Chucks are employed to support wafers in a variety of semiconductor workpiece processes. In a deposition process, for example, a chuck clamps a semiconductor wafer in place while a film is deposited on the wafer. Similarly, in an etch process, an electrostatic chuck clamps a semiconductor wafer in place while material is removed from the wafer. An electrostatic chuck has electrodes that are energized with a clamping voltage, which electrostatically clamps the wafer to the surface of the electrostatic chuck.
After a wafer is transferred to a processing chamber, it rests on the upper surface of the electrostatic chuck. A clamping voltage is applied to the electrostatic chuck to clamp the wafer during the process. Uniformity in the chuck surface is critical to deposition or etch uniformity across the wafer surface. Over a period of use, uneven wear on the chuck can lead to poor uniformity across a wafer, as well as poor wafer-to-wafer uniformity.
Novel methods for extending electrostatic chuck lifetimes are provided. The methods involve providing a chuck having a metal cooling plate attached to a ceramic top plate, and after a period of use, disassembling the chuck, and providing a new chuck including the used metal cooling plate. In certain embodiments, the use of a low temperature bond material uniquely allows the described disassembly and reassembly without damage to other parts of the chuck.
These and other aspects are described further below.
Novel methods for extending electrostatic chuck lifetimes are provided. In certain embodiments, the methods involve receiving a chuck including a metal bottom plate bonded to a ceramic top plate. The metal bottom plate may be a cooling plate including one or more channels for coolant. The ceramic plate typically includes electrodes and a top surface on which a wafer is clamped via electrostatic force during processing.
In certain embodiments, the methods involve providing a chuck having a metal cooling plate attached to a ceramic top plate via indium bonding, and after a period of use, disassembling the chuck, and providing a new chuck including the used metal cooling plate. In certain embodiments, the use of indium as a bond material uniquely allows the described disassembly and reassembly without damage to other parts of the chuck.
As indicated, in certain embodiments, the debonding process involves heating the bond to melt an indium bond. The use of indium bonding material allows non-fracturing debonding to occur at much lower temperatures than required for other types of bonds including elastomer bonds and aluminum bonds.
Bottom plate 201 is made of a metal, typically copper though brass or another material may be used, and includes one or more channels 211 through which a coolant, typically water, passes to cool the chuck. Orifice 204 is a backside gas delivery path and may accommodate a sapphire pin (not shown) that extends into a similarly situated orifice (not shown) in the ceramic plate 203. The pin does not extend to the top surface of the ceramic plate 203 and may be used in a substrate temperature measurement system. Pins 215 include RF and DC bias pins. Bottom plate 201 is bonded to ceramic plate 203. The assembly 200 also includes a matched aluminum ring 207 that fits around bottom plate 201. O-ring 209 aids in aligning match aluminum 207 and bottom plate 201.
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The chuck assembly is then disassembled, by removing the O-rings, the aluminum ring and other installation hardware. (Block 103) The aluminum ring is matched to the bottom plate and is associated with it through the lifetime of the bottom plate. (Block 105).
At this stage, the bonded top and bottom plate (310 in
After debonding, the ceramic top plate and metal bottom plate are separated. (Block 107). The indium is removed from the metal plate, and the metal plate is cleaned. (Block 109). In other embodiments, the indium is optionally left on the metal plate for use in bonding a new ceramic plate. If removed, the indium may be discarded or saved for reuse in subsequent bonding processes. Unlike other bonding materials, because the indium is liquefied at low temperatures, it can be wiped off or otherwise easily removed without having to remove any remaining solid materials. Cleaning the metal plate is optional. In certain embodiments, the coolant channels are checked for build-up and cleared of any blockages. An unused ceramic plate that has not undergone any semiconductor fabrication processing operations is then provided. (Block 111).
The metal plate may also be masked as necessary to protect orifices on its top side. A wetting layer is then applied to the metal plate by a PVD, CVD or other appropriate process. (Block 117) According to various embodiments, the wetting layer may be a backside metallization or wetting layer. The wetting layer is applied to the edge of the top surface of the metal plate. Indium is then applied, typically in a paste, to a height of 0.01 inches (10 mils). To do this, this indium is applied up to a height of 0.01 inch high stand-offs on the top side of metal plate. (Block 119).
The bond height of about 10 mils is permissible because of the high thermal conductivity of indium; elastomer bonds, for example, would need to be between about 2 and 4 mils. The indium bonding material is applied to the edge of the metal plate. The unused ceramic plate is then put into contact with the bonding material to assemble the hybrid used/unused chuck assembly. (Block 121) The indium bond is tightly controlled such that it is not recessed from or extended past the edge of the metal plate. In certain embodiments, this is facilitated by the use of the mask around the edge region 527 of the bottom surface of the ceramic plate as depicted in
The assembly is then cooled to form the bond, thereby completing the assembly of the hybrid chuck. (Block 123). The masking is then removed.
In certain embodiments, the height of the depicted assembly is about 1.2-1.3 inches, e.g., 1.25-1.27 inches, with the indium bond being about 0.01 inches thick. In one example, the diameter of the ceramic plate is about 7.794 inches and the diameter of the metal plate 7.424 inches.
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Other Embodiments
In other embodiments the processes described above are applied to electrostatic chucks having elastomer or aluminum bonds. For example, in certain embodiments, a chuck is provided after a period of use, as described above with respect to
In still other embodiments, a chuck including an indium bond may be refurbished to include an elastomer bond. In these embodiments, a used chuck may be provided and undergo a low temperature debonding process as described above. Elastomer bonding material is then used to bond an unused ceramic plate to the used metal plate. If the metal plate includes standoffs to control bond height as described above, the process includes removing these or machining them down to the appropriate height of the elastomer bond.
While the present invention has been described with reference to preferred embodiments, those skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the invention.
This application is a continuation of application Ser. No. 12/648,638 filed Dec. 29, 2009, titled ELECTROSTATIC CHUCKS AND METHODS FOR REFURBISHING SAME, naming Hart et al. as inventors, which is incorporated by reference herein in its entirety and for all purposes.
Number | Name | Date | Kind |
---|---|---|---|
3513891 | Heth | May 1970 | A |
5581874 | Aoki et al. | Dec 1996 | A |
7019956 | Fujii et al. | Mar 2006 | B2 |
7558045 | Onate et al. | Jul 2009 | B1 |
8597448 | Hart et al. | Dec 2013 | B2 |
20050219786 | Brown et al. | Oct 2005 | A1 |
20060002053 | Brown et al. | Jan 2006 | A1 |
20070103844 | Eguchi | May 2007 | A1 |
20070190799 | Wang et al. | Aug 2007 | A1 |
20080089001 | Parkhe et al. | Apr 2008 | A1 |
20080143379 | Norman | Jun 2008 | A1 |
20090034149 | Lubowirsky et al. | Feb 2009 | A1 |
20110155299 | Hart et al. | Jun 2011 | A1 |
Number | Date | Country |
---|---|---|
2786784 | Jun 2006 | CN |
102696101 | Sep 2012 | CN |
H9-45757 | Feb 1997 | JP |
2003-258072 | Sep 2003 | JP |
2004-104113 | Apr 2004 | JP |
2005191500 | Jul 2005 | JP |
2007-129142 | Jul 2007 | JP |
201138017 | Nov 2011 | TW |
2011090650 | Jul 2011 | WO |
Entry |
---|
Office Action dated Sep. 21, 2012, issued in U.S. Appl. No. 12/648,638. |
Final Office Action dated Apr. 12, 2013, issued in U.S. Appl. No. 12/648,638. |
Notice of Allowance dated Aug. 2, 2013, issued in U.S. Appl. No. 12/648,638. |
International Search Report and Written Opinion mailed Sep. 14, 2011, issued in Application No. PCT/US2010/061348. |
Chinese Office Action dated Aug. 15, 2014, issued in Application No. 201080059991.0. |
Japanese Office Action dated Sep. 16, 2014, issued in Application No. 2012-547130. |
Number | Date | Country | |
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20140124123 A1 | May 2014 | US |
Number | Date | Country | |
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Parent | 12648638 | Dec 2009 | US |
Child | 14066369 | US |