Semiconductor device and method for manufacturing the same

Abstract

Disclosed is a semiconductor device that includes a semiconductor chip; bonding pads provided to the semiconductor chip; a plurality of lead terminals arranged around the semiconductor chip; a plurality of bonding wires that electrically connect the semiconductor chip with the plurality of lead terminals; and a resin encapsulant which encapsulates the semiconductor chip and the bonding wires, the semiconductor device further having an insulating material interposed at the interface between the bonding wires and the resin encapsulant, and the insulating material containing a nanometer-sized insulating particle and amorphous silica.

Claims

1. A method for manufacturing a semiconductor device comprising: providing a semiconductor chip; bonding pads having a surface coplanar with the semiconductor chip; a plurality of lead terminals arranged around the semiconductor chip; a plurality of bonding wires that electrically connect to the semiconductor chip via the bonding pads and connect the semiconductor chip with the plurality of lead terminals; and a resin encapsulant, composed of an epoxy resin, which encapsulates the semiconductor chip and the bonding wires; contacting at least the bonding wires with an insulating material; and electrically connecting the semiconductor chip and the plurality of lead terminals through a plurality of bonding wires; encapsulating the semiconductor with the resin encapsulant after contacting at least the bonding wires with the insulating material; wherein the insulating material contains an insulating particle having a particle size of 1 m or smaller, amorphous silica, and an organosilicon compound consisting of one of an alkyl alkoxy silane compound, and an organopolysiloxane; and the organosilicon reacts with the Si particles to form SiO bonds around the insulating particles, and a thickness of the insulating material is 100 nm or less.

2. The method for manufacturing the semiconductor device described in claim 1, wherein the method comprises, after electrically connecting the semiconductor chip and the plurality of lead terminals through a plurality of bonding wires and before encapsulation with the resin encapsulant, contacting at least the bonding wires with the insulating material.

3. The method for manufacturing the semiconductor device of claim 1, wherein the organosilicon compound is an alkyl alkoxy silane.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic cross-sectional view illustrating a widely-known semiconductor device.

(2) FIG. 2 is a drawing illustrating an insulating paste used in this invention.

DESCRIPTION OF THE EMBODIMENTS

(3) The semiconductor device of this invention may cover a whole range of conventional semiconductor devices, provided that an insulating material explained below is interposed between the bonding wires and the resin encapsulant.

(4) Such semiconductor device may be typically embodied as the semiconductor device 101 previously illustrated in FIG. 1, which has a semiconductor chip 2, bonding pads 211 provided to the semiconductor chip 2, a plurality of lead terminals 50 arranged around the semiconductor chip 2, a plurality of bonding wires 6 that electrically connect the semiconductor chip 2 with the lead terminals 50, and a resin encapsulant 11 that encapsulates these components.

(5) To interpose the insulating material at the interface between the bonding wires 6 and the resin encapsulant 11, it suffices to bring the bonding wires 6 into contact with an insulating paste that contains a nanometer-sized insulating particle and an organosilicon compound, after electrically connecting the semiconductor chip 2 and the plurality of lead terminals 50 through the plurality of bonding wires 6, and before encapsulation with the resin encapsulant.

(6) The insulating paste contains the nanometer-sized insulating particle and amorphous silica. The nanometer size in the context of this invention means a size of 1 m or smaller.

(7) Referring now to FIG. 2, an insulating paste 300 used in this invention contains insulating particles 311, and preferably contains Si particles 312, and a liquid organosilicon compound 320. The organosilicon compound 320, when allowed to react with the Si particles 312, forms SiO bonds (amorphous silica (SiO.sub.2)) around the insulating particles 311 which serve as an aggregate.

(8) Each of the insulating particle 311 and Si particle 312 has a particle size on the nanometer scale (1 m or smaller). External forms of the insulating particle 311 and the Si particle 312 are freely selectable without being limited to sphere, although illustrated as spheres in FIG. 1.

(9) The insulating particle 311 is exemplified by metal oxide particles (ceramic particles) composed of barium titanate, silica, alumina and so forth. The insulating particle 311 need not have a uniform particle size, but may have different particle sizes within the nanometer scale described above.

(10) The Si particle 312 is an optional ingredient, but is beneficial for demonstrating the effects of this invention. The Si particle 312 need not have a uniform particle size, but may have different particle sizes within the nanometer scale described above.

(11) The organosilicon compound 320 is represented by an alkyl alkoxy silane given by the formula below:
CH.sub.3O[Si.sub.nO.sub.n1(CH.sub.3).sub.n(OCH.sub.3).sub.n]CH.sub.3.

(12) Besides this, employable is an organopolysiloxane (for example, alkoxy silane having a functional side chain), which is specifically exemplified by compounds having alkoxy group(s) (RO) bound to a Si atom or tetrasiloxane, where R represents an organic group.

(13) To bring the insulating paste 300 into contact with the bonding wires 6, employable is a method by which, before the semiconductor chip 2 and the plurality of lead terminals 50 are electrically connected through the plurality of bonding wires 6, and before encapsulation with the resin encapsulant 11, these components are dipped in a dipping tank that contains an insulating paste, or these components are sprayed with the insulating paste. After the process, the components are preferably air-dried or dried under heating. Thickness of coating of the insulating paste is typically, but not specifically limited to, 100 nm or thinner.

(14) The components thus coated with the insulating paste is then encapsulated with the resin encapsulant 11. Epoxy resin is typically used as the resin encapsulant. Any of known methods for encapsulation is employable, by which the components are typically placed in a mold, the resin is filled into the mold, and the resin is allowed to cure.

(15) The thus obtained semiconductor device of this invention has the insulating material disposed at the interface between the bonding wires 6 and the resin encapsulant 11, thereby enjoys improved adhesiveness between the bonding wires 6 and the resin encapsulant 11, while preventing separation of both components.

(16) Also the bonding strength between the bonding wires 6 and the lead terminals 50, during the second bonding, is advantageously improved.

(17) While the bonding wires 6 are exemplified by known wires made of Au, Al, Cu and so forth, effects of this invention may be particularly be enhanced when Au wires are used. While the resin encapsulant is again not specifically limited, effects of this invention may be enhanced particularly when epoxy resin is used as the resin encapsulant.

(18) Electronic devices incorporating the semiconductor device of this invention cover almost all devices that contain electronic circuits as the functional elements thereof, which are exemplified by sensor module, optoelectronic module, unipolar transistor, MOS FET, CMOS FET, memory cell, or, integrated circuit (IC) incorporating these components, and LSIs of various scales.

(19) Experiments below were conducted to demonstrate the effects of this invention.

Preparation of Insulating Paste

(20) Barium titanate as the insulating particle, Si particle, and organopolysiloxane represented by formula CH.sub.3O[Si.sub.nO.sub.n1(CH.sub.3).sub.n(OCH.sub.3).sub.n]CH.sub.3 were mixed to thereby prepare an insulating paste.

(21) A semiconductor device before being encapsulated with the resin encapsulant was dipped in the insulating paste, and air-dried. The semiconductor device was then placed in a predetermined die, and encapsulated with an epoxy resin.

(22) Now, the semiconductor device of this example has, as illustrated in FIG. 1, the semiconductor chip 2; bonding pads 211 provided to the semiconductor chip 2; the plurality of lead terminals 50 arranged around the semiconductor chip 2; the plurality of bonding wires 6 that electrically connect the semiconductor chip 2 with the lead terminals 50; and the resin encapsulant 11 that encapsulates these components. The bonding wires 6 are Au wires, the semiconductor chip 2 typically measures approximately 4 mm4 mm in planar view, the distance between each electrode pad 211 and each lead terminal 50 is approximately 500 m, and each bonding wire 6 is bonded to the top surface 51 of each lead terminal 50 at a certain angle of inclination.

(23) Adhesiveness between the bonding wires 6 and the resin encapsulant 11 was examined. The bonding wires 6 and the resin encapsulant 11 were found to remain under good adhesion even after the experiment, without showing separation between them. In contrast, separation between the bonding wires 6 and the resin encapsulant 11 was observed for a semiconductor device not having been brought into contact with the insulating paste.

(24) Bonding between the bonding wires 6 and the lead terminal 50 during the second bonding was observed. The state of bonding was found to remain intact in the semiconductor device of this invention having been brought into contact with the insulating paste, whereas a plurality of bonding wires 6 were found to be separated from the lead terminals 50 in the semiconductor device not having been brought into contact with the insulating paste.

(25) According to this invention, it now becomes possible to provide a semiconductor device and a method for manufacturing the same, capable of enhancing adhesiveness between the bonding wires and the resin encapsulant enough to prevent separation of them, and of improving bonding strength between the bonding wires and the lead terminals in the second bonding.