JP2008010632A - Method for manufacturing semiconductor device, semiconductor device manufactured thereby, and sheet to be used therein - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor device capable of omitting an independent process for forming a through-hole to prevent a defect from being generated in re-flow. <P>SOLUTION: A die pad 4b having an opening 6 is formed on a metallic plate. A die bonding material 5 is coated on the Ag layer 24 of the die pad, and a semiconductor element 2 is mounted on the die pad 4b so as to clog the opening 6 of the die pad 4b. Then, sealing is performed with a resin 8. Even when resin sealing is performed, the opening 6 is clogged by the semiconductor element 2, so that the resin does not invade the opening 6. When the metallic plate is separated from the resin 8 after the sealing is terminated with the resin 8, the bottom surface of the semiconductor element 2 is exposed in the opening 6 of the die pad 4b. Thus, the through-hole is formed for preventing the defect from being generated in re-flow. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a semiconductor device manufacturing method, a semiconductor device manufactured by the manufacturing method, and a sheet used for the manufacturing method.

A semiconductor package in which a through hole is provided in an insulating substrate on which a semiconductor chip is mounted is known as a prior art in order to prevent occurrence of defects such as package cracking, peeling, and blistering during solder reflow (for example, Patent Document 1). ).
Japanese Patent Laid-Open No. 10-223795

  In the conventional semiconductor package described in Patent Document 1, in order to provide a through hole for preventing the occurrence of defects such as package cracks, machining such as drilling or punching, excimer laser, carbon dioxide gas laser, etc. However, there is a problem that the formation of the through hole is troublesome.

(1) The semiconductor device of the invention of claim 1 includes a semiconductor element, a die pad having an opening, and a semiconductor element mounted so as to close the opening, and an external electrically connected to the semiconductor element by a wire. The die pad and the external electrode are formed by electroforming, and the semiconductor element, the die pad, the wire, and the external electrode are sealed with a resin so that the die pad and the external electrode are exposed on the bottom surface, and the semiconductor element is in the opening It is exposed.
(2) The invention of claim 2 is characterized in that, in the semiconductor device of claim 1, the semiconductor element is fixed to the die pad using any one of Ag paste, insulating paste and adhesive film.
(3) The invention of claim 3 is the semiconductor device according to claim 2, wherein the shape of the opening is substantially cross-shaped.
(4) The semiconductor device of the invention of claim 4 has a semiconductor element, an opening, a die pad on which the semiconductor element is mounted, affixed to the die pad so as to close the opening, and a semiconductor element is adhered to the die pad. An adhesive film; and an external electrode electrically connected to the semiconductor element by a wire. The die pad and the external electrode are formed by electroforming, and the semiconductor element and the die pad are exposed so that the die pad and the external electrode are exposed on the bottom surface. The wire and the external electrode are sealed with resin, and the adhesive film is exposed at the opening.
(5) In the method of manufacturing a semiconductor device according to the fifth aspect of the present invention, a plurality of metal layers each including a die pad having an opening and an external electrode disposed outside the die pad are disposed adjacent to the flexible sheet. Forming the metal layer, mounting the semiconductor element on the die pad so as to close the opening, and electrically connecting the semiconductor element and the external electrode; and the metal layer and the semiconductor element as a resin A resin sealing step for sealing, a peeling step for peeling the flexible sheet to obtain a resin sealing body, and a dividing step for cutting the resin sealing body and dividing it into individual semiconductor devices. Features.
(6) A semiconductor device manufacturing sheet of the invention of claim 6 is a metal plate having flexibility, a die pad formed on the metal plate by electroforming, having an opening, and on which a semiconductor element is mounted, It is also formed by electroforming, and includes an external electrode electrically connected by a semiconductor element and a wire.

  According to the present invention, since the die pad for mounting the semiconductor element is formed by providing the opening by electroforming, it is not necessary to provide a separate step for forming the through hole.

  A semiconductor device according to an embodiment of the present invention will be described with reference to FIG. 1A is a rear view of the semiconductor device 1A, FIG. 1B is a cross-sectional view taken along the line AA ′ of FIG. 1A, and FIG. 1C is a cross-sectional view taken along line BB of FIG. FIG.

  In FIG. 1, reference numeral 1A denotes a semiconductor device having a rectangular shape in plan view, and 2 denotes a semiconductor element mounted on the upper surface of a die pad 4b by a die bonding material 5 made of Ag paste. The die pad 4b is provided with an opening 6 and the bottom surface of the semiconductor element 2 is exposed. An external electrode 3b is disposed outside the die pad 4b. Reinforcing pads 9b are disposed at the four corners of the semiconductor device 1A.

  Ag layers 3a, 4a and 9a are formed on the upper surfaces of the external electrode 3b, die pad 4b and reinforcing pad 9b, and Au layers 3c, 4c and 9c are formed on the lower surfaces of the external electrode 3b, die pad 4b and reinforcing pad 9b, respectively. ing. FIG. 1A shows all the Au layers 3c, 4c and 9c. Hereinafter, a semiconductor device 1A according to an embodiment of the present invention will be described in detail.

  The external electrode 3b and the die pad 4b are made of nickel electroforming (Ni electroforming), and are provided on the bottom surface of the semiconductor device 1A. Therefore, this semiconductor device 1A is a so-called lead frameless type. Here, the external electrode 3b is an electrode for establishing electrical connection between the semiconductor element 2 and a circuit board on which the semiconductor device 1A is mounted. The die pad 4 b is an electrode for mounting the semiconductor element 2. Ag layers 3a and 4a are formed on the upper surfaces of the external electrode 3b and the die pad 4b. The Ag layer 3a on the upper surface side of the external electrode 3b is provided for improving the connectivity of wire bonding, and the Ag layer 4a on the upper surface side of the die pad 4b is replaced with the Ag layer 3a on the upper surface side of the external electrode 3b. It was provided together when forming. On the other hand, Au layers 3c and 4c are formed on the lower surfaces of the external electrode 3b and the die pad 4b. The Au layer is provided to improve solder wettability.

  On the bottom surface of the semiconductor device 1A, reinforcing pads 9b are provided at the four corners in addition to the external electrodes 3b. The reinforcing pad 9b is an electrode for increasing the adhesive strength of the semiconductor device 1A to the circuit board, and the reinforcing pad 9b is connected to the circuit board via solder. Similar to the external electrode 3b, an Ag layer 9a is formed on the upper surface side of the reinforcing pad 9b, and an Au layer 9c is formed on the lower surface side. Therefore, the Au layer 9c is exposed on the bottom surface of the semiconductor device 1A.

  As shown in FIG. 1B, the semiconductor element 2 and the external electrode 3b are electrically connected by an Au wire 7. The semiconductor element 2, the wire 7, the external electrode 3b, the die pad 4b, and the reinforcing pad 9b are sealed with a resin 8 made of an epoxy resin or the like. Such a semiconductor device 1A has a bottom surface disposed on a circuit board coated with a solder paste, and reflows the solder in a reflow furnace, so that the solder is passed through the Au layers 3c, 4c and 9c by solder. It is mounted and bonded to.

  Next, a method for manufacturing the semiconductor device 1A described above will be described with reference to FIGS. This manufacturing method includes a metal layer forming step, a semiconductor element mounting step, a resin sealing step, a metal plate peeling step, and a dividing step, and simultaneously produces a plurality of semiconductor devices 1A on one metal plate. . Hereinafter, each process will be described in the order of processes.

(A) Metal layer formation process
The metal layer forming step will be described with reference to FIGS.
As shown in FIG. 2A, a resist 22 is applied or laminated on both surfaces of a flexible metal plate 21. The metal plate 21 is made of a thin metal plate such as a flat JIS standard SUS stainless steel plate or Cu plate having a thickness of about 0.1 mm. Next, an acrylic film-based pattern mask film is brought into intimate contact and exposed to ultraviolet rays. Then, development is performed, and as shown in FIG. 2B, a portion of the resist 22 where the external electrode 3b, the die pad 4b, and the reinforcing pad 9b are to be formed is removed. Here, the resist 22-6 in the portion where the opening 6 of the die pad 4b is formed is left. Since no metal layer is formed on one surface of the metal plate 21, the entire surface is covered with the resist 22.

  Next, the metal plate 21 is immersed in an Au plating solution, electric power is supplied to the metal plate 21 and electroforming is performed, and the Au layer 23 is formed on the metal plate 21. Next, the metal plate 21 on which the Au layer 23 is formed is immersed in a Ni plating solution and electroformed to form the Ni layer 24. Furthermore, the Ag layer 25 is formed on the Ni layer 24 by immersing the metal plate 21 in the Ag plating solution and supplying power to the metal plate 21. In this way, as shown in FIG. 2C, the patterned Au layer 23, Ni layer 24, and Ag layer 25 are formed on the metal plate 21 as metal layers. After forming the metal layer, the resist 22 is peeled from the metal plate 21 as shown in FIG.

(B) Semiconductor element mounting process The semiconductor element mounting process will be described with reference to FIGS.
As shown in FIG. 2E, the die bonding material 5 is applied to the Ag layer 25 corresponding to the Ag layer 4a of the die pad 4b. The die bonding material 5 is made of Ag paste. Then, as shown in FIG. 2F, the semiconductor element 2 is mounted so as to close the opening 6 of the die pad 4b. Although omitted in FIG. 2, a plurality of patterned Ni layers 24 are arranged in parallel on the metal plate 21, and the semiconductor element 2 is mounted adjacently on each patterned Ni layer 24. . After mounting the semiconductor element 2, the die bonding material 5 is heated. Then, the terminals provided in the peripheral region of the semiconductor element 2 and the Ag layer 25 corresponding to the Ag layer 3a of the external electrode 3b are connected by the wire 7 by wire bonding.

(C) Resin sealing process The resin sealing process is demonstrated with reference to Fig.3 (a) and FIG.
In the resin sealing step, the semiconductor element 2, the wire 7, the Au layer 23, the Ni layer 24, and the Ag layer 25 are sealed with the resin 8 as shown in FIG. Resin sealing is performed as follows. As shown in FIG. 4, a mold 41 is placed on the surface of the metal plate 21 on which the semiconductor element 2 is mounted. Then, the resin 8 is injected into the mold 41, and the plurality of semiconductor elements 2 mounted on the metal plate 21 are sealed together. In this resin sealing step, the mold 41 serves as an upper mold, and the metal plate 21 serves as a lower mold. Since the opening 6 is blocked by the semiconductor element 2, the resin 8 does not enter the opening 6.

(D) Metal plate peeling process A metal plate peeling process is demonstrated with reference to FIG.3 (b).
After the sealing with the resin 8 is completed, the metal plate 21 is peeled from the Ni layer 24 and the resin 8 as shown in FIG. Since the metal plate 21 has flexibility, it can be easily peeled off. Since the resin 8 does not enter the opening 6, the Au layer 23 on the bottom surface of the semiconductor element 2 is exposed when the metal plate 21 is peeled off. Hereinafter, the metal plate 21 is peeled off and is referred to as a resin sealing body 30A.

(E) Division Step The division step will be described with reference to FIGS. 3 (b) and 3 (c).
The resin sealing body 30A is diced by a diamond blade dicing method along the dotted line 34 in FIG. And as shown in FIG.3 (c), one resin sealing body 30A is divided | segmented and the semiconductor device 1A is completed.

The semiconductor device 1A according to the first embodiment of the present invention described above has the following operational effects.
(1) An opening 6 is provided in the die pad 4b on which the semiconductor element 2 is mounted to form a through hole for preventing a defect from occurring during reflow. Therefore, in order to form the through hole, another new process, for example, a machining process or a laser machining process is not necessary.

(2) Since the die pad 4b is formed by electroforming, the size and shape of the opening 6 of the die pad 4b can be freely changed by changing the mask at the time of electroforming. Therefore, the shape of the opening 6 can be appropriately selected so as to effectively prevent the occurrence of defects such as package cracking, peeling, and blistering during solder reflow. From the viewpoint of heat dissipation of the semiconductor element 2 by the die pad 4b, the smaller the area of the opening 6, the better.

(3) Since Ag paste is used for the die bonding material 5, heat generated from the semiconductor element 2 can be quickly conducted to the die pad 4b.

(4) Since the semiconductor element 2 is mounted on the die pad 4b so as to close the opening 6, the resin 8 does not enter the opening 6 in the resin sealing step. Therefore, it is not necessary to separately provide a member that prevents the resin 8 from entering the opening 6.

The semiconductor device 1A of the above embodiment can be modified as follows.
(1) The shape of the opening 6 of the die pad 4b in the semiconductor device 1A is not limited to the embodiment. For example, as shown in FIG. 5, the shape of the opening 6 of the die pad 4b in the semiconductor device 1B may be a substantially cross shape. Compared to the case where the shape of the opening 6 is made circular by making the shape of the opening 6 substantially cross-shaped and applying the die bonding material 5 at four locations as shown in FIG. 6 can be made difficult to protrude.

(2) The number of openings 6 of the die pad 4b in the semiconductor device 1A is not limited to 1 as in the embodiment. For example, as shown in FIG. 7, the number of openings 6 of the die pad 4b in the semiconductor device 1C may be four.

(3) Although the external electrode 3b is made of Ni, it is not limited to Ni as long as it is a conductive metal. For example, a Cu electrode or a Ni / Co alloy electrode formed by electroforming may be used.

(4) Although the metal layer for wire connection and the metal layer for solder connection are formed by plating, they may be formed by vacuum deposition or CVD.

(5) Although the Ag layer 3a is formed on the upper surface side of the external electrode 3b, the Ag layer 3a is not limited to the Ag layer as long as the wire 7 and the external electrode 3b can be connected. For example, an Au layer may be formed. Further, when the wire 7 can be directly connected to the external electrode 3b, the Ag layer may not be formed.

(6) Although the Au layer 23 is formed in the metal layer forming step, the Au layer 23 is not limited to the Au layer 23 as long as it is a metal layer for joining the external electrode 4b and the solder. For example, a Sn layer, a Sn—Ag layer, A Sn—Cu layer, a Sn—Bi layer, or a Sn—Pb layer may be formed. Further, when the external electrode 4b and the solder are directly joined, the metal layer may not be provided on the lower surface side of the Ni layer 24.

(7) In the above embodiment, the Ni layer 24 and the resist 22 are formed on the flexible metal plate 21, but SUS stainless steel can be used as long as it is flexible and conductive. It is not limited to a steel plate or a Cu plate. For example, a thin metal plate other than a SUS stainless steel plate or Cu plate may be used, or a conductive resin may be used. Alternatively, a substrate having a conductive film formed on the surface may be used.

(8) The die bonding material 5 may protrude beyond the opening 6 as long as the opening 6 is not blocked so as to hinder the effect of preventing defects such as package cracking, peeling, and blistering during solder reflow.

(9) Although the Ag paste is used as the die bonding material 5, an insulating paste may be used in addition to the Ag paste.

(10) Although the Ag paste is used as the die bonding material 5, an adhesive film such as DAF (die attach film) may be used instead of the Ag paste. A semiconductor device 1D when an adhesive film 5A is used as the die bonding material 5 is shown in FIG. FIG. 8A is a back view of the semiconductor device 1D, and FIG. 8B is a cross-sectional view taken along line C-C ′ of FIG. In this case, the adhesive film 5A is attached so as to close the opening 6 of the die pad 4b, and the semiconductor element 2 is bonded thereon. Therefore, as shown in FIG. 8B, the bottom surface of the semiconductor element 2 is not exposed from the opening 6, and the adhesive film 5A is exposed. However, since moisture and the like are released through the adhesive film 5A, it is possible to prevent occurrence of defects such as package cracking, peeling, and blistering during solder reflow.

  The present invention is not limited to the embodiment described above as long as it has the characteristic configuration.

It is a figure which shows the structure of the semiconductor device of embodiment of this invention. It is a figure for demonstrating the manufacturing method of the semiconductor device of embodiment of this invention. It is a figure for demonstrating the manufacturing method of the semiconductor device of embodiment of this invention. It is a figure for demonstrating sealing of the resin in the manufacturing method of the semiconductor device of embodiment of this invention. It is a figure for demonstrating the semiconductor device which made the shape of the opening part the cross shape. It is a figure for demonstrating application | coating of the die bonding material of the semiconductor device which made the shape of the opening part the cross shape. It is a figure for demonstrating the semiconductor device provided with the several opening part. It is a figure which shows the structure of a semiconductor device when an adhesive film is used as a die-bonding material.

Explanation of symbols

1A, 1B, 1C, 1D Semiconductor device 2 Semiconductor elements 3a, 4a, 9a, 25 Ag layer 3b External electrodes 3c, 4c, 9c, 23 Au layer 4b Die pad 5 Die bonding material 5A Adhesive film 6 Opening 7 Wire 8 Resin 9b Reinforcing pad 21 Metal plate 22 Resist 24 Ni layer 30A Resin encapsulant 41 Mold

Claims (6)

A semiconductor element;
A die pad having an opening and mounting the semiconductor element so as to close the opening;
An external electrode electrically connected to the semiconductor element by a wire;
The die pad and the external electrode are formed by electroforming,
The semiconductor element, the die pad, the wire, and the external electrode are sealed with a resin so that the die pad and the external electrode are exposed at the bottom surface, and the semiconductor element is exposed at the opening. Semiconductor device. The semiconductor device according to claim 1,
A semiconductor device, wherein the semiconductor element is fixed to the die pad using Ag paste or insulating paste. The semiconductor device according to claim 2,
The semiconductor device according to claim 1, wherein the opening has a substantially cross shape. A semiconductor element;
A die pad having an opening and mounting the semiconductor element;
An adhesive film that is affixed to the die pad so as to close the opening, and that adheres a semiconductor element to the die pad;
An external electrode electrically connected to the semiconductor element by a wire;
The die pad and the external electrode are formed by electroforming,
The semiconductor element, the die pad, the wire, and the external electrode are sealed with resin so that the die pad and the external electrode are exposed at the bottom surface, and the adhesive film is exposed at the opening. Semiconductor device. A metal layer forming step in which a plurality of metal layers each including a die pad having an opening and an external electrode disposed outside the die pad are disposed adjacent to the flexible sheet; and
Mounting a semiconductor element on the die pad so as to close the opening, and electrically connecting the semiconductor element and the external electrode; and
A resin sealing step of resin sealing the metal layer and the semiconductor element;
A peeling step of peeling the flexible sheet to obtain a resin sealing body;
A method of manufacturing a semiconductor device, comprising: a step of cutting the resin sealing body to divide into individual semiconductor devices. A flexible metal plate;
A die pad formed by electroforming on the metal plate, having an opening, and on which a semiconductor element is mounted;
A sheet for manufacturing a semiconductor device, comprising: an external electrode formed by electroforming on the metal plate and electrically connected to the semiconductor element by a wire.

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