Methods and apparatus for measuring analytes

A method for manufacturing a semiconductor device, comprising:

• forming an array of chemically-sensitive field effect transistors (chemFETs), each chemFET in the array having a floating gate structure including a sensing surface formed on a top metal layer of the floating gate structure;
• depositing a dielectric layer over the sensing surfaces of the floating gate structures of the chemFETs in the array;
• etching the dielectric layer to define an array of reaction chambers;
• each reaction chamber exposing a corresponding sensing surface of a floating gate structure;
• and
• depositing a layer of sensing material within the array of reaction chambers and at least partially on each reaction chamber sidewall to define an array of reaction chambers where each reaction chamber includes a sensing layer in contact with a sensing surface of a floating gate structure.