Palo Alto, Calif.Agilent Technologies's Automated Test Group is now delivering a new semiconductor tester called the B1500A Semiconductor Device Analyzer. This product was announced a few months ago, but is now ready to order.
Shipped with Agilent's EasyEXPERT software, it's a Windows XP Pro-based analyzer that integrates CV (capacitance versus voltage), and IV (current versus voltage) measurements in a single instrument. The Windows-based graphical user interface is familiar, even to new engineers who are inexperienced with parametric measurement instruments.
Why is CV plotting needed? Well, many of the important physical characteristics of a MOSFET can only be extracted after first plotting the CV curve of the transistor. Typical parameters extracted from this data include gate oxide thickness), substrate impurity concentration, flat band capacitance, flat band voltage, surface charge density, and threshold voltage). All of these parameters affect the behavior of the MOSFET, so understanding their values is important to determine if a process is meeting design targets.
Back to the B1500A, a self-contained and expandable system. Handling both parametric characterization and analysis, it's also capable of accommodating 65-nm lithographiesand smaller. The modular instrument, with a 10-slot configuration, gives you an intuitive top-down approach to device characterization.
Device Application Tests
The EasyEXPERT Windows software supplies a library of device application tests that you select based on the type of measurement required. After making a few selections, such as identifying the technology by classification and selecting the appropriate device type, the software selects the appropriate settings, makes the measurements, analyzes the data and displays it graphically.
EasyEXPERT also lets you view multiple tests simultaneously, perform test sequencing without programming, and supports sharing of application tests. It does realtime graphical data analysis, with unique see-through multiple window graphical overlays. The software also lets you print across either a LAN (local area network) or using USB (Universal Serial Bus). Speaking of USB, the system supports communications with any USB peripheral.
Agilent claims that even a beginner can start making productive measurements within a few minutes of powering up a B1500A. This is important, as most engineers face additional challenges when both IV and CV measurements are required for characterization. Most instruments are designed for only one type of measurement, which means that two different instruments must be used for the tests, requiring mastery of two interfaces.
The Cable Conundrum
Proper connection of the CMU (capacitance measurement unit) cables to the DUT (device under test), and precise cable length compensation are also necessary to ensure accurate CV measurement results. Click on this image to see a blow-up showing typical cabling.
Click for larger image
The length of the cable coming from the CMU to the DUT has a significant impact on capacitance measurements. Any measurement cable possesses some innate capacitance per unit length, and this capacitance will distort the total capacitance measured by the CMU unless this distortion is compensated for. The process of compensation is a mathematical operation performed on the measured capacitance values to remove the effects of the cable capacitance.
Also, CMUs use BNC coaxial connectors, whereas SMUs (source measurement units) use triaxial connectors. Switching between these incompatible connectors can be difficult and confusing, especially when using positioners on a wafer prober. In any case, the B1500A's 10-slot configuration supports three SMU types. It supports HRSMUs (high-resolution SMUs), MPSMUs (medium-power SMUs), and HPSMUs (high-power SMUs).
A MFCMU (multi-frequency capacitance measurement unit) is also available, and a 4.2-A GNDU (ground unit) is included with a B1500A mainframe.
Besides integrating CV measurement into the device analyzer mainframe, the MFCMU possesses many measurement capabilities not typically available on comparable external capacitance meters. For example, it can measure capacitance at up to 5-MHz, and provide ±25-V of DC bias.
Tightly Coupled Resources
In addition, the combination of the MFCMU and SMUs within the same instrument enables these measurement resources to be tightly coupled. When joined using the B1500A SMU SCUU (CMU Unify Unit), the MFCMU and SMU combination supports capacitance measurement with +/-100-V of DC bias.
The B1500A SCUU provides a convenient (and, Agilent says foolproof) means to connect two SMUs and the MFCMU together, and to switch between these different measurement resources without using a separate external switching matrix. The B1500A software handles and resolves all IV-CV switching, compensation, and return path problems. To begin making accurate measurements, you only need to select an IV or CV algorithm and push a button.
Room To Grow
The flexibility to tailor a measurement approach also helps reduce cost of test by ensuring you buy only what you currently need, leaving room to grow as your needs change. Because of its low-current, low-voltage, and compensated capacitance capabilities, the B1500A can be used for a range of characterization needs for semiconductor devices and emerging materials, including nanotechnology devices.
An ASU (atto-sense and switch unit) is also available to provide measurement resolution at 0.1-femtoamp (100-attoamps) and 0.5-µV. That's needed for measurements such as MOSFET Idoff and memory-cell leakage characterization. The ASU can be connected to the high-resolution SMU and the CMU so you can switch between precision IV and compensated CV measurements.
Price And Availability
Agilent says its B1500A semiconductor device analyzer is available for order, with pricing starting at $45,000 for a basic 4-SMU IV measurement system, and $58,000 for a basic CV-IV measurement system. Product is expected to ship in August.
For much more info, click here for an in-depth datasheet.
Contact Agilent Technologies, 395 Page Mill Rd., Palo Alto, Calif. 94303. Phone: 800-829-4444. Fax: (650) 752-5300.
Agilent Technologies, 800-829-4444, www.agilent.com/see/parametric