Negative Photoresists vs. Positive Photoresists: Which is Better for Your Application?

The photoresist is a material that is constantly worked with by semiconductor suppliers. This material with light-sensitivity is divided into 2 types: negative and positive, which react very contrarily when it’s exposed to UV light; so, understanding each reaction is critical in order to produce the most astonishing results in the manufacturing industry of semiconductor.

Photoresists That Are Negative:

Exposure to UV light causes the chemical structure of the photoresist to polymerize, which is the inverse of positive photoresists. Negative photoresists become tremendously tough to dissolve rather than becoming more soluble.

As a result, the exposed UV negative resist rests on the surface while the solution of photoresist developer removes the unexposed areas. This results in a mask with an inverse pattern of the original, which is then applied to the wafer.

Photoresists That Are Positive:

UV light is strategically directed at the material in the parts that the supplier of semiconductor means to eliminate with positive photoresists. When exposed to UV light, the chemical structure of the photoresist changes and it becomes more soluble in the photoresist developer.

The photoresist developer solvent is then used to wash away the exposed areas, revealing the underlying material. The photoresist developer cannot dissolve areas of the photoresist that have not been exposed to UV light. Working with positive photoresists in the semiconductor industry yields an identical copy of the pattern, which is exposed as a mask on the wafer.

Negative Photoresists vs. Positive Photoresists

Negative and positive photoresists are still used in the semiconductor manufacturing industry today, but positive photoresists are preferred by many semiconductor suppliers due to their higher resolution capabilities. Because the photoresist developer solvent does not permeate the areas that have not been exposed to UV light, positive photoresists retain their size and pattern. The solvent permeates both the UV- unexposed and exposed areas of negative resists, causing pattern distortions.

While positive photoresists appear to have the upper hand, negative photoresists aren't necessarily extinct. Negative resists are an excellent material for semiconductor supplies that do not require such high resolution. Negative photoresists, as opposed to positive photoresists, have a wider process latitude, faster photo speed, and a significantly lower cost of operation. Plus, negative photoresists are more adherent to certain substrate materials.

To learn more about the differences between Negative Photoresists and Positive Photoresists connect with the experts of A-Gas Electronic Materials and find out more today.