Method for hermetically joining plate and shaft devices including ceramic materials used in semiconductor processing
A method for the joining of ceramic pieces with a hermetically sealed joint comprising brazing a continuous layer of joining material between the two pieces. The wetting and flow of the joining material is controlled by the selection of the joining material, the joining temperature, the time at temperature, the joining atmosphere, and other factors. The ceramic pieces may be aluminum nitride and the pieces may be brazed with an aluminum alloy under controlled atmosphere. The joint material is adapted to later withstand both the environments within a process chamber during substrate processing, and the oxygenated atmosphere which may be seen within the shaft of a heater or electrostatic chuck.
1. A method for joining a hollow heater shaft to a heater plate for a heater used in semiconductor processing, said method comprising the steps of:
placing a brazing element between an interface area of said hollow heater shaft and an interface area of said heater plate, thereby creating a joining pre-assembly, wherein said hollow heater shaft and said heater plate comprise aluminum nitride, and wherein said brazing element comprises at least 99% aluminum by weight;
placing said joining pre-assembly in a process chamber;
removing oxygen from said process chamber; and
heating said joining pre-assembly after removing the oxygen from the process chamber, thereby joining said hollow heater shaft to said heater plate with a joint which hermetically seals an interior space of said hollow heater shaft from an exterior of said hollow heater shaft through said joint, wherein the step of heating the joining pre-assembly comprises heating the joining pre-assembly to a first temperature between 800 C and 1200 C, and wherein said joint joins between an aluminum nitride surface of said hollow heater shaft and an aluminum nitride surface of said heater plate.
2. The method of claim 1 further comprising the steps of:
heating the joined shaft and plate assembly to temperature above 540 C; and
disjoining the joint between said device shaft and said device plate.
3. The method of claim 1 wherein the step of removing oxygen comprises applying vacuum to the process chamber wherein said pressure is lower than 1×10E-4 Torr.
4. The method of claim 1 wherein the step of removing oxygen from said shaft and plate pre-assembly during the heating step comprises filling said process chamber with pure, dehydrated inert gas.
5. The method of claim 1 wherein the step of removing oxygen from said shaft and plate pre-assembly during the heating step comprises filling said process chamber with purified hydrogen.
6. A method for joining a hollow electrostatic chuck shaft to a electrostatic chuck plate for an electrostatic chuck used in semiconductor processing, said method comprising the steps of:
placing a brazing element between an interface area of said hollow electrostatic chuck shaft and an interface area of said electrostatic chuck plate, thereby creating a joining pre-assembly, wherein said hollow electrostatic chuck shaft and said electrostatic chuck plate comprise aluminum nitride, and wherein said brazing element comprises at least 99% aluminum by weight;
placing said joining pre-assembly in a process chamber;
removing oxygen from said process chamber; and
heating said joining pre-assembly after removing the oxygen from the process chamber, thereby joining said hollow electrostatic chuck shaft to said electrostatic chuck plate with a joint which hermetically seals an interior space of said hollow electrostatic chuck shaft from an exterior of said hollow electrostatic chuck shaft through said joint,
wherein the step of heating the joining pre-assembly comprises heating the joining pre-assembly to a first temperature between 800 C and 1200 C, and wherein said joint joins between an aluminum nitride surface of said hollow electrostatic chuck shaft and an aluminum nitride surface of said electrostatic chuck plate.
7. The method of claim 6 wherein the step of removing oxygen comprises applying vacuum to the process chamber wherein said pressure is lower than 1×10E-4 Torr.
8. The method of claim 6 wherein the step of removing oxygen from said shaft and plate pre-assembly during the heating step comprises filling said process chamber with pure, dehydrated inert gas.
9. The method of claim 6 wherein the step of removing oxygen from said shaft and plate pre-assembly during the heating step comprises filling said process chamber with purified hydrogen.
10. The method of claim 1 further comprising the steps of:
heating the joined shaft and joint assembly to temperature above 540 C; and
disjoining the joint between said device shaft and said device plate.