1. A sensing method comprising:
providing at least one carbon nanotube;
biasing the at least one carbon nanotube;
exposing the at least one carbon nanotube to an environment where gas is adapted to be detected, whereby, in presence of the gas, heat is removed by the gas from the at least one carbon nanotube;
varying pressure inside the environment with the gas, whereby temperature of the at least one carbon nanotube changes with variation of pressure; and
detecting variation in temperature of the at least one carbon nanotube as an electrical response.
2. The method of claim 1, wherein the method is a gas sensing method.
3. The method of claim 1, wherein the method is a chemical species sensing method to differentiate chemical species.
4. The method of claim 1, wherein each one of the at least one carbon nanotube is a single-walled carbon nanotube.
5. The method of claim 1, wherein biasing the at least one carbon nanotube occurs by connecting electrodes at end regions of the at least one carbon nanotube.
6. The method of claim 5, wherein the at least one carbon nanotube and the electrodes are suspended and devoid of a substrate.
7. The method of claim 6, wherein suspension occurs through critical point drying.
8. The method of claim 5, wherein the electrodes comprise metals selected from the group consisting of Al, Ti, Nb, Mo, Pd, Pt, Sc, Ta, W, Hf, Zr, Au, Cr and combinations thereof.
9. The method of claim 5, wherein the electrodes comprise metals selected from the group consisting of Au, Cr and combinations thereof.
10. The method of claim 6, wherein the electrodes comprise electrodes made of Cr.
11. The method of claim 1, wherein varying the pressure inside the environment with the gas comprises varying the pressure from a substantially ambient pressure to a substantially vacuum pressure.
12. The method of claim 1, wherein the variation in the temperature of the at least one carbon nanotube causes a resistance change in the at least one carbon nanotube, the resistance change being detected as a current response.
13. The method of claim 1, wherein the environment is a chamber containing the gas and the carbon nanotube.
14. The method of claim 1, wherein the at least one carbon nanotube is an array of carbon nanotubes.
15. The method of claim 1, wherein the at least one carbon nanotube is a bundle of carbon nanotubes.
16. The method of claim 1, wherein the at least one carbon nanotube is voltage biased and the electrical response is a current response.
17. The method of claim 1, wherein the electrical response is a voltage response.
18. A method of sensing comprising:
i) exposing a sensor to an environment where gas is adapted to be detected, the sensor comprising
two terminals;
a biasing source to the terminals;
a single-walled carbon nanotube in electrical communication between the terminals;
a calibration of measured electrical conductance of the single-walled carbon nanotube to magnitudes of vacuum about the single-walled carbon nanotube;
a current meter in electrical communication with the source of constant voltage, wherein, in presence of the gas, heat is removed by the gas from the sensor; and
ii) detecting variation in temperature of the single-walled carbon nanotube as an electrical response.
19. The method of claim 18, wherein the method is a method of sensing gas.
20. The method of claim 18, wherein the method is a method of sensing a chemical species to differentiate chemical species.
21. The method of claim 18, wherein the sensor further comprises a substrate supporting the two terminals, the single-walled carbon nanotube being displaced from the substrate between the terminals.
22. The method of claim 18, wherein the electrical response is a current response or a voltage response.
23. The method of claim 18, wherein the biasing source is a source of constant voltage.
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 article comprising:
a wafer having a surface;
a layer of photoresist material over the wafer surface;
a top coat on the photoresist layer operative to substantially cancel a reflected portion of radiation having a wavelength .
2. The article of claim 1, wherein the top coat has a thickness approximately equal to
2
4
n
1
–
(
NA
n
)
2
,
where n is
the refractive index of the top coat and NA is a numerical aperture of an optical system.
3. The article of claim 2, wherein the NA is greater than about 0.7.
4. The article of claim 1, wherein the top coat comprises a substantially low absorption, low refractive index material.
5. The article of claim 4, wherein the top coat comprises a material having a refractive index of about 1.5 or less.
6. The article of claim 4, wherein the top coat has a thickness of about 500 or less.
7. The article of claim 1, wherein the top coat is operative to couple radiation into the photoresist material such that the magnitude of the Transverse Electric (TE) polarization mode of the radiation is substantially equal to the Transverse Magnetic (TM) polarization mode of the radiation over the range of NA from 0 to 1.
8. The article of claim 1, wherein the top coat is operative to couple radiation into the photoresist material such that the magnitude of the Transverse Electric (TE) polarization mode of the radiation is substantially equal to the Transverse Magnetic (TM) polarization mode of the radiation at an NA of about 0.80 and higher.
9. The article of claim 1, wherein the top coat is operative to couple greater than about 75% of a Transverse Electric (TE) polarization mode of an incident radiation at an NA of about 0.93.
10. The article of claim 1, wherein the top coat is operative to couple greater than about 90% of a Transverse Electric (TE) polarization mode of an incident radiation at an NA of about 0.93.
11. An article comprising:
a wafer having a surface;
a layer of photoresist material over the wafer surface;
a bottom anti-reflective coating (BARC) between the wafer and the layer of photoresist material; and
a top coat on the photoresist layer operative to substantially cancel a reflected portion of radiation having a wavelength .
12. The article of claim 11, wherein the top coat has a thickness approximately equal to
3
4
n
1
–
(
NA
n
)
2
,
wherein n
is a refractive index of the top coat and NA is a numerical aperture of an optical system.
13. The article of claim 12, wherein the NA is greater than about 0.7.
14. The article of claim 11, wherein the top coat comprises a substantially low absorption, low refractive index material.
15. The article of claim 14, wherein the top coat comprises a material having a refractive index of about 1.5 or less.
16. The article of claim 15, wherein the top coat has a thickness of about 500 or less.
17. The article of claim 11, wherein the top coat is operative to couple radiation into the photoresist material such that the magnitude of the Transverse Electric (TE) polarization mode of the radiation is substantially equal to the Transverse Magnetic (TM) polarization mode of the radiation over the range of NA from 0 to 1.
18. The article of claim 11, wherein the top coat is operative to couple radiation into the photoresist material such that the magnitude of the Transverse Electric (TE) polarization mode of the radiation is substantially equal to the Transverse Magnetic (TM) polarization mode of the radiation at an NA of about 0.8 and higher.
19. The article of claim 11, wherein the top coat is operative to couple greater than about 65% of a Transverse Electric (TE) polarization mode of an incident radiation at an NA of about 0.93.
20. The article of claim 11, wherein the top coat is operative to couple greater than about 90% of a Transverse Electric (TE) polarization mode of an incident radiation at an NA of about 0.93.
21. A method comprising:
depositing a top coat on a layer of photoresist material over a substrate;
exposing the top coat to light in a lithography system having a numerical aperture (NA) of about 0.8 or higher, said light including a Transverse Electric (TE) polarization mode energy; and
coupling greater than about 80% of the TE polarization mode energy into the photoresist material.
22. The method of claim 21, further comprising:
depositing a bottom anti-reflective coating (BARC) on the substrate; and
depositing the layer of photoresist material on the BARC.
23. The method of claim 21, wherein said exposing comprises exposing the top coat to light in a lithography system having a numerical aperture (NA) of about 0.9 or higher.
24. The method of claim 21, wherein said depositing comprises depositing the top coat at a thickness approximately equal to
4
4
n
1
–
(
NA
n
)
2
.
25. The method of claim 24, wherein the thickness is deposited to a thickness of about 500 or less.
26. The method of claim 21, wherein said depositing comprises depositing a substantially low absorption, low refractive index material.
27. The method of claim 26, wherein the material has a refractive index of about 1.5 or less.