Magnetically enhanced plasma etch process using a heavy fluorocarbon etching gas
First Claim
1. A method for etching an oxide layer with increased selectivity to photoresist, comprising the steps of:
- providing a magnetically enhanced plasma etch reactor chamber having a pedestal electrode supporting a substrate having said oxide layer to be etched;
flowing into said chamber an etching gas mixture comprising (a) hexafluorobutadiene, (b) oxygen, and (c) a chemically inactive carrier gas selected from the group consisting of argon and xenon and containing essentially no carbon monoxide;
applying a magnetic field substantially parallel to said pedestal electrode; and
applying RF electrical power to said pedestal electrode to provide the only significant power to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask comprising photoresist overlying said oxide layer with an etching selectivity to a facet of said photoresist of at least 5;
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1 Assignment
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Accused Products
Abstract
An oxide etch process practiced in magnetically enhanced reactive ion etch (MERIE) plasma reactor. The etching gas includes approximately equal amounts of a hydrogen-free fluorocarbon, most preferably C4F6, and oxygen and a much larger amount of argon diluent gas. The magnetic field is preferably maintained above about 50 gauss and the pressure at 40 milliTorr or above with chamber residence times of less than 70 milliseconds. A two-step process may be used for etching holes with very high aspect ratios. In the second step, the magnetic filed and the oxygen flow are reduced. Other fluorocarbons may be substituted which have F/C ratios of less than 2 and more preferably no more than 1.6 or 1.5.
99 Citations
47 Claims
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1. A method for etching an oxide layer with increased selectivity to photoresist, comprising the steps of:
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providing a magnetically enhanced plasma etch reactor chamber having a pedestal electrode supporting a substrate having said oxide layer to be etched;
flowing into said chamber an etching gas mixture comprising (a) hexafluorobutadiene, (b) oxygen, and (c) a chemically inactive carrier gas selected from the group consisting of argon and xenon and containing essentially no carbon monoxide;
applying a magnetic field substantially parallel to said pedestal electrode; and
applying RF electrical power to said pedestal electrode to provide the only significant power to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask comprising photoresist overlying said oxide layer with an etching selectivity to a facet of said photoresist of at least 5;
1.- View Dependent Claims (3, 6, 20)
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2. A method for etching an oxide layer with increased selectivity to photoresist, comprising the steps of:
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providing a magnetically enhanced plasma etch reactor chamber having a pedestal electrode supporting a substrate having said oxide layer to be etched in opposition to a showerhead and further including at least one magnetic coil positioned on a side of said showerhead towards said pedestal electrodes;
flowing through said showerhead into said chamber an etching gas mixture comprising (a) a fluorocarbon having at least four carbon atoms and an F/C ratio of less than 2, (b) oxygen, and (c) a chemically inactive carrier gas selected from the group consisting of argon and xenon;
applying a magnetic field substantially parallel to said pedestal electrode by powering said at least one magnetic coil; and
applying RF electrical power to said pedestal electrode to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask comprising photoresist overlying said oxide layer with an etching selectivity to a facet of said photoresist of at least 5;
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wherein in a first step said magnetic field is applied to a first field strength and wherein in a second step said magnetic field is applied to a second field strength less than said first field strength. - View Dependent Claims (4, 5, 21, 22, 23, 24, 25)
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7. A method for etching an oxide layer with increased selectivity to photoresist, comprising the steps of:
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providing a magnetically enhanced plasma etch reactor chamber having a pedestal electrode supporting a substrate having said oxide layer to be etched;
flowing into said chamber an etching gas mixture comprising (a) a fluorocarbon having at least four carbon atoms and an F/C ratio of less than 2, (b) oxygen, and (c) a chemically inactive carrier gas selected from the group consisting of argon and xenon;
applying a magnetic field substantially parallel to said pedestal electrode; and
applying RF electrical power to said pedestal electrode to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask comprising photoresist overlying said oxide layer with an etching selectivity to a facet of said photoresist of at least 5;
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vacuum pumping said chamber to maintain a residence time of said etching gas mixture in said chamber of no more than 70 milliseconds. - View Dependent Claims (8, 9, 26, 27, 28, 41)
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10. A method of etching a hole in an oxide layer, comprising the steps of:
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providing a magnetically enhanced reactive ion plasma etch reactor;
flowing into said reactor an etching gas mixture comprising a first amount of C4F6, a second amount of O2, and a third amount of argon and containing essentially no carbon monoxide;
applying a magnetic field in said reactor;
applying RF power to a pedestal electrode supporting a substrate containing said oxide layer to excite said etching gas mixture into a plasma to etch said oxide layer. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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29. In a magnetically enhanced plasma etch reactor chamber having a pedestal electrode in opposition to a showerhead, a method for etching an oxide layer in a substrate supported on said pedestal electrode in said chamber, comprising two sequentially performed steps each comprising the sub-steps of:
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flowing into said chamber through said showerhead an etching gas mixture comprising (a) a fluorocarbon and (b) a chemically inactive carrier gas selected from the group consisting of argon and xenon;
applying a magnetic field adjacent to said pedestal electrode; and
applying RF electrical power to said pedestal electrode to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask comprising photoresist overlying said oxide layer;
wherein during a first one of said steps said magnetic field has a first field strength level and during a second one of said steps said magnetic field has a second field strength level less than said first field strength level. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 42)
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37. In a magnetically enhanced plasma etch reactor chamber having a pedestal electrode, a method for etching an oxide layer in a substrate supported on said pedestal electrode in said chamber, comprising two sequentially performed steps each comprising the sub-steps of:
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flowing into said chamber an etching gas mixture comprising (a) a fluorocarbon having at least four carbon atoms and an F/C ratio of less than 2, (b) oxygen, and (c) a chemically inactive carrier gas selected from the group consisting of argon and xenon;
applying a magnetic field substantially parallel to said pedestal electrode; and
applying RF electrical power to said pedestal electrode to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask comprising photoresist overlying said oxide layer;
wherein a ratio of a flow of said oxygen to a flow of said fluorocarbon is higher in a first one of said steps than in a second one of said steps. - View Dependent Claims (38, 39, 40)
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43. A method for etching an oxide layer, comprising the steps of:
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providing a magnetically enhanced plasma etch reactor chamber having a pedestal electrode supporting in opposition to a showerhead a substrate having said oxide layer to be etched;
flowing through said showerhead into said chamber an etching gas comprising (a) a fluorocarbon selected from the group consisting of C4F6, C5F8, and C6F6, (b) oxygen, and (c) a chemically inactive carrier gas selected from the group consisting of argon and xenon, said etching gas including essentially no CO;
applying a magnetic field parallel to said pedestal electrode; and
applying RF electrical power to said pedestal electrode to excite said etching gas mixture into a plasma to thereby etch a hole into said oxide layer defined by a patterned photomask overlying said oxide layer. - View Dependent Claims (44, 45, 46, 47)
wherein at least one magnetic coil is disposed on a side of said showerhead towards said pedestal electrode; and
a wherein said step of applying said magnetic field comprises powering said magnetic coil.
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Specification