Method of providing lower contact resistance in MOS transistors
AssigneeNational Semiconductor Corporation
InventorsSheldon Aronowitz, Courtney Hart, Court Skinner
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Abstract
Germanium is used to significantly enhance the drift mobilities of minority carriers in the channels of N-channel and P-channel metal-oxide-semiconductor (MOS) transistors with silicon substrates. Germanium processing is also used to enhance the source/drain contact conductance for MOS devices. Methods are disclosed for forming the germanium-rich interfacial layer utilizing a germanium implant and wet oxidation or growing a silicon-germanium alloy by molecular beam epitaxy.
Claims3
A method of enhancing drift mobility of minority carriers in an MOS transistor, the method comprising the sequential steps of:
- (a) defining a channel region in the surface of a silicon substrate;
- (b) introducing germanium atoms into the previously defined channel region;
- (c) after introducing germanium ions into the channel region, performing an oxidation step to form an oxide layer on the channel region and to create a germanium-rich layer in the channel region at the interfacial region between the channel region and the oxide layer;
- and
- (d) after the oxidation step, forming an MOS transistor structure having source and drain regions separated by the channel region and a gate electrode overlying the channel region and separated therefrom by a layer of dielectric material.
A method of enhancing drift mobility of minority carriers in an MOS transistor, the method comprising the sequential steps of:
- (a) defining a channel region in the surface of a silicon substrate;
- (b) forming an epitaxial layer of silicon-germanium alloy at the surface of the previously defined channel region;
- and
- (c) after forming the epitaxial layer of silicon-germanium alloy, forming an MOS transistor structure having source and drain regions separated by the channel region and a gate electrode overlying the channel region and separated therefrom by a layer of dielectric material.
Dependencies are inferred from the claim text.