Is there any capicitor in a digital IC?

Question

If no, what cause the delay between the input and output?

Answer 1

there are some small value caps. Dynamic RAM chips have lots of caps, as they are how the data are stored.

Delays have other causes. Every transistor causes a delay due to it's finite switching time.

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Answer 2

There are few deliberate capacitors since they take a lot of chip space, however the gate of every MOS transistor is a tiny capacitor.