Method for forming a semiconductor device

Abstract

A method for forming a semiconductor device includes forming an electrical structure at a main surface of a semiconductor substrate and carrying out an anodic oxidation of a back side surface region of a back side surface of the semiconductor substrate to form an oxide layer at the back side surface of the semiconductor substrate. Additionally, the method includes connecting a carrier substrate to the oxide layer and processing a back side of the semiconductor substrate.

What is claimed is: 
     
         1 . A method for forming a semiconductor device, the method comprising:
 forming an electrically conductive layer above a main surface of a semiconductor substrate;   carrying out an anodic oxidation of a surface of the electrically conductive layer to form an oxide layer at the surface of the electrically conductive layer;   connecting a carrier substrate to the oxide layer; and   processing a back side of the semiconductor substrate.   
     
     
         2 . The method according to  claim 1 , wherein a surface of the oxide layer comprises at least one uneven area causing a gap between the carrier substrate and the oxide layer, wherein the method further comprises removing the carrier wafer by inserting acid at least into the gap. 
     
     
         3 . A method for forming a semiconductor device, the method comprising:
 forming an edge termination trench extending from a main surface of a semiconductor substrate towards an opposite back side of the semiconductor substrate, wherein the trench surrounds an active area of the semiconductor device; and   carrying out an anodic oxidation of a surface of the edge termination trench to form an oxide layer at least at a wall of the edge termination trench.   
     
     
         4 . The method according to  claim 3 , further comprising at least partly filling the edge termination trench with a polymer. 
     
     
         5 . The method according to  claim 3 , wherein processes for forming structures associated with the semiconductor substrate carried out after the anodic oxidation comprise process temperatures below 650° C. 
     
     
         6 . The method according to  claim 3 , further comprising forming at least one field effect transistor structure at the main surface of the semiconductor substrate. 
     
     
         7 . The method according to  claim 3 , wherein at least one semiconductor structure of the semiconductor device comprises a blocking voltage of more than 10V. 
     
     
         8 . A method for forming a semiconductor device, the method comprising:
 forming an electrical structure at a main surface of a semiconductor substrate; and   carrying out an anodic oxidation of a back side surface region of a back side surface of the semiconductor substrate to form an oxide layer at the back side surface of the semiconductor substrate.   
     
     
         9 . The method according to  claim 8 , comprising forming a p-doped region adjacent to an n-doped region at the back side surface of the semiconductor substrate, wherein the oxide layer in a first portion of the back side surface extending along the n-doped region has a greater thickness than the oxide layer in a second portion of the back side surface extending along the p-doped region. 
     
     
         10 . The method according to  claim 8 , further comprising removing the oxide layer at a back side emitter region and forming an emitter doping region of an insulated gate bipolar transistor within the semiconductor substrate at the back side emitter region arranged at the back side surface of the semiconductor substrate. 
     
     
         11 . The method according to  claim 10 , further comprising implanting dopants of a first conductivity type with an implant energy higher than an implant energy used for forming the emitter doping region to generate a first conductivity type doping layer within a region covered by the oxide layer and within the back side emitter region, where the first conductivity type doping layer extends to a first average depth within the back side emitter region and to a second average depth within the region covered by the oxide layer, wherein the first depth is larger than the second depth. 
     
     
         12 . The method according to  claim 10 , wherein the emitter doping region comprises a first conductivity type and an adjacent part of the semiconductor substrate comprises a second conductivity type. 
     
     
         13 . The method according to  claim 8 , further comprising forming a field effect transistor structure at the back side of the semiconductor substrate, wherein the oxide layer forms a gate oxide of the field effect transistor structure at the back side. 
     
     
         14 . The method according to  claim 8 , further comprising forming a trench extending from the back side surface to a part of the electrical structure at the main side of the semiconductor substrate, wherein the oxide layer formed during the anodic oxidation covers at least a wall of the trench, wherein the electrical structure at the main surface is a doping region of a diode or a transistor, a gate of a transistor or a metallization of a diode, a transistor, a resistor, a capacitor or an inductor. 
     
     
         15 . The method according to  claim 8 , wherein the oxide layer is formed with a gradient by a variation of the magnitude of the p-doping at the back side surface of the semiconductor surface.