Method for manufacture of a multi-layer plate device

A method for the manufacture of a ceramic multi-layer plate device used as a plate in an electrostatic chuck, or in a heater, or other wafer support, used in semiconductor wafer processing, said method comprising the steps of:

• arranging a plurality of plate components into a stack, wherein said plurality of plate components comprise an upper plate layer, a lower plate layer, and an annular a brazing layer disposed between said upper plate layer and said lower plate layer between the outer periphery of said upper plate layer and said lower plate layer, thereby forming an inner space in said stack between said upper plate layer and said lower plate layer, wherein said upper plate layer comprises ceramic, wherein said lower plate layer comprises ceramic, and wherein said brazing layer comprises at least 89% aluminum by weight;
• placing said stack of plate components into a process chamber;
• removing oxygen from said process chamber;
• and
• joining said upper plate layer to said lower plate layer, wherein said step of joining said upper plate layer to said lower plate layer comprises the steps of:
• applying pressure between said upper plate layer and lower plate layer across said brazing layer;
• and
• heating the stack of plate components to a temperature between 800° C. and 1200° C., thereby joining said upper plate layer to said lower plate layer with a hermetically sealed joint which hermetically seals said inner space from an area exterior to said plate components, wherein the hermetically sealed joint has a vacuum leak rate of <1×10−9 sccm He/sec.