Patent Application
20070026769
The present invention is directed, in general, to planarizing/polishing a surface and, more specifically, to a chemical mechanical polishing apparatus, a method for planarizing/polishing a surface, and a method for manufacturing an integrated circuit.
Chemical mechanical planarizing/polishing (CMP) is an essential process in the manufacture of semiconductor chips today. Dielectric and metal layers used in chip fabrication must be made extremely flat and of precise thickness in order to pattern the sub-micron sized features that comprise a semiconductor device. During CMP, the combination of chemical etching and mechanical abrasion produces the required flat, precise surface for subsequent depositions.
Turning briefly to
The CMP apparatus 100 illustrated in
While CMP offers a practical approach for achieving the important advantage of global wafer planarity, CMP has certain disadvantages. One such disadvantage of CMP is the extreme cost associated therewith. For example, the cost associated with the CMP slurry itself can be significant.
Accordingly, what is needed in the art is a CMP process and a CMP apparatus that does not experience the drawbacks of the conventional CMP processes.
To address the above-discussed deficiencies of the prior art, the present invention provides a method for planarizing/polishing a surface, a method for manufacturing an integrated circuit and a chemical mechanical polishing apparatus. The method for planarizing/polishing a surface, among other elements, includes providing a chemical mechanical polishing apparatus having a polishing platen, a carrier head positioned over the polishing platen the polishing platen, and a slurry delivery source positioned over and off center the polishing platen, and rotating the polishing platen in a direction such that slurry exiting the slurry delivery source and contacting the polishing platen must rotate less than about 220 degrees before contacting a polishable surface maintained by the carrier head.
As briefly mentioned above, the present invention further provides a method for manufacturing an integrated circuit. The method for manufacturing the integrated circuit, without limitation, may include forming a polishable surface over a wafer substrate, and planarizing/polishing the polishable surface, the planarizing/polishing being conducted similar to that discussed in the paragraph directly above. For example, the planarizing/polishing could be conducted by placing the polishable surface in a carrier head positionable over a polishing platen of a chemical mechanical polishing apparatus, and rotating the polishing platen in a direction such that slurry exiting a slurry delivery source must rotate an angle (θ) less than about 220 degrees before contacting the polishable surface, the slurry delivery source positioned over and off center of the polishing platen.
Another aspect of the present invention provides a chemical mechanical polishing apparatus. In addition to other elements, the chemical mechanical polishing apparatus may include: 1) a polishing platen, 2) a carrier head positionable over the polishing platen, and 3) a slurry delivery source positionable over and off center the polishing platen, the polishing platen configured to rotate in a direction such that slurry exiting the slurry delivery source and contacting the polishing platen must rotate less than about 220 degrees before contacting a polishable surface maintained by the carrier head.
The foregoing has outlined preferred and alternative features of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they can readily use the disclosed conception and specific embodiment as a basis for designing or modifying other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention.
The invention is best understood from the following detailed description when read with the accompanying FIGUREs. It is emphasized that in accordance with the standard practice in the semiconductor industry, various features are not drawn to scale. In fact, the dimensions of the various features may be arbitrarily increased or reduced for clarity of discussion. Reference is now made to the following descriptions taken in conjunction with the accompanying drawings, in which:
Prior Art
The present invention is based, at least in part, on the acknowledgment that the cost of slurry is a significant portion of the overall cost of manufacturing an integrated circuit, and moreover, that the conventional chemical mechanical polishing (CMP) apparatus, and the conventional techniques for planarizing/polishing surfaces using the conventional CMP apparatus, are responsible for a large portion of the cost. More specifically, the present invention has acknowledged that the conventional CMP apparatus, and the conventional techniques for planarizing/polishing surfaces using the conventional CMP apparatus, require that the slurry travel a significant distance on the polishing platen prior to encountering the polishable surface. It should be noted that for the purpose of the present invention, the terms planarizing and polishing are synonymous, and thus may be used interchangeably without limiting the present invention.
Referring briefly back to
The present invention has further acknowledged that the design of the conventional CMP apparatus requires the slurry to encounter the polishing pad conditioner prior to encountering the polishable surface, as illustrated in
Given the aforementioned acknowledgements, the present invention has uniquely recognized that placing the slurry delivery source closer to the polishable surface would significantly decrease the amount of slurry required to properly polish the polishable surface. Namely, by placing the slurry delivery source such that the slurry must rotate less than about 220 degrees before encountering the polishable surface, the amount of slurry used may be greatly reduced. The present invention has further uniquely recognized that placing the polishing pad conditioner such that the slurry must encounter the polishable surface before the polishing pad conditioner, would also significantly decrease the amount of slurry required to properly polish the polishable surface. By employing these two recognitions, it is believed that the amount of slurry traditionally used may be reduced by about 30-50 percent.
Regrettably, prior art CMP apparatuses are configured in such a way as to prevent accommodating the aforementioned acknowledgements. In other words, prior art CMP apparatuses during normal operation and without significant modifications may not accommodate the aforementioned acknowledgements. Namely, prior art CMP apparatuses are configured such that the slurry delivery source is substantially fixed with respect to the carrier head, and thus the polishable surface. As the slurry delivery source of the conventional CMP apparatuses is substantially fixed in a position that the slurry must rotate at least about 240 degrees before encountering the polishable substrate, conventional CMP apparatuses may not, without reconfiguration, accommodate the unique desire to have the slurry rotate less than about 220 degrees before encountering the polishable surface. While the rotation of the polishing platen could conceivably be changed to rotate in a clockwise direction, as compared to the counter-clockwise direction that the conventional CMP apparatuses require, the conventional CMP apparatuses are not, again without significant reconfiguration, capable of rotating in the clockwise direction. For example, attempting to rotate the conventional CMP apparatuses in a clockwise direction generates a collection of error messages in the software that operates the conventional CMP apparatuses. Because of the error messages, the conventional CMP apparatuses may not be configured to rotate in a direction such that the large degree of rotation may be reduced.
Additionally, the prior art CMP apparatuses are configured such that the location of the polishing pad conditioner is semi-fixed with respect to the carrier head, and thus the polishable surface. Accordingly, without a massive reconfiguration of the polishing pad conditioner, the conventional CMP apparatuses may not accommodate the unique desire to have the slurry encounter the polishable surface before contacting the polishing pad conditioner.
Turning now to
The CMP apparatus 200 illustrated in
The CMP apparatus 200 additionally includes a polishing pad conditioner 240 positioned over the polishing platen 210. As those skilled in the art are generally aware, the polishing pad conditioner 240 is designed to condition or replenish the polishing pad on the polishing platen 210, thus extending its effective lifespan. The polishing pad conditioner 240 is configured to both rotate and oscillate about the polishing platen 210.
The CMP apparatus 200 illustrated in
In the embodiment of
The change of rotational direction of the polishing platen 210 may be accomplished a number of different ways. In one embodiment of the present invention, the motor connected to the polishing platen 210 of the conventional CMP apparatus 100 is replaced with a motor designed to rotate the polishing platen 210 in a clockwise direction. While this would be a significant modification to the conventional CMP apparatus, it might be the only modification that would need to be made to practice the novel aspects of the present invention, and thus a worthy modification.
Another embodiment might exist wherein the software that controls the conventional CMP apparatus 100 is rewritten to allow the original motor associated with the conventional CMP apparatus 100 to rotate in the opposite direction that it was initially designed to rotate (e.g., it was originally designed to rotate in a counter-clockwise direction). While this embodiment might require the hiring of a computer programmer and the introduction of the new software into the conventional CMP apparatus 100, it might be less costly than replacing the motor as described above.
Accordingly, in the embodiment of
The advantages of operating the CMP apparatus 200 in the aforementioned manner are significant. First and foremost, operating the CMP apparatus 200 in the aforementioned manner saves an exceptional amount of slurry. More specifically, operating the CMP apparatus 200 in the aforementioned manner may save at least about 30 percent, and more specifically from about 30-50 percent, of the slurry traditionally required. Moreover, the polishing process does not suffer at the expense of saving slurry, as might occur using other methods.
Turning now briefly to
It should be noted that the same idea might be accomplished by moving the carrier head 320 to a location wherein it interposed the slurry delivery source 330 and the polishing pad conditioner 340. Because the general idea is based upon the location of the slurry delivery source 330 to the carrier head 320, or vice verse, the movement of either to reduce the angle (θ3) would suffice.
Turning to
Referring now to
Although the present invention has been described in detail, those skilled in the art should understand that they could make various changes, substitutions and alterations herein without departing from the spirit and scope of the invention in its broadest form.
