US 6,887,126 B2 · Wafer thickness control during backside grind

Abstract

A method and apparatus for controlling the thickness of a semiconductor wafer during a backside grinding process are disclosed. The present invention uses optical measurement of the wafer thickness during a backside grinding process to determine the endpoint of the grinding process. Preferred methods entail measuring light transmitted through or reflected by a semiconductor wafer as a function of angle of incidence or of wavelength. This information is then used, through the use of curve fitting techniques or formulas, to determine the thickness of the semiconductor wafer. Furthermore, the present invention may be used to determine if wedging of the semiconductor occurs and, if wedging does occur, to provide leveling information to the thinning apparatus such that a grinding surface can be adjusted to reduce or eliminate wedging.

Claims14

Dependent claims

An apparatus for thinning a semiconductor wafer, comprising:

a system for removing a portion of a backside of the semiconductor wafer;
an optical system for measuring a thickness of the semiconductor wafer, wherein the optical system comprises a multi-wavelength light source positioned to illuminate a surface of the semiconductor wafer, a splitter, a movable mirror, and a non-segmented detector, the splitter positioned to allow a beam of light to be split to illuminate the movable mirror and the non-segmented detector;
and
a control system for halting the system for removing when the measured thickness of the semiconductor wafer reaches a predetermined thickness.

1 more element

Dependencies are inferred from the claim text.

Wafer thickness control during backside grind

Life of this patent

Wafer thickness control during backside grind

Life of this patent

Abstract

Claims14