SHOWERHEAD ASSEMBLY FOR VACUUM PROCESSING APPARATUS
Vacuum processing chambers having provisions for thermal expansion and contraction. Specific embodiments provide a plasma processing chamber having a showerhead that enables thermal expansion and contraction without imparting structural stress on the chamber body and without breaking any vacuum seal.
This application is a continuation of and claims priority from U.S. Provisional Application Ser. No. 61/285,505, filed on Dec. 10, 2009, the entire content of which is incorporated herein by reference.
BACKGROUND1. Field
The invention concerns a vacuum processing apparatus, such as plasma chambers used for etching or forming thin films on substrates or other workpieces.
2. Related Art
Manufacturing processes in the fields of semiconductor, flat panel displays, solar panels, etc., involve processing in vacuum chambers. For example, vacuum chambers are used for plasma-enhanced chemical vapor deposition (PECVD), plasma etching and various other processes for forming thin films on substrates (workpieces) and etching structures on the substrates. In such chambers, various gases are flowed into the chamber, either via injectors or via a showerhead. For uniform plasma processing in large chambers, a showerhead is preferable over injectors. The showerhead would generally cover substantially the entire ceiling of the chamber, so that even amount of gas is injected everywhere within the chamber.
As gas is flowed into the chamber, plasma is ignited and sustained using radio frequency or microwave energy. This heats up the chamber. Also, for many processes active heaters are used to heat the substrates, which further add to heating of the chamber. Of course, when the processed substrates are removed from the chamber and fresh ones are introduced into the chamber, the chamber cools down until plasma is ignited again. These changes in temperatures cause various parts of the chamber to expand and contract. Parts made of different material would expand and contract at different rates. Also, large parts in large chamber would expand considerably. This is especially true for showerheads of large processing chambers, such as those used for fabrication of flat panel displays or solar cell.
SUMMARYThe following summary of the invention is included in order to provide a basic understanding of some aspects and features of the invention. This summary is not an extensive overview of the invention and as such it is not intended to particularly identify key or critical elements of the invention or to delineate the scope of the invention. Its sole purpose is to present some concepts of the invention in a simplified form as a prelude to the more detailed description that is presented below.
Embodiments of the invention provide vacuum processing chambers having provisions for thermal expansion and contraction. Specific embodiments of the invention provide a plasma processing chamber having a showerhead that enables thermal expansion and contraction without imparting structural stress on the chamber body and without breaking any gas seal.
According to an embodiment of the invention, a plasma chamber is provided wherein the showerhead assembly anchors the showerhead at one point, while allowing sliding of the shower at other points in order to allow for thermal expansion and contraction. According to another embodiment, no anchoring is provided, and the showerhead may slide in all directions while maintaining gas seal.
According to an embodiment of the invention, a vacuum processing chamber is provided, comprising: a chamber body; a showerhead assembly coupled to top portion of the chamber body and comprising: a back plate rigidly attached to the chamber body; a perforated showerhead plate having a plurality of oval holes; and, a plurality of fastening assemblies that slidingly attach the showerhead plate to the back plate to thereby allow sliding of the showerhead plate relative to the back plate while gas seal is maintained between the showerhead plate and the back plate. According to one embodiment, at least one bolt rigidly attaches the showerhead plate to the back plate.
According to an embodiment of the invention, a method for securing a showerhead assembly onto a vacuum processing chamber is provided, comprising: fixedly attaching a back plate to the vacuum processing chamber; coupling a perforated showerhead plate to the back plate by using a plurality of fastening assemblies to slidingly attach the perforated showerhead plate to the back plate; and, providing a gas seal between the perforated showerhead plate and the back plate. According to one embodiment, the method further comprises fixedly attaching at least one location of the perforated showerhead plate to the back plate.
Other aspects and features of the invention will become apparent from the description of various embodiments described herein, and which come within the scope and spirit of the invention as claimed in the appended claims.
The accompanying drawings, which are incorporated in and constitute a part of this specification, exemplify the embodiments of the present invention and, together with the description, serve to explain and illustrate principles of the invention. The drawings are intended to illustrate major features of the exemplary embodiments in a diagrammatic manner. The drawings are not intended to depict every feature of actual embodiments nor relative dimensions of the depicted elements, and are not drawn to scale.
As shown in
A sliding plate 173 is provided over the insert 170. The sliding plate 173 has four oval holes 174, which are also oriented in the direction of sliding. In each of the holes, a ball 175 is inserted. Each ball 175 can ride freely inside its respective oval hole 174. A cover plate 176 is provided over the assembly of the sliding plate 173 and balls 175. It can be appreciated that the insert 170, sliding plate 173, balls 175 and cover plate 176, essentially form a “linear” ball bearing arrangement. Two optional washers 177, 178 are provided over the cover plate 176, and a bolt 150 tightens the entire assembly onto the back plate 125. As can be understood, under proper tightening of the bold 150, the showerhead plate 120 can be sealed to the backplate 150, but also be able to expand by sliding with respect to the backplate 125. When this occurs, the assembly of showerhead plate 120 and insert 170 “ride” on balls 175, since the hole 172 provided in the insert 170 is oval in the direction of expansion motion. In this embodiment, all of the parts, except for the bolt 150, are made of ceramic, but other materials may be used for the various parts, such as aluminum, anodized aluminum, Teflon, etc.
According to another embodiment, the showerhead plate is not fixedly attached to the back plate. Rather, a plurality of sliding fastening assemblies are used to attach the showerhead plate to the back plate, so that it is free to expand in all directions. However, the plurality of sliding fastening assemblies are oriented such that the center of the showerhead plate remains at the same location regardless of expansion or contraction of the showerhead plate. This is illustrated in
While the invention has been described with reference to particular embodiments thereof, it is not limited to those embodiments. Specifically, various variations and modifications may be implemented by those of ordinary skill in the art without departing from the invention's spirit and scope, as defined by the appended claims. Additionally, all of the above-cited prior art references are incorporated herein by reference.
Claims
1. A vacuum processing chamber, comprising:
- a chamber body;
- a showerhead assembly coupled to top portion of the chamber body and comprising: a back plate rigidly attached to the chamber body; a perforated showerhead plate; a plurality of fastening assemblies slidingly securing the showerhead plate to the back plate such that the showerhead plate may slide with respect to the back plate; and, wherein gas seal is maintained between the showerhead plate and the back plate.
2. The vacuum processing chamber of claim 1, wherein the perforated showerhead plate comprises a plurality of oval holes at periphery thereof, and wherein each one of the plurality of fastening assemblies is inserted in a respective one of the plurality of oval holes.
3. The vacuum processing chamber of claim 1, wherein the showerhead assembly further comprises an o-ring provided between the showerhead plate and the back plate.
4. The vacuum processing chamber of claim 1, wherein the showerhead assembly further comprises a spacer provided between the showerhead plate and the back plate to thereby maintaining a small gap between the showerhead plate and the back plate.
5. The vacuum processing chamber of claim 1, wherein the showerhead plate further comprises a circular hole and a bolt passing through the circular hole and fixedly securing the showerhead plate to the back plate.
6. The vacuum processing chamber of claim 2, wherein the each of the plurality of oval holes is oriented such that its long axis lies along a straight line extending radially from the center of the showerhead plate and passing through that oval hole.
7. The vacuum processing chamber of claim 6, wherein each of the fastening assembly comprises a key to enable only one orientation when the fastening assembly is seated within its respective oval hole.
8. The vacuum processing chamber of claim 1, wherein each of the fastening assemblies comprises a ball bearing assembly and a bolt passing through the ball bearing assembly.
9. The vacuum processing chamber of claim 8, wherein the ball bearing assembly comprises:
- an insert having an oval hole therein;
- a sliding plate having a plurality of non-circular holes therein;
- a plurality of balls, each for a corresponding one of the non-circular holes;
- a cover plate having a circular hole therein.
10. The vacuum processing chamber of claim 9, wherein the insert further comprises a key to orient the insert inside one of the oval holes of the showerhead plate.
11. The vacuum processing chamber of claim 9, wherein at least one of the insert, sliding plate, plurality of balls, and cover plate, is made of ceramic.
12. The vacuum processing chamber of claim 8, further comprising a covering plate for covering the fastening assembly.
13. The vacuum processing chamber of claim 1, wherein each of the fastening assembly comprises:
- an insert having an oval hole therein and a sliding surface;
- a cover plate having a mating surface facing the sliding surface; and,
- a bolt passing through the insert and the cover plate.
14. The vacuum processing chamber of claim 1, wherein each of the fastening assembly further comprises a sliding plate inserted between the insert and the cover plate.
15. The vacuum processing chamber of claim 1, wherein the sliding plate comprises a Teflon plate.
16. A method for securing a showerhead assembly onto a vacuum processing chamber, comprising:
- fixedly attaching a back plate to the vacuum processing chamber;
- coupling a perforated showerhead plate to the back plate by using a plurality of fastening assemblies to slidingly attach the perforated showerhead plate to the back plate; and,
- providing a gas seal between the perforated showerhead plate and the back plate.
17. The method of claim 16, wherein slidingly attaching comprises bolting the perforated showerhead plate to the back plate via a ball bearing assembly.
18. The method of claim 17, further comprising inserting a spacer between the perforated showerhead plate and the back plate.
19. The method of claim 17, further comprising orienting each of the ball bearing assembly such that it is aligned with an imaginary line extending radially from the center of the showerhead plate.
20. The method of claim 16, further comprising fixedly affixing the showerhead plate to the back plate at one point.
Type: Application
Filed: Dec 10, 2010
Publication Date: Jun 16, 2011
Inventors: Wendell Thomas BLONIGAN (Pleasanton, CA), Michael Allen Renta (Campbell, CA)
Application Number: 12/965,804
International Classification: C23F 1/08 (20060101); C23C 16/455 (20060101); B23P 11/00 (20060101);