SU655996A1 - Arrangement for measuring mds-structure hysteresis characterictics - Google Patents

Description

I

The ognosigs image is applied to the semiconductor unit and can be used to control the quality and measure the parameters of MIS structures.

At present, the C-V (capacitive voltage) meters are used for controlling MISs (megallelectric-semiconductor).

The avomagic karakteriograf of the C-V characteristics is known, consisting of a generator and amplifier of a sinusoidal and meririgal signal with a frequency of 1 MHz iJ. To measure the capacitance, the R C divider method, i.e., the measurement of a gok flowing through a resistor, is used. Automatic synchronization, scanning and viewing of C-Characteristics are provided by using the oscillator voltage generator itself as a sweep generator, and the X and Y channels of the oscilloscope are used to register BE signals C, respectively.

With the help of a known device, it is possible to control the characteristics only from the oscilloscope screen, which limits the possibilities of using the device and reduces the accuracy of measurements.

It is also known a device for monitoring characteristic MIS structures, comprising a Hess signal generator, an amplifier, a sawtooth voltage generator, a synchronizer, threshold devices and a voltage difference indicator G21.

In case of cyclic variation of the bias voltage, the C-V characteristics obtained on the forward and reverse raververt steps do not coincide. This hysteresis of the C-V characteristics is one of the most important parameters to be measured, and this device allows you to control this parameter with limited accuracy.

The goal of the present invention is to improve the measurement accuracy.

For this purpose, a subtraction circuit is inserted in the device, connected to the synchronizer and capacitive storage devices, which are connected via a battery to the sawtooth generator, and the control inputs of the keys are connected to the output of the aorog system.

FIG. 1. given the block diagram of the proposed usgroysuva; FIG. 2 is a graph depicting a pulse at the same time mixing; in fig. 3 is a graph depicting a C-V harakgersgiki.

The proposed device consists of a signal generator 1 and an amplifier 2 measur | of the game, the signal intended for H "kjepeHHfl of the capacitance of the MDPstructure, by the method of intent of the current flowing through the resistor. 3 sawtooth voltage generator 4} intended for supplying the voltage of mixing to an emittable structure, threshold device 6, whose input is connected to the output of amplifier 2 of the measuring lanyard, intended to control electronic analog switches 7 and 3, of the subtraction circuit 9 intended for automatic subtraction and digital recording of measurement results and automatic synchronizer; 1p, designed to synchronize the operation of the entire device. To the inputs of the subtraction circuit 8, capacitors 11, 12 are connected to expand the pulses supplied to the switches with keys 7 to 8, the signal inputs of which are connected to the generator 4 of the sawtooth voltage, and the control devices {to the device 6.

When supplying the scissors from generator 1 to the tested MIS-string 5, current flows through it and a current-earth resistor 3 is released. The voltage proportional to the capacitance is released. This is amplified and detected by the amplifier 2 of the measuring signal, and then goes to the input of the threshold device 6.

At the command of the automatic synchronizer Yu, the generator 4 of the sawtooth voltage is started, forms the leading front 18 of the sweep (Fig. 2). The signal at the input of the threshold device 6 and the branch in accordance with the C-V characteristic of 14 fvg. 3). At the same time, the automatic synchronizer 10 through the threshold device prepares the operation of the electronic analog key 7, which is initially closed. At the moment when the voltage at the input of the threshold device 6 becomes equal to the preset voltage VOQ, the noporoEJoe device triggers and sends a control pulse to the key 7. The key closes and the mixing voltage V, (see Fig. 2, Fig. 3). ) connected to the forward input of the subtraction circuit for a time sufficient to charge the capacitor 11. After switching off the key 7, the capacitor 11 saves the voltage V2 the time required to complete the measurement cycle.

Similarly, when the automatic synchronizer 10 gives the command to form a sweepOfront 14 sweep and through the threshold device

prepares the operation of the key B, the capacitor 18 connected to the inverting input of the subtracting circuit 9, is charged to the voltage V2 corresponding to the same value V on the C – V harsh thyristine 15.

Between the inputs of the subtraction circuit, a voltage AV is formed, equal to the hysteresis of the C-V characteristics: at the capacitance level Qon. This level is determined by the magnitude of the reference voltage.

In the last stage of the measurement cycle, the automatic synchronizer includes a digital voltmeter-circuit 9 of subtraction: which digitally records, dV and allows you to read, or use digital data for further information processing.

To use the proposed device to view the C-V characteristic itself, it is sufficient to connect 4 sawtooth voltage and the output of amplifier 2 of the measuring signal X and O channels of the oscilloscope to the generator 4 output.

Claims (2)

Invention Formula A device for measuring the characteristics of hysteresis MDP structures, comprising a test signal generator, an amplifier, a sawtooth voltage generator, a synchronizer, threshold devices, and a voltage difference indicator, characterized in that, in order to improve measurement accuracy, a subtraction circuit is inserted in the device, connected with synchronizer and capacitive accumulators, which are connected via keys to the generator of pipoo voltage, and the control codes of the keys are connected to the output of the threshold accumulator. Sources of information taken into account in the examination -one. Auiomaiic Disp oi-if of {nie Capacitance versus Beiaa dieroctemiics Ueview v.27, f966, P34i-359 2. USSR author's certificate № 24O0853, CP. Q Ol R 31/26, Ol.04.69. on