US 8,569,138 B2 · Drain extended MOS transistor and method for fabricating the same

Abstract

A drain extended MOS (DEMOS) transistor including at least one of: (1) A p-type epitaxial layer grown over an n-type semiconductor substrate. (2) An n-type well formed in a portion of the epitaxial layer. (3) A p-type drift region formed in another portion of the epitaxial layer. (4) A p-type source region formed in the well. (5) A p-type drain region formed in the drift region and spaced apart from the source region inside the epitaxial layer. (6) An n-type channel region extending between the drift region and the source region. (7) A gate structure formed over the channel region. (8) An n-type buried layer having a contact surface with the well and the drift region and formed in the epitaxial layer. A region of the buried layer has surface contact with the drift region and has a relatively low dopant concentration compared to other regions.

Claims4

Dependent claims

A method of fabricating a DEMOS transistor, comprising:

providing a first conductive type silicon substrate;
forming a second conductive type buried layer having a different concentration distributions in portion of the silicon substrate;
forming an epitaxial silicon layer over the silicon substrate;
defining a second conductive type well and a first conductive type drift region in the epitaxial silicon layer;
forming a first conductive type source region and a second conductive type back gate in the second conductive type well;
forming a first conductive type expanded drain in the drift region,
wherein, in the forming of the second conductive type buried layer, the buried layer is formed such that a first region adjacent to the drift region has a lower dopant concentration than a second region, wherein the second region is outside of the first region.

4 more elements

Dependencies are inferred from the claim text.

Drain extended MOS transistor and method for fabricating the same

Life of this patent

Drain extended MOS transistor and method for fabricating the same

Life of this patent

Abstract

Claims4