Probable value of the resistance offered by substrate

[satishgra]

Hi,

I am working on a mems device and need to model the equivalent lumped model

I wud like to know what is the probable value of the resistance offered by the substrate

Regards,
satish

 

[kspalla]

Check for the conductivity of the material by the Vendor.

 

[satishgra]

Hi,

I am using "silicon" as substrate...I know that the conductivity of silicon is ~0 (from pozar)...how am i going to calculate it from this value given the dimensions of substrate as 350*300*5 (um) ??

Any formula ??

 

[timof]

Hi,

I am using "silicon" as substrate...I know that the conductivity of silicon is ~0 (from pozar)...how am i going to calculate it from this value given the dimensions of substrate as 350*300*5 (um) ??

Any formula ??

Ask your wafer vendor about substrate resistivity, or conductivity, or doping level - silicon substrate are never absolutely pure from impurities, so they have a finite (non-zero) resistivity.

 

[satishgra]

Hey thanks,

what you mean to say is Ideally SI should give you a zero resistivity...but, due to impurities, it can be slightly more

Regards,
satish

 

[timof]

Hey thanks,

what you mean to say is Ideally SI should give you a zero resistivity...but, due to impurities, it can be slightly more

Regards,
satish

No. Ideally pure Si (called intrinsic) has a very high resistivity (at room temperature). Pure silicon is very hard to produce. Silicon wafers are usually doped to a certain level (e.g. 1e14cm-3, 1e15cm-3, or higher), and this doping level (and corresponding conductivity or resistivity) are very tightly controlled by wafer vendors.