Abstract

CMOS image sensors with smaller pixels are expected to enable digital imaging systems with better resolution. When pixel size scales below 2 μm, however, diffraction affects the optical performance of the pixel and its microlens, in particular. We present a first-principles electromagnetic analysis of microlens behavior during the lateral scaling of CMOS image sensor pixels. We establish for a three-metal-layer pixel that diffraction prevents the microlens from acting as a focusing element when pixels become smaller than 1.4 μm. This severely degrades performance for on and off-axis pixels in red, green and blue color channels. We predict that one-metal-layer or backside-illuminated pixels are required to extend the functionality of microlenses beyond the 1.4 μm pixel node.

© 2010 OSA

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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]
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    [CrossRef]
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    [CrossRef]
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  20. S. Iwabuchi, Y. Maruyama, Y. Ohgishi, M. Muramatsu, N. Karasawa, and T. Hirayama, “A Back-illuminated high-sensitivity small-pixel color CMOS image sensor with flexible layout of metal wiring,” 2006 IEEE Intl. Solid-State Circuits Conf., 1171–1178 (2006).
  21. T. Joy, S. Pyo, S. Park, C. Choi, C. Palsule, H. Han, C. Feng, S. Lee, J. McKee, P. Altice, C. Hong, C. Boemler, J. Hynecek, M. Louie, J. Lee, D. Kim, H. Haddad, and B. Pain, “Development of a production-ready, back-illuminated CMOS image sensor with small pixels,” 2007 IEEE Intl. Electron Dev. Meeting, 1007–1010 (2007).
  22. C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Optical confinement methods for continued scaling of CMOS image sensor pixels,” Opt. Express 16(25), 20457–20470 (2008).
    [CrossRef]

2009

C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Effects of imaging lens f-number on sub-2 μm CMOS image sensor pixel performance,” Proc. SPIE 7250, 72500G (2009).

2008

2005

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

P. B. Catrysse and B. A. Wandell, “Roadmap for CMOS image sensors: Moore meets Planck and Sommerfeld,” Proc. SPIE 5678, 1–13 (2005).

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

2003

G. Agranov, V. Berezin, and R. H. Tsai, “Crosstalk and microlens study in a color CMOS image sensor,” IEEE Trans. Electron. Dev. 50(1), 4–11 (2003).
[CrossRef]

C. P. Lin, H. Yang, and C. K. Chao, “Hexagonal microlens array modeling and fabrication using a thermal reflow process,” J. Micromech. Microeng. 13(5), 775–781 (2003).
[CrossRef]

P. B. Catrysse and B. A. Wandell, “Integrated color pixels in 0.18-μm complementary metal oxide semiconductor technology,” J. Opt. Soc. Am. A 20(12), 2293–2306 (2003).
[CrossRef]

2002

2000

D. M. Hartmann, O. Kibar, and S. C. Esener, “Characterization of a polymer microlens fabricated by use of the hydrophobic effect,” Opt. Lett. 25(13), 975–977 (2000).
[CrossRef]

K. Shinmou, K. Nakama, and T. Koyama, “Fabrication of micro-optic elements by the sol-gel method,” J. Sol-Gel Sci. Technol. 19(1/3), 267–269 (2000).
[CrossRef]

1994

J. P. Bérenger, “A perfectly matched layer for the absorption of electromagnetic waves,” J. Comput. Phys. 114(2), 185–200 (1994).
[CrossRef]

1982

Agranov, G.

G. Agranov, V. Berezin, and R. H. Tsai, “Crosstalk and microlens study in a color CMOS image sensor,” IEEE Trans. Electron. Dev. 50(1), 4–11 (2003).
[CrossRef]

Bérenger, J. P.

J. P. Bérenger, “A perfectly matched layer for the absorption of electromagnetic waves,” J. Comput. Phys. 114(2), 185–200 (1994).
[CrossRef]

Berezin, V.

G. Agranov, V. Berezin, and R. H. Tsai, “Crosstalk and microlens study in a color CMOS image sensor,” IEEE Trans. Electron. Dev. 50(1), 4–11 (2003).
[CrossRef]

Bu, J.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Catrysse, P. B.

Chao, C. K.

C. P. Lin, H. Yang, and C. K. Chao, “Hexagonal microlens array modeling and fabrication using a thermal reflow process,” J. Micromech. Microeng. 13(5), 775–781 (2003).
[CrossRef]

Cheong, W. C.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Esener, S. C.

Fesenmaier, C. C.

C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Effects of imaging lens f-number on sub-2 μm CMOS image sensor pixel performance,” Proc. SPIE 7250, 72500G (2009).

C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Optical confinement methods for continued scaling of CMOS image sensor pixels,” Opt. Express 16(25), 20457–20470 (2008).
[CrossRef]

Hartmann, D. M.

He, M.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Huo, Y.

C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Effects of imaging lens f-number on sub-2 μm CMOS image sensor pixel performance,” Proc. SPIE 7250, 72500G (2009).

C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Optical confinement methods for continued scaling of CMOS image sensor pixels,” Opt. Express 16(25), 20457–20470 (2008).
[CrossRef]

Hwang, S. B.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

Kibar, O.

Kim, H. J.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

Kim, J. S.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

Kim, S. Y.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

Koyama, T.

K. Shinmou, K. Nakama, and T. Koyama, “Fabrication of micro-optic elements by the sol-gel method,” J. Sol-Gel Sci. Technol. 19(1/3), 267–269 (2000).
[CrossRef]

Lee, J. G.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

Lee, W. G.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

Li, Y.

Lin, C. P.

C. P. Lin, H. Yang, and C. K. Chao, “Hexagonal microlens array modeling and fabrication using a thermal reflow process,” J. Micromech. Microeng. 13(5), 775–781 (2003).
[CrossRef]

Nakama, K.

K. Shinmou, K. Nakama, and T. Koyama, “Fabrication of micro-optic elements by the sol-gel method,” J. Sol-Gel Sci. Technol. 19(1/3), 267–269 (2000).
[CrossRef]

Niu, H. B.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Peng, X.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Shinmou, K.

K. Shinmou, K. Nakama, and T. Koyama, “Fabrication of micro-optic elements by the sol-gel method,” J. Sol-Gel Sci. Technol. 19(1/3), 267–269 (2000).
[CrossRef]

Tsai, R. H.

G. Agranov, V. Berezin, and R. H. Tsai, “Crosstalk and microlens study in a color CMOS image sensor,” IEEE Trans. Electron. Dev. 50(1), 4–11 (2003).
[CrossRef]

Wandell, B. A.

Yang, H.

C. P. Lin, H. Yang, and C. K. Chao, “Hexagonal microlens array modeling and fabrication using a thermal reflow process,” J. Micromech. Microeng. 13(5), 775–781 (2003).
[CrossRef]

Yu, W. X.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Yuan, X. C.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

Appl. Phys. Lett.

X. C. Yuan, W. X. Yu, M. He, J. Bu, W. C. Cheong, H. B. Niu, and X. Peng, “Soft-lithography-enabled fabrication of large numerical aperture refractive microlens array in hybrid SiO–TiO sol-gel glass,” Appl. Phys. Lett. 86(11), 114102 (2005).
[CrossRef]

IEEE Trans. Electron. Dev.

G. Agranov, V. Berezin, and R. H. Tsai, “Crosstalk and microlens study in a color CMOS image sensor,” IEEE Trans. Electron. Dev. 50(1), 4–11 (2003).
[CrossRef]

J. Comput. Phys.

J. P. Bérenger, “A perfectly matched layer for the absorption of electromagnetic waves,” J. Comput. Phys. 114(2), 185–200 (1994).
[CrossRef]

J. Korean Phys. Soc.

W. G. Lee, J. S. Kim, H. J. Kim, S. Y. Kim, S. B. Hwang, and J. G. Lee, “Two-dimensional optical simulation on a visible ray passing through inter-metal dielectric layers of CMOS image sensor device,” J. Korean Phys. Soc. 47, S434–S439 (2005).

J. Micromech. Microeng.

C. P. Lin, H. Yang, and C. K. Chao, “Hexagonal microlens array modeling and fabrication using a thermal reflow process,” J. Micromech. Microeng. 13(5), 775–781 (2003).
[CrossRef]

J. Opt. Soc. Am.

J. Opt. Soc. Am. A

J. Sol-Gel Sci. Technol.

K. Shinmou, K. Nakama, and T. Koyama, “Fabrication of micro-optic elements by the sol-gel method,” J. Sol-Gel Sci. Technol. 19(1/3), 267–269 (2000).
[CrossRef]

Opt. Express

Opt. Lett.

Proc. SPIE

C. C. Fesenmaier, Y. Huo, and P. B. Catrysse, “Effects of imaging lens f-number on sub-2 μm CMOS image sensor pixel performance,” Proc. SPIE 7250, 72500G (2009).

P. B. Catrysse and B. A. Wandell, “Roadmap for CMOS image sensors: Moore meets Planck and Sommerfeld,” Proc. SPIE 5678, 1–13 (2005).

Other

H. Rhodes, G. Agranov, C. Hong, U. Boettiger, R. Mauritzson, J. Ladd, I. Karasev, J. McKee, E. Jenkins, and W. Quinlin, “CMOS imager technology shrinks and image performance,” 2004 IEEE Workshop on Microelectronics and Electron. Devices, 7–18 (2004).

K. B. Cho, C. Lee, S. Eikedal, A. Baum, J. Jiang, C. Xu, X. Fan, and R. Kauffman, “A 1/2.5 inch 8.1 Mpixel CMOS image sensor for digital cameras,” 2007 IEEE Intl. Solid-State Circuits Conf., 508–618 (2007).

C. R. Moon, J. C. Shin, J. Kim, Y. K. Lee, Y. J. Cho, Y. Y. Yu, S. H. Hwang, B. J. Park, H. Y. Kim, S. H. Lee, J. Jung, S. H. Cho, K. Lee, K. Koh, D. Lee, and K. Kim, “Dedicated process architecture and the characteristics of 1.4 μm pixel CMOS image sensor with 8M density,” 2007 IEEE Symp. on VLSI Tech., 62–63 (2007).

E. D. Palik, Handbook of Optical Constants of Solids (Academic Press, Orlando, 1985).

J. Ahn, C. R. Moon, B. Kim, K. Lee, Y. Kim, M. Lim, W. Lee, H. Park, K. Moon, J. Yoo, Y. J. Lee, B. J. Park, S. Jung, J. Lee, T. H. Lee, Y. K. Lee, J. Jung, J. H. Kim, T. C. Kim, H. Cho, D. Lee, and Y. Lee, “Advanced image sensor technology for pixel scaling down toward 1.0μm,” 2008 IEEE Intl. Electron Dev. Meeting, 1–4 (2008).

S. Iwabuchi, Y. Maruyama, Y. Ohgishi, M. Muramatsu, N. Karasawa, and T. Hirayama, “A Back-illuminated high-sensitivity small-pixel color CMOS image sensor with flexible layout of metal wiring,” 2006 IEEE Intl. Solid-State Circuits Conf., 1171–1178 (2006).

T. Joy, S. Pyo, S. Park, C. Choi, C. Palsule, H. Han, C. Feng, S. Lee, J. McKee, P. Altice, C. Hong, C. Boemler, J. Hynecek, M. Louie, J. Lee, D. Kim, H. Haddad, and B. Pain, “Development of a production-ready, back-illuminated CMOS image sensor with small pixels,” 2007 IEEE Intl. Electron Dev. Meeting, 1007–1010 (2007).

A. Taflove and S. C. Hagness, Computational electrodynamics: the finite-difference time-domain method (Artech House, Boston, 2000).

OptiFDTD, Optiwave Systems, Inc., http://www.optiwave.com

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