Chemical Mechanical Polishing (CMP) is a critical process in semiconductor manufacturing, specifically for producing Integrated Circuits (ICs). CMP combines chemical and mechanical methods to achieve a flat, smooth surface on semiconductor wafers, which is essential for depositing subsequent layers of material in multi-layered ICs. At Caplinq, we provide specialized materials and solutions that support the CMP process, ensuring the production of high-performance semiconductors.

What is the purpose of CMP?

In semiconductor fabrication, achieving flatness and precision is crucial. CMP helps planarize the wafer surface, ensuring each layer deposited is uniform and defect-free. This level of precision is vital when manufacturing ICs with multiple layers of material, as each layer needs to be perfectly smooth for the next to be accurately applied. Without proper planarization, surface anomalies can result in uneven deposition, leading to functional defects in the final product.

CMP provides several key benefits to the semiconductor manufacturing process:

• Flatness and Planarization: Essential for precise layer deposition, helping avoid variations in thickness and irregularities.

• Defect Reduction: Removes scratches, particles, and imperfections that could impact device performance and yield.

• Improved Lithography and Etching Yields: Planarized surfaces ensure better pattern transfer and consistent etching, even for fine lines under 0.5mm.

• Enhanced Device Reliability: Planarization eliminates electro-migration effects, reduces contact resistance, and prevents undesired contacts.

How does CMP work?

As the name suggests, Chemical Mechanical Polishing combines two methods of polishing to grind the wafer flat. For the chemical part of the process, a slurry made up of various chemicals is deposited onto the wafer. The mechanical part of the process is the rotation of the polishing pad onto the wafer. As the slurry is deposited, the wafer’s movement in combination with the abrasive properties of the slurry is what helps dissolve the wafer and allows for polishing.

What is the CMP Slurry made of?

CMP Slurries are usually made of an abrasive, like High Purity Alumina, water, and chemicals like oxidizing agents or acids which assist in the breakdown of the wafer. The abrasive does most of the heavy lifting and can vary in size and purity depending on application requirements. High Purity Alumina has extremely high hardness, which makes it very effective at grinding down the top layer of the wafer. It can also be processed to be very high purity, which means very few impurities will be introduced into the process. 

The High Purity Alumina that is used in CMP slurries is usually 5N purity, which means it is 99.999% pure. Semiconductor manufacturing has no room to add contaminants to the process, or else the finished products will have defects. This is why it is of utmost importance to use materials in the process that are as pure as possible. Below is a table of the different versions of 5N High Purity Alumina offered by Polar that can be used in Chemical Mechanical Polishing as well as other semiconductor applications.