DOUBLE-RESURF LDMOS WITH DRIFT AND PSURF IMPLANTS SELF-ALIGNED TO A STACKED GATE "BUMP" STRUCTURE

摘要

A double-RESURF LDMOS transistor has a gate dielectric structure including a shallow field “bump” oxide region and an optional raised dielectric structure that provides a raised support for the LDMOS transistor's polysilicon gate electrode. Fabrication of the shallow field oxide region is performed through a hard “bump” mask and controlled such that the bump oxide extends a minimal depth into the LDMOS transistor's drift (channel) region. The hard “bump” mask is also utilized to produce an N-type drift (N-drift) implant region and a P-type surface effect (P-surf) implant region, whereby these implants are “self-aligned” to the gate dielectric structure. The N-drift implant is maintained at Vdd by connection to the LDMOS transistor's drain diffusion. An additional Boron implant is utilized to form a P-type buried layer that connects the P-surf implant to the P-body region of the LDMOS transistor, whereby the P-surf implant is maintained at 0V.

主权项

1. A method of fabricating a double-RESURF LDMOS transistor on a semiconductor substrate, the method comprising:
forming a well region in the semiconductor substrate using a dopant having a first conductivity type, and a base oxide layer on an upper surface of the semiconductor substrate over a first portion of the well region; forming a mask on the upper surface such that the mask defines an opening that exposes a portion of the upper surface located over a second portion of the well region; forming a drift implant region and a surface field implant in the semiconductor substrate by implanting associated dopant materials through the opening defined in the mask; forming a gate dielectric structure inside the opening defined in the mask such that both the drift implant region and the surface field implant are self-aligned to the gate dielectric structure; removing the mask; and forming a gate electrode on a portion of the base oxide layer and a portion of the gate dielectric structure.