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Wide dynamic range CMOS pixels with reduced dark current

  • Bhaskar ChoubeyEmail author
  • Steve Collins
Article

Abstract

The sensitivity of logarithmic pixels at low light levels is limited by the dark current that flows through the load transistor in the pixel in addition to the photocurrent. This dark current also degrades the performance of cameras containing these pixels by increasing the residual fixed pattern noise following fixed pattern noise correction. The performance of logarithmic pixels will therefore be improved if the dark current can be reduced. A review of the sources of dark current has led to the design of a new layout for a logarithmic pixel. Results are reported that show that this layout significantly reduces the dark current in the pixel. In addition, a simple change to the bias voltages applied to the proposed pixel means that the new layout can simultaneously exhibit a linear response at low light levels and a logarithmic response at higher light levels. Experimental results from both modes of operations are presented.

Keywords

Wide dynamic range pixels Dark current Logarithmic pixels Fixed pattern noise Layout Guard ring Linear response Logarithmic response 

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References

  1. 1.
    Joseph, D., & Collins, S. (2001). Modelling, calibration and correction of illumination-dependent fixed pattern noise in logarithmic CMOS image sensor. IEEE Transactions on Instrumentation and Measurement, 55(5), 996–1001.Google Scholar
  2. 2.
    Choubey, B., Otim, S., Aoyama, S., Joseph, D., & Collins, S. (2006). An electronic calibration scheme for logarithmic CMOS image sensor. IEEE Journal of Sensors, 6(4), 950–956.CrossRefGoogle Scholar
  3. 3.
    Shcherback, I., Belenky, A., & Yadid-Pecht, O. (2002). Empirical dark current modelling for CMOS active pixel sensor. Optical Engineering, 41(6), 1216–1219.CrossRefGoogle Scholar
  4. 4.
    Shockley, W., & Read, W. (1952). Statistics of recombination of holes and electrons. Physical Review, 87(5), 835–842.zbMATHCrossRefGoogle Scholar
  5. 5.
    Sze, S. M. (2001). Semiconductor devices - Physics and technology (2nd ed.). John Wiley & sons.Google Scholar
  6. 6.
    Inoue, I., Tanaka, N., Yamashita, H., Yagamuchi, T., Ishiwata, H., & Ihara, H. (2003). Low-leakage-current and low-operating-voltage buried photodiode for a CMOS imager. IEEE Transactions on Electron Devices, 50(1), 43–47.CrossRefGoogle Scholar
  7. 7.
    Loukianiva, N. V., Folkerts, H. O., Mass, J. P. V., Verbugt, D. W. E., Mierop, A. J., Hoekstra, W., Roks, E., & Theuwissen, A. J. P. (2003). Leakage current modeling of test structures for characterization of dark current in CMOS image sensors. IEEE Transactions on Electron Devices, 50(1), 77–84.CrossRefGoogle Scholar
  8. 8.
    EerNisse, E. P. (1979). Stress in thermal SiO2 during growth. Applied Physics Letters, 35(1), 8–10.CrossRefGoogle Scholar
  9. 9.
    Ha, D., Cho, C., Shin, D., Koh, G. H., Chung, T. Y., & Kim, K. (1999). Anomalous junction leakage current induced by STI dislocations and its impact on dynamic random access memory devices. IEEE Transactions on Electron Devices, 46(5), 940–946.CrossRefGoogle Scholar
  10. 10.
    Kwon, H. I., Kang, I. M., Park, B. G., Lee, J. D., & Park, S. S. (2004). The analysis of dark signals in the CMOS APS imagers from the characterization of test structures. IEEE Transactions on Electron Devices, 51(2), 178–184.CrossRefGoogle Scholar
  11. 11.
    Scott, S. R. (1990). Oxidation-induced defect generation in advanced DRAM structures. IEEE Transactions on Electron Devices, 37(5), 1253–1287.CrossRefGoogle Scholar
  12. 12.
    Kwon, H. I., Kwon, O. J., Shin, H., Park, B. G., Park, S. S., & Lee, J. D. (2004). The effects of deuterium annealing on the reduction of dark currents in the CMOS APS. IEEE Transactions on Electron Devices, 51(8), 1346–1349.CrossRefGoogle Scholar
  13. 13.
    Lee, J. I. (2005). Method of manufacturing image sensor for reducing dark current. US Patent no. 6838298.Google Scholar
  14. 14.
    Wu, C. H., Zhao, T., & He, X. (2005). Surface passivation to reduce dark current in a CMOS image sensor. US Patent no. 6909162.Google Scholar
  15. 15.
    Lee, H. S., & Fife, K. G. (2005). CMOS pixel design for minimization of defect-induced leakage current. US patent no. 6881992.Google Scholar
  16. 16.
    Chandra, M., & Rhodes, H. (2005). Method of forming photodiode with self-aligned implants for high quantum efficiency. US Patent no. 6969631.Google Scholar
  17. 17.
    Merril, R. B. (2000). CMOS image sensor employing silicide exclusion mask to reduce leakage and improve performance. US Patent no. 6160282.Google Scholar
  18. 18.
    Yaung, D. N., Wuu, S. G., & Fang, Y. K. (2001). Non-silicide source drain pixel for 0.25-µm CMOS image sensor. IEEE Electron Devices Letters, 22(2), 71–73.CrossRefGoogle Scholar
  19. 19.
    Lee, T. H., Guidash, R. M., & Lee, P. P. (1991). Partially pinned photodiode for solid state image sensors. US Patent no. 5903021.Google Scholar
  20. 20.
    He, X., Wu, C. H., & Zhao, T. (2002). Active pixel having reduced dark current in a CMOS image sensor. US Patent no. 6462365.Google Scholar
  21. 21.
    Chan, C. L. (2002). Invention for reducing dark current of CMOS image sensor with new structure. US Patent no. 6495391.Google Scholar
  22. 22.
    Berezin, V., Ovsiannikov, I., Jerdev, D., & Tsai, R. (2003). Dynamic range enlargement in CMOS imagers with buried photodiode. In IEEE Workshop on CCD and AIS.Google Scholar
  23. 23.
    Berezin, V., & Fossum, E. R. (2002). Active pixel sensor with fully-depleted buried photoreceptor. US Patent no. 6388243.Google Scholar
  24. 24.
    Dierickx, B. (2004). Buried, fully depletable, high fill factor photodiodes. US Patent no. 6815791.Google Scholar
  25. 25.
    Maeda, A., & Sakakibara, K. (2003). Semiconductor device having a solid-state image sensor. US Patent no. 6566678.Google Scholar
  26. 26.
    Lee, J. I. (2005). Method for manufacturing CMOS image sensor using spacer etching barrier film. US Patent no. 6974715.Google Scholar
  27. 27.
    Wu, C. Y., Shih, Y. C., Lan, J. F., Hsieh, C. C., Lu, J. H. (2004). Design, optimization and performance analysis of new photodiode structures for CMOS active pixel sensor (APS) imager applications. IEEE Journal of Sensors, 4(1), 135–144.CrossRefGoogle Scholar
  28. 28.
    Han, J. S. (2003). Image sensor capable of decreasing leakage current between diodes and method for fabricating the same. US Patent no. 6545302.Google Scholar
  29. 29.
    Okita, A., & Suzuki, S. (2002). Photoelectric transducer and imaging device. Japanese Patent publication no. 2002-353430.Google Scholar
  30. 30.
    Shunzai, C. (2004). Photodiode structure. Japanese Patent no. 3583702.Google Scholar
  31. 31.
    Tiemin, X., He, X., & Chen, D. (2002). Optimized floating P+ region photodiode for a CMOS image sensor. US Patent no. 6486521.Google Scholar
  32. 32.
    Pan, J. H., & Chen, M. I. (2001). Method of manufacturing photodiode CMOS image sensor. US Patent no. 6329233.Google Scholar
  33. 33.
    Yang, S. H. (2003). Method of reducing leakage current of a photodiode. US Patent no. 6569700.Google Scholar
  34. 34.
    Mann, R. (2003). Improved semiconductor device for isolating a photodiode to reduce junction leakage and method of formation. International Patent no. WO 03/019675 A1.Google Scholar
  35. 35.
    Rhodes, H. E., Juengling, W., Figura, T. A., & Cummings, S. D. (2005). Low leakage diodes, including photodiodes. US Patent no. 6486521.Google Scholar
  36. 36.
  37. 37.
    Choubey, B., Joseph, D., Aoyama, S., & Collins, S. (2006). Dark current reductions techniques for wide dynamic range logarithmic CMOS pixels. In 30th International Congress of Imaging Science.Google Scholar
  38. 38.
    Sugiyama, M., & Tashiro, T. (2000). Semiconductor photodiode and a method for fabricating the same. US Patent no. 6080600.Google Scholar
  39. 39.
    Kopley, T. E., Vook, D. W., & Dungan, T. (2002). Method of manufactering a structure for reducing leakage currents by providing isolation between adjacent regions of an integrated circuits. US Patent no. 6417074.Google Scholar
  40. 40.
    Cheng, H. Y., & King, Y. C. (2002). An ultra low dark current CMOS image sensor cell using n+ ring reset. IEEE Electron Devices Letters, 23(9), 538–540.CrossRefGoogle Scholar
  41. 41.
    Fox, E. C., Hynecek, J., & Dykaar, D. R. (2000). Wide dynamic range pixel with combined linear and logarithmic response and increased signal swing. In IS&T/SPIE 12th International Symposium on Electronic Imaging-Sensors and Camera Systems for Scientific, Industrial, and Digital Photography Applications, volume 3965 of Proceedings of SPIE, pages 4–10. SPIE.Google Scholar

Copyright information

© Springer Science+Business Media, LLC 2007

Authors and Affiliations

  1. 1.Department of Engineering ScienceUniversity of OxfordOxfordUK

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