Biological sensing structures

A biological sensing structure comprising:

• a mesa in a substrate;
• a first light reflecting layer over a top surface and sidewall surface of the mesa;
• a first opening in the first light reflecting layer, wherein the first opening exposes a first portion of the top surface of the mesa;
• a second light reflecting layer over the first light reflecting layer, the second light reflecting layer extending along sidewalls and a bottom of the first opening;
• and
• a second opening in the second light reflecting layer, wherein the second opening exposes a second portion of the top surface of the mesa.

A biological sensing structure comprising:

• at least two recesses in a substrate leaving a mesa therebetween;
• a first light reflecting layer over a top surface and sidewalls of the mesa and over a bottom surface of the at least two recesses;
• a first opening in the first light reflecting layer, the first opening exposing a portion of the top surface of the mesa, and the first opening having a tapered sidewall;
• a filling material over the first light reflecting layer in the at least two recesses;
• a conformal liner layer over the first light reflecting layer in the at least two recesses;
• a sacrificial material over the conformal liner layer in the at least two recesses;
• a second light reflecting layer over the sacrificial material, over the first light reflecting layer, on the tapered sidewall of the first opening, and in the first opening;
• and
• a second opening in the second light reflecting layer, wherein the second opening at least partially exposes the portion of the top surface of the mesa.