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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.
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GE 214 LD
GE 214 LD is the large diameter grade industry standard tubing. For all but highly specialized operations, this low cost tubing offers the levels of purity, sag resistance, furnace life and other properties that diffusion and CVD processes require.
For superior performance at elevated temperatures, GE 214 LDH furnace tubing gives process engineers a better balance between the effects of higher temperatures and heavier wafer loads.
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Description
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Typical Application
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Clear fused quartz with the same excellent properties as GE 214 but for large diameter applications.
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Used by the semiconductor industry for diffusion, oxidation and LPCVD processing.
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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.
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Description
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Typical Application
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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.
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Used in critical semiconductor diffusion systems where even trace levels of alkali content can reduce chip yields.
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GE 244 LD - Low Alkali/Low Aluminum Quartz Tubing
This grade has been specially developed for quartz users concerned about the aluminum level in fused quartz. GE 244 LD has a typical aluminum level of 8 ppm.
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GE 214 Bell Jar Body
Certain pieces of semiconductor process equipment require a quartz bell jar for the process chamber. Momentive Performance Materials makes a selected list of standard bell jar bodies and blanks that can be used by fabricators of finished bell jars. With this bell jar body, fabricators can add a top and bottom flange to make a high quality finished product.
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514/544 Opaque Rings
A common practice in fabricating high temperature process chambers is to add a cross-section of opaque quartz to the tube used to form the chamber. The opaque quartz ring used to form the cross-section, blocks IR energy traveling the length of the tube wall (commonly called light piping). Blockage of this IR energy is important to protect the o-ring seal used to seal the chamber. Momentive Performance Materials makes opaque rings in standard 514 purity (equivalent to GE 214 tubing) and GE 544 purity (equivalent to GE 244 tubing). These rings make a cost effective alternative to other methods of forming opaque rings. Sizes are generally available for all standard process chambers.
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Low Hydroxyl (OH)-
One reason that Momentive Performance Materials fused quartz tubing can withstand the wide thermal gradients and chemical environments of wafer processing operations is its (OH)- content of less than 10 ppm water in most grades. Low (OH)- minimizes the sag rate at diffusion temperatures, and effectively retards the progress of devitrification. Because of its low hydroxyl content, Momentive Performance Materials tubing does not require special coatings that could potentially release contaminants at elevated temperatures.
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