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Journal of Display Technology

Journal of Display Technology


  • Vol. 5, Iss. 4 — Apr. 1, 2009
  • pp: 126–132

Substrate Cleaning Methods for Fabricating OLEDs and Its Effect on Current Leakage Defect Formation

Masaru Nagai

Journal of Display Technology, Vol. 5, Issue 4, pp. 126-132 (2009)

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Various methods for cleaning the large glass substrates (300$\times$400 mm) used in organic light-emitting diode (OLED)fabrication processes were investigated. Horizontal roller-bed cleaning methods using a shower-rinse with megasonic (MS)-irradiation, or brush-scrubbing, were investigated for use with anode sputtering processes. Substrates were contaminated with particulate contaminants (0.3–0.5 particles/cm$^{2}$) generated from anode sputtering targets. Large particles (${\geq}5\ \mu$m) were easily removed with the MS irradiation (efficiency ${\geq}\hbox{95\%}$). Small particles (${<}{\hbox{3}}\mu{\hbox{m}}$) were harder to remove. The brush-scrubbing cleaning removed them with 80–90% efficiency, while the MS-irradiation cleaning had an efficiency of 60%–70%. Spin–rinse–dry cleaning methods using ozonized or electrolyzed cathode water were investigated for use with pre-organic deposition processes. Glass substrates were intentionally contaminated by exposing them to a clean room atmosphere for either 24 or 100 hours. The number of particles was reduced from around 0.4 to 0.03/cm$^{2}$ and from around 1.7 to 0.08/cm$^{2}$ by the MS-irradiation cleaning using de-ionized water alone, respectively. The effect of the ozonized water treatment was evident for the longer exposure substrates: it reduced the number of particles to 0.03. The electrolyzed-cathode water cleaning was successful in removing submicrometer size particles. We also investigated the effect of particulate contaminants on the current leakage defect formation.

© 2009 IEEE

Masaru Nagai, "Substrate Cleaning Methods for Fabricating OLEDs and Its Effect on Current Leakage Defect Formation," J. Display Technol. 5, 126-132 (2009)

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