Self-aligned contact etch with high sensitivity to nitride shoulder
First Claim
1. A method for etching a substrate, comprising the steps of:
- providing a substrate comprising at least one oxide layer, and etching the oxide layer with a plasma based on a mixture of oxygen and at least a first and second gas;
wherein the first gas has the formula CaFb, wherein the second gas has the formula CxHyFz wherein a/b≧
⅔
, wherein x/z≧
½
, and wherein a, b, x, y, and z are all greater than 0.
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Accused Products
Abstract
A method and apparatus are provided for etching semiconductor and dielectric substrates through the use of plasmas based on mixtures of a first gas having the formula CaFb, and a second gas having the formula CxHyFz, wherein a/b≧⅔, and wherein x/z≧½. The mixtures may be used in low or medium density plasmas sustained in a magnetically enhanced reactive ion chamber to provide a process that exhibits excellent corner layer selectivity, photo resist selectivity, under layer selectivity, and profile and bottom CD control. The percentages of the first and second gas may be varied during etching to provide a plasma that etches undoped oxide films or to provide an etch stop on such films.
254 Citations
80 Claims
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1. A method for etching a substrate, comprising the steps of:
-
providing a substrate comprising at least one oxide layer, and etching the oxide layer with a plasma based on a mixture of oxygen and at least a first and second gas;
wherein the first gas has the formula CaFb, wherein the second gas has the formula CxHyFz wherein a/b≧
⅔
, wherein x/z≧
½
, and wherein a, b, x, y, and z are all greater than 0. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
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36. A method for etching a substrate, comprising the steps of:
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positioning in a chamber a structure comprising a first layer disposed on a substrate, the first layer being selected from the group consisting of dielectric layers and semiconductor layers;
supplying a reactive gas mixture to the chamber, the gas mixture comprising a first gas having the formula CaFb and a second gas having the formula CxHyFz, wherein a/b≧
⅔ and
x/z≧
½
, and wherein a, b, x, y, and z are all greater than 0;
applying sufficient RF energy to the chamber to establish an etching plasma and an associated electric field perpendicular to the surface of the substrate;
applying a magnetic field to the chamber substantially perpendicular to the electric field and substantially parallel to the surface of the substrate; and
allowing the plasma to etch at least a portion of the first layer. - View Dependent Claims (37, 38, 39, 40, 41, 42, 43, 44)
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45. A method for etching a substrate, comprising the steps of:
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providing a substrate selected from the group consisting of semiconductor and dielectric substrates; and
etching the substrate through a magnetically enhanced reactive ion etch process, the process including the addition of a source of hydrogen radicals to a gas mixture in an amount sufficient to increase the value of at least one parameter selected from the group consisting of etch rate and selectivity of the reactive gas mixture for the substrate;
wherein the gas mixture comprises a first gas having the formula CaFb and a second gas having the formula CxHyFz, and wherein a/b≧
⅔ and
x/z≧
½
, and wherein a, b, x, y, and z are all greater than 0.
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46. A apparatus for etching substrates, comprising:
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a chamber adapted to receive a substrate to be etched; and
at least one reservoir in open communication with said chamber, said at least one reservoir adapted to supply a gas mixture to the chamber, said gas mixture comprising a first gas having the formula Cab and a second gas having the formula CxHyFz, wherein a/b≧
⅔ and
x/z≧
½
, and wherein a, b, x, y, and z are all greater than 0. - View Dependent Claims (47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66)
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67. A method for etching a substrate, comprising the steps of:
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providing a substrate selected from the group consisting of semiconductor and dielectric substrates;
etching the substrate through the use of a plasma based on a gaseous mixture comprising C4F6, O2, and Ar, thereby forming a modified substrate; and
further etching the modified substrate through the use of a plasma based on a gaseous mixture comprising C4F6, O2, Ar, and C2H2F4.
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68. A method for etching a substrate, comprising the steps of:
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providing a substrate comprising (a) a first layer comprising a doped oxide, and (b) a second layer, comprising an undoped oxide;
etching the substrate through the use of a plasma based on a first gaseous mixture comprising C4F6, O2 and Ar so as to form a depression that extends at least partially through the second layer, but does not extend substantially into the first layer, thereby forming a modified substrate; and
etching the modified substrate through the use of a plasma based on a second gaseous mixture comprising C4F6, O2, C2H2F4, and Ar so as to extend the depression substantially into the first layer. - View Dependent Claims (69, 70, 71, 72, 73, 74)
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75. An article, comprising:
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a substrate;
first and second gate structures disposed on said substrate, said first and second gate structures being separated by a gap of less than about 0.25 microns;
a layer of silicon nitride disposed over said gate structures and said gap;
a layer of doped oxide disposed over said layer of silicon nitride; and
a layer of undoped oxide disposed over said layer of doped oxide. - View Dependent Claims (76, 77, 78, 79, 80)
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Specification