Capacitor structure, image sensor structure, and method for forming image sensor structure

An image sensor structure, comprising:

• a semiconductor substrate;
• a plurality of image sensing elements over the semiconductor substrate;
• a capacitor layer between the semiconductor substrate and the image sensing elements;
• and
• a dielectric structure encapsulating the capacitor layer, wherein a sidewall of the capacitor layer is spaced apart from the dielectric structure by a gap.

A method for forming an image sensor structure, comprising:

• forming a capacitor layer over a semiconductor substrate;
• forming a dielectric structure encapsulating the capacitor layer, wherein a sidewall of the capacitor layer is spaced apart from the dielectric structure by a gap;
• and
• forming a plurality of image sensing elements over the capacitor layer.