US6602434B1 — Process for etching oxide using hexafluorobutadie…

Claim 1

Independent Claim 111 words

An oxide etch process for etching an oxide layer over a non-oxide layer, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising a first amount of a heavy fluorocarbon selected from the group consisting of hexafluorobutadiene, hexafluorocyclobutene, and hexafluorobenzene, a second amount of a chemically inactive gas being at least equal to said first amount, and a third amount of a hydrofluoromethane having no more than two hydrogen atoms; RF biasing a pedestal electrode supporting a substrate having an oxide layer overlying a non-oxide layer; and exciting said etching gas mixture into a plasma to thereby etch said oxide layer selectively to said non-oxide layer.

Claim 2

Dependent Claim 111 words

An oxide etch process for etching an oxide layer over a non-oxide layer, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising a first amount of a heavy fluorocarbon selected from the group consisting of hexafluorobutadiene, hexafluorocyclobutene, and hexafluorobenzene, a second amount of a chemically inactive gas being at least equal to said first amount, and a third amount of a hydrofluoromethane having no more than two hydrogen atoms; RF biasing a pedestal electrode supporting a substrate having an oxide layer overlying a non-oxide layer; and exciting said etching gas mixture into a plasma to thereby etch said oxide layer selectively to said non-oxide layer.

Claim 3

Dependent Claim 20 words

The oxide etch process of claim 1 , wherein said non-oxide layer is a nitride layer having a nitride corner.

Claim 4

Dependent Claim 14 words

The oxide etch process of claim 1 , wherein said heavy fluorocarbon is hexafluorobutadiene.

Claim 5

Dependent Claim 26 words

The oxide etch process of claim 1 , wherein said heavy fluorocarbon comprises hexafluorobutadiene and said second amount is at least four time said first amount.

Claim 6

Dependent Claim 20 words

The oxide etch process of claim 4 , wherein said second amount is greater than fifteen times said first amount.

Claim 7

Dependent Claim 13 words

The oxide etch process of claim 1 , wherein said hydrofluoromethane comprises difluoromethane.

Claim 8

Dependent Claim 14 words

The oxide etch process of claim 6 , wherein said heavy fluorocarbon comprises hexafluorobutadiene.

Claim 9

Dependent Claim 47 words

The oxide etch process of claim 7 , wherein said first amount of said hexafluorobutadiene and said third amount of said difluoromethane are within respective ranges of 10 to 25 sccm and 5 to 20 sccm as normalized for a volume of said chamber being 23 liters.

Claim 10

Independent Claim 233 words

A method of etching a hole in an oxide layer overlying a nitride layer having a nitride corner, a minimum width of said hole being no more than 0.4 μm and a depth of said hole being at least 0.7 μm, comprising the steps of: flowing into a plasma reactor a first gas mixture comprising a first amount of a first fluorocarbon selected from members of the group consisting of hexafluorobutadiene, hexafluorocyclobutene, and hexafluorobenzene, a second amount of a chemically inactive diluent gas, and a third amount of a second fluorocarbon other than said members of said group and which is more polymerizing than said first fluorocarbon or a hydrofluorocarbon which is more polymerizing than said first fluorocarbon; from a first oscillatory power supply biasing a pedestal electrode supporting a substrate including an oxide layer overlying a nitride layer and a mask layer overlying said oxide layer to define a hole to be etched in said oxide layer; and from a second oscillatory power supply exciting said first gas mixture into a plasma to thereby etch said oxide layer selectively to said nitride layer; wherein said first and second amounts and power levels of said first and second power supplies are chosen to provide a process window in said first amount of ±20% in which selectivity of etching oxide to nitride is at least 10 and no etch stop occurs in said hole.

Claim 11

Independent Claim 233 words

A method of etching a hole in an oxide layer overlying a nitride layer having a nitride corner, a minimum width of said hole being no more than 0.4 μm and a depth of said hole being at least 0.7 μm, comprising the steps of: flowing into a plasma reactor a first gas mixture comprising a first amount of a first fluorocarbon selected from members of the group consisting of hexafluorobutadiene, hexafluorocyclobutene, and hexafluorobenzene, a second amount of a chemically inactive diluent gas, and a third amount of a second fluorocarbon other than said members of said group and which is more polymerizing than said first fluorocarbon or a hydrofluorocarbon which is more polymerizing than said first fluorocarbon; from a first oscillatory power supply biasing a pedestal electrode supporting a substrate including an oxide layer overlying a nitride layer and a mask layer overlying said oxide layer to define a hole to be etched in said oxide layer; and from a second oscillatory power supply exciting said first gas mixture into a plasma to thereby etch said oxide layer selectively to said nitride layer; wherein said first and second amounts and power levels of said first and second power supplies are chosen to provide a process window in said first amount of ±20% in which selectivity of etching oxide to nitride is at least 10 and no etch stop occurs in said hole.

Claim 12

Dependent Claim 12 words

The method of claim 9 , wherein said first fluorocarbon comprises hexafluorobutadiene.

Claim 13

Dependent Claim 15 words

The method of claim 10 , wherein said second fluorocarbon or hydrofluorocarbon comprises a hydrofluorocarbon.

Claim 14

Dependent Claim 15 words

The method of claim 9 , wherein said second fluorocarbon or hydrofluorocarbon comprises a hydrofluorocarbon.

Claim 15

Dependent Claim 88 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, pentafluoropropylene, and trifluoropropyne, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said non-oxide corner.

Claim 16

Dependent Claim 88 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, pentafluoropropylene, and trifluoropropyne, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said non-oxide corner.

Claim 17

Dependent Claim 13 words

The process of claim 13 , wherein said inactive carrier gas comprises argon.

Claim 18

Dependent Claim 79 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon comprising hexafluorobutadiene, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said corner.

Claim 19

Dependent Claim 79 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon comprising hexafluorobutadiene, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said corner.

Claim 20

Dependent Claim 170 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: a first step of flowing into a plasma reaction chamber a first gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne, (b) a chemically inactive carrier gas, and (c) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane; and a first step of said exciting said first gas mixture into a first plasma to etch said oxide layer; a second step performed subsequently to said first flowing step of flowing into said plasma reaction chamber a second etching gas mixture comprising (d) said unsaturated fluorocarbon, (e) said hydrofluoromethane in an amount substantially more than in said first flowing step, and (f) said chemically inactive carrier gas; and a second step of exciting said second etching gas mixture into a plasma to etch said oxide layer selectively to said non-oxide corner.

Claim 21

Dependent Claim 170 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: a first step of flowing into a plasma reaction chamber a first gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne, (b) a chemically inactive carrier gas, and (c) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane; and a first step of said exciting said first gas mixture into a first plasma to etch said oxide layer; a second step performed subsequently to said first flowing step of flowing into said plasma reaction chamber a second etching gas mixture comprising (d) said unsaturated fluorocarbon, (e) said hydrofluoromethane in an amount substantially more than in said first flowing step, and (f) said chemically inactive carrier gas; and a second step of exciting said second etching gas mixture into a plasma to etch said oxide layer selectively to said non-oxide corner.

Claim 22

Dependent Claim 39 words

The process of claim 16 , wherein said first plasma produces a more vertical profile in said oxide layer than said second plasma and wherein said second plasma is more selective to said non-oxide corner than said first plasma.

Claim 23

Dependent Claim 12 words

The method of claim 16 , wherein said unsaturated fluorocarbon comprises hexafluorobutadiene.

Claim 24

Dependent Claim 115 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas, wherein said flowing step flows less of said fluoromethane and more of said chemically inactive carrier gas than of said unsaturated fluorocarbon; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said non-oxide corner.

Claim 25

Dependent Claim 115 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas, wherein said flowing step flows less of said fluoromethane and more of said chemically inactive carrier gas than of said unsaturated fluorocarbon; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said non-oxide corner.

Claim 26

Dependent Claim 12 words

The method of claim 19 , wherein said unsaturated fluorocarbon, comprises hexafluorobutadiene.

Claim 27

Dependent Claim 107 words

An oxide etching process for etching an oxide layer over an underlying non-oxide layer formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas; RF biasing a pedestal electrode; and exciting said etching gas mixture into a plasma in a plasma source region remote from said pedestal electrode to etch said oxide layer with high selectivity to said non-oxide layer.

Claim 28

Dependent Claim 107 words

An oxide etching process for etching an oxide layer over an underlying non-oxide layer formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane and difluoromethane, and (c) a chemically inactive carrier gas; RF biasing a pedestal electrode; and exciting said etching gas mixture into a plasma in a plasma source region remote from said pedestal electrode to etch said oxide layer with high selectivity to said non-oxide layer.

Claim 29

Dependent Claim 14 words

The etching process of claim 21 , wherein said plasma is a high-density plasma.

Claim 30

Dependent Claim 20 words

The etching process of claim 21 , wherein said exciting step inductively couples RF energy into said plasma source region.

Claim 31

Dependent Claim 14 words

The etching process of claim 21 , wherein said non-oxide layer comprises silicon nitride.

Claim 32

Dependent Claim 13 words

The etching process of claim 21 , wherein said unsaturated fluorocarbon comprises hexafluorobutadiene.

Claim 33

Dependent Claim 17 words

The etching process of claim 21 , wherein said unsaturated fluorocarbon comprises C 5 F 8 .

Claim 34

Dependent Claim 13 words

The etching process of claim 21 , wherein said unsaturated fluorocarbon comprises trifluoropropyne.

Claim 35

Dependent Claim 141 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: a first step of flowing into a plasma chamber a first etching gas mixture comprising an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne and a chemically inactive gas; a first step of exciting said first etching gas mixture into a first plasma etching said oxide layer with a substantially vertical profile; a second step, performed subsequently to said first flowing step, of flowing into said plasma chamber a second etching gas mixture comprising a hydrofluoromethane and a chemically inactive gas; and a second step of exciting said second etching gas mixture into a second plasma etching said oxide layer with enhanced selectivity to said non-oxide corner.

Claim 36

Dependent Claim 141 words

An oxide etching process for etching an oxide layer over an underlying feature having a non-oxide corner formed in a substrate, comprising the steps of: a first step of flowing into a plasma chamber a first etching gas mixture comprising an unsaturated fluorocarbon selected from the group consisting of hexafluorobutadiene, C 5 F 8 , pentafluoropropylene, and trifluoropropyne and a chemically inactive gas; a first step of exciting said first etching gas mixture into a first plasma etching said oxide layer with a substantially vertical profile; a second step, performed subsequently to said first flowing step, of flowing into said plasma chamber a second etching gas mixture comprising a hydrofluoromethane and a chemically inactive gas; and a second step of exciting said second etching gas mixture into a second plasma etching said oxide layer with enhanced selectivity to said non-oxide corner.

Claim 37

Dependent Claim 19 words

The oxide etching process of claim 28 , wherein said second etching gas mixture additionally comprises said unsaturated fluorocarbon.

Claim 38

Dependent Claim 27 words

The oxide etching process of claim 28 , wherein in said second flowing step a flow of unsaturated fluorocarbon is greater than a flow of said hydrofluoromethane.

Claim 39

Dependent Claim 37 words

The oxide etching process of claim 30 , wherein in said second flowing step a flow of said chemically inactive gas is greater than a sum of said flows of said unsaturated fluorocarbon and of said hydrofluoromethane.

Claim 40

Dependent Claim 30 words

The oxide etching process of claim 31 , wherein in said first flowing step a flow of said chemically inactive gas is greater than a flow of said unsaturated fluorocarbon.

Claim 41

Dependent Claim 14 words

The oxide etching process of claim 28 , wherein said unsaturated hydrofluorocarbon comprises hexafluorobutadiene.

Claim 42

Dependent Claim 13 words

The oxide etching process of claim 28 , wherein said hydrofluoromethane comprises difluoromethane.

Claim 43

Dependent Claim 85 words

An oxide etching process for etching an oxide layer over an underlying nitride layer formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) hexafluorobutadiene, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane, difluoromethane, and trifluoromethane, (c) an anti-polymerizing gas selected from the group consisting of oxygen gas and nitrogen gas, and (d) argon; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said nitride layer.

Claim 44

Dependent Claim 85 words

An oxide etching process for etching an oxide layer over an underlying nitride layer formed in a substrate, comprising the steps of: flowing into a plasma reaction chamber an etching gas mixture comprising (a) hexafluorobutadiene, (b) a hydrofluoromethane selected from the group consisting of monofluoromethane, difluoromethane, and trifluoromethane, (c) an anti-polymerizing gas selected from the group consisting of oxygen gas and nitrogen gas, and (d) argon; and exciting said etching gas mixture into a plasma to etch said oxide layer selectively to said nitride layer.

Claim 45

Dependent Claim 28 words

The process of claim 35 , wherein said nitride layer is formed into a nitride corner and said plasma etching said oxide layer selectively to said nitride corner.

Claim 46

Dependent Claim 13 words

The process of claim 35 , wherein said anti-polymerizing gas comprises oxygen gas.

Claim 47

Dependent Claim 11 words

The process of claim 37 , wherein said hydrofluoromethane comprises monofluoromethane.

Claim 48

Dependent Claim 38 words

The process of claim 38 , wherein said plasma reaction chamber is a capacitively coupled plasma reaction chamber including a pedestal electrode supporting said substrate and wherein said exciting step includes applying RF power to said pedestal electrode.

Claim 49

Dependent Claim 11 words

The process of claim 37 , wherein said hydrofluoromethane comprises difluoromethane.

Claim 50

Dependent Claim 11 words

The process of claim 37 , wherein said hydrofluoromethane comprises trifluoromethane.

Claim 51

Dependent Claim 16 words

The process of claim 35 , wherein said etching gas mixture contains essentially no carbon monoxide.

Claim 52

Dependent Claim 13 words

The method of claim 35 , wherein said anti-polymerizing gas comprises nitrogen gas.

Claim 53

Dependent Claim 16 words

The method of claim 35 , wherein said etching gas mixtures includes effectively no carbon monoxide.

Claim 54

Dependent Claim 84 words

A process of etching an oxide layer over an underlying nitride layer including a nitride corner formed in a substrate supported on a substrate electrode in a capacitively coupled plasma reactor, comprising the steps of: flowing into said plasma reaction chamber an etching gas mixture comprising (a) hexafluorobutadiene, (b) a hydrofluoromethane, (c) oxygen gas, and (d) argon; and applying RF power to said pedestal electrode to excite said etching gas mixture into a plasma to etch said oxide layer selectively to said nitride corner.

Claim 55

Dependent Claim 84 words

A process of etching an oxide layer over an underlying nitride layer including a nitride corner formed in a substrate supported on a substrate electrode in a capacitively coupled plasma reactor, comprising the steps of: flowing into said plasma reaction chamber an etching gas mixture comprising (a) hexafluorobutadiene, (b) a hydrofluoromethane, (c) oxygen gas, and (d) argon; and applying RF power to said pedestal electrode to excite said etching gas mixture into a plasma to etch said oxide layer selectively to said nitride corner.

Claim 56

Dependent Claim 11 words

The process of claim 45 , wherein said hydrofluoromethane comprises monofluoromethane.

Claim 57

Dependent Claim 11 words

The process of claim 45 , wherein said hydrofluoromethane comprises difluoromethane.

Claim 58

Dependent Claim 25 words

The process of claim 45 , wherein a ratio of a flow of said argon to a flow of said hydrofluoromethane is at least 15.

Claim 59

Dependent Claim 11 words

The process of claim 45 , wherein said hydrofluoromethane comprises trifluoromethane.

Claim 60

Independent Claim 205 words

A method of etching a hole in an oxide layer overlying a nitride layer having a nitride corner, a minimum width of said hole being no more than 0.4 μm and a depth of said hole being at least 0.7 μm, comprising the steps of: flowing into a plasma reactor a first gas mixture comprising a first amount of a first fluorocarbon selected from members of the group consisting of hexafluorobutadiene, hexafluorocyclobutene, and hexafluorobenzene, a second amount of a chemically inactive diluent gas, and a third amount of a hydrofluoromethane; from a first oscillatory power supply biasing a pedestal electrode supporting a substrate including an oxide layer overlying a nitride layer and a mask layer overlying said oxide layer to define a hole to be etched in said oxide layer; and from a second oscillatory power supply exciting said first gas mixture into a plasma to thereby etch said oxide layer selectively to said nitride layer; wherein said first and second amounts and power levels of said first and second power supplies are chosen to provide a process window in said first amount of ±20% in which selectivity of etching oxide to nitride is at least 10 and no etch stop occurs in said hole.

Claim 61

Independent Claim 205 words

A method of etching a hole in an oxide layer overlying a nitride layer having a nitride corner, a minimum width of said hole being no more than 0.4 μm and a depth of said hole being at least 0.7 μm, comprising the steps of: flowing into a plasma reactor a first gas mixture comprising a first amount of a first fluorocarbon selected from members of the group consisting of hexafluorobutadiene, hexafluorocyclobutene, and hexafluorobenzene, a second amount of a chemically inactive diluent gas, and a third amount of a hydrofluoromethane; from a first oscillatory power supply biasing a pedestal electrode supporting a substrate including an oxide layer overlying a nitride layer and a mask layer overlying said oxide layer to define a hole to be etched in said oxide layer; and from a second oscillatory power supply exciting said first gas mixture into a plasma to thereby etch said oxide layer selectively to said nitride layer; wherein said first and second amounts and power levels of said first and second power supplies are chosen to provide a process window in said first amount of ±20% in which selectivity of etching oxide to nitride is at least 10 and no etch stop occurs in said hole.

Claim 62

Dependent Claim 12 words

The method of claim 50 , wherein said first fluorocarbon comprises hexafluorobutadiene.

Claim 63

Independent Claim 200 words

A method of etching a hole in an oxide layer overlying a non-oxide layer formed in a substrate and having a mask layer overlying said oxide layer to define said hole to be defined in said oxide layer, a minimum width of said hole being no more than 0.4 μm and a depth of said hole being at least 0.7 μm, comprising the steps of: flowing into a plasma reactor a first gas mixture comprising a first amount of a fluorocarbon selected from the group consisting of hexafluorobutadiene, hexafluorocyclobutene, C 5 F 8 , and hexafluorobenzene, a second amount of a chemically inactive diluent gas, and a third amount of a hydrofluorocarbon; from a first oscillatory power supply biasing a pedestal electrode supporting said substrate; and from a second oscillatory power supply exciting said first gas mixture into a plasma to thereby etch said oxide layer selectively to said non-oxide layer; wherein said first and second amounts and power levels of said first and second power supplies are chosen to provide a process window in said first amount of ±20% in which selectivity of etching oxide to non-oxide is at least 10 and no etch stop occurs in said hole.

Claim 64

Independent Claim 200 words

A method of etching a hole in an oxide layer overlying a non-oxide layer formed in a substrate and having a mask layer overlying said oxide layer to define said hole to be defined in said oxide layer, a minimum width of said hole being no more than 0.4 μm and a depth of said hole being at least 0.7 μm, comprising the steps of: flowing into a plasma reactor a first gas mixture comprising a first amount of a fluorocarbon selected from the group consisting of hexafluorobutadiene, hexafluorocyclobutene, C 5 F 8 , and hexafluorobenzene, a second amount of a chemically inactive diluent gas, and a third amount of a hydrofluorocarbon; from a first oscillatory power supply biasing a pedestal electrode supporting said substrate; and from a second oscillatory power supply exciting said first gas mixture into a plasma to thereby etch said oxide layer selectively to said non-oxide layer; wherein said first and second amounts and power levels of said first and second power supplies are chosen to provide a process window in said first amount of ±20% in which selectivity of etching oxide to non-oxide is at least 10 and no etch stop occurs in said hole.

Claim 65

Dependent Claim 14 words

The method of claim 52 , wherein said non-oxide layer comprises a nitride layer.

Claim 66

Dependent Claim 11 words

The method of claim 52 , wherein said fluorocarbon comprises hexafluorobutadiene.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2006-08-04	2007-02-03	2007-08-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2010-08-04	2011-02-03	2011-08-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2014-08-04	2015-02-03	2015-08-05	$7700.00	Window Closed / Lapsed

Process for etching oxide using hexafluorobutadiene or related fluorocarbons and manifesting a wide process window

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