The first few generations of DRAM used the same fabs as logic circuits. But the capacitor for each bit took proportionally a larger and larger area with newer processes. So they came up with the idea of making the capacitors vertical instead of horizontal (essentially a deep well into the silicon with the capacitor actually being the walls of the well) and the steps became different.
You can still make DRAMs with the logic process (normally for the last level caches) but it will be less efficient than the dedicated process.
You can still make DRAMs with the logic process (normally for the last level caches) but it will be less efficient than the dedicated process.