MATERIAL SELECTION GUIDE

There are two different type of quartz material to choose from, Fused Quartz and Fused Silica.

FUSED QUARTZ

Naturally occurring crystalline (sand) is crushed into powder and passes through numerous purifying processes. The resulting pure powder is fused by either of two different processes to manufacture clear fused quartz ingots.

Electrically fused:

High energy electrical heating process melts (fuses) the powder, casting very large ingots which will be cut up during fabrication. The result of this process is a fairly pure material with a very low (~15ppm) Hydroxyl (OH) content, however, it contains some fine bubbles, inclusions, and a minute amount of other contaminants. Currently, this is the most widely used material in the semiconductor industry, however, it is less desirable for quartz wafers except in particular application where the OH content and the electrical properties and dielectric constant is in consideration.

Flame Fused:

In this manufacturing process, the powder is fused with an Oxygen-Hydrogen flame. This clear fused quartz material is extremely pure and virtually bubble-free. However, the OH content is somewhat higher (~180ppm) than the electrically fused quartz. This material is appropriate for almost all wafers but the most demanding optical and semiconductor grade applications.

FUSED SILICA

The manufacturing of this form of Silicon Dioxide does not use naturally occurring material but is derived synthetically, hence the name Synthetic Quartz. There are two different ways this material is produced.

Flame fused:

In this process, particular chemicals are fused with an Oxygen-Hydrogen flame. This material processing method involves various drying processes, thus numerous grades are available with OH content ranging from 180ppm to as high as 1200ppm. The OH content affects the maximum processing temperature for the wafer so this parameter should be carefully evaluated.

Dry VAD process:

This process to manufacture synthetic quartz is one of the most advanced and sophisticated methods available today. This method produces the highest grade material to date. The extremely low OH content (<2ppm) allows for very high wafer processing temperatures among other notable benefits. The optical characteristics are the highest grade but also the most expensive.

Additional information on our quartz wafers:

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