ClearlySapphire.com


 

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Fabrication

Commercial sapphire is delivered in multiple forms factors – from rough cores cut from crystal boules to polished and unpolished wafers to finished products.  Some manufacturers receive intact cores which are later sliced into wafers, while others receive wafers that are polished or ground, depending on their final use.

 

The sapphire boules produced by crystal growth processes are typically smooth, rounded, roughly cylindrical mounds, yet they are crystals with precise, defined planes of orientation.  Just as a gemstone is fashioned with intricate cuts coinciding with its planes, sapphire boules all have known planes.  The end products exploit the various physical, optical and electrical properties of these unique planes.

 

Fabrication begins with an inspection using polarized light and magnification to identify imperfections and microscopic deposits within the boule.  These imperfections dictate the size, location and orientation of the available cores to be extracted.  Once The inspected boule is marked to cut cores from which wafers will be produced. 

 

The process of extracting the cylindrical cores begins with a boule being securely mounted, and X-ray equipment is used to ensure proper crystal plane orientation before a diamond blade saw is used to drill the cores.

 

To produce wafers, the extracted sapphire cores are mounted onto metal beams using a precision alignment tool to achieve a target angle.  Proper alignment helps achieve the desired characteristic of wafers such as total thickness variation and warp (think of a potato chip).  Wafer thickness varies based on customer/application requirements.  The cores are sliced into thin wafers using a mechanical wire saw with a loose abrasive slurry.

 

The cut wafers are polished in a multi-step process, and are either shipped as “ground wafers” or polished “Epi Ready” wafers, which are ready for semiconductor materials to be grown on them.  High speed rotating diamond wheels are used to grind the edge of the wafers to provide a better rounding end to the products.