JP2001165987A - Method for detecting disconnection of internal wiring of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a disconnection detection method for a semiconductor device of a multi-chip module or the like with a plurality of semiconductor chips mounted to the same package, whereby a disconnection of a signal line connected in common to the plurality of semiconductor chips can be detected simply. SOLUTION: According to the disconnection detection method for internal wiring, the disconnection of the signal line connected in common to the plurality of semiconductor chips 11 and 12 is detected for the semiconductor device, having the plurality of semiconductor chips 11 and 12 mounted in the same package 1. A constant current is impressed from a power source 6 for testing to an external terminal An, to which the signal line is connected. A terminal voltage VDF at the external terminal is measured and is compared with a terminal voltage of a good product, whereby the presence/absence of the disconnection of the signal line is detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for testing a semiconductor device such as a multi-chip module in which a plurality of semiconductor chips are mounted on the same package, and more particularly, to disconnection of a signal line commonly connected to a plurality of semiconductor chips. And a disconnection detection method capable of easily detecting the disconnection.

2. Description of the Related Art In a multi-chip module (hereinafter abbreviated as MCM), a plurality of semiconductor chips are mounted in the same package, and terminals of each semiconductor chip are connected to external parts provided in the package via wires, wiring patterns, and the like. Connected to terminal.

[0003] Among these wirings, signal lines commonly connected to a plurality of semiconductor chips, such as data lines and address lines of a memory, are included. Wirings commonly connected are wirings connected to one semiconductor chip. Is broken, the normal operation of the MCM is hindered.

Therefore, it is necessary to reliably detect the disconnection of the wiring. In the MCM test, the presence or absence of the disconnection is checked for all the wirings. However, such common connection is performed by the conventional disconnection detecting method. The operation of detecting the disconnection of the signal line was complicated and could not be easily detected.

Therefore, there is a demand for the development of a disconnection detecting method capable of easily detecting a disconnection of a signal line commonly connected to a plurality of semiconductor chips.

[0006]

2. Description of the Related Art FIG. 5 is a diagram showing an example of a circuit configuration of a device under test, FIG. 6 is a diagram showing an example of disconnection of internal wiring, and FIG. 7 is a flowchart showing a conventional test method.

In FIG. 5, a target device to be measured has a plurality of (two in the figure) semiconductor chips 11 and 12 mounted in the same package 1, and each terminal of the semiconductor chips 11 and 12 has a wire, a wiring pattern or the like. It is connected to an external terminal provided on the package 1 via the intermediary terminal.

Namely, the semiconductor chip 11 and the semiconductor chip 12 via an external terminal A ₁ to A _X, the B ₁ .about.B _X is internal wiring
Is connected to the terminal, if the sometimes having external terminals A _Z, the external terminal connected to a terminal of one of the semiconductor chips as B _Z.

In such a device under test, the semiconductor chip and the internal wiring are often connected by a bonded wire. For example, an external force is applied to the wire when the device is sealed in a molded resin package. Disconnection may occur.

As a result, as shown in FIG. 6, when a disconnection 13 occurs between the terminal of the semiconductor chip 11 connected to the external terminal A ₁ and the internal wiring, the wiring connecting the external terminal A ₁ and the semiconductor chip 12 is disconnected. Even if there is no disconnection, the normal operation of the device under test may be hindered.

Therefore, conventionally, individual semiconductor chips are operated independently to activate all internal wirings, and at the same time, by detecting output signals when test signals are applied to external terminals, connection portions such as wires are connected. Disconnection of all the internal wirings including.

That is, as shown in FIG. 7, a device to be measured is set in a socket or the like of a measuring device and a chip select line of the device to be measured is selected, so that the first semiconductor chip, for example, the semiconductor chip 11 operates. All relevant internal wiring is activated.

[0013] DUT corresponds to H level or L level of the associated the test signal to an external terminal A ₁ to A _X is applied, the applied test signal when one of the semiconductor chip is in operation Thus, the output signal of the semiconductor chip, for example, the level of the B signal changes.

When a control signal, for example, a C signal is applied to the operating semiconductor chip instead of the test signal applied to the external terminals A ₁ -A _X , the H level of the applied C signal or External terminals A _{1 to} A corresponding to the L level
The voltage level of _X changes.

However, if the internal wiring connected to the external terminals A _{1 to} A _X is broken, the external terminal A ₁
Even test signal is applied to to A _X without B signals changes, the external terminals A ₁ to A _X be C signal is applied to the semiconductor chip
Voltage level does not change.

[0016] Thus, to see if B signal by applying a test signal to an external terminal A _n as shown is expected, the voltage level of the external terminals A _n applies the C signal to the semiconductor chip, i.e. A _n signal Can be discriminated as a good product or a defective product by confirming that the product is as expected.

[0017] Note that the device under test there are other outside terminal B ₁ .about.B _X external terminals A ₁ to A _X as shown in FIG. 5,
Although not described in FIG. 7, the internal wiring connected to the external terminals A ₁ Similarly external terminal and internal wiring connected to ~A _X B ₁ ~B _X are also tested.

[0018]

However, depending on the circuit configuration of the device under test, it may not be possible to individually operate the mounted semiconductor chips. In this case, the semiconductor chips are sequentially operated and the internal chips are not operated. The conventional disconnection detection method for detecting the presence / absence of disconnection of the wiring cannot be applied.

Further, by individually operating the semiconductor chip as shown in FIG. 7, a test signal is applied to the external terminals A ₁ to A _X, then the C signal is applied to the semiconductor chip, all this work The test needs to be repeatedly performed for the external terminals, and the test takes time.

In addition, when it is determined that the semiconductor device is defective in the conventional test method, it is unclear whether the defect is caused by a defect of the semiconductor chip itself or a disconnection of the internal wiring. There is a problem that it is extremely difficult to analyze the cause.

An object of the present invention is to provide a disconnection detecting method capable of easily detecting a disconnection of a signal line commonly connected to a plurality of semiconductor chips.

[0022]

FIG. 1 is a principle diagram showing a disconnection detecting method according to the present invention. The same object is denoted by the same symbol throughout the drawings.

The object is to detect a disconnection of a signal line commonly connected to a plurality of semiconductor chips 11, 12 for a semiconductor device having a plurality of semiconductor chips 11, 12 mounted in the same package 1. a disconnection detection method, the signal line applies a constant current from the test power supply 6 to the connected external terminals a _n, measured terminal voltage VDF of the external terminal, is compared with the terminal voltage of the semiconductor device of good This is achieved by a method for detecting disconnection of internal wiring of a semiconductor device, which detects the presence or absence of disconnection of a signal line.

FIG. 1 shows a device under test to which the present invention is applied.
a plurality of semiconductor chips 11 and 12 in the same package 1 as shown in (a) are mounted, the terminals of the semiconductor chips 11 and 12 are connected to the external terminal A _n provided on the package via a wire or a wiring pattern I have.

[0025] When there is no disconnection in the internal wiring, including the connections for applying a constant current to an external terminal A _n constant current is shunted to both of the semiconductor chip, the voltage value VDF determined by the protection diode characteristics of the semiconductor chip It occurs between the external terminal _An and the ground terminal G.

[0026] In contrast to flow into the disconnection internal wiring 13 is generated external terminals A _n to the applied current is one of the semiconductor chip (11 in the figure), a voltage value VDF between the external terminals A _n and the ground terminal G _S naturally becomes higher than the voltage value VDF when there is no disconnection in the internal wiring.

Therefore, by applying a current from the constant current power supply to the external terminal to which the signal line is connected, measuring the voltage value at the external terminal, and comparing the measured voltage value with the previously measured terminal voltage value of the non-defective product. It is possible to detect the presence or absence of disconnection.

As described above, according to the disconnection detecting method of the present invention, the presence / absence of disconnection of the internal wiring can be detected without putting the semiconductor chip into an operating state, so that the mounted semiconductor chips can be individually operated for circuit configuration reasons. Even if it is not possible, disconnection can be detected.

Further, since it is not necessary to repeatedly apply a test signal, a control signal, and the like to each semiconductor chip, the operation is simplified and the test time is shortened. Can be detected only.

That is, it is possible to realize a disconnection detecting method capable of easily detecting a disconnection of a signal line commonly connected to a plurality of semiconductor chips.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the accompanying drawings. 2 is a diagram showing a distribution of voltage values at external terminals, FIG. 3 is a block diagram showing an example of a measuring device used for disconnection detection, and FIG. 4 is a flowchart showing a disconnection detection method according to the present invention.

As shown in FIG. 5, the device under test has external terminals.
A₁~ A_XExternal terminal B₁~ B _XAre each semiconductive
Connected to the semiconductor chip, and a single semiconductor chip
When a constant current is applied to the tip, the voltage value VDF changes as shown in FIG.
And (b).

On the other hand, the external terminals A ₁ through an internal wiring plurality of semiconductor chips are both to A _X and the external terminals B ₁ .about.B _X
2 (a) and (b)
2 are combined, the voltage value VDF is distributed as shown in FIG. 2 (c).

The voltage value VDF is a value determined by the protection diode characteristics of each semiconductor chip.
, (B) changes depending on the semiconductor chip constituting the device under test, and the distribution of the voltage value VDF shown in FIG. 2 (c) changes accordingly.

However, even when the semiconductor chips are different, the difference between the maximum value (max) and the minimum value (min) of the distribution of the voltage value VDF is similar, and if the number of semiconductor chips constituting the device to be measured is the same. As shown in FIG. 2C, the difference between max and min is approximate.

Therefore, the distribution of the voltage value VDF is shown in FIG.
As shown in (d), max deviates greatly from other voltage values VDF.
When the value includes the value, it means that a disconnection has occurred in the internal wiring between the external terminal whose voltage value VDF indicates the maximum value and the terminal of the semiconductor chip.

FIG. 3 shows an example of a measuring device for detecting a disconnection of the internal wiring of the device under test 2 based on the disconnection detecting method according to the present invention, wherein at least a socket (or probe unit) 3, a switch unit 4, a voltage It comprises a total of 5 and a test power supply 6.

The device under test 2 is mounted on a socket (or probe unit) 3, and the external terminals A _{1 to} A _X and B _{1 to} B _X (not shown) of the device under test 2 are connected to the socket (or probe unit). ) 3 to the switch unit 4.

The switch unit 4 has external terminals A ₁ -A
A _X, B ₁ ~B _X (not shown) and comprises a number of switches 41 corresponding to the switch 41 (FIG. A ₂₎ any external terminals other with connecting to the test power supply 6 An external terminal is connected to the ground circuit GND.

The switch units 4 connected to the external terminals A _{1 to} A _X and B _{1 to} B _X are not limited to a system in which the individual switches 41 are manually switched. It may be one that can be switched to.

One of the electrodes of the test power supply 6 is connected to the switch 41 of the switch unit 4 and the other is connected to the ground circuit GND.
Is connected to the switch unit 4 in parallel with the test power supply 6.

Although not shown, the measured value of the voltmeter 5 is digitized to store, for example, the measured value in a storage device, or to compare the measured value with a specified value to automatically determine good / bad. And display of measurement results and execution of printout and the like can be performed.

The breakage detecting method according to the present invention is set to a socket or a probe unit of the measuring apparatus device under test as shown in FIG. 4, the other to connect the external terminals A ₁ to the test power supply by operating the switch unit Is dropped to the ground circuit GND.

[0044] stores the measurement result by measuring the voltage of the external terminal A ₁ by a voltmeter and inputs a constant current to an external terminal A ₁ in the storage device until it is determined for all of the external terminals A ₁ to A _X The steps from the operation of the switch unit to the storage of the measurement result are repeated.

The difference between Vmax and Vmin is calculated with the maximum value of the measured values obtained from all of the external terminals A _{1 to} A _X as Vmax and the minimum value as Vmin, and the difference between Vmax and Vmin is compared with a specified value. If the size is larger, the device under test is defective. If the size is smaller, the device under test is non-defective.

Although not shown, the external terminal B ₁
Calculating the difference between Vmax and Vmin by measuring the voltage Similarly, the .about.B _X, larger by comparing the difference between Vmax and Vmin a specified value to be measured device failure, and good products DUT smaller I do.

As described above, according to the disconnection detecting method of the present invention, the presence or absence of disconnection of the internal wiring can be detected without putting the semiconductor chip into an operating state. Even if it is not possible, disconnection can be detected.

Further, since it is not necessary to repeatedly apply a test signal, a control signal, and the like to each semiconductor chip, the operation is simplified and the test time is shortened. Can be detected only.

[0049]

As described above, according to the present invention, it is possible to provide a disconnection detecting method capable of easily detecting a disconnection of a signal line commonly connected to a plurality of semiconductor chips.

[Brief description of the drawings]

FIG. 1 is a principle diagram showing a disconnection detection method according to the present invention.

FIG. 2 is a diagram showing a distribution of voltage values at external terminals.

FIG. 3 is a block diagram showing an example of a measuring device used for disconnection detection.

FIG. 4 is a flowchart illustrating a disconnection detection method according to the present invention.

FIG. 5 is a diagram illustrating a circuit configuration example of a device under test.

FIG. 6 is a diagram showing an example of disconnection of internal wiring.

FIG. 7 is a flowchart showing a conventional test method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Package 2 Device under test 3 Socket 4 Switch unit 5 Voltmeter 6 Test power supply 11, 12 Semiconductor chip 13 Disconnection 41 Switch

Continued on the front page (72) Inventor Takashi Tsubota 460 Oyama, Sazaka, Nagano Prefecture F-term in Fujitsu Media Devices Limited (Reference) 2G003 AA07 AB18 AE08 AF01 AF04 AF06 AG01 AH03 AH04 2G014 AA02 AB51 AC07 AC15

Claims (1)

[Claims] 1. A disconnection detecting method for detecting a disconnection of a signal line commonly connected to a plurality of semiconductor chips for a semiconductor device having a plurality of semiconductor chips mounted in the same package. A constant current is applied from a test power supply to the external terminal to which the signal line is connected, and the terminal voltage at the external terminal is measured and compared with the terminal voltage of a non-defective semiconductor device. A method for detecting internal wire disconnection in a semiconductor device, comprising detecting presence or absence.