USp_6516815 (1063235), страница 2
Текст из файла (страница 2)
Aplurality of grooves 24are formed in the loWer surface of the substrate holder 14.A vacuum pump (not shoWn) is coupled to the substrateholder 14 and communicates With the grooves 24 to createa vacuum condition capable of securing the substrate 22 toformation of these interconnect features is very important tothe success of ULSI and to the continued effort to increasethe substrate holder 14 during processing.
The contact ringcircuit density and quality on individual substrates and die.As circuit densities increase, the Widths of vias, contacts20 comprises a plurality of metallic or semimetallic contactpins 26 distributed about the peripheral portion of thesubstrate 22 to de?ne a central substrate plating surface. Theand other features, as Well as the dielectric materialsbetWeen them, decrease to less than 250 nanometers,Whereas the thickness of the dielectric layers remains substantially constant, With the result that the aspect ratios forplurality of contact pins 26 eXtend radially inWardly over a25conductive seed layer of the substrate 22 at the tips of thecontact pins 26. A poWer supply (not shoWn) is attached tothe pins 26 thereby providing an electrical bias to thethe features, i.e., their height divided by Width, increases.Many traditional deposition processes, such as physicalsubstrate 22.
The substrate 22 is positioned above thevapor deposition (PVD) and chemical vapor deposition(CVD), have dif?culty ?lling structures Where the aspectcylindrical electrolyte container 12 and electrolyte ?oWimpinges perpendicularly on the substrate plating surfaceduring operation of the cell 10.One particular problem encountered in current electroplating processes is that the edge of the seed layer receivesratio eXceed 4:1, and particularly Where it eXceeds10:1.Therefore, there is a great amount of ongoing effortbeing directed at the formation of void-free, nanometersiZed features having high aspect ratios Wherein the ratio offeature height to feature Width can be 4:1 or higher.Additionally, as the feature Widths decrease, the devicenarroW perimeter portion of the substrate 22 and contact a35 an eXcess amount of deposition, typically referred to as anedge bead, during the electroplating process.
FIG. 2 is acurrent remains constant or increases, Which results in ancross sectional vieW of an edge of an Wafer 30 shoWingincreased current density in the feature.Elemental aluminumand its alloys have been thetraditional metals used to form lines and plugs in semiconeXcess deposition 36 at the edge 32 of the seed layer 34. AsshoWn in FIG. 2, the Wafer 30 has a seed layer 32 depositedthereon and an electroplated layer 38 electrochemicallydeposited over the seed layer 34. It has been observed thatthe edge 32 of the seed layer 34 receives a higher currentductor processing because of aluminum’s perceived loWelectrical resistivity, its superior adhesion to silicon dioxide(SiOZ), its ease of patterning, and the ability to obtain it ina highly pure form. HoWever, aluminum has a higherelectrical resistivity than other more conductive metals suchas copper, and aluminum also can suffer from electromigration leading to the formation of voids in the conductor.density than the remainder of the seed layer 34, resulting in45is also higher than the remainder of the seed layer, causingthe deposition at the edge of the seed layer to pull up andaWay from the edge of the Wafer 30.
The eXcess deposition36 is typically removed by a CMP process. HoWever, duringCopper and its alloys have loWer resistivities than aluminum and signi?cantly higher electromigration resistance ascompared to aluminum. These characteristics are importantfor supporting the higher current densities experienced atthe CMP process, the eXcess deposition 36 at the edge of theWafer typically tears off from the edge of the seed layer andmay damage the adjacent portion of the Wafer. The brokenhigh levels of integration and increase device speed. Copperalso has good thermal conductivity and is available in ahighly pure state.
Therefore, copper is becoming a choicemetal for ?lling sub-quarter micron, high aspect ratio interoff metal may also damage the devices formed on the Wafer.Thus, the number of properly formed devices is decreased55connect features on semiconductor substrates.iting copper into very high aspect ratio features, such as a4:1, having 0.35 p (or less) Wide vias are limited. As a resultof these process limitations, plating, Which had previouslyMetal electroplating is generally knoWn and can beachieved by a variety of techniques. A typical methodand the cost per device formed is increased.Therefore, there is a need for an apparatus for removingthe eXcess deposition at the edge of the Wafer. Preferably, theapparatus removes the eXcess deposition at the edge of theWafer Without damaging the devices formed on the Wafersurface.
It Would be further desirable for the apparatus to beadaptable for performing a Wafer cleaning process after theDespite the desirability of using copper for semiconductordevice fabrication, choices of fabrication methods for deposbeen limited to the fabrication of lines on circuit boards, isjust noW being used to ?ll vias and contacts on semiconductor devices.a higher rate of deposition at the edge 32 of the seed layer34. The mechanical stress at the edge 32 of the seed layer 34eXcess deposition has been removed from the Wafer, such asa spin-rinse-dry process.65SUMMARY OF THE INVENTIONThe invention generally provides an apparatus and amethod for removing deposition at the edge of a Wafer.
TheUS 6,516,815 B134apparatus according to the invention removes deposition atthe edge of a Wafer Without damaging the devices formed onthe Wafer surface.One aspect of the invention provides an apparatus foretching a substrate, comprising: a container; a substratesupport disposed in the container; a rotation actuatorsubstrate disposed in a processing position for removingexcess deposition from the edge of the substrate. The EBRmodule 100 can be a stand-alone unit or disposed as acomponent of an electrochemical deposition system or otherdeposition systems. The EBR module 100 comprises acontainer 102, a Wafer holder assembly 104 and a ?uid/chemical delivery assembly 106.
The container 102 preferattached to the substrate support; and a ?uid delivery assembly disposed in the container to deliver an etchant to aably includes a cylindrical sideWall 108, a container bottom110 having a central opening 112, and an upturned inner Wallperipheral portion of a substrate disposed on the substratesupport. Preferably, the substrate support comprises avacuum chuck and the ?uid delivery assembly comprises10one or more noZZles.Another aspect of the invention provide a method forThe Wafer holder assembly 104 is disposed above theetching a substrate, comprising: rotating a substrate positioned on a rotatable substrate support; and delivering anetchant to a peripheral portion of the substrate. Preferably,central opening 112 and includes a lift assembly 118 and a15the substrate is rotated at betWeen about 100 rpm and about1000 rpm, and the etchant is delivered in a direction that isrotation assembly 120 that extends through the centralopening 112.
The lift assembly 118 preferably comprises abelloWs-type lift or a lead-screW stepper motor type liftassembly, Which are Well knoWn in the art and commerciallysubstantially tangent to the peripheral portion of the substrate at an incident angle betWeen about 0 degrees and about45 degrees from a surface of substrate.Another aspect of the invention provides an apparatus forremoving the excess deposition at the edge of the Wafer that114 extending upWardly from the peripheral edge of thecentral opening 112.
A ?uid outlet 116 is connected to thecontainer bottom 110 to facilitate draining of the used ?uidsand chemicals from the EBR module 100.20is adaptable for performing a Wafer cleaning process afterthe excess deposition has been removed from the Wafer, suchas a spin-rinse-dry process. The apparatus comprises a 25available.
The lift assembly 118 facilitates transfer andpositioning of the Wafer 122 on the Wafer holder assembly104 betWeen various vertical positions. The rotation assembly 120 preferably comprises a rotary motor that is attachedbeloW the lift assembly. The rotation assembly 120 rotatesthe Wafer 122 during the edge bead removal process.The Wafer holder assembly 104 preferably comprises acontainer; a substrate support disposed in the container; avacuum chuck 124 that secures a Wafer 122 from the Waferrotation actuator attached to the substrate support; and abackside and does not obstruct the Wafer edge 126.Preferably, an annular seal 128, such as a compressibleO-ring, is disposed at a peripheral portion of the vacuum?uid delivery assembly disposed in the container to selectively deliver an etchant to a peripheral portion of a substratedisposed on the substrate support and a rinsing ?uid, such asdeioniZed Water, to the surface of the substrate.30and chemicals used during the edge bead removal process.The Wafer holder assembly 104 preferably includes a WaferBRIEF DESCRIPTION OF THE DRAWINGSlift 130 that facilitates transfer of a Wafer from a robot bladeof a transfer robot onto the Wafer holder assembly 104.
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