I find it surprising that google, amazon and now tesla can enter the « build your own processor » market that easily. Isn’t it more likely that they’re in fact only defining the general spec, and then use the services of other companies specialized in actually designing cpus ?
Tesla hired people who designed chips for Apple and Intel to design their chips. They are designed from the ground up for this application. It seems like they're doing all the chip design in house.
To design your own IC has at the same time become extremely complex and very approachable, if you have the money for it.
A multi-billion transistor CPU is an insanely complex product, there are multiple layers coming together to make it possible. The base layer is the foundry, here TSMC, which does the manufacturing and provides reference design kits. They contain for example the blueprints for transistors and other electrical components. For a digital chips like processors, they are usually used as they come from the foundry.
Next is a layer of software which enables the chip designs, provided by the big EDA companies. This is a rather huge layer, enabling the basic designs on the one side, but also including all kind of simulation and verification tools. And quite some engineering knowledge comes along with it.
So if you want to start designing your own CPU, you still need good engineers who know what they are doing, but large parts of the whole "stack" can and have to bought from the vendors listed above. This enables the quick entries of companies into the market, who were not traditional chip design houses.
