Abstract

In scanning systems for surface profile measurement, e.g., stylus systems, the profile of a surface is generally determined by measuring the distance of the surface relative to a reference plane. This can be either a plane defined by a moving stage under a rigid stylus or a plane defined by a moving stylus if a fixed stage is used. In both cases, the measurement precision is limited by the straightness of a linear motion. This paper presents a new interferometric profile measurement technique based on using a rigid differential interferometer probing the test object which is moved by a stage. Information on the surface profile is obtained by scanning the surface with two laser spots simultaneously and measuring the optical path difference between the reflected light beams. This makes the profile measurement largely insensitive to flatness errors of the mechanical stage and enables extremely precise measurements. Data processing is done digitally using a storage scope and a microprocessor. The suitability of this method for measuring the profiles of magnetic sliders and SIMS sputter craters has been investigated. The experimental work includes long- and short-term repeatability tests and an extensive investigation of the temperature dependent behavior of the measuring instrument.

© 1984 Optical Society of America

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References

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  1. J. M. Bennett, J. H. Dancy, “Stylus Profiling for Measuring Statistical Properties of Smooth Optical Surfaces,” Appl. Opt. 20, 1785 (1980).
    [CrossRef]
  2. J. H. Bruning et al., “Digital Wavefront Measuring Interferometer for Testing Optical Surfaces and Lenses,” Appl. Opt. 13, 2693 (1974).
    [CrossRef] [PubMed]
  3. M. J. Lavan et al., “Mach-Zehnder Heterodyne Interferometer,” Opt. Eng. 15, 464 (1976).
    [CrossRef]
  4. C. W. Chen, P. W. Mayman, “Use of Phase Measuring Interferometry for Surface Characterization,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 9 (1981).
  5. J. C. Wyant et al. “An Optical Profilometer for Surface Characterization of Magnetic Media,” ASLE Reprint 83-AM-6A-1.
  6. R. M. Pettigrew, F. J. Hancock, “An Optical Profilometer,” in Precision Engineering (IPC Business Press 0141-6359/79/03/03133-04, 1979), pp. 133–136.
    [CrossRef]
  7. G. Makosch, B. Solf., “Surface Profiling by Electro-optical Phase Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 42 (1981).
  8. L. Yencharis, “IBM’s Thin Film Heads Squeeze Disk Capacity to Record Levels,” Electron. Des. 5, 60 (1980).
  9. H.-E. Korth, “A Computer Integrated Spectrophotometer for Film Thickness Monitoring,” J. Phys. Paris 44, No. 12, 101 (1983).
    [CrossRef]

1983 (1)

H.-E. Korth, “A Computer Integrated Spectrophotometer for Film Thickness Monitoring,” J. Phys. Paris 44, No. 12, 101 (1983).
[CrossRef]

1981 (2)

C. W. Chen, P. W. Mayman, “Use of Phase Measuring Interferometry for Surface Characterization,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 9 (1981).

G. Makosch, B. Solf., “Surface Profiling by Electro-optical Phase Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 42 (1981).

1980 (2)

L. Yencharis, “IBM’s Thin Film Heads Squeeze Disk Capacity to Record Levels,” Electron. Des. 5, 60 (1980).

J. M. Bennett, J. H. Dancy, “Stylus Profiling for Measuring Statistical Properties of Smooth Optical Surfaces,” Appl. Opt. 20, 1785 (1980).
[CrossRef]

1976 (1)

M. J. Lavan et al., “Mach-Zehnder Heterodyne Interferometer,” Opt. Eng. 15, 464 (1976).
[CrossRef]

1974 (1)

Bennett, J. M.

Bruning, J. H.

Chen, C. W.

C. W. Chen, P. W. Mayman, “Use of Phase Measuring Interferometry for Surface Characterization,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 9 (1981).

Dancy, J. H.

Hancock, F. J.

R. M. Pettigrew, F. J. Hancock, “An Optical Profilometer,” in Precision Engineering (IPC Business Press 0141-6359/79/03/03133-04, 1979), pp. 133–136.
[CrossRef]

Korth, H.-E.

H.-E. Korth, “A Computer Integrated Spectrophotometer for Film Thickness Monitoring,” J. Phys. Paris 44, No. 12, 101 (1983).
[CrossRef]

Lavan, M. J.

M. J. Lavan et al., “Mach-Zehnder Heterodyne Interferometer,” Opt. Eng. 15, 464 (1976).
[CrossRef]

Makosch, G.

G. Makosch, B. Solf., “Surface Profiling by Electro-optical Phase Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 42 (1981).

Mayman, P. W.

C. W. Chen, P. W. Mayman, “Use of Phase Measuring Interferometry for Surface Characterization,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 9 (1981).

Pettigrew, R. M.

R. M. Pettigrew, F. J. Hancock, “An Optical Profilometer,” in Precision Engineering (IPC Business Press 0141-6359/79/03/03133-04, 1979), pp. 133–136.
[CrossRef]

Solf, B.

G. Makosch, B. Solf., “Surface Profiling by Electro-optical Phase Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 42 (1981).

Wyant, J. C.

J. C. Wyant et al. “An Optical Profilometer for Surface Characterization of Magnetic Media,” ASLE Reprint 83-AM-6A-1.

Yencharis, L.

L. Yencharis, “IBM’s Thin Film Heads Squeeze Disk Capacity to Record Levels,” Electron. Des. 5, 60 (1980).

Appl. Opt. (2)

Electron. Des. (1)

L. Yencharis, “IBM’s Thin Film Heads Squeeze Disk Capacity to Record Levels,” Electron. Des. 5, 60 (1980).

J. Phys. Paris (1)

H.-E. Korth, “A Computer Integrated Spectrophotometer for Film Thickness Monitoring,” J. Phys. Paris 44, No. 12, 101 (1983).
[CrossRef]

Opt. Eng. (1)

M. J. Lavan et al., “Mach-Zehnder Heterodyne Interferometer,” Opt. Eng. 15, 464 (1976).
[CrossRef]

Proc. Soc. Photo-Opt. Instrum. Eng. (2)

C. W. Chen, P. W. Mayman, “Use of Phase Measuring Interferometry for Surface Characterization,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 9 (1981).

G. Makosch, B. Solf., “Surface Profiling by Electro-optical Phase Measurement,” Proc. Soc. Photo-Opt. Instrum. Eng. 316, 42 (1981).

Other (2)

J. C. Wyant et al. “An Optical Profilometer for Surface Characterization of Magnetic Media,” ASLE Reprint 83-AM-6A-1.

R. M. Pettigrew, F. J. Hancock, “An Optical Profilometer,” in Precision Engineering (IPC Business Press 0141-6359/79/03/03133-04, 1979), pp. 133–136.
[CrossRef]

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Figures (16)

Fig. 1
Fig. 1

Differential interferometer: (a) principal optical arrangement; (b) measuring instrument.

Fig. 2
Fig. 2

Magnetic slider (4 × 3.2 mm).

Fig. 3
Fig. 3

Principle of slider profile measurement: (a) profile definition in an x-z plane; (b) readout signal of the differential interferometer.

Fig. 4
Fig. 4

Error distribution along the profile (N-total number of measurement intervals).

Fig. 5
Fig. 5

Effect of table flatness and pitch.

Fig. 6
Fig. 6

Profile measurement of slider ABS (practical result).

Fig. 7
Fig. 7

Profile measurement of slider ABS (practical results).

Fig. 8
Fig. 8

Distribution of measurement values (n = 50).

Fig. 9
Fig. 9

Distribution of measurement values (n = 55, reference mirror).

Fig. 10
Fig. 10

Distribution of measurement values (n = 50, without moving the table).

Fig. 11
Fig. 11

Repeated measurements of ABS extreme value.

Fig. 12
Fig. 12

Practical measurement error.

Fig. 13
Fig. 13

Scanning profile measurement of a SIMS sputter crater: (a) top view of the crater; (b) cross section; (c) response curve of differential interferometer.

Fig. 14
Fig. 14

Profile measurement results: (a) phase measurement signal; (b) profile of SIMS sputter crater.

Fig. 15
Fig. 15

Comparative profile measurements: (a) differential interferometer; (b) stylus instrument.

Fig. 16
Fig. 16

Profile measurement of a slider taper: (a) phase measurement signal; (b) profile of the taper.

Tables (2)

Tables Icon

Table I Results of Measurements

Tables Icon

Table II Results of Correlation Measurements

Equations (19)

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h ( x ) = z ( x ) - z ( x - d )
x k = k · d             ( k = 1 , 2 , 3 )
x N = N · d = L .
h k = z ( x k ) - z ( x k - 1 )             ( k = 1 , 2 , 3 N ) , z ( 0 ) = 0 , Def . ! ] ,
z ( x k ) = i = 1 k h i             ( i = 1 , 2 , 3 ) .
z = - x sin β + z cos β , x = x cos β + z sin β , tan β = z ( x N ) x N .
z ( x k ) = m = 1 k h m - x k x N i = 1 N h i ,
x k x N = k N ,
z ( x k ) = m = 1 k h m - k N i = 1 N h i
z ( x k ) = ( 1 - k N ) i = 1 k h i - k N i = k + 1 N h i .
u k = u 0 ( k - k 2 N ) 1 / 2             ( k = 1 , 2 , 3 N ) ,
u k = / 2 1 u 0 · N 1 / 2 ,
u 0 = ( u i 2 + u α 2 ) 1 / 2 .
u α = ( α · d ) / 4 ,
u ^ k = / 2 1 N 1 / 2 [ u i 2 + ( α · d 4 ) 2 ] 1 / 2 .
d = d 0 = 4 u i α .
u ^ k = u = ( L · u i · α 8 ) 1 / 2 = u i ( L 2 d 0 ) 1 / 2 ,
u α = ( α · d ) / 4 ,
u = ( u i 2 + u α 2 ) 1 / 2 .

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