JPS623981B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a semiconductor device, and particularly to a passivation structure.

A conventional semiconductor device subjected to passivation is shown in FIG. In FIG. 1, 1 is a silicon substrate, 2 is a field oxide film, 3 is an Al conductive layer, and 4 is a silicon substrate.
5 is a passivation film, and 5 is a grid line. The passivation film 4 is formed on the Al conductive layer 3 except for the Al conductive layer 3 as the bonding pad 6, and on the insulation including the field oxide film 2.

However, in such a semiconductor device, since the adhesion between the passivation film 4/Al conductive layer 3 interface and the passivation film 4/field oxide film 2 interface is poor, water may seep in from the bonding pad 6 and the grid line 5. Arise, Al
Short between 3 conductive layers (between wiring layers), or
There was a drawback that disconnection occurred due to corrosion of the Al conductive layer 3 (wiring metal), resulting in low reliability.

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 passivation structure with excellent moisture resistance.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 2 is a sectional view showing the apparatus of the first embodiment of the present invention in the order of manufacturing steps. Therefore, the device of the embodiment will be described according to the manufacturing method.

In FIG. 2a, reference numeral 11 denotes a single crystal silicon substrate, on the surface of which a diffusion region 12 is formed.
Further, an insulating layer such as a field oxide film 13 is formed on the surface of the silicon substrate 11, and a plurality of selected surface areas of this insulating layer are covered with Al
A plurality of first conductive layers 1 made of (aluminum)
4 is formed.

A plasma SiN film (silicon nitride film) 15 is formed on the entire surface of the silicon substrate 11 as described above. Then, the pad area 16 and the grid line 17
The portion of the SiN film 15 is etched using dry etching. As a result, the SiN film 15 is
A layer is formed on the surface of the first conductive layer 14 except on the first conductive layer 14 and the surface of the insulating layer, and further extends to and covers the side surface of the field oxide film 13 (insulating layer). Ru. (See Figure 2b) After forming the SiN film 15 in this way, as shown in Figure 2c.
As shown in FIG. 2, an Al (aluminum) conductive layer 18 is formed on the entire surface.

Then, in order to separate the Al conductive layer 18 in the pad region 16 and form it into a bonding pad 19, the surrounding Al conductive layer 18 is etched. At the same time, in order to prevent unnecessary Al conductive layer 18 from remaining on grid line 17, unnecessary peripheral Al conductive layer 18 is etched. As a result, the SiN film 1 is placed on the first conductive layer 14 in the pad region 16 in close contact with the surrounding SiN film 15.
A bonding pad 19 made of Al (Al conductive layer 18 ) is formed on the portion protruding above the SiN film 15 so as to cover the SiN film 15 . In addition, the SiN film 1 except for the vicinity of the bonding pad 19 is
A conductive layer 18 is formed on the surface of the SiN film 15, covering the side surfaces of the SiN film 15, being in contact with the surface of the silicon substrate 11 at the grid line 17, and extending slightly laterally over the surface of the silicon substrate 11. Two conductive layers 20 are formed. (See FIG. 2d) Through the above steps, the semiconductor device of this embodiment is completed. A plan view of this completed semiconductor device is shown in FIG.

According to this semiconductor device, the grid line 17
Also, water seepage from the bonding pad 19 portion and water seepage from the pinhole in the center of the device is reduced, moisture resistance is improved, and a highly reliable semiconductor device is obtained.

That is, the conventional structure does not have the bonding pad 19 and the second conductive layer 20 as shown in FIG. Due to poor moisture resistance at the interface, water seeped through the bonding pad and grid lines.

The reason why the moisture resistance is poor at the SiN/Al interface is that the surface of the Al deposited film is oxidized and becomes Al ₂ O ₃ , and this oxidized layer deteriorates the adhesion with SiN. However, when Al is deposited on SiN, an oxidized layer of Al is not formed, which increases adhesion and improves moisture resistance.

In the semiconductor device of the above embodiment, Al on the SiN
The Al conductive layer 18 corresponding to the pad area 1
bonding pad 1 on the first conductive layer 14 of
9 is formed. Therefore, due to the good adhesion of the bonding pad 19, it is possible to prevent water from seeping into the bonding pad 19.

What is the cause of water seepage from the grid line?
The moisture resistance of the PSG (field oxide film)/SiN interface is poor, and the reason for this poor moisture resistance is that the adhesion of PSG to SiN decreases due to the hygroscopicity of PSG. However, in the semiconductor device of the above embodiment, the side surface of the field oxide film 13 (insulating layer)
After being covered with the SiN film 15, the side surfaces of the SiN film 15 are covered with a second conductive layer 20 made of Al, and the second conductive layer 20 is further in contact with the surface of the silicon substrate 11, and further on the surface of the silicon substrate 11. The second conductive layer Al20/SiN film 15,
The adhesion between the second conductive layer Al 20 and the silicon substrate 11 is very good. Therefore, according to the semiconductor device of the embodiment, water seepage from the grid line 17 can also be prevented. Moreover, according to this structure, the side surface of the field oxide film 13 is covered with the SiN film 15 and the second conductive layer 20, and the second conductive layer 20 extends laterally on the surface of the silicon substrate 11. The grid line 1 is extended to provide a large contact area with the silicon substrate 11.
It becomes possible to reliably prevent water from seeping in from 7.

Further, in the semiconductor device of the embodiment, the entire surface of the SiN film 15 except for the vicinity of the bonding pad 19 is covered with a second conductive layer 20 made of Al. Therefore, in the conventional structure, if there was a pinhole in the SiN film (passivation film) in the center of the device, water would seep through the pinhole, causing an inconvenience. can also be solved.

Note that if consideration for this pinhole is not required, the second conductive layer 20 may be formed as follows. That is, the second conductive layer 20 is
It may be formed to cover the side surface of the SiN film 15 from the end surface of the SiN film 15, to be in contact with the surface of the silicon substrate 11, and to extend laterally on the surface. A semiconductor device in which the second conductive layer 20 is formed in this manner is shown in FIG. 4 as a second embodiment of the present invention.

As detailed above, in the semiconductor device of the present invention, nitriding is applied to the surfaces of the first conductive layer and the insulating layer except for the first conductive layer in the pad region, and further to cover the side surfaces of the insulating layer. While forming a silicon film, on the first conductive layer in the pad region,
A bonding pad is formed in close contact with the surrounding silicon nitride film, and furthermore, it covers the side surface of the silicon nitride film from the end surface of the silicon nitride film, and is in contact with the surface of the silicon substrate, and further extends laterally on the surface of the silicon nitride film. Since the second conductive layer is formed so as to extend, it is possible to prevent water from seeping in from the bonding pad portion and the grid line, and a highly reliable semiconductor device can be obtained. In particular, according to the device of the present invention, the side surface of the insulating layer is covered with the silicon nitride film and the second conductive layer, and the second conductive layer is covered with the silicon nitride film and the second conductive layer.
After the conductive layer is in contact with the surface of the silicon substrate, the surface is extended in the lateral direction to increase the contact area with the silicon substrate, so that water seepage from the grid lines can be reliably prevented. Further, when the second conductive layer is extended laterally on the substrate surface to increase the contact area with the silicon substrate, the second conductive layer is applied over a wide area of the silicon substrate, and the second conductive layer is applied to a wide area of the silicon substrate. Since the silicon substrate is in a reinforced state, when the grid lines are cut to form chips, chips and cracks in the silicon substrate are stopped at the reinforced portions and can be prevented from entering the device area. Further, in the device of the present invention, a silicon nitride film is used as an insulating film that covers the insulating layer on the surface of the substrate and the first conductive layer, and this silicon nitride film has high moisture resistance, so that the insulating film can be used at least on bonding pads. Even if exposed around the insulating film, SiO ₂
Unlike when using a membrane, there is no water seepage, and high moisture resistance can be ensured.

[Brief explanation of the drawing]

Figure 1 is a sectional view showing a conventional semiconductor device, Figure 2 is a cross-sectional view showing a conventional semiconductor device;
The figures are cross-sectional views showing the first embodiment of the semiconductor device of the present invention in the order of manufacturing steps, FIG. 3 is a plan view of the semiconductor device of the first embodiment, and FIG. 4 is a second embodiment of the invention. FIG. 11... Single crystal silicon substrate, 12... Diffusion region, 13... Field oxide film, 14... First conductive layer, 15... SiN film, 16... Pad region,
19... Bonding pad, 20... Second conductive layer.

Claims (1)

[Scope of Claims] 1. A single-crystal silicon substrate having a diffusion region on the surface, an insulating layer formed on the surface of the silicon substrate and consisting of at least one layer, and a plurality of selected surface regions of the insulating layer. A plurality of first conductive layers are formed on the surfaces of the first conductive layer and the insulating layer except on the first conductive layer in the pad region, and further extend to cover the side surfaces of the insulating layer. a bonding pad formed on the first conductive layer in the pad region in close contact with the surrounding silicon nitride film; and a bonding pad formed on the first conductive layer in the pad region in close contact with the surrounding silicon nitride film; A semiconductor device comprising: a second conductive layer covering and contacting a surface of a silicon substrate, and further extending laterally over the surface of the silicon substrate. 2. The semiconductor device according to claim 1, wherein the first conductive layer, the bonding pad, and the second conductive layer are made of aluminum.