LDMOS transistor and method of making the same

The present invention provides an LDMOS transistor (200) and a method for fabricating it. The LDMOS transistor includes an n-type epitaxial layer (206) formed on a p-type substrate (202), and an asymmetric conductive spacer (214) which acts as its gate. The LDMOS transistor also includes a source (212) and a drain (220) region on either side of the asymmetric conductive spacer, and a channel region (218) formed by ion-implantation on the asymmetric conductive spacer. The height of the asymmetric conductive spacer increases from the source region to the drain region. The channel region is essentially completely under the asymmetric conductive spacer and has smaller length than that of the channel region of the prior art LDMOS transistors. The LDMOS transistor of the present invention also includes a field oxide layer (208a,208b) surrounding the active region of the transistor, and a thin dielectric layer (216) isolating the asymmetric conductive spacer from the n-type epitaxial layer.