Layout questions about widths and resistors

Dear all,
I have some quesiton.
1.If I have two block(analog and digital), My digital block has nor gate, nand gate and inverter gate. How much width do my power (vdd and ground)? I use tsmc 0.18µm.
2.If I have six metals, which metal have low resistor? Metal1 or metal6
3.How do I decide my power ring width?
4.Which material is Gurad ring? How do I draw?
Thanks.

Re: layout question

Dear ilter,

the following are the answers to your questions:

1.If I have two block(analog and digital), My digital block has nor gate, nand gate and inverter gate. How much width do my power (vdd and ground)? I use tsmc 0.18µm.

The width of the metal for power routing depends on how much current the gates draw. If you are working at reasonable speeds, i do not think that the metal width will be beyond 1um for each gate.

2.If I have six metals, which metal have low resistor? Metal1 or metal6
Obviously metal 6 will have the least resistance. Hence for top level routing use metal 6. But I would suggest that you use metal 5 instead. Keep metal 6 for any options.

3.How do I decide my power ring width?
The power ring width depends on the total current drawn from the chip. Usually it is about 1u thickness for a 1mA current drawn from power supplies.

4.Which material is Gurad ring? How do I draw?

Guard ring is actually diffusion(active) material. So, using the diffusion, you form rings and place as many number of contacts and then route it with the metal. The guard rings will be of p-type for the VSS connections and n-type(inside the n-well) for P-type connections.

I hope that I am clear

layout question

For power rings question, you also need to be carefully about the voltage drop from the pad. Also 1uA/1um can work for 0.18um, but for 0.13um, the metal is thinner.

Re: layout question

process reference manual have the info you needed on resistance and layer, you should follow that data, in addition to suggestion you received.

layout question

you need look through the design rule. in the document, there is these information.

Re: layout question

Vamsi,
what are these metal options that u were talking about? when and why are they used?