Photoresist Use In Semiconductor Manufacturing

Those who are a part of the electronic industry know the importance of photoresists as this light-sensitive material is used in photoengraving and photolithography to form a pattern on the membrane. The devices you love to use like mobile phones, computers, tablets etc have silicon wafer which undergoes numerous procedures before the final product is achieved and one of the processes that make it happen is photolithography in which photoresists is used.

What is a photoresist?

It is a light-sensitive material composed of a solvent, polymer and sensitizer which turns into a soluble material when exposed to ultraviolet light. The exposed areas are then dissolved using a solvent and thus a pattern is left behind. The primary function of photoresists is targeted towards precise pattern formation and protection of the substrate from any kind of chemical attack during etching. Photoresists can either be positive or negative. In the positive photoresists, the photochemical reaction during exposure weakens the polymer and makes it more soluble to the developer, thus forming a positive pattern. The mask has an exact copy of the pattern which remains as a stencil for further processing. On the other hand, negative photoresists contain the photographic negative or the inverse of the pattern that has to be transferred.

What is the use of photoresists in semiconductor manufacturing?

Technological advances have brought in the massive use of photoresists in semiconductor manufacturing. The reason is the shelf life, cost, resolution, etching resistance, purity, sensitivity and availability of the photoresists. Photolithography which refers to semiconductor lithography is the process of transferring geometric patterns to a substrate. There are numerous steps involved in this procedure which ultimately culminate into a silicon wafer product that is fit for use. These steps can be briefed as:

• The substrate or wafer is extensively cleaned to remove all kinds of impurities which can affect the adhesion of the patterns.
• After this, silicon oxide that acts as a barrier layer is applied to the surface of the wafer so that the photoresist can be applied at the next stage.
• Spin coating method is used to apply photoresist so that the surface is even.
• After this, the soft-baking process removes the solvents from the photoresist coating and thus makes the photoresist open to photo-imaging
• Once this is done, the photoresist is dried and mask alignment and exposure thus follow.

For more information and details on the use of photoresists in semiconductor manufacturing, visit to www.agasem.com.