Abstract: Exemplary methods of etching a silicon-containing material may include flowing a first fluorine-containing precursor into a remote plasma region of a semiconductor processing chamber. The methods may include flowing a sulfur-containing precursor into the remote plasma region of the semiconductor processing chamber. The methods may include forming a plasma within the remote plasma region to generate plasma effluents of the first fluorine-containing precursor and the sulfur-containing precursor. The methods may include flowing the plasma effluents into a processing region of the semiconductor processing chamber. A substrate may be positioned within the processing region. The substrate may include a trench formed through stacked layers including alternating layers of silicon nitride and silicon oxide. The methods may include isotropically etching the layers of silicon nitride while substantially maintaining the silicon oxide.

Abstract: A layered exhaust treatment catalyst comprising: (a) a carrier such as cordierite; (b) a first layer deposited on the carrier comprising a palladium metal component, a platinum metal component and an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina; and (c) a second layer deposited on the first layer comprising a rhodium metal component, a platinum metal component and an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina. Preferably, the catalyst also includes a bottom layer interposed between the carrier and the first layer. The bottom layer comprises an oxygen storage component such as ceria supported on a refractory metal oxide such as gamma-alumina. The amount of the oxygen storage component of the catalyst may be “tuned”, i.e., adjusted, to meet the needs of a vehicle's on-board diagnostic (“OBD”) catalyst efficiency monitoring system, without adversely affecting the performance of the catalyst.