What is an optical lithography?

Optical lithography is a chemical process that is usually used in the production of computer chips. Flat wafers, often made of silicon, are etched patterns for creating integrated circuits. Usually this process involves coating the plates in the chemical resistance material. The durability is then removed to detect the pattern of the perimeter and the surface is etched. The method of removal of resistance involves revealing the light of sensitive resistance to visible or ultraviolet (UV) light, where the term optical lithography came from.

The main factor in optical lithography is light. Like photos, this process involves exposing chemicals sensitive to light beams to form a patterned surface. Unlike photography, however, lithography usually uses focused rays of visible - or more common UV - light to create a pattern on a silicon plate. This viscous liquid creates a movie sensitive film on a wafer. There are two types of resistance, positive and negative. SpoilR dissolves in the developers in all areas where it is exposed to light, while negatively dissolves in areas that have been kept outside the light. In this process, a negative resistance is more often used because it is less likely that it is distorted in the development of developers than positive.

The second step in optical lithography is to detect light resistance. The aim of the process is to create a formula on the wafer so that the light is not evenly emitted throughout the wafer. Photongles, often made of glass, are usually used to block light in areas that developers do not want to expose. The lenses are also usually used to focus light on a particular mask area.

There are three ways to be used in optical lithography. First, the Against wafer can be pressed for light blocking directly. This is called contact printing . Defects on mask or wafers can allow light to the surface resistanceU, thus interfere with patterns.

Second, masks can be held in close proximity to wafers, but not touching. This process, called proximity printing , reduces interference from defects in the mask and also allows the mask to avoid any of the other wear -related wear. This technique can produce light diffraction between the mask and the wafer, which can also reduce the accuracy of the pattern.

The third and most commonly used technique for optical lithography is called projection print . This process sets a mask at a greater distance from the wafer, but uses the lenses between them to target light and reduce diffusion. The projection print usually creates the highest resolution formula.

Optical lithography includes two final steps after chemical resistance is exposed to light. Plates are usually washed with a developer solution to remove positive or negative resistance material. Then the wafer is usually etched in all areas where Odola jI do not cover. In other words, the material "resists" etching. This leaves parts of the elaborate wafers and other smooth.