Abstract:
The present invention uses hybrid ball-lock devices as an alternate for threaded fasteners. Parts of the fastener exposed directly to the plasma act as a shield for the remaining pieces of the fastener or are used as a material to actually enhance plasma characteristics. The present invention also provides consistent electrical and mechanical contact between parts, without the use of any tools.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to and is related to U.S. Provisional Application Ser. No. 60/466,416, filed on Apr. 30, 2003. The content of this application is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of the Invention  
     This invention relates to an improved component for a plasma processing system, and more particularly, to hardware fasteners for internal chamber parts in a plasma processing chamber such as fasteners using actuating type or spring plunger type hybrid ball-lock devices. 
     The fabrication of integrated circuits in the semiconductor industry typically employs plasma to create and assist surface chemistry within a plasma reactor necessary to remove material from and deposit material to a substrate. In general, plasma is formed with the plasma reactor under vacuum conditions by heating electrons to energies sufficient to sustain ionizing collisions with a supplied process gas. Moreover, the heated electrons can have energy sufficient to sustain dissociative collisions and, therefore, a specific set of gasses under predetermined conditions (e.g. chamber pressure, gas flow rate etc.) are chosen to produce a population of charged species and chemically reactive species suitable to the particular process being performed within the chamber, e.g. etching processes where materials are removed from the substrate or deposition where materials are added to the substrate. 
     Although the formation of a population of charged species (ions, etc.) and chemically reactive species is necessary for performing the function of the plasma processing system (i.e. material etch, material deposition, etc.) at the substrate surface, other component surfaces on the interior of the plasma processing chamber are exposed to the physically and chemically active plasma and, in time, can erode. The erosion of exposed components in the plasma processing system can lead to a gradual degradation of the plasma processing performance and ultimately to complete failure of the system. 
     A need exists for an attachment apparatus that minimizes the hardware necessary to assemble internal components of a plasma-processing chamber. Removal of parts secured with hardware, especially threaded hardware, is time consuming, requires hand or power tools and tends to create particles as the hardware is removed and subsequently replaced. Each piece of hardware adds another part that must be procured, inspected, cleaned, assembled and controlled. 
     When installing parts using threaded hardware, consistent assembly is difficult to accomplish. To obtain consistent interface between parts, secured by threaded fasteners, the fasteners must be secured to specific torque requirements. This also requires additional tools. A need exists to consistently assemble internal plasma processing parts without special tools, processes and inspections. 
     Most current plasma tools utilize threaded hardware to secure internal chamber parts as necessary. Hardware is secured in place and may require specific torque specifications. Usually, extra parts are required to shield hardware after installation. The shield parts can cover multiple hardware devices or can be made to cover each piece of hardware individually. 
     Known plasma processing chambers employ a minimum number of threaded fasteners which can be shielded from the plasma utilizing associated shielding devices. 
     SUMMARY OF THE INVENTION 
     These and other problems are addressed by the present invention, which provides an apparatus and method for attaching replaceable parts within a process chamber such that the need to clean the chamber is reduced. 
     The present invention utilizes an actuating hybrid ball-lock device or a hybrid spring-plunger type ball-lock device to reduce the need for threaded fasteners. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above-noted and other aspects of the present invention will become more apparent from a detailed description of preferred embodiments when read in conjunction with the drawings, wherein: 
         FIG. 1  represents a cut-away view of a plasma process chamber in which a hybrid ball-lock device is shown; 
         FIG. 2A  represents a close-up cut-away view of a plasma process chamber in which the internal constitution of an actuating hybrid ball-lock device is shown in more detail; 
         FIG. 2B  depicts a close-up view of the construction of a hybrid ball-lock device; 
         FIG. 2C  depicts a sectional view of the embodiment of  FIG. 2B  showing location of assembly retaining pins; 
         FIG. 2D  depicts an alternate attachment of a release button to the hybrid ball-lock device; 
         FIG. 3A  represents a side view an embodiment of an actuating hybrid ball-lock device wherein the corrosion resistant steel (CRES) shaft is attached to the head with thin clamping fingers of CRES material; 
         FIG. 3B  represents a sectional view of the embodiment of  FIG. 3A  showing internal components; 
         FIG. 3C  represents a sectional view of the embodiment of  FIG. 3A  showing head, clamping fingers and CRES shaft; 
         FIG. 4A  represents a plan view of an embodiment of an actuating hybrid ball-lock device wherein a head is brazed to a CRES shaft; 
         FIG. 4B  represents a sectional view of the embodiment of  FIG. 4A  showing internal components; 
         FIG. 5A  represents a close-up cutaway view of a plasma process chamber in which the internal constitution of a hybrid spring plunger ball-lock device is shown in more detail; 
         FIG. 5B  represents a close up view of the embodiment of  FIG. 5A  in which the construction of a hybrid spring plunger ball-lock device is shown in more detail; 
         FIG. 5C  represents an embodiment of a hybrid spring plunger ball-lock device wherein a head is thermally fit into a CRES sleeve; 
         FIG. 5D  represents an embodiment of a hybrid spring plunger ball-lock device wherein a head is brazed to a CRES shank; 
         FIG. 5E  represents an embodiment of a hybrid spring plunger ball-lock device wherein the spring and balls are retained in place with a sleeve attached to the head by thin clamping fingers of CRES material; 
         FIG. 5F  represents a sectional view of the embodiment of  FIG. 5E  showing head and sleeve with associated clamping fingers; and 
         FIG. 5G  represents a sectional view of the embodiment of  FIG. 5E  showing internal components. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     With reference to  FIG. 1 , a plasma-processing device  10  is shown. The plasma processing device  10  can include a process chamber  20 , a chuck assembly  30 , an inject plate  40 , a ceramic insulator  50 , and an upper electrode including an upper electrode portion  60 , and a lower electrode portion  70 . Baffle plates  80  can also be included in the construction of the plasma-processing device  10 . The plasma-processing device  10  is typically configured such that an upper housing  90  is electrically insulated from the upper electrode portion  60  and the lower electrode portion  70  by the ceramic insulator  50 . 
     The plasma-processing device  10  has a hybrid ball-lock device  100 . In  FIG. 1 , the hybrid ball-lock device  100  is depicted as maintaining secure contact between the inject plate  40  and the assembly made up of the upper electrode portion  60 , lower electrode portion  70 , and baffle plates  80 . Use of the hybrid ball-lock device  100  can allow the reduction in the number of threaded fasteners that must be used in the plasma-processing device  10 . The hybrid ball lock-device  100  can be used to secure any of the other parts of the plasma-processing device  10  together, which negates the need for threaded fasteners. Additionally, a hybrid spring plunger or detent pin could have been used in place of a hybrid ball-lock device in this application 
     As can more clearly be seen in  FIG. 2A , a cutaway view of the hybrid ball-lock device  100  is represented. The hybrid ball-lock device is comprised of an actuating shaft  200 , axial spring  210 , release button  220 , at least one retaining ball  230 , head  240 , and CRES fastener housing  250  and at least one retaining pin  275 . The inject plate  40  has a first hole  41  with a first diameter  42 . The lower electrode has a third hole  70  with a third diameter  71 . The upper electrode  60  has a second hole  61 . The second hole  61  has a recessed area  63  with a second diameter  62 . The at least one retaining ball  230  moves into the recessed area  63 . At a boundary of the recessed area  63 , a seam  292  begins. The seam  292  is sealed by a compressible seal  291 . 
     As more clearly seen in  FIG. 2B  and  FIG. 2C , the CRES fastener housing  250  is constructed such that one or more cross-drilled holes  260  are drilled perpendicular to an axis  270  of the CRES fastener housing  250 . At assembly of the ball-lock device  100 , each retaining ball  230  is inserted into the cross-drilled holes  260  such that they can freely move therethrough until reaching an area of smaller diameter near the outside surface of the CRES fastener housing  250  and are subsequently retained therein. 
     Each retaining pin  275  helps provide secured contact between head  240  and CRES fastener housing  250 . In this embodiment at least one retaining pin  275  is installed using locational interference or thermal fits. 
     The actuating shaft  200  is retained in the ball-lock device  100  by an internal head feature  265  mating to a bore in the fastener housing  250 , an axial spring  210  and the release button  220 , as shown. The axial compression spring  210  provides a constant axial force against the release button  220 ; therefore, the release button must be secured to the actuating shaft  200 . 
     The last operation completed as the ball-lock device is assembled, is mechanically pinning the release button  220  to the actuating shaft  200 . This is accomplished mechanically with locational interference or thermal fits commonly known to a person having ordinary skill in the art, through a cross-drilled access hole  295  in head  240 . Also, retaining pin  297 , is shown to facilitate contact between the release button  220  and the actuating shaft  200 . 
     As shown in  FIG. 2D , alternately, a method of attaching the release button  220  to the actuating shaft  200  can be used in which pinning devices are not necessary. This method requires a locking or non-locking insert  275  to be installed in the release button  220  which mates to a threaded end  285  of actuating shaft  200 . A slot in the head feature  265  of the actuating shaft  200  opposite the threaded end  285  would allow tightening of the two parts to particular torque requirements as necessary at the assembly of the hybrid ball-lock device  101 . 
     As shown in  FIG. 1  and  FIG. 2B  when the hybrid ball-lock device  100  is actuated, the actuating shaft  200  moves until relieved section  280  of the actuating shaft  200  becomes adjacent to retaining ball  230 . As retaining ball  230  moves to the relieved section  280  of the actuating shaft  200 , the hybrid ball-lock device  100  can then be removed from the plasma-processing device  10 . 
     An electrical contact device  290  is shown in  FIGS. 1 and 2A  as well. The electrical contact device  290  ensures consistent electrical and mechanical contact between the inject plate  40  and the lower electrode  70  when the ball-lock assembly  100  is installed in the plasma-processing device. The electrical contact device  290  may or may not be used with various embodiments of the present invention. 
     By way of example, in this configuration, the release button  220  can be made of a ceramic material, quartz, silicon, silicon carbide, carbon, Vespel, Teflon, anodized aluminum, fine coated ceramic covering a metallic material or other materials suitable for plasma processing applications. Any number of shapes or lengths can be used for the release button  220 . 
     As is known in the art, a getter material is added during the plasma process in small amounts to adsorb impurities, whereas a scavenging material can cause introduction of a specific material to the plasma process to affect process chemistry. For example, when silicon is used for the release button  220 , the release button  220  can be partially consumed, hence, introducing silicon to the plasma process and, consequently, help to modify the plasma process. Therefore, the hybrid ball-lock device can make the plasma process even more efficient. 
       FIG. 3A ,  FIG. 3B  and  FIG. 3C  depict a further embodiment of the present invention in which a hybrid ball-lock device  300  is comprised of an actuating shaft  305 , axial spring  310 , release button  320 , at least one retaining ball  330 , head  340 , and CRES fastener housing  350 . 
     As more clearly seen in  FIG. 3B , the CRES fastener housing  350  is constructed such that two or more cross-drilled holes  360  are drilled perpendicular to an axis  370  of the CRES fastener housing  350 . At assembly of the hybrid ball-lock device  300 , each retaining ball  330  is inserted into the cross-drilled holes  360  such that they can freely move therethrough until reaching an area of smaller diameter near the outside surface of the CRES fastener housing  350  and are subsequently retained therein. As shown in  FIG. 3A ,  FIG. 3B  and  FIG. 3C , the fastener housing is constructed such that two or more thin retaining fingers  361  are fashioned to mate to a groove  362  in head  340 . The fingers  361  secure the fastener housing  350  to the head  340  as the hybrid ball-lock device  300  is assembled together. The retaining fingers  361  are an alternate embodiment to the retaining pins  275  described in the first embodiment of the hybrid ball-lock device. 
     The actuating shaft  305  is retained in the ball-lock device  300  by an internal head feature  365  mating to a bore in the fastener housing  350 , an axial spring  310  and the release button  320 , as shown. The axial compression spring  310  provides a constant axial force against the release button  320 ; therefore, the release button must be secured to the actuating shaft  305 . The last operation completed as the ball-lock device is assembled, is mechanically pinning the release button  320  to the actuating shaft  305 . This is accomplished mechanically with locational interference or thermal fits commonly known to a person having ordinary skill in the art, through a cross-drilled access hole  390  in head  340 . Also, as depicted in  FIG. 3B , retaining pin  397 , is shown to facilitate contact between the release button  320  and the actuating shaft  305 . 
     As described above, an alternate method of attaching the release button  320  to the actuating shaft  305  can be accomplished with an insert located in the release button and a mating thread located on the actuating shaft. 
     As the hybrid ball-lock device  300  is actuated, the actuating shaft  305  moves until relieved section  380  of the actuating shaft  305  becomes adjacent to retaining ball  330 . As retaining ball  330  moves to the relieved section  380  of the actuating shaft  305 , the ball-lock device  300  can then be removed from the plasma-processing device  10 . 
       FIG. 4A  and  FIG. 4B  depict a further embodiment of the present invention in which an actuating shaft  405  is used in hybrid ball-lock device  400 . This further embodiment is comprised of an actuating shaft  405 , CRES fastener housing  450 , head  440 , at least one retaining ball  430 , release button  420 , axial compression spring  410 , retaining pin  470 , and kovar braze joint  480 . The brazed joint  480  is an alternate embodiment to the retaining pin  275  described in the first embodiment of the hybrid ball-lock device. 
     The axial compression spring  410  provides a constant axial force against the release button  420 ; therefore, the release button must be secured to the actuating shaft  405 . The last operation completed as the ball-lock device is assembled, is mechanically pinning the release button  450  to the actuating shaft  410 . This is accomplished mechanically with locational interference or thermal fits commonly known to a person having ordinary skill in the art, through a cross-drilled access hole  490  in head  440 . Also, retaining pin  470  is shown to facilitate contact between the release button  450  and the actuating shaft  405 . 
     As described above an alternate method of attaching the release button  420  to the actuating shaft  405  can be accomplished with an insert located in the release button and a mating thread located on the actuating shaft. 
     Again as before, the hybrid ball-lock device  400  is actuated, the actuating shaft  405  moves until relieved section  485  of the actuating shaft  405  becomes adjacent to retaining ball  430 . As retaining ball  430  moves to the relieved section  485  of the actuating shaft  405 , the hybrid ball-lock device  400  can then be removed from the plasma-processing device  10 . 
       FIG. 5A  represents a cutaway view of a plasma process chamber  505  in which the internal constitution of a hybrid spring plunger ball-lock device  500  is more clearly depicted. The hybrid spring plunger ball-lock device  500  is inserted into a recess  590  in the inject plate  525  and the lower electrode portion  540 . At least one sub-recess  595  is located in the recess  590 . Each sub-recess  595  corresponds to each retaining ball  530 . The recess  590  is shaped similarly to the CRES shank  510  and is intended to receive the CRES shank  510 . The diameter of the recess  590  is large enough to accept the CRES shank  510 . The sub-recess  595  extends away from the axis  570  of the hybrid spring plunger device  500 . When the hybrid spring plunger ball-lock device  500  initially engages the recess  590 , each retaining ball  530  is pushed toward the axis  570  of the hybrid spring plunger ball-lock device  500  by the recess  590 . Once each retaining ball  530  reaches the sub-recess  595  each retaining ball  530  is pushed out away from the axis  570 , to its normal position, thereby locking the hybrid spring plunger ball-lock device  500  in place. To remove the hybrid spring plunger ball-lock device  500  from recess  590 , one need only grasp head  520  and pull with enough force to cause each retaining ball  530  to withdraw from sub-recess  595  toward axis  570 . 
     As can be more clearly seen in  FIG. 5B , a hybrid spring plunger ball-lock device  600  is depicted in which a CRES shank  610  and a head  620  are mechanically pinned together with a retaining pin  630 . Retaining pin  630  can be fabricated from CRES or aluminum. The head  620  can be ceramic, silicon, anodized aluminum, quartz, silicon carbide, carbon, Vespel, Teflon, or fine coated ceramic or metallic materials. At least one retaining ball  640  is located in the CRES shank  610 . The retaining ball  640  is pushed toward the outer surface of the CRES shank  610  by a transverse spring  650 . 
     The CRES shank  610  is substantially cylindrical and is constructed with a cross drilled hole  660  perpendicular to the axis  670  of the hybrid spring plunger ball-lock device  600 . The cross-drilled hole  660  can have any diameter as long as the diameter near the outer surface of the CRES shank  610  is smaller than the diameter of each retaining ball  640 . Each retaining ball  640  and transverse spring  650  are retained in the CRES shank  610  by the smaller diameter of the cross-drilled hole  660 . 
     The cross-drilled hole  660  has a substantially uniform diameter during the manufacture of the CRES shank  610 . After the manufacture of the CRES shank  610 , the cross-drilled hole  660  is processed to have said smaller diameter near the outer surface of the CRES shank  610 . The process of modifying the cross-drilled hole  660  after assembly of the transverse spring  650  and retaining ball  640  to the CRES shank  610  is accomplished with common metal cold working techniques. 
     As can be seen in  FIG. 5C , a further embodiment of the present invention involves a hybrid spring plunger type ball-lock device  700 . The hybrid spring plunger type ball-lock device is comprised of a head  710 , at least one retaining ball  720 , a CRES sleeve  730 , and a transverse spring  740 . As with the previous embodiments, the head  710  can be ceramic, silicon, quartz, or anodized aluminum. The head  710  can also be a ceramic or a metallic material covered in fine-coated ceramic material. The CRES sleeve  730  is thermally fit to the head  710  in this embodiment and captivates each retaining ball  720  and transverse spring  740  in place in cross-drilled hole  760 . 
     A further embodiment of the present invention employs the use of a hybrid spring plunger ball-lock device  800  and is depicted in  FIG. 5D . The hybrid spring plunger ball-lock device  800  is comprised of a head  810 , a CRES shank  820 , a transverse spring  830 , and at least one retaining ball  840 . The head  810  can be fabricated from some alumina alloy, other ceramic, anodized aluminum, or some metallic or ceramic material coated with some fine coating ceramic material. 
     The CRES shank  820  is substantially cylindrical and is constructed with a cross drilled hole  850  perpendicular to axis  860  of the hybrid spring plunger ball-lock device  800 . The cross drilled hole  850  can have any diameter as long as the diameter near the outer surface of the CRES shank  820  is smaller than the diameter of the retaining ball  840 . The retaining ball  840  and transverse spring  830  are retained in the CRES shank  820  by the smaller diameter of the cross-drilled hole  850 . 
     The cross-drilled hole  850  has a substantially uniform diameter during the manufacture of the CRES shank  820 . After the manufacture of the CRES shank  820 , the cross-drilled hole  850  is processed to have said smaller diameter near the outer surface of the CRES shank  820 . The process of modifying the cross drilled hole  850  after assembly of the transverse spring  830  and retaining ball  840  to the CRES shank  820  is accomplished with common metal cold working techniques. 
     Mating of the CRES shank  820  with head  810  is accomplished with common brazing techniques. This process is common to persons having ordinary skill in the art. Kovar is the preferred brazing material to form a braze joint between the CRES shank  820  and head  810 . However, kovar is not the only brazing alloy possible. Invar and other alloy brazing alloys containing iron, nickel and cobalt can be used. 
     A further embodiment of the present invention employs the use of a hybrid spring plunger ball-lock device  900  and is depicted in  FIG. 5E ,  FIG. 5F  and FIG G. The hybrid spring plunger ball-lock device  900  is comprised of a head  910 , a CRES shank  920 , a transverse spring  930 , and at least one retaining ball  940 . The head  910  can be fabricated from some alumina alloy, other ceramic, anodized aluminum, or some metallic or ceramic material coated with some fine coating ceramic material. 
     The CRES shank  920  is constructed such that two or more thin retaining fingers  961  are fashioned to mate to a groove  962  in head  910 . The fingers  961  secure the CRES shank  920  to the head  910  as the hybrid spring plunger ball-lock device  900  is assembled together. 
     When assembling an exemplary system of the present invention using either hybrid spring plunger ball-lock type device  600 , hybrid spring plunger ball-lock type device  700 , hybrid spring plunger ball-lock type device  800  or hybrid spring plunger ball-lock type device  900  or a combination thereof, components including inject plate  525 , baffle plate  535 , lower electrode portion  540 , and upper electrode portion  550  can be joined together using the hybrid spring plunger ball-lock device  600 , hybrid spring plunger ball-lock device  700 , hybrid spring plunger ball-lock device  800 , or hybrid spring plunger ball-lock device  900 . As understood by one of ordinary skill in the art, any subset of these components can be fastened together using a ball-lock device. 
     As is known to one of ordinary skill in the art, any of the hybrid ball-lock devices described herein can be used alone or in conjunction with other ball lock devices in the same plasma processing device. Furthermore, different types of hybrid ball-lock devices can be used in the same plasma processing device.