Method for producing a semiconductor device having a semiconductor layer of SiC

Claim 1

A method for producing a semiconductor device having a semiconductor layer of a SiC, said method comprising the steps of a) supplying dopants to the surface of the SiC layer during heating thereof for diffusion of said dopants into the SiC layer, and b) prior to step a) highly doping at least a portion of the surface layer in the peripheral regions of the SiC layer with dopants of the same conductivity type as that of the dopants for said diffusion for obtaining enhanced diffusion of dopants at the periphery of the SiC layer under said surface layer portion, and wherein the heat treatment and thereby the diffusion in step a) is carried out under such conditions that the dopants may penetrate through a junction thereby creating the space charge region of said device for creating a guard ring arranged to smooth out the electric field in the peripheral region during a blocking state of the power device.

Claim 2

A method for producing a semiconductor device having a semiconductor layer of a SiC, said method comprising the steps of a) supplying dopants to the surface of the SiC layer during heating thereof for diffusion of said dopants into the SiC layer, and b) prior to step a) highly doping at least a portion of the surface layer in the peripheral regions of the SiC layer with dopants of the same conductivity type as that of the dopants for said diffusion for obtaining enhanced diffusion of dopants at the periphery of the SiC layer under said surface layer portion, and wherein the heat treatment and thereby the diffusion in step a) is carried out under such conditions that the dopants may penetrate through a junction thereby creating the space charge region of said device for creating a guard ring arranged to smooth out the electric field in the peripheral region during a blocking state of the power device.

Claim 3

A method for producing a semiconductor device having a semiconductor layer of a SiC, said method comprising the steps of a) supplying dopants to the surface of the SiC layer during heating thereof for diffusion of said dopants into the SiC layer, and b) highly doping at least a portion of the surface layer of the SiC layer prior to step a) with dopants of an opposite conductivity type to that of the dopants supplied for said diffusion, to control diffusion of dopants into the SiC layer under said surface layer portion, whereby said surface layer portion in step a) functions as a diffusion mask and wherein said mask is first created by epitaxial growth of a highly doped layer followed by a patterning thereof for removing said mask layer in the peripheral regions of the SiC layer, an ion implantation is then carried out for creating a thin highly doped surface layer in said peripheral regions, then the SiC layer is annealed so as to re-crystallize the ion-implanted layer, said diffusion step is carried out for forming a guard ring, and then the mask layer is removed in a non-mechanical way.

Claim 4

A method for producing a semiconductor device having a semiconductor layer of a SiC, said method comprising the steps of a) supplying dopants to the surface of the SiC layer during heating thereof for diffusion of said dopants into the SiC layer, and b) highly doping at least a portion of the surface layer of the SiC layer prior to step a) with dopants of an opposite conductivity type to that of the dopants supplied for said diffusion, to control diffusion of dopants into the SiC layer under said surface layer portion, whereby said surface layer portion in step a) functions as a diffusion mask and wherein said mask is first created by epitaxial growth of a highly doped layer followed by a patterning thereof for removing said mask layer in the peripheral regions of the SiC layer, an ion implantation is then carried out for creating a thin highly doped surface layer in said peripheral regions, then the SiC layer is annealed so as to re-crystallize the ion-implanted layer, said diffusion step is carried out for forming a guard ring, and then the mask layer is removed in a non-mechanical way.