JPH11326439A - Low power semiconductor integrated circuit capable of leak current and leak inspection method - Google Patents

Abstract

(57) [Summary] [Problem] 1. In a semiconductor integrated circuit composed of MT-CMOS, a failure occurs in which a voltage is always supplied from a power supply terminal to a pseudo power supply line due to a short circuit between a source and a drain of a high threshold transistor, a failure in a control line, and the like. In such a case, it is difficult to detect a failure and specify a failure location. 2. Similarly, the required circuit area increases. [MEANS FOR SOLVING PROBLEMS] A power supply terminal for inspection is provided on the pseudo power supply line, a high threshold transistor is turned on at the time of inspection, and the resistance between the power supply terminal and the power supply terminal for inspection is measured to find a failure or a failure location. 2. Use a diode.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a semiconductor integrated circuit,
In particular, M having different thresholds for low power consumption
1. Field of the Invention The present invention relates to a low-power semiconductor integrated circuit compatible with a leak current and having an OS transistor mounted thereon and a method of inspecting the same.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for lower power consumption (power consumption) of semiconductor integrated circuits in order to reduce the size and integration of semiconductor devices. In order to reduce the power, it is effective to reduce the power supply voltage. (Note, power consumption is CV ² f
Is determined by Here, C is the internal capacitance, V is the power supply voltage, and f is the operating frequency. However, simply lowering the power supply voltage slows down the operation speed (on / off switching speed) of the transistor. Therefore, the threshold voltage of a MOS transistor (a field effect transistor that controls a current path by applying a voltage to a gate electrode that is electrically insulated from a current path by an oxide film) is being reduced in particular.

In a CMOS circuit composed of low threshold transistors, the leakage current (Iddq) increases when the potential of the input terminal of each node does not change, that is, in a steady state. (Note that these matters and the reasons thereof, as well as the drive voltage, etc., are described in, for example, IEICE Technical Report 1CD93-107 (1993-1).
0) Yasuyuki Matsutani and 3 other authors, "IV, 10MHZ _Z operation Mu"
lti-Threshold CMOS Logic Technology "
And so on, so further description is omitted. Separately, as the size of semiconductor integrated circuits increases,
The leakage current of the entire circuit is also increasing.

For this reason, the leakage current due to the failure is relatively smaller than the leakage current in the steady state, and it is difficult to detect the failure by detecting an increase in the leakage current of the entire circuit. It is becoming. Therefore, as a measure against this, for example, IEEE 1996 CUSTOM I
NTEGRATED CIRCUIT CONFERE
At NCE, the following means have been proposed.

FIG. 9 shows a part of a schematic configuration of the proposed semiconductor integrated circuit (only a part related to the present invention).
It is the electric circuit diagram which extracted and shown. As shown in the figure, the semiconductor integrated circuit is divided into a plurality of functional blocks (here, two functional blocks 9041 and 9042 are shown as logic circuits).

[0006] A normal power supply terminal 901 which is a terminal of a power supply used by the functional block during normal operation is connected between pseudo power supply lines 9071 and 9072 which directly supply voltages to the functional blocks 9041 and 9042 respectively. , MOS transistor 905 for controlling power supply
1, 9052 are interposed. (Note that an electric wire paired with the normal power supply terminal 901, for example, a diode provided in a ground signal line or a pseudo power supply line is not shown because it is complicated.
Since the role of the signal between 41 and 9042 is a well-known fact, the description thereof is omitted. )

A MOS transistor 90 for controlling power supply is also provided between an inspection power supply terminal 902 which is a terminal of a power supply used for inspection and pseudo power supply lines 9071 and 9072.
61, 9062 are interposed. Next, the control circuit 90
3 controls the MOS transistors 9061 and 9062 so that only one of the two functional blocks 9041 and 9042 is supplied with power from the inspection power supply terminal 902 in response to the control signal 900, and The MOS transistors 9051 and 9052 are also controlled so that power is supplied from the normal power supply terminal 901 only to the block.

In the following, it is assumed that a failure causing a large leakage current exists in the functional block 9041, and the procedure (operation) of finding a failure or determining the presence or absence of the failure will be described based on the assumption. When the control signal 900 specifies the test of the functional block 9041, the control circuit 903, which is a means for specifying the test target, turns off the MOS transistor 9051 (OF).
F, closed), 9052 on (ON, open), 9061
Is turned on, and 9062 is turned off.

Thus, only the test power supply terminal 902 supplies power to the function block 9041, and the other function block 9042 supplies power to the normal power supply terminal 901. Therefore, by measuring the amount of current at the test power supply terminal 902, it is possible to measure only the leak current flowing in the steady state of the functional block 9041.

The difference between the leakage current including the increase due to the failure in the functional block 9041 and the leakage current when there is no failure in the functional block 9041 is, of course, a ratio more proportional to the difference between the leakage current of the entire semiconductor integrated circuit. Because it gets bigger,
By measuring the current of the inspection power supply terminal 902, it is easy to determine whether there is a failure. Note that the above is the case of two functional blocks, but even in the case of three or more,
Needless to say, the structure such as the interposition of the MOS transistor and the ON / OFF control are similarly performed.

Next, in a C (Complementary) MOS semiconductor integrated circuit composed of low-threshold transistors, since the leakage current in a steady state is inevitably increased, the power consumption of a device using this semiconductor integrated circuit is unnecessary. Tend to increase. Therefore, C considering this countermeasure
MT-C in which a low threshold transistor and a high threshold transistor are arranged as one of MOS semiconductor integrated circuits
MOS (Multi Threshold)
Ethhold (CMOS) semiconductor integrated circuits have been proposed.

As an example of the conventionally proposed MT-CMOS semiconductor integrated circuit, for example, the Institute of Electronics, Information and Communication Engineers:
There is one as shown in IEICE Technical Report ICD93-107 (1993-10). Hereinafter, referring to FIG.
This MT-CMOS semiconductor integrated circuit will be described.

FIG. 8 is an electric circuit diagram showing a part of the schematic configuration of the MT-CMOS semiconductor integrated circuit. As shown in the figure, between a power supply terminal 801 for supplying a high-potential-side voltage for operation and a power supply terminal 802 for providing a low-potential-side voltage, a low-threshold transistor is provided and a pseudo power supply line 805 is provided. And a functional block (illustrated as a logic circuit) 807 that uses the pseudo power supply line 806 as a high-potential side power supply and a low-potential side power supply, respectively. Then, the power supply terminal 801, the pseudo power supply line 805, and the power supply terminal 8
High threshold transistors 803 and 804 are interposed between the power supply line 02 and the pseudo power supply line 806, respectively.

The operation of the circuit shown in FIG. 1 will be specifically described below. When the function block 807 operates, charge is supplied to the function block 807 by turning on the high threshold transistors 803 and 804, and the function block 807 including the low threshold transistor operates at high speed. Conversely, during standby, the high threshold transistor 8
By turning off the switches 03 and 804, the leakage current from the power supply terminal 801 to the functional block 807 and from the functional block 807 to the power supply terminal 802 are suppressed. Therefore, the leakage from the power supply terminal 801 to the power supply terminal 802 is extremely small.

[0015]

However, in the first conventional low-power semiconductor integrated circuit corresponding to leak current, two divided transistors and two control signal lines are required for each divided functional block. Therefore, the required area on the integrated circuit becomes large, which leads to an increase in manufacturing cost. For this reason, it is desired to develop and implement a semiconductor integrated circuit whose manufacturing cost is kept low by making it possible to control a functional block to which a test power supply terminal supplies a voltage with a smaller circuit configuration, and a test method thereof. Was.

Next, in the low-power semiconductor integrated circuit of the second conventional example corresponding to the leakage current, pseudo-always due to short-circuits between the source and drain of the high-threshold transistors 803 and 804, failure of the control line, etc. When a failure (hereinafter, referred to as an ON failure) in which a voltage is supplied from the power supply terminals 801 and 802 to the power supply lines 805 and 806 occurs, or when a connection line to the power supply terminal of the high-threshold transistors 803 and 804 occurs. A failure in which voltage cannot be supplied from the power supply terminals 801 and 802 to the pseudo power supply lines 803 and 804 due to disconnection, disconnection of a connection line to the pseudo power supply line, failure of a control signal line, and the like (hereinafter, referred to as an off failure). Occurs, the following problems may occur.

First, a case where an ON failure occurs,
During the operation of the functional block 807, the high threshold transistors 803 and 804 are controlled to be turned on, and the voltage is supplied from the respective power supply terminals 801 and 802, so that the functional block operates normally and adversely affects the operation. Nothing. On the other hand, when the functional block 807 is on standby (power is supplied but the circuit is stopped)
, The high threshold transistors 803 and 804 are turned off, but the voltage is actually supplied due to a failure. At this time, since this is a standby time, this itself has no logical effect.

However, since the high threshold transistors 803 and 804 are not turned off during standby, a large leak current flows from the power supply terminal 801 to the power supply terminal 802 via the functional block 807 including the low threshold transistors. Will occur. As a result, the MT-C that the leakage current during standby is small.
The advantage of the MOS semiconductor integrated circuit will be lost.

However, in the conventional MT-CMOS semiconductor integrated circuit, when such a failure that the high threshold transistors 803 and 804 are not turned off occurs, it cannot be detected.

When an off fault occurs, the voltage is not supplied, so that the function block 807 naturally does not operate. However, if a situation occurs in which the function block 807 does not operate once, the cause is a high threshold transistor. 803, 804
It is difficult to immediately distinguish and detect whether the power supply is in the power supply portion or the functional block 807. Therefore, it has often been difficult to reduce the frequency of subsequent failures by improving the design.

Therefore, an inspection method for an MT-CMOS semiconductor integrated circuit which has a means for detecting an ON failure and which can reliably exhibit functions of high-speed operation and low power consumption is realized. MT- which can detect whether the function block does not operate due to the power supply portion or the function block.
It has been desired to realize a low-power semiconductor integrated circuit capable of leak current rather than CMOS and a method of testing the same.

[0022]

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has been made by providing a power supply terminal for inspection on a pseudo power supply line and using a diode.
It is an object of the present invention to provide a low-power semiconductor integrated circuit capable of leak current detection and a test method therefor, in which a fault in which a leak current occurs can be easily found and a fault location can be easily specified. Specifically, the configuration is as follows.

According to the first aspect of the present invention, the first terminal for supplying the high potential side voltage, the second terminal for supplying the low potential side voltage, the first terminal and the second terminal are provided. A functional block driven by electric power from a terminal (one is at a high potential and the other is at a low potential), and further includes a plurality of low threshold transistors arranged (including other elements). , Is provided between the first terminal and the functional block (including a mode in which wiring is provided between the first terminal and the functional block if it is electrically connected), and is turned on and off according to a switching signal from the outside. A high-threshold transistor for switching the connection state between the first terminal and the functional block between on and off by switching, and a high-threshold transistor between the second terminal and the functional block, and the second terminal when switched on and off. Terminals and functional blocks At least one of the high-threshold transistors that switches the connection state between on and off corresponds to the high-threshold transistor if the high-threshold transistor is interposed. The first terminal or the second terminal is connected, and when the high threshold transistor is not provided, the first terminal or the second terminal and the functional block are connected (directly) in total of 2 At least one (two if there are two high threshold transistors) pseudo power supply line that connects (directly) the power supply line, the high threshold transistor and the functional block, and the pseudo power supply line At least one test terminal (two if two high threshold transistors) is used, and the switching of the high threshold transistor on and off is controlled by an instruction from an inspector, an inspection signal from a tester, or the like. In the leakage current corresponding type low power semiconductor integrated circuit and control means,

An on-control step of turning on the high-threshold transistor by control means provided for testing the high-threshold transistor; and a high threshold controlled to be on after the on-control step. An inspection step of inspecting a resistance between the first terminal or the second terminal connected to the value transistor and the corresponding inspection terminal; and a resistance value in the inspection step being a predetermined value. If the value is equal to or more than the value, the high-threshold transistor controlled to be turned on of the leak-response low-power semiconductor integrated circuit is determined to be defective, and in many cases, the leak-response low-power transistor integrated with the high-threshold transistor A method for testing a low power semiconductor integrated circuit capable of leaking, including a transistor determining step of determining that the semiconductor integrated circuit is also defective. That.

With the above structure, the first terminal for supplying the high potential side voltage, the second terminal for supplying the low potential side voltage, and the power from the first and second terminals are used. Not only is configured to be driven, but also a functional block configured by further arranging a plurality of low-threshold transistors, and is interposed between the first terminal and the functional block. A high-threshold transistor and a second terminal for energization control for switching the connection state between the first terminal and the functional block between on and off by switching on and off in accordance with the switching signal from At least one of the high-threshold transistors interposed between the functional block and switching on / off the connection state between the second terminal and the functional block by switching on and off; When a threshold transistor and a high-threshold transistor are interposed, the high-threshold transistor is connected to a first terminal or a second terminal corresponding to the high-threshold transistor. Otherwise, a total of two power lines connecting the first terminal or the second terminal to the functional block, and at least one power line connecting the high threshold transistor and the functional block (high threshold). Pseudo-power supply line connected to the pseudo power supply line, at least one (two if high-threshold transistor is used) test terminal, and a high-threshold transistor The following operation is performed in a low-power semiconductor integrated circuit compatible with a leakage current including a control unit that controls switching between ON and OFF.

In the ON control step, a control means provided separately or incorporated in the substrate or the like turns on (ON, energized) the high threshold transistor by applying a voltage or the like. In the inspection step, of course, if necessary,
After the other transistor is turned off (OFF, closed) or a constant voltage is applied to the first or second terminal and the inspection terminal, the transistor is connected to the high-threshold transistor that is turned on in the on-control step. The resistance between the corresponding first or second terminal and the corresponding inspection terminal is measured.

In the transistor determining step, when the resistance value measured in the inspection step is equal to or more than a predetermined value determined in advance according to measurement conditions and the like, the low power semiconductor integrated circuit is controlled to be turned on. The high-threshold transistor is determined to be defective due to the ON failure, and in many cases, the leak-response low-power semiconductor integrated circuit integrated with the high-threshold transistor is also determined to be defective. (Of course, 2
When there are two high-threshold transistors, one transistor may be discarded immediately after the other transistor is determined to be ON without being measured. )

According to the second aspect of the present invention, the first terminal for supplying the high potential side voltage, the second terminal for supplying the low potential side voltage, the first terminal and the second terminal are provided. A functional block driven by power from the terminal and further including a plurality of low-threshold transistors disposed between the first terminal and the functional block; A high-threshold transistor for switching the connection state between the first terminal and the function block between on and off, and a second terminal and the function block interposed between the second terminal and the function block;
At least one of the high-threshold transistors, which switches the connection state between the second terminal and the functional block between on and off by switching on and off, and a high-threshold transistor are interposed. When the high threshold transistor is not connected, the first terminal or the second terminal is connected. When the high threshold transistor is not provided, the first terminal or the second terminal is connected. Terminal and the functional block, a total of two power supply lines, at least one pseudo power supply line connecting the high threshold transistor and the functional block, and at least one pseudo power supply line connected to the pseudo power supply line. In a leakage current-compatible low-power semiconductor integrated circuit including a test terminal and control means for controlling switching of a high threshold transistor on and off,

An off control step of turning off the high threshold transistor by the control means if at least one of the high threshold transistors is two, and turning off the high transistor after the off control step Applying a different potential to the first terminal or the second terminal connected to the high-threshold transistor and the corresponding test terminal, and applying a different potential after the potential applying step. The first terminal or the second terminal
Leak current measuring step of measuring the leak current between the terminal of the above and the inspection terminal,

If the measured value in the leak current measuring step is equal to or larger than a predetermined value, a function block judgment for judging the high threshold transistor controlled to be off of the low power semiconductor integrated circuit corresponding to the leak as a defect is performed. And an inspection method for a leak-response type low-power semiconductor integrated circuit having steps.

According to the above configuration, the first terminal for supplying the high-potential-side voltage, the second terminal for supplying the low-potential-side voltage, and the power from the first terminal and the second terminal. A functional block that is driven and configured by arranging a plurality of low-threshold transistors, and is interposed between the first terminal and the functional block, and is connected to the first terminal by switching on and off. A high-threshold transistor for switching the connection state between the block and the function block; and a high-threshold transistor interposed between the second terminal and the function block, the connection between the second terminal and the function block by switching on and off. At least one of the high threshold transistors for switching the state between on and off, and if a high threshold transistor is provided, this high threshold transistor And a total of two power lines connecting the first terminal or the second terminal to the functional block when the high threshold transistor is not interposed. At least one pseudo power line connecting the high threshold transistor and the functional block, at least one test terminal connected to the pseudo power line, and switching on and off of the high threshold transistor The following operation is performed in the low-power semiconductor integrated circuit adapted for leakage current having the control means for controlling.

In the off control step, the control means controls the high threshold transistor and, if there are two high threshold transistors, at least one of the high threshold transistors in accordance with the instruction of the inspector or the inspection signal from the tester. Turn off. (If both are tested at the same time, both are turned off.) In the potential applying step, the first terminal or the second terminal connected to the high threshold transistor which is turned off after the off control step And a corresponding test terminal are supplied with different potentials which are predetermined for test in many cases.

In the leak current measuring step, after the potential applying step, the first terminal or the second terminal to which a different potential is applied is connected to the inspection terminal while turning off the other transistor if necessary. Measure the leak current during the period. In the function block determination step, when the measured value in the leak current measurement step is equal to or more than a predetermined value determined from a potential difference or the like, the high-threshold transistor (to be inspected) of the leak-capable low-power semiconductor integrated circuit is turned off. It is determined to be defective as a failure.

According to the third aspect of the present invention, there is provided a functional block set including a functional block and a pseudo power supply line for supplying a high-potential or low-potential power to the functional block.
An inspection target specifying unit (including a signal line for transmitting a signal, etc.) for outputting a signal such as a voltage for specifying a functional block to be inspected among the plurality of functional blocks; An inspection power supply terminal for supplying power to the pseudo power supply line of the specified functional block to be inspected, and a normal power supply terminal for supplying power to the pseudo power supply line of the functional block not specified as the inspection target by the inspection target designation means. The one connected between the normal power supply terminal and each of the pseudo power supply lines and connected to the pseudo power supply line of the functional block designated as the inspection target by the presence or absence of the designation signal from the inspection target designation means is turned off. Those connected to the pseudo power supply lines of the function blocks that are controlled and not designated as the inspection target are energization control transformers provided for each of the function block sets that are controlled to be turned on. And a diode provided between the test power supply terminal and each of the pseudo power supply lines in the direction in which power is supplied and provided for each functional block combination. It is a semiconductor integrated circuit.

With the above configuration, the following operation is performed.
A functional block set includes a functional block and a pseudo power supply line for supplying power on the high potential side or the low potential side to the functional block. Inspection target designating means outputs a signal for designating a functional block (set) to be inspected from among a plurality of functional blocks (sets) in accordance with an instruction of an inspector, an inspection signal from a tester, or the like. Specifically, it controls on / off of a conduction control transistor (Note, not necessarily a high threshold transistor) provided in each functional block group.

An inspection power supply terminal supplies power to the pseudo power supply line of the functional block to be inspected designated by the inspection object designation means. (Or, such a wiring or structure is used.) A normal power supply terminal supplies power to a pseudo power supply line of a functional block that is not specified as an inspection target by the inspection target specifying means. (Alternatively, such wiring and structure are used.)

For example, a high-threshold transistor for energization control provided for each functional block set is interposed between the normal power supply terminal and each of the pseudo power supply lines, and is specified by the test target specifying means. Those connected to the pseudo power supply line of the functional block specified as the inspection target according to the presence / absence of the signal (for example, high or low voltage) are turned off, and connected to the pseudo power supply line of the functional block not specified as the inspection target. What you do is controlled on. A diode is interposed between the test power supply terminal and each of the pseudo power supply lines in the direction in which power is supplied for each functional block set.

According to the fourth aspect of the present invention, the third aspect is provided.
The method for testing a low power semiconductor integrated circuit corresponding to a leak according to the invention described above, wherein the functional block designated as the test target is controlled by, for example, turning off a high threshold transistor for the conduction control. An inspection power supply step of supplying power from the inspection power supply terminal to the pseudo power supply line of the functional block via the diode, and a designation signal from the inspection object designation means for the functional block not designated as the inspection object. A normal power supply step of controlling the energization control transistor to turn on and supplying power from the normal power supply terminal to the pseudo power supply line of the corresponding function block; According to whether the diode is interposed in
A constant voltage supply step of applying a high or low voltage that does not generate a current flowing through a diode connected to a pseudo power supply line other than the function block to be inspected, as compared with the inspection power supply terminal, A leak current amount measuring step of measuring a leak current amount of the inspection power supply terminal while the constant voltage supplying step is performed;
A comparing step of comparing the measured value of the leak current amount measuring step with a predetermined value, and if the measured value is equal to or greater than a predetermined value, the function block to be inspected is determined to be defective And a determining step of inspecting the leak-response type low current value semiconductor integrated circuit.

With the above configuration, the following operation is performed as the inspection of the low power semiconductor integrated circuit corresponding to the leak according to the third aspect of the present invention. In the test power supply step, the power supply control transistor of the function block is turned off to the functional block designated as the test target, and the pseudo power supply line is supplied with power from the test power supply terminal via the diode. In the normal power supply step, the power supply control transistor is turned on by the specification signal from the test target specifying means, and the pseudo power supply line of the corresponding functional block is supplied with the normal power supply. Power is supplied from the terminal.

In the constant voltage supply step, the normal power supply terminal is compared with the test power supply terminal in accordance with whether the diode is interposed on the high potential side or the low potential side of the function block. A high or low (interposed to the low voltage side) constant voltage that does not generate a current flowing through the diode connected to the pseudo power supply line other than the block is provided. In the leak current amount measuring step, the leak current amount of the inspection power supply terminal is measured during the constant voltage supply step. In the comparing step, the measured value in the leak current amount measuring step is compared with a predetermined value. In the determination step, if the measured value is equal to or greater than the predetermined value as a result of the comparison step, the function block to be inspected is determined to be defective because a failure that causes leakage current has occurred.

According to a fifth aspect of the present invention, there is provided a functional block set including a functional block and a pseudo power supply line for supplying a high-potential or low-potential power to the functional block;
An inspection target specifying unit that outputs a signal for specifying a functional block to be inspected among the plurality of functional blocks,
An inspection power supply terminal for supplying power to the pseudo power supply line of the function block to be inspected designated by the inspection object designation means; and a power supply to the pseudo power supply line of the function block not designated as the inspection object by the inspection object designation means. And a pseudo power supply line of a functional block that is interposed between the test power supply terminal and each of the pseudo power supply lines and that is designated as a test target by the presence or absence of a designation signal from the test target designation means. Connected to a pseudo power supply line of a functional block not designated as a test target is controlled to be turned off, and an energization control transistor provided for each functional block set; and A predetermined height provided between a normal power supply terminal and each of the pseudo power supply lines in a direction in which power is supplied and provided for each functional block set. And a leak-aware low-power semiconductor integrated circuit and a value of the diode.

With the above configuration, the following operation is performed.
There is at least one functional block set including a functional block and a pseudo power supply line for supplying power on the high potential side or the low potential side to the functional block. The inspection target designation means outputs a signal for designating a functional block to be inspected among the plurality of function blocks to a corresponding energization control transistor. An inspection power supply terminal supplies power to the pseudo power supply line of the functional block to be inspected designated by the inspection object designation means. A normal power supply terminal supplies power to the pseudo power supply line of the functional block not specified as the inspection target by the inspection target specifying means.

For each of the functional block sets, the current-controlling transistor interposed between the normal power supply terminal and each of the pseudo power supply lines has the function specified as the inspection target by the presence or absence of the specification signal from the inspection target specifying means. Those connected to the pseudo power supply line of the block are controlled to be on, and those connected to the pseudo power supply line of the functional block not specified as the inspection target are controlled to be off. A diode having a predetermined threshold value is provided between the test power supply terminal and each pseudo power supply line in the direction in which power is supplied for each functional block set.

In the invention according to claim 6, claim 5
A method for testing a leak-response type low-power semiconductor integrated circuit according to the above, wherein the energization control transistor is turned on by a designation signal from the inspection object designation means to a pseudo power supply line of the functional block designated as the inspection object. An inspection power supply step of controlling and supplying power from the inspection power supply terminal; and a power supply from the normal power supply terminal via the diode to the pseudo power supply line of the functional block not designated as the inspection target. According to the power supply step and whether the energization control transistor is interposed on the high-potential side or the low-potential side of the functional block, the inspection power supply terminal is set as the inspection target compared with the normal power supply terminal. High or low voltage that does not generate the current flowing through the diode connected to the pseudo power line other than the function block A constant voltage supply step, a leakage current amount measurement step of measuring a leakage current amount of the inspection power supply terminal while the constant voltage supply step is performed, a measurement value of the leakage current amount measurement step and a predetermined value determined in advance. And a determining step of determining that the functional block to be inspected is defective if the measured value is equal to or greater than a predetermined value as a result of the comparing step. This is a testing method for a compliant low current value semiconductor integrated circuit.

With the above configuration, the following operation is performed as the inspection method of the leak-response type low power semiconductor integrated circuit according to the fifth aspect. In the test power supply step, the energization control transistor is turned on to the pseudo power supply line of the functional block specified as the test target by the specification signal from the test target specifying means, and power is supplied from the test power supply terminal.

In the normal power supply step, power is supplied from the normal power supply terminal via a diode to a pseudo power supply line of a functional block not specified as an inspection target. In the constant voltage supply step, the test power supply terminal is compared to the normal power supply terminal, and the test power supply terminals other than the functional block to be tested are determined according to whether the transistor is provided on the high potential side or the low potential side of the function block A high or low constant voltage that does not generate a current flowing through a diode connected to the pseudo power supply line is applied.

In the leak current amount measuring step, the amount of leak current at the inspection power supply terminal is measured while the constant voltage supply step is being performed. In the comparing step, the measured value in the leak current amount measuring step is compared with a predetermined value. In the determination step, if the result of the comparison step is that the measured value is equal to or greater than a predetermined value, the function block to be inspected is determined to be defective.

[0048]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on its embodiments. (First Embodiment) FIG. 3 is an electric circuit diagram showing a part of a schematic configuration of an MT-CMOS semiconductor integrated circuit according to a first embodiment of the present invention.

As shown in the figure, a low threshold transistor is provided between a power supply terminal 301 for supplying a high potential side voltage for operation and a power supply terminal 302 for providing a low potential side voltage. And a functional block (illustrated as a logic circuit) 307 that uses the pseudo power supply line 305 and the pseudo power supply line 306 as power sources on the high potential side and the low potential side, respectively. High-threshold transistors 303 and 304 are interposed between the power supply terminal 301 and the pseudo power supply line 305 and between the power supply terminal 302 and the pseudo power supply line 306, respectively. In addition, power terminals 308 and 309 for inspection are connected to the pseudo power lines 305 and 306, respectively.

FIG. 1 shows an inspection procedure according to the present embodiment. Hereinafter, a method of testing the semiconductor integrated circuit of FIG. 3 will be described with reference to the flowchart. (Step 101)
First, the high threshold transistor is turned on. Thereby, the pseudo power supply line 30 is connected from the power supply terminals 301 and 302 through the high threshold transistors 303 and 304, respectively.
5, 306 can be supplied with voltage.

(Step 102) Next, the power supply terminal 30
1 and the test power supply terminal 308 and the resistance between the power supply terminal 302 and the test power supply terminal 309 are measured. If there is no failure in the semiconductor integrated circuit, the resistance between the power supply terminal 301 and the test power supply terminal 308 and between the power supply terminal 302 and the test power supply terminal 309 should be in a low resistance state. (Step 103) The measured resistance value is compared with a predetermined value which is a predetermined value which is previously obtained by actual results or calculation and which is a low value indicating normality, and if it is lower than the predetermined value, the semiconductor integrated circuit is passed. On the contrary, if the value is high, the failure is determined as an ON failure of the high threshold transistor.

As described above, according to the present embodiment, the pseudo power supply line is provided with the power supply terminal for inspection, and the resistance between the power supply terminal and the power supply terminal for inspection is measured, whereby the high threshold voltage is obtained. Is there a failure that the voltage cannot be supplied from the power supply terminal to the pseudo power supply line due to disconnection of the connection line of the value transistor to the power supply terminal, disconnection of the connection line to the pseudo power supply line, failure of the control signal line, etc. This makes it easy to check whether or not a failure has occurred. Note that in this embodiment mode, the high threshold transistor and the pseudo power supply line are provided on both the high potential side and the low potential side. However, even when only one of them is provided, the resistance measurement is similarly performed. Inspection and failure site identification.

(Second Embodiment) Next, similarly to the first embodiment, a second embodiment of the present invention will be described with respect to the semiconductor integrated circuit inspection method of FIG.
FIG. 2 shows an inspection procedure in the present embodiment. Hereinafter, a method of testing the semiconductor integrated circuit of FIG. 3 will be described with reference to the flowchart.

(Step 201) First, the high threshold transistor is turned off. Thereby, the power supply terminal 30
1 and 302 and the corresponding pseudo power supply lines 305 and 306 are in a high impedance state. (Step 202) Next, in order to confirm the high impedance state, the power supply terminal 301 and the test power supply terminal 309 and the power supply terminal 302 and the test power supply terminal 309 are used.
During the voltage is applied.

(Step 203) The leak current between each is measured. This measurement may be performed on either the power supply terminal side or the inspection power supply terminal side. If there is no failure in the semiconductor integrated circuit, the power supply terminal 301 and the test power supply terminal 308 and the power supply terminal 302 and the test power supply terminal 309 are used.
The amount of leakage current between should be small because each is in a high impedance state. (Step 204) Finally, the measured leak current amount is compared with a predetermined value as in the first embodiment. If the value is smaller than the predetermined value, the semiconductor integrated circuit is accepted. If the value is larger than the predetermined value, the semiconductor integrated circuit is determined to be defective due to an off failure of the high threshold transistor.

As described above, according to the present embodiment, the power supply terminal for inspection is provided on the pseudo power supply line, and the amount of leakage current between the power supply terminal and the power supply terminal for inspection is measured, whereby high power consumption is achieved. This makes it easy to check for a failure in which a voltage is always supplied from the power supply terminal to the pseudo power supply line due to a short circuit between the source and the drain of the threshold transistor, a failure in the control line, and the like. In this embodiment, the high potential side,
Although the high threshold transistor and the pseudo power supply line are provided on both of the low potential sides, even when only one of them is provided, the inspection by measuring the leak current can be similarly performed.

(Third Embodiment) Next, a third embodiment of the present invention will be described.
An embodiment will be described. FIG. 4 is a diagram of an electric circuit in which a part of the schematic configuration of the semiconductor integrated circuit according to the third embodiment is extracted and shown, and has basically the same configuration as that shown in FIG. 9 as a conventional example. is there. For this reason, the same components are denoted by the same reference numerals. However, the MOS transistors 9061 and 9062 for controlling the supply of the voltage from the inspection power supply terminal 902 to the functional block are connected to the diode 4.
011 and 4012, and the difference is that the control signal lines of the MOS transistors 9061 and 9062 are eliminated. Therefore, it goes without saying that the configuration of the control circuit itself is also simplified.

FIG. 4 shows a case where the test power supply terminal 902 is provided on the high potential side of the functional block. When the test power supply terminal 902 is provided on the low potential side of the functional block, The directions of the diodes 4011 and 4012 are reversed. FIG. 5 shows an inspection procedure in the present embodiment. Hereinafter, the inspection method of the semiconductor integrated circuit of FIG. 4 will be described with reference to the flowchart.

(Step 501) First, the control signal 90
The function block to be inspected is selected by 0. Here, it is assumed that the function block 9041 has been selected as a target. Accordingly, the control circuit 903 controls the transistors 9051 for controlling the conduction, preventing leakage, and specifying the test target so that power is supplied from the normal power supply terminal 901 to the functional blocks 9042 other than the test target functional block 9041. Off, 9052 on. (Step 502) Next, the inspection target function block 90
41 from the inspection power supply terminal 902 to the diode 401
Give via 1

(Step 503) Normal power supply terminal 901
Further, power is supplied to the function block 9042 which is not the inspection target via the conduction control transistor 9052. At this time, if the test power supply terminal 902 is provided on the high potential side (low potential side) of the functional block, the test power supply terminal 90
2. A voltage sufficiently higher (lower) than the test power supply terminal 902 is applied to the normal power supply terminal 901 in consideration of the voltage drop of the conduction control transistor 9052 so that no current flows through the path of the diode 4012 and the pseudo power supply line 9072. give.

(Step 504) Function block 904
The semiconductor integrated circuit is operated until the internal state of the semiconductor integrated circuit 1 becomes a desired state for inspection. (Step 505) In the steady state in the desired state of the function block 9041, the amount of leakage current is measured at the inspection power supply terminal 902. (Step 506) Finally, the measured amount of leak current is compared with a predetermined value. If the measured value is smaller than the predetermined value, the semiconductor integrated circuit is accepted. If the measured value is larger, an abnormal leak current is detected in the function block 9041. It is determined that the defective product is defective.

As described above, according to the present embodiment, the power supply control conventionally performed by two high threshold transistors and two control signal lines for each divided functional block is:
This can be achieved with one energization control and in many cases a high threshold transistor, one diode and one control signal line. As a result, the required area on the integrated circuit can be reduced, leading to a reduction in manufacturing cost.

In this embodiment, the pass / fail of the functional block is determined by measuring the leakage current at the test power supply terminal 902. However, the amount of leak current flowing through the test power supply terminal 902 inside the semiconductor integrated circuit is determined. It is also possible to provide a current measuring unit for measuring and outputting a determination signal of the result to the outside, and make a determination based on the output signal.
Further, the MOS transistor 905 in the present embodiment
When the transistors 1 and 9052 are high threshold transistors and the functional blocks 9041 and 9042 are low threshold transistors, the present invention can be similarly implemented in an MT-CMOS semiconductor integrated circuit.

In step 505, the signal state inside the functional block, that is, the path through which the current leaks varies depending on the on / off state of the transistor. It is necessary to determine this route in the state of, and to inspect various routes, it is necessary to set in various states, so that it is needless to say that procedure manuals for these have been created in advance. is there. However, this differs for each functional block, and has no direct relation to the gist of the present invention, so that the description thereof is omitted.

(Fourth Embodiment) A fourth embodiment of the present invention will be described. FIG. 6 is a diagram of an electric circuit in which a part of a schematic configuration of a semiconductor integrated circuit according to the fourth embodiment is extracted. This electric circuit is substantially the same as that shown as 1 of the conventional example in FIG. For this reason, the same components are denoted by the same reference numerals. However, the MOS transistors 9051 and 9052 for controlling the supply of the voltage from the normal power supply terminal 901 to the function block (logic circuit) are replaced with the diodes 6011 and 6012, and
The difference is that the control signals for the transistors 9051 and 9052 are eliminated. FIG. 6 shows the case where the test power supply terminal 902 is provided on the high potential side of the functional block. When the test power supply terminal 902 is provided on the low potential side of the functional block, the diode 6011 The direction of 6012 is reversed.

FIG. 7 shows an inspection procedure according to this embodiment. Hereinafter, the inspection method of the semiconductor integrated circuit shown in FIG. 6 will be described with reference to the flowchart. (Step 701) First, a functional block to be inspected is selected by the control signal 900. Here, the function block 904
1 is selected as a target. Therefore, the control circuit 903
Is the inspection power supply terminal 90
The power supply control transistor 9061 is turned on and the power supply control transistor 9062 is turned off so that power is supplied from the power supply 1. (Step 702) Next, the inspection target function block 90
The power to the power supply 41 is supplied from the inspection power supply terminal 902 via the conduction control transistor 9061.

(Step 703) Power is supplied to the function block 9042 other than the test target function block 9041 from the normal power supply terminal 901 via the diode 6012. At this time, if the test power supply terminal 902 is provided on the high potential side (low potential side) of the functional block, the power is supplied so that a current flowing through the path of the normal power supply terminal 901, the diode 6011, and the pseudo power supply line 9071 is not generated. Considering the voltage drop of the control transistor 9061, the inspection power supply terminal 90
2 is given a sufficiently higher (lower) voltage than the normal power supply terminal 901. (Step 704) The semiconductor integrated circuit is functionally operated until the internal state of the function block 904A becomes a desired state for inspection.

(Step 705) Function block 904
1. In a steady state in a desired state, the amount of leakage current is measured at the power supply terminal 902 for inspection. (Step 706) Finally, the measured value of the leak current is compared with a predetermined value. If the measured value is smaller than the predetermined value, the semiconductor integrated circuit is accepted. Is determined to be a defective product having a failure that causes a failure.

As described above, according to the present embodiment, as in the third embodiment, two transistors and two control signal lines are used for each of the conventionally divided functional blocks. Power control can be performed with one transistor for controlling the conduction and in many cases a transistor having a high threshold value, one diode, and one control signal line. As a result, the required area on the integrated circuit can be reduced, leading to lower manufacturing costs.

In the present embodiment, the leak current is measured at the test power supply terminal 902, and the quality of the functional block is determined based on the measured leak current. However, the amount of leakage current flowing through the test power supply terminal 902 inside the semiconductor integrated circuit is determined. Is provided, and a current measuring unit for outputting a signal of the result of determination to the outside is provided, and a determination is made based on the presence or absence of this signal. It should be noted that in a functional block or a set thereof incorporating tens of thousands to 10 million or more low threshold transistors, even if such an LSI is incorporated a little, the cost can be neglected.) Of course.

In this embodiment, the MOS transistors 9061 and 9062 are high threshold transistors, and the functional blocks 9041 and 9042 are low threshold transistors. Can be implemented in the same manner.

Although the present invention has been described based on some embodiments, it is needless to say that the present invention is not limited to the above embodiments. For example, the following may be performed. (1) In the first embodiment and the like, at least part of the high-threshold transistor and the conduction control transistor are, for example, a plurality of middle-threshold transistors connected in series for the sake of the standard and the conduction capacity. Connected. (2) In the third embodiment and the like, the ON fault and the OFF fault of the conduction control transistor are inspected.

(3) The threshold voltages of the high threshold transistor and the low threshold transistor are 1 at the time of filing of the present application.
The mainstream voltage is about 5 V, but it is, for example, about 0.1 V to 0.5 V as the technology advances. Accordingly, "sufficiently low voltage" in the embodiments and the like means "so that the P-side terminal is lower than the N-side terminal in consideration of the voltage drop in the wiring and the like". It is not limited to a specific numerical range. Further, the leak current value and the like are specifically described in, for example, the aforementioned IEICE Technical Report ICD93-10.
7 (1993-3), but of course the invention is not limited to these values.

[0074]

As described above, according to the present invention, the connection line between the power supply terminal of the high threshold transistor and the power supply terminal regardless of whether it is a shipment inspection in a factory or an inspection for repair at the request of the user. Inspection of a failure in which voltage cannot be supplied from the power supply terminal to the pseudo power supply line due to disconnection of the power supply line, disconnection of the connection line to the pseudo power supply line, failure of the control signal line, or the like can be easily performed.

In addition, it is possible to easily inspect for a failure in which a voltage is always supplied from a power supply terminal to a pseudo power supply line due to a short-circuit failure between a source and a drain of a high threshold transistor, a failure in a control line, and the like. . As a result, it is possible to reduce subsequent manufacturing defects of the product based on the data obtained from the data, and ultimately the manufacturing cost is reduced. Further, the required area on the integrated circuit can be reduced, and the manufacturing cost can be reduced in this respect as well.

Further, in the third and fourth embodiments, since an appropriate voltage is automatically applied to the function blocks not to be inspected by the diode, the leak current can be easily measured. In addition, there is little danger that the circuit is destroyed by the inspection voltage due to an erroneous ON / OFF operation of the energization control transistor of the function block not to be inspected.

[Brief description of the drawings]

FIG. 1 is a diagram (flowchart) showing a procedure of an inspection according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an inspection procedure in a second embodiment of the present invention.

FIG. 3 is a diagram showing a configuration of a semiconductor integrated circuit according to first and second embodiments of the present invention.

FIG. 4 is a diagram illustrating a configuration of a semiconductor integrated circuit according to a third embodiment of the present invention.

FIG. 5 is a diagram showing an inspection procedure according to a third embodiment of the present invention.

FIG. 6 is a diagram illustrating a configuration of a semiconductor integrated circuit according to a fourth embodiment of the present invention.

FIG. 7 is a diagram showing an inspection procedure according to a fourth embodiment of the present invention.

FIG. 8 is a diagram of an example of a conventionally proposed semiconductor integrated circuit.

FIG. 9 is a diagram of another example of a conventionally proposed semiconductor integrated circuit.

[Description of sign]

301, 302 Power supply terminals 303, 304 High-threshold transistors 305, 306 Pseudo power supply lines 805, 806 Same as above 307, 9041, 9042 Logic circuits 308, 309, 902 as functional blocks Power supply terminals for inspection 4011, 4012 Diode 6011 6012 Same as above 801 Higher power supply terminal 802 Lower power supply terminal 900 Control signal 901 Normal power supply terminal 903 Control circuit 9051, 9052 MOS transistor 9061, 9062 Same as above

Claims (6)

[Claims] A first terminal for supplying a high-potential-side voltage; a second terminal for supplying a low-potential-side voltage; and a first terminal and a second terminal. A functional block including a plurality of low-threshold transistors, and a first terminal and the functional block interposed between the first terminal and the functional block. A high-threshold transistor for switching the connection state between on and off, and a second terminal, interposed between the second terminal and the functional block, and switching between on and off to change the connection state between the second terminal and the functional block. At least one of the high-threshold transistors for switching on and off, and a first terminal corresponding to the high-threshold transistor if the high-threshold transistor is interposed. Alternatively, when the high-threshold transistor is not provided, the first terminal is connected to the second terminal.
Terminal or the second terminal and a total of two power supply lines connecting the functional block, at least one pseudo power supply line connecting the high-threshold transistor and the functional block, and a pseudo power supply line. A low-power semiconductor integrated circuit for leakage current, comprising at least one test terminal and control means for controlling switching of a high-threshold transistor on and off. An on control step of turning on the first terminal or the second terminal connected to the high threshold transistor controlled to be on after the on control step, and the corresponding inspection terminal An inspection step of measuring the resistance between the low power semiconductor integrated circuit and the leakage-resistant low-power semiconductor integrated circuit when the resistance value in the inspection step is a predetermined value or more. Inspection method of the leak-enabled low-power semiconductor integrated circuit, characterized in that determining and a transistor judging step the high threshold transistor being controlled as defective. 2. A first terminal for supplying a high-potential-side voltage, a second terminal for supplying a low-potential-side voltage, and driven by power from the first terminal and the second terminal. A functional block including a plurality of low-threshold transistors, and a first terminal and the functional block interposed between the first terminal and the functional block. A high-threshold transistor for switching the connection state between on and off, and a second terminal, interposed between the second terminal and the functional block, and switching between on and off to change the connection state between the second terminal and the functional block. At least one of the high-threshold transistors for switching on and off, and a first terminal corresponding to the high-threshold transistor if the high-threshold transistor is interposed. Alternatively, when the high-threshold transistor is not provided, the first terminal is connected to the second terminal.
Terminal or the second terminal and a total of two power supply lines connecting the functional block, at least one pseudo power supply line connecting the high-threshold transistor and the functional block, and a pseudo power supply line. A low-power semiconductor integrated circuit for leakage current, comprising at least one test terminal and control means for controlling switching of a high-threshold transistor on and off. An off-control step of turning off at least one of the high-threshold transistors if there are two, and connecting to the high-threshold transistor that has been turned off after the off-control step A potential applying step of applying different potentials to the first terminal or the second terminal, and the corresponding inspection terminal, A leak current measuring step of measuring a leak current between the first terminal or the second terminal provided with the position and the inspection terminal; and a case where a measured value in the leak current measuring step is a predetermined value or more. A function block determining step of determining a high-threshold transistor, which is controlled to be off, of the leak-response type low-power semiconductor integrated circuit to be defective. Circuit inspection method. 3. A function block set including a function block and a pseudo power supply line for supplying a high-potential side or a low-potential side power supply to the function block, and a function block to be inspected is designated among the plurality of function blocks. An inspection target designating means for outputting a signal for performing the test, an inspection power supply terminal for supplying power to a pseudo power supply line of a functional block to be inspected designated by the inspection target designation means, A normal power supply terminal for supplying power to the pseudo power supply line of the unspecified functional block; and a normal power supply terminal interposed between the normal power supply terminal and each of the pseudo power supply lines. Those connected to the pseudo power supply line of the functional block specified as the inspection target are controlled to be turned off, and those connected to the pseudo power supply line of the functional block not specified as the inspection target are turned off. The following are controlled to be turned on, and are provided in a direction in which power is supplied between the inspection power supply terminal and each of the pseudo power supply lines, and a conduction control transistor provided for each functional block set. And a diode provided for each functional block set. 4. A plurality of functional block sets each including a functional block and a pseudo power supply line for supplying a high-potential side or a low-potential side power to the functional block; Inspection target designating means for outputting a signal for designating the test object, an inspection power supply terminal for supplying power to a pseudo power supply line of a functional block to be inspected designated by the inspection object designation means, and an inspection to the inspection object designation means A normal power supply terminal for supplying power to the pseudo power supply line of the functional block not specified as a target, and a normal power supply terminal interposed between the normal power supply terminal and each of the pseudo power supply lines. Those connected to the pseudo power supply line of the functional block specified as the inspection target are controlled to be turned off, and connected to the pseudo power supply line of the functional block not specified as the inspection target. The power supply is controlled to be on, and a conduction control transistor provided for each functional block set, a test power supply terminal and each of the pseudo power supply lines are provided in a direction in which power is supplied, and each function is provided. A method for testing a leak-response type low-power semiconductor integrated circuit having a diode provided for each block set, wherein the function block designated as the test target is provided in the function block set. An inspection power supply step of controlling the energization control transistor to turn off and supplying power from the inspection power supply terminal to the pseudo power supply line of the corresponding function block via the diode, and to a function block not designated as an inspection target. Controls the energization control transistor to be turned on in response to a designation signal from the inspection target designation means, and simulates a corresponding functional block. A normal power supply step of supplying power to the power supply line from the normal power supply terminal, and the inspection power supply terminal is connected to the normal power supply terminal according to whether the diode is interposed on the high potential side or the low potential side of the functional block. A constant voltage supply step of providing a high or low voltage that does not generate a current flowing through a diode connected to a pseudo power supply line other than the function block to be inspected, and the constant voltage supply step. A leak current amount measuring step of measuring a leak current amount of the inspection power supply terminal during the operation, a comparing step of comparing a measured value of the leak current amount measuring step with a predetermined value, and a result of the comparing step. When the value is equal to or more than a predetermined value, the function block to be inspected is determined to be defective. Inspection method of the leak-compatible low current semiconductor integrated circuit according to claim Rukoto. 5. A function block set including a function block and a pseudo power supply line for supplying a high-potential side or a low-potential side power supply to the function block, and a function block to be inspected is designated among the plurality of function blocks. An inspection target designating means for outputting a signal for performing the test, an inspection power supply terminal for supplying power to a pseudo power supply line of a functional block to be inspected designated by the inspection target designation means, A normal power supply terminal for supplying power to the pseudo power supply line of the unspecified functional block; and a power supply terminal interposed between the test power supply terminal and each of the pseudo power supply lines, depending on the presence / absence of a specification signal from the test target specification means. Those connected to the pseudo power supply line of the functional block specified as the inspection target are controlled to be turned on, and those connected to the pseudo power supply line of the function block not specified as the inspection target are turned on. The following components are controlled to be turned off, and a conduction control transistor provided for each functional block set, and a power supply direction interposed between the normal power supply terminal and each of the pseudo power supply lines. And a diode provided for each functional block set. 6. A plurality of functional block sets each composed of a functional block and a pseudo power supply line for supplying a high-potential side or a low-potential side power supply to the functional block, and a function block in the plurality of functional block sets to be inspected. Inspection target designating means for outputting a signal for designating the test object, an inspection power supply terminal for supplying power to a pseudo power supply line of a functional block to be inspected designated by the inspection object designation means, and an inspection to the inspection object designation means A normal power supply terminal for supplying power to a pseudo power supply line of a functional block not specified as a target, and a test power supply terminal interposed between the pseudo power supply line and each of the pseudo power supply lines. Those connected to the pseudo power supply line of the functional block specified as the target are turned on,
Those connected to the pseudo power supply lines of the functional blocks not specified as the inspection target are controlled to be turned off, and a conduction control transistor provided for each functional block set,
Inspection of a leak-response type low-power semiconductor integrated circuit having a diode interposed between a normal power supply terminal and each pseudo power supply line in a power supply direction and provided for each functional block set. A method, wherein a power supply is supplied from the inspection power supply terminal by controlling the energization control transistor to be turned on to a pseudo power supply line of a functional block designated as the inspection object by a designation signal signal from the inspection object designation means. A normal power supply step of supplying power from the normal power supply terminal via the diode to the pseudo power supply line of a functional block not designated as a test target; and a high potential side of the functional block. Or, depending on which of the low potential side the transistor is interposed, the inspection power supply terminal is compared with the normal power supply terminal, A constant voltage supply step of providing a high or low voltage that does not generate a current flowing through a diode connected to a pseudo power supply line other than the function block to be inspected; and the inspection power supply during the constant voltage supply step A leak current amount measuring step of measuring a leak current amount of a terminal; a comparing step of comparing a measured value of the leak current amount measuring step with a predetermined value; and a result of the comparing step, the measured value is equal to or more than a predetermined value. And a determining step of determining that the functional block to be inspected is defective.