SU1000946A1 - Device for measuring c-g-v characteristics of mis structures - Google Patents

Description

(54) DEVICE FOR MEASURING C-Q CHARACTERISTICS OF TIR STRUCTURES

one

The invention of ognosigs for measuring instrumentation and can be used to control the quality of semi-pioneer structures, for example, MIS structures, during their production. ,

A device is known in which was-. there is a separate change in the capacitance of the investigated MIS structure and the active conductivity of the leak in a wide dynamic range of changes in the parameters of the object under study Ij,

The disadvantage of this device is the low accuracy of measurement of reaped parameters of the MIS-structures due to the use of an inaccurate replacement scheme.

Closest to the present invention is a device for measuring the electrophysical parameters of MIS structures, comprising a control unit, a reference voltage source, a first adder, a test object, an operational amplifier, a differential clamp, a controlled voltage divider, a first key, a second adder , second key, storage unit, zero-organ, programmable source of mixing, inverter, adjustable resistance, first, second and third additional keys, additional storage unit, key, subtractor straight zheny unit measuring a time constant circuit dividing the voltage, the switch and the recorder 2J.

The known device is characterized by insufficient measurement accuracy. In addition, it incorporates a positive feedback loop (compensation circuit for the effect of dielectric capacitance S. (), which leads to a decrease in the stability and stability of its operation. The effect of positive feedback leads to an increase in amplitude amplitude the frequency characteristics of the device, and in the process of operation, the speed loops of the signal are changed during the operation, in the feedback loop 1i, 1 call

the change in the steepness of the fronts of the pulse signals, which is reflected in the measurement accuracy of the parameter C a, determined by the instantaneous value of the voltage at the output of the operational amplifier with the help of a key. The remaining parameters of the MIS structure also vary with great permissiveness, since they are defined as south with regard to the measured value of Cj.

All of these factors lead to

decrease in the accuracy of measurement of parameters of MOS structures.

The purpose of the invention is to improve the measurement accuracy of the C characteristics of the characteristics of the MIS structures.

The goal is achieved by the fact that in a device for measuring C - (Y characteristics of a MIS structure, containing a control unit, the first output of which is connected to the control input of a voltage source, the second output is connected to the control input of a programmable bias source, the output of which is connected to the first input of the recorder and the first terminal for connecting the object under study, the second terminal of which is connected to the input of the operational amplifier and one of the plates of the reference capacitor, the second of which is connected The unit is connected to the first input of the voltage calculator, the second input of which is connected to the output of the operating force of the body, the constant time meter, the input of which is connected to the input of the zero, organ, and the output - with the key input, as well as the switch, the output of which is connected to the second input of the recorder, a separation capacitor is introduced, the source of the control voltage, the second

voltage healer, first and second peak detectors, voltage measuring unit, additional voltage detector, comparison unit and low-pass filter, the first plate of the coupling capacitor connected to the first terminal for connecting the object under study, and the second to the output of the operating capacitor the amplifier, the output of the voltage supply is connected to the inputs of the first

a peak detector, a second voltage detector, a zero-organ and a constant time measurement unit; the output of the first pico detector is connected to the first input of the comparison unit and the first input of the switch; the output of the second voltage divider is connected to the inputs of the second peak

a detector and a voltage measuring unit, the control input of which is connected to the third output of the control unit, and the output to the second input of the switch and the first input of the second voltage subtractor, the second input of which is connected to the output of the second peak detector, the control input of the key, the output of which through a low-pass filter connected to the third input of the switch, the control input of the second peak detector is connected to the input of the first peak detector and the fourth output of the control unit, the fifth output of which is connected to the first The source of the control voltage source, the second input of which is connected to the output of the null organ, and the output connected to the input of the first divider and the fourth input of the switch, the output of the additional voltage subtractor is connected to the second input of the comparator unit, the output of which is connected to the control input of the second divider .

The drawing shows a block diagram of the proposed device.

The device contains a control unit 1, a reference voltage source 2, a reference capacitor 3, an operational amplifier 4, an object K5 under study, a programmable bias source 6, a coupling capacitor 7, a voltage subtractor 8, a first controlled voltage divider 9, a control source 10 for example, null organ 11, first peak detector 12, second. t1p is a voltage divider 13, a constant time measurement unit 14, a second peak detector 15, a steady voltage measurement unit 16, an additional subtractor 17, voltages, a comparison device 18, a switch 19, a low-pass filter 20, a switch 21 and Recorder 22.

The control input of the source 2 of the reference voltage is connected to one of the outputs of the control unit 1. The output of the source 2 of the reference voltage is connected via the first controlled healer 9 of the voltage to the first input of the subtractor 8, and through the reference capacitor 3 to the input of the operational amplifier 4 and to one terminal of the object under study B, the other terminal of the object under study 5 is connected to the output of the programmable bias source 6, and through the separation capacitor 7 - to the output of the operational amplifier 4 and the second input of the voltage subtractor 8, the output of which is the peak of the voltage divider 13, the zero-body 11 and the measurement unit 14 post time constant. The output of the zero-organ 11 is connected to the control input of the first controlled voltage divider 9 through the source of the 1-control voltage. The output of the second controllable voltage divider 13 is connected to the inputs of the hot peak detector 15 and the measurement unit 16 of the set voltage value. The output of the second peak detector 15 is connected to the input of the key 19 and the first input of the additional 17 voltage subtracted, the second input of which is connected to the output of the measurement unit 16 of a steady-state voltage value. The output of the additional voltage subtractor 17 is connected to the first input of the comparison device 18, the second input of which is connected to the output of the first peak detector 12. The output of the comparison device 18 is connected to the control input of the second divider of the SRI 13. The output of the constant time measurement unit 14 is connected with the control input of the switch 19, the output of which is connected to the input of the low-pass filter 2O Control inputs of the control voltage source 1O, the first and second peak detectors 12 and 15, block 16

e.

, Gcd - capacitance of the supporting capacitor C - capacitance of the dielectric, C: capacitance of the depleted layer of the semi conductor, C2pc- capacitance and resistance associated with surface junctions. This is what depends on the surface potential. During the other half period, this voltage has the opposite sex. In the enrichment mode, the capacitance C of the outer semiconductor layer is so large that the capacitance of the MIS structure is almost equal to the dielectric capacitance. Consequently, in the enrichment mode, at the output, the opera tional amplifier 4 OY O O / CIC j-C-j

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2

510009 64 is connected to the inputs of the first dimension at a fixed value of the detector 12, the second control is connected to the corresponding outputs of the control unit 1. The outputs of the control voltage source 1O, the first peak detector 12, the measurement unit 16 of the steady-state voltage and the low-pass filter 2O connect with the corresponding inputs of the switch 21. The output of the last sub-keys to the signal input of the recorder 22, the horizontal input of which is coupled to the programmable output source 6 offset. The device works as follows: On the command of the control unit 1, the programmable bias source 6 supplies to the investigated MIS structure 5 such a bias voltage, which introduces the MIS structure into the strong enrichment mode (this voltage must be positive for the P-type structure negative for the p-type structure). The source 2 of the reference voltage produces a reference (test) voltage in the form of bipolar rectangular pulses with amplitude bd. In this case, during one of the half-periods of the reference voltage, the output voltage of the operational amplifier 4 has the form The output voltage of the “first control divider 9 voltage VAH, E The output voltage of the subtractor 8 is in the form of n, be, (, CgtCa -СС, Я.EoCo .; with a mode of enrichment Ln At the command of the control unit of the source 10 of the control voltage, the control input of the first control unit

710009468

Healer 9 ex; control voltage Permanent control voltage

a constant voltage, slowly and ea kx, at the entrance of the first controlled healer, is as long as the null organ 11

does not zyfiksiruet at the exit

8 voltages zero value volt- 5 Tagore 21 is fed to the recorder 22.

NIAUVU "EoSo / S EdKu.i. Y. This is a pro. For the entire measurement cycle

when the YAH-I command is issued to the zero-command command 11, the source 10 of the control voltage stops changing the output voltage and fixes it at the level at which

SAHI CO / C ,.

Noso

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: - Co + C; The first peak detector 12 detects the extreme (for the half-period of the reference signal) voltage value (J c. Cohort is fed to the recorder 22 through the switch 21. The output voltage of the subtractor 8 voltage is scaled by the second controlled by the voltage divider 13 and is fed to the inputs of the second peak detector 15 and measurement unit 16 of the set voltage value. Their output voltages V k L: lM BHvSH-q .. are fed to the inputs of the additional voltage detector (Cs + Ca) This voltage compare comparing device 18 with a voltage taken from the output of the first peak detector of torus 12

voltages, proportional to the value of its transmission coefficient, through the commuparameters of the MDPstructure sample under study. the value of K does not change.

Then, at the command of the control unit 1, the programmable bias source 6 removes the MIS structure from the enrichment mode with the investigated MOS structure. At different bias voltages, the value of the capacitance of the dielectric C remains unchanged, therefore

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Claims (2)

e, in the case of the inequality of the voltages of the UcD and UriDj, the error signal from the output of the comparator 18 changes the transmission coefficient of the second controlled voltage divider 13 until CoC2 EdCo is reached. Cs. This will occur at ./C. The output voltage of the measurement unit 16 of the steady-state value of the voltage of OEoC g 1g is fed through the switch 21 to the source 22. The output voltage of the second detector signal 15 -EoC, () VAHI goes to the filter through the key 19 2 About low frequencies. The constant time measurement unit 14 determines the time constant of the exponentially varying voltage at the output of the subtractor of 8 voltages, converts the value of the constant time of this voltage to the pulse duration CL R R The output voltage of the constant time measurement unit 14 It is applied to the control input of the key 19, opening it for the duration of the pulse L t t. At the output of the key 19 pho {1yuyugs rectangular pulses with amplitude Yfi and duration L. p. Volt-second area of these pulses EoCo (C2 + Ce) KA Vnft7 t The low-pass filter 20 finds the average value of the output voltage of the switch (proportional). The output of the low-pass filter 2O through the switch 21 is connected to the recorder 22. Thus, a constant voltage is proportional to the current values of the parameters of all elements of the four-element replacement circuit of the MIS structure (with VCi i R), depending on the applied bias voltage. In this case, when changing the operating modes in the circuit, no re-commutations are performed, there is no feedback loop, which ultimately leads to an increase in the measurement accuracy of С -G-V characteristics of MDGT-h; The invention The device for measuring with --QV characteristics of MOS structures, containing a control unit, the first output of which is connected to the control input of the source of the reference voltage, the second output is connected to the control input of the programmable bias source, the output of which is connected to the first input itself the scribe and the first terminal to connect the object under investigation, the second terminal which is connected to the input of the operational amplifier and one of the plates of the reference capacitor, the second of which is connected to the output of the source Nickname of the reference voltage and the input of the divider, the output of which is connected to the first input of the subtractors of voltages, the second input of which is connected to the output of the operational amplification of the body, a constant time meter, which is connected to the input of the zero-organ, and the output to the input key, as well as a commutator, the output of which is connected to the second input of the recorder, is connected with the fact that, in order to increase the measurement accuracy, an isolating capacitor was inserted into it, the control voltage source , the second voltage divider, the first and second prototype detectors, a voltage measurement unit, an additional voltage subtractor, a comparison unit and a low-pass filter, with the first plate of the coupling capacitor connected to the first terminal for connecting the sam- pline under test, and the second to the output of the operational amplifier, the voltage subtractor output is connected to the inputs of the first peak detector, the second voltage divider, the zero-organ and the unit of measurement of the constant time, the output of the first peak detector is connected to the first input of the comparison unit and the first input of the Ator, the output of the second voltage divider is connected to the second inputs of picosecond. iBor6 of the detector and the voltage measuring unit, the control input of which is connected to the third upstream of the control unit, and the output to the second input of the switch and the first input of the second voltage downreader, the second input of which is connected to the 1st EXIT of the second peak cetecore that controls the key input, output which through a low-pass filter is connected to the third input of the switch, the control video of the second peak detector is connected to the input of the first peak detector and the fourth output of the control unit, the fifth output of which is connected to the first The control input of the control voltage source, the second input of which is connected to the output of the zero-organ, and the output connected to the input of the first divider and the fourth input of the commutator, connect the output of the additional voltage subtractor to the second input of the comparator, the output of which is connected to the control input expensive splitter Sources of information taken into account in the examination 1. The copyright certificate. USSR № 6585О8, cl. Q O1 R 31/26, 25.04.79. 2. Author's svioetelsgvo for for-. Ke number 2926071 / 18-21, class. Q O1R31 / 26, 20.11.80 (prototype).