Applied Materials, Inc.

Other

Joseph P Caulfield

Gerald Z Yin

Ruiping Wang

Raymond Hoiman Hung

Hongqing Shan

Jian Ding

Hoiman Raymond Hung

Hoiman (Raymond) Hung

Kenneth S Collins

Michael Robert Rice

Hongching Shan

Chunshi Cui

Gerald Zheyao Yin

Sum-Yee Betty Tang

Hongchin Shan

Tianzong Xu

An oxide etching process, particularly useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. The invention uses a heavy perfluorocarbon, for example, hexafluorobutadiene (CF) or hexafluorobenzene (CF). The fluorocarbon together with a substantial amount of a noble gas such as argon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. A more strongly polymerizing fluorocarbon such as difluoromethane (CHF) is added in the over etch to protect the nitride corner. Oxygen or nitrogen may be added to counteract the polymerization. The same chemistry can be used in a magnetically enhanced reactive ion etcher (MERIE) or with a remote plasma source.

Highly selective process for etching oxide over nitride using hexafluorobutadiene

A plasma etching process, particularly useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. A primary fluorine-containing gas, preferably hexafluorobutadiene (C F ), is combined with a significantly larger amount of the diluent gas xenon (Xe) enhance nitride selectivity without the occurrence of etch stop. The chemistry is also useful for etching oxides in which holes and corners have already been formed, for which the use of xenon also reduces faceting of the oxide. For this use, the relative amount of xenon need not be so high. The invention may be used with related heavy fluorocarbons and other fluorine-based etching gases.

Enhancement of silicon oxide etch rate and nitride selectivity using hexafluorobutadiene or other heavy perfluorocarbon

An oxide etching process, particular useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. The invention preferably uses the unsaturated 4-carbon fluorocarbons, specifically hexafluorobutadiene (C F ), which has a below 10&deg;C. and is commercially available. The hexafluorobutadiene together with argon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. Preferably, a two-step etch is used process is used in which the above etching gas is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH F ) is added in the over etch to protect the nitride corner.

Highly selective oxide etch process using hexafluorobutadiene

An oxide etching process, particularly useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. One aspect of the invention uses one of four hydrogen-free fluorocarbons having a low F/C ratio, specifically hexafluorobutadiene (C F ), octafluoropentadiene (C F ), hexafluorocyclobutene (C F ), and hexafluorobenzene (C F ). At least hexafluorobutadiene has a boiling point below 10&deg; C. and is commercially available. Another aspect of the invention, uses an unsaturated fluorocarbon such as pentafluoropropylene (C HF ), and trifluoropropyne (C HF ), both of which have boiling points below 10&deg; C. and are commercially available. The fluorocarbon together with a substantial amount of a noble gas such as argon or xenon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. Preferably, one of two two-step etch process is used. In the first, the source and bias power are reduced towards the end of the etch. In the second, the fluorocarbon is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH F ) is added in the over etch to protect the nitride corner. The same chemistry can be used in a magnetically enhanced reactive ion etcher (MERIE), preferably with an even larger amount of argon.

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

A plasma etching process, particularly useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. A primary fluorine-containing gas, preferably hexafluorobutadiene (C F ), is combined with a significantly larger amount of the diluent gas xenon (Xe) to enhance nitride selectivity without the occurrence of etch stop. The chemistry is also useful for etching oxides in a time oxide etch in which holes and corners have already been formed, for example counterbore vias in a dual damascene structure. In this case, the relative amount of xenon need not be so high, but xenon still reduces faceting of the oxide corners. The invention may be used with related heavy fluorocarbons and other fluorine-based etching gases. The plasma etching preferably includes striking the plasma with argon, switching to xenon and the fluorine-based gas but at reduced bias power to stabilize the plasma, and then increasing the bias to a full etching level.

Enhancement of silicon oxide etch rate and substrate selectivity with xenon addition

An oxide etching process, particularly useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. The invention uses one of three hydrogen-free fluorocarbons having a low F/C ratio, specifically hexafluorobutadiene (C F ), hexafluorocyclobutene (C F ), and hexafluorobenzene (C F ). At least hexafluorobutadiene has a boiling point below 10&deg; C. and is commercially available. The fluorocarbon together with a substantial amount of a noble gas such as argon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. Preferably, one of two two-step etch process is used. In the first, the source and bias power are reduced towards the end of the etch. In the second, the fluorocarbon is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH F ) is added in the over etch to protect the nitride corner. The same chemistry can be used in a magnetically enhanced reactive ion etcher (MERIE), preferably with an even larger amount of argon.

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

An integrated in situ oxide etch process particularly useful for a counterbore dual-damascene structure over copper having in one inter-layer dielectric level a lower nitride stop layer, a lower oxide dielectric, a lower nitride stop layer, an upper oxide dielectric layer, and an anti-reflective coating (ARC). The process is divided into a counterbore etch and a trench etch with photolithography for each, and each step is preferably performed in a high-density plasma reactor having an inductively coupled plasma source primarily generating the plasma and a capacitively coupled pedestal supporting the wafer and producing the bias power. The counterbore etch preferably includes at least four substeps of opening the ARC, etching through the upper oxide and nitride layers, selectively etching the lower oxide layer but stopping on the lower nitride layer, and a post-etch treatment for removing residue. The trench etch preferably includes the five substeps of opening the ARC, etching through the upper oxide layer but stopping on the upper nitride layers, a first post-etch treatment for removing residue, a nitride removal of the exposed portions of the upper and lower nitride layers, and a second post-etch treatment for remaining further residues. The oxide etches selective to nitride are accomplished using a fluorocarbon chemistry with high bias and a high temperature for a silicon-based scavenger for fluorine placed next to the plasma. The nitride etches and removal are accomplished by adding an oxygen-containing gas to a fluorocarbon. The final nitride removal is accomplished with very low bias power to increase selectivity to nitride and reduce sputtering of the underlying copper. The post-etch treatments are oxygen plasmas with zero bias power.

In-situ integrated oxide etch process particularly useful for copper dual damascene

An integrated self aligned contact process includes oxide etch with high oxide etch rate, integrated selective oxide etch and nitride liner removal with high selectivity to corner nitride with the ability to remove the bottom nitride liner, and stripping of all polymer and photoresist. C,F,and CH,F,are used for the high selectivity oxide etch step. The unique behavior of CH,F,in high density plasma allows polymer protection to form on the nitride corner/sidewall while at the same time etching the bottom nitride.

Integrated self aligned contact etch

An oxide etching process, particular useful for selectively etching oxide over a feature having a non-oxide composition, such as silicon nitride and especially when that feature has a corner that is prone to faceting during the oxide etch. The invention uses one of three unsaturated 3- and 4-carbon fluorocarbons, specifically hexafluorobutadiene (C,F,), pentafluoropropylene (C,HF,), and trifluoropropyne (C,HF,), all of which have boiling points below 10&deg; C. and are commercially available. The unsaturated hydrofluorocarbon together with argon is excited into a high-density plasma in a reactor which inductively couples plasma source power into the chamber and RF biases the pedestal electrode supporting the wafer. Preferably, a two-step etch is used process is used in which the above etching gas is used in the main step to provide a good vertical profile and a more strongly polymerizing fluorocarbon such as difluoromethane (CH,F,) is added in the over etch to protect the nitride corner.

Oxide etch process using hexafluorobutadiene and related unsaturated hydrofluorocarbons

An oxide etch process that is highly selective to nitride, thereby being beneficial for a self-aligned contact etch of silicon dioxide to an underlying thin layer of silicon nitride. The process uses difluoromethane (CH.sub.2 F.sub.2) for its strong polymer forming and a greater amount of trifluoromethane (CHF.sub.3) for its strong etching, and with a high diluent fraction of argon (Ar). The etch process is performed at a low pressure of about 20 milliTorr in a high-density plasma etching chamber.

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Oakland, CA, United States of America

Joseph P Caulfield