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US 4,233,093 AGranted
Process for the manufacture of PNP transistors high power
OwnerPel Chowinventor
Life of this patent
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Abstract
PNP high power transistors are made in high yield by a process wherein the base diffusion step is conducted in a diffusion furnace wherein phosphorus is deposited on the walls of the furnace. This results in a sharp collector to base junction.
Claims5
In the process of making PNP high power transistors wherein a silicon wafer is predoped with a N-type impurity such as phosphorus and the wafer heated in a base diffusion step to diffuse the dopant into the body of the silicon, the improvement comprising carrying out said diffusion step in a heated reaction vessel wherein the walls of the vessel have been first precoated with phosphorus.
Dependencies are inferred from the claim text.