Controlled porosity yttrium oxide for etch applications
A sintered yttrium oxide body having a total impurity level of 40 ppm or less, a density of not less than 4.93 g/cm3, wherein the sintered yttrium oxide body has at least one surface comprising at least one pore, wherein no pore is larger than 5 μm in diameter. A process for making the sintered yttrium oxide body is also disclosed.
1. A sintered yttrium oxide body having a total impurity level of 40 ppm or less, a density of not less than 4.93 g/cm 3 , wherein the sintered yttrium oxide body has at least one surface comprising at least one pore, wherein no pore is larger than 5 μm in diameter.
2. The sintered yttrium oxide body of claim 1 wherein the density is not less than 4.96 g/cm 3 .
3. The sintered yttrium oxide body of claim 1 wherein no pore is larger than 2 μm in diameter.
4. The sintered yttrium oxide body of claim 3 wherein no pore is larger than 1 μm in diameter.
5. The sintered yttrium oxide body of claim 1 wherein the total impurity level is 35 ppm or less.
6. The sintered yttrium oxide body of claim 5 wherein the total impurity level is 10 ppm or less.
7. The sintered yttrium oxide body of claim 6 wherein the total impurity level is 6 ppm or less.
8. The sintered yttrium oxide body of claim 1 exhibiting an etch volume of less than about 375,000 μm 3 in a process wherein a 10 mm×5 mm area of the at least one surface is subjected to etching conditions at a pressure of 10 millitorr, an argon flow rate of 20 sccm, a bias of 600 volts and 2000 Watt ICP power, wherein the process has a first step and a second step wherein the first step has a CF 4 flow rate of 90 sccm, oxygen flow rate of 30 sccm for 1500 seconds, and the second step has a CF 4 flow rate of 0 sccm and oxygen flow rate of 100 sccm for 300 seconds, wherein the first and second steps are repeated sequentially until the time of CF 4 exposure in the first step is 24 hours.
9. The sintered yttrium oxide body of claim 1 having a pore size distribution with a maximum pore size of 1.50 um for 95% or more of all pores on the at least one surface.
10. The sintered yttrium oxide body of claim 1 exhibiting an etch rate of less than 1.0 nm/min in a process wherein a 10 mm×5 mm area of the at least one surface is subjected to etching conditions at a pressure of 10 millitorr, an argon flow rate of 20 sccm, a bias of 600 volts and 2000 Watt ICP power, wherein the process has a first step and a second step wherein the first step has a CF 4 flow rate of 90 sccm, oxygen flow rate of 30 sccm for 1500 seconds, and the second step has a CF 4 flow rate of 0 sccm and oxygen flow rate of 100 sccm for 300 seconds, wherein the first and second steps are repeated sequentially until the time of CF 4 exposure in the first step is 24 hours.
11. A process of making a sintered yttrium oxide body, the process comprising the steps of:
a. disposing yttrium oxide powder inside a volume defined by a tool set of a sintering apparatus;
b. creating vacuum conditions or an inert environment inside the volume;
c. applying a pressure of from 10 MPa to 60 MPa to the yttrium oxide powder while heating to a sintering temperature of from 1200 to 1600° C. and performing sintering to form a sintered yttrium oxide body; and
d. lowering the temperature of the sintered yttrium oxide body, wherein the yttrium oxide powder of step a) has a surface area of 10 m 2 /g or less, wherein the sintered yttrium oxide body has a total impurity level of 40 ppm or less, a density of not less than 4.93 g/cm 3 , at least one surface comprising at least one pore, wherein no pore is larger than 5 μm in diameter.
12. The process of claim 11 , further comprising the steps of:
e. annealing the sintered yttrium oxide body by applying heat to raise the temperature of the sintered yttrium oxide body to reach an annealing temperature, performing annealing;
f. lowering the temperature of the annealed sintered yttrium oxide body to an ambient temperature by removing the heat source applied to the sintered yttrium oxide body; and
g. optionally machining the annealed sintered yttrium oxide body to create a sintered yttrium oxide body component, wherein the component is selected from the group consisting of a dielectric window or RF window, a focus ring, a nozzle or a gas injector, a shower head, a gas distribution plate, an etch chamber liner, a plasma source adapter, a gas inlet adapter, a diffuser, an electronic wafer chuck, a chuck, a puck, a mixing manifold, an ion suppressor element, a faceplate, an isolator, a spacer, and a protective ring.
13. The process of claim 11 wherein the yttrium oxide powder is calcined prior to step a).
14. The process of claim 11 wherein the pressure applied to the yttrium oxide while heating is from 10 MPa to 40 MPa.
15. The process of claim 11 wherein the yttrium oxide powder has a surface area of from 2.0 to 4.0 m 2 /g.
16. The process of claim 11 wherein the purity of the yttrium oxide powder is higher than 99.998%.
17. The process of claim 11 wherein the sintered yttrium oxide body has a purity of between 99.99 and 99.999%.
18. The process of claim 11 wherein the sintering is performed for a time of from 1 minute to 120 minutes.
19. The process of claim 11 wherein the sintered yttrium oxide body has a density of not less than 4.98 g/cm 3 .
20. The process of claim 11 wherein no pore on the at least one surface is larger than 2 μm in diameter.