Method for measuring and analyzing surface roughness on semiconductor laser etched facets
AssigneeThe United States of America as represented by the Secretary of the Air Force
InventorRobert W. Herrick
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Abstract
A scanning electron microscope is used to scan the etched facet edge to produce digital data representative of its profile. A Fourier transform of the edge profile is produced and the resulting plurality of spatial frequency components can be used to generate a first low frequency waveform component indicative of lack of precise edge definition, a midrange frequency component indicative of poor liftoff samples, and a high frequency component indicative of metal grain size. A tilt adjustment feature of the electron microscope is optionally used to advantageously magnify the shape of the profile in the y direction.
Claims3
Method of measuring surface characteristics of a semiconductor facet having a surface profile comprising the steps of:
- (a) digitizing data representative of said surface profile to produce digitized data;
- (b) taking the Fourier transform of said digitized data;
- (c) taking the inverse Fourier transform of spatial frequency spectrum components resulting from the execution of step (b) and reconstructing three waveform components therefrom wherein:
- (d) a first waveform component has a 10-30 micron period for measuring the extent of edge wander, a second waveform component has a 2-5 micron period for measuring the extent of bumpiness and a third waveform component has periods of less than two microns for measuring the extent of surface roughness.
Dependencies are inferred from the claim text.