Patent Application
20060239800
This invention relates generally to cluster tools for etching and depositing layers on semiconductor wafers.
A cluster tool is a robot operated tool which includes a plurality of processing chambers for etching and deposition. One or more robots situated centrally relative to the processing chambers are responsible for transferring the wafers from chamber to chamber for processing.
Commonly, DC sputtering or physical vapor deposition may be implemented in one or more of those chambers. However, such sputtering may not be successful in depositing relatively high resistance films such as chalcogenide materials.
Thus, there is a need for other ways to deposit physical vapor deposition layers in cluster tools.
Referring to
Inside the chamber 12 is a grounded shield 14. The grounded shield 14 is coupled to a wafer clamp 18. The wafer clamp 18 clamps a wafer (not shown in
Also contained within the vacuum chamber 12 may be a floating shield 84. Finally, at the top of the chamber 12 is the target 86 which is made of the material to be sputtered on the wafer mounted on the pedestal electrode 16 by the clamps 18.
The vacuum within the chamber 12 may be established by cryopump 20 which communicates through a port (not shown) with the chamber 12. The cryopump 20 maintains a low pressure within the chamber 12.
The DC magnetron and radio frequency generator 28 may include a lid cover 27 made of metal, such a aluminum, instead of plastic for better RF shielding to the source. Also, the access plate 80, for communication connections, may be made of a metal, such as aluminum, to isolate RF power from traveling on communication lines 82. Finally, a metal plate 89 may be located between the target 86 and the generator 28. The plate 89 may be formed of aluminum. The plate 89 may enable better source grounding.
Over the generator 28 may be situated a radio frequency matching circuit 30. The circuit 30 balances out the radio frequency energy from the generator to the chamber load. The RF matching circuit 30 enables the tuning of the RF power supply to the chamber 12. The matching circuit 30 is coupled to a radio frequency power supply 32.
Referring to
The clamp ring 18 may have an edge exclusion, indicated by the distance X, of 6 millimeters in some embodiments of the present invention. Such an edge exclusion results in minimal contact with the edge of the wafer W. Also, an increased edge exclusion may protect more surface area to prevent cross contamination in the RF physical vapor deposition environment.
Referring to
The robot buffer chamber 60 also includes a robot. That robot may receive wafers from a load lock chamber 66, and transfer them to different stations surrounding the robot buffer chamber 60 or to the treatment chamber 62 for transfer to the transfer robot chamber 58. For example, the chamber 75 may be a pre-clean chamber and the chamber 56 may provide a barrier chemical vapor deposition chamber. The chambers 70 and 72 may be used for degassing and orientation.
Thus, the robot in the robot buffer chamber 60 grabs a wafer from a load lock chamber 66 and transports the wafer to chambers 70, 72 for degassing and orientation. From there the robot in the chamber 60 transfers the wafer to chamber 56 for chemical vapor deposition barrier layer formation in some embodiments of the present invention. Then, the wafer may be transferred to the pre-clean chamber 75.
Finally, the wafer may be transferred by the robot in the robot buffer chamber 60 to the treatment chamber 62 for transfer to the robot chamber 58. From there, various physical vapor deposition (or other steps) may be completed, including the RF or pulsed DC deposition of highly resistive layers in the chamber 10. Once the processing is done, the robot in the chamber 58 transfers the wafer to the cool down treatment chamber 63. From there, it can be accessed by the robot buffer chamber 60 robot and transferred out of the cluster tool 50 through a load lock chamber 66.
In some embodiments of the present invention, the reactor 10 may RF sputter deposit more highly resistive films, such as chalcogenide films. However, the same chamber may also be utilized for pulsed direct current sputtering as well. Because the RF power source is isolated from the rest of the components in the tool 50, RF interference with other chambers and with computer cluster tool 50 controllers that control the robots and other RF sensitive elements may be reduced.
In particular, better RF shielding for the source may be provided, RF power may be isolated from traveling on communication lines, and better source grounding may be achieved. As a result, in some embodiments of the present invention, RF sputtering may be implemented in a cluster tool despite the sensitivity of other components in the cluster tool to the radio frequency power.
While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate numerous modifications and variations therefrom. It is intended that the appended claims cover all such modifications and variations as fall within the true spirit and scope of this present invention.
