E4727A Advanced Low-Frequency Noise Analyzer

• Advanced low-frequency noise analyzer’s integration with WaferPro Express enables turnkey noise measurements as well as measurement of DC characteristics, capacitance and RF S-parameters.
• Industry-leading noise sensitivity (-183 dBV²/Hz) that allows noise measurements at high voltages (to ±200 V) and down to ultra-low frequencies (to 0.03 Hz).
• Software module measures DC characteristics, 1/f noise, random telegraph noise and conducts data analysis.
• Keysight’s close collaboration with Cascade Microtech enables a complete integrated on-wafer solution with automated control of all major wafer probing systems.

The E4727A Advanced Low-Frequency Noise Analyzer enables fast, accurate and repeatable low-frequency noise (LFN) measurements on numerous device types. Now, thanks to tight integration with Keysight’s WaferPro Express software, device modeling and characterization engineers can now add noise measurements to a larger suite that includes high-speed DC, capacitance and RF S-parameter measurements, all the while automating wafer prober control.

Applications

The applications are numerous, however a few important ones are listed as follows.

• Process design kit (PDK) development - Semiconductor device foundries enable fabless design centers to design components like transceivers for mobile phones, frequency synthesizers, analog-to-digital converters. To make this possible, the foundries must provide Process Design Kits (PDK’s) with simulation models of the semiconductor devices. The simulation models must capture noise effects on transistors (BJT, CMOS, etc.) and resistors across all possible bias currents, temperatures and geometries.
• Manufacturing statistical process control - As an example, manufacturers of GaN devices may use noise measurements across their wafers as an early indicator of device reliability. Those devices that exhibit more noise are likely to fail sooner. Now we have a nondestructive way of assessing reliability, quite in contrast with standard accelerated life testing. Furthermore, for circuit applications where noise is a critical parameter, wafer level measurements can be used to track the evolution of noise performance across days, weeks and months of manufacturing.
• IC noise specification - Integrated circuit manufacturers of operational amplifiers and linear voltage regulators often need to characterize output voltage noise as a critical specification in their datasheets. One wafer may contain 20,000 such circuits. To efficiently measure and map circuit performance across the wafer (and even across lots of wafers), the probe and signal conditioning circuitry must be placed close to the device under test to improve grounding and minimize external noise influences. The unique modular design of the A-LFNA enables short cables to the probe fixtures, thereby widening the frequency range of this measurement.

Turnkey Measurements

The A-LFNA’s built-in measurement routines make DC and noise measurements turnkey. To measure noise on an N-Type MOSFET, for example, the system automatically chooses the source and load impedances that will best expose the intrinsic device noise. The engineer can accept these recommended settings or make changes, and a noise measurement is initiated. The A-LFNA then measures noise power spectral density (1/f noise) and noise in the time domain (RTN). Resulting data is plotted using a multiplot data display window. Various windows tabs help facilitate common tasks like evaluating device DC operating point and measuring the slope of the power spectral density curve. Noise data can also be analyzed and represented in device models using device modeling tools such as Keysight’s Model Builder Program (MBP) and IC-CAP. Circuit designers can use these device models to ensure highly accurate RF and analog low-noise circuit design.

Automated RTN Solution using E4727E3 and B1500A

E4727E3 efficiently performs at a low cost an automated RTN measurement on the wafer using the B1500A Semiconductor Device Analyzer with the B1530A Waveform Generator/Fast Measurement Unit (WGFMU). It can improve the efficiency of RTN measurement and data analysis including wafer prober control.

Key features

• Automated RTN and 1/f noise measurement and data analysis
• Wafer mapping
• Multiple data overlapping display
• System noise floor display and data clipping

 A-LFNA - WGFMU Comparison

Figure 1. A-LFNA - WGFMU Comparison using Device: JFET, Bias: Ids=300p/1n/2n/7n/100n/1µA, Vds=50mV.