Radiant energy – Photocells; circuits and apparatus – With circuit for evaluating a web – strand – strip – or sheet
Reexamination Certificate
2000-09-29
2002-12-03
Le, Que T. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
With circuit for evaluating a web, strand, strip, or sheet
C250S559300, C356S237400
Reexamination Certificate
active
06489627
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to reticles employed when fabricating microelectronic fabrications. More particularly, the present invention relates to methods and apparatus for inspecting reticles employed when fabricating microelectronic fabrications.
2. Description of the Related Art
Microelectronic fabrications are formed from microelectronic substrates over which are formed patterned microelectronic conductor layers which are separated by microelectronic dielectric layers.
As microelectronic fabrication integration levels have increased and microelectronic device and patterned microelectronic conductor layer dimensions have decreased, it has become increasingly important when fabricating microelectronic fabrications to assure optimal registration of various overlying microelectronic layers which may be employed when fabricating a microelectronic fabrication.
While assuring optimal registration of various overlying microelectronic layers which may be employed when fabricating a microelectronic fabrication is thus clearly of significance and importance when fabricating a microelectronic fabrication, assuring optimal registration of various overlying microelectronic layers which may be employed when fabricating a microelectronic fabrication is nonetheless not entirely without problems in the art of microelectronic fabrication. In that regard, it is often recognized in the art of microelectronic fabrication that optimal registration of various overlying layers which may be employed when fabricating a microelectronic fabrication may be influenced by multiple interrelated and obscure factors derived from interactions between a photoexposure reticle and a photoexposure apparatus.
It is thus in general towards the goal of providing optimal registration of various overlying layers which may be employed when fabricating a microelectronic fabrication that the present invention is generally directed. Similarly, it is thus more particularly towards the goal of providing an efficient method for inspecting a reticle such as to provide optimal registration of an overlying layer which may be employed when fabricating a microelectronic fabrication while employing the reticle that the present invention is more specifically directed.
Various methods and apparatus have been disclosed in the art of microelectronic fabrication for inspecting reticles employed within the art of microelectronic fabrication.
For example, Noguchi et al., in U.S. Pat. No. 5,098,191, discloses a method for inspecting a reticle and a related apparatus for inspecting the reticle, wherein only foreign substances and defects which actually produce damage when employing the reticle incident to forming a microelectronic layer for use within a microelectronic fabrication are detected. To realize the foregoing object, the method for inspecting the reticle and the apparatus for inspecting the reticle employ a comparison of an inspected reticle in conjunction with a standard reticle with respect to reflected illuminating inspection light characteristics and transmitted illuminating inspection light characteristics.
In addition, Emery et al., in U.S. Pat. No. 5,737,072, discloses a method for inspecting a reticle and a apparatus for inspecting the reticle, wherein the method for inspecting the reticle and the apparatus for inspecting the reticle need not employ a standard reticle for comparison purposes when inspecting the reticle while employing the method for inspecting the reticle and the apparatus for inspecting the reticle. To realize the foregoing result, defect detection within the reticle is determined while employing the method for inspecting the reticle and the apparatus for inspecting the reticle by comparing combinations of at least two inspection light transmission signals or light reflection signals which are measured or derived while employing the method for inspecting the reticle and the apparatus for inspecting the reticle.
Desirable in the art of microelectronic fabrication are additional methods and apparatus which may be employed for inspecting reticles employed for fabricating microelectronic fabrications, particularly as regards inspecting reticles such as to assure optimal registration of overlying layers within microelectronic fabrications which are fabricated while employing the reticles.
It is towards the foregoing object that the present invention is directed.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a method for inspecting a reticle and an apparatus for inspecting the reticle.
A second object of the present invention is to provide the method for inspecting the reticle and the apparatus for inspecting the reticle in accord with the first object of the present invention, wherein the method for inspecting the reticle and the apparatus for inspecting the reticle provide for optimal registration of an overlying layer within a microelectronic fabrication fabricated employing the reticle.
A third object of the present invention is to provide the method for inspecting the reticle and the apparatus for inspecting the reticle in accord with the first object of the invention and the second object of the invention, which method and apparatus are readily commercially implemented.
In accord with the objects of the present invention, there is provided by the present invention a method for inspecting a reticle and an apparatus for inspecting the reticle. To practice the method for inspecting the reticle, there is first provided a reticle comprising a transparent substrate having formed thereupon a patterned non-transparent layer which defines an alignment mark. There is then impinged at a non-orthogonal angle through the alignment mark within the reticle an inspection light beam which is both: (a) refracted and transmitted directly through the reticle; and (b) refracted, reflected and then transmitted through the reticle, to thus provide a multiplicity of refracted transmitted inspection light beams. There is then passed the multiplicity of refracted transmitted inspection light beams through a pair of wedges whose inclined surfaces are counter-opposed and separated by a gap to form a multiplicity of additionally refracted transmitted inspection light beams. Finally, there is then varied a distance of the gap to optimize an optical characteristic of the additionally refracted transmitted inspection light beams.
Optionally, the method for inspecting the reticle may also further comprise correlating a variation of the distance of the gap to a variation of the non-orthogonal angle to provide a varied non-orthogonal angle which alternatively optimizes an optical characteristic of the additionally refracted transmitted inspection light beams.
The method for inspecting the reticle in accord with the present invention contemplates an apparatus for inspecting the reticle in accord with the present invention.
In addition, the method for inspecting the reticle in accord with the present invention also contemplates a method for aligning the reticle within a photoexposure apparatus in accord with the present invention.
The present invention provides a method for inspecting a reticle and an apparatus for inspecting the reticle, wherein the method for inspecting the reticle and the apparatus for inspecting the reticle provide for optimal registration of an overlying layer within a microelectronic fabrication fabricated employing the reticle. The method for inspecting the reticle and the apparatus for inspecting the reticle in accord with the present invention realize the foregoing object by employing with respect to a multiplicity of refracted transmitted inspection light beams derived from an inspection light beam incident non-orthogonal to a reticle at the location of an alignment mark within the reticle a pair of transparent wedges whose inclined surfaces are counter-opposed and separated by a gap a distance of which is varied to optimize an optical characteristic of a series of additionally refracted transmitted inspection lig
Guo Joseph
Lin Cheng-Hsun
Sheng Parson
Le Que T.
Taiwan Semiconductor Manufacturing Co. Ltd
Tung & Associates
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