JPH0143458B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device having grid lines for dividing a plurality of semiconductor elements formed on the main surface of a semiconductor substrate into individual semiconductor pieces.

When forming a large number of semiconductor elements (integrated circuits) on the main surface of a semiconductor substrate (silicon wafer), the boundaries of the semiconductor elements are also formed in a grid pattern in each photolithography process, and this is called a grid line. There is.

FIG. 1 is a cross-sectional view of the vicinity of a grid line of a conventional semiconductor device using platinum silicide as an ohmic contact. In this figure, 1 is a semiconductor substrate, 2 is a field oxide film, 3 is a CVD film for passivation, and 4 is a platinum silicide layer. In this figure, region A corresponds to the grid line mentioned above.

Region A of this grid line is typically used to facilitate the separation of a large number of semiconductor devices into individual semiconductor pieces, and to generate thermal stress between the mask oxide film and the semiconductor substrate during heat treatment following photolithography. In order to alleviate this problem, the mask oxide film is removed in a grid pattern each time photolithography is performed to expose the surface of the semiconductor substrate.

Therefore, for example, in a semiconductor device in which an ohmic contact is formed with platinum silicide, the region A of the grid line opened in the contact photolithography process (exposing the surface of the semiconductor substrate) is also affected by the formation of the platinum silicide layer. In the process, a platinum silicide layer 4 is simultaneously formed as shown in FIG.

The platinum silicide layer 4 in the grid line area A is likely to peel off during subsequent steps, such as dipping in hydrofluoric acid, and the peeled pieces adhere to other pattern parts. Therefore, in the past, there was a drawback that the peeled off pieces caused short circuits, resulting in a decrease in yield.

Therefore, it may be possible to prevent the platinum silicide layer 4 from being formed in the grid line area A by leaving the thermal oxide film formed in the final heat treatment step in the grid line area A in FIG. ing.

However, in this method, the semiconductor substrate warps due to the thermal stress generated between the mask oxide film and the semiconductor substrate, which causes inconvenience in subsequent steps.

The present invention has been made in view of the above points, and an object of the present invention is to provide a semiconductor device having a novel grid line structure capable of solving the conventional drawbacks.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 shows an embodiment of the present invention, which is a semiconductor device using platinum silicide for ohmic contacts and shot key contacts. In FIG. 2, a is particularly a plan view of the semiconductor device. In this plan view, the protective film (corresponding to the reference numeral 15 in FIG. 2b) covering the entire surface other than the grid line area A is omitted so that the invention can be easily understood. On the other hand, Fig. 2b
is a sectional view taken along line bb in FIG. 2a.

Now, in FIGS. 2a and 2b, 11 is a semiconductor substrate, and 12 is a thick oxide film formed thereon. This oxide film 12 is generally called a field oxide film. Reference numeral 13 denotes a relatively thin oxide film formed on the semiconductor substrate 11 in the area A forming the grid line. Further, 14 is a platinum silicide layer made of a binary alloy of the semiconductor substrate 11 and metal. This platinum silicide layer 14 is located on the semiconductor substrate 11 in the vicinity adjacent to the region A forming the grid line, and is elongated along the grid line.
Moreover, it extends over the entire grid line so as to surround each semiconductor element (which can also be called each divided semiconductor piece) formed on the main surface of the semiconductor substrate 11. 15 is
This is a protective film made of PSG (phosphosilicate glass), etc., formed by the CVD method. This protective film 15
covers the entire surface except area A of the grid line. Therefore, the platinum silicide layer 1
4 is covered with a protective film 15.

The semiconductor device described above is shown in Figures 3 to 5.
It is manufactured by the following manufacturing method described with reference to the drawings. FIG. 3 is a cross-sectional view of the state immediately before contact photolithography after all the diffusion steps have been completed. In this figure, as in FIG. 2, 11 is a semiconductor substrate, 12 is a thick oxide film, and 13 is a relatively thin oxide film formed in the area A forming the grid line. This is an oxide film formed at the same time as the impurity diffusion region (not shown) formed on the semiconductor substrate 11, and this relatively thin oxide film 13 causes the semiconductor substrate 11 to warp slightly.

Next, FIG. 4 shows a state in which the contact photolithography process has been completed. In this photolithography process,
A long and narrow semiconductor substrate 1 is provided along the grid line on both sides adjacent to the grid line.
An opening 21 is formed extending over the entire grid line so as to surround each semiconductor element on the grid line. This opening 21 repairs the warpage of the semiconductor substrate 11.

Next, a metal layer as an electrode material, for example, platinum, is deposited on the entire surface including the openings 21 and heat-treated. Then, the platinum deposited on the semiconductor substrate 11 forms a binary alloy with silicon and remains as a platinum silicide layer 14 as shown in FIG. 5 without being removed by the platinum etchant.

Next, the platinum silicide layer 1 on the semiconductor substrate 11 is
For example, a PSG film (not shown) is formed as a protective film over the entire surface of the oxide films 12 and 13, and the PSG film on the grid lines is removed using a photomask (not shown), thereby obtaining the semiconductor device shown in FIG.

As explained above, in the semiconductor device of the example,
The easily peelable platinum silicide layer 14 is covered with a protective film 15, so that the platinum silicide layer 14 is not exposed to an etching solution such as hydrogen fluoride in subsequent steps. Therefore, there is an advantage that peeling of the platinum silicide layer does not occur and the peeled pieces do not cause short circuits and reduce yield.

Further, in the grid line region A, there is only a relatively thin oxide film 13, and no platinum silicide layer is present in this region A. Therefore, there is an advantage that no platinum silicide layer remains on the scribe cross section, and thin line-like peeling due to scribe residue does not occur.

Furthermore, as is clear from the above-described manufacturing method, there is an advantage that warpage of the semiconductor substrate 11 is eliminated.

In addition, since the entire surface other than the grid line area A is covered with the protective film 15, the thick oxide film 12
The edges of the semiconductor element are now covered with the protective film 15, and the oxide film 12 is further separated from the relatively thin oxide film 13 in the grid line area A by the platinum silicide layer 14, preventing moisture from entering from the edges of each semiconductor element. It has the advantage of preventing moisture and improving moisture resistance.

In the above embodiments, the case where the metal layer is a platinum silicide layer has been explained, but this also applies when the metal layer is another high melting point metal (for example, Ti, W, Mo, Pd) or a silicide layer with it. Can apply the invention. Furthermore, this invention provides multilayer wiring,
Can be applied regardless of layer wiring.

As detailed above, the semiconductor device of the present invention has only a relatively thin oxide film on the main surface of the semiconductor substrate over the entire grid line, and on the semiconductor substrate in the vicinity adjacent to the grid line.
By having a metal layer made of a high melting point metal or its silicide extending long along the grid line, and further having a protective film on this metal layer,
Prevents peeling of metal layers and warping of semiconductor substrates,
Furthermore, thin line-like peeling due to scribe residue can be eliminated.

[Brief explanation of drawings]

Figure 1 is a sectional view showing a conventional semiconductor device, Figure 2 is a cross-sectional view showing a conventional semiconductor device;
Figures a and b are a plan view and a cross-sectional view showing an embodiment of the semiconductor device of the present invention, and Figures 3 to 5 are cross-sectional views shown to explain the method of manufacturing the semiconductor device of Figure 2. 11...Semiconductor substrate, 12...Thick oxide film, 1
3... Relatively thin oxide film, 14... Platinum silicide layer, 15... Protective film.

Claims (1)

[Claims] 1 A refractory metal or a silicide of a refractory metal, which has a dividing grid line at a predetermined location on the substrate in order to divide a plurality of semiconductor elements formed on the main surface of the semiconductor substrate into individual semiconductor pieces. In the semiconductor device, the grid line is entirely composed of only a relatively thin oxide film formed on the main surface of the semiconductor substrate, and the semiconductor device in the vicinity adjacent to the grid line A metal layer made of a high melting point metal or a silicide of a high melting point metal is provided on the substrate and in contact with the surface of the substrate, extending thinly and thinly along the entire grid line so as to surround the semiconductor pieces to be divided, A semiconductor device characterized in that the metal layer has a protective film thereon.