Patent ID: 7132321

Claim:
A method of making semiconductor substrates suitable for making thin vertical current conducting devices comprising: providing a relatively thick semiconducting substrate with at least one conductivity type having a thickness of from about 100 μm to 700 μm and having a first side and a second side opposite to the first side; thinning the semiconducting substrate in at least one selected region on the second side below at least partially where the active device will be on the first side so as to have the selected region thinned to a thickness ranging from about 10 μm to 400 m to form at least one deep trench; controlling the depth of the thinning of the semiconducting substrate when the substrate has more than one conductivity type layers or more than one conductivity type layer concentrations so that either (a) some of a first conductivity type layer or some of a first conductivity type layer concentration remains or (b) thinning all the way through the first conductivity type layer or all the way through the first conductivity type layer concentration; forming a current electrode on the second side in contact with said thinned selected region or said conductivity type dopant in said thinned selected region; and forming at least one active device region on the first side of said relatively thick substrate.