The present disclosure relates to a CMOS image sensor having a multiple deep trench isolation (MDTI) structure, and an associated method of formation. In some embodiments, a plurality of pixel regions is disposed within a substrate and respectively comprising a photodiode. A boundary deep trench isolation (BDTI) structure is disposed between adjacent pixel regions, extending from a back-side of the substrate to a first depth within the substrate, and surrounding the photodiode. A multiple deep trench isolation (MDTI) structure is disposed within the individual pixel region, extending from the back-side of the substrate to a second depth within the substrate, and overlying the photodiode. A dielectric layer fills in a BDTI trench of the BDTI structure and a MDTI trench of the MDTI structure.