TSMC patent application US20160276285 "Method for forming alignment marks and structure of same" by Cheng-hsien Chou, Sheng-chau Chen, Chun-wei Chang, Kai-chun Hsu, Chih-yu Lai, Wei-cheng Hsu, Hsiao-hui Tseng, Shih Pei Chou, Shyh-fann Ting, Tzu-hsuan Hsu, Ching-chun Wang, Yeur-luen Tu, and Dun-nian Yaung proves that the company prepares STI-less pixel designs: "Embodiments presented below, for example, may describe formation of alignment marks for an image sensor formed without using a shallow trench isolation (STI) process."
Also, TSMC application US20160276382 talks about the STI-less isolation.
Also, TSMC application US20160276382 talks about the STI-less isolation.