STACKED SEMICONDUCTOR STRUCTURE

In some embodiments, the present disclosure relates to an integrated chip structure. The integrated chip structure includes at least one device on a front side of a semiconductor substrate. A plurality of grating layers are under the at least one device. The plurality of grating layers include at least a first material having a first refractive index alternating with a second material having a second refractive index. Contacts extend through an interlevel dielectric material, and further extend through the semiconductor substrate, to directly contact at least one of the first material and the second material below the at least one device and below the semiconductor substrate underlying the interlevel dielectric material.