In the semiconductor industry, a combination of high purity and excellent high temperature properties make fused quartz tubing an ideal furnace chamber for processing silicon wafers. The material can tolerate the wide temperature gradients and high heat rates of the process. Its high purity creates the low contamination environment required for achieving superior wafer yields.
The stringent requirements of today’s advanced semiconductor processes demand continued advancement in materials used in the process chamber. These developments have impacted heavily on quartz producers, requiring both larger tube diameter developments and significantly higher levels of purity. Momentive Performance Materials has responded on both counts.
Quartz tubing is available in a full range of sizes, including diameters up to 550mm. Diameter and wall thickness dimensions are tightly controlled. Special heavy wall thicknesses are available on request. By finding new and better sources of raw material, expanding and modernizing production facilities, and upgrading quality control functions, Momentive Performance Materials has reduced contaminant levels in its fused quartz tubing to less than 25 ppm, with alkali levels below 1 ppm.
GE 224 LD – Low Alkali Quartz Tubing
As the semiconductor industry moves toward higher density devices, furnace atmosphere contamination becomes an increasingly critical factor in controlling wafer yields. One potential contaminant is sodium, which occurs naturally in the silica sand used to make fused quartz. If not removed, this highly mobile ion can effectively destabilize the electrical characteristics of MOS and bipolar devices.
For these critical applications, Momentive Performance Materials has developed GE 224 low alkali fused quartz tubing. It is made in a special process that eliminates up to 90% of the naturally occurring alkalis. The process achieves a typical sodium level of 0.1 ppm (vs. a normal 0.7 ppm) greatly reduces potassium, and virtually eliminates lithium.
Similar to GE 214 with the same exceptional high viscosity and visual standards. Special methods are used to reduce alkali content to the PPB range.
Used in critical semiconductor diffusion systems where even trace levels of alkali content can reduce chip yields.