A method of manufacturing a semiconductor structure includes receiving a first substrate including a dielectric layer disposed over the first substrate; forming a sensing structure and a bonding structure over the dielectric layer; disposing a conductive layer on the sensing structure; disposing a barrier layer over the dielectric layer; removing a first portion of the barrier layer to at least partially expose the conductive layer on the sensing structure; and removing a second portion of the barrier layer to at least partially expose the bonding structure.