JP5489717B2 - Method and integrated system for conditioning a substrate surface for metal deposition - Google Patents

Description

  Integrated circuits use conductive wiring to connect individual elements on a semiconductor substrate or to communicate externally to the integrated circuit. Wiring metallization for vias and trenches may include aluminum alloys and copper. Electromigration (EM) is a well-known reliability issue for metal interconnects and is caused by electrons moving metal atoms in the direction of current at a rate determined by the current density. Electromigration can ultimately lead to thinning of the metal wire, which can result in increased resistivity or, in the worst case, damage to the metal wire. Fortunately, all of the wiring metal lines on the IC do not always have current flowing in the same direction, unlike the power line and ground lines. However, as metal lines become narrower (International Technology Roadmap for Semiconductors (ITRS) calls for ~ 0.7x linewidth reduction per technology node), electromigration is increasingly It is a problem.

  In aluminum wires, EM is a bulk phenomenon and is well controlled by the addition of small amounts of dopants such as copper. On the other hand, EM in copper wire is a surface phenomenon. This can occur anywhere where copper can move freely, and generally occurs at poorly bonded interfaces between copper and another material. In today's dual damascene processes, this occurs most frequently at the top of the copper line bordering the layer, which is typically a SiC diffusion barrier layer, but can also occur at the copper / barrier interface. The problem gets worse with each transition to the next technology node and with the resulting increase in current density.

  The solution to the EM problem and the associated stress void, another common reliability problem, was the process integration process. That is, optimized deposition (ie deposition that reduces the thickness of the barrier and seed layers), wafer cleaning before and after deposition, surface treatment, etc. all provide a uniform surface and provide adhesion between layers It was the process of integrating processes aimed at making it excellent and minimizing metal atom migration and void propagation. In the dual damascene process, trenches and holes (for contacts and vias) are etched into the dielectric and then lined with a barrier material such as tantalum (Ta), tantalum nitride (TaN), or a combination of both films. This is followed by copper seed layer deposition, copper electroplating, copper planarization using CMP, and dielectric stack deposition such as SiC / low-k / SiC. Because copper easily forms oxides on it when exposed to air, to ensure good adhesion between copper and SiC, proper post-CMP cleaning before copper is covered with SiC And copper oxide must be removed. Removal of copper oxide prior to SiC deposition is essential for achieving excellent EM resistance and resulting metal resistivity reduction.

  In recent years, a cobalt alloy cap layer such as CoWP (Cobalt Tungsten Phosphorus), CoWB (Cobalt Tungsten Boron) or CoWBP (Cobalt Tungsten Phosphorus Phosphide) is applied to the copper before the SiC dielectric barrier layer. It has been shown that electromigration is greatly improved when covered, compared to the case where SiC is provided on copper. FIG. 1 shows that cobalt alloy cap layers 20 and 30 were deposited on the copper layers 23 and 33 and below the dielectric cap SiC layers 25 and 35, respectively. As the layers 24 and 34, Ta and / TaN barrier layers are illustrated. The cobalt alloy layers 20 and 30 improve the adhesion between the copper 23 and 33 and the SiC cap layers 25 and 35. The cobalt alloy layers 20, 30 can also exhibit some copper diffusion barrier properties. The cobalt alloy cap layer can be selectively deposited on copper by electroless deposition. However, electroless deposition can be hampered by a thin layer of copper oxide that can form when copper is exposed to air. In addition, contaminants on the copper and dielectric surfaces can cause pattern-dependent plating effects. Pattern-dependent plating effects include pattern-dependent Co alloy thickness and pattern-dependent copper wire thickness due in part to etching during the “incubation time” required to initiate the Co plating reaction There is loss. Therefore, limiting the growth of native copper oxide by controlling the processing environment immediately prior to depositing a metal cap layer such as a cobalt alloy (ie, controlling) and copper oxide and organic contaminants and dielectrics on the copper surface It is important to remove organic and metal contaminants on the surface. Furthermore, to reduce pattern-dependent deposition variability, the dielectric surface must be controlled to standardize its effect on structures with different pattern densities. To ensure good interfacial adhesion and good EM resistance, the copper layers 23, 33, the copper-barrier layers 33, 34 and 23, 24, as well as the adhesion promoting layer (ie metal cap layer) and the cobalt alloy layers 20, 20 It is very important to design the metal-metal interface between and the like. Further, as the metal line becomes narrower, the portion occupied by the barrier film and seed film by physical vapor deposition (PVD) occupies the metal line, which increases the effective resistivity and thus the current density. A thin, conformal barrier layer and seed layer comprises an atomic layer growth (ALD) barrier (TaN, Ru, or heterogeneous) that provides conformal step coverage and acceptable barrier properties, and a conformal seed layer. This trend can be mitigated by the electroless Cu process provided. However, until now, there has been no electroless Cu seed layer that can adhere to the resulting ALD TaN barrier film.

  Thus, there is a need for a system and process for forming a metal-metal interface for copper wiring that has improved electromigration resistance, reduced sheet resistance, and improved interfacial adhesion.

  In general, embodiments provide improved metal-to-copper interconnects to improve electromigration resistance, to provide lower metal resistivity, and to improve metal-metal or silicon-metal interface adhesion. The need is met by providing a process and integrated system that provides a metal interface or silicon-metal interface. The present invention can be implemented in many ways, including solutions, methods, processes, apparatuses, or systems. In the following, several embodiments of the invention will be described.

  In one embodiment, in an integrated system, the substrate surface of the substrate is used to selectively deposit a thin layer of cobalt alloy material on the copper surface of the copper interconnect of the substrate to improve the electromigration resistance of the copper interconnect. A method of adjusting is provided. The method removes contaminants and metal oxides from the substrate surface within the integrated system and, after removing contaminants and metal oxides, reconditions the substrate surface using a reducing environment within the integrated system. Including. The method also includes selectively depositing a thin layer of cobalt alloy material on the copper surface of the copper interconnect in the integrated system after reconditioning the substrate surface.

  In another embodiment, the substrate is placed in a controlled environment to allow a thin layer of cobalt alloy material to be selectively deposited on the copper surface of the copper interconnect to improve the electromigration resistance of the copper interconnect. An integrated system for transport and processing is provided. The integrated system includes a laboratory atmosphere transfer chamber, a laboratory atmosphere transfer chamber capable of transferring a substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system, and a laboratory atmosphere transfer chamber. And a substrate cleaning reactor for cleaning the substrate surface to remove metal organic complex contaminants on the substrate surface.

  The system is also operated under vacuum at a pressure of less than 1 Torr, a vacuum transfer chamber coupled with at least one vacuum process module, and a vacuum process module for removing organic contaminants from the substrate surface, One of at least one vacuum process module coupled to the vacuum transfer chamber and operated under a vacuum having a pressure of less than 1 Torr. The integrated system further includes a controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases and at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber. The system is also used to deposit a thin layer of cobalt alloy material on the copper surface of the copper interconnect after the substrate surface has been cleared of metal and organic contaminants and the copper surface has been removed of copper oxide. An electroless cobalt alloy material deposition process module, one of at least one controlled atmosphere process module coupled to a controlled atmosphere transfer chamber, filled with an inert gas selected from the group of inert gases, An electroless cobalt alloy material deposition process module having a fluid delivery system from which fluid is degassed.

  In another embodiment, in an integrated system, a metal barrier layer is deposited to line the copper interconnect structure of the substrate, and a thin copper seed layer is deposited on the surface of the metal barrier layer to provide electromigration of the copper interconnect. A method is provided for conditioning the substrate surface of the substrate to improve resistance. The method includes cleaning an exposed surface of the underlying metal to remove surface metal oxide within the integrated system. The lower metal is a part of the lower wiring that is electrically connected to the copper wiring. The method also includes depositing a metal barrier layer to line the copper interconnect structure within the integrated system. After depositing the metal barrier layer, the substrate is transported and processed in a controlled environment to prevent metal barrier oxide formation. The method further includes depositing a thin copper seed layer in the integrated system and depositing a gap fill copper layer over the thin copper seed layer in the integrated system.

  In another embodiment, in an integrated system, a thin copper seed layer is deposited on the surface of the metal barrier layer of the copper interconnect structure to improve the electromigration resistance of the copper interconnect structure. A method of adjusting is provided. The method includes reducing the surface of the metal barrier layer to convert the metal barrier oxide on the surface of the metal barrier layer to make the surface of the metal barrier layer metal rich within the integrated system. The method also includes depositing a thin copper seed layer in the integrated system and depositing a gap fill copper layer over the thin copper seed layer in the integrated system.

  In another embodiment, an integrated system for processing a substrate in a controlled environment is provided to allow a thin copper seed layer to be deposited on the surface of a copper barrier metal barrier layer. The integrated system includes a laboratory atmosphere transfer chamber that is capable of transferring a substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system. The integrated system also includes a vacuum transfer chamber that is operated under a vacuum whose pressure is less than 1 Torr. At least one vacuum process module is coupled to the vacuum transfer chamber. The integrated system further includes a vacuum process module for cleaning the exposed surface of the metal oxide of the underlying metal within the integrated system. The lower metal is a part of the lower wiring, and the copper wiring is electrically connected to the lower wiring. The vacuum process module for cleaning is one of at least one vacuum process module coupled to the vacuum transfer chamber and is operated under a vacuum at a pressure of less than 1 Torr.

  The integrated system also includes a vacuum process module for depositing the metal barrier layer. The vacuum process module for depositing the metal barrier layer is one of at least one vacuum process module coupled to a vacuum transfer chamber and is operated under a vacuum at a pressure of less than 1 Torr. The integrated system also includes a controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases. At least one controlled atmosphere process module is coupled to the controlled atmosphere transfer chamber. The integrated system further includes an electroless copper deposition process module that is used to deposit a thin copper seed layer on the surface of the metal barrier layer. The electroless copper deposition process module is one of at least one controlled environment process module coupled to a controlled atmosphere transfer chamber.

  In another embodiment, an integrated system for processing a substrate in a controlled environment is provided to allow a thin copper seed layer to be deposited on the surface of a copper barrier metal barrier layer. The integrated system includes a laboratory atmosphere transfer chamber that is capable of transferring a substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system. The integrated system also includes a vacuum transfer chamber that is operated under a vacuum whose pressure is less than 1 Torr. At least one vacuum process module is coupled to the vacuum transfer chamber.

  The integrated system further includes a vacuum process module for reducing the metal barrier layer. The vacuum process module for reducing the metal barrier layer is one of at least one vacuum process module coupled to a vacuum transfer chamber and is operated under a vacuum at a pressure of less than 1 Torr. The integrated system also includes a controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases. At least one controlled atmosphere process module is coupled to the controlled atmosphere transfer chamber. The integrated system also includes an electroless copper deposition process module that is used to deposit a thin copper seed layer on the surface of the metal barrier layer. The electroless copper deposition process module is one of at least one controlled environment process module coupled to a controlled atmosphere transfer chamber.

  In another embodiment, a method for conditioning a substrate surface of a substrate to selectively deposit a layer of metal on a silicon surface or polysilicon surface of the substrate to form a metal silicide in an integrated system. Provided. The method removes organic contaminants from the substrate surface in the integrated system and converts the silicon oxide on the silicon surface or polysilicon surface to silicon in the integrated system after removing the organic contaminants. Reducing the silicon surface or the polysilicon surface. After reducing the silicon or polysilicon surface, the substrate is transported and processed in a controlled environment to prevent the formation of silicon oxide, and the silicon or polysilicon surface increases the selectivity of the metal on the silicon surface. In order to be reduced. The method also includes selectively depositing a layer of metal on the silicon surface or polysilicon surface of the substrate in the integrated system after reducing the silicon surface or polysilicon surface.

  In another embodiment, an integrated system is provided for processing a substrate in a controlled environment to enable selective deposition of a layer of metal on the silicon surface of the substrate to form a metal silicide. The integrated system includes a laboratory atmosphere transfer chamber that is capable of transferring a substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system. The integrated system also includes a vacuum transfer chamber that is operated under a vacuum whose pressure is less than 1 Torr. At least one vacuum process module is coupled to the vacuum transfer chamber. The integrated system further includes a vacuum process module for removing organic contaminants from the substrate surface. The vacuum process module for removing organic contaminants is one of at least one vacuum process module coupled to a vacuum transfer chamber and is operated under a vacuum at a pressure of less than 1 Torr.

  The integrated system also includes a vacuum process chamber for reducing the silicon surface. The vacuum process chamber for reducing the silicon surface is one of at least one vacuum process module coupled to the vacuum transfer chamber and is operated under a vacuum at a pressure of less than 1 Torr. The integrated system also includes a controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases and at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber. The integrated system further includes an electroless metal deposition process module that is used to selectively deposit a thin metal layer on the silicon surface after the silicon surface is reduced, the electroless metal deposition process module Is one of at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber.

  Other aspects and advantages of the invention will become apparent from the following detailed description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the invention.

  The present invention can be readily understood by the following detailed description in conjunction with the accompanying drawings. Here, similar reference numerals indicate similar components.

It is sectional drawing which shows the typical cross section of wiring. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is explanatory drawing which shows the various forms of the contaminant on the board | substrate surface after metal CMP. FIG. 3 is a process diagram illustrating an exemplary process flow for conditioning a copper surface for electroless deposition of a cobalt alloy. FIG. 4B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 4A. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. FIG. 3 is a process diagram illustrating an exemplary process flow for conditioning a copper surface for electroless deposition of a cobalt alloy. FIG. 6B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 6A. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. It is sectional drawing which shows the cross section of the wiring structure in the various stages of wiring processing. FIG. 3 is a process diagram illustrating an exemplary process flow for conditioning a copper surface for electroless deposition of a cobalt alloy. FIG. 8B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 8A. It is sectional drawing which shows the cross section of the metal wire structure in the various stages of a process. It is sectional drawing which shows the cross section of the metal wire structure in the various stages of a process. It is sectional drawing which shows the cross section of the metal wire structure in the various stages of a process. It is sectional drawing which shows the cross section of the metal wire structure in the various stages of a process. It is sectional drawing which shows the cross section of the metal wire structure in the various stages of a process. FIG. 5 is a process diagram illustrating an exemplary process flow for adjusting a barrier layer surface to electrolessly deposit a copper layer. FIG. 10B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 10A. FIG. 5 is a process diagram illustrating an exemplary process flow for adjusting a barrier layer surface to electrolessly deposit a copper layer. FIG. 10D is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 10C. FIG. 5 is a process diagram illustrating an exemplary process flow for conditioning a barrier layer surface for electroless deposition of a copper layer and conditioning a copper surface for electroless deposition of a cobalt alloy. FIG. 11B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 11A. It is sectional drawing which shows the cross section of the wiring structure in the various stages of a process. It is sectional drawing which shows the cross section of the wiring structure in the various stages of a process. It is sectional drawing which shows the cross section of the wiring structure in the various stages of a process. It is sectional drawing which shows the cross section of the wiring structure in the various stages of a process. FIG. 5 is a flow diagram illustrating an exemplary process flow for conditioning a barrier surface for electroless copper deposition and for conditioning a copper surface for electroless deposition of a cobalt alloy. FIG. 13B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 13A. It is sectional drawing which shows the cross section of the gate structure in the various stages of metal silicide formation. It is sectional drawing which shows the cross section of the gate structure in the various stages of metal silicide formation. It is sectional drawing which shows the cross section of the gate structure in the various stages of metal silicide formation. It is sectional drawing which shows the cross section of the gate structure in the various stages of metal silicide formation. FIG. 6 is a process diagram illustrating an exemplary process flow for adjusting an exposed silicon surface to form a metal silicide. FIG. 15B is a block diagram illustrating an exemplary system used to process a substrate through the process flow of FIG. 15A. It is a block diagram which shows the outline of the system integration about the integrated system which has an atmosphere control processing environment.

  Several exemplary embodiments are provided for improved metal integration techniques that modify the metal interface by removing the interfacial metal oxide by reduction to improve electromigration, metal resistivity, and interfacial adhesion. . The present invention can be implemented in many ways, including as a process, a method, an apparatus, or a system. Several inventive embodiments of the invention are described below. It will be apparent to those skilled in the art that the present invention may be practiced without some or all of the details specified herein.

  FIG. 2A shows a representative cross section of a wiring structure after it has been patterned using a dual damascene process procedure. The wiring structure has a dielectric layer 100 on the substrate 50 and having a metallization line 101 formed therein in advance. Metallization lines are typically created by etching a trench in dielectric 100 and then filling the trench with a conductive material such as copper.

  Within the trench is a barrier layer 120 that is used to prevent the copper material 122 from diffusing into the dielectric 100. The barrier layer 120 can be made of PVD tantalum nitride (TaN), PVD tantalum (Ta), ALD TaN, or a combination of these films. Other barrier layer materials can also be used. The barrier layer 102 is planarized copper to protect the copper material 122 from premature oxidation when the via hole 114 is etched through the upper dielectric material 104, 106 into the barrier layer 102. Deposited on material 122. The barrier layer 102 is also configured to function as a selective etch stop and a copper diffusion barrier. Exemplary barrier layer 102 materials include silicon nitride (SiN) or silicon carbide (SiC).

  A via dielectric layer 104 is deposited over the barrier layer 102. Via dielectric layer 104 can be made of organosilicate glass (OSG, carbon doped silicon oxide) or other type of dielectric material, preferably of low dielectric constant. Typical silicon dioxide includes PECVD undoped TEOS silicon dioxide, PECVD fluorinated silica glass (FSG), HDP FSG, OSG, porous OSG, and the like. Commercial dielectric materials including Black Diamond (I) and Black Diamond (II) by Applied Materials in Santa Clara, California, Coral by Novellus Systems in San Jose, and Aurora by ASM America Inc. in Phoenix, Arizona should also be used. Can do. Above the via dielectric layer 104 is a trench dielectric layer 106. The trench dielectric layer 106 may be a low-k dielectric material such as carbon-doped oxide (C oxide). The dielectric constant of the low-k dielectric material may be about 3.0 or less. In one embodiment, the via dielectric layer and the trench dielectric layer are both made of the same material and are simultaneously deposited to form a continuous film. After the trench dielectric layer 106 is deposited, the substrate 50 holding this (these) structure is subjected to a patterning process and an etching process to form via holes 114 and trenches 116 by known techniques.

  FIG. 2B shows that after formation of via hole 114 and trench 116, barrier layer 130 and copper layer 132 are deposited for lining and filling via hole 114 and trench 116. FIG. The barrier layer 130 can be made of tantalum nitride (TaN), tantalum (Ta), ruthenium (Ru), or a heterogeneous mixture of these films. These are commonly considered materials, but other barrier layer materials can also be used. A copper film 132 is then deposited to fill the via hole 114 and the trench 116.

  After filling the via hole 114 and the trench 116 with the copper film 132, the substrate 50 is then exposed to a copper material (ie excess copper) and a barrier layer (ie excess barrier) over the surface of the dielectric 106, as shown in FIG. 2C. ) Is removed by chemical mechanical polishing (CMP). The next step is to cover a copper surface 140 with a copper / SiC interface adhesion promoting layer 135 such as a cobalt alloy, as shown in FIG. 2D. Examples of cobalt alloys include CoWP, CoWB, or CoWBP that can be selectively deposited on copper by an electroless process. The thickness of the adhesion promoting layer is as thin as a monomolecular layer of only a few angstroms such as 5 angstroms, but is thicker layers such as 200 to 300 angstroms that can also function as a Cu diffusion barrier and eliminate the need for a dielectric cap. It is possible that

Copper chemical mechanical polishing (CMP) often uses benzotriazole (BTA) as a copper corrosion inhibitor. Copper forms a Cu-BTA complex with BTA. Substrates processed through Cu CMP and post-CMP cleaning contain copper residues in the form of Cu-BTA complexes, shown as open circles in FIG. 3, both on the Cu lines and on the adjacent dielectric. There is a fear. The Cu-BTA complex on the dielectric needs to be removed to prevent increased current leakage or metal shorting. Furthermore, in addition to the various organic contaminants shown as solid circles in FIG. 3, there may also be a small amount of Ta or other barrier material residue shown as open triangles in FIG. In addition to these contaminants, there are various metal oxides represented by CuO and CuO ₂ shown as solid triangles in FIG. Cu-BTA complexes, metal oxides, and organic contaminants are the three major surface contaminants that must be removed from the substrate surface. Providing dielectric and metal surfaces free of organic and metal-containing compound contaminants is a challenge and requires multi-step surface conditioning that would include both wet and dry processes.

  The following are some representative process flows and systems that allow surface conditioning of the underlying metal to allow the superior metal layer to be deposited in an excellent manner for adhesion between the two metal layers. is there. Metal layers deposited by typical process flows and systems are believed to exhibit improved EM resistance and thus low overall metal resistivity.

1. Design of copper surface for cobalt alloy deposition:
Case I: Metal CMP Stops on Dielectric Layer FIG. 4A illustrates a surface conditioning for electroless deposition of a cobalt alloy on post-CMP copper surface 140 of the dual damascene via-trench structure shown in FIG. 2C. 1 illustrates one embodiment of a process flow. The substrate used in the process flow of FIG. 4A has just completed a metal CMP process to remove excess copper layers and excess barrier layers such as Ta and / or TaN. As described above in the paragraph related to FIG. 3, there are various metal and organic contaminants on the substrate surface.

The process begins at step 401 by removing metal organic complex contaminants (ie, complexed metal-organic contaminants) such as Cu-BTA complexes and metal oxides from the substrate surface. Although metal contaminants are removed from both the copper and dielectric surfaces, the purpose of this step is to eliminate potential metal sources that may later function as nucleation sites for subsequent Co alloy deposition This is to improve the selectivity and the Co film morphology. Other metal oxides such as copper-BTA complexes, copper oxide (CuO _x ), and tantalum oxide (TaO _y ) are removed from the substrate surface during this step. The amount of copper oxide removed depends on the level and depth of metal oxide contamination on the surface. Metal complexes and metal oxides can be removed by an O ₂ / Ar sputtering process or by a wet chemical removal process of a one-step or two-step wet chemical process procedure. Preferred embodiments use a wet process to remove complexing metals and metal oxides. Wet chemical removal processes include organic acids such as DeerClean provided by Kanto Chemical Co., Japan, semi-aqueous solvents such as ESC 5800 provided by DuPont, Wilmington, Delaware, tetramethylammonium chloride (TMAH) Organic bases such as, complexing amines such as ethylenediamine and diethylenetriamine, or proprietary chemicals such as ELD Cleaning and Cap Clean 61 provided by Enthone, Inc. of West Haven, Conn., Can be used. The removal of Cu-BTA from the dielectric surface reduces the selectivity by copper from Cu-BTA being oxidized to copper oxide and subsequently reduced to copper during other surface conditioning steps, resulting in a Co alloy. As a result of providing nucleation sites on the dielectric surface on which the substrate is to be grown, it is ensured that no short circuit is caused and no leakage current is increased. Thus, the Cu-BTA removal process can also reduce yield loss due to metal shorts or current leakage.

  Cu-BTA complexes and other metal oxide contaminants are the two major metal contaminants to be removed during this step, and this removal can be in either a controlled or uncontrolled atmosphere (ie, environment). It can be done with. For example, Cu-BTA can be tetramethylammonium hydroxide (TMAH) or complexing amines such as ethylenediamine or diethylenetriamine, or ELD cleaning and Cap Clean 61 provided by Enthone, Inc. of West Haven, Connecticut. It can be removed by a wet cleaning process with a cleaning solution containing a patented chemical. Metal oxides, particularly copper oxide, can be removed using weak organic acids such as citric acid, or other organic or inorganic acids can be used. Also very thin (ie <0.1%) peroxide-containing acids such as sulfur-peroxide mixtures can be used. The wet cleaning process can also remove other metal residues or metal oxide residues.

  The presence of BTA on copper wires of different patterns or feature types, such as low density, small isolation, wide, etc., is the result of line passivation, the amount of which is partly due to the pattern-dependence that occurs on these features. Related to the degree of galvanic effect. This may result in the formation of a pattern-dependent passivation layer. This dependence may further affect the deposition characteristics of the Co alloy, resulting in pattern-dependent deposition characteristics, sometimes referred to as incubation effects or initiation effects. Removal of BTA from the Cu line eliminates this pattern-dependent deposition effect of the cobalt alloy (to be deposited in subsequent steps) and allows the cobalt alloy to be deposited uniformly within the dense isolation features. Useful for.

In step 304, organic contaminants can be removed by an oxidizing plasma, such as an oxygen-containing plasma process. The oxygen (O ₂ ) plasma process is preferably performed at a relatively low temperature of less than 120 degrees Celsius. High temperature O ₂ plasma processes tend to oxidize copper into thick layers, making subsequent reduction difficult. Therefore, a low temperature O ₂ plasma process is preferred. In one embodiment, the O ₂ plasma process may be a downstream plasma process. Alternatively, organic residues (ie, contaminants) can be removed using an O ₂ / Ar sputtering process to physically remove organic contaminants. O ₂ plasma processes and O ₂ / Ar sputtering processes are generally operated at less than 1 Torr.

  Once the substrate surface is free of contaminants such as Cu-BTA, metal oxides, and other organic contaminants, the substrate should be exposed to as little oxygen as possible to protect the copper surface from oxidation. Is desirable. Copper oxidation is not a self-regulating process. In order to minimize copper oxide formation, it is desirable to limit (or control) the amount and duration of exposure of the substrate to oxygen. Copper oxide is reduced in a later step, but thick copper oxide layers may not be completely reduced. Therefore, it is important to limit the exposure of copper to oxygen only to that required for the removal of organic contaminants. In order to achieve control and limitation of exposure to oxygen, it is desirable that the substrate be transported and processed in a controlled environment, such as an environment under vacuum or filled with an inert gas.

In order to ensure that there is no copper oxide on the copper surface, the substrate surface is reconditioned in a reducing environment in step 405 to convert any residual copper oxide to copper. Since the previous pre-cleaning step has removed any metal from the dielectric layer, metal reduction is performed only on the copper wire. Reduction of the copper surface can be achieved by converting copper oxide to copper (or substantially copper) by a hydrogen-containing plasma process. Exemplary reactive gases that can be used to generate a hydrogen-containing plasma include hydrogen (H ₂ ), ammonia (NH ₃ ), and carbon monoxide (CO). For example, the substrate surface is reduced by a hydrogen-containing plasma generated by hydrogen (H ₂ ) gas, ammonia (NH ₃ ) gas, or a combination of both gases, and the substrate is heated to a high temperature from 20 degrees Celsius to 300 degrees Celsius. is there. In one embodiment, the hydrogen plasma process is a downstream plasma process. After undergoing a hydrogen reduction process, the substrate is ready for cobalt alloy deposition. The copper surface needs to be carefully protected to ensure that no copper oxide is formed. As described above, electroless deposition of cobalt alloys can be inhibited by the presence of copper oxide. Therefore, it is important to control the processing and transport environment to minimize the exposure of the copper surface to oxygen.

  In a next process step 407, a cobalt alloy such as CoWP, CoWB, or CoWBP is electrolessly deposited on the copper surface. Electroless deposition of cobalt alloys is a wet process and deposits only on catalytic surfaces such as copper surfaces. The cobalt alloy is selectively deposited only on the copper surface.

  After electroless deposition of the cobalt alloy, the process flow can enter an optional post-deposition cleaning process step 409. Post-deposition cleaning can be accomplished using a brush scrub cleaning with a chemical solution such as a solution containing CP72B supplied by Air Products and Chemical, Inc. of Allentown, Pa. Other substrate surface cleaning processes such as Lam's C3 ™ or P3 ™ cleaning technology can also be used. Other post-cleaning chemicals can include hydroxylamine-based chemicals to remove any metal-based contaminants that would remain on the dielectric surface after electroless plating.

  As described above, control of the process environment and wafer transfer environment is very important for conditioning the copper surface for cobalt alloy deposition, particularly after hydrogen plasma reduction of the copper surface. FIG. 4B shows a schematic diagram of an exemplary integrated system 450 that can minimize exposure of the substrate surface to oxygen at key steps after surface treatment. Also, since this is an integrated system, the substrate is immediately transferred from one process station to the next, which limits the time that the conditioned copper surface is exposed to oxygen. The integrated system 450 can be used to process the substrate throughout the process sequence of the flow 400 of FIG. 4A.

As mentioned above, surface treatment, electroless deposition of cobalt alloys, and optional post-cobalt alloy deposition processes involve a mix of dry and wet processes. Wet processes are generally operated in the near atmosphere, and dry O ₂ plasma, hydrogen plasma, and O ₂ / Ar sputtering are all operated at less than 1 Torr. Thus, the integrated system needs to be able to handle a mix of dry and wet processes. The integrated system 450 has three substrate transfer modules (or chambers) 460, 470, 480. The transfer chambers 460, 470, 480 are equipped with a robot for moving the substrate 455 from one process area to another. The process area may be a substrate cassette, a reactor, or a load lock. The substrate transfer module 460 is operated in a laboratory atmosphere. A laboratory atmosphere refers to a laboratory (or factory) environment that is exposed to air at room temperature, atmospheric pressure, and generally filtered through UEPA or ULPA to control particle defects. Module 460 functions in conjunction with substrate loader (or substrate cassette) 461 to bring substrate 455 into the integrated system or to return the substrate to cassette 461 and continue processing outside system 450.

  As described above in process flow 400, substrate 455 is planarized by metal CMP to remove excess metal from the substrate surface, leaving metal only in the metal trenches, as shown in FIG. 2C. And then brought into the integrated system 450 for depositing a cobalt alloy such as CoWB, CoWP, or CoWBP. As described in step 401 of process flow 400, the substrate surface needs to be cleaned of surface contaminants such as Cu-BTA complexes and other metal oxide residues. Cu-BTA and metal oxides can be removed by a wet cleaning process with a cleaning solution such as a solution containing TMAH or a complexed amine containing ethylenediamine or diethylaminetriamine as non-limiting examples. Following removal of the BTA metal complex, the metal oxide remaining on the copper and dielectric surfaces contained citric acid or other organic acids that could remove copper oxide to some degree of selectivity over copper. It can be removed using a wet cleaning process with a cleaning solution such as a solution. Metal oxides, particularly copper oxide, can be removed using weak organic acids such as citric acid, or other organic or inorganic acids can be used. Also very thin (ie <0.1%) peroxide-containing acids such as sulfur-peroxide mixtures can be used. The wet cleaning process can also remove other metal residues or metal oxide residues.

  A wet cleaning reactor 463 can be integrated into the laboratory atmosphere transfer module 460 that operates in laboratory atmosphere conditions. The wet cleaning reactor can be used to perform a one-step or two-step cleaning, as described above in step 401 of FIG. 4A. Alternatively, an additional wet cleaning reactor 463 ′ is integrated into the laboratory atmosphere transfer module 460 so that the first step of the two-step cleaning process is performed in the reactor 463 and the second step is performed in the reactor 463 ′. Can be. For example, in the reactor 463, there is a cleaning solution containing a chemical agent such as TMAH for cleaning Cu-BTA, and in the reactor 463 ′, a weak organic material such as citric acid is used for cleaning the metal oxide. There are cleaning solutions containing acids.

  Laboratory atmosphere conditions are under air and open to air. The wet cleaning reactor 463 can be integrated into the laboratory atmosphere transfer module 460 in the process flow 400, but this process step is performed immediately after metal CMP and before the substrate is brought into the integrated system for cobalt alloy deposition. You can also Alternatively, the wet cleaning process can be performed in a controlled atmosphere process environment where the controlled environment is maintained during and after the wet cleaning step.

Organic residues that were not removed by the previous wet clean (ie, contaminants) can be removed by dry oxidation plasma processes such as oxygen-containing plasma, O ₂ / Ar sputtering, or Ar sputtering following removal of Cu-BTA and metal oxides. Can be removed. As mentioned above, most plasma or sputtering processes are operated at less than 1 Torr. Accordingly, it is desirable to couple such a system (or apparatus or chamber or module) to a transfer module that is operated under a vacuum, such as a pressure of less than 1 Torr. If the transfer module integrated with the plasma process is under vacuum, there is no need to spend a long time to evacuate the transfer module, so the time efficiency of substrate transfer is high and the process module is kept under vacuum . Also, since the transfer module is under vacuum, the substrate after being cleaned by the plasma process need only be exposed to extremely low levels of oxygen. Assuming an O ₂ plasma process is selected to clean the organic residue, the O ₂ plasma process reactor 471 is coupled to the vacuum transfer module 470.

  Since the laboratory atmosphere transfer module 460 is operated in air and the vacuum transfer module 470 is operated under vacuum (<1 Torr), there are two modules operating under different pressures between these two transfer modules. A load lock 465 is provided to allow the substrate 455 to be transported between 460 and 470. The load lock 465 is configured to operate under a vacuum at a pressure of less than 1 torr, to operate in a laboratory atmosphere, or to be filled with an inert gas selected from the group consisting of inert gases. Is done.

For example, after the oxidation plasma treatment using O ₂ is finished, the substrate 455 is moved to the hydrogen-containing reduction plasma reduction chamber (or module) 473. Since the reduction with a hydrogen-containing plasma is generally processed at a low pressure of less than 1 Torr, the chamber is coupled to a vacuum transfer module 470. When the substrate 455 is reduced by the hydrogen-containing plasma, the copper surface becomes clean with no copper oxide. In a preferred embodiment, after the substrate 455 has completed the O ₂ plasma treatment, an H ₂ or H ₂ / NH ₃ plasma reduction step can be performed in-situ without removing the wafer from the chamber. In any case, after completion of the reduction process, the substrate is ready for cobalt alloy deposition.

  As mentioned above, it is important to control the processing and transport environment to minimize exposure of the copper surface to oxygen after reconditioning of the substrate with a hydrogen-containing reducing plasma. The substrate 455 is preferably processed in a controlled environment, which is under vacuum or filled with one or more inert gases to limit exposure of the substrate 455 to oxygen. Either. Dashed line 490 indicates the boundaries of the parts of the processing system and transfer module whose environment is controlled in integrated system 450 of FIG. 4B. Transport and processing under the control environment 490 limits the exposure of the substrate to oxygen.

Electroless deposition of cobalt alloys is a wet process with in-solution cobalt species reduced by a reducing agent. Here, the reducing agent may be phosphorus based (eg hypophosphite), boron based (eg dimethylamine borane), or phosphorus based and boron based. It may be a combination of A solution using a phosphorus-based reducing agent deposits CoWP. A solution using a boron-based reducing agent deposits CoWB. A solution using both a phosphorus-based reducing agent and a boron-based reducing agent deposits CoWBP. In one embodiment, the cobalt alloy electroless deposition solution is based on alkalinity. Alternatively, the cobalt alloy electroless deposition solution may be acidic. Since wet processes are typically performed under atmospheric pressure, it is desirable that the transfer module 480 coupled to the electroless deposition reactor be operated at near atmospheric pressure. To ensure that the environment is controlled so as not to contain oxygen, an inert gas can be used to fill the controlled atmosphere transport module 480. Also, all fluids used in the process have been degassed by a commercial degassing system, i.e., dissolved oxygen has been removed. Typical inert gases include nitrogen (N ₂ ), helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

  In one embodiment, a rinsing and drying system (to allow dry-in / dry-out) to be transferred into and out of the electroless deposition system 481 under dry conditions (dry-in / dry-out). Or an apparatus or module) is coupled to the wet cobalt alloy electroless deposition reactor (or apparatus or system or module). The dry-in / dry-out requirement allows the electroless deposition system 481 to be integrated into the controlled atmosphere transfer module 480 and avoids the need for a robotic wet transfer step to a separate rinse drying module. The environment of the electroless deposition system 481 also needs to be controlled to reduce (or limit) oxygen and moisture (water vapor) levels. The system can also be filled with an inert gas to ensure that oxygen in the processing environment is at a low level.

  Alternatively, cobalt alloy electroless deposition can be performed in a dry-in / dry-out manner, similar to the recently disclosed electroless copper deposition. A dry-in / dry-out electroless copper process has been developed for the electroless deposition of copper. The process uses a proximity process head to bring the electroless process liquid into contact with a limited area on the substrate surface. The substrate surface in the area not under the proximity process head is dry. Details of such processes and systems have been filed on June 27, 2003, “Apparatus And Method For Depositing And Planarizing Thin Films On Semiconductor Wafers”. No. 10 / 607,611 entitled “Apparatus And Method For Plating Semiconductor Wafers” filed June 28, 2004. US application Ser. No. 10 / 879,263. Both of these applications are incorporated herein in their entirety. Electroless plating of cobalt alloys can use similar proximity process heads to enable dry-in / dry-out processes.

  After cobalt alloy deposition in system 481, substrate 455 can be passed through an optional post-deposition cleaning reactor. This can be done with mechanical aids such as brush scrubs using chemicals such as CP72B or hydroxyamine based cleaning chemicals, or by immersion, spin rinse, or C3 ™ proximity. Other methods such as technology can be used. In order to allow dry-in / dry-out of the substrate 455 to the wet cleaning system 483, it is also necessary to integrate a rinse and dry system into the brush scrub system. In order to ensure that the oxygen present in the system 483 is limited (or low), the system 483 is filled using an inert gas. As described above in FIG. 4A, since post-deposition cleaning is optional, system 483 is shown in dashed lines to indicate that this system is optional. Since the post-deposition cleaning step is a final process operated by the integrated system 450, the substrate 455 needs to be returned to the cassette 461 after processing. Accordingly, the cleaning system 483 can alternatively be coupled to a laboratory atmosphere transfer module 460 as shown in FIG. 4B. When coupled to the laboratory atmosphere transfer module 460, the cleaning system 483 is not operated in a controlled environment and need not be filled with an inert gas.

  As described above, the process step of removing Cu-BTA and metal oxide can also be performed immediately after metal CMP and before the substrate is brought into the integrated system for cobalt alloy deposition.

Case II: Metal CMP Stops on Barrier Layer FIGS. 5A-5C show cross sections of the wiring structure at various stages of processing. The copper layer on the substrate of FIG. 5A has been planarized by CMP. The barrier layer 130 has not been removed and remains on the substrate surface. FIG. 6A illustrates one embodiment of a surface conditioning process flow for electroless deposition of a cobalt alloy over copper in a dual damascene metal trench. The substrate used in the process flow 600 of FIG. 6A has just finished the copper CMP process to remove copper. As shown in FIG. 5A, the barrier layer still remains on the substrate surface. The difference between Case II and Case I is that in Case II the surface of dielectric 106 is not exposed to Cu-BTA complex or other copper compound residues. The dielectric surface is of higher quality in case II than in case I (i.e. less metal contamination). Thus, process steps aimed at removing copper oxide on the dielectric layer formed after O ₂ plasma is used to remove organic contaminants can be eliminated.

  The process begins at step 601 where metal contaminants such as Cu-BTA or metal oxide are removed from the substrate surface. As mentioned above, Cu-BTA complexes and metal oxides are the two major surface metal contaminants to be removed. The processes used to remove metal contaminants such as Cu-BTA and metal oxides from the substrate surface have been described above. For example, Cu-BTA and metal oxides including copper oxide can be removed by a wet cleaning process with a cleaning solution including, for example, tetramethylammonium hydroxide (TMAH) or a complexing amine such as ethylenediamine or diethylenetriamine. The removal of Cu-BTA eliminates the pattern-dependent deposition effect of the cobalt alloy (to be deposited in a later step) and thus allows the cobalt alloy to be deposited uniformly within the dense isolation features. To do.

  Metal oxides, more specifically copper oxides, can be removed using weak organic acids such as citric acid, or other organic or inorganic acids can be used. Also very thin (ie <0.1%) peroxide-containing acids such as sulfur-peroxide mixtures can be used. The wet cleaning process can also remove other metal residues or metal oxide residues.

Organic contaminants including BTA remaining on the Cu and barrier surfaces are removed in step 602. Organic contaminants can be removed by processes such as dry oxygen (O ₂ ) plasma processes, or other oxidizing plasma processes such as plasma processes with H ₂ O, ozone, or hydrogen peroxide vapor. As mentioned above, the oxygen-containing plasma process is preferably performed at a relatively low temperature of less than 50 degrees Celsius, preferably less than 120 degrees Celsius. The oxygen-containing plasma process may be a downstream plasma process. Alternatively, organic residues (ie, contaminants) can be removed using an O ₂ / Ar sputtering process to physically remove organic contaminants. As mentioned above, the O ₂ plasma process and the O ₂ / Ar sputtering process are generally operated at less than 1 Torr.

When the substrate surface is free of contaminants such as Cu-BTA, metal oxides, and organic contaminants, the substrate may be exposed to as little oxygen as possible to protect the copper surface from further oxidation. desirable. After the surface contaminants are removed, as shown in FIG. 5B, in step 603, a barrier layer such as Ta, TaN, Ru, or a combination of these materials is removed from the substrate surface. The barrier layer can be removed by processes such as CF ₄ plasma, O ₂ / Ar sputtering, CMP, or by wet chemical etching. Both the CF ₄ plasma etch process and the O ₂ / Ar sputtering process are operated at less than 1 Torr.

  The copper oxide present on the copper surface 140 of FIG. 5A and the copper oxide produced during the plasma oxidation step will be completely removed during the barrier metal removal step 603. Thus, the process of reducing the copper surface using H-containing plasma is optional. However, to ensure that there is no copper oxide on the copper surface, the substrate surface can be (optionally) reduced in step 605 to convert any residual copper oxide to copper. Reduction of the copper surface can be accomplished by a hydrogen-containing plasma process to reduce copper oxide to copper. The process gas and process conditions used by the hydrogen-containing plasma process are described above in Case I. After undergoing a hydrogen reduction process, the substrate is ready for cobalt alloy deposition. The copper surface needs to be carefully protected from oxygen to ensure that no copper oxide is formed. As described above, electroless deposition of cobalt alloys can be inhibited by the presence of copper oxide. It is therefore important to control the processing and transport environment to minimize or eliminate exposure of the copper surface to oxygen.

  In a next process step 607, a cobalt alloy such as CoWP, CoWB or CoWBP is electrolessly deposited on the copper surface. The cobalt alloy is shown as layer 135 in FIG. 5C. Electroless deposition of cobalt alloys is a selective deposition and a wet process. Cobalt alloys are deposited only on the copper surface.

  As described above for Case I, after electroless deposition of the cobalt alloy, the process flow can enter an optional post-deposition cleaning process step 609. Post-deposition cleaning is a solution containing CP72B supplied by Air Products and Chemical, Inc. of Allentown, PA to remove any metal contaminants introduced on the dielectric surface by an electroless deposition process. Can be performed using brush scrubbing with a chemical solution such as, or with a chemical agent based on hydroxyamine. Other substrate surface cleaning processes can also be used.

  As mentioned above, environmental control is very important for conditioning the copper surface for cobalt alloy deposition, particularly after H-containing plasma reduction of the copper surface. FIG. 6B shows a schematic diagram of an exemplary integrated system 650 that can minimize exposure of the substrate surface to oxygen at key steps after surface treatment. The integrated system 650 can be used to process the substrate throughout the process procedure of the flow 600 of FIG. 6A.

  Similar to the integrated system 450, the integrated system 650 includes three substrate transfer modules 660, 670, 680. The transfer modules 660, 670, 680 are equipped with a robot for moving the substrate 655 from one process area to another. The substrate transfer module 660 is operated in a laboratory atmosphere. Module 660 functions in conjunction with substrate loader (or substrate cassette) 661 to bring substrate 655 into the integrated system or to return the substrate to cassette 661 for further processing outside system 650.

  As described above in the process flow 600, the substrate 655 is planarized by copper CMP to remove excess copper from the substrate surface, as shown in FIG. 5A, and the barrier on the dielectric surface. After leaving the layer and copper in the metal trench, it is brought into the integrated system 650 to deposit a cobalt alloy such as CoWB, CoWP, or CoWBP. As described in step 601 of process flow 600, the substrate surface needs to be cleaned of surface contaminants such as Cu-BTA, metal oxides, and organic residues. Cu-BTA and metal oxides can be removed by a wet cleaning process with a cleaning solution such as a solution containing TMAH. The wet cleaning reactor 663 can be integrated into the laboratory atmosphere transfer module 660. The wet clean reactor 663 can be integrated into the laboratory atmosphere transfer module 660 in the process flow 600, but this process step is performed immediately after metal CMP and before the substrate is brought into the integrated system for cobalt alloy deposition. You can also Alternatively, the wet cleaning process can be performed in a controlled atmosphere process environment where the controlled environment is maintained during and after the wet cleaning step.

Organic residues (ie, contaminants) that have not been removed by the wet cleaning process 601 performed in the reactor 683 may be removed in step 602 by a dry plasma process such as O ₂ plasma, or O ₂ / Ar sputtering. it can. As mentioned above, most plasma or sputtering processes are operated at less than 1 Torr. It is therefore desirable to couple such a system to a transfer module that is operated under a vacuum, such as a pressure of less than 1 Torr. Assuming an O ₂ plasma process is selected to clean the organic residue, the O ₂ plasma process reactor 671 is coupled to the vacuum transfer module 670.

The O ₂ plasma process may be a downstream plasma process. The O ₂ plasma reactor 671 can be integrated into the vacuum transfer module 670 in the process flow 600, but this process step is performed immediately after metal CMP and before the substrate is brought into the integrated system for cobalt alloy deposition. You can also

  Since the laboratory atmosphere transfer module 660 is operated under air and the vacuum transfer module 670 is operated under vacuum (<1 Torr), between these two transfer modules is between the two modules 660 and 670. The load lock 665 is disposed so that the substrate 655 can be transported.

After finishing the O ₂ plasma treatment, the substrate 655 is moved to a processing system for barrier layer etching, as shown in step 603. If a dry barrier plasma etch process is selected, the barrier layer etch chamber (or module) 673 can be coupled to the vacuum transfer module 670. The dry barrier plasma process may be a CF ₄ plasma process or an O ₂ / Ar sputtering process.

The process following the etching of the barrier layer is an optional H-containing plasma reduction to ensure that no copper oxide remains on the copper surface. H ₂ plasma reduction can be performed in a plasma chamber (or module) 674 coupled to a vacuum transfer module 670. Alternatively, the hydrogen plasma reduction can be continued after purging the remaining oxygen species in the O ₂ plasma reactor 671 used to remove organic residues.

  As mentioned above, electroless deposition of cobalt alloys is a wet chemical process. Since wet processes are typically performed at atmospheric pressure, it is desirable that the transfer module 680 coupled to the electroless deposition reactor be operated at near atmospheric pressure. To ensure that the environment is controlled so that it does not contain oxygen, an inert gas can be used to fill the controlled atmosphere transport module 680. Also, all fluids used in the process have been degassed by a commercial degassing system, i.e., dissolved oxygen has been removed.

  In order to allow the substrate to be transferred into and out of the electroless deposition system 681 under dry conditions (dry-in / dry-out), the wet cobalt alloy electroless deposition reactor is rinsed and It is necessary to combine the drying system. As described above, the dry-in / dry-out requirement allows the electroless deposition system 681 to be integrated into the controlled atmosphere transfer module 680. System 681 is filled using an inert gas to ensure that a low (or limited or controlled) oxygen level is maintained therein.

  After cobalt alloy deposition in system 681, substrate 655 can be passed through a post-deposition cleaning reactor 683. In order to allow dry-in / dry-out of the substrate 655 to the wet cleaning system 683, it is also necessary to integrate a rinse and dry system into the brush scrub system. To ensure that no oxygen is present, the system 683 is filled using an inert gas. As described above in FIG. 6A, since post-deposition cleaning is optional, system 683 is shown in dashed lines to indicate that this system is optional. Since the post-deposition cleaning step is a final process operated by the integrated system 650, the substrate 655 needs to be returned to the cassette 661 after processing. The cleaning system 683 can alternatively be coupled to the laboratory atmosphere transfer module 660.

Case III: Metal CMP Stops on Thin Copper Layer FIGS. 7A-7C show cross sections of the wiring structure at various stages of wiring processing. The substrate of FIG. 7A has just been planarized with copper, but the copper has not been completely removed from the substrate. A thin copper layer 132 remains on the substrate surface. FIG. 8A illustrates one embodiment of a surface conditioning process flow for electroless deposition of a cobalt alloy on copper in a dual damascene metal trench. The substrate used in the process flow 800 of FIG. 8A has just completed a copper CMP process to remove most of the copper above the barrier layer above the dielectric layer. As shown in FIG. 7A, a thin copper layer in the range of about 100 angstroms to about 1000 angstroms remains on the barrier surface. The difference between Case III and both Case II and Case I is that, in Case III, a thin copper layer covers the entire substrate surface and, therefore, copper galvanic due to dissimilar materials exposed in the copper CMP solution. There is no concern about corrosion. Thin copper layers and other surface contaminants present are removed in an oxygen-free environment, so there is no concern for copper oxidation. Therefore, H ₂ plasma reduction is not necessary. Case II and Case III both have no barrier CMP, thus reducing the cost of metal CMP processing. The copper surface conditioned by this process can improve the selectivity of the cobalt alloy on the dielectric layer to copper.

The process begins at step 801 where contaminants including organic residues and inorganic metal oxides are removed from the substrate surface. Organic contaminants can be removed by oxidizing plasma, such as dry oxygen (O ₂ ) plasma process, H ₂ O plasma process, H ₂ O ₂ plasma process, or plasma with ozone vapor. As mentioned above, the O ₂ plasma process is preferably performed at a relatively low temperature of less than 120 degrees Celsius. The O ₂ plasma process may be a downstream plasma process. Alternatively, organic residues (ie, contaminants) can be removed using an O ₂ / Ar sputtering process to physically remove organic contaminants. As mentioned above, the O ₂ plasma process and the O ₂ / Ar sputtering process are generally operated at less than 1 Torr.

When the substrate surface is free of contaminants, it is desirable that the substrate be exposed to as little oxygen as possible to protect the copper surface from oxidation. After the surface contaminants are removed, in step 803, the thin copper layer over the barrier layer and dielectric layer is removed. Thin copper layers can be obtained by O ₂ / Ar sputtering, by O ₂ / hexafluoroacetylacetone (HFAC) plasma etching, by wet chemical etching using chemicals such as sulfuric acid and hydrogen peroxide, or by using complexing chemicals Can be removed. Both the O ₂ / Ar sputtering process and the O ₂ / HFAC plasma process are operated under low pressure, such as less than 1 Torr.

Thereafter, in step 805, a barrier layer such as Ta, TaN, or a combination of both films is removed from the substrate surface. A cross-section of the wiring structure after removing the thin copper and barrier is shown in FIG. 7B. The barrier layer can be removed by CF ₄ plasma, O ₂ / Ar sputtering, CMP, or wet chemical etching. Both the CF ₄ plasma etch process and the O ₂ / Ar sputtering process are operated at less than 1 Torr.

  The copper surface for selectively depositing the cobalt alloy is formed by etching a thin copper layer and barrier layer from above the dielectric in a controlled atmosphere environment, so that the copper surface is formed using H-containing plasma. The process of reducing is almost unnecessary. However, to ensure that there is no copper oxide on the copper surface, the substrate surface can optionally be reduced in step 807 to convert any residual copper oxide to copper. The copper surface reduction process has been described above. After undergoing a hydrogen reduction process, the substrate is ready for cobalt alloy deposition. The copper surface needs to be carefully protected to prevent copper oxide formation. In a next process step 809, a cobalt alloy such as CoWP, CoWB, or CoWBP is electrolessly deposited on the copper surface. The cobalt alloy is shown as layer 135 in FIG. 7C. Electroless deposition of cobalt alloys is a selective deposition and a wet process. Cobalt alloys are deposited only on the copper surface.

  As described above for Case I and Case II, after electroless deposition of the cobalt alloy, the process flow can enter an optional post-deposition cleaning process step 811. Post-deposition cleaning is described above in Case I and Case II.

  As mentioned above, environmental control is very important for conditioning the copper surface for cobalt alloy deposition, particularly after H-containing plasma reduction of the copper surface. FIG. 8B shows a schematic diagram of an exemplary integrated system 850 that can minimize exposure of the substrate surface to oxygen at key steps after surface treatment. The integrated system 850 can be used to process the substrate throughout the process sequence of the flow 800 of FIG. 8A.

  The integrated system 850 includes three substrate transfer modules 860, 870, and 880. The transfer modules 860, 870, and 880 are equipped with a robot for moving the substrate 855 from one process area to another process area. The substrate transfer module 860 is operated in a laboratory atmosphere. Module 860 functions in conjunction with substrate loader (or substrate cassette) 861 to bring substrate 855 into the integrated system or to return the substrate to cassette 861 to continue processing outside system 850.

  As described above in process flow 800, the substrate 855 is planarized by copper CMP to remove excess copper from the substrate surface, as shown in FIG. 7A, and a barrier layer over the dielectric surface. After leaving a thin copper layer on top, it is brought into the integrated system 850 to deposit a cobalt alloy such as CoWB, CoWP, or CoWBP. As described in step 801 of process flow 800, the substrate surface needs to be cleaned of surface contaminants such as organic residues and non-copper metal oxides. In contrast to Case I and Case II, there is no need to perform wet Cu-BTA cleaning, so the laboratory atmosphere transfer module 860 can be eliminated and the cassette holder 861 can be directly coupled to the load lock 865. It will be possible.

Surface contaminants including organic residues and metal oxides can be removed by oxidizing plasma processes such as O ₂ plasma or O ₂ / Ar sputtering. As mentioned above, most plasma or sputtering processes are operated at less than 1 Torr. It is therefore desirable to couple such a system to a transfer module that is operated under a vacuum, such as a pressure of less than 1 Torr. Assuming an O ₂ plasma process is selected to clean the organic residue, the O ₂ plasma process reactor 871 is coupled to the vacuum transfer module 870.

The O ₂ plasma process may be a downstream plasma process. The O ₂ plasma reactor 871 can be integrated into the vacuum transfer module 870 in the process flow 800, but this process step is performed immediately after metal CMP and before the substrate is brought into the integrated system for cobalt alloy deposition. You can also

  Since the laboratory atmosphere transfer module 860 is operated under air and the vacuum transfer module 870 is operated under vacuum (<1 Torr), there is a gap between the two modules 860 and 870 between these two transfer modules. The load lock 865 is arranged so that the substrate 855 can be transported.

After finishing the O ₂ plasma treatment, the substrate 855 is moved to a processing system for copper etching, as shown in step 803. A copper etch chamber (or module) 873 is coupled to the vacuum transfer module 870 when a dry copper plasma etch process is selected. If a wet process is selected, the wet copper etch reactor can be integrated with a rinse / dry system to form a wet copper etch system 873 ′ and coupled to the controlled atmosphere transfer module 880. To allow the wet copper etch system 873 ′ to be integrated with the controlled atmosphere transfer module 880, substrate dry-in and dry-out to the system 873 ′ is required. In one embodiment, a rinsing and drying system can be incorporated into the wet copper etch system 873 ′ to meet dry-in / dry-out requirements. The environment of system 873 'also needs to be controlled to be free of oxygen. An inert gas can also be used to fill the system to ensure that there is no oxygen in the processing environment.

  As shown in step 805, the copper etch is followed by a barrier layer etch. If a dry barrier plasma etch process is selected, the barrier layer etch chamber 874 can be coupled to the vacuum transfer module 870. If a wet barrier etch process is selected, the wet barrier etch reactor may be integrated with a rinse / dry system to form a wet barrier etch system 874 'and coupled to the controlled atmosphere transfer module 880. In order to allow the wet barrier etch system 874 'to be integrated with the controlled atmosphere transfer module 880, substrate dry-in and dry-out to the system 874' is required. The environment of system 874 'also needs to be controlled to reduce (or limit or control) the level of oxygen. An inert gas can also be used to fill the system to ensure that oxygen in the processing environment is at a low level.

The process following the barrier layer etch is an optional H-containing plasma reduction as described above. H ₂ plasma reduction can be performed in a plasma chamber 877 coupled to a vacuum transfer module 870.

As mentioned above, the electroless deposition of cobalt alloy is a wet process. Since wet processes are typically performed under atmospheric pressure, it is desirable that the transfer module 680 coupled to the electroless deposition reactor be operated at near atmospheric pressure. To ensure that the environment is controlled so that the oxygen level is low, an inert gas can be used to fill the controlled atmosphere transport module 880. Also, all fluids used in the process have been degassed by a commercial degassing system, i.e., dissolved oxygen has been removed. Typical inert gases include nitrogen (N ₂ ), helium (He), neon (Ne), argon (Ar), krypton (Kr), and xenon (Xe).

  In order to allow the substrate to be transferred into and out of the electroless deposition system 881 under dry conditions (dry-in / dry-out), the wet cobalt alloy electroless deposition reactor is rinsed and It is necessary to combine the drying system. The dry-in / dry-out requirement allows the electroless deposition system 881 to be integrated into the controlled atmosphere transfer module 880. System 881 is filled using an inert gas to ensure that the oxygen present therein is at a low level.

  After cobalt alloy deposition in system 881, substrate 855 can be passed through a post-deposition cleaning reactor. In order to allow the substrate 855 to dry-in / dry-out with respect to the wet cleaning system 883, it is also necessary to integrate a rinse and dry system into the brush scrub system. To ensure that no oxygen is present, the system 883 is filled using an inert gas. As described above in FIG. 8A, since post-deposition cleaning is optional, system 883 is shown in dashed lines to indicate that this system is optional. Since the post-deposition cleaning step is a final process operated by the integrated system 850, the substrate 855 needs to be returned to the cassette 861 after processing. The cleaning system 883 can alternatively be coupled to the laboratory atmosphere transfer module 860.

2. Barrier surface design for electroless copper deposition:
The system concept described above can be used to condition the barrier surface for copper plating. Barrier layers such as Ta, TaN, or Ru form Ta _x O _y (tantalum oxide), TaO _x N _y (tantalum oxynitride), or RuO ₂ (ruthenium oxide) when exposed to air for extended periods of time. There is a fear. Electroless deposition of a metal layer on a substrate is highly dependent on the surface properties and composition of the substrate. Electroless plating of copper on Ta, TaN, or Ru surfaces is a concern for both the formation of a seed layer prior to electroplating and the selective deposition of Cu lines in a lithographically defined pattern. is there. One concern is that the electroless deposition process is suppressed by an atomically thin layer of native metal oxide formed in the presence of oxygen (O ₂ ).

  In addition, the copper film does not adhere to a barrier oxide layer such as tantalum oxide, tantalum nitride oxide, or ruthenium oxide, but is pure barrier metal film or barrier layer rich such as Ta film, Ru film, or Ta-rich TaN film. Adhere to the membrane. Ta and / or TaN barrier layers are only used as examples. The description and concept apply to other types of barrier metals such as Ta or TaN coated with a thin layer of Ru. As mentioned above, poor adhesion can adversely affect EM resistance. In addition, the formation of tantalum oxide or tantalum oxynitride on the barrier layer surface may increase the resistivity of the barrier layer. Because of these problems, it is desirable to use an integrated system to tune the barrier / copper interface to ensure good adhesion between the barrier layer and copper and to ensure a low barrier layer resistivity.

Case I: Metal Line Formation FIG. 9A shows a typical cross section of a metal line structure after patterning by dielectric etching and removal of the photoresist. The metal line structure is on a substrate 900 and has a silicon layer 110 with a gate oxide 121, a spacer 107, and a gate structure 105 with contacts 125 formed therein in advance. Contact 125 is typically made by etching a contact hole in oxide 103 and then filling the contact hole with a conductive material such as tungsten. Alternative materials include copper, aluminum, or other conductive materials. The barrier layer 102 is also configured to function as a selective trench etch stop. The barrier layer 102 can be made of a material such as silicon nitride (SiN) or silicon carbide (SiC).

  A metal line dielectric layer 106 is deposited over the barrier layer 102. Dielectric materials that can be used for the deposition of 106 are described above. After deposition of dielectric layer 106, the substrate is patterned and etched to form metal trenches 106. FIG. 9B shows that after formation of the metal trench 116, a metal barrier layer 130 is deposited to line the metal trench 116. FIG. 9C shows that after the barrier layer 130 is deposited, a copper layer 132 is deposited over the barrier layer 130. The barrier layer 130 can be made of tantalum nitride (TaN), tantalum (Ta), Ru, or a combination of these films. A copper film 132 is then deposited to fill the metal trench 116. In one embodiment, the copper film 132 includes a thin copper seed layer 131 below it.

  After conditioning the catalyst surface for deposition of the conformal thin copper seed layer 131 using plasma surface pretreatment and filling the trench 116 with the copper film 132, the substrate 900 is as shown in FIG. Chemically and mechanically polished (CMP) or wet etched to remove copper material (ie excess copper) and barrier layer (ie excess barrier) on the surface of dielectric 106 . In one embodiment, the thickness of the thin copper seed layer is between about 5 angstroms and about 300 angstroms. The next step is to cover a copper surface 140 with a copper / SiC interface adhesion promoting layer 135, such as a cobalt alloy, as shown in FIG. 9E. Examples of cobalt alloys include CoWP, CoWB, or CoWBP that can be selectively deposited on copper by an electroless process. The thickness of the adhesion promoting layer can be as thin as a monolayer of only a few angstroms, such as 5 angstroms, to a thicker layer, such as 200 angstroms.

FIG. 10A illustrates one embodiment of a process flow 1000 for conditioning a barrier (or liner) layer surface for electroless copper deposition after a trench is formed. However, the barrier (or liner) layer may be tailored in a non-integrated deposition system such as an ALD deposition reactor or a PLD deposition reactor. In this case, the surface conditioning to deposit a thin copper seed layer would not include the metal plug pre-clean and barrier deposition process steps. In step 1001, the contact plug top surface 124a is cleaned to remove native metal oxide. The metal oxide is removed by an Ar sputtering process or a plasma process using a fluorine-containing gas such as NF ₃ , CF ₄ , or a combination of both, or a wet chemical etching process, or a reduction process using, for example, a hydrogen-containing plasma can do. In step 1003, a barrier layer is deposited. Due to the reduction in metal line and via critical dimensions, the barrier layer can be deposited by atomic layer deposition (ALD), depending on the technology node. The thickness of the barrier layer 130 is between about 20 angstroms and about 200 angstroms. As mentioned above, preventing exposure of the barrier layer to oxygen is important to ensure that the copper is electrolessly deposited on the barrier layer in a manner that provides excellent adhesion to the barrier layer. Once the barrier layer is deposited, the substrate is desirably transported or processed in a controlled atmosphere environment to limit exposure to oxygen. The barrier layer is subjected to a hydrogen plasma treatment to form a metal-rich surface on the Ta, TaN, or Ru layer in optional step 1005 to provide a catalytic surface for a subsequent copper seed deposition step. Is done. Whether this step is necessary depends on how metal-rich the surface is.

  Thereafter, in step 1007, a conformal copper seed is deposited on the barrier surface, and in step 1008, a thick copper gap filling (or bulk filling) process is followed. In one embodiment, the conformal copper seed layer can be deposited by an electroless process. The thick copper bulk filling process may be an electroless deposition (ELD) process or an electroplating (ECP) process. Electroless copper deposition and ECP are well known wet processes. In order to integrate a wet process into a system with a controlled processing and transport environment as described above, it is necessary to integrate the reactor into a rinse / dryer to enable dry-in / dry-out process capabilities. The system also needs to be filled with an inert gas to ensure minimal exposure of the substrate to oxygen. In recent years, dry-in / dry-out electroless copper processes have been developed. In addition, all fluids used in the process have been degassed by a commercial degassing system, i.e., dissolved oxygen has been removed.

  The electroless deposition process can be performed in a number of ways, such as paddle plating. In paddle plating, a fluid is supplied onto a substrate and the reaction is allowed to proceed in a stationary state. The reactant is then removed and discarded or regenerated. In another embodiment, the process uses a proximity process head to bring the electroless process liquid into contact with a limited area on the substrate surface. The substrate surface in the area not under the proximity process head is dry. Details of such processes and systems were filed on June 27, 2003, “Apparatus And Method For Depositing And Planarizing Thin Films On Semiconductor Wafers”. United States Application No. 10 / 607,611 entitled "Apparatus And Method For Plating Semiconductor Wafers" filed June 28, 2004 Application 10 / 879,263 can be found. Both of these applications are incorporated herein in their entirety. The aforementioned electroless plating of cobalt alloys can enable a dry-in / dry-out process using a similar proximity process head.

  After copper deposition in steps 1007 and 1008, the substrate may undergo optional substrate cleaning in step 1009. Cleaning after copper deposition can be accomplished using brush scrub cleaning with a chemical solution such as a solution containing CP72B supplied by Air Products and Chemical, Inc. of Allentown, Pa. Other substrate surface cleaning processes such as Lam's C3 ™ or P3 ™ cleaning techniques can also be used.

  FIG. 10B illustrates one embodiment of a schematic diagram of an integrated system 1050 that can minimize exposure of the substrate surface to oxygen after barrier surface conditioning. Also, since this is an integrated system, the substrate is immediately transferred from one process station to the next, which limits the time that clean copper surfaces are exposed to low levels of oxygen. The integrated system 1050 can be used to process a substrate throughout the process sequence of the flow 1000 of FIG. 10A.

  As mentioned above, surface conditioning for the electroless deposition of copper, and the optional post-cobalt alloy deposition process, involves a mix of dry and wet processes. Wet processes are generally operated in the near atmosphere and dry plasma processes are operated at less than 1 Torr. Thus, the integrated system needs to be able to handle a mix of dry and wet processes. The integrated system 1050 includes three substrate transfer modules 1060, 1070, and 1080. The transfer modules 1060, 1070, and 1080 are equipped with a robot for moving the substrate 1055 from one process area to another process area. The process area may be a substrate cassette, a reactor, or a load lock. The substrate transfer module 1060 is operated in a laboratory atmosphere. The module 1060 functions in conjunction with a substrate loader (or substrate cassette) 1061 to bring the substrate 1555 into the integrated system or return the substrate to one of the cassettes 1061.

  As described above in process flow 1000, substrate 1055 is brought into integrated system 1050 to deposit a barrier layer and a copper layer. As described in step 1001 of process flow 1000, tungsten top surface 124a of contact 125 is etched to remove native tungsten oxide. When the tungsten oxide is removed, the exposed tungsten surface 124a of FIG. 9A needs to be protected from exposure to oxygen. If the removal process is an Ar sputtering process, the reactor 1071 is coupled to a vacuum transfer module 1070. If a wet chemical etching process is selected, the reactor should be coupled to the controlled atmosphere transfer module 1080, not the laboratory atmosphere transfer module 1060, to limit the exposure of the tungsten surface to oxygen. Is desirable.

The substrate is then deposited with a metal barrier layer, such as Ta, TaN, Ru, or a combination of these films, as described in step 1003 of FIG. 10A. The barrier layer 130 of FIG. 9B can be deposited by an ALD process or a PVD process. In one embodiment, the ALD process is operated at less than 1 Torr. ALD reactor 1073 is coupled to vacuum transfer module 1070. In another embodiment, the deposition process is a high pressure process that uses supercritical CO ₂ and an organometallic precursor to form a metal barrier. In yet another embodiment, the deposition process is a physical vapor deposition (PVD) process that operates at a pressure of less than 1 Torr. Details of a typical reactor for a high pressure process using supercritical CO ₂ were filed on February 3, 2003, “Method and Apparatus For Semiconductor Wafer Cleaning Using High-Frequency Acoustic Energy with Supercritical Fluid. No. 10 / 357,664 by the same applicant entitled “Method and apparatus for semiconductor wafer cleaning using high frequency acoustic energy”. This application is hereby incorporated by reference.

  The substrate can undergo an optional reduction process using, for example, a hydrogen-containing plasma, as described in step 1005 of FIG. 10A. The hydrogen reduction reactor 1074 can be coupled to the vacuum transfer module 1070. At this stage, the substrate is ready for electroless copper deposition. Electroless copper plating can be performed by depositing a conformal seed layer in the electroless copper plating reactor 1081. Subsequent to seed layer deposition, copper bulk in the same electroless copper deposition reactor 1081 used for conformal seed layer deposition, but using different chemicals to achieve bulk filling. Filling can be performed. Alternatively, copper bulk filling can be performed in a separate ECP reactor 1081 '.

  Prior to leaving the integrated system 1050, the substrate can optionally undergo a surface cleaning process that can clean residues from previous copper deposition processes. For example, the substrate cleaning process may be a brush cleaning process. The substrate cleaning reactor 1083 can be integrated into the controlled atmosphere transfer module 1080. Alternatively, the substrate cleaning reactor 1083 can be integrated into the laboratory atmosphere transfer module 1060.

  Alternatively, the barrier layer 130 of FIG. 9B can be deposited in the process chamber before the substrate 900 is brought into the system for surface treatment and copper deposition. FIG. 10C illustrates one embodiment of a process flow 1090 for adjusting the barrier (or liner) layer surface for electroless copper deposition. The barrier surface is subjected to hydrogen plasma treatment to form a metal-rich surface on the Ta, TaN, or Ru layer in optional step 1095 to provide a catalytic surface for a subsequent copper seed deposition step. Is done. Whether this step is necessary depends on how metal-rich the surface is.

  Thereafter, in step 1097, a conformal copper seed is deposited on the barrier surface, and in step 1098, a thick copper gap filling (or bulk filling) process follows. In one embodiment, the conformal copper seed layer can be deposited by an electroless process. The thick copper bulk filling process may be an electroless deposition (ELD) process or an electroplating (ECP) process. After copper deposition in steps 1097 and 1098, the substrate may undergo optional substrate cleaning in step 1099. Cleaning after copper deposition can be accomplished using brush scrub cleaning with a chemical solution such as a solution containing CP72B supplied by Air Products and Chemical, Inc. of Allentown, Pa. Other substrate surface cleaning processes such as Lam's C3 ™ or P3 ™ cleaning techniques can also be used.

  FIG. 10D shows one embodiment of a schematic diagram of an integrated system 1092 that can minimize the exposure of the substrate surface to oxygen at key steps after barrier surface conditioning. Also, since this is an integrated system, the substrate is immediately transferred from one process station to the next, which limits the time that clean copper surfaces are exposed to low levels of oxygen. The integrated system 1092 can be used to process the substrate throughout the process procedure of the flow 1090 of FIG. 10C.

  As mentioned above, surface conditioning for the electroless deposition of copper, and the optional post-cobalt alloy deposition process, involves a mix of dry and wet processes. Wet processes are generally operated in the near atmosphere and dry plasma processes are operated at less than 1 Torr. Thus, the integrated system needs to be able to handle a mix of dry and wet processes. The integrated system 1092 includes three substrate transfer modules 1060, 1070, and 1080. The transfer modules 1060, 1070, and 1080 are equipped with a robot for moving the substrate 1055 from one process area to another process area. The process area may be a substrate cassette, a reactor, or a load lock. The substrate transfer module 1060 is operated in a laboratory atmosphere. The module 1060 functions in conjunction with a substrate loader (or substrate cassette) 1061 to bring the substrate 1555 into the integrated system or return the substrate to one of the cassettes 1061.

  As described above in process flow 1090, substrate 1055 is brought into integrated system 1092 to condition the barrier surface for electroless copper deposition after deposition of the barrier layer. The substrate first undergoes a reduction process using, for example, a hydrogen-containing plasma, as described in step 1095 of FIG. 10C. The hydrogen reduction reactor 1074 can be coupled to the vacuum transfer module 1070. At this stage, the substrate is ready for electroless copper deposition. Electroless copper plating can be performed by depositing a conformal seed layer in the electroless copper plating reactor 1081. Subsequent to seed layer deposition, copper bulk in the same electroless copper deposition reactor 1081 used for conformal seed layer deposition, but using different chemicals to achieve bulk filling. Filling can be performed. Alternatively, copper bulk filling can be performed in a separate ECP reactor 1081 '.

  Prior to leaving the integrated system 1092, the substrate can optionally undergo a surface cleaning process that can clean residues from previous copper deposition processes. For example, the substrate cleaning process may be a brush cleaning process. The substrate cleaning reactor 1083 can be integrated into the controlled atmosphere transfer module 1080. Alternatively, the substrate cleaning reactor 1083 can be integrated into the laboratory atmosphere transfer module 1060.

  FIG. 11A illustrates one embodiment of a process flow for adjusting the barrier (or liner) layer surface for electroless copper deposition and adjusting the post-CMP copper surface for electroless cobalt alloy deposition. In step 1101, the contact plug top surface 124a is cleaned to remove native tungsten oxide. The metal oxide can be removed by an Ar sputtering process, a plasma reduction process, a reactive ion etching process, or a wet chemical etching process. In step 1103, a barrier layer is deposited. The barrier layer is subjected to hydrogen plasma treatment to form a metal-rich surface on the Ta, TaN, or Ru layer in optional step 1005 to provide a catalytic surface for subsequent copper seed deposition steps. Is done. Whether this step is necessary depends on how metal-rich the surface is.

  However, the barrier (or liner) layer may be tailored in a non-integrated deposition system such as an ALD deposition reactor or a PLD deposition reactor. In this case, surface conditioning to deposit a thin copper seed layer does not include the metal plug pre-clean and barrier deposition process steps as described in steps 1001, 1003 of FIG. 10A and steps 1101, 1103 of FIG. 11A. it is conceivable that. In these cases, the described process begins at step 1005 or 1105.

  Thereafter, in step 1107, a conformal copper seed is deposited on the barrier surface, and in step 1108, a thick copper gap filling (or bulk filling) process follows. In one embodiment, the conformal copper seed layer can be deposited by an electroless process. The thick copper bulk filling process may be an electroless deposition process (ELD) or an electroplating (ECP) process. Electroless copper deposition and ECP are well known wet processes. In order to integrate a wet process into a system with a controlled processing and transport environment as described above, it is necessary to integrate the reactor into a rinse / dryer to enable dry-in / dry-out process capabilities. The system also needs to be filled with an inert gas to ensure minimal exposure of the substrate to oxygen. In recent years, dry-in / dry-out electroless copper processes have been developed. In addition, all fluids used in the process have been degassed by a commercial degassing system, i.e., dissolved oxygen has been removed.

In step 1107, a conformal copper seed is deposited on the substrate, and in step 1108, after thick Cu gap filling (bulk filling) by either an electroless process or an electrolytic plating process, as shown in FIG. 9D. In step 1109, the copper layer 132 is removed from the substrate surface above the barrier layer 130 above the dielectric 106. The barrier layer is then removed. Both of these removal processes are performed in process step 1109 of FIG. 11A. Removal of copper from the surface above the barrier layer can be achieved by CMP, a wet process. The barrier layer can be removed by reactive ion etching such as CF ₄ plasma, O ₂ / Ar sputtering, CMP, or wet chemical etching. These barrier etching processes have been described above.

  After removing the barrier layer, in order to remove contaminants from the substrate surface, a cleaning process for removing Cu-BTA complex and metal oxide (step 1110) and a process for removing organic contaminants (step 1111). And are carried out. Details of cleaning the substrate surface using these two steps after metal CMP are described above.

  After surface contaminants are removed from the substrate surface, the substrate is treated in step 1112 with a reduction plasma (hydrogen-containing plasma) to reduce any remaining metal oxide to metal. After hydrogen reduction, the copper surface is very clean and catalytic, ready for electroless deposition of cobalt alloys. In step 1113, the substrate undergoes electroless deposition of a cobalt alloy and rinsing and drying of the substrate. Final process step 1115 is an optional substrate cleaning step to clean any residual contaminants from previous electroless cobalt alloy depositions.

  FIG. 11B shows one embodiment of a schematic diagram of an integrated system 1150 that can minimize exposure of the substrate surface to oxygen at key steps after conditioning the barrier and copper surfaces. Also, since this is an integrated system, the substrate is immediately transferred from one process station to the next, which limits the time that clean copper surfaces are exposed to low levels of oxygen. The integrated system 1150 can be used to process the substrate throughout the process procedure of the flow 1100 of FIG. 11A.

  The integrated system 1150 includes three substrate transfer modules 1160, 1170, 1180. The transfer modules 1160, 1170, 1180 are equipped with a robot for moving the substrate 1155 from one process area to another process area. The process area may be a substrate cassette, a reactor, or a load lock. The substrate transfer module 1160 is operated in a laboratory atmosphere. Module 1160 functions in conjunction with a substrate loader (or substrate cassette) 1161 to bring substrates 1155 into the integrated system or to return substrates to one of cassettes 1161.

  As described above in the process flow 1100 of FIG. 11A, the substrate 1155 is a post-CMP copper for depositing a barrier layer, conditioning the barrier surface for copper layer deposition, and for electroless cobalt alloy deposition. Bringed into integrated system 1150 to condition the surface. As described in step 1101 of process flow 1100, metal plug top surface 124a of contact 125 is etched to remove native metal oxide. Alternatively, the oxide on the surface of the metal plug can be removed using a reducing plasma such as a hydrogen-containing plasma. When the oxide on the metal plug surface is removed, the exposed metal surface 124a of FIG. 9A needs to be protected from exposure to oxygen. If the removal process is an Ar sputtering process, the Ar sputtering reactor 1171 is coupled to the vacuum transfer module 1170. If a wet chemical etch process is selected, the reactor is coupled to a controlled atmosphere transfer module 1180 rather than a laboratory atmosphere transfer module 1160 to limit exposure of clean metal plug surfaces to oxygen. It is desirable that

The substrate is then deposited with a metal barrier layer, such as Ta, Ru, TaN, or a combination of these films, as described in step 1103 of FIG. 11A. The barrier layer 130 of FIG. 9B can be deposited by an ALD process or a PVD process. In one embodiment, the ALD process is operated at less than 1 Torr. The ALD reactor 1173 is coupled to the vacuum transfer module 1170. In another embodiment, the deposition process is a high pressure process that uses supercritical CO ₂ and an organometallic precursor to form a metal barrier. In yet another embodiment, the deposition process is a physical vapor deposition (PVD) process operated at a pressure of less than 1 Torr. The substrate can go through an optional reduction process using, for example, a hydrogen-containing plasma, as described in step 1105 of FIG. 11A. The hydrogen reduction reactor 1174 can be coupled to the vacuum transfer module 1170. At this stage, the substrate is ready for electroless copper deposition. Electroless copper plating can be performed by depositing a conformal seed layer in the electroless copper plating reactor 1181. Subsequent to seed layer deposition, copper bulk in the same electroless copper deposition reactor 1181 used for conformal seed layer deposition, but using different chemicals to achieve bulk filling. Filling can be performed. Alternatively, copper bulk filling can be performed in a separate ECP reactor 1181 '.

The substrate is then removed of excess copper and excess barrier as described in step 1109 of FIG. 11A. Excess copper and excess barrier removal may be implemented in one CMP system 1183 or may be implemented in two CMP systems. In the embodiment shown in FIG. 11A, only one CMP system 1183 is used. After CMP removal of excess copper and excess barrier, the substrate surface needs to be cleaned to remove surface contaminants. A wet cleaning system 1185 is used to remove the copper BTA complex and metal oxide. An O ₂ plasma system 1177 is used to remove organic contaminants. In one embodiment, an O ₂ plasma process for removing organic contaminants can be performed in the hydrogen reduction chamber 1174.

  After removal of the contaminants, the substrate undergoes a reduction process as described in step 1112 of FIG. 11A. The hydrogen reduction process can occur in the same reduction reactor 1174 that was used to reduce the barrier surface to become Ta-rich. Following the hydrogen reduction treatment, the copper surface is ready for electroless cobalt alloy deposition, which can be performed in reactor 1187.

  Prior to leaving the integrated system 1150, the substrate can optionally undergo a surface cleaning process that can clean residues from previous copper plating processes. The substrate cleaning process may be a brush cleaning process and the reactor 1163 may be integrated into the laboratory atmosphere transfer module 1160.

  Any of the wet processing systems described in FIG. 15B coupled to the controlled atmosphere transfer module 1180 must meet dry-in / dry-out requirements to allow system integration.

Case II: Dual Damascene Wiring Procedure FIG. 12A shows a representative cross section of the wiring structure after patterning by a dual damascene process. The wiring structure has an oxide layer 100 on a substrate 1200 and having a metallization line 101 formed therein in advance. Metallization lines are typically created by etching a trench in oxide 100 and then filling the trench with a conductive material such as copper.

  Within the trench is a barrier layer 120 that is used to prevent the copper material 122 from diffusing into the oxide 100. The barrier layer 120 can be made of tantalum nitride (TaN), tantalum (Ta), ruthenium (Ru), or a combination of these films. Other barrier layer materials can also be used. A barrier layer 102 is deposited over the copper material 122 to provide an etch stop during the via etch process and to serve as a diffusion barrier between the dielectric layers for copper. The barrier layer 102 can be made of a material such as silicon nitride (SiN), or silicon carbide (SiC), or other material suitable for incorporation into a dual damascene process flow.

A via dielectric layer 104 is deposited over the barrier layer 102. Via dielectric layer 104 can be made of an inorganic dielectric material, such as silicon dioxide, or preferably a low-K dielectric material. Typical dielectrics include undoped TEOS silicon dioxide, fluorinated silica glass (FSG), porous OSG, and commercially available dielectric materials include Black Diamond (I) and Black Diamond (II), Coral, Aurora and so on. After the via dielectric layer 104 is deposited, a patterning and etching process is used to form the via hole 114. The copper surface 122a is protected by a dielectric barrier layer such as SiC or Si ₃ N ₄ . FIG. 12A shows a dual damascene structure after formation of the via hole 114 and the trench 116. The dielectric barrier layer 102 under the via hole 114 is removed.

FIG. 12B shows that after the formation of the via hole 114 and the trench 116, the first barrier layer 130 _I , the second barrier layer 130 _II , and the copper layer 132 are deposited to line the via hole 114 and the trench 116. ing. Both the barrier layers 130 _I and 130 _II can be made of tantalum nitride (TaN), tantalum (Ta), or ruthenium (Ru). Other barrier layer materials can also be used. In one embodiment, the first barrier layer 130 _I is a thin TaN layer deposited by ALD and the second barrier layer 130 _II is a very thin Ta layer deposited by flash PVD or ALD or PVD. It is a deposited Ru layer. In one embodiment, the thickness of the first barrier layer 130 _I is between about 10 angstroms and about 150 angstroms, and the thickness of the second barrier layer 130 _II , between about 10 angstroms and about 50 angstroms. Between. A thin TaN layer by ALD provides conformal coverage by the barrier layer over the via 114 ′ and trench 116. A thin Ta or Ru layer by PVD provides excellent adhesion to the copper film 132 to be deposited on the barrier layers 130 _I and 130 _II . In general, barrier layers deposited by PVD processes do not have excellent step coverage (ie, the film is not conformal). Therefore, an ALD barrier is necessary to ensure good coverage by the barrier inside the via and trench. In another embodiment, the first barrier layer 130 _I and the second barrier layer 130 _II are combined into a single layer, which can be deposited by ALD or PVD. The single layer barrier material may be tantalum, tantalum nitride, ruthenium, or a combination of these films.

After deposition of the first and second barrier layers 130 _I and 130 _II , the substrate undergoes the required surface treatment steps described above to ensure that the barrier surface is Ta-rich. A copper film 132 is then deposited using either PVD seed 131 or electroless seed 131 followed by a thick gap-fill copper layer to fill via hole 114 and trench 116.

  After the copper film 132 fills the via hole 114 and the trench 116, the substrate 1200 may be coated with a copper material (ie excess copper) and a barrier layer (ie excess barrier) over the surface of the dielectric 106, as shown in FIG. ) To be removed. The substrate is then subjected to the required surface treatment steps described above to ensure that the substrate surface is clean and that the copper oxide has been removed from the copper surface. The next step is to cover a copper surface 140 with a copper / SiC interface adhesion promoting layer 135, such as a cobalt alloy, as shown in FIG. 16D. Examples of cobalt alloys include CoWP, CoWB, or CoWBP that can be selectively deposited on copper by an electroless process. The thickness of the adhesion promoting layer can be as thin as a monomolecular layer of only a few angstroms to a thicker layer such as 200 angstroms.

FIG. 13A illustrates one embodiment of a process flow for adjusting the surface of a barrier (liner) layer for electroless copper deposition and adjusting the post-CMP copper surface for electroless cobalt alloy deposition. In step 1301, the upper surface 122a of the metal wire 101 is cleaned to remove natural copper oxide. Copper oxide can be removed by either an Ar sputtering process or a wet chemical etching process. In step 1302, the first barrier layer (130 _I of Figure 12B) is deposited in an ALD system. In step 1303, the second barrier layer in a PVD system (130 _II in FIG. 12B) is deposited. As mentioned above, preventing exposure of the barrier layer to oxygen is important to ensure that the copper is electrolessly deposited on the barrier layer in a manner that provides excellent adhesion between the copper and the barrier layer. is there. Once the barrier layer is deposited, the substrate is desirably transported or processed in a controlled atmosphere environment to limit exposure to oxygen. The barrier layer is treated with a reducing plasma (ie, a hydrogen-containing plasma) at step 1305 to form a metal rich layer that provides a catalytic surface for a subsequent copper seed deposition step. Reduction plasma treatment is optional depending on the surface composition.

  Thereafter, in step 1307, a conformal copper seed is deposited on the barrier surface, and in step 1308, a thick copper bulk filling (or cap filling) process is followed. The conformal copper seed layer can be deposited by an electroless process. A thick copper bulk fill (also gap fill) layer can be deposited by an ECP process. Alternatively, a thick bulk fill (also gap fill) layer can be deposited by an electroless process, but using a different chemical, in the same electroless system as for a conformal seed layer.

In step 1307, a conformal copper seed is deposited on the substrate, and in step 1308, after a thick Cu bulk fill by either an electroless process or an electroplating process, as shown in FIG. 12C , step 1309 is performed. , The copper layer 132 is removed from the substrate surface above the barrier layer 130 over the dielectric 106. The barrier layer is then removed. Both of these removal processes are performed in process step 1309 of FIG. 13A. Removal of copper from the surface above the barrier layer can be achieved by CMP, a wet process. The barrier layer can be removed by CF ₄ plasma, O ₂ / Ar sputtering, CMP, or wet chemical etching. These barrier etching processes have been described above.

  After the removal of the barrier layer, in order to remove contaminants from the substrate surface, a cleaning process for removing Cu-BTA complex and metal oxide (step 1310) and a process for removing organic contaminants (step 1311). And are carried out. Details of cleaning the substrate surface using these two steps after metal CMP are described above.

  After surface contaminants are removed from the substrate surface, the substrate is treated in step 1312 with a reducing plasma, such as a hydrogen-containing plasma, to reduce any remaining metal oxide to metal. After hydrogen reduction, the copper surface is very clean and catalytic, ready for electroless deposition of cobalt alloys. In step 1313, the substrate undergoes electroless deposition of a cobalt alloy and rinsing and drying of the substrate. Final process step 1315 is an optional substrate cleaning step to clean any residual contaminants from previous electroless cobalt alloy deposition.

  FIG. 13B shows one embodiment of a schematic diagram of an integrated system 1350 that can minimize exposure of the substrate surface to oxygen at key steps after conditioning the barrier and copper surfaces. Also, since this is an integrated system, the substrate is immediately transferred from one process station to the next, which limits the time that clean copper surfaces are exposed to low levels of oxygen. The integrated system 1350 can be used to process the substrate throughout the process procedure of the flow 1300 of FIG. 13A.

  The integrated system 1350 has three substrate transfer modules 1360, 1370, 1380. The transfer modules 1360, 1370, 1380 are equipped with a robot for moving the substrate 1355 from one process area to another process area. The process area may be a substrate cassette, a reactor, or a load lock. The substrate transfer module 1360 is operated in a laboratory atmosphere. Module 1360 functions in conjunction with a substrate loader (or substrate cassette) 1361 to bring the substrate 1355 into the integrated system or to return the substrate to one of the cassettes 1361.

  As described above in the process flow 1300 of FIG. 11A, the substrate 1355 is a post-CMP copper for depositing a barrier layer, conditioning the barrier surface for copper layer deposition, and for electroless cobalt alloy deposition. It is brought into the integrated system 1350 to condition the surface. As described in step 1301 of process flow 1300, copper upper surface 122a of metal line 101 is etched to remove native copper oxide. When the copper oxide is removed, the exposed tungsten surface 122a of FIG. 12A needs to be protected from exposure to oxygen. If the removal process is an Ar sputtering process, the Ar sputtering reactor 1371 is coupled to a vacuum transfer module 1370. If a wet chemical etch process is selected, the reactor is coupled to a controlled atmosphere transfer module 1380 rather than a laboratory atmosphere transfer module 1360 to limit exposure of the clean tungsten surface to oxygen. It is desirable.

The substrate is then deposited with first and second barrier layers. The first barrier layer 130 _I of Figure 12B is deposited by an ALD process is operated at less than 1 torr with a dry process. ALD reactor 1372 is coupled to vacuum transfer module 1370. The second barrier layer 130 _II of FIG. 12B is deposited by a PVD or ALD process that is a dry process and operated at less than 1 Torr. The PVD reactor 1373 is coupled to the vacuum transfer module 1370. The substrate can undergo an optional hydrogen reduction process to ensure that the barrier layer surface is metal rich due to electroless copper deposition. The hydrogen reduction reactor 1374 can be coupled to the vacuum transfer module 1370. At this stage, the substrate is ready for electroless copper deposition. Electroless copper plating can be performed by depositing a conformal seed layer in an electroless copper plating reactor 1381 as described in step 1307 of FIG. 13A. As described above, the deposition of the gap-fill copper layer in step 1308 of FIG. 13A can be performed using different chemicals in the same electroless plating reactor 1381 or in a separate ECP reactor 1381 ′.

Thereafter, the substrate is removed of excess copper and excess barrier as described in step 1309 of FIG. 13A. Excess copper and excess barrier removal may be implemented in one CMP system 1383 or may be implemented in two CMP systems. In the embodiment shown in FIG. 13A, only one CMP system 1383 is used. After CMP removal of excess copper and excess barrier, the substrate surface needs to be cleaned to remove surface contaminants. A wet cleaning system 1385 is used to remove the copper BTA complex and metal oxide. An O ₂ plasma system 1377 is used to remove organic contaminants. In one embodiment, an O ₂ plasma process for removing organic contaminants can be performed in a hydrogen reduction chamber 1374.

  After removal of the contaminants, the substrate undergoes a reduction process as described in step 1312 of FIG. 13A. The hydrogen reduction process is used to reduce copper oxide to copper and can occur in the same reduction reactor 1374 used to reduce the barrier surface to Ta-rich. Following the hydrogen reduction treatment, the copper surface is ready for electroless cobalt alloy deposition. This can be done in reactor 1387.

  Prior to leaving the integrated system 1350, the substrate can optionally undergo a surface cleaning process that can clean residues from previous copper plating processes. The substrate cleaning process may be a brush cleaning process, and the reactor 1163 may be integrated into the laboratory atmosphere transfer module 1360.

  Any of the wet processing systems described in FIG. 13B coupled to the controlled atmosphere transfer module 1380 must meet dry-in / dry-out requirements to enable system integration.

  The apparatus and method (or process) described above applies to conditioning a metal surface for subsequent metal deposition to improve metal-metal adhesion and EM resistance. The inventive concept also applies to conditioning the silicon surface for subsequent selective metal layer deposition.

3. Design of silicon surface for selective electroless metal deposition to form metal silicides:
The processes described thus far have been used to improve their EM resistance, metal resistivity, and thus yield, for copper wiring such as contacts, vias, and metal lines. Early in the IC fabrication procedure, metal silicide is formed in the device source / drain / gate, resistor, contact contact area of the structure (such as the contact contact area of the resistor), gate region, capacitor region, or inductor region, and contact is made. Another metal deposition is applied on the silicon surface or on the polysilicon surface to reduce resistance and provide good ohmic contact. FIG. 14A is a cross section of a gate structure 127 that includes a thin gate oxide 121, a polysilicon layer 105, and a nitride spacer 107 on the silicon structure 110. Shallow trench isolation (STI) 65 is used to separate the active devices. Both sides of the gate structure are a source area 61 and a drain area 63. On the source area 61 is an exposed silicon surface 62. On the drain area 63 is an exposed silicon surface 64. On the polysilicon layer 105 is exposed polysilicon 109. In order to reduce the sheet resistance, a metal silicide is formed.

  To form a metal silicide, a metal 111 such as nickel (Ni), titanium (Ti), or cobalt (Co) is first deposited on the silicon surface as shown in FIG. 14B. At this time, the metal 111 is deposited on the substrate surface by a PVD process and is not selective to the silicon region or the dielectric region. The metal is then annealed to form a metal-silicon alloy (silicide) in the region where the metal is in contact with the silicon or polysilicon substrate. No silicide is formed in the dielectric region. Non-reacted metal, including metal in the dielectric region and metal that remains unreacted above the silicided region, is selectively removed relative to the silicide. An alternative process to the current Co or Ni deposition process is electroless metal deposition. The advantage is that the metal-silicide layer can be thicker to improve the etch stop characteristics and to allow the formation of metal-metal contacts. To enable electroless metal deposition, the silicon surface must be very clean and free of native silicon oxide. After the metal 111 is selectively deposited on the silicon surfaces 62, 64, the substrate may be between about 800 degrees Celsius and about 900 degrees Celsius to form the metal silicide 113, as shown in FIG. 14C. Heat treated at a high temperature. The formed metal silicide 113 can enable the contact 125 to be in electrical communication with the drain area 61, as shown in FIG. 14D.

  As noted above, surface conditioning prior to electroless metal deposition needs to be performed in a controlled atmosphere environment to ensure that the surface on which electroless deposition is to be performed is not exposed to oxygen. FIG. 15A illustrates one embodiment of a process flow 1500 used to form a metal silicide. In step 1501, metal contaminants are removed from all dielectric surfaces. This can be done using known methods and chemicals. Step 1501 is an optional step that is only required if there is a concern for surface metal contamination. Next, in step 1502, organic contaminants are removed from the substrate surface. As mentioned above, organic contaminants can be removed by either a variety of dry or wet processes. Thereafter, in step 1503, the silicon surface is reduced to reduce native silicon oxide to silicon. Since native silicon oxide is a self-regulating process, the oxide layer is very thin and does not require an oxide removal step prior to the reduction process. As mentioned above, the reduction process may be a hydrogen plasma process.

  After surface reduction, the silicon surface is ready for electroless metal deposition. In step 1505, a metal such as Ni, Ti, or Co is selectively deposited on the exposed silicon (including polysilicon) surface. Selective metal deposition can be achieved by an electroless process. After electroless metal deposition, the substrate undergoes optional substrate cleaning in step 1507 using known methods and chemicals. The substrate is then subjected to a high temperature process (or anneal) to form a metal silicide in step 1509.

FIG. 15B illustrates one embodiment of an integrated system 1550 that includes a laboratory atmosphere transfer module 1560, a vacuum transfer module 1950, and a controlled atmosphere transfer module 1580. The laboratory atmosphere transfer module 1560 is coupled to a cassette 1561 that holds a substrate 1555. In one embodiment, the metal contaminant is removed by a wet cleaning process, such as one of the wet cleaning processes described above used to remove the metal contaminant. Wet cleaning can be performed in a chamber 1565 coupled to a laboratory atmosphere transfer module 1560. Since this process step is optional, chamber 1565 in FIG. 15B is dashed. Following removal of metal contaminants, organic contaminants are removed. In one embodiment, organic contaminants are removed in reactor 1571 in an oxidizing plasma such as O ₂ , H ₂ O, or ozone plasma. The reactor 1571 is coupled to the vacuum transfer module 1570 because the O ₂ plasma process is a low pressure dry process operated at a pressure of less than 1 Torr.

  Thereafter, in step 1503 of flow 1500, the reduction of the silicon surface can be performed in reactor 1573. The substrate is then transferred to the next system to deposit the metal used to form the metal silicide (or silicide metal) in the electroless process reactor 1581. The substrate passes from the reactor 1573 through the vacuum transfer module 1570, the load lock 1575, and the controlled atmosphere transfer module 1580 and finally reaches the reactor 1581 for processing. Electroless metal deposition reactor 1581 includes a rinse / dry system. The substrate can undergo optional substrate cleaning in a wet cleaning chamber 1583 after metal deposition, as described in process step 1507 of FIG. 15A. After electroless deposition, the substrate is sent to a thermal reactor 1576, such as a rapid thermal processing (RTP) reactor, to form a metal silicide.

The system described above allows for substrate processing that needs to integrate mixing low pressure dry processes, high pressure processes, and wet processes to limit exposure to oxygen in critical process steps. FIG. 16 shows a schematic diagram showing how the different processes are integrated. The laboratory atmosphere transfer module can be integrated with cassettes, wet processes, and dry processes that do not need to limit exposure to oxygen (ie, are uncontrolled processes). The vacuum transfer module can integrate a low pressure dry process. Since the vacuum transfer module is operated under vacuum, such as less than 1 Torr, exposure to oxygen is limited and controlled. The load lock I enables transfer of the substrate between the experimental atmosphere transfer module and the vacuum transfer module. The controlled atmosphere transfer module can integrate wet processes, near atmospheric pressure processes, and high pressure processes. The term “high pressure” is used to distinguish from a low pressure process. The pressure of the high pressure process refers to a pressure greater than the atmospheric pressure process such as the supercritical CO ₂ process described above. In one embodiment, there is a load lock (not shown) between the high pressure process chamber and the controlled atmosphere transfer module to allow the substrate to be efficiently transferred between the transfer module and the process chamber. . The load lock II allows the substrate to be transported between the vacuum transport module and the controlled atmosphere transport module. The controlled atmosphere transfer module and the reactor coupled to the controlled atmosphere transfer module are filled with an inert gas to limit exposure to oxygen. The load lock II can be evacuated to receive the substrate from the vacuum transfer module. Loadlock II can also be filled with an inert gas to exchange the substrate with the controlled atmosphere transfer module.

Although the invention has been described in terms of several embodiments, those skilled in the art will recognize various alternatives, additions, substitutions, and equivalent forms upon reading the foregoing specification and examining the drawings. Can understand. Accordingly, the present invention is intended to embrace all such alternatives, additions, substitutions and equivalents as fall within the true spirit and scope of the invention. In the claims, elements and / or steps do not imply any particular order of operation, unless explicitly stated in the claims.
For example, the present invention can be implemented as the following application examples.
(1) In an integrated system, in order to selectively deposit a thin layer of cobalt alloy material on the copper surface of the copper wiring of the substrate to improve the electromigration resistance of the copper wiring, A method of adjusting,
In the integrated system, removing contaminants and metal oxides from the substrate surface;
Reconditioning the substrate surface using a reducing environment in the integrated system after removing contaminants and metal oxides;
After reconditioning the substrate surface, selectively depositing a thin layer of the cobalt alloy material on the copper surface of the copper interconnect in the integrated system;
A method comprising:
(2) The method according to Application Example 1,
The substrate surface is reconditioned by hydrogen-containing plasma generated by hydrogen (H ₂ ) gas, ammonia (NH ₃ ) gas, or a mixture of both gases.
(3) The method according to Application Example 1,
Reconditioning the substrate surface is substantially converting surface copper oxide to copper, and after reconditioning the substrate surface, the substrate forms copper oxide on the copper surface. A method that is transported and processed in a controlled environment to minimize.
(4) The method according to application example 3,
After reducing the copper surface, the substrate is transported with controlled exposure to oxygen to allow a thin layer of the cobalt alloy material to be selectively deposited on the copper surface. And processed.
(5) The method according to application example 1,
The thin layer of cobalt alloy material is selectively deposited on the copper surface by an electroless deposition process to promote adhesion between the copper surface of the copper interconnect and a dielectric cap layer for the copper interconnect. Deposited in a method.
(6) The method according to application example 1,
The method wherein the cobalt alloy material is selected from the group consisting of CoWP, CoWB, and CoWBP.
(7) Transport and process the substrate in a controlled environment to allow selective deposition of a thin layer of cobalt alloy material on the copper surface of the copper interconnect and to improve the electromigration resistance of the copper interconnect. An integrated system for
A laboratory atmosphere transfer chamber capable of transferring the substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system;
A substrate cleaning reactor coupled to the laboratory atmosphere transfer chamber for cleaning the substrate surface to remove metal organic complex contaminants on the substrate surface;
A vacuum transfer chamber operated under vacuum at a pressure of less than 1 torr and coupled with at least one vacuum process module;
A vacuum process module for removing organic contaminants from the substrate surface, wherein the vacuum process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber and operates under a vacuum of less than 1 Torr A vacuum process module,
A controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases, and at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber;
Used to deposit a thin layer of the cobalt alloy material on the copper surface of the copper interconnect after the substrate surface is decontaminated with metal and organic contaminants and the copper surface is decontaminated with copper oxide. An electroless cobalt alloy material deposition process module, one of the at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber, filled with an inert gas selected from the group of inert gases. An electroless cobalt alloy material deposition process module having a fluid delivery system from which the process fluid is degassed;
Integrated system with.
(8) The integrated system according to Application Example 7,
A hydrogen-containing reduction process module used to reduce residual copper oxide on the copper surface to copper, wherein the hydrogen-containing reduction is coupled to the vacuum transfer chamber and operated under vacuum at a pressure of less than 1 Torr. Integrated system with process modules.
(9) The integrated system according to application example 7,
A substrate cleaning reactor coupled to the laboratory atmosphere transfer chamber and cleaning the substrate surface to remove metal oxide on the substrate surface, wherein the wet cleaning solution is citric acid, sulfuric acid, or hydrogen peroxide An integrated system comprising a substrate cleaning reactor containing one of the sulfuric acids with
(10) The integrated system according to Application Example 7,
A first load lock coupled to the vacuum transfer chamber and the controlled atmosphere transfer chamber, which assists in transferring the substrate between the vacuum transfer chamber and the controlled atmosphere transfer chamber, with a pressure of 1 Torr A first load lock configured to be operated under a vacuum of less than or filled with an inert gas selected from the group of inert gases and operated under the same pressure as the controlled atmosphere transfer module; ,
A second load lock coupled to the vacuum transfer chamber and the laboratory atmosphere transfer chamber, which assists in transferring the substrate between the vacuum transfer chamber and the laboratory atmosphere transfer chamber; A second load lock configured to operate under a vacuum of less than 1 Torr or in a laboratory atmosphere;
Integrated system with.
(11) The integrated system according to Application Example 7,
The integrated system, wherein the vacuum transfer chamber and the at least one vacuum process module coupled to the vacuum transfer chamber are operated at a pressure of less than 1 Torr to control exposure of the substrate to oxygen.
(12) The integrated system according to Application Example 7,
The controlled atmosphere transfer chamber and the at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber are selected from the group of inert gases to control exposure of the substrate to oxygen 1 An integrated system filled with seeds or inert gases.
(13) The integrated system according to Application Example 7,
An integrated system wherein the substrate is transported and processed within the integrated system to limit the time that the substrate is exposed to oxygen.
(14) The method according to application example 13,
Limiting exposure of the substrate surface to oxygen reduces the introduction time of a deposition reaction and enhances the quality of the thin layer of the cobalt alloy material that is selectively deposited on the copper surface.
(15) The integrated system according to Application Example 7,
The integrated system wherein the at least one process module coupled to the controlled atmosphere transfer module enables dry-in / dry-out processing of the substrate, wherein the substrate enters and exits in a dry state.
(16) In the integrated system, a metal barrier layer is deposited to line the copper wiring structure of the substrate, and a thin copper seed layer is deposited on the surface of the metal barrier layer to make the electromigration resistance of the copper wiring. In order to improve, a method of adjusting the substrate surface of the substrate,
In the integrated system, cleaning an exposed surface of a lower metal to remove surface metal oxide, wherein the lower metal is a part of a lower wiring electrically connected to the copper wiring And that
Within the integrated system, depositing the metal barrier layer to line the copper interconnect structure, and after depositing the metal barrier layer, the substrate prevents formation of a metal barrier oxide. In order to be transported and processed in a controlled environment,
Depositing the thin copper seed layer in the integrated system;
Depositing a gap-fill copper layer over the thin copper seed layer in the integrated system;
A method comprising:
(17) The method according to Application Example 16, further comprising:
Within the integrated system, reducing the surface of the metal barrier layer to convert the metal barrier oxide on the surface of the metal barrier layer to make the surface of the metal barrier layer metal rich. And after the exposed surface of the underlying metal is cleaned.
(18) The method according to Application Example 16,
The copper wiring includes a metal line on a via, and the lower wiring includes a metal line.
(19) The method according to Application Example 16,
Cleaning the exposed surface of the surface metal oxide is accomplished using either an Ar sputtering process or a plasma process using a fluorine-containing gas.
(20) The method according to Application Example 16,
Depositing the metal barrier layer further comprises:
Depositing a first metal barrier layer;
Depositing a second metal barrier layer;
Including a method.
(21) The method according to Application Example 16,
The substrate is transported and processed in a controlled environment to prevent metal barrier oxide formation and allow the thin copper seed layer to be selectively deposited to improve electromigration of the copper interconnect. To be the way.
(22) The method according to Application Example 16,
A method wherein a substrate is transported and processed in the integrated system to limit the time that the substrate is exposed to oxygen.
(23) In the integrated system, a thin copper seed layer is deposited on the surface of the metal barrier layer of the copper wiring structure, and the metal barrier surface of the substrate is adjusted to improve the electromigration resistance of the copper wiring structure. A method,
Reducing the surface of the metal barrier layer in the integrated system to convert a metal barrier oxide on the surface of the metal barrier layer to render the surface of the metal barrier layer metal rich;
Depositing the thin copper seed layer in the integrated system;
Depositing a gap-fill copper layer over the thin copper seed layer in the integrated system;
A method comprising:
(24) An integrated system for processing a substrate in a controlled environment to allow a thin copper seed layer to be deposited on the surface of a metal barrier layer of a copper interconnect;
A laboratory atmosphere transfer chamber capable of transferring the substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system;
A vacuum transfer chamber operated under vacuum at a pressure of less than 1 torr, the vacuum transfer chamber coupled with at least one vacuum process module;
A vacuum process module for cleaning an exposed surface of a metal oxide of a lower metal in the integrated system, wherein the lower metal is a part of a lower wiring, and the copper wiring is the lower metal The cleaning vacuum process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber and operated under vacuum at a pressure of less than 1 Torr. A vacuum process module,
A vacuum process module for depositing the metal barrier layer, the vacuum process module being one of the at least one vacuum process module coupled to the vacuum transfer chamber, wherein the vacuum is operated under a vacuum of less than 1 Torr. A process module;
A controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases, the control atmosphere transfer chamber being coupled with at least one controlled atmosphere process module;
An electroless copper deposition process module used to deposit the thin copper seed layer on the surface of the metal barrier layer of the at least one controlled environment process module coupled to the controlled atmosphere transfer chamber. One electroless copper deposition process module;
Integrated system with.
(25) The integrated system according to Application Example 24,
A hydrogen-containing reduction process module used to reduce metal oxides or metal nitrides on the surface of the metal barrier, which is coupled to the vacuum transfer chamber and operates under a vacuum of less than 1 Torr Integrated system comprising a hydrogen-containing reduction process module.
(26) The integrated system according to Application Example 24,
A first load lock coupled to the vacuum transfer chamber and the controlled atmosphere transfer chamber, which assists in transferring the substrate between the vacuum transfer chamber and the controlled atmosphere transfer chamber, with a pressure of 1 Torr A first load lock configured to operate under a vacuum of less than or filled with an inert gas selected from the group of inert gases;
A second load lock coupled to the vacuum transfer chamber and the laboratory atmosphere transfer chamber, which assists in transferring the substrate between the vacuum transfer chamber and the laboratory atmosphere transfer chamber; A second load lock configured to operate under a vacuum of less than 1 Torr, or to operate in a laboratory atmosphere, or to be filled with an inert gas selected from the group of inert gases When,
Integrated system with.
(27) The integrated system according to Application Example 24,
The integrated system, wherein the vacuum transfer chamber and the at least one vacuum process module coupled to the vacuum transfer chamber are operated at a pressure of less than 1 Torr to control exposure of the substrate to oxygen.
(28) The integrated system according to Application Example 24,
The controlled atmosphere transfer chamber and the at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber are selected from the group of inert gases to control exposure of the substrate to oxygen 1 An integrated system filled with seeds or inert gases.
(29) The integrated system according to Application Example 24,
The at least one process module coupled to the controlled atmosphere transfer module enables dry-in / dry-out processing of the substrate, and the substrate is in and out of the at least one process module in a dry state. system.
(30) An integrated system for processing a substrate in a controlled environment to allow a thin copper seed layer to be deposited on the surface of a metal barrier layer of a copper interconnect;
A laboratory atmosphere transfer chamber capable of transferring the substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system;
A vacuum transfer chamber operated under vacuum at a pressure of less than 1 torr, the vacuum transfer chamber coupled with at least one vacuum process module;
A vacuum process module for reducing the metal barrier layer, the vacuum process module being one of the at least one vacuum process module coupled to the vacuum transfer chamber, wherein the vacuum is operated under a vacuum of less than 1 Torr. A process module;
A controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases, the control atmosphere transfer chamber being coupled with at least one controlled atmosphere process module;
An electroless copper deposition process module used to deposit the thin copper seed layer on the surface of the metal barrier layer of the at least one controlled environment process module coupled to the controlled atmosphere transfer chamber. One electroless copper deposition process module;
Integrated system with.
(31) A method for adjusting a substrate surface of a substrate to form a metal silicide by selectively depositing a metal layer on a silicon surface or a polysilicon surface of the substrate in an integrated system,
In the integrated system, removing organic contaminants from the substrate surface;
After removing organic contaminants, reducing the silicon surface or the polysilicon surface in the integrated system to convert silicon oxide on the silicon surface or the polysilicon surface to silicon. After reducing the silicon surface or the polysilicon surface, the substrate is transported and processed in a controlled environment to prevent the formation of silicon oxide; the silicon surface or the polysilicon surface is on the silicon surface; Reduced to increase the selectivity of the metal,
Selectively depositing the layer of metal on the silicon surface or on the polysilicon surface of the substrate in the integrated system after reducing the silicon surface or the polysilicon surface;
A method comprising:
(32) The method according to Application Example 31, further comprising:
Forming the metal silicide in the integrated system after selectively depositing the metal layer on the silicon surface.
(33) The method according to application example 31, further comprising:
Removing metal contaminants from the substrate surface in the integrated system prior to reducing the silicon surface.
(34) The method according to Application Example 31,
The method wherein the silicon surface or the polysilicon surface is reduced by a hydrogen-containing plasma generated by hydrogen (H ₂ ) gas, ammonia (NH ₃ ) gas, or a combination of both gases.
(35) The method according to application example 31,
The method wherein the metal is selected from the group consisting of Ni or Co.
(36) The method according to Application Example 31,
After the silicon surface is reduced, the substrate is transferred or processed in a vacuum environment or in an inert gas-filled environment to control exposure of the substrate surface to oxygen, thereby integrating the system. A method that is transported and processed within a controlled environment.
(37) The method according to Application Example 32,
The method wherein the metal silicide is formed in a rapid thermal processing (RTP) system.
(38) An integrated system for processing a substrate in a controlled environment to enable selective deposition of a layer of metal on the silicon surface of the substrate to form a metal silicide,
A laboratory atmosphere transfer chamber capable of transferring the substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system;
A vacuum transfer chamber operated under vacuum at a pressure of less than 1 torr, the vacuum transfer chamber coupled with at least one vacuum process module;
A vacuum process module for removing organic contaminants from the substrate surface, wherein the vacuum process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber and operates under a vacuum of less than 1 Torr A vacuum process module,
A vacuum process chamber for reducing the silicon surface, wherein the vacuum process is one of the at least one vacuum process module coupled to the vacuum transfer chamber and operated under a vacuum at a pressure of less than 1 Torr A chamber;
A controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases, and at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber;
An electroless metal deposition process module used to selectively deposit the thin metal layer on the silicon surface after the silicon surface has been reduced, wherein the electroless metal deposition process module is coupled to the controlled atmosphere transfer chamber. An electroless metal deposition process module that is one of at least one controlled atmosphere process module;
Integrated system with.
(39) The integrated system according to Application Example 38,
The integrated system, wherein the vacuum process chamber for forming the metal silicide is an RTP chamber.
(40) The integrated system according to application example 38,
The controlled atmosphere transfer chamber and the at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber are selected from the group of inert gases to control exposure of the substrate to oxygen 1 An integrated system filled with seeds or inert gases.

Claims (14)

In an integrated system, a method for selectively depositing a thin layer of cobalt alloy material on a copper surface of a copper interconnect of a substrate to condition the substrate surface of the substrate to improve electromigration resistance of the copper interconnect Because
Introducing the substrate in which the copper wiring is embedded in a trench formed in a dielectric via a barrier layer and the barrier layer is exposed on the dielectric surface into the integrated system;
In the integrated system, removing contaminants and metal oxides from the substrate surface;
And that after removing the contaminants and the metal oxides from the substrate surface, within the integrated system, removing the barrier layer from the substrate surface,
And that from the substrate surface, which removes the contaminants and the metal oxide, after removing the barrier layer, within the integrated system, readjusting the substrate surface using a reducing environment,
After reconditioning the substrate surface, selectively depositing a thin layer of the cobalt alloy material on the copper surface of the copper interconnect in the integrated system;
A method comprising: The method of claim 1, comprising:
The substrate surface is reconditioned by hydrogen-containing plasma generated by hydrogen (H ₂ ) gas, ammonia (NH ₃ ) gas, or a mixture of both gases. The method of claim 1, comprising:
Reconditioning the substrate surface is substantially converting surface copper oxide to copper, and after reconditioning the substrate surface, the substrate forms copper oxide on the copper surface. A method that is transported and processed in a controlled environment to minimize. The method of claim 3, comprising:
After reducing the copper surface, the substrate is transported with controlled exposure to oxygen to allow a thin layer of the cobalt alloy material to be selectively deposited on the copper surface. And processed. The method of claim 1, comprising:
The thin layer of cobalt alloy material is selectively deposited on the copper surface by an electroless deposition process to promote adhesion between the copper surface of the copper interconnect and a dielectric cap layer for the copper interconnect. Deposited in a method. The method of claim 1, comprising:
The method wherein the cobalt alloy material is selected from the group consisting of CoWP, CoWB, and CoWBP. A trench formed in a dielectric in a controlled environment to enable selective deposition of a thin layer of cobalt alloy material on the copper surface of the copper interconnect and to improve the electromigration resistance of the copper interconnect. An integrated system for transporting and processing a substrate in which the copper wiring is embedded through a barrier layer and the barrier layer is exposed on the dielectric surface;
A laboratory atmosphere transfer chamber capable of transferring the substrate from a substrate cassette coupled to the laboratory atmosphere transfer chamber into the integrated system;
Coupled to said laboratory ambient transfer chamber, a substrate cleaning reactor for cleaning the substrate surface to remove gold Shokukitana dyeings on the substrate surface,
A vacuum transfer chamber operated under vacuum at a pressure of less than 1 torr and coupled with at least one vacuum process module;
A vacuum process module for removing organic contaminants from the substrate surface, wherein the vacuum process module is one of the at least one vacuum process module coupled to the vacuum transfer chamber and operates under a vacuum of less than 1 Torr A vacuum process module,
A module coupled to said vacuum transfer chamber, and etching module for removing the barrier layer from the substrate surface,
A controlled atmosphere transfer chamber filled with an inert gas selected from the group of inert gases, and at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber;
One of the controlled atmosphere process modules coupled to the controlled atmosphere transfer chamber, wherein the substrate surface has metal and organic contaminants removed, the barrier layer removed, and the copper surface removed copper oxide. later, a electroless cobalt alloy material deposition process module used for depositing a thin layer of the cobalt alloy material on the copper surface of the copper wiring, wherein the inert is selected from the group of inert gases An electroless cobalt alloy material deposition process module having a fluid delivery system filled with gas and degassed process fluid;
A hydrogen-containing reduction process module used to reduce residual copper oxide on the copper surface to copper, wherein the hydrogen-containing reduction is coupled to the vacuum transfer chamber and operated under vacuum at a pressure of less than 1 Torr. Integrated system with process modules . The integrated system according to claim 7, further comprising:
A substrate cleaning reactor coupled to the laboratory atmosphere transfer chamber and cleaning the substrate surface to remove metal oxide on the substrate surface, wherein the wet cleaning solution is citric acid, sulfuric acid, or hydrogen peroxide An integrated system comprising a substrate cleaning reactor containing one of the sulfuric acids with The integrated system according to claim 7, further comprising:
A first load lock coupled to the vacuum transfer chamber and the controlled atmosphere transfer chamber, which assists in transferring the substrate between the vacuum transfer chamber and the controlled atmosphere transfer chamber, with a pressure of 1 Torr A first load lock configured to be operated under a vacuum of less than or filled with an inert gas selected from the group of inert gases and operated under the same pressure as the controlled atmosphere transfer module; ,
A second load lock coupled to the vacuum transfer chamber and the laboratory atmosphere transfer chamber, which assists in transferring the substrate between the vacuum transfer chamber and the laboratory atmosphere transfer chamber; A second load lock configured to operate under a vacuum of less than 1 Torr or in a laboratory atmosphere;
Integrated system with. The integrated system according to claim 7,
The integrated system, wherein the vacuum transfer chamber and the at least one vacuum process module coupled to the vacuum transfer chamber are operated at a pressure of less than 1 Torr to control exposure of the substrate to oxygen. The integrated system according to claim 7,
The controlled atmosphere transfer chamber and the at least one controlled atmosphere process module coupled to the controlled atmosphere transfer chamber are selected from the group of inert gases to control exposure of the substrate to oxygen 1 An integrated system filled with seeds or inert gases. The integrated system according to claim 7,
An integrated system wherein the substrate is transported and processed within the integrated system to limit the time that the substrate is exposed to oxygen. The integrated system according to claim 7,
An integrated system that limits exposure of the substrate surface to oxygen reduces the introduction time of a deposition reaction and improves the quality of the thin layer of the cobalt alloy material that is selectively deposited on the copper surface. The integrated system according to claim 7,
The integrated system wherein the at least one process module coupled to the controlled atmosphere transfer module enables dry-in / dry-out processing of the substrate, wherein the substrate enters and exits in a dry state.

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