Deposition of an aluminum oxide layer

Abstract

This invention relates to the deposition of an alumina etch stop layer. It is characterized by a dielectric constant (k) less than about 7 (e.g., between about 4 and 6) and a density of at least about 2.5 g / cm³. 3 (For example, between approximately 3.0 and 3.2 g / cm³) 3 An alumina film (between metal and dielectric layers) is deposited on partially fabricated semiconductor devices as an etch stop layer. A deposition method that does not cause oxidative damage to the metal is used to deposit the film. Deposition involves reacting an aluminum-containing precursor (e.g., trialkylaluminum) with an alcohol and / or alkoxyaluminum. In one implementation, the method involves flowing trimethylaluminum into a processing chamber housing a substrate with exposed metal and dielectric layers; cleaning and / or evacuating the processing chamber; flowing tert-butanol into the processing chamber and reacting it with trimethylaluminum to form an alumina film; and repeating these process steps until a film of the desired thickness is formed.

Description

[0001] This application is a divisional application of application number 201711119934.7, filed on November 14, 2017, entitled "Deposition of Alumina Etching Stop Layer". Technical Field

[0002] This invention relates to semiconductor substrate processing methods. Specifically, this invention relates to a method for depositing dielectric etch stop layers on interlayer dielectrics (ILDs) and on metals during integrated circuit (IC) manufacturing. Background Technology

[0003] In integrated circuit manufacturing, metal lines (e.g., copper wires) are typically embedded in ILD layers, where the ILD is usually a dielectric material based on porous silicon oxide or an organic polymer dielectric material with a low dielectric constant, such as an ultra-low-k (ULK) dielectric with a dielectric constant of 2.2 or below. Forming such embedded metal lines using a damascene process requires patterning and etching the ILD to form vias and trenches, which are then filled with metal (e.g., copper) for example, by electroplating. After the vias and trenches are filled with metal, a second ILD layer is deposited and patterned again to form vias and trenches. These recessed features are again filled with metal, resulting in a stack of ILD layers with embedded metal lines, where the metal lines form the conductive paths of the integrated circuit. Etch-stop layers are typically deposited on the individual ILD layers and metal lines and are used for the patterning operations of the IC manufacturing process to protect the material beneath these layers from being etched during patterning. For example, a semiconductor substrate may include an etch-stop layer located between two ILD layers. When the top ILD layer is patterned and etched (e.g., using fluorine-based chemicals) to define vias and trenches, an etch stop layer protects the bottom ILD layer below the etch stop point from being etched.

[0004] The material of the etch stop layer should exhibit good etch selectivity relative to the material being etched. In other words, the etch stop layer material should be etched at a significantly lower rate than the exposed ILD material (or other material being patterned).

[0005] Etch stop layers are typically not completely removed during integrated circuit manufacturing and remain as a thin film between thicker ILD layers in the final manufactured semiconductor device. Examples of commonly used etch stop layer materials include silicon carbide and silicon nitride. Summary of the Invention

[0006] Methods, apparatus, and systems for forming high-quality alumina layers are provided. The provided methods enable the deposition of alumina without causing oxidation of the metal layer on which the alumina is deposited. This is a significant advantage of the provided methods because metal oxidation leads to increased resistance in the metal lines and thus increases unwanted resistive-capacitive (RC) delay. Furthermore, the alumina materials deposited by the methods provided herein are well-suited for use as etch stop layers because they are characterized by low dielectric constant (k) and high density. A low dielectric constant is highly desirable for etch stop layers because the etch stop layer is not completely removed from the semiconductor device during processing, and the final device typically contains thin etch stop layers between individual ILD layers. To minimize crosstalk between metal lines and reduce RC delay, it is important to use etch stop materials with low dielectric constants. However, many conventional low-k materials typically have relatively low etch selectivity relative to ILD materials. Therefore, materials with both low dielectric constants and high etch selectivity are needed. Etching selectivity is a property positively correlated with material density. Therefore, materials with both low dielectric constants and high density are desirable.

[0007] According to some embodiments, the alumina material deposited by the method provided herein is characterized by a dielectric constant of less than about 7, for example, between about 4 and 6, and a density of at least about 2.5 g / cm³. 3 For example, between approximately 3.0-3.2 g / cm³ 3 Between (e.g., between approximately 2.6-3.2 g / cm³) 3 Examples of molded films include those with a dielectric constant of less than about 6 and a density of at least about 2.8 g / cm³. 3 The film. In some implementations, a dielectric constant of about 4-6 and a density of about 3.0-3.2 g / cm³ are formed. 3 Alumina film.

[0008] According to one aspect, a method for processing a semiconductor substrate is provided. The method includes: providing a semiconductor substrate comprising an exposed dielectric layer (e.g., a ULK dielectric layer) and an exposed metal layer; and forming an alumina etch-stop film over the dielectric layer and the metal layer by reacting an aluminum-containing precursor with a reactant selected from alcohols and aluminum alkoxy groups, wherein the alumina etch-stop film contacts both the dielectric layer and the metal layer, wherein the formed alumina etch-stop film has a dielectric constant of less than about 7 and at least about 2.5 g / cm³. 3 The density. In some embodiments, the etch stop film is formed with a thickness between about 10 and 100 angstroms, for example, between about 20 and 50 angstroms.

[0009] Various metals can be present in the exposed metal layer. In some embodiments, the metal is selected from copper, cobalt, and tungsten, and the deposition of alumina does not result in the formation of metal oxides at the interface between the metal and the alumina. In some embodiments, the metal is cobalt, and no Co-O bonds, detectable by X-ray photoelectron spectroscopy (XPS), are formed during alumina deposition.

[0010] In some embodiments, forming an alumina etch-stop film involves reacting an aluminum-containing precursor with an alcohol containing at least four carbon atoms. For example, in one implementation, a high-quality alumina etch-stop film is formed by reacting trimethylaluminum (TMA) with tert-butanol. Using an alcohol with at least four carbon atoms allows for improved control of the reaction compared to using a more reactive alcohol with fewer carbon atoms.

[0011] In some embodiments, the alumina etch-stop film is formed by a reaction that occurs substantially on the surface of the semiconductor substrate. In other embodiments, the alumina etch-stop film is formed by a reaction that occurs substantially outside the surface of the semiconductor substrate.

[0012] In one implementation, forming the alumina etch-stop film includes: (i) adsorbing an aluminum-containing precursor, wherein the aluminum-containing precursor is trialkylaluminum, onto the surface of the semiconductor substrate in a processing chamber containing the semiconductor substrate (e.g., by allowing trialkylaluminum to flow into the processing chamber for about 0.1-10 seconds); (ii) purging and / or emptying the processing chamber after the aluminum-containing precursor has been adsorbed; (iii) after purging, providing the processing chamber with an alcohol having at least four carbon atoms (e.g., by allowing an alcohol to flow into the processing chamber for about 0.1-10 seconds) and reacting the alcohol with the adsorbed aluminum-containing precursor to form alumina; (iv) purging and / or emptying the processing chamber after the reaction; and (v) repeating (i)-(iv). In some embodiments, steps (i)-(iv) are repeated at least three times. Preferably, the reaction between the trialkylaluminum and the alcohol in (iii) is carried out in the absence of plasma. In some embodiments, the alumina etch-stop film is formed at a temperature between about 50 and 400°C and at a pressure between about 0.5 and 8 Torr. In a preferred embodiment, the trialkylaluminum is TMA and the alcohol is tert-butanol.

[0013] In some embodiments, the semiconductor substrate processing method further includes: applying a photoresist to the semiconductor substrate; exposing the photoresist to light; patterning the photoresist and transferring the pattern to the semiconductor substrate; and selectively removing the photoresist from the semiconductor substrate. In some embodiments, the semiconductor substrate processing method further includes depositing a dielectric layer on the alumina layer, and etching a recessed feature in the deposited dielectric layer in the presence of an exposed etch stop layer. In some embodiments, the alumina etch stop layer is removed (at least partially) after the recessed feature has been formed.

[0014] According to another aspect, an apparatus for depositing an alumina etch-stop film is provided. In one embodiment, the apparatus includes a processing chamber having a support for holding a semiconductor substrate and a controller. The controller includes program instructions for performing any of the deposition methods provided herein. In some embodiments, the controller is programmed to form an alumina etch-stop film on a dielectric layer and a metal layer by reacting an aluminum-containing precursor with a reactant selected from alcohols and aluminum alkoxylates, wherein the alumina etch-stop film contacts the dielectric layer and the metal layer, wherein the formed alumina etch-stop film has a dielectric constant of less than about 7 and at least about 2.5 g / cm³. 3 The density. The program instructions may include instructions for: (a) introducing (e.g., sequentially introducing) an aluminum-containing precursor and an alcohol or alkoxy aluminum into a processing chamber; and (b) allowing them to react and form an alumina etch-stop film on the substrate.

[0015] In some embodiments, the apparatus includes a first conduit configured to deliver an aluminum-containing precursor to the processing chamber; and a second conduit configured to deliver an alcohol or aluminum alkoxy to the processing chamber, wherein the first and second conduits are different conduits.

[0016] According to another aspect, this paper provides a system comprising a deposition apparatus for depositing an alumina etch stop film and a stepper.

[0017] According to another aspect, a non-transitory computer-readable medium is provided. It includes program instructions for controlling a deposition apparatus. The instructions include code for the deposition method provided herein. In some embodiments, code is provided for: (a) introducing (e.g., sequentially introducing) an aluminum-containing precursor and an alcohol (or aluminum alkoxide) into a processing chamber; and (b) allowing them to react and form an alumina etch-stop film on a semiconductor substrate.

[0018] According to another aspect, a semiconductor device is provided comprising an alumina etch-stop film, wherein the alumina etch-stop film has a thickness between about 10 and 50 angstroms, and is characterized by a dielectric constant of less than about 6 and a density of at least about 2.8 g / cm³. 3 The aluminum oxide remains in contact with the metal layer, and the metal layer shows no signs of oxidation.

[0019] These and other features and advantages of the present invention are described in more detail below with reference to the accompanying drawings. Attached Figure Description

[0020] Figure 1A-1C A cross-sectional view of a semiconductor substrate during processing is shown according to the embodiments provided herein, in which an etch stop film is shown.

[0021] Figure 2 This is a process flow diagram of the processing method provided in this article.

[0022] Figure 3 This is a process flow diagram of a method for depositing an alumina etching stop film according to the embodiments provided herein.

[0023] Figure 4 This is a schematic diagram of an ALD processing station that can be used to deposit alumina films according to the embodiments provided herein.

[0024] Figure 5 A schematic diagram of a multi-station processing tool according to an embodiment provided herein is shown.

[0025] Figure 6 This is a block diagram of a processing tool configured for depositing thin films according to the embodiments provided herein.

[0026] Figure 7A This is an experimental XPS image of the cobalt layer after the deposition of an alumina film according to the method described in this paper.

[0027] Figure 7B This is an experimental XPS image of the cobalt layer after deposition of an aluminum-containing film, showing the oxidation of cobalt. Detailed Implementation

[0028] In the following detailed description, numerous specific details are set forth to provide a full understanding of the disclosed implementations. However, it will be apparent to those skilled in the art that the disclosed implementations may be carried out without these specific details or by using alternative elements or processes. In other examples, well-known processes, procedures, and components have not been described in detail to avoid unnecessarily obscuring aspects of the disclosed embodiments.

[0029] In this application, the terms "semiconductor wafer," "semiconductor substrate," "wafer," "substrate," "wafer substrate," and "partially fabricated integrated circuit" are used interchangeably. Those skilled in the art will understand that the term "partially fabricated integrated circuit" can refer to a silicon wafer during any of the many stages of integrated circuit fabrication on which it is placed. The following detailed description describes the deposition of interface layers on the wafer. However, the disclosed implementations are not limited thereto. Workpieces can be of various shapes, sizes, and materials. Besides semiconductor wafers, other workpieces that can take advantage of the disclosed implementations include various articles of manufacture such as printed circuit boards. As used herein, the terms "semiconductor wafer" or "semiconductor substrate" refer to a substrate having semiconductor material anywhere within its body, and it is understood that the semiconductor material does not need to be exposed. In many embodiments, the semiconductor substrate includes one or more dielectric and conductive layers formed on the semiconductor material.

[0030] The alumina films provided herein comprise Al and O. Although other elements may be present in some embodiments, in many illustrative embodiments the films are essentially composed of Al and O and do not contain more than 5 atomic percent of other elements (e.g., no more than 5 atomic percent of carbon, no more than 5 atomic percent of hydrogen). In these exemplary embodiments, the atomic ratio of aluminum to oxygen is about 2 to 3. It has been unexpectedly found that the deposition methods provided herein can be used to deposit alumina on metal surfaces (e.g., cobalt or copper surfaces) without forming metal oxides at the interface between the metal and the alumina. This finding is surprising because metals such as copper and cobalt readily form oxides, and depositing alumina-based films by different methods exhibits undesirable copper and cobalt oxidation.

[0031] The alumina film provided in this paper is a high-quality film, where high quality refers to the combination of high density and low dielectric constant. Specifically, the film provided in this paper has a dielectric constant of less than about 7 and a dielectric constant of at least about 2.5 g / cm³. 3 The density. In some embodiments, these films have a dielectric constant of less than about 6 and at least about 2.8 g / cm³. 3 The density. In some embodiments, a dielectric constant of about 4-6 and a density of about 3.0 g / cm³ are provided. 3 -3.2g / cm 3The films are made of alumina. Furthermore, in some embodiments, the provided films are characterized by a breakdown voltage greater than about 8 MV / cm, for example at least about 9 MV / cm, or at least about 11 MV / cm. These films exhibit good adhesion to cobalt, indicating the formation of Al-O-Co bonds. Adhesion to copper has also proven good. The films provided according to some embodiments have been found to possess a unique combination of properties (no metal oxidation, strong adhesion to metals, high density, low dielectric constant, and high breakdown voltage), making them ideal for use as etch stop layers.

[0032] The alumina films described herein are typically deposited as thin interface layers between dielectric layers and / or between metal layers and dielectric layers. In some embodiments, the film is located at the interface between a layer comprising a metal (e.g., copper, cobalt, or tungsten) and a ULK dielectric, and a diffusion barrier material layer (e.g., a doped or undoped silicon carbide layer or a doped or undoped silicon nitride layer). The thickness of the provided layers is about 10-200 angstroms, more typically about 10-100 angstroms, for example about 20-50 angstroms.

[0033] In some embodiments, a semiconductor device is provided, wherein the semiconductor device comprises two ILD layers (e.g., ULK dielectric) and a thin layer of provided alumina film (e.g., in approximately) located between the two ILD layers. Between, for example, about The ILD layer may also include embedded metal (e.g., copper, tungsten, or cobalt) lines, and in some embodiments, a thin alumina film is also located between the metal and the ILD (e.g., a ULK dielectric), contacting both the ILD and the metal. Advantageously, in some embodiments, there are no metal oxides detectable by XPS or a reflectometer at the interface between the metal layer and the alumina layer. In some embodiments, the device includes an interface between cobalt and alumina.

[0034] The provided alumina film is particularly suitable as an etch stop layer, but can also be used as an interface layer for various purposes (e.g., to improve electromigration resistance or as a hard mask).

[0035] Typically, the provided film can be deposited on a flat or patterned substrate. In one embodiment, the provided film is deposited on a semiconductor substrate having an exposed flat surface that includes both an exposed dielectric and a metal (e.g., copper, cobalt, or tungsten).

[0036] Figure 1A-1C An example of a semiconductor substrate undergoing a dual damascene process involving several steps is provided, in which the provided alumina film can be used. Reference Figure 1A An example of a partially fabricated integrated circuit (IC) structure 100 for dual-damascene fabrication is shown. Figure 1A-1CAs shown, structure 100 is part of a semiconductor substrate and in some embodiments may reside directly on a layer containing active devices (e.g., transistors). In other embodiments, it may reside directly on a metallization layer or on other layers containing conductive materials, such as on a layer containing storage capacitors.

[0037] Figure 1A Layer 103, as shown, is an interlayer dielectric layer, which may be silicon dioxide, but more typically a low-k dielectric material. To minimize the dielectric constant of the intermetallic dielectric stack, materials with a k value less than about 3.5, preferably less than about 3.0 and often less than about 2.8, are used as the interlayer dielectric. These materials include, but are not limited to, fluorine- or carbon-doped silicon dioxide (e.g., SiCOH), organic low-k materials, and porous doped silicon dioxide materials. Such materials can be deposited, for example, by plasma-enhanced chemical vapor deposition (PECVD) or by spin-coating. In some embodiments, layer 103 contains a ULK dielectric. Layer 103 is etched with wire paths (trenches and vias), in which a partially conductive metal diffusion barrier layer 105 is deposited, followed by embedding of a copper conductive path 107. In other embodiments, a metal other than copper (e.g., cobalt or tungsten) is used. Since copper or other movable conductive materials provide conductive paths for the semiconductor substrate, the underlying silicon device and dielectric layer near the metal lines must be protected from metal ions (e.g., Cu). 2+ The influence of these metal ions (e.g., Cu) otherwise, 2+ Diffusion barriers (DLPs) may diffuse or drift into the silicon or interlayer dielectric, leading to performance degradation. Several types of metal diffusion barrier layers are used to protect the dielectric layers of IC devices. These types can be categorized into partially conductive metal-containing layers, such as 105, and dielectric barrier layers. Suitable materials for partially conductive diffusion barrier layers 105 include materials such as tantalum, tantalum nitride, titanium, and titanium nitride. These are typically conformally deposited onto dielectric layers with vias and trenches using physical vapor deposition (PVD) or atomic layer deposition (ALD) methods.

[0038] The copper conductive path 107 can be formed after depositing a diffusion barrier layer 105 using various techniques including PVD, electroplating, electroless deposition, and chemical vapor deposition (CVD). In some implementations, a preferred method for forming the copper filler includes depositing a thin copper seed layer by PVD, followed by depositing the bulk copper filler by electroplating. Since copper deposition typically forms a capping layer in the field region, a chemical mechanical polishing (CMP) operation is required to remove the capping layer and obtain a planarized structure 100. As described above, in some embodiments, the conductive path 107 is made of tungsten or cobalt, which can be deposited, for example, by CVD or ALD (where CVD and ALD can be thermally or plasma-assisted).

[0039] Next, refer to Figure 1B After structure 100 is completed, the provided alumina etch stop film 109 is deposited onto copper wire 107 and dielectric 103 using the methods provided herein. Advantageously, at the interface between copper wire 107 and alumina etch stop film 109, this deposition method does not cause the formation of copper oxide (nor does it cause the formation of cobalt and tungsten oxides when cobalt and tungsten are used in the metal wire).

[0040] It should be noted that in some embodiments, the top of the ILD layer 103 (on which layer 109 is deposited) may differ from the body portion of layer 109. For example, in some embodiments, the top of layer 103 is mechanically more robust than the body portion. In one implementation, the top of layer 103 is mechanically robust doped or undoped silicon carbide or silicon nitride, while the body portion of the dielectric layer 103 is a more delicate ULK dielectric (e.g., a porous material). In one example, the top of layer 103 is oxygen-doped silicon carbide (ODC). The presence of this more robust layer makes it easier to deposit an etch stop film using a plasma step without damaging exposed portions of the substrate.

[0041] In some embodiments, the alumina etched layer 109 also serves as a dielectric diffusion barrier layer at its location at the interface between copper and dielectric in the fabricated structure. In some embodiments, a separate diffusion barrier layer is deposited on top of layer 109. Typically, such a diffusion barrier layer (not shown) comprises doped or undoped silicon carbide (e.g., silicon carbide) or silicon nitride.

[0042] refer to Figure 1B A first dielectric layer 111 of the dual damascene dielectric structure is deposited onto an alumina etch stop film 109. An etch stop film 113 is then deposited on the first dielectric layer 111. The etch stop film 113 may be the alumina etch stop film provided herein, or it may contain different etch stop materials. Dielectric layer 111 typically contains a low-k dielectric material, such as those listed for dielectric layer 103, and may also include a mechanically more robust top (e.g., a top containing an ODC). Note that layers 111 and 103 do not necessarily have the same composition. In some embodiments, both layers 111 and 103 are ULK dielectric layers.

[0043] The process continues, such as Figure 1CAs shown, the second dielectric layer 115 of the dual damascene dielectric structure is deposited onto the etch stop film 113 in a manner similar to the deposition of the first dielectric layer 111. An antireflective layer (not shown) and a CMP stop film 117 are then deposited. The second dielectric layer 115 typically comprises a low-k dielectric material, such as those described above for layers 103 and 111, and may optionally include a mechanically more robust top portion. The CMP stop film 117 serves to protect the fine dielectric material of the interlayer dielectric layer 115 during subsequent CMP operations. Typically, the CMP stop layer undergoes similar integration requirements as the etch stop films 109 and 113 and may comprise an alumina film as provided herein. Alternatively, it may comprise conventional CMP stop materials based on silicon carbide or silicon nitride.

[0044] During subsequent operations, ILD layers 111 and 115 are patterned to form recessed features (vias and trenches). Patterning is typically performed using conventional photolithography techniques and involves applying a photoresist to a substrate, exposing the photoresist to light, patterning the photoresist, transferring the pattern to the substrate by etching the dielectric material, typically using fluorine-based chemicals, and removing the photoresist. The provided alumina etch-stop film has good etch selectivity relative to the ILD dielectric (e.g., ULK dielectric and / or ODC) and protects the material beneath the etch-stop layer from etching. In some embodiments, the dielectric layer 111 (e.g., a SiCOH layer) is etched using fluorine-based chemicals (e.g., a mixture of C4F8, CF4, O2, and argon in plasma) in the presence of the exposed etch-stop alumina film 119, thereby protecting the underlying layer. If necessary (e.g., after dielectric etching is complete), the exposed portion of the alumina etch-stop film can be removed by wet etching. Examples of wet etching compositions used for alumina removal include mixtures of ammonia and hydrogen peroxide and mixtures of bromine and methanol.

[0045] It should be noted that the provided alumina etch stop films can be used in a variety of different integration schemes, and their applications are not limited to... Figure 1A-1C The scheme is shown. Because cobalt is particularly prone to oxidation, it is especially advantageous to use the provided film on a substrate containing cobalt wires. Therefore, a method that allows the formation of an etch-stop film on cobalt without causing cobalt oxidation is very valuable.

[0046] exist Figure 2 The document provides a process flow diagram for a method of etching a stop layer using alumina. The process begins at step 201, where a semiconductor substrate with an exposed metal layer and an exposed dielectric layer is provided. For example, the substrate may include an exposed ULK dielectric layer and an exposed metal layer, such as a copper, tungsten, or cobalt layer. Figure 1AAn example of such a substrate is shown. Next, in step 203, an alumina etch-stop film is deposited on the substrate. Deposition is performed by reacting an aluminum-containing precursor (e.g., trialkylaluminum) with an alcohol or alkoxyaluminum, thereby forming alumina in the reaction. Typically, the reaction can be carried out using various methods (e.g., CVD and ALD). In some embodiments, it is preferable to carry out the reaction substantially on the surface of the substrate, thereby enabling a high level of control over the thickness of the formed layer. In other embodiments, the reaction is carried out substantially outside the surface of the substrate, for example, in the bulk of the processing chamber in CVD mode. The reaction is typically carried out without the use of plasma. However, plasma treatment can be used after the alumina film has been deposited to improve the quality of the film.

[0047] In one embodiment, the deposition of an alumina etch-stop film includes supplying an aluminum-containing precursor and an alcohol (or alkoxyaluminum) to a processing chamber and configuring process conditions for depositing the alumina film onto a substrate. Suitable volatile aluminum-containing precursors include, but are not limited to, organoaluminum compounds such as trimethylaluminum (TMA), dimethylaluminum hydride, triethylaluminum, triisobutylaluminum, and tris(diethylamino)aluminum. In some embodiments, aluminum halides (e.g., AlCl3) can be used as aluminum-containing precursors. In many embodiments, trialkylaluminum (e.g., TMA) is a preferred precursor. Examples of alcohols include methanol, ethanol, propanol (e.g., n-propanol or isopropanol), and butanol (e.g., tert-butanol). In some embodiments, alcohols having at least four carbon atoms are preferred (particularly when the aluminum-containing precursor is TMA) because they are less reactive than lower alcohols and the reaction can be more easily controlled, which is advantageous when it is necessary to deposit very thin films with a defined thickness. Butanol (especially tert-butanol) is particularly preferred because it is less reactive than lower alcohols and allows for good reaction control, while at the same time it is sufficiently volatile and can be easily handled in a vacuum chamber. In one preferred embodiment, the reaction of TMA with tert-butanol is used to form alumina.

[0048] Suitable examples of aluminum alkoxys include aluminum ethoxide (OEt)3 and aluminum isopropoxide Al(OiPr)3. For example, alumina films can be deposited by reacting TMA with aluminum isopropoxide, or by reacting AlCl3 with aluminum isopropoxide or aluminum ethoxide via ALD.

[0049] In some embodiments, the introduction of precursors and reactants is sequential. In some embodiments, the reaction occurs primarily on the surface of the substrate, and mixing of precursors and reactants is suppressed or not permitted in the main portion of the processing chamber. In other embodiments, mixing of precursors and reactants is permitted in the main portion of the processing chamber, and the reaction can occur on the surface of the substrate and in the main portion of the processing chamber volume.

[0050] In some implementations, alumina films are deposited by a combination of surface-based reaction (ALD) and CVD (CVD) from the bulk portion of the processing chamber. For example, if the precursor cannot be completely removed from the processing chamber after each adsorption step, both surface-based reaction and bulk deposition may occur.

[0051] In some embodiments, deposition is carried out at a temperature range of about 50-400°C and a pressure range of about 0.5-8 Torr. The flow rates of the aluminum-containing precursor and the alcohol (or aluminum alkoxy) will depend on the size of the processing chamber and are in the range of about 10-20000 sccm in some embodiments. When the aluminum-containing precursor and the alcohol (or aluminum alkoxy) are dosed sequentially, in some embodiments, each flows into the processing chamber for a duration of about 0.1-10 seconds.

[0052] Refer again Figure 2 The process flow diagram shows that after depositing the alumina etch stop film, the process continues as follows: Optionally, a dielectric diffusion barrier layer is deposited on and in contact with the alumina etch stop film, as shown in Figure 205. The diffusion barrier film can be, for example, an oxygen-doped silicon carbide layer deposited by PECVD.

[0053] Next, in operation 207, an ILD layer is deposited on an etch stop layer and an optional diffusion barrier film. The ILD layer is then etched at selected locations (after standard photolithographic patterning) to form a recessed feature. During etching, which is typically performed using fluorine-based chemicals, an alumina film protects the material beneath the etch stop layer from being etched.

[0054] exist Figure 3One exemplary process for depositing an alumina etch-stop film is illustrated. The process includes placing a semiconductor substrate in a processing chamber (e.g., an ALD processing chamber) and, in operation 301, providing an aluminum-containing precursor (e.g., TMA) to the processing chamber. In some embodiments, the aluminum-containing precursor is provided to the processing chamber using a carrier gas (such as N2 or an inert gas). The temperature and pressure in this step are selected such that the aluminum-containing precursor adsorbs onto the substrate surface. Next, in operation 303, the processing chamber is purged and / or evacuated to remove unadsorbed aluminum-containing precursor from the processing chamber. In some embodiments, the removal is substantially complete. In other embodiments, a portion of the aluminum-containing precursor remains in the processing chamber. The process continues at 305, where an alcohol (e.g., tert-butanol) or aluminum alkoxy (e.g., aluminum isopropoxide) is provided to the processing chamber. The alcohol (in vaporized form) is provided using a carrier gas such as N2 or an inert gas. Importantly, in some embodiments, the aluminum-containing precursor and the alcohol (or aluminum alkoxy) are introduced into the processing chamber via separate conduits, preventing mixing of these precursors during transport to the processing chamber. This allows the alcohol or aluminum alkoxy to react on the surface of the substrate. In the illustrated embodiment, the reaction occurs substantially on the surface of the substrate (e.g., more than 50% alumina is formed in the reaction on the surface). In other embodiments, the reaction may occur substantially outside the substrate surface (e.g., more than 50% of the alumina is formed in the main body of the processing chamber and then deposited on the substrate).

[0055] Next, in step 307, the processing chamber is purged and / or emptied to remove reaction products. Typically, one cycle of operations 301-307 forms an alumina film on the substrate with an average thickness between about 0.2 and 3 angstroms. In step 311, it is determined whether further deposition is needed. If the layer is not thick enough, operations 301-309 are repeated until an alumina film of the desired thickness is formed. Typically, the deposition process involves performing cycles 301-309 at least 4 times, for example at least 5 times, for example between about 5 and 20 times. Typically, the thickness of the deposited etch-stop film is between about 10 and 100 angstroms, for example between about 20 and 100 angstroms, for example about 30 angstroms.

[0056] Used according to Figure 3 Suitable process conditions for depositing alumina films using the method shown are provided in Table 1.

[0057] Table 1: Illustrative process conditions for depositing alumina films

[0058]

[0059] Note that although the deposition reaction is usually carried out in the absence of plasma, in some embodiments, the formed alumina film is subjected to plasma treatment after deposition.

[0060] In several experimental verification examples, according to Figure 3 The method shown uses TMA and tert-butanol as reactants to deposit alumina films. Deposition is carried out in an ALD processing chamber at a temperature of 250-350°C and a pressure of 1 Torr, with TMA and tert-butanol being added sequentially for 5 seconds each. The resulting alumina films were found to have a high density (3.0-3.2 g / cm³). 3 The alumina film exhibits an excellent combination of high dielectric constant (4-6) and low dielectric constant. When the alumina film was deposited on copper, no copper oxidation was observed by reflectance measurements. Similarly, when the alumina film was deposited on cobalt, no cobalt oxidation was observed by XPS. This is a surprising result, as copper, and especially cobalt, are highly susceptible to oxidation, and the formation of alumina-based films deposited by different methods (using TMA dosage followed by plasma treatment in CO2) showed oxidation of both copper and cobalt. Furthermore, the provided alumina film is characterized by a breakdown voltage greater than 11 MV / cm and approximately 5.10 at 4 MV / cm. -9 Amp / cm 2 The relatively low leakage current was observed. The experimentally obtained membrane was found to be essentially free of hydrogen and carbon (each less than 5 atomic percent), with an aluminum to oxygen ratio of approximately 2:3.

[0061] Furthermore, the experimentally obtained films exhibited good adhesion to copper and cobalt and were stable during annealing. After annealing at 400°C for 2 hours in an argon atmosphere, no damage to the underlying copper layer was observed. The provided films are superior to AlN films because they possess a higher density (greater than 3.0 g / cm³). 3 In contrast, the value for AlN films is approximately 2.7 g / cm³. 3 The films provided are superior to many alumina films deposited by other methods because they exhibit very low dielectric constants (e.g., k = 4–6, compared to k > 7 observed in contrast alumina films) and can be deposited on metals without causing oxidative damage.

[0062] Device

[0063] Another aspect of the embodiments disclosed herein is an apparatus configured to perform the method described herein. Suitable apparatus includes hardware for performing processing operations and a system controller having instructions for controlling the processing operations according to the disclosed implementation. In some embodiments, the apparatus includes having instructions for executing... Figure 2 or Figure 3 The system controller provides the program instructions for the method steps.

[0064] The hardware used to perform deposition process operations includes ALD (including iALD) processing chambers and CVD (including PECVD) processing chambers. In some embodiments, all operations of the provided method are performed in a single processing chamber. In other implementations, the substrate can be transferred from chamber to chamber to perform different steps of the method. The system controller will typically include one or more memory devices and one or more processors configured to execute instructions such that the apparatus will execute the method according to the disclosed implementation. A machine-readable medium containing instructions for controlling process operations according to the disclosed implementation may be coupled to the system controller.

[0065] In some embodiments, deposition is carried out in an iALD reactor, which is part of the Vector Excel deposition module available from LamResearch Corp. (Fremont, CA). While the illustrated apparatus has the capability to generate plasma, which can be used, for example, for the plasma post-processing of the formed alumina layer, it should be noted that plasma is not required for the formation of the alumina layer, and apparatus without a plasma generator can also be used.

[0066] A suitable processing chamber includes a support (wafer pedestal) for holding the wafer substrate during deposition, and conduits for delivering the aluminum-containing precursor and the alcohol (or aluminum alkoxide) into the processing chamber. In some embodiments, these conduits are separate conduits, with each conduit connected to a source of the aluminum-containing precursor and a source of the alcohol (or aluminum alkoxide), respectively. In some embodiments, the conduits are connected such that the aluminum-containing precursor and the alcohol (or aluminum alkoxide) cannot mix within the conduits (e.g., within the delivery lines). The apparatus is further configured for cleaning and / or evacuating the processing chamber, and for maintaining the required pressure and temperature within the processing chamber during deposition.

[0067] Examples of iALD processing chambers are described in U.S. Patent Nos. 6,416,822, 6,428,859 and 8,747,964, the entire contents of which are incorporated herein by reference.

[0068] Figure 4 An embodiment of a processing station 400 that can be used to deposit films using atomic layer deposition (ALD) is schematically illustrated. The illustrated apparatus has the capability to generate plasma and can be used for both thermal ALD mode and ion-induced iALD mode. In the provided process, plasma treatment is not used during alumina deposition but can be used after alumina film deposition.

[0069] For simplicity, processing station 400 is described as a standalone processing station having a processing chamber body 402 for maintaining a low-pressure environment. However, it should be understood that multiple processing stations 400 may be included in a common processing tool environment. Furthermore, it should be understood that in some embodiments, one or more hardware parameters of processing station 400, including those discussed in detail below, can be programmed and adjusted by one or more computer controllers.

[0070] Processing station 400 is in fluid communication with reactant delivery system 401 to deliver process gas to distribution nozzle 406. Reactant delivery system 401 includes a mixing container 404 for mixing and / or regulating the process gas for delivery to nozzle 406. One or more mixing container inlet valves 420 control the introduction of process gas into mixing container 404. Similarly, nozzle inlet valve 405 controls the introduction of process gas into nozzle 406.

[0071] Some reactants can be stored in liquid form before vaporization and then transported to a processing station. For example, Figure 4 Implementations include a vaporization point 403 for vaporizing liquid reactants to be supplied to mixing vessel 404. In some embodiments, vaporization point 403 may be a heated evaporator. The reactant gas phase generated from such an evaporator may condense in a downstream delivery line. Exposing incompatible gases to the condensed reactants can produce small particles. These particles can clog lines, impede valve operation, contaminate substrates, etc. Some methods for addressing these problems involve purging and / or evacuating the delivery line to remove residual reactants. However, purging the delivery line can increase the processing station's cycle time and reduce its throughput. Therefore, in some embodiments, the delivery line downstream of vaporization point 403 may also be thermally tracked. In some examples, mixing vessel 404 may also be thermally tracked. In a non-limiting example, the line downstream of vaporization point 403 has a temperature profile that increases from about 100°C to about 150°C at mixing vessel 404.

[0072] In some embodiments, the reactant liquid can be vaporized at a liquid injector. For example, the liquid injector can inject pulsed liquid reactants into a carrier gas flow upstream of the mixing vessel. In one case, the liquid injector can vaporize the reactants by flashing the liquid from high pressure to low pressure. In another case, the liquid injector can atomize the liquid into dispersed droplets, which are then vaporized in a heated delivery line. It should be understood that slightly smaller droplets vaporize faster than slightly larger droplets, thereby reducing the delay between liquid injection and complete vaporization. Faster vaporization can reduce the length of the line downstream of vaporization point 403. In one case, the liquid injector can be directly mounted to the mixing vessel 404. In another case, the liquid injector can be directly mounted to the nozzle 406.

[0073] In some embodiments, a liquid flow controller may be provided upstream of the vaporization point 403 to control the mass flow rate of the liquid used for vaporization and delivery to the treatment station 400. For example, the liquid flow controller (LFC) may include a thermal mass flow meter (MFM) located downstream of the LFC. The plunger valve of the LFC can then be adjusted in response to a feedback control signal provided by a proportional-integral-derivative (PID) controller electrically communicating with the MFM. However, using feedback control to stabilize the liquid flow may take a second or longer. This can prolong the time required to dispense the liquid reactants. Therefore, in some embodiments, the LFC may dynamically switch between a feedback control mode and a direct control mode. In some embodiments, the LFC may dynamically switch from a feedback control mode to a direct control mode by disabling the sensing tubes of both the LFC and the PID controller.

[0074] In some embodiments, to avoid mixing of the aluminum-containing precursor with the alcohol (or aluminum alkoxy) , separate conduits 436 and 434 are used to connect the source of the aluminum-containing precursor 430 and the source of the silicon-containing precursor 432 to the nozzle, respectively, to ensure that these precursors are delivered separately to the processing chamber. The aluminum-containing precursor and the alcohol (or aluminum alkoxy) can be mixed separately with the carrier gas and evaporated (if desired).

[0075] Nozzle 406 dispenses process gas toward substrate 412. Figure 4 In the illustrated embodiment, the substrate 412 is located below the nozzle 406 and is shown resting on the base 408. It should be understood that the nozzle 406 may have any suitable shape and may have any suitable number and port configuration to distribute process gases to the substrate 412.

[0076] In some implementations, the microvolume 407 is located below the nozzle 406. Performing the ALD process in a microvolume, rather than throughout the entire volume of the processing station, reduces reactant exposure and purging time, reduces the number of times process conditions (e.g., pressure, temperature, etc.) can be changed, limits the exposure of the processing station's robotic arms to process gases, and so on. Example microvolume sizes include, but are not limited to, volumes between 0.1 liters and 2 liters. This small volume also affects productivity. As the deposition rate decreases per cycle, the cycle time also decreases. In some cases, the latter effect is large enough to increase the overall throughput of a module for a given target film thickness.

[0077] In some embodiments, the pedestal 408 may be raised or lowered to expose the substrate 412 to the microvolume 407 and / or to alter the volume of the microvolume 407. For example, during the substrate transfer stage, the pedestal 408 may be lowered to allow the substrate 412 to be loaded onto the pedestal 408. During the deposition process, the pedestal 408 may be raised to position the substrate 412 within the microvolume 407. In some embodiments, the microvolume 407 may completely surround the substrate 412 and a portion of the pedestal 408 to create a region with high flow resistance during the deposition process.

[0078] Optionally, the base 408 may be lowered and / or raised during portions of the deposition process to regulate process pressure, reactant concentration, etc., within the microvolume 407. Lowering the base 408 allows the microvolume 407 to be emptied, provided that the processing chamber body 402 maintains a basic pressure during the deposition process. Examples of microvolume-to-chamber volume ratios include, but are not limited to, volume ratios between 1:900 and 1:10. It should be understood that in some embodiments, the base height may be adjusted by programming using a suitable computer controller.

[0079] In another scenario, adjusting the height of the pedestal 408 allows the plasma density to vary during plasma activation and / or processing cycles included in the deposition process. At the end of the deposition process stage, the pedestal 408 can be lowered during another substrate transfer stage to allow the substrate 412 to be removed from the pedestal 408.

[0080] While the exemplary microvolume changes described herein involve a height-adjustable base, it should be understood that in some embodiments, the position of the nozzle 406 may be adjusted relative to the base 408 to change the volume of the microvolume 407. Furthermore, it should be understood that the vertical position of the base 408 and / or the nozzle 406 can be changed by any suitable mechanism within the scope of this disclosure. In some embodiments, the base 408 may include a rotation axis for the orientation of rotating the substrate 412. It should be understood that in some embodiments, one or more of these exemplary adjustments may be performed by one or more suitable computer controllers through programming.

[0081] Return to Figure 4The embodiment shown is illustrated. Nozzle 406 and base 408 are electrically connected to RF power source 414 and matching network 416 to provide power to the plasma. In some embodiments, the energy of the plasma can be controlled by controlling one or more of the following: pressure of the processing station, gas concentration, RF source power, radio frequency source frequency, and plasma power pulse timing. For example, RF power source 414 and matching network 416 can operate at any suitable power to form a plasma with a desired free radical material composition. Examples of suitable power are included above. Similarly, RF power source 414 can provide RF power at any suitable frequency. In some embodiments, RF power source 414 can be configured to control high-frequency RF power and low-frequency RF power independently of each other. Examples of low-frequency RF frequencies may include, but are not limited to, frequencies between 50 kHz and 900 kHz. Examples of high-frequency RF frequencies may include, but are not limited to, frequencies between 1.8 MHz and 2.45 GHz. It should be understood that any suitable parameters can be adjusted discretely or continuously to provide plasma energy for the surface reaction. In a non-limiting example, the plasma power can be intermittently pulsed to reduce ion bombardment of the substrate surface relative to continuously excited plasma.

[0082] In some embodiments, the plasma can be monitored in situ by one or more plasma monitors. In one case, plasma power can be monitored by one or more voltage and current sensors (e.g., VI probes). In another case, plasma density and / or the concentration of process gases can be measured by one or more optical emission spectrometers (OES) sensors. In some embodiments, one or more plasma parameters can be programmed to adjust based on measurements from such in-situ plasma monitors. For example, OES sensors can be used in feedback loops to provide programmable control of plasma power. It should be understood that in some embodiments, other monitors can be used to monitor plasma and other process characteristics. Such monitors may include, but are not limited to, infrared (IR) monitors, acoustic monitors, and pressure sensors.

[0083] In some implementations, the plasma can be controlled via input / output control (IOC) sequencing instructions. In one example, instructions for setting the plasma conditions for the plasma processing stage may be included in a corresponding plasma activation formulation stage of the deposition process formulation. In some cases, the formulation stages may be arranged sequentially such that all instructions for the deposition process stage are executed synchronously with that process stage. In some implementations, instructions for setting one or more plasma parameters may be included in a formulation stage preceding the plasma process stage. For example, a first formulation stage may include instructions for setting the flow rates of the inert gas and / or reactant gas, instructions for setting the plasma generator to a power setpoint, and time delay instructions for the first formulation stage. A subsequent second formulation stage may include instructions for enabling the plasma generator and time delay instructions for the second formulation. A third formulation stage may include instructions for disabling the plasma generator and time delay instructions for the third formulation. It should be understood that these formulations may be further subdivided and / or repeated in any suitable manner within the scope of this disclosure.

[0084] In some deposition processes, plasma excitation lasts for durations on the order of seconds or longer. In some implementations, much shorter plasma excitations can be used. These can range from 10 milliseconds to 1 second, typically from about 20 to 80 milliseconds, with 50 milliseconds being a specific example. Such short RF plasma excitations require extremely rapid plasma stabilization. To achieve this, the plasma generator can be configured such that impedance matching is preset to a specific voltage, while the frequency is allowed to fluctuate. Conventionally, high-frequency plasmas are generated at an RF frequency of approximately 13.56 MHz. In the various embodiments disclosed herein, the frequency is allowed to fluctuate to values ​​different from this standard value. By allowing frequency fluctuations while simultaneously fixing the impedance matching to a predetermined voltage, the plasma can stabilize much more rapidly, which is important when using very short plasma excitations associated with certain types of deposition cycles.

[0085] In some embodiments, the base 408 can be temperature-controlled via a heater 410. Furthermore, in some embodiments, pressure control for the deposition processing station 400 can be provided by a butterfly valve 418. (As in...) Figure 4 As shown in the embodiment, the butterfly valve 418 throttles the vacuum provided by the downstream vacuum pump (not shown). However, in some embodiments, the pressure control of the processing station 400 can also be adjusted by changing the flow rate of one or more gases introduced into the processing station 400.

[0086] In some embodiments, the substrates provided herein are processed in a multi-station tool. Figure 5A schematic diagram of an embodiment of a multi-station processing tool 500 is shown. The multi-station processing tool 500 has an inbound loading lock 502 and an outbound loading lock 504, either or both of which may include a remote plasma source. At atmospheric pressure, a robotic arm 506 is configured to move a wafer from a cassette loaded via a crystal boat 508 to the inbound loading lock 502 through an atmospheric port 510. The wafer is placed on a base 512 within the inbound loading lock 502 by the robotic arm 506, the atmospheric port 510 is closed, and the loading lock is evacuated. The inbound loading lock 502 includes a remote plasma source, and the wafer can be exposed to remote plasma processing within the loading lock before being introduced into a processing chamber 514. Furthermore, the wafer can also be heated within the inbound loading lock 502, for example, to remove moisture and adsorbed gases. Next, the chamber transfer port 516 leading to the processing chamber 514 is opened, and another robotic arm (not shown) places the wafer into the reactor on the base shown in the reactor for processing.

[0087] The depicted processing room 514 includes four processing stations, in Figure 5 In the illustrated embodiments, stations are numbered 1 through 4. Each station has a heating base (shown as 518 for station 1) and a gas line inlet. It should be understood that in some embodiments, each processing station may have different or multiple uses. Although the depicted processing chamber 514 includes four stations, it should be understood that a processing chamber according to this disclosure may have any suitable number of stations. In some embodiments, a processing chamber may have five or more stations, while in other embodiments, a processing chamber may have three or fewer stations.

[0088] Figure 5 One embodiment of a wafer handling system 590 for transferring wafers within a processing chamber 514 is also described. In some embodiments, the wafer handling system 590 can transfer wafers between various processing stations and / or between a processing station and a loading lock. It should be understood that any suitable wafer handling system can be employed. Non-limiting examples include wafer rotary conveyors and wafer handling robots. Figure 5 An embodiment of a system controller 550 for controlling the process conditions and hardware status of the processing tool 500 is also described. The system controller 550 may include one or more memory devices 556, one or more mass storage devices 554, and one or more processors 552. The processor 552 may include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, etc.

[0089] In some embodiments, system controller 550 controls all activities of processing tool 500. System controller 550 executes system control software 558, which is stored in mass storage device 554, loaded into memory device 556, and executed on processor 552. System control software 558 may include instructions for controlling timing, gas mixing, chamber and / or station pressure, chamber and / or station temperature, purge conditions and timing, wafer temperature, RF power level, RF frequency, substrate, pedestal, chuck and / or base position, and other parameters for specific processes performed by processing tool 500. System control software 558 can be configured in any suitable manner. For example, various processing tool component subroutines or controlled objects can be written to control the operation of processing tool components required to perform various processing tool processes according to the disclosed methods. System control software 558 can be coded in any suitable computer-readable programming language.

[0090] In some embodiments, the system control software 558 may include input / output control (IOC) sequencing instructions for controlling the various parameters described above. For example, each stage of the ALD process may include one or more instructions for execution by the system controller 550. Instructions for setting the process conditions for an ALD process stage may, for example, be included in the corresponding ALD formulation stage. In some embodiments, these ALD formulation stages may be arranged sequentially such that all instructions for an ALD treatment stage are executed simultaneously with that treatment stage.

[0091] In some implementations, additional computer software and / or programs may be employed, stored on a mass storage device 554 and / or a memory device 556 associated with the system controller 550. Examples of programs or program segments used for this purpose include substrate positioning programs, process gas control programs, pressure control programs, heater control programs, and plasma control programs.

[0092] The substrate positioning procedure may include program code for a processing tool assembly that loads the substrate onto the base 518 and controls the spacing between the substrate and other components of the processing tool 500.

[0093] The process gas control program may include code for controlling the gas composition and flow rate, and optionally for allowing the gas to flow into one or more processing stations prior to deposition to stabilize the pressure within the processing station. The process gas control program may include code for controlling the gas composition and flow rate within any range disclosed. The pressure control program may include code for controlling the pressure within the processing station by, for example, throttling valves in the processing station's exhaust system, regulating the gas flow rate into the processing station, etc. The pressure control program may include code for maintaining the pressure within the processing station within any range disclosed.

[0094] The heater control program may include code for controlling the current flowing to the heating element used to heat the substrate. Alternatively, the heater control program may control the delivery of a heat transfer gas (such as helium) toward the substrate. The heater control program may include instructions for maintaining the temperature of the substrate within any range disclosed.

[0095] The plasma control program may include code for setting the RF power level and frequency applied to the processing electrodes in one or more processing stations, such as using any RF power level disclosed herein. The plasma control program may also include code for controlling the duration of each plasma exposure.

[0096] In some implementations, a user interface may be associated with the system controller 550. The user interface may include a display screen, a graphical software display of the device and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0097] In some implementations, the parameters adjusted by the system controller 550 relate to process conditions. Non-limiting examples include process gas composition and flow rate, temperature, pressure, plasma conditions (e.g., RF power level, frequency, and exposure time), and so on. These parameters can be provided to the user in the form of a recipe, which can be input using the user interface.

[0098] Signals used for monitoring the process can be provided from various processing tool sensors via analog and / or digital input connections of system controller 550. Signals used for controlling the process can be output via analog and digital output connections of processing tool 500. Non-limiting examples of processing tool sensors that can be monitored include mass flow controllers, pressure sensors (e.g., pressure gauges), thermocouples, etc. Appropriately programmed feedback and control algorithms can be used with data from these sensors to maintain process conditions.

[0099] The disclosed embodiments can be implemented using any suitable chamber. Exemplary deposition apparatuses include, but are not limited to, those from... Product series Product lines and / or The device can be from any of the product family (each available from Lam Research Corp., Fremont, California) or a variety of other commercially available processing systems. Two or more stations can perform the same function. Similarly, two or more stations can perform different functions. Each station can be designed / configured to perform a specific function / method as needed.

[0100] Figure 6 This is a block diagram of a processing system suitable for performing thin film deposition processes according to certain embodiments of the present invention. The system 600 includes a transfer module 603. The transfer module 603 provides a clean, pressurized environment to minimize the risk of substrate contamination as the substrate being processed moves between different reactor modules. Mounted on the transfer module 603 are two multi-station reactors 609 and 610, each capable of performing atomic layer deposition (ALD) and / or chemical vapor deposition (CVD) according to certain embodiments. Reactors 609 and 610 may include multiple stations 611, 613, 615, and 617 that can operate sequentially or non-sequentially according to the disclosed embodiments. These stations may include a heating base or substrate support, one or more gas inlets or nozzles or dispersion plates.

[0101] Alternatively, one or more single- or multi-station modules 607 may be mounted on the transfer module 603, capable of performing plasma or chemical (non-plasma) pre-cleaning or any other process described in relation to the disclosed method. The module 607 may also be used for various processes in certain situations, such as preparing substrates for deposition processes. The module 607 may also be designed / configured to perform various other processes, such as etching or polishing. The system 600 also includes one or more wafer source modules 601, where wafers are stored before and after processing. An atmospheric manipulator (not shown) in the atmospheric transfer chamber 619 can first move the wafer from the source module 601 to the loading lock 621. Wafer transfer devices (typically robotic arm units) in the transfer module 603 move the wafer from the loading lock 621 to modules mounted on the transfer module 603 and move the wafer between these modules.

[0102] In various implementations, a system controller 629 is used to control the process conditions during the deposition process. The controller 629 will typically include one or more memory devices and one or more processors. The processor may include a CPU or computer, analog and / or digital input / output connections, a stepper motor controller board, etc.

[0103] The controller 629 controls the activities of all deposition equipment. The system controller 629 runs system control software, which includes a set of instructions for controlling timing, gas mixing, chamber pressure, chamber temperature, wafer temperature, radio frequency (RF) power levels, wafer chuck or pedestal position, and other process-specific parameters. In some embodiments, additional computer programs stored on memory devices associated with the controller 629 may be used.

[0104] Typically, a user interface will be associated with the controller 629. The user interface may include a display screen, a graphical software display of the device and / or process conditions, and user input devices such as pointing devices, keyboards, touch screens, microphones, etc.

[0105] The system control logic can be configured in any suitable manner. Generally, this logic can be designed or configured in hardware and / or software. Instructions for controlling the drive circuitry can be hard-coded or provided as software. These instructions can be provided through "programming." Such programming is understood to include any form of logic, including hard-coded logic in digital signal processors, application-specific integrated circuits (ASICs), and other devices with specific algorithms implemented in hardware. Programming is also understood to include software or firmware instructions executable on a general-purpose processor. The system control software can be encoded in any suitable computer-readable programming language.

[0106] The computer program code used to control the germanium-containing reducing agent pulse, hydrogen flow rate, and tungsten-containing precursor pulse, as well as other processes, in the process sequence can be written in any conventional computer-readable programming language: for example, assembly language, C, C++, Pascal, Fortran, or others. The compiled object code or script is executed by the processor to perform the tasks identified in the program. Also, as indicated, the program code can be hard-coded.

[0107] The controller parameters relate to process conditions such as, for example, process gas composition and flow rate, temperature, pressure, cooling gas pressure, substrate temperature, and chamber wall temperature. These parameters are provided to the user in the form of a recipe and can be input via a user interface. Signals for monitoring the process can be provided through analog and / or digital input connections to the system controller 629. Signals for controlling the process are output through analog and digital output connections to the deposition apparatus 620.

[0108] The system software can be designed or configured in many different ways. For example, multiple chamber assembly subroutines or control targets can be written to control the operation of the chamber assembly required to perform the deposition process (and in some cases other processes) according to the disclosed embodiments. Examples of programs or program segments used for this purpose include substrate positioning code, process gas control code, pressure control code, and heater control code.

[0109] In some embodiments, controller 629 is part of a system that may be part of the embodiments described above. Such systems include semiconductor processing apparatuses that include one or more processing tools, one or more chambers, one or more platforms for processing, and / or specific processing components (wafer pedestals, gas flow systems, etc.). These systems may be integrated with electronics to control their operation before, during, or after the processing of a semiconductor wafer or substrate. The electronics may be referred to as a “controller” that controls various components or sub-sections of one or more systems. Depending on the processing requirements and / or the type of system, controller 629 may be programmed to control any of the processes disclosed in this invention, including controlling the delivery of processing gases, temperature settings (e.g., heating and / or cooling), pressure settings, vacuum settings, power settings, radio frequency (RF) generator settings in some systems, RF matching circuit settings, frequency settings, flow rate settings, fluid delivery settings, position and operation settings, wafer transfer tools and other transfer tools, and / or the transfer of loading locks connected to or interfaced with a particular system.

[0110] In a broad sense, a controller can be defined as an electronic device with various integrated circuits, logic, memory, and / or software that receives instructions, issues instructions, controls operations, enables cleaning operations, enables endpoint measurements, etc. The integrated circuit may include a chip storing program instructions in firmware form, a digital signal processor (DSP), a chip defined as an application-specific integrated circuit (ASIC), and / or one or more microprocessors or microcontrollers that execute program instructions (e.g., software). Program instructions may be instructions delivered to the controller or system in various settings (or program files) that define operational parameters for performing specific processes on or for a semiconductor wafer. In some embodiments, these operational parameters may be part of a recipe defined by a process engineer to perform one or more processing steps in the fabrication process of one or more layers, materials, metals, oxides, silicon, silica, surfaces, circuits, and / or bare dies of a wafer.

[0111] In some implementations, the controller may be part of or coupled to a computer integrated with, coupled to, or networked with the system or a combination thereof. For example, the controller may be in the “cloud” or be a part of the main computer system of a wafer fab, allowing remote access to wafer processing. The computer may enable remote access to the system to monitor the current progress of manufacturing operations, examine the history of past manufacturing operations, examine trends or performance criteria of multiple manufacturing operations to change parameters of the current process, set processing steps to follow the current process, or start a new process. In some embodiments, the remote computer (e.g., a server) may provide process recipes to the system via a network, which may include a local network or the Internet. The remote computer may include a user interface that allows input or programming of parameters and / or settings, which are then transmitted from the remote computer to the system. In some examples, the controller receives instructions in the form of data specifying parameters for each processing step to be performed during one or more operations. It should be understood that these parameters may be specific to the type of process to be performed and the type of tool, to which the controller is configured to connect to or control. Therefore, as described above, the controller can be distributed, for example, by comprising one or more discrete controllers connected together via a network and working toward a common goal (e.g., the process and control described herein). An example of a distributed controller for these purposes would be one or more integrated circuits located indoors that communicate with one or more remote integrated circuits (e.g., at the platform level or as part of a remote computer), which together control the process within the indoor environment.

[0112] Exemplary systems may include, but are not limited to, plasma etching chambers or modules, deposition chambers or modules, rotary rinsing chambers or modules, metal plating chambers or modules, cleaning chambers or modules, chamfering edge etching chambers or modules, physical vapor deposition (PVD) chambers or modules, chemical vapor deposition (CVD) chambers or modules, atomic layer deposition (ALD) chambers or modules, atomic layer etching (ALE) chambers or modules, ion implantation chambers or modules, orbital chambers or modules, and any other semiconductor processing systems that may be associated with or used in the fabrication and / or manufacturing of semiconductor wafers.

[0113] As described above, depending on one or more process steps the tool is to perform, the controller may communicate with one or more other tool circuits or modules, other tool components, combined tools, other tool interfaces, adjacent tools, neighboring tools, tools located throughout the plant, a host, another controller, or tools used in material handling that move wafer containers to and from tool locations and / or loading ports within the semiconductor manufacturing plant.

[0114] Further implementation methods

[0115] The apparatus and processes described herein can be used in conjunction with photolithographic patterning tools or processes, for example, for the fabrication or manufacture of semiconductor devices, displays, LEDs, photovoltaic panels, etc. Typically, although not necessarily, such apparatus and processes will be used together or operated in a common manufacturing facility. Photolithographic patterning of films typically involves some or all of the following steps, each step enabling multiple feasible tools: (1) applying a photoresist to a workpiece, i.e., a substrate, using a spin coater or spray coater; (2) curing the photoresist using a hot plate or oven or a UV curing tool; (3) exposing the photoresist to visible light or UV or X-rays using a tool such as a wafer stepper; (4) developing the photoresist to selectively remove the photoresist and thereby patterning it using a tool such as a wet cleaning station; (5) transferring the photoresist pattern onto the underlying film or workpiece using a dry or plasma-assisted etching tool; and (6) removing the photoresist using a tool such as an RF or microwave plasma stripper. This process can be used, for example, to pattern the dielectric layer on which tantalum nitride, tantalum, and / or copper layers are deposited as described above.

[0116] XPS Experiment Results

[0117] Using the process conditions shown in Table 1, an alumina film was deposited on a wafer substrate containing a cobalt layer by sequentially exposing the wafer substrate to TMA and tert-butanol. The cobalt layer was analyzed by XPS. Figure 7A XPS plots of the film at the wafer edge are shown. It can be seen that the XPS indicates the absence of significant signals attributed to cobalt-oxygen bonds. Similar results were obtained at the center of the wafer substrate.

[0118] Comparative alumina-based films were deposited by sequentially treating a substrate with a cobalt layer using TMA and CO2 plasma. The cobalt layer was analyzed by XPS. Figure 7B XPS plots of the film on the wafer edge provided in the image show significant cobalt-oxygen bonding. Similar results were obtained for the film obtained from the center of the wafer.

Claims

1. A method for processing a semiconductor substrate, the method comprising: (a) Providing a semiconductor substrate comprising at least one of an exposed dielectric layer and an exposed metal layer; as well as (b) An alumina film is formed on at least one of the dielectric layer and the metal layer by reacting an aluminum-containing precursor with a reactant selected from the group consisting of alcohols and aluminum alkoxy groups, wherein the alumina film contacts at least one of the dielectric layer and the metal layer, wherein the formed alumina film has a dielectric constant of less than 7 and a dielectric constant of at least 2.5 g / cm³. 3 The density.

2. The method of claim 1, wherein the semiconductor substrate comprises an exposed metal layer, wherein the exposed metal layer is an exposed cobalt layer.

3. The method according to claim 2, wherein after the alumina film is formed, no cobalt oxide is formed at the interface between the cobalt layer and the alumina film.

4. The method of claim 1, wherein forming the alumina film comprises reacting the aluminum-containing precursor with an alcohol containing at least four carbon atoms.

5. The method of claim 1, wherein forming the alumina film comprises reacting trimethylaluminum with tert-butanol.

6. The method of claim 1, wherein the alumina film is formed by a reaction occurring on the surface of the semiconductor substrate.

7. The method of claim 1, wherein the alumina film is formed by a reaction occurring outside the surface of the semiconductor substrate.

8. The method of claim 1, wherein the alumina film is formed with a thickness between 10 and 100 angstroms.

9. The method of claim 1, wherein forming the alumina film comprises: (i) In a processing chamber containing the semiconductor substrate, the aluminum-containing precursor is adsorbed onto the surface of the semiconductor substrate, wherein the aluminum-containing precursor is trialkylaluminum; (ii) After the aluminum-containing precursor has been adsorbed, clean and / or empty the processing chamber; (iii) After cleaning, an alcohol having at least four carbon atoms is provided to the treatment chamber, and the alcohol reacts with the adsorbed aluminum-containing precursor to form aluminum oxide; (iv) After the reaction, clean and / or empty the processing chamber; and (v) Repeat (i)-(iv).

10. The method of claim 9, wherein (iii) is performed in the absence of plasma.

11. The method according to claim 9, wherein the alumina film is formed at a temperature between 50 and 400°C and at a pressure between 0.5 and 8 Torr.

12. The method of claim 9, wherein (i) comprises flowing the aluminum-containing precursor into the processing chamber for 0.1-10 seconds.

13. The method of claim 9, wherein (iii) comprises flowing the alcohol into the processing chamber for 0.1-10 seconds.

14. The method of claim 9, wherein (v) comprises repeating (i) to (iv) at least three times.

15. The method according to claim 1, wherein the alumina film has a dielectric constant of less than 6 and a dielectric constant of at least 2.8 g / cm³. 3 The density.

16. The method according to claim 1, wherein the alumina film has a dielectric constant of 4-6 and a dielectric constant of 3.0-3.2 g / cm³. 3 The density.

17. The method according to claim 1, wherein, The semiconductor substrate provided in (a) includes an exposed dielectric layer.

18. The method of claim 1, further comprising: A photoresist is applied to the semiconductor substrate; Expose the photoresist to light; Pattern the photoresist and transfer the pattern to the semiconductor substrate; as well as The photoresist is selectively removed from the semiconductor substrate.

19. A method for processing a semiconductor substrate, the method comprising: (a) A semiconductor substrate including an exposed metal layer, wherein the metal layer is selected from the group consisting of a cobalt layer, a copper layer and a tungsten layer; as well as (b) An alumina film is formed on the metal layer by reacting an aluminum-containing precursor with a reactant selected from the group consisting of alcohols and aluminum alkoxy groups, and the alumina film is in contact with the metal layer, wherein the formation of the alumina film does not lead to the formation of metal oxides selected from the group consisting of cobalt oxide, copper oxide, and tungsten oxide, wherein the formed alumina film has a dielectric constant of less than 7 and a dielectric constant of at least 2.5 g / cm³. 3 The density.

20. The method of claim 19, wherein forming the alumina film comprises: (i) In a processing chamber containing the semiconductor substrate, the aluminum-containing precursor is adsorbed onto the surface of the semiconductor substrate, wherein the aluminum-containing precursor is trialkylaluminum; (ii) After the aluminum-containing precursor has been adsorbed, clean and / or empty the processing chamber; (iii) After cleaning, an alcohol having at least four carbon atoms is provided to the treatment chamber, and the alcohol reacts with the adsorbed aluminum-containing precursor to form aluminum oxide; (iv) After the reaction, clean and / or empty the processing chamber; and (v) Repeat (i)-(iv).

21. An apparatus for depositing an aluminum oxide layer on a semiconductor substrate, the apparatus comprising: (a) A processing chamber including a substrate support for holding the semiconductor substrate during the deposition of the alumina layer; (b) An inlet in the processing chamber for introducing reactants into the processing chamber; and (c) A controller containing program instructions for the following operations: A reaction is initiated between an aluminum-containing precursor and a reactant selected from the group consisting of alcohols and aluminum alkoxy groups, wherein the reaction forms an aluminum oxide layer on a metal selected from the group consisting of cobalt, copper, and tungsten, but not cobalt oxide, copper oxide, or tungsten oxide, wherein the formed aluminum oxide layer has a dielectric constant of less than 7 and a dielectric constant of at least 2.5 g / cm³. 3 The density.

22. A semiconductor device comprising: An alumina film is formed on a metal layer by reacting an aluminum-containing precursor with a reactant selected from the group consisting of alcohols and aluminum alkoxy groups, wherein the alumina film has a thickness between 10 and 50 angstroms and is characterized by a dielectric constant of less than 6 and a density of at least 2.8 g / cm³. 3 The aluminum oxide remains in contact with the metal layer, and the metal layer shows no signs of oxidation.

23. The semiconductor device of claim 22, wherein the alumina film further remains in contact with the dielectric layer.

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