HINTS & TIPS

Q: I would like to make DC measurements above 100mA by using UTMOST and the HP4155/56 DC Parameter Analyzer. What is the recommended measurement procedure?

A: High current measurements with the HP4155/56 can be achieved by using a High Power SMU (HPSMU) and the Ground Unit together. The HPSMUs can force and measure currents up to 1A and the Ground Unit can sink currents up to 1.6A. The HPSMU and Ground unit should be on the same current path as the DUT. For example, in Bipolar devices the HPSMU should be connected to the Collector and the Ground Unit should be connected to the Emitter terminals. In MOS devices the HPSMU should be connected to the Drain and Ground Unit should be connected to the Source terminal. The Ground unit does not have a measurement capability. Therefore the HPSMU should be connected to the terminal at which the current needs to measured.

The addition of the Ground Unit to the UTMOST HP4155/56 driver is completed. This feature is available in the current development version of UTMOST. This version of UTMOST can be made available to customers who request it.

The HP4155/56 DC Parameter Analyzer can have up to six SMUs. HPSMUs are usually connected to SMU5 or SMU6. In the UTMOST HP4155/56 driver, SMU0 is assigned to the Ground Unit. Typical SMU settings for a high current bipolar device measurement are provided in Figure 1. Please note that the Emitter terminal is connected to the Ground Unit and is represented as SMU0 in the UTMOST SMU definition screen.

Figure 1. The HP4156 SMU Definition Screen.


Q: Can we utilize the BSIM3 Extraction Routine in UTMOST to convert the HSPICE Level 28 model parameters to BSIM3 parameters?

 

A: Yes, BSIM3 routine can be used efficiently for model conversion. Please follow the steps provided below to convert HSPICE Level 28 model parameters to BSIM3 parameters:

  • Start VYPER and select Net Setup from the "Files" menu of VYPER. This will open the "VYPER configuration screen". Select UTMOST press the "Connect" button. Select a version of UTMOST which is 10.10.1 or greater. Press the "Apply" button to make the connection.
  • By following a similar procedure to that described in Step 1 connect the HSPICE circuit simulator. Make sure to enter the correct "Path to HSPICE location" and "Host name". For more information on "Connecting HSPICE as an External Simulator to UTMOST" please refer to the UTMOST Extraction Manual Volume 3, Appendix F.
  • Start the UTMOST interactive MOS Technology and load a setup file.
  • Press the "System" button. This will open the "Common Control Screen". Toggle the "Get Raw Data" button until it reads "Simulation" and toggle the "Spice Models" button until it reads "External SPICE".
  • Select the "Spice Model File" from the UTMOST Files Menu. This should open the "Spice Screen". Highlight HSPICE and the Level 28 model. Press the "Load Model" button. This will load the Level 28 default model parameters into the parameters screen of UTMOST.
  • Select the "Spice Library File" from the UTMOST Files Menu. Load the Level 28 parameters which need to be converted. For more information on loading the SPICE Library Files please refer to the UTMOST User's Manual page 2-12.
  • Press the "Setups" button from the Main UTMOST screen. This will open the "Setup and Result" screen. Select the BSIM3 Routine and press the "Set Measurem." button to open the "DC measurement Screen". Set the bias conditions according to the process specifications. For more information on the bias settings for the BSIM3 Routine please refer to the UTMOST Extraction Manual, Volume 1 page 6-187. Press the "Fit Vars." button from the "DC measurement Screen". This will open the "Fit Variables" Screen. Set the "Meas.&extract" variable to "0" (Figure 2). This will ensure that UTMOST will not extract BSIM3 model parameters immediately after simulation with the Level 28 parameters but only generate measurement data for the BSIM3 extraction.

Figure 2. The BSIM3 Fit Variables Screen.

  • Press the "Strategy" button to open the "Model Strategy" screen and select the required geometries. There should be at least two devices with common L and two devices with common W.
  • Press the "Output Log Files" button to open the "Output Log File Screen". Type in a Log File Name and Press the "Open New" button. This will open a log file where the simulated data will be stored.
  • Press the "Extraction" button from the main UTMOST window. This will open the "Extraction Screen". Select the "BSIM3" routine only. Press the "Measure" button. This will start the simulated data generation with the External HSPICE Level28 parameters.
  • After the simulation for the last device is completed open the "Output Log File Screen" and press the "Close File" button.
  • Toggle the "Get Raw Data" Button until it reads "Log File" and toggle the "Spice Models" button until it reads "External Models" in the "Common Control Screen".
  • Select the "Spice Model File" option in the UTMOST Files Menu. This should open the "Spice Screen". Highlight SmartSpice and the BSIM3 model. Press the "Load Model" button. This will load the BSIM3 default model parameters into the parameters screen of UTMOST. Modify the parameters such as TOX, XJ, NPEAK and NSUB according to the process specifications.
  • Load the generated Log File using the UTMOST File Manager.
  • Open the "Fit Variables Screen" of the BSIM3 routine and set the "Meas.&extract" variable to "1" (Figure 2). This will activate the parameter extraction feature of the BSIM3 routine.
  • Press the "Measure" button from the "Extraction Screen". This will start the reading of the data from the log file and the subsequent extraction of the BSIM3 parameters. For more information on the BSIM3 parameter extraction please refer to the UTMOST Extraction Manual, Volume 1, page 6-187.
  • After the extraction is completed the same data file can be used in the ALL_DC Routines to compare the Level 28 and BSIM3 simulation results or to refine the results using parameter optimization.