Lightup prevention using multi-layer ceramic fabrication techniques
In accordance with this disclosure, there are provided several inventions, including an electrostatic chuck apparatus comprising multiple layers with cutouts that form a labyrinth structure which defined a path for cooling or heating gas. The structure prevents particles from accelerating such that they form unwanted lightup in the gas flow path.
1. An electrostatic chuck for use in a plasma processing chamber, comprising:
a base through which passes a gas inlet;
above the base, constituting the top surface of the electrostatic chuck, a wafer ceramic for placement underneath a wafer for plasma processing, comprising a plurality of ceramic layers, wherein each ceramic layer contains one or more cutouts, the cutouts forming a labyrinth in direct or indirect fluid communication with the gas inlet, wherein at any position within the labyrinth, the line of sight to a surface within the wafer ceramic layer is less than about 4 mm in any direction.
2. The electrostatic chuck of claim 1 , wherein the number of layers is at least 3.
3. The electrostatic chuck of claim 2 , wherein the number of layers is at least 10.
4. The electrostatic chuck of claim 3 , wherein the number of layers is at least 14.
5. The electrostatic chuck of claim 1 , wherein the line of sight to a surface within the wafer ceramic layer is less than about 2 mm in any direction.
6. The electrostatic chuck of claim 5 , wherein the line of sight to a surface within the wafer ceramic layer is less than about 1 mm in any direction.
7. The electrostatic chuck of claim 6 , wherein the line of sight to a surface within the wafer ceramic layer is less than about 0.5 mm in any direction.
8. The electrostatic chuck of claim 1 , wherein the cutouts for each of the ceramic layers are selected from the group consisting of a semicircular channel and a bore, wherein each bore in one layer aligns with an end of a semicircular channel in an adjacent layer, thus forming a gas path that alternates between bore and circular layer.
9. The electrostatic chuck of claim 1 , further comprising:
a plug opening which constitutes a passageway from the gas opening to the labyrinth; and
a porous ceramic plug within the plug opening.
10. The electrostatic chuck of claim 1 , wherein at least one of the one or more cutouts is an excavation of a layer that passes only partially through the layer for at least a portion of the cutout.
11. A method of forming the electrostatic chuck of claim 1 , comprising:
providing the base through which passes the gas inlet;
providing the plurality of ceramic layers;
forming the cutouts within each of the ceramic layers; and
joining the ceramic layers, such that the ceramic layers form the wafer ceramic.
12. The method of claim 11 , wherein the ceramic layers are joined by co-sintering.
13. The method of claim 11 , wherein the ceramic layers are joined by bonding with glass frit.
14. The method of claim 11 , wherein the ceramic layers are joined by an adhesive.
15. An insert for an electrostatic chuck in a plasma processing chamber, comprising:
a plurality of ceramic layers, wherein each ceramic layer contains one or more cutouts, the cutouts forming a labyrinth in direct or indirect fluid communication with a gas inlet, wherein at any position within the labyrinth, the line of sight to a surface within the wafer ceramic layer is less than about 4 mm in any direction;
wherein a cutout in the top ceramic layer forms a top opening to the insert;
wherein a cutout in the bottom ceramic layer forms a bottom opening to the insert; and
wherein the insert is sized and configured to fit securely within an insert opening within the electrostatic chuck, so as to provide a fluid path from the gas inlet in the electrostatic chuck below the bottom opening, then through the bottom opening, then through the labyrinth, and then through the top opening.
16. The insert of claim 15 , wherein the insert is coated on one or more sides with an electrically insulating material, such that the coating does not obstruct the top opening or the bottom opening.
17. A method of placing the insert of claim 15 within the electrostatic chuck, comprising:
providing an electrostatic chuck with the insert opening located in its top surface; and
inserting the insert into the insert opening, such that the bottom opening aligns with the gas inlet of the electrostatic chuck.
18. The method of claim 17 , further comprising bonding the insert to the insert opening with a bonding material.