JPH0763823A - Method and apparatus for inspecting integrated circuit - Google Patents

Abstract

PURPOSE:To make it possible to monitor the current state in a circuit without breaking by operating an integrated circuit in a magnetically stable inspecting region, and detecting the fluctuation of a magnetic field caused by the current in the circuit with a magnetic sensor using SQUID. CONSTITUTION:In this apparatus, a plurality of magnetic sensors 3 are arranged in a magnetic shielding container 1 formed of permalloy or the like, and an information processing device 2 for processing the output signals of the sensors 3 are provided. The sensor has SQUID and a magnetic flux transformer in a heat insulating container. When a semiconductor circuit is put into this apparatus and operated, a current flows through a signal transmitting path in the circuit. A magnetic field is generated around each signal transmitting path by the change of the current. The magnetic field is detected with the highly sensitive sensor 3, and the current in each signal transmission path can be monitored in real time. Especially in the digital integrated circuit, the current is always changed in response to the clock frequency Therefore, the monitoring becomes easy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an integrated circuit inspection method. More specifically, the present invention is a completely novel inspection method capable of monitoring the operating state of an integrated circuit completed as a chip or an integrated circuit as a product after packaging in real time without destroying the integrated circuit. And the configuration of an apparatus for implementing it.

[0002]

2. Description of the Related Art In recent years, integrated circuits, which have made rapid progress, are loaded with an enormous number of elements and can perform extremely sophisticated functions even with a single chip. Therefore, the technology necessary for verification at the time of development and product inspection before shipment is also sophisticated.

In a usual product, a so-called electrical test using a probe is carried out in a state where an integrated circuit is formed on a wafer, and a defective chip is removed before packaging. Even after packaging, the quality is inspected by using a test pattern or by utilizing a test function that is built in the integrated circuit in advance.

[0004]

However, the test conducted in the wafer state cannot deal with any troubles that may occur in the subsequent steps such as mounting on the lead frame, wiring, and packaging. Further, a method using a test pattern or a test circuit can detect only a failure predicted in advance, and an unexpected failure may actually occur after shipping. On the other hand, an integrated circuit after packaging cannot generally be disassembled and operated, and it is often difficult to determine the cause of a failure with respect to the operating state of the integrated circuit, which changes every moment.

As described above, a method of inspecting the internal operation of the integrated circuit after packaging has not been developed, but if possible, it is extremely useful not only for product inspection but also for development of the integrated circuit. Needless to say. Therefore, the present invention provides a novel inspection method that solves the above-mentioned problems of the prior art and is capable of performing an effective inspection even on an integrated circuit after packaging, and an apparatus for performing the inspection method. Is the purpose.

[0006]

That is, according to the present invention,
The integrated circuit is operated in a magnetically stable inspection area, and the fluctuation of the magnetic field generated by the current flowing in the integrated circuit is reduced by S.
There is provided a method for inspecting an integrated circuit, which is characterized by detecting the state of a current in the integrated circuit in real time by detecting with a sensor using a QUID.

According to the present invention, as an apparatus for carrying out the above-mentioned inspection method according to the present invention, there is provided an apparatus for carrying out the integrated circuit inspection method according to claim 1, which is magnetically An integrated circuit test comprising: a magnetic shielding container for defining a stable inspection area; and a magnetic sensor including a SQUID capable of detecting a change in a magnetic field at a specific position in the magnetic shielding container. A device is provided.

[0008]

The inspection apparatus according to the present invention is characterized in that the operation of the integrated circuit can be monitored in real time by detecting the behavior of the current flowing in the integrated circuit as the fluctuation of the magnetic field. Further, the resolution of the monitoring can be considerably increased, and the operation inside the integrated circuit can be monitored substantially directly.

That is, when the integrated circuit is operating, a current flows through the signal transmission path in the circuit. A magnetic field is generated around each signal transmission line due to this change in current, so this magnetic field is detected by a magnetic sensor using SQUID, which is an extremely sensitive magnetic sensor, and the amount of current in each signal transmission line is measured in real time. Can be monitored at. In particular, in an integrated circuit that handles digital signals, the amount of current constantly changes depending on the clock frequency, so that it becomes easier to monitor the operation via a magnetic field.

However, since there are an extremely large number of signal transmission lines in the integrated circuit, high resolution is required for monitoring the current. Therefore, according to one of the preferable embodiments of the present invention, it is preferable to monitor the current for each location of the integrated circuit by using a plurality of SQUIDs. Such a method allows a general view of the operating conditions within the integrated circuit.

According to yet another aspect of the present invention, it is preferable that the SQUID used in the magnetic sensor is formed of an oxide superconducting thin film. Since this type of superconductor exhibits effective superconducting properties with inexpensive liquid nitrogen, it can be used at a low running cost and is easy to handle.

Hereinafter, the present invention will be described in more detail with reference to examples, but the following disclosure is merely an example of the present invention and does not limit the technical scope of the present invention.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a diagram showing the construction of an apparatus capable of carrying out the inspection method according to the present invention.

As shown in the figure, this inspection apparatus outputs a magnetic shield container 1 defining an inspection area, a plurality of magnetic sensors 3 arranged in the magnetic shield container 1, and a magnetic sensor 3. And an information processing device 2 for processing a signal. The magnetic shielding container 1 can be made of, for example, permalloy or the like.

FIG. 2 is a diagram showing a basic structure of a magnetic sensor usable in the inspection apparatus shown in FIG.

As shown in the figure, the magnetic sensor 3 is
The heat insulating container 34 is mainly composed of a SQUID 32 and a magnetic flux transformer 31 housed in the heat insulating container 34. Here, the SQUID 32 alone functions as a magnetic sensor, but the sensitivity can be improved by adding the magnetic flux transformer 31. Flux transformer 31 and SQUID 32
The heat insulating container 34 containing the is filled with a cooling medium 33 such as liquid nitrogen. In this figure, only one SQUID 32 and magnetic flux transformer 31 are provided in one heat insulating container 34.
Although it is drawn so that a plurality of magnetic sensors can be used as needed, it is actually easier to use a container that stores a plurality of magnetic sensors in one container.

The magnetic flux transformer 31 and the SQUID 32 can be produced, for example, by patterning an oxide superconducting thin film using a technique such as photolithography. Therefore, according to today's lithographic technology, it is possible to configure an extremely small detection unit, and further it is possible to arrange the magnetic sensor units at a high density. Although each coil is represented by a simple loop in the drawing, in reality, the coil has an appropriate number of turns according to the required sensitivity and the like.

[0018]

As described in detail above, the integrated circuit inspection apparatus according to the present invention can monitor the internal operation of the integrated circuit after packaging in detail in real time. Therefore, it is possible to directly detect the loss of function or the occurrence of failure, which greatly contributes to the development of integrated circuits and the inspection of products.

By forming the SQUID and the magnetic flux transformer, which are sensors, with an oxide superconducting material having a high superconducting critical temperature, it is possible to carry out an inspection using liquid nitrogen that is inexpensive and supplied stably. It becomes a device.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of an integrated circuit inspection device according to the present invention.

FIG. 2 is a diagram showing a structure of a magnetic sensor that can be suitably used in the integrated circuit inspection apparatus according to the present invention.

[Explanation of symbols]

1 ... Magnetically shielded container, 2 ... Information processing device, 3 ... Magnetic sensor, 31 ... Flux transformer, 31a ... Pickup coil, 31b ... Input coil

Claims (2)

[Claims] 1. An integrated circuit is operated within a magnetically stable inspection area, and a magnetic sensor using an SQUID is used to detect fluctuations in a magnetic field generated by a current flowing through the integrated circuit. A method for inspecting an integrated circuit, which comprises monitoring the current state of the device in real time. 2. An apparatus for carrying out the method for inspecting an integrated circuit according to claim 1, wherein a magnetic shielding container for defining a magnetically stable inspection area, and an inside of the magnetic shielding container. And a magnetic sensor including an SQUID capable of detecting a change in magnetic field at a specific position of the integrated circuit inspection device.