JPH0311650A - Manufacture of semiconductor device provided with redundant circuit - Google Patents

Abstract

PURPOSE:To obtain a fuse for redundant circuit use which does not cause bulk damage and a fused splash by a method wherein a doped polysilicon interconnection is brought into contact with a high-melting metal silicide interconnection via an opening and this part is heated selectively by using a laser beam. CONSTITUTION:A semiconductor interconnection 13 into which p-type impurities have been introduced is formed, a high-melting metal silicide interconnection 16 which has been connected partially to the semiconductor interconnection 13 is formed. A connection part of the semiconductor interconnection 13 and the high-melting metal silicide interconnection 16 is irradiated with an energy beam 18; p-type impurities B contained in the semiconductor interconnection 13 are diffused to the high-melting silicide interconnection 16; the semiconductor interconnection 13 and the high-melting silicide interconnection 16 are made electrically nearly noncontinuous. Thereby, it is possible to obtain a fuse for redundant circuit use which does not damage a silicon substrate and does not produce a fused splash of polysilicon.

Description

[Detailed Description of the Invention] [Summary] A method of manufacturing a semiconductor device with a redundant circuit, particularly a method of manufacturing a redundant circuit fuse, provides a method of manufacturing a semiconductor device equipped with a fuse for a redundant circuit that is free from bulk damage and blow-out splashes. A process of forming a semiconductor wiring into which a p-type impurity is introduced on a semiconductor substrate, a process of forming a high melting point metal silicide wiring partially connected to the semiconductor wiring, a process of forming a high melting point metal silicide wiring with the semiconductor wiring and a high melting point. Irradiating the connection portion of the metal silicide wiring with an energy beam to diffuse P-type impurities contained in the semiconductor wiring into the high melting point silicide wiring, thereby making the semiconductor wiring and the high melting point silicide wiring almost electrically non-conductive. A method for manufacturing a semiconductor device with a redundant circuit, comprising the steps of: forming a high melting point metal silicide wiring on a semiconductor substrate; a step of forming semiconductor wiring;
A p-type impurity contained in the semiconductor wiring is diffused into the high melting point metal silicide wiring by irradiating the opening with an energy beam through the cover film to the connecting portion of the high melting point metal silicide wiring on the semiconductor wiring, and the semiconductor wiring is removed. The present invention includes a method for manufacturing a semiconductor device with a redundant circuit, characterized in that the method includes a step of making a semiconductor device and a high melting point metal silicide wiring substantially non-conductive electrically.

[Industrial application field]

The present invention relates to a semiconductor device with a redundant circuit, and particularly to a method of manufacturing a redundant circuit fuse.

Laser redundancy is often used as a redundancy method in recent years, but
To cut a fuse, the fuse material itself had to be melted and sublimated in an instant, and a huge amount of energy had to be used to cut the smallest part.

[Conventional technology]

In other words, in the conventional redundant laser cutting method, the huge amount of energy caused the welding droplets to be scattered around the cutting area, and also caused damage to the lower layer.

Referring to FIG. 4, according to the conventional redundant circuit system, as shown in FIG. The polysilicon deposited on top to a thickness of 3000 nm is patterned as shown in the figure to form a polysilicon fuse 23, and a phosphorus glass (PSG) film 24 with a thickness of 1 μm is formed on the entire surface. When cutting the fuse, a laser beam 25 of 1 to 2 μJ is irradiated toward the polysilicon fuse 23. By this laser beam irradiation, the polysilicon fuse is heated to a high temperature of several thousand degrees [°C], and the polysilicon fuse 23 is cut, but the enormous energy applied during the irradiation causes the silicon substrate 21 to A hole 26 is drilled in the hole 26, and a molten droplet 27 of polysilicon is applied to the PSG around the hole 26.
It may be deposited on two membranes and three on top.

Fusing droplets are, of course, dust in themselves, and their presence can reduce the yield of semiconductors. Furthermore, they can re-adhere to the area around the cut area, reconnecting the cut area, and causing leakage current. This greatly affected the reliability of subsequent fuses.

Regarding the damage to the lower layer, since the base is of course bulk silicon, it had a negative effect on the electrical characteristics of the semiconductor elements built there.

[Problem to be solved by the invention]

Therefore, in laser redundant circuit design, in order to avoid the above-mentioned disadvantages, we have avoided creating elements in the 100 to 200 μm wide area around the fuse, but this requires an area dedicated to the fuse within the chip.
Needless to say, a considerable amount of effective bulk area is lost in order to fit thousands of fuses into a chip, and this is a major impediment to future high integration of semiconductors.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for manufacturing a semiconductor device equipped with a redundant circuit fuse that is free from bulk damage and blown splashes.

[Means to solve the problem]

The above problems are a process of forming a semiconductor wiring into which P-type impurities are introduced on a semiconductor substrate, a process of forming a high melting point metal silicide wiring partially connected to the semiconductor wiring, and a process of forming a high melting point metal silicide wiring between the semiconductor wiring and the high melting point metal silicide. A step of irradiating an energy beam to a connecting portion of the wiring to diffuse p-type impurities contained in the semiconductor wiring into the high melting point silicide wiring, thereby rendering the semiconductor wiring and the high melting point silicide wiring almost electrically non-conductive. A method of manufacturing a semiconductor device with a redundant circuit, and a step of forming a high melting point metal silicide wiring on a semiconductor substrate, a semiconductor partially connected to the high melting point metal silicide wiring and into which a P-type impurity is introduced. In the step of forming a wiring, an energy beam is irradiated into the opening through the cover film to the connecting portion between the semiconductor wiring and the high melting point metal silicide wiring to remove p-type impurities contained in the semiconductor wiring at the high melting point. The problem is solved by a method of manufacturing a semiconductor device with a redundant circuit, which includes a step of diffusing the metal silicide wiring into the metal silicide wiring and making the semiconductor wiring and the high melting point metal silicide wiring almost electrically non-conductive.

[Effect]

That is, in the present invention, as shown in FIG. 2 for explaining the principle, a P-type doped polysilicon wiring 13 and a silicide wiring 16 made of a high melting point metal such as tungsten are contacted through an opening 15. The laser beam 18 selectively applies a laser beam 18 to the
By heating to about .degree. C. to 1000.degree. C., p-type impurities (for example, boron B) in polysilicon rapidly diffuse into the silicide wiring layer as schematically shown by arrows. B+ of the contact part of the polysilicon wiring 13 is an elephant,
Boron is quickly incorporated into the silicide wiring 16, and the boron thus incorporated quickly diffuses to the left when viewed from the diagram in which the silicide wiring 16 is not doped, and as a result,
Polysilicon wiring 13 and silicide wiring 1 in opening 15
Almost no boron is present at and around the interface of 6.
Since the impurity concentration at the contact interface becomes extremely low, the contact resistance at that part becomes infinitely high and no current passes through it, so the effect is exactly the same as the cutting state caused by the conventional laser redundant circuit method, which causes damage to the silicon substrate. This can be achieved without giving any molten polysilicon droplets and without generating melted polysilicon splashes.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

An embodiment of the invention is shown in FIG. First, as shown in FIG. 5A, an insulating film (SjO□ film) 12 is formed on a semiconductor substrate (silicon substrate) 11 by thermal oxidation, for example, in a thickness of 500 nm.
Formed to a film thickness of 0.05 mm, and then chemical vapor deposition (CVD)
Undoped polycrystalline silicon (polysilicon) 13a is grown to a thickness of 2000 nm using the method, and then boron (B) is deposited on the entire surface at an acceleration energy of 30 KeV and 3 Xl.
Ion implantation is performed at a dose of 0I'cm-2.

Next, as shown in FIG. 4B, polysilicon wiring 13 is formed by patterning polysilicon 13a using photolithography. Subsequently, an interlayer insulating film 14 (for example, a PSG film) is deposited to a thickness of 2000 nm using the CVD method, and nitrogen (N2) is applied at 900°C for 130 minutes to activate the impurity (B") in the polysilicon wiring 13. Annealing is performed in an atmosphere. After that, the opening I5 is formed using photolithographic technology so that the width of the polysilicon wiring 13 is 2 μm, for example.
m, the opening has an opening size of 1.5 μm.

Next, as shown in FIG. 1(c), a high melting point metal silicide wiring, for example, tungsten silicide (WSiz)
is grown to a thickness of 2000 nm using the CVD method, and patterned using photolithography to form the silicide wiring 16.

Subsequently, as shown in FIG. 1(d), a cover film 17 (for example, a PSG film) is deposited to a thickness of 10,000 nm using the CVD method.

To disconnect the redundant circuit formed as described above, the pulses of the laser beam 18 are selectively set to 1/2 of the conventional pulse.
The opening 15 is instantaneously irradiated from above the cover film 17 with a power of 0.1 to 0.2 μJ of polysilicon wiring 13.
and the contact part of the silicide wiring 16 from 900 to 100
Heat to around 0°C. Due to this heating, as explained in the [Operation] section, the p-type impurity (boron) at the interface between the polysilicon wiring 13 and the silicide wiring 16 rapidly diffuses to areas other than the contact portion of the silicide wiring 16 with the polysilicon wiring 13. However, the contact resistance of the contact portion becomes infinitely large, and no current flows in the 0 contact portion, so the same effect as blowing the fuse in the conventional method can be obtained. Figure 3 shows the results of SIMS analysis of the impurity concentration distribution of boron B. In the figure, (a) shows the distribution before laser beam irradiation, and (b) shows the distribution after laser beam irradiation.

However, a small leakage current of about 100 picoA was observed when a voltage of IOV was applied, for example.
In this case, the contact resistance is on the order of gigabytes, and this level of leakage current was also observed when the fuse was cut using the conventional method, so there is no problem in terms of design or practical use.

The impurity doped into polysilicon is limited to n-type impurities, most preferably boron, and the impurity concentration is 5XIO
It is best to set it to about 2 x 10 cm3.

If an n-type impurity is doped, contrary to the above example, the n-type impurity does not diffuse into the silicide, the contact resistance decreases, and it is not possible to achieve the fuse cutting function.

In the above example, tungsten silicide was explained, but the silicide wiring 16 can be made of silicide of other high melting point metals, such as TiS2, osiz, pbSiz.
, Co51z, etc. It is most preferable to use tungsten silicide for this silicide wiring 16. This silicide wiring 16 was formed in the upper layer of the polysilicon wiring 13, but on the contrary, the silicide wiring 16 was first formed on the insulating film 12, and then the polysilicon wiring 13 was formed in the upper layer of the silicide wiring 16. You may. Although the heating of the opening 15 has been described using a laser beam as an example, other energy beams may be used as long as they heat the opening to about 900 to 1000°C. Therefore, the scope of application of the present invention is not limited to the above embodiments.

Note that the heating of the opening to about 900 to 1000°C described above is instantaneous heating, and the cover film 17, insulating film 12,
No damage was observed on any of the silicon substrates 11.

〔Effect of the invention〕

1 2 As described above, according to the present invention, since the fuse is not melted and cut as in the conventional example, there is no generation of molten droplets and no damage to the bulk under the fuse (opening). This makes it possible to provide a semiconductor element in the lower layer of the fuse part, and also eliminates the need to leave an extra area around the fuse as in the past, allowing for miniaturization of semiconductor devices and higher stacking. It greatly contributes to the development of

13 is polysilicon wiring, 13a is polysilicon, 14 is an interlayer insulating film; 15 is an opening; 16 is silicide wiring, 17 is a cover film; 18 is a laser beam shows.

[Brief explanation of drawings]

1(a) to (d) are cross-sectional views of embodiments of the present invention, FIG. 2 is a cross-sectional view for explaining the present invention in detail, FIG. 3 is a diagram showing the impurity concentration distribution of Bo, and FIG. (a) and (b) are cross-sectional views showing the prior art.

Claims (1)

[Claims] [1] A step of forming a semiconductor wiring (13) into which a p-type impurity is introduced on a semiconductor substrate (11), a high melting point metal partially connected to the semiconductor wiring (13). The step of forming a silicide interconnect (16) is to irradiate the energy beam (18) to the connecting portion between the semiconductor interconnect (13) and the high melting point metal silicide interconnect (16) to form the semiconductor interconnect (16).
13) is diffused into the high melting point silicide wiring (16), and the semiconductor wiring (13) and the high melting point silicide wiring (16) are diffused.
1. A method for manufacturing a semiconductor device with a redundant circuit, comprising the step of rendering substantially electrically non-conductive. [2] Step of forming a high melting point metal silicide wiring (16) on the semiconductor substrate (11), a semiconductor wiring (13) partially connected to the high melting point metal silicide wiring (16) and into which a p-type impurity is introduced. forming the semiconductor wiring (13) and the high melting point metal silicide wiring (1
An energy beam (18) is irradiated to the opening (15) through the cover film (17) to remove p-type impurities contained in the semiconductor wiring (13) from the high melting point metal silicide wiring (16). ) and the semiconductor wiring (13)
1. A method of manufacturing a semiconductor device with a redundant circuit, comprising the step of rendering substantially electrically non-conductive between and a high melting point metal silicide wiring (16).