Differences

This shows you the differences between two versions of the page.

--- screen_manufacturing [2026/06/05 23:41] – [1. TFT matrix (only for Active Matrix (AM) displays)] sophie
+++ screen_manufacturing [2026/07/06 17:04] (current) – [4. Module process] yusufabdillah
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 Once the glass substrates are ready, the next step depends on the kind of thin film transistor (TFT) backplane technology that is being employed. The TFT backplane acts as the electronic control layer of the display and regulates individual pixels. There are several types of TFT backplanes such as amorphous silicon (a-Si), indium gallium zinc oxide (IGZO), low-temperature polysilicon (LTPS), and low-temperature polyoxide (LTPO).
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 ## Glass substrate fabrication
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 ### 1. Array process
-In the TFT array process, the process includes glass cleaning, gate metal sputtering, PECVD, photolithography, source:drain etching, and ITO pixel electrode.
+In the TFT array process, the active transistor circuit is created on one glass substrate. It will later control the pixels electrically, and therefore it has the gate lines, data lines, thin-film transistors, storage capacitors, and pixel electrodes. The array process includes glass cleaning, gate metal sputtering, PECVD, photolithography, source/drain etching, and ITO pixel electrode.
 #### Glass Cleaning
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 #### Photolithography
-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 cleaning and the application of an adhesion promoter like HMDS before coating the substrate with a photoresist (PR). The PR is hardened through pre-baking and then exposed to UV light through a patterned mask. A developer solution subsequently dissolves portions of the PR to reveal the desired layout. This hardened PR pattern acts as a mask for the underlying film during subsequent etching or ion doping [( 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]])].
+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.
 <figure center |photolithography>
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 \\
 ### 4. Module process
-#### Polarizer Lamination
+#### Polariser Lamination
-Flexible linear polarizer sheets are attached to the outer surfaces of the assembled LCD cell. These films transmit light of a specific polarization axis while absorbing orthogonal components to modulate display brightness. These polarizer films are made from an oriented PVA film containing iodine dye, which is then laminated between two TAC layers. It is essential that the direction of polarization is carefully controlled to align with the direction of orientation of the LC cells.
+Flexible linear polariser sheets are attached to the outer surfaces of the assembled LCD cell. These films transmit light of a specific polarization axis while absorbing orthogonal components to modulate display brightness. These polariser films are made from an oriented PVA film containing iodine dye, which is then laminated between two TAC layers. At the very surface, a protective film is applied to avoid any mechanical damage during handling and operation. Below this protective film, there is an additional functional film which can be any type like AG (Anti-Glare), LR (Low Reflection), AR (Anti-Reflection), or HC (Hard-Coat). The back side has an adhesive film that adheres the polariser with LCD cell, whereas a release film covers this adhesive film before installation. It is essential that the direction of polarisation is carefully controlled to align with the direction of orientation of the LC cells.
 <figure center |polarizer lamination>
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 ## OLED screen manufacturing
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 In this section, we chose to focus on the manufacturing processes of the most common OLED screen types. These choices are based on a screen market analysis, detailed in [[screen_market|this dedicated page]]
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-cc ### 1.  TFT matrix (only for Active Matrix (AM) displays)
+### 1.  TFT matrix (only for Active Matrix (AM) displays)
 For Active Matrix OLED (AMOLED), a TFT matrix matric is constrcucted on the [[screen_manufacturing#glass_substrate_fabrication|glass substrate]]. [[intro_screen#transistor_technologies |LTPS TFT]] technology is used for small and medium-sized screens, and [[intro_screen#transistor_technologies |IGZO TFT]] technology for larger ones. These technologies are explained in [[screen_manufacturing#transistor_technology | this section ]]. An AMOLED device needs two TFTs :  the **switching TFT** store the data signal in storage capacitor to
 provide a voltage without time loss, and the **driving TFT** delivers current modulated by the signal voltage to the pixel for light emission [(Flay_Panel_Display_Manufacturing)].
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 </figure>
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 ### 2.  Color filter fabrications (only for displays based on white OLED)
 via photolithography [( 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]])]
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 </figure>
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 ### 3. Over coat layer
 The overcoat layer is formed for three purposes[( 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]])]:
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 </figure>
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 ### 4. Pixel fabrication
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 The processes used for deposition of the cathode are either **vacuum thermal evaporation combined with an FMM** (Fine Metal Mask)[([[https://advanced.onlinelibrary.wiley.com/doi/epdf/10.1002/aelm.202500555|Vacuum Thermal Evaporation for OLEDs: Fundamentals, Optimization, and Implications for Perovskite LEDs]])] for small displays, or **vacuum thermal evaporation with open mask** for large displays.
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 ### 5. Encapsulation