I understand that the price of silicon doesn't always scale linearly with its size/number of components, but I'm just genuinely curious as to why we haven't seen any digital camera sensors at true medium format sizes yet. It seems even the high-end camera makers are pushing some sort of current upper limit in sensor size, as the camera with the largest sensor size I can find, the Phase One IQ4, a $50,000 camera, has a sensor size just under 645 film size.
I'd think that the bigger the sensor, the better the image quality, and hence there'd be a market for professional photographers looking to differentiate themselves from the competition. So one would think there's a market incentive to produce sensors corresponding to some of the larger film sizes.
Is it mainly economies of scale that are just making it expensive to produce certain sizes of sensors which are currently not mass produced? Do factories have to be updated to facilitate production of these larger sensors? Or is there some limitation with existing fabrication techniques that keeps companies from making an arbitrarily large CMOS sensor?