US5286344A — Process for selectively etching a layer of silico…

Claim 1

Independent Claim 195 words

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 SiO 2 etch rate, and at a high level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 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 SiO 2 outer layer are perpendicular to the multilayer structure layers.

Claim 2

Dependent Claim 195 words

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 SiO 2 etch rate, and at a high level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 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 SiO 2 outer layer are perpendicular to the multilayer structure layers.

Claim 3

Dependent Claim 15 words

The process of claim 1, wherein said additive material comprises CH 2 F 2 .

Claim 4

Dependent Claim 21 words

The process of claim 1, wherein said etchant material comprises at least one of CHF 3 , CF 4 and Ar.

Claim 5

Dependent Claim 32 words

The process of claim 1, wherein said higher level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate is at least about 10:1.

Claim 6

Dependent Claim 23 words

The process of claim 1, wherein said high SiO 2 etch rate is at least about 2,500 angstroms of SiO 2 per minute.

Claim 7

Dependent Claim 13 words

The process of claim 1, wherein said additive material comprises CH 3 F.

Claim 8

Dependent Claim 35 words

The process of claim 1, wherein said etching of the exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer comprises a dry etching process conducted in a magnetically-enhanced etching chamber.

Claim 9

Dependent Claim 38 words

The process of claim 1, wherein said fluorinated chemical etchant system comprises from about 70-90% of said etchant material, and from about 10-30% of said additive material, based on the total flow of the fluorinated chemical etchant system.

Claim 10

Dependent Claim 103 words

The process of claim 1, wherein the selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate for etching the silicon dioxide outer layer to the silicon nitride stop layer, employing a fluorinated chemical etchant system including an etchant material and an additive material, is at least about 500% higher than the selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate for etching the silicon dioxide outer layer to the silicon nitride stop layer, employing a fluorinated chemical etchant system including said etchant material without said additive material.

Claim 11

Dependent Claim 30 words

The process of claim 1, wherein said multilayer structure includes a silicon wafer, and the temperature of said silicon wafer during said etching step is from about 20-80 degrees C.

Claim 12

Dependent Claim 237 words

A process for using an etchant material for plasma etching a multilayer structure to form a etched pattern therein, comprising: providing a fluorinated chemical etchant system including an etchant material and an additive material, said additive material comprising at least one of CH 2 F 2 or CH 3 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 SiO 2 etch rate, and at a high level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 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 SiO 2 outer layer are perpendicular to the multilayer structure layers.

Claim 13

Dependent Claim 237 words

A process for using an etchant material for plasma etching a multilayer structure to form a etched pattern therein, comprising: providing a fluorinated chemical etchant system including an etchant material and an additive material, said additive material comprising at least one of CH 2 F 2 or CH 3 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 SiO 2 etch rate, and at a high level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 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 SiO 2 outer layer are perpendicular to the multilayer structure layers.

Claim 14

Dependent Claim 21 words

The process of claim 11, wherein said etchant material comprising at least one of CHF 3 , CF 4 and Ar.

Claim 15

Dependent Claim 32 words

The process of claim 11, wherein said high level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate is at least about 10:1.

Claim 16

Dependent Claim 23 words

The process of claim 11, wherein said high SiO 2 etch rate is at least about 2,500 angstroms of SiO 2 per minute.

Claim 17

Dependent Claim 13 words

The process of claim 11, wherein said additive material comprises CH 3 F.

Claim 18

Dependent Claim 35 words

The process of claim 11, wherein said etching of the exposed areas of the silicon dioxide outer layer to the silicon nitride stop layer comprises a dry etching process conducted in a magnetically-enhanced etching chamber.

Claim 19

Dependent Claim 38 words

The process of claim 11, wherein said fluorinated chemical etchant system comprises from bout 70-90% of said etchant material, and from about 10-30% of said additive material, based on the total flow of the fluorinated chemical etchant system.

Claim 20

Dependent Claim 103 words

The process of claim 11, wherein the selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate for etching the silicon dioxide outer layer to the silicon nitride stop layer, employing a fluorinated chemical etchant system including an etchant material and an additive material, is at least about 500% higher than the selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate for etching the silicon dioxide outer layer to the silicon nitride stop layer, employing a fluorinated chemical etchant system including said etchant material without sad additive material.

Claim 21

Dependent Claim 30 words

The process of claim 11, wherein said multilayer structure includes a silicon wafer, and the temperature of said silicon wafer during said etching step is from about 20-80 degrees C.

Claim 22

Dependent Claim 183 words

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 SiO 2 etch rate, and at a high level of selectivity of said SiO 2 etch rate, respect to said Si 3 N 4 etch rate, to form an etched pattern in the silicon dioxide layer in which the contact sidewalls of said SiO 2 outer layer are perpendicular to the multiplayer structure layers.

Claim 23

Dependent Claim 183 words

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 SiO 2 etch rate, and at a high level of selectivity of said SiO 2 etch rate, respect to said Si 3 N 4 etch rate, to form an etched pattern in the silicon dioxide layer in which the contact sidewalls of said SiO 2 outer layer are perpendicular to the multiplayer structure layers.

Claim 24

Dependent Claim 15 words

The system of claim 20, wherein said additive material comprises CH 2 F 2 .

Claim 25

Dependent Claim 21 words

The system of claim 20, wherein said etchant material comprising at least one of CHF 3 , CF 4 and Ar.

Claim 26

Dependent Claim 32 words

The system of claim 20, wherein said high level of selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate is at least about 10:1.

Claim 27

Dependent Claim 23 words

The system of claim 20, wherein said high SiO 2 etch rate is at least about 2,500 angstroms of SiO 2 per minute.

Claim 28

Dependent Claim 38 words

The process of claim 20, wherein said fluorinated chemical etchant system comprises from about 70-90% of said etchant material, and from about 10-30% of said additive material, based on the total flow of the fluorinated chemical etchant system.

Claim 29

Dependent Claim 105 words

The system of claim 20, wherein the selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate for etching the silicon dioxide outer layer to the silicon nitride stop layer, employing a fluorinated chemical etchant system including an etchant material and an additive material, is at least about 500% higher than the selectivity of said SiO 2 etch rate with respect to said Si 3 N 4 etch rate for etching the SiO 2 outer layer to the Si 3 N 4 stop layer, employing a fluorinated chemical etchant system including said etchant material without said additive material.

Claim 30

Dependent Claim 68 words

A dry etching process for a multilayer semiconductor wafer, comprising: 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.

Claim 31

Dependent Claim 68 words

A dry etching process for a multilayer semiconductor wafer, comprising: 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.

Claim 32

Dependent Claim 28 words

An etching process as in claim 22, further comprising: etching with the plasma when the bottom electrode is within a temperature range from 20 to 80 degrees C.

Claim 33

Dependent Claim 21 words

An etching process as in claim 27, wherein the silicon-dioxide layer etch rate is at least about 2,500 angstroms per minute.

Claim 34

Dependent Claim 21 words

An etching process as in claim 27, wherein the plasma etching is dry etching process conducted in a magnetically-enhanced etching chamber.

Claim 35

Dependent Claim 36 words

An etching process as in claim 27, wherein the plasma etching has a selectivity of SiO 2 etch rate with respect to Si 3 N 4 etch rate is at least a 15 to 1 ratio.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1997-02-14	1997-08-16	1998-02-15	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2001-02-14	2001-08-16	2002-02-15	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2005-02-14	2005-08-16	2006-02-15	$7700.00	Window Closed / Lapsed

Process for selectively etching a layer of silicon dioxide on an underlying stop layer of silicon nitride

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