CMP Polishing: Process and Techniques

We're very lucky that silicon turned out to be such a useful material. We could've found that a less plentiful substance had abilities like silicon's. Instead, silicon has the abilities it does and it makes up 90% of the earth's crust

Still, silicon's usefulness only goes so far. A good chunk of what makes silicon so useful is based on the efforts of silicon wafer manufacturers. One of their most important processes is CMP polishing. 

Would you like to learn more about CMP and the techniques used for it? If so, read on. 

What Is the CMP Polishing Process? 

The chemical mechanical polishing process grinds the surface of silicon wafers down. Silicon wafers must be this thin to function properly in devices. Any particles or imperfections can make it hard for electronic device components to fit together. 

If wafer manufacturers don't polish their wafers like this, they can run into several problems. One issue is that the chip may not fit into the thin body of a certain device. Another issue is that unpolished chips have poorer heat dissipation. 

So how do CMP facilities perform these tasks? You can learn more about this in the sections below: 

Setting Up the CMP Machine 

Workers don't perform the CMP wafer cleaning process by hand. Rather, a machine takes on that responsibility. However, workers still need to set up the machine properly before it can start a polishing session. 

Workers are also responsible for placing each prepared silicon wafer on the part of the machine known as the polishing head. After this, they turn the machine on. 

Polishing Process 

Once the machine is on, it will perform a few tasks. The polishing head will bring the wafer over to a polishing pad. The machine should have already poured out a chemical etching slurry onto the polishing pad. 

The polishing pad will spin under the silicon wafer. In addition, the polishing head will move back and forth across the pad. 

Some Different CMP Techniques 

Not all CMP polishing processes are the same. Workers often switch up the different factors of the processes to get different results. Here are some of the things that can change: 

The CMP Slurry 

The CMP slurry is responsible for the chemical etching process. This process eliminates the surface defects that mechanical abrasion can leave behind. By changing the size and distribution of the abrasive particles, workers can change how the slurry affects the surface of the wafer. 

The Polishing Pad 

The polishing pad, which handles the mechanical abrasion process, controls how thin a wafer gets. By using different grits, workers can change how thin or thick a wafer gets. 

Test Wafers 

Workers will also use test wafers to test their pad and slurry mix. By doing this, they ensure no damage comes to prime wafers. 

Try Our Patterned Silicon Test Wafers

So CMP polishing is a fairly simple process on the surface. However, workers have to be careful with the slurry and polishing pad type used. 

Are you unsure if you're using the right tools? Our patterned silicon test wafers help you test your process before using real silicon wafers. Request information about our custom patterned test wafers on this page

Published August 21, 2023.