How to set the model parameter STIMOD in simulation?

[Alex Liao]

Hi,

The STIMOD is the LOD stress effect model selector. I can view this after any simulation by printing the model parameter in virtuoso ADE. But I have checked the modelfile.scs which is included in any simulation. It is BSIM4.5 and no such selector found in it. Is there anybody who knows how to set this STIMOD? If it is in print MODEL parameter, it should come from somewhere. Anyone who has knowledge and presents here is highly appreciated.

Thanks,
Alex

 

[erikl]

Search this Reference Manual for STIMOD.

 

[Alex Liao]

Hi erikl, Thank you. But my simulator is spectre from Cadence and your file is Hspice from Synopsys. In fact, in Hspice, one could change two instance parameters, Mulu0 and Delvth0 which represent STI strain influence on mobility and vth0. The two parameters can be found in Hspice net list and thus the performance of the design is affected. However in Spectre, even I could find these two in Spectre Manual but they are not in net list or print model parameters field. So there is no way to affect the performance via changing these two. Neither, I cannot found any stress/strain-related parameter in Spectre like its the two in Hspice net list. Are you familiar with Spectre and do you have any clue on the STI-related parameter which is user-customized in simulation model or netlist? The reason for this is because I have calculated my version of mobility under STI effect but I do not know how to put my value into anywhere in simulation. Further, I cannot confirm my mobility value because it is invisible in Spectre to me.

 

[erikl]

Are you familiar with Spectre ...

Just a little. You can force Spectre to use (H)SPICE netlists with the command

simulator lang=spice

and do you have any clue on the STI-related parameter which is user-customized in simulation model or netlist?

Sorry, no.

 

[Alex Liao]

Just a little. You can force Spectre to use (H)SPICE netlists with the command

simulator lang=spice

Sorry, no.

Hi erikl, now I can change my simulator to HspiceD Version 2010. Is this the simulator that you mostly use? One problem for this is that I cannot perform Print Model Parameter unlike using Spectre. Do you know an alternative way to print Model parameter. Another problem is even I tried to observe the Hspice Model card, I failed to find STIMOD selector. But your manual which is also Version 2012 indicates that STIMOD exists. Since you may be more familiar with Hpice, do you know how to change default STIMOD in Hspice?

Thanks,
Alex

 

[erikl]

... do you know how to change default STIMOD in Hspice?

Alex: This is described in the above linked manual (version Dec-2010). See pages 432 (456 in the PDF rep.) & 481-482 (505-506) !

 

[Alex Liao]

Erikl, actually, I have noticed this before and I tried in this way. First, I put STIMOD =0 in one bin pch.14 PMOS (section in model card) and keep monitoring this device in hspice.out after simulation. Second, from the figure, you can see that I have replaced section = tt by my own model card which has STIMOD = 0 (Default value is 1). I am sure I put two STIMO = 0 in mismatch section and standard section within .MODEL pch.14 PMOS. Still, the result shows an unchanged STIMOD. I do not know why I failed changing it.

Regards,
Alex.

 

[erikl]

... the result shows an unchanged STIMOD. I do not know why I failed changing it.

It's not your fault: Level 54 is a BSIM4 model. On page 481 (PDF: 505) the a.m. manual says: If VERSION>=4.3, the STI model is not dependent on STIMOD=0 or 1. So if your simulator uses a BSIM VERSION>=4.3 , STIMOD will automatically be reset to 1 , s. p. 482/506 , i.e. UCB's STI model usage will be enforced.

Seems you need a BSIM VERSION<4.3 to disable the STI effect simulation with STIMOD=0 . But I don't know where you can change the BSIM VERSION. Perhaps with an older HSPICE version?

 

[Alex Liao]

Erikl, I am consulting Cadence engineer, who knows whether this rule applies on spectre. I guess the way spectre and hspice dealing with STIMOD is similar. If New version of BSIM4 (>=4.3) is stimod un-customer-editable. Then I have to go back to older version to try for any simulator. I tried modifying sitmod =2 in spectre-associated model card in every section where necessary, but I filed to change it as well. Anyway I would like to share this experience with you once I get the answer from Cadence.

Regards,
Alex