MEASURE DC CURVES OF BJT

EXTRACT SPICE MODEL

SIMULATE ELDO MODEL

GET BIAS CONDITIONS FOR SIMS FROM MEAS.

QA MODEL

REPEAT ~150 TIMES (PROCESS,

CURVES, TEMPERATURE)

PUBLISH MODEL RESULTS ON WEB

Abstract

Automation Of BJT PNP Silicon versus SimulationWilliam Berry, Alex Chee, Chris Soh, Dalton Young

Industry Advisor: Mr. Bob Peddenpohl; Faculty Advisor: Dr. Joseph Elias

New Method

Technical Description

High Level Design

Objective

Sponsors

Acknowledgement

Conclusion

During semiconductor design, it is necessary to compare data from physical testing of a device to simulation data to validate simulation SPICE models for future designs. Historically, the BJT versus silicon measurement comparisons at Cypress Semiconductor have been done either manually, with all running simulations, formatting data, and plotting data performed by an engineer; or autonomously, with non-native simulation tools which are used specifically to avoid the manual process. This project aims to automate the process of formatting the measured data file from an HP 4156 Semiconductor Parametric Analyzer, performing the simulations across Cypress’ process models of a device using Mentor’s Eldo SPICE circuit simulator, formatting and plotting the output data from simulations alongside the original measured data, and arranging the plots and data in an intuitive format for Cypress design engineers (an existing Cypress format).

The objective of this project is to save money and increase productivity for Cypress Semiconductor. On average, Cypress creates BJT models once a quarter, and this task takes an engineer 1 day, with a cost of approximately $1K. Bigger savings to Cypress, however, come through quality assurance of the SPICE model. In the most extreme case, an inaccurate SPICE model could result in a new all-layer tapeout that would cost Cypress approximately $500K for a new mask set.

The new process is started by initial input from the HP4156 Semiconductor Parametric Analyzer. The HP4156 generates data files of parametric sweeps from a silicon-based BJT, for which Cypress develops SPICE models. This HP4156 data file is then read and split into the different plot types which were taken on the analyzer, and each of the measured data sets is simulated using Mentor’s Eldo circuit simulation tool. Simulations are performed for different process models developed by Cypress for the different plot types using a load-balancing tool across a cluster, and the resulting data is then formatted and plotted using the gnuplot plotting program. The final plots and their data are then arranged into an HTML page for design engineers to use and present. The program was developed to be very modular, as seen in the communication between phases above. All data is passed through the central data-handling mechanism, making the addition of new processes or methods simple. Inside that mechanism, data is separated on a per-plot basis, making modification of a single class of plots, or addition of new plot types and functions, very simple for future work.

A high-level view of the automation process

(ABOVE) A comparison of the old and new methods. Note especially the red boxes, which mark particularly time-consuming or tedious processes that are eliminated by this automation.

(ABOVE) The Final Results: A Beta-Ic (Gain) Plot, an Ib,Ic-Vbe (Gummel) Plot, and an Ic-Vce (Characteristic) Plot, as generated by the program.

(BELOW) The HP4156 Semiconductor Parametric Analyzer, in use.

The actual process consists of four phases to get from start to finish. The phases were created in parallel, but are made to run end-to-end, with each one processing or manipulating the data generated by the previous phase. As seen above phase one of the process consists of parsing BSIMPRO++ measured data files (from HP4156) and creating metafiles (data files in memory) in the metafile handler for each plot to be made. Bias conditions and other information are also extracted in phase one. Phase two consists of creating the circuit files for each type of plot to simulate and running the actual Eldo simulations for all the specified process models (specified in the user control file) using the load-balancer, as well as collecting the data post-simulation. Phase three consists of plotting all the data into .png files using gnuplot and generating .csv data files corresponding to the plots. Phase four consists of generating the actual HTML webpage and linking to the data (again, in a familiar format for Cypress design engineers).

A detailed view of the process, in phases

The group would like to thank both Eta Kappa Nu and Cypress Semiconductor for sponsoring EE 499.

The group would like to acknowledge the following people for their invaluable assistance on the project:

Mr. Bob Peddenpohl, for his continual guidance and assistance.

Dr. Joseph Elias, for helping to guide the group during the early development stages.

Dr. Regina Hannemann, for her assistance in keeping the group on-task and up-to-date with required reports and reviews.

vs. Old Method

The program has been completed, and has been used for the Cypress Semiconductor 150nm programmable technology. Of the original deliverables specified, all will be delivered before the end of the semester, and only the user document has taken extra time. The program will meet all specifications provided by Cypress, and should be extensible for future use.

Future Work

Due to its modular construction, there is already discussion of modifying the existing code to process npn-type devices, as well as handle new plot-types and input file formats.

LOAD SIM & MEAS INTO EXCEL

MEASURE DC CURVES OF BJT

EXTRACT SPICE MODEL

RUN PROGRAM

QA MODEL

PUBLISH MODEL RESULTS ON WEB