CPU's on or in silicon chips?

[JacoFett]

If I said ""The CPUs circuitry is located on silicon chips", would this be correct? Or would it be in silicon chips? I need to write an assignment and want to get this fact right. I am very confused, would appreciate it if someone assisted

 

[Ecky]

I'm going to be facetious and suggest you say "of silicon".

http://www.tomshardware.com/picturestory/514-intel-cpu-processor-core-i7.html

EDIT: NOTE I'm not an engineer, just an enthusiast who reads a lot. Take what I have to say with a grain of silicon dioxide.

There's the package or substrate, which is the (usually green) square bit that has all of the pins or connectors. It's usually made of fiberglass, like motherboards, but has been made of ceramic in the past. This serves as a holder for the die.

The die is made of silicon, and contains the electrical circuits responsible for doing useful work. As you can see in the article above, the circuits are "carved" into the silicon, so it's both on the silicon, and in it.

One part I'm a bit fuzzy on is how the die is oriented. It's not shown in the article, but I believe the interconnect-side is placed face down on the substrate, making it a "flip-chip", where it's connected on the bottom.

The opposite of a flip chip is where the interconnects are on top, and the connections to the substrate come out the sides, like this: