Choose the right capacitor

Hello all,
I have a question about capacitors :
i saw a design that use for decoupling capacitor on op amp a standard ceramic cap and a tantal one with a serial resistor. What is the role of it ? ESR compensation ? I thought that tantalum cap need some precautions when used with others caps ...

Should I prefer the ceramic one for op amp decoupling ? (some of them have a high value up to 10µF, is it better than tantalum cap for noise consideration for example ?)

regards

The resistor and capacitor is probably to filter noise from the supply lines. Without the resistor, the capacitors would be filtering the whole supply, sometimes it's better to concentrate the filtering on a specific part, such as your op-amp and low value resistors create crude low pass filters, cleaning just the amps supply lines. The resistors are usually low in value so they don't have too much effect on the DC conditions.
The reason for two capacitors is simple, in general (there are exceptions) higher value capacitors are better as reservoirs to dampen low frequency noise but their impedance increases as the frequency gets high due to their inductance and ESR. On the other hand, ceramic capacitors work the other way around, they are good filters at high frequency but usually lack the storage capability needed to smooth low frequency noise. By putting both types in parallel, you get the best overall performance, as one loses efficiency, the other takes over.
Brian.