Forksheet CMOS SCM Generator

Import SDE / SCM

Open an .scm file or paste Sentaurus SDE commands. The input is recognised by its content, not its file name, so a pasted fragment and a saved file are handled the same way.

Paste SDE commands

Nothing imported.

Study parameters

The six primary geometry variables of the self-heating study. All lengths are in micrometres (1 nm = 0.001 µm). Every other coordinate in the structure is recomputed from these and from the design constants below.

1 · T_NS — nanosheet thickness

µm

Vertical (Y) extent of each sheet. Sets the sheet pitch, the gate bands and the device height — the dominant term in the thermal path out of the channel.

2 · W_NS — nanosheet width

µm

Transverse (Z) extent of each sheet. Drives the HfO₂ collars, the gate bridges and the pMOS offset.

3 · L_G — gate length

µm

Gated length in X. Sets the channel segment, the gate metal and both junction planes.

4 · T_SPACER — spacer thickness

µm

Si₃N₄ between gate and pad, each side. Also the source-to-gate and drain-to-gate distance, and a poor thermal conductor in the escape path.

5 · L_PAD — source/drain length

µm

Length of each source and drain pad in X. The pad height and width are not independent: they follow the sheet stack and the gate envelope.

6 · N_NS — number of nanosheets

sheets

Sheets per transistor. Every dependent band, spacer piece, collar and doping placement is rebuilt from this. The structured V8 formats are written for 3; other counts emit step-by-step.

Advanced — fixed design constants

These are the constants at the top of the Python generator. They are not part of the study, but they are editable there, so they are editable here too. Changing one recomputes the whole structure.

T_FORK — fork wall thickness

µm

T_IL — interfacial SiO₂

µm

T_HFO2 — HfO₂ collar

µm

T_METAL — gate metal in each gap

µm

T_LINER — SiO₂ gate liner

µm

T_BRIDGE — gate bridge thickness

µm

T_DOMAIN — thermal domain depth

µm

T_WELL — well depth

µm

MESH_MIN_X

µm

MESH_MIN_Y

µm

MESH_MIN_Z

µm

Doping concentrations

Active concentrations in cm⁻³, written straight into the profile definitions and bound to named regions. The channel value is shared by both devices, as are the extension and pad values — the species differ, the magnitudes do not.

N_sub — substrate, Boron

N_wellP — nFET body, Boron

N_wellN — pFET body, Phosphorus

N_chan — channel

N_ext — extensions

N_sd — source/drain pads

The channel is effectively undoped: at 3e17 a 20×6×30 nm channel holds about one dopant atom, so the threshold would be a single-atom lottery. Vt comes from the gate workfunction instead, set in sdevice.cmd.

Generation options

Mode

One at a time varies each parameter while holding the other two at the values above. Full grid takes every combination.

Tick the variables to sweep and give each a comma-separated list. Unticked parameters hold the value set above. A full grid is the product of every ticked list, so it grows quickly — the case count below is live.

T_NS

W_NS

L_G

T_SPACER

L_PAD

N_NS

T_FORK

No cases.

Mesh prefix

auto keeps sweep runs from overwriting each other. A fixed name such as fork1108 matches an existing sdevice.cmd Grid entry.

Custom prefix

writes <prefix>_msh.tdr

Mesh size — target element at the active regions

Scales every sdedr:define-refinement-size in the generated SCM, so it changes the mesh snmesh actually builds. Smaller = finer = more elements and longer solves; larger = coarser = cheaper. The ratios are preserved, so the channel, the gate dielectric and both junctions stay finer than the bulk. 2 nm is the baseline and emits the refinement lines unchanged.

Computed geometry

Structure analysis

Generate or import a structure to measure it.

1 · Structure input

The SCM is the source of truth: the electrodes, regions and mesh filename in the generated deck all come from it. Load the SCM you actually meshed.

Or paste the SCM / SDE script

Nothing loaded.

2 · Detected architecture

Analyze a structure to see its regions, materials and electrodes.

3 · Mesh size

For a structure loaded from elsewhere. If the SCM came from this generator, use the Mesh size control under Generation options instead — that one rewrites the refinement lines directly.

Mesh refinement lives in the SDE script, not in sdevice.cmd — by the time SDevice runs the mesh is already a .tdr file. This slider writes refinement commands to paste into the loaded SCM before meshing.

Target element size at the active regions

2.0 nm

◀ FinefineCoarse ▶

Smaller = finer mesh = higher computational cost. Larger = coarser = cheaper. The bulk and the dielectric are scaled from this, not set to it.

4 · Physics

Isothermal drift-diffusion. These decks carry no Thermodynamic model and no Thermode, so there is no self-heating section.

Mobility: DopingDependence

Mobility: Enormal

Mobility: HighFieldSaturation

Recombination: SRH (DopingDependence)

EffectiveIntrinsicDensity (OldSlotboom)

Temperature

AreaFactor

5 · Gate workfunction

The threshold knob. Applied to every metal region of that gate with a Physics ( Region = ... ) block, so the whole gate shifts together. The idle device keeps its own value so it stays off.

6 · Bias and sweeps

Write deck for

The two devices share one mesh but are simulated separately. pMOS biases are negated automatically.

Saturation |VDS|

Linear |VDS|

Sweep step

CurrentPlot points

Id-Vd gate biases |VGS|

One Id-Vd sweep per value, in order, stepping the gate between them.

Id-Vg at linear VDS

Id-Vg at saturation VDS

Id-Vd family

Field snapshot at the on-state corner

7 · Solver and output

Digits

Iterations

Notdamped

NumberOfThreads

ErrRef (both carriers)

RhsMin

Linear solver

Plot carrier densities

Plot current densities

Plot potential, field and space charge

Plot doping profiles

Plot quasi-Fermi potentials

Plot band edges

Plot mobility

Name	-
Material	-
X min	-
X max	-
Y min	-
Y max	-
Z min	-
Z max	-
X length	-
Y length	-
Z length	-
Volume	-
Doping type	-
Concentration	-
Profile	-