Apparatus and Method for Wafer Pre-Wetting

This application is a divisional application of and claims the priority benefit of U.S. application Ser. No. 18/163,296, filed on Feb. 2, 2023, now allowed, which is a divisional application of and claims the priority benefit of U.S. application Ser. No. 17/147,471, filed on Jan. 13, 2021, now patented. The entirety of each of the above-mentioned patent applications is hereby incorporated by reference herein and made a part of this specification.

In the production of advanced semiconductor integrated circuits (ICs), electroplated copper is currently used because copper has a lower electrical resistivity and a higher current carrying capacity. However, the copper electroplating process may produce conductive features with defects. For example, nano-bubbles trapped in the electroplated copper layer will limit the quality of the conductive features and therefore reduce production yield of the IC product. Accordingly, forming defect-free conductive features is one of the ongoing efforts in order to improve electrical performance of IC devices.

The following disclosure provides many different embodiments, or examples, for implementing different features of the provided subject matter. Specific examples of components and arrangements are described below to simplify the present disclosure. These are, of course, merely examples and are not intended to be limiting. For example, the formation of a first feature over or on a second feature in the description that follows may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features may be formed between the first and second features, such that the first and second features may not be in direct contact. In addition, the present disclosure may repeat reference numerals and/or letters in the various examples. This repetition is for the purpose of simplicity and clarity and does not in itself dictate a relationship between the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,” “above,” “upper” and the like, may be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. The spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. The apparatus may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

are schematic cross-sectional views of various stages of forming a conductive feature of a semiconductor structure according to some embodiments. Referring to, a base layerof a semiconductor structureis provided with an opening OP, and a seed material layermay be formed on the base layerin a conformal manner. In some embodiments, the base layeris a semiconductor wafer (e.g., silicon wafer) or is a part of a semiconductor wafer. The base layermay be or may include a semiconductor substrate, such as a bulk semiconductor or the like, which may be doped or undoped. Under this scenario, the subsequently formed conductive feature (e.g.,in) may act as a through substrate via (TSV) in the semiconductor structure. In some embodiments in which the base layeris a dielectric layer formed over a semiconductor substrate, the conductive feature may be formed as a part of interconnect circuitry in the semiconductor structure.

The opening OP may be formed by acceptable removal techniques (e.g., lithography and etching, drilling, and/or the like). The depth of the opening OP may range from sub-micron to about 100 μm with the aspect ratio (width/depth) ranging from about 1:1 to about 1:20. Although this depth may vary and scale with semiconductor processes. It should be noted that the opening OP which does not penetrate through the base layeris illustrated; however, in some embodiments, the opening OP may penetrate through the base layerto expose element(s) underlying the base layer, if desired. It should be appreciated that the cross-sectional shape of the opening is merely an example, and a dual damascene opening including a via hole connecting a trench may be formed in the base layer according to some embodiments.

With continued reference to, the opening OP may be lined with the seed material layer. The material of the seed material layermay include Cu, Ni, Co, Ru, a combination thereof, etc. For example, the seed material layermay include the same conductive material (e.g., Cu) as that used in the subsequent plating process. In some embodiments, the opening OP is initially lined with a barrier liner (not shown), and then the seed material layeris deposited on the barrier liner. The barrier liner may bond the conductive material to the base layer (e.g., the dielectric layer) or may prevent interaction between the conductive material and the base layer (e.g., silicon substrate). For example, the material of the barrier liner includes Ta, TaN, Ti, TiN, a combination thereof, etc.

Referring to, a pre-wetting processis performed on the semiconductor structure. For example, the seed material layeris treated with the pre-wetting processto increase wetting ability. The wettability of the seed material layer may be critical for the subsequent plating process. If the seed material layer cannot wet the plating fluid, no plated material can be deposited on that area of the seed material layer, thereby forming a defect. The pre-wetting process may involve wetting the semiconductor structurewith fluid. In some cases, jetting the pre-wetting fluid to the semiconductor structurecauses the presence of undesirable bubbles. Those bubbles may be pressed into the openings due to pressure difference during the process. During the subsequent plating process, those bubbles in the openings become blocking spots that inhibit plating at those spots and lead to associated defects. The pre-wetting apparatus and pre-wetting method which may avoid the formation of bubbles will be described later in the other embodiments.

Referring to, a conductive material layeris formed on the seed material layer. The conductive material layermay be a metallic material including a metal or a metal alloy such as copper, silver, gold, tungsten, cobalt, aluminum, or alloys thereof. For example, after the pre-wetting process, electrochemical plating (ECP) is performed to fill the opening OP with the conductive material layer. In some embodiments, the semiconductor structureis immersed in an electrolytic bath (not shown). Since the semiconductor structureis electrically biased with respect to the electrolytic bath, the conductive material electrochemically deposits on the semiconductor structure. Although electroless plating may be used to form the conductive material layer, in accordance with some embodiments.

Referring to, the excess material formed over the major surfaceof the base layermay be removed to form the semiconductor structurehaving a conductive featureembedded in the base layer. In some embodiments, a planarization (e.g., chemical mechanical polishing, etching, grinding, a combination thereof, etc.) is performed to remove the excess material. In some embodiments, after the planarization, the surfaces of the conductive material layerand the seed material layerform a major surfacethat is substantially level with the major surfaceof the base layer. In some embodiments, the barrier liner formed between the base layerand the seed material layeris also removed by the planarization. After the planarization, the remaining portions of the conductive material layerand the seed material layerthat are laterally covered by the base layeris collectively viewed as the conductive feature.

is a flowchart illustrating a method of pre-wetting a semiconductor structure according to some embodiments. It is appreciated that although the processis described below as a series of steps, the ordering of such steps is not to be interpreted in a limiting sense. For example, some steps occur in different orders and/or concurrently with other steps apart from those illustrated and/or described herein. In addition, not all illustrated steps may be required to implement one or more aspects or embodiments of the description herein. Further, one or more of the steps depicted herein may be carried out in one or more separate acts and/or phases.

Referring to, at step, a semiconductor workpiece is placed on a workpiece holder in a process chamber. The semiconductor workpiece may be a pre-wetting target (e.g., the semiconductor structureshown in). The semiconductor workpiece to be wetted may be provided in a wafer form and the semiconductor wafer may include a plurality of fields having integrated circuits defined therein, and each field may have one or more semiconductor dies. The semiconductor workpiece is not intended to be limited to any particular type. In some embodiments, forming the seed material layer, pre-wetting, and the subsequent plating are performed in separate chambers (or apparatuses), and thus the semiconductor workpiece may be transferred from the former chamber to the latter chamber. In some embodiments, the process chamber for pre-wetting semiconductor workpieces is part of a plating system. The workpiece holder may include any suitable element or may be provided in any form for carrying and limiting the semiconductor wafer. The details of the process chamber are described later in accompanying with.

At step, the pressure in the process chamber may be reduced. For example, after placing the semiconductor workpiece, the process chamber is sealed and the pressure within the process chamber is reduced. For example, a vacuum environment is created in the process chamber. In some embodiments, during this step, the air inside the openings of the semiconductor workpiece is evacuated. In some embodiments, a pump (e.g., vacuum pump) is employed to pump down the process chamber from atmospheric pressure to sub-atmospheric pressure (e.g., a low vacuum pressure). The pump coupled to the process chamber may be utilized to control the pressure within the process chamber to a desired pressure, for example, in a range of about 50 Torr to about 100 Torr.

At step, the major surface of the semiconductor workpiece is rinsed with pre-wetting fluid. For example, the pre-wetting fluid is deionized water. Alternatively, the pre-wetting fluid includes deionized water, acid, and/or the like. In some embodiments, the pre-wetting fluid is degassed before contacting the major surface of the semiconductor workpiece. In some embodiments, the sub-atmospheric pressure (e.g., vacuum conditions) is maintained in the process chamber when applying the degassed pre-wetting fluid to the semiconductor workpiece. The semiconductor workpiece held by the workpiece holder may be (or may not be) spun during this step. In some embodiments, the semiconductor workpiece is rotated at a slow rate. For example, the rotational speed is between aboutrpm to about 100 rpm, such as about 50 rpm. The semiconductor workpiece may be wetted by flooding the major surface with the pre-wetting fluid in a gentle manner to avoid formation of bubbles. The details thereof will be described below in accompanying with.

At steps-, after the wetting step, allowing the semiconductor workpiece to stand still for a short time, for example, ranging from about 10 seconds to about 1 minute. In some embodiments, the stepis skipped. Next, the pressure within the process chamber may be increased. For example, the vacuum in the process chamber is released. In some embodiments, the process chamber is vented to atmosphere (e.g., about 760 Torr).

At steps-, the semiconductor workpiece is dried to remove the pre-wetting fluid from the major surface. For example, a spin-drying process is performed, where the semiconductor workpiece is spun at a rate ranging from about 200 rpm to about 400 rpm, for a duration ranging from about 10 seconds to about 30 seconds. After the spin-drying is complete, the semiconductor workpiece may sit still for a short time. Other suitable drying method(s) may be employed. Afterwards, the semiconductor workpiece is moved out of the process chamber for further processing (e.g., plating as shown in).

is a schematic cross-sectional view illustrating a pre-wetting apparatus including a semiconductor workpiece disposed on a workpiece holder andis a schematic cross-sectional view illustrating a pre-wetting apparatus including a semiconductor workpiece rinsed by pre-wetting fluid, in accordance with some embodiments.are schematic plan views illustrating a semiconductor workpiece disposed on a workpiece holder according to some embodiments. The pre-wetting apparatus shown herein may be utilized to perform the processdescribed in. Unless specified otherwise, the components mentioned inare essentially the same as the like components described below.

Referring to, a pre-wetting apparatusis provided, and the semiconductor workpiece W is placed on the workpiece holderwithin the process chamberof the pre-wetting apparatus. The semiconductor workpiece W may be a pre-wetting target (e.g., the semiconductor structureshown in). The major surface WS(e.g., the top surface of the seed material layer) of the semiconductor workpiece W may be hydrophilic and have recessed features to be wetted and plated. The workpiece holdermay be provided in a disk form or may include several arms to support the semiconductor workpiece W. The semiconductor workpiece W is engaged with the workpiece holderusing any suitable holding fixture (e.g., pins, clamps, etc.), where the holding fixture may support and/or affix the semiconductor workpiece W during processing. In some embodiments, the workpiece holderis coupled to a moving mechanism(e.g., motor, controller, shaft, combination of these, and/or the like). The moving mechanismis configured to drive the workpiece holderto perform movements (e.g., translate, tilt, rotate, and/or the like) of the semiconductor workpiece W. In some embodiments, the bottom of the process chamberacts as the overflow reservoir for collecting the overflowed pre-wetting fluid. For example, the bottom of the process chamberis provided with drainage portsD for draining the overflowed pre-wetting fluid.

In some embodiments, a pre-wetting fluid tankis adapted for delivering the pre-wetting fluid to the semiconductor workpiece W through at least one conduit. The pre-wetting fluid tankmay be disposed outside the process chamber. Although other configuration of the pre-wetting fluid tankis possible. In some embodiments, a flow control deviceis disposed upstream of the outlet of the conduit. In some embodiments, the water level in the pre-wetting fluid tankis below the workpiece holder, and the pre-wetting fluid tankis equipped with the flow control device(e.g., a pump) for driving the pre-wetting fluid in the pre-wetting fluid tankto flow to the semiconductor workpiece W. Alternatively, the pre-wetting fluid is delivered through the suction generated by a pressure differential between the pre-wetting fluid tankand the process chamber.

In some embodiments, the conduitsare coupled to the pre-wetting fluid tankand assembled on the workpiece holder. Although two conduitsare shown, the number of the conduits is not intended to be limiting. For example, portions of the conduitsare embedded in the workpiece holderto form channelsinside the workpiece holder. In some embodiments, the channelsare the hollow passageways in the workpiece holder. The flow path of the pre-wetting fluid passing through the channelsmay be below the semiconductor workpiece W and along the sidewalls WSof the semiconductor workpiece W. In some embodiments, the channelsare in fluidic communication with the pre-wetting fluid tank, and the pre-wetting fluid may flow to the semiconductor workpiece W through the outlets of the channelsthat are defined by the inner sidewalland the outer sidewallof the workpiece holder. The inner sidewalland the outer sidewallof the workpiece holdermay be substantially parallel to the sidewall WSof the semiconductor workpiece W. The outer sidewallmay be higher than the inner sidewallrelative to the major surface WS. In some embodiments, the shortest distance Hbetween the top of the outer sidewalland a reference plane where the major surface WSis located on is greater than the shortest distance Hbetween the top of the inner sidewalland a reference plane where the major surface WSis located on. For example, the inner sidewallsand the outer sidewallsof the workpiece holdermay act as overflow weirs, and the pre-wetting fluid delivering through the channelsmay overflow the inner sidewallsprior to overflowing the outer sidewallsdue to the difference of highness.

With continued reference toand also referring to, the outlets of the channelsmay be provided in any suitable fashion. For example, when viewed from above (e.g.,), the outlets of the channelsare distributed around the periphery of the semiconductor workpiece W. The pre-wetting fluid may be discharged from these outlet ports and flow to the major surface WSof the semiconductor workpiece W as indicated by the arrows Al. In this manner, the major surface WSof the semiconductor workpiece W may be wetted from the edge to the center. The outlets may have any top-view shape such as a square shape, a rectangular shape, a circular shape, an elliptical shape, a polygonal shape, etc. It is noted that four outlets shown inis merely an example, the pre-wetting fluid may be discharged through a single outlet or multiple outlets, and the number of the outlet construes no limitation in the disclosure. In some embodiments, when viewed from above (e.g.,), the outlet of the channelsis a trench encircling the periphery of the semiconductor workpiece W. The outlet of the channelsmay be a continuous annular trench or may be discontinuous trenches along the perimeter of the semiconductor workpiece W. Other suitable configuration of the outlet may be possible. The pre-wetting fluid may overflow from the trench to the semiconductor workpiece W from the edge to the center as indicated by the arrows A.

Referring to, the semiconductor workpiece W is rinsed by the pre-wetting fluid DW. The condition shown inmay correspond to the stepdescribed in. In some embodiments, during the wetting step, the semiconductor workpiece W is rotated about an axis AX that passes through its center and is perpendicular to the major surface WS. For example, the semiconductor workpiece W is driven by the moving mechanismto spin in clockwise (or counterclockwise) direction. Alternatively, the semiconductor workpiece W is not spun during the wetting step. The dashed arrows indicate that the spinning may be or may not be performed during the wetting.

In some embodiments, the pre-wetting fluid DW is degassed prior to delivery to the semiconductor workpiece W. For example, a degasser (not shown) is configured to remove (or reduce) dissolved gases from the pre-wetting fluid DW before entering the conduits. In some embodiments, the water level in the pre-wetting fluid tankis below the workpiece holder, and the pre-wetting fluid DW in the pre-wetting fluid tankmay be delivered upwardly by the conduitsas indicated by the arrows A. Then, the pre-wetting fluid DW may flow through the channelsin the workpiece holderas indicated by the arrows A. Next, the pre-wetting fluid DW may overflow the inner sidewallof the workpiece holderto contact the major surface WSof the semiconductor workpiece W as indicated by the arrows A. The flow of the pre-wetting fluid DW may mildly wet the major surface WSof the semiconductor workpiece W without the formation of bubbles. For example, the wetting rate across the major surface WSis regulated by adjusting the fluid pressure of the pre-wetting fluid DW. To avoid fluid jet having a higher fluid pressure being impinged on the major surface, the flow of the pre-wetting fluid DW contacting the major surface WSof the semiconductor workpiece W may be regulated to have a relatively low fluid pressure. It is noted that any suitable flow control device (not shown; e.g., valves, controller, sensors, etc.) may be employed for handling the pressure and flow requirements. For example, the fluid pressure is controlled to be in a range of about 10 pounds per square inch (psi) and about 100 psi.

The pre-wetting fluid DW may continuously flow out through the channelsto wet the semiconductor workpiece W. The excess pre-wetting fluid DW may overflow the outer sidewallof the workpiece holderand flow downwardly to the bottom of the process chamberas indicated by the arrows A. In some embodiments, the pre-wetting fluid DW may fill the recesses features (or openings) on the major surface WSof the semiconductor workpiece W due to the pressure differential (e.g., the pressure in the process chamber is increased at the stepdescribed in). In some embodiments, during the stepdescribed in, the pre-wetting fluid DW is removed from the major surface WSof the semiconductor workpiece W and may be collected at the bottom of the process chamber, and those pre-wetting fluid DW at the bottom of the process chambermay be discharged through the drainage portsD.

is a schematic cross-sectional view illustrating a pre-wetting apparatus including a semiconductor workpiece rinsed by pre-wetting fluid according to some embodiments. The condition shown inmay correspond to the stepdescribed in. The pre-wetting apparatusA shown inis similar to the pre-wetting apparatusshown in, and thus like reference numbers are used to designate like elements.

Referring to, the semiconductor workpiece W is wetted by flowing the pre-wetting fluid DW from the pre-wetting fluid tankto the semiconductor workpiece W. The semiconductor workpiece W may be (or may not be) driven by the moving mechanismto spin during the wetting step. In some embodiments, the pre-wetting fluid tankdisposed outside the process chamberis coupled to the conduit, where the conduitextending into the process chamberis positioned above the semiconductor workpiece W for delivery the pre-wetting fluid DW downwardly to the major surface WSof the semiconductor workpiece W. In some embodiments, the lateral dimension D(e.g., diameter) of the outletis less than about 3 mm, for example, in a range of about 1 mm to about 3 mm. It should be noted that the lateral dimension Dmay be adjusted depending on the predetermined flow rate and process requirements.

In some embodiments, the conduitis movable inside the process chamberto be located at any desired position. The conduitmay be provided as the priming arm or may be part of priming arm which is driven by a controller (not shown) to perform movements (e.g., swinging, lowering down, lifting up, etc.). In some embodiments, the outletof the conduitis positioned above the center of the major surface WSof the semiconductor workpiece W by a vertical distance WH. Alternatively, the outletof the conduitis positioned above the edge or anywhere else of the major surface WSof the semiconductor workpiece W.

In some embodiments, the pre-wetting fluid tankis equipped with the flow control device, and the pre-wetting fluid DW in the pre-wetting fluid tankmay be fed into the conduitby the flow control device. The flow control devicemay include at least one pump (e.g., syringe pump, pressure based pump, etc.), valves, motors, pipelines, etc. Other suitable device which is configured to pressure control and flow rate control may be utilized. By regulating the flow rate and the pressure of the pre-wetting fluid DW delivering to the semiconductor workpiece W, the semiconductor workpiece W may be rinsed in a gentle manner. For example, the fluid pressure is controlled to be in a range of about 5 psi and about 50 psi.

In some embodiments, the pre-wetting fluid DW is initially degassed and delivered by the conduits. For example, there is no air bubble inside the conduitsduring the delivery of the pre-wetting fluid DW using any suitable technique. In some embodiments, the outletof the conduitis above the semiconductor workpiece W and at the position close to the major surface WSof the semiconductor workpiece W, and the pre-wetting fluid DW flows out through the outletto contact the major surface WSof the semiconductor workpiece W, as indicated by the arrows A. For example, the vertical distance WHbetween the outletof the conduitand the major surface WSof the semiconductor workpiece W is in a range of about 1 mm to about 3 mm. The vertical distance WHmay be regulated before, during, and after delivery the pre-wetting fluid DW to the semiconductor workpiece W.

In some embodiments, as the pre-wetting fluid DW continuously flowing to the semiconductor workpiece W, the pre-wetting fluid DW is accumulated on the major surface WSof the semiconductor workpiece W, and the position of the outletis kept to be lower than the height (water level) of the pre-wetting fluid DW relative to the major surface WS. For example, the outletof the conduitis submerged under the pre-wetting fluid DW over the major surface WS. In some embodiments, the vertical distance WHis less than the vertical distance WHthat is between the fluid surface of the pre-wetting fluid DW surrounding the conduitand the major surface WSof the semiconductor workpiece W. In some embodiments, as the continuous delivery of the pre-wetting fluid DW to the semiconductor workpiece W, the pre-wetting fluid DW gradually and slowly spreads in a radial direction to the edges as indicated by the dashed arrows A. It is noted that the flow path of the pre-wetting fluid DW on the semiconductor workpiece W is illustrated in the dashed lines. For example, the flow of pre-wetting fluid DW over the major surface WSof the semiconductor workpiece W is in a “creeping” flow regime, in order to prevent the fluid jet from impinging on the major surface WS. The wetting rate across the major surface WSmay be regulated by adjusting the fluid pressure. The creeping flow regime may be achieved by, for example, optimizing the size of the outletand the length of the conduit, regulating the fluid pressure and velocity through the flow control device, etc. It should be noted that the term “creeping flow” used herein may refer to the flow with lower fluid pressure and velocity (or flow rate).

The spreading flow rate of the pre-wetting fluid DW over the semiconductor workpiece W may be regulated to avoid turbulence and/or the formation of bubbles. For example, the application of the flow control devicefacilitates control of the fluid pressure and flow rate of the pre-wetting fluid DW fed into the conduit. The lateral dimension Dof the outletmay be designed to have the small amount of the pre-wetting fluid DW flowing out through the outlet. In this manner, the pre-wetting fluid DW may gently wet the major surface WSof the semiconductor workpiece W to prevent the fluid jet from hitting the major surface WS. In some embodiments, when wetting the semiconductor workpiece W, keeping the outletsubmerged in the pre-wetting fluid DW may prevent air bubbles from being introduced into the pre-wetting fluid DW over the semiconductor workpiece W. As continuous flooding the major surface WSof the semiconductor workpiece W with the pre-wetting fluid DW, the excess pre-wetting fluid DW over the semiconductor workpiece W may overflow the top surface of the workpiece holderas indicated by the arrow A, and then the overflowed pre-wetting fluid DW may be discharged through the drainage portsD.

is a schematic cross-sectional view illustrating another variation of a pre-wetting apparatus shown inaccording to some embodiment, and thus the details of the apparatus are not repeated for the sake of brevity. Referring toand with reference to, the difference between the pre-wetting apparatusB and the pre-wetting apparatusA inincludes that a plurality of conduitsis configured to convey the pre-wetting fluid DW. Although two conduits are shown, it is understood that more than two conduits may be configured. In some embodiments, the conduitsare positioned above the semiconductor workpiece W to deliver the pre-wetting fluid DW from the pre-wetting fluid tanktoward the semiconductor workpiece W as indicated by the arrows A. The conduitsmay be distributed along the perimeter of the semiconductor workpiece W, and the pre-wetting fluid DW flowing to the semiconductor workpiece W may spread from the edges to the center of the major surface WSof the semiconductor workpiece W as indicated by the dashed arrows A. In some embodiments, one of the conduits is positioned at the center of the semiconductor workpiece W and another one of the conduits is positioned at the edge of the semiconductor workpiece W. Again, other configuration of the conduits may be possible.

is a schematic cross-sectional view illustrating a pre-wetting apparatus including a semiconductor workpiece rinsed by pre-wetting fluid according to some embodiments. The pre-wetting apparatusA shown inis similar to the pre-wetting apparatusdescribed in, like reference numbers are used to designate like elements, and the details of the similar elements are not repeated for the sake of brevity. The condition shown inmay correspond to the stepdescribed in. The dashed arrows indicate that the spinning may be or may not be performed during the wetting.

Referring to, the conduitsare coupled to the pre-wetting fluid tankand extend into the process chamberA to deliver the pre-wetting fluid from the pre-wetting fluid tankinto the process chamberA in vapor form. In some embodiments, the pre-wetting fluid is condensable fluid vapors which may be (or may not be) degassed prior to introducing into the process chamberA. As used herein, the pre-wetting fluid in vapor form is called pre-wetting vapors DV. In some embodiments, the pre-wetting vapors DV are formed by vaporization of deionized water. The pre-wetting vapors DV may include other substances depending on process requirements. The pre-wetting fluid tankmay contain high moisture content (e.g., about 100% relative humidity). For example, the pre-wetting fluid tankis equipped with a heating device(e.g., heater, hot plate, vapor generator, and/or the like) configured to heating the pre-wetting fluid and allowing pre-wetting fluid to vaporize. In some embodiments, the temperature in the pre-wetting fluid tankis maintained to be higher than about 90° C. Although the temperature in the pre-wetting fluid tank may vary depending on the content and pressure of the pre-wetting fluid.

In some embodiments, to ensure that the pre-wetting vapors DV flowing into the process chamberA without condensation inside the conduits, the conduitsare kept in a heating condition using, for example, the heating device′. The heating device′ equipped with the conduitsmay be the same or similar to the heating deviceequipped with the pre-wetting fluid tank. It is understood that the number and the configuration of the conduits and the heating devices construes no limitation in the disclosure. For example, portions of the conduitsextending into the process chamberA are positioned at the upper portionof the process chamberA above the semiconductor workpiece W, and the portions of the conduitsmay include a plurality of holes (or outlets)distributed on the sidewalls of the conduits. The pre-wetting vapors DV may enter the process chamberA through the holesas indicated by the dashed arrows A. In some embodiments, the portions of the conduitsare disposed in a vertical (or tilted) manner relative to the major surface WSof the semiconductor workpiece W to avoid the fluid droplets directly falling onto the major surface WSof the semiconductor workpiece W. It is understood that the number, the size, and the configuration of the holes are shown for illustrative purpose only and may vary depending on process requirements.

In some embodiments, the process chamberA includes tilted surfacesconnected to the chamber sidewall and the ceiling. The tilted surfacesmay be configured to prevent the condensation of the pre-wetting vapors DV on the top of the process chamber that resides above and possibly falls onto the semiconductor workpiece W. For example, the condensation of the pre-wetting vapors DV on the ceiling of the process chamberA is directed to the overflow reservoir (e.g., the bottom of the process chamber) through the tilted surfacesand then drained through the drainage portsD. It is noted that the tilt angles of the tilted surfacesrelative to the sidewalls of the process chamberA may depend on chamber design and construe to limitation in the disclosure. The tilted surfacesmay be replaced with any suitable flow-directing plate or other configuration.

With continued reference to, the workpiece holderof the pre-wetting apparatusA may be equipped with a temperature control device(e.g., thermoelectric cooling device, heat exchanging device, cooling plate, and/or the like). In some embodiments, the temperature control deviceis configured to reduce the temperature of the semiconductor workpiece W disposed on the workpiece holder. For example, during the wetting step, the temperature of the semiconductor workpiece W is reduced to a temperature below the condensation temperature (e.g., dew point temperature) of the pre-wetting vapors DV using the temperature control device. In this manner, the pre-wetting vapors DV introducing into the process chamberA may be allowed to condense to form pre-wetting fluid DW on the major surface WSof the semiconductor workpiece W. The condensation temperature may vary depending on parameters (e.g., the content of the pre-wetting fluid, the operation pressure in the process chamber, etc.).

In some embodiments, to facilitate the condensation process performed onto the major surface WSof the semiconductor workpiece W, the operation temperature in the process chamberA is set to be higher than the condensation temperature (e.g., dew point temperature) of the pre-wetting vapors DV to avoid condensation on the chamber sidewalls and/or the ceiling. As continuous delivery of the pre-wetting vapors DV through the holesof the conduits, the pre-wetting vapors DV condensing over the major surface WSof the semiconductor workpiece W may gradually form a flow of the pre-wetting fluid DW that wets the major surface WS. The condensation process performed onto the semiconductor workpiece W may form the pre-wetting fluid DW over the major surface WSin a slow manner without formation of bubbles. In some embodiments, the recessed portions of the major surface WSof the semiconductor workpiece W are filled with the condensed pre-wetting fluid DW during the wetting step and when the pressure in the process chamberA is changed (e.g., step). The excess pre-wetting fluid DW over the semiconductor workpiece W may overflow the top surface of the workpiece holderas indicated by the arrow A, and then the overflowed pre-wetting fluid may be discharged through the drainage portsD.

is a schematic cross-sectional view illustrating another variation of a pre-wetting apparatus shown inaccording to some embodiments. Like reference numbers are used to designate like elements, and the details of the similar elements are not repeated for the sake of brevity. Referring toand with reference to, the difference between the pre-wetting apparatusB and the pre-wetting apparatusA inlies in that the process chamberA includes a dome-shaped ceiling. For example, the dome-shaped ceilingis engaged with the chamber sidewalls to form vacuum seal, if desired. During the wetting step, the condensed pre-wetting fluid DW formed on the top of the process chamberB, if present, may be directed to the overflow reservoir (e.g., the bottom of the process chamber) and then drained through the drainage portsD. By configuring the dome-shaped ceiling, the condensation of the pre-wetting vapors DV on the top of the process chamber that resides above and possibly falls onto the semiconductor workpiece W may be prevented.

In accordance with some embodiments, a semiconductor apparatus for pre-wetting a semiconductor workpiece includes a process chamber, a workpiece holder disposed within the process chamber to hold the semiconductor workpiece, a pre-wetting fluid tank disposed outside the process chamber and containing a pre-wetting fluid, and a conduit coupled to the pre-wetting fluid tank and extending into the process chamber. The conduit delivers the pre-wetting fluid from the pre-wetting fluid tank out through an outlet of the conduit to wet a major surface of the semiconductor workpiece comprising a plurality of recess portions.

In accordance with some embodiments, a method of processing a semiconductor workpiece includes at least the following steps. The semiconductor workpiece is pre-wetted. The pre-wetting includes decreasing a pressure in a process chamber that contains a semiconductor workpiece held by a workpiece holder, flowing a pre-wetting fluid to the semiconductor workpiece to wet a major surface of the semiconductor workpiece which comprises a plurality of recessed portions, and increasing the pressure in the process chamber. A wetting rate across the major surface is regulated by adjusting a fluid pressure of the pre-wetting fluid, and the recessed portions of the semiconductor workpiece is filled with the pre-wetting fluid during increasing the pressure. The pre-wetting fluid is removed from the semiconductor workpiece, and a conductive material is plated on the semiconductor workpiece.

In accordance with some embodiments, a method of processing a semiconductor workpiece includes at least the following steps. A vacuum is applied to a process chamber that contains the semiconductor workpiece held by a workpiece holder, pre-wetting vapors are introduced into the process chamber, and the pre-wetting vapors condense on the major surface of the semiconductor workpiece that comprises a plurality of recessed portions.

In accordance with some embodiments, a semiconductor apparatus for pre-wetting a semiconductor workpiece includes a process chamber, a workpiece holder disposed within the process chamber to hold the semiconductor workpiece, a pre-wetting fluid tank disposed outside the process chamber and containing a pre-wetting fluid, and a conduit coupled to the pre-wetting fluid tank and extending into the process chamber. The conduit delivers the pre-wetting fluid from the pre-wetting fluid tank out through an outlet of the conduit to wet a major surface of the semiconductor workpiece, wherein the outlet of the conduit is positioned above the major surface of the semiconductor workpiece by a vertical distance.

In accordance with some embodiments, a semiconductor apparatus for pre-wetting a semiconductor workpiece includes a process chamber, a workpiece holder disposed within the process chamber to hold the semiconductor workpiece, a pre-wetting fluid tank disposed outside the process chamber and containing a pre-wetting fluid, and a conduit coupled to the pre-wetting fluid tank and extending into the process chamber. The conduit includes a plurality of holes distributed on a sidewall of the conduit, wherein the conduit delivers the pre-wetting fluid from the pre-wetting fluid tank out through the holes of the conduit to wet a major surface of the semiconductor workpiece.

In accordance with some embodiments, a semiconductor apparatus includes a process chamber, a workpiece holder and a pre-wetting fluid tank. The workpiece holder is disposed within the process chamber to hold a semiconductor workpiece. The pre-wetting fluid tank is disposed outside the process chamber, wherein the workpiece holder comprises an inner sidewall, an outer sidewall and a channel between the inner sidewall and the outer sidewall, the channel is coupled to the pre-wetting fluid tank, and the outer sidewall is higher than the inner sidewall relative to a major surface of the semiconductor workpiece.

In accordance with some embodiments, a semiconductor apparatus includes a process chamber, a workpiece holder, a pre-wetting fluid tank and a conduit. The workpiece holder is disposed within the process chamber, comprising an inner sidewall and an outer sidewall, wherein the inner sidewall forms a space to hold a semiconductor workpiece. The pre-wetting fluid tank is disposed outside the process chamber and containing a pre-wetting fluid. The conduit is coupled to the pre-wetting fluid tank to deliver the pre-wetting fluid, wherein the conduit is disposed between the inner sidewall and the outer sidewall, the outer sidewall is higher than the inner sidewall relative to a major surface of the semiconductor workpiece, and an excess portion of the pre-wetting fluid overflows from the outer sidewall of the workpiece holder.

In accordance with some embodiments, a method includes at least the following steps. A semiconductor workpiece is disposed on a workpiece holder in a process chamber, wherein the workpiece holder comprises an inner sidewall, an outer sidewall and a conduit between the inner sidewall and the outer sidewall, and the outer sidewall is higher than the inner sidewall relative to a major surface of the semiconductor workpiece. The semiconductor workpiece is pre-wetted. The pre-wetted process includes decreasing a pressure in the process chamber, flowing a pre-wetting fluid to the semiconductor workpiece through the conduit to wet the major surface of the semiconductor workpiece and increasing the pressure in the process chamber. The pre-wetting fluid is removed from the semiconductor workpiece. A conductive material is placed on the semiconductor workpiece.

The foregoing outlines features of several embodiments so that those skilled in the art may better understand the aspects of the present disclosure. Those skilled in the art should appreciate that they may readily use the present disclosure as a basis for designing or modifying other processes and structures for carrying out the same purposes and/or achieving the same advantages of the embodiments introduced herein. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the present disclosure, and that they may make various changes, substitutions, and alterations herein without departing from the spirit and scope of the present disclosure.