Short detection circuit and short detection method

A circuit and method for judging a latent short-circuit defect, also known as a short-circuit defect with time passing, in the case of a high voltage system. A detection-dedicated wiring for detecting a short-circuit defect is provided between a first high voltage system wiring and a second high voltage wiring. A power supply and an ammeter is connected in series and one end of it is connected to the high voltage system wiring and the other end of it is connected to the detection-dedicated wiring. If a current value us higher than a predetermined value when the power supply is turned on, one can judge that the circuit has a high possibility of the latent short-circuit defect.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a technique for detecting a short-circuit between interconnections of a semiconductor device.

2. Description of the Related Art

In the interconnections of the circuit in a semiconductor device and the like, a short-circuit is generated due to the contact of a conductive foreign matter with an interconnection and the other interconnection. This leads to the defect of a circuit. Even if the circuit is not judged as defective before shipping, there is a possibility that the circuit become defective depending on various conditions.

FIG. 1is the plane view of a suspected substance. InFIG. 1, a conductive foreign matter101exists between a high-voltage interconnection A and a high-voltage interconnection B. The electric potential of the interconnection A and that of the interconnection B may be set in different. In this case, the high-voltage interconnection A and the high-voltage interconnection B are short-circuited through the conductive foreign matter

Therefore, the suspected substance can be judged as being defective in a usual test.

On the other hand, referring toFIG. 2, the conductive foreign matter102is placed slightly apart from the high-voltage interconnection A. Therefore, the high-voltage interconnection A and the high-voltage interconnection B are not short-circuited. Therefore, the suspected substance should not be judged as being defective in a usual test. However, a stress and the like after the test may cause the conductive foreign matter102to contact the high-voltage interconnection A, and the high-voltage interconnection A and the high-voltage interconnection B will be possibly short-circuited. Such a phenomenon is hereafter referred to as a “short-defect with time passing” or a “latent short-circuit defect.”

A method of applying overvoltage between interconnections has been used in a low-voltage circuit to detect the short-defect with time passing. On the other hand, in the case of a high-voltage circuit, it is necessary to apply higher voltage than the one used in a usual test for detecting the short-defect with time passing by applying overvoltage as well as the low-voltage circuit, and that possibly causes elements to be broken down or deteriorated.

Japanese Laid Open Patent Application (JP-A 2004-14694) as a conventional technique discloses an interconnection test pattern characterized in including at least two resistors the resistance values of which is known on a silicon substrate; an interconnection that connects the resistors electrically in series; an adjacent interconnection formed by the same material as the mentioned interconnection, which is placed adjacent to the interconnection with a predetermined interval; and two terminals that are electrically connected to the mentioned resistors respectively.

Japanese Laid Open Patent Application (JP-A H06-29364) discloses a semiconductor device characterized in including a group of interconnection layers mutually arranged in parallel and a test means that tests whether the mentioned group of interconnection layers is normal or not, wherein the mentioned test means includes; a first potential applying means to apply a first potential to a n-th interconnection layer (n is a multiple of two including 0) in the group of interconnection layers; and a second potential applying means to apply a second potential having at least a different potential from the first potential to n+1-th interconnection layer in the group of interconnection layers, in which, the first potential is applied to the n-th interconnection layer and the second potential is applied to the n+1 interconnection layer at the same time and this status is maintained during a predetermined time.

Japanese Laid Open Patent Application (JP-A H11-23668) discloses an interconnection defect testing circuit as a testing device, which is configured corresponding to an evaluation object circuit and provided on a same substrate as the evaluation object circuit, consisting of a first interconnection and a second interconnection which are electrically insulated, in which a detection circuit forming area for the same evaluation object circuit is divided into a plural, and an insulation-defective detection can be possible in each divided area.

SUMMARY OF THE INVENTION

In the high-voltage circuit, to detect a foreign matter between the interconnections by applying an electrical stress between the interconnections, it is necessary to supply a larger potential difference than the potential difference when the circuit is normally used. However, this testing method cannot be used in the high-voltage circuit since the element has a small margin of stress-resistance. Therefore, the suspected substance having the possibility of the short-defect with time passing due to the conductive foreign matter between interconnections cannot be judged as a defective. That causes a distribution of defective products.

Therefore, an object of the present invention is to provide the short detection circuit and the short detection method that make it possible to recognize the high-voltage circuit with high possibility of the short-defect with time passing.

Another object of the present invention is to provide the short detection circuit and the short detection method that can detect the circuit having high possibility of the short-defect with time passing in the high-voltage circuit without applying an excessive load to the elements.

According to the present invention, it is possible to provide the short detection circuit and the short detection method that make it possible to recognize the high-voltage circuit with high possibility of the short-defect with time passing.

In addition, according to the present invention, it is possible to provide the short detection circuit and the short detection method that can detect the circuit having high possibility of the short-defect with time passing in the high-voltage circuit without applying an excessive load to the element.

In an aspect of the present invention, a short detection circuit includes a first interconnection, a second interconnection and a first detecting interconnection positioned between the first interconnection and the second interconnection and unconnected to the first interconnection and the second interconnection. The first interconnection has a terminal for connecting to a power supply and an ammeter connected in series. The first interconnection has a terminal for connecting a power supply and an ammeter connected in series, and the second interconnection has a terminal for connecting a power supply and an ammeter connected in series.

In another aspect of the present invention, a method for detecting short-circuit includes a step of providing a first detecting interconnection between a first interconnection and a second interconnection, a first measuring step applying a predetermined value of voltage between the first interconnection and the first detecting interconnection and measuring a current, and a step of judging a possibility of short-circuit by comparing a value of the current measured by the first measuring step with a predetermined value.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, a short detection circuit and a short detection method in the preferred embodiments will be described in detail with reference to the attached drawings.

FIG. 3shows the short detection circuit of the first embodiment. In the short detection circuit, a high-voltage interconnection A and a high-voltage interconnection B are provided on a substrate. InFIG. 3, the interconnection A and the interconnection B are parallel. The potential of the interconnection A and the potential of the interconnection B may be different. A high-voltage interconnection means the interconnection to which the voltage of tens of volts or more is applied in usual operations.

A detection-dedicated interconnection001is provided between the high-voltage interconnections A and B. The interconnection001is not connected with the interconnection A and B. The interconnection001has a terminal unit to which external devices exemplified by an ammeter and a power supply can be connected. InFIG. 3, the interconnection001, interconnections A and B are parallel to each other. The detection-dedicated interconnection001is manufactured in the process that is in parallel to the process of the high-voltage interconnection A and B. The detection-dedicated interconnection001is arranged so as to provide the potential independently from the high-voltage interconnection A and B.

FIG. 4shows an equivalent circuit diagram in the test1-1, which is one of the testing methods using the short detection circuit shown inFIG. 3. Here, a power supply and an ammeter are connected in series between the high-voltage interconnection A and the detection dedicated interconnection001. The power supply applies a controlled predetermined voltage between the positive terminal and the negative terminal. The ammeter detects the electric current generated from the power supply.

FIG. 5shows an equivalent circuit diagram in the test1-2, which is an another testing method using the short detection circuit shown inFIG. 3. Here, a power supply and an ammeter are connected in series between the high-voltage interconnection B and the detection dedicated interconnection001. The ammeter detects the electric current generated by the power supply.

In the tests1-1and1-2, each voltage applied by the power supply is allowable to be lower than the one in the usual operation under the condition that the short-defect with time passing can be detected.

FIG. 6is a flowchart of the test of the short-defect with time passing in the first embodiment. The flowchart shows the test of the short-defect with time passing, in which a conductive foreign matter102exists as shown inFIG. 2is referred as an example.

First, the test1-1is executed on a suspected substance as shown inFIG. 7. If the current value detected by the ammeter is higher than a predetermined value, the suspected substance is judged as a defective. InFIG. 7, the suspected substance is not judged as the defective in the test1-1.

If the current value detected in the test1-1is lower than a predetermined value, the test1-2is executed as shown inFIG. 8. Then, in the case that the current value detected in the test1-2detected at that time is higher than a predetermined value, the suspected substance is judged as being defective. InFIG. 8, the conductive foreign matter102, which exists in the suspected substance, contacts with each of the high-voltage interconnection B and the detection-dedicated interconnection001. Therefore, the suspected substance is judged as being defective because it has a possibility to cause the short-defect with time passing. If the current values detected in both tests1-1and1-2are lower than predetermined values, the circuit is judged as being non-defective having few possibility to cause the short-defect with time passing.

FIG. 9shows a circuit in a second embodiment. A high-voltage interconnection A and a high-voltage interconnection B that is arranged in parallel to the high-voltage interconnection A are shown inFIG. 9. The potential of the interconnection A and the potential of the interconnection B may be different. A detection-dedicated interconnection002is provided between the high-voltage interconnection A and the high-voltage interconnection B. A detection-dedicated line003is provided between the detection-dedicated interconnection002and the high-voltage interconnection B. The interconnection002is not connected to the interconnections A and B. The interconnection003is not connected to the interconnections A, B and002.

The interconnection002has a terminal unit to which external devices exemplified by an ammeter and a power supply can be connected. The interconnection003has the same kind of terminal.

The distance between the high-voltage interconnection A and the detection-dedicated interconnection002is equal to the distance between the detection-dedicated line003and the high-voltage interconnection B. The detection dedicated interconnection002and the detection-dedicated line003are manufactured in the parallel processes to the processes of the high-voltage interconnections A and B. The detection dedicated interconnection002and the detection-dedicated line003are arranged so as to provide the potential independently from the high-voltage interconnections A and B. The potential of the detection dedicated interconnection002and the detection-dedicated line003can be also provided independently.

FIG. 10shows an equivalent circuit diagram in the test2-1, which is one of the testing methods using the short detection circuit shown inFIG. 9. Here, a power supply and an ammeter are connected in series between the high-voltage interconnection A and the detection dedicated line003.

FIG. 11shows an equivalent circuit diagram in the test2-2, which is one of the testing methods using the short detection circuit shown inFIG. 9. Here, a power supply and an ammeter are connected in series between the detection-dedicated interconnection002and the high-voltage interconnection B.

FIG. 12shows an equivalent circuit diagram in the test2-3, which is an another testing method using the short detection circuit shown inFIG. 9. Here, a power supply and an ammeter are connected in series between the detection-dedicated interconnection002and the detection dedicated line003.

In the tests2-1,2-2and2-3, each voltage applied by the power supply is allowable to be lower than the one in the usual operation under the condition that the short-defect with time passing can be detected. The ammeter which can detect that the detected value is higher than a setting value which is set in larger value than a normal leak current at the voltage of this process in these tests.

FIG. 13is the flowchart of the test of the short-defect with time passing in the second embodiment. First, the test2-1is executed on a suspected substance. If the current value detected in this test is higher than a predetermined value, the suspected substance is judged as being defective having the high potential of the short-defect with time passing. If the current value is equal to or lower than the predetermined value, the test2-2is executed. Then, in the case that the current value detected in the test2-2is higher than a predetermined value, the suspected substance is judged as being defective. If the current values detected in both tests2-1and2-2are lower than predetermined values, the circuit is judged as being non-defective having few possibility to cause the short-defect with time passing.

FIG. 14is a second flowchart of the test of the short-defect with time passing in the second embodiment. First, the test2-3is executed on a suspected substance. If the current value detected in this test is equal to or lower than a predetermined value, the suspected substance is judged as being non-defective. If the current value detected in this test is larger than the predetermined value, the test2-1is executed. If the current value detected in the test2-1is larger than a predetermined value, the suspected substance is judged as being defective. If the current value detected in the test2-1is equal to or lower than the predetermined value, the test2-2is executed. Further, if the current value detected in the test2-2is larger than a predetermined value, the suspected substance is judged as being defective. If the current value detected in the test2-2is equal to or lower than the predetermined value, the suspected substance is judged as being non-defective.

When it is known that the incidence rate of the conductive foreign matter is low, the judgment whether the suspected substance is the non-defective or the defective can be achieved by only the step of the test2-3. Therefore, the testing time of the testing flow shown inFIG. 14is shorter generally. Contrary, if the incidence rate of the defect is high in the test2-3(for example, 50% or more), the testing time of the testing flow shown inFIG. 13in which the judgment is carried in two steps is shorter.

The short detection circuit and the short detection method in the second embodiment have following characteristics in comparison with the first embodiment. Referring toFIG. 15, it is assumed that a large conductive foreign matter102and a smaller conductive foreign matter103are touched with the high-voltage interconnection B. The conductive foreign matter103is small and has few possibilities to cause the short-defect with time passing. Therefore, in this case, it is desirable that the suspected substance may be judged as the non-defective when only the conductive foreign matter103exists. However, in the first embodiment, when any one of the electrical conductive foreign matters102and103exists, both of the suspected substances are judged as defectives. This causes that the rate of the non-defective products falls more than necessary, and the manufacturing cost of the products increases.

In the second embodiment, as for the conductive foreign matter103, the detected current value is lower than a predetermined value, and is judged as being non-defective in the test2-1shown inFIG. 16, the test2-2shown inFIG. 17and in the test2-3shown inFIG. 20. On the other hand, as for the conductive foreign matter102, it is judged as being defective in the test2-2shown inFIG. 19or the test2-3shown inFIG. 21. When the conductive foreign matter102contacts with the high-voltage interconnection A and occupies near the high-voltage interconnection B, it is judged as being defective in the test2-1or the test2-3. Therefore, in the second embodiment, only the suspected substance which includes the conductive foreign matter with the large possibility to cause the short-defect with time passing can be judged as being defective.

Referring toFIG. 22, the detection-dedicated interconnection001is provided between the high-voltage interconnection A and the high-voltage interconnection B as well as the first embodiment. The high-voltage interconnection A and the detection-dedicated interconnection001are conducted through the conductive foreign matter105. Further, the detection dedicated interconnection001and high-voltage interconnection B are conducted through the conductive foreign matter104. That is, providing the detection-dedicated interconnection001causes the high-voltage interconnection A and the high-voltage interconnection B to be short-circuited by the comparatively small conductive foreign matters104and105though they should not be short-circuited originally.

In order to decrease such occurrence of the short circuit, it is effective to divide the detection dedicated interconnection001into the detection dedicated interconnection004and the detection dedicated interconnection005as shown inFIG. 23. InFIG. 23, there is a clearance between the detection dedicated interconnection004and the detection dedicated interconnection005from a viewpoint of a normal direction of the interconnection A. The detection dedicated interconnection005is positioned on the extension of the interconnection004. Each of the detection dedicated interconnections004and005has a terminal unit for connecting the external devices.

Referring toFIG. 24, two detection-dedicated interconnections002and003are provided between the high-voltage interconnection A and the high-voltage interconnection B as well as the second embodiment. In this case, the comparatively small conductive foreign matters106,107and108possibly cause the high-voltage interconnections A and B to be short-circuited. In order to decrease such short-circuit, it is effective to divide the detection dedicated interconnection002into detection dedicated interconnections006and008, and the detection dedicated interconnection003into the detection dedicated interconnections007and009as shown inFIG. 25.

According to the short detection circuit and the short detection method of the present invention, though such detection of the short-defect with time passing using the overvoltage is carried out in a low-voltage circuit, it becomes possible to detect the short-defect with time passing of the high-voltage circuit at the applied voltage equal to the usual detection.