System for trimming microelectronic resistors

Abstract

A system for trimming the ohmic value of a resistor included in a microelectronic chip to raise or lower its resistance without changing its physical dimensions. The system is provided with a self-contained unit which generates a low radio-frequency carrier overmodulated by a sonic frequency signal to yield at its output terminal pulsed radio-frequency energy. Coupled by an extension cable to the output terminal of the unit is a portable probe assembly whose position may be manipulated to bring the assembly into operative relation with the resistor to be trimmed. The assembly includes a tank circuit connected by the cable to the output terminal of the unit and tuned to the carrier frequency so that the pulsed energy is stored therein and not radiated. A "Down" probe is inductively coupled in step-up relation to the tank circuit to cause a corona discharge beam to be projected from the tip of this probe, which beam when directed toward a point on the resistor acts to reduce its ohmic value. An "Up" probe is inductively coupled in step-down relation to the tank circuit so that when this probe is brought into contact with a point on the resistor, the resultant current acts to increase its ohmic value.

Dependencies are inferred from the claim text.