Patent ID: 9105712
Filing Date: 2015-08-11
Classification: H01L

Abstract:
1. A method for fabricating a double-RESURF LDMOS transistor including an N+ buried layer and a P-surf region disposed over the N+ buried layer, the method comprising: forming a mask on a surface of a substrate, the mask consisting of a mask material layer defining both at least one first opening disposed over a first region of the substrate, and a plurality of second openings disposed over a second region of the substrate, wherein the first opening is larger than each of the second openings in at least one direction; directing a P-type implant material and an N-type implant material onto the mask, a first implant material of said P-type and N-type implant materials being directed at a first angle onto the mask such that the first implant material only passes through the at least one first opening and forms a first implant region only in the first region of the substrate, and a second implant material of said P-type and N-type implant materials being directed at a second angle such that the second implant material passes through both said at least one first opening and said plurality of second openings such that subsequent annealing causes the second implant material to form a second implant region disposed in both the first region and the second region of the substrate; forming an epitaxial layer on the substrate over the first and second implant regions; and annealing the substrate such that the first implant material forming the first implant region diffuses from the first region into the epitaxial layer to form a first buried layer of a P+ buried layer and said N+ buried layer, and such that the second implant material forming the second implant region diffuses from the first and second regions into the epitaxial layer to form a second buried layer of said P+ buried layer and said N+ buried layer, wherein the P-type implant material forming the P+ buried layer form a P+ buried layer including a P-surf region disposed between the N+ buried layer and an upper surface of the epitaxial layer.