Abstract:
An auto-aligning linear motion apparatus is provided. The apparatus includes a leadscrew. The apparatus also includes a nut arrangement configured to surround the leadscrew, wherein the nut arrangement includes at least a nut, a nut bracket, and a floating collar. A shoulder screw is inserted through a nut bracket slot of the nut bracket and a nut slot of the nut to rest at least partially within the floating collar. One dimension of the not bracket slot is larger than a dimension through a cross-section area of the shoulder screw to enable the shoulder screw to move within the nut bracket slot to adjust the nut arrangement as the leadscrew is rotated to maintain a concentric relationship between the nut arrangement and the leadscrew.

Description:
PRIORITY CLAIM 
       [0001]    The present application is a divisional under 37 CFR 1.53(b) and claims priority under 35 U.S.C. §120 from the following application “Floating collar clamping device for auto-aligning nut and screw in linear motion leadscrew and nut assembly,” by James E. Tappan, Attorney Docket Number P1806/LMRX-P154, application Ser. No. 12/365,327 filed on Feb. 4, 2009, which claims priority under 35 U.S.C. § 119(e) to a commonly assigned provisional patent application entitled “A floating collar clamping device for auto aligning nut and screw in linear motion leadscrew and not assembly,” by James E. Tappan, Attorney Docket Number P1806P/LMRX-P154P1 application Ser. No. 61/027,405 tiled on Feb. 8, 2008, all of which are incorporated herein by reference, 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    Advances in plasma processing have provided for growth in the semiconductor industry. During substrate processing, conditions of the chamber may have to be closely manipulated to create a processing environment that produces semiconductor devices. In a precision linear motion processing system, manipulation may occur by altering the configuration of the processing chamber. 
         [0003]    Consider the situation wherein, for example, a substrate is being processed in a processing chamber of a precision linear motion processing system. The substrate is positioned on top of a lower electrode electrostatic chuck). Depending upon the recipe, the lower electrode may be moved vertically, thereby adjusting the substrate in relation to the upper electrode, which is usually positioned above the lower electrode. 
         [0004]    To facilitate the vertical adjustment of the lower electrode, a linear motion apparatus may be attached to the lower electrode. The linear motion apparatus may include a leadscrew. To enable the leadscrew to rotate, a motor may be attached to the leadscrew via a shaft. The motorized leadscrew arrangement may be attached to the external wall of the processing chamber via a pair of clamps, which may be fastened to the wall of the processing chamber via a pair of screws. 
         [0005]    The linear motion apparatus may also include a nut arrangement. The nut arrangement may include a threaded nut, which may surround the leadscrew to create a concentric relationship between the leadscrew and the threaded nut. The nut arrangement may be attached to a support plate, which is fastened to the threaded nut via a nut bracket. Accordingly, as the leadscrew rotates, the nut arrangement is moved in a vertical direction, thereby causing the support plate to move in the same direction. Since the support plate is attached to the lower electrode, the lower electrode is adjusted by manipulating the linear motion apparatus. In other words, the motorized leadscrew causes the nut arrangement to move in a vertical direction, thereby translating into a vertical adjustment of the lower electrode. 
         [0006]    To maximize the life of the linear motion apparatus, the concentricity between the leadscrew and the threaded nut may have to he maintained. However, maintaining concentricity may be a challenge, especially if the linear motion apparatus may have been improperly assembled. In an example, during assembly of the precision linear motion processing system, the leadscrew may have been positioned in a manner slightly out of concentricity. Even if the linear motion apparatus has been assembled properly, leadscrew runout may occur. As discussed herein, leadscrew runout refers to a leadscrew that is not straight due to a manufacture defect, or normal manufacturing tolerances. Regardless if the linear motion apparatus has been improperly assembled or the leadscrew may have runout, the rotation of the leadscrew may cause the threaded nut to apply load to one side of the leadscrew, thereby causing excessive friction and/or premature wearing of the leadscrew and/or the threaded nut. 
         [0007]    To address the misalignment, one prior art solution includes employing, a set of clearance slots to accommodate the fasteners that may be utilized to mount either hardware (e.g. leadscrew or threaded nut). In an example, a clamp may mount the leadscrew to the wall of the processing chamber. The clamp may be fastened to the wall of the processing chamber via a pair of screws, which may be inserted into a pair of clearance slots located on the clamp. Each clearance slot may have an oblong configuration, thereby enabling an assembler to align the leadscrew in an X direction. However, by using clearance slot to perform alignment, the simple assembly process becomes as time-consuming and more complicated assembly procedure, As a result, a highly-skilled assembler is required to perform the more complicated assembly procedure. In addition, unwanted side loading grinding against the side of the leadscrew) may still occur since the clearance slots do not address leadscrew runout. 
         [0008]    Another prior art solution includes employing a floating nut, which is a threaded nut with a clearance gap at its mounting holes. In an example, a linear motion apparatus may include a leadscrew surrounded by a threaded nut mounted with holes with clearance gap. In other words, a gap may exist between the mounting screws and the mounting holes of the threaded nut. Accordingly, with a gap, misalignment due to improper assembly and/or leadscrew runout may be accommodated, thereby reducing unwanted side loading. However, the floating nut arrangement may cause the threaded nut to shift in a clockwise and/or counterclockwise direction. As a result, the shifting of the threaded nut may cause loss of positional accuracy that may translate to inability to accurately manipulate the configuration of the processing chamber in order to etch a substrate. 
         [0009]    As can be appreciated from the foregoing, premature wearing due to unwanted side loading may require that at least part of the linear motion apparatus, such as the leadscrew and the threaded nut, be replaced. While the worn parts are being replaced, the processing tool is essentially unavailable for processing substrate. Depending upon the time period required to replace the worn parts (which may include shutting down the processing tool, ordering, the required parts, disassembling the linear motion apparatus, reassembling the linear motion apparatus with the new parts, recalibrating the processing tool, and the like), the economic loss that a company may suffer due to premature wearing can become quite significant. 
       SUMMARY OF INVENTION 
       [0010]    The invention relates, in an embodiment, an auto-aligning linear motion apparatus. The apparatus includes a leadscrew. The apparatus also includes a nut arrangement configured to surround the leadscrew, wherein the nut arrangement includes at least a nut, a nut bracket and a floating collar. A shoulder screw is inserted through a nut bracket slot of the nut bracket and a nut slot of the nut to rest at least partially within the floating collar. One dimension of the nut bracket slot is larger than a dimension through a cross-section area of the shoulder screw to enable the shoulder screw to move within the nut bracket slot to adjust the nut arrangement as the leadscrew is rotated to maintain a concentric relationship between the nut arrangement and the leadscrew. 
         [0011]    The above summary relates to only one of the many embodiments of the invention disclosed herein and is not intended to limit the scope of the invention, which is set forth in the claims herein. These and other features of the present invention will be described in more detail below in the detailed description of the invention and in conjunction with the following figures. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         [0012]    The present invention is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which: 
           [0013]      FIG. 1  shows, in an embodiment of the invention, an exploded-view of an auto-aligning linear motion apparatus. 
           [0014]      FIG. 2  shows, in an embodiment of the invention, a cut-out view of an auto-aligning linear motion apparatus with a pair of inserted shoulder screws. 
           [0015]      FIG. 3  shows, in an embodiment of the invention, a cut-out view of an auto-aligning linear motion apparatus with a pair of raised bosses. 
           [0016]      FIG. 4  shows, in an embodiment of the invention, an exploded-view of an auto-aligning linear motion apparatus (another view of  FIG. 1 ). 
           [0017]      FIG. 5  shows, in an embodiment of the invention, as cut-out view of an auto-aligning linear motion apparatus with a pair of inserted shoulder screws (another view of  FIG. 2 ). 
           [0018]      FIG. 6  shows, in an embodiment of the invention, a cut-out view of an auto-aligning linear motion apparatus with a pair of raised bosses (another view of  FIG. 3 ). 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0019]    The present invention will now be described in detail with reference to a few embodiments thereof as illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art, that the present invention may be practiced without some or all of these specific details. In other instances, well known process steps and/or structures have not been described in detail in order to not unnecessarily obscure the present invention. 
         [0020]    Various embodiments are described hereinbelow, including methods and techniques. It should be kept in mind that the invention might also cover articles of manufacture that includes a computer readable medium on which computer-readable instructions for carrying out embodiments of the inventive technique are stored. The computer readable medium may include, for example, semiconductor, magnetic, opto-magnetic, optical, or other forms of computer readable medium for storing computer readable code. Further, the invention may also cover apparatuses for practicing embodiments of the invention. Such apparatus may include circuits, dedicated and/or programmable, to carry out tasks pertaining, to embodiments of the invention. Examples of such apparatus include as general-purpose computer and/or a dedicated computing device when appropriately programmed and may include a combination of as computer/computing device and dedicated/programmable circuits adapted for the various tasks pertaining to embodiments of the invention. 
         [0021]    In accordance with embodiments of the present invention, an auto-aligning linear motion apparatus provides a mechanism for to nut to self-align in relation to the configuration of as leadscrew. To facilitate self-alignment, the nut may be attached to a nut bracket and a floating collar via a pair of shoulder screws. In an example, the nut may slide in an X direction due to the shape of the out bracket slots that have been cut into the nut brackets. In an embodiment, the pair of nut bracket slots may have an oblong shape in the X direction, thereby enabling the inserted shoulder screws to move in an X direction. Since the shoulder screws are also inserted into slots cut into the nut, the sliding of the shoulder screws may also translate into self-alignment of the nut in the X direction. 
         [0022]    In another embodiment, the nut is connected to the floating collar via the shoulder screws and a pair of opposing raised bosses, which are raised fixtures located on the floating collar. In an embodiment, the raised bosses are inserted upward into a pair of nut flange slots that have been cut into the nut flange. In one embodiment, the nut flange slots have an oblong shape in the Y direction, thereby enabling the nut to slide in the Y direction. 
         [0023]    With the modified nut arrangement, the shoulder screws and/or the raised bosses restrict the nut from rotating while allowing the nut the freedom of self-aligning in the X/Y direction. In an example, the motorized leadscrew is offset to the right in an X direction. As the motorized leadscrew rotates, the nut is able to perform self-alignment to accommodate the offset of the leadscrew by also sliding in the X direction, thereby maintaining concentricity between the nut and the leadscrew and substantially minimizing unwanted side loading. Thus, premature wearing that is usually associated with unwanted side loading may be significantly reduced. 
         [0024]    The features and advantages of the present invention may be better understood with reference to the figures and discussions that follow. 
         [0025]      FIG. 1  shows, in an embodiment of the invention, an exploded-view of an auto-aligning linear motion apparatus, For an exploded view of  FIG. 1 , see  FIG. 4  As aforementioned, a precision linear motion processing system may include a movable lower electrode (not shown) that, may be adjusted during substrate processing, thereby enabling an operator to control the height of the lower electrode. To facilitate adjustment, the lower electrode is attached to an auto-aligning linear motion apparatus  100  via a support plate  110 . In an embodiment, auto-aligning linear motion apparatus  100  may include a modified nut arrangement surrounding as leadscrew  102 . Similar to the prior art, leadscrew  102  may be attached to a motor (not shown), thereby enabling leadscrew  102  to rotate when the motor is turned on. 
         [0026]    The modified nut arrangement may include a nut bracket  104 , a nut  106 , and a floating collar  108 . Nut bracket  104  is an extension of support plate  110  and connects nut  106  (which may be threaded) to support plate  110 . To join the two components, a pair of shoulder screws ( 112  and  114 ) may be inserted into a pair of opposing nut bracket slots ( 116   a  and  116   b ) and a pair of opposing not slots ( 118   a  and  118   b ). 
         [0027]    In an embodiment, each shoulder screw ( 112  and  114 ) may include a screw head  122 , a shoulder portion  124 , and a screw portion  126 . In one embodiment, shoulder portion  124  may have a length that is at least equal to the thickness of nut bracket  104  and the thickness of a nut flange  128 , which is the wider portion of nut  106 . When shoulder screw is inserted into the slots, screw portion  126  may extend beyond nut flange  128 . In an embodiment, shoulder screw  112  may be secured into the modified nut arrangement by inserting screw portion  126  into a collar threaded hole  120   a  of floating collar  108 . As discussed herein, a floating collar is to ring arrangement that is positioned directly beneath nut flange  128  and fits securely around a nut body  130  of nut  106 . 
         [0028]    In the prior art, unwanted side loading, which may lead to premature wearing, may occur when concentricity between a leadscrew and a nut is either not established and/or maintained due to misalignment and/or leadscrew runout. In one aspect of the invention, the inventor herein realizes that concentricity may be maintained if the modified nut arrangement automatically aligns in an X/Y direction to accommodate the configuration of the leadscrew.  FIGS. 2 and 3  will he used to illustrate how auto alignment may be achieved through the modified nut arrangement. 
         [0029]      FIG. 2  shows, in an embodiment of the invention, a cut-out view of an auto aligning linear motion apparatus with a pair of inserted shoulder screws. For an exploded view of  FIG. 2 , see  FIG. 5 . Shoulder screws  112  and  114  have been inserted into the modified nut arrangement. In an example, shoulder screw  112  has been inserted into nut bracket slot  116   a , nut slot  118   a  (not shown), and collar threaded hole  120   a  (not shown), thereby joining nut bracket  104 , nut  106 , and floating collar  108  into a single modified nut arrangement. 
         [0030]    In an embodiment, the pair of nut bracket slots ( 116   a  and  116   b ) may have a larger diameter than the pair of shoulder screws ( 112  and  114 ). In other words, when shoulder screw  112  is inserted into nut bracket slot  116   a , a slight gap may exist between shoulder section  124  and wall of nut bracket slot  116   a . In one embodiment, each of the pair of nut bracket slots ( 116   a  and  116   b ) has an oblong shape in an X direction  202 , thereby enabling the inserted shoulder screws to move in X direction  202  when shoulder screw  112  is tightened. 
         [0031]    In an embodiment, shoulder sections of the shoulder screws may pass through the corresponding pair of opposing nut slots. In an example, when shoulder section  124  is butted snugly against top surface of floating collar  108  inserted shoulder screw  112  is securely affixed to floating collar  108 . Since inserted shoulder screw  112  is able to slide in X direction  202 , floating collar  108 , consequently, may also inherit the trait and is able to automatically align in the same direction. Accordingly, nut  106  is constrained in the X direction relative to floating collar  108 , via the pair of opposing raised bosses ( 302  and  304 ) and corresponding slots  306   a  and  306   b  in nut  106  floating collar  108  and nut  106  together may also be automatically aligned in the X direction. 
         [0032]      FIG. 3  shows, in an embodiment of the invention, a cut-out view of an a aligning linear motion apparatus with a pair of raised bosses. For an exploded view of  FIG. 3  see  FIG. 6 . Floating collar  108  may include a pair of opposing raised bosses ( 302  and  304 ), in an embodiment. Pair of raised bosses  302  and  304  may be located on top of floating collar  108  and each may be situated between the pair of opposing collar threaded holes ( 120   a  and  120   b    FIG. 1 ). 
         [0033]    In an embodiment, pair of opposing raised bosses ( 302  and  304 ) may be inserted upward into a pair of opposing nut flange slots ( 306   a  and  306   b ), which may be recessed into nut flange  128 . In one embodiment, pair of opposing nut flange slots ( 306   a  and  306   b ) may be slightly larger than larger pair of opposing raised bosses ( 302  and  304 ). In an example, when raised boss  302  is inserted into nut flange slot  306   a , a slight gap may exist between the raised boss and the slot, thereby enabling nut  106  to automatically align in relation to raise boss  302 . In one embodiment, pair of nut flange slots ( 306   a  and  306   b ) may have an oblong shape in a Y direction  308 , thereby allowing nut  106  to adjust in a Y direction relative to floating collar  108 . 
         [0034]    If modification to nut  104  is not feasible or permissible to create the pair of oblong slots (i.e., pair of nut flange slots) to allow the pair of raised bosses to rise into the pair of oblong slots and translate in the Y direction, then an additional adapter ring may be provided in-between nut flange  128  and floating collar  108 , in an embodiment. The adapter ring may have a pair of opposing oblong slots to facilitate the guiding function of the raised bosses for the translation movement in the Y direction. 
         [0035]    As can be appreciated from  FIGS. 2 and 3 , the modified nut arrangement enables the nut to automatically self-align in the X/Y direction while the shoulder screws and the raised bosses prevent the nut from rotating, thereby limiting rotation between nut and nut bracket to ensure that no loss of positional accuracy is sacrificed while accommodating the ability to self-align in the X/Y direction. In other words, the nut is able to perform self-alignment in relation to the configuration of the leadscrew, thereby enabling the nut and the leadscrew to maintain a concentric relationship while maintaining good positional accuracy of the linear motion apparatus. In an example, the nut is able to accommodate misalignment of the leadscrew due to improper assembly or manufacturing tolerances resulting in a non-concentric nut to leadscrew relationship. For example, as the motorized leadscrew rotates, the modified nut arrangement may slide in either the X or Y direction to accommodate the position of the leadscrew. Similarly, the modified nut arrangement ability to perform self-alignment in the X/Y direction may also address the unwanted side loading that may occur due to leadscrew runout. 
         [0036]    As can be appreciated from one or more embodiments of the invention, the auto-aligning linear motion apparatus provides an arrangement for vertically adjusting a lower electrode while substantially eliminating unwanted side loading of leadscrew nut. Accordingly, by substantially eliminating the unwanted side loading, premature wearing of the leadscrew and the nut may also be correspondingly prevented. With a modified nut arrangement, concentricity between the leadscrew and the nut may be maintained without requiring complicated assembly procedures. Since the arrangement requires fairly inexpensive parts, concentricity may he maintained without incurring expensive costs. Thus, the auto aligning linear motion apparatus provides a cost effective solution for minimizing economic loss that may have originated from lack of concentricity. 
         [0037]    While this invention has been described in terms of several preferred embodiments, there are alterations, permutations, and equivalents, which fall within the scope of this invention. Although various examples are provided herein, it is intended that these examples be illustrative and not limiting with respect to the invention. 
         [0038]    Also, the title and summary are provided herein for convenience and should not be used to construe the scope of the claims herein. Further, the abstract is written in a highly abbreviated form and is provided herein for convenience and thus should not be employed to construe or limit the overall invention, which is expressed in the claims. If the term “set” is employed herein, such term is intended to have its commonly understood mathematical meaning to cover zero, one, or more than one member. It should also be noted that there are many alternative ways of implementing the methods and apparatuses of the present invention, It is therefore intended that the following appended claims be interpreted as including all such alterations, permutations, and equivalents as fall within the true spirit and scope of the present invention.