Ultra Flat Wafers | How Is Wafer Quality Measured?


September 24, 2018

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Ultra flat wafers are just what they sound like. They are silicon wafers that are flatter than traditional ones. When it comes to wafer quality, especially with ultra flat wafers, several things are taken into consideration. Let’s take a look at how wafer quality is measured when it comes to ultra flat wafers.


One way in which wafer quality is measured is by the cleanliness of the wafer. Light point defects, or LPDs, are unwanted particles that are found on the surface of a wafer. The cleanliness quality is then determined by the total number of LPDs found across a certain area of a wafer.


Another way that wafer quality is determined is by the planarity. Planarity factors in the total thickness variation (TVV), warp, global total indicated reading (GTIR), and site TIR. The TVV determines the absolute difference in thickness between the thickest and thinnest parts of the wafer. The warp is used to figure out the difference between the minimum and maximum values of the wafer surface measured from a reference plane. GTIR is the maximum peak to valley deviation of a wafer from a given reference plane. Finally, site TIR is similar to GTIR except on smaller sites on the wafer.

Are You Looking for Ultra Flat Wafers?

At Wafer World, we have the wafers that you need no matter the size or use. If you are looking for wafers for your next project, including ultra flat wafers, contact us today to learn more or to place an order.

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