Multi-zone silicon nitride wafer heater assembly having corrosion protective layer, and methods of making and using the same

A wafer heater assembly, the assembly comprising:

• a heater substrate comprising nitride including at least one heating element embedded therein, the heater substrate having a first surface;
• and
• a non-porous outermost layer proximal the first surface of the heater substrate, the non-porous outermost layer comprising a rare earth disilicate, wherein the rare earth disilicate comprises ytterbium disilicate (Yb2Si2O7);
• wherein the non-porous outermost layer comprises an exposed surface and a second surface, wherein the exposed surface is configured to contact a wafer for heating, and wherein the second surface faces the first surface of the heater substrate;
• and
• wherein the non-porous outermost layer realizes a Keiviite 001 peak intensity and a Keiviite 020 peak intensity, wherein the Keiviite 001 peak intensity is less than 95% of the Keiviite 020 intensity when tested using a theta-theta x-ray diffractometer, copper tube operated at 40 kV;
• and
• wherein the wafer heater assembly is configured for use in fabricating semiconductor chips and for in-situ cleaning with halogen gases.