Patent Description:
The present invention relates to semiconductor fabrication equipment and processing, and in particular, relates to a system and method for removing residues from processing equipment used in a wet treatment process, including solvent immersion and film lift-off stations.

Semiconductor fabrication typically involves deposition of a mask or pattern which determines the components and the electrical connections on a substrate. One common masking technique involves depositing photoresist across a substrate surface and then selectively exposing a pattern on the photoresist. During wet treatment, the pattern is etched onto the substrate material by removal of the exposed sections (or alternatively by sections that were not exposed, depending on the type of photoresist). By chemical development both exposed photoresist and material underlying the exposed photoresist can then be chemically removed by immersion in a solvent, resulting in a patterned structure.

To accommodate fabrication on substrates that are harder to remove by conventional solvent immersion, such as Gallium Arsenide (GaAs), photoresist can be deposited first, underneath subsequently deposited material that is harder to dissolve. When solvent is applied, the photoresist dissolves and layers overlying the photoresist can be removed, or lifted-off, as well. During both the immersion phase and subsequent lift-off phase, a considerable amount of debris and residue can accumulate. Additionally, during immersion incompletely dissolved materials build-up in the solvent bath and can also remain on the meniscus on the wafer surface.

After immersion, the wafer is typically transferred to a spin chamber in which a high-pressure spray is applied to remove excess material and residual photoresist from the wafer. The residual debris tends to accumulate rapidly on walls of the spin chamber or in filters positioned in the fluid drain path, necessitating frequent cleaning of the spin chamber (e.g., several times per day). The time that the chambers spend offline reduces wafer throughput and the overall efficiency of the fabrication process. Furthermore, the high-pressure spray can damage the wafer surface as any adhering or trapped debris is dragged along by surface by the force of the spray.

It would therefore be advantageous to adapt the semiconductor fabrication process to meet these challenges caused by the accumulation of residual resist and other dislodged material.

Anyway, it is worth noting also that <CIT>, that relates to a wet etch system with overflow particle removing feature, discloses a wet etch system including a process tank having an inner etch bath chamber and an outer overflow chamber surrounding the etch bath chamber. A frame which is removably mounted on the process tank defines a diversion channel between the upper ends of the etch bath chamber and overflow chamber. The etch bath chamber receives a wafer-containing cassette, which displaces etchant from the etch bath chamber, through the diversion channel and into the overflow chamber, where the etchant is drained from the process tank. Particulate impurities leave the etch bath chamber, enter the overflow chamber and drain from the process tank with the overflow etchant. Fresh etchant is poured into the etch bath chamber prior to a subsequent etch cycle. A water spray loop may be provided in the overflow chamber for removing etch particles from the interior wall surfaces of the overflow chamber. Additionally, <CIT>, that relates to a method and apparatus for recovery of semiconductor wafers from a chemical tank, discloses a method for stopping chemical processing of a semiconductor wafer in an emergency included the steps of: <NUM>) placing a chemical having a water concentration of about <NUM>% or less in a tank; <NUM>) processing a semiconductor wafer with the chemical in the process tank; <NUM>) detecting a malfunction in the processing; <NUM>) quick draining the chemical from the process tank; and <NUM>) rinsing the wafer in the process tank with a rinsing material to stop chemical action. Optionally, the method may include recycling the drained chemical from a storage tank to the process tank for use in a subsequent process step. Also, a chemical processing system includes: <NUM>) a process tank adapted to processing semiconductor wafers in a chemical having a water concentration of about <NUM>% or less; <NUM>) a control system adapted to detecting a malfunction in processing; <NUM>) a drain valve adapted to quick draining the chemical in the process tank; <NUM>) a storage tank adapted to storing the quick drained chemical; <NUM>) a spray bar adapted to applying a rinsing material to the wafers in the process tank; and <NUM>) a recycling mechanism adapted to returning the quick drained chemical to the process tank.

<CIT> discloses a substrate liquid treatment apparatus that includes: a tank that stores a processing liquid; a circulation line connected to the tank, through which circulation line a circulation flow of the processing liquid that leaves the tank and then returns back to the tank; a processing unit that processes a substrate by supplying the processing liquid, distributed from the circulation line, to the substrate; a return line that returns, to the tank, the processing liquid discharged from the processing unit after being supplied to the substrate; a cleaning nozzle that discharges a cleaning liquid onto an inner wall surface of the tank to clean the inner wall surface by the cleaning liquid; and a cleaning line that supplies the cleaning liquid to the cleaning nozzle.

<CIT> discloses a substrate cleaning apparatus capable of preventing a cleaning vessel from being corroded by a chemical liquid while constituting the cleaning vessel with a low-price material. The substrate cleaning apparatus includes: a cleaning vessel for holding a substrate therein; a substrate holder arranged in the cleaning vessel; a chemical liquid nozzle for supplying a chemical liquid onto the substrate held by the substrate holder; and a plurality of cleaning liquid nozzles for supplying a cleaning liquid onto an inner surface of the cleaning vessel. The inner surface of the cleaning vessel has been subjected to a hydrophilization treatment.

<CIT> discloses an apparatus in accordance with the preamble of claim <NUM> and method for removing challenging polymer films and structures from semiconductor wafers. In particular, the method according to <CIT> involves the use of a double soak and spray sequence with unique parameters and can be varied depending upon the application. The initial immersion step is used to initiate the swelling and dissolution of the polymer. The first spray step may include a high pressure needle to pierce through the top layer allowing more solvent to penetrate in the subsequent soak process. The second immersion can then penetrate further and faster allowing substantial penetration of the polymer by the solvent. The final high pressure spray proceeds to remove all of the polymer coating. The process ends with a final rinse and dry sequence.

<CIT> discloses a process and device for local treatment of substrates based on directing a fine jet of fluid towards a local preselected areas of the substrate and simultaneously applying vacuum suction force that are tuned so that the fluid is allowed to interact with the preselected area of the substrate and that, when interaction is completed, the fluid and possible products of interaction are completely or partially removed from the substrate by action of the vacuum suction force. The fluid is applied to the substrate for the purpose of etching, local dissolution or the formation of an additional layer. Finally, <CIT> discloses a wet etching apparatus and a wet etching method using the same to improve an etching characteristic by improving over etching or an undercut phenomenon. In particular, a vacuum chuck part includes a vacuum chuck which vacuum-absorbs and rotates a wafer. An etching solution spraying part includes a plurality of nozzles spraying an etching solution on a wafer. An air spraying part includes a plurality of nozzles spraying air on the wafer. A cleaning water spraying part includes a plurality of nozzles spraying cleaning water on the wafer. The etching solution is sprayed from a nozzle in the etching solution spraying part and then the air is sprayed from the nozzle of the air spraying part and this process is repetitively performed.

The present invention concerns a semiconductor processing system comprising:.

The present invention concerns also a method of semiconductor processing comprising:.

These and other aspects, features, and advantages can be appreciated from the following description of certain embodiments of the invention and the accompanying drawing figures and claims.

Embodiments of the present invention provide a system and method for removing debris from processing chambers during semiconductor fabrication. In particular, embodiments of the present invention include a self-cleaning immersion station that includes sets of sprayers for both cleaning the internal surfaces of the station chamber, and for spraying wafers as they are transferred out of the immersion station to remove suspended debris adhering to the wafer surface. Embodiments of the present invention also include a self-cleaning lift-off station that includes several types of sprays for cleaning residual debris and solvent from the internal surfaces of the lift-off station chamber, and a vacuum-assisted separator that draws of lift-off material into a suction path as the material is forcibly dislodged from the wafer surface by a high-pressure spray. Collectively, the sprayers and other devices that are added to the immersion and lift-off stations prevent the rapid build-up of debris within the chambers and dramatically reduce the frequency with which the stations need to be brought off-line for cleaning and maintenance.

<FIG> is a top plan view of an integrated wet treatment processing system <NUM> according to an embodiment of the present invention. The integrated system contains load ports for receiving and outputting wafer substrates into and out of the system. Within the system are disposed a number of stations or chambers in which specific processes are performed on wafer substrates. Typically, the wafers are processed by in a particular order, starting, for example, with immersion in a first chamber, followed by metal lift-off in a second chamber, and drying in a third chamber. A robot arm transfers wafers between the stations of the integrated system. More specifically, in <FIG>, an integrated wet processing system <NUM> includes a rectangular enclosure <NUM> that houses several processing stations. Load port <NUM> is adapted to receive cassettes housing one or more semiconductor wafers from other parts of the fabrication facility. Load port <NUM>, situated on the same side of the enclosure, is adapted to receive cassettes including wafers that have been processed and are ready to be transferred out of the system <NUM>. Alternatively, the wafers can be returned to the same cassette.

Integrated system <NUM> includes a number of processing stations arranged within the enclosure <NUM> including an immersion station <NUM> adapted for soaking wafers in a solvent bath to loosen resist layers, metal layers, or any suitable layers; a lift-off station <NUM> adapted to remove residual resist and overlying metallic films from the wafer; and a rinse dry station <NUM> adapted for removing any remaining solvent or other fluids from the wafer surface. A robot arm <NUM> is adapted to securely hold and move individual wafers between the processing stations and the cassettes. In some embodiments, the robot arm includes a paddle <NUM> that is supplied with a Venturi vacuum stream. The vacuum stream enables a wafer to be secured in relation to the paddle without direct contact between the wafer and the paddle surface, preventing damage to the wafer surface. The integrated system <NUM> may also include one or more user control units, e.g., <NUM> that allow process engineers to set various parameters of the system, such as length of immersion time, and spray pressure, among numerous other control parameters.

<FIG> is a perspective view of an immersion station <NUM> according to an embodiment of the present invention. The immersion station <NUM> includes a generally rectangular upper housing <NUM> enclosing an immersion chamber. Below the upper housing <NUM> is a tank <NUM> in which a solvent bath is maintained. The solvent bath stored in the tank <NUM> may include one or more solvents which are used in semiconductor processing. The housing <NUM> includes a door <NUM> through which individual wafers can be transferred into and out of the station. Within the immersion station <NUM>, the wafers are received in cassettes (not shown in <FIG>) that secure the wafers. The internal cassettes can be moved vertically via a cassette Z-drive <NUM> (See, <FIG>) (which may include rods, interconnectors and other components not shown) to move the cassette downward to soak the wafer in tank <NUM>, and to lift the cassettes out of the tank after immersion. Ultrasonic actuators <NUM> may be coupled to the tank <NUM> for vibrating the solvent bath, which helps force solvent though the small openings in the photoresist layers, aiding in the dissolving of photoresist material. The enclosure <NUM> can also include a view port <NUM> for allowing process engineers to monitor the immersion process.

<FIG> is a perspective view of an embodiment of the self-cleaning immersion station <NUM> according to an embodiment of the present invention with the top portion of the enclosure removed. As shown, station <NUM> includes a spray bar <NUM> coupled to the housing via a pivotable coupling <NUM>. The pivotable coupling <NUM> can be positioned near to and/or on the side of the housing near to the door <NUM> (<FIG>) of the immersion station (not explicitly shown in <FIG>) The spray bar includes <NUM> is coupled to a plurality of nozzles, e.g., <NUM>, <NUM> that are adapted to spray cleaning fluid at a selected pressure onto a wafer <NUM> after the wafer has been lifted from the solvent tank <NUM> and is being removed from the immersion station after a soaking process. The nozzles <NUM>, <NUM> are distributed over the majority of the length of the spray bar <NUM> to cover the entire width of the substrate with spray to remove material from the surface of the wafer. The spray bar <NUM> can also be rotated via the pivotable coupling <NUM> fixed or movable at a selective speed provide to vary the distribution of spray. Depending on the residual material and device structure the pressure can range from a light liquid dispense of about <NUM> to <NUM> psi, to a medium pressure of about <NUM> to about <NUM> psi, to a high-pressure spray of about <NUM> to about <NUM> psi. Material or residual small particles (e.g., under <NUM>) suspended in the solvent that adhere to the wafer surface are removed by the spray. In addition to dislodging adhering particles, the spray can contribute solvent for replacing fluid that is often lost from the bath due to transfer or evaporation. A variety of different types of nozzles can be used in the spray bar, including, but not limited to fan, cone, and fan and needle nozzles. The spray type, pressure, flow rate and temperature are controllable parameters that can be set based on a specific processing recipe.

<FIG> illustrate side, perspective and end views of an embodiment of the spray bar <NUM> according to the present invention. <FIG>, shows a spray bar <NUM> including five nozzles <NUM>, <NUM>, <NUM>, <NUM>, <NUM> arranged linearly along the length of the spray bar. In the embodiment depicted, nozzles <NUM>, <NUM>, <NUM>, <NUM>, <NUM> are fan nozzles that direct a spray in a diverging, fan-like manner. As noted above, in other embodiments, other combinations of nozzle types can be used. As shown more clearly in <FIG>, the nozzles <NUM>-<NUM> can pivot within an angular range (α) with respect to a vertical axis. The pivoting aids the dislodging of material as a component of the force of the spray is directed horizontally, providing a shearing action to remove residual debris. The spray bar has <NUM> an internal fluid conduit and is coupled to an inlet <NUM> through which pressurized solvent is supplied through the conduit to the nozzles <NUM>-<NUM>. In other embodiments, the spray bar <NUM> can include more than one inlet for delivering different fluids (e.g., solvent, water or otherwise). The height of the spray bar <NUM> can be adjusted using an adjustable fastener such as a locking nut <NUM>.

<FIG> is a top plan view and <FIG> is a side view depicting a wafer <NUM> in the process being removed from the immersion station <NUM> after having been released from the holding cassette by a handler (not shown). Paddle <NUM> is shown supporting the wafer from underneath as the wafer is transferred. The extraction of the wafer occurs directly under the spray bar so that the plurality of nozzles <NUM>-<NUM> can direct maximal spray onto the wafer surface for dislodging adhered solids and to rinse contaminated, debris-filled solvent from the wafer.

<FIG>, <FIG> and <FIG> illustrate an embodiment of an immersion tank having a tank rinse assembly for self-cleaning according to the present invention. <FIG> is a perspective top view of an immersion station with the upper housing removed and shows a cleaning fluid delivery tube <NUM> that extends circumferentially around the inner perimeter of the tank <NUM>. A plurality of nozzles e.g., <NUM>, <NUM> are attached to, and receive fluid from, the delivery tube <NUM>. The delivery tube <NUM> is coupled to a cleaning fluid supply source (not shown). Nozzles <NUM>, <NUM> which may be, but are not limited to, fan nozzles as shown, direct a pressurized cleaning spray onto the inner walls of the tank <NUM> and also toward the solvent bath held within the tank. With respect to debris that adheres to the tank, the sprayed cleaning fluid dislodges the particles from the wall and/or into the solvent bath. Alternatively, the nozzles can be arranged to direct the particles along the floor and into the drain. In some cases, for example when a small number of nozzles are employed, it may be preferable to use fan nozzles which emit a wide-angle to cover the inner surfaces of the tank with cleaning fluid.

Referring to the cut-away side view of <FIG>, the spray from nozzles <NUM>, <NUM> is directed toward the solvent bath and agitates the chemicals and suspended debris within the bath. The agitation helps break larger debris particles into smaller particles which are able to pass through filters positioned in the drain path <NUM> and exit from the immersion station. The bottom surface of the tank <NUM> can be sloped to facilitate movement of particles coming out of suspension toward drain path <NUM>. The agitation of the solvent bath can also aided by the one or more ultrasonic actuators <NUM> which induce ultrasonic vibrations via one or more walls of the tank, as shown in <FIG>.

<FIG> is a perspective view of the self-cleaning assembly <NUM> shown by itself. A cleaning fluid inlet <NUM> feeds fluid to the tube <NUM>, which runs circumferentially in a form that follows the inner contour of the tank, which in the depicted case is octagonal. In contrast to the cut-away views shown in <FIG> and <FIG>, <FIG> shows the entire track of the tube with four equally-spaced nozzles <NUM>, <NUM>, <NUM>, <NUM> positioned to direct wide-angle sprays onto the inner surfaces of the tank and the surface of the solvent bath. It should be appreciated that the tube can be configured differently, for example, in a circular shape.

<FIG> illustrates a cut-away top view of an embodiment of the immersion station <NUM> that includes through-beam sensors for determining the position of wafers held within the immersion tank, and for determining whether a wafer has been moved toward the door of the immersion station for transfer. As shown, wafers of a variety of diameters (diameters A, B and C) are shown positioned in an immersion tank <NUM> and confined within a secure by a wafer cassette <NUM>. The wafer cassette <NUM> contacts and supports the edges of the wafer such that the robot arm can transfer wafers into and out of the immersion station. A first sensor <NUM>, which may comprise a laser beam emitter (e.g., infrared or visible) positioned on one side of tank and a laser detector positioned on the opposite side, is positioned to intersect the wafers and provides a signal for determining the wafer presence and position according to the timing or position at which the laser beam is reflected or blocked. Sensor <NUM> is blocked by the wafer as the cassette is indexed allowing the cassette to be mapped. A second sensor <NUM> is positioned near to but further from the center of the tank towards the door <NUM> of the immersion station. The second sensor <NUM> may also comprise a laser beam emitter and detector positioned on opposite sides of the tank. The second sensor is positioned to detect a wafer that has been shifted toward the door by the handler or otherwise. When the laser beam of the second sensor <NUM> is blocked by a wafer, it is determined that the wafer is moved or slid out such that an error is detected before door <NUM> is closed.

The immersion process causes photoresist layers to swell, and serves as a preparation for a material lift-off process which takes place in the lift-off station, to which wafers are transferred by the robot arm after immersion. In the lift-off station, metal or other materials deposited over a resist layer are "lifted-off" and removed from the wafer. <FIG> shows an embodiment of a self-cleaning lift-off station <NUM> according to an embodiment of the present invention. The station <NUM> comprises a rectangular chamber <NUM> having a number of different spray devices for lifting-off metal and/or other material from photoresist layers from wafer surfaces and for thoroughly cleaning the inner surfaces of the chamber. At the front of the chamber <NUM> is a door <NUM> through which wafers are transferred into an out of the chamber. An overhead shower sprayer <NUM> is positioned toward the top of chamber, for example, by a cantilevered coupling as shown, and includes a plurality of spray nozzles <NUM> (e.g., <NUM>, <NUM>, <NUM>, etc.) positioned around the perimeter of a fixture, which may be circular in shape as shown, or have other shapes. The nozzles <NUM> can also be adjustable in that they can pivot to allow the spray direction to be slightly altered. An exemplary embodiment of an overhead shower sprayer <NUM> is shown in <FIG>. Additional pivotable nozzle manifolds <NUM>, <NUM>, <NUM> are positioned on three inner walls of the chamber. An exemplary embodiment of one of the nozzle manifolds, e.g., <NUM> is shown in <FIG>. The manifold <NUM> has a fluid inlet <NUM> arranged on an upwardly tilted front surface, a plurality of nozzles, e.g., <NUM>, <NUM> arranged on a bottom surface front and one or more nozzles arranged on side <NUM>, and back surfaces <NUM>. The nozzle manifolds, having a large number of nozzles arranged on different surfaces and at various angles, are configured to apply a rinse spray over a wide area of the chamber <NUM> and cover as much inner surface area as possible. The nozzles <NUM>, <NUM> can be capped in they are not in-use. The manifolds <NUM>, <NUM>, <NUM> can have the same structure and as shown, can be arranged along one side of the rectangular chamber <NUM>.

Alternatively, one of the manifolds <NUM>, <NUM>, <NUM> can also be used as part of a spray mechanism for spraying a splash shield <NUM> that is part of self-cleaning lift-off station <NUM>. As is known, the splash shield <NUM> is a structure that surrounds a substrate (e.g., wafer chuck) on which the wafer rests. The splash shield <NUM> is annular shaped as shown and many times, can be raised or lowered. More specifically, a manifold <NUM> can be provided that has a similar or the same structure as the manifolds <NUM>, <NUM>, <NUM> and therefore, like elements are numbered alike. The main difference is that the manifold <NUM> includes an elongated spray element <NUM> that has a conduit form and has a first end that is sealingly coupled to the nozzle <NUM> and the opposite second end that is sealingly coupled to the nozzle <NUM>. The elongated spray element <NUM> has a bent structure so as to protrude inwardly toward the center of the rectangular chamber <NUM> and more specifically, the elongated spray element <NUM> has an arcuate section <NUM> that is positioned above an arcuate segment of the splash shield <NUM>. Along an underside of the elongated spray element <NUM>, there is a plurality of holes (spray holes) through which the liquid spray is discharged in a downward direction toward the splash shield <NUM>. The elongated spray element <NUM> can thus be in the form of a rinse tube for cleaning the top of the splash shield <NUM>. In <FIG>, the downward spray pattern is shown by the series of parallel lines extending from the underside of the elongated spray element <NUM> to the splash shield <NUM> for cleaning thereof. In combination with the other spray systems described herein, including the spray system shown in <FIG> and <FIG>, optimal spray coverage within the rectangular chamber <NUM> is achieved.

In addition to the shower spray and side nozzle manifolds, the lift-off station preferably includes a swivel sprayer <NUM> coupled to an arm <NUM> that pivots in the horizontal plane (in the other words, the arm <NUM> can rotate about a pivot axis so as to position the arm <NUM> in a desired location which can be a location that is directed inward towards a center of the equipment housing as described with reference to <FIG>. <FIG> is a perspective view of an exemplary embodiment of swivel sprayer <NUM> and shows a rotating spray head <NUM> joined via collar <NUM> to one or more spray nozzles <NUM> positioned at the end of the pivotable arm <NUM>. Rotating spray head <NUM> can be implemented using a commonly-available landscape sprayer that provides a full <NUM>° spray. In other words, the spray coverage of the head <NUM> is generally a circle of a given diameter which depends on the construction of the nozzle of the head <NUM>. The combination of sprayers is designed to be able to direct sprays of cleaning for to all of the wall surfaces and components within the chamber <NUM>. In alternative aspects, more or less sprayers can be provided in any suitable combination to remove material deposited on surfaces within the chamber. It will be appreciated that the rotating spray head <NUM> is positioned so as to spray upward, while the one or more spray nozzles <NUM> spray downward.

The swivel sprayer <NUM> of <FIG> can be thought of as being a single swivel sprayer since it includes a single rotating spray head <NUM>. In contrast, <FIG> and <FIG> illustrate a dual swivel sprayer that includes a pair of rotating spray heads and does not includes the one or more spray nozzles <NUM> shown in <FIG>. More specifically, a swivel sprayer <NUM> is shown in <FIG> and <FIG> that is similar to the swivel sprayer <NUM> but includes the aforementioned differences and more particularly, the swivel sprayer <NUM> pivots in the horizontal plane (so as to have a sweeping action). The swivel sprayer <NUM> includes a first rotating spray head <NUM> and a second rotating spray head <NUM>. The first rotating spray head <NUM> and the second rotating spray head <NUM> can be similar to the rotating spray head <NUM> and thus, each is configured to spray liquid in a <NUM> degree spray pattern. The first and second rotating spray heads <NUM>, <NUM> can be the same type of head in that they each have the same <NUM> degree spray pattern (i.e., they spray a circle having a prescribed diameter). The first rotating spray head <NUM> has a first fluid conduit formed in a first arm <NUM> for delivering fluid to the head <NUM> and the second rotating spray head <NUM> has a second fluid conduit formed in a second arm <NUM> for delivering fluid to the head <NUM>. The two conduits are maintained separately. As shown in <FIG>, the first rotating spray head <NUM> can be located a first distance (first radius) from a vertical post <NUM> from which the arms <NUM>, <NUM> extend and the second rotating spray head <NUM> is located a second distance from the vertical post <NUM>, with the first distance being greater than the second distance. The arms <NUM>, <NUM> and heads <NUM>, <NUM> rotate about the vertical post <NUM>. Both heads <NUM>, <NUM> point down to project the sprayed liquid downward. <FIG> shows the swivel sprayer <NUM> in an in-use position in which the arms <NUM>, <NUM> are positioned inwardly and centrally within the housing (e.g., at a location over the wafer chuck). The spray patterns of the heads <NUM>, <NUM> are selected such that the two circular spray patterns, labeled C1 and C2, at least partially overlap as shown and when combined, the two circular shaped spray coverage covers a substantial inside area of the housing (station), thereby ensuring that the equipment and associated surfaces are cleaned. As will also be appreciated in view of <FIG>, the arms <NUM>, <NUM> are laterally spaced apart from one another and can be straight in shape or as shown, the distal end portion of the arm <NUM> can be curved (bent). It will be understood that the spray coverage shown in <FIG> is merely exemplary and the sizes and location of the circles can vary depending on the type of spray heads and other parameters, such as tank size, etc. As mentioned, when the spray heads <NUM>, <NUM> have the same <NUM> spray coverage, the circles C1 and C2 depicting said spray coverage should have the same diameter. Any portion of the housing that is not within the spray coverage of C1, C2 can be addressed using another spray device, such as the ones described herein. In this way, with two or more sprayers, complete spray coverage within the housing is achieved.

Embodiments of the self-cleaning lift-off station according to present invention can also include a useful feature for entirely removing debris that might otherwise clog filters or adhere to wafer and chamber surfaces. A vacuum-assisted separator sprayer <NUM> is positioned with spray end positioned toward the front of the chamber near door <NUM>. <FIG> is a bottom perspective view that shows the vacuum-assisted separator <NUM> sprayer in greater detail. As shown, a main arm <NUM> is attached to an arm drive (not shown). The main arm <NUM> makes an elbow turn or coupling to a distal arm <NUM> that holds a dispense head <NUM>. A skirt <NUM> encircles the elbow joint where the main arm <NUM> and distal arm <NUM> join in order to prevent fluids from entering the arm drive. The dispense head includes first and second nozzles <NUM>, <NUM>. In some implementations, first nozzle <NUM> is adapted to generate a fan spray, and nozzle <NUM> is adapted to generate a needle spray, or vice versa. In other embodiments, nozzles <NUM>, <NUM> can be adapted to generate the same type of spray or sprays other than a fan and needle spray. Preferably solvent is supplied to nozzles <NUM>, <NUM> at high pressure to provide enough force to dislodge the metal or other material film and underlying resist from wafer substrates during a lift-off process.

In the embodiment depicted, a collar <NUM> is coupled to the distal arm <NUM> as well as to a suction conduit <NUM>. A suction head <NUM> coupled to the suction conduit <NUM> is positioned adjacent to the dispense head. In the depicted embodiment, the suction head <NUM> is adapted to generate a vacuum suction force by a Venturi body <NUM> coupled to a nitrogen supply line via nitrogen inlet <NUM>. Within Venturi body <NUM>, nitrogen gas is forced into a narrow passageway from a larger passageway, which as is known in the art, generates a high-speed flow and a pressure differential in a direction perpendicular to the gas flow. The suction head <NUM> includes an inlet <NUM> that is positioned to draw in, via the suction force generated by the Venturi body <NUM>, material dislodged by the high-pressure sprays generated by the nozzles <NUM>, <NUM> at the dispense head <NUM>. Lift-off materials, some solvent from the wafer surface and some amount of air that is entrapped by the suction force enters the inlet and flows through the suction conduit to a drain (not shown in <FIG>). The rapid removal of the debris into the suction conduit not only prevents the accumulation of the debris within the station chamber <NUM>, but also prevents the debris from being dragged along the surface of the wafer.

<FIG> is an end view of the vacuum-assisted separator which illustrates a jet of high-pressure solvent <NUM> emitted from a nozzle <NUM> impacting a wafer <NUM>. As shown, fluid and lift-off material is captured by the suction force and enters the inlet <NUM> of suction head <NUM>. <FIG> is a cross-sectional view of the vacuum-assisted portion of separator <NUM>. This view shows nitrogen inlet <NUM> of the Venturi body and the narrow opening <NUM> through which the nitrogen is forced to generate the high-speed flow and pressure differential. The suction flow <NUM> is shown by arrows within the suction conduit <NUM>. Air, nitrogen, lift-off material and solvent exits the suction conduit toward a drain.

<FIG> is a perspective view of an alternative embodiment of a vacuum-assisted separator <NUM> according to the present invention. The separator includes a coiled supply line that provides pressurized solvent to a dispense head <NUM> including a fan nozzle <NUM>. The end of the nozzle <NUM> is coupled to a first side of spacer <NUM>, and the second side of the spacer <NUM> is coupled to a suction head <NUM>. According to this arrangement, the nozzle <NUM> is in line with and directs spray through the suction head <NUM>. Suction head <NUM> has a main opening at the bottom through which spray can be directed onto a wafer surface, and includes a side opening into a suction conduit <NUM> that is coupled to a vacuum source. In this embodiment, a Venturi body is not directly coupled to the suction head <NUM>, rather, the suction conduit <NUM> is coupled to a downstream blower or other conventional vacuum-generating device <NUM>. In operation, when the high-pressure spray of nozzle <NUM> impacts the wafer, lift off material is forcibly ejected upwardly from the surface into the suction head <NUM> and becomes entrained by the suction emanating from the suction conduit at side exit of the suction head. The material is drawn off through the suction conduit to a drain (not shown).

<FIG> is a magnified schematic illustration of how the vacuum-assisted separator aids in drawing debris from the wafer surface into a suction path, which aids in preventing build-up of residual material in the lift-off station. As shown, a nozzle <NUM> is enveloped within a suction head which is cut at an angle so that both the suction head main opening <NUM>, and the adjacent opening <NUM> to the suction conduit through which suction is applied, are positioned near to the surface of a wafer <NUM>. When the nozzle <NUM> directs a fan of high-pressure solvent spray toward the surface of a wafer <NUM>, the spray forcibly breaks off and atomizes the lift-off material. The overwhelming majority particles of debris <NUM> that is dislodged from the wafer surface enters and becomes entrained in the suction flow within the suction head, due to the close positioning of the suction head and applied vacuum to the wafer surface.

<FIG> is a schematic illustration of debris removal using a vacuum-assisted separator that employs a Venturi body <NUM>. Debris that is removed from the wafer <NUM> positioned within a chamber is drawn into the main opening of suction head <NUM> by the suction generated by nitrogen gas flow in the Venturi body. The suction conduit delivers the debris to a drain <NUM> that flows into a tank <NUM> with a filter <NUM>. <FIG> is a schematic illustration of debris removal using a vacuum-assisted separator that employs a blower <NUM> to generate suction. In this embodiment, suction is generated from a blower that is fluidly coupled to the suction head via a tank <NUM>. Debris drawn through the suction head is similarly drawn through a conduit into a filter <NUM> positioned in the tank. These embodiments illustrate how rather than being ejected into the spaces and surfaces within the lift-off chamber, embodiments of the vacuum-assisted separator redirect lift-off debris into a drain and filter. The amount of debris that accumulates on the internal surfaces of the chamber is thereby reduced. Furthermore, any debris that is not captured by the vacuum-assisted separator can be washed from the internal surfaces by the numerous cleaning sprays employed in the lift-off station according to the embodiments of the present invention.

<FIG> is a front view of an overhead track sprayer device <NUM> that may be used in embodiments of a lift-off station according to the present invention. The device includes a circular or elliptical track system <NUM> that may be attached to roof or dome of the station chamber <NUM>. A nozzle <NUM> is positioned on the track and receives fluid from tubing <NUM> that may run through a seal <NUM> attached to the chamber and to a cleaning fluid supply source. The tubing swivels the nozzle <NUM>° around the track by the force of the high-pressure fluid within the tubing. The swiveling allows the nozzle to cover the inner surfaces of the chamber with cleaning fluid to remove debris and leftover solvents. In some embodiments, the tubing <NUM> can run from a valve to a fast-acting disconnect. A sealed swivel fitting at the center of the track <NUM> can be used to provide full rotation of the tubing <NUM> without twisting or kinking. The tubing <NUM> can be attached to the track <NUM> using rollers to reduce friction and provide consistent rotation.

It is to be understood that any structural and functional details disclosed herein are not to be interpreted as limiting the system and methods, but rather are provided as a representative embodiment and/or arrangement for teaching one skilled in the art one or more ways to implement the methods.

It is to be further understood that like numerals in the drawings represent like elements through the several figures, and that not all components and/or steps described and illustrated with reference to the figures are required for all embodiments or arrangements.

Terms of orientation are used herein merely for purposes of convention and referencing and are not to be construed as limiting. However, it is recognized these terms could be used with reference to a viewer. Accordingly, no limitations are implied or to be inferred.

Claim 1:
A semiconductor processing system comprising:
an immersion station (<NUM>) adapted for immersion of a wafer (<NUM>) in solvent for removal of material, wherein an opening is formed in the immersion station (<NUM>) through which the wafer (<NUM>) can be removed from inside the immersion station (<NUM>); and
a lift-off station (<NUM>) adapted to completely remove material from the surface of the wafer (<NUM>) and including a separator (<NUM>) adapted to spray solvent at a high pressure spray onto the wafer surface;
characterized in that:
- the immersion station (<NUM>) is self-cleaning and includes a self-cleaning assembly (<NUM>) adapted to spray cleaning fluid on internal surfaces of the immersion station (<NUM>);
- the immersion station (<NUM>) further includes a first sprayer having a plurality of nozzles (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) positioned to spray the wafer (<NUM>) as it is transferred out of the immersion station (<NUM>), wherein the first sprayer comprises an elongated spray bar (<NUM>) that is disposed proximate the opening formed in the immersion station (<NUM>), includes a plurality of nozzles (<NUM>, <NUM>, <NUM>, <NUM>, <NUM>) positioned longitudinally along the spray bar (<NUM>) and is configured to spray downward onto the wafer (<NUM>) for removing suspended particles and solvent from a surface of the wafer (<NUM>) as the wafer (<NUM>) is removed from the opening formed in the immersion station (<NUM>);
- the lift-off station (<NUM>) is self-cleaning and further includes at least one cleaning sprayer adapted to clean internal surfaces of the lift-off station (<NUM>); and
- the separator (<NUM>) is vacuum-assisted and is adapted to spray the solvent while applying suction in the vicinity of the sprayed wafer surface to capture material dislodged by the spray.