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  1. #1
    Junior Member level 1
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    [Moved from ASIC Design]: How to solve Convergence Problem in SILVACO TCAD?

    I am simulating a circuit using devices designed using SILVACO ATLAS in Mixed Mode. Now, there is no convergence error while finding IV Characteristics of the designed device but when I'm using that particular device in a circuit, on simulation is giving me a message in the Command Bar which states

    Code:
    Warning: Not A Numbers found in currents.
    Simulator did not converge.
    
    Error: No solution possible!
    Try smaller bias step
    I have checked my structure and mesh and have made every other alteration in the mesh and have also changed the bias step but is still giving me the same Warning and Error.

    Is there any other alternate approach to solving this problem apart from changing the mesh and bias step?

    -Thanks in advance

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  2. #2
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    Re: [Moved from ASIC Design]: How to solve Convergence Problem in SILVACO TCAD?

    Can you post your deck?



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  3. #3
    Junior Member level 1
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    Re: [Moved from ASIC Design]: How to solve Convergence Problem in SILVACO TCAD?

    Sure, here is my input deck:

    Code:
    go atlas
    #
    mesh outf=NFeFET.str master.out
    #
    x.m loc=0.0 spacing=0.1
    x.m loc=0.25 spacing=0.1
    x.m loc=0.5 spacing=0.1
    x.m loc=4.5 spacing=0.1
    x.m loc=4.75 spacing=0.1
    x.m loc=5.0 spac=1.0
    #
    y.m loc=-0.2 spacing=0.2
    y.m loc=0.0 spacing=0.2
    y.m loc=5.0 spac=1.0
    #
    #
    region num=1 silicon y.min=0.0
    region num=2 oxide y.max=0.0
    #
    electrode num=3 top x.min=0.5 x.max=4.5 name=gate material=n.poly
    electrode num=4 bottom name=sub
    electrode num=1 x.max=0.25 y.max=0.0 name=source
    electrode num=2 x.min=4.75 y.max=0.0 name=drain
    #
    doping conc=1e15 uniform p.type
    doping gaus conc=1e19 n.type junction=0.4 x.max=0.5 ratio=0.1
    doping gaus conc=1e19 n.type junction=0.4 x.min=4.5 ratio=0.1
    #
    models region=2 ferro
    material region=2 ferro.ec=20e3 ferro.pr=0.08e-6 ferro.ps=0.1e-6 ferro.epsf=92
    #
    
    
    
    
    go atlas
    #
    mesh outf=PFeFET.str
    #
    x.m loc=0.0 spacing=0.1
    x.m loc=0.25 spacing=0.1
    x.m loc=0.5 spacing=0.1
    x.m loc=4.5 spacing=0.1
    x.m loc=4.75 spacing=0.1
    x.m loc=5.0 spac=1.0
    #
    y.m loc=-0.2 spacing=0.2
    y.m loc=0.0 spacing=0.2
    y.m loc=5.0 spac=1.0
    #
    #
    region num=1 silicon y.min=0.0
    region num=2 oxide y.max=0.0
    #
    electrode num=3 top x.min=0.5 x.max=4.5 name=gate material=n.poly
    electrode num=4 bottom name=sub
    electrode num=1 x.max=0.25 y.max=0.0 name=source
    electrode num=2 x.min=4.75 y.max=0.0 name=drain
    #
    doping conc=1e15 uniform n.type
    doping gaus conc=1e19 p.type junction=0.4 x.max=0.5 ratio=0.1
    doping gaus conc=1e19 p.type junction=0.4 x.min=4.5 ratio=0.1
    #
    models region=2 ferro
    material region=2 ferro.ec=20e3 ferro.pr=0.08e-6 ferro.ps=0.1e-6 ferro.epsf=92
    #
    
    
    
    
    
    go atlas
    .begin
    #
    # DC Point Simulation
    #
    va 2 0 0
    ap 3=drain 2=gate 1=source 1=sub infile=PFeFET.str width=12.
    an 3=drain 2=gate 0=source 0=sub infile=NFeFET.str width=8.
    vdd 1 0 2.
    
    .nodeset v(2)=0 v(1)=0 
    
    .numeric vchange=1.
    .options print m2ln noshift 
    
    .save outfile=F1_Combo
    .end
    
    contact device=ap name=gate n.poly
    model device=ap region=2 ferro
    material region=2 ferro.ec=20e3 ferro.pr=0.08e-6 ferro.ps=0.1e-6 ferro.epsf=92
    
    contact device=an name=gate n.poly
    model device=an region=2 ferro
    material region=2 ferro.ec=20e3 ferro.pr=0.08e-6 ferro.ps=0.1e-6 ferro.epsf=92
    
    quit



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  4. #4
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    Re: [Moved from ASIC Design]: How to solve Convergence Problem in SILVACO TCAD?

    same problem,seeking for help



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