higher density and higher integration. In the semiconductor wafer process in which transistors and wirings are formed on a semiconductor wafer, the smaller the semiconductor chip, the smaller the size of the semiconductor chip. Since the number increases and the productivity improves, the production cost can be reduced. However, in the package process, the package size does not change even if the chip size is reduced, so the outer dimensions remain constant. For this reason, the productivity of the package process is not improved, and the appearance of a package in which the outer dimension of the package is the same as the outer dimension of the chip is desired.
[0004]
Therefore, recently, as shown in Japanese Patent Laid-Open No. 10-79362, a package is obtained by cutting at the semiconductor wafer level, that is, the package has the same outer dimensions as the chip, so-called semiconductor wafer level. Chip size packages have been proposed. This is because, in a semiconductor wafer process, after forming a plurality of transistors and wiring on a semiconductor wafer, rewiring from the electrodes around the chip toward the center of the chip, and metal posts connected to external connection terminals are provided here. Stand up and seal the periphery with resin. Then, after marking the molded product and joining the solder balls to be electrically connected to the metal posts, the semiconductor wafer is cut for each chip and a function test is performed to manufacture a chip size package.
As a result, the packaging process is integrated with the semiconductor wafer process to reduce the number of processes and improve the throughput, and the manufacturing equipment required for the packaging process can be omitted, so that the manufacturing cost can be reduced, and the lot management is facilitated while saving space. The package productivity can be significantly improved.
[0005]
In the manufacturing process of the semiconductor wafer level chip size package, in the resin sealing process, the semiconductor wafer is placed on the lower mold instead of the transfer mold method in which the semiconductor wafer is clamped with the mold and sealed with the sealing resin. A compression molding method is employed in which a solid sealing resin is placed on the center of a semiconductor wafer and is simply compression molded.
In this compression molding method, a relatively hard temporary film slightly larger than the diameter of the semiconductor wafer is interposed between the sealing resin and the mold so that the sealing resin does not adhere to the tip of the mold or the metal post. It has become. The sealing resin is placed in the middle of the semiconductor wafer and is clamped between the upper mold and the lower mold so that the sealing resin is filled between the metal posts.
Further, after sealing the resin, the temporary film is peeled off from the molded product, so that the sealing resin on the metal post adheres to the temporary film and exposes the surface where the solder bumps are joined.
[0006]
[Problems to be solved by the invention]
However, in the compression molding method, the sealing resin is poured into the periphery while being compressed by the mold, so that it is difficult to uniformly flow the sealing resin into the space where the metal post stands. It takes time until the sealing resin spreads to the periphery. Accordingly, it takes time for the resin sealing process, and the resin amount of the molded product tends to vary, which may reduce the molding quality. Also, the temporary film interposed between the end face of the metal post and the mold is relatively hard, and the sealing resin on the metal post adheres to the temporary film by peeling the temporary film from the molded product after resin sealing. Since the surface to which the solder bumps are bonded is exposed, the sealing resin often enters the end face of the metal post and is sealed with the resin. When the temporary film is peeled off, the sealing resin is also peeled off together. Although it is easy, resin residue may occur on the end face of the metal post. As a result, the bonding strength of the bonding surface of the solder ball may be reduced.
[0007]
The object of the present invention is to solve the above-mentioned problems of the prior art, to fill the sealing resin between the metal pillars uniformly and quickly by printing, to improve the molding quality of the molded product, and to connect the external connection terminal An object of the present invention is to provide a resin sealing method in which sealing resin does not adhere to the end face of a metal pillar.
[0008]
[Means for Solving the Problems]
The present invention has the following configuration in order to solve the above problems.
That is, a sealing resin is applied by printing so as to fill a space between the metal pillars in which a plurality of metal pillars are erected in a wiring layer formed on a semiconductor wafer, and at least a molded article to which the sealing resin is applied is applied. release film covering the outer surface and the metal pillars end face of the semiconductor wafer is placed on each stretched been mold on the parting face of the upper mold and the lower mold, the molded article through the release film at upper and lower mold And the sealing resin is heat-cured and molded .
[0009]
Also, the molding die has a feature in that the end faces of the metal pillars by end surfaces of the metal pillars that are formed on the molded article is clamped bite on the release film is exposed form the resin sealing surface To do.
In addition, the release film is applied to the sealing resin applied between the metal pillars when clamping a formed product formed at a plurality of locations on the semiconductor wafer on the parting surface of the mold. through uneven surface partitioned into a lattice shape enters each be formed article by the features that you have been formed.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described below in detail with reference to the accompanying drawings.
In this embodiment, a resin sealing method for manufacturing a semiconductor wafer level chip size package will be described.
FIG. 1 is an explanatory view showing a state in which a semiconductor wafer on which metal pillars are erected is sealed with resin, FIG. 2 is an explanatory view showing a configuration of a main part of a mold, and FIG. 3 is a chip formed on the semiconductor wafer. FIG. 4 is an explanatory diagram showing the structure of the upper mold parting surface, and FIG. 5 is an explanatory diagram showing the main configuration of a mold according to another example.
[0011]
First, a schematic configuration of a semiconductor wafer level chip size package will be described with reference to FIG. After a plurality of transistors and wiring are formed on the semiconductor wafer 1, copper plating is applied from the electrode on the periphery of the chip toward the center of the chip, patterning and rewiring are performed, and solder balls are joined as external connection terminals here. A metal pillar (metal post) 2 is set up and its periphery is sealed with a sealing resin 3 to form a molded product. This resin sealing step is performed by printing a plurality of chip surfaces formed on the semiconductor wafer 1 by supplying a liquid resin or a semi-fluid resin with a squeegee unit as disclosed in, for example, Japanese Patent Laid-Open No. 5-114620. Evenly applied.
Then, the molded product is carried into the mold 4 and clamped, whereby the sealing resin 3 is cured by heating and molded. After the resin sealing, the molded product is marked, and the semiconductor wafer 1 is cut into individual pieces for each chip to form a semiconductor wafer level chip size package. If necessary, the solder balls may be joined to the end face of the metal post 2 exposed from the sealing resin 3 to the outer surface.
[0012]
FIG. 2 shows a configuration of a mold 4 for carrying in a product to be molded and heat-curing it. The mold 4 includes an upper mold 6 having a heater 5 and a lower mold 8 having a heater 7, and a cavity recess 9 capable of accommodating the semiconductor wafer 1 is formed on the lower mold 8 side.
Release films 10 are stretched on the upper and lower parting surfaces of the mold 4. The release film 10 is either a long film wound between a delivery reel and a take-up reel, a film cut into a strip shape to cover the circular semiconductor wafer 1 shown in FIG. May be used in combination. The release film 10 covers the outer surface of the semiconductor wafer 1 so that the sealing resin 3 does not directly adhere to the parting surface of the mold 4 and does not enter the end surface of the metal post 2. The metal post 2 is clamped so as to bite into the release film 10.
[0013]
As will be described later, the release film 10 has the flexibility to be sucked and supported in the shape of the inner surface of the cavity recess 9 by air suction, and has heat resistance that can withstand the heating temperature of the mold 4. Further, it is necessary to be able to be easily released from the mold die 4 after resin sealing and easily peeled off from the sealing resin. As such a film, for example, an FEP film, a fluorine-impregnated glass cloth, a PET film, an ETFE film, a polypropylene film, a polyvinylidin chloride and the like are preferably used. The release film 10 may be either a long one wound by a feeding mechanism and a winding mechanism or one cut into a strip shape.
The mold 4 is equipped with a suction holding means (not shown) for holding the release film 10 on the parting surface. Specifically, a cavity suction hole 12 opening in a slit shape is formed on the inner bottom surface of the cavity recess 9. Further, suction holes (not shown) are formed in the parting surfaces of the upper mold 6 and the lower mold 8. These cavity suction holes 12 and suction holes are connected to an external air suction mechanism (not shown) via an air flow path provided in the mold base.
[0014]
As shown in FIG. 4, when clamping the semiconductor wafer 1, the upper mold 6 enters the sealing resin 3 and partitions each chip size package 11 via a release film 10 when clamping the semiconductor wafer 1. The uneven surface 13 may be formed.
When the mold 4 clamps the molded product to which the sealing resin 3 is applied, the convex portion of the concave-convex surface 13 of the upper mold 6 enters the sealing resin 3 through the release film 10 and the sealing resin 3 is sealed. The stop resin 3 is partitioned into a lattice shape while escaping to the periphery, and each chip size package 11 is heat-cured and molded. In this case, when the semiconductor wafer 1 is cut into individual pieces for each chip size package 11 in a subsequent process, only the semiconductor wafer 1 is cut rather than cutting the sealing resin 3 and the semiconductor wafer 1. Since it is good, there is an advantage that it is easy to cut.
[0015]
In the resin sealing process of the present embodiment, a plurality of metal posts 2 are erected on a wiring layer formed on the semiconductor wafer 1, and the sealing resin 3 is squeegee unit (not shown) so as to fill the space between the metal posts 2. ) Is placed in the mold 4 with the release film 10 stretched on the parting surface, clamped with the upper mold 6 and the lower mold 8 via the release film 10, and sealed Although the resin 3 is cured by heating, the molded product in which a plurality of metal posts 2 are connected to the wiring layer formed on the semiconductor wafer 1 is stretched on the parting surface. After the sealing resin 3 is printed so that a squeegee unit (not shown) enters the mold mold 4 which is placed and opened and fills the space between the metal posts 2, the upper mold 6 and the lower mold Released with 8 Through Irumu 10 may be molded by heat curing the sealing resin 3 is clamped.
Further, as shown in FIG. 5, when the cavity bottom 14 is movable, if the sealing resin 3 is printed slightly by the squeegee unit (not shown), A little extra sealing resin 3 is placed between the metal posts 2 to uniformly seal the spaces between the posts. Thereafter, when the mold 4 is clamped, the cavity bottom 14 is slightly moved upward to return it to the original position, so that the tip of the metal post 2 is buried in the release film 10, and the resin is sealed by this burying amount. The exposure amount in the height direction of the end face of the metal post 2 can be controlled. Note that various mechanisms such as a spring, an air cylinder, and an electric motor can be adopted as a mechanism for moving the cavity bottom 14.
[0016]
According to the above configuration, since the sealing resin 3 is applied between the metal posts 2 by printing, compared to the compression molding method in which the sealing resin is placed on the center of the semiconductor wafer placed on the mold and compression molded. It is possible to fill the sealing resin 3 uniformly and quickly so that the sealing resin 3 can be quickly filled and the molding quality of the molded product can be improved.
In addition, the molded article filled with the sealing resin 3 is clamped by the mold 4 on which the release film 10 is stretched and thermally cured to form the metal post 2 exposed on the resin sealing surface. The end surface can bite into the release film 10 so that the sealing resin 3 does not adhere to it, and no resin residue or the like is generated on the joint surface of the external connection terminal such as a solder ball, so that the joining property can be maintained well.
[0017]
【The invention's effect】
In the present invention, as described above, a plurality of metal pillars are erected on the wiring layer formed on the semiconductor wafer, and a sealing resin is applied by printing so as to fill between the metal pillars, and the sealing resin is printed. The molded product is placed in a mold mold in which a release film is stretched on the parting surface, and clamped through the release film with the upper mold and the lower mold, and the sealing resin is heat-cured and molded, or Molded product with multiple metal pillars standing on the wiring layer formed on the semiconductor wafer is placed in a mold mold with release film stretched on the parting surface, and sealed between the metal pillars After applying the resin by printing, the upper mold and lower mold are clamped via a release film and the sealing resin is heated and cured, so the sealing resin is placed on a conventional mold and compression molded. To play Compared to the metal mold method, the sealing resin is applied between the metal pillars by printing, so the sealing resin is uniformly and quickly filled, and the sealing resin is quickly filled and the molded product is molded. Quality can be improved.
In addition, the molded product filled with the sealing resin is clamped by a mold with a release film stretched and thermally cured, so the end face of the metal post exposed on the resin sealing surface is the release film. It is possible to prevent the sealing resin from adhering to the surface, and since no resin residue or the like is generated on the joint surface of the external connection terminal such as a solder ball, the bondability can be maintained satisfactorily.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing a state in which a semiconductor wafer on which metal pillars are erected is sealed with resin.
FIG. 2 is an explanatory view showing a main configuration of a mold.
FIG. 3 is an explanatory diagram of a chip size package formed on a semiconductor wafer.
FIG. 4 is an explanatory view showing a structure of an upper parting surface.
FIG. 5 is an explanatory diagram showing a main configuration of a mold according to another example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Metal post 3 Sealing resin 4 Mold metal mold | die 5,7 Heater 6 Upper mold | type 8 Lower mold | type 9 Cavity recessed part 10 Release film 11 Chip size package 12 Cavity adsorption hole 13 Irregular surface 14 Cavity bottom part

Claims (3)

A sealing resin is applied by printing so as to fill a space between the metal pillars in which a plurality of metal pillars are erected on a wiring layer formed on a semiconductor wafer, and at least a molded product to which the sealing resin is applied is applied to the semiconductor wafer. outer surface and the release film covering the metal pillar end surface is arranged on each stretched been mold on the parting face of the upper mold and the lower mold, the upper mold and the clamp to be molded article through the release film under type And molding the resin by heat-curing the sealing resin. The mold die is characterized in that the end face of each metal pillar is exposed and formed from the resin sealing surface by the end face of the metal pillar formed on the molded product being bitten into the release film and being clamped. The resin sealing method according to claim 1. The clamping resin applied between the metal pillars is clamped on the parting surface of the mold through the release film when clamping a formed product formed at a plurality of locations on the semiconductor wafer. The resin sealing method according to claim 1, wherein an uneven surface that enters and partitions in a lattice shape for each formed product is formed .

Images