Slurrydeliveryarm.

1、Slurry delivery armBACKGROUND OF THE INVENTION1. Field of the InventionEmbodiments of the present invention generally relate to a method and apparatus fordispensing polishing fluids in a chemical mechanical polishing system.2. Description of the Related ArtChemical mechanical polishing is one proces

2、s commonly used in the manufacture ofhigh-density integrated circuits. Chemical mechanical polishing is utilized to planarizea layer of material deposited on a semiconductor wafer by moving the substrate incontact with a polishing surface while in the presence of a polishing fluid. Material isremove

3、d from the surface of the substrate that is in contact with the polishing surfacethrough a combination of chemical and mechanical activity. One type of polishing fluidcommonly used in chemical mechanical polishing applications is a slurry containingchemical agents and abrasive particles. The abrasiv

4、e particles in the slurry enhancethe mechanical removal of material from the substrate while exposing the underlyingsurface to the chemical agents in the polishing fluid.Polishing fluid is typically provided to the polishing surface through a delivery arm thatis positioned over the polishing surface

5、 during processing. The dispense point (i.e.,the point at which the polishing fluid flows from a delivery tube to the polishingsurface), and the amount and concentration of polishing fluid provided to the polishingsurface are attributes that impact the quality of substrate processing. To ensureaccep

6、table polishing results, conventional polishing fluid delivery systems rely ondetent mechanisms to ensure repeatable positioning of the polishing fluid delivery armat a predefined dispense location along with various flow control devices utilized tomonitor and control the amount and concentration of

7、 polishing fluid delivered to thepolishing surface.One problem associated with this conventional arrangement is that the polishing fluiddelivery arm is limited to the pre-defined position wherein the detent mechanismengages the arm. Thus, control of the dispense point on the polishing surface is lim

8、itedto physically changing the delivery tubes position along the arm. Thus, in order tochange the dispense point to achieve a desired processing result, polishing must beinterrupted to allow for service personnel to mechanically adjust the position of thenozzles along the length of the slurry delive

9、ry arm, thereby increasing the risk ofequipment damage and disadvantageously decreasing substrate throughput.Another issue affecting many conventional polishing fluid delivery systems is thetendency of abrasive particles within the slurry to attach and agglomerate at tubefittings and around flow con

10、trol components. For example, the interfaces between theslurry delivery tube and tees, valves, restrictors or other devices include small seamsor gaps along the flow path where abrasive particles from within the slurry tend toadhere and conglomerate. As the number of abrasive particles accumulating

11、at theselocations grows, chains or groups of the conglomerated particles break free and traveldownstream through the delivery tube to the polishing surface where they come incontact with the surface of the substrate being polished. These conglomeratedparticles often cause scratching of the substrate

12、 surface and defect generation.Therefore, it would be desirable to minimize and/or eliminate any seams along theslurry flow path to minimize the introduction of conglomerated particles to the polishingsurface.Therefore, there is a need for an improved slurry delivery system.SUMMARY OF THE INVENTIONA

13、 polishing fluid delivery apparatus has been provided that in one embodimentincludes a support member, a dispense arm, at least one polishing fluid delivery tubeand a variable restricting device. The dispense arm extends from an upper portion ofthe support member and has an outlet of the delivery tu

14、be coupled thereto. Therestricting device interfaces with the delivery tube and is adapted to provide a variablerestriction to flow passing through the delivery tube. In another embodiment, therestricting device is a pinch valve and the tube is continuous from the outlet to beyonda portion that inte

15、rfaces with the pinch valve. In yet another embodiment, the positionof the delivery arm is controllable.BRIEF DESCRIPTION OF THEDRAWINGSA more particular description of the invention, briefly summarized above, may be hadby reference to the embodiments thereof that are illustrated in the appended dra

16、wings.It is to be noted, however, that the appended drawings illustrate only typicalembodiments of this invention and are therefore not to be considered limiting of itsscope, for the invention may admit to other equally effective embodiments.FIG. 1 is a top view of an illustrative chemical mechanica

17、l polishing system having oneembodiment of a polishing fluid delivery system;FIG. 2 is a sectional view of a polishing fluid delivery arm of the polishing fluid deliverysystem of FIG. 1;FIGS. 3A-C are simplified top views of the polishing fluid delivery arm in variouspositions;FIG. 4 is a bottom per

18、spective view of one embodiment of a polishing fluid deliveryarm;FIG. 5 is a top view of another embodiment of a polishing fluid delivery arm; andFIGS. 6-7 are simplified top views of other embodiments of a polish fluid deliverysystem.To facilitate understanding, identical reference numerals have be

19、en used, whereverpossible, to designate identical elements that are common to the figures.DETAILED DESCRIPTIONFIG. 1 is a top view of an illustrative chemical mechanical polishing system 100 havingone embodiment of a polishing fluid delivery system 102 of the present invention. Thechemical mechanica

20、l polishing system 100 generally includes a factory interface 104, acleaner 106 and a polisher 108. One polishing system100 that may be adapted tobenefit from the invention is a REFLEXION? chemical mechanical polishing system,available from Applied Materials, Inc., located in Santa Clara, Calif. Ano

21、ther polishingsystem100 that may be adaptedto benefit from the invention is described in U.S. Pat. No. 6,244,356,issued Jul. 2, 2002 to Birang, et al., which is incorporated by reference in its entirety.In one embodiment, the factory interface104 includes a first orinterface robot 110 adapted to tra

22、nsfer substrates from one or more substrate storagecassettes112 to a first transfer station 114. Asecond robot 116 is positioned between the factory interface 104 and the polisher 108and is configured to transfer substrates between the first transfer station 114 of thefactory interface104 and a seco

23、ndtransfer station118 disposed on the polisher108. The cleaner 106 istypically disposed in or adjacent to the factory interface104 and isadapted to clean and dry substrates returning from the polisher 108 before beingreturned to the substrate storage cassettes by the interface robot 110.The polisher

24、 108 includes at least one polishing station126 and atransfer device 120 disposed on a base 140. In the embodiment depicted in FIG. 1, thepolisher108 includes three polishingstations 126, each having a platen130 that supports a polishingmaterial 128 on which the substrate is processed.The transfer d

25、evice120 supports at least one polishing head124 thatretains the substrate during processing. In the embodiment depicted in FIG. 1, thetransfer device120 is a carousel supporting onepolishing head 124 on each of four arms 122. One arm 122 is cutaway to show thesecond transfer station118. The transfe

26、r device 120facilitates moving substrates retained in each polishing head124between the second transfer station118 and the polishing stations126 where substrates are processed. The polishing head124 isconfigured to retain a substrate while polishing. The polishing head 124 is coupled to atransport m

27、echanism that is configured to move the substrate retained in the polishinghead124 between the transferstation 118 and the polishing stations 126. One polishing head 124 that may beadapted to benefit from the invention is a TITAN HEAD? substrate carrier, availablefrom Applied Materials, Inc.The seco

28、nd transfer station118 includes a load cup142, an inputbuffer 144, an output buffer142 and a transfer station robot148.The input buffer144 accepts a substrate being transferred to thepolisher 108 from the second robot116. The transfer station robot148 transfers the substrate from the input buffer144

29、 to the load cup142. The load cup 142 transfers the substrate vertically to the polishing head 124,which retains the substrate during processing. Polished substrates are transferredfrom the polishing head124 tothe load cup 142, and then moved by the transfer station robot148 tothe output buffer142.

30、From the output buffer142, polishedsubstrates are transferred to the first transfer station114 by thesecond robot 116 and then transferred through the cleaner 106. One second transferstation118 that may be adapted to benefit from theinvention is described in U.S. Pat. No. 6,156,124, issued Dec. 5, 2

31、000, to Tobin, whichis incorporated by reference in its entirety.In one embodiment, the polishing station126 includes a platen130that supports a polishing material128. During processing, thesubstrate is held against the polishing material128 by the polishinghead 124. The platen 130 rotates to provid

32、e at least a portion of the polishing motionimparted between the substrate and the polishing material 128. Alternatively, thepolishing motion may be imparted by moving at least one of the polishing head124or polishing material128 in a linear, orbital, random, rotary or other motion.The polishing mat

33、erial128 may be comprised of a foamed polymer, suchas polyurethane, or may be a fixed abrasive material. Fixed abrasive material generallyincludes a plurality of abrasive elements disposed on a flexible backing. In oneembodiment, the abrasive elements are comprised of geometric shapes formed fromabr

34、asive particles suspended in a polymer binder. The polishing material 128 may bein either pad or web form.The polishing fluid delivery system102 includes at least onepolishing fluid supply 150 coupled to at least one polishing fluid delivery arm assembly152. Generally, each polishing station126 iseq

35、uipped with a respective delivery arm assembly152 positionedproximate to the respective platen130. In the embodiment depicted inFIG. 1, the three polishing stations126 each have one delivery armassembly 152 associated therewith. Each polishing fluid delivery arm assembly 152may be coupled to a dedic

36、ated polishing fluid supply 150, or may be configured toreceive polishing fluid from a single or multiple shared polishing fluid supplies. Eachdelivery arm assembly 152 includes at least one fluid delivery tube 154 coupled tothepolishing fluid supply 150.FIG. 2 depicts a sectional view of one embodi

37、ment of the polishing fluid delivery armassembly152. The polishing fluid delivery armassembly 152 includes a dispense arm202 affixed to and extendinglaterally from the upper portion206 of a support member 204 above atop surface 210 of the base 140. The lower portion208 of the supportmember 204 is ro

38、tatably mounted in and extends through a bottom212of the base 140. A bearing assembly 214 is disposed between the support member204 and the base 140 to allow the dispense arm 202extending from the upper portion206 of the support member204 to berotated between a standby or purge position clear of the

39、 platen130 anda dispense position over the polishing material 128 (as shown in FIG. 1).For simplicity in the embodiment depicted in FIG. 2, a singledelivery tube 154 is shown routed along the dispense armsupplying polishing fluid to the polishing material the platen 130.However, any number of delive

40、ry tubes utilized to supplypolishing fluid from a common dispense arm a single platen130. The delivery tube is comprised of a resilient and flexible material, such as silicone.The interior of the tube must be substantially free of interior anomalies.In one embodiment, the delivery tube154 is routed

41、from an inlet end222 coupled to the polishing supply150 through a passage 216 formedin the support member 204 and outward along a channel 220 disposed in the dispensearm 202. An outlet end 224 of the delivery tube 154 is positioned at a distal end218of the dispense arm202. The distalend 218 includes

42、 a tube receiving passage270 through which theoutlet end 224 of the delivery tube154 is disposed. The deliverytube 154 is secured in the passage270 by a clamp 272, which in oneembodiment is a set screw. Alternatively, the delivery tube154 maybe positioned at other locations along the length of the d

43、ispense arm 202. Inembodiments utilizing multiple delivery tubes 154, any one of the tubes may be fixed toor positionable along the dispense arm202,and have their outlet ends224 grouped in a common location or spacedapart to dispense polishing fluid at predefined locations across the diameter of the

44、polishing material 128.In one embodiment, the delivery tube154 is a single, continuousmember running from its inlet to outlet ends 222, 224. The delivery tube 154 has nocrevasses, seams or other anomalies present along its inner surface 226 that wouldotherwise provide attachment points for abrasive

45、or other particles that may beentrained or form in the polishing fluid, thereby advantageously decreasing theprobability of particle agglomeration within the tube and there release to the polishingmaterial128 where they may contact a substrate130 beingprocessed. The substantial elimination of releas

46、e of agglomerated particles results inincreased product yield by reducing scratching and substrate defects. Alternatively, thedelivery tube154 may besegmented, but with increased potential for diminished yield.In one embodiment, the polishing fluid supply 150 includes a pressure vessel 232 anda pres

47、sure control system234. The pressure vessel 232202 for128 disposed on154 may be202 tocontains a polishing fluid244, and may be optionally coupled to abulk supply system (not shown) for periodic replenishment of polishing fluid. Thepressure vessel 232 has an inlet port238 andoutlet port 240. The inle

48、t port238 is coupled to the pressurecontrol system 234 while the outlet port240 is coupled to inlet end222 of the delivery tube154.The pressure control system234 generally controls the pressurewithin and/or delivers gas to the pressure vessel232. Gas 242 withinthe pressure vessel232 imparts a pressu

49、re on the polishing fluid244232, thereby driving the polishing240 and the delivery tube 154, and224 to the polishing material234 may include regulators, pumps and the like to control the pressure applied to thepolishing fluid244 disposed in the pressure vessel232. A pressure sensor 236 iscoupled to

50、the pressure vessel232 to provide a metric indicative ofthe pressure within the pressure vessel232.A flow sensor 246 is interfaced with the delivery tube154 to providea metric indicative of the flow of polishing fluid passing therethrough. In embodimentswhere the delivery tube154 isconfigured to flo

51、w fluids not prone to particle formation, for example de-ionized waterand chemical reagents, flow sensors that engage the fluid, such as paddle wheels andthe like may be utilized.In embodiments where the delivery tube154 is configured to flowfluids containing particles and/or prone to particle forma

52、tion, such as abrasivecontaining slurries, non-intrusive flow sensors, such as sonic flow transducers and thelike may be utilized to maintain a continuous non-interrupted inner wall integrity of thedelivery tube 154 between the polishing fluid supply150 andthe outlet end224 ofthe delivery tube154.To

53、 enhance control over the polishing fluid flowing through the polishing fluid deliverytube154, a variable restricting device260is utilized to interface with the delivery tube154. In theembodiment depicted in FIG. 2, the restricting device260 isconfigured to apply a bias to the exterior of the delive

54、ry tube154,resulting in a reduction of the interior sectional area228 of thedelivery tube154 resulting in a flow restriction to the polishingfluid flowing therethrough. As the restricting device260 is nonintrusive, i.e., does not create a seam in the flow path or otherwise contact thepolishing fluid

55、 flowing through the tube, flow attributes, such as backpressure, whichmay be utilized to control the flow through the tube, may be controlled without creatingsurfaceresiding in the pressure vessel fluid244 through the outlet port ultimatelyflowing out the outlet end 128. Theconditions such as a sea

56、m that encourages the attachment and build-up of particles.Moreover, as the restricting device260 is configured to provide avariable restriction, the flow of polishing fluid through the delivery tube 154 to thepolishing material128 may be controlledthrough a full range of flow conditions as desired.

57、 For example, the restricting device260 may completely close the interior sectionalarea 228 of the delivery tube154 resulting in zero polishing fluidflow. The restricting device260 may also partially close thedelivery tube 154 to a predefined percentage of the open sectional area 228, or therestrict

58、ing device260 may leave the sectional area228 of the delivery tube154 substantially open in a full flowcondition. One benefit of completely opening the delivery tube154 toa full flow condition is that the increased flow rate through the delivery tube 154 sweepsany particles that may have attached to

59、 the tube walls or other components disposed inthe polishing fluid flow path out of the delivery tube154 during a purge cyclebetweenpolishing, thereby further reducing incidence of agglomerated particles reaching thesubstrate during processing.In one embodiment, the restricting device260 is a pinch

60、valve 262having a slot 264 for receiving the delivery tube154. The pinchvalve 262 includes an actuation bar266 coupled to an actuator268that selectively biases the bar266 against the exterior of thedelivery tube 154 to control the amount that the inner sectional area 228 of the deliverytube154 is op