METHODS FOR MANUFACTURING MICROWELL STRUCTURES OF CHEMICALLY-SENSITIVE SENSOR ARRAYS
Methods and apparatus relating to FET arrays for monitoring chemical and/or biological reactions such as nucleic acid sequencing-by-synthesis reactions. Some methods provided herein relate to improving signal (and also signal to noise ratio) from released hydrogen ions during nucleic acid sequencing reactions.
1 . A method for manufacturing a sensor, 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;
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 cavities exposing the sensing surfaces of the floating gate structures; and
depositing a layer of sensing material within the cavities and lining sidewalls of the cavities to define microwells having sensing layers contacting the sensing surfaces of the floating gate structures.
2 . The method of claim 1 , wherein the dielectric layer comprises at least one of silicon oxide, silicon nitride and silicon oynitride.
3 . The method of claim 1 , wherein the sensing material comprises tantalum oxide.
4 . The method of claim 1 , wherein the sensing material is a metal oxide or metal nitride selected from one or more of the group of Al 2 O 3 , Ta 2 O 5 , HfO 3 , WO 3 or mixtures thereof.
5 . The method of claim 1 , wherein the sensing material includes Al 2 O 3 , and Ta 2 O 5 over the Al 2 O 3 .
6 . The method of claim 1 , wherein the chemFETs in the array provide signals indicating an ion-concentration in an analyte solution coupled to the floating gate via the microwells.
7 . The method of claim 1 , wherein the microwells have non-circular cross-sections.
8 . A method of manufacturing a sequencing device, comprising:
forming an array of chemically-sensitive field effect transistors (chemFETs), each chemFET in the array having a floating gate structure;
depositing a dielectric layer over the floating gate structures of the chemFETs in the array;
etching the dielectric layer to define cavities to expose upper surfaces of the floating gate structures;
depositing a layer of sensing material within the cavities, thereby forming microwells having sensing layers contacting the upper surfaces of the floating gate structures; and
forming a microfluidic structure in fluid flow communication with the array of microwells, and arranged to deliver analytes for sequencing.
9 . The method of claim 8 , wherein the dielectric layer comprises at least one of silicon oxide, silicon nitride and silicon oxynitride.
10 . The method of claim 8 , wherein the sensing material comprises tantalum oxide.
11 . The method of claim 8 , wherein the sensing material is a metal oxide or metal nitride selected from one or more of the group of Al 2 O 3 , Ta 2 O 5 , HfO 3 , WO 3 , or mixtures thereof.
12 . The method of claim 8 , wherein the sensing material includes Al 2 O 3 , and Ta 2 O 5 over the Al 2 O 3 .
13 . The method of claim 8 , wherein the microwells have non-circular cross-sections.