SU410340A1 - - Google Patents

Description

one

The invention relates to electronic engineering and can be used to control the parameters of semiconductor devices during their manufacture.

Devices for measuring the minimum base thickness of transistors are known, comprising an emitter-base blocking source, a collector-base blocking voltage source, a high frequency generator, and an indicator used to record the time when a high frequency voltage appears in the collector circuit.

The disadvantages of the known devices are as follows;

the limited measurement range of the minimum base thickness, due to the fact that in transistors with a thick base, electrical breakdown occurs earlier than closure;

low measurement accuracy due to the dependence of the time of fixation of the puncture on the area of the defect;

low measurement speed due to the need for additional calculations.

The aim of the invention is to improve measurement accuracy. The goal is achieved by the fact that the proposed device contains a delay circuit, the input of which is connected to the output of the comparison circuit, and the output with a pulse counter and an OR circuit. The second input of the OR circuit is connected to the output of the starting pulse generator, the second output of which is connected via a generator of linearly varying voltage to the comparison circuit. The second input of the comparison circuit through the generator

current pulses connected to the circuit "OR

The drawing is a block diagram of the proposed device.

The device contains an OR 1 logic circuit, a pulse counter 2, a delay circuit 3, a current pulse generator 4, a starting impulse generator 5, a linearly varying generator 6, a comparison circuit 7.

The signal "Start from one of the outputs of the starting pulse generator 5 is fed through the logic circuit" OR 1 to the current pulse generator 4, and from the other output to the linearly varying nanometer generator 6. Current pulse from the generator 4, passage through the emitter-collector circuit the test transistor creates a voltage drop, the amplitude of which is proportional to the minimum base thickness. This voltage and the linearly varying voltage from the generator 6

is fed to the inputs of the comparison circuit 7. If the amplitude of the voltage taken from the transistor increases to the amplitude of the linearly varying voltage, the comparison circuit 7 generates a pulse that is delayed by the delay circuit 3 n is fed to the input of the counter 2

and to one of the inputs of the logic circuit OR 1. A pulse from the output of the logic circuit OR 1 is detonated by the current pulse generator 4, and the measurement cycle is repeated.

If the linearly varying voltage exceeds the amplitude of the voltage drop across the test transistor, the comparison circuit 7 does not generate an output pulse, and the process stops.

Since the pulse delay time is proportional to the amplitude increment of the linearly varying voltage, the number of pulses in the counter is equal to the minimum base thickness. To reset the display of counter 2, a "Reset" signal is applied, which prepares the device for the next measurement.

Subject invention

A device for measuring the minimum transistor base thickness, which contains an impulse counter, a starting pulse generator, a current pulse geerator and an OR circuit, characterized in that, in order to improve measurement accuracy, it contains a delay circuit

is connected to the output of the comparison circuit, and the output is connected to the counter and the OR circuit, the second input of which is connected to the output of the starting impulse generator, the second output of which through a linearly varying generator

the voltage is connected to the comparison circuit, the second input of the comparison circuit is connected to the OR circuit via the pulse current generator.