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US 4,050,967 AGranted
Method of selective aluminum diffusion
AssigneeRCA Corporation
InventorsWojciech Rosnowski, Samuel Ponczak
Life of this patent
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Abstract
A silicon substrate is coated with a mask comprised of the combination of a silicon dioxide layer and a layer of undoped polycrystalline silicon. Aluminum is then diffused through windows formed in the mask. The mask has proven effective for relatively deep aluminum diffusion.
Claims10
A method of selectively diffusing aluminum into a wafer including a silicon body having a surface comprising:
- forming a masking layer comprising a layer of silicon dioxide and a layer of polycrystalline silicon on a surface of said body;
- forming an opening in at least one of said layers thereby defining a masked portion and an unmasked portion of said surface;
- subjecting said wafer, including both the unmasked portion of said surface and said masked portion to a source of aluminum impurities;
- and
- diffusing said aluminum through said opening and into said body.
2 more elements
Dependencies are inferred from the claim text.