Browse Prior Art Database

Contact Hole Cleaning Process

IP.com Disclosure Number: IPCOM000073369D
Original Publication Date: 1970-Dec-01
Included in the Prior Art Database: 2005-Feb-22
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Barson, F: AUTHOR [+3]

Abstract

An anodic oxidation cleaning process is employed to remove a high and variable contact resistance to those diffused regions produced by doped oxide diffusion. Standard silicon dioxide and silicon etches do not remove the cause of the poor contact resistance.

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Contact Hole Cleaning Process

An anodic oxidation cleaning process is employed to remove a high and variable contact resistance to those diffused regions produced by doped oxide diffusion. Standard silicon dioxide and silicon etches do not remove the cause of the poor contact resistance.

In an illustrative example, 200 angstroms of anodic oxide is grown in contact holes by placing the silicon oxide coated wafer in a solution of methyl acetamide (1100 millimeters), plus potassium nitrate (1 gram) and distilled water with a ratio of the water to the other materials of 1 to 40 millimeters, respectively. Fifty volts DC is placed across the anode of the anodic oxidation apparatus and the wafer is connected to the positive potential. The anodic oxidation is completed in approximately 7 minutes and about 80 angstroms of silicon is removed from the contact area. The oxidation is done at room temperature and, therefore, no change occurs in the diffusion profile. The effect on diffused layer sheet resistance is small, since the porous anodic oxide etches quite fast. The change in contact resistance for 0.1 x 1-1/2 mil contact area of emitter or base is reduced from delta v = 220 millivolts to delta v = 120 millivolts at a current level of 0.5 ma to 10 ma.

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