Method for applying charge-based-capacitance-measurement with switches using only NMOS or only PMOS transistors
Described is a CBCM technique that works only with PMOS transistors or only with NMOS transistors. Specifically, a method of monitoring performance of an integrated circuit device using a CBCM technique is disclosed, the method comprising: providing a metrology structure having a pseudo-inverter comprising a pull-up pull-down transistor switch, wherein the transistor switch comprises a pull-up transistor and a pull-down transistor of the same type; charging and discharging a device under test (DUT) coupled to the pseudo-inverter using a non-overlapping clock; measuring capacitance of the DUT with a gate voltage of the pull-up transistor at a preset value; and, using the value of the measured capacitance to estimate a dimension of a structure in the integrated circuit device. The non-overlapping clock is generated by: turning the pull-down transistor off when the pull-up transistor is on; and, turning the pull-down transistor on when the pull-up transistor is off.
1. A method for estimating at least one dimension of a structure of an integrated circuit device under test (DUT) using a charged-based capacitance measurement (CBCM) technique, the method comprising:
providing a metrology structure having a pseudo-inverter comprising a pull-up, pull-down transistor switch, and an output, wherein the transistor switch comprises a pull-up transistor and a pull-down transistor of same transistor type;
charging and discharging the DUT coupled to the output of the pseudo-inverter using non-overlapping clock signals comprising a first clock signal electrically connected with a gate of the pull-up transistor and a second clock signal electrically connected with a gate of the pull-down transistor, the second clock signal non-overlapping with respect to the first clock signal, wherein the non-overlapping clock signals are configured for: turning the pull-down transistor off when the pull-up transistor is on; and
turning the pull-down transistor on when the pull-up transistor is off;
providing a first backside voltage bias for the DUT when the pull-up transistor is on and the pull-down transistor is off such that voltage potential of a backside of the DUT comprises a positive supply voltage Vdd;
providing a second backside voltage bias for the DUT when the pull-up transistor is off and the pull-down transistor is on such that the potential of the backside of the DUT comprises ground (GND); measuring capacitance of the DUT with a gate voltage of the pull-up transistor at a preset value to obtain a value of the measured capacitance; and
using the value of the measured capacitance to estimate the at least one dimension of the structure in the DUT.
2. The method of claim 1 , wherein both the pull-up transistor and the pull-down transistor are n-channel metal-oxide-semiconductor (NMOS) transistors.
3. The method of claim 2 , wherein the preset value of the gate voltage of the pull-up NMOS transistor comprises a voltage greater than Vdd plus at least a worst-case threshold voltage of the pull-down NMOS transistor.
4. The method of claim 3 , wherein a maximum preset value of the gate voltage is kept lower than a voltage where an oxide layer in the integrated circuit device breaks down.
5. The method of claim 1 , wherein both the pull-up transistor and the pull-down transistor are p-channel metal-oxide-semiconductor (PMOS) transistors.
6. The method of claim 5 , wherein the preset value of the gate voltage of the pull-up PMOS transistor comprises a voltage lower than at least a threshold voltage of the pull-down PMOS transistor.
7. The method of claim 6 , wherein a maximum preset value of the gate voltage is kept lower than a voltage where an oxide layer in the integrated circuit device breaks down.
8. The method of claim 1 , wherein the CBCM technique comprises a charge-injection-error-free (CIEF) CBCM technique.
9. A method for estimating at least one dimension of a structure in an integrated circuit device under test (DUT) using a charged-based capacitance measurement (CBCM) technique for instances wherein complementary metal-oxide-silicon (CMOS) devices are not available, the method comprising:
at a metrology structure provided with a pseudo-inverter switch comprising a pull-up transistor and a pull-down transistor of same transistor type, and an output, wherein the pseudo-inverter switch comprises a structure wherein a positive supply voltage (Vdd) of the DUT is electrically connected with a source of the pull-up transistor, a drain of pull-up transistor is electrically connected with a source of the pull-down transistor of the same transistor type and with an the output of the pseudo-inverter switch which is configured for charging and discharging the DUT, wherein a drain of the pull-down transistor is electrically connected with electrical ground (GND), and wherein the gate of the pull-up transistor is electrically connected to receive a first clock signal and the gate of the pull-down transistor is electrically connected to receive a second clock signal that is opposite in polarity and non-overlapping with respect to the first clock signal:
charging and discharging the DUT coupled to the output of the pseudo-inverter switch using the non-overlapping clock signals, wherein the non-overlapping clock signals are configured for (i) turning the pull-down transistor off when the pull-up transistor is on and (ii) turning the pull-down transistor on when the pull-up transistor is off;
providing a first backside voltage bias for the DUT when the pull-up transistor is on and the pull-down transistor is off such that voltage potential of a backside of the DUT comprises a positive supply voltage Vdd;
providing a second backside voltage bias for the DUT when the pull-up transistor is off and the pull-down transistor is on such that the potential of the backside of the DUT comprises ground (GND); measuring capacitance of the DUT with a gate voltage of the pull-up transistor at a preset value to obtain a value of the measured capacitance; and
using the value of the measured capacitance to estimate the at least one dimension of the structure in the integrated circuit DUT.
10. The method of claim 9 wherein both the pull-up transistor and the pull-down transistor are n-channel metal-oxide-semiconductor (NMOS) transistors.
11. The method of claim 9 wherein both the pull-up transistor and the pull-down transistor are p-channel metal-oxide-semiconductor (PMOS) transistors.
12. The method of claim 11 wherein the preset value of the gate voltage of the pull-up PMOS transistor comprises a voltage lower than at least a threshold voltage of the pull-down PMOS transistor.
13. The method of claim 12 wherein a maximum preset value of the gate voltage is kept lower than a voltage where an oxide layer in the integrated circuit device breaks down.
14. The method of claim 9 wherein the preset value of the gate voltage of the pull-up NMOS transistor comprises a voltage greater than Vdd plus at least a worst-case threshold voltage of the pull-down NMOS transistor.
15. The method of claim 14 wherein a maximum preset value of the gate voltage is kept lower than a voltage where an oxide layer in the integrated circuit device breaks down.
16. The method of claim 9 wherein the CBCM technique comprises a charge-injection-error-free (CIEF) CBCM technique.