Process for selectively etching a layer of silicon dioxide on an underlying stop layer of silicon nitride
DC CAFCFirst Claim
1. A process for plasma etching a multilayer structure to form a predetermined etched pattern therein, comprising:
- providing a multilayer structure, the outer layers of the multilayer structure comprising a silicon dioxide outer layer on an underlying silicon nitride stop layer;
forming on the top surface of the multilayer structure a chemical etchant resistant layer having a pattern of openings in therein and thereby exposing areas of the silicon dioxide outer layer corresponding to the pattern of openings; and
etching the exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer, at a high SiO2 etch rate, and at a high level of selectivity of said SiO2 etch rate with respect to said Si3 N4 etch rate, with a fluorinated chemical etchant system including an etchant material ad an additive material, said additive material comprising a fluorocarbon material in which the number of hydrogen atoms is equal to or grater than the number of fluorine atoms, and sad etching step forming an etch pattern in the silicon dioxide outer layer in which the contact sidewalls of said SiO2 outer layer are perpendicular to the multilayer structure layers.
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Abstract
More specifically, a process is provided for etching a multilayer structure to form a predetermined etched pattern therein. The subject process comprises providing the multilayer structure having a plurality of structural layers. The structural layers of the multilayer structure comprise a silicon dioxide outer layer on an underlying silicon nitride stop layer. Then, a chemical etchant protective layer is formed on a major surface of the multilayer structure having a predetermined pattern of openings, thereby exposing areas of the silicon dioxide outer layer corresponding to the predetermined pattern of openings. The exposed areas of the silicon dioxide outer layer are then etched down to the silicon nitride stop layer, at a high SiO2 etch rate and at a high level of selectivity of the SiO2 etch rate with respect to the Si3 N4 etch rate, with a fluorinated chemical etchant system. The fluorinated chemical etchant system includes an etchant material and an additive material. The additive material comprises a fluorocarbon material in which the number of hydrogen atoms is equal to or greater than the number of fluorine atoms. The etching step forms a substantially predetermined etch pattern in the silicon dioxide outer layer in which the contact sidewalls of said SiO2 outer layer are substantially upright.
185 Citations
31 Claims
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1. A process for plasma etching a multilayer structure to form a predetermined etched pattern therein, comprising:
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providing a multilayer structure, the outer layers of the multilayer structure comprising a silicon dioxide outer layer on an underlying silicon nitride stop layer; forming on the top surface of the multilayer structure a chemical etchant resistant layer having a pattern of openings in therein and thereby exposing areas of the silicon dioxide outer layer corresponding to the pattern of openings; and etching the exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer, at a high SiO2 etch rate, and at a high level of selectivity of said SiO2 etch rate with respect to said Si3 N4 etch rate, with a fluorinated chemical etchant system including an etchant material ad an additive material, said additive material comprising a fluorocarbon material in which the number of hydrogen atoms is equal to or grater than the number of fluorine atoms, and sad etching step forming an etch pattern in the silicon dioxide outer layer in which the contact sidewalls of said SiO2 outer layer are perpendicular to the multilayer structure layers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A process for using an etchant material for plasma etching a multilayer structure to form a etched pattern therein, comprising:
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providing a fluorinated chemical etchant system including an etchant material and an additive material, said additive material comprising at least one of CH2 F2 or CH3 F; providing a multilayer structure having a plurality of structural layers, one of the outer structural layers of the multilayer structure comprising a silicon dioxide outer layer on an underlying silicon nitride stop layer; forming on the top surface of the multilayer structure a chemical etchant resistant layer having a pattern of openings therein and thereby exposing areas of the silicon dioxide outer layer corresponding to the pattern of openings; and etching the exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer, at a high SiO2 etch rate, and at a high level of selectivity of said SiO2 etch rate with respect to said Si3 N4 etch rate, with a fluorinated chemical etchant system including an etchant material and an additive material, said additive material comprising a fluorocarbon material in which the number of hydrogen atoms is equal to or greater than the number of fluorine atoms, ad said etching step forming an etch pattern in the silicon dioxide outer layer in which the contact sidewalls of sad SiO2 outer layer are perpendicular to the multilayer structure layers. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. A fluorinated chemical etchant system for plasma etching a multilayer structure having a plurality of structural layers comprising a silicon dioxide outer layer on an underlaying silicon nitride layer, the multilayer structure having a chemical etchant resistant patterned layer including a pattern of openings therein, thereby exposing a plurality of areas of the top surface of the multilayer structure corresponding to the pattern of openings during etching, which comprises:
a fluorinated chemical etchant system including an etchant material and an additive material, said additive material comprising a fluorocarbon material in which the number of hydrogen atoms is equal to or greater than the number of fluorine atoms, for etching the plurality of exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer, at a high SiO2 etch rate, and at a high level of selectivity of said SiO2 etch rate, respect to said Si3 N4 etch rate, to form an etched pattern in the silicon dioxide layer in which the contact sidewalls of said SiO2 outer layer are perpendicular to the multiplayer structure layers. - View Dependent Claims (21, 22, 23, 24, 25, 26, 28)
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27. A dry etching process for a multilayer semiconductor wafer, comprising:
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a) providing a silicon-dioxide layer; b) providing a silicon-nitride layer, located under the silicon-dioxide layer; and c) using a plasma, having an etchant, and a fluorocarbon additive gas in which the number of hydrogen atoms are greater than the number of fluorine atoms, to etch through the silicon-dioxide layer down to the top surface of the silicon-nitride layer. - View Dependent Claims (29, 30, 31)
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Specification