Method of achieving high selectivity for high aspect ratio dielectric etch
AssigneeLam Research Corporation
InventorsNikhil Dole, Takumi Yanagawa
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Abstract
Various embodiments herein relate to methods and apparatus for etching a feature in a substrate. Often, the feature is etched in the context of forming a DRAM device. The feature is etched in dielectric material, which often includes silicon oxide. The feature is etched using chemistry that includes WF6. Although WF6 is commonly used as a deposition gas (e.g., to deposit tungsten-containing film), it can also be used during etching. Advantageously, the inclusion of WF6 in the etch chemistry can increase the etch rate of the dielectric material, as well as increase the selectivity of the etch. Unexpectedly, these benefits can be realized without any increase in capping.
Claims20
A method of etching a feature in dielectric material on a substrate while fabricating a memory structure, the method comprising:
- receiving the substrate on a substrate support in a reaction chamber, the substrate comprising the dielectric material under a mask layer that is patterned, the dielectric material comprising silicon oxide;
- and
- exposing the substrate to a plasma in the reaction chamber to thereby etch the feature in the dielectric material on the substrate, wherein the plasma is generated from a plasma generating gas comprising WF6, one or more fluorocarbons, and oxygen (O2), wherein the plasma is a capacitively-coupled plasma and the substrate is biased, wherein the substrate support is maintained at a temperature between about −80° C. and 130° C. while the substrate is exposed to the plasma, and wherein the WF6 dissociates in the plasma into tungsten-containing fragments and fluorine-containing fragments, and wherein the substrate is biased and exposed to the capacitively-coupled plasma under conditions such that the tungsten-containing fragments preferentially attach to upper sidewalls of the feature compared to lower sidewalls of the feature and the fluorine-containing fragments travel to the bottom of the feature to further etch the feature.
A method of etching a feature in dielectric material on a substrate while fabricating a memory structure, the method comprising:
- receiving the substrate on a substrate support in a reaction chamber, the substrate comprising the dielectric material under a mask layer that is patterned, the dielectric material comprising silicon oxide, wherein the dielectric material is provided in a dielectric stack comprising at least a first layer of silicon oxide, at least a first layer of silicon nitride, and at least a second layer of silicon oxide, the first layer of silicon oxide being positioned below the first layer of silicon nitride and the second layer of silicon oxide being positioned above the first layer of silicon nitride;
- etching the second layer of silicon oxide without WF6 prior to etching the first layer of silicon nitride;
- etching the first layer of silicon nitride without WF6 prior to etching the first layer of silicon oxide;
- and
- etching the first layer of silicon oxide by exposing the substrate to a plasma in the reaction chamber to thereby etch the feature in the dielectric material on the substrate, wherein the plasma is generated from a plasma generating gas comprising WF6, one or more fluorocarbons, and oxygen (O2), wherein the plasma is a capacitively-coupled plasma and the substrate is biased, wherein the substrate support is maintained at a temperature between about −80° C. and 130° C. while the substrate is exposed to the plasma.
Dependencies are inferred from the claim text.