PHILIPS Model 9 New MM9 Extraction Routine in UTMOST III

Part II

Introduction



This is the continuation of the same article printed in the previous issue of the Simulation Standard (October, 1998).

Philips Level 9 model is widely used as an accurate deep submicron CMOS model. The model is physical, and as such lands itself to accurate extraction methodologies. This paper describes, step by step, an extraction methodology that was developed in collaboration with an industrial partner, and has been validated for its accuracy




Strategy #8: Subthreshold region I subth_highVB_mm9_min





Figure 1. subth_highVB_mm9_min Local Optimization Definition.






This strategy must be used at the end of the local optimization sequence.

The optimized parameter is: VSBTR. This parameter will not be optimized on a long and wide device.

We work on ISUB/VGS for different VDS and at VBS=0V.




Strategy #9: Substrate current I isub_mm9_min.





Figure 2. isub_mm9_min Local Optimization Definition.






The optimized parameters are: A1R, A2R, A3R. Take care that A1R and A2R are strongly correlated. So, this strategy may need to be modified for each device.

The Optimization Sequence

An example of optimization sequence is given on the next figures. The order here is important. The first strategy should be #1 or #2, depending on body effect observed on our devices. But only one of these should be present in the sequence. Then #3 should be the second strategy. #4, #5, #6 must follow in the sequence. Utmost III will recognize itself the type of device it is displaying, and so which strategy to apply. Only one will be executed for a given device. Then #7 should follow. #9 is optional, but is strongly recommended. #8 must be the last strategy of this sequence.




Figure 3. Local Optimization Sequence recommended




At the end of each miniset extraction, the parameters are stored in the Optimized column and also in a library file whose name is specified in the Spice Library File. If that library already exists, Utmost III will append the minisets so extracted to the library. The default library file name, if not set by the user, is "SetupFileName.l". The graphic screen shows you the result of the optimization as you can see on the next figure.

You can also extract the miniset on only one device. You have to know that among the strategies for the gds optimization, #6 for narrow device will be executed whatever can be the type of the device displayed. In that case, you can easily adapt this strategy to obtain a good miniset.




Figure 4. Graphic Screen after a Miniset Extraction on a short device




Maxiset Extraction

Each parameter of the MOS Level 9 model can be expressed as:



Where LER and WER are respectively the reference effective length and width. The whole set of parameters (parameter for reference transistor and scaling parameters) constitute the maxiset. This equation may be slightly different for some parameters. But in any case, a simple regression will be sufficient to calculate all the scaling parameters.





Figure 5. Fitting Variables Table





Fitting Variables

Once the miniset extraction is completed, the maxiset procedure is called. For that matter, we need to fix some fitting variables. These variables are listed below.

 1

Meas.&Extract  0 for measurement only; 1 for miniset extraction

 2

 Extrfromlibfi  1 for maxiset extraction from the library file ; 0 false

 3

 lref  Reference length for maxiset

 4

 wref  Reference width for maxiset

 5

 TR  Reference Temperature

 6

 PHIBR  Reference fb. Default: 0.65V