What is the difference between LVS and ERC ?

[MubarakKhan]

What is the difference between LVS and ERC?
is ERC is part of LVS or it is a separate check?
in Assura, I can see two-run options (Run LVS & Run ERC).
with the help of switch option, I can check antenna error while (I'm assuming it is ERC) running DRC.

 

[erikl]

- LVS means Layout versus Schematic comparison
- ERC means Electrical Rules' Check
- DRC means layout Design Rules' Check

These all are necessary checks with their own rules' sets. Depending on the PDK set-up, they can be called as separate checks, or all together (in series).

- ARC, the Antenna Rules' Check actually is an electrical safety check (for safe silicon production), but uses layout design rules.

 

[timof]

To extend a little bit (or to give examples of checks) on what erikl already explained:

* LVS (Layout Versus Schematic comparison) - does the following things:

- net connectivity extraction (determines the connectivity between the polygons)
- device recognition (identifies the devices - like MOSFET, design resistors, design capacitor, diodes, etc.)
- layer derivation (for example, calculates gate poly and field poly layers from poly and active layers)
- cross-referencing between schematic and layout
- calculates layout-dependent instance parameters for device instances (such as gate width and length, area/perimeter for source/drain, well proximity effect, LOD effect, etc.)
- etc.

* DRC (Design Rule Checking) - checks various rules, such as:

- metal line widths
- spacings between different layers
- metal density
- etc.

(in modern technologies there thousands or tens of thousands of such rules)


* ERC (Electrical Rule Checks) - verifies various things related to electrical behavior:

- resistance rules (e.g. resistance from a pad to ESD diodes, from ESD diodes to power clamps, resistance to guard rings, etc.)
- current density rules (ESD current densities, etc.)
- voltage polarity checks (for example - checks that one of the parasitic diodes are forward biased)
- voltage domains checks
- latchup checks
- etc.

Max