US20040188257A1

US20040188257A1 - Methods for processing micro-feature workpieces, patterned structures on micro-feature workpieces, and integrated tools for processing micro-feature workpieces

Info

Publication number: US20040188257A1
Application number: US10/760,713
Authority: US
Inventors: John Klocke; Thomas Ritzdorf
Original assignee: Semitool Inc
Current assignee: Semitool Inc
Priority date: 2001-08-31
Filing date: 2004-01-20
Publication date: 2004-09-30

Abstract

Method and apparatus for processing a micro-feature workpiece having a workpiece having a first side, a second side, a plurality of micro-devices including submicron features integrated in and/or on the workpiece, and a deep depression or other large three-dimensional feature in either the first side and/or the second side. The method can include forming a thin conductive seed layer on the workpiece that conforms to the depression, and depositing a negative resist layer onto the seed layer. The negative resist layer, for example, can be a highly conformal and uniform layer of negative electrophoretic resist that is deposited onto the seed layer by contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath. After depositing the negative resist layer, the method includes removing a portion of the negative resist layer to uncover a deposition area of the seed layer within the depression. The method then includes the additive technique of electrochemically depositing a material onto the deposition area of the seed layer within the depression without covering the entire workpiece with the material.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is a continuation-in-part of U.S. patent application Ser. No. 10/234,637, entitled “APPARATUS and METHOD for DEPOSITION of an ELECTROPHORETIC EMULSION,” filed on Sep. 3, 2002, which claims priority to U.S. Patent Application No. 60/316,461, filed on Aug. 31, 2001, both of which are incorporated by reference herein.[0001]

TECHNICAL FIELD

The present invention is directed to methods for processing micro-feature workpieces having a plurality of micro-devices that are integrated in and/or on the workpiece. The micro-devices can include submicron features. Additional aspects of the present invention include micro-feature workpieces that have patterned structures, and integrated tools that carry out methods in accordance with the invention for manufacturing micro-feature workpieces.

BACKGROUND

In the fabrication of microelectronic devices and micromechanical devices, several layers of materials are typically deposited and worked on a single substrate to produce a large number of individual devices. For example, layers of photoresist (resist) are deposited and worked (i.e., patterned, developed, etched, and so forth) to form patterns of features in and/or on the substrate. The patterns are then used to form various structures.

The microelectronics industry continually seeks to reduce manufacturing costs and improve the performance of the microelectronic devices. The manufacturing costs can be reduced, in part, by reducing the volume of materials that are consumed in fabricating the individual components. For example, a manufacturer can achieve significant savings by reducing the amount of gold, resist, or other materials that are used in typical fabrication processes. Additionally, manufacturers seek to increase the density of features so that more components and devices can be fabricated on a single wafer. Therefore, microelectronic manufacturers continually seek more efficient processes that reduce the manufacturing costs and improve the performance of their products.

One aspect of manufacturing microelectronic devices that can be problematic is forming conductive features in through-holes, in deep depressions, or on other three-dimensional structures. Several products, such as telecommunications products, have backside vias that extend completely through the workpiece or other deep depressions that have large step heights. Such three-dimensional structures cause several problems in manufacturing processes including step coverage and inefficient use of materials. Referring to FIGS. 1A-1E, for example, a backside via is currently formed using a subtractive process including the following steps:

(A) Forming a through-

hole

130 completely through a substrate 110 of a workpiece 100 (FIG. 1A).

(B) Depositing a

seed layer

140 on the substrate 110 and into the through hole 130 (FIG. 1A).

(C) Plating the

entire substrate

110 with a layer of gold 150 or other material (FIG. 1A).

(D) Depositing a layer of resist 160 over the substrate 110 using a spin-on or dry film technique (FIG. 1B).

(E) Patterning the

resist

160 to leave masked regions 162 over the through holes 130 and to expose the gold layer 150 outside of the through holes 130 (FIG. 1C).

(F) Etching the exposed portions of the

gold layer

150 and the seed layer 140 outside of the through holes 130 (FIG. 1D).

(G) Removing the

masks

162 to expose gold contacts 170 within the through holes 130 (FIG. 1E).

The subtractive process shown in FIGS. 1A-1E is inefficient and difficult to perform. One problem with this subtractive process is that it is difficult and expensive to deposit and work the layer of resist. For example, spin-on techniques do not provide good step coverage in deep depressions or over other features with large step heights because the resist may not cover the upper regions on the sidewalls (see FIGS. 1B-1D). This can cause defects in subsequent manufacturing. To provide adequate step coverage using spin-on techniques, a significant amount of resist is deposited such that the through holes are substantially filled with resist but the top surface is covered by only a thin layer. Depositing such a non-uniform layer of resist, however, is relatively expensive because (a) a significant amount of resist is wasted as it flows off the wafer, and (b) the non-uniform layer of resist requires longer exposure periods and stripping cycles that take more time and use more consumable materials. Therefore, conventional subtractive processes that use spin-on techniques for depositing the layer of resist are expensive and make it more difficult to provide consistent exposure and stripping processes.

Another problem of conventional subtractive processes for forming conductive features in backside vias or other deep depressions is that a significant amount of gold or other relatively expensive conductive material is wasted. Conventional subtractive processes use a positive photoresist and expose the areas outside of the deep depressions. The positive photoresist is exposed in the areas outside of the deep depressions because (a) it is difficult to adequately focus the exposure radiation in the deep depressions, and (b) the layer of photoresist is much more uniform on top of the substrate than within the depressions. As a result, the portion of the gold or other conductive material outside of the vias is removed from the workpiece to form the conductive features.

A significant portion of the gold is thus wasted in the etching process because only a fraction of it remains on the wafer. Therefore, a significant amount of the precious metals or other conductive materials that are used to form contacts in deep depressions are wasted in conventional subtractive processes.

SUMMARY

The present invention is directed toward forming several types of features on or in micro-feature workpieces, and unique processes for depositing a uniformly conformal layer of negative resist over large step heights. Several embodiments of the invention enable additive processes for forming features that reduce costs, increase throughout, and enhance reliability.

One aspect of the present invention is forming a conformal, uniform layer of negative resist on a workpiece with large three-dimensional structures (i.e., large step heights) and then removing the portion of the negative resist within the large three-dimensional structures. A conductive feature or other features can then be formed by adding material to the wafer within the three-dimensional structures instead of over the entire wafer so that extensive etching is not necessary to remove excess material from the wafer. This reduces the consumption of precious metals or other materials. Additionally, forming a conformal, uniform layer of resist reduces the quantity of resist required to adequately cover large three-dimensional features. This provides more consistent exposure, development, and stripping processes to reduce defects, and results in faster process times to enhance the throughput and cost-effectiveness for manufacturing the features.

One embodiment of a method for processing a micro-feature workpiece involves a workpiece having a first side, a second side, a plurality of micro-devices including submicron features integrated in and/or on the workpiece, and a deep depression or other large three-dimensional feature in either the first side and/or the second side. The method can include forming a thin conductive seed layer on the workpiece that conforms to the depression, and depositing a negative resist layer onto the seed layer. The negative resist layer, for example, can be a highly conformal and uniform layer of negative electrophoretic resist. The negative resist layer can be deposited onto the seed layer by contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath. After depositing the negative resist layer, the method includes exposing portions of the negative resist layer outside of the depression to a selected energy. This creates an exposed region of the negative resist layer outside of the depression and an unexposed region of the negative resist layer in the depression. The unexposed region of the negative resist layer in the depression is removed to uncover a deposition area of the seed layer within the depression. The method then includes the additive technique of electrochemically depositing a material onto the deposition area of the seed layer within the depression without covering the entire workpiece with the material. The exposed regions of. the negative resist layer outside of the depression can then be removed to expose the portions of the seed layer outside of the depression, and then the seed layer can be quickly etched to isolate the electrochemically deposited material in the depression.

The methods for processing a micro-feature workpiece in accordance with the invention define an additive process in which a precious metal or other material is not wasted because it is deposited only in the area of the feature instead of across the entire surface of the workpiece. Moreover, electrochemically depositing a layer of negative electrophoretic resist enables this additive process because it provides conformal, uniform coverage over large three-dimensional features. This reduces the amount of resist that is used compared to spin-on techniques because the thickness of the resist layer can be tightly controlled using electrochemical deposition of electrophoretic resist. The conformal layer of resist also reduces defects because it can be patterned using consistent exposure, development, and stripping processes. Therefore, several aspects of embodiments for processing a micro-feature workpiece in accordance with the invention reduce the cost of materials, reduce the defects, and enhance the throughput for forming features in and/or on large three-dimensional structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1E are cross-sectional views illustrating a portion of a micro-feature workpiece at various stages of a subtractive method for forming a conductive feature in a deep depression in accordance with the prior art. [0020]
FIGS. 2A-2F are cross-sectional views of a micro-feature workpiece at various stages of an additive method for forming features in deep depressions in accordance with an embodiment of the invention. [0021]
FIG. 3 is an isometric view of one embodiment of an automated processing tool for processing a micro-feature workpiece in accordance with the invention. [0022]
FIG. 4 is a cross-sectional view of one embodiment of a processing reactor that may be used in an automated processing tool to deposit a conformal layer of negative electrophoretic resist onto a seed layer in accordance with an embodiment of the invention. [0023]
FIG. 5 is a flow diagram of a control sequence for processing a micro-feature workpiece in accordance with an embodiment of the invention. [0024]
FIGS. 6-8 are top plan schematic views illustrating additional embodiments of integrated tools in accordance with other embodiments of the invention.[0025]

DETAILED DESCRIPTION

As used herein, the terms “micro-feature workpiece” or “workpiece” refer to substrates on or in which microelectronic devices are integrally formed, such as microelectronic circuits or components, thin-film recording heads, data storage elements, and similar devices. Micromachines or micromechanical devices are included within this definition because the manufacturing processes used to make them are the same as or similar to the manufacturing processes used in the fabrication of integrated circuits. The substrates can be semiconductive pieces (e.g., silicon wafers), nonconductive pieces (e.g., various ceramic substrates), or conductive pieces. Typical workpieces are relatively thin and disk-shaped, although not necessarily circular, as ordinarily understood in the microfabrication industry. The work-pieces can also be mounted to carrier substrates that are typically relatively thin and disk shaped, although not necessarily circular. [0026]
Several embodiments of micro-feature workpieces and methods for processing micro-feature workpieces are described in the context of forming backside vias or other structures in deep depressions on a workpiece. The present invention, however, is not limited to forming such structures. The present invention is applicable to forming structures with a conformal layer of photoresist over any large three-dimensional structure on a workpiece. For example, other structures can include raised features or depressions such as streets, backside patterns, and other features used in MEMS, communications devices, optics and advanced packaging applications. [0027]
Additionally, several embodiments are described in the context of electrochemically depositing an electrophoretic photoresist (EPR) onto a workpiece. Yet, the present invention is not limited to electrophoretic deposition of EPR. It may be possible to deposit the resist using other methods, such as spin-on deposition or spray coating in some embodiments, or perhaps electrochemical processes can be used to deposit suitable electrophoretic emulsions (EPEs) other than EPR emulsions. For example, other materials that can be contained in an emulsion and deposited by electrophoresis include phosphor materials for use in high resolution flat panel display devices and various selectively depositable dielectric materials. [0028]
A. Forming Micro-Features in or on Large Three-Dimensional Structures [0029]
FIGS. 2A-2F illustrate a [0030] micro-feature workpiece 200 at various stages of a method in accordance with one embodiment of the invention. The method disclosed in FIGS. 2A-2F, more specifically, is directed toward manufacturing backside vias or other features in deep depressions. As explained above, however, the invention is not limited to such structures and can be applied in the formation of other features on and/or in large three-dimensional structures.
Referring to FIG. 2A, the [0031] workpiece 200 includes a substrate 210 and a plurality of micro-devices 220 that are integrally formed on and/or in the substrate 210. The substrate 210, for example, can be a semiconductor substrate, a nonconductive substrate, or any other type of substrate that is suitable for manufacturing microelectronic devices, micromechanical devices, or other types of micro-devices 220. In many applications, the micro-devices 220 are formed integrally on and/or in the substrate 210, and the micro-devices 220 can have features as small as approximately 0.05 microns to 10 microns. The substrate 210 can include a plurality of deep depressions, such as through holes 230 or trenches 240. The substrate 210 can also include other types of large three-dimensional structures such as ridges or studs that have step heights from approximately 10-500 microns.
In the embodiment shown in FIG. 2A, the [0032] workpiece 200 further includes a seed layer 250 deposited on the substrate 210 and a negative resist layer 260 deposited on the seed layer 250. The material of the seed layer 250 is selected according to the type of material that is to be electrochemically deposited onto the workpiece 200. For example, the seed layer 250 can be copper, gold, or other suitable materials. The seed layer 250 can be deposited using chemical -vapor deposition, physical vapor deposition, atomic layer deposition, electroless plating, or other suitable methods. The negative resist layer 260 can be deposited using an electrochemical deposition process in which the substrate 210 contacts a bath of negative electrophoretic resist while an electrical field is present between the seed layer 250 and another electrode in the bath. Suitable processes for electrochemically depositing the negative resist layer 260 are described in more detail below with reference to FIGS. 3-8.
FIG. 2B illustrates the [0033] workpiece 200 at another stage of the method in which portions of the negative resist layer have been exposed to a selected energy “R” or otherwise irradiated to form a patterned resist layer. In one embodiment, the portions of the negative resist layer 260 on the top surface of the substrate 210 outside of the depressions 230/240 are exposed to the selected energy, while the portions of the negative resist in the depressions 230/240 are not exposed to the energy. The negative resist layer 260 accordingly has exposed regions 262 outside of the depressions 230/240 and unexposed regions 264 in the depressions 230/240. By exposing only the highly uniform, conformal areas of the negative resist layer 260 on top of the substrate 210 instead of the areas in the depressions 230/240, it is possible to use consistent focusing and exposure times. It will be appreciated that this is particularly beneficial because it becomes more difficult to focus the selected energy accurately throughout the depths of the deep depressions 230/240, or requires less “depth of field from the exposure system.
FIG. 2C illustrates the [0034] workpiece 200 at a subsequent stage of the method in which the unexposed regions 264 of the negative resist layer 260 have been removed. The exposed regions 262 of the negative resist layer 260 become less soluble in a selected developing solution such that the unexposed regions 264 of the negative resist layer 260 can be preferentially removed relative to the exposed regions 262. Removing the unexposed regions 264 of the negative resist layer 260 uncovers deposition areas 252 on the seed layer 250 in the depressions 230/240. The deposition areas 252 are surfaces upon which a conductive material can be plated using an electrochemical deposition process.
FIG. 2D illustrates the [0035] micro-feature workpiece 200 at a subsequent stage in the method after individual features 270 have been electrochemically deposited onto the deposition areas 252. In one embodiment, the features 270 can be conductive vias formed from copper, gold, or other suitable materials that are electrochemically deposited onto the deposition areas 252 by either electroless plating techniques or electroplating techniques. For example, an electroplating procedure for depositing gold onto the deposition areas 252 includes contacting the deposition areas 252 with a plating solution while establishing an electrical field between another electrode in the plating solution and the deposition areas 252. Suitable processing stations and workpiece holders for electrochemical deposition processes are described in U.S. application Ser. Nos. 09/804,696; 09/804,697; 09/872,151; 09/875,365; 09/386,558; and 10/234,442, all of which are herein incorporated by reference.
FIGS. 2E and 2F illustrate the [0036] workpiece 200 in the final stages for forming micro-features on the workpiece 200. Referring to FIG. 2E, the exposed regions 262 of the negative resist have been removed from the workpiece 200 to expose portions of the seed layer 250 on the top surface of the substrate 210. As shown in FIG. 2F, the exposed portions of the seed layer 250 on top of the substrate 210 have been removed using a suitable etching procedure. The process shown in FIGS. 2A-2F accordingly forms discrete contacts in and/or on large three-dimensional structures such as through holes 230 or deep trenches 240 in a manner that provides several advantages compared to the conventional subtractive process described above with respect to FIGS. 1A-1E.
One advantage of several embodiments of methods in accordance with the invention is that they are less susceptible to defects than the subtractive process shown above in FIG. 1A-1E. The highly uniform, conformal layer of negative electrophoretic resist [0037] 260 is less susceptible to having defects than a resist layer formed using spin-on or other techniques. For example, the upper regions of the sidewalls are less likely to be exposed in applications that use a conformal electrophoretic resist deposited using electrochemical techniques compared to the nonconformal layers that are deposited using spin-on techniques. Therefore, one advantage of embodiments of methods in accordance with FIGS. 2A-2F is that they are expected to provide better quality devices.
Another advantage of several embodiments of the methods shown in FIGS. 2A-2F is that they efficiently use the resist, electrochemically deposited conductive material, and other consumable materials. The additive processes shown above in FIGS. 2A-2F only use enough gold to deposit a thin seed layer and fill the depressions where the gold will remain on the workpiece, but the subtractive process shown in FIGS. 1A-1E covers the entire workpiece with a relatively thick layer of gold and then etches the unwanted portions of the gold layer. The additive processes shown in FIGS. 2A-2F accordingly use significantly less gold than the subtractive process shown in FIGS. 1A-1E. Moreover, because the negative electrophoretic resist [0038] layer 260 is formed using electrochemical deposition, the processes shown in FIGS. 2A-2F also use less resist than the subtractive processes. The conformal layer of resist 260 also requires less developing fluid and washing fluid because it has a uniform thickness in the depressions 230-240. Therefore, several embodiments of methods described above with reference to FIGS. 2A-2F efficiently use the materials in a manner that reduces the material cost of forming features.
Several embodiments of methods in accordance with the invention also enhance the throughput of processing workpieces. For example, consistent and efficient processes for exposing, developing, and washing the resist [0039] layer 260 can be developed because it is a highly conformal, uniform layer. This allows manufacturers to optimize the processes for working the negative resist layer so that they can shorten the cycle times for these processes. Therefore, several embodiments of methods in accordance with the invention are expected to enhance the throughput of manufacturing micro-features on workpieces.
B. Automated Micro-Feature Processing Tools [0040]
The additive methods for forming features described in FIGS. 2A-2F can be executed in one or more automated processing tools. The following description of automated processing tools provides several examples of methods and systems for forming the conformal layer of resist and other layers on the workpiece. The automated processing tools can be integrated with additional microfabrication processing tools to form a complete microfabrication processing system. For example, it is well within the scope of the present invention to have different configurations of automated processing tools that include several different types of processing stations, such as an automated EPE station, an exposure station, a chemical etching station, and/or a metal depositing station. [0041]
As explained in more detail below, the microelectronic workpieces can be transferred between processing stations manually or by automatic robotic handling equipment. [0042]
FIG. 3 is an isometric view of an automated [0043] microelectronic processing tool 310 having an EPE deposition station 311 for depositing EPR or other electrophoretic materials. The processing tool 310 may include a cabinet 312 having an interior region 313 that is at least partially isolated from an exterior region 314 (e.g., a clean room). The cabinet 312 may be an enclosed structure including a plurality of apertures 315 (only one shown in FIG. 3) through which microelectronic workpieces 316 contained in cassettes 317 can move to or from load/unload station 318. In other embodiments, the cabinet can be open, such as the layouts and tool platforms shown in U.S. application Ser. Nos. 10/080,914 and 10/080,915, which are herein incorporated by reference.
The embodiments of the [0044] tool 310 shown in FIG. 3 include one or more EPE deposition stations 311, one or more fluid processing stations 324, a workpiece handling system 326, and a photoresist baking station 325. The EPE deposition stations 311 may also include an in-situ rinse assembly or other ancillary in-situ process. For example, after a deposition cycle, the in-situ rinse may be used to rinse the workpiece at the EPE station 311 before it is transferred to another station. In this way, cross-contamination with other reactors is reduced and the footprint of the processing tool is more efficient. Further, the in-situ rinse may be used to clean the electrodes and/or any seals that contact the workpiece during deposition to remove any buildup of material on the electrodes and/or seals. This in-situ cleaning process may involve cleaning only the electrodes without having a workpiece loaded in the EPE station 311.
The [0045] fluid processing stations 324 may execute one or more different process sequences, such as pre-cleaning and/or pre-wetting the workpiece before EPR deposition, cleaning the workpiece after EPR deposition, baking the EPR coating, developing the EPR coating following exposure, depositing metallization on the workpiece, enhancing the seed layer prior to either EPR deposition or metallization deposition, and several other processes.
The particular embodiment of the processing tool shown in FIG. 3 is a “linear” tool in which the processing stations are aligned in a generally linear fashion on one or both sides of the [0046] workpiece handling system 326. In this type of system, the workpiece handling system 326 includes a linear track 328 and one or more robotic transfer mechanisms 330 that travel along the linear track 328. In the particular embodiment shown in FIG. 3, a first set of processing stations is arranged in a generally linear manner along a first row R₁-R₁and a second set of processing stations is arranged in a generally linear manner along a second row R₂-R₂. The linear track 328 extends between the first and second rows of the processing stations so that the robot unit 330 can access one or more of the processing stations along the track 328 to load and/or unload workpieces.
The [0047] workpiece handling system 326, as well as the actuatable components of the processing stations 311 and 324, are in communication with a control unit 346. The control unit 346 can implement software programming or other computer operable instructions in response to user input parameters. The control unit 346 may include at least one graphical user interface 348 including, for example, a user-friendly display through which input parameters are entered into the control unit 346. Optionally, the user interface may be located on an area of the tool or at a remote location. In the case of the latter implementation, the control unit 346 may also include a communicating link for communicating with the remote user interface. It will be recognized that a number of control units 346 may be connected to a common control system (not illustrated) that is used to control and oversee the operations performed in the microfabrication facility or sections thereof. Among its many functions, the control unit 346 is programmed to control the transfer of microelectronic workpieces between the various processing stations and between the input/output section and the processing stations. Further, the control unit 346 is programmed to control the operation of the components at the individual processing stations to implement specific processing sequences in response to the user input parameters.
C. Embodiments of EPE Deposition Reactors [0048]
EPE deposition reactors electrochemically deposit EPRs or other EPEs onto microelectronic workpieces. As used herein, the term “electrochemically” includes (a) electrical processes that establish an electrical field in a bath using the workpiece as an anode or a cathode and (b) electroless processes that rely on the electrochemical interaction between the workpiece and the bath without inducing an electrical field in the bath. In general, the EPE deposition reactors are particularly suitable for depositing the conformal, uniform layer of negative resist [0049] 260 over and/or in large three-dimensional structures as described above with reference to FIG. 2B. Several embodiments of reactors for use in processing tools are single-wafer units that hold a workpiece at least substantially horizontal so that the EPE bath contacts only one side of the workpiece. This allows the other side of the workpiece to remain “clean” or otherwise isolated so that single-wafer handling equipment is not fouled by the EPE. Several embodiments of reactors also control bubbles to mitigate pinholes. In some embodiments, deposition of photoresist is prevented at the edge of the wafer so that an edge bead removal process is not needed.
FIG. 4 illustrates one embodiment of a [0050] reactor assembly 400 that can be used for the EPE deposition station 311 of the processing tool 310 (FIG. 3). In one embodiment, the reactor assembly 400 comprises a reactor head 405 and a reactor base 410. The reactor head 405 includes a stator 407, a rotor 420 carried by the stator 407, and a workpiece holder 425 carried by the rotor 420. The reactor base 410 includes a processing area or vessel suitable for EPR deposition or deposition from other EPEs. The general design of the reactor depicted in FIG. 4 can also be used to implement other processing operations and, as such, can be modified for use at other processing stations within the processing tool 310. For example, the reactor assembly 400 can be modified to execute rinse/dry processes, etching processes, and electrochemical processes (e.g., electropolishing, anodization, electroless plating, electroplating, etc.). For such other processes, the reactor base 410 may be modified to contain different chemistry and/or different chemical delivery mechanisms.
FIG. 4 illustrates one embodiment of the [0051] reactor base 410 for depositing an EPE on the workpiece 316. In this embodiment, the workpiece 316 is positioned with respect to the reactor base 410 so that the side of the workpiece that is to be processed faces downward in a generally horizontal plane. The particular reactor base 410 shown in FIG. 4 can be functionally divided into four subassemblies. A first subassembly 435 provides an environmentally controlled reservoir of processing fluid. A second subassembly 440 is a fluid input/output region including channels and passageways through which processing fluids flow to and from the reactor base 410. A third subassembly 445 is a deposition region in which the photoresist or other electrophoretic solution/emulsion is deposited onto the workpiece 316. The third subassembly 445 may include one or more components that reduce and/or eliminate bubbles that can cause pinhole formations in the deposited layer. A fourth subassembly 450 is an in-situ secondary processing region in which (a) the workpiece may be rinsed in-situ, (b) the workpiece holder 425 may be cleaned in-situ, or (c) other pre- or post-deposition procedures can take place.
As illustrated, the [0052] first subassembly 435 includes an emulsion tank 455 and a temperature control apparatus 460 disposed in the tank 455. The temperature control apparatus 460 can be an element that heats and/or cools the EPE chemistry in the tank 455 to a desired temperature for delivery to the deposition region 445.
The [0053] third subassembly 445 includes a bowl 485 above the emulsion tank 455 and a cup 490 within the bowl 485. The bowl 485 can be a generally cylindrical member that concentrically surrounds the cup 490. In the illustrated embodiment, the cup 490 has an annular upper structure and a tapered, frusto-conical lower portion 497 that slopes downwardly and radially inwardly. The dimensions of the bowl 485 may be similar to other types of reaction vessels used in wet processing tools (e.g., electroless plating reactors, etching reactors, rinse/dry capsules, etc.). As such, the reactor 400 is readily interchangeable with other reactors so that a single processing tool frame may be used for a wide range of different types of processes.
The [0054] reactor assembly 400 also includes a counter-electrode 495. As shown, the counter-electrode 495 is an annular ring. The counter-electrode 495 is coupled to one or more electrical connecting members to provide electrical power to the counter-electrode 495. The counter-electrode 495 can alternatively comprise a plurality of linear or curved segments positioned around the processing cup 490 or other electrodes as set forth in U.S. application Ser. Nos. 09/804,696; 09/804,697; and 09/872,151, all of which are herein incorporated by reference.
In operation, the [0055] reactor assembly 400 electrochemically deposits an EPR or other type of EPE onto the face of the workpiece 316. The electrochemical process includes lowering the reactor head 405 until the workpiece 316 contacts a flow of EPR at the top of the cup 490. An electrical field is established in the EPR by biasing a seed layer on the workpiece 316 at one potential and the counter-electrode 495 at an opposite potential. The electrical field between the seed layer on the workpiece 316 and the counter-electrode 495 causes micelles in the EPR solution to become attached to the surface of the workpiece 316. This is a self limiting process because the deposited EPR does not conduct electricity such that thin portions of the layer of the EPR deposited on the workpiece 316 have a higher deposition rate than thick portions. After a period of time, the thickness of the EPR layer deposited on the workpiece 316 becomes highly uniform and conforms to the topography of the workpiece 316.
D. Embodiments of Control Sequences [0056]
The control unit [0057] 346 (FIG. 3) can operate the processing tool 310 (FIG. 3) to deposit an electrophoretic material onto a workpiece in accordance with several different control sequences. The control sequences generally provide automated deposition of resists and other materials onto semiconductor wafers or other types of micro-feature workpieces in a manner that can be integrated with the other types of single-wafer processing equipment used in patterning micro-features and depositing metals. Several embodiments of such control sequences provide automated substrate handling by maintaining a clean surface on the workpiece. As such, the control sequence can use single-wafer handling equipment compatible with stepper machines and other microfabrication equipment.
FIG. 5 illustrates one [0058] processing sequence 550 of a number of possible sequences. The particular sequences and parameters used in the EPE deposition processes depend on the particular manufacturing processes that are to be implemented. In the illustrated embodiment of the processing sequence 550, the processing tool 310 (FIG. 3) receives a microelectronic workpiece from a cassette 317 (FIG. 3) and transfers it to one of the processing stations. The processing sequence 550, for example, can include a first fluid process 552, such as a pre-clean/pre-wetting process, in a fluid processing station 324 (FIG. 3). In an alternate embodiment, the processing sequence 550 can include a seed layer repair/enhancement procedure before the first fluid process 552 because it may be useful to enhance or otherwise deposit additional conductive material onto the seed layer before a pre-clean/pre-wetting process. Such enhancement or repair of the seed layer may provide better photoresist film characteristics. Methods and apparatus for processing a conductive seed layer are shown and described in U.S. Pat. No. 6,197,181, which is incorporated by reference herein.
After the pre-clean/pre-wetting process or other type of [0059] first fluid process 552, the control system 346 causes the robotic transfer mechanism 330 to remove the workpiece from the pre-clean/pre-wetting station and transfer it to the electrophoretic deposition station 311. At the electrophoretic deposition station 311, the sequence 550 further includes a deposition process 554 in which a negative electrophoretic resist is deposited on the workpiece. The EPR deposition process 554 forms a highly uniform conformal layer of negative resist even over large three-dimensional structures with large step heights as shown above in FIG. 2A. The specific parameters used in the deposition process 554 are input either directly or indirectly into the control system 346 by the user. It will be recognized that the particular parameters depend on the EPE type, the size of the workpiece, the type of underlying conductive layer, the thickness of the photoresist layer desired, and several other parameters.
After completing the [0060] deposition process 554, the sequence 550 includes an in-situ rinse process 556 carried out in the deposition station 311. This process reduces contamination of other components because residual EPE is rinsed from the workpiece before it is loaded onto the robot 330 (FIG. 3). Further, the control system 346 may direct an in-situ contact cleaning operation at any time. This process ensures consistent contact between the seed layer and the electrical contacts that provide electroplating power to the seed layer.
After the in-situ rinse [0061] process 556, the sequence 550 further includes a second fluid process such as a rinsing process 558. For example, the control system 346 directs the robotic transfer mechanism 330 to remove the microelectronic workpiece from the deposition station 311 and transfer it to a deionized water rinse station for executing the rinsing process 558. After the rinsing process 558, the workpiece can be removed from the tool 310 for subsequent processing. In an alternate embodiment, the sequence can optionally include a thermal process 559. For example, the control system 346 may also be programmed to direct the workpiece to a station at which the thermal process 559 is executed after completing the rinsing process 558. The thermal process 559 may include both heating and subsequent cooling of the workpiece to effectively cure the photoresist. When the thermal process 559 occurs in the tool 310, the workpiece can be removed from the tool 310 after baking and cooling the resist. As explained in more detail below, the workpiece is typically processed in additional tools for further processing the resist or other electrophoretic material deposited on the workpiece.
The [0062] control sequence 550 can further include an exposure procedure 560 followed by a photoresist development procedure 562 to create the openings in the negative resist layer for exposing the deposition areas 252 (FIG. 2C) on the seed layer 250 (FIG. 2C). Although the exposure procedure 560 and the development procedure 562 may be performed in the processing tool 310 (FIG. 3), these procedures are generally executed in separate tools. After the exposure procedure 560 and the development procedure 562, the microelectronic workpieces may be transferred back to the processing tool 310 for a metallization plating procedure 564 to form the features 270 (FIG. 2F). As shown at stage 566, the overall process may be repeated as necessary until the desired structures are formed in or on the substrate.
E. Additional Embodiments of Processing Station Layouts [0063]
FIGS. 6-8 illustrate additional layouts for processing stations in EPE deposition tools in accordance with other embodiments of the invention. With specific reference to FIG. 6, [0064] tool 310 a comprises EPE deposition stations 311, the load/unload station 318, one or more first fluid processing stations 332, and one or more second fluid processing stations 334. The fluid processing stations 332 and 334 may execute one or several process sequences, such as pre-wetting the workpiece prior to EPR deposition, cleaning the workpiece subsequent to EPR deposition, developing the EPR coating following patterning, depositing metallization on the workpiece, enhancing the seed layer prior to either EPR deposition or metallization deposition, and so forth.
The workpieces are transferred between the [0065] processing stations 311, 332 and 334 using one or more robotic transfer mechanisms 336 and 338 that are disposed for linear movement along a central track 328. All of the processing stations, as well as the robotic transfer mechanism, are disposed in a cabinet, such as the one shown in FIG. 3. The cabinet can be provided with filtered air at a positive pressure to thereby limit airborne contaminants that may reduce the effectiveness of the workpiece processing. To further limit cross-contamination between processing stations, the robotic transfer mechanisms 336 and 338 may be dedicated to specific processing stations.
FIG. 7 illustrates another embodiment of a [0066] processing tool 310 b in which a processing station 340 is located in a separate portion of the integrated tool set. Unlike the embodiment of FIG. 6, at least one processing station in the tool 310 b is serviced by a dedicated robotic mechanism 342. The dedicated robotic mechanism 342 accepts workpieces that are transferred to it by the robotic transfer mechanisms 336 and/or 338. Transfer may take place through an intermediate staging area 344. As such, it becomes possible to separate one portion of the workpiece processing tool, such as a thermal processing station 345, from other portions of the tool. Additionally, the processing station serviced by the dedicated robot 342 may be implemented as a separate module that is attached to upgrade an existing tool set. In another embodiment, the processing station 340 can be placed between the load/unload station 318 and the remainder of the processing tool 310 a. In which case, the dedicated robot 342 may also transfer workpieces from the load/unload station 318 to an intermediate staging area 344. It will be recognized that other types of processing stations may be serviced by the dedicated robot 342.
Other types of processing tool layouts may also be used. For example, in certain tools sold under the brand name Equinox™ available from Semitool, of Kalispell, Mont., the processing stations are disposed radially about a centrally located robotic transfer mechanism and a load/unload station. As illustrated in FIG. 8, for example, a [0067] radial tool 310c may include the same basic processing stations and robotic transfer apparatus similar to the linear tool.
From the foregoing, it will be appreciated that specific embodiments of the invention have been described herein for purposes of illustration, but that various modifications may be made without deviating from the spirit and scope of the invention. Accordingly, the invention is not limited except as by the appended claims. [0068]

Claims

We claim:

1. A method for processing a micro-feature workpiece having a first side, a second side, a plurality of micro-devices integrated in and/or on the workpiece, and at least one deep depression in the first side and/or the second side, the method comprising:

forming a conductive seed layer that extends into the deep depression in the workpiece;

depositing a conformal, uniformly thick negative resist layer onto the seed layer;

exposing portions of the negative resist layer outside of the depression to a selected energy to form an exposed region of the negative resist layer outside of the depression and an unexposed region of the negative resist layer in the depression;

removing the unexposed region of the negative resist layer to uncover a deposition area of the seed layer in the depression; and

electrochemically depositing a conductive material onto the deposition area of the seed layer.

2. The method of claim 1 wherein depositing the negative resist layer comprises electrochemically depositing a conformal layer of negative electrophoretic resist onto the seed layer.

3. The method of claim 1 wherein depositing the negative resist layer comprises electrochemically depositing a conformal layer of negative electrophoretic resist onto the seed layer by:

contacting the seed layer with a bath of negative electrophoretic resist; and establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist.

4. The method of claim 1 wherein depositing the negative resist layer comprises electrochemically depositing a conformal layer of negative electrophoretic resist onto the seed layer by:

holding the workpiece at least substantially horizontal and contacting the seed layer with a bath of negative electrophoretic resist while isolating another region of the workpiece from contacting the bath; and

establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist.

5. The method of claim 1 wherein depositing the negative resist layer comprises electrochemically depositing a conformal layer of negative electrophoretic resist onto the seed layer by:

holding the workpiece at least substantially horizontal and contacting the seed layer with a bath of negative electrophoretic resist while isolating another region of the workpiece from contacting the bath;

rotating the workpiece while the seed layer contacts the bath; and

6. The method of claim 1 wherein exposing the workpiece comprises aligning a mask with the depression to block the energy from irradiating the negative resist in the depression.

7. The method of claim 1 wherein electrochemically depositing a conductive material comprises electroplating a metal onto the deposition area of the seed layer by contacting the workpiece with a bath of electroplating solution and establishing an electrical field between the deposition area of the seed layer and an electrode in the bath of the electroplating solution.

8. The method of claim 1 wherein electrochemically depositing a conductive material comprises electroplating gold onto the deposition area of the seed layer by contacting the workpiece with a bath of electroplating solution containing gold ions and establishing an electrical field between the deposition area of the seed layer and an electrode in the bath of the electroplating solution.

9. The method of claim 1 wherein:

the workpiece comprises a microelectronic workpiece having a semiconductor substrate and a plurality of semiconductor devices integrally formed in discrete dies on the substrate; and

depositing a negative resist layer comprises contacting the seed layer with a bath of negative electrophoretic resist in an electrochemical resist deposition station, establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist, and rinsing in-situ within the electrochemical resist deposition station.

10. The method of claim 1 wherein:

the workpiece comprises a microelectronic workpiece having a semiconductor substrate and a plurality of semiconductor devices integrally formed in discrete dies on the substrate;

depositing a negative resist layer comprises contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist; and

electrochemically depositing a conductive material comprises electroplating gold or copper onto the deposition area of the seed layer by contacting the workpiece with a bath of electroplating solution containing gold ions and establishing an electrical field between the deposition area of the seed layer and an electrode in the bath of electroplating solution.

11. The method of claim 1 wherein:

the deep depression comprises a backside via extending through the substrate from the first surface to the second surface;

depositing a negative resist layer comprises contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist to cover the backside via with a conformal layer of the negative electrophoretic resist; and

12. A method for processing a micro-feature workpiece, comprising:

providing a workpiece having a first side, a second side, a plurality of micro-devices formed integrally on and/or in the workpiece, and at least one deep depression in the first side and/or the second side;

forming a thin conductive seed layer that extends into a deep depression in the workpiece;

constructing a conformal layer of negative resist on the seed layer by electrochemically depositing the negative resist onto the seed layer;

irradiating portions of the conformal layer of negative resist in areas outside of the depression to form an exposed pattern of negative resist outside of the depression and an unexposed pattern of negative resist in the depression;

removing the unexposed pattern of negative resist to uncover a deposition area of the seed layer in the depression; and

13. The method of claim 12 wherein constructing the conformal layer of negative resist comprises electrochemically depositing negative electrophoretic resist onto the seed layer in a single-wafer processing chamber while rotating the workpiece.

14. The method of claim 12 wherein constructing the conformal layer of negative resist comprises electrochemically depositing negative electrophoretic resist onto the seed layer by:

contacting the seed layer with a bath of negative electrophoretic resist; and

15. The method of claim 12 wherein constructing the conformal layer of negative resist comprises electrochemically depositing negative electrophoretic resist onto the seed layer by:

16. The method of claim 12 wherein constructing the conformal layer of negative resist comprises electrochemically depositing negative electrophoretic resist onto the seed layer by:

rotating the workpiece while the seed layer contacts the bath; and

17. The method of claim 12 wherein irradiating portions of the workpiece comprises aligning a mask with the depression to block the energy from irradiating the negative resist in the depression.

18. The method of claim 12 wherein electrochemically depositing the conductive material comprises electroplating a metal onto the deposition area of the seed layer by contacting the workpiece with a bath of electroplating solution and establishing an electrical field between the deposition area of the seed layer and an electrode in the bath of the electroplating solution.

19. The method of claim 12 wherein electrochemically depositing the conductive material comprises electroplating gold onto the deposition area of the seed layer by contacting the workpiece with a bath of electroplating solution containing gold ions and establishing an electrical field between the deposition area of the seed layer and an electrode in the bath of the electroplating solution.

20. The method of claim 12 wherein:

constructing the conformal layer of negative resist comprises contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist.

21. The method of claim 12 wherein:

constructing the conformal layer of negative resist comprises contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist; and

electrochemically depositing the conductive material comprises electroplating gold onto the deposition area of the seed layer by contacting the workpiece with a bath of electroplating solution containing gold ions and establishing an electrical field between the deposition area of the seed layer and an electrode in the bath of electroplating solution.

22. The method of claim 12 wherein:

constructing the conformal layer of negative resist comprises contacting the seed layer with a bath of negative electrophoretic resist and establishing an electrical field between the seed layer and an electrode in the bath of negative electrophoretic resist to form the conformal layer of the negative electrophoretic resist in the backside via; and

23. A micro-feature workpiece, comprising:

a substrate;

a plurality of micro-devices formed integrally with the substrate;

a deep depression having a sidewall extending into the substrate;

a conductive seed layer on the substrate and the sidewall of the deep depression; and

a conformal layer of negative electrophoretic resist on the seed layer.

24. The micro-device workpiece of claim 23 wherein the conformal layer of resist has an irradiated portion outside of the depression and a non-irradiated portion in the depression, and wherein the non-irradiated portion has a higher. solubility in a developing solution than the irradiated portion.

25. The micro-device workpiece of claim 23 wherein:

the substrate comprises a semiconductor wafer; and

the micro-devices comprise semiconductor dies formed integrally with the wafer, and the dies include integrated circuitry having submicron features.

26. The micro-device workpiece of claim 23 wherein:

the substrate comprises a semiconductor wafer; and

the micro-devices comprise semiconductor dies formed integrally with the wafer, and the dies include supramicron features.

27. The micro-device workpiece of claim 23 wherein:

the substrate comprises a micromechanical wafer; and

the micro-devices comprise micromechanical devices formed integrally with the wafer, and the micromechanical devices have submicron features.

28. The micro-device workpiece of claim 23 wherein:

the substrate comprises a micromechanical wafer; and

the micro-devices comprise micromechanical devices formed integrally with the wafer, and the micromechanical devices have supramicron features.

29. The micro-device workpiece of claim 23 wherein:

the substrate comprises a semiconductor wafer;

the micro-devices comprise semiconductor dies formed integrally with the wafer, and the dies include integrated circuitry having submicron features;

the deep depression comprises at least one backside via having a sidewall extending completely through the wafer; and

the conformal layer of electrophoretic negative resist has a thickness that is at least substantially constant along the sidewall of the backside via.

30. The micro-device workpiece of claim 23 wherein:

the substrate comprises a semiconductor wafer;

the deep depression comprises a backside via having a sidewall extending completely through the wafer;

the conformal layer of negative resist has an irradiated portion outside of the backside via and an opening over the seed layer in the backside via defining a deposition area; and

a metal is deposited in the deposition area but not on the resist.

31. An integrated tool for processing a micro-feature workpiece, comprising:

a cabinet;

an electrophoretic emulsion (EPE) deposition station in the cabinet, the EPE deposition station having a reactor including a cup configured to contain an EPE and a workpiece holder configured to isolate at least one region of the workpiece from EPE in the cup;

a first wet processing station in the cabinet, the first wet processing station comprising a chamber configured to develop electrophoretic resist;

a second wet processing station in the cabinet, the second wet processing station being an electrochemical deposition station configured to deposit conductive material onto the workpiece; and

a workpiece handling apparatus in at least a portion of the cabinet, the workpiece handling apparatus being configured to contact the region of the workpiece isolated from the EPE to transport the workpiece relative to the EPE station, the chamber, and the electrochemical deposition station.