# US 7,745,902 B1 · System and method for providing improved trench isolation of semiconductor devices > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,745,902 B1 - Document ID: US7745902B1 - Status: Granted - Kind: B1 - Application number: 11/903,349 - Filed: 2007-09-21 - Granted: 2010-06-29 - Earliest claimed: 2004-03-18 - Assignees: National Semiconductor Corporation - Inventors: Richard W. Foote - Web page: https://patentgrep.com/patent/US7745902B1 ## CPC - H10W 10/40: Isolation regions comprising polycrystalline semiconductor materials - H10W 10/041: {of isolation regions comprising polycrystalline semiconductor materials} - H10W: GENERIC PACKAGES, INTERCONNECTIONS, CONNECTORS OR OTHER CONSTRUCTIONAL DETAILS OF DEVICES COVERED BY CLASS H10 ## Abstract A system and method is disclosed for providing improved trench isolation of semiconductor devices. An isolation trench of the present invention is manufactured as follows. A substrate of a semiconductor device is provided and a trench is etched in the substrate. Then a silicon liner is grown in the trench. The trench is then filled with polysilicon material. Polysilicon material is also deposited on top of the filled trench to protect the silicon dioxide liner from the effects of subsequent etch procedures and oxidation procedures. The initial height of the polysilicon material is selected to be large enough to allow the polysilicon material to survive the subsequent etch procedures and oxidation procedures. ## Claims ### Claim 1 An isolation trench for use in a semiconductor device comprising: a substrate of said semiconductor device; a trench etched in said substrate; a silicon dioxide liner comprising a first portion in said trench and a second portion over horizontal portions of the substrate that are adjacent to the trench, wherein the second portion of the silicon dioxide liner comprises a first top and a first side, the first side extending from the first top to the substrate; polysilicon material comprising a first portion filling said trench and a second portion over said filled trench and extending laterally over at least one edge of the trench to protect said silicon dioxide liner, wherein the second portion of the polysilicon material comprises a second top and a second side, the second top comprising a notch, the second side extending from the second top to one of: the silicon dioxide liner and the substrate, wherein the second portion of the polysilicon material completely covers the first top of the second portion of the silicon dioxide layer; and a layer of oxidation material formed over the second portion of the polysilicon material, wherein the layer of oxidation material contacts the second top and the second side of the second portion of the polysilicon material and fills the notch in the second top of the second portion of the polysilicon material. ### Claim 2 (depends on 1) The isolation trench as set forth in claim 1, wherein said second portion of the polysilicon material has an initial height that is sufficient for said second portion of the polysilicon material to survive one of: at least one subsequent etch procedure and at least one subsequent oxidation procedure. ### Claim 3 (depends on 1) The isolation trench as set forth in claim 1, wherein said second portion of the polysilicon material is capable of expanding vertically and laterally. ### Claim 4 (depends on 1) The isolation trench as set forth in claim 1, wherein said second portion of the polysilicon material does not create stress in said substrate. ### Claim 5 A semiconductor structure, comprising: a silicon dioxide liner comprising a first portion in a trench of a substrate and a second portion over one or more horizontal portions of the substrate that are adjacent to the trench, wherein the second portion of the silicon dioxide liner comprises a first top and a first side, the first side extending from the first top to the substrate; polysilicon material deposited in the trench and over the trench, wherein at least one portion of the deposited polysilicon material extends laterally over at least one edge of the trench, wherein the at least one portion of the deposited polysilicon material comprises a second top and a second side, the second top comprising a notch, the second side extending from the second top to one of: the silicon dioxide liner and the substrate, wherein the at least one portion of the polysilicon material completely covers the first top of the second portion of the silicon dioxide layer; and a layer of oxidation material over the at least one portion of the deposited polysilicon material, wherein the layer of oxidation material contacts the second top and the second side of the at least one portion of the deposited polysilicon material and fills the notch in the second top of the at least one portion of the deposited polysilicon material. ### Claim 6 (depends on 5) The semiconductor structure of claim 5, wherein the polysilicon material comprises portions that extend laterally over all edges of the trench. ### Claim 7 (depends on 5) The semiconductor structure of claim 5, wherein an initial height of the at least one portion of the deposited polysilicon material is sufficient for the at least one portion of the deposited polysilicon material to survive at least one of: an etch procedure and an oxidation procedure. ### Claim 8 (depends on 5) The semiconductor structure of claim 5, wherein the silicon dioxide liner does not include any exposed portions. ### Claim 9 (depends on 5) The semiconductor structure of claim 5, further comprising a silicon dioxide layer over the at least one portion of the deposited polysilicon material. ### Claim 10 A semiconductor device, comprising: a substrate; a trench in said substrate; a silicon dioxide liner, comprising a first portion in said trench and a second portion over one or more horizontal portions of said substrate that are adjacent to said trench, wherein the second portion of the silicon dioxide liner comprises a first top and a first side, the first side extending from the first top to the substrate; polysilicon material comprising a first portion filling the trench and a second portion over said filled trench to protect said silicon dioxide liner, the second portion of the polysilicon material extending laterally over at least one edge of the trench, wherein the second portion of the polysilicon material comprises a second top and a second side, the second top comprising a notch, the second side extending from the second top of the second portion of the polysilicon material to one of: the silicon dioxide liner and the substrate, where the second portion of the polysilicon material completely covers the first top of the second portion of the silicon dioxide layer; and a layer of oxidation material over the second polysilicon material, the layer of oxidation material contacting the second top and the second side of the second portion of the polysilicon material and filling the notch in the second top of the second polysilicon material. ### Claim 11 (depends on 10) The semiconductor device of claim 10, wherein said second portion of the polysilicon material extends laterally over all edges of said trench. ### Claim 12 (depends on 10) The semiconductor device of claim 10, wherein an initial height of said second portion of the polysilicon material is sufficient for said second portion of the polysilicon material to survive one of: at least one subsequent etch procedure and at least one subsequent oxidation procedure. ### Claim 13 (depends on 5) The semiconductor structure of claim 5, wherein the polysilicon material that is deposited on top of the trench is capable of expanding vertically and laterally. ### Claim 14 (depends on 10) The semiconductor device of claim 10, wherein the second polysilicon material is capable of expanding vertically and laterally. ### Claim 15 (depends on 1) The isolation trench as set forth in claim 1, wherein the layer of oxidation material contacts the first side of the second portion of the silicon dioxide liner. ### Claim 16 (depends on 1) The isolation trench as set forth in claim 1, wherein the substrate comprises monocrystalline silicon. ### Claim 17 (depends on 5) The semiconductor structure of claim 5, wherein the second portion of the polysilicon material does not create stress in the substrate. ### Claim 18 (depends on 5) The semiconductor structure of claim 5, wherein the layer of oxidation material contacts the side of the second portion of the silicon dioxide liner. ### Claim 19 (depends on 10) The semiconductor structure of claim 10, wherein the second portion of the polysilicon material does not create stress in the substrate. ### Claim 20 (depends on 10) The semiconductor structure of claim 10, wherein the layer of oxidation material contacts the first side of the second portion of the silicon dioxide liner.