JPS62139352A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent a punch-through phenomenon in a insulating film breakdown incident by a method wherein an insulating film and Al electrode are laid on a semiconductor conductive region with the intermediary of a high- melting metal film, transition metal film, or high-melting silicide film and the insulating film is electrically broken down for the establishment of continuity between the semiconductor conductive region and Al electrode. CONSTITUTION:A tungsten film 10 is selectively attached to an electrode film formed on a semiconductor conductive region 2. After the attachment of an SiO2 film 3 by vapor phase growth to the tungsten film 10, an Al film is attached. The Al film is patterned into an Al electrode 5. Application of a voltage results in a breakdown of the insulating film 3 for the establishment of electrical continuity between the Al electrode 5 and conductive semiconductor region 2. The application of the voltage also results in a damaged tungsten film 10. With Al going into reaction with tungsten only with difficulty, the migration of Al is stopped by the tungsten film 10 before it reaches the semiconductor conductive region 2.

Description

[Detailed Description of the Invention] [Summary] A conductive film such as a high melting point metal film or a high melting point metal silicide film is provided on a conductive semiconductor region, and an insulating film and an aluminum electrode are laminated thereon.

This will prevent damage to the semiconductor region when the insulating film is electrically destroyed.

[Industrial Field of Application] The present invention relates to a semiconductor device, and particularly to a semiconductor cell having an inverted fuse structure.

When a FROM (programmable ROM) or redundant circuit configuration is adopted in a semiconductor integrated circuit (IC), a reverse phase cell (destroying the insulating film to make it conductive: insulation-conduction) or a fuse cell (conduction-insulation) is provided. ing.

It is desired that such cells have a structure that takes into consideration not to adversely affect the IC memory (cell array) during connection or disconnection operations.

[Prior art] P ROM (Programmabie Read
0nly Memory) is a semi-electromechanical storage device in which the user can freely program the memory.For this purpose, it is necessary to connect or disconnect desired bit cells, and therefore reverse fuse cells and fuse cells are provided.

Additionally, as IC memories (cell arrays) become more highly integrated, the number of memory bits increases dramatically, leading to a decrease in yield (yield reduction), which in turn leads to an increase in costs. However, I was devised to avoid this.
According to the redundant circuit configuration of C, the redundant circuit is provided with inverse fuse cells and fuse cells similar to FROM, and measures are taken to discard defective bits and connect good bits.

The present invention relates to a reverse fuse cell among the reverse fuse cells and fuse cells provided in these circuits. Also, the reverse fuse cell is BI C (Breakd
own of In5lator for Cond
It is also called a cell.

This inverted fuse cell usually has a cross-sectional structure as shown in the example in Fig. 4 (al), and is
1, 1 is a p-type semiconductor substrate, 2 is an n" type semiconductor conductive region, and 3 is a 5i02 film (silicon oxide film) or Si3
An insulating film made of an N4 film (silicon nitride film), 4 a phosphosilicate glass (PSG) film (interlayer insulating film), and 4 an aluminum electrode.

After providing such a structure, the insulating film 3 is electrically destroyed during programming, the aluminum electrode 5 and the conductive region 2 are electrically connected, and the bit line (
(not shown) and an aluminum electrode to select a cell or circuit. FIG. 4(b) shows a cross-sectional view after the insulating film 3 is destroyed, and this insulating film 3 will be destroyed if a voltage higher than the dielectric strength voltage is applied, and for example, the film thickness is 80 mm.
An insulating film of ~100 people can be destroyed at a voltage of around 20V.

[Problems to be solved by the invention] However, as shown in Fig. 4, the insulating film 3
When broken, aluminum may spike and penetrate beyond the conductive region 2 into the semiconductor substrate 1, resulting in a short circuit between the semiconductor substrate and the aluminum electrode.

If this happens, the bit cells or circuits connected to the aluminum electrodes will become defective, causing write errors and lowering the reliability of the entire cell array.

Recently, as ICs have been miniaturized and semiconductor conductive regions 2 have been formed by shallow junctions, the above-mentioned troubles are increasing in particular.

The present invention proposes a reverse fuse cell to solve these problems.

[Means for solving the problem] The problem is to create a structure in which an insulating film and an aluminum electrode are laminated on a conductive semiconductor region via a high melting point metal film, a high melting point metal silicide film, etc. The problem is solved by a semiconductor device in which the conductive semiconductor region and the aluminum electrode are electrically broken down to establish electrical continuity between the conductive semiconductor region and the aluminum electrode.

[In other words, the present invention has a structure in which a refractory metal film, a refractory metal silicide film, or the like is provided between a conductive region and an insulating film, and an insulating film and an aluminum electrode are laminated thereon. By doing so, when the insulating film is destroyed by applying a voltage, there will be no punch-through phenomenon in which the aluminum reaches the semiconductor substrate.

[Example code] Hereinafter, embodiments will be described in detail with reference to the drawings.

FIG. 1 shows the cross-sectional structure of a cell according to the present invention,
10 is a tungsten (W) film, and the symbols of other members are the same as those in FIG. An aluminum electrode 5 is provided thereon through a 5i02 film 3 with a film thickness of 80 to 100. Then, when a voltage is applied, damage is added to the tungsten film 10, but since aluminum hardly reacts with tungsten, The movement is blocked by the tungsten film, and the influence of the voltage application does not affect not only the semiconductor substrate 1 but also the semiconductor conductive region 2. Furthermore, the insulating film 3 is destroyed, and the aluminum electrode 5 and the conductive region 2 are not electrically connected. do.

Next, FIGS. 2(a) to 2(C) show cross-sectional views in the order of the formation process. First, as shown in FIG. 2(a), an approximately 2 μm square electrode is formed on the semiconductor conductive region 2. A tungsten film 10 having a film thickness of about 1000 mm is selectively deposited on the window.

The deposition method is a vapor phase growth method using tungsten hexafluoride (W F s), which allows selective growth only in the semiconductor region.

Next, as shown in FIG. 2 (bl), a 5i02 film 3 with a thickness of 80 to 100 layers was deposited on the upper surface by vapor phase epitaxy, and then, as shown in FIG.
An aluminum film having a thickness of approximately m is deposited and patterned to form an aluminum electrode 5.

Moreover, FIG. 3 shows the cross-sectional structure of another cell according to the present invention, and this example is made of tungsten silicide (WSi2).
The structure is such that a film 11 is deposited over the entire surface by a spunter method, a 5i02 film 3 is further deposited thereon, and both are simultaneously patterned by a dry etching method. Similarly to the structure shown in FIG. 1, this example also prevents damage from being caused to the semiconductor conductive region.

Note that the barrier metal interposed between the insulating film 3 and the semiconductor conductive region 2 is not limited to the above example, and other materials such as molybdenum, platinum, or a silicide film thereof may be used.

With the above structure, the phenomenon of punching through the aluminum is prevented, writing errors in the cell array are eliminated, and the IC becomes highly reliable.

Although the above example is explained using a memory, it goes without saying that it can also be applied to other ICs.

[Effects of the Invention] As is clear from the above explanation, according to the present invention, the credibility of ICs such as memories is greatly improved.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional structural diagram of a cell according to the present invention, and FIG. 2 (a
) to (C) are sectional views in the order of their formation steps, FIG. 3 is a sectional structural view of another cell according to the present invention, and FIGS. 4(a) and (b)
is a cross-sectional structural diagram of a conventional cell. In the figure, 1 is a p-type semiconductor substrate, 2 is an n + type semiconductor conductive region, 3 is an insulating film, 4 is a PSG film, 5 is an aluminum electrode, 10 is a tungsten film, 11 is a tungsten silicide film half 1EJfi+; v・tps tLqpfjnJL5J
[11!1 Diagram) i Bl+=tpeltM e*'r, g tank diagram @
2 Figure

Claims (1)

[Claims] A structure is formed in which an insulating film and an aluminum electrode are laminated on a conductive semiconductor region via a high melting point metal film, a transition metal film other than a high melting point film, a high melting point metal silicide film, or a composite film/alloy film thereof. 1. A semiconductor device, characterized in that the insulating film is electrically broken down to establish electrical continuity between the conductive semiconductor region and the aluminum electrode.