US 5,698,474 A · High speed diamond-based machining of silicon semiconductor die in wafer and packaged form for backside emission microscope detection

Abstract

Emission microscopy testing of semiconductor integrated circuits is accomplished from the back side of a packaged die or a wafer but selectively milling the back surface using high speed (e.g., 40,000-60,000 rpm) milling tool having a 150 grit 0.125 inch diameter laterally translated at 3 inches per minute and taking cuts up to approximately 0.00025 inch (6 microns). In milling a packaged die, a trench is first milled in the molding material holding the die in the package and surrounding the die so that the tool can momentarily pause to switch directions off the die face. The die or wafer can be thinned to less than 200 microns for the emission microscopy testing.

Claims16

Dependent claims

A method of machining a back surface of a semiconductor chip to permit backside emission microscopy of an integrated circuit in a front surface of the chip, said chip affixed by molding material in a package, comprising the steps of

a) mounting said package in a milling machine which permits movement of the package along three axes,
b) milling molding material of said package using a rotary tool operated at a first rotary speed thereby removing molding material over the back surface and forming a trench in the molding material around the semiconductor chip, and
c) milling semiconductor material from the back surface of the semiconductor chip using a rotary tool operating at a second rotary speed on the order of 60,000 rpm or greater.

Dependencies are inferred from the claim text.

High speed diamond-based machining of silicon semiconductor die in wafer and packaged form for backside emission microscope detection

Life of this patent

High speed diamond-based machining of silicon semiconductor die in wafer and packaged form for backside emission microscope detection

Life of this patent

Abstract

Claims16