Fotolitográfia

Fotolitografía, also known as photolithography, is a process used in microfabrication to selectively pattern thin films on a substrate. It is a key technique in the manufacturing of integrated circuits, microelectromechanical systems (MEMS), and other microdevices. The process relies on the use of light to transfer a geometric pattern from a photomask onto a light-sensitive chemical, known as a photoresist, coated on the substrate.

The basic steps involved in fotolitografía include preparing the substrate, applying a photoresist layer, exposing the photoresist to light through a photomask, developing the photoresist to remove either the exposed or unexposed areas, and finally etching or depositing material on the patterned areas. The photomask contains the desired pattern and acts as a stencil. When light passes through the mask, it selectively illuminates the photoresist.

There are two main types of photoresists: positive and negative. With a positive photoresist, the areas exposed to light become soluble and are removed during development, leaving the unexposed areas intact. Conversely, with a negative photoresist, the exposed areas become insoluble and remain after development, while the unexposed areas are removed.

After the photoresist has been patterned, the substrate is subjected to further processing, such as etching, where material is removed from the exposed areas, or deposition, where new material is added to the patterned areas. Finally, the remaining photoresist is stripped away, leaving the desired pattern on the substrate. The resolution and accuracy of fotolitografía depend on factors like the wavelength of light used, the quality of the photomask, and the properties of the photoresist.