The etching is a method used to get rid of unwanted materials from an Si wafer. It is carried out immediately after the photolithography process. The etching is not selective. Thus, the need to trace the pattern onto the wafer using photoresist. There are two main types of etching, wet etching, and dry etching. In this article, we will discuss to you what you need to know about etching and its process.
The photoresist leaves a pattern on the Si wafer in the exact pattern of the mask. The hardened pattern is then cleaned using another chemical. This process is called wet etching.
Wet etching is a process that utilizes chemicals to get rid of unwanted material on a wafer's surface. The process is done in by batch which is good because this makes sits affordable and capable of etching multiple wafers at a time. The wafer is dipped into a pool of highly concentrated acid. Immediately, the exposed areas of the wafer are carved away. The only drawback of using this method is that it doesn't permit smaller complex geometries that are necessary for today's ICs and chips.
Dry etching is a process that utilizes gas, instead of chemical etchants, to remove unwanted materials on a wafer’s surface. What’s great about dry etching is that it is capable of generating very small critical geometries.
Plasma Etching is a process that utilizes gas that is put under an intense electric field to achieve a plasma state of matter. There are two different types of plasma etching based on the shape of the chamber used.
The gases are very reactive in their plasma form, providing very effective etching for the exposed wafer surface. It can also provide good critical geometry. The only drawback is that there’s a possibility of damaging the wafer from the RF radiation.
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