Keithley's latest system goes for ultra-fast I-V solution


This week Keithley Instruments Inc. unveiled its Model 4225-PMU Ultra Fast I-V Module, integrating ultra-fast voltage waveform generation and current/voltage measurement capabilities into the company's Model 4200-SCS semiconductor characterization system (Figure 1). Because it has wide programmable sourcing and measurement ranges, pulse widths, and rise times, it is suited for applications that demand both ultra-fast voltage outputs and synchronized measurement. Among its targeted applications are nanometer CMOS, flash memory, silicon-on-insulator (SOI), MEMS cap, ultra-fast NBTI, LDMOS/GaAs isothermal, and single-pulse charge trapping/high-k.

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Figure 1. Current measurements vs. time comparison of various Keithley DC and pulsed I-V instruments. (Source: Keithley Instruments)

The common denominator for all these targeted applications, according to Keithley marketing manager Lee Stauffer, is that they require faster measurement/pulse speeds than a traditional source measure unit can do (Figure 2). For example, SOI is a technology where the transistors are built up on top of an insulating layer—so they have a difficult time dumping heat and have to be tested very quickly in a pulsed mode, e.g., 100μs and faster. Phase-change memory (PCM) also requires a very fast pulse and measure to be able to fully characterize the device.

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Figure 2. Current measurements vs. time comparison of various targeted applications for various Keithley DC and pulsed I-V instruments. (Source: Keithley Instruments)

The new product also allows characterization of the full range of materials, devices, and processes with a single set of instrumentation, explained Stauffer. Labs can configure one system to handle all three measurement types: precision DC I-V (Model 4200-SMU), AC impedance (Model 4210-CVU C-V Instrument), and ultra-fast I-V or transient I-V (Model 4225-PMU).

Each 4225-PMU module provides two channels of integrated sourcing and measurement, where each channel combines high-speed voltage outputs (with pulse widths ranging from 60ns to DC) with simultaneous current and voltage measurements. The module provides high-speed voltage pulsing with simultaneous current and voltage measurement, at acquisition rates of up to 200 megasamples/second (MS/s) with 14-bit analog-to-digital converters (A/Ds), using two A/Ds per channel (four A/Ds per card). End-users can choose from two voltage source ranges (±10 volts or ±40 volts into 1Mohm) and four current measurement ranges (800mA, 200mA, 10mA, 100μA). — D.V.

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