JPH0212840A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To dissolve warp and internal stress caused by heat in a die bonding process by a simple process, by a method wherein, after a magnetic film is formed on the rear of a semiconductor wafer and magnetized, the wafer is divided into semiconductor chips by dicing, the chip is mounted on a lead frame made of magnetic material provided with a die pad, and fixed thereon by magnetic force. CONSTITUTION:After a magnetic film 3 is formed on the rear of a semiconductor wafer and magnetized, the wafer is divided into chips 11 by dicing it. The semiconductor chip 11 is mounted on a lead frame 13 made of magnetic material provided with a die pad 14, and fixed by magnetic force. The above semiconductor 11 and lead frame terminals 15 are wire-bonded, and then molded in a body with mold resin 19. For example, when the attractive force is small as compared with the operating force at the time of bonding, the attractive force is reinforced by a magnet 18. Thereby, treatments such as injection of adhesive agent or solder and its heating are made unnecessary, the process is shortened, and the warp and the internal stress caused by heat based on the difference of thermal expansion coefficients between the semiconductor chip and the lead frame, can be eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, particularly a semiconductor integrated circuit device.

[Conventional technology]

FIG. 2 is a perspective view showing a state of a conventional semiconductor integrated circuit device in one step. A semiconductor chip 1 obtained by dicing a semiconductor wafer is fixed onto a die pad 2 of a lead frame 6 with an adhesive 3. This fixation is
In addition to resin bonding using the adhesive 3, solder bonding using soldering, eutectic bonding using eutectic gold and silicon, etc. are available. After the semiconductor chip 1 is fixed to the lead frame 6 in this manner, the semiconductor chip 1 and the lead frame terminals 5 are connected by wires 4 such as gold wires using a wire bonding device. The figure shows this situation. Thereafter, the semiconductor chip 1, leads, and frame 6 are molded with a molding resin (not shown).

[Problem to be solved by the invention]

The conventional manufacturing method described above includes (a) resin bonding, (
b) Solder bonding, (C) Eutectic bonding, etc. are used. (a) is 150° to 200°C for curing the resin, (b) is 25°C.
0" to 350°C, and (c) a high temperature of 320° to 450°C is applied to the semiconductor chip 1. Therefore, due to the difference in thermal expansion coefficient between the semiconductor chip 1 and the die pad 2, the semiconductor chip 1 warps on the same principle as bimetal. There is a problem in that internal stress is generated and cracks may occur in the semicircular chip 1.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for manufacturing a semiconductor device using a simple process that eliminates warpage and internal stress caused by heat in the bonding process.

[Means to solve the problem]

This invention involves forming a magnetic film on the back surface of a semiconductor wafer, magnetizing it, dividing it into semiconductor chips by dicing, mounting the semiconductor chips on a lead frame made of a magnetic material with a die pad, and fixing them by magnetic force. Wire bonding is performed between the semiconductor chip and the lead frame terminal, and then the semiconductor chip and the lead frame are integrally molded with a molding resin.

[Effect]

According to this invention, the semiconductor chip is simply attracted and fixed by magnetic force between the magnetic film on the back surface of the semiconductor chip N and the die pad without using adhesive or heating, and wire bonded, and then molded together with a lead frame. Since the semiconductor chip is molded with resin, heat is not applied to the semiconductor chip due to adhesion or heating unlike in the past, and therefore there is no possibility of warping or cracking of the semiconductor chip due to internal stress.

〔Example〕

FIG. 1 is a process diagram of an embodiment of the present invention, and (a) shows a semiconductor chip positioned on a guide pad (
(b) shows the wire bonding process, and (c) shows the semiconductor device after the molding process has been completed.

Prior to the steps shown in the drawings, a semiconductor wafer that has undergone a known wafer process has a magnetic film formed on its back surface and is magnetized. This magnetic film is formed by sputtering a magnetic material, but a paint containing magnetic powder as a main component may also be applied. Thereafter, the semiconductor wafer is diced into chips.

As shown in step (a) of FIG.
It is brought into contact with a predetermined position of a die pad 14 of a lead frame 13 punched out of a thin plate made of a magnetic material such as 0I. In this way, the semiconductor chip 11 is magnetically attracted and fixed to the die pad 14. Note that 15 is a lead frame terminal integrated with the guide pad 14.

In the wire bonding step (b), the gui pad 14 is placed on the table 16 of the wire bonding machine.
A wire 4 such as a gold wire drawn out from a capillary 17 connects the semiconductor chip 11 which is attracted to the lead frame terminal 15 to the lead frame terminal 15 . When the magnetic attraction is weak against the wire bonding operation force, the magnet 18 is used to reinforce it. Alternatively, holes may be provided in the die pad 14 and the table 16 to reinforce the suction force using vacuum force.

As shown in (b), the wire-bonded lead frame 13 and the semiconductor chip 1 are still attracted by magnetic force.
1 is molded with mold resin 19 using a transfer molding machine or the like with lead frame terminals 15 exposed. Although it is necessary to prevent the relative positions of the semiconductor chip 11 and the lead frame 13 from shifting due to adsorption due to the flow pressure of the resin during molding, this can be achieved extremely easily using common molding techniques. At that time, when the number of wires 4 connecting the semiconductor chip 11 and the lead frame 13 is large, this contributes considerably.

A variation of the above process is demonstrated. Instead of magnetizing the magnetic film 12 on the back surface of the semiconductor chip 11, the lead frame 13, particularly the die pad 14 thereof, may be magnetized, or both may be magnetized. In addition, when using the magnet 18,
Alternatively, the unmagnetized lead frame 13 is placed on the table 16, the unmagnetized semiconductor chip 1-1 is positioned and placed, and both are magnetized and attracted for the first time by the magnetic force of the magnet 18, and wire bonding is performed immediately. . In this case, the wire bonding process is completely absorbed into the wire bonding process and is essentially nothing.

〔Effect of the invention〕

This invention forms a magnetic film on the back surface of a semiconductor wafer, magnetizes it, divides it into semiconductor chips by dicing, mounts this semiconductor chip on a lead frame made of a magnetic material with a die pad, and fixes it by magnetic force. Wire bonding is performed between the semiconductor chip and the lead frame terminal, and then the semiconductor chip and the lead frame are integrally molded with molding resin, so there is no need to inject adhesive or solder as in conventional die bonding. This eliminates the need for heating and heating, which has the effect of simplifying and shortening the process. In addition, since there is no heat treatment and the adsorption is done by magnetic force, there is no warping or internal stress caused by heat due to the difference in thermal expansion coefficients between the semiconductor chip and the lead frame, eliminating defects such as cracks and improving quality and yield. It has the effect of

[Brief explanation of the drawing]

FIG. 1 is a process diagram of an embodiment of the present invention, and FIG. 2 is a perspective view of a conventional technique. 1.11... Semiconductor chip, 2, 4... Gui pad, 3... Adhesive, 6, 13... Lead frame, 1
2...Sieve diagram

Claims (1)

[Claims] 1) Form a magnetic film on the back surface of a semiconductor wafer, magnetize it, divide it into semiconductor chips by dicing, mount this semiconductor chip on a lead frame made of a magnetic material with a die pad, fix it by magnetic force, and divide the semiconductor wafer into semiconductor chips. 1. A method of manufacturing a semiconductor device, comprising wire bonding between the semiconductor chip and the lead frame terminal, and then molding the semiconductor chip and the lead frame together with a molding resin.