JPH11133101A - Stationary power supply current test circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately measure the abnormal current value of a power supply current caused by the defect of an internal circuit by dividedly measuring the stationary power supply current test. SOLUTION: This test circuit is provided with small-scale CMOS circuits 1-3 using low-threshold value voltage transistors, switches 4-5 using high- threshold value voltage transistors inserted between the power supply terminals and GND of the CMOS circuits 1-3, pull-down circuits 7 fixing the CMOS inputs of the small-scale circuits 1-3, and a selector 10 selecting the small-scale circuit measuring a stationary power supply current. Large-scale CMOS circuits can be divided to measure the stationary power supply current, thereby the effect of the leakage current of the low-threshold value voltage transistors can be minimized. The measurement of the stationary power supply current which has been difficult by conventional low-voltage, large-scale CMOS circuits using the low-threshold value voltage transistors is made feasible, and good product/ defective products can be judged by a stationary power supply current test in a shipping inspection.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a test circuit for a semiconductor device.

[0002]

2. Description of the Related Art FIG. 2 shows a configuration diagram of a conventional static power supply current measuring circuit of a semiconductor device. 11 is a power supply terminal of the CMOS circuit, 17 is a power supply current of the CMOS circuit, 15 is an input signal to the CMOS circuit, and 14 is a large-scale CMOS circuit using low threshold voltage transistors. In the conventional measurement of the quiescent power supply current, the internal state of the CMOS
And the static power supply current 1 flowing through the power supply terminal 11
7 was measured.

[0003]

In recent years, the degree of integration of semiconductor devices has been increased, and it has become possible to realize an entire system conventionally constituted by a plurality of semiconductor devices with one semiconductor device. For this reason, the size and complexity of semiconductor devices have been rapidly increasing. As described above, as the size of the semiconductor device increases, it becomes difficult to control the internal circuit of the semiconductor device and create a test pattern for detecting all failures inside the semiconductor device. However, the failure detection rate in shipping inspection of semiconductor devices and the market failure rate are closely related, and in order to guarantee the quality of semiconductor devices, the failure detection rate is improved even if a lot of man-hours are required. It is the current situation.

As a means for effectively improving the failure detection rate, there is a method called a static power supply current test for measuring a power supply current when the semiconductor device is at rest, in addition to a function test using a test pattern. Since the power supply terminal of the semiconductor device is connected to all internal circuits, the state of the internal circuit can be determined by measuring the power supply current flowing through the power supply terminal. The quiescent power supply current test will be described with reference to FIG. First, an input signal 15 for changing the state of the internal circuit is input to the input of the CMOS circuit. If there is no defect 18 in the internal circuit, the power supply current 17 (a) without defect
Flows in the CMOS circuit only during operation and has a leakage current value 20 of several uA or less at rest. Here, when the defect 18 exists in the internal circuit, the power supply current 17 at the measurement point 19 is determined.
(b) is an abnormally large abnormal current value 21 according to the failure mode.
Becomes By making a pass / fail decision based on the good / defective product selection current value 22, good / defective products can be selected in the shipping inspection. Comparing the function test and the quiescent power supply current test, the function test needs to prepare a pattern 23 for controlling the internal state, a pattern 24 for transmitting the internal state to the outside, and a pattern 25 for determining the expected value. The current test can be performed by preparing a pattern 23 for controlling the internal state. For this reason, since relatively few man-hours are required to realize a highly completed inspection, it is possible to shorten the development period of the semiconductor device, reduce costs and improve quality.

[0005] However, in recent semiconductor devices, the voltage has been reduced for the purpose of lowering the power consumption, and the mainstream current 3.3 V is used.
It is rapidly changing from driving to 2.5V driving and further to 1.8V driving. The problem here is a decrease in the threshold voltage of the CMOS transistor due to the lowering of the voltage. It has been found that when the threshold voltage decreases, the leakage current flowing when the CMOS circuit is at rest increases, which causes a problem that it is becoming difficult to measure the quiescent power supply current in a large-scale circuit.

The difficulty of a static power supply current test in a large-scale semiconductor device using low threshold voltage transistors will be described with reference to FIG. FIG. 4A shows a power supply current in a small-scale semiconductor device using a high threshold voltage transistor. In this case, the leakage current value 20 at the measurement point 19 in the circuit having no defect is 1 uA or less, and the abnormal current value 21 when the circuit has a defect is several tens times or more of the leakage current value 20. The non-defective / defective product selection can be accurately performed with the / defective product selection current value 22. The reason why the non-defective / defective product selection current value 22 has a width is in consideration of the measurement variation of the measuring device. FIG. 4B shows a power supply current in a small-scale semiconductor device using a low threshold voltage transistor. In this case, the measurement point 19 in the circuit without defects
Although the leakage current value 20 increases to about a few uA, the abnormal current value 21 when there is a defect in the circuit is about the same, so that the ratio to the leakage current value 20 becomes relatively several times.
For this reason, although it is more difficult to make a determination than a semiconductor device using a high threshold voltage transistor, it is possible to perform a non-defective / defective product selection using the non-defective / defective product selection current value 22.
However, in the case of the power supply current in a large-scale semiconductor device using the low threshold voltage transistor shown in FIG. 4C, the number of transistors that generate a leakage current value of 20 increases significantly, so that even a circuit without defects can be used. The leakage current value 20 is several tens uA or more. In this case, even if there are one or two defects in the circuit, the abnormal current value 21 does not greatly differ from the leakage current value 20, so that the non-defective / defective product is selected based on the non-defective / defective product current value 22. Becomes difficult.

SUMMARY OF THE INVENTION An object of the present invention is to provide a static power supply current test circuit capable of performing a static power supply current test even with a low-voltage and large-scale semiconductor device.

[0008]

A quiescent power supply current test circuit according to claim 1 is a small scale CMOS circuit using a low threshold voltage transistor, and a high threshold voltage transistor inserted into a power supply and GND of the CMOS circuit. Switch and
An input fixing circuit for fixing the CMOS input of the small-scale circuit;
It is provided with a selector for selecting a small-scale circuit for measuring a quiescent power supply current.

According to the quiescent power supply current test facilitation circuit of the present invention, since the quiescent power supply current test can be divided and measured, the abnormal current value of the power supply current due to a defect in the internal circuit can be measured accurately. Compared with the conventional semiconductor device, the quality of the product is improved due to the improvement of the fault detection capability, and the inspection design does not require much man-hour, so that the development period of the semiconductor device can be shortened.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is shown in FIG.
This will be described below. FIG. 1 is a configuration diagram of a circuit for facilitating the test of a static power supply current of a semiconductor device according to an embodiment of the present invention. 1-3 are small-scale CMOS circuits using low threshold voltage transistors, 4 (a)-(c) are switches using high threshold voltage transistors inserted in the power supply of the CMOS circuit, and 5 (a)-(c). ) Are switches by high threshold voltage transistors inserted in the GND of the CMOS circuit, and 6 (a) to 6 (c) are switches 4 (a) to 4 by high threshold voltage transistors.
(c), control circuits for controlling 5 (a) to (c); 7 (a) to (c), input fixing circuits for fixing CMOS inputs of small-scale circuits;
Is a selector for selecting a small-scale circuit for measuring a static power supply current, 8 (a) to 8 (c) are outputs of the selector 10, and 11 is a CMOS.
A power supply terminal of the circuit, 12 is a test mode terminal for setting a quiescent power supply current measurement mode, 13 is a normal mode terminal for controlling power consumption in a normal operation state, and 9 is a truth table showing an operation of the control circuit 6.

The semiconductor device using the quiescent power supply current test circuit of the present embodiment operates as a large-scale circuit in the actual use mode, and is divided into small-scale circuits in the quiescent power supply current test mode for performing the quiescent power supply current test. Test. The operation in the static power supply current test mode and in the actual use mode will be described with reference to FIG.

First, the operation in the static power supply current test mode will be described. The quiescent power supply current test divided into small-scale circuits is performed as follows. First, the test mode terminal 12 for static power supply current test is fixed at H. When the test mode terminal 12 is set to the H state, the quiescent power supply current test mode is set. As shown in the truth table 9, the output 8 of the selector 10 can control the switch 4 and the switch 5 by the high threshold voltage transistor. . At this time, since the normal mode terminal 13 does not affect the quiescent power supply current test operation, it may be fixed to H or L. In such a static power supply current test mode, the selector output A8 (a) is set to H, the transistor switches A4 (a) and a5 (a) are turned on, and the small-scale circuit A1 is selected. At this time, the small-scale circuits B2 and B3 output the selector output B8 (b) and the selector output C8
By fixing (c) to L, the power supply and GND are controlled by the switches B4 (b) and b5 (b) and the switches C4 (c) and c5 (c) using the high threshold voltage transistors.
Disconnected from At this time, the input of the small-scale circuit A1 is fixed by the input fixing circuit A7 (a).
The internal state of No. 1 is in a stationary state. This internal state can be fixed to various stationary states. In this state, the static power supply current of the power supply terminal 11 is measured, and the small-scale circuit A1 is measured.
It is determined whether or not an abnormal current has occurred due to a defect in the internal circuit. Next, the output B8 (b) of the selector 10 is set to H, the transistor switch B4 (b) and the transistor switch b5 (b) are turned on, and the small-scale circuit B2 is selected. As in the case of the small-scale circuit B2, the static power supply current of the power supply terminal 11 is measured to determine whether or not an abnormal current has occurred due to a defect in the internal circuit of the small-scale circuit B2. In this way, small-scale circuits are sequentially selected, and the static power supply current is individually measured.

Next, the operation in the actual use mode will be described. In the semiconductor device using the quiescent power supply current test circuit of the present embodiment, the power consumption in the actual use mode can be reduced by controlling the normal mode terminal 13. In the actual use mode in which the test mode terminal 12 for the quiescent power supply current test is fixed at L, by setting the normal mode terminal 13 to H as shown in the truth table 9, all the low threshold voltage transistors are used. Switch 4 using a high threshold voltage transistor having the CMOS circuits 1 to 3 inserted in the power supply terminal of the CMOS circuit.
And a power supply terminal 11 and a GND by a switch 5 using a high threshold voltage transistor inserted into the GND of a CMOS circuit.
To operate as one large-scale circuit. At this time, since the selector output 8 does not affect the operation in the actual use mode, it may be fixed to H or L. In this state, the normal operation in the actual use mode is performed. Here, when it is not necessary to operate the circuit as in the standby state in the actual use mode and it is desired to reduce power consumption as much as possible, as shown in the truth table 9, the test mode terminal 12 for the quiescent power supply current test is set to L level. By setting the normal mode terminal 13 to L in the actual use mode state fixed to, the CMOS circuits 1 to 3 using all the low threshold voltage transistors are inserted into the power supply terminals of the CMOS circuit. The power supply terminal 11 and the GND can be separated by a switch 4 formed by a value voltage transistor and a switch 5 formed by a high threshold voltage transistor inserted in the GND of the CMOS circuit, thereby reducing power consumption.

[0014]

According to the quiescent power supply current test circuit of the present invention, since the large-scale CMOS circuit is divided so that the quiescent power supply current can be measured, the leakage current of the low threshold voltage transistor is reduced. The minimum power supply current, which is difficult for low-voltage, large-scale CMOS circuits using conventional low-threshold-voltage transistors. / Defective products can be determined.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a quiescent power supply current test circuit according to an embodiment of the present invention;

FIG. 2 is a configuration diagram of a conventional static power supply current measuring circuit of a semiconductor device.

FIG. 3 is an explanatory diagram showing a determination method of a static power supply current test.

FIG. 4 is an explanatory diagram of a quiescent power supply current test in a large-scale semiconductor device using a low threshold voltage transistor;

[Explanation of symbols]

 1 Small-scale circuit A with low threshold voltage transistor 2 Small-scale circuit B with low threshold voltage transistor 3 Small-scale circuit C with low threshold voltage transistor 4 (a) Switch A 4 with high threshold voltage transistor (b) High threshold voltage transistor switch B 4 (c) High threshold voltage transistor switch C 5 (a) High threshold voltage transistor switch a 5 (b) High threshold voltage transistor switch b 5 (c) Switch c 6 (a) using high threshold voltage transistor Control circuit A 6 (b) Control circuit B 6 (c) Control circuit C 7 (a) Input fixed circuit A 7 (b) Input fixed circuit B 7 (c) Input fixed circuit C 8 (a) Selector output A 8 (b) Selector output B 8 (c) Selector output C 9 Truth table of control circuit 6 10 Selector 11 Power supply terminal 12 Test mode terminal 13 No Multi-mode terminal 14 Large-scale circuit with low threshold voltage transistor 15 Input signal 16 Output signal 17 Power supply current 18 Defect 19 Measurement point 20 Leakage current value 21 Abnormal current value 22 Non-defective / defective product selection current value 23 Controls internal state Pattern 24 Pattern for transmitting the internal state to the outside 25 Pattern for performing expected value judgment

Claims (1)

[Claims] 1. A small-scale CMOS circuit using a low threshold voltage transistor, and a power supply and a GND of the CMOS circuit.
, A switch for fixing the input of the CMOS circuit, a selector for selecting the CMOS circuit for measuring the quiescent power supply current, and a test for setting the quiescent power supply current measurement mode A quiescent power supply current test circuit including a mode terminal and a normal mode terminal for controlling power consumption in a normal operation state.