Active solid-state devices (e.g. – transistors – solid-state diode – Including semiconductor material other than silicon or... – Containing germanium – ge
Reexamination Certificate
2008-07-29
2008-07-29
Prenty, Mark (Department: 2822)
Active solid-state devices (e.g., transistors, solid-state diode
Including semiconductor material other than silicon or...
Containing germanium, ge
C257S656000, C365S075000
Reexamination Certificate
active
07405465
ABSTRACT:
In deposited silicon, n-type dopants such as phosphorus and arsenic tend to seek the surface of the silicon, rising as the layer is deposited. When a second undoped or p-doped silicon layer is deposited on n-doped silicon with no n-type dopant provided, a first thickness of this second silicon layer nonetheless tends to include unwanted n-type dopant which has diffused up from lower levels. This surface-seeking behavior diminishes when germanium is alloyed with the silicon. In some devices, it may not be advantageous for the second layer to have significant germanium content. In the present invention, a first heavily n-doped semiconductor layer (preferably at least 10 at % germanium) is deposited, followed by a silicon-germanium capping layer with little or no n-type dopant, followed by a layer with little or no n-type dopant and less than 10 at % germanium. The germanium in the first layer and the capping layer minimizes diffusion of n-type dopant into the germanium-poor layer above.
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Dugan & Dugan PC
Prenty Mark
SanDisk 3D LLC
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