Standard R load measurement technology and Keithley new measurement technology

In the standard R load measurement technique (as shown in Figure 5), a resistor is connected in series with the DUT, and the current flowing through the DUT can be measured by measuring the voltage on the load resistor. Use an active, high impedance probe and an oscilloscope [1] to record the voltage on the load resistance. The current flowing through the DUT is equal to the applied voltage (VAPPLIED) minus the voltage on the device (VDEV), then divided by the load resistance. The size of the load resistance usually ranges from 1 kiloohm to 3 kiloohms. This technology uses a compromise: if the load resistance is too high, the RC effect and the voltage distribution on the R load and DUT will limit the performance of this technology; however, if the resistance value is too small, it will affect the current resolution rate.


Figure 5. Standard R load technology
Recently, we have developed a new current limiting technology that does not require load resistance. By tightly controlling the size of the current source, a more characteristic analysis can be performed on the low current in the RI curve. This new technology (shown in Figure 6) can simultaneously obtain I-V and RI curves through pulse scanning, which uses a high-speed pulse source and measuring instrument, that is, the dual-channel 4225-PMU [2] ultra-fast I-V module. This new module can provide a voltage source while measuring voltage and current response with high accuracy, with rise and fall times as short as 20ns.
Removing the load resistance also eliminates the side effects of foldback. The 4225-PMU module [3] and the 4225-RPM [4] remote amplifier/switch used to expand its sensitivity (as shown in Figure 7) can be used in the 4200-SCS [5] semiconductor characteristic analysis system, which not only has the ability to PCM The measurement function necessary for the device to perform characteristic analysis, and can automatically realize the entire test process.


Figure 6. Current limiting technology using 4225-PMU


Figure 7.4225-PMU ultra-fast I-V module and two 4225-RPM remote amplifiers/switches,
Applicable to Keithley 4200-SCS characteristic analysis system