Lithographically

Lithographically refers to the process of printing or manufacturing using lithography. Lithography is a method of printing and image reproduction where a flat surface, typically a stone or metal plate, is treated to be ink-repellent in some areas and ink-receptive in others. This difference in receptivity is created by chemical processes.

In its most traditional form, lithography relies on the immiscibility of oil and water. An image is drawn on a smooth, porous stone (like limestone) with a greasy or oily substance. The stone is then dampened with water, which adheres to the non-greasy areas. Ink, which is oil-based, is then rolled onto the stone. The ink adheres to the greasy image areas but is repelled by the water-covered non-image areas. Paper is then pressed against the stone, transferring the inked image.

In modern manufacturing, particularly in the semiconductor industry, lithography is a key process for transferring patterns onto silicon wafers. Photolithography is a common technique. A photosensitive material called photoresist is coated onto the wafer. A mask containing the desired pattern is placed between a light source and the wafer. Exposure to light through the mask causes chemical changes in the photoresist. The exposed or unexposed photoresist is then selectively removed, leaving a pattern on the wafer that can be further processed, such as by etching or deposition. This lithographically defined pattern is crucial for creating integrated circuits.