JPS628750B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for measuring the electrical characteristics of a semiconductor integrated circuit device using a capacitor as an external element, and particularly aims to provide a measuring method that is effective in reducing time.

Conventionally, when a large-capacity capacitor is connected as an external element to a semiconductor integrated circuit device, or when the internal impedance of the terminal to which the capacitor is connected is large, the capacitor is charged.
Since it takes a long time to reach a steady state and then measurement is started, this time loss is extremely large when testing the characteristics of a semiconductor integrated circuit device.

FIG. 1 is a circuit connection diagram showing an example of measuring the electrical characteristics of a semiconductor integrated circuit device using a conventional method. The potential V at the connection point A between the capacitor C f and the capacitor C _f changes as shown in FIG. To represents the power-on time.
In this case, if the capacitance of capacitor C _f is very large and the internal impedance seen from terminal -2 of semiconductor integrated circuit device DUT is large, the time required for the potential at point A to reach V ₁ shown in Figure 2 is T ₁
becomes very long, and that time is the capacitor C _f
and is proportional to the internal impedance of terminal 2. Characteristics are measured by turning on the power supply voltage and measuring the time (T ₁ -
T ₀ ), that is, after the circuit reaches a steady state, the time required for measurement is longer, but especially in semiconductor integrated circuits for low frequency amplification, C _f is set to a large value, for example, 100 μF. Therefore, the time (T ₁ -T ₀ ) proportional to R _f C _f is several seconds long, and this time is accumulated when a large number of tests are performed, resulting in an extremely large time loss.

It is an object of the present invention to provide a method for measuring the electrical characteristics of a semiconductor integrated circuit device having an external capacitor that eliminates such drawbacks and can quickly charge the external capacitor and reduce time loss until the start of measurement. shall be.

According to the present invention, in a method for measuring the electrical characteristics of a semiconductor integrated circuit device using an externally attached capacitor, the terminal to which the capacitor of the semiconductor integrated circuit device under test is externally attached is first detected to cause abnormal behavior such as oscillation when the power is turned on. The first capacitor is connected to a first capacitor having a small capacity sufficient to prevent the above, and the charging potential of the first capacitor is transmitted to a second capacitor having a regular capacity via a current amplifier with a voltage gain of 1. A method for measuring electrical characteristics of a semiconductor integrated circuit device using an external capacitor, characterized in that the charging potential of the second capacitor reaches a predetermined value, and then switching to the second capacitor and starting measurement. is obtained.

Next, the present invention will be explained according to examples and with reference to the drawings.

FIG. 3 is a circuit connection diagram for explaining one embodiment of the present invention. Initially, terminal 2 of the DUT (terminal to which a capacitor is externally connected) is connected to a capacitor _C1 via a switch S. The capacitance of capacitor _C1 is
Select the minimum value required to prevent DUT oscillation and ensure stable operation, for example, several tens of picofurads. Since C ₁ has such a small capacity, the potential at point A quickly rises and reaches the steady-state value V ₁ by charging after power is turned on. The potential at point A is transmitted via the voltage follower 6 to one end of a large-capacity capacitor C _f whose other end is grounded, and quickly charges the capacitor C _f . The potential of C _f rises rapidly following the potential of C ₁ , and its speed is proportional to the current amplification factor of the voltage follower 6 . FIGS. 4a and 4b are curves showing changes in the charging potential of capacitors C ₁ and C _f, respectively, and T ₁ ′ and T ₁ ″ are the times at which the steady potential V ₁ is reached, respectively. The terminal voltage of the DUT, that is, V ₁ C ₁
Since this method detects the potential of C f and charges C _f , the potential can be determined depending on each DUT.

Measurement of electrical characteristics using this circuit can be started immediately by switching point A to the capacitor C _f side using switch S immediately after the potentials of C ₁ and C _f both reach steady potentials. For example, the voltage generated when the power is turned on.
Vcc' is applied to the base of the transistor 8 through the delay circuit 7, and this is made conductive to make the relay coil 9
What is necessary is to apply a current to the switch S and switch the switch S. It is assumed that the terminal 10 is connected to a relay power source (not shown). The delay time of the delay circuit need not be smaller than (T ₁ ″−T ₀ ).
Alternatively, the switch S uses a semiconductor switch,
It goes without saying that the switching may be performed by detecting that the potential of C _f has reached a predetermined value.

As explained in detail above, according to the present invention, the waiting time (conventionally (T ₁
- T ₀ ), the present invention can make (T ₁ ″-T ₀ )) extremely short ((T ₁ - T ₀ )≫(T ₁ ″-T ₀ )), which reduces the measurement time of semiconductor integrated circuit devices. This has the effect of eliminating waste and saving time.

[Brief explanation of the drawing]

Figure 1 is a circuit connection diagram for explaining a method for measuring the electrical characteristics of a semiconductor integrated circuit device that uses a conventional capacitor as an external element, and Figure 2 is a temporal change in the potential at point A in Figure 1. 3 is a circuit connection diagram for explaining the measurement method of the present invention,
FIGS. 4a and 4b are curve diagrams showing temporal changes in the charging potential of the capacitors C ₁ and C _f of FIG. 3, respectively. IN...Signal input terminal, Esig...Test signal, DUT...Semiconductor integrated circuit device under test, _C0 , _C1 , _Cf ...Capacitor, S...Switch, Vcc...Power supply voltage, OUT...
DUT output terminal, 1, 2, 3, 4, 5...Symbols indicating DUT terminals, 6...Voltage follower, 7...Delay circuit, 8...Transistor, 9...Coil, 10...Relay power supply terminal.

Claims (1)

[Claims] 1 In a method for measuring the electrical characteristics of a semiconductor integrated circuit device that uses an external capacitor, the terminal to which the capacitor of the semiconductor integrated circuit device under test is externally connected must first be connected to the terminal to prevent abnormal operation and ensure stable operation of the device when the power is turned on. the charging potential of the first capacitor is transmitted to a second capacitor of normal capacity via a current amplifier with a voltage gain of 1; 1. A method for measuring electrical characteristics of a semiconductor integrated circuit device using an external capacitor, characterized in that measurement is started by switching to the second capacitor after the charging potential of the capacitor reaches a predetermined value.