CS240502B1 - Leakage currents' and parasitic capacities' influence on mis-structure's quasi static capacity-stress curve removing connection - Google Patents

Abstract

The invention belongs to the Electrical Engineering Department and solves the wiring problem streams and parasitic capacities to quasi-static capacitance-voltage curve MIS structure. Its essence is that the generator is through resistive capacitance measurement block, connected through a current-voltage converter to the summation circuit to which it is connected still a recorder.

Description

The invention relates to a circuit eliminating the effect of leakage currents and parasitic capacities on the quasi-static capacitance-voltage curve of the MIS structure.

The quasi-static method of measuring capacitance-voltage dependences METAL - INSULATOR - SEMICOYDUCTOR metal - insulator - - structure semiconductor in the next allows to obtain in a short time dependence of differential capacity of MIS structure from voltage to structure.

The principle of the method lies in the measurement of a small direct current of the order of 10 ¹² A flowing into the structure as a consequence of the time of linearly increasing voltage. In the case of sufficiently slow changes of the stress on the structure we get a graphical record of the passing current and the stress n on the structure t. Vol. Low-frequency capacitance-voltage dependence of MIS structure. This method of measuring low-frequency capacitance-voltage dependence of MIS structures is more advantageous in terms of time and economics than measuring low-frequency capacitance-voltage dependence by a classical method that uses a capacitance bridge for very low frequencies to measure the differential capacity of the MIS structure. A major drawback of the quasi-static method is the sensitivity to ohmic current flowing through the insulation resistance of the samples. The ohmic current, in the case of a conventional workplace arrangement, is recorded simultaneously with the capacitive current of the MIS structure, and thus the capacitance-voltage dependence is deformed.

These drawbacks are solved by a circuit eliminating the effect of leakage currents and parasitic capacities on the quasi-static capacitance-voltage curve of the MIS structure according to the invention, the principle being that the second generator voltage terminal is connected both to the third terminal of the summation circuit and a resistive capacitance measuring block and via a current-to-voltage converter to a second summation circuit terminal, wherein a first generator voltage terminal is connected to a first summation circuit terminal whose fourth terminal is connected to a second recorder terminal. Further, a first summation circuit terminal is connected through a grounded first variable resistor to a second resistor on both the first resistor and a non-inverting differential amplifier input, and a third summation circuit terminal is connected through a grounded second variable resistor, a fourth resistor and a fifth resistance to the fourth terminal of the summation circuit and to the inverting input of the differential amplifier.

The advantage of the circuitry according to the invention is that the interfering components of the parasitic capacitance and the leakage current are continuously subtracted from the total current, thereby avoiding the deformation of the capacitance-voltage curves of the MIS structure and the accuracy of the quasi-static method is increased several times.

The attached drawing shows a circuit eliminating the effect of leakage currents and parasitic capacities on the quasi-static capacitance-voltage curve of the MIS structure.

In connection, the second voltage terminal 19 of the generator 4 is connected both to the third terminal 3 of the summation circuit 15 and to the first terminal x of the recorder 17 and to the capacitance measuring block 5 through the current-to-voltage converter 6 to the other terminal 2 of the summation circuit. the voltage terminal 18 of the generator 4 is connected to the first terminal 1 of the summation circuit 15, the fourth terminal 16 of which is connected to the second terminal y of the recorder 17.

Further, the first terminal 1 of the summation circuit 15 is connected through a grounded first variable resistor 7 and through the second resistor 9 to both the first resistor 8 and the non-inverting input of the differential amplifier 10, the output of which is connected to the fourth terminal 16 of the summing circuit 15; the summation circuit 15 is connected via a third resistor 11 to the inverting input of the differential amplifier 10 and further the third terminal 3 of the summation circuit 15 is connected via a second variable resistor 14, further via a fourth resistor 12 through a fifth resistor 13 to the fourth terminal 18 and on the other hand the inverting input of the differential amplifier 10.

The task is to get the circuit voltage U _out, which is proportional only Icmis capacity currents, flowing through the MIS structure.

The principle of operation is that the output terminal 16 of the summing circuit 15 maintains the voltage given by the relation Uvy = K _r U _x - K ₂ U ₂ - K ₃ U ₃ (I)

It can be shown that when the required voltage conditions U _{1 are} met _; U ₂ , U ₃ and transmission constants K _b K ₂ , K _3, we achieve the correct wiring operation.

The following applies to voltage U:

(Π)

The voltage U ₂ is proportional to the total current of the MIS structure and the parasitic capacity C _PAR . 7, and through the second resistor 9, on the one hand, for which the transfer constant of the current-voltage converter 6 is.

For voltage U ₂ :

U ₂ = K (Irpar + Icar + Icmis) or

U ₂ = K - ^ - + KC _RA r - ^ - + KCmis

KpAR UL Hive (III)

For the voltage U ₃ at the input terminal 3 of the summation circuit 15:

U ₃ = U _G (IV)

We assume that:

K ₂ .K ₌

K3. Rpar (V) a

Ki.K ' ₌

K ₂ . K. C _PAR (VI) where the tip of the measuring tool is lowered just above the measured MIS structure.

At that time, the total current consists of the current flowing through the parasitic capacity C _PAR . By turning the first variable resistor 7, we set the zero voltage to the fourth output terminal 16 of the summation circuit 15. Then connect the measured MIS structure by starting the tip of the jig and stop the generator 4, dU _G ''.

——— = 0. On measured

Then after substituting (II), (IV) into (I) we get:

(III),

Show —K'Ki dU _G dt

K, KUG

rpart

- K ₂ KC _PAR _ K ₂ K Cmis K ₃ U _G (VII)

After adjusting and establishing relationships. (V), (VI) to (VII) we get:

Rise - —K ₂ K Cmis, ° (VIII)

Because = const, we can write:

Rise - K '. Cmis (IX) where

K '= —K ₂ K dU _G dt

Transfer constant K and K ₃ can be set by the first and second variable resistor 7 and 14. In practical operation, the transfer constant K found by dV _r actuated generator 4 0 MIS structure of the voltage U _G - const.

The total current of the MIS structure is now composed of only the current flowing through the parasitic resistance R _par MIS structures. By turning the second variable resistor 14, again set the zero voltage at the fourth terminal 16 of the summary circuit 15.

The summing circuit 15 thus set can be used for measuring the capacitance-voltage dependencies of the MIS structure and for a whole series of samples. For very accurate measurements, it is recommended to set the transmission constants K _t and K ₃ separately for each sample.

List of symbols:

C - capacity F

Cmk - capacity of MIS F structure

Cpar - parasitic capacity of the tip preparation F

Irrar - current flowing through the parasitic resistance of the MIS A structure

Icpar - current flowing through the parasitic capacity of the MIS A structure

Icmis - capacity current of MIS structure

K, K _{1 (} K ₂ , K ₃ - transmission constants)

U —- voltage V

For _G - voltage applied to the MIS V structure

U _R - generator output voltage

Uout - output voltage of the summing circuit 15 V

U _b U ₂ , U ₃ - input voltage of the summing circuit 15 V

Rpar - parasitic resistance of MIS structure.

Claims (2)

240502 U3 = UG (IV) We assume that: K2.K = K3. Rpar (V) and Ki.K ‘= K2. K. CPAR (VI) wherein the tip of the measuring jig is triggered just above the measured MIS structure. Then the total current consists of flowing through the parasitic capacity CPAR. By turning the first variable resistor 7, we set the zero voltage to the fourth output terminal 16 of the summing circuit 15. Then, the measured MIS start-up of the measuring jig is connected and the generator 4, dUG ' ——— = 0. On the measured Then after substituting the relations (II), (IV) into the relation (I) we get: (III), Uvyst —K'Ki dUG dt K, K- Ug Rpar - K2K CPAR - - K2K Cmis K3.UG (VII) After adjusting and establishing relationships. (V), (VI) in relation (VII) we get: Uvyst - —KKK Cmis,. ° (VIII) Because = constant, we can write: Uvyst - K “. Cmis (IX) where K '= -K2K dUG dt The transmission constants Ki and K3 can be set using the first and second variable resistors 7 and 14. In practical operation, the transmission constant K i is found such that dUr is given by the generator 4 - --- · 0, the structure of MIS is the voltage UG - constant. The total current of the MIS structure is now only stored from the current flowing through the parity resistor Rpar of the MIS structure. By rotating the second variable resistor 14, I set the zero tension at the fourth terminal 16 of the sonic circuit 15. The summation circuit 15 thus set can be used to measure the capacitance-voltage dependencies of both the MIS structure and the entire series of samples. For very accurate measurements, it recommends setting the IQ and K3 transmission con- ditions in particular for each sample being measured. List of symbols: C - capacity F Cmk - capacity of structure MIS F Cpar - parasitic capacity of spike F Irrar - current flowing through parasitic resistance of MIS structure A Icpar - current flowing through parasitic capacitance of MIS A Icmis - capacitance current of structure MIS AK, K1 ( K2, K3 - transmission constants U - voltage V UG - voltage applied to the structureMIS V UR - generator output voltage V Uvyst - output voltage of summation circuit 15 V Ub U2, U3 - input voltage of summation circuit 15 V Rpar - parasitic resistance of MIS structure. OBJECT 1. A wiring eliminating the influence of leakage currents and parasitic capacities on a quasi-static capacitance-voltage curve of the MIS structure, characterized in that the second voltage terminal (19) of the generator (4) is connected to the third terminal (3) of the summation circuit (15) on the one hand, on the first clamp (x) of the writer (17) and on the other hand via the resistive capacitive measuring block (5) and via the flow-band converter (6) on the terminal (2) of the summing circuit (15), the first on the voltage terminal (18) of the generator (4) is connected to the first summation terminal (1) of water (15), the fourth terminal (16) of which is connected to the recorder terminal (s) (17). 2. Connection of the stage of claim 1, characterized in that the first terminal (1) of the summing circuit (15) is connected via a grounded first variable (7) and via a second resistor (9), on the other hand, the grounded first resistor (8) and the non-inverting the input of the differential amplifier (10), the output of which is connected to the fourth terminal (16) of the summation circuit (15), the second terminal (2) of the summation circuit 240502 du (15) being connected via the third resistor (11) to the inverting input of the differential the amplifier (10) and further the third terminal (3) of the scanning circuit (15) is connected via. a grounded second variable resistor (14) passing through a fourth resistor (12) and a second resistor (13) to a fourth terminal (16) of the summing circuit (15) and an inverting input of the differential amplifier ( 10). 1 sheet of drawings