Patent Application
20090137192
In a number of applications, fluid pressure must be regulated in coupled or non-coupled volumes that are remotely placed with respect to the pressure sensor and the fluid flow actuator. These applications may include, but are not limited to, semiconductor processing systems such as CMP (chemical mechanical polishing) tools. Improving the reliability and serviceability of pressure control systems (PCS) for such applications is a high priority.
A pressure control system that controls the pressure of a fluid in a plurality of zones includes a distribution manifold, at least one main manifold connected to the distribution manifold, and at least one disposable manifold connected to the distribution manifold and the main manifold. The disposable manifold is adapted to be replaced independent of the distribution manifold and the main manifold, and is connected to each zone and to at least one vacuum source. The distribution manifold is configured to distribute the fluid from a pressurized source of the fluid to the plurality of zones, so as to cause flow of the fluid into and out of a measurement chamber located within each zone. The main manifold includes, for each zone, a pressure sensor configured to measure pressure in the measurement chamber in that zone, and a control valve configured to regulate the flow of the fluid through that zone.
Systems and methods are described in which pressure is controlled in a plurality of zones. These systems and methods provide a distribution manifold, at least one manifold, and at least one disposable manifold that is independently replaceable, in order to control the pressure in the plurality of zones. In case a failure, such as slurry contamination, occurs in one of the zones, the systems and methods described below permit only the failed zone to be replaced without having to replace the other zones. Also, such a replacement can be performed directly on the tool, resulting in shorter change over time. The systems and methods described below provide a more robust design for a multi-zone pressure control system.
As seen in
The distribution manifold 110, also referred to in this patent as a pressure and vacuum distribution manifold or a fluid distribution manifold, does not house any field replaceable parts. In the present patent, the words “distribution manifold,” “fluid distribution manifold”, and “pressure and vacuum distribution manifold” have the same meaning, and are used interchangeably. In the illustrated embodiment, the distribution manifold 110 is fed from a regulated pressure line 112 and a vacuum line 114.
At least one main manifold is coupled to the distribution manifold 120. In the embodiment illustrated in
For each zone, a disposable manifold is also provided, each disposable manifold including a vacuum port 135 that connects to a vacuum source, and a zone port 138 that connects to a respective zone (one of 160, 170, 180, and 190) via a conduit. Each disposable manifold (130-a . . . 130-d) in the disposable manifold assembly 130 is designed to be field removable and independently replaceable, in the event of failures such as slurry contamination.
While in the illustrated embodiment, one main manifold is provided for each one of the plurality of zones, and likewise one disposable manifold is provided for each one of the plurality of zones, other embodiments of the present disclosure may include different combinations of the main manifold and/or the disposable manifold, for the different zones. In general, at least one main manifold and at least one disposable manifold may be provided for each zone.
In one embodiment, the pressure control system 100 may be used for pressure control in a CMP (chemical mechanical polishing) application, and the plurality of zones may be resilient bladders found in internal chambers of a CMP carrier head system. CMP is a commonly used method of planarization of semiconductor substrate surfaces. As a series of silicon layers are sequentially deposited and etched, the outer or uppermost surface of the substrate, i.e., the exposed surface of the substrate, may become increasingly non-planar, and may need to be periodically planarized in order to avoid problems in the photolithographic steps of the integrated circuit fabrication process. Therefore, there may be a need to periodically planarize the substrate surface, and CMP is one of the widely used methods of planarization.
The CMP planarization method may typically require that the substrate be mounted on a carrier or polishing head. The exposed surface of the substrate may be placed against a rotating polishing pad. The carrier head may provide a controllable load, i.e., pressure, on the substrate to push it against the polishing pad. A polishing slurry, including at least one chemically-reactive agent and, in some cases, abrasive particles, may be supplied to the surface of the polishing pad.
An illustrative CMP carrier head system is shown for example in published U.S. application No. US 2004/0250859 to Poulin and Clark, which is hereby incorporated by reference in its entirety. An exemplary CMP carrier head system may be rotatable about its rotation axis, and may include a carrier head connected to a rotation motor. The carrier head may have a number of internal chambers, which are formed at least in part by resilient bladders which expand when the chambers are pressurized, and which contract when a vacuum is created within the chambers. For example, pressurizing a chamber in the carrier head can be used to press a substrate against a rotating polishing pad, while creating a vacuum in the chamber can be used to provide suction for holding the substrate against the carrier head during transfer of the substrate to and from the polishing pad.
The pressure control system 100 may be coupled to the CMP carrier head through a rotary coupling, and may control pressure of a fluid (such as nitrogen) in the plurality of bladders in the carrier head.
The third valve 240 may be opened when it is desired to decrease the pressure of the fluid flowing through the zone to which the disposable manifold is connected. The first valve 230 may be opened when it is desired to slow down a rate of decrease of the pressure of the fluid flowing through the zone to which the disposable manifold is connected.
In a CMP tool, there is typically a barrier in between the pressure control system (PCS) and the wet mixture (slurry) contained in the bladder. The bladder can rupture, due to lack of preventative maintenance, and allow the slurry enter the vacuum line that results in exposure of the valve to the slurry. Over time slurry can cause valve failure. In the event of slurry contamination, the disposable manifold is the only subassembly that would get contaminated. The disposable manifold 200 is designed to be field removable and replaceable in the event of failure, such as slurry contamination in a CMP carrier head. The disposable manifold 200 can be removed while the PCS (pressure control system) 100 is on the CMP tool.
In sum, systems and methods have been described that allows pressure to be controlled in a plurality of independent pressure control zones. Different zones may have different pressure control ranges over which pressure within respective zones can be controlled.
The design described above introduces a significant improvement over prior methods of controlling pressure in remote zones. Using the modular design for the pressure control system (PCS) would allow to serve the PCS on the tool, which would reduce the tool down time and cost of serviced parts. Using conventional techniques, all zones would have to be replaced, once one zone was exposed to slurry. Using the systems and methods described in the present disclosure, only the failed zone would have to be replaced, and such a replacement can be done on the tool resulting in shorter change over time. The design described above also helps with the robustness of the PCS. The systems and methods described in the present disclosure may be used by customers to regulate, for example, the pressure in the carriage head for CMP applications. The PCS described above may be used in many other applications, including but not limited to semiconductor processing systems.
While certain embodiments have been described of systems and methods for controlling pressure in a plurality of zones, it is to be understood that the concepts implicit in these embodiments may be used in other embodiments as well. The protection of this application is limited solely to the claims that now follow.
In these claims, reference to an element in the singular is not intended to mean “one and only one” unless specifically so stated, but rather “one or more.” All structural and functional equivalents to the elements of the various embodiments described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference, and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public, regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. §112, sixth paragraph, unless the element is expressly recited using the phrase “means for” or, in the case of a method claim, the element is recited using the phrase “step for.”
