Method and apparatus for real-time determination of spherical and non-spherical curvature of a surface

摘要

The present invention provides for an apparatus for measuring a curvature of a surface of a wafer in a multi-wafer epitaxial reactor.

主权项

1. Apparatus for measurement of a curvature of a surface of a wafer in a multi-wafer epitaxial reactor, comprising:
means adapted for irradiating a first light beam and a second light beam onto a surface of a sample, wherein the first light beam and the second light beam are parallel to each other; a detector comprising at least one detector plane and being adapted to detect a first position of a reflected first light beam in the at least one detector plane and a first position of a reflected second light beam in the at least one detector plane at a first sampling time and to detect a second position of a reflected first light beam in the at least one detector plane and a second position of a reflected second light beam in the at least one detector plane at a second sampling time; means adapted to synchronize the detector sampling time with the sample main rotation (ωmain); means adapted to determine:
a first distance between the first position of the reflected first light beam and the first position of the reflected second light beam measured at the first sampling time;a second distance between the second position of the reflected first light beam and the second position of the reflected second light beam measured at the second sampling time;a third distance between the first position of the reflected first light beam measured at the first sampling time and the second position of the reflected first light beam measured at the second sampling time; anda fourth distance between the first position of the reflected second light beam measured at the first sampling time and the second position of the reflected second light beam measured at the second sampling time; means adapted to determine a mean spherical curvature (Csph) of the surface and an azimuthal aspherical curvature deviation (ΔCasph) from the first to fourth distances.