MULTI-ZONE GAS FEEDS

BACKGROUND OF TOE INVENTION

{0001 j Substrate processing systems have iong been employed to process substrates to produce electronic de vices (such as integrated circuit dies or flat display panels or solar panels), in a modem substrate processing system, multiple process modules (PMs) may be provisioned per system. This is commonly known as the clustered tool approach, and a cluster tool is commonly understood to include multiple processing modules for processing multiple siibstrates in parallel,

j 0002 j Generally speaking, each process module is configured to process one or more substrates in accordance with the same or different recipes/processes. Since the processing of substrates typically requires a plurality of process gases (such as etching or deposition or tuning gases), each process module (or chamber, as the term "chamber" is used interchangeably with, "process module" herein) is typically provisioned with its own gas panel in the past in order t selectively provide a set of required process gases to the process module to exec ute a desired recipe.

{6603] To elaborate, a gas panel represents the arrangement that performs the function of receiving the plurality of process gases, selectively providing selective gases of the plurality of process gases to the process module in accordance with parameters specified by the recipe. These parameters may inc lude one or more of volume, pressure, and temperature, for example. {000 j Gas panels are, however, fairly bulky and are relatively expensi e items to purchase, operate, and maintain , A typical gas panel includes a plurality of input and output gas l ines, a plurality of valves for volume/pressure control and for safety/isolation of the individual process gases and associated sensor/con trol/communication electronics. The typical gas panel also typically includes a mixing manifold for mixing the process gases prior to supplying such process gases to the process module. The large number of components increases the cost to acquire, operate, and maintain the substrate processing system.

}ΘΘ05] Furthermore, some plasma processing chambers, such as dielectric etch chambers, require multiple gas feeds to different regions or zones of the chamber, in an example dielectric etch tool that employs dual zone gas feeds, the recipe may specify that 60% of the process gas be directed to the c enter zone and 40% of the process gas be directed to the edge zone. A

i subsequent recipe in the same chamber may specify that 72% of the process gas be directed to the center zone and 28% of the process gas be directed to the edge zone, A commercially viable dielectric etcher that employs multi-zone gas feed needs to accurately accommodate a range of ratios for the various zones as specified by different recipes,

{0006] Reducing the cost of acquiring, operating, and maintaining substrate processing systems by simplifying and/or reducing the number of gas panels while still efficiently accommodating the multi-zone gas feed requirement for individual chambers

SUMMARY OF THE INVENTION

|0007| The invention relates, in an embodiment, to a gas supply delivery arrangement for supplying process gas to a plurality of multi-zone gas feed chambers of a plasma processing system. The arrangement includes a plurality of gas supply conduits and a shared gas panel coupled to receive different gases from the plurality of gas supply conduits, the shared gas panel mixing the different gases to create mixed gas and evenly splitting the mixed gas to supply a portion of the mixed gas to each of the pluraiity of multi-zone gas feed chambers. The arrangement further includes a plurality of multi-zone gas feed devices comprising at least two multi-zone gas feed devices coupled downstream of the shared gas panel . Each of the plurality of multi-zone gas feed devices is configured to adjustably split the portion of the mixed gas received by each of the plurality of multi-zone gas feed devices from the shared gas panel into a plurality of gas zone flows destined for different zones of a multi-zone gas feed chamber of the plurality of multi-zone gas feed chambers.

{00O8J In another embodiment, the invention relates to a method for supplying process gas to a plurality of mul ti-zone ga feed chambers of a plasma processing system. The method includes providing a plurality of multi-zone gas feed devices comprising at least two multi-zone gas feed devices and flowing different gases from a plurality of gas supply condui ts to a shared gas panel. The shared gas panel mixes the different gases to create mixed gas and evenly splitting the mixed gas to supply a portion of the mixed gas to each of the plurality of multi -zone gas feed devices. The method also includes adjustable splitting, using each of the multi-zone gas feed devices, the portion of the mixed gas into a plurality of gas zone flows destined for different zones of a multi- zone gas feed chamber of the plurality of multi-zone gas feed chambers. BRIEF DESCRIPTION OF THE DRAWINGS

{0009 j The present in ven tion is illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings and in which iike reference numerals refer to similar elements and in which:

j ^' 00010] Fig. 1 shows, in accordance with an embodiment of the invention, an arrangement for supplying process gases to a set of process modules of a cluster tool.

00011 j Fig. 2 conceptually shows, in accordance with an embodiment of the invention, some relevant components within a shared gas panel (SGP).

|00012] Fig, 3 shows the spatial arrangements of some relevant components of the shared gas panel in accordance with one or more embodiments of the invention.

|00013] Fig. 4 shows another view of the mixing valve of the type commonly employed in industry,

100014] Fig. 5 shows the stagger arrangement of the two weldments forming two mixing manifolds of a shared gas panel.

{00015] Fig. 6 shows a typical example prior art multi-zone gas feed arrangement to facilitate di cussion.

{00016] Fig. 7 shows a gas delivery system whereby some multi-zone gas feeds (MGFs) are shared among multiple chambers to facilitate discussion.

{00017] Fig. 8 shows, in accordance with one or more embodiments of the invention, the hybrid approach whereby the gas panel may be shared among multiple chambers to reduce cost while each multi-zone chamber is provided with its own MGF.

100018] Fig, 9 shows, in accordance with one or more embodiments of the invention, the OES arrangement for performing chamber and/or process matching,

DETAILED DESCRIPTION OF EMBODIMENTS

{000191 The present invention will now be described in detail with reference to a few embodiments thereof as illustrated in the accompanying drawings. In the fol lowing 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. 00 2 j Various embodiments are described hereinbelow, including methods and techniques. It should be kepi 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, opio- agneiie, 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 a general-purpose computer and/or a dedicated computing device when appropriately programmed and may include a combination of a computer/computing device and dedicated/programmable circuits adapted for the various |Oi)021] Embodiments of the invention relate to methods and apparatus for reducing the number and size of gas panels in a substrate processing system. In one or more embodiments, it is realized by the inventors herein that if substrate processing systems are constructed and best practices are established such that if multiple process modules of the same cluster tool carry out the same recipe at the same time to execute the same process on different substrates in these different process modules, it is unnecessary to provide each such process module with an independently controllable gas box. I an embodiment, multiple process modules share a gas panel, thereby reducing the number of components that need to be purchased and maintained. Each shared gas panel (SGP) can service two or more process modules simultaneously, f 0002 1 More importantly, embodiments of the inventio involve arrangements and techniques to minimize the volume occupied by components of the shared gas panel (SGP). For example, embodiments of the invention involve staggering the mixing manifolds such that multiple mixing manifolds can occupy the same footprint as one prior art manifold. This is important since modem safety requirements specify that components of a gas panel (such as valves, mass flow controllers, gas line connectors) be isolated from the ambient environment by a containment structure. The air in the containment structure is constantly pumped out and scrubbed (i.e., processed to remove or render relatively harmless any gas that may be leaked from the gas panel, components}. In a example gas panel currently i use, about 150 CFM (cubic feet per minute) of containment structure air needs to be pumped and scrubbed every minute. This pumping and scrubbing needs to be performed whenever the cluster tool is in operation and contributes in a non-trivial way to the cost of owning and operating the ciuster tool when a large number of high volume gas panel s are involved.

{00023] If fewer gas panels are employed in the cluster tool, iess containment structure air needs to be pumped and scrubbed, th ereby reducing the cost of too! ownership . Fiatheraiore, if the inventive shared gas panel (SGP) that services multiple process modules can be kept small in volume such that the components of the shared gas panel fit in a smaller containment structure, less containment structure air needs to be pumped and scrubbed, thereby reducing the cost of owning and operating the cluster tool. With fewer gas panels and gas containment structures, the probabil ity of gas leak to the environment may also be reduced ..

|0002 ] In an embodiment, there is provided an apparatus for supplying selective process gases to a set of process modules that includes at least two process modules. The apparatus includes a gas evacuation containment structure (i.e., a containment structure that isolates the components within the containment structure from the ambient environment and is configured to have its interior air frequently or constantly evacuated to a treatment system). Within the containment structure, there are provided a plurality of -port mixing valves. Each 3-port mixing valve includes an input port, a first output port, and a second output port.

{66025] The process gases are selectively supplied to the input ports of the mixing valves using a plurality of upstream primary val e and/or mass flow controllers. I fan. upstream primary valve and/or mass flow controller shuts off, the process gas associated with the gas hue on which the upstream primary valve and/or mass flow controlled is closed does not get delivered to an input port of a mixing valve and is not used in the processing of the substrate.

00026] In an embodiment, in each 3-por mixing valve, the input port is coupled to both the first output, port and the second output port such that when the 3-port mixing val e is on, the input port provides gas to both the first output port and the second output port. When the 3-port mixing valve is off, the input port stops providing gas to both the first output port and the second output port.

00027] In another embodiment, in each 3-port mixing valve, the input port is selectively coupled to both the first output port and the second output port such that when the 3-port mixing valve is on, the input port provides gas (depending on a control input, which may be pneumatic, hydraulic, or electrical) to 1) both the first output port and the second output port, or 2) only the first output port, or 3) only the second output port. When the 3-port mixing valve is off, the input port stops prov iding gas to both the first output port and the second output port. The first output ports of the mixing valves are coupled to the plural ity of input ports of a first mixing manifold, while the second output ports of the mixing vaives are coupled to the plurality of input ports of a second mixing manifold The first mixing manifold represents the shared gas manifold within which process gases from various first output ports of various mixing valves are mixed before being delivered via a first mixing manifold output port to the first process module of the cluster tool The second mixing manifold represents the gas manifold within which process gases from various second output posts of various mixing valves are mixed before being delivered via a second mixing manifold output port to the second process module of the cl uster tool. Although only a 3 -port mixing valve and 2 mixing manifolds are discussed in the example herein, it should be understood that it is also possible to have a 4-port mixing valve (1 input port and 3 output ports) working with 3 mixing manifolds, or a 5-port mixing valve ( 1 input port and 4 output ports) working with 4 mixing manifolds, and so on. in an embodiment, the first mixing manifold and the second mixing manifold are oriented in parallel, such that their longitudinal axis are parallel to a first direction or such that their manifold input ports generally line up parallel to the first direction. In an embodiment, each of these mixing manifolds assumes the general shape of a tubular length ha ving a longitudinal dimension and a cross section. The cross-section may be circular or may be square or rectangular or any other enclosed shape. The longitudinal dimension forms an axis that is parallel to the aforementioned first dimension in this

embodiment

|00028 Each set of three ports that incl udes the input port, the fu st output port, and the second output port of each mixing valve are lined up in a line that is parallel to a second direction. More importantly, the second direction is at an angle with the first direction with which the mixing manifolds are oriented. As the terra is employed herein, the second direction is deemed to be "at an angle" with the first direction when the second direction is neither orthogonal nor parallel to the first direction. By staggering the mixing manifolds and thus angling each mixing valve such that its input port, first output port, and second output port line up in a direction that is at an angle with the first direction with which the mixing manifolds are oriented, the mixing manifolds may be placed closer together, thereb reducing the volume of the components of the shared gas panel and concomitantly reducing the v olume of the containment structure that houses these components, in some cases, multiple mi ing manifolds can occupy the same footprint formerly employed to accommodate a prior art manifold.

{ ^" 00029] In an embodiment, the mixing valves occupy a given plane. The first mixing manifold is disposed on a first plane under the mixing valves plane, while the inlet lines that supply the process gas to the mixing valve input ports are placed on a second plane under the nnxing valves, with the second plane being disposed between the first plane and the mixing valves, in an embodiment, both the first mixing manifold and the second mixing manifold are disposed on the first plane under the mixing valves while the inlet lines that supply the process gas to the i nput, ports of the mixing val ves are placed on a second plane under the mixing val ves plane, with the second plane being disposed between the first plane and the mixing valves plane. By stacking various components in different verti c al planes, th e volume of the components of the shared gas panel may he further reduced.

100030] The features and advantages of embodiments of the invention may be better understood with reference to the figures and discussions that follow,

{00031 ^' j Fig. 1 shows, in accordance with an embodiment of the invention, an arrangement for supplying process gases to a set of process modules PMl- PM4 of a cluster tool 100. A gas supply 1 10 is shown providing process gases to Shared Gas Panel 1 and Shared Gas Panel 2. Generally speaking, the gas supply includes multiple gas lines, each of which may provide one specific process gas from the gas supply store (such as a storage tank via appropriate supply tubing). Shared Gas Panel 1 is shown supplying process gas(es) to both process modules PMl and PM2. in an embodiment:, PM 1 and PM 2 both execute the same recipe, in another embodiment, PMl and PM2 may execute different: recipes.

100032] Although only two shared gas panels are shown in the example of Fig, L a cluster tool may include any number of shared gas panels and individual (oae-per-process-raodule) gas panels or any mixture thereof. Further, although two process modules per shared gas panel are shown, a shared gas panel may supply process gas(es) to as many process modules as desired. Further, although only four process modules are shown, a cluster tool may have as many process modules as desired. Shared Gas Panel I is shown with a gas evacuation containment structure 102, representing the environmental enclosure for isolating the components of the shared gas panel from the ambient environment. In use, the gas within gas evacuation containment structure 102 is evacuated periodically or continually (using pumps, for example) for treatment (such as scrubbing).

{00033] Fig. 2 conceptually shows, in accordance with an embodiment of the invention, some relevant components within a shared gas panel (SGP) 202, suc as shared gas panel 1 of Fig. I . SGP 202 is shown receiving four process gases through four gas input lines 204A, 206A, 208A, and 21 OA although a typical SGP may receive or more gases (the number of gas input lines may vary as desired). Each of gas input lines 204 A, 206 A, 208 A, and 21 OA is coupled to a respective primary valve 204B, 206B, 208B, and 21.0B. Each primary valve may be

programmaticaUy controlled to select which process gas may he provided to the mixing

manifolds 250 and/or 252 (to be discussed later). A set of purge valves 204D, 206D, 208D, and 210D, which is part of a purging system, are also sho wn altlioug purge v alves and purge systems are conventional and are not past of the present invention.

100034] Mass Flow Controllers (MFC) 204C 206G 208C. 210C are in gaseous

communication with primary valves 20 A, 206 A, 208A, and 21 OA to selectively receive input process gas from the primary valves (depending on which primary valve is open). As is well known, a mass flow controller is employed to regulate (including shutting off) the flow rate and/or pressure of the gas delivered. Downstream of the mass flow controllers are the mixing valves, each of which is in gaseous communication wit a respecti ve mass flow controller. In the example of Fig. 2, there are two mixing manifolds 250 and 252 coupled in gaseous

communication with each, of mixing valves 204E, 206E, 208E, and 210E. Since each mixing valve has one input port for receiving a process gas from it respective manifold (e.g., mixing valve 204E receiving process gas from MFC 204C and mixing valve 208E receiving process gas from MFC208C and two output ports for coupling to the two mixing manifolds 250 and 252, each mixing valve is thus a 3-port val ve (one input port and 2 output ports). Mixing valves 204E-210E may be pneumatically operated, electrically operated, mechanically operated, or hydraulically operated, for example.

{00035] Mixing manifold 250 receives its input gas(es) via the mixing valves and mixes the process gas(es) before delivering the process gas(es) to its process module PM t via an isolation valve 260. Likewise, mixing manifold 252 receives its input gas(es) via the mixing valves and mixes the process gas(es) before delivering the process gas(es) to its process module PM 2 via an

S isolation valve 262. Isolation valves isolate the process modules from the gas panels and are employed for volume/flow control purposes during processing and maintenance, for example. {Ό0036] In the example of Fig. 2, the mixing valves are siog!e-input-two-common-outpufts valves, in other words, when the valve is open, gas from the input port is provided to both output ports simultaneously, in this case, each mixing valve is essentially a splitter valve and both mixing manifolds 250 and 252 will receive the same type of process gas(es).

£00037] In other embodiments, the mixing valve may, as discussed earlier, selectively provide gas from its i nput port to any one of the output ports, any combination of output ports, or to all output ports. With this capability, it is possible to have different mixtures in mixing manifolds 250 and 252 to execute different recipes in the two process modules associated with SGP 202, for example. As mentioned, more than 2 output ports may be provided per mixing valve if there are more than 2 mixing manifolds and/or more than 2 process modules.

100038] In accordance with an embodiment, the mixing manifolds are disposed under the mixing valves in order to save space and to reduce the volume within the containment enclosure. This is best seen in Fig, 3 wherein mixing manifolds 250 and 252 are disposed under plane portion 302, representing a portion of a plane at which the mixing valve flange (402 of Fig. 4) may be disposed. In Fig. 3, mixing manifolds 250 and 252 occupy the same plane in the Y dimension under the mixing valve. Further, gas line portion 310 that is coupled to the input port (marked with reference number 310 A) occupies, at its bottom end, a different plane in the Y- diraension that is higher than the Y -dimension plane occupied by the mixing manifolds 250 and 252. in oilier words, the input gas line ( whether is vertical portion or the circumference of its horizontal portion) does not extend downward to the plane occupied by mixing manifolds 250 and 252. By displacing the space-occupying gas lines vertical ly and also front the mixing valves themselves, it is possible to squeeze mixing manifolds 250 and 252 closer together (in the Z dimension in the example of Fig. 3} to save space. Accordingly, less horizontal space (in the X- Z plane of Fig. 3 } is required, leading to reduced SGP volume. This is particularly true for industry-standard rectangular box-shaped enclosures since the height of such an enclosure is typically governed by its tallest component. If components are spread-out in the X-Z plane, not only would the footprint be unduly large but a lot of interior volume space would have been wasted as a result. 00039] In the example of Fig. 3, a process gas is provided via gas line 310 and travels upward portion 31 OA in the + Y direction to the input port of the mixing valve via hole 320 (hole 320 represents an imaginary cut-away aperture in gas line portion 31 OA for illustration purposes). If the mixing valve is open, the process gas will be distributed to one or both of output ports by traveling down one or both of holes 322 and/or 324 in the - Y direction. Holes 322 and 324 represent imaginary cut-away apertures in gas line portions 250A and 252A (which are in gaseous communication with mixing manifolds 250 and 252 respectively) to be mixed in manifolds 252 and 250 respectively.

|00040] As can be seen in the example of Fig. 3, gas is provided to the mixing manifolds 252 and 250 from portions 252A and 250A via T-coupiings 372 and 370. Gas is provided to the input port of the mixing valve (by traveling up portion 310A) via an L-coupling 374. A short horizontal portion 310B is employed to provide the input gas in a plane that is higher (more positive in the Y direction) than the plane occupied by the mixing manifolds 250 and 252).

OO04I] In one or more embodiments, the tubing lengths, number of turns, and/or the tubing construction/diameters of the two gas paths from the two mixing valve outlet ports to its two mixing manifold are kept as similar as possible to ensure that each mixing manifold receive the same mass flow iron) the MFC with the same pressure, gas velocity, and concentration, in one or more embodiments, these gas paths may be optimized with different tubing lengths, number of turns, and/or tubing diameters/construction to ensure that each mixing manifold recei e the same mass flow from the MFC with the same pressure, gas velocity, and concentration.

|0O42 ^' | Fig. 3 also shows another process gas provided via L-coupling 368 and gas line 360 to another mixing valve coupled to plane portion 386 and distributed t the two mixing manifolds 250 and 252 via lines 362 and 364.

{00043] Fig. 3 shows mixing manifolds 250 and 252 oriented along direction X such thai its input ports line up along the same direction X. Thus, input ports of manifold 252 (i.e., the upward pointing portions of T-couplings 366 and 372) that couple to portions 364 and 252A respectively line up parallel to direction X of Fig. 3 (also directio X of Fig. 5). Similarly, input ports of manifold 250 (i.e., the upward pointing portions of T-couplings 370 and 376) that couple to portions 250A and 362 respectively line up parallel to direction X of Fig. 3. Similarly, input ports of the mixing valves (i.e., the upward pointing portions of L -couplings 374 and 368) that couple to portions 31 OA and 360 respectively line up parallel to direction X of Fig. 3. Since each mixing manifold has a long dimension (e.g., longitudinal dimension in the case of a tubular structure such as those shown in Fig, 3) and a cross section (e.g., a round or some other polygonal cross section in the case of a tubular structure), the long dimension of the mixing manifold represents the mixing manifold direction herein. In the example of Fig. 3, this mixing manifold direction is also in the direction +/- X.

{00044j The three input/output ports (or at least one i nput port and I output port) of each mixing valve line up i a direction that is at an angle with direction X of Fig. 3. In the example of Fig. 3, the input post for the mixing val ve that is coupled plane portion 302 occupies the positions denoted by reference number 320. The two output posts for the mixing valve that is coupled to plane portion 302 occupy the positions denoted by reference numbers 322 and 324. As can be seen holes 320, 322, and 324 line up along the direction of line 380, which is at an angle (i.e. other than orthogonal, or parallel) to the X direction (i.e., the mixing manifold direction or the mixing manifold longitudinal direction).

OO045] Fig. 4 shows the three ports 404, 406, and 408 of the mixing valve. Input port 406 is sandwiched between output ports 404 and 408. Together, ports 404, 406, and 408 line up in the direction 414, which is at an angle to the mixing manifold direction X. In other words, the mixing manifolds are oriented in the direction X of Fig. 4, and the ports of a gi ven mixing valve (either a!l three or the input port to the mixing valve and either of the output ports to the two mixing manifolds) line up along direction 414, which is at an angle (i.e.. not orthogonal or parallel) to mixing .manifold direction X. This angle may be deemed diagonal or an acute angle (less than 90 degrees) depending on which direction is deemed positive for reference direction X, for example. For completeness, body 412 housing the valve body and controls is also shown in Fig, 4, Also shown are mounting flange 402 and mounting holes 414 A, B, 414C, and 414D. In practice, flange 402 of Fig. 4 mates with tabes 252 A, 31 OA, and 250A of Fig. 3 at the plane shown by plane portion 302.

{uu046j As can be seen in the example of Fig. 5, the mixin manifolds are parallel and essentially "staggered" such that each set of 3 ports of each mixing valve (1 input port to the mixing valve and 2 output ports to the two mixing manifolds) line up parallel to direction 506, In one or more embodiments, these two mixing manifolds are identical weldment parts to save inventory and manufacturing cost.

Π |00047] Similarly, the input port for the mixing valve that is coupled to mixing manifold input ports 510 and 514 occupy the position denoted by reference number 512, Thus this mi ing valve input port and its two mixing val ve output ports {coupled to mixing manifold input ports 510 and 514) line up parallel to direction 506. As mentioned, direction 506 is considered to be "at an angle" with the X direction { which is parallel to the longitude of the mixing mani folds) if they are not. orthogonal or parallel to one another.

£00048] Fig. 5 also shows a mixing assembly output port 502, representing the port for outpotting the mixed process gas to the process module coupled to mixing manifold 250.

Another mixing assembly output post (not shown to improve clarity in Fig. 5) is also provided for mixing manifold 252. The output port may be provided at one end of the mixing manifold, or may be provided anywhere along its shared length.

{ΘΘ049) By staggering the mixing manifolds such that the ports of a given mixing valve line up along a direction (such as 506) that is at an angle relative to the mixing manifold longitudinal axis directio X and also vertically displacing components (such that portion 3 0B occupy a different plane compared to the plane occupied by mixing manifolds 250 and 252 in Fig, 3 and the mixing valves occupy a different plane), it is possible to dispose the input line (such as portion 310A of Fig. 3) to a mixing valve in between the two mixing valve output lines (such as portions 250A and 252 A of Fig, 3) and still allow the mixing manifolds to be squeezed together tightly in the Z direction in Fig, 3, This is particularly true if industry-standard mixing val ves having its input and output ports lined up in a single line are to be used. If the ports are not angled relative to the mixing manifold longitudinal axis direction and disposed at different planes, such volume-saving arrangement would not have been possible with these industry- standard valves.

{00050] As can be appreciated from the foregoing, embodi ments of the in vention permit a single shared gas panel to selectively provide process gas(es) to a plurality of process modules. By ensuring that each mixing manifold receive the same mass flow, matching issues are eliminated. By reducing the number of gas panels per cluster tool fewer gas panel components (such as valves, MFCs, connec tors, transducers, sensors, etc.) need to be acquired and or maintained. Further, one or more embodiments of the in vention stagger the mixing man ifolds (e.g., in the X-Z direction of Fig. 3) and/or vertically displace (e.g., in the Y direction of Fig. 3) the lines that feed the ports of the mixing valves as well as the valves themselves (such that at ieasf 3 planes are involved), the components can be squeezed into a smaller footprint and thus smaller volume, thereby reducing the volume occupied by the gas panel components. When such volume is reduced, less air needs to be pumped and purged, leading to reduced operating cost

{00051] In some plasma processing tools, one or more plasma processing chambers may be employed to perform processes that require gas feeds to multiple zones (i.e., regions) of the chamber. As an example, dielectric etch processes may employ multi-zone gas feeds that provide tbe process gas to multiple zones in the chamber either simultaneously or at different times, in a specific example, one gas feed may provide the process gas to the center zone of the chamber (such as above the substrate center) while another gas feed may provide the process gas to the edge of the chamber or the edge of the substrate.

{ΘΘ052) In the past, a multi-zone gas feed (MGF) device has been employed to ensure that the process gas is adjustably provided to different chamber zones in the appropriate ratio as required by the recipe. For example, one recipe may require that the center zone receives 80% of the gas flow while the edge zone receives 20% of the gas flow. Another recipe at another time ma require that the center zone receives 10% of the gas flow while the edge zone receives 90% of the gas flow.

{00053] Generally speaking, the MGF is disposed downstream of the gas panel in a typical prior art plasma processing tool to perform the work of di iding the incoming gas flow into multiple gas flows for multiple zones of the chamber. An example MGF is further discussed in details in a commonly assigned US issued patent entitled "GAS DISTRIBUTION SYSTEM WITH TUNING GAS" by Larson et al. (Patent No. 7,169,231 B2, issues January 30, 2007 and incorporated by reference herein,

{00054] When a gas panel is shared among multiple chambers (such as two chambers for the purpose of explanation although more than two chambers can share a single gas panel), the inventors herein have discovered that sharing the MGF among multiple chambers actually is a disadvantageous approach. In a counter-intuitive manner, even though tbe gas panel may be shared among multiple chambers, optimal operation is achieved if each chamber is provided with its own MGF.

{00055] To facilitate discussion. Fig. 6 shows a typical example prior art .multi-zone gas feed arrangement whereby the incoming process gas from gas panel 602 is provided to MGF 604. In a simplified explanation, MGF 604 has a plurality of inlet valve-ori free-outlet valve sets, of which ix sets are shown in the example of Fig. 6. Thus there is shown an inlet valve II that is in fiuidic communication with orifice 01 , which is in turn in fiuidic communication with exit valve EI . Likewise, there is shown an inlet valve 12 that is in fiuidic communication with orifice 02, which is in turn in fiuidic coramuiiicaiion with exit valve E2 and so on,

{00056] The process gas from gas feed 606 flows out of gas panel 602 to inlet valves 11-16. in an embodiment, inlet valves 11 -16 are normally open valves although this is not a requirement. Orifices 01.-06 have different cross-sectional dimensions or orifice sizes to present different flow resistance to the process gas. These orifice sizes are highly precise, in an embodiment, the orifices are made of a jewel material such as ruby to ensure a high, degree of accuracy.

{00057] Each of exit valves El -E6 may be selectively opened or closed to control the flow ratio of process gas provided to conduits 620 and 622, thereby controlling the flow ratio of the process gas to the center zone (conduit 620) or to the edge zone (conduit 622), Thus when different combinations of exit valves E1-E6 are closed, different ratios of center flow to edge flow may be obtained. Although onl two exit flows (center and edge) are discussed in this example, it should be understood that more than two exit flows may be provided. Hie MGF is said to adjustably split the incoming mixed gas from the shared gas panel and to adjustably provide (or adjustably flow) different gas flows at different ratios destined for various multi-zone gas feed chambers since various combinations of these valves can be opened and/or closed to achieve different ratios. The valves may be electrically, pneumatically, or mechanically

controlled in response to control circuitry to flexibly provide the aforementioned flow ratios to accommodate recipe requirement.

1000581 In the past, when a plurality of multi-zone chambers are involved, the temptation and natural approach may be to share a MGF among multiple chambers. One approach to pro viding the center flow process gas out of conduit 620 to multiple chambers may involve the use of a splitter valve. Likewise, the edge flow process gas out of conduit 622 may be di vided into multiple edge flows for multiple chambers by the use of another splitter val ve.

{00059] This approach is shown in Fig, 7 whereby splitter valve 740 is employed to split the center flow out of MGF 708 (via conduit 720) to two gas flows in conduits 742A and 7426. The gas flow in conduit 742A may be destined for the center zone of the first plasma processing chamber while the gas flow in conduit 742B may be destined for the center zone of the second plasma processing chamber, for example. Likewise, splitter valve 750 is employed to split the edge flow out of conduit 722 to two gas flows in conduits 752A and 752B, The gas flow in conduit 752 A may be destined for the edge zone of the first plasma processing chamber while the gas flow hi conduit 752B may be destined for the edge zone of the second p lasma processing chamber, for example.

{00060] While the approach of Fig. 7 may achieve the sharing of MGF 708 among multiple chambers, the inventors herein have discovered that this approach results in several

disadvantages. First, in order to provide a given center flow rate to each chamber, MGF 708 must source twice the flow rate (assuming MGF 70S of Fig. 7 is shared between two chambers) so that each chamber would receive the required flow rate after splitting via splitter valves 740 and 750.

{00061] Although a MGF is an off-the-shelf part, each MGF is a highly precise device and is manufactured with valves and orifices optimized for a certain pressure range and flow range. The requirement that the MGF handles twice the flow rate and/or twice the input gas pressure would force MGF 708 to operate outside of its optimal ranges, thereby degrading MGF accuracy. {00062] Even if new MGFs can be designed t handle the higher flow/pressure (assuming cost is no consideration since MGF design and qualification is an expensive and time-consuming process), the use of splitter valves 740 and 750 also introduces undesirable inaccuracy since splitter valves are typically much less accurate than MGFs. Thus, while MGF 70S may be able to accurate provide the proper center/edge flow ratio, splitter valve 740 may be unable to evenly spl it the center flow out of MGF 70S into two equal center flows for the two center zones of the two chambers sharing the MGF. Likewise, splitter valve 750 may be unable to evenly split the edge flow out of MGF 708 into two equal edge flows for the two edge zones of the two chambers sharing the MGF.

{00063] Thus, in a counter-intuitive manner, and especially in view of the relatively high cost of the MGF and the desire to share gas delivery system components among multiple chambers, it has been found by the inventors herein that multi-zone gas delivery into each chamber works best if each chamber requiring the multi-zone gas delivery is equipped with its own MGF.

Doing so also alleviates the low-flow problem associated with comnierciaily available mass flow controllers, as will be discussed later herein. |60064] Fig. 8 shows, in accordance with one or more embodiments of the invention, the hybrid approach whereby the gas panel may be shared among multiple chambers to reduce cost while each multi-zone chamber is provided with its own MGF. The arrangement of Fig. 8 represents a set of shared gas panel associated MGFs/associated ch ambers although there may be multiple such sets in a gi ven cluster plasma tool. As can be seen in Fig. 8, shared gas panel 802 receives different process gases from a plurality of gas conduits 810. The process gases are mixed in the dual manifolds as discussed earlier according to the desired recipe and provided via conduits 812 and 814 to two respective chambers SI 6 and 818. Since chambers 816 and 818 are multi-zone gas feed chambers (two gas feed zones for each chamber in the example of Fig. 8 although three or more zones are possible), GFs 804 and 806 are provided downstream of shared gas panel 802.

{ΘΘ065) MGF 804 receives the mixed process gas front shared gas panel 802 (via conduit 812} and performs the dividing of the mixed process gas into various flows destined for various zones of chamber 816. i the example of Fig. 8, MGF 804 may provide for example 70% of the incoming flow from conduit 812 to the center zone of chamber 816 (via conduit 820} and 30% of the incoming flow from conduit 8.12 to the edge zone of chamber 816 (via condui 822).

{66066] likewise, MGF 806 receives the mixed process gas from shared gas panel 802 (via conduit 814) and performs the dividing of the mixed process gas into various flows destined for various zones of chamber 818, hi the example of Fig. 8, MGF 806 provides 70% of the incoming flow from conduit 814 to the center zone of chamber 818 (via conduit 826} and 30% of the incoming flow from conduit 814 to the edge zone of chamber 818 (via conduit 828 ).

100067] In this manner, a hybrid approach is achieved whereby although the gas panel 802 is shared between chamber 816 and 818, each chamber is provided with its own MGF (804 and 806) to ensure accurate gas delivery to the various zones of each chamber.

J66068S The advantages with the approach exemplified by Fig, 8 are many. For example, as mentioned, it is well-known that each MGF is a highly precise device and is manufactured with valves and orifices optimized for a certain pressure range and flow range. The approach of Fig. 8, unlike mat of Fig. 7, does not require the MGF to operate outside of its optimal flow/pressure range. This is because each MGF only handles the gas flow/pressure for its own chamber, which is exactly the situation with current plasma tools in which the gas panels are not shared. Thus existing MGFs can be used without loss of accuracy. |00069j Further, unlike the situation in Fig. 7, it is not necessary to employ {relatively} inaccurate splitter valves (such as splitter valves 740 and 750 of Fig. 7} to accommodate the multi-zone gas feed requirement of the chambers, In the example of Fig, 8„ flow accuracy is limited primarily by the MGFs (which tend to be highly accurate clue to their highly precise orifice tolerances) and by the shared gas panel design. The shared gas panel also tends to be highly accurate since, as discussed earlier, manifolds and feed lines in the shared gas panel may be optimized such that the shared gas panel can accurately share its incoming gas flow among multiple chambers. For example, the length of the conduits and manifolds and the number of turns and the gas flow resistance to each chamber may be timed in the shared gas panel such that gas flow sharing is highly accurate (under 0.5 % difference in some examples). As a result, the arrangement of Fig. 8 results in a highly accurate gas delivery system to the various zones of the various chambers sharing the shared gas panel. Additionally, since the approach of Fig. 8 accommodates multi-zone gas feed chambers while allowing sharing of the gas panel the number of mass flow con trollers (MFCs) and other costs associated with the gas panel are substantial iy reduced.

|00070j This approach of the example of Fig. 8 also alleviates the low-flow problem associated with off-the-shelf MFCs. The low flow problem occurs when a given recipe requires a low flow rate for a particular type of constituent process gas, typically much lower than the optimal flow range for an off-the-shelf MFC.

{00071] For example, some off-the-shelf MFCs may operate optimally for 5-20 seems (standard cubic centimeters per minute). If the recipe calls for 2 seem of a particular constituent gas, gas delivery by that MFC; and associated conduits tend to be less than accurate since the required gas flow is quite small compared to the optimal flow range for which the MFC is designed,

j By sharing a gas panel (and the MFCs within) among multiple chambers, each MFC may handle a greater amount of gas flow since the MFC delivers gas for more than one chamber. In the above example, the MFC may now handle 4 seem, which is closer to the optimal range and will tend to be more accurate. Further, as discussed, sharing a gas panel also reduces real estate usage (since there wil l be fewer conduits with fewer gas panels) and lower the

environmental remediation cost. 00 73j In one or more embodiments, OES (Optical. Emission Spectroscopy) may advantageously be used during calibration or during processing in. order to match, processes and/or match chambers. In this aspect, OES output is used as a feedback signal to control the valves associated with one or more chambers to ensure process matching or chamber matching with, another chamber. With reference to Fig. 9„ for example, OES sensor 904 may be employed to obtain an OES signal from chamber 816. Likewise, OES sensor 906 may be employed to obtain an OES signal from chamber S 18.

{00074] If the recipe calls for equal flows in these two chambers, the OES signal from OES sensor 904 should substantially match the OES signal from OES sensor 906. If the OES signals differ (based on an analysis performed by logic 930 which takes as its inputs the OES signals from OES sensors 904 and 906), control signals may be sent to one or more MGF output valves 910, 12, 914 and/or 916 (disposed between the MGF and the chamber) to control, the zone flow(s) into the individual chambers. Logic 930 may be dedicated hardware or programmable logic and ma include a processor executing computer readable code.

fyy07S| The control strategy may be based on a library of previously acquired OES signals from the chambers to be matched and corresponding valve control settings in order to achieve chamber matching and/or process matching, for example. Alternatively or additionally, valve controi settings may be detennsned algorithmicaliy, taking into account the OES signals from the chambers to be matched and or other chamber/process parameters from those chambers. In contrast to prior art OES approaches, embodiments of the invention propose looking across multiple chambers and taking into account OES signals from multiple chambers (and optionally other chamber and/or process parameters from multiple chambers) in order to control valve settings, thereby achieving process matching and/or chamber matching among a pluralit of chambers. This is different from prior art approaches whereby an. OES signal associated with a chamber i s used only for process control of that chamber, and OES signal s from other chambers are not taken into account in that process control.

09076] Control signals from logic 930 may also be sent to MGF input valves 920 and/or 922 (disposed between the MGF and the shared gas panel) to improve chamber matching and/or process matching. Although not shown i Fig. 9, control signals from logic 930 may

alternatively or additionally be sent to individual MGF inlet valves or individual MGF outlet valves associated with individual inlet valve-orifice-outlet valve sets (e.g., valves 11 , 12, El , or

E2 in the example of Fig. 6) in order to more finely control chamber/process matching.

{00077] 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. For example, although the apparatus is described in the example, the invention also covers methods for providing, making and/or assembling the apparatus by coupling the components together to form the structure described or for operating the plasma processing system by operating the apparatus to employ its intended functionality and advantages. Also, the title and summary are provided herein for convenience and should not be used t construe the scope of the claims herein . Further, the abstract is written i 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 man 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.