This sensor design vs sensor fab. vs stepper maker question keeps coming up, so here is a summary as I understand it:
1. Nikon designs some of its own high end sensors, but out-sources their fabrication, and outsources sensors for its lower priced DSLR models and compacts from Sony, sometimes with Nikon input on design customizations.
2. Canon does similarly, but with more in-house: it designs and manufacture all its own DSLR sensors, but at the lower end of the product range, Canon outsources the sensors for most of its compacts, again from Sony.
3. Outsourcing sensor fab. is no big deal: there are multiple foundries that can make sensors once one gives them the design, so there is no reason to think that Nikon is tied to Sony for fab. of its sensors. In fact, I would bet that Nikon can get the fab. done cheaper in Korea or Taiwan or China.
4. Nikon and Canon both make steppers, so quite likely Canon uses its own steppers, though it seems to be struggling a bit in the stepper business, in which ASML and Nikon are the top two (ASML well ahead as #1.)
5. To those who insist that it is always best to do everything in-house, never outsourcing, I have one word: "Apple". The turn-around of Apple from its dark days was driven in part by Tim Cook's initiative to get Apple out of the manufacturing business entirely, outsourcing to the most cost-effective suppliers and assembly plants. Even fab. of its own new A4 chip design for iPhone/iPad/iPod is outsourced ... ironically from Apple's smart phone and tablet rival, Samsung. And Apple seems be surviving!