Abstract

A microscope coherent optical processor based on the VanderLugt optical correlator is applied to the measurement of registration error in multilayer integrated-circuit wafers. A treatment of the effects of wafer faults on the correlation signal is given. Threshold criteria and fault-induced peak splitting of the correlation signal from reject production samples are exploited to demonstrate the easy and rapid detection of faults in partially processed integrated-circuit wafers.

© 1994 Optical Society of America

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References

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  1. B. E. Dom, “Machine vision techniques for integrated circuit inspection,” in Machine Vision for Inspection and Measurement, H. Freeman, ed. (Academic, New York, 1989), pp. 257–282.
  2. K. Harris, P. Sandland, R. Singleton, “Wafer inspection automation: current and future needs,” Solid State Technol. 8, 199–205 (1983).
  3. P. Blaustein, S. Hahn, “Real-time inspection of wafer surfaces,” Solid State Technol. 12, 27–29 (1989).
  4. J. Lyman, “Moving wafer inspection into the fast lane,” Electronics (5March1987), pp. 74–76.
  5. M. S. I. Valera, “Efficient matched spatial filters for coherent optical processing,” Ph.D. dissertation (University of Manchester Institute of Science and Technology, Manchester, UK, 1989).
  6. A. D. Fisher, J. N. Lee, “The current status of two-dimensional spatial light modulator technology,” in Optical and Hybrid Computing, H. H. Szu, ed., Proc. Soc. Photo-Opt. Instrum. Eng.634, 352–371 (1986).
  7. G. Indebetouw, T. Tschudi, G. Herziger, “Quality control of small mechanical pieces using optical correlation techniques,” Appl. Opt. 15, 516–522 (1976).
    [CrossRef] [PubMed]
  8. G. Indebetouw, T. Tschudi, J. Steffen, “Optical processing techniques in the quality control of microelectronics,” Appl. Opt. 17, 911–916 (1978).
    [CrossRef] [PubMed]
  9. X. Y. Cai, F. Kvasnik, “Wafer pattern inspection using a coherent optical processor,” in Machine Vision Applications in Character Recognition and Industrial Inspection, W. Blanz, D. P. D’Amato, B. E. Dom, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1661, 333–344 (1992).
  10. A. VanderLugt, “Signal detection by complex signal filtering,” IRE Trans. Info. Theory IT-10, 139–145 (1964).
    [CrossRef]
  11. See, for example, F. T. S. Yu, Optical Information Processing (Wiley, New York, 1983).
  12. G. L. Turin, “An introduction to matched filters,” IRE Trans. Info. Theory IT-6, 311–324 (1960).
    [CrossRef]
  13. X. Y. Cai, F. Kvasnik, “Space-variant characteristics in multiple object recognition with a coherent optical processor,” J. Mod. Opt. 38, 1145–1158 (1991).
    [CrossRef]

1991 (1)

X. Y. Cai, F. Kvasnik, “Space-variant characteristics in multiple object recognition with a coherent optical processor,” J. Mod. Opt. 38, 1145–1158 (1991).
[CrossRef]

1989 (1)

P. Blaustein, S. Hahn, “Real-time inspection of wafer surfaces,” Solid State Technol. 12, 27–29 (1989).

1987 (1)

J. Lyman, “Moving wafer inspection into the fast lane,” Electronics (5March1987), pp. 74–76.

1983 (1)

K. Harris, P. Sandland, R. Singleton, “Wafer inspection automation: current and future needs,” Solid State Technol. 8, 199–205 (1983).

1978 (1)

1976 (1)

1964 (1)

A. VanderLugt, “Signal detection by complex signal filtering,” IRE Trans. Info. Theory IT-10, 139–145 (1964).
[CrossRef]

1960 (1)

G. L. Turin, “An introduction to matched filters,” IRE Trans. Info. Theory IT-6, 311–324 (1960).
[CrossRef]

Blaustein, P.

P. Blaustein, S. Hahn, “Real-time inspection of wafer surfaces,” Solid State Technol. 12, 27–29 (1989).

Cai, X. Y.

X. Y. Cai, F. Kvasnik, “Space-variant characteristics in multiple object recognition with a coherent optical processor,” J. Mod. Opt. 38, 1145–1158 (1991).
[CrossRef]

X. Y. Cai, F. Kvasnik, “Wafer pattern inspection using a coherent optical processor,” in Machine Vision Applications in Character Recognition and Industrial Inspection, W. Blanz, D. P. D’Amato, B. E. Dom, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1661, 333–344 (1992).

Dom, B. E.

B. E. Dom, “Machine vision techniques for integrated circuit inspection,” in Machine Vision for Inspection and Measurement, H. Freeman, ed. (Academic, New York, 1989), pp. 257–282.

Fisher, A. D.

A. D. Fisher, J. N. Lee, “The current status of two-dimensional spatial light modulator technology,” in Optical and Hybrid Computing, H. H. Szu, ed., Proc. Soc. Photo-Opt. Instrum. Eng.634, 352–371 (1986).

Hahn, S.

P. Blaustein, S. Hahn, “Real-time inspection of wafer surfaces,” Solid State Technol. 12, 27–29 (1989).

Harris, K.

K. Harris, P. Sandland, R. Singleton, “Wafer inspection automation: current and future needs,” Solid State Technol. 8, 199–205 (1983).

Herziger, G.

Indebetouw, G.

Kvasnik, F.

X. Y. Cai, F. Kvasnik, “Space-variant characteristics in multiple object recognition with a coherent optical processor,” J. Mod. Opt. 38, 1145–1158 (1991).
[CrossRef]

X. Y. Cai, F. Kvasnik, “Wafer pattern inspection using a coherent optical processor,” in Machine Vision Applications in Character Recognition and Industrial Inspection, W. Blanz, D. P. D’Amato, B. E. Dom, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1661, 333–344 (1992).

Lee, J. N.

A. D. Fisher, J. N. Lee, “The current status of two-dimensional spatial light modulator technology,” in Optical and Hybrid Computing, H. H. Szu, ed., Proc. Soc. Photo-Opt. Instrum. Eng.634, 352–371 (1986).

Lyman, J.

J. Lyman, “Moving wafer inspection into the fast lane,” Electronics (5March1987), pp. 74–76.

Sandland, P.

K. Harris, P. Sandland, R. Singleton, “Wafer inspection automation: current and future needs,” Solid State Technol. 8, 199–205 (1983).

Singleton, R.

K. Harris, P. Sandland, R. Singleton, “Wafer inspection automation: current and future needs,” Solid State Technol. 8, 199–205 (1983).

Steffen, J.

Tschudi, T.

Turin, G. L.

G. L. Turin, “An introduction to matched filters,” IRE Trans. Info. Theory IT-6, 311–324 (1960).
[CrossRef]

Valera, M. S. I.

M. S. I. Valera, “Efficient matched spatial filters for coherent optical processing,” Ph.D. dissertation (University of Manchester Institute of Science and Technology, Manchester, UK, 1989).

VanderLugt, A.

A. VanderLugt, “Signal detection by complex signal filtering,” IRE Trans. Info. Theory IT-10, 139–145 (1964).
[CrossRef]

Yu, F. T. S.

See, for example, F. T. S. Yu, Optical Information Processing (Wiley, New York, 1983).

Appl. Opt. (2)

Electronics (1)

J. Lyman, “Moving wafer inspection into the fast lane,” Electronics (5March1987), pp. 74–76.

IRE Trans. Info. Theory (2)

A. VanderLugt, “Signal detection by complex signal filtering,” IRE Trans. Info. Theory IT-10, 139–145 (1964).
[CrossRef]

G. L. Turin, “An introduction to matched filters,” IRE Trans. Info. Theory IT-6, 311–324 (1960).
[CrossRef]

J. Mod. Opt. (1)

X. Y. Cai, F. Kvasnik, “Space-variant characteristics in multiple object recognition with a coherent optical processor,” J. Mod. Opt. 38, 1145–1158 (1991).
[CrossRef]

Solid State Technol. (2)

K. Harris, P. Sandland, R. Singleton, “Wafer inspection automation: current and future needs,” Solid State Technol. 8, 199–205 (1983).

P. Blaustein, S. Hahn, “Real-time inspection of wafer surfaces,” Solid State Technol. 12, 27–29 (1989).

Other (5)

See, for example, F. T. S. Yu, Optical Information Processing (Wiley, New York, 1983).

M. S. I. Valera, “Efficient matched spatial filters for coherent optical processing,” Ph.D. dissertation (University of Manchester Institute of Science and Technology, Manchester, UK, 1989).

A. D. Fisher, J. N. Lee, “The current status of two-dimensional spatial light modulator technology,” in Optical and Hybrid Computing, H. H. Szu, ed., Proc. Soc. Photo-Opt. Instrum. Eng.634, 352–371 (1986).

X. Y. Cai, F. Kvasnik, “Wafer pattern inspection using a coherent optical processor,” in Machine Vision Applications in Character Recognition and Industrial Inspection, W. Blanz, D. P. D’Amato, B. E. Dom, eds., Proc. Soc. Photo-Opt. Instrum. Eng.1661, 333–344 (1992).

B. E. Dom, “Machine vision techniques for integrated circuit inspection,” in Machine Vision for Inspection and Measurement, H. Freeman, ed. (Academic, New York, 1989), pp. 257–282.

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Figures (12)

Fig. 1
Fig. 1

Block diagram of the microscope coherent optical processor (MCOP).

Fig. 2
Fig. 2

Negative images and transmittance profiles of a typical amplitude filter recorded with total exposures of (a) 8 nW, (b) 30 nW, and (c) 250 nW.

Fig. 3
Fig. 3

Chips on the voltage-regulator wafer in (a) undamaged and (b) faulty states.

Fig. 4
Fig. 4

Correlation peak intensity as functions of (a) axial and (b) lateral displacement.

Fig. 5
Fig. 5

Correlation profiles obtained with (a) an undamaged and (b) a faculty chip on the voltage-regulator wafer.

Fig. 6
Fig. 6

Correlation profiles obtained from the voltage-regulator wafer after direction filtering of (a) an undamaged and (b) a faulty chip.

Fig. 7
Fig. 7

Faulty uncommitted logic gate on the ASIC wafer.

Fig. 8
Fig. 8

Interface element on the ASIC wafer.

Fig. 9
Fig. 9

Correlations profiles obtained from the ASIC wafer showing the effect of the three amplitude niters in Fig. 2, which have the half-widths at half-maximum transmittance of (a) 3.5 line pairs mm−1, (b) 6.8 line pairs mm−1, and (c) 7.3 line pairs mm−1.

Fig. 10
Fig. 10

Correlation profiles obtained from the ASIC wafer with the gate-array matched spatial filter with a chip (a) near the center of the wafer and (b) near the edge of the wafer.

Fig. 11
Fig. 11

Vector plot of the relative displacement of the connect layer on the ASIC wafer obtained with the interface-element matched spatial filter (displacements shown micrometers).

Fig. 12
Fig. 12

Comparison of relative displacement measurements by MCOP and by conventional optical microscopy with the ASIC wafer and the interface-element matched spatial filter.

Tables (1)

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Table 1 Individual Correlation Intensities from the Voltage-Regulator Wafer as Percentages of Autocorrelation Intensities

Equations (16)

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

g R ( x ) = i h i ( x x i ) ,
g S ( x ) = j h j ( α j x + β j x j ) .
C ( ξ ) = g R ( x ) g S ( x ) = g R ( x ) g S * ( x ξ ) d x = i j C i j ( ξ ) ,
C i j ( ξ ) = h i ( x x i ) h j ( α j x + β j x j ) .
C i j ( ξ ) = A i j * δ ( ξ ξ i j Δ j ) ,
A i j ( ξ ) = h i ( x ) h j ( α j x ) ,
ξ i j = x i x j ,
Δ j = x j ( 1 1 / α j ) β j / α j .
ξ i j = x i x j ,
S i j , k l = ξ i j ξ k l = ( x i x k ) ( x j x l ) .
ξ i j = ξ i j + Δ j = x i x j / α j + β j / α j ,
S i j , k l = ξ i j ξ k l = ( x i x k ) ( x j / α j x l / α l ) + ( β j / α j β l / α l ) .
S i j , j i = ( 1 + 1 / α ) ( x i x j ) .
S i i , j j = ( 1 1 / α ) ( x i x j ) ,
S i j , j i = 2 ( x i x j ) + ( β j β i ) ,
S i i , j j = β j β i .

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