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Number 3141
Pulse I-V Characterization of
Application Note Non-Volatile Memory Technologies
Series
Introduction testing floating gate flash, phase-change cell, and ferro-electric
cell devices.
Until recently, floating gate (FG) NAND flash memory
technology has successfully met the growing requirement for
non-volatile memory (NVM) for digital cameras, MP3 players Brief History of NVM
and smartphones. However, there is increasing concern in the Scientists around the world are investigating NVM alternatives
consumer electronics industry that floating gate NVM may not that can replace FG NAND technology, including phase-change
be able to continue providing higher storage capacities at the memory (PCM/PRAM), charge trap flash (CTF/SONOS), resistive
ever-lower cost-per-bit requirements that drive the NVM market memory (ReRAM), ferro-electric memory (FeRAM), and
[1]. The potential for the floating gate approach to "hit the wall" magnetoresistive memory (MRAM) (Figure 1). These device
means that research into alternative technologies has become technologies have been studied for years, and each is currently
increasingly critical. available in the market in some form. Other NVM technologies,
This wide-ranging research into an expanding number including spin-transfer torque (STT) MRAM, floating body
of materials and technologies requires an electrical test (FBRAM), and various types of carbon-nanotube-based memory
system with wide dynamic range and flexible parameter (CNT RAM), are being actively researched to determine their
control. This application note provides a brief history of NVM, suitability for memory product applications.
an overview of the test parameters required for electrical In addition to the traditional uses of NVM in portable
characterization of NVM materials and devices, and an consumer electronic devices, the success of FG NVM has created
explanation of the capabilities of the Model 4225-PMU Ultra-Fast new product categories, such the ubiquitous "thumb" or USB
I-V Module with the Model 4225-RPM Remote Amplifier/Switch, drive and, more recently, the high performance Solid State Disk
two instrument options designed for use with Keithley's Model (SSD) products now being used as replacements for traditional
4200-SCS Semiconductor Characterization System. The Model computer hard drives in high performance applications. These
4225-PMU/4225-RPM combination has integrated simultaneous products, as well as the possibility of a "universal" memory that
measurement of current and voltage on each channel, making would replace both existing flash and dynamic memory (DRAM),
investigating transient pulse responses much simpler than with have justified ongoing research at universities and semiconductor
previous hardware. With the system's multi-pulse waveform organizations and companies [2].
generation capability, the Model 4200-SCS with the Model 4225-
The ideal memory should have characteristics of both
PMU may be used to characterize the memory device's switching
dynamic and non-volatile memory:
mechanism in both the transient and I-V domains. After a
discussion of emerging test requirements, this note provides