JPH01209736A - Method of replacing semiconductor element - Google Patents

Abstract

PURPOSE:To perform replacement of semiconductor elements at a high yield rate and to increase the manufacturing yield rate, by removing a semiconductor element from a substrate, forming a thin film having good solder wettability on a silicon plate, pushing said thin film to a semiconductor-element mounting position, heating the silicon plate or the substrate in this state, and absorbing the remaining solder on the substrate into the thin film on the silicon plate. CONSTITUTION:A substrate 1 on which a defective semiconductor element 3 is mounted is placed on a hot plate 4 and heated. The semiconductor element 3 is removed from the substrate 1. A gold thin film (described as Au film hereinafter) 7 is formed on a silicon plate 6. The Au thin film 4 is pushed to the mounting position of the semiconductor element 3, where solder remnant 5 remains, with a pushing jig 8. Then, heating is performed under the state wherein the silicon plate 6 is pushed. The solder remnant 5 on the substrate 1 is absorbed into the Au film 7 on the silicon plate very excellently because the Au thin film 7 has excellent solder wettability and the flatness of the silicon plate 6 is good. Then, another semiconductor element 9 for replacement is mounted on the substrate 1 and connected to the remaining solder 5' through a solder bump 2.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for replacing a semiconductor device, and more particularly to a method for replacing a flip-chip type semiconductor device having solder bumps.

[Conventional technology]

Recently, as semiconductor devices have become lighter, thinner, shorter, and smaller, there has been a demand for higher density mounting methods for semiconductor elements, and flip-chip bonding technology is becoming more widespread as one of these methods.

FIGS. 3(a) and 3(b) are cross-sectional views of an element-mounted substrate shown in the order of steps for explaining such a simple flip-chip connection technique.

As shown in FIGS. 3(a) and 3(b), FIG. 3(a) shows the state before mounting, and FIG. 3(b) shows the state after mounting. The semiconductor element 11 and the substrate 1 are connected by melting the solder bumps 2.

After the connection is completed in this way, semiconductor devices are generally judged to be good or bad by a sorting inspection or burn-in test, and non-defective devices are sent to the next process such as resin coating. Most devices are discarded because it is difficult to replace defective semiconductor elements.

[Problem to be solved by the invention]

The reasons for discarding the above-mentioned conventional semiconductor devices with defective products and the problems to be solved will be explained with reference to FIG.

FIGS. 4A to 4C are cross-sectional views of a semiconductor device shown in the order of steps to explain a conventional example.

First, as shown in FIG. 4(a), the substrate 1 and the semiconductor element 3 to be replaced are connected through the solder bumps 2, so if the substrate 1 or the semiconductor element 3 is heated, the solder bumps 2 are removed. Can be melted. Next, by mechanically pulling up the semiconductor element 3 while it is melted, the substrate 1 and the semiconductor element 3 can be separated.

Next, as shown in FIG. 4(b), such a semiconductor element 3
In the separation, the solder bump 2 is attached to the semiconductor element 3 by the solder bump 1.
In addition to remaining as solder 2', irregularly remaining solder 5 also exists on the board 1.
remains. Note that the remaining solder 5 on this substrate 1 has a diameter of 10
Since the solder particles are as fine as 0 to 200 μm, they can hardly be removed using a net-like solder absorber or a suction-type solder absorber used for repairing printed circuit boards.

Next, as shown in FIG. 4(C), a new solder bump 2 is
When mounting a new replacement semiconductor element 9 face down on the substrate 1, the solder bumps 2 on the semiconductor element 9 may The remaining solder 5 on the substrate 1 does not come into contact with each other at all points, and poor connection points often occur where melting and connection cannot be achieved even if the substrate 1 or the semiconductor element 9 is heated.

Therefore, the new semiconductor element 9 that has been replaced is not a good product due to poor connection, and has to be discarded again.As a result, the replacement yield and, by extension, the manufacturing yield are significantly reduced.
This has the disadvantage of increasing manufacturing costs and decreasing reliability as a semiconductor device.

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for replacing a semiconductor element, in which a semiconductor element to be replaced, such as a defective semiconductor element, can be easily replaced and reliability is improved.

[Means to solve the problem]

The method for replacing a semiconductor element of the present invention includes the steps of heating a substrate or a semiconductor element to separate the semiconductor element from the substrate, and placing the thin film of a silicon plate on which a thin film with good solder wettability is formed to face the substrate. A step of pressing the semiconductor element onto the semiconductor element mounting position on the substrate, a step of heating the silicon plate or the substrate to absorb the solder remaining on the substrate into the thin film on the silicon plate, and then exchanging the solder. The method includes a step of mounting and connecting a semiconductor element having new solder bumps onto the substrate.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(e) are cross-sectional views of a semiconductor device shown in order of steps for explaining a first embodiment of the present invention.

First, as shown in FIG. 1(a), in order to remove the defective semiconductor element adhered on the substrate 1, that is, the semiconductor element 3 to be replaced, from the substrate 1, the defective semiconductor element on the hot plate 4 must be removed. A substrate 1 on which a semiconductor element 3 is mounted is placed and heated. Next, in the case of eutectic solder, 200℃ to 230℃
Since the solder bumps 2 are melted, the semiconductor element 3 is removed from the substrate 1 using, for example, a bottle set.

Next, as shown in FIG. 1(b), when the semiconductor element 3 is removed from the substrate 1, residual solder 5 remains in an irregular manner.

Next, as shown in FIG. 1(c), the silicon plate 6 on which the gold thin film (hereinafter referred to as Au film) 7 has been formed is pressed against the remaining solder on the substrate 1 using a pressing jig 8 under a load of several grams to several tens of grams. 5 is pressed against the mounting position of the remaining semiconductor element 3. Here, the silicon plate 6 is cut out from a silicon wafer, which is the base material of the semiconductor element 3, or is a silicon wafer itself, and has good flatness so that it makes good contact with the surface of the substrate 1. The Au film 7 has a thickness of 100 to 10,000 angstroms, and is previously formed on the silicon plate 6 by a normal vapor deposition or sputtering method. Subsequently, the silicon plate 6 is heated while being pressed against it. As explained in FIG. 1(a), the heating method is as follows:
This may be carried out on a hot plate set at 30° C., or the pressing jig 8 may be equipped with a heater mechanism and the silicon plate 6 may be heated by the pressing jig 8, or both may be used in combination. . Since the Au thin film 7 has good solder wettability and the silicon plate 6 has good flatness, the remaining solder 5 on the substrate 1 is very well bonded to the Au on the silicon plate.
It is absorbed into the membrane 7. Incidentally, in order to promote solder activation, flux may be interposed between the substrate 1 and the silicon plate 6 in FIG. 1(c).

Next, as shown in FIG. 1(d), when the pressing jig 8 is removed, most of the remaining solder 5 on the board 1 is removed by the solder 5''.
Although a small amount is left on the substrate 1 as solder 5', the surface of the substrate 1 is almost smoothed.

Next, as shown in FIG. 1(e), a new replacement semiconductor element 9 is mounted on the substrate 1 and connected to the remaining solder 5' via the solder bumps 2. A normal adhesive flow method (eg, infrared reflow method, hot plate method, etc.) is used to melt and connect the solder bumps 2.

By completing the above-described procedure, the replacement of the flip-chip semiconductor elements 3 and 9 having the solder bumps 2 is completed.

FIG. 2 is a sectional view of a semiconductor device for explaining a second embodiment of the present invention.

As shown in FIG. 2, the difference between this second embodiment and the first embodiment described above is that when the defective semiconductor element 3 is removed from the substrate 1, only this semiconductor element 3 is locally removed. It means heating. For example, a hot air generator 10 is installed above the defective semiconductor element 3, and hot air is blown onto the upper surface of the semiconductor element 3 to heat it to 200 to 230°C. The replacement method of this embodiment is particularly effective when a plurality of flip-chip semiconductor elements are mounted on the substrate 1. That is, only the defective semiconductor element 3 can be replaced without imparting thermal history to good semiconductor elements that do not need to be replaced.

In the above-mentioned embodiments, a gold thin film is used as an example of a thin film having good solder wettability, but other materials such as tin, nickel, and possibly solder may also be used.

〔Effect of the invention〕

As explained above, the semiconductor element replacement method of the present invention makes the height of the residual solder remaining on the substrate almost uniform after the semiconductor element to be replaced is removed, and uses a thin film with good solder wettability. Since the flip-chip type semiconductor element can be easily replaced with a high yield, there is an effect that the manufacturing yield of the semiconductor device can be increased, the manufacturing cost can be lowered, and the reliability can also be improved.

[Brief explanation of the drawing]

1(a) to (e) are cross-sectional views of a semiconductor device shown in the order of steps for explaining a first embodiment of the present invention, and FIG. 2 is a sectional view for explaining a second embodiment of the present invention. FIG. 3(a) is a cross-sectional view of the semiconductor device of FIG. (b) is a cross-sectional view of an element mounting board shown in the order of steps to explain the flip-chip connection technology;
Figures (a) to (c) are cross-sectional views of a semiconductor device shown in order of steps to explain a conventional example. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Solder bump, 3... Semiconductor element to be replaced, 4... Hot plate, 5... Residual solder, 6... Silicon plate, 7... Gold thin film , 8... Pressing jig, 9... Replacement semiconductor element, 10... Hot air generator.

Claims (1)

[Claims] In a method for replacing a semiconductor element melt-connected on a substrate using solder bumps, the step of heating the substrate or the semiconductor element to detach the semiconductor element from the substrate;
a step of pressing the thin film of a silicon plate on which a thin film with good solderability is formed, facing the substrate and against the semiconductor element mounting position on the substrate; and heating the silicon plate or the substrate to place the thin film on the substrate. A semiconductor device comprising the steps of absorbing remaining solder into the thin film on the silicon plate, and then mounting and connecting a semiconductor device having new solder bumps to be replaced on the substrate. How to replace.