JPS62119938A - Semiconductor device provided with redundancy circuit - Google Patents

Abstract

PURPOSE:To permit the fuse of a semiconductor device provided with a redundancy circuit to be blown at very low energy and to prevent damage to the element by using Mo, W, Cr or V for the material of the fuse. CONSTITUTION:A laser beam 8 is irradiated on the desired part of a wiring 7 for fuse in an oxidizing atmosphere. The material of the wiring for fuse is a high-melting point metal of Mo, W, Cr or V, but is changed into a low- melting point MoO2, WOx, CrO3 or V2O3 by the laser irradiation and furthermore, the MoO2, WOx is a volatile substance. Accordingly, the lowest impressing energy density value needed for blowing the fuse becomes small and damage to be inflicted on the element in the vicinity of the fuse and the designed pattern can be sufficiently prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] This invention relates to large scale integrated circuits (VLSI), and more particularly to the structure of redundancy circuits in highly integrated memory devices.

[Conventional technology]

FIG. 2 is a sectional view showing a semiconductor device equipped with a conventional redundancy circuit. In the figure, l is silicon (St), for example.
2 is an insulating film such as a silicon oxide film (SIO□ film) formed on the substrate 1; 3 is a fuse wiring for a redundancy circuit; this is a polycrystalline silicon film (polycrystalline silicon film); It is a single layer film consisting of a silicon film) 3a or a high melting point metal silicide film (hereinafter referred to as R metal silicide film) 3b, and it can also be a two-layer film consisting of both of the above as shown in FIG. 2(b). good. Reference numeral 5 denotes an insulating film formed by, for example, a CVD method for insulating between the eyebrows, and is made of a stow film containing phosphorus, boron, etc. 8 is a laser beam for cutting the fuse wiring 3; 6 is an opening in the insulating film 5 formed to cut the fuse wiring 3 by the laser beam 8; and 9 is an opening for cutting the fuse wiring 3 by the laser beam 8. This is the part of the fuse wiring 3.

Next, the operation will be explained. In order to blow out a desired portion of the fuse wiring 3 as shown in FIG. The surface of the fuse wiring 3 is irradiated through the opening 6 and blown by the energy. In this way, desired defective bit lines and defective word lines are cut.

[Problem that the invention seeks to solve]

As mentioned above, fuse wiring used in conventional redundancy circuits has been a single-layer film made of polysilicon or R-metal silicide, or a two-layer film made of polysilicon and R-metal silicide. In order to actually cut fuses and improve the yield of devices with redundant circuits in semiconductor devices equipped with It is necessary to apply it to the fuse wiring part to blow it out. However, there is not only a minimum limit but also a maximum limit to the applied energy density per unit area when cutting a fuse.

This means that if excessive energy is applied to the fuse, it will damage the insulating film 2 under the fuse, the substrate 1, and the surrounding elements and design patterns, resulting in the chip becoming defective, or even if it is a good chip, it is not reliable. This is because it has an adverse effect on sex.

In other words, conventional fuse materials use materials with extremely high melting points such as polysilicon and R metal silicide (Table 1 shows the melting points of typical materials). If so, the minimum applied energy density is high. On the other hand, as the density and integration of devices progresses, the horizontal and vertical structures become finer, resulting in smaller wiring and junctions between fuses and in close proximity to fuses.

The distance between the transistor electrode or the element isolation insulating film is shortened, and the 1! As the thickness of the edge film 2 becomes thinner, it becomes necessary to reduce damage caused by fuse cutting, and therefore the maximum applied energy density is being lowered. For the above reasons, the conventional redundancy circuit has a problem in that the allowable range for the appropriate applied energy density for cutting the fuse is extremely narrow.

This invention was made in order to solve the above-mentioned problems, and has a very wide tolerance range for applied energy density, and even in VLSI, it is a redundant system that does not damage surrounding elements when cutting a fuse. The purpose of the present invention is to obtain a semiconductor device equipped with a functional circuit.

[Means for solving problems]

A semiconductor device equipped with a redundancy circuit according to the present invention uses Mo, W, Cr, or V as a fuse material.

[Effect]

In this invention, the fuse wiring made of Mo, W, Cr, or V forms an oxide with a very low melting point by being heated by electricity or laser beam irradiation and at the same time being placed in an oxidizing atmosphere. Although this substance originally has a very high melting point as a single metal, it becomes an oxide and is melted, removed, and cut under conditions of relatively low applied energy density.

〔Example〕

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

FIG. 1 shows a cross-sectional structure of a semiconductor device equipped with a redundancy circuit according to an embodiment of the present invention, and in the figure, the same reference numerals as in FIG. 2 indicate the same parts. 7 is Mo.

This is fuse wiring made of W, Cr, or V.

As shown in Table 1, these Mo, W, Cr or V are a type of refractory metal and are substances with very high melting points, and their oxides MoO, WO.

(x = 2 + 3) , Cr 02 or VtO
, has a low melting point, and MO02,'NOs is a volatile substance.

Next, the effects will be explained. When a desired part of the fuse wiring 3 is irradiated with laser light 8 in an oxidizing atmosphere, Mo, W, Cr, or V in the part is oxidized and becomes an oxide with a low melting point such as Mo 03 , WOX,
It changes into CrOs and VtOs, and is melted and removed by irradiation with the laser beam. At this time, since the melting point of the oxide is lower than the melting point of conventional fuse materials, the minimum applied energy density value required for cutting the fuse becomes smaller than in the past. Therefore, the allowable range of the appropriate applied energy density for cutting the fuse is very large, and the damage caused to the elements and design patterns around the fuse is very large.
1 - can be sufficiently suppressed.

〔Effect of the invention〕

As described above, according to the present invention, Mo and W can be used as materials for fuse wiring for redundancy circuits.

Since Cr or ■ is used, this fuse material is heated in an oxidizing atmosphere during cutting and turns into an oxide with a low melting point, which makes it possible to cut the fuse with very low energy, which gives less energy to the device. This has the effect of reducing damage and improving the design pattern margin around the fuse.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional side view showing a semiconductor device equipped with a redundancy circuit according to an embodiment of the present invention, and FIG. 2 is a cross-sectional side view showing a semiconductor device equipped with a conventional redundancy circuit. In the figure, 7 is a fuse wiring made of Mo, W, Cr, or ■. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (2)

[Claims] (1) A semiconductor device equipped with a redundancy circuit, characterized in that the wiring material of a fuse for the redundancy circuit of a semiconductor memory element is made of a high melting point metal. (2) A semiconductor device equipped with a redundancy circuit according to claim 1, wherein the high melting point metal is molybdenum (Mo), tungsten (W), chromium (Cr), or vanadium (V). .