Methods of forming field effect transistors and related field effect transistor constructions

A method of forming a field effect transistor comprising:

• forming an opening through a masking layer disposed over a substrate having a first conductivity type, the opening comprising a pair of sidewalls and defining a substrate area within which a transistor channel region is to be formed;
• providing halo doping impurity through the opening and into the substrate, the halo doping impurity comprising the first conductivity type and having portions which extend outwardly of the substrate area within which the channel region is to be formed;
• providing a doping impurity type into the substrate opposite from the first conductivity type, said doping impurity type defining at least a portion of the channel region;
• and
• forming sidewall spacers over the opening's sidewalls after providing the halo doping impurity.

A method of forming a field effect transistor comprising:

• providing a silicon substrate comprising a first conductivity type;
• forming a masking layer over the substrate;
• forming an opening through the masking layer, the opening comprising a pair of sidewalls and defining a substrate area within which a transistor channel region is to be formed;
• providing halo doping impurity through the opening and into the substrate, the halo doping impurity comprising the first conductivity type and having portions which extend outwardly of the substrate area within which the channel region is to be formed;
• providing a doping impurity type into the substrate which is different from the first conductivity type and defining at least a portion of the channel region;
• forming sidewall spacers over the opening's sidewalls after providing the halo doping impurity;
• and
• forming a transistor gate within the opening and over the channel region and source/drain diffusion regions laterally proximate the channel region.