1. A computer-implemented method for determining stresses at a location on a layered structure comprising at least one film formed on a substrate, comprising:
applying a spatially varying structural condition in the layered structure to computation of stresses at a selected location in the layered structure from curvatures at all locations of the layered structure, wherein the spatially varying structural condition in the layered structure comprises at least one of (1) the film covers only a portion of the substrate, (2) the film has a film thickness that varies from one location to another across the film, and (3) the substrate has a substrate thickness that varies from one location to another;
determining in the computation under the spatially varying structural condition a local contribution to stresses at the selected location on the layered structure from curvature changes at the selected location;
determining a non-local contribution to the stresses at the selected location from curvature changes at all locations of the layered structure; and
combining the local contribution and the non-local contribution to estimate the total stresses at the selected location.
2. The method as in claim 1, further comprising:
when the film covers only a portion of the substrate, applying a formula in the computation for an equivalent structure, which is identical to the layered structure except for that the film in the equivalent structure fully covers the substrate, to compute the total stresses at the selected location.
3. The method as in claim 2, further comprising:
using a radial gradient of a sum of curvature changes along a radial direction and an orthogonal circumferential direction to represent an interface shear stress between the film and the substrate.
4. The method as in claim 1, further comprising:
applying a formula to compute a difference in stresses along a radial direction and an orthogonal circumferential direction that is independent of a thickness of the film when the film thickness varies from one location to another across the film.
5. The method as in claim 4, further comprising:
using a radial gradient of a sum of curvature changes along the radial direction and the orthogonal circumferential direction to represent an interface shear stress between the film and the substrate.
6. The method as in claim 4, further comprising:
using a sum of (1) a radial gradient of a sum of local curvature changes along the radial direction and the orthogonal circumferential direction and (2) a non-local contribution to represent an interface shear stress between the film and the substrate.
7. The method as in claim 4, further comprising:
using a formula to compute a sum of local curvature changes at a given location along the radial direction and the orthogonal circumferential direction wherein the formula is inversely proportional to a local film thickness at the given location.
8. The method as in claim 1, further comprising:
obtaining a full field spatial curvature measurement of the layered structure; and
using spatial curvature changes from the full field spatial curvature measurement to compute the local contribution and the non-local contribution from distribution.
9. The method as in claim 8, further comprising:
obtaining diagonal curvature tensor components at the selected location from the spatial curvature change distribution;
computing a sum of the diagonal curvature change tensor components and a difference of the diagonal curvature change tensor components, at the selected location;
computing the local contribution to a sum of diagonal stress tensors at the selected location from the sum of the diagonal curvature change tensor components at the selected location;
computing the non-local contribution to the sum of diagonal stress tensors at the selected location and a sum of diagonal stress tensors averaged over all locations across the layered structure; and
computing the local contribution to a difference of diagonal stress tensor components of the layered structure at the selected location from the difference of the diagonal curvature change tensor components at the selected location.
10. A method for monitoring a substrate fabrication process using the computer-implemented method in claim 1, comprising:
while the layered structure is being processed, directing an optical probe to the layered structure to optically obtain a full-field curvature map of the layered structure;
processing the full-field curvature map to obtain curvature information at all locations of the layered structure;
applying the computer-implemented method in claim 1 to determine the total stresses at each location of the layered structure; and
determining whether the layered structure is defective based on an acceptable threshold stress.
11. The method as in claim 10, further comprising using the total stresses of the layered structure to determine whether a film is likely to delaminate from the substrate.
12. The method as in claim 10, further comprising using an optical shearing interferometer to optically obtain the full-field curvature map of the layered structure.
13. The method as in claim 12, wherein the optical shearing interferometer comprises a coherent gradient sensing system with two optical diffraction elements.
14. A device for charactering stresses in a layered structure, comprising:
an optical module to project an optical probe beam to a layered structure and to obtain a full-field curvature map of a surface on the layered structure;
a processor in communication with the optical module to receive data of the full-field curvature map, the processor comprising:
means for applying a spatially varying structural condition in the layered structure to computation of stresses at a selected location in the layered structure from curvatures at all locations of the layered structure, wherein the spatially varying structural condition in the layered structure comprises at least one of (1) the film covers only a portion of the substrate, (2) the film has a film thickness that varies from one location to another across the film, and (3) the substrate has a substrate thickness that varies from one location to another;
means for determining in the computation under the spatially varying structural condition a local contribution to stresses at the selected location on the layered structure from curvature changes at the selected location;
means for determining a non-local contribution to the stresses at the selected location from curvature changes at all locations of the layered structure; and
means for combining the local contribution and the non-local contribution to estimate the total stresses at the selected location.
15. The device as in claim 14, wherein the optical module comprises:
a collimated radiation source to produce the probe beam onto the surface of the layered structure;
an optical shearing interferometer device positioned to receive the optical probe beam reflected from the surface and to cause an optical interference between a reflected wavefront of the optical probe beam and another replica of the reflected wavefront that is spatially shifted by a shearing distance, wherein the optical shearing interferometer is operable to adjust a phase shift between the reflected wavefront and the replica of the reflected wavefront to obtain a plurality of phase-shifted interference patterns of different phase shifts;
an imaging device which captures the interference patterns to produce the full-field curvature map.
16. The device as in claim 15, wherein the optical shearing interferometer comprises a coherent gradient sensing (CGS) system with two diffraction gratings.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. An earplug comprising:
an open inserting end;
an open inlet end opposite to the open inserting end;
a hollow body having
a first annular sidewall close to the open inlet end and having a first cavity encircled by the first annular sidewall; and
a second annular sidewall close to the open inserting end and having a second cavity tapered toward the open inserting end;
a sound-processing unit inserted through the first cavity and engaging the second cavity; and
a soft sheath mounted around the hollow body close to the open inserting end and having
a bottom close to the open inserting end;
a third annular sidewall formed on the bottom and mounted around the second annular sidewall of the hollow body;
an open end opposite to the bottom; and
a through hole defined through the bottom.
2. The earplug as claimed in claim 1, wherein the hollow body has an annular flange formed around an outer surface of the hollow body and abutting the open end of the soft sheath; and
a fourth annular sidewall formed on an outer edge of the annular flange and extending toward the open inserting end to cover the open end of the soft sheath.
3. The earplug as claimed in claim 1 further comprising a cover closing the open inlet end of the hollow body and having
at least one passage defined through the cover and allowing the first cavity to communicate with ambient air.
4. The earplug as claimed in claim 3, wherein:
an annular groove is defined in an inner surface of the first annular sidewall;
the cover has
a cap having at least one passage defined through the cap;
a short annular sidewall is formed on the cap and extends toward the first cavity and has
an outer surface hermetically contacting an inner surface of first annular sidewall; and
an annular rib formed on the outer surface of the short annular sidewall and engaging the annular groove of the first annular sidewall to strengthen the combination of the cover and the hollow body.
5. The earplug as claimed in claim 1 further comprising a tube mounted securely through the through hole in the soft sheath and allowing the second cavity to communicate with the open inserting end.
6. The earplug as claimed in claim 5 further comprising:
an inner flange formed on a bottom edge of the hollow body inside the second cavity and extending inward;
a hollow cylinder, mounted inside the second cavity, abutting the inner flange, located close to the through hole in the soft sheath and opposite to the open inserting end and allowing an extension section of the tube to engage a through hole in the hollow cylinder; and
an annular blocking rib formed on the outer surface of the extension section of the tube and hermetically abutting a top outer edge of the through hole in the soft sheath.
7. The earplug as claimed in claim 1, wherein the soft sheath is made of medical resilient material.
8. The earplug as claimed in claim 1, wherein the sound-processing unit is a noise-reducing valve.
9. The earplug as claimed in claim 1, wherein the sound-processing unit is an electronic signal receiver for receiving radio signals.
10. A hearing protection apparatus with earplugs comprising:
two earplugs and each earplug having
an open inserting end;
an open inlet end opposite to the open inserting end;
a hollow body having
a first annular sidewall close to the open inlet end and having a first cavity encircled by the first annular sidewall; and
a second annular sidewall close to the open inserting end and having a second cavity tapered toward the open inserting end;
a sound-processing unit inserted through the first cavity and engaging the second cavity, wherein the sound-processing unit is a noise-reducing valve;
a cover closing the open inlet end of the hollow body and having
at least one passage defined through the cover and allowing the first cavity to communicate with ambient air;
a soft sheath mounted around the hollow body close to the open inserting end and having
a bottom close to the open inserting end;
a third annular sidewall formed on the bottom and mounted around the second sidewall of the hollow body;
an open end opposite to the bottom; and
a through hole defined through the bottom;
a hollow cylinder mounted inside the second cavity close to a bottom edge of the hollow body and having a through hole; and
a tube mounted securely through the through hole in the soft sheath into the through hole in the hollow cylinder and allowing the second cavity to communicate with the open inserting end; and
an attachment connected between the earplugs.
11. The hearing protection apparatus with earplugs as claimed in claim 10, wherein
the number of the passages is two, and the passages are defined through the cover, communicate with and are opposite to each other; and
the attachment has
a cord having two ends extending through the passages respectively in the covers; and
two clamps respectively binding the ends to the cord itself.
12. The hearing protection apparatus with earplugs as claimed in claim 10, wherein the attachment is a U-shaped headband having two ends integrally formed respectively on the covers.
13. An audio earphone apparatus with earplugs electrically connected to an audio device and comprising:
two earplugs, and each earplug having
an open inserting end;
an open inlet end opposite to the open inserting end;
a hollow body having
a first annular sidewall close to the open inlet end and having a first cavity encircled by the first annular sidewall; and
a second annular sidewall close to the open inserting end and having a second cavity tapered toward the open inserting end;
a sound-processing unit inserted through the first cavity and engaging the second cavity, wherein the sound-processing unit is an electronic signal receiver;
a cover closing the open inlet end of the hollow body and having
at least one passage defined through the cover and allowing the first cavity to communicate with ambient air;
a soft sheath mounted around the hollow body close to the open inserting end and having
a bottom close to the open inserting end;
a third annular sidewall formed on the bottom and mounted around the second sidewall of the hollow body;
an open end opposite to the bottom; and
a through hole defined through the bottom;
a hollow cylinder mounted inside the second cavity, abutting the inner flange and having a through hole; and
a tube mounted securely through the through hole in the soft sheath into the through hole in the hollow cylinder and allowing the second cavity to communicate with the open inserting end; and
an attachment connected between the earplugs.