scott, I guess that you have learned the hard way that a single crystal of
aluminum oxide has pretty poor thermal shock resistance and exhibits brittle
fracture.  That is because the thermal conductivity of aluminum oxide is less
than that of silicon, both exhibiting brittle fracture. You simply have to raise
the temperature of the material more slowly so that large temperature
differentials are not set up, giving rise to enormous stresses that can
obviously shatter the material.  Gary
---- General MEMS discussion  wrote:
>
> Hi,
>
> I recently had a 100mm sapphire wafer crack shortly after it was placed
> on a 350C PECVD platen.  From google it appears there is some increased
> risk with sapphire compared to silicon wafers.   Does anyone have some
> direct experience with handling sapphire wafers who could give me some
> pointers, or was I just unlucky?  (Is scribing a bigger problem than for
> silicon, can they handle hot plate dehydration bakes, etc)  Thanks