Bulk contacts on the Standard cells

[sudeep_]

Hi,

anyone help me how to add bulk contacts on the Standard cells. suppose,
i would like to select one D flip flop from Cadence STM Standard cells (65nm) in to my design (for Counter).
But Standard cells did not have bulk contacts, how can i add bulk contacts on the D-Flipflop Standard cell.

I needed to check LVS.

Thanks!

 

[Yarrow]

To my knowledge LVS i tricky when using standard cells from fab ( I take it you only see the abstract view and not the full layout?) If so you need to use a black box approach where you treat the std cells as black boxes with IO.

When it comes to the physical bulk contacts, in a place and route tool, these are usually placed in the same way as filler cells. So you have your row with DFFs and power rails, then you place the power cell (with bulk contacts) every lets say 20 um in between your DFFs, depending on your requirements.

The power cell (dont remember the correct term of this cell) is a cell that connects the VDD rail to the NWELL and the GND rail to the SUBSTRATE.

 

[sudeep_]

I used Cadence SOC Encounter for generating layout, after gds file is imported into Cadence ADE for LVS. I did not added bulk contacts in Cadence SOC Encounter.
Could you tell me how to add bulk contacts in SOC Encounter on the Standard cells.

To my knowledge LVS i tricky when using standard cells from fab ( I take it you only see the abstract view and not the full layout?) If so you need to use a black box approach where you treat the std cells as black boxes with IO.

When it comes to the physical bulk contacts, in a place and route tool, these are usually placed in the same way as filler cells. So you have your row with DFFs and power rails, then you place the power cell (with bulk contacts) every lets say 20 um in between your DFFs, depending on your requirements.

The power cell (dont remember the correct term of this cell) is a cell that connects the VDD rail to the NWELL and the GND rail to the SUBSTRATE.

 

[whenkey]

you have to use well tap (well tie) well to add bulk contact.

 

[sudeep_]

Thanks whenkey,
Can you give any suitable command or GUI instructions for adding bulk contacts,
In my manual it does not show about well tap, can you give more Information about this (is it placing after power rails or Standard cells)

you have to use well tap (well tie) well to add bulk contact.

 

[whenkey]

i also dont have idea about tool commands. generally after building power grid, in each standard cell row for fixed distances well tie cells are added. In attached figure all the substrates are internally connected together (continuous N-Well or P-Well) and connected to a single well tie cell. which gives physical connection to all substrates in that row.