Abstract

Scattered total internal reflection of visible light is used to measure linear nanometric distance to as small as 10 nm. Specifically, we measure the height of magnetic transducer heads above a rotating glass disk. A breakthrough in the approach to calibration, based on combining the second derivative of the transmittance of the scattered light and parameter fitting, substantially improves the quality of the measurement relative to previous demonstrations of this method. The results agree to 1 nm with an industry-standard three-color interferometer to and including the lowest values measured. The technique in principle remains robust to as low as the zero height. Furthermore the calibration point can be as low as 10 nm, which is especially attractive in practice.

© 2004 Optical Society of America

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References

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    [CrossRef]
  3. Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
    [CrossRef]
  4. C. Lacey , “ Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings ,” U.S. patent5,280,340 (18January1994).
  5. C. Lacey, E. W. Russ , “Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings,” U.S. patent5,457,534 (10October1995).
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    [CrossRef]
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    [CrossRef] [PubMed]
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    [CrossRef]
  11. X. Liu, W. Clegg, B. Liu, “Normal-incidence polarization interferometry for measuring flying height of magnetic heads,” IEEE Trans. Magn. 35, 2457–2459 (1999).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef]
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    [CrossRef] [PubMed]
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  23. C. W. Strunk, C. C. Zahn, P. J. Sides, “Comparison of the phase metrics DFHT IV and Zygo Pegasus 2000 FH testers,” Appl. Opt. 40, 4507–4513 (2001).
    [CrossRef]
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    [CrossRef]
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    [CrossRef]

2001 (3)

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

C. W. Strunk, C. C. Zahn, P. J. Sides, “Comparison of the phase metrics DFHT IV and Zygo Pegasus 2000 FH testers,” Appl. Opt. 40, 4507–4513 (2001).
[CrossRef]

2000 (2)

X. Liu, W. Clegg, B. Liu, C. Chow, “Improved intensity interferometry method for measuring head-disk spacing down to contact,” IEEE Trans. Magn. 36, 2674–2676 (2000).
[CrossRef]

C. W. Strunk, J. L. Lo, P. J. Sides, “Calibration of fly height measured by scattered total internal reflection,” IEEE Trans. Magn. 36, 2727–2729 (2000).
[CrossRef]

1999 (2)

X. Liu, W. Clegg, B. Liu, “Normal-incidence polarization interferometry for measuring flying height of magnetic heads,” IEEE Trans. Magn. 35, 2457–2459 (1999).
[CrossRef]

D. C. Prieve, “Measurement of colloidal forces with TIRM,” Adv. Colloid Interface Sci. 82, 93–125 (1999).
[CrossRef]

1998 (2)

1997 (1)

J. L. Lo, P. J. Sides, “Measurement of fly height by scattered total internal reflection,” J. Appl. Phys. 81, 5381–5383 (1997).
[CrossRef]

1996 (4)

E. Hotaling, “Measuring flying height in an era of near-contact recording,” Data Storage 3, 41–46 (1996).

P. J. Sides, J. L. Lo, “Measurement of linear nanometric distances between smooth plane parallel bodies by scattered total internal reflection,” Appl. Phys. Lett. 69, 141–142 (1996).
[CrossRef]

Y. Li, A. Menon, “Flying height measurement metrology for ultralow spacing in rigid magnetic recording,” IEEE Trans. Magn. 32, 129–134 (1996).
[CrossRef]

P. de Groot, L. Deck, J. Soobitsky, J. Biegen, “Polarization interferometer for measuring the flying height of magnetic read-write heads,” Opt. Lett. 21, 441–443 (1996).
[CrossRef] [PubMed]

1995 (1)

J. J. Wallace, J. R. Pavlat, “Flying height testing at near contact,” Data Storage 9, 55–58 (1995).

1993 (1)

1979 (1)

1964 (1)

Azzam, R. M. A.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light (Elsevier, Amsterdam, 1987), pp. 269–363.

Bashara, N. M.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light (Elsevier, Amsterdam, 1987), pp. 269–363.

Bhushan, B.

B. Bhushan, Tribology and Mechanics of Magnetic Storage Devices, 2nd ed. (Springer-Verlag, New York, 1996).
[CrossRef]

Biegen, J.

Chen, Q.

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

Chew, H.

Chon, C.

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

Chow, C.

X. Liu, W. Clegg, B. Liu, C. Chow, “Improved intensity interferometry method for measuring head-disk spacing down to contact,” IEEE Trans. Magn. 36, 2674–2676 (2000).
[CrossRef]

Clegg, W.

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

X. Liu, W. Clegg, B. Liu, C. Chow, “Improved intensity interferometry method for measuring head-disk spacing down to contact,” IEEE Trans. Magn. 36, 2674–2676 (2000).
[CrossRef]

X. Liu, W. Clegg, B. Liu, “Normal-incidence polarization interferometry for measuring flying height of magnetic heads,” IEEE Trans. Magn. 35, 2457–2459 (1999).
[CrossRef]

Court, I.

de Groot, P.

Deck, L.

Groot, P. de

P. de Groot, “Optical gap measuring apparatus and method,” U.S. patent5,557,399 (17September1996.

Hansen, W. N.

W. N. Hansen, “Internal reflection spectroscopy in electrochemistry,” in Advances in Electrochemistry and Electrochemical Engineering (Wiley, New York, 1973), pp. 1–226.

Hotaling, E.

E. Hotaling, “Measuring flying height in an era of near-contact recording,” Data Storage 3, 41–46 (1996).

Hu, S.

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

Jenkins, D.

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

Kerker, M.

Lacey, C.

C. Lacey , “ Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings ,” U.S. patent5,280,340 (18January1994).

C. Lacey, E. W. Russ , “Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings,” U.S. patent5,457,534 (10October1995).

Leng, Q.

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

Li, A.

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

Li, Y.

Y. Li, A. Menon, “Flying height measurement metrology for ultralow spacing in rigid magnetic recording,” IEEE Trans. Magn. 32, 129–134 (1996).
[CrossRef]

Liu, B.

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

X. Liu, W. Clegg, B. Liu, C. Chow, “Improved intensity interferometry method for measuring head-disk spacing down to contact,” IEEE Trans. Magn. 36, 2674–2676 (2000).
[CrossRef]

X. Liu, W. Clegg, B. Liu, “Normal-incidence polarization interferometry for measuring flying height of magnetic heads,” IEEE Trans. Magn. 35, 2457–2459 (1999).
[CrossRef]

Liu, X.

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

X. Liu, W. Clegg, B. Liu, C. Chow, “Improved intensity interferometry method for measuring head-disk spacing down to contact,” IEEE Trans. Magn. 36, 2674–2676 (2000).
[CrossRef]

X. Liu, W. Clegg, B. Liu, “Normal-incidence polarization interferometry for measuring flying height of magnetic heads,” IEEE Trans. Magn. 35, 2457–2459 (1999).
[CrossRef]

Lo, J. L.

C. W. Strunk, J. L. Lo, P. J. Sides, “Calibration of fly height measured by scattered total internal reflection,” IEEE Trans. Magn. 36, 2727–2729 (2000).
[CrossRef]

J. L. Lo, P. J. Sides, “Measurement of fly height by scattered total internal reflection,” J. Appl. Phys. 81, 5381–5383 (1997).
[CrossRef]

P. J. Sides, J. L. Lo, “Measurement of linear nanometric distances between smooth plane parallel bodies by scattered total internal reflection,” Appl. Phys. Lett. 69, 141–142 (1996).
[CrossRef]

Menon, A.

Y. Li, A. Menon, “Flying height measurement metrology for ultralow spacing in rigid magnetic recording,” IEEE Trans. Magn. 32, 129–134 (1996).
[CrossRef]

Pavlat, J. R.

J. J. Wallace, J. R. Pavlat, “Flying height testing at near contact,” Data Storage 9, 55–58 (1995).

Prieve, D. C.

Russ, E. W.

C. Lacey, E. W. Russ , “Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings,” U.S. patent5,457,534 (10October1995).

Sides, P. J.

C. W. Strunk, C. C. Zahn, P. J. Sides, “Comparison of the phase metrics DFHT IV and Zygo Pegasus 2000 FH testers,” Appl. Opt. 40, 4507–4513 (2001).
[CrossRef]

C. W. Strunk, J. L. Lo, P. J. Sides, “Calibration of fly height measured by scattered total internal reflection,” IEEE Trans. Magn. 36, 2727–2729 (2000).
[CrossRef]

J. L. Lo, P. J. Sides, “Measurement of fly height by scattered total internal reflection,” J. Appl. Phys. 81, 5381–5383 (1997).
[CrossRef]

P. J. Sides, J. L. Lo, “Measurement of linear nanometric distances between smooth plane parallel bodies by scattered total internal reflection,” Appl. Phys. Lett. 69, 141–142 (1996).
[CrossRef]

P. J. Sides , “Apparatus and method for measuring linear nanometric distances using evanescent radiation,” U.S. patent5,715,060 (3February1998).

Soobitsky, J.

Strunk, C. W.

C. W. Strunk, C. C. Zahn, P. J. Sides, “Comparison of the phase metrics DFHT IV and Zygo Pegasus 2000 FH testers,” Appl. Opt. 40, 4507–4513 (2001).
[CrossRef]

C. W. Strunk, J. L. Lo, P. J. Sides, “Calibration of fly height measured by scattered total internal reflection,” IEEE Trans. Magn. 36, 2727–2729 (2000).
[CrossRef]

von Willisen, F. K.

Wallace, J. J.

J. J. Wallace, J. R. Pavlat, “Flying height testing at near contact,” Data Storage 9, 55–58 (1995).

Walz, J. Y.

Wang, D.-S.

Yuan, Z.-M.

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

Zahn, C. C.

C. W. Strunk, C. C. Zahn, P. J. Sides, “Comparison of the phase metrics DFHT IV and Zygo Pegasus 2000 FH testers,” Appl. Opt. 40, 4507–4513 (2001).
[CrossRef]

Adv. Colloid Interface Sci. (1)

D. C. Prieve, “Measurement of colloidal forces with TIRM,” Adv. Colloid Interface Sci. 82, 93–125 (1999).
[CrossRef]

Appl. Opt. (1)

C. W. Strunk, C. C. Zahn, P. J. Sides, “Comparison of the phase metrics DFHT IV and Zygo Pegasus 2000 FH testers,” Appl. Opt. 40, 4507–4513 (2001).
[CrossRef]

Appl. Opt. (4)

Appl. Phys. Lett. (1)

P. J. Sides, J. L. Lo, “Measurement of linear nanometric distances between smooth plane parallel bodies by scattered total internal reflection,” Appl. Phys. Lett. 69, 141–142 (1996).
[CrossRef]

Data Storage (1)

E. Hotaling, “Measuring flying height in an era of near-contact recording,” Data Storage 3, 41–46 (1996).

Data Storage (1)

J. J. Wallace, J. R. Pavlat, “Flying height testing at near contact,” Data Storage 9, 55–58 (1995).

IEEE Trans. Magn. (2)

W. Clegg, X. Liu, B. Liu, A. Li, C. Chon, D. Jenkins, “Normal-incidence polarization interferometry flying height testing,” IEEE Trans. Magn. 37, 1941–1943 (2001).
[CrossRef]

C. W. Strunk, J. L. Lo, P. J. Sides, “Calibration of fly height measured by scattered total internal reflection,” IEEE Trans. Magn. 36, 2727–2729 (2000).
[CrossRef]

IEEE Trans. Magn. (4)

Y. Li, A. Menon, “Flying height measurement metrology for ultralow spacing in rigid magnetic recording,” IEEE Trans. Magn. 32, 129–134 (1996).
[CrossRef]

X. Liu, W. Clegg, B. Liu, “Normal-incidence polarization interferometry for measuring flying height of magnetic heads,” IEEE Trans. Magn. 35, 2457–2459 (1999).
[CrossRef]

X. Liu, W. Clegg, B. Liu, C. Chow, “Improved intensity interferometry method for measuring head-disk spacing down to contact,” IEEE Trans. Magn. 36, 2674–2676 (2000).
[CrossRef]

Z.-M. Yuan, B. Liu, S. Hu, Q. Leng, Q. Chen, “Scanning carrier current method for in situ measurement of flying height variation,” IEEE Trans. Magn. 37, 1814–1817 (2001).
[CrossRef]

J. Appl. Phys. (1)

J. L. Lo, P. J. Sides, “Measurement of fly height by scattered total internal reflection,” J. Appl. Phys. 81, 5381–5383 (1997).
[CrossRef]

J. Opt. Soc. Am. A (1)

Opt. Lett. (1)

Other (7)

W. N. Hansen, “Internal reflection spectroscopy in electrochemistry,” in Advances in Electrochemistry and Electrochemical Engineering (Wiley, New York, 1973), pp. 1–226.

R. M. A. Azzam, N. M. Bashara, Ellipsometry and Polarized Light (Elsevier, Amsterdam, 1987), pp. 269–363.

P. de Groot, “Optical gap measuring apparatus and method,” U.S. patent5,557,399 (17September1996.

C. Lacey , “ Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings ,” U.S. patent5,280,340 (18January1994).

C. Lacey, E. W. Russ , “Method and apparatus to calibrate intensity and determine fringe order for interferometric measurement of small spacings,” U.S. patent5,457,534 (10October1995).

B. Bhushan, Tribology and Mechanics of Magnetic Storage Devices, 2nd ed. (Springer-Verlag, New York, 1996).
[CrossRef]

P. J. Sides , “Apparatus and method for measuring linear nanometric distances using evanescent radiation,” U.S. patent5,715,060 (3February1998).

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Figures (13)

Fig. 1
Fig. 1

Hard disk drive, showing the relative positions of the slider; HGA, head-gimbal assembly; actuator arm, and disk.

Fig. 2
Fig. 2

Schematic of the head to magnetic medium spacing on a platter in a hard disk drive. The fly height, which has decreased from hundreds of nanometers to less than 10 nm in current devices, is an important component of the spacing.

Fig. 3
Fig. 3

Schematic of the glass-air interface showing the generation of the evanescent wave. The decay length is ∼50 nm for He-Ne 633-nm/BK-7 glass and ∼40 nm for Ar 488/BK-7 glass.

Fig. 4
Fig. 4

Schematic of a three-layer system. Multiple reflections of both the evanescent wave and the scattered light influence overall transmittance. The dashed lines in the air gap and the asterisk on the angle of refraction are intended to alert the reader that the angle is complex and the rays are evanescent for total internal reflection.

Fig. 5
Fig. 5

Total transmittance as a function of FH for He-Ne and Ar lasers for both polarizations.

Fig. 6
Fig. 6

Second derivative of total transmittance [Eqs. (15) and (16)] as a function of FH. The zero crossing of the functions indicates an inflection point in the functions.

Fig. 7
Fig. 7

Schematic of the three-wavelength interferometry (DFHT) apparatus.

Fig. 8
Fig. 8

Schematic of the experimental SCATIR apparatus. The scattered photons enter the optical train of the DFHT. Thus the SCATIR measurement is piggybacked onto the instrument that takes equivalent measurements.

Fig. 9
Fig. 9

Measured SCATIR intensities using He-Ne 633 illumination. The lines are the fit of a cubic equation to the data. Note the inflection point that clearly appears in the p-polarization data.

Fig. 10
Fig. 10

Measured SCATIR intensities using Ar 488 illumination. The lines are the fit of a cubic equation to the data. Note the inflection point that clearly appears in the p-polarization data.

Fig. 11
Fig. 11

Comparison of SCATIR and DFHT data when the pure parameter fit method is used. The SCATIR results when this method of calibration is used do not agree well with the DFHT measurements.

Fig. 12
Fig. 12

Comparison of SCATIR and DFHT data when only the second derivative is used. The agreement is much better with this method of calibration.

Fig. 13
Fig. 13

Comparison of SCATIR and DFHT data when the hybrid calibration method is used where use of the second to derivative to find I p narrows the search for the optimal I s .

Equations (20)

Equations on this page are rendered with MathJax. Learn more.

I h = I 0 exp - α h ,
α = 4 π λ n 1 2   sin 2   θ 1 - n 2 2 1 / 2 ,
r sjk = ξ j - ξ k ξ j + ξ k ,
r pjk = n ˆ k 2 ξ j - n ˆ j 2 ξ k n ˆ k 2 ξ j + n ˆ j 2 ξ k
t sjk = 2 ξ j ξ j + ξ k ,
t pjk = 2 n ˆ j n ˆ k ξ j n ˆ k 2 ξ j + n ˆ j 2 ξ k ,
ξ j n ˆ j 2 - n 1 2   sin 2   θ j 1 / 2 ,
r s = r s 12 + r s 23   exp - 2 i β 1 + r s 12 r s 23   exp - 2 i β ,
r p = r p 12 + r p 23   exp - 2 i β 1 + r p 12 r p 23   exp - 2 i β ,
t s = t s 12 t s 23   exp - i β 1 + r s 12 r s 23   exp - 2 i β ,
t p = t p 12 t p 23   exp - i β 1 + r p 12 r p 23   exp - 2 i β .
β = 2 π ξ 2 h / λ ,
T s θ = Re   ξ 3 ξ 1   | t s | 2 ,
T p θ = Re ξ 3 / n ˆ 3 ξ 1   | n ˆ 3 t p | 2 ,
SCATIR s = I s T s θ h T s 0 h ,
SCATIR p = I p T p θ h T p 0 h .
error p j = SCATIR p j calc - SCATIR p j meas .
Error p = j   error p j .
I p Ar = SCATIR p Ar T p θ Ar 24.5 T p 0 Ar 24.5 ,
I p He - Ne = SCATIR p He - Ne T p θ He - Ne 32.5 T p 0 He - Ne 32.5 .

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