HERAEUS MATERIALS

HSQ 351 / 751

HSQ 351 and 751 are two varieties of flame fused quartz glass. HSQ 351 provides an exceptional material purity qualified for many semiconductor applications. For even more demanding applications, HSQ 751 offers significantly lower levels of aluminum, alkali and heavy metal impurities. Introduced by Heraeus in 1989, the flame fusion process is the oldest manufacturing process for quartz glass. The raw materials come from highly purified natural quartz sand.

CHEMICAL PURITY

Typical trace elements and OH content in quartz glass (ppm by weight oxide)

 
Elements Al Ca Cl Cr Cu Fe K Li Mg Mn Na Ti Zr OH Content
HSQ 351* 15 0.6 n.s. <0.05 0.07 0.2 0.7 0.4 0.1 0.05 0.8 1.1 1.1 175
HSQ 751* 8 0.5 n.s. <0.05 <0.06 0.2 <0.1 0.2 <0.05 0.05 <0.05 1.4 0.1 175

* Tubes made of these materials can be stabilized with a special surface treatment. Stabilization is achieved by including a thin (approx. 20 μm) uniform layer of cristobalite to form on the outer tube surface upon its first exposure to elevated temperature.


Characteristics HSQ 351

OH content 175 ppm

Products and applications HSQ 751

Diffusion barrier with highest purity requirements


Characteristics HSQ 351

OH content 175 ppm, higher purity

Products and applications HSQ 751

Diffusion barrier with highest purity requirements and low bubble content