How Are Silicon Wafers Polished?


June 27, 2022

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Silicon wafer polishing is the last step in the fabrication process. It gets the double-side polish wafer ready to become the substrate of the resulting chip that will be rolled out to customers.

a double side polish wafer

Why Do You Polish Silicon Wafers?

Polishing reduces the silicon wafer’s thinness and makes the semiconductor flat. The modern world’s applications for silicon wafers require specific thinness and flatness. These applications include mobile devices, which are significantly smaller than computers or solar panels.

Second, the wafer production process could result in minor imperfections that could affect the final product’s performance. These flaws could also make the wafer break when subjected to physical stress. Polishing removes these defects effectively and ensures no other particles get trapped on the smooth surface.

Polishing also helps in making manufacturing more efficient and less costly. Fabrication teams can create more from a single silicon rod by producing thin wafer slices.  

A Look at the Double Polishing Process

There are two types of wafer polishing: single-side and double-side polishing. This article will examine double-side polishing (DSP) and how it works.  

Three materials are involved: the polishing pads, polishing agent or slurry, and a carrier wafer.

Carrier Wafer

The carrier wafer is the substrate that protects the production wafer from damage during the polishing process. It can be made of silicon or glass. Technicians bond the wafer to the carrier before mounting it between the two polishing pads. The wafers can be connected either temporarily or permanently.

Polishing Agent Slurry

Wafer polishing uses chemical mechanical planarization (CMP) slurries. These substances contain abrasives made from fine metal oxides like silicon dioxide, aluminum oxide, iron (3) oxide, and cerium (4) oxide.  

Slurries come in powder form and are mixed with water before being applied to the surface of the polishing pads. A distribution system keeps the polishing pads supplied with slurry while the polishing is ongoing.  

Polishing Pads

The CMP pads are the surfaces that make direct contact with the wafers. Rapid spinning movement and abrasive slurry combine to help the pads scrape away flaws and protrusions in the wafers. The pads also remove excess wiring and ensure the circuits’ smoothness in the finished product.

a worker handling a double side polish wafer

Take a Look at Our Double Side Polish Wafers

We offer both single-side and double-side polished wafers. For a quote, you can contact us now with your specifications.

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