US Patent 10374034 Undercut control in isotropic wet etch processes

A method for manufacturing a semiconductor device includes forming a first nanosheet device and forming a second nanosheet device spaced apart from the first nanosheet device in respective first and second regions corresponding to first and second types. The first and second nanosheet devices respectively include a first and a second plurality of work function metal layers, and a work function metal layer extends from the first and second plurality of work function metal layers in the space between the nanosheet devices. In the method, part of the work function metal layer is removed from the space between the nanosheet devices, and the removed part of the work function metal layer is replaced with a polymer brush layer. The first plurality of work function metal layers is selectively removed from the first region with respect to the polymer brush layer.