Selective treatment of microelectric workpiece surfaces

This invention provides a process for treating a workpiece having a front side, a back side, and an outer perimeter. In accordance with the process, a processing fluid is selectively applied or excluded from an outer peripheral margin of at least one of the front or back sides or the workpiece. Exclusion and/or application of the processing fluid occurs by applying one or more processing fluids to the workpiece as the workpiece and corresponding reactor are spinning about an axis of rotation that is generally orthogonal to the center of the face of the workpiece being processed. The flow rate of the one or more processing fluids, fluid pressure, and/or spin rate are used to control the extent to which the processing fluid is selectively applied or excluded from the outer peripheral margin.

FIELD

The present invention relates to the selective chemical processing of front side, back side and perimeter edge surfaces of microelectronic substrates.

BACKGROUND

This invention pertains to treating a substrate such as a semiconductor wafer, e.g., a silicon wafer, so as to remove a thin film, such as a copper or other metal or oxide film, from selected regions on the wafer.

The fabrication of a microelectronic circuit and/or component from a substrate typically involves a substantial number of processes. Many of these processes involve the deposition of a thin film on the surface of the workpiece followed by contact with a processing liquid, vapor, or gas. In a known process for treating a microelectronic workpiece, such as a silicon wafer, on which microelectronic devices have been fabricated and which has a front, device side, a back, non-device side, and an outer perimeter, thin-film layers are successively applied and etched to form, for example, a metallized interconnect structure. In a typical metallization process, both sides of a semiconductor wafer are coated with a protective film such as a silicon nitride or a silicon oxide. Thereafter, a barrier layer such as titanium nitride, tantalum or tantalum nitride is applied over a dielectric layer on the front side of the workpiece. Depending upon the particular process used to form the interconnect structures, the dielectric layer may include a pattern of recessed micro-structures that define the various interconnect paths. A thin metal film, such as a copper film is applied exterior to the barrier layer. In most instances, the thin film serves as an initial seed layer for subsequent electroplating of a further metal layer, such as a further copper layer. Due to manufacturing constraints, the thin film is not applied over an outer, peripheral margin of the front side.

Known techniques, such as physical vapor deposition (sputtering) or chemical vapor deposition, are typically used to apply the barrier layer and the thin film. Both methods can deposit copper onto the wafer bevel (the peripheral edge of the wafer), and in many cases this deposit is non adherent and can flake off in subsequent processing steps such as annealing or CMP. After deposition of the barrier layer, additional layers may be deposited to the wafer front side edge. In instances in which a further metal layer is to be electroplated exterior to the thin film, one or more electrical contacts are connected to an outer margin of the thin film to provide plating power. Because subsequent layers are deposited with an edge exclusion, the previously deposited layers are left exposed. Many of these layers allow copper to be deposited on them, but the adhesion is very poor and flaking during post processing is observed. A typical copper example might be an exposed barrier layer such as Ti/TiN being exposed to copper plating solution. Following electrochemical deposition, the barrier layer would have a copper film of low quality which would flake off easily in CMP. Removal of flaking material before CMP processing is desirable as the flakes have the potential to cause scratches in the polished surface, resulting in yield losses.

The surface area of the front side beyond the inner boundary of the outer margin of the thin film is not available for fabricating the microelectronic devices since the present manufacturing processes limit the extent to which device structures can be formed at the outer margin. It would be highly desirable and would result in increased yield if more of the surface area beyond the present limits of the outer margin of the thin film were available for fabricating interconnect structures.

Covering the exposed barrier layer with a full coverage seed layer would eliminate copper metal from flaking off the barrier and also have the added benefit of increasing usable area on the wafer surface. Even in this case, copper deposited on the bevel during the seed layer and electrochemical deposition would need to be removed, as it too can flake off and/or cause cross contamination of metrology tools. A clear area inboard of the wafer bevel may also be necessary for reliable processing; many clamp rings are very sensitive to surface characteristics.

In the known process discussed above, and in other processes, contamination by copper, other metals, or other contaminants can occur on the back side of the workpiece. Although copper and other metals tend to diffuse rapidly through silicon or silicon dioxide, the back side is generally not provided with barrier layers that are capable of preventing copper, other metals, or other contaminants from diffusing through the silicon wafer to the front side, at which such contamination can be very detrimental to device performance.

Such contamination can result from overspraying or other processing artifacts or from cross-contamination via fabrication tools. Such contamination can occur on the outer perimeter of a silicon wafer as well as on its back side.

If not removed, such contamination can lead to cross-contamination of other wafers, via fabrication tools. Such contamination can be very difficult to remove, particularly if the contaminant has formed a stable silicide. It would be highly desirable if such contamination could be easily removed in a controlled manner without detrimentally affecting the front side of the workpiece.

SUMMARY

The present invention provides processes for selectively treating surfaces of a workpiece having a first side, an opposing second side, and a peripheral edge defined between the perimeters of the first and second sides. In a first aspect of the present invention, a process is provided for applying a first fluid to the first side and peripheral edge of the workpiece, while excluding the first fluid from at least a majority of the second side of the workpiece. In a still further preferred embodiment, the first fluid is applied to the first side of the workpiece, the peripheral edge, and an outer perimeter portion of the second side of the workpiece. The first fluid preferably comprises an etchant to remove a metal film or oxide film from the exposed surface portions of the workpiece, to the exclusion of the remaining substantially non-exposed portion of the second side of the workpiece.

In a still further aspect of the present invention, a workpiece having a first side, an opposing second side, and a peripheral edge defined between the outer perimeters of the first side and the second side is received within a fluid chamber of a reactor. The fluid chamber has a first chamber portion which receives the first surface of the workpiece, and a second chamber portion which receives the second surface of the workpiece. A first fluid is supplied to the first chamber portion, in which the first side is exposed to the first fluid to the exclusion of the second side of the workpiece, which is not exposed in totality or to a predetermined extent to the first fluid. In the preferred embodiment, the first fluid includes an acid, preferably an inorganic acid, and an oxidizer that act on the first side to remove a metal film or oxide film therefrom, while not substantially affecting the second side of the workpiece or a selected portion of a second side of the workpiece. In addition to or in lieu of supplying the first fluid, a second fluid may optionally be supplied to the second chamber portion of the reactor, so that the second side of the workpiece or a selected portion of the second side of the workpiece is exposed to the second fluid. The second fluid may be a different process fluid such as an inert gas or liquid, a diluent or rinsing agent or other fluid.

The present invention thus provides a method and apparatus for selectively exposing a second side of a workpiece, such as a back side of a semiconductor wafer, to an etchant solution preferably including an etchant solvent, such as an acid, and optionally, an oxidizer, to remove a metal film, an oxide film or particulates from the back side of the wafer. The present invention also provides for exposure of the peripheral edge of the workpiece, such as the bevel edge of a semiconductor wafer, to the etchant solution to remove a metal film or oxide film from the bevel edge. Additionally, the processes and apparatus of the invention may be utilized to etch, remove, or reduce a metal film or an oxide film from a perimeter edge portion of the opposing second side of the workpiece, such as a narrow annular exclusion zone bordering the perimeter edge of the front (i.e., device) side of a semiconductor wafer. The selective exposures of surfaces of the workpiece are made without substantial exposure of the remainder of the second side of the workpiece, i.e., in the preferred embodiment, the device or front side of the semiconductor wafer. While the first fluid is supplied to the first side of the workpiece, the opposing second side of the workpiece may be exposed to no fluid, or may alternately be exposed to a purge fluid such as an inert gas or deonized water, or to another process fluid.

The present invention also provides semiconductor wafers and other workpieces produced from these processes.

The present invention also provides etchant solutions including an inorganic acid and ozone as an oxidizer, preferably hydrofluoric acid and ozone.

In a still further aspect of the invention, a processing fluid is selectively applied or excluded from an outer peripheral margin of at least one of the front or back sides of the workpiece. Exclusion and/or application of the processing fluid occurs by applying one or more processing fluids to the workpiece as the workpiece and corresponding reactor are spinning about an axis of rotation that is generally parallel (or antiparallel) to the vector defining the face of the workpiece being processed. The flow rate of the one or more processing fluids, fluid pressure, and/or spin rate are used to control the extent to which the processing fluid is selectively applied or excluded from the outer peripheral margin.

In a further aspect of the invention, a thin film is applied over the front side and over at least a portion of the outer perimeter. Usually, a barrier layer is applied over the front side and over at least a portion of the outer perimeter, whereupon a further thin film, such as a conductive seed layer, is applied over the barrier layer.

In a preferred embodiment, after one or more further intervening steps, such as electroplating of a metal layer onto the conductive seed layer, an etchant capable of removing one or more of the thin film layers is caused to flow over an outer margin of the front side while the etchant is prevented from flowing over the front side except for the outer margin. Thus, the etchant only contacts the outer margin of the front side thereby selectively removing only the one or more thin film layers from the outer margin of the front side. If the etchant is also caused to flow over the back side and over the outer perimeter, as well as over the outer margin of the front side, the one or more thin film layers are removed from the outer perimeter and any contaminant that the etchant is capable of removing is stripped from the back side as well.

Rather than an etchant, a cleaning chemical can be used in some applications to remove or dissolve the one or more thin film layers as described above.

DETAILED DESCRIPTION

Although the process of the present invention has applicability to any process in which a processing fluid is selectively provided to or excluded from an outer margin of an electrochemically processed workpiece, the present invention is particularly well suited for removal of a film, or a portion of a film, that has been deposited on a substrate by electrolytic or electroless processing, specifically metal films and oxide films. Thus the invention is suitably used for removing or decreasing the thickness of metal films from select surfaces of a workpiece, including by way of nonlimiting example, films containing copper, copper alloys such as copper zinc, neon, zinc, chromium, tin, gold, silver, lead, cadmium, platinum, palladium, iridium, or rubidium. Such metal films are typically removed using solutions applied in accordance with the present invention, including an etchant such as an acid and preferably an oxidizing agent, as shall be described further subsequently. Oxide films can also be suitably removed in whole or in part in accordance with the present invention, including metal oxides, silicon oxides, and barrier and protective layers, such as by way of nonlimiting examples, silicon nitride, silicon oxide, polysilicon, tantalum nitride, and titanium nitride. The term “film” and “contaminant” are used interchangeably herein. However, the term “workpiece” is not limited to semiconductor wafers, but rather refers to substrates having generally parallel planar first and second surfaces and that are relatively thin, including semiconductor wafers, ceramic wafers, and other substrates upon which microelectronic circuits or components, data storage elements or layers, and/or micromechanical elements are formed.

A preferred embodiment of the invention will be described in connection with a sequence of processing steps for depositing one or more metallization layers or metallized structures on a semiconductor workpiece, with it being understood that the invention is adaptable for use with other workpieces and films.

The known sequence of processing steps in accordance with the prior art begins with a semiconductor wafer10, on which microelectronic devices (not shown) have been fabricated. As illustrated inFIG. 1A, the wafer10has a front, device side12, a back, non-device side14, and a beveled, outer perimeter16. Via physical vapor deposition (sputtering) or chemical vapor deposition, a barrier layer20is applied over the front side12and over an upper portion18of the outer perimeter16. A thin-film seed layer, such as a copper film30, is applied over the barrier layer20. Conventionally, the seed layer30is only deposited within the bounds of an outer margin22of the barrier layer20, as illustrated inFIG. 1B. At an outer edge32of the copper film30, one or more electrical contacts40to be used in providing electroplating power to the seed layer are placed in electrical contact with the copper film30, as illustrated inFIG. 1C.

After the one or more electrical contacts40have been connected to the seed layer copper film30a further copper layer50from which interconnect structures and/or metallized devices are fabricated is electroplated onto the wafer110as illustrated inFIG. 1C. The electrical contact(s)40are then removed to provide the resultant multi film structure, shown generally at60inFIG. 1D. Beyond an inner boundary34of the outer margin32of the copper layer50, an annular region62of the front side12is not available for fabricating such interconnect structures or metallized devices.

One example of novel sequence of processing steps in accordance with the present invention begins with a silicon wafer70, which is similar to the silicon wafer10before processing, on which microelectronic devices (not shown) have been fabricated, and which has a front, device side72, a back, non-device side74, and a beveled, outer perimeter76, as illustrated inFIG. 2A. Via physical vapor deposition (sputtering) or chemical vapor deposition, a barrier layer80is applied over the front side72and over an upper portion78of the outer perimeter76and a thin seed layer, such as a copper film82is applied over the entire barrier layer80, without exclusion from a peripheral outer margin86, so as to cover the barrier layer80where applied over the front side72and over the upper portion78of the outer perimeter76, as illustrated inFIG. 1B. At an outer edge84of the copper seed layer82, one or more electrical contacts87to be used in electroplating are connected to provide electroplating power to the copper film82, as illustrated inFIG. 2C. As illustrated, the outer edge84at which contact may be made for the supply of electroplating power illustrated inFIG. 2Cis substantially closer to the peripheral edge than the process as illustrated inFIG. 1C.

A further copper film88from which metallized interconnects and/or microelectronic devices are fabricated is then applied using an electrochemical deposition process. As illustrated inFIG. 2C, the further copper film88is deposited within the outer margin92of the copper film82. The electrical contact86is then removed leaving the resultant multi-layer structure shown generally at90ofFIG. 2D. Metallized devices (not shown) and/or interconnects are formed by known techniques, from the resultant structure90. After the copper layer88has been deposited, the seed layer82, film88, and/or barrier layer80may be removed from the outer margin84and, if desired peripheral edge76of the workpiece70. Removal of at least layer82from the outer margin assists in preventing film flaking and cross-contamination problems that may occur during subsequent workpiece processing.

In accordance with an embodiment the process, processing fluid is selectively applied to the outer peripheral margin of at least the front side of the workpiece. Exclusion and/or application of the processing fluid occurs by applying one or more processing fluids to the workpiece as the workpiece and corresponding reactor are spinning about an axis of rotation that is generally aligned on the central orthogonal axis of the face of the workpiece being processed. The flow rate of the one or more processing fluids, fluid pressure, and/or spin rate are used to control the extent to which the processing fluid is selectively applied to the outer peripheral margin.

A reactor suitable for executing the foregoing removal process may generally be comprised of upper and lower members that define an upper chamber and a lower chamber with respect to the workpiece contained therein. A centrally disposed inlet is provided to each of the upper an lower chambers for supplying one or more processing fluids. Fluid outlets are disposed at peripheral portions of the chambers and are adapted to assist in the exclusion of one processing fluid from the outer margin of the workpiece while allowing intrusion of an etchant thereat. The upper and lower chambers are rotated conjointly so as to distribute a processing fluid in the upper chamber across an upper side of the workpiece through centripetal acceleration and so as to distribute a processing fluid in the lower chamber across a lower side of the workpiece through centripetal acceleration. Depending upon the processes being performed, however, the processing fluids in the upper and lower chambers may be the same fluid or different fluids.

Also, rather than relying on the rotation of the workpiece, the processing fluid could also be selectively driven by pumps.

Through control of the respective pressures of the processing fluids entering the respective chambers and of the rotational speed of the rotating chambers, it is possible to control the reactor so as to cause the processing fluid entering the inlet of the lower chamber to flow over the near side of the wafer, over the outer perimeter of the workpiece, and over an outer margin of the far side of the workpiece, and so as to prevent the same processing fluid from flowing over the far side except for the outer margin. The control of the fluid pressures may be achieved for example through the use of a pump for liquids, or a pressure regulator for a pressurized gas source.

B. Process Overview

The present invention provides processes for selectively removing a film, such as a metal film or oxide film, from selected surface portions of a semiconductor workpiece. The metal film or oxide film can be selectively removed from: a single side of the workpiece; the peripheral edge of the workpiece; the peripheral edge and back side of the workpiece; the peripheral edge and an exclusion zone defined by a narrow annular perimeter edge portion of the front side of the workpiece; or the back side, peripheral edge and exclusion zone. To remove such films, such as metal contaminants that are not desired on the peripheral edge and/or the back side, an etchant solution is utilized which first oxidizes the metal and then solubilizes the oxidized metal to remove it from the selected surface portion. Oxide films may likewise be removed from selected surfaces of the workpiece using an acidic etchant. While the back side and/or peripheral edge is being etched, the front or device side of the semiconductor wafer may be left unprocessed, or may be exposed to an inert material such as a purge gas (e.g., nitrogen or helium), to a rinse such as deionized water, or to another processing fluid such as a more highly diluted etchant. The front side of the wafer (excluding the exclusion zone) is either left unprocessed, or is processed to a lesser degree without damage to the underlying devices, metal interconnects or semiconductor layers.

The processes of the present invention are adapted for many types of processes, including the removal of metal films such as copper ion contamination that is deposited on the peripheral bevel edge or the back side of a wafer during previous processing steps. For example, copper ion contamination can be removed from the bevel edge and back side, and additionally bulk copper can be selectively removed by a reduction in thickness from all areas of the substrate including the front or device side, to a predetermined extent. While reference is made herein to treating a bevel edge, it should also be understood that the methods of the present invention are adaptable for treating non-beveled edges such as flatted edges of semiconductor wafers.

In addition to copper removal, other examples of uses for the processes and apparatus of the present invention are, without limitation: the removal of cobalt contaminants from the back side and/or bevel edge of the wafer; the removal of contaminant particles from the back side of a semiconductor wafer prior to photo-lithography; the removal of residue remaining after dry plasma etching of the front side of the front side of a semiconductor wafer; the oxide etching of one or both sides and/or the peripheral edge of a semiconductor wafer; the etching of silicon nitride from one or both sides of the peripheral edge of a semiconductor wafer, and other processing techniques where it is desirable to selectively remove a metal or oxide film from surfaces. Other uses of the processes of the present invention include removal of noble metals (Pt, Pd, Ru, Ir), and removal of metallic oxides such as high K dielectrics (BST, SBT, Ta2O5) from the backside and peripheral edge.

Before describing these processes in detail, suitable equipment for carrying out the processes of the present invention are first described.

A system92useful for carrying out the processes of the present invention is illustrated inFIG. 3.FIG. 3includes one or more preprocessing stations94, in which a substrate that is to be electrochemically processed is prepared. In the case of a semiconductor wafer, the processing station94may be a chemical vapor deposition or physical vapor deposition station, such as for applying a barrier layer to a workpiece. The thusly prepared workpiece is then moved to one or more further processing stations96, where, for example, a thin metal film such as a seed layer may be deposited on the substrate. Additional process steps may be incorporated as required to complete preparation of the workpiece for electrochemical treatment, such as the application of a metal film. The workpiece then is passed, either manually or under automated control, to a reactor98, in which the metal film is to be deposited. In the case of a semiconductor wafer this may be an electroplating reactor98, in which metal is deposited over the seed layer to the front or device side of the wafer, with potential contamination of the bevel edge and back side of the wafer.

The semiconductor wafer is then moved to an etching reactor100, in which the surfaces of the workpiece are to be selectively treated to remove metal film or oxide film. In the preferred embodiment, the reactor100provides for selective etching of the back side, bevel edge and/or perimeter exclusion zone of a semiconductor wafer. The workpiece is received within a chamber defined within the reactor100, with a first side of the workpiece being exposed to a lower chamber portion102and a second side of the workpiece being exposed to an upper chamber portion104. The terms “upper” and “lower” are used herein for convenience, and other orientation are also encompassed by the invention.

The perimeter edge of the workpiece may be sealed, or may be in communication with fluid outlets at a perimeter edge portion106of the reactor. The side of the workpiece exposed to the lower chamber102may then be selectively supplied with one or more fluids from fluid supplies108, such as deionized water for rinsing, chemical solution for etching or other processing, or an inert fluid such as nitrogen. In addition to or in lieu of fluids being supplied from the supplies108to the lower chamber102, one or more fluids may be selectively supplied from one or more fluid supplies110to the upper chamber104. Again, fluid supplies110may supply a chemical processing fluid, deionized water, or purge gas such as nitrogen. Supply of the various fluids is controlled by a programmable controller112that operates valves or pumps supplying the various fluids. In accordance with the present invention, fluid may be supplied only to one side of the workpiece, such as a chemical solution provided to etch the back side and/or peripheral edge, with no fluid being supplied to the opposing second side of the workpiece. In the preferred embodiment, however, while the first side is being supplied with a chemical solution, the second side is being supplied with an inert gas or deionized water rinse, or an alternate processing solution. After etching, the etched side of preferably both sides of the wafer are supplied with deionized water rinse, spun to remove fluids, and dried with heated nitrogen.

Various configurations of reactors may be utilized for carrying out the selective treatment of the present invention. By way of example, the processes provided by this invention can be advantageously practiced in one of a variety of reactors illustrated and described in U.S. patent application Ser. Nos. 09/437,711 filed Nov. 10, 1999 and 09/437,926 filed Nov. 10, 1999, the disclosures of which are hereby incorporated herein by reference.

FIG. 4is a cross-sectional view of one suitable embodiment of a reactor, shown generally at114, constructed in accordance with the teachings of the present invention. The embodiment of the reactor114ofFIG. 4is generally comprised of a rotor portion115and a microelectronic workpiece housing116. The rotor portion115includes a plurality of support members118that extend downwardly from the rotor portion115to engage the workpiece housing116. Each of the support members118includes a groove120that is dimensioned to engage a radially extending flange122that extends about a peripheral region of the workpiece housing116. Rotor portion115further includes a rotor motor assembly124that is disposed to rotate a hub portion126, including the support members118, about a central axis128. Workpiece housing116is thus secured for co-rotation with hub portion130when support members118are engaged with flange122. Other constructions of the rotor portion115and the engagement mechanism used for securement with the workpiece housing116may also be used.

The workpiece housing116of the embodiment ofFIG. 4defines a substantially closed processing chamber132. Preferably, the substantially closed processing chamber132is formed in the general shape of the microelectronic workpiece134and closely conforms with the surfaces of the workpiece. The specific construction ofFIG. 1includes an upper chamber member136having an interior chamber face138. The upper chamber member136includes a centrally disposed fluid inlet opening140in the interior chamber face138. The specific construction also includes a lower chamber member142having an interior chamber face144. The lower chamber member142has a centrally disposed fluid inlet opening148in the interior chamber face144. The upper chamber member136and the lower chamber member146engage one another to define the processing chamber132. The upper chamber member136includes sidewalls150that project downward from the interior chamber face138. One or more outlets152are disposed at the peripheral regions of the processing chamber132through the sidewalls150to allow fluid within the chamber132to exit therefrom through centripetal acceleration that is generated when the housing116is rotated about axis128.

In the illustrated embodiment, the microelectronic workpiece134is a generally circular wafer having upper and lower planar surfaces. As such, the processing chamber132is generally circular in plan view and the interior chamber faces138and144are generally planar and parallel to the upper and lower planar surfaces of the workpiece134. The spacing between the interior chamber faces138and144and the upper and lower planar surfaces of the workpiece134is generally quite small. Such spacing is preferably minimized to provide substantial control of the physical properties of a processing fluid flowing through the interstitial regions.

The wafer134is spaced from the interior chamber face144by a plurality of spacing members154extending from the interior chamber face144. Preferably, a further set of spacing members146extend from the interior chamber face138and are aligned with the spacing members152to grip the wafer134therebetween.

Fluid inlet openings140and148provide communication passageways through which one or more processing fluids may enter the chamber132for processing the wafer surfaces. In the illustrated embodiment, processing fluids are delivered from above the wafer134to inlet140through a fluid supply tube156having a fluid outlet nozzle158disposed proximate inlet140. Fluid supply tube156extends centrally through the rotor portion115and is preferably concentric with the axis of rotation128. Similarly, processing fluids are delivered from below the wafer134to inlet148through a fluid supply tube160. Fluid supply tube160terminates at a nozzle162disposed proximate inlet148. Although nozzles158and162terminate at a position that is spaced from their respective inlets, it will be recognized that tubes156and160may be extended so that gaps are not present. Rather, nozzles158and162or tubes156and160may include rotating seal members that abut and seal with the respective upper and lower chamber members136and146in the regions of the inlets140and148. In such instances, care should be exercised in the design of the rotating joint so as to minimize any contamination resulting from the wear of any moving component.

During processing, one or more processing fluids are individually or concurrently supplied through fluid supply tubes156and160and inlets140and148for contact with the surfaces of the workpiece134in the chamber132. Preferably, the housing116is rotated about axis128by the rotor portion115during processing to generate a continuous flow of any fluid within the chamber132across the surfaces of the workpiece134through the action of centripetal acceleration. Processing fluid entering the inlet openings140and148are thus driven across the workpiece surfaces in a direction radially outward from the center of the workpiece134to the exterior perimeter of the workpiece134. At the exterior perimeter of the workpiece134, any spent processing fluid is directed to exit the chamber132through outlets166as a result of the centripetal acceleration. Spent processing fluids may be accumulated in a cup reservoir disposed below and/or about the workpiece housing116. As will be set forth below in an alternative embodiment, the peripheral regions of the workpiece housing116may be constructed to effectively separate the processing fluids provided through inlet140from the processing fluids supplied through inlet148so that opposite surfaces of wafer134are processed using different processing fluids. In such an arrangement, the processing fluids may be separately accumulated at the peripheral regions of the housing116for disposal or re-circulation.

In the embodiment ofFIG. 4, the workpiece housing116may constitute a single wafer pod that may be used to transport the workpiece134between various processing stations and/or tools. If transport of the housing116between the processing stations and/or tools takes place in a clean room environment, the various openings of the housing116need not be sealed. However, if such transport is to take place in an environment in which wafer contaminants are present, sealing of the various housing openings should be effected. For example, inlets140and148may each be provided with respective polymer diaphragms having slits disposed therethrough. The ends of fluid supply tubes156and160in such instances may each terminate in a tracor structure that may be used to extend through the slit of the respective diaphragm and introduce the processing fluid into the chamber132. Such tracor/slitted diaphragm constructions are used in the medical industry in intravenous supply devices. Selection of the polymer material used for the diaphragms should take into consideration the particular processing fluids that will be introduced therethrough. Similar sealing of the outlets166may be undertaken in which the tracor structures are inserted into the diaphragms once the housing116is in a clean room environment.

Alternatively, the outlets166themselves may be constructed to allow fluids from the processing chamber to exit therethrough while inhibiting the ability of fluids to proceed from the exterior of housing116into chamber132. This effect may be achieved, for example, by constructing the openings152as nozzles in which the fluid flow opening has a larger diameter at the interior of chamber132than the diameter of the opening at the exterior of the housing116. In a further construction, a rotational valve member may be used in conjunction with the plurality of outlets166. The valve member, such as a ring with openings corresponding to the position of outlets166, would be disposed proximate the opening166and would be rotated to seal with the outlets166during transport. The valve member would be rotated to a position in which outlets166are open during processing. Inert gas, such as nitrogen, can be injected into the chamber132through supply tubes156and160immediately prior to transport of the housing to a subsequent tool or processing station. Various other mechanisms for sealing the outlets166and inlets140and148may also be employed.

FIG. 5is a perspective view of a further reactor construction wherein the reactor is disposed at a fixed processing station and can open and close to facilitate insertion and extraction of the workpiece. The reactor, shown generally at200, is comprised of separable upper and lower chamber members,205and210, respectively. As in the prior embodiment, the upper chamber member205includes a generally planar chamber face215having a centrally disposed inlet220. Although not shown in the view ofFIG. 5, the lower chamber member210likewise has a generally planar interior chamber face225having a central inlet230disposed therethrough. The upper chamber member205includes a downwardly extending sidewall235that, for example, may be formed from a sealing polymer material or may be formed integrally with other portions of member205.

The upper and lower chamber members,205and210, are separable from one another to accept a workpiece therebetween. With a workpiece disposed between them, the upper and lower chamber members,205and210, move toward one another to form a chamber in which the workpiece is supported in a position in which it is spaced from the planar interior chamber faces215and225. In the embodiment of the reactor disclosed inFIGS. 5-11B, the workpiece, such as a semiconductor wafer, is clamped in place between a plurality of support members240and corresponding spacing members255when the upper and lower chamber members are joined to form the chamber (seeFIG. 10B). Axial movement of the upper and lower chamber members toward and away from each other is facilitated by a plurality of fasteners307, the construction of which will be described in further detail below. Preferably, the plurality of fasteners307bias the upper and lower chambers to a closed position such as illustrated atFIG. 10A.

In the disclosed embodiment, the plurality of wafer support members240extend about a peripheral region of the upper chamber member205at positions that are radially exterior of the sidewall235. The wafer support members240are preferably disposed for linear movement along respective axes245to allow the support members240to clamp the wafer against the spacing members255when the upper and lower chamber members are in a closed position (seeFIG. 10A), and to allow the support members240to release the wafer from such clamping action when the upper and lower chamber members are separated (seeFIG. 11A). Each support member240includes a support arm250that extends radially toward the center of the upper chamber member205. An end portion of each arm250overlies a corresponding spacing member255that extends from the interior chamber face215. Preferably, the spacing members255are each in the form of a cone having a vertex terminating proximate the end of the support arm250. Notches295are disposed at peripheral portions of the lower chamber member210and engage rounded lower portions300of the wafer support members240. When the lower chamber member210is urged upward to the closed position, notches295engage end portions300of the support members240and drive them upward to secure the wafer55between the arms250of the supports240and the corresponding spacing members255. This closed state is illustrated inFIG. 8. In the closed position, the notches295and corresponding notches296of the upper chamber member (seeFIG. 5) provide a plurality of outlets at the peripheral regions of the reactor200. Radial alignment of the arm250of each support member240is maintained by a set pin308that extends through lateral grooves309disposed through an upper portion of each support member.

The construction of the fasteners307that allow the upper and lower chamber members to be moved toward and away from one another is illustrated inFIGS. 5,9and10B. As shown, the lower chamber member210includes a plurality of hollow cylinders270that are fixed thereto and extend upward through corresponding apertures275at the peripheral region of the upper chamber member205to form lower portions of each fastener307. Rods280extend into the hollow of the cylinders270and are secured to form an upper portion of each fastener307. Together, the rods280and cylinders270form the fasteners307that allow relative linear movement between the upper and lower chamber members,205and210, along axis283between the open and closed position. Two flanges,285and290, are disposed at an upper portion of each rod280. Flange285functions as a stop member that limits the extent of separation between the upper and lower chamber members,205and210, in the open position. Flanges290provide a surface against which a biasing member, such as a spring (seeFIG. 9) or the like, acts to bias the upper and lower chamber members,205and210, to the closed position.

With reference toFIG. 9, the spring303or the like, has a first end that is positioned within a circular groove305that extends about each respective fastener307. A second end of each spring is disposed to engage flange290of the respective fastener307in a compressed state thereby causing the spring to generate a force that drives the fastener307and the lower chamber member210upward into engagement with the upper chamber member205.

The reactor200is designed to be rotated about a central axis during processing of the workpiece. To this end, a centrally disposed shaft260extends from an upper portion of the upper chamber member205. As will be illustrated in further detail below inFIGS. 10A-11B, the shaft260is connected to engage a rotary drive motor for rotational drive of the reactor200. The shaft260is constructed to have a centrally disposed fluid passageway (seeFIG. 7) through which a processing fluid may be provided to inlet220. Alternatively, the central passageway may function as a conduit for a separate fluid inlet tube or the like.

As illustrated inFIGS. 6 and 7, a plurality of optional overflow passageways312extend radially from a central portion of the upper chamber member205. Shaft260terminates in a flared end portion315having inlet notches320that provide fluid communication between the upper portion of processing chamber310and the overflow passageways312. The flared end315of the shaft260is secured with the upper chamber member205with, for example, a mounting plate325. Mounting plate325, in turn, is secured to the upper chamber member205with a plurality of fasteners330(FIG. 8). Overflow passages312allow processing fluid to exit the chamber310when the flow of fluid to the chamber310exceeds the fluid flow from the peripheral outlets of the chamber.

FIGS. 10A and 10Bare cross-sectional views showing the reactor200in a closed state and connected to a rotary drive assembly, shown generally at400, whileFIGS. 11A and 11Bare similar cross-sectional views showing the reactor200in an opened state. As shown, shaft260extends upward into the rotary drive assembly400. Shaft260is provided with the components necessary to cooperate with a stator405to form a rotary drive motor assembly410.

As in the embodiment ofFIG. 4, the upper and lower chamber members205and210join to define the substantially closed processing chamber310that, in the preferred embodiment, substantially conforms to the shape of the workpiece55. Preferably, the wafer55is supported within the chamber310in a position in which its upper and lower faces are spaced from the interior chamber faces215and225. As described above, such support is facilitated by the support members240and the spacing members255that clamp the peripheral edges of the wafer55therebetween when the reactor200is in the closed position ofFIGS. 10A and 10B.

It is in the closed state ofFIGS. 10A and 10Bthat processing of the wafer55takes place. With the wafer secured within the processing chamber310, processing fluid is provided through passageway415of shaft260and inlet220into the interior of chamber310. Similarly, processing fluid is also provided to the chamber310through a processing supply tube125that directs fluid flow through inlet230. As the reactor200is rotated by the rotary drive motor assembly410, any processing fluid supplied through inlets220and230is driven across the surfaces of the wafer55by forces generated through centripetal acceleration. Spent processing fluid exits the processing chamber310from the outlets at the peripheral regions of the reactor200formed by notches295and296. Such outlets exist since the support members240are not constructed to significantly obstruct the resulting fluid flow. Alternatively, or in addition, further outlets may be provided at the peripheral regions.

Once processing has been completed, the reactor200is opened to allow access to the wafer, such as shown inFIGS. 11A and 11B. After processing, actuator425is used to drive an actuating ring430downward into engagement with upper portions of the fasteners307. Fasteners307are driven against the bias of spring303causing the lower chamber member210to descend and separate from the upper chamber member205. As the lower chamber member210is lowered, the support members240follow it under the influence of gravity, or against the influence of a biasing member, while concurrently lowering the wafer. In the lower position, the reactor chamber310is opened thereby exposing the wafer for removal and/or allowing a new wafer to be inserted into the reactor200. Such insertion and extraction can take place either manually, or by an automatic robot.

The foregoing arrangement makes the reactor200particularly well-suited for automated workpiece loading and unloading by, for example, a robotic transfer mechanism or the like. As evident from a comparison ofFIGS. 10A and 11A, the spacing between the upper surface of the workpiece and the interior chamber wall of the upper chamber member205varies depending on whether the reactor200is in an open or closed state. When in the open state, the upper surface of the workpiece is spaced from the interior chamber wall of the upper chamber member205by a distance, x1, that provides sufficient clearance for operation of, for example, a workpiece transfer arm of a robotic transfer mechanism. When in the closed processing state, the upper surface of the workpiece is spaced from the interior chamber wall of the upper chamber member205by a distance, x2, that is less than the distance, x1. The distance, x2, in the disclosed embodiment may be chosen to correspond to the spacing that is desired during workpiece processing operations. While the processing of upper and lower surfaces is disclosed, processing of only a single surface is also within the scope of the present invention.

FIG. 12Aillustrates an edge configuration that facilitates separate processing of each side of the wafer. As illustrated, a dividing member500extends from the sidewall235of the processing chamber310to a position immediately proximate the peripheral edge505of the wafer55. The dividing member500may take on a variety of shapes, the illustrated tapered shape being merely one configuration. The dividing member500preferably extends about the entire circumference of the chamber310. A first set of one or more outlets510is disposed above the dividing member500to receive spent processing fluid from the upper surface of the wafer. Similarly, a second set of one or more outlets515is disposed below the dividing member500to receive spent processing fluid from the lower surface of the wafer. When the wafer rotates during processing, the fluid through supply415is provided to the upper surface of the wafer55and spreads across the surface through the action of centripetal acceleration. Similarly, the fluid from supply tube125is provided to the lower surface of the wafer and spreads across the surface through the action of centripetal acceleration. Because the edge of the dividing member500is so close to the peripheral edge of the wafer, processing fluid from the upper surface of the wafer does not proceed below the dividing member500, and processing fluid from the lower surface of the wafer does not proceed above the dividing member500. As such, this reactor construction makes it possible to concurrently process both the upper and lower surfaces of the wafer in a mutually exclusive manner using different processing fluids and steps.

FIG. 12Aalso illustrates one manner in which the processing fluids supplied to the upper and lower wafer surfaces may be collected in a mutually exclusive manner. As shown, a fluid collector520is disposed about the exterior periphery of the reactor200. The fluid collector520includes a first collection region525having a splatter stop530and a fluid trench535that is structured to guide fluid flung from the outlets510to a first drain540where the spent fluid from the upper wafer surface may be directed to a collection reservoir for disposal or re-circulation. The fluid collector520further includes a second collection region550having a further splatter stop555and a further fluid trench560that is structured to guide fluid flung from the outlets515to a second drain565where the spent fluid from the lower wafer surface may be directed to a collection reservoir for disposal or re-circulation.

FIGS. 12B and 12Cillustrate two alternate embodiments for peripheral edge and front side exclusion zone treatment using reactors and processes of the present invention. Referring toFIG. 12B, the peripheral edge of the wafer12is engaged by an edge seal566, while a nozzle567positioned above the front side exclusion zone, radially outboard from the center of the wafer, applies etchant or other solution to the exclusion zone. Alternately, if treatment of the entire front side, or treatment of the back side, is desired, multiple nozzles can be used at different radial locations, or the nozzle can move inwards and outwards while applying the treatment solution.FIG. 12Cillustrates a still further embodiment, in which rather than a nozzle567, an inlet568is provided for application of a fluid above the exclusion zone or at other locations through the reaction chamber wall onto the side of the wafer to be treated.

FIG. 13illustrates an embodiment of the reactor200having an alternate configuration for supplying processing fluid through the fluid inlet opening230. As shown, the workpiece housing20is disposed in a cup570. The cup570includes sidewalls575exterior to the outlets100to collect fluid as it exits the chamber310. An angled bottom surface580directs the collected fluid to a sump585. Fluid supply line587is connected to provide an amount of fluid to the sump585. The sump585is also preferably provided with a drain valve589. An inlet stem592defines a channel595that includes a first end having an opening597that opens to the sump585at one end thereof and a second end that opens to the inlet opening230.

In operation of the embodiment shown inFIG. 13, processing fluid is provided through supply line587to the sump585while the reactor200is spinning. Once the sump585is full, the fluid flow to the sump through supply line587is eliminated. Centripetal acceleration resulting from the spinning of the reactor200provides a pressure differential that drives the fluid through openings597and230, into chamber310to contact at least the lower surface of the wafer, and exit outlets100where the fluid is re-circulated to the sump585for further use.

There are numerous advantages to the self-pumping re-circulation system illustrated inFIG. 13. The tight fluid loop minimizes lags in process parameter control thereby making it easier to control such physical parameters as fluid temperature, fluid flow, etc. Further, there is no heat loss to plumbing, tank walls, pumps, etc. Still further, the system does not use a separate pump, thereby eliminating pump failures which are common when pumping hot, aggressive chemistries.

FIGS. 14 and 15illustrate two different types of processing tools, each of which may employ one or more processing stations including the reactor constructions described above.FIG. 14is a schematic block diagram of a tool, shown generally at600, including a plurality of processing stations605disposed about an arcuate path606. The processing stations605may all perform similar processing operations on the wafer, or may perform different but complementary processing operations. For example, one or more of the processing stations605may execute an electrodeposition process of a metal, such as copper, on the wafer, while one or more of the other processing stations perform complementary processes such as, for example, clean/dry processing, pre-wetting processes, photoresist processes, etc.

Wafers that are to be processed are supplied to the tool600at an input/output station607. The wafers may be supplied to the tool600in, for example, S.M.I.F. pods, each having a plurality of the wafers disposed therein. Alternatively, the wafers may be presented to the tool600in individual workpiece housings, such as at20ofFIG. 4.

Each of the processing stations605may be accessed by a robotic arm610. The robotic arm610transports the workpiece housings, or individual wafers, to and from the input/output station607. The robotic arm610also transports the wafers or housings between the various processing stations605.

In the embodiment ofFIG. 14, the robotic arm610rotates about axis615to perform the transport operations along path606. In contrast, the tool shown generally at620of theFIG. 15utilizes one or more robotic arms625that travel along a linear path630to perform the required transport operations. As in the embodiment ofFIG. 13, a plurality of individual processing stations605are used, but more processing stations605may be provided in a single processing tool in this arrangement.

FIG. 16illustrates one manner of employing a plurality of workpiece housings700, such as those described above, in a batch processing apparatus702. As shown, the workpiece housings700are stacked vertically with respect to one another and are attached for rotation by a common rotor motor704about a common rotation axis706. The apparatus702further includes a process fluid delivery system708. The delivery system708includes a stationary manifold710that accepts processing fluid from a fluid supply (not shown). The stationary manifold710has an outlet end connected to the input of a rotating manifold712. The rotating manifold712is secured for co-rotation with the housings700and, therefore, is connected to the stationary manifold710at a rotating joint714. A plurality of fluid supply lines716extend from the rotating manifold712and terminate at respective nozzle portions718proximate inlets of the housings700. Nozzle portions718that are disposed between two housings700are constructed to provide fluid streams that are directed in both the upward and downward directions. In contrast, the lowermost supply line716includes a nozzle portion718that directs a fluid stream only in the upward direction. The uppermost portion of the rotating manifold712includes an outlet720that provides processing fluid to the fluid inlet of the uppermost housing700.

The batch processing apparatus702ofFIG. 16is constructed to concurrently supply the same fluid to both the upper and lower inlets of each housing700. However, other configurations may also be employed. For example, nozzle portions718may include valve members that selectively open and close depending on whether the fluid is to be supplied through the upper and/or lower inlets of each housing700. In such instances, it may be desirable to employ an edge configuration, such as the one shown inFIG. 12, in each of the housings700to provide isolation of the fluids supplied to the upper and lower surfaces of the wafers55. Still further, the apparatus702may include concentric manifolds for supplying two different fluids concurrently to individual supply lines respectively associated with the upper and lower inlets of the housings700.

An embodiment of the reactor that is particularly well-suited for integration in an automated processing tool is illustrated inFIG. 17. The reactor, shown generally at800, includes features that cooperate in a unique manner to allow a robotic arm or the like to insert and extract a workpiece to and from the reactor800during loading and unloading operations while also maintaining relatively tight clearances between the workpiece and the interior chamber walls of the reactor during processing.

One of the principal differences between the reactor embodiments described above and the reactor800ofFIG. 17lies in the nature of the workpiece support assembly. As shown, reactor800includes a workpiece support assembly, shown generally at805, that is associated with the lower chamber member210. In accordance with the illustrated embodiment, the workpiece support assembly805includes a plurality of workpiece support members810that extend through the lower chamber member210. The workpiece support members810are supported at a lower end thereof by a biasing member815. At the end of the workpiece support member810that is distal the biasing member815, the workpiece support member810terminates at a workpiece support surface820and a guide structure825. The guide structure825extends from the workpiece support surface820and terminates at a frustoconical section830. The guide structure825assists in urging the peripheral edges of the workpiece into proper alignment with the workpiece support surface820thereby ensuring proper registration of the workpiece during processing. The guide structure825may also serve as a spacer that defines the clearance between the interior chamber wall of the upper chamber member205and the upper surface of the workpiece.

The biasing member815of the illustrated embodiment serves to bias the workpiece support members810in an upward direction when the upper and lower chamber members205and210are in the illustrated open condition in which the reactor800is ready for loading or unloading the workpiece. The biasing member815may take on various forms. For example, a single biasing structure may be used that is common to all of the workpiece support members810. Alternatively, as shown in the disclosed embodiment, individual biasing structures may be respectively associated with individual ones of the workpiece support members810. The individual biasing structures are in the form of leaf springs835but, for example, may alternatively be in the form of coil spring actuators or the like.

As in the embodiment of the reactor described above, the upper and lower chamber members205and210of reactor800are movable with respect to one another between the open condition ofFIG. 17to a closed processing condition as illustrated inFIG. 18. As the chamber members205and210move toward one another, the frustoconical sections830of the workpiece support members810engage the interior chamber wall of the upper chamber member205. Continued movement between the chamber members205and210drives the workpiece support members810against the leaf springs835until the workpiece is clamped between the support surfaces820of the workpiece support members810and corresponding projections840that extend from the interior chamber wall of the upper chamber member205. While in this closed state, the reactor is ready to process the workpiece.

The reactor800ofFIG. 17also includes structures which assists in ensuring proper registration between the upper and a lower chamber members210and205as they are brought proximate one another to their processing position. In the illustrated embodiment, these structures are in the form of lead-in pins845that extend from one of the chamber members to engage corresponding apertures of the other of the chamber members. Here, the lead-in pins845extend from the lower chamber member210to engage corresponding apertures (not shown) in the upper chamber member205. The lead-in pins845are in the form of upstanding members that each terminate in a respective frustoconical section that functions as a guide surface.

The foregoing arrangement makes the reactor800particularly well-suited for automated workpiece loading and unloading by, for example, a robotic transfer mechanism or the like, particularly one in which the workpiece is directly inserted into the reactor without flipping of the workpiece. As evident from a comparison ofFIGS. 17 and 18, the spacing between the lower surface of the workpiece and the interior chamber wall of the lower chamber member210varies depending on whether the reactor800is in an open or closed state. When in the open state, the lower surface of the workpiece is spaced from the interior chamber wall of the lower chamber member210by a distance, x1, that provides sufficient clearance for operation of, for example, a workpiece transfer arm of a robotic transfer mechanism. When in the closed processing state, the lower surface of the workpiece is spaced from the interior chamber wall of the lower chamber member210by a distance, x2, that is less than the distance, x1. The distance, x2, in the disclosed embodiment corresponds to the spacing that is desired during workpiece processing operations.

One embodiment of the biasing member815is illustrated inFIG. 19. As shown, the biasing member815is comprised of a plurality of leaf springs835that extend radially from a central hub portion850to positions in which they contact the underside of respective workpiece support members810. A further plurality of radial members855extend from the hub850to positions in which they contact the underside of respective lead-in pins845. Unlike the leaf springs835, the further plurality of radial members855are not necessarily designed to flex as the upper and lower chamber members210and205move toward the processing position. The biasing member825may be formed from a polymer material or the like which is resistant to the chemistry used in the processing environment. When formed from such a material, the workpiece support members810and lead-in pins845may be formed integral with their respective leaf springs835and radial members855.

In the illustrated embodiment, the central hub portion850includes a central aperture900that accommodates a securement905which connects the biasing member815to the underside of the lower chamber member210. With reference toFIGS. 17 and 18, the securement905can be formed to provide the processing fluid inlet through the lower chamber member210. When the securement905is formed in this manner, the reactor800is provided with a quick and easy manner of providing different inlet configurations for different processes.

On occasion, it may be desirable to remove the reactor800from head portion860. For example, the reactor800may be removed for service or for replacement with a reactor that is designed for executing other processes, or processing other workpiece types.

To this end, the reactor800and the head portion860are engaged at a connection hub assembly865which allows the reactor800to be easily connected to and disconnected from the head portion860. In embodiment illustrated inFIG. 18, the connection hub assembly865is comprised of a head connection hub870that is fixed to the processing head portion860, and a reactor connection hub875that is fixed to the reactor800. The connection hubs870and875are secured to one another during normal operation by, for example, a threaded joint880. A set screw885extends through the head connection hub870and may be rotated to engage a surface of or corresponding aperture in the reactor connection hub875to thereby prevents the connection hubs870and875from unscrewing.

When removal of the reactor800is desired, the reactor is rotated to align set screw885with a corresponding channel sleeve890that is fixed to the head portion860. The channel sleeve890is constructed to allow a user to extend a tool therethrough to engage the set screw885. The set screw is then turned to raise it until it engages and secures with a screw head block895. Once secured in this manner, the head connection hub870is rotationally locked with the head portion860thereby allowing the reactor800and corresponding reactor connection hub875to be unscrewed from the head connection hub870to remove the reactor.

In accordance with a still further feature of the reactor800, a stiffening member910formed, for example, from aluminum is secured with the upper chamber member205. By increasing the stiffness of the upper and/or lower chamber members, higher rotating speeds may be used and, further, the flatness of the interior chamber walls during processing may be increased.

Numerous substantial benefits flow from the use of the disclosed reactor configurations. Many of these benefits arise directly from the reduced fluid flow areas in the reactor chambers. Generally, there is a more efficient use of the processing fluids since very little of the fluids are wasted. Further, it is often easier to control the physical parameters of the fluid flow, such as temperature, mass flow, etc., using the reduced fluid flow areas of the reactor chambers. This gives rise to more consistent results and makes those results repeatable.

The foregoing constructions also give rise to the ability to perform sequential processing of a single wafer using two or more processing fluids sequentially provided through a single inlet of the reaction chamber. Still further, the ability to concurrently or sequentially provide different fluids to the upper and lower surfaces of the wafer opens the opportunity to implement novel processing operations. For example, a processing fluid, such as HF liquid, may be supplied to a lower fluid inlet of the reaction chamber for processing the lower wafer surface while an inert fluid, such as nitrogen gas, may be provided to the upper fluid inlet. As such, the HF liquid is allowed to react with the lower surface of the wafer while the upper surface of the wafer is effectively isolated from HF reactions. Numerous other novel processes may also be implemented.

The present inventors have recognized that demands for integrated circuit rinsing/drying processes may ultimately require more control and economic efficiency from the rinser/dryer. As such, a substantially new approach to rinsing and drying of the semiconductor wafer has been undertaken which provides greater control of the physical properties of the rinsing and drying fluids. Further, wafers may be rinsed and dried on an individual basis more quickly when compared to the drying of an individual wafer using any of the foregoing processes.

FIG. 20illustrates one manner of controlling the provision of rinsing/drying fluids that are supplied to the rinser/dryer of any of the foregoing embodiments. As illustrated, the fluid supply system, shown generally at1800, includes a nitrogen gas supply1805, an IPA supply1810, an IPA vaporizer1815, a DI water supply1820, optional heating elements1825, optional flowmeters1830, optional flow regulators/temperature sensors1835, and valve mechanism1840. All of the various components of the system1800may be under the control of a controller unit845having the appropriate software programming.

In operation of the rinser/dryer, the valve mechanism1840is connected to supply DI water from supply1820to both the upper and lower inlets of the rinser/dryer chamber. As the water is supplied to the chamber, the wafer is spun at, for example, a rate of 200 RPM. This causes the water to flow across each surface of the wafer under the action of centripetal acceleration. Once a sufficient amount of water has been supplied to the chamber to rinse the wafer surfaces, valve mechanism1840is operated to provide a drying fluid, preferably comprised of nitrogen and IPA vapor, to both the upper and lower inlets of the rinser/dryer chamber. Valve mechanism1840is preferably operated so that the front of the drying fluid immediately follows the trailing end of the DI water. As the drying fluid enters the chamber, centripetal acceleration resulting from the spinning of the wafer drives the drying fluid across the wafer surface and follows a meniscus across the wafer surface formed by the DI water. The IPA vapor assists in providing a drying of the surface of the wafer at the edge of the meniscus. Drying of the wafer may be further enhanced by heating the DI water and/or the nitrogen/IPA vapor using heating elements1825. The particular temperature at which these fluids are supplied may be controlled by the controller1845. Similarly, flow regulators1835and flowmeters1830may be used by controller1845to regulate the flow of the DI water and/or the nitrogen/IPA vapor to the rinser/dryer chamber.

With some modifications, the foregoing reactor designs may be adapted to execute several unique processes in which contact between the microelectronic workpiece and one or more processing fluids is controlled and confined to selected areas of the workpiece. One embodiment of such a reactor design is shown inFIGS. 21-25.

With reference toFIGS. 21-25, there is shown a reactor2100for processing a microelectronic workpiece, such as a silicon wafer10having an upper side12, a lower side14, and an outer, circular perimeter16, in a micro-environment. For certain applications, the upper side12is the front side, which may be otherwise called the device side, and the lower side14is the back side, which may be otherwise called the non-device side. However, for other applications, the silicon wafer10is inverted.

Generally, except as disclosed herein, the reactor2100is similar to the reactors illustrated and described above. However, as illustrated in the drawings and described herein, the reactor2100is improved to be more versatile in executing selected microelectronic fabrication processes.

The reactor2100has an upper chamber member that includes an upper chamber wall2120and a lower chamber member that includes a lower chamber wall2140. These walls2120,2140, are arranged to open so as to permit a wafer10to be loaded into the reactor100for processing, by a loading and unloading mechanism (not shown) that, for example, may be in the form of a robot having an end effector. These walls2120,2140, are arranged to close so as to define a capsule2160supporting a wafer10in a processing position, between these walls2120,2140.

The reactor2100, which defines a rotation axis A, has a head2200containing a rotor2210, which mounts the upper chamber wall2120, and mounting a motor2220for rotating the rotor2210and the upper and lower chamber walls2120,2140, when closed, around the axis A, conjointly with a wafer10supported in the processing position. The motor2220is arranged to drive a sleeve2222, which is supported radially in the head2200, by rolling-element bearings2224. The head2200is arranged to be raised for opening these walls2120,2140, and to be lowered for closing these walls2120,2140.

The upper chamber wall2120has an inlet2122for processing fluids, which may be liquid, vaporous, or gaseous, and the lower chamber wall2140has an inlet2142for such fluids, which for a given application may be similar fluids or different fluids. The head2200mounts an upper nozzle2210, which extends axially through the sleeve2222so as not to interfere with the rotation of the sleeve2222. The upper nozzle2210directs streams of processing fluids downwardly through the inlet2122of the upper chamber wall2120.

The upper chamber wall2120includes an array of similar outlets2124, which are spaced similarly at uniform angular spacings around the vertical axis A. In the disclosed embodiment, thirty-six such outlets2124are employed. Each outlet2124is spaced outwardly from the vertical axis A by a comparatively larger radial distance and is spaced inwardly from the outer perimeter16of a wafer10supported in the processing position by a comparatively smaller radial distance, such as a distance of approximately 1.5 millimeters or other desired edge exclusion zone.

When the upper and lower chamber walls2120,2140, are closed, they define a micro-environment reactor2160the having an upper processing chamber2126that is defined by the upper chamber wall2120and by a first generally planar surface of the supported wafer10, and a lower processing chamber2146that is defined by the lower chamber wall2140and a second generally planar surface of the supported wafer opposite the first side. The upper and lower processing chambers2126,2146, are in fluid communication with each other in an annular region2130beyond the outer perimeter16of the supported wafer10and are sealed by an annular, compressible seal (e.g. O-ring)2132bounding a lower portion2134of the annular region2130. The seal2132allows processing fluids entering the lower inlet2142to remain under sufficient pressure to flow toward the outlets2134.

As compared to reactors of the type disclosed in the previously described embodiments, the reactor2100is particularly suitable for executing a range of unique microfabrication processes. For example, reactor2100is particularly suited to execute a process that requires complete contact of a processing fluid at a first side of a workpiece and at only a peripheral margin portion of the second side thereof. Such processes may be realized because processing fluids entering the inlet2142of the lower chamber wall2140can act on the lower side14of a supported wafer10, on the outer periphery16of the supported wafer10, and on an outer margin18of the upper side12of the supported wafer10before reaching the outlets2124, and because processing fluids entering the inlet2122of the upper chamber wall2120can act on the upper side12of the supported wafer10, except for the outer margin18of the upper side12, before reaching the outlets2124.

As a significant example of one such process, the reactor2100can be used with control of the respective pressures of processing fluids entering the respective inlets2122,2142, to carry out a process in which a processing fluid is allowed to contact a first side of the workpiece, the peripheral edge of the workpiece, and a peripheral region of the opposite side of the workpiece. Such fluid flow/contact can also be viewed as a manner of excluding a processing fluid that is applied to the opposite side from a peripheral region of that side. In accordance with one embodiment of such a process, a thin film of material is etched from the first side, peripheral edge of the workpiece, and peripheral region of the opposite side of the workpiece.

In a more specific embodiment of such a process, the process may employed in a metallization process that is used to form a microelectronic component and/or interconnect structures on a semiconductor wafer or the like. To this end, a thin film, such as the seed layer, is applied over a barrier layer on the front side and over at least a portion of the outer perimeter. After one or more intervening steps, such as electroplating of a copper layer or the like thereover, an etchant capable of etching the electroplating material, thin film material, and/or the barrier layer material is caused to flow selectively over only an outer margin of the first side while being concurrently prevented from flowing over other radial interior portions of the first side. Thus, one or more of the layers are removed from the outer margin of the first side while the layers remain intact at the portions of the first side that are disposed interior of the outer margin. If the etchant is driven over the opposite side and over the outer perimeter, as well as over the outer margin of the first side, the one or more layers are also removed from the outer perimeter of the wafer and, further, any contaminant that the etchant is capable of removing is stripped from the back side.

Based on the description of the foregoing process, it will be recognized that other layers and/or materials may be selectively etched, cleaned, deposited, protected, etc., based on selective contact of a processing fluid with the outer margin and/or opposing side of the workpiece. For example, oxide may be removed from the opposite side and outer margin of the first side of a workpiece through selective contact with an oxide etchant, such as hydrofluoric acid. Similarly, the oxide etchant may be controlled in the reactor so that it contacts all of the front side of the workpiece except for the outer margin thereby leaving the oxide at the outer margin intact. It will also be recognized that removal of the outlets2124allows the reactor2100to be used for processes in which selective outer margin inclusion or exclusion is unnecessary or otherwise undesirable.

As illustrated inFIGS. 26-29, additional structures may be incorporated with any of the foregoing reactors dependent on the particular process(es) the reactor is designed to implement and the automation, if any, that will be used along with it. In accordance with one such structural addition, the lower chamber wall140has an upper surface2144shaped so as to define an annular sump2146around the inlet2142. The sump2146is used to collect liquid byproducts and/or residual processing fluids supplied through the inlet2142. If a liquid, for example, strikes and drops from wafer10, it is conducted toward the outlet2124under the influence of centripetal acceleration as the reactor100is rotated.

Another structural addition illustrated in connection with the reactor2100relates to the lower nozzle design. As illustrated, the lower nozzle2260, which is provided beneath the inlet2142of the lower chamber wall2140, includes two or more ports2262(two shown) for directing two or more streams of processing fluids upwardly through the inlet2142. The ports2262are oriented so as to cause the directed streams to converge approximately where the directed streams reach the lower surface of the wafer10. The reactor2100also includes a purging nozzle2280, which is disposed at a side of the lower nozzle2260, for directing a stream of purging gas, such as nitrogen, across the lower nozzle2260.

Still further, the reactor2100may have a base2300, which mounts the lower nozzle2260and the purging nozzle2280and which defines a coaxial, annular plenum2320. The plenum2320has plural (e.g. four) drains2322(one shown) each of which is equipped with a pneumatically actuated, poppet valve2340for opening and closing the drain2322. These drains2322provide separate paths for conducting processing liquids of different types to appropriate systems (not shown) for storage, disposal, or recirculation.

An annular skirt2360extends around and downwardly from the upper chamber wall2120, above the plenum2320, so as to be conjointly rotatable with the upper chamber wall2140. Each outlet2124is oriented so as to direct processing fluids exiting such outlet2124through fluid passages2364against an inner surface2362of the annular skirt2360. The inner surface2362is flared outwardly and downwardly, as shown, so as to cause processing fluids reaching the inner surface2362to flow outwardly and downwardly toward the plenum2320, under the influence of centripetal acceleration when the reactor is rotated. Thus, processing fluids tend to be swept through the plenum2320, toward the drains2322.

The rotor2210has a ribbed surface2215facing and closely spaced from a smooth surface2202of the rotor2210, in an annular region204communicating with the plenum2320. When the rotor2210rotates, the ribbed surface2215tends to cause air in the annular region2204to swirl, so as to help to sweep processing fluids through the plenum2320, toward the drains2322.

The upper chamber wall2120has spacers2128that project downwardly to prevent the lifting of a supported wafer10from the processing position and from touching the upper chamber wall2120. The lower chamber wall2140has spacers2148that project upwardly for spacing a supported wafer10above the lower chamber wall140by a given distance, and posts2150projecting upwardly beyond the outer perimeter16of a supported wafer10for preventing the supported wafer10from shifting off center from the vertical axis A.

The lower chamber wall2140may mount a lifting mechanism2400for lifting a wafer10supported in the processing position to an elevated position. The lifting mechanism lifts the wafer10to the elevated position when the head2200is raised above the base2300so as to open the upper and lower chamber walls2120,2140. Lifting a supported wafer10to the elevated position facilitates its being unloaded by a loading and unloading mechanism (not shown) such as a robotic arm having an end effector.

The lifting mechanism2400includes an array of lifting levers2420. Each lifting lever2420is mounted pivotably to the lower chamber wall2140via a pivot pin2422extending from such lifting lever2420into a socket2424in the lower chamber wall2140, so as to be pivotable between an operative position and an inoperative position. Each pivoting lever2420is arranged to be engaged by the upper chamber wall2120when the upper and lower chamber walls2120,2140, are closed, whereby such pivoting lever2420is pivoted into the inoperative position. Each lifting lever2420is biased, as described below, so as to pivot into the operative position when not engaged by the upper chamber wall2120.

Thus, each lifting lever420is adapted to pivot from the operative position into the inoperative position as the upper and lower chamber walls2120,2140, are closed, and is adapted to pivot from the inoperative position into the operative position as the upper and lower chamber walls2120,2140, are opened. Each lifting lever2420mounts a pin2424, which extends beneath a wafer10supported in the processing position and lifts the supported wafer to the elevated position, when such lifting lever2420is pivoted from the inoperative position into the operative position.

The lifting levers2420may be biased by an elastic member2440(e.g. O-ring) surrounding the lower chamber wall2140and engaging the lifting levers2420, via a hook2426depending from each lifting lever2420. On each lifting lever2420, the pin2422defines an axis, relative to which the pin2424and the hook2426are opposed diametrically to the each other. The elastic member2440is maintained under comparatively higher tension when the upper and lower chamber walls2120,2140, are closed, and under comparatively lower tension when the upper and lower chamber walls2120,2140, are opened.

The upper and lower chamber walls2120,2140, may also be releasably clamped to each other when in the closed state by a latching mechanism2500. In accordance with one embodiment, the latching mechanism, the latching mechanism includes a latching ring2520that is retained by the lower chamber wall2140and that is adapted to engage a complementary shaped recess2540disposed in the upper chamber wall2120. The latching ring2520is made from a resilient spring material (e.g. polyvinylidine fluoride) with an array of inwardly stepped portions2530. Thus stepped portions2530enable the latching ring2520to deform from an undeformed condition in which the latching ring2520has a first diameter into a deformed condition in which the latching ring2520has a comparatively smaller diameter. Such deformation occurs when the stepped portions2530are subject to radial inward directed forces. Upon removal of the forces, the latching ring2520returns to the undeformed.

The latching mechanism2500further includes an array of latching cams2540, each associated with a respective one of the stepped portions2530. Each latching cam2540is adapted to apply radial forces to the respective stepped portions2530.

The latching mechanism2500further includes an actuating ring2560, which is adapted to actuating the latching cams540as the actuating ring2560is raised and lowered within a predetermined limited range of movement. In the illustrated embodiment, the actuating ring2560is adapted, when raised, to actuate the latching cams2540, and, when lowered, to deactuate the latching cams. The latching mechanism2500further includes an array of pneumatic devices2580(e.g. three such devices) which are adapted to raise and lower the actuating ring2560. When the actuating ring2560is raised, the upper and lower chamber walls2120,2140, are released from each other so that the head2200can be raised from the base2300for opening the upper and lower chamber walls2120,2140, or lowered onto the base2300for closing the upper and lower chamber walls2120,2140.

The actuating ring2560mounts upwardly projecting pins2562(one shown) that project into respective ones of multiple apertures2564in an aligning ring2570when the actuating ring2560is raised. The aligning ring2570is mounted to rotate conjointly with the lower chamber wall2140. The pins2562are withdrawn from the apertures2564and clear the aligning ring2570when the actuating ring2560is lowered. When projecting into the respective apertures2564, the pins2562align a wafer10that had been supported in the processing position so as to facilitate unloading the wafer10via a robotic system, as mentioned above.

D. Preferred Embodiments of the Processes and Solutions

The reactor illustrated and described above may be employed to practice the processes provided by this invention for treating a semiconductor wafer having a front, device side, a back, non-device side, and an outer perimeter (i.e., the peripheral edge), so as to remove a bulk metal or oxide thin film, such as a copper film, or metal ion or oxide contamination from selected surfaces. The wafer is suitably placed into the reactor with its back side being the lower side (or in the opposing configuration for a differently configured reactor). An etchant capable of removing the copper is used as the processing fluid. The etchant is delivered by a pump to the lower chamber. An inert gas purge is preferably used as the processing fluid that is concurrently supplied and enters the upper chamber. The supply of an inert gas purge or an aqueous rinse, such as deionized water, is preferred to insure no vapor or etchant intrusion onto the majority of the first side (excluding the edge perimeter). However, the supply of fluid to the front side is not necessary, particularly for front sides coated with an exterior layer that is not vulnerable to etchant vapor, or from which a partial amount of film can be etched without a detrimental effect to the underlying layers. The etchant is caused to flow over the back side, over an outer perimeter of the silicon wafer, and over an outer margin (the exclusion zone) of the front side, but is prevented from flowing over the remainder of the front side except for the outer margin. After the etchant removes the thin film, any residual etchant is rinsed away, as with deionized water.

The processing fluid can suitably be a mixture of an acid and an oxidizing agent.

If the thin film is a metal film, such as a copper film, a preferred etchant is a mixture of hydrofluoric acid and hydrogen peroxide, as an oxidizing agent. Preferably the solution includes 0.4 to 0.6 volume % HF, most preferably 0.5% HF, and 5 to 15% H2O2, most preferably 10 volume % H2O2, with the balance being deionized water. An alternative reagent is approximately 10% to 25% sulfuric acid with 5% to 15% hydrogen peroxide. An HF/H2O2solution is preferred for stripping metal from wafers treated with a silicon nitride protective layer, which HF/H2O2and H2SO4/H2O2solutions are useful in stripping metal contamination from thermal oxide (silicon oxide) protective layers. Other concentrations of sulfuric acid from approximately 5% to approximately 98%, along with approximately 0% to 20% of an oxidizing agent, can be instead used to remove a metal film, such as a copper film.

The processing fluid can also be a mixture of sulfuric acid and ammonium persulfate. Other alternative enchants that can be instead used to remove a metal film, such as a copper film, include mixtures of hydrofluoric acid and a surfactant, mixtures of hydrofluoric and hydrochloric acids, mixtures of nitric and hydrofluoric acids, and EKC 5400, which is a proprietary chemical available commercially from EKC of Hayward, Calif. Mixtures of HF and HCL are suitably supplied as 0.4 to 0.6% HF and 5% to 15% HCL in deionized water. Mixtures of HNO3and HF are suitably supplied as 0.4 to 0.6% HF and 5% to 15% HCL in deionized water.

In place of hydrogen peroxide in the above etchant solutions, other oxidizers capable of etching metal films may be utilized. Dissolved ozone (O3) has been found suitable for use in the above solutions in place of hydrogen peroxide, and is preferred due to its limited duration of solubility in water, such that after treatment the ozone breaks down and leaves a less hazardous waste fluid. Thus for example a suitable etchant solution for removal of metal films, such as copper films, includes 0.4 to 0.6% HF, most preferably 0.5% HF, and 10 parts per million ozone to an ozone saturated solution, preferably 20 parts per million ozone, in deionized water. When utilizing ozone as an oxidizer, apparatus used in carrying into the invention suitably include a mixing chamber into which ozone is introduced to the solution, such as through sparging ozone gas through the solution. In addition to HF/Ozone solutions, ozone may also be included as the oxidizer, in place of H2O2, in the other solutions described above, such as the sulfuric acid solutions.

The exact etchant solution to be utilized will be selected, based on the disclosure contained herein, for use with a particular film. Turning to a specific application of the processes of the present invention, treatment of the back side and bevel edge of a wafer for removal of copper contamination will be described in further detail. A preferred process sequence for a semiconductor wafer includes initially laying down a PVD or CVD barrier/adhesion layer onto the acidic wafer, followed by application of a seed layer of a metal onto the barrier layer to support subsequent deposition. The wafer is then subjected to electrochemical deposition to deposit the desired conductive film of copper over the front (device) side of the wafer, possibly excluding the outer perimeter of the substrate from the deposition, or potentially depositing copper to the edge and over the bevel of the wafer.

The wafer is then placed into a reaction chamber to perform a controlled etch of the back side, bevel edge, end of the seed layer metal and/or electroplated metal on the front side within a controlled distance from the perimeter edge of the substrate, to define a distinct exclusion zone from which copper has been removed by the etchant. Alternately, etchant may be supplied to remove metal from only the back side and bevel edge of the wafer, or to just remove metal contaminant from the back side of the wafer. The various process configurations will be described in terms of a process for exposing the back side, bevel edge and controlled perimeter edge exclusion zone to etchant, but it should be understood that any of these variations are possible.

After placement of the wafer in the etchant chamber, the chamber spins until it reaches a desired processing rotational speed, at which point any residual plating solution is rinsed from the front side of the wafer using deionized water. After rinsing, an inert gas stream is preferably (but not necessarily) supplied to the front (device) side of the wafer, while an etchant solution is delivered to the back side of the wafer. The etchant solution, such as use of the HF/H2O2or H2SO4/H2O2solutions disclosed above, is delivered at a concentration level and for a sufficient period of time to achieve the desired level of removal of copper ions from the back side and bevel, as well as the front side exclusion zone. After cleaning of the back side and etching of the bevel and front side exclusion zone in this fashion, the wafer is rinsed with deionized water on both sides, spun to remove liquid, and then dried with inert gas such as heated nitrogen. The following tables I and II illustrate suitable sets of process steps to achieve this back side cleaning and bevel etching:

TABLE IISuitable Cu Backside Clean and Bevel Etch RecipeStepDescriptionTimeSupply1Etch/process0:20-0:60Chemical to one or both sides; N2alternate2Rinse0:10-0:30DI rinse to front and back3Dry0:30-0:60N2Purge to front and back; dry

The above sequence times and sequence steps are provided by way of example only, and are not intended to limit the invention. Other sequence arrangements, such as single rather than multiple rinses, and rinsing or etching for different periods of time, are also within the scope of the present invention.

Use of a diluted sulfuric acid and peroxide solution, including approximately 10 parts H2SO4to thirty parts H202in deionized water, for an etchant exposure of approximately 30 seconds, results in removal of copper films of less than approximately 1.5 microns and achieves a back side clean of less than or equal to 5-10 copper atoms/cm2.FIG. 30provides a scanning electron microscope photo of the exclusion zone formed on the front side of a wafer treated in accordance with this process, yielding a clean etch exclusion zone (as well as clean bevel edge and back side (not shown)), and a distinct demarcation between the exclusion zone and the substantially unaffected copper film on the remainder of the front side.

While the specific example above uses a dilute sulfuric acid and hydrogen peroxide solution, as noted above other solutions are suitably used.FIG. 31provides results for use of various solutions on test wafers prepared by treating the polished side of bare silicon wafers with an acid copper solution. The acid copper solution was then rinsed from the wafer, and then the back side was cleaned and the edge bevel etched in accordance with the processes and apparatus of the present invention. Post cleaning analysis was done using a TXRF detector, with detection limits being roughly 7-9E10atoms per centimeter square.FIG. 31provides comparative post-processing copper residues for an untreated wafer (“control”), for the acid-copper treated wafer (“uncleaned ECD+SRD”), and various etchant solutions. Specimens showing a post cleaning copper contamination level of less than 1E11atoms were judged to be suitable. Specifically, cleaning with a hydrogen fluoride/hydrogen peroxide solution was found to yield cleaning at a level equal to that of an uncontaminated control specimen, while cleaning with a dilute sulfuric acid etchant, sulfuric acid/hydrochloric acid solutions, and DSPM (dilute sulfuric acid/hydrogen peroxide) solutions were also found to yield suitable results. The exact solution utilized will be selected in accordance with compatibility for other films on the substrate and other process solutions.

The above examples illustrate the use of the processes of the present invention for cleaning copper contamination from the back side of a semiconductor wafer, and for etching copper from the bevel edge and front side exclusion zones. However, other processes are also suitably carried out, and involve common steps of rinsing the wafer to clear it of any residual chemistry from prior processing steps if necessary, followed by etching the wafer with a suitable etchant solution, followed by post etch rinsing such as with deionized water, spinning to remove solution, and then dying such as with heated inert gas.

One such further example entails the removal of trace amounts of cobalt from the back side of a wafer, and unreactive cobalt from the front side of the wafer, after cobalt processing. Specifically, after a wafer has been treated with cobalt to form contact points on the front device side, such as by sputtering cobalt (physical vapor deposition) onto the front side, the front side of the wafer includes both cobalt suicides where the cobalt has contacted bare silicon, and unreacted cobalt where the cobalt has contacted an oxide coating. Processes of the present invention may be utilized to remove this unreacted cobalt from the front side, as well as to remove any cobalt contaminant from the back side (and potentially the bevel edge). In this instance, both front and back side are preferably exposed to treatment solutions.

The preferred cobalt etching process entails first rinsing the front and back sides of the wafer. A dilute sulfuric acid/hydrogen peroxide solution, as disclosed above, is then sprayed or otherwise applied onto both sides of the wafer, concurrently, to remove unreacted cobalt. A suitable dilution for the solution is one part sulfuric acid to 10-20 parts hydrogen peroxide. After exposing both sides to this dilute sulfuric acid solution for a suitable period of time to achieve a predetermined level of cobalt removal, both sides are exposed to a further deionized water rinse. Thereafter, the back side only of the wafer is exposed to a hydrofluoric acid solution (such as 200 parts deionized water to one part HF), to remove a portion of the protective cap of oxide layer present on the back side of the wafer, which typically has an amount of cobalt diffused thereinto. The entire oxide layer is not removed, but just a predetermined amount of the oxide layer as required to remove the cobalt contamination. The front side of the wafer is preferably supplied with an inert nitrogen gas concurrent to back side treatment with hydrofluoric acid. Both sides of the wafer are then rinsed and dried. Treatment requirements for the present invention will yield a removal of cobalt with less than 1E10as measured with total x-ray fluorescent detection. While the supply of nitrogen to the front side has been described and is preferred in order to exclude hydrofluoric acid vapor from the front side, it is not strictly necessary. Similarly, wafers with films of Pt, Pd, BST, SBT, Ru, and Ir can be processed using suitable etchants.

A further example of a process in accordance with the present invention is the cleaning of the back side of a semiconductor wafer prior to photo lithographic treatment. If particulate contamination is present on the back side of a semiconductor wafer, high spots, referred to as hotspots, can be formed on the front side of the wafer during further lithographic treatment due to the wafer sitting at an uneven degree of tilt. Prior to photo resist application, the wafer can be treated in accordance with the present invention to remove particulates and other contaminants from the backside. This process suitably is carried out by rinsing both sides of the wafer, followed by exposure of the back side only to a suitable etchant solution such as hydrofluoric acid/ozone, hydrofluoric acid/hydrogen peroxide, sulfuric acid/hydrogen peroxide or hydrochloric acid/hydrogen peroxide, as previously described above. Optionally, the front side of the wafer may be supplied with nitrogen gas at the same time as cleaning of the back side. The present invention insures that the front side is not contaminated with the cleaning solutions during the cleaning of the back side. A still further example of a process for use in the present invention is removal of dry etch residue material after patterning of a wafer. Specifically, when the front side of a wafer has been etched with a dry plasma etch, a residue consisting of materials being etched or removed from the substrate surface, gas etch residue or metallization and dielectric layer residue remains on the front side of a wafer. Conventionally, this residue is removed using a solvent to which the wafer must be exposed for a long period of time, often in an excess of 60 minutes, at elevated temperatures. In accordance with the present invention, wafers may be suitably treated at ambient temperatures, e.g., 23° C., for relatively short process times of approximately one minute in length or less, using commercially available dry etch residue removal solutions such as EKC 640 and Ashland NE 89, which are believed to be hydrofluoric acid or ammonium fluoride based solutions. EKC 640 is available from EKC Corporation, while Ashland NE 89 as available from the Ashland Corporation. The process entails rinsing and then exposing the front side of the wafer to the solvent, and then rinsing and drying both sides. Typically it is not necessary to treat the back side, which has not been contaminated during the dry etching process.

It is noted that the above processes for cleaning the back side to remove particulate contamination prior to photo lithography, and the front side to remove dry etch residue, may be carried out concurrently in a reactor in accordance with the present invention.

Other processes are also included with the scope of the present invention, such as etching oxides on one or both sides of the wafer, concurrently or separately.

The present invention reduces the size of the annular exclusion zone on the front side of the wafer, which region is not available for fabricating interconnect structures and/or metallized components (seeFIG. 2). All other dimensions being alike, the present invention, when used for bevel edge and front side exclusion zone cleaning, increases the surface area of a wafer available for fabricating interconnect structures and/or metallic components. It follows that this invention enables a greater yield of microelectronic devices from a silicon wafer of a given size. Advantageously, the process provided by this invention not only removes a thin film, such as a copper film, but also removes any contaminant, such as any copper or other metal, that the reagent is capable of solvating from the back side of the silicon wafer.

The thin film removed by the process of the present invention could also be substantially comprised of silicon nitride, silicone oxide or polysilicon.

The present invention has been illustrated with respect to a wafer. However, it will be recognized that the present invention has a wider range of applicability. By way of example, the present invention is applicable in the processing of disks and heads, flat panel displays, microelectronic masks, and other devices requiring effective and controlled wet processing. While the preferred embodiment of the invention has been illustrated and described, it will be appreciated that various changes can be made therein without departing from the spirit and scope of the invention.