Compact Model Council An Industry Standard Approach to Compact Models

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1 Compact Model Council An Industry Standard Approach to Compact Models If your company is not currently a member, please consider our invitation to attend one of our 2013 meetings as a guest. There will be meetings in the US and Japan this year. Contact CMC chairman Keith Green (krg@ti.com) for more information. CMC Accomplishments Since forming in 1995 the CMC s members and consultants have collaborated to develop, maintain, and standardize compact models for widely used semiconductor components: Models available in the Public Domain: MOSFETs: BSIM3 (1995) BSIM4 (2000) PSP (2006) HiSIM2 (2011) BSIM-CMG (2012) SOI MOSFETs: BSIMSOI (2002) HiSIM-SOI (2012) BJTs: MEXTRAM (2004) HICUM (2004) LDMOS: HiSIM_HV (2007) Models available only to CMC Members: MOS Varactor: MOSVAR (2006) Resistors: R2_CMC (2005) R3_CMC (2007) Junction Diodes: DIODE_CMC (2009) Other standards available in the Public Domain Standard SPICE Language (2012) Additionally, the CMC developed guidelines for extracting well-proximity effect model instance parameters and a test suite for verifying the accuracy of Verilog-A implementations in circuit simulators. The CMC is currently working on the selection of new standard models for SOI MOSFETs and ETSOI MOSFETs, as well as a common model interface. How the CMC Operates CMC membership is open to any company with an interest in compact models. Members include foundries, fabless companies, integrated manufactures and EDA vendors. Standard models are selected after a broad search for candidates and a comprehensive evaluation. Final selection is by ballot. The CMC meets quarterly to discuss new models and improvements to existing models. Much of the CMC s work is done by subcommittees of experts. Members can participate in as many subcommittees as they choose. TechAmerica, an accredited standards organization, oversees CMC operations and provides administrative and legal support. Why join the CMC? Standard models make economic sense. They are supported by all major EDA vendors. Foundries only need to support standard models; designers are free to move to the best simulation tool for their work. Members have a say in what models become a standard. Models are continuously improved based on input from large numbers of users. CMC members have the opportunity to request enhancements specific to their needs. Members attend quarterly CMC meetings with leading industry and academic model developers, where they learn about technology developments, often before they are published in the literature. All of the information from the meetings is available to members only on the CMC website. An Invitation Potential members are invited to attend one of our 2013 meetings to learn more about us. Monterey, CA USA, April 18 & 19 Kyoto, Japan, June 13 & 14 Burlingame, CA USA, September 26 & 27 Washington, DC USA, December 12 & 13 CMC Expenses The CMC funds university research to maintain and enhance each CMC model. These funds and the cost of CMC meetings and operations are supported by member dues. Dues for 2013 are $29,000 for a member wishing to have a vote on all CMC models. Members can also pay $13,600, $17,600, $21,600, or $25,600 and select 1, 2, 3, or 4 models, respectively, on which they will have voting rights. All new members must pay a one-time initiation fee of $2000.

2 CMC GaN HEMT Model Requirements Revision History Version Date Author(s) Comments Feb 2011 R. Poore Initial version started from SOI Requirements Draft B Mar 2011 F. Pascale and Updates from National Semiconductor R. Poore Mar 2011 R. Poore Updates from phone conference Mar 2011 K. Green Updates from TI Apr 2011 R. Jones Updates from Raytheon Feb 2013 F. Pascale and S. Mertens Edits for final version Introduction Since its inception, the Compact Model Council (CMC) has supported and standardized silicon compact models. Enough CMC members have decided that gallium nitride (GaN) technology is important enough for their businesses that the CMC should try to develop its first standard III-V transistor model. GaN transistors are high electron mobility transistors (HEMTs), a FET technology based on a heterojunction channel and a Schottky / Insulated / Junction (pgan) gate. The primary use for GaN transistors is for high voltage, high frequency and high power devices. They can also be used for switches and low noise amplifiers. Important figures of merit are P sat (saturated power output), P 1dB (1 db compression point), IP3 (third-order intercept point), gate charge, R DS,ON. Self heating and dynamic trapping effects are some other technology effects that must be accurately modeled. The CMC Standard Model Selection Policy is defined by the CMC Future Committee in its final report. The CMC plans a three-phase process for identification and evaluation of candidate models. Phase I will be a solicitation of available models which meet the fundamental requirements set forth in this document. The GaN Subcommittee will review written proposals and request top candidates present an overview of their model at a CMC Meeting. Candidates identified in Phase I which have sufficient support from CMC sponsors will be subjected to thorough testing in Phases II and III. During Phase II, candidates with at least one industry sponsor will be tested for their ability to fit real data from a technology yet to be identified, physical correctness, continuity, symmetry, and ability to model behaviors. Model developers should be prepared to assist in the evaluation of their models. One or more CMC member companies must serve as a sponsor for each selected candidate, and will provide

3 engineering effort for the evaluation. Model code and documentation will be frozen and made available to all CMC members for review. Phase II results will be presented at a CMC Meeting by model developers and sponsors. During Phase III, candidate models will be evaluated for runtime, convergence, and operability. CMC members will have an opportunity to test the models using their own processes and circuits. The CMC recognizes that runtime and convergence may be dependent on simulation tool and implementation. As such, the CMC encourages assessment by multiple member companies, and will ignore anomalies in runtime or convergence for which there is no explicit correlation to a specific model feature. Phase III results will be presented at a CMC Meeting by model developers and sponsors. Following Phase III presentations, members will vote to select which if any models should be standardized, if and when they demonstrate full compliance to requirements. Models should be selected only if they meet all requirements, or it appears they can be made to meet all requirements within a reasonable time. If you are aware of a model that you believe should be considered, please forward this document to the developer, or contact the GaNFET subcommittee chair, Samuel Mertens (samuel_mertens@agilent.com). If you are the developer of a candidate model and are prepared to dedicate the resources required for the evaluation process, contact Samuel Mertens to indicate your interest as soon as possible. You will be required to provide documentation outlining the high-level formulation of your model and an assessment of how fully your model meets the specific requirements listed in this document, by May 15, If the GaN Subcommittee believes your model is a viable candidate, then you will be notified by June 1, 2013 and asked to present an overview of your model to the CMC membership at one of the CMC meetings in 2013, whichever location and time works best for you. The initial request is for a compact model that specifically models GaN devices. After the CMC evaluates and standardizes a model for GaN HEMTs, the CMC may decide to extend this to all III-V FET/HEMT devices. The ability for the model to generalize from GaN to III-V would be a bonus but is not a strict requirement. Requirements for a Standardization Candidate The CMC recognizes that this document may not contain a complete list of behaviors necessary for these GaN models. Model developers are strongly encouraged to notify the CMC of relevant model features not identified in this document. Basic HEMT Functionality 1. Inputs: standard HEMT layout geometries (Depletion mode, enhancement mode and lateral), terminal voltages, ambient temperature 2. Outputs: all terminal node currents and charges and their derivatives, and a thermal node temperature that may be either internal to the model or externally available for thermal coupling. 3. Utility for GaN HEMT gate lengths, gate-source lengths and gate-drain lengths in common use today and in the next five years. Evaluation will be done with some technology yet to be decided. 4. Support for DC, AC, transient, and noise analyses, as well as ability to run in steady state simulation like harmonic balance and/or pss (shooting).

4 5. In addition to the Core Model Requirements below, include extrinsic device resistances, capacitances, and junction currents appropriate for an industry-standard layout. 6. Support the following external node options: a. drain, gate, source, substrate b. drain, gate, source, substrate, thermal General Requirements 1. Provide as physical a representation of measurement data as possible. Currents, charges, and their derivatives should exhibit physically correct behavior over all operating biases and temperatures and be self consistent. 2. AC, transient and harmonic balance/shooting analyses must be self consistent. 3. Include equations for all physical phenomena in the phenomena lists below. 4. Accurate for second and third derivatives of current at all regional boundary transitions, such as forward/reverse mode boundary, weak/strong inversion boundary, and linear/saturation boundary. Accurate for large signal analysis. 5. Models will be judged primarily on their ability to fit data accurately with a single global set of parameters for all device geometries. 6. Dependence on critical structural dimensions such as gate length, gate-source length, gatedrain length, width, and number of gate fingers should be physically correct. 7. Model parameters should be as physically and structurally meaningful as possible. Where necessary, empirical or mathematical parameters may be used to enable a better fit for real deviations from ideal physical behavior. 8. The model formulation must be such that solutions are found efficiently (runtime) and easily (convergence) in DC, AC, transient and harmonic balance/shooting operation. Outside of normal device operation conditions, the model should give results that aid convergence. 9. Parameters should be as uncorrelated and few in number as necessary for precise fitting of measured data. 10. Model extraction should be quick and simple, requiring as little iteration as possible. 11. The model extraction methodology should be documented. 12. Since HEMTs are unipolar devices, only electrons have high mobility, and industry does not fabricate complementary processes, only the N-type HEMT needs to be modeled. 13. Support for both depletion mode and enhancement mode HEMTs with Schottky gate, insulated gate, or junction gate (pgan). Support for lateral architectures. 14. Reverse source/drain operation physically correct I-V and C-V characteristics for V DS <0 as well as V DS >0. Core Model Requirements 1. As exact, complete, and simple a representation of physical GaN HEMT behavior as possible. 2. Extensibility of the model from GaN to all III-V FET/HEMT structures would be an added benefit but is not a strict requirement. 3. Physically correct in all operating regions. 4. No unphysical behavior: a. No unintended asymmetry in source/drain b. No discontinuities in charges or currents through third order derivatives 5. As computationally efficient as possible. 6. Model should be charge based and not capacitance based, and charge conserving.

5 Support Requirements 1. A CMC member company must agree to sponsor the model during Phases II and III. 2. Frozen source model code and documentation must be made available to all CMC members at the beginning of Phase II without requiring legal documents or agreements. The CMC members must treat these as confidential and proprietary information. 3. The model must be available to CMC members in Verilog-A at the beginning of Phase II, and available in at least one commercial simulator as well as Verilog-A format at the beginning of Phase III. 4. If selected as a CMC standard, the code and documentation must meet the CMC s standard developer agreement requirements for public availability. 5. Model documentation must include all model equations, an explanation of equations, parameter extraction procedures, and User s Guide. 6. A university must be identified that is willing to accept long-term support of the standardized model. Fundamental Phenomenon List These effects are considered fundamental to the operation of GaN HEMT devices, and should be considered an integral part of the core model. These fundamentals will be verified in Phase II as part of the standardization process. 1. Temperature dependence 2. Self heating, with the thermal node optionally available as an external node 3. Dynamic trapping effects gate/drain lag, dynamic R DS,ON degradation, dispersion, etc. 4. Bias dependence of drain-source resistance and all capacitances (gate-drain, gate-source, drain-source) 5. Subthreshold modeling 6. High power operation P sat, P 1dB, IP3, gain, PAE (or drain efficiency), Id, and Ig vs. input drive level under different harmonic input and output loading conditions 7. Schottky gate current or any other gate leakage mechanism (e.g. tunneling) under both forward and reverse bias conditions 8. Noise sources for all conduction mechanisms 9. Parasitic gate, source, drain and substrate resistances 10. High voltage including breakdown and leakage between all terminals (drain-source, draingate, gate-source, drain-substrate); there could be significant leakage currents between terminals prior to breakdown that needs to be modeled correctly 11. Asymmetric source/drain 12. Reverse operation (V DS <0) and appropriate derivative continuity across V DS =0 13. Support for field plates, both gate- and source-connected configurations 14. Large periphery/large unit gate width scaling with trapping or mechanical stress effects Supplemental Phenomenon List These effects are required for a complete GaN model, but because the CMC believes they may be added without changing the fundamental core formulations, they are considered supplemental, and are not required for a model to pass evaluation tests in Phases II or III, or to be selected for standardization. The CMC may request implementation of these supplemental phenomena prior to standardization. 1. High frequency (distributed, non-quasi-static) effects f T, f MAX, R G, etc.

6 GaN HEMT Tests The fundamental phenomena must be shown to exhibit the following electrical behaviors. Measurement data may not be available which exhibits all of these effects, but the model should be prepared to fit data for any of these effects, and in the absence of data must at least show model playbacks exhibiting these effects. 1. Static I-V and pulse I-V, including current kinks related to self heating, dynamic trapping, and impact ionization effects 2. Large signal measurements of one-tone power compression and harmonics as well as intermodulation characteristics (two-tone tone IP3 for simple test, ACPR for complex modulation test) 3. Cgs, Cgd, Cds, Cdsub versus bias and frequency 4. gm, gds versus bias and frequency 5. Operation over temperature, especially at high temperatures 6. Operation at high voltages and high electric fields, including breakdown behavior between all terminals 7. Transient simulations for turn-on and turn-off switching behavior 8. Thermal, shot, and 1/f noise 9. Correct geometric interpretation and bias dependence of extrinsic parasitic resistance and capacitance models Requirements for Support of a Standard Model These requirements apply after a model has been selected as a standard. However, a model will not be selected as a standard unless the CMC is convinced the following criteria will be met after selection. The CMC expects to provide funding for support of no more than one standard model. References 1. Support requirements do not have to be met during candidate selection, or candidate evaluation period, but a university willing to provide this support must be identified during the evaluation period. 2. Code and documentation must be available for download from a website. 3. Extraction procedures for model parameters must be developed and documented 4. User s Guide must be maintained. 5. A quality assurance (QA) test suite must be released with the model and maintained, using the format already specified by the CMC QA and Release subcommittee. 6. Version control and model release schedules must be coordinated with CMC. Changes must be documented with each new release of model code. 7. Bug reports must be documented, tracked, and investigated. Fixes to verified bugs must be documented. 8. Model enhancements requested by the CMC must be implemented, including extraction procedures for new parameters. 9. Representatives must attend CMC meetings to present on the status of model development and discuss proposed model updates. [1] L Duleavy, C Baylis, W Curtice and R Connick, Modeling GaN: Powerful but Challenging, IEEE Microwave Magazine, Oct 2010, pp [2] A Katz and M Franco, GaN Comes of Age, IEEE Microwave Magazine, Dec 2010, pp S24-S34.