They were originally manufactured by Aptina for Nikon, using Nikon additions and changes to Aptina designs. If you're surprised by this answer you shouldn't be: Nikon has had sensor design teams going back to at least 1988. Those teams have produced five Nikon-only sensors and have worked with at least four other partners on others.
Aptina was acquired in 2015 and began to shut down its camera sensor work. The latest Nikon 1 model, the J5, uses a Sony EXMOR sensor instead of Aptina.