JPS5956338A - Method of cutting fuse - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] This invention relates to a method for cutting a fuse.

A conventional fuse element using polycrystalline silicon is shown in FIG. 1 (FIG. 1(a) is a plan view and FIG. 1(b) is a side sectional view). In this figure, 1 is an insulating substrate of 6D, and on top of that is a conductive thickness of several thousand
A fuse element (fuse pattern) 2 made of polycrystalline silicon of X is formed.

In the connoisseur element 2, the width of the pattern is narrow in some parts.

When cutting such a fuse element 2, a current is applied to the fuse element 2, and the polycrystalline silicon is melted by Joule heat at the narrow part of the pattern and cut. Alternatively, a laser beam is applied to the narrow portion of the pattern to melt and evaporate the polycrystalline silicon and cut it.

However, this cutting method has the following drawbacks.

■ Polycrystalline silicon melts/1 What current or laser power is required? In the case of current, a current of 10 mA or more is required, although it varies depending on the pattern width.

(2) Because it is partially heated to over 100 degrees Celsius, the nearby insulating substrate 1 may change color or deteriorate in quality.

■ Melted material scatters.

■ If the film thickness, resistance value, or pattern width of polycrystalline silicon changes due to variations in the manufacturing process, the current, voltage, and energy required for fusing will change, making fusing uncertain.

The present invention has been made in view of the above points, and it is an object of the present invention to provide a method for cutting a fuse that can overcome all of the conventional drawbacks.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 is a diagram for explaining the first embodiment of the invention. In FIG. 2(a), 11 is an insulating substrate;
Thereon, a fuse pattern (fuse element) 12 is formed using molybdenum or tungsten thin M.

When cutting the fuse, a laser beam 13 is applied to the fuse pattern 12 in oxygen or air as shown in Fig. 2.

At this time, the laser output is set to about 11:1 to melt the molybdenum and tungsten (fuse pattern 12). When the laser beam 13 is applied to the fuse pattern 12 in this way, molybdenum or tungsten (fuse pattern 1
2) is heated to 600 to 800°C to oxidize the surface.

Since molybdenum or tungsten oxides are sublimated substances, they disappear quickly. Therefore, the underlying molybdenum or tungsten surface reappears and is oxidized and sublimated again. Thereafter, the surface of molybdenum or tungsten is prevented from appearing, oxidizing, and sublimating. Then, in about 3 milliseconds, the portion of molybdenum or tungsten (fuse pattern 12) covered by the laser beam 13 disappears, and the fuse pattern 12 is cut as shown in FIG. 2(c).

FIG. 3 is a diagram for explaining a second embodiment of the present invention, in which (a) is a plan view and (b) is a side sectional view.

In this FIG. 3, 21 is an insulating substrate, on which is a polycrystalline silicon pattern 22 containing impurities with a width of several μm.
form. This polycrystalline silicon pattern 22 is covered with a thin insulating film 23 such as a silicon oxide film. Further, a molybdenum or tungsten (7) fuse, x'' pattern 24 is formed on the insulating substrate 21 and the insulating film 23 so as to be orthogonal to the polycrystalline silicon pattern 22. A current is applied to the crystalline silicon pattern 22 to cause the polycrystalline silicon pattern 22 to generate heat, thereby heating the fuse pattern 24 (molybdenum or tungsten) present on the polycrystalline silicon pattern 22 via the insulating film 23. In this case, 6
Heat the fuse pattern 24 to 00-800°C.

Therefore, the surface of the portion of the fuse pattern 24 on the polycrystalline silicon pattern 22 is oxidized. Then, the oxide sublimes immediately, and thereafter molybdenum or tungsten appears on the surface, is oxidized, and sublimes repeatedly. Finally, the portion of the fuse pattern 24 above the polycrystalline silicon pattern 22 becomes empty and the fuse pattern 24 is cut.

As is clear from the above first and second embodiments, in the present invention, a shifuse pattern is formed from molybdenum or tungsten, and this fuse pattern is heated and oxidized at a temperature below the melting temperature of molybdenum or tungsten. , thereby cutting the fuse pattern due to the sublimation of molybdenum or tungsten oxides. Yes / No (, according to this invention, the following effects are achieved.

■ Cutting the fuse pattern at a relatively low temperature (600~800℃)
Since the process is carried out at a temperature of 00° C.), there is no effect on nearby insulating substrates, etc.

■ The fuse pattern (molybdenum or tungsten) does not melt, so molten material does not scatter.

■ Even if variations occur in the manufacturing process, the fuse pattern is cut at a relatively low temperature, so the effect is small and the fuse pattern can be cut reliably.

■ Only enough current or laser output is required to heat the fuse pattern to 600-800°C.

The method of the present invention can actually be used as a method for cutting fuse elements used as switching elements in redundant circuits of LSIs or memory writing elements.

[Brief explanation of the drawing]

FIG. 1 is a plan view and side sectional view showing a conventional fuse-cutting type fuse element using polycrystalline silicon, FIG. 2 is a plan view illustrating a first embodiment of the fuse cutting method of the present invention, FIG. 3 is a plan view and a sectional side view of a device for explaining a second embodiment of the present invention. 11.21... Absolute R substrate, 12, 24... Fuse pad py, 13... Laser beam, 22... Polycrystalline silicon pattern, 23... Insulating film. Patent applicant Oki Electric Industry Co., Ltd. Figure 1

Claims (1)

[Claims] A fuse pattern is formed from molybdenum or tungsten, and this fuse pattern is heated to oxidize at a temperature below the melting temperature of molybdenum or tungsten, and the resulting fuse pattern is cut by sublimation of the molybdenum or tungsten oxide. A fuse cutting method characterized by: