Abstract

The resolution of chemically amplified resists is becoming an increasing concern, especially for lithography in the extreme ultraviolet (EUV) regime. Large-scale screening is currently under way to identify resist platforms that can support the demanding specifications required for EUV lithography. Current screeningprocesses would benefit from the development of metrics that can objectively quantify resist resolution in a high-throughput fashion. Here we examine two high-throughput metrics for resist resolution determination. After summarizing their details and justifying their utility, we characterize the sensitivity of both metrics to known uncertainties in exposure tool aberrations and focus control. For an implementation at EUV wavelengths, wereportaberration and focus-limited error bars in extracted resolution of 1.25  nm rms for both metrics, making them attractive candidates for future screening and downselection efforts.

© 2008 Optical Society of America

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References

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  1. S. Wurm, "EUV lithography development in the United States," presented at the Fourth International EUV Lithography Symposium, San Diego, Calif., 7-9 November 2005, proceedings available from SEMATECH, Austin, Tex.
  2. S. Wurm, "EUV lithography update," presented at the Fifth International Symposium on EUV Lithography, Barcelona, Spain, 15-18 October 2006, proceedings available from SEMATECH, Austin, Tex.
  3. G. M. Schmid, M. D. Stewart, C. Wang, B. D. Vogt, M. Vivek, E. K. Lin, and C. G. Willson, "Resolution limitations in chemically amplified photoresist systems," Proc. SPIE 5376, 333-342 (2004).
  4. G. F. Lorusso, P. Leunissen, M. Ercken, C. Delvaux, F. V. Roey, and N. Vandenbroeck, "Spectral analysis of line width roughness and its applications to immersion lithography," J. Microlithogr., Microfab., Microsyst. 5, 033003 (2006).
  5. P. Naulleau and C. Anderson, "Lithographic metrics for the determination of intrinsic resolution limits in EUV resists," Proc. SPIE 6517, 65172N (2007).
  6. J. Hoffnagle, W. D. Hinsberg, F. A. Houle, and M. I. Sanchez, "Characterization of photoresist spatial resolution by interferometric lithography," Proc. SPIE 5038, 464-472 (2003).
  7. T. Brunner, C. Fonseca, N. Seong, and M. Burkhardt, "Impact of resist blur on MEF, OPC, and PD control," Proc. SPIE 5377, 141-149 (2004).
  8. P. Dirksen, J. Braat, A. J. E. M. Janssen, A. Leeuwestein, H. Kwinten, and D. Van Steenwinckel, "Determination of resist parameters using the extended Nijboer-Zernike theory," Proc. SPIE 5377, 150-159 (2004).
  9. R. Jones and J. Byers, "Theoretical corner rounding analysis and mask writer simulation," Proc. SPIE 5040, 1035-1043 (2003).
  10. C. Ahn, H. Kim, and K. Baik, "Novel approximate model for resist process," Proc. SPIE 3334, 752-763 (1998).
  11. P. Naulleau, "Status of EUV micro-exposure capabilities at the ALS using the 0.3-NA MET optic," Proc. SPIE 5374, 881-891 (2004).
  12. K. Goldberg, P. Naulleau, P. Denham, S. Rekawa, K. Jackson, E. Anderson, and J. A. Liddle, "At-wavelength alignment and testing of the 0.3 NA MET optic," J. Vac. Sci. Technol. B 22, 2956-2961 (2004).
  13. As an external control, all experimental and modeling corner data are taken at and around the dose where the coded 100 nm features print at 100 nm.
  14. Note that commercial modeling packages such as prolith and solid e could also be used.

2007

P. Naulleau and C. Anderson, "Lithographic metrics for the determination of intrinsic resolution limits in EUV resists," Proc. SPIE 6517, 65172N (2007).

2006

G. F. Lorusso, P. Leunissen, M. Ercken, C. Delvaux, F. V. Roey, and N. Vandenbroeck, "Spectral analysis of line width roughness and its applications to immersion lithography," J. Microlithogr., Microfab., Microsyst. 5, 033003 (2006).

2004

G. M. Schmid, M. D. Stewart, C. Wang, B. D. Vogt, M. Vivek, E. K. Lin, and C. G. Willson, "Resolution limitations in chemically amplified photoresist systems," Proc. SPIE 5376, 333-342 (2004).

T. Brunner, C. Fonseca, N. Seong, and M. Burkhardt, "Impact of resist blur on MEF, OPC, and PD control," Proc. SPIE 5377, 141-149 (2004).

P. Dirksen, J. Braat, A. J. E. M. Janssen, A. Leeuwestein, H. Kwinten, and D. Van Steenwinckel, "Determination of resist parameters using the extended Nijboer-Zernike theory," Proc. SPIE 5377, 150-159 (2004).

P. Naulleau, "Status of EUV micro-exposure capabilities at the ALS using the 0.3-NA MET optic," Proc. SPIE 5374, 881-891 (2004).

K. Goldberg, P. Naulleau, P. Denham, S. Rekawa, K. Jackson, E. Anderson, and J. A. Liddle, "At-wavelength alignment and testing of the 0.3 NA MET optic," J. Vac. Sci. Technol. B 22, 2956-2961 (2004).

2003

R. Jones and J. Byers, "Theoretical corner rounding analysis and mask writer simulation," Proc. SPIE 5040, 1035-1043 (2003).

J. Hoffnagle, W. D. Hinsberg, F. A. Houle, and M. I. Sanchez, "Characterization of photoresist spatial resolution by interferometric lithography," Proc. SPIE 5038, 464-472 (2003).

1998

C. Ahn, H. Kim, and K. Baik, "Novel approximate model for resist process," Proc. SPIE 3334, 752-763 (1998).

J. Microlithogr., Microfab., Microsyst.

G. F. Lorusso, P. Leunissen, M. Ercken, C. Delvaux, F. V. Roey, and N. Vandenbroeck, "Spectral analysis of line width roughness and its applications to immersion lithography," J. Microlithogr., Microfab., Microsyst. 5, 033003 (2006).

J. Vac. Sci. Technol. B

K. Goldberg, P. Naulleau, P. Denham, S. Rekawa, K. Jackson, E. Anderson, and J. A. Liddle, "At-wavelength alignment and testing of the 0.3 NA MET optic," J. Vac. Sci. Technol. B 22, 2956-2961 (2004).

Proc. SPIE

G. M. Schmid, M. D. Stewart, C. Wang, B. D. Vogt, M. Vivek, E. K. Lin, and C. G. Willson, "Resolution limitations in chemically amplified photoresist systems," Proc. SPIE 5376, 333-342 (2004).

P. Naulleau and C. Anderson, "Lithographic metrics for the determination of intrinsic resolution limits in EUV resists," Proc. SPIE 6517, 65172N (2007).

J. Hoffnagle, W. D. Hinsberg, F. A. Houle, and M. I. Sanchez, "Characterization of photoresist spatial resolution by interferometric lithography," Proc. SPIE 5038, 464-472 (2003).

T. Brunner, C. Fonseca, N. Seong, and M. Burkhardt, "Impact of resist blur on MEF, OPC, and PD control," Proc. SPIE 5377, 141-149 (2004).

P. Dirksen, J. Braat, A. J. E. M. Janssen, A. Leeuwestein, H. Kwinten, and D. Van Steenwinckel, "Determination of resist parameters using the extended Nijboer-Zernike theory," Proc. SPIE 5377, 150-159 (2004).

R. Jones and J. Byers, "Theoretical corner rounding analysis and mask writer simulation," Proc. SPIE 5040, 1035-1043 (2003).

C. Ahn, H. Kim, and K. Baik, "Novel approximate model for resist process," Proc. SPIE 3334, 752-763 (1998).

P. Naulleau, "Status of EUV micro-exposure capabilities at the ALS using the 0.3-NA MET optic," Proc. SPIE 5374, 881-891 (2004).

Other

As an external control, all experimental and modeling corner data are taken at and around the dose where the coded 100 nm features print at 100 nm.

Note that commercial modeling packages such as prolith and solid e could also be used.

S. Wurm, "EUV lithography development in the United States," presented at the Fourth International EUV Lithography Symposium, San Diego, Calif., 7-9 November 2005, proceedings available from SEMATECH, Austin, Tex.

S. Wurm, "EUV lithography update," presented at the Fifth International Symposium on EUV Lithography, Barcelona, Spain, 15-18 October 2006, proceedings available from SEMATECH, Austin, Tex.

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Figures (8)

Fig. 1
Fig. 1

Fifty nanometer contact metric: (a) Modeled deprotection image cross sections for resist blurs of 0, 5, , 35   nm . Lighter colors are larger blurs. (b) Experimental PD versus relative dose curves for MET1K and EUV2D resists.

Fig. 2
Fig. 2

Through-dose 50   nm contact printing in (a) MET1K and (b) EUV2D resists with 15% relative dose steps between exposures.

Fig. 3
Fig. 3

(a) Modeled rounding of a 700   nm elbow corner for varying degrees of deprotection blur. Blur numbers are given in nanometers, FWHM. (b), (c) Equal magnification SEM images of a 700   nm elbow corner at dose to size [9] in MET1K and EUV2D resists, respectively.

Fig. 4
Fig. 4

Left, screenshot of software used to extract corner rounding from an experimental SEM image. Right, radial lineouts for the ideal (nonrounded) and actual (rounded) corner edges.

Fig. 5
Fig. 5

Modeled rounding versus blur curves for the corner metric focus study. There are five focus curves associated with [ 50 , 25 , 0 , 25 , 50 ]  nm of defocus.

Fig. 6
Fig. 6

Modeled rounding versus blur curves for the corner metric aberration study. There are ten random aberration curves at each rms noise level: (a) 10%, (b) 20%, and (c) 30%. (d) Zoomed 30% noise plot centered around the radius of 90 nm. Solid curves indicate modeled radius versus blur data for the ten aberration maps in the 30% noise level. The intersections of the horizontal dashed line at radius = 90   nm with the ten modeled curves are traced down with vertical dashed lines to show the range of blurs that might produce a rounding of 90   nm assuming a 30% rms uncertainty in optical aberrations.

Fig. 7
Fig. 7

Modeled PD versus relative dose curves for the contact metric focus study. Each gray level corresponds to one blur. There are eight blurs spanning 0 35   nm in 5   nm steps. Each blur level contains five focus curves associated with [ 50 , 25 , 0 , 25 , 50 ]  nm of defocus. Note the heavy overlap of the 0 and 5   nm blur curves.

Fig. 8
Fig. 8

Modeled PD versus relative dose curves for the contact metric aberration study. Each gray level corresponds to one blur. There are eight blurs spanning 0 35   nm in 5   nm steps. Each blur level contains ten curves, one from each of the ten randomly generated optical aberration maps within a given aberration noise level. Plots (a)–(d) are associated with rms aberration noise levels of 0%, 10%, 20%, and 30%, respectively. Note the heavy overlap of the 0 and 5   nm blur level curves.

Tables (2)

Tables Icon

Table 1 Aberration-Limited Error Bars for the Corner Rounding Metric a

Tables Icon

Table 2 Aberration-Limited Error Bars for the Contact Metric a

Metrics