Optics: measuring and testing – By configuration comparison – With comparison to master – desired shape – or reference voltage
Patent
1996-10-15
2000-05-23
Font, Frank G.
Optics: measuring and testing
By configuration comparison
With comparison to master, desired shape, or reference voltage
356388, 250272, G01N 1100
Patent
active
060671637
ABSTRACT:
The invention provides a process for evaluating a substrate, such as a wafer of semiconductive material having a semiconductor die at least partially formed thereon, as to the condition of an overlying film, such as an overlying film of photoresist that is applied to the semiconductor die prior to metal etching and ion implantation. The condition of the film is evaluated by exposing at least a portion of the substrate to electromagnetic radiation and evaluating the wave profile of the reflected beam.
In instances where it is desirable to evaluate the substrate for the presence or absence or photoresist, ultraviolet, or near ultraviolet light having a wavelength of about 240-650 nm can be used, as such wavelengths are strongly absorbed by photoresist. In contrast, areas of the substrate that are not covered by photoresist will not significantly absorb ultraviolet or near ultraviolet radiation. The presence or absence of the film under study can be evaluated by detecting reflected light from the substrate and comparing the detected light to a known profile. When photoresist films are under evaluation, the profile will feature portions of relatively low amplitude, which correspond to absorption of uv due to the presence of photoresist, and portions of relatively high amplitude, which correspond to non-absorption (reflectance) of uv. While the principles of the invention are applicable to single-point testing of a substrate, it is preferable to undertake a multi-point, and more preferably a continuous scan, of at least a portion of the substrate to minimize the occurrence of possibly erroneous results, as could occur from sampling a portion of the substrate that was deliberately not patterned with the film under study.
REFERENCES:
patent: 4656358 (1987-04-01), Divens et al.
patent: 4795260 (1989-01-01), Schuur et al.
patent: 5124927 (1992-06-01), Hopewell et al.
patent: 5260154 (1993-11-01), Forrest
patent: 5386430 (1995-01-01), Yamagishi et al.
Guldi Richard L.
Paradis Douglas E.
Font Frank G.
Holland Robby T.
Punnoose Roy M.
Telecky Jr. Frederick J.
Texas Instruments Incorporated
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