# US 2014/0191293 A1 · Methods for manufacturing well structures for low-noise chemical sensors > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0191293 A1 - Document ID: US20140191293A1 - Status: Published application - Kind: A1 - Application number: 13/736,566 - Filed: 2013-01-08 - Published: 2014-07-10 - Earliest claimed: 2013-01-08 - Assignees: Life Technologies Corporation - Applicants: Life Technologies Corporation - Inventors: James BUSTILLO; Shifeng LI - Web page: https://patentgrep.com/patent/US20140191293A1 ## CPC - G01N 27/414: Ion-sensitive or chemical field-effect transistors, i.e. ISFETS or CHEMFETS - G01N 27/4148: {Integrated circuits therefor, e.g. fabricated by CMOS processing} - G01N 27/4145: {specially adapted for biomolecules, e.g. gate electrode with immobilised receptors} - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract In one implementation, a method for manufacturing a chemical detection device is described. The method includes forming a chemical sensor having a sensing surface. A dielectric material is deposited on the sensing surface. A first etch process is performed to partially etch the dielectric material to define an opening over the sensing surface and leave remaining dielectric material on the sensing surface. An etch protect material is formed on a sidewall of the opening. A second etch process is then performed to selectively etch the remaining dielectric material using the etch protect material as an etch mask, thereby exposing the sensing surface. ## Claims ### Claim 1 A method for manufacturing a chemical detection device, the method comprising: forming a chemical sensor having a sensing surface; depositing a dielectric material on the sensing surface; performing a first etch process to partially etch the dielectric material to define an opening over the sensing surface and leave remaining dielectric material on the sensing surface; forming an etch protect material on a sidewall of the opening; and performing a second etch process to selective etching the remaining dielectric material using the etch protect material as an etch mask, thereby exposing the sensing surface. ### Claim 2 (depends on 1) The method of claim 1, wherein the chemical sensor is a chemically-sensitive field effect transistor, and the sensing surface is coupled to a channel of the chemically-sensitive field effect transistor. ### Claim 3 (depends on 2) The method of claim 2, wherein the sensing surface is on an upper surface of a floating gate of the field effect transistor. ### Claim 4 (depends on 1) The method of claim 1, wherein the first etch process is an anisotropic etch process, and the second etch process is an isotropic etch process. ### Claim 5 (depends on 4) The method of claim 4, wherein the first etch process is a dry etch process, and the second etch process is a wet etch process. ### Claim 6 (depends on 1) The method of claim 1, wherein the second etch process does not accumulate charge on the sensing surface. ### Claim 7 (depends on 1) The method of claim 1, wherein depositing the dielectric material comprises depositing a first dielectric material on the sensing surface, and depositing a second dielectric material on the first dielectric material. ### Claim 8 (depends on 1) The method of claim 1, wherein forming the etch protect material comprises: depositing the etch protect material on the remaining dielectric material and the sidewall of the opening; and etching the etch protect material to expose the remaining dielectric material, thereby forming a sidewall spacer of remaining etch protect material on the sidewall of the opening. ### Claim 9 (depends on 8) The method of claim 8, wherein the sidewall spacer includes a bottom surface spaced away from the sensing surface. ### Claim 10 (depends on 1) The method of claim 1, wherein the chemical sensor generates a sensor signal in response to a chemical reaction occurring within the reaction region. ### Claim 11 (depends on 9) The method of claim 9, wherein the chemical reaction is a sequencing reaction. ### Claim 12 A chemical detection device, comprising: a chemical sensor having a sensing surface; a dielectric material having an opening extending to the sensing surface; and a sidewall spacer on a sidewall of the opening, the sidewall spacer having a bottom surface spaced away from the sensing surface and having an inside surface defining a reaction region for receiving at least one reactant. ### Claim 13 (depends on 12) The chemical detection device of claim 12, wherein the dielectric material within a lower portion of the opening comprises material different than that of the sidewall spacer. ### Claim 14 (depends on 12) The chemical detection device of claim 12, wherein the chemical sensor is a chemically-sensitive field effect transistor, and the sensing surface is coupled to a channel of the chemically-sensitive field effect transistor. ### Claim 15 (depends on 14) The chemical detection device of claim 14, wherein the sensing surface is on an upper surface of a floating gate of the field effect transistor. ### Claim 16 (depends on 12) The chemical detection device of claim 12, wherein the chemical sensor generates a sensor signal in response to a chemical reaction occurring within the reaction region. ### Claim 17 (depends on 16) The chemical detection device of claim 16, wherein the chemical reaction is a sequencing reaction.