US6074959A — Method manifesting a wide process window and usin…

Claim 1

Independent Claim 158 words

A process of etching an oxide layer formed in a substrate and comprising silicon and oxygen overlying a non-metallic, non-oxide layer comprising silicon but substantially less oxygen than in said oxide layer, comprising the steps of: placing said substrate in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; and exciting said etching gas into a plasma to thereby etch a hole having an aspect ratio of at least 2.5 through said oxide layer with a lack of etch stop and with a selectivity to said non-metallic, non-oxide layer of at least 20:1; wherein said first and second amounts having values providing a process window to said first amount of at least ±5% of said first amount, said process window manifesting said selectivity and said lack of etch stop.

Claim 2

Dependent Claim 158 words

A process of etching an oxide layer formed in a substrate and comprising silicon and oxygen overlying a non-metallic, non-oxide layer comprising silicon but substantially less oxygen than in said oxide layer, comprising the steps of: placing said substrate in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; and exciting said etching gas into a plasma to thereby etch a hole having an aspect ratio of at least 2.5 through said oxide layer with a lack of etch stop and with a selectivity to said non-metallic, non-oxide layer of at least 20:1; wherein said first and second amounts having values providing a process window to said first amount of at least ±5% of said first amount, said process window manifesting said selectivity and said lack of etch stop.

Claim 3

Dependent Claim 11 words

The process of claim 1, wherein said hydrofluoropropane gas comprises hexafluoropropane.

Claim 4

Dependent Claim 11 words

The process of claim 1, wherein said hydrofluoropropane gas comprises heptafluoropropane.

Claim 5

Dependent Claim 11 words

The process of claim 1, wherein said hydrofluoropropane gas comprises pentafluoropropane.

Claim 6

Dependent Claim 17 words

The process of claim 1, wherein said hydrofluoropropane gas comprises a plurality of pentafluoropropane, hexafluoropropane, and heptafluoropropane.

Claim 7

Dependent Claim 20 words

The process of claim 1, wherein said chemically inactive gas is selected from the group consisting of helium and argon.

Claim 8

Dependent Claim 21 words

The process of claim 1, wherein said exciting step includes inductively coupling a first level of RF power into said chamber.

Claim 9

Dependent Claim 31 words

The process of claim 7, wherein said first level has a value providing said process with said process window to said first amount of at least ±5% of said first level.

Claim 10

Dependent Claim 25 words

The process of claim 7, wherein said exciting step additionally includes capacitively coupling a second level of RF power to a pedestal supporting said substrate.

Claim 11

Dependent Claim 18 words

The process of claim 1, wherein said exciting step includes exciting said etching gas into a high-density plasma.

Claim 12

Dependent Claim 40 words

The process of claim 1, wherein said admitting steps admits a first amount of said hydrofluoropropane and a second amount of said chemically inactive gas, wherein a ratio of said second amount to said first amount is greater than two.

Claim 13

Dependent Claim 18 words

The process of claim 11, further comprising maintaining a pressure within said chamber of less than 15 milliTorr.

Claim 14

Dependent Claim 15 words

The process of claim 12, wherein said pressure is maintained to greater than 4 milliTorr.

Claim 15

Dependent Claim 17 words

The process of claim 1, further comprising a silicon-based scavenging step for removing fluorine from said plasma.

Claim 16

Dependent Claim 25 words

The process of claim 14, wherein said scavenging step includes placing a silicon-containing body adjacent to said plasma and activating a surface of said body.

Claim 17

Dependent Claim 14 words

The process of claim 15, wherein said activating step includes thermally activating said body.

Claim 18

Dependent Claim 22 words

The process of claim 16, wherein said applying step maintains a surface of body at a temperature of at least 200° C.

Claim 19

Dependent Claim 17 words

The process of claim 15, wherein said activating step includes capacitively coupling RF energy to said body.

Claim 20

Dependent Claim 17 words

The method of claim 14, wherein said scavenging step includes injecting a silicon-containing gas into said chamber.

Claim 21

Dependent Claim 13 words

The process of claim 1, wherein said non-metallic, non-oxide layer comprises silicon nitride.

Claim 22

Dependent Claim 13 words

The process of claim 1, wherein said non-metallic, non-oxide layer comprises silicon oxynitride.

Claim 23

Dependent Claim 148 words

A process of etching an oxide layer formed in a substrate and comprising silicon and oxygen overlying a non-metallic, non-oxide layer comprising silicon but substantially less oxygen than in said oxide layer, comprising the steps of: placing said substrate in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; and exciting said etching gas into a plasma, wherein said first and second amounts having values providing a process window to said first amount of at least ±5% of said first amount, wherein within said process window a selectivity of etching said oxide layer to etching said non-metallic, non-oxide layer is maintained above 20:1 and no etch stop occurs for holes having a critical dimension of less than 0.5 μm.

Claim 24

Dependent Claim 148 words

A process of etching an oxide layer formed in a substrate and comprising silicon and oxygen overlying a non-metallic, non-oxide layer comprising silicon but substantially less oxygen than in said oxide layer, comprising the steps of: placing said substrate in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; and exciting said etching gas into a plasma, wherein said first and second amounts having values providing a process window to said first amount of at least ±5% of said first amount, wherein within said process window a selectivity of etching said oxide layer to etching said non-metallic, non-oxide layer is maintained above 20:1 and no etch stop occurs for holes having a critical dimension of less than 0.5 μm.

Claim 25

Dependent Claim 147 words

A process of etching an oxide layer formed in a substrate and comprising- silicon and oxygen overlying a non-metallic, non-oxide layer comprising silicon but substantially less oxygen than in said oxide layer, comprising the steps of: placing said substrate in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; and exciting said etching gas into a plasma including inductively coupling a first level of RF power into said chamber, and capacitively coupling a second level of RF power to a pedestal supporting said substrate, wherein said second level is greater than said first level, wherein said first and second amounts having values providing a process window to said first amount of at least ±5% of said first amount.

Claim 26

Dependent Claim 147 words

A process of etching an oxide layer formed in a substrate and comprising- silicon and oxygen overlying a non-metallic, non-oxide layer comprising silicon but substantially less oxygen than in said oxide layer, comprising the steps of: placing said substrate in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; and exciting said etching gas into a plasma including inductively coupling a first level of RF power into said chamber, and capacitively coupling a second level of RF power to a pedestal supporting said substrate, wherein said second level is greater than said first level, wherein said first and second amounts having values providing a process window to said first amount of at least ±5% of said first amount.

Claim 27

Dependent Claim 211 words

A process of etching an oxide layer preferentially to a non-metallic, non-oxide layer containing substantially less oxygen than said oxide layer, comprising the steps of: placing a substrate containing said oxide and non-metallic, non-oxide layers onto a pedestal electrode in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; inductively coupling a first power level of RF energy into said chamber to at least partially excite said etching gas into a plasma; capacitively coupling a second power level of RF energy to said pedestal electrode to thereby bias said substrate with respect to said plasma; and maintaining a pressure of said etching gas within said chamber to less than 50 milliTorr; whereby a hole having an aspect ratio of at least 2 is through said oxide layer with a lack of etch stop and with a selectivity to said non-metallic, non-oxide layer of at least 20:1; wherein said first and second power levels have values providing a process window to said first amount of ±5% of said first power level, said process window manifesting said lack of etch stop and said selectivity.

Claim 28

Dependent Claim 211 words

A process of etching an oxide layer preferentially to a non-metallic, non-oxide layer containing substantially less oxygen than said oxide layer, comprising the steps of: placing a substrate containing said oxide and non-metallic, non-oxide layers onto a pedestal electrode in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; inductively coupling a first power level of RF energy into said chamber to at least partially excite said etching gas into a plasma; capacitively coupling a second power level of RF energy to said pedestal electrode to thereby bias said substrate with respect to said plasma; and maintaining a pressure of said etching gas within said chamber to less than 50 milliTorr; whereby a hole having an aspect ratio of at least 2 is through said oxide layer with a lack of etch stop and with a selectivity to said non-metallic, non-oxide layer of at least 20:1; wherein said first and second power levels have values providing a process window to said first amount of ±5% of said first power level, said process window manifesting said lack of etch stop and said selectivity.

Claim 29

Dependent Claim 12 words

The process of claim 24, additionally comprising scavenging fluorine from said plasma.

Claim 30

Dependent Claim 16 words

The process of claim 25, wherein said scavenging comprises activating a silicon-containing surface in said chamber.

Claim 31

Dependent Claim 21 words

The process of claim 26, wherein said activating comprises maintaining said silicon-containing surface at a temperature of at least 180° C.

Claim 32

Dependent Claim 26 words

The process of claim 24, wherein said first amount of said hydrofluoropropane gas is at least twice said second amount amount of said chemically inactive gas.

Claim 33

Dependent Claim 13 words

The process of claim 24, wherein said etching gas additionally comprises another hydrofluorocarbon.

Claim 34

Dependent Claim 11 words

The process of claim 24, wherein said another hydrofluorocarbon comprises difluoromethane.

Claim 35

Dependent Claim 14 words

The process of claim 24, wherein said etching gas additionally comprises a hydrogen-free fluorocarbon.

Claim 36

Dependent Claim 45 words

The process of claim 24, further comprising an establishing step of determining said first and second amounts such that a variation of at least ±5% in said first amount does not reduce said selectivity of etching said oxide layer over said non-oxide layer below 20:1.

Claim 37

Dependent Claim 36 words

The process of claim 32, wherein said establishing step additionally determines that a variation of a pressure in said chamber and a variation of said first power level have respective processing windows of at least ±5%.

Claim 38

Dependent Claim 78 words

The process of claim 24, wherein said oxide layer is a first oxide layer; and wherein a second oxide layer is formed under said non-metallic, non-oxide layer, said process further comprising forming a masking layer over said first oxide layer having a trench shape; and wherein said non-metallic, non-oxide layer has an aperture under a portion of said trench shape prior to said admitting step, whereby said process etches both said oxide layers through said trench-shape masking layer.

Claim 39

Dependent Claim 20 words

The process of claim 24, wherein said chemically inactive gas is selected from the group consisting of helium and argon.

Claim 40

Dependent Claim 174 words

A process of etching an oxide layer preferentially to a non-oxide layer containing substantially less oxygen than said oxide layer, comprising the steps of: placing a substrate containing said oxide and non-oxide layers onto a pedestal electrode in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; inductively coupling a first power level of RF energy into said chamber to at least partially excite said etching gas into a plasma; capacitively coupling a second power level of RF energy to said pedestal electrode to thereby bias said substrate with respect to said plasma; and maintaining a pressure of said etching gas within said chamber to less than 50 milliTorr; wherein said second power level is greater than said first power level and said first and second power levels have values providing a process window to said first amount of ±5% of said first power level.

Claim 41

Dependent Claim 174 words

A process of etching an oxide layer preferentially to a non-oxide layer containing substantially less oxygen than said oxide layer, comprising the steps of: placing a substrate containing said oxide and non-oxide layers onto a pedestal electrode in a plasma reaction chamber; admitting into said chamber an etching gas comprising a first amount of a hydrofluoropropane gas selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second amount of a chemically inactive gas; inductively coupling a first power level of RF energy into said chamber to at least partially excite said etching gas into a plasma; capacitively coupling a second power level of RF energy to said pedestal electrode to thereby bias said substrate with respect to said plasma; and maintaining a pressure of said etching gas within said chamber to less than 50 milliTorr; wherein said second power level is greater than said first power level and said first and second power levels have values providing a process window to said first amount of ±5% of said first power level.

Claim 42

Dependent Claim 20 words

The process of claim 36, wherein said chemically inactive gas is selected from the group consisting of helium and argon.

Claim 43

Dependent Claim 122 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying a non-metallic layer comprising silicon but substantially no oxygen, comprising the steps of: placing said substrate into a reaction chamber; admitting into the chamber an etching gas comprising a first gas of a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second chemically inert gas; controlling the flow of said gases into the chamber to maintain a significantly greater flow rate of the second gas as compared to that of the first gas; and exciting said etching gas into a plasma to thereby etch said oxide layer selectively to said non-metallic, non-oxide layer with a selectivity of at least 20:1.

Claim 44

Dependent Claim 122 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying a non-metallic layer comprising silicon but substantially no oxygen, comprising the steps of: placing said substrate into a reaction chamber; admitting into the chamber an etching gas comprising a first gas of a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane and a second chemically inert gas; controlling the flow of said gases into the chamber to maintain a significantly greater flow rate of the second gas as compared to that of the first gas; and exciting said etching gas into a plasma to thereby etch said oxide layer selectively to said non-metallic, non-oxide layer with a selectivity of at least 20:1.

Claim 45

Dependent Claim 38 words

The process of claim 38, wherein the flows of said first and second gases have values providing a process window to said flow of said first gas of at least ±5% of the flow of said first gas.

Claim 46

Dependent Claim 31 words

The process of claim 38, wherein said exciting step includes inductively coupling RF energy through a coil into said chamber and capacitively coupling RF energy to an electrode supporting said substrate.

Claim 47

Dependent Claim 22 words

The process of claim 38, further comprising the step of reducing a pressure within said reaction chamber to less than 100 milliTorr.

Claim 48

Dependent Claim 15 words

The process of claim 41, wherein said pressure is reduced to less than 50 milliTorr.

Claim 49

Dependent Claim 15 words

The process of claim 42, wherein said pressure is reduced to less than 10 milliTorr.

Claim 50

Dependent Claim 156 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying a layer comprising silicon but substantially no oxygen, comprising the steps of: placing said substrate into a reaction chamber; admitting into the chamber an etching gas comprising a first gas of a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane, and a second chemically inert gas; controlling the flow of said gases into the chamber to maintain a significantly greater flow rate of the second gas as compared to the at of the first gas; and exciting said etching gas into a plasma including inductively coupling RF energy through a coil into said chamber; and capacitively coupling RF energy to an electrode supporting said substrate, wherein more RF energy is coupled to said electrode than through said coil; thereby etching said oxide layer selectively to said non-metallic, non-oxide layer with a selectivity of at least 20:1.

Claim 51

Dependent Claim 156 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying a layer comprising silicon but substantially no oxygen, comprising the steps of: placing said substrate into a reaction chamber; admitting into the chamber an etching gas comprising a first gas of a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane, and a second chemically inert gas; controlling the flow of said gases into the chamber to maintain a significantly greater flow rate of the second gas as compared to the at of the first gas; and exciting said etching gas into a plasma including inductively coupling RF energy through a coil into said chamber; and capacitively coupling RF energy to an electrode supporting said substrate, wherein more RF energy is coupled to said electrode than through said coil; thereby etching said oxide layer selectively to said non-metallic, non-oxide layer with a selectivity of at least 20:1.

Claim 52

Dependent Claim 118 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying an underlying layer comprising silicon but substantially less oxygen than said dielectric layer, comprising the steps of: placing said substrate into a reaction chamber; admitting into said chamber a flow of an etching gas comprising a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane; reducing a pressure within said chamber to less than 50 milliTorr; exciting said gas into a high-density plasma; wherein said flow has a value producing a selectivity of etching said dielectric layer over said underlying layer of at least 20:1 and variations of ±5% in said flow maintains said selectivity at at least 20:1.

Claim 53

Dependent Claim 118 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying an underlying layer comprising silicon but substantially less oxygen than said dielectric layer, comprising the steps of: placing said substrate into a reaction chamber; admitting into said chamber a flow of an etching gas comprising a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane; reducing a pressure within said chamber to less than 50 milliTorr; exciting said gas into a high-density plasma; wherein said flow has a value producing a selectivity of etching said dielectric layer over said underlying layer of at least 20:1 and variations of ±5% in said flow maintains said selectivity at at least 20:1.

Claim 54

Dependent Claim 147 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying an underlying layer comprising silicon but substantially less oxygen than said dielectric layer, comprising the steps of: placing said substrate into a reaction chamber; admitting into said chamber a flow of an etching gas comprising a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane; reducing a pressure within said chamber to less than 50 milliTorr; exciting said gas into a high-density plasma; wherein said value of said flow produces no etch stop in holes formed in said dielectric layer and having an aspect ratio of at least 2 and a critical dimension of less than 0.5 μm produces a selectivity of etching said dielectric layer over said underlying layer of at least 20:1 and variations of ±5% in said flow maintains said selectivity of at least 20:1.

Claim 55

Dependent Claim 147 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying an underlying layer comprising silicon but substantially less oxygen than said dielectric layer, comprising the steps of: placing said substrate into a reaction chamber; admitting into said chamber a flow of an etching gas comprising a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane; reducing a pressure within said chamber to less than 50 milliTorr; exciting said gas into a high-density plasma; wherein said value of said flow produces no etch stop in holes formed in said dielectric layer and having an aspect ratio of at least 2 and a critical dimension of less than 0.5 μm produces a selectivity of etching said dielectric layer over said underlying layer of at least 20:1 and variations of ±5% in said flow maintains said selectivity of at least 20:1.

Claim 56

Dependent Claim 106 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying an underlying layer comprising silicon but substantially less oxygen than said dielectric layer, comprising the steps of: placing said substrate into a reaction chamber; admitting into the chamber an etching gas comprising a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane; reducing a gas pressure within the chamber to less than 100 milliTorr; exciting said etching gas into a plasma; and scavenging fluorine from said plasma such that a selectivity of greater than 20 is obtained for etching said dielectric layer relative to said underlying layer.

Claim 57

Dependent Claim 106 words

A process of etching a dielectric layer formed in a substrate and comprising silicon and oxygen overlying an underlying layer comprising silicon but substantially less oxygen than said dielectric layer, comprising the steps of: placing said substrate into a reaction chamber; admitting into the chamber an etching gas comprising a hydrofluoropropane selected from the group consisting of pentafluoropropane, hexafluoropropane, and heptafluoropropane; reducing a gas pressure within the chamber to less than 100 milliTorr; exciting said etching gas into a plasma; and scavenging fluorine from said plasma such that a selectivity of greater than 20 is obtained for etching said dielectric layer relative to said underlying layer.

Claim 58

Dependent Claim 25 words

The process of claim 47, wherein said scavenging step includes placing a silicon-containing body adjacent to said plasma and activating a surface of said body.

Claim 59

Dependent Claim 14 words

The process of claim 48, wherein said activating step is a thermal activating step.

Claim 60

Dependent Claim 21 words

The process of claim 49, wherein said thermal activating step maintains said body at a temperature of at least 200° C.

Claim 61

Dependent Claim 27 words

The process of claim 48, wherein said scavenging step applies RF energy to said body acting as a counter electrode to a pedestal electrode supporting said wafer.

Claim 62

Dependent Claim 14 words

The process of claim 51, further comprising applying RF energy to said pedestal electrode.

Claim 63

Dependent Claim 16 words

The process of claim 47, wherein said scavenging step injects a silicon-containing gas into said chamber.

Claim 64

Dependent Claim 26 words

The process of claim 47, wherein said process produces said selectivity over a process window of ±5% in the flow of said hydrofluoropropane into said chamber.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2003-06-13	2003-12-13	2004-06-13	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2007-06-13	2007-12-13	2008-06-13	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2011-06-13	2011-12-13	2012-06-13	$7700.00	Window Closed / Lapsed

Method manifesting a wide process window and using hexafluoropropane or other hydrofluoropropanes to selectively etch oxide

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