Abstract:
In one embodiment, a surface having a sealing groove formed therein. The sealing groove is configured to accept an elastomeric seal. The sealing groove includes a first portion having a full dovetail profile and at least on a second portion having a half dovetail profile.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims benefit of U.S. Provisional Patent Application Ser. No. 61/866,802, filed Aug. 16, 2013, which is incorporated by reference in its entirety. 
    
    
     BACKGROUND 
     Field 
     Embodiments disclosed herein generally relate to an apparatus and method for sealing a vacuum processing chamber. More particularly, embodiments herein relate to sealing technology for vacuum processing chambers. 
     Description of the Related Art 
     In the process of fabricating modern semiconductor integrated circuits (ICs), it is necessary to develop various material layers over previously formed layers and structures. The fabrication processes often involves multiple tightly controlled steps in various vacuum processing chambers before an IC is completely formed. The chamber gasses are evacuated to tightly control plasma processes and remove contaminants from within the vacuum processing chambers. Thus the vacuum processing chambers, such as plasma-assisted etching, chemical vapor deposition (CVD), physical vapor deposition (PVD), load lock, and transfer chambers and the like, are designed to operate under vacuum conditions. The vacuum processing chambers have seals along an opening, or connected surface, to keep outside air from being drawn into the vacuum processing chamber as vacuum is drawn and a negative pressure is maintained inside the vacuum processing chamber. 
     Some vacuum processing chambers, such as plasma processing chambers, operate at elevated temperatures. For example, the deposition of silicon and etching of metals typically occur with very high chamber temperatures. These high temperatures in the plasma chamber cause thermal expansion of chamber components and may contribute to chamber vacuum seal failure. Seal failure damages the seal itself, thus requiring costly chamber down time to allow for seal replacement. Some chamber manufactures utilize a large seal groove to mitigate seal issues at high temperatures. However, at lower temperatures, the O-rings tend to fall out of the oversized seal grooves. 
     Therefore there is a need for improved sealing technology suitable for use in a vacuum processing system. 
     SUMMARY 
     The embodiments described herein generally relate to a sealing groove suitable for use at elevated temperatures. In some embodiments, the sealing groove is particularly suitable for use in a vacuum processing chamber and the like. 
     In one embodiment, a surface has a sealing groove formed therein. The sealing groove is configured to accept an elastomeric seal. The sealing groove includes a first portion having a full dovetail profile and at least on a second portion having a half dovetail profile. 
     In another embodiment, a vacuum processing chamber includes a chamber body with a bottom, and side walls, a lid assembly moveable between an open and a closed position; and a sealing groove formed in one of the lid assembly and chamber body. The sealing groove configured to accept an elastomeric seal and includes a first portion having a full dovetail profile and at least on a second portion having a half dovetail profile. 
     In yet another embodiment, a sealing groove is disposed in a surface. The sealing groove includes a first portion having a full dovetail profile and at least on a second portion having a half dovetail profile. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments. 
         FIG. 1  is a cross-sectional view of an exemplary a vacuum processing chamber in having one embodiment of a sealing groove; 
         FIG. 2  is a bottom view of a lid of the vacuum processing chamber, containing the sealing groove; 
         FIG. 3  is an enlarged partial top view of the sealing groove shown in  FIG. 2 ; 
         FIG. 4  is a sectional view of the sealing groove and taken along section line A-A of  FIG. 3 ; and 
         FIG. 5  is a sectional view of the sealing groove and taken along section line B-B of  FIG. 3 . 
     
    
    
     To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. 
     DETAILED DESCRIPTION 
     Embodiments disclosed herein generally relate to seal technology for enabling pressure control in vacuum processing chambers over wide operating temperature ranges. The seal technology described herein includes a sealing groove which accommodates seal expansion while being able to retain the seal in the groove at both low and high temperature conditions. Although the sealing groove is disclosed utilized in a vacuum processing chamber, the sealing groove may be utilized to retain a seal between other surfaces, particularly in applications where the seal is exposed to elevated temperatures. 
     A variety of vacuum processing chambers may be modified to incorporate the sealing groove described herein. For example, the sealing groove of the present invention may be used in a chemical vapor deposition (CVD) chamber, physical vapor deposition (PVD) chamber, etch chamber, annealing chamber, furnace, plasma treating chambers, transfer chambers, load lock chambers and implantation chambers, among others. 
       FIG. 1  illustrates an exemplary vacuum processing chamber  100  having a sealing groove  101 . The exemplary vacuum processing chamber  100  is configured as an etch processing chamber and is suitable for removing one or more material layers from a substrate. The vacuum processing chamber  100  includes a chamber body  105  enclosed by a chamber lid assembly  110  and defining a processing chamber volume  152  therein. The chamber body  105  has sidewalls  112  and a bottom  118  which may be coupled to a ground  126 . The sidewalls  112  have a top surface  132 . The dimensions of the chamber body  105  and related components of the vacuum processing chamber  100  are not limited and generally are proportionally larger than the size of a substrate  120  to be processed. Examples of substrate sizes include, among others, substrates  120  with a 150 mm diameter, 200 mm diameter, 300 mm diameter and 450 mm diameters, among others. 
     The chamber body  105  may be fabricated from aluminum or other suitable materials. A substrate access port  113  is formed through the sidewall  112  of the chamber body  105 , facilitating the transfer of a substrate  120  into and out of the vacuum processing chamber  100 . The access port  113  may be coupled to a transfer chamber and/or other chambers of a substrate processing system (both not shown). 
     A gas source  160  provides process gases into the processing chamber volume  152  through an inlet  161  formed through the chamber body  105  or lid assembly  110 . In one or more embodiments, process gases may include etchants and passivation gases. 
     A showerhead  114  may be coupled to the lid assembly  110 . The showerhead  114  has a plurality of gas delivery holes  150  for distributing process gases entering the chamber volume  152  through the inlet  161 . The showerhead  114  may be connected to an RF power source  142  through a match circuit  141 . The RF power provided to the showerhead  114  energizes the process gases exiting the showerhead  114  to form plasma within the processing chamber volume  152 . 
     A substrate support pedestal  135  is disposed below the showerhead  114  in the processing chamber volume  152 . The substrate support pedestal  135  may include an electro-static chuck (ESC)  122  for holding the substrate  120  during processing. The ring assembly  130  is disposed on the ESC  122  and along the periphery of the substrate support pedestal  135 . The ring assembly  130  is configured to control the distribution of etching gas radicals at the edge of the substrate  120 , while shielding the top surface of the substrate support pedestal  135  from the plasma environment inside the vacuum processing chamber  100 . 
     The ESC  122  is powered by an RF power source  125  integrated with a match circuit  124 . The ESC  122  comprises an electrode  134  embedded within a dielectric body  133 . The RF power source  125  may provide a RF chucking voltage of about 200 volts to about 2000 volts to the electrode  134 . The RF power source  125  may also be coupled to a system controller for controlling the operation of the electrode  134  by directing a DC current to the electrode for chucking and de-chucking the substrate  120 . 
     A cooling base  129  is provided to protect the substrate support pedestal  135  and assists in controlling the temperature of the substrate  120 . The cooling base  129  and ESC  122  work together to maintain the substrate temperature within the temperature range required by the thermal budget of the device being fabricated on the substrate  120 . The ESC  122  may include heaters for heating the substrate, while the cooling base  129  may include conduits for circulating a heat transfer fluid to sinking heat from the ESC  122  and substrate disposed thereon. For example, the ESC  122  and cooling base  129  may be configured to maintain the substrate  120  at a temperature of about minus 25 degrees Celsius to about 100 degrees Celsius for certain embodiments, at a temperature of about 100 degrees Celsius to about 200 degrees Celsius temperature range for other embodiments, and at about 200 degrees Celsius to about 500 degrees Celsius for yet still other embodiments. In one embodiment, the substrate  120  temperature is maintained at 15 to 40 degrees Celsius by the ESC  122  and cooling base  129 . 
     Lift pins (not shown) are selectively moved through the substrate support pedestal  135  to lift the substrate  120  above the substrate support pedestal  135  to facilitate access to the substrate  120  by a transfer robot or other suitable transfer mechanism. 
     A cathode electrode  138  is disposed in the substrate support pedestal  135  and connected to an RF power source  136  through an integrated match circuit  137 . The cathode electrode  138  capacitively couples power to the plasma from below the substrate  120 . In one embodiment, the RF power source  136  provides the cathode electrode  138  with between about 200 W to about 1000 W of RF power. 
     A pumping port  145  may be formed through the sidewall  112  of the chamber body  105  and connected to the chamber volume through the exhaust manifold  123 . A pumping device  170  is coupled to the processing chamber volume  152  through the pumping port  145  to evacuate and control the pressure therein. The exhaust manifold  123  has a baffle plate  154  to control the uniformity of the plasma gas drawn into the exhaust manifold  123  from the pumping device  170 . The pumping device  170  may include one or more pumps and throttle valves. The pumping device  170  and chamber cooling design enables high base vacuum (about 1×E −8  Torr or less) and low rate-of-rise (about 1,000 mTorr/min) at temperatures suited to thermal budget needs, e.g., about −25 degrees Celsius to about +500 degrees Celsius. In one embodiment, the pumping device enables a vacuum pressure between 10 and 30 mT. 
     During processing, gas is introduced into the vacuum processing chamber  100  to form a plasma and etch the surface of the substrate  120 . The substrate support pedestal  135  is biased by the power source  136 . Power source  142  energizes the process gas, supplied by the gas source  160 , leaving the showerhead  114  to form the plasma. Ions from the plasma are attracted to the cathode in the substrate support pedestal  135  and bombard/etch the substrate  120  until a desired structure is formed. 
     The lid assembly  110  is moveable between an open position and a closed position to facilitate service to the interior of the vacuum processing chamber  100 . One of the lid assembly  110  and the chamber body  105  includes one or more sealing grooves  101 . The sealing groove  101 , shown formed in a bottom surface  102  of the lid assembly  110 , has a seal  106  disposed therein. The seal  106  may be an O-ring or other suitable seal, the material of which is selected for the expected process conditions. When the lid assembly  110  is in the open position, a portion of the seal  106  extends below the bottom surface  102  of the lid assembly  110 . When the lid assembly  110  is moved into the closed position, the seal  106  is compressed between the top surface  132  of the chamber body  105  and the lid assembly  110 , thereby sealing the lid assembly  110  to the chamber body  105 . The compression of the seal  106  is sufficient to prevent the flow of gas from outside the chamber body  105  from entering the processing chamber volume  152  when vacuum conditions are present within the chamber volume  152 . 
     The configuration of the sealing groove  101  in the lid assembly  110  may be selected in response to the processing parameters utilized to etch a particular material disposed on the substrate  120 , which governs the selection of the material and geometry for the seal  106 . The configuration of the sealing groove  101  permits the Seal  106  to thermally expand and contract without extruding from the sealing groove  101  while maintaining 10 mTorr to about 30 mTorr of pressure at about 40 degrees Celsius or greater. The robust seal between the chamber body  105  and the lid assembly  110 , provided by the combination of the sealing groove  101  and the seal  106 , allows a wider window for the plasma processes which prevent contamination associated with seal failure. To better understand how the function of sealing groove  101  enables chamber operation at elevated temperatures, the sealing groove  101  is described in greater detail with reference to  FIG. 2 . 
       FIG. 2  is a view of the lid bottom  102 , illustrating the sealing groove  101 . The lid bottom  102  has a center  210  about which an outside edge  230  and outer edge  220  are concentrically aligned. An outer surface  225  of the lid assembly bottom  122  between the outer edge  220  and outside edges  230  may be flat to receive the sealing groove  101 . The sealing groove  101  is formed into the outer surface  225  in a location that aligns the sealing groove  101  with the top  132  of the chamber body  105  (as shown in  FIG. 1 ) so that the seal  106 , retained in the sealing groove  101 , compresses between the lid assembly  110  and the chamber body  105  when the lid assembly  110  is in the closed position. 
     The outer surface  225  may include through holes  232  near the outside edge  230 . Through holes  232  accepts a fastener and aligns with a fastener receiver (not shown) deposed in the top  122  of the sidewalls  112 . The fasteners may be used to secure the lid assembly  110  to the chamber body  105 . In one embodiment, there are 8 evenly spaced through holes  232  in the outer surface  225 . 
     The sealing groove  101  may be circular and concentrically aligned with the lid bottom  102 . The sealing groove  101  may have a radius  240  measured from the center  210  to an outer perimeter  265  of the sealing groove  101 . Alternatively, the sealing groove  101  may be other plan view geometries. For instance, the sealing groove  101  may have square, rectangular, octagonal, polygonal, or other plan view form suitable for aligning with the sidewalls of the substrate chamber. 
     The sealing groove  101  has an inner perimeter  260 , proximate the center  210 , and the outer perimeter  265 , nearer to the outer edge  220 , both of which are concentric about the center  210 . The inner perimeter  260  is circular in shape while the outer perimeter  265  is mostly circular with one or more small tabs  201  extending into the sealing groove  101 . The outer perimeter  265  may have an outer diameter that varies between about 200 mm and about 1000 mm, depending on the size of the chamber body  105  which the sealing groove  101  interfaces with. In one embodiment, the sealing groove  101  may have an outer diameter of about 500 mm and an outer perimeter  265  with a length of about 1,570 mm. 
     Alternately, the sealing groove  101  may have a square geometry. All four sides of the sealing groove may be of equal length that varies between about 200 mm and about 1000 mm, depending on the size of the chamber body  105  which the sealing groove  101  interfaces with. In one embodiment, the square sealing groove  101  may have a length of about 900 mm along one side and an outer perimeter  265  with a length of about 3,600 mm. 
     The tab  201  is a small protrusion extending from the outer perimeter  265  of the seal groove. Portions of the sealing groove  101  do not have the tab  201 . For instance, an open portion  202  (i.e. portion of the sealing groove  101  unrestricted by a tab  201 ) is shown adjacent to tabs  201 . The open portion  202  and tab  201  alternate along the outer perimeter  265  of the sealing groove  101 . For example, the outer perimeter  265  of the sealing groove  101  may have 12 evenly spaced tabs  201  separated by open portions  202 . 
     An enlarged view of the tab  201  as well as the open portion  202  is in  FIG. 3 . The tabs  201  may have a length  310  measured from the intersection of the tab  201  with the outer perimeter  265 . The length  310  of the tab  201  may vary between about 2 mm and about 100 mm, depending on the size of the sealing groove  101 , the materials of the seal, and expected operating conditions. In one embodiment, the outer perimeter  265  of the sealing groove  101  has a length of about 1,570.80 mm, the lengths  310  the tabs  201  along the outer perimeter  265  may each be about 17.44 mm while a length for each of the 12 open portions  202  between adjacent tabs  201  may be about 113 mm. 
     The tab  201  has a protrusion  311  that extends radially inward from the outer perimeter  265 . In another embodiment, the tab  201  may have a protrusion  311  which may extend radially outward from the inner perimeter  260 . The protrusion  311  of the tab  201  has a rounded curve  320  at a beginning  350  and an end  351  of the tab  201  which connects the tabs  201  to the outer perimeter  265 . The rounded curve  320  breaks the sharp edge at the beginning  350  and the end  351  so as to not damage the seal  106  placed in the sealing groove  101 . In one embodiment, the rounded curve  320  has a radius of about 1 mm. 
       FIG. 4  is a cross sectional profile of the sealing groove  101 , taken along a section line A-A of  FIG. 3 , taken through the tabs  201 . As shown in  FIG. 4 , the sealing groove  101  has a full dovetail profile  400  that incorporates the tab  201 . The full dovetail profile  400  may be substantially symmetric about a center axis  401 . The full dovetail profile  400  includes an opening  470  that breaks the bottom surface  102  of the lid assembly  110 . 
     The opening  470  has a rounded edge  420  along the inner perimeter  260  and the outer perimeter  265 . The rounded edge  420  may have a radius of about 0.38 mm. The rounded edge  420  starts at the bottom surface  102  of the lid assembly  110  and concludes at the opening  470 . The opening  470  is the narrowest portion of the full dovetail profile  400 . In one embodiment, the opening  470  is about 4.58 mm. However, the width of the opening  470  is dependent on the size and material selection for the seal  106 . The opening  470  is selected to hold the seal  106  into the sealing groove  101  under the range of conditions and temperatures the lid assembly  110  may experience. 
     The full dovetail profile  400  expands below the opening  470  to include tapered walls  425 . The walls  425  have an angle  460  defined with a bottom  420  of the sealing groove  101 . The angle  460  of the walls  425  may be the same for both sides of the full dovetail profile  400 . In one embodiment, the angle  460  may be about 60°. However, it should be appreciated that the angle  460  may vary in response to different seal profiles, among other factors. 
     The walls  425  intersect the bottom  426  at a bottom radius  430 . The bottom radius  430  starts at a depth  530  (shown in  FIG. 5 ) measured perpendicular to the bottom surface  102  and outer surface  225  of the lid assembly  110 . The depth  530  is measured from the outer surface  225  along the outer perimeter  265 . The depth  530  may vary between about 3.56 mm and about 3.64 mm. In one embodiment, the depth  530  of the sealing groove  101  is about 3.60 mm. 
     Along the inner perimeter  260 , the bottom surface  102  is recessed below the plane formed by the outer surface  225 . Therefore, when the lid assembly  110  is in a closed position, the outer surface  225  is closer than bottom surface  102  to the top  122  of the sidewall  112  to prevent the lid assembly  110  from contacting the chamber body  105  on the vacuum side of the seal thereby minimizing the potential for particle generation. In one embodiment, a difference  411  from the plane of the bottom surface  102  to the plane of the outer surface  225  may be about 0.25 mm. 
     The bottom radius  430  is present at both ends of the seal groove bottom  426 . The bottom radius  430  may have a radius of about 0.79 mm. However, it should be appreciated that as the size of the wall  425  and bottom  426  may change, bottom radius  430  may also be different. The seal groove bottom  426  may be substantially parallel to both the bottom surface  102  and the outer surface  225 . The bottom  420  may have a circular surface roughness of about 0.4 mm. A depth  410  of the bottom  426  measured from the outer surface  225  may vary between about 4.12 mm and about 4.22 mm. In one embodiment, the depth  410  of the sealing groove  101  is about 4.17 mm. 
     It should be appreciated that the full dovetail profile  400  of the sealing groove  101  may be substantially symmetrical about the center axis  401 . The full dovetail profile  400  has the opening  470  and the bottom  426  bisected by the center axis  401 . However this is not the case for the open portion  202 .  FIG. 5  is a cross sectional profile of the sealing groove  101  taken along section lines B-B of  FIG. 3  which does not cut through tab  201 .  FIG. 5  illustrates a half dovetail profile  500  that the sealing groove  101  has in the open portions  202 . 
     The half dovetail profile  500  has an opening  570  which is larger than the opening  470  of the full dovetail profile  400  shown in  FIG. 4 . The half dovetail profile  500  has a bottom  501  which is substantially the same as bottom  401 . The bottoms  426 ,  501  are also ex-planar. A section line  511  is substantially perpendicular to and bisects the opening  570 . However, the section line  511  is not aligned with center axis  401 . The section line  511  extends through the middle of the opening  570  and to the bottom  501  dividing the bottom  501  into an x portion  590  and a y portion  595 . 
     The half dovetail profile  500  has an outer portion  505  and an inner portion  506  defined by the partitioning of the half dovetail profile  500  by the section line  511 . The inner portion  506  is substantially similar to that of the corresponding portion of the full dovetail profile  400  as shown in  FIG. 4 , whereas the outer portion  505  is substantially dissimilar. Therefore, unlike the full dovetail profile  400 , the outer portion  505  of the half dovetail profile  500  is not symmetric with the inner portion  506 . 
     The half dovetail profile  500  has a wall  525  which intersects the bottom  501  with a radius  510 . The radius  510  is substantially similar to the bottom radius  430 . In one embodiment the radius  510  is about 0.79 mm. However, instead of the both walls  425 ,  525  having the angle  460 , the wall  525  is substantially perpendicular to the bottom surface  102  and the bottom  501  of the sealing groove  101 . Thus, the half dovetail profile  500  has an x portion  490  which is larger than the x portion  490  of the full dovetail profile  400 . The larger x portion  490  in the half dovetail profile  500  allows additional space in the sealing groove  101  for the Seal  106  to expand while under elevated thermal conditions. The opening  570  may vary between about 5 mm and about 12 mm in width, depending on the size of the sealing groove  101 . In one embodiment, the opening  570  may be about 5.71 mm wide. 
     The wall  525  has a rounded edge  540  starting at the opening  570  and ending at the outer surface  225  portion of the lid assembly  110 . The rounded edge  540  is substantially similar to rounded edge  420 . In one embodiment the rounded edge  540  may have a radius of about 0.38 mm. 
     Referring to  FIGS. 3, 4 and 5 , the non-continuous profile for the half dovetail profile  500  (shown as section B-B) and full dovetail profile  400  (shown as section A-A) generate a series of tabs  201  and open portions  202 . The tabs have substantially similar x portions  490  and y portions  495  and open portions  202  have substantially dissimilar x portions  490  and y portions  495 . It should be appreciated that the half dovetail profile  500  are the open portions  202  yet determine the location of the tabs  201  on either the inner perimeter  260 , the outer perimeter  265 , or in some embodiments, both the inner and outer perimeter  260 ,  265  together. In one embodiment, the x portions  490  are greater than the y portions  495  and causes the formation of tabs  201  on the inner perimeter  260  of the sealing groove  101 . In an alternate embodiment, the x portions  490  are less than the y portions  495  and causes the formation of tabs  201  on the outer perimeter  265  of the sealing groove  101 . 
     Referring back to  FIG. 2 , it can now be appreciated that the tabs  201  and the open portions  202  accommodate expansion of the seal  106  while together making up a continuous profile for the sealing groove  101 . The tabs  201  hold the seal  106  at the lower temperatures while the open portions  202  allow for the expansion of the seal  106  when heated. Alternately, when the seal expansion may be large, the tabs  201  and the open portions  202  may not make a continuous surface. The open portions  202  may have an even larger diameter than the tabs  201 . In this manner, the seal  106  is retained in the sealing groove  101  throughout a wide temperature range, without damage, while allowing for a robust sealing of the vacuum processing chamber. 
     While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof.