Abstract:
A dielectric arrestor insert for use in a chamber wafer processing system having a gas input line, an arrestor housing and a wafer processing space. The input line is able to provide gas to the arrestor housing. The arrestor housing is able to house the dielectric arrestor insert. The dielectric arrestor insert comprises a gas entry portion, a non-linear channel and a gas exit portion. The gas entry portion is arranged to receive the gas from the input line. The non-linear channel is arranged to deliver the gas from the gas entry portion to the gas exit portion. The gas exit portion is arranged to deliver the gas from the non-linear channel to the wafer processing space.

Description:
The present application claims benefit under 35 U.S.C. §119 (e) to U.S. provisional patent application 61/165,270, filed Mar. 31, 2009, the entire disclosure of which is incorporated herein by reference. 
     BACKGROUND 
     The semiconductor manufacturing industry places increased emphasis on cost savings and efficiency to increase a constantly dwindling profit margin. One important effort to drive costs lower is to preserve components within a system that requires extremely high ion energy at the substrate surface when using helium based plasma to complete the required etching process. To create this high ion energy at the substrate surface, a high voltage is applied at the substrate surface, which creates a large electrical field gradient extending back into the helium supply line, which in turn creates unwanted electrical arcing between surfaces and generates plasma in the supply lines and other components. This produces adverse effects such as pitting and melting of the supply lines. Disposing an electrical insulator between the area of high electrical potential and the supply lines can minimize impact of unwanted electrical arcing and plasma generation. However, such electrical insulators increase cost of ownership. Great care must be taken to avoid the unnecessary wear rate of system parts. 
       FIG. 1  is a cross-sectional view of a conventional helium supply system  100  of a chamber wafer processing system  112 . System  100  includes a flexible helium supply line  102 , a metallic weldment  104 , a dielectric arrestor insert  106 , a dielectric arrestor housing  108 , an ESC mounting plate  118 , and a bowl housing assembly  116 . Arrestor housing  108  is shaped to include a cylindrical cavity  120  for holding dielectric arrestor insert  106 . Flexible helium supply line  102 , metallic weldment  104 , dielectric arrestor insert  106 , arrestor housing  108 , and ESC mounting plate  118  reside in bowl housing assembly  116 . Chamber wafer processing system  112  includes an electro-static chuck (ESC)  110  that is operable to electrostatically hold a wafer for processing. 
     In operation, helium is supplied to chamber wafer processing system  112  via conventional helium supply system  100 . The path of the helium through conventional helium supply system  100  as indicated by arrows within flexible helium supply line  102 , metallic weldment  104  and arrows  114  through dielectric arrestor insert  106 . 
     Operation of the ESC requires the use of high voltage DC power be applied to clamp the wafer, and high-frequency RF power to generate the plasma needed for wafer processing. Helium is supplied to the ESC to effect thermal sinking between the wafer and the ESC  110 . Application of either the high voltage DC or RF power can, in turn, excite the helium to a point where electrons are able to escape the bond of the helium atom, thus generating plasma. The time at which gaseous helium is converted into plasma is commonly referred to as “light-up.” 
     Mounting plate  118 , which is usually operated at a high voltage potential similar to what that of ESC  110 , is electrically-separated from flexible helium supply line  102  and metallic weldment  104 , by arrestor housing  108 , and dielectric arrestor insert  106 . Bowl housing assembly  116  is at ground potential. It is desirable that flexible helium supply line  102  and metallic weldment  104  be shielded from the electrical and magnetic field effects from ESC  110 . Further, the electrical potential of metallic weldment  104  and flexible helium supply line  102  should closely match that of bowl housing assembly  116  to prevent electrical arcing between the two, or to prevent a high voltage potential between the two so as to cause light-up within flexible helium supply line  102 . If electrical arcing occurs, damage to bowl components can occur. If plasma light-up occurs, pitting and melting of the supply lines and other components within bowl housing assembly  116  can occur. The requirement to hold metallic weldment  104  at the ground potential of bowl  116  results in a large voltage potential impressed across arrestor housing  108 , and dielectric arrestor insert  106 . 
     At lower helium pressures between 1 to 50 Ton (pressures between 1/760 and 50/760 of standard atmospheric pressure), which is typical of normal operating conditions of chamber wafer processing system  112  and system  100 ; the helium can conduct electrical current and generate electrical arcing under certain conditions. The likelihood of plasma generation or arcing within arrestor housing  108  and dielectric arrestor insert  106  is directly related to the voltage potential difference, and inversely related to the gas path length, between metallic weldment  104  and mounting plate  118 , and is also directly related to the cross-section mean free path available, which will be discussed in more detail below. 
       FIG. 2A  is an oblique view of dielectric arrestor insert  106 . Dielectric arrestor insert  106  includes a first cylindrical portion  202 , spaced from a second cylindrical portion  204  via a circumferential channel  206 . First cylindrical portion  202  has a circular face  208 , whereas second cylindrical portion  204  has a circular face  210 . Circular face  208  has a helium entry  216 , whereas circular face  210  has a helium exit  218 . A longitudinal channel  212 , having a width d 1  and a depth d 2 , extends from helium entry  216  at circular face  210  to circumferential channel  206 , whereas a longitudinal channel  214  extends from circumferential channel  206  to helium exit  218 . 
       FIG. 2B  is a cross-sectional view of dielectric arrestor insert  106 . In the figure, helium gas flows along a path indicated by arrows  114 . Specifically, helium provided by metallic weldment  104  enters helium entry  216 , proceeds through longitudinal channel  212 , proceeds around circumferential channel  206 , continues through longitudinal channel  214  and finally exits out helium exit  218  into chamber wafer processing system  112 . The total distance that the helium gas travels in dielectric arrestor insert  106  includes the length of longitudinal channel  212 , half the circumference of circumferential channel  206  and the length of longitudinal channel  214 . 
     Returning back to  FIG. 1 , dielectric arrestor insert  106  is tightly disposed within cylindrical cavity  120  of arrestor housing  108 . Accordingly, cylindrical cavity  120  closes longitudinal channel  212 , circumferential channel  206  and longitudinal channel  214  to form tubes such that helium gas will only pass through longitudinal channel  212 , circumferential channel  206  and longitudinal channel  214 . Dielectric arrestor insert  106  provides an insulator block between a low electrical potential of metallic weldment  104  and a high potential of mounting plate  118 . Metallic weldment  104  is at or near ground potential and mounting plate  118  is at a high electrical potential. Because of the voltage difference between metallic weldment  104  and mounting plate  118 , there is a possibility of light up and arcing of helium within dielectric arrestor insert  106  or arrestor housing  108 . At least one of two tactics may be employed to reduce the potential of arcing or light-up in dielectric arrestor insert  106  or arrestor housing  108 . 
     First, width d 1  and depth d 2  of longitudinal channel  212  of dielectric arrestor insert  106  can be decreased. For a constant supply of helium, decreasing width d 1  and depth d 2  of longitudinal channel  212  of dielectric arrestor insert  106  will reduce the cross-sectional area and thus reduce the space for electrons to move in an excited state to produce plasma. A problem with this tactic is that decreasing the width d 1  and depth d 2  of longitudinal channel  212  of dielectric arrestor insert  106  will increase the pressure drop across the components, and that will decrease the amount of helium supplied into wafer processing system  112 . 
     Second, the total length that the helium gas travels in dielectric arrestor insert  106  can be increased. This will effectively increase the distance between metallic weldment  104  and ESC  110  as viewed from an electrostatic field induced through helium within longitudinal channel  212 , circumferential channel  206  and longitudinal channel  214 . This will reduce the voltage gradient over the total length that the helium gas travels in dielectric arrestor insert  106  making dielectric arrestor insert  106  a better insulator block. However, arcing or light-up potential can be an issue if the increased length comes in the form of a longer, line-of-site path. Also, there is only a limited amount of space in arrestor housing  108  and bowl housing assembly  116 . As such, in system  100 , this is not a viable option. 
     Finally, the dielectric constant of the electrically insulative material may be decreased. 
     The dielectric arrestor insert  106  includes a width d 1  and depth d 2  of longitudinal channel  212  that is sufficiently large to provide sufficient helium into wafer processing system  112 . Further, as noted above, the total length that the helium gas travels in dielectric arrestor insert  106  includes the space in arrestor housing  108 . The width d 1  and depth d 2  of longitudinal channel  212  in combination with a short total length that the helium gas travels in dielectric arrestor insert  106  affect the ability of dielectric arrestor insert  106  to prevent arcing and plasma generation in dielectric arrestor insert  106  itself. 
     What is needed is a dielectric arrestor insert that decreases the likelihood of arcing and plasma generation in the dielectric arrestor insert itself, while not causing and adverse pressure drop. 
     BRIEF SUMMARY 
     It is an object of the present invention to provide a dielectric arrestor insert that decreases the likelihood of arcing and plasma generation in the dielectric arrestor insert. 
     In accordance with an aspect of the present invention, a dielectric arrestor insert may be used in a chamber wafer processing system having a gas input line, an arrestor housing and a wafer processing space. The input line is able to provide gas to the arrestor housing. The arrestor housing is able to house the dielectric arrestor insert. The dielectric arrestor insert comprises a gas entry portion, a non-linear channel and a gas exit portion. The gas entry portion is arranged to receive the gas from the input line. The non-linear channel is arranged to deliver the gas from the gas entry portion to the gas exit portion. The gas exit portion is arranged to deliver the gas from the non-linear channel to the wafer processing space. 
     Additional objects, advantages and novel features of the invention are set forth in part in the description which follows, and in part will become apparent to those skilled in the art upon examination of the following or may be learned by practice of the invention. The objects and advantages of the invention may be realized and attained by means of the instrumentalities and combinations particularly pointed out in the appended claims. 
    
    
     
       BRIEF SUMMARY OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and form a part of the specification, illustrate an exemplary embodiment of the present invention and, together with the description, serve to explain the principles of the invention. In the drawings: 
         FIG. 1  illustrates a conventional helium supply system to a chamber wafer processing system used during wafer etching processes; 
         FIG. 2A  illustrates an expanded conventional dielectric arrestor insert of  FIG. 1 ; 
         FIG. 2B  illustrates a cross-sectional view of  FIG. 2A  of an expanded conventional dielectric arrestor insert of  FIG. 1 ; 
         FIG. 3  illustrates an exemplary embodiment in accordance with the present invention of a helium supply system to a chamber wafer processing system used during wafer etching processes; 
         FIG. 4A  illustrates an expanded side view of an example single-lead dielectric arrestor insert in accordance with the present invention; 
         FIG. 4B  shows a cross-sectional view of the example dielectric arrestor insert of  FIG. 4A ; 
         FIG. 4C  illustrates an oblique top view of the example dielectric arrestor insert of  FIG. 4A ; 
         FIG. 5A  illustrates an expanded side view of another example dielectric arrestor insert in accordance with the present invention; 
         FIG. 5B  shows a cross-sectional view of the example dielectric arrestor insert of  FIG. 5A ; 
         FIG. 5C  illustrates an oblique top view of the example dielectric arrestor insert of  FIG. 5A ; 
         FIG. 6A  illustrates an expanded side view of a dual-lead dielectric arrestor insert in accordance with the present invention; 
         FIG. 6B  shows a cross-sectional view of the example dielectric arrestor insert of  FIG. 6A ; 
         FIG. 6C  illustrates an oblique top view of the example dielectric arrestor insert of  FIG. 6A ; 
         FIG. 7  illustrates an oblique top view of a quad-lead dielectric arrestor insert in accordance with the present invention; 
         FIG. 8  illustrates a cross-sectional view of another example dielectric arrestor insert in accordance with the present invention; and 
         FIG. 9  illustrates a cross-sectional view of another example dielectric arrestor insert in accordance with the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     In a helium supply system that supplies helium to a chamber wafer processing system, a portion of the helium supply system may be at or near ground potential, whereas a portion of the chamber wafer processing system may have a high electrical potential. In such a case, helium within the helium supply line or in the dielectric arrestor insert positioned to supply helium into the chamber wafer processing system has a likelihood of plasma light-up or electrical arcing. In accordance with an aspect of the present invention, the likelihood of helium light-up within the dielectric arrestor insert or arrestor housing is decreased by increasing the length that the helium gas travels in the dielectric arrestor insert. More particular, in accordance with an aspect of the present invention, a dielectric arrestor insert includes non-linear channels into which the helium gas passes. The non-linear channels increase the distance that the helium gas travels in dielectric arrestor insert as compared to the conventional dielectric arrestor insert, while concurrently limiting direct line-of-sight that would allow light-up or electrical arcing to occur. 
     Example embodiments of a dielectric arrestor insert in accordance with aspects of the present invention will now be described below with reference to  FIGS. 3-9 . 
       FIG. 3  is a cross-sectional view of helium supply system  300  operable to provide helium to a chamber wafer processing system  112 . Helium supply system  300  is similar to helium supply system  100  as illustrated in  FIG. 1 , wherein dielectric arrestor insert  106  is replaced with a dielectric arrestor insert  306  in accordance with an aspect of the present invention. System  300  includes flexible helium supply line  102 , metallic weldment  104 , dielectric arrestor insert  306 , an arrestor housing  108 , a bowl housing assembly  116 . Arrestor housing  108  is shaped to include a cylindrical cavity  120  for holding dielectric arrestor insert  306 . Flexible helium supply line  102 , metallic weldment  104 , dielectric arrestor insert  306  and arrestor housing  108  reside in bowl housing assembly  116 . Chamber wafer processing system  112  includes ESC  110  that is operable to electrostatically hold a wafer for processing. 
     In operation, helium is supplied to chamber wafer processing system  112  via helium supply system  300 . The path of the helium through system  300  is indicated by arrows within flexible helium supply line  102 , and arrows  314  through dielectric arrestor insert  306 . 
     In accordance with an aspect of the present invention, a helical channel is provided in a dielectric arrestor insert to increase the total length that the helium gas travels in dielectric arrestor insert. Further, in some embodiments a plurality of channels may be included. For similar cross-section areas of individual channels, the total cross-section area within the dielectric arrester insert is directly related to the number of individual channels. Further, the total length that the helium gas travels in each individual channel within the dielectric arrestor insert is inversely related to the number of individual channels. That is to say, a dual channel dielectric arrestor insert will give twice the cross-section flow area as a single channel dielectric arrestor insert, but will only have half the path length of the single channel dielectric arrestor insert. The pitch of a helical channel within a dielectric arrestor insert is the center-to-center distance of one continuous winding. 
     Various example embodiment dielectric arrestor inserts in accordance with the present invention are discussed herein, showing different numbers of channels with different pitches. The spacing, pitch, depth, and number of channels can be altered to achieve a desirable cross-section area and path length. 
     An example embodiment of a dielectric arrestor having a single helical channel in accordance with an aspect of the present invention will now be described with reference to  FIGS. 4A-4C . 
       FIG. 4A  illustrates an expanded side view of dielectric arrestor insert  306 . As illustrated in the figure, dielectric arrestor insert  306  includes a top face  402 , a bottom face  404 , a core portion  406  and a winding portion  408 . Top face  402  includes a helium entry  410 , whereas bottom face  404  includes a helium exit  412 . Winding portion  408  helically winds around core portion  406  such that adjacent windings form a continuous helical channel  414 . 
       FIG. 4B  is a cross-sectional view of dielectric arrestor insert  306 . Helium provided by helium input line  118  enters helium entry  410 , proceeds through continuous helical channel  414  and finally exits out helium exit  412  into chamber wafer processing system  112 . The total length that the helium gas travels in dielectric arrestor insert  306  includes the length of continuous helical channel  414 . 
     Dielectric arrestor insert  306  has a diameter D t  that corresponds to the diameter of cylindrical cavity  120 . Accordingly, cylindrical cavity  120  closes continuous helical channel  414  to form a tube such that helium gas will only pass through continuous helical channel  414 . Core portion  406  has a diameter D i , wherein the radial distance of winding portion  408  is d w , wherein D t =D i +2(d w ). The cross-sectional shape of winding portion  408  includes a plurality of rectangular fins  416 , separated by a distance S w . The cross-sectional area bounded by rectangular fins  416 , core portion  406  and cylindrical cavity  120  is a rectangular area  418  and is equal to d w  times S w . 
     The length of continuous helical channel  414  is directly proportional to diameter D i , wherein as D i  increases, the length of continuous helical channel  414  increases. The length of continuous helical channel  414  is also directly proportional to length S, and the number of turns of the helical channel. This will be discussed in more detail below. 
     The available cross-sectional area within dielectric arrestor insert  306  for passing helium into chamber wafer processing system  112  is directly proportional to rectangular area  418 . As such, the available cross-sectional area within dielectric arrestor insert  306  for passing helium into chamber wafer processing system  112  is directly proportional to distance S w . As distance S w  increases, the available cross-sectional area increases. Similarly, the available cross-sectional area within dielectric arrestor insert  306  for passing helium into chamber wafer processing system  112  is directly proportional to d w , wherein as distance d w  increases, the available cross-sectional area increases. 
       FIG. 4C  shows an oblique top view of dielectric arrestor insert  306  which illustrates a single feed helium entry  410  indicated by the arrow to top face  402 . 
     In this example embodiment, the length of continuous helical channel  414  is significantly longer than longitudinal channel  212 , circumferential channel  206  and longitudinal channel  214  of  FIG. 2B . Accordingly, in accordance with the present invention, the propensity of generating gas plasma in dielectric arrestor insert  306  and helium input line  118  or other components inside the bowl housing assembly  116  significantly decreases. 
     Another example embodiment of a dielectric arrestor insert having a single helical channel in accordance with an aspect of the present invention will now be described with reference to  FIGS. 5A-5C . 
       FIG. 5A  illustrates an expanded side view of an example dielectric arrestor insert  500 . Dielectric arrestor insert  500  includes a top face  502 , a bottom face  504 , a core portion  506  and a winding portion  508 . Top face  502  includes a helium entry  510 , whereas bottom face  504  includes a helium exit  512 . Winding portion  508  helically winds around core portion  506  such that adjacent windings form a continuous helical channel  514 . 
       FIG. 5B  is a cross-sectional view of dielectric arrestor insert  500  of  FIG. 5A . When disposed within cylindrical cavity  120  of helium supply system  300 , cylindrical cavity  120  closes continuous helical channel  514  to form a tube such that helium gas will only pass through continuous helical channel  514 . Helium provided by helium input line  118  enters helium entry  510 , proceeds through continuous helical channel  514  and finally exits out helium exit  512  into chamber wafer processing system  112 . The total length that the helium gas travels in dielectric arrestor insert  500  includes the length of continuous helical channel  514 . The cross-sectional shape of winding portion  508  includes a plurality of rectangular fins  516 , separated by a distance S w1 . 
       FIG. 5C  shows an oblique top view of dielectric arrestor insert  500  and illustrates a single feed helium entry  510  indicated by the arrow to top face  502 . 
     Dielectric arrestor insert  500  has a decreased pitch as compared to dielectric arrestor insert  306  of  FIG. 4B . In other words, as the pitch of winding portion  508  decreases, the winding portion  508  forms a tighter spiral around core portion  506 . Accordingly, the total length that helium gas travels through winding portion  508  of arrestor insert  500  is longer than the total length that helium gas travels through winding portion  408  of dielectric arrestor insert  306  of  FIG. 4B . As such, dielectric arrestor insert  500  is able to provide a longer total length for the gas to travel than dielectric arrestor insert  400 , thus decreasing the likelihood of plasma light-up or electrical arcing. However, the cross-sectional area of winding portion  508  of arrestor insert  500  is less than the cross-sectional area of winding portion  408  of dielectric arrestor insert  306  of  FIG. 4B . As such, dielectric arrestor insert  500  is able to provide less gas into wafer processing system  112  than dielectric arrestor insert  400  at a comparable gas pressure. 
     Another example embodiment of a dielectric arrestor insert having two helical channels in accordance with an aspect of the present invention will now be described with reference to  FIGS. 6A-6C . 
       FIG. 6A  illustrates an expanded side view of dielectric arrestor insert  600 . Dielectric arrestor insert  600  includes a top face  602 , a bottom face  604 , a core portion  606 , a winding portion  608  and a winding portion  620 . Top face  602  includes a helium entry  610  and a helium entry  622 , whereas bottom face  604  includes a helium exit  612  and a helium exit  624 . Winding portion  608  helically winds around core portion  606  such that adjacent outside windings form a continuous helical channel  614 . Winding portion  620  helically winds around core portion  606  such that adjacent outside windings form a continuous helical channel  626 . 
       FIG. 6B  is a cross-sectional view of dielectric arrestor insert  600 . When disposed within cylindrical cavity  120  of helium supply system  300 , cylindrical cavity  120  closes continuous helical channel  614  to form a first tube and closes continuous helical channel  626  to form a second tube, such that helium gas will only pass through continuous helical channel  614  and continuous helical channel  626 . Helium provided by helium input line  118  enters helium entry  610  and helium entry  622 . Helium entering into helium entry  610  proceeds through continuous helical channel  614 , exits helium exit  612  and enters into chamber wafer processing system  112 . Helium entering into helium entry  622  proceeds through continuous helical channel  626 , exits helium exit  624  and additionally enters into chamber wafer processing system  112 . The total length that the helium gas travels in dielectric arrestor insert  600  includes the length of either one of continuous helical channel  614  and continuous helical channel  626 . The cross-sectional shape of each of winding portion  608  and winding portion  620  includes a plurality of rectangular fins  616 , separated by a distance S w3 . 
       FIG. 6C  shows an oblique top view of dielectric arrestor insert  600  and illustrates a dual feed helium entry system including helium entry  610  and helium entry  622  indicated by the arrows to top face  602 . 
     Each of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600  has an increased pitch as compared to continuous helical channel  514  of dielectric arrestor insert  500 . In other words, as the pitch of each of continuous helical channel  614  and continuous helical channel  614  increases over the pitch of continuous helical channel  514 , the total length that helium gas travels through either one of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600  decreases from the total length that helium gas travels through continuous helical channel  514  of dielectric arrestor insert  500 . As such, each of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600  provides a shorter total length for the gas to travel than dielectric arrestor insert  500 , thus increasing the likelihood of plasma light-up or electrical arcing. However, the cross-sectional area of the combination of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600  is greater than the cross-sectional area of continuous helical channel  514  of dielectric arrestor insert  500 . As such, dielectric arrestor insert  600  provides a greater amount of gas into wafer processing system  112  than dielectric arrestor insert  500  at a comparable gas pressure. 
     Another example embodiment of a dielectric arrestor insert having four helical channels in accordance with an aspect of the present invention will now be described with reference to  FIG. 7 . 
       FIG. 7  illustrates another example embodiment with aspect of the present invention of an oblique top view of a multiple feed helium path dielectric arrestor insert  306  which includes in this example four feeds  714 ,  716 ,  718  and  720  to top face  702 . 
       FIG. 7  demonstrates another way to increase the amount of helium gas provided to the chamber wafer processing system  112  of  FIG. 3  while still maintaining additional increased path length. This will increase the total helium gas flow to an acceptable level while decreasing the likelihood for generating plasma as discussed above. 
     Each of the four continuous helical channels of dielectric arrestor insert  700  has an increased pitch as compared to each of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600 . In other words, as the pitch of each of the four continuous helical channels of dielectric arrestor insert  700  increases over the pitch of each of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600 , the total length that helium gas travels through any of the four continuous helical channels of dielectric arrestor insert  700  decreases from the total length that helium gas travels through each of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600 . As such, each of the four continuous helical channels of dielectric arrestor insert  700  provides a shorter total length for the gas to travel than each of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600 , thus increasing the likelihood of plasma light-up or electrical arcing. However, the cross-sectional area of the combination of the four continuous helical channels of dielectric arrestor insert  700  is greater than the cross-sectional area of the combination of continuous helical channel  614  and continuous helical channel  614  of dielectric arrestor insert  600 . As such, dielectric arrestor insert  700  is able to provide a greater amount of gas into wafer processing system  112  than dielectric arrestor insert  600  at comparable gas pressure. 
     In the above-discussed embodiments of the present invention, the cross-sectional shape of the gas feed path is rectangular. In accordance with aspects of the present invention, the cross-sectional shape of the gas feed path may be any desired shape. A cross-sectional shape of the gas feed path may be designed to provide specific amounts of gas into chamber wafer processing system  112 . Two other example dielectric arrestor inserts are illustrated in  FIGS. 8 and 9 . 
       FIG. 8  is a cross-sectional view of a dielectric arrestor insert  800 . As illustrated in the figure, dielectric arrestor insert  800  has a winding portion  802 . Winding portion  802  create a continuous helical channel  804 . The cross-sectional shape of continuous helical channel  804  is triangular. 
       FIG. 9  is a cross-sectional view of a dielectric arrestor insert  900 . As illustrated in the figure, dielectric arrestor insert  900  has a winding portion  902 . Winding portion  902  create a continuous helical channel  904 . The cross-sectional shape of continuous helical channel  904  is curved. 
     The above discussed example embodiments of a dielectric arrestor insert in accordance with aspects of the present invention have a continuous helical channel, or continuous helical channels, to increase a gas path length. Other embodiments may use non-helical channels to increase a gas path length. Non-limiting examples of other embodiments include dielectric arrestor inserts having a curved or serpentine channel, or curved or serpentine channels. 
     In accordance with aspects of the present invention, at least one non-linear channel is provided in a dielectric arrestor insert to increase the total length that the helium gas travels in dielectric arrestor insert. For similar cross-section areas of individual channels, the total cross-section area within the dielectric arrester insert is directly related to the number of individual channels. Further, the total length that the helium gas travels in each individual channel within the dielectric arrestor insert is inversely related to the number of individual channels. The spacing, pitch, depth, and number of channels can be altered to achieve a desirable cross-section area, which is directly related to an amount of gas that can be provided into chamber wafer processing system for a predetermine pressure. Further the spacing, pitch, depth, and number of channels can be altered to achieve a desirable path length, which is inversely related to the likelihood of plasma light-up or electrical arcing. 
     The foregoing description of various preferred embodiments of the invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The exemplary embodiments, as described above, were chosen and described in order to best explain the principles of the invention and its practical application to thereby enable others skilled in the art to best utilize the invention in various embodiments and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto.