Sony was the first to build a mobile camera with on-chip memory the Motion Eye camera on the Xperia XZ Premium and XZs (later XZ1 too). Now chatter from Korea suggests that Samsung Semiconductors is looking to build a similar camera in November, ready to use in the next-generation Galaxy S phone.
The advantage of on-chip memory is that the camera can store many frames very fast enough to shoot 1,000fps or so for slow-motion video. Streaming those to the main RAM will be too slow, so Sony built a three layer chip pixels, control logic and memory.
Samsungs design is reportedly slightly different. It uses a traditional two layer chip to which a DRAM chip is bonded. Apparently this is to avoid infringing certain patents.
While Samsung’s design is not as sophisticated as Sony’s, the company has an advantage it has in-house factories that produce both image sensors and memory chips. Sony has to rely on Micron for the 1 gigabit memory chip.
Currently, Samsung uses a mix of Samsung and Sony-made sensors on its phones. For example, Korean Galaxy S8 phones come with a Samsung image sensor, the US models have a Sony sensor. The S9 could use all-Samsung sensors if this pans out.
Source (in Korean)