The present disclosure describes a semiconductor device with modulated gate structures and a method for forming the same. The method includes forming a fin structure, depositing a polysilicon layer over the fin structure, and forming a photoresist mask layer on the polysilicon layer. The method further includes etching, with a first etching condition, the polysilicon layer not covered by the photoresist mask layer and above a top surface of the fin structure. The method further includes etching, with a second etching condition, the polysilicon layer not covered by the photoresist mask layer and below the top surface of the fin structure, where the etched polysilicon layer below the top surface of the fin structure is narrower than the etched polysilicon layer above the top surface of the fin structure. The method further includes removing the etched polysilicon layer to form a space and forming a gate structure in the space.

A planarization method includes the following steps. A silicon layer is deposited on a substrate, and a top surface of the silicon layer includes a lower portion and a bump portion protruding upwards from the lower portion. An ion bombardment etching process is performed to the silicon layer for reducing a surface step height of the silicon layer. The top surface of the silicon layer is etched by the ion bombardment etching process to become a post-etching top surface, and a distance between a topmost portion of the post-etching top surface and a bottommost portion of the post-etching top surface in a vertical direction is less than a distance between a topmost portion of the bump portion and the lower portion in the vertical direction before the ion bombardment etching process. Subsequently, a chemical mechanical polishing process is performed to the post-etching top surface of the silicon layer.

An etching method includes: providing a substrate having a film and a patterned mask on the film; forming a silicon-containing layer including silicon, carbon, and nitrogen on the substrate using a precursor gas containing silicon; and performing a plasma etching on the film. The substrate is placed under a depressurized environment for a time period from a start time point of the step of forming the silicon-containing layer on the substrate to an end time point of the step of performing the plasma etching on the film.

An etching method includes: a) preparing, within a chamber, a substrate including a mask film containing ruthenium and having a predetermined pattern formed in the mask film, and a silicon-containing film provided under the mask film; b) supplying a process gas including a hydrocarbon-containing gas and a fluorine-containing gas into the chamber; and c) etching the silicon-containing film through the mask film using plasma generated from the process gas supplied into the chamber.

An etching method comprises (a) providing a substrate in a chamber, the substrate including a silicon-containing film and a mask on the silicon-containing film; and (b) etching the silicon-containing film, including (b-1) etching the silicon-containing film using plasma generated from a first process gas, the first process gas containing a hydrogen fluoride gas and a reaction control gas to control a reaction between hydrogen fluoride and the silicon-containing film, the first process gas containing, as the reaction control gas, at least one of a reaction accelerator gas to accelerate the reaction or a reaction inhibitor gas to inhibit the reaction, and (b-2) etching the silicon-containing film using plasma generated from a second process gas, the second process gas containing a hydrogen fluoride gas, and containing at least one of a reaction accelerator gas to accelerate the reaction or a reaction inhibitor gas to inhibit the reaction.

A plasma etching apparatus includes: a chamber; a support configured to support a substrate in the chamber; a gas supply configured to supply a processing gas into the chamber, the processing gas including hydrogen fluoride gas with a volume flow ratio of 30% or more with respect to a total flow rate of the processing gas; a plasma generator configured to generate a plasma from the processing gas in the chamber to etch the substrate with the plasma; and a cooler configured to maintain the support at 0 C. or lower during generation of the plasma.

A method of forming a device includes forming a patterned resist layer over a substrate using an extreme ultraviolet (EUV) lithography process. The method includes forming a mandrel in a plasma processing chamber by selectively depositing a mandrel material over the patterned resist layer, the mandrel including the patterned resist layer and the mandrel material.

A method of forming features in stack with a silicon containing layer below a mask is provided. Features are etched into the stack. A post etch plasma treatment is provided to reduce surface roughness of sidewalls of the features.

A technique increases verticality in etching. An etching method is a method for etching a target film with a plasma processing apparatus including a chamber and a substrate support located in the chamber to support a substrate, the substrate support holding a substrate that includes the target film, the target film including a patterned mask film having at least one opening. The etching method includes supplying a process gas containing an HF gas into the chamber, and etching the target film by: generating plasma from the process gas in the chamber with radio-frequency power having a first frequency, and applying a pulsed voltage periodically to the substrate support at a second frequency lower than the first frequency.