Method of forming a gate dielectric

A method comprising the sequential steps of:

• providing a semiconductor substrate;
• forming a base oxide layer overlying the semiconductor substrate and forming an interface at a boundary thereof;
• forming a nitrogen-rich layer overlying the base oxide layer by plasma incorporation of nitrogen into the base oxide layer;
• annealing the semiconductor substrate, the base oxide layer and the nitrogen-rich layer in a dilute oxygen and hydrogen-free ambient of below 1 Torr partial pressure of oxygen to heal bond damage in both the base oxide layer and the nitrogen-rich layer;
• placing the semiconductor substrate, base oxide layer and nitrogen-rich layer in an ambient for in-situ steam generation (ISSG), the ISSG growing and densifying the base oxide layer at the interface between the semiconductor substrate and the base oxide layer;
• using the base oxide layer and the nitrogen-rich layer as a gate dielectric;
• forming a transistor gate overlying the gate dielectric;
• forming source and drain diffusions in the semiconductor substrate and adjacent the overlying transistor gate;
• and
• forming a sidewall spacer laterally adjacent sides of the transistor gate.

A method comprising:

• providing a silicon substrate;
• forming a dielectric layer overlying the silicon substrate and adjoining at an interface thereof;
• introducing nitrogen into the dielectric layer with a nonlinear distribution of nitrogen through a depth of the dielectric layer, a greatest amount of nitrogen being present at an exposed surface of the dielectric layer;
• annealing the silicon substrate and the dielectric layer in a dilute oxygen ambient at a temperature of at least 1,000 degrees Celsius, the dilute oxygen ambient being hydrogen-free and having an oxygen partial pressure below 1 Torr to heal bond damage in the dielectric layer;
• after annealing the silicon substrate and the dielectric layer in the dilute oxygen ambient, subjecting the silicon substrate and the dielectric layer to an in-situ steam generation (ISSG) to grow and densify the dielectric layer at the interface between the silicon substrate and the dielectric layer
• forming a gate electrode on the dielectric layer;
• and
• forming a source in the substrate on a first side of the gate electrode and drain in the substrate on a second side of the gate electrode.