초록 ▼

A particle detection on a periodic patterned surface is achieved in a method and apparatus using a single light beam scanning at a shallow angle over the surface. The surface contains a plurality of identical die with streets between die. The beam scans parallel to a street direction, while a light

A particle detection on a periodic patterned surface is achieved in a method and apparatus using a single light beam scanning at a shallow angle over the surface. The surface contains a plurality of identical die with streets between die. The beam scans parallel to a street direction, while a light collection system collects light scattered from the surface with a constant solid angle. The position of the collection system as well as the polarization of the light beam and collected scattered light may be arranged to maximize the particle signal compared to the pattern signal. A detector produces an electrical signal corresponding to the intensity of scattered light that is colelcted. A processor constructs templates from the electrical signal corresponding to individual die and compares the templates to identify particles. A reference template is constantly updated so that comparisons are between adjacent die. In one embodiment, the templates are made up of registered positions where the signal crosses a threshold, and the comparison is between corresponding positions to eliminate periodic pattern features, leaving only positions representing particles.

대표청구항 ▼

A method of particle detection on a patterned surface comprising, (a) scanning a substantially flat surface with a single laser beam, said beam scanning said surface in a sequence of paths, (b) collecting approximately constant solid angles of acceptance of light scattered from a plurality of points

A method of particle detection on a patterned surface comprising, (a) scanning a substantially flat surface with a single laser beam, said beam scanning said surface in a sequence of paths, (b) collecting approximately constant solid angles of acceptance of light scattered from a plurality of points on said surface with an optical collection system, (c) detecting said collected light and producing an electrical signal corresponding to the intensity of light collected, (d) producing electrical waveform templates from said electrical signal, said surface having a periodic pattern representing a plurality of die formed thereon, each of said waveform templates representing a portion of a scan path corresponding to one of said die, one of said waveform templates corresponding to a die being designated as a reference waveform template, (e) comparing the waveform template corresponding to another die with said reference waveform template, differences between the waveform templates representing particles on the surface in said scan path, and (f) repeating steps (a)-(e) until at least a predetermined number of said die have been scanned.