KR20200135547A - Low temperature molybdenum film deposition using boron nucleation layer - Google Patents

Abstract

The present disclosure relates to a method of making a molybdenum film using a boron and molybdenum nucleation layer. The resulting molybdenum film has a low electrical resistivity, is substantially boron free, and can be produced at a reduced temperature compared to a conventional chemical vapor deposition process that does not use a boron or molybdenum nucleation layer. The molybdenum nucleation layer formed by this process can protect the substrate from the etching effect of MoCl ₅ or MoOCl ₄ , facilitate the nucleation of subsequent CVD Mo growth on top of the molybdenum nucleation layer, and further Allows Mo CVD deposition at low temperatures. The nucleation layer can also be used to control the particle size of the subsequent CVD Mo growth, thus controlling the electrical resistivity of the Mo film.

Description

Low temperature molybdenum film deposition using boron nucleation layer

Cross-reference of related applications

This application is a continuation in part of U.S. Patent Application No. 15/820,640 filed on November 22, 2017 claiming the benefit of U.S. Provisional Application No. 62/425,705 filed on November 23, 2016, the disclosure of which is all For the purpose, the entirety is incorporated herein by reference.

Technical field

The present disclosure relates to a vapor-deposited molybdenum film or layer that can be fabricated at lower processing temperatures while having a deposition rate similar to that achieved using traditional high temperature vapor deposition conditions for molybdenum. The resulting molybdenum film or layer formed by lower temperature evaporation also has a low resistivity and can be used in a variety of articles such as semiconductor devices and display devices.

Molybdenum is a low-resistivity refractory metal that can potentially replace tungsten as a material in memories, logic chips, and other devices that use polysilicon-metal gate electrode structures. Thin films containing molybdenum can also be used in some organic light emitting diodes, liquid crystal displays, and also thin film solar cells and photovoltaic cells. A thin molybdenum film can be used as a barrier film.

Various precursor and vapor deposition techniques have been used to deposit thin molybdenum films. Precursors include inorganic and organometallic reagents and vapor deposition techniques include chemical vapor deposition (CVD) and atomic layer deposition (ALD) as well as a number of modifications, such as UV laser photolysis CVD, plasma assisted CVD, and plasma assisted ALD. I can. CVD and ALD processes are increasingly being used because they can provide excellent conformal step coverage to the geometry of highly non-planar microelectronic devices, but the cost and complexity of plasma assisted deposition and high temperature deposition systems can drive manufacturing costs and tool costs. Can increase. High-temperature processes can also damage previously deposited or underlying structures.

In a typical CVD process, the precursor is passed over an optionally heated substrate (eg wafer) in a low pressure or ambient pressure reaction chamber. The precursors react and/or decompose on the surface of the substrate to create a thin film of a deposited material such as molybdenum. Volatile by-products are removed by gas flow through the reaction chamber. Some metal films are formed in a CVD process by the reaction of gases leading to the deposition of metal on the substrate by supplying two or more gases to the reaction chamber. The deposited film thickness and uniformity is dependent on the adjustment of many parameters such as temperature, pressure, gas flow rate and mixing uniformity, chemical depletion effect and time.

The refractory metal film is followed by heating a substrate such as silicon dioxide to a temperature of about 500° C. to 800° C. in a sealed chamber, and treating the heated surface with a vaporized material such as molybdenum hexafluoride for a short period of time. Increasing the adhesion of the surface to the molybdenum layer to be deposited with hydrogen, purging all unreacted molybdenum hexafluoride from the chamber, followed by mixing some newly vaporized molybdenum hexafluoride with hydrogen To reduce the molybdenum hexafluoride, generate HF(g), and deposit a molybdenum film on the heated surface by depositing a molybdenum film on the substrate. . The high temperature for these depositions complicates the processing equipment and consumes the thermal budget for temperature sensitive devices. In addition, the toxicity of HF(g) and the associated abatement and safety equipment for the handling of HF(g) make this process expensive and complicated.

A smooth, low-resistivity molybdenum film with excellent step coverage was obtained by chemical vapor deposition (CVD) using MoOCl ₄ or MoCl ₅ as a molybdenum precursor and H ₂ as a reducing gas at a high temperature of about 700°C. It can be deposited on the substrate. These high-temperature molybdenum films are useful, but the lower deposition temperatures are more because they consume less thermal budget of the materials used to make devices such as DRAM or photovoltaic cells, and the films can be made using less expensive and less complex equipment. It will be advantageous. As the temperature of the substrate was lowered to less than 700° C. during the deposition process, a reaction temperature cutoff of about 550° C. was observed for both MoOCl ₄ and MoCl ₅ . Around this temperature, the film roughness increases, the film resistivity increases, and the film deposition rate decreases, eventually stopping below the cutoff temperature. This cutoff temperature also limited the step coverage performance of the molybdenum film. A smooth low-resistivity molybdenum film with excellent step coverage is a very beneficial quality of thin films used in semiconductor device manufacturing.

There continues to be a need to fabricate molybdenum metal films and coatings on a variety of substrates at lower deposition temperatures and without complex and expensive heating and vapor abatement equipment.

In order to overcome the problems of high-temperature molybdenum processing, including coarse high-resistivity films formed between 550°C and 700°C, a boron decomposition layer or boron nucleation layer is deposited on a substrate, and subsequently it is at a temperature of less than 550°C. Was replaced with a high quality molybdenum nucleation layer on the substrate. The molybdenum nucleation layer prepared in this way, for example, protects the underlying substrate from the etching effect of MoCl ₅ to facilitate the nucleation of the subsequent smooth CVD Mo growth on top, and CVD at lower temperatures. It has been found to enable Mo deposition. The molybdenum nucleation layer can also be used to control the particle size of the subsequent CVD growth of bulk molybdenum, thus controlling the electrical resistivity of the final molybdenum film. In some cases, a large amount of boron, which can be seen by SEM, was found under the molybdenum layer, which increases the film resistivity. This was particularly a problem when multiple alternating layers of boron and molybdenum were deposited. The solution to the problem of high temperature molybdenum film formation and the presence of large amounts of boron in the deposited molybdenum nucleation layer is the reaction with a vapor containing molecules of molybdenum and chlorine, for example MoOCl ₄ or MoCl ₅ By consuming or replacing substantially all of the deposited solid boron nucleation layer on the substrate. This reaction forms a molybdenum nucleation layer and can take place in the presence or absence of a reducing gas such as hydrogen, at the same time replacing the boron nucleation layer. The resulting molybdenum nucleation layer uses, for example, a vapor composition comprising MoOCl ₄ or MoCl ₅ in the presence of a reducing gas such as hydrogen, to set the cutoff temperature for the subsequent bulk Mo CVD film formation process of MoOCl ₄ In the case of 400 ℃ to 575 ℃, in the case of MoCl ₅ is lowered to between 450 ℃ to 550 ℃. The molybdenum CVD film formed in this way had a low film resistivity, was smooth, and was chemically vapor deposited (CVD) at a high temperature of about 700° C. using MoOCl ₄ or MoCl ₅ as a molybdenum precursor and H ₂ as a reducing gas. ) It had better step coverage compared to the molybdenum film deposited on the substrate by molybdenum.

The present disclosure relates to compositions and methods for making a molybdenum nucleation layer on a substrate. Optionally, the substrate may itself be a molybdenum nucleation layer. Alternatively, the substrate may be substantially free of molybdenum.

The method may comprise the action or step of the reaction of a vapor composition comprising molecules containing molybdenum and chlorine atoms with a nucleation layer comprising an existing solid boron on a substrate. In some versions, the vapor composition is substantially free of reducing gas. The substrate is maintained at a temperature between 450° C. and 550° C., and the reaction with the vapor consumes at least a portion of the boron nucleation layer while forming a molybdenum nucleation layer over the substrate. In some versions, the molybdenum nucleation layer may be formed on a substrate maintained at a temperature between 450°C and 480°C. In some versions, the deposited molybdenum nucleation layer may have a thickness ranging from about 5 angstroms (5 Å) to about 100 angstroms (100 Å). Suitably, the thickness of the deposited molybdenum nucleation layer can range from about 5 to about 50 angstroms, optionally from 5 to about 30 angstroms, for example from about 5 to about 20 angstroms. Vapor compositions comprising molecules of molybdenum and chlorine may be present in a reaction chamber having a substrate heated at a pressure between 10 Torr and 60 Torr and in some versions between 20 Torr and 40 Torr.

One aspect of the present invention includes reacting a nucleation layer comprising boron on a substrate with a vapor composition comprising molecules containing molybdenum and chlorine atoms, wherein the substrate is at a temperature between 450°C and 550°C. Exist; The reaction provides a method for producing a molybdenum layer, wherein the reaction consumes at least a portion of the boron nucleation layer and forms a molybdenum nucleation layer over the substrate.

The nucleation layer comprising boron that is substantially consumed may have a thickness between about 5 Å and about 100 Å. Suitably, the thickness of the nucleation layer comprising boron may range from about 5 to about 50 angstroms, optionally from about 5 to about 30 angstroms, for example from about 5 to about 20 angstroms.

Advantageously, the nucleation layer comprising boron can be substantially consumed by the reaction, so that the molybdenum layer comprises less than 5 wt% boron, optionally less than 1 wt% boron by elemental analysis.

The boron nucleation layer can suitably be formed by decomposition of B ₂ H ₆ on a heated substrate. In some versions, the substrate is heated to 300° C. to 450° C. during boron nucleation layer deposition. Other boron containing precursors and conditions can be used to deposit the boron nucleation layer. For example, the same or substantially the same temperature used for the molybdenum deposition between 450° C. and 550° C. can be used for the deposition of the boron nucleation layer.

Thus, in some versions, the method includes depositing a nucleation layer comprising boron over a substrate, the substrate being at a temperature between 300°C and 550°C.

The method optionally comprises depositing a nucleation layer comprising additional boron over the molybdenum nucleation layer over the substrate, the substrate having a temperature between 300° C. and 550° C.; Optionally at a temperature of 300° C. to 450° C., and reacting the nucleation layer comprising additional boron with a vapor composition comprising molecules comprising molybdenum and chlorine atoms, wherein the substrate is 450° C. to 550° C. Is at a temperature between °C; The reaction includes consuming at least a portion of the additional boron nucleation layer and forming an additional molybdenum nucleation layer.

The thickness of the nucleation layer comprising additional boron may suitably be between 5 Å and 100 Å. Suitably, the thickness of the nucleation layer comprising additional boron may range from about 5 to about 50 angstroms, optionally from about 5 to about 30 angstroms, such as from about 5 to about 20 angstroms. The deposition thickness of the nucleation layer comprising additional boron may be less than the deposition thickness of the nucleation layer comprising boron on the substrate.

The method may include vapor deposition of a nucleation layer comprising boron over a substrate during a first period and vapor deposition of a nucleation layer comprising additional boron during a second period, the second period being Shorter than 1 period.

The nucleation layer comprising additional boron can be substantially consumed by the reaction, so that the additional molybdenum layer comprises less than 5 wt% boron, optionally less than 1 wt% boron by elemental analysis.

Advantageously, the deposition and reaction steps can be repeated to form a plurality of additional molybdenum nucleation layers.

Optionally, the molybdenum nucleation layer(s) may be formed on a substrate maintained at a temperature between 450°C and 480°C. Advantageously, the vapor composition can be at a pressure between 10 Torr and 60 Torr. The vapor composition may be substantially free of reducing gas.

It will be appreciated that the method may include manufacturing an upper molybdenum nucleation layer. A molybdenum nucleation layer or an additional molybdenum nucleation layer on the substrate may constitute an upper molybdenum nucleation layer.

Indeed, another version of the method for making an upper molybdenum nucleation layer comprises depositing a nucleation layer comprising boron over a substrate or over a molybdenum nucleation layer over the substrate, wherein the substrate or The molybdenum nucleation layer on the substrate is at a temperature between 300° C. and 550° C., optionally between 300° C. and 450° C., and subsequently contains a nucleation layer comprising boron and molecules containing molybdenum and chlorine atoms. And the reaction of the vapor composition, wherein the substrate is present at a temperature between 450°C and 550°C.

The reaction between the vapor composition and the boron layer consumes at least a portion of the boron nucleation layer to form the upper molybdenum nucleation layer. In this version of the method, the thickness of the nucleation layer comprising boron may be between 5 Å and 100 Å. Suitably, the thickness of the nucleation layer comprising boron may range from about 5 to about 50 angstroms, optionally from about 5 to about 30 angstroms, for example from about 5 to about 20 angstroms.

In some versions of the method of making an upper molybdenum layer on a substrate, consuming at least a portion of the boron nucleation layer substantially or completely consumes the boron nucleation layer. Consuming at least a portion of the boron nucleation layer can produce volatile boron compounds.

In various versions of the method of making an upper molybdenum nucleation layer, depositing a nucleation layer comprising boron (also referred to as a boron decomposition layer) and it comprising molecules containing molybdenum and chlorine. The step of reacting with the vapor composition may be repeated one or more times. The one or more molybdenum nucleation layers may be substantially free of boron, as determined from SEM analysis, elemental analysis, or electrical resistivity measurements.

The method of manufacturing the molybdenum nucleation layer may include vapor deposition of a bulk molybdenum layer over the upper molybdenum nucleation layer at a temperature between 450°C and 550°C. The molybdenum complex can be used to vapor-deposit a bulk molybdenum layer. In some versions, the molybdenum complex contains molybdenum and chlorine. In another version, the molybdenum complex may comprise MoCl ₅ or may comprise MoOCl ₄ .

Suitably, the thickness of the film may be 200 angstroms or more, and the resistivity of the molybdenum film is ±10% of a substantially similar thickness deposited from the molybdenum complex on a 700° C. substrate without a molybdenum nucleation layer. It may be ±20% of the resistivity measured at room temperature (RT, 20°C-23°C) of the ribdenum film.

In a version of the method of making a molybdenum film, the molybdenum film over the substrate comprises a top bulk molybdenum layer and at least one bottom molybdenum nucleation layer. The molybdenum film may have an electrical resistivity of less than 25 μΩ·cm for a layer thickness of a molybdenum film of 200 angstroms or more, and in some versions the molybdenum film may have an electrical resistivity of less than 20 μΩ·cm for a layer thickness of a molybdenum layer of 200 angstroms or more Have. Low-resistivity molybdenum films consume lower power and generate less heat than devices with higher resistivity molybdenum films.

In another version of the method of making a molybdenum film, the molybdenum film over the substrate includes a top bulk molybdenum layer and one or more bottom molybdenum nucleation layers. The molybdenum film on the substrate can have an electrical resistivity measured at room temperature (RT, 20°C-23°C) between 10 μΩ·cm and 25 μΩ·cm for a molybdenum film having a thickness between 800 angstroms and 200 angstroms. And, in some versions, the electrical resistivity may be between 12 μΩ·cm and 25 μΩ·cm, and in some other versions, the electrical resistivity may be between 10 μΩ·cm and 20 μΩ·cm. In some versions, the molybdenum film has a thickness of 200 Å to 1000 Å. In another version of the method for making a molybdenum film, the resistivity of the molybdenum film is at room temperature (RT, 20° C.-23° C.) of a vapor deposited molybdenum film of similar thickness ±10% deposited on a similar substrate at 700° C. It may be within ±20% of the measured resistivity.

One version of a method of making a molybdenum film on a substrate includes exposing the substrate to a B ₂ H ₆ gas at a temperature range of 250° C. to 550° C. and a pressure range of 10 Torr to 60 Torr; Forming a solid boron nucleation layer on the substrate surface; Exposing the boron nucleation layer to a vapor comprising molybdenum and chlorine atoms at a temperature above 450° C. and converting the boron layer to a molybdenum nucleation layer and BCl ₃ (g) or BOCl (g) Producing a boron compound such as; Optionally repeating the first four steps at least once to form an additional molybdenum nucleation layer; And CVD deposition of molybdenum on the upper molybdenum nucleation layer at a temperature of 550° C. or lower by H ₂ reduction of the molybdenum complex containing molybdenum and chlorine atoms. have.

Another version of making a molybdenum film on a substrate involves first exposing the substrate to a B ₂ H ₆ gas at a temperature range of 300° C. to 550° C. and a pressure range of 10 Torr to 60 Torr. A boron decomposition or boron nucleation layer is formed on the substrate surface, and the thickness of this layer can be controlled by the B ₂ H ₆ flow and dosing time. The boron layer is then exposed to MoCl ₅ at a temperature above 450°C. The reaction converts the boron layer into a molybdenum nucleation layer with a volatile gas comprising BCl ₃ (g) or BOCl (g) as a by-product. The thickness of the resulting molybdenum nucleation layer is dependent on the starting thickness of the boron decomposition layer. The process of preparing a boron nucleation layer and converting it to a molybdenum nucleation layer can be repeated multiple times until the desired upper molybdenum nucleation layer is achieved. Subsequently, conventional CVD molybdenum deposition can proceed on the upper molybdenum nucleation layer. The molybdenum nucleation layer can help lower the CVD molybdenum deposition temperature cut-off from 550°C to 450°C. The CVD molybdenum film deposited on the upper nucleation layer has low roughness and excellent step coverage for deep via structures.

A version of the method of manufacturing a molybdenum film can be performed in a manufacturing process of forming a semiconductor device on a substrate. Molybdenum films of the present disclosure may also be deposited during the manufacture of various electronic, display, or photovoltaic devices. Examples of electronic devices include digital memory storage used for flash memory devices and dynamic random access devices (DRAM) for 3-D NAND logic gates.

The present disclosure relates to a method of making a molybdenum film on a substrate using a boron and molybdenum nucleation layer. The resulting molybdenum film may have a low electrical resistivity, may be substantially free of boron, and be prepared at a reduced temperature compared to a conventional chemical vapor deposition process that does not use a boron or molybdenum nucleation layer. I can. The molybdenum nucleation layer formed by this process can protect the substrate from the etching effect of chlorine-containing precursors such as MoCl ₅ or MoOCl _4, and facilitate the nucleation of subsequent CVD Mo growth on the molybdenum nucleation layer. And allows molybdenum CVD deposition at lower temperatures. The molybdenum nucleation layer can also be used to control the particle size of the subsequent CVD molybdenum growth, thus controlling the electrical resistivity of the final molybdenum film.

The boron nucleation layer may be formed by first exposing the substrate (which may include a thin overlying film) to a B ₂ H ₆ gas in a temperature range of 300°C to 550°C and a pressure range of 10 Torr to 60 Torr. A solid nucleation or decomposition layer containing boron is formed on the substrate surface (or a thin film overlying it), and the thickness of the nucleation layer containing boron or the decomposition layer containing boron is B ₂ H ₆ flow and administration time Can be controlled by The thickness of the nucleation layer including boron may be between 5 Å and 100 Å. Suitably, the thickness of the nucleation layer comprising boron may range from about 5 to about 50 angstroms, optionally from 5 to about 30 angstroms, for example from about 5 to about 20 angstroms.

The molybdenum nucleation layer can be formed by exposing and reacting the boron nucleation layer to a vapor composition comprising molybdenum, chlorine and optionally oxygen at elevated temperature. The reaction with this vapor composition consumes the boron nucleation layer and replaces it with the molybdenum nucleation layer. The vapor composition may include MoCl ₅ , MoOCl ₄ or other materials. For example, a substrate having a boron nucleation layer or may be maintained at a temperature between 450 ℃ to 550 ℃ in stages in the reactor, can include MoCl _5, or exposed to the composition composed of these only, MoCl ₅ and argon ( It may be exposed to a composition that may be a mixture comprising an inert gas such as Ar), or may be exposed to a composition that may be a mixture comprising a reducing gas such as MoCl ₅ and hydrogen (H ₂ ). In another example, it may be a substrate on a heated stage with a boron nucleation layer is maintained at a temperature between 450 ℃ to 550 ℃, may be included, or exposed to a composition consisting of those of MoOCl _4, MoOCl _4, and Ar It may be exposed to a composition, which may be a mixture comprising an inert gas such as (Ar), or may be exposed to a composition, which may be a mixture comprising a reducing gas such as MoOCl ₄ and hydrogen (H ₂ ). Exposing the boron nucleation layer to one or more of these compositions at temperatures between 450° C. and 550° C. converts the boron nucleation layer into a nucleation layer comprising molybdenum.

BCl ₃ or other boron containing volatiles can be produced as a by-product of the conversion of the boron nucleation layer to the molybdenum nucleation layer. This reaction has a temperature cutoff of approximately 450°C.

In the presence of H ₂ , reaction by-products may include HCl, BCl ₃ and OCl ₂ (for vapor compositions comprising MoOCl ₄ ). The reaction can take place on the boron nucleation layer with or without the H ₂ co-reactant.

The thickness of the resulting molybdenum nucleation layer is dependent on the starting thickness of the boron nucleation layer. In some versions, a vapor composition comprising molybdenum, chlorine, and optionally oxygen but no reducing gas can be used to convert the boron nucleation layer to the molybdenum nucleation layer. The thickness of the resulting molybdenum nucleation layer is proportional to the thickness of the boron nucleation layer.

Advantageously, the steps of depositing the boron nucleation layer and reacting the boron nucleation layer to form the molybdenum nucleation layer may be repeated to form one or more additional boron nucleation layers.

When a plurality of boron nucleation layers are formed, they can be produced in substantially the same way. Alternatively, different conditions can be used for different layers, for example as described herein.

The method may include preparing an upper molybdenum nucleation layer. A molybdenum nucleation layer or an additional molybdenum nucleation layer on the substrate may constitute an upper molybdenum nucleation layer.

Versions of the molybdenum film formation process may further include the act or step of vapor depositing a molybdenum complex on an upper molybdenum nucleation layer on a substrate to form a bulk molybdenum layer. The bulk molybdenum layer and at least one lower molybdenum nucleation layer constitute a molybdenum film, the molybdenum film can have a thickness in the range of 50 Å to 3000 Å; In some versions, the thickness of the molybdenum film may be between 200 Å and 1000 Å. The substrate may be at a temperature between 450° C. and 550° C. during this bulk vapor deposition operation or step. In some versions, the molybdenum complex can be a vapor composition comprising molybdenum and chlorine atoms, and in other cases the molybdenum complex can be a vapor composition comprising molybdenum, chlorine and oxygen atoms. Examples of molybdenum complexes that can be used in the version of the method include MoCl ₅ and MoOCl ₄ .

Containing molybdenum and chlorine atoms for use in a method of forming a molybdenum film by vaporizing a composition comprising a molecule containing molybdenum and a chlorine atom or a molybdenum complex containing a molybdenum and a chlorine atom Vapor compositions can be prepared. The composition or complex may individually comprise MoCl ₅ (with molecular purity of 99% or higher in some versions) or MoOCl ₄ (with molecular purity of 99% or higher in some versions). In some versions, the molybdenum complex may be an organometallic molybdenum compound containing cyclopentadienyl and other ligands. Molybdenum complexes can be purified to a molecular purity greater than 99.99% by sublimation. For example, MoCl ₅ can be purified by sublimation to remove traces of higher vapor pressure MoOCl ₄ . Versions of the present disclosure may include ampoules configured for use in vapor deposition processes, which ampoules contain MoCl ₅ with a molecular purity greater than 99.99%. Another version of the present disclosure may include an ampoule configured for use in a vapor deposition process, the ampoule containing MoOCl ₄ with a molecular purity greater than 99.99%. Sublimation can be used to purify MoCl ₅ or MoOCl ₄ and remove unwanted metal halides and metal oxyhalides.

Reference to the boron nucleation layer that is substantially consumed in the version of the method for making the molybdenum film is that boron is not visible by SEM analysis of the sample cross section where at least one boron nucleation layer has been replaced by at least one molybdenum nucleation layer Can refer to. Substantially consumed may additionally or alternatively refer to less than 5 wt %, and in some cases less than 1 wt% boron, present in the molybdenum film and any lower molybdenum nucleation layer. The boron content can be determined by acid dissolution of the film from the substrate and by elemental analysis. Substantially consumed is also at room temperature (RT, 20° C.-23° C.) within ±20% of a molybdenum layer of similar thickness (±10%) vapor deposited on a similar substrate at 700° C. from MoCl ₅ It may refer to a molybdenum film having a measured resistivity.

Thermal budget refers to the cumulative thermal energy imparted to a semiconductor microelectronic transistor, logic gate, or photovoltaic cell by all thermal processing steps during manufacturing. Controlling the thermal budget of the process can help prevent dopant redistribution at the junction and diffusion of metal through the barrier layer. If high temperatures are required during manufacturing, moderate heat budgets can be achieved by limiting the duration of the process. Similarly, if the process requires a significant amount of time to complete, the temperature can be lowered to avoid excessive heat budget. In a version of the method, molybdenum nucleation layers and bulk molybdenum layers can be deposited at a temperature of less than 500° C. and with similar deposition times compared to a 700° C. molybdenum process without a Mo nucleation layer. The use of lower deposition temperatures in the novel methods disclosed herein can reduce the need for thermal budgets for processes in which molybdenum films are used in semiconductor device fabrication. Additionally, the lower process temperatures achieved by the process of the present invention can reduce costs by allowing the use of less expensive process equipment and designs.

In the version of the method for making a molybdenum film, the decomposition layer or nucleation layer comprising boron is substantially free of borides. Similarly, the molybdenum nucleation layer and the molybdenum film are substantially free of borides. Boride is a material that forms between boron and a more electronegative element such as silicon. A boride layer has been proposed as a barrier layer in the manufacture of integrated circuits for inhibiting diffusion of metals and other impurities into the underlying barrier layer. Borides are typically formed using chemical vapor deposition (CVD) techniques. For example, metal tetrachloride can be reacted with diborane using CVD to form metal diborides. However, when Cl-based chemicals are used to form the boride barrier layer, reliability problems can arise. In particular, boride layers formed using CVD chlorine-based chemicals typically have high chlorine content (eg, greater than about 3% chlorine content). High chlorine content is undesirable, which can cause chlorine to migrate from the boride barrier layer to adjacent interconnect layers, which can increase the contact resistance of such interconnect layers and potentially change the properties of integrated circuits made therefrom. Because it can. The molybdenum film prepared by the method disclosed herein has been found to protect the substrate from the etching effect of MoCl ₅ , MoOCl ₄ .

In the version of forming a molybdenum film over the substrate, the bulk molybdenum, molybdenum nucleation layer(s), and boron nucleation layers may be deposited by vapor deposition. Vapor deposition includes chemical vapor deposition (CVD), atomic layer deposition (ALD), high and low pressure versions thereof, and versions including their auxiliary versions, and those such as plasma enhanced CVD, laser assisted and microwave assisted. Includes minor versions of these, but not limited to.

In some versions of the present disclosure, there is a layer of material overlying the substrate. This layer may be, for example, but is not limited to, titanium nitride, molybdenum, or other material underneath the bulk molybdenum layer in a semiconductor device. For example, when a refractory elemental metal such as molybdenum is used in the polysilicon-metal gate electrode structure, a thin conductive diffusion barrier is placed between the polysilicon and elemental metal to prevent siliconization of the elemental metal during high temperature processing. Can be. The diffusion barrier is typically composed of conductive metal nitrides such as tungsten nitride (WN), titanium nitride (TiN), tantalum nitride (TaN) and/or respective silicon-containing ternary compounds such as WSiN, TiSiN, and TaSiN. .

In some versions, the substrate comprises a molybdenum nucleation layer, for example a molybdenum nucleation layer previously formed in accordance with the present invention.

Substrates that may be used in the version of the method include silicon, silicon oxide, gallium arsenide, alumina, and other ceramics and metals with suitable chemical and temperature properties.

The boron nucleation layer or boron decomposition layer can have a thickness ranging from about 5 angstroms (5 Å) to about 100 angstroms (100 Å). The molybdenum nucleation layer can have a thickness ranging from about 5 angstroms (5 Å) to about 100 angstroms (100 Å). The boron nucleation layer may be deposited on a substrate heated to a temperature of 250° C. to 550° C., or on a layer over the substrate. In some versions, the boron nucleation layer may be deposited on a substrate heated to a temperature of 300° C. to 450° C., or on a layer on top of the substrate. The boron nucleation layers produced between 300° C. and 450° C. provide smooth, low-resistivity bulk molybdenum layers. One or more B ₂ H ₆ nucleation layers may be deposited by exposing the substrate to a B ₂ H ₆ gas at a temperature range of 300° C. to 550° C. and a pressure range of 10 Torr to 60 Torr.

The bulk molybdenum vapor deposition from the molybdenum complex onto the upper nucleation layer can occur in the presence of a reducing gas such as hydrogen. For example, the molybdenum pentachloride MoCl ₅ complex can be transferred to the reaction chamber by sublimation from a vessel or ampoule having a flow of N ₂ or Ar carrier gas. The ampoule container containing molybdenum pentachloride as a complex can be heated to a temperature between 70° C. and 100° C., for example. The temperature for vaporization will depend on the molybdenum complex used. A lower ampoule temperature is beneficial for all vapor generation, as it can reduce the decomposition of the molybdenum complex, thereby providing a more consistent molybdenum deposition rate.

Example 1

This example illustrates the deposition of molybdenum on top of a 50 Å thick titanium nitride layer on a substrate. After deposition of the molybdenum nucleation layer and the bulk molybdenum, the thickness of the titanium nitride layer was within ±20% of the initially measured TiN layer thickness, which indicates that the molybdenum nucleation layer is a chlorine-containing precursor and by-product. It is exemplified that it provides etch resistance to TiN from below.

The molybdenum film on the substrate was deposited by a multi-step process at various temperatures and pressures as detailed in Table 1 below. The first step comprises a sub-step of depositing a solid boron nucleation layer on a titanium nitride layer on top of the SiO ₂ substrate; And a sub-step of exposing the solid boron nucleation layer (or boron decomposition layer) to a composition comprising MoCl ₅ and hydrogen to substantially replace the boron nucleation layer with a molybdenum nucleation layer.

The next step is the deposition of a new boron nucleation layer on top of the molybdenum nucleation layer with soaking shorter than the first boron layer nucleation, followed by substantially consuming the new boron nucleation to form molybdenum and then smoothly MoCl. _It was a bulk molybdenum deposition initiated by bulk deposition of molybdenum to form a molybdenum film on a substrate by reaction of ₅ and H ₂ .

The electrical resistivity of the membrane was measured at room temperature (RT, 20° C.-23° C.).

B ₂ H ₆ soaking MoCl ₅ /H ₂ After measurement Sample fair Stage temperature (℃) deposition
Time (seconds) Stage temperature (℃) pressure
chamber
(Torr) deposition
Time (seconds) Mo film thickness (Å) Resistivity @RT (4 points μΩ·cm) 9 Molybdenum nucleation layer 300 60 480 10 30 1.6 NA Bulk molybdenum layer 300 30 480 10 600 10 Molybdenum nucleation layer 300 60 480 40 30 683.8 12.9 Bulk molybdenum layer 300 30 480 40 600 11 Molybdenum nucleation layer 300 60 460 40 30 563.2 13.7 Bulk molybdenum layer 300 30 460 40 600 12 Molybdenum nucleation layer 300 60 450 40 30 297.6 16.9 Bulk molybdenum layer 300 30 450 40 600

As detailed in Table 1, the deposition temperature of the molybdenum nucleation layer was performed at a temperature of 480°C to 450°C, specifically 480°C, 460°C or 450°C. The pressure of the nucleation or bulk molybdenum deposition step was varied between 10 Torr and 40 Torr. MoCl ₅ ampoule temperature (Amp temperature °C) was 90 °C.

The results of this example show that at 10 Torr process pressure, little or no Mo deposition was obtained at 480°C. However, at 40 Torr process pressure, the Mo film deposition rate produced a film of about 300 Å or thicker, and the deposition rate decreased as the deposition temperature decreased. At 480° C. and 40 Torr pressure, the molybdenum deposition rate was about 65 Å/min; The molybdenum deposition rate at 460° C. and 40 Torr pressure was about 54 A/min; The molybdenum deposition rate at 460° C. and 40 Torr pressure was about 28 Å/min.

The results of this example also show a 4-point electrical resistivity measured at room temperature (RT, 20° C.-23° C.) between 12 μΩ·cm and 20 μΩ·cm for molybdenum membranes each having a thickness of 700 angstroms to 300 angstroms. It is shown that a molybdenum film comprising at least one molybdenum nucleation layer and a bulk molybdenum layer was prepared. All membranes exhibited a low resistivity of less than 20 μΩ·cm when measured at room temperature (RT, 20° C.-23° C.).

Example 2

This comparative example illustrates the deposition of molybdenum on a substrate without a molybdenum nucleation layer. Deposition was tested at a stage temperature of 550[deg.] C. to 700[deg.] C., and deposition times varied from 30 seconds to 600 seconds. Deposition of MoCl ₅ to form Mo was performed on a 100 Å TiN layer on a SiO ₂ substrate. The MoCl ₅ ampoule was heated to 70° C., the chamber pressure was 60 Torr, the H ₂ flow rate was 2000 sccm, and the argon carrier gas flow was 50 sccm.

The results in Table 2 show that CVD deposition of Mo films on TiN coated substrates was achieved using MoCl ₅ /H ₂ at stage temperatures above 550°C. At lower temperatures (eg stage temperatures below 550° C.), the deposition of Mo stopped due to the effect of etching the substrate from MoCl ₅ and inadequate nucleation.

Sample Stage (substrate) temperature (℃) Evaporation time (sec) Molybdenum film thickness (Å) Resistivity (4 points μΩ·cm) @RT 322-237-15 700 30 64.4 27.5 322-237-12 700 180 340.8 16.1 322-237-13 700 120 231.2 21.8 322-399-7 600 60 59.9 40.4 322-399-5 600 180 150.5 28.3 322-399-3 600 300 248.2 30.3 322-399-9 550 600 241.7 60.0 322-399-13 550 180 37.1 56.0

The results of this example show that at the same deposition time of approximately 180 seconds, the thickness of the deposited molybdenum film was from 341 Å (deposition rate of 1.89 Å/second) at 700° C. to 150 Å (deposition rate of 0.83 Å/second) at 600° C. It decreased, and it was as low as 37Å (deposition rate of 0.2Å/sec) at 550°C. For films of similar thickness prepared at different temperatures, the molybdenum film resistivity measured at room temperature (RT, 20° C.-23° C.) increased with decreasing deposition temperature. For example, a 241 Å thick Mo film deposited at 550° C. had a resistivity of 60 μΩ·cm; The 248Å-thick Mo film deposited at 600°C had a resistivity of 30.3µΩ·cm, and the 231Å-thick film deposited at 700°C had a resistivity of 21.8µΩ·cm.

Example 3

This example illustrates the steps of making a molybdenum film comprising at least one molybdenum nucleation layer and a bulk molybdenum layer deposited by vapor deposition from MoCl ₅ .

The resulting molybdenum membrane was prepared and characterized as detailed in Table 3. The substrate used had a 50Å titanium nitride layer over SiO ₂ . The formation of the solid boron nucleation layer on the TiN layer was carried out at a stage temperature of 300° C., a chamber pressure of 40 torr, a B ₂ H ₆ flow of 35 sccm and an argon flow of 250 sccm; The time varied from 60 to 30 seconds depending on whether the boron nucleation layer was formed on TiN or the initial molybdenum nucleation layer. The estimated thickness of the boron nucleation layer was 5 to 30 angstroms.

MoCl ₅ ampoule temperature was 90°C, chamber pressure was 20 Torr, argon carrier flow was 100 sccm, H ₂ was 2000 sccm, and stage temperature varied from 480°C to 500°C. The reaction time varied from 30 seconds to 600 seconds, depending on whether the molybdenum nucleation layer was formed by consuming the initial boron nucleation layer or the second molybdenum nucleation layer was subsequently formed by bulk Mo CVD.

B ₂ H ₆ soaking MoCl ₅ /H ₂ After measurement Sample fair Substrate temperature (℃ Time (seconds) Substrate temperature (℃ Time (seconds) Mo film thickness (Å) Resistivity (4 points, μΩ·cm)@RT A Molybdenum nucleation layer 300 60 500 30 638.9 14.3 Bulk molybdenum layer 300 30 500 600 B Molybdenum nucleation layer 300 60 480 30 385.5 19.1 Bulk molybdenum layer 300 30 480 600

These molybdenum films each had an electrical resistivity measured at room temperature ranging between 12 μΩ·cm and 25 μΩ·cm for a molybdenum layer having a thickness between 800 angstroms and 200 angstroms.

The results of this example also show that between 480° C. and 500° C. by consuming the boron nucleation layer through the reaction of a nucleation layer containing boron on a substrate and a vapor composition containing molecules containing molybdenum and chlorine atoms. It shows that low-resistivity molybdenum films can be produced at the substrate temperature. The resistivity of the bulk molybdenum film in this example was the room temperature of the bulk molybdenum layer of substantially similar thickness (±10%) deposited from the same molybdenum complex on a similar substrate at 700° C. without the molybdenum nucleation layer. It was ±20% of the resistivity measured at. For example, deposition of molybdenum on a similar substrate using the molybdenum complex of samples 322-237-12 in Example 2 gave a film with a resistivity of about 16.1 μΩ·cm for a film of 340 Å thickness.

Example 4

This example illustrates the detrimental effect of excess residual boron on the resistivity of a molybdenum film on which a boron nucleation layer is deposited and the cut-off temperature of molybdenum deposition using a boron nucleation layer.

Molybdenum thickness after deposition at substrate temperatures of 450°C, 500°C, and 550°C was measured after 1, 2, 3, 4, 5 cycles. After 5 nucleation cycles, the molybdenum film thickness at a deposition temperature of 450° C. was less than 25 Å. After 5 nucleation cycles, the molybdenum film thickness at 500° C. deposition temperature was about 275 Å. After 5 nucleation cycles, the molybdenum film thickness at 550° C. deposition temperature was about 410 Å. Based on these results, the cut-off temperature for the reaction between MoCl ₅ and boron was determined to be between 450°C and 500°C.

Molybdenum film resistivity measured at room temperature after deposition at substrate temperatures of 500° C. and 550° C. was measured after 1, 2, 3, 4, and 5 cycles. The resistivity after one nucleation cycle at 500° C. was too high to measure, and the resistivity of the molybdenum film after one nucleation cycle at 550° C. was about 310 μΩ·cm. The resistivity of the molybdenum film formed at 500°C after two nucleation cycles was about 250 μΩ·cm, and the resistivity of the molybdenum film after two nucleation cycles at 550°C was about 275 μΩ·cm. The resistivity of the molybdenum film formed at 500° C. after 5 nucleation cycles was about 250 μΩ·cm, and the resistivity of the molybdenum membrane after 5 nucleation cycles at 550° C. was about 340 μΩ·cm. The resistivity after two nucleation cycles in this example is much higher than a similar film made after two nucleation cycles in Example 1, for example, and is not bound by theory, and is believed to be due to the presence of boron in the film.

Example 5

This example illustrates the deposition of molybdenum on a substrate without a boron nucleation layer and a TiN layer. The substrate was heated to 700° C. on the stage of the reactor and treated with a composition comprising MoCl ₅ vapor and different amounts of hydrogen gas. The process conditions included an inert argon gas flow of 50 sccm, a chamber pressure of 60 Torr, and a low hydrogen flow rate of 2000 seem and a high hydrogen flow rate of 4000 seem.

The results of this example show that the measured electrical resistivity of four points of the molybdenum film deposited on the substrate without the nucleation layer was about 15 μΩ·cm to 23 μΩ·cm for the 200 Å thick molybdenum film deposited without the boron nucleation layer. Is in the range of about 10 μΩ·cm to 16 μΩ·cm for a 600-800 Å thick molybdenum film deposited without a boron nucleation layer. The resistivity of all membranes produced using higher hydrogen flow rates is lower than those produced at lower hydrogen flow rates, and for molybdenum membranes approximately 800 Å thick, the resistivity of membranes produced at higher hydrogen flow rates was produced at lower hydrogen flow rates. It was about 5 μΩ·cm lower than that of the sample. As the film thickness increased, the molybdenum film resistivity decreased.

While a variety of compositions and methods are described, it is to be understood that the invention is not limited to the particular molecules, compositions, designs, methodologies or protocols described, and that they may vary. In addition, it is to be understood that the terms used in the detailed description are only for describing specific versions or embodiments, and are not intended to limit the scope of the invention to be limited only by the appended claims.

It should be noted that, as used herein and in the appended claims, the singular forms “a”, “a”, and “the” also include the plural meanings unless the context clearly dictates otherwise. Thus, for example, a reference to a "nucleation layer" is a reference to one or more nucleation layers and equivalents thereof known to those skilled in the art. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. Methods and materials similar or equivalent to those described herein can be used in the practice or testing of embodiments of the present invention. All publications mentioned herein are incorporated by reference in their entirety. Nothing herein is to be construed as an admission that the present invention is not entitled to antedate such disclosure by virtue of prior invention. “Arbitrary” or “arbitrarily” means that an event or situation described subsequently may or may not occur, and that the detailed description includes when the event occurs and when the event does not occur. . All numerical values herein may be modified with the term "about" whether or not explicitly indicated. The term “about” generally refers to a range of numbers that a person skilled in the art will consider equivalent to the stated value (ie, having the same function or result). In some embodiments the term “about” refers to ±10% of the recited value, and in other embodiments the term “about” refers to ±2% of the recited value. Compositions and methods are described by the term "comprising" (interpreted in the sense of "including, but not limited to") various components or steps, and compositions and methods are also "consisting essentially of" of various components and steps. It can be made or “consisting of” and such terms are to be construed as defining a group of essentially closed or closed members.

While the present invention has been specified and described with respect to one or more implementations, equivalent changes and modifications will be made to those skilled in the art based on reading and understanding of this specification and the accompanying drawings. The present invention includes all such modifications and modifications, and is limited only by the scope of the following claims. Additionally, certain features or aspects of the invention may have been disclosed for only one of several implementations, and such features or aspects may be desirable and advantageous for any given or particular application. It can be combined with aspects. In addition, when the terms "comprising", "having", "having", "having" or variations thereof are used in the detailed description or claims, these terms are intended to be inclusive in a manner analogous to the term "comprising". Is intended. Also, the term "exemplary" is meant only to be illustrative and not best. Features, layers, and/or elements depicted herein are illustrated in specific dimensions and/or orientations relative to each other for simplicity and ease of understanding and that actual sizes and/or orientations may differ materially from those illustrated herein. It must also be understood.

Claims (20)

It is a method of manufacturing a molybdenum layer,
Reacting a nucleation layer comprising boron on a substrate with a vapor composition comprising molecules containing molybdenum and chlorine atoms, wherein the substrate is at a temperature between 450°C and 550°C; The reaction consumes at least a portion of the boron nucleation layer and forms a molybdenum nucleation layer over the substrate.
How to include. The method of claim 1, wherein the nucleation layer comprising boron has a thickness between about 5 Å and about 50 Å. The method of claim 1, wherein the nucleation layer comprising boron is substantially consumed by the reaction such that the molybdenum layer comprises less than 5 wt% boron, optionally less than 1 wt% boron by elemental analysis. Way. The method of claim 1, comprising depositing a nucleation layer comprising boron over the substrate, wherein the substrate is at a temperature between 300°C and 550°C. The method of claim 1,
Depositing a nucleation layer comprising additional boron over the molybdenum nucleation layer on the substrate, the substrate being at a temperature between 300° C. and 550° C.; And
Reacting a nucleation layer comprising additional boron with a vapor composition comprising molecules containing molybdenum and chlorine atoms, wherein the substrate is at a temperature between 450° C. and 550° C.; The reaction consumes at least a portion of the additional boron nucleation layer and forms an additional molybdenum nucleation layer.
How to further include. 6. The method of claim 5, wherein the thickness of the nucleation layer comprising additional boron is between about 5 Angstroms and about 50 Angstroms. The method of claim 5, wherein the deposition thickness of the nucleation layer comprising additional boron is less than the deposition thickness of the nucleation layer comprising boron on the substrate. The method of claim 5, comprising vapor deposition of a nucleation layer comprising boron over the substrate during a first period and vapor deposition of a nucleation layer comprising additional boron during a second period, and a second period. Is shorter than the first period. The method of claim 5, wherein the nucleation layer comprising additional boron is substantially consumed by the reaction, whereby the additional molybdenum layer is less than 5 wt% boron, optionally less than 1 wt% boron by elemental analysis. The method comprising a. 6. The method of claim 5, wherein the deposition and reaction steps are repeated to form a plurality of additional molybdenum nucleation layers. The method of claim 1, wherein the temperature of the substrate is between 450° C. and 480° C. during the reaction of the nucleation layer(s) comprising boron. The method of claim 1, wherein the vapor composition is at a pressure of 10 Torr to 60 Torr. The method of claim 1 wherein the vapor composition is substantially free of reducing gas. The method of claim 1, wherein the molybdenum nucleation layer, or additional molybdenum nucleation layer over the substrate constitutes the top molybdenum nucleation layer. 15. The method of claim 14 including depositing the molybdenum complex at a temperature between 450° C. and 550° C. to form a bulk molybdenum layer over the top molybdenum nucleation layer. 16. The method of claim 15, wherein the molybdenum complex comprises MoCl ₅ or MoOCl ₄ . The method of claim 15, wherein the thickness of the molybdenum film is at least 200 angstroms, and the resistivity of the bulk molybdenum layer is substantially similar deposited from the molybdenum complex on a 700° C. substrate without a molybdenum nucleation layer. A method of ±20% of the resistivity of a bulk molybdenum layer of ±20% thickness. The room temperature of claim 15, comprising the step of preparing a molybdenum film comprising a bulk molybdenum layer and at least one molybdenum nucleation layer, wherein the film is less than 20 μΩ·cm for a molybdenum film thickness of at least 200 angstroms. Method with the electrical resistivity measured in. The method of claim 1, wherein the substrate comprises one or more molybdenum nucleation layers. The method of claim 1 wherein the substrate comprises a semiconductor substrate.