JPH08167634A - Semiconductor device - Google Patents

Abstract

PURPOSE: To obtain a semiconductor device having an improved reliability against corrosion after preventing electric discontinuity of a wire at openings with a measuring probe, by extending a part of a lower interconnection layer to just beneath a measuring pad and connecting it to the measuring pad through the openings. CONSTITUTION: A semiconductor device has a multilayer interconnection layer composed of interconnection layers laminated through interlayer insulation films 13. A measuring pad 14a formed on an uppermost Al interconnection layer 14 and lower interlayer insulation film 13 and a lower Al interconnection layer (corresponding parts to the measuring pads) 12a formed below the pad 14a in approximately the same pattern as the of this pad are connected through openings 13a formed through the film 13 just beneath the pad 14a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device having a multilayer wiring layer, and more particularly to a structure for connecting an electrical characteristic measuring pad to an internal circuit wiring.

[0002]

2. Description of the Related Art The structure of a pad portion for measuring electrical characteristics of a semiconductor device having a multilayer wiring layer will be described with reference to FIG.
Reference numeral 1 denotes a semiconductor substrate which has been diffused, and a field oxide film 1a is formed on the surface on which the element is formed. Reference numeral 2 denotes a lower aluminum wiring layer (hereinafter referred to as first aluminum), which is formed by opening the field oxide film 1a by lithography and dry etching (hereinafter, lithography and dry etching will be omitted) to partially expose the semiconductor substrate 1. An exposed ohmic contact portion (not shown) is formed, and an aluminum layer is formed thereon by, for example, sputtering. Reference numeral 3 is an interlayer insulating film (for example, silicon oxide or silicon nitride) formed by CVD on which an opening 3a is formed. Reference numeral 4 denotes an uppermost aluminum wiring layer (hereinafter referred to as second aluminum) on which an aluminum layer is formed by sputtering, for example. Reference numeral 5 is a protective film made of an insulating film (for example, silicon oxide, silicon nitride) formed by CVD on the protective film 5, and a part of the second aluminum 4 is exposed by exposing an electric characteristic measuring pad ( (Hereinafter referred to as measurement pad)
Bonding pads (not shown) are formed to connect to the metal wires when assembled with 4a. The measurement pad 4a and the first aluminum 2 are connected by a measurement pad connection line 4b which is a part of the second aluminum 4 through an opening 3a formed near the measurement pad 4a. Further, the first aluminum 2 is electrically connected to the second aluminum 4 and the bonding pad (not shown) through an opening (not shown) formed at another position if necessary. Further, the measurement pad 4a may be disposed close to the second aluminum 4 at a distance of, for example, 100 μm from the viewpoint of circuit design.

[0003]

In the above-described conventional structure of the measuring pad portion, the protective film 5 is opened to expose the second aluminum 4 to form the measuring pad 4a. Even if it is sealed with mold resin as a device,
Water penetrates through the interface between the metal and the resin (the interface between the internal lead wire and the resin and the interface between the thin metal wire connecting the internal lead wire and the element and the resin) and the bulk of the resin. Since it spreads over the entire surface of the element through the interface between and, the measurement pad 4a may be corroded. Generally, moisture easily enters from the interface between the metal and the resin, and therefore the measurement pad 4a has no connection with the fine metal wire, less moisture than the bonding pad connected to the fine metal wire, and does not corrode. Although it takes a long time, the high-reliability product requires a long-term guarantee, and if corrosion further progresses, the measurement pad connection line 4b connected to the measurement pad 4a also corrodes, and further the measurement pad connection line. Corrosion may proceed up to the first aluminum 2 connected to 4b. by the way,
In the structure of the conventional measurement pad described above, even if the connection wire 4b for the measurement pad corrodes and is electrically disconnected, it does not affect the electrical characteristics because it is unnecessary as a function after sealing, but the measurement pad 4a is closer to the measurement pad 4a. When the corrosion of the first aluminum 2 progresses to the position where it crosses the arranged second aluminum 4, the first aluminum 2 expands at the crossing position, thereby cracking the interlayer insulating film 3 on the upper side and The aluminum 4 may be electrically disconnected or short-circuited with the first aluminum 2. In such a case, the internal circuit will not function and the electrical characteristics of the semiconductor device will be affected. Therefore, there is a technique in which polyimide or the like is applied onto the element and the invading water is absorbed by the polyimide or the like to prevent corrosion of the measurement pad. But according to this method,
There is a problem that the number of manufacturing processes increases and the cost increases.

In the case of the bonding pad having the same structure as that of the above-mentioned measuring pad portion, however, the amount of water infiltrated into the bonding pad is larger than that of the measuring pad. The connection portion is isolated and electrically disconnected from the first aluminum. Therefore, as for the structure of the bonding pad portion, Japanese Patent Application Laid-Open No. 61-232637 proposes a structure having improved reliability against corrosion of a semiconductor device having a multilayer wiring layer. This feature will be described with reference to the sectional view of the bonding pad portion in FIG. 6a is a bonding pad formed by exposing a part of the second aluminum 6. A part of the first aluminum 7 is extended to just below the bonding pad 6a, and the bonding pad 6a and the first aluminum 7 are passed through the opening 8a of the interlayer insulating film 8 formed immediately below the center of the bonding pad 6a.
And are electrically connected. 9 is a bonding pad 6
It is a thin metal wire, for example, a gold wire, which is bonded to approximately the center of a. In the structure of the bonding pad configured as described above, even if the moisture invading after the resin sealing acts on the exposed second aluminum 6 and the aluminum around the connecting portion of the thin metal wire 9 corrodes, Since the second aluminum 6 is electrically connected to the first aluminum 7 in the opening 8a immediately below the connecting portion, the connection with the internal circuit is not damaged.

When the above technique is applied to the structure of the measurement pad portion, the reliability against corrosion can be further improved. However, when measuring the electrical characteristics of the element on the semiconductor wafer, the measurement probe is brought into contact with the measurement pad, and the measurement may be repeated. The aluminum in the opening for electrically connecting the first aluminum may be broken by the measuring probe to lose the electrical connection, and the measurement may not be possible during the measurement or during the repeated measurement. The present invention has been made in view of the above circumstances,
The aluminum in the opening that electrically connects the measurement pad and the first aluminum is electrically connected through the opening formed in the interlayer insulating film directly below the measurement pad. It is an object to provide an improved semiconductor device.

[0006]

Therefore, the semiconductor device of the present invention is a semiconductor device having a multi-layered wiring layer in which wiring layers are laminated with an interlayer insulating film interposed therebetween. The characteristic characteristic measuring pad and the lower wiring layer under the pad are electrically connected to each other through a plurality of openings formed in the interlayer insulating film. Also,
In the above semiconductor device, it is desirable that the lower wiring layer under the measurement pad has substantially the same pattern as the measurement pad. Also,
In the above semiconductor device, the uppermost wiring layer and the lower wiring layer are aluminum wiring layers.

[0007]

According to the present invention, by forming a plurality of openings in the interlayer insulating film just below the measurement pad, when the measurement probe is brought into contact with the measurement pad to measure the electrical characteristics, the inside of a part of the opening Even if the aluminum is damaged by the measuring probe, all of the aluminum is not damaged, and the measurement pad and the lower aluminum wiring layer immediately below the measurement pad are not electrically disconnected. Further, according to the present invention, even if water penetrates into the measurement pad, the hole diameter per piece can be reduced by making a plurality of openings directly below the measurement pad, so that the speed of aluminum corrosion in the opening can be suppressed, and, Since the lower aluminum wiring layer directly under the measurement pad extends in the same pattern as the measurement pad, the corrosion speed of the lower aluminum wiring layer directly under the measurement pad can also be suppressed, so aluminum corrosion reaches the internal circuit and the internal circuit is disconnected. However, it takes 1.5 times or more longer than before to lose the function as a semiconductor device.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to FIG. Reference numeral 11 denotes a semiconductor substrate on which diffusion has been completed, and a field oxide film 11a is formed on the surface on which the element is formed.
Reference numeral 12 denotes the semiconductor substrate 1 by opening the field oxide film 11a.
1 is exposed to form an ohmic contact portion (not shown), and an aluminum layer is formed thereon by sputtering, for example, is first aluminum. Reference numeral 12a is a portion corresponding to the measurement pad, which is formed by extending a part thereof to directly below a measurement pad described later. The measurement pad corresponding portion 12a has substantially the same pattern as the measurement pad. Reference numeral 13 denotes an interlayer insulating film (for example, silicon oxide or silicon nitride) formed on it by CVD.
Then, a plurality of openings 13a are formed in a part thereof directly below a measurement pad described later. A second aluminum 14 is an uppermost wiring layer having an aluminum layer formed thereon by, for example, sputtering. Reference numeral 15 is a protective film made of an insulating film (eg, silicon oxide or silicon nitride) formed by CVD on the protective film.
By exposing a part of the second aluminum by opening a part thereof, a bonding pad (not shown) is formed which is connected to the measurement pad 14a and a fine metal wire during assembly.
In addition, the measurement pad 14a is, for example, 45
They are closely arranged at a distance of μm.

According to this embodiment, the measurement probe is brought into contact with the measurement pad 14a by electrically connecting the measurement pad 14a and the measurement pad corresponding portion 12a through the plurality of openings 13a immediately below the measurement pad 14a. When the electrical characteristics are measured by using the measuring probe, even if aluminum in a part of the opening 13a is broken by the measuring probe, the aluminum is not completely broken, and the measuring pad 14a and the measuring pad corresponding portion 12a are electrically connected. There is no disconnection. Further, according to the present embodiment, even if moisture penetrates into the measurement pad 14a, the hole diameter per piece can be reduced by providing a plurality of openings 13a immediately below the measurement pad 14a, so that aluminum corrosion in the openings 13a can be prevented. The speed is suppressed, and since the measurement pad corresponding portion 12a is extended in substantially the same pattern as the measurement pad 14a, the corrosion speed of the measurement pad corresponding portion 12a is also suppressed, and the second aluminum placed close to the measurement pad 14a. Corrosion of the first aluminum 12 progresses to a position intersecting with 14, and an internal circuit is electrically disconnected or short-circuited, and it takes a longer time than before to lose its function as a semiconductor device. According to the result of the reliability test conducted by the present inventor, the vapor pressure test (test condition: Ta = 125 ° C., 2.
In the conventional semiconductor device shown in FIG. 2, at 3 atmospheric pressure and RH 100%), the second aluminum 4 placed close to the measurement pad 4a at a distance of 100 μm may fail in the test time of 192 hours. However, in the semiconductor device of the present invention shown in FIG.
Second aluminum 14 placed close to 4a at a distance of 45 μm
There was nothing that would break down.

[0010]

According to the present invention, by electrically connecting the measurement pad and the portion corresponding to the measurement pad through a plurality of openings directly below the measurement pad, the measurement probe is brought into contact with the measurement pad and the electrical characteristics are improved. When measuring a, even if aluminum in a part of the opening is broken by the measuring probe, not all is broken, and electrical disconnection between the measuring pad and a portion corresponding to the measuring pad is prevented. Further, according to the present invention, even if moisture penetrates into the measurement pad, the hole diameter per piece can be reduced by making a plurality of openings directly under the measurement pad, so that the speed of aluminum corrosion in the opening can be suppressed, and the measurement pad Since the corresponding part is extended in the same pattern as the measurement pad, the corrosion speed of the part corresponding to the measurement pad is also suppressed, aluminum corrosion reaches the internal circuit, and the internal circuit is electrically disconnected or short-circuited and functions as a semiconductor device Since it takes 1.5 times or more longer than before to eliminate the problem, a more reliable semiconductor device can be obtained. Further, since a highly reliable semiconductor device can be obtained as described above, it is not necessary to prevent the corrosion of the measurement pad by coating the element with polyimide or the like to absorb the invading water into the polyimide or the like, and the manufacturing process There is an effect that the cost is not increased without increasing.

[Brief description of drawings]

FIG. 1A is a cross-sectional view of an essential part of a semiconductor device of the present invention. FIG. 1B is a schematic plan view of an essential part of FIG.

2A is a cross-sectional view of a main part of a conventional semiconductor device, and FIG. 2B is a schematic plan view of a main part of FIG. 2A.

FIG. 3 is a sectional view of a conventional bonding pad portion.

[Explanation of symbols]

 12 Lower Aluminum Wiring Layer (First Aluminum) 12a Measurement Pad Corresponding Portion 13 Interlayer Insulating Film 13a Opening 14 Uppermost Aluminum Wiring Layer (Second Aluminum) 14a Electrical Characteristics Measuring Pad (Measuring Pad)

Claims (3)

[Claims] 1. A semiconductor device having a multi-layer wiring layer in which wiring layers are laminated with an interlayer insulating film interposed therebetween, and an electrical characteristic measurement pad formed on the uppermost layer of the wiring layer, and a lower wiring layer under the pad. Are electrically connected via a plurality of openings formed in the interlayer insulating film. 2. The semiconductor device according to claim 1, wherein the lower wiring layer under the pad has a pattern substantially the same as that of the pad to delay the progress of corrosion to prevent disconnection. 3. The semiconductor device according to claim 1, wherein the uppermost wiring layer and the lower wiring layer are aluminum wiring layers.