depositionandetchback

Deposition and etchback is a subtractive patterning technique used in semiconductor fabrication and other microfabrication processes. It combines two fundamental steps: deposition of a material, often a resist or a sacrificial layer, followed by the selective removal of both the deposited material and underlying material through an etching process. This allows for the creation of intricate patterns on a substrate.

The process typically begins with depositing a blanket layer of material over the entire surface. This deposited layer is then patterned using a lithographic technique, such as photolithography, where a mask is used to expose specific areas to radiation. Following lithography, an etching step is employed. This etch removes the exposed portions of the deposited layer, and crucially, also removes the underlying material in those same exposed areas. The unexposed portions of the deposited layer act as a protective mask, preventing the underlying material from being etched.

After the etchback step, the remaining portions of the deposited layer are removed, leaving behind the patterned underlying material. This technique is versatile and can be used to pattern various materials, including photoresists, dielectrics, and metals, depending on the specific application. It is particularly useful for creating fine features and for processes where a direct etch of a desired material might be difficult or lead to poor selectivity.