JPH0611538A - Burn-in system of integrated circuit - Google Patents

Abstract

PURPOSE:To obtain an improved system for performing an improved current switch operation of an ECL in a burn-in system of an integrated circuit including the ECL. CONSTITUTION:A reference base voltage VBB of a reference voltage side transistor TR21 of an ECL current switch part is varied periodically between levels larger and smaller than a logic amplitude by an oscillation circuit on burn-in in addition of application of prescribed voltages to a collector power supply VCC and emitter power supplies VEE1-2 on normal operation. Switching operation is made regardless of input by changing the reference base voltage of the ECL above the logic amplitude, thus reducing a test pattern for operating an integrated circuit. Also, the reference base voltage can be changed, thus entirely operating the ECL inside the integrated circuit and performing an improved burn-in.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a burn-in system for an integrated circuit which applies thermal stress to an integrated circuit including an emitter-coupled logic circuit (hereinafter abbreviated as ECL).

[0002]

2. Description of the Prior Art Generally, prior to the use of integrated circuits,
A test is performed to remove the initial failure of the integrated circuit.
In that case, in order to shorten the test time, there is a burn-in acceleration test in which the integrated circuit is operated in a high temperature environment in which a thermal stress is applied.

FIG. 4 is a block diagram of the burn-in test apparatus. In FIG. 4, 1 is a semiconductor integrated circuit, 2 is a burn-in test substrate on which the semiconductor integrated circuit 1 is mounted, and 3 is a signal generator for inputting a test signal to the semiconductor integrated circuit 1. In the burn-in environment,
After applying the test signal generated by the signal generator 3 to the semiconductor integrated circuit 1 for a predetermined time, an operation test of the semiconductor integrated circuit 1 is performed to remove defects. Therefore, the more the internal circuit of the semiconductor integrated circuit operates, the better the test accuracy becomes.

In such a burn-in method, as shown in FIG.
An apparatus as shown in FIG.
Has been proposed to. In FIG. 3, 1 is a semiconductor integrated circuit, 2 is a burn-in test substrate, 3 is a signal generator, 4
Is an input terminal for a switching selection signal for switching and selecting a test operation and an actual operation, 5 is an input buffer, 6 is an internal logic circuit, 7 is an input terminal, and 8 is an output terminal. During the burn-in test, the output signal of the internal logic circuit is fed back to the internal logic circuit as a test input signal, and a new logic output signal is output. Since the output signal becomes a new input signal, the number of test signals to be generated is reduced, and since it becomes a random test signal, the test accuracy becomes good.

[0005]

FIG. 2 shows a basic configuration diagram of ECL. In FIG. 2, transistors TR11-1
2 (hereinafter abbreviated as TR11 to 12) is an input transistor,
A transistor TR21 (hereinafter abbreviated as TR21) is a reference voltage transistor, R11 and R21 are resistors, VCC is a common collector power supply, VEE1 is an emitter power supply having a constant current characteristic, and VBB is a reference base power supply and constitutes a current switch unit. . In addition, the output transistors TR13 and TR2
2 (hereinafter abbreviated as TR13, TR22), resistors R12, R
22 (hereinafter abbreviated as R12 and R22) and emitter power supply V
The output is taken out from the emitter follower composed of EE2.

Inputs A and B are supplied to the bases of TR11 to 12, respectively, and a reference base voltage is supplied from VBB to the base of TR21. When either input A or B is on, TR11 or TR12 is on and TR22 is off. TR11 when inputs A and B are both off
And TR12 are both off, and TR22 is on.

In order to satisfactorily burn-in an integrated circuit including the above ECL, it is necessary to apply a test pattern to the integrated circuit so that the current switch section performs a switching operation. However, integrated circuits such as LSI and VLSI are required. In this case, the number of circuits and the circuit operating states are enormous, and the test patterns are enormous. For this reason, there is a problem in that there is a portion that does not perform switching operation in a random number pattern.

The present invention eliminates the need for using various test patterns for switching the ECL current switch section.
It is an object of the present invention to provide a burn-in system that enables good burn-in by switching the current switch units of all ECLs.

[0009]

In the present invention, it is possible to change the reference base voltage of the reference voltage side transistor TR22 of the current switch portion in FIG. 2 to be larger than the logical amplitude, and to make the voltage higher than the logical amplitude during the burn-in. The voltage is alternately changed to a low voltage for current switching.

[0010]

When the burn-in is performed, the collector power supply VCC,
The emitter power supply VEE1 and the reference voltage VBB are respectively applied to the integrated circuit. At this time, the on / off state of the input side transistor and the reference voltage side transistor is determined by the input of the input side transistor of the current switch unit and the reference base voltage of the reference voltage side transistor. When the reference base voltage is higher than the input, the reference voltage side transistor is turned on and the input side transistor is turned off. If the reference base voltage is lower than the input, the reference voltage side transistor is turned off and the input side transistor is turned on.

In the present invention, since the reference base voltage is changed to a voltage value larger than the logic amplitude and a voltage value smaller than the logic amplitude, all ECLs perform the current switch operation regardless of the input pattern.

As described above, by changing the reference base voltage of the transistor on the reference voltage side of the current switch unit to a value larger than the logical amplitude, it is not necessary to create various test patterns for switching the current switch unit, and It is possible to perform current switch operation for all ECLs, and good burn-in can be performed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. In FIG. 1, TR11 to 12 are input side transistors, TR21 is a reference voltage side transistor, and R11 to 21.
Is a resistor, VEE1 and VEE2 are emitter power supplies, and VCC is a collector power supply. The reference base power supply is an oscillating circuit because it changes periodically during burn-in. Further, the output transistors TR13 and TR22 and the resistors R12 and R22 form an emitter follower circuit for output.

In normal times, the emitter power supplies VEE1 to VEE
2. A specified voltage value is applied to the collector power supply VCC, the inputs A and B, and the reference base power supply VBB, and the on / off state of the input side transistor and the reference voltage side transistor is determined by the input voltage and the reference base voltage at this time. It

During burn-in, in addition to the applied voltage at the normal time,
Periodically, the reference base power supply VBB is alternately changed to a voltage value larger and a voltage value smaller than the logical amplitude. As a result, the current is switched alternately regardless of the input, so that it is not necessary to create various test patterns, and the switching operation is performed for all ECLs. In this embodiment, the reference base power source VB
Although B is an oscillating circuit, it suffices that it is possible to control that the voltage value is periodically changed, and the application of the voltage may be external or internal.

[0016]

As described above, according to the present invention, ECL
By changing the reference base power source of the reference voltage side transistor in the current switch section of the
Since there is no need to create various test patterns for switching the L current switch units, and the current switch units of all ECLs can be switched, good burn-in can be performed.

[Brief description of drawings]

FIG. 1 is a diagram showing an embodiment of the present invention.

FIG. 2 is a basic configuration diagram of ECL.

FIG. 3 is a block diagram of a conventional burn-in test apparatus with a reduced number of test patterns.

FIG. 4 is a block diagram showing a conventional burn-in test apparatus.

[Explanation of symbols]

 TR11 to 13, TR21 to 22 ... Transistor, R11 to 12, R21 to 22 ... Resistor, VEE1 to VEE2 ... Emitter power supply, VCC ... Collector power supply, VBB ... Reference base power supply 1 ... Semiconductor integrated circuit, 2 ... Burn-in substrate, 3 ... pattern generation circuit, 4 ... switching terminal, 5 ... input buffer, 6 ... internal logic circuit, 7 ... input terminal, 8 ... output terminal.

Claims (1)

[Claims] 1. A burn-in system for an integrated circuit including an emitter-coupled logic circuit ECL, wherein a reference base voltage of a transistor on a reference voltage side of transistors constituting a current switch section of the emitter-coupled logic circuit ECL is higher than a logic amplitude. A burn-in method for an integrated circuit, wherein current switching of a current switch unit of an emitter-coupled logic circuit ECL is performed by changing the value to a low voltage value.