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screen_manufacturing [2026/09/11 16:07] – [1. Array process] lucas.burlot.extscreen_manufacturing [2026/09/11 17:34] (current) – [1. Array process] lucas.burlot.ext
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 This repetitive process transfers precise circuit patterns from a photomask to the thin films deposited on the glass [(Bitard, Léa. Development of parametric model for Life Cycle Assessment of digital displays. 2025. EPFL, Master thesis)]. It begins with substrate cleaning to eliminate all contaminants from its surface, Next step involves coating the substrate surface with an adhesion promoter such as hexamethyldisilazane (HMDS), which improves bonding between substrate and photoresist (PR). A photoresist layer is uniformly coated with spinning, which is later on subjected to a pre-bake treatment (soft bake) in order to evaporate solvents and stabilize resist. In the next step, the photoresist is subjected to exposure to ultraviolet radiation using a patterned photomask. There occur chemical changes in the exposed areas of the photoresist. For a positive photoresist, the exposed regions become soluble and are removed during the development process, leaving behind the desired resist pattern. Post-baking (hard bake) is carried out in order to make the remaining photoresist strong and resistant to the upcoming processes. This hardened PR pattern acts as a protective mask during the etching process, where the exposed regions of the underlying thin film are removed[( Flay_Panel_Display_Manufacturing>[[https://www.wiley.com/en-es/Flat+Panel+Display+Manufacturing-p-9781119161363|Flat Panel Display Manufacturing, Jun Souk, Shinji Morozumi, Fang-Chen Luo, Ion Bita, 2018]])]. Finally, the remaining photoresist is stripped away (resist removal), leaving only the patterned thin-film layer on the substrate. Depending on the fabrication process, the patterned photoresist may also serve as a mask for ion implantation or doping instead of etching. This repetitive process transfers precise circuit patterns from a photomask to the thin films deposited on the glass [(Bitard, Léa. Development of parametric model for Life Cycle Assessment of digital displays. 2025. EPFL, Master thesis)]. It begins with substrate cleaning to eliminate all contaminants from its surface, Next step involves coating the substrate surface with an adhesion promoter such as hexamethyldisilazane (HMDS), which improves bonding between substrate and photoresist (PR). A photoresist layer is uniformly coated with spinning, which is later on subjected to a pre-bake treatment (soft bake) in order to evaporate solvents and stabilize resist. In the next step, the photoresist is subjected to exposure to ultraviolet radiation using a patterned photomask. There occur chemical changes in the exposed areas of the photoresist. For a positive photoresist, the exposed regions become soluble and are removed during the development process, leaving behind the desired resist pattern. Post-baking (hard bake) is carried out in order to make the remaining photoresist strong and resistant to the upcoming processes. This hardened PR pattern acts as a protective mask during the etching process, where the exposed regions of the underlying thin film are removed[( Flay_Panel_Display_Manufacturing>[[https://www.wiley.com/en-es/Flat+Panel+Display+Manufacturing-p-9781119161363|Flat Panel Display Manufacturing, Jun Souk, Shinji Morozumi, Fang-Chen Luo, Ion Bita, 2018]])]. Finally, the remaining photoresist is stripped away (resist removal), leaving only the patterned thin-film layer on the substrate. Depending on the fabrication process, the patterned photoresist may also serve as a mask for ion implantation or doping instead of etching.
  
-The pixel density of the screen (PPI) determines the pixel size thus the TFT channel width, finaly imposing a Photolitographi size. +The pixel density of the screen (PPI) determines the pixel size, thus the TFT channel width, finaly imposing a photolitographi size. 
- For exemple, an LTPS IPS LCD screen with a 2K4K resolution, 8" screen, has a PPI of 550, requires a TFT channel width of 1.5 μm, this was atchieved using an i-line (365 nm) photolithography[( A 550-PPI LCD using 1.5 µm channel width LTPS TFTs>[[https://sid.onlinelibrary.wiley.com/doi/abs/10.1002/jsid.405|Nakamura, T., Tada, M., and Kimura, H. (2015) A 550-PPI LCD using 1.5 µm channel width LTPS TFTs with low frame rate driving. Jnl Soc Info Display, 23: 580–586. doi: 10.1002/jsid.405.]])].+ For exemple, an LTPS IPS LCD screen with a 2K4K resolution, 8" screen, has a PPI of 550, requires a TFT channel width of 1.5 μm. This was achieved using an i-line (365 nm) photolithography[( A 550-PPI LCD using 1.5 µm channel width LTPS TFTs[[https://sid.onlinelibrary.wiley.com/doi/abs/10.1002/jsid.405|Nakamura, T., Tada, M., and Kimura, H. (2015) A 550-PPI LCD using 1.5 µm channel width LTPS TFTs with low frame rate driving. Jnl Soc Info Display, 23: 580–586. doi: 10.1002/jsid.405.]])].
  
 <figure center |photolithography> <figure center |photolithography>