KR20000007363A - Tantalum, film of which principal ingredient is tantalum, and manufacturing method thereof - Google Patents

Abstract

PURPOSE: A tantalum, a film of which principal ingredient is the tantalum, and a manufacturing method thereof are provided, which is suitable for a super large scale integrated circuit and chemically deposits a film including a tantalum on a substrate. CONSTITUTION: A manufacturing method comprises the steps of: inducing a substrate, a source precursor with a steam state, and one carrier gas in a deposit chamber; maintaining a temperature of the substrate in the deposit chamber as 70°C to 675°C during a sufficient time for depositing a film having a tantalum on the substrate, wherein the one carrier gas is selected from a group including hydrogen, helium, oxygen, fluoride, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide, nitrogen, ammonia, hydrazine, nitrous oxide, and steam.

Description

Tantalum and a film containing tantalum as a main component and a method of manufacturing the same

The development of computer integrated circuit chips (ICs) has been driven by the need to increase speed, performance and functionality. Successful implementation of this purpose has demanded an innovative change in chip design with the introduction of multi-stage interconnection design using three-dimensional (vertical) space in the chip to improve the performance of the device. This approach simultaneously minimizes the increase in length and chip size, or “space,” of the entire connection line. This multi-stage interconnect design is commonly referred to as a large scale integrated circuit (ULSI) and is expected to average up to seven layers of interconnect within the next decade.

Changes in chip layout design have been achieved by a continuous reduction in single device device size to accommodate more devices per needle, which has achieved significant improvements in chip functionality. In this regard, device devices are expected to shrink from nominally 0.5μm to less than 0.18μm by 2000. However, the tendency to reduce the size of the device faces serious performance issues in terms of increased RC delay, where R is the resistance in the interconnect structure and C is the capacitance.

Significant reduction in line resistance R can be achieved by replacing the currently used metal layout design consisting of a tungsten plug and a tungsten or aluminum interconnect with a fully integrated copper-based metal layout design. Copper exhibits lower resistivity (bulk resistivity = 1.68 μ-Ω-cm) than aluminum and tungsten, which can yield a 40% reduction in RC delay. It is also expected to exhibit improved electromigration and stress resistance, thus leading to higher certainty and improved performance.

However, a major problem in the realization of such structural stability, namely copper-based metallization placement designs, is to identify suitable diffusion barriers and advice promoters that provide the performance required in sub-micron device technology. Copper is known to be highly reactive and rapidly diffuse in silicon. Once inside the silicon, they form a deep trap level that destroys the device's performance. Titanium and titanium nitride technologies are currently used, but are not expected to deliver the required performance, and in order to maximize space utilization for practical conductors in a constantly decreasing device structure, the need for increasingly thinner liners is needed. Is given. In addition, it is known that the advice and promoters of copper against titanium nitride diffusion barriers of the prior art are questioned, especially if titanium nitride is exposed to air prior to the copper deposition step.

Tantalum-based compounds provide a potential solution to this problem. Tantalum and its binary and tertiary nitrides are known to be non-reactive with copper and are highly refractory materials that are stable at extremely high temperatures. The copper-tantalum contact is stable up to 550 ° C., and the movement of copper through tantalum is extremely slow at typical temperatures used in the manufacture of microelectronic devices. In addition, nitrides mainly tantalum have a much higher melting point than tantalum. Tantalum nitride has a high melting point, for example, TaN and Ta ₂ N have melting points of 2050 ° C and 3087 ° C, respectively. This property led to a successful demonstration of sputtered tantalum nitride, such as a good diffusion barrier to copper-based techniques, with proven copper-tantalum contact stability up to high temperatures such as 750 ° C.

More importantly, the need for thinner liners has led to the production of alloys that primarily make tantalum much inherently more desirable than titanium alloys. This may be because tantalum is an ion that is heavier than titanium, and therefore, an alloy that is primarily tantalum should provide the diffusion barrier performance required for ULSI structures at a significantly reduced liner thickness compared to titanium alloys. Improved performance at reduced liner thickness ensures to maximize the useful space available for aluminum or copper conductors in a continuously decreasing device structure.

In this respect, TaN _x Si _y ; Ternary tantalum alloys such as x is greater than 0 and less than or equal to 2 and y is greater than 0 and less than or equal to 3; are highly desirable in view of their unique structural properties. These compounds not only share the excellent diffusion barrier properties of their binary tantalum, but are also able to grow in amorphous form. The formation of an amorphous state can eliminate the presence of grain boundaries, thereby obstructing any dislocation metal, for example copper, or diffusion paths along those boundaries, resulting in a TaN _x Si _y phase ( Improve the barrier properties of the phase.

One important application of pure tantalum is its ability to getter oxygen. Therefore, it provides a stable ohmic contact when deposited directly on silicon and alloyed to form tantalum silicide, ie, TsSi _y (y is greater than 0 and possibly less than 3) phase. Traditionally, the formation of tantalum silicide phases involves the deposition of pure tantalum on silicon and single or multi-anneal at high temperatures (high temperature of 900 ° C.) to form silicide phases. However, since the size of the semiconductor device is smaller than ¼ micron, the consumption of silicon from the substrate during the silicification process becomes undesirably high and very problematic, resulting in contact reliability relationships, and possible current leakage and device performance problems. Certainly, silicon consumption from the base substrate is not needed, and a deposition process for the growth of tantalum silicide directly from the gas phase needs to be developed.

At present, tantalum and its binary and tertiary nitrides are grown by conventional sputtering techniques. This technique, unfortunately inherently, is incompatible with the step coverage in aggressive trench and via structures if their eyes are placed on metal deposition. Therefore, alternative process techniques are required to be able to grow films that are primarily tantalum for application in devices less than ¼ micron. In this respect, chemical vapor deposition (CVD) is one of the most promising technologies. CVD has inherent potential for insulating protection of aggressive via and hole structures in terms of its ability to use substrate surfaces as catalysts for deposition reactions. In addition, CVD has the proven ability to deposit pure, doped pro-processed materials at industrially viable growth rates over large substrate areas such as the standard 200mm wafer size currently used in the semiconductor industry. .

Various CVD devices have already been tested for the growth of tantalum and its nitrides. Inorganic CVD using tantalum pentachloride (TaCl ₅ ) in hydrogen, nitrogen and argon atmospheres resulted in the deposition of TaN and Ta ₂ N at temperatures in the range of 700-1000 ° C. tea. Takahashi, H. Ito, and S. Ozeki, J., Less-Common Met. See vol. 52,29 (1977). Certainly, the high process temperatures required prohibit the use of this deposition method in practical semiconductor devices. High temperatures are necessary to ensure complete dissociation of tantalum-chlorine bonds in TaCl ₅ and subsequent reaction with ammonia to produce the nitride phase. Obviously, this high process temperature prohibits the use of deposition methods mainly based on such CVD tantalum pentachloride in actual semiconductor devices. In addition, the inclusion of small amounts of chlorine (up to 5 at%) in the film, which is primarily tantalum, is very problematic, given significant erosion and reliability, given the resulting nitride phase and mobility of chlorine out of the surrounding layer. Will cause.

Approaches by organometallic CVD have been attempted to include the use of homoreptic dialkylamido tantalum composites and tributyldiethyl tantalum type sources. S. Sun, M. H. Chai, H. T. Chiu, H. Chuang, and S. Chai, Proceedings of the IEDM; S.S.Sun, M.H.Chai, S.C.D.C., and H.T.Ciu, Proceedings of the 12th International VLSI Multilevel Interconnection Conference (VMIC, Tampa, Florida, 1995) p.157; And R. fix, R. G. See Gordon and D. M. Hoffmann, Chem. Mater. Vol. 5,614 (1993) and the like. However, deposition methods based on organometallic CVD have not achieved much success for reasons of diversity. In the case of tantalum, the organometallic CVD method could not produce pure tantalum free of carbon and oxygen contaminants. In the case of nitride, the low vapor pressure of the source used in some cases made the product of the resulting organometallic CVD process worthless, while the relative instability and short shelf life of the precursor used in some other cases Has made difficulties in transportation, treatment and storage.

However, none of these approaches have led to verification of organometallic CVD processes suitable for fabricating tantalum and its various nitrides and alloys in ULSI computer device structures.

Therefore, there is a serious need in the art for a method for providing a tantalum and tantalum-based film, which is preferably suitable for the manufacture of ultra-large scale integrated circuits. One requirement in the technical world has been in terms of purity, primarily in tantalum films with an impurity concentration of 1 at% or less, particularly those of very high quality electrical grades, which suitably represent a non-circular structure to perform the barrier layer. It is suitable for complex topography of ULSI circuits.

Another need in the art is to provide a way to easily prepare a single film comprising pure tantalum, a film mainly consisting of tantalum such as tantalum nitride, or a bilayer or a film comprising a suitable size of tantalum and its various alloys. Is in. There is also a need for a method that can maintain process temperatures of about 675 ° C. or less, preferably about 500 ° C. or less, to prevent thermally induced damage to the device during processing.

In addition, there has been a need to continue to allow the preparation of the above-mentioned films in situ without the need to expose the substrate coated with a tantalum-based film to air during transport to another reaction chamber to deposit another film. . According to the prior art method, the production of a bilayer or multilayer structure typically forms the first layer in the first reaction chamber and then the next layers are deposited over the already made layer, typically by exposing the substrate to air. Moving the substrate to another reaction chamber. Prior art processes do not provide a single reaction chamber with flexibility for depositing tantalum and its nitrides by simply adjusting the operating parameters of the reaction chamber. The prior art also does not supply deposition of tantalum and / or nitride thereof in two or more reaction chambers connected by a vacuum loadlock or a central conveying mechanism that allows the sample to move between the empty reactors without exposure to air. .

In particular, a process in which the deposition of a continuous double layer or multiple layers of tantalum or its nitride is possible in place is preferred, in part due to the high affinity of tantalum for oxygen and water. This affinity will lead to contamination of the surface of the film, which typically consists of tantalum, during the transfer to the second reaction chamber coated in the next layer by exposing the layer to air.

1 shows an x-ray diffraction pattern of a tantalum film produced by plasma CVD reaction of TaBr ₅ and hydrogen in Example 1 according to the practice of the method of the present invention.

2 shows the x-ray photoelectron spectrum of the tantalum film of Example 1. FIG.

3 shows Auger electron spectra of the tantalum film of Example 1. FIG.

4 shows Rutherford backscattering spectra of the tantalum film of Example 1. FIG.

5 is a cross-sectional scanning magnified with an electron microscope in view of a silicon substrate having an oxygen via pattern having a diameter of 0.25 mu m and an aspect ratio of 4 to 1, and on which the insulating protective tantalum film of Example 1 is deposited.

6 shows an x-ray diffraction pattern of a TaN _x film prepared by thermal CVD reaction of TaBr ₅ and ammonia in Example 2 according to one embodiment of the present invention.

7a and 7b show the x-ray photoelectron spectrum of the film of Example 2. FIG.

8 shows the Auger electron spectrum of Example 2. FIG.

9 shows the Rutherford backscattering spectrum of the film of Example 2. FIG.

10 is a cross-sectional scanning magnified with an electron microscope in consideration of a silicon substrate on which an oxygen via pattern having a diameter of 0.25 mu m and an aspect ratio of 4 to 1 is formed and the insulating protective film of Example 2 is deposited.

FIG. 11 mainly shows tantalum grown in situ, including a tantalum layer produced by a plasma-enhanced CVD reaction of TaBr ₅ and hydrogen, coated with a TaN _x layer deposited by a thermal CVD reaction of TaBr ₅ and ammonia. Auger electron spectrum of the bilayer film is shown.

The present invention includes a method for chemical vapor deposition of a film comprising tantalum on a substrate. The method includes (1) a substrate; (2) a source precursor having a vapor state and having the following formula (I); And (3) introducing at least one carrier gas into the deposition chamber.

(Ⅰ)

Wherein m is an integer from 0 to 5, n is an integer from 0 to 4, p is an integer from 0 to 4, and R is selected from the group consisting of hydrogen and lower alkyl. The temperature of the substrate in the deposition chamber is maintained from about 70 ° C. to about 675 ° C. for a sufficient period of time to deposit a tantalum containing film on the substrate.

In an embodiment, the method includes depositing a second film containing tantalum in the film deposited on the substrate to form a multilayer structure while the substrate is fixed in the deposition chamber. The second film containing tantalum is a pure tantalum film, where Ta is a TaN _x film that is greater than 0 and less than or equal to about 2, y is a TaSi _y film that is greater than 0 and less than or equal to about 3, x is greater than 0 and less than about 2 Or equal to and y is selected from the group consisting of TaN _x Si _y films greater than 0 and less than or equal to about 3.

In yet another embodiment, the method further comprises using a silicon substrate and heating the substrate, wherein the deposition film contains tantalum from a temperature of about 700 ° C. to about 950 ° C. to supply silicon to the deposition film containing tantalum.

(Example)

The configuration of the present invention described above, like the detailed description of the preferred embodiment of the present invention, is much easier to understand when read in connection with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS For the purpose of illustrating the invention, presently preferred embodiments are shown in the drawings. However, the invention is not limited to the specific apparatus and equipment shown.

Insulation protection tantalum and TaN_xtantalum nitride, including (preferably x has any value in the range greater than 0 and less than or equal to 2) With alloy, TaSi_yand tantalum silicide alloy comprising TaN, preferably having a value in the range of greater than 0 and less than or equal to 3_xSi_y(x and y are preferably as defined above) to a chemical precursor and associated thermal plasma method which primarily consists of halides for chemical vapor deposition of tantalum nitride alloys comprising a variety of specific substrates. In the present invention, a plurality of layers thereof and films deposited on a substrate forming a metal coating layer or a multilayered structure in the form of a single film mainly composed of tantalum on the substrate are deposited.

Such films are useful for semiconductor substrates such as silicon and gallium arsenide substrates having sub-micron features and structures. Single or multi-layered films can be deposited in different reactors, or in situ single reactors, or combinations thereof. For example, several layers can be deposited in a single reactor and the next layer can be deposited in a separate reactor. When more than one reactor is used, the reactors are preferably connected via a closed lock arm and a locklock which allows the transport of samples between different reactors without exposing the substrate coated with air.

In microelectronics, preferred substrates tend to be integrated circuits and tend to have composite photography formed with holes, trenches, and the like to provide the necessary connections between the various electrically conductive materials forming the semiconductor device. . The substrate is preferably formed of, for example, silicon, silicon dioxide, or a doped version and mixtures thereof.

The substrate of the invention is more preferably aimed at ULSI circuits and is patterned with holes, trenches, and other elements having a diameter of 1.0 micron or less, often 0.50 micron or even 0.25 micron. Substrates with such small devices are known as "sub-micron" substrates. Sub-micron substrates that can be coated in accordance with the present invention also typically have high aspect ratio elements of about 3: 1 to about 6: 1 and more, where the aspect ratio is viewed in cross section. , As the ratio of the depth of the device to its diameter. As used herein, substrates less than ¼ micron have a device diameter of less than about 0.25 microns, and the aspect ratio of the devices is typically greater than about 3: 1. Devices with aspect ratios of about 4: 1 and above are found in most substrates for ULSI circuits.

Examples of substrates that can be coated include semiconductor substrates as mentioned above, or metals, glass, plastics, or other polymers, and applications include, for example, aircraft components and engines, automotive components and engines and cutting tools. Solid protective clothing of dragons; Decorative coatings for jewelry; Barrier layers for flat panel display, advice promoters, and solar cell devices. Preferred metal substrates are aluminum, beryllium, cadmium, cerium, chromium, cobalt, copper, gallium, gold, iron, lead, manganese, molybdenum, nickel, palladium, platinum, rhenium, rhodium, silver, stainless steel, steel, iron, strontium Tin, titanium, tungsten, zinc, zirconium, and alloys thereof and compounds such as silicides and carbides.

The type of substrate that can be used in the present invention is not limited. However, the substrate is preferably stable under the conditions used for depositing a film or films on the substrate. That is, the substrate is preferably stable at temperatures from about 70 ° C. to about 950 ° C., preferably from about 70 ° C. to about 700 ° C., depending on the manner of the deposited film and the intended use of the coated substrate.

Depending on the CVD process used in the method of the present invention, the conformal single, bilayer or other multilayer film can be placed on a ¼ micron substrate. Conformal coatings of tantalum, tantalum nitride, tantalum silicide, and tantalum nitride may be placed on ¼ micron substrates with device diameters of about 0.25 microns or smaller and aspect ratios of about 6: 1 or greater.

As used herein, “insulation protective coating” refers to a coating that evenly covers a substrate having composite topography. Uniformity of the coating can be measured, for example, by testing the thickness of the coating along the wall and the bottom of the hole in the substrate, and by determining the change in the thickness of the coating. According to the invention, the quarter-micron substrate is insulated protectively coated, and when the coating has a thickness, it is measured at some point perpendicular to the bottom of the hole at the surface of the wall or at the surface of the substrate, which is at any other point The thickness at is within 25%. According to a preferred embodiment, the change in coating thickness is within 10%. That is, at no point is the thickness of the coating 10% greater or 10% less than the average thickness of the coating.

As used herein, particularly when referring to ULSI devices and coated substrates useful therein, “step coverage” refers to devices such as trenches or vias for the thickness of the coating at the surface apex of the substrate proximate the device. It is the ratio of the coating thickness at the bottom of, which is provided as a% value and increases to 100. The process of the present invention provides an insulating protective coating of a ¼ micron substrate having a step coverage of greater than about 70% on a ¼ micron substrate.

The present invention employs a composite that primarily consists of halides for the low temperature production of tantalum and its nitrides and / or alloys thereof, depending on the reactants employed. In situ, a continuous CVD process using a single halide precursor can be used for gentle and reversible changes between tantalum and its nitride and / or silicide alloys by appropriately modifying process conditions. It also provides a CVD process that can use other halide precursors to successively deposit various layers of pure tantalum or tantalum as needed for a particular application.

The present invention includes a method for CVD of tantalum, ie a film comprising pure tantalum or tantalum-based films on a substrate. The method includes introducing a substrate, a source precursor and at least one carrier gas into the deposition chamber, which can function as a carrier and / or a reactant. However, for convenience, such gas will generally be referred to herein as at least one "carrier gas". The source precursor is introduced in the vapor state and preferably has the following formula:

(I)

Where m is an integer from 0 to 5, n is an integer from 0 to 4, p is an integer from 0 to 4, and R is hydrogen and lower alkyl, for example, preferably methyl or neo Pentyl.

According to a preferred embodiment, the source precursor of formula (I) is TaBr ₅ or (CH ₃ ) ₃ TaBr ₂ and the substrate is a silicon dioxide wafer useful for the manufacture of silicon or ULSI devices. The arrangement of bonds between different halides that can be used as source precursors and the related electronic environment in tantalum pentabromide and tantalum tentidide are very different from tantalum pentabromide as used in the prior art. The use of such precursors of the present invention generates corresponding dissociation energy significantly lower than tantalum pentabromide, and thus has the ability to deposit tantalum-base films at process temperatures significantly lower than those required for tantalum pentabromide.

Additionally, if the activation energy is given much heavier than Cl, for example I or Br, the iodine or bromine diffusion is expected to be significantly higher than chlorine, and M. sil and P. Bags, Phys. Rev. .B28,2023 (1983), which includes the study of the interaction of fluorine and chlorine with Si (111), shows that the barrier to chlorine penetrating into the silicon surface is much greater than that of fluorine. This behavior is the result of the larger size of the chlorine atoms, and thus the ionic and consequent Coulomb interactions, compared to the fluorine atoms. This property has important implications for the effect of residual halides bound in tantalum-based films, and certain concentrations of iodine or bromine require somewhat higher thermal energy to diffuse from the film lattice than chlorine.

At least one carrier gas is preferably hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, nitrogen, ammonia, hydrazine, nitrous oxide, and / or wafer vapor. The gas may vary depending on the type of film formed. For example, for pure tantalum films, the gas is preferably hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide, and water vapor. Most preferably, to form a pure tantalum film, at least one gas is hydrogen, helium, xenon, and / or argon, more preferably the gas is hydrogen or hydrogen combined with argon or xenon.

The source precursor, the at least one carrier gas and the substrate are maintained in the reaction chamber at an internal reaction temperature of about 70 ° C. to about 675 ° C., preferably at least 100 ° C. Most preferably, a plasma having a plasma power density of about 0.01 to about 10 W / cm ² is supplied to the chamber. Preferably the plasma has a frequency of about 0 Hz to 10 ⁸ Hz. The components remain under these conditions for a time period sufficient to deposit pure tantalum or a tantalum based film on the substrate. The deposition step typically takes from about 30 seconds to about 30 minutes, depending on the type of film, process conditions, and the desired film thickness, primarily for the tantalum to be deposited.

According to another embodiment of the method, a tantalum nitride alloy film is deposited by CVD on a substrate. A tantalum nitride alloy, such as TaN _x (where x is any value greater than 0 and less than or equal to about 2), has a substrate, a source precursor of formula (I) above, and at least one carrier gas as listed above. Most preferably, for example, by introducing a gas comprising nitrogen, such as nitrogen, ammonia or hydrazine, and also a nitrogen-containing reaction gas, which may be the same as or different from at least one carrier gas. The nitrogen-containing reaction gas is preferably selected from the group consisting of nitrous oxide, ammonia, nitrogen, and hydrazine. Preferably, the at least one carrier gas and the nitrogen containing reaction gas are used in combination with hydrogen, nitrogen, argon, ammonia and / or hydrazine. These components are maintained in the deposition chamber at a temperature of about 70 ° C to about 675 ° C. Most preferably, in order to form the tantalum nitride alloy, the temperature in the deposition chamber is from about 250 ° C to about 500 ° C. The substrate is held in the deposition chamber for a time sufficient to deposit the tantalum nitride alloy. In order to form tantalum nitride alloys, the compound of formula (I) is preferably TaBr ₅ or (CH ₃ ) ₃ TaBr ₂ together with a substrate which is a silicon or silicon dioxide wafer useful for the manufacture of ULSI devices.

Tantalum nitride alloys are most preferably neutralized using at least one carrier gas using one or more of the following: hydrogen; Hydrogen bonded with nitrogen, ammonia, argon, xenon, and / or hydrazine; Nitrogen bound with ammonia, argon, and / or xenon; Or ammonia combined with argon and / or xenon.

Preferably, each component is held in the deposition chamber in the presence of a plasma having a plasma power density of about 0 to 10 W / cm ² , more preferably tantalum-based film, ie, tantalum nitride in the substrate. From about 0.01 to about 10 W / cm ² for a period of sufficient time to deposit the alloy. According to this embodiment, the source precursor is most preferably TaBr ₅ and in combination with at least one carrier and / or reaction gas and an additional nitrogen-containing reaction gas which is nitrogen, ammonia, and / or hydrazine, ULSI Deposited on a silicon or silicon dioxide wafer substrate for use in the manufacture of the device.

Alternating or continuous deposited multilayers of pure tantalum and / or tantalum nitride alloys may preferably be provided on the substrate while the substrate is held in a single deposition reactor. The substrate and source precursor are supplied to the deposition chamber and the source precursor is in vapor phase. Preferred gases are supplied to form alternating or continuous film layers in the preferred deposition chamber as described above. Tantalum metal films or tantalum nitride films are first deposited on a substrate and these layers can be altered or applied in any given order or order.

Alternatively, such alternating or continuous multilayers of pure tantalum or tantalum nitride alloys can be deposited on the substrate while the substrate is moving in a single deposition reactor. In addition, multiple layers may be provided on the substrate while the substrate is moving between two or more separate reactors, and may be used respectively for the deposition of one or more layers of tantalum or tantalum nitride alloys, depending on the particular application of the coated substrate. Can be. Pure tantalum or tantalum nitride films may be deposited first on the substrate. The substrate moves in one reactor where one or more layers are deposited and in another reactor additional layers are deposited. Preferably, the reactors are connected via sealed carrier arms and / or loadlocks that allow the sample to move between different reactors without exposing the substrate coated with air.

According to a further preferred embodiment, a pure tantalum or tantalum nitride alloy film is deposited on the substrate to provide a coated substrate, followed by a series of tantalum based films such as pure tantalum or tantalum nitride, preferably the next layer. Nitrogen concentration in is increased and deposited on the coated substrate. Tantalum or tantalum nitride alloy films are formed as described above.

The present invention uses a CVD process to produce pure (electronic grade) tantalum or tantalum nitride alloy films, for example for use as an integrated inner layer or diffusion barrier in integrated circuit fabrication, and particularly in ULSI fabrication. use. The process of the present invention refers to precursors that have been carefully selected for heat or plasma-promoted CVD reactors to achieve a high quality tantalum-based film under desirable conditions.

In addition to the tantalum nitride alloy film described above, the tantalum nitride alloy film and tantalum nitride alloy film may also be similarly drawn according to the present invention as described in more detail below. Such films may also be formed in a multilayer laminate structure, for example, bilayer films of tantalum and tantalum nitride, bilayer films of tantalum and tantalum nitride, and multilayer films of tantalum and tantalum nitride in an optional or continuous arrangement. to be.

In order to prepare tantalum and tantalum-based films according to the invention, thermal CVD or plasma-promoted CVD can be used. The term "thermal CVD" refers herein to a CVD process in which all reactants are introduced into the CVD reactor in gaseous form, and the energy required for bond breakdown is supplied entirely by thermal energy. "Plasma-promoted CVD" means here a CVD process in which all reactants are introduced into the CVD reactor in gaseous form and the energy required for bond cleavage is incandescent discharge or from about 0 to about 100 W / cm ² , preferably Partially supplied by the high energy electrons formed in the plasma having a plasma power density from about 0.01 to about 10 W / cm ² , more preferably from 0.5 W / cm ² . Plasma-promoted CVD has the advantage of high energy electrons present in incandescent discharges, as is the case for plasma-enhanced CVD, which is generally well known in the art to assist in dissociation of gas molecules. However, in contrast to plasma-enhanced CVD, it uses a high plasma power density, and the low plasma power density used in plasma-promoted CVD does not cause hasty precursor decomposition in the gaseous state, so it is an undesirable film. Prevent contamination In addition, the use of low plasma power densities prevents electrical losses to the film and the substrate.

CVD reactors having the following basic components may be used with the method of the present invention: precursor transport systems, vacuum chambers, used to maintain source precursors and to control their conveyance, to maintain adequately reduced pressure. Pumping systems, power supplies for generating plasma discharges for plasma-promoted CVD, temperature control systems, gas or vapor treatment to control and meter the flow of reactants and products from the process. Precursor conveying system can be any of the following: a pressure-based bubbler or sublimer, a hot source massflow controller, a liquid conveying system, a direct liquid injection system or a similar device.

In the deposition of tantalum-based films according to the invention, the source precursor can preferably be heated by bonding in the form of resistive heat and the power supply will be associated to a temperature which is very sufficient to ensure sublimation or vaporization of the precursor. It is placed in a reservoir, but not high enough to cause hasty decomposition of the precursor. The mass flow regulator can be separated from the reservoir by a high vacuum valve, and is preferably supplied to assist the regulating gas flow in the reservoir. Gases such as hydrogen, helium, argon, xenon, and nitrogen may function as transfer agents when conventional pressure and / or temperature-based mass flow controlled transport systems are used as transport systems for precursors in CVD reactor chambers. . Optionally, such gas may function as a high pressure agent when using a liquid transport system for transport of the precursor to the CVD reactor. Such a system may include a combination of a micropump and a vapor head. A suitable example of such a sieve is an MKS direct liquid injection system. Another example of a suitable transport system for a source precursor is a hot source massflow controller, for example MKS Model 1150 MFC, which does not require the use of a carrier or high pressure gas. Another example of a solid source transport system is, for example, an MKS 1153 system, which does not require the use of a carrier or high pressure gas.

In a preferred embodiment, the precursor vapor (or carrier gas depending on the precursor and the transport system used) is transported into the CVD reactor via a transport line, preferably maintained at the same temperature as the reservoir, to prevent precursor liquefaction. For this purpose, a power supply associated with a resistive array is used. The CVD reactor preferably has a plasma generating capacity. The plasma can be generated by several sources such as direct current plasma, radio frequency plasma, low frequency plasma, high density plasma, electron cyclone plasma, inductively coupled plasma, microwave plasma or other similar sources. Plasma can be used for dual purposes. It can be used for actual deposition if using pre-deposition substrate cleaning, and plasma-promoted CVD in situ.

Preferably the reactor may be equipped with an electrical bias on the substrate. The bias is derived from self-producing waves below 500 kHz, high frequencies between 500 kHz and 10 ⁶ kHz or from 10 ⁶ to 10 ⁸ direct current or similar power sources.

Decompression of the CVD deposition reactor is possible using various pumping systems. Two systems are preferred. One system is a high vacuum (10 ^-6 torr or higher) pumping system that can use cryogenic or turbomolecular pumps. This system ensures a high vacuum basic pressure in the reactor. Vacuum systems with roots blowers or dry pumps can be used to handle high gas throughput in CVD. Both pumping units are preferably isolated from the CVD reactor by high vacuum gate valves.

The CVD reactor may be preferably equipped with a high vacuum load lock used to transport and load substrates of about 300 mm in size into the reactor. Optionally, the reactor may be connected to a vacuum central handler unit that may be used to transport substrates between multiple CVD reactors to deposit a continuous or alternating layer of tantalum and / or tantalum based film.

After being filled in the reservoir, the source precursor is heated to a temperature high enough to ensure sublimation or vaporization of the precursor, but not so rapid decomposition occurs. Preferably the source precursor is heated to a temperature of about 50 ° C to about 200 ° C. When conventional massflow controlled or solid-sourced conveying systems are used to control the flow rate of the precursors into the CVD reactor, the pressurer in the reservoir is heated. Optionally, when a liquid conveying system, for example an MKS direct liquid spraying system consisting of a combination of a micropump and a vaporizer head, is used, the liquid in the reservoir is at room temperature. In such a liquid conveying system, not the liquid in the reservoir, the vaporizer head is heated to a temperature high enough to ensure sublimation or vaporization of the precursor, but not so rapid decomposition occurs.

When a gas is used, it reacts with or reacts with the source precursor to form intermediates that can be more easily returned to the reaction zone or more easily decomposed to produce a film based on the desired tartalum or tantalum. Gaseous substances that do not react with may be used. Exemplary carrier gases are listed above. Hydrogen is particularly preferred as a carrier gas for thermal CVD and plasma promoter CVD. The flow rate of the carrier gas may vary between about 10 standard cm ³ / min and about 5 standard l / min, preferably 10 to 100 cm ³ for both thermal CVD and plasma promoter CVD. In all the forms of conveyance described above, the vapor flow rate of the source precursor is between about 0.01 and about 2000 standard cm ³ / min. Preferably, the flow rate of the precursor into the CVD room is about 0.1 to 100 standard cm ³ / min.

The carrier gas, which also functions as a reaction gas, is preferably hydrogen with respect to thermal CVD and plasma of the pure tantalum film. Mixing with ammonia or hydrazine, single or hydrogen, is a particularly preferred carrier / reaction gas for thermal CVD or plasma promoter CVD of tantalum nitride or other tantalum based films. The flow rate of the carrier and / or reaction gas as a single gas or mixed gas is preferably about 10 standard cm ³ / min to about 10 standard l / min, more preferably about 100 standard cm ³ / min to about 5 standard l / min. The pressure of the corresponding reactor is preferably from 10 mtorr to 1000 mtorr for atmospheric CVD for low pressures, more preferably from 100 mtorr to 15 tor.

Although for the sake of convenience, the gases disclosed herein are referred to as "carrier" gases or "responsive" gases, but these gases should not be mistaken for their function. In practice, in addition to transferring the vapor of the source precursor into the reaction chamber, the carrier gas may undergo a reaction in the reaction chamber through a decomposition process. In addition, the so-called "reaction" gas introduced may comprise an inert element, in which case some or all of the reaction gas may simply function to dilute the reaction atmosphere inside the cracking chamber. Likewise, the carrier casing may comprise an inert element.

According to a preferred embodiment of the plasma promoter CVD for forming a tantalum film, hydrogen is a carrier gas and no reaction gas, because hydrogen plasma functions as a catalyst to decompose the precursor on the substrate. According to another preferred embodiment of the plasma promoter CVD for forming a tantalum film, hydrogen is introduced into the decomposition chamber simultaneously with an inert gas such as neon, argon, krypton and / or xenon as at least one carrier gas. Preferably, hydrogen is introduced to function as a reactant and at least one of arcon and xenon is introduced to function as a carrier. However, the inert gas can be introduced in admixture with hydrogen and the gas mixture which can be introduced as at least one carrier gas can function as a carrier and a reactant.

Pure tantalum films can be prepared using thermal CVD according to the present invention. To prepare a pure tantalum film by thermal CVD, hydrogen, argon and / or xenon may be introduced, for example, as at least one carrier gas to function as a reactant in the deposition chamber. According to a preferred embodiment, argon functions as a carrier and hydrogen functions as a reactant in at least one carrier gas.

Plasma promoter CVD according to the present invention is used to produce a film based on tantalum, such as tantalum nitride alloy. In one preferred embodiment for the production of tantalum nitride films in the form of TaN by plasma promoter CVD, a reaction gas comprising nitrogen has to be introduced into the reaction chamber. Nitrogen, ammonia and hydrazine are preferred as reaction gases comprising nitrogen according to the invention. If the nitrogen is a reaction gas containing nitrogen, it may function as a carrier and a reaction gas containing nitrogen, and an inert gas such as hydrogen or argon or xenon may be simultaneously introduced as at least one carrier, and the carrier and / Or as a reactant. Preferably, one of hydrogen, nitrogen and active gas functions as at least one carrier gas. Hydrogen, nitrogen and / or inert gas may be introduced together as a complex reaction gas, ie hydrogen and / or inert gas may be mixed with ammonia or hydrazine gas. Nitrogen mixed with at least one of ammonia and hydrazine may be the only gas present in the deposition chamber at the time of production of the tantalum nitride film, in which case at least one carrier gas together with these three gases as a reaction gas containing nitrogen Can function as According to one preferred embodiment for producing TaN by plasma promoter CVD, hydrogen and nitrogen are introduced into the reaction chamber simultaneously with the source precursor.

Tantalum-based films can be produced using thermal CVD according to the present invention. In order to prepare a film mainly composed of tantalum such as a tantalum nitride film by thermal CVD, for example, ammonia, nitrogen and / or hydrazine may be introduced into the deposition chamber as a reaction gas containing nitrogen, and hydrogen, nitrogen Or at least one carrier gas in an inert gas such as argon or xenon may serve as a carrier and / or a reactant. According to a preferred embodiment, hydrogen functions as a carrier and ammonia functions as a reaction gas containing nitrogen.

When ammonia or hydrazine is a gas containing nitrogen during plasma promoter CVD of a tantalum nitride film, it is preferably introduced into the deposition chamber as a reaction gas, and an inert gas such as hydrogen and / or argon or xenon preferably functions as a carrier. Hydrogen and / or inert gas may be introduced together, for example as a reaction gas mixed with ammonia and / or hydrazine gas.

Regardless of whether thermal CVD or plasma promoter CVD is used to produce the tantalum nitride film, and also regardless of the exact identity of the reaction gas containing nitrogen and at least one carrier gas that can function as a carrier and / or reaction gas. If stoichiometric TaN is desired, it is important to maintain at least one mole of nitrogen atoms in the reaction chamber per mole of tantalum in the reaction chamber. If there are substoichiometric amounts of nitrogen in the deposition chamber, _a tantalum metal or tantalum rich film such as Ta ₂ N or TaN _a , where a <1, is deposited. This may allow the formation of a mixed phase film, ie a film with pure tantalum and tantalum rich nitride phases. As long as the mixed phase film is preferred for certain applications and the methodology for preparing such tantalum based films and substrates coated with such films is within the scope of the present invention, a pure TaN film must be deposited for a particular use. If so, that is, a film having a molar ratio of Ta: N of 1: 1, an appropriate supply of nitrogen atoms should be provided into the deposition chamber.

Additionally, irrespective of whether thermal CVD or plasma promoter CVD is used to produce the tantalum nitride film, at least one carrier that can also function as a carrier and / or reactant and the exact identity of the reactant gas containing nitrogen Irrespective of the gas, if a membrane containing nitrogen-rich tantalum as the main component is required, it is important to have an excess of nitrogen atoms, i.e., at least one mole of nitrogen atoms in the reaction chamber relative to one mole of tantalum in the reaction chamber. . If excess nitrogen is present in the reaction chamber, TaN with Z> 1_Z Nitrogen-rich films, such as, are deposited. This may allow the formation of a mixed phase membrane, ie a membrane having phases of pure tantalum, tantalum rich nitride and nitrogen rich nitride.

In one embodiment of the method, when forming a pure tantalum or tantalum nitride alloy film, preferably using thermal CVD or plasma promoter CVD, any one of the carriers and / or reaction gases described above is used. In the reaction chamber, a silicon-containing compound, preferably in a vapor state, is provided. The additional silicon preferably provides a tantalum silicide phase which is TaSi _y , wherein y is a value of 0-3, or a tantalum nitride phase, preferably TaN _x , where x is 0-2 and y is 0-3 Si _y is provided.

Compounds containing silicones are compounds based on halides of formula (II):

(Ⅱ)

Here, m is an integer of 0 to 4, n is an integer of 0 to 4, p is an integer of 0 to 4, R is defined in the same manner as in formula (I) described above.

The plasma used in the plasma promoter CVD can be generated by any of the plasma sources described above. The plasma frequency may range from 0 Hz to about 10 ⁸ kHz or more, preferably from 1 MHz to about 10 ⁶ kHz. The plasma power density is preferably 0.01 to 10 W / cm ² , more preferably 0.01 to 0.5 W / cm ² .

Electrical biases as described above may be applied to the substrate. The corresponding power density is preferably 0.001 W / cm ² to 10 ³ W / cm ² , more preferably 0.001 W / cm ² to 10 W / cm ² .

An alternative method of providing a tantalum or tantalum nitride alloy film according to the present invention in silicon is to use a substrate containing silicon as the main component or polyvalent silicon as the main component. After the tantalum or tantalum nitride film is formed, the temperature of the substrate in the reactor is typically raised to a temperature sufficient to react the silicon with the tantalum or tantalum nitride phase in the film, preferably 700 ° C to 950 ° C, so that the silicon of the substrate Is reacted with tantalum in the film formed on the substrate to provide a tantalum silicide or tantalum nitride nitride phase. The type and amount of silicified phase provided in the membrane depends on the treatment temperature and the type of reactant and / or carrier gas used as described above. In these cases, the silicidated phase can be prepared without using a compound composed mainly of vaporized silicon, such as a compound composed mainly of halides of the general formula (II).

Tantalum and tantalum-based films formed according to the present invention can be made in a column or non-column structure. Tantalum and tantalum based films of the present invention also have excellent ohmic contact properties when in the form of ULSI circuits. In addition, tantalum and tantalum-based films serve as excellent barrier properties and good barriers to metal diffusion when in the form of ULSI circuits.

Tantalum-based films prepared by thermal CVD or prepared by plasma promoter CVD typically have a tantalum to nitrogen ratio of 0 to 2 and a tantalum to silicon ratio of 0 to 3.

The present invention allows for the separation and independent production of pure tantalum and tantalum-based membranes, and the method of the present invention is also performed in the field between pure tantalum and tantalum nitride membranes by changing the reaction gas which can function as a carrier gas. The deposition mode of smooth and reversible conversion of a single tantalum precursor in is achieved.

Thus, according to one preferred embodiment of the method of the present invention, the deposition reactor is prepared from the compound of formula (I) in the presence of hydrogen and plasma having a plasma power density of about 0.01 W / cm ² to about 0.5 W / cm ² . Can be filled with steam. As already mentioned above, these reaction conditions result in the formation of a pure tantalum film on the substrate. The plasma is turned off and the reaction gas is changed from hydrogen to a reaction gas containing nitrogen such as ammonia. Under these inverted reaction conditions, a TaN _x film, where x is as described above, is deposited on top of the already deposited pure tantalum film, providing a double film on the substrate.

According to another preferred embodiment of the method of the present invention, the deposition reactor is about 0.01 W / cm to form a pure tantalum film on the substrate.²To about 0.5 W / cm²In the presence of a plasma having a plasma power density of and hydrogen, it is charged with vapor from the compound of formula (I). The plasma can then be turned off and a reactant gas comprising nitrogen, such as ammonia, is introduced together with the vapors of the different source precursors according to formula (I). Under these changed reaction conditions, TaN_x The film of was deposited on the pure tantalum film deposited for the first time, to provide a two-layer film of the present invention.

In situ, by varying the reaction gas, which may function as a carrier gas, a pure tantalum film, containing a single silicon in vapor phase, in order to reversibly and smoothly switch between TaSi _x and TaN _x Si _y Compounds and single source precursors can be used in continuous CVD. Thus, according to one preferred embodiment of the method, the deposition reactor is in the presence of hydrogen and plasma having a plasma power density of about 0.01 W / cm ² to about 0.5 W / cm ² to form a pure tantalum film on the substrate. It is filled with vapor from the compound of (I). The plasma is turned off and the reaction gas is changed from hydrogen to a reaction gas containing nitrogen, such as ammonia, which can also function as a carrier gas. The vapor of the compound comprising silicon of formula (II) is also introduced into the deposition reactor together with the reaction gas containing nitrogen. Under these conditions, the reverse reaction, x and y is a film of TaN _x Si _y independently greater than 0 and less than or equal to 2 deposited on a pure tantalum film deposited first and provides a double layer on the substrate.

According to another preferred embodiment of the method, the deposition reactor is in the presence of hydrogen and plasma having a plasma power density of about 0.01 W / cm ² to about 0.5 W / cm ² to form a pure tantalum film on the substrate. It is filled with vapor from the compound of (I). The plasma is turned off and the reaction gas is changed from hydrogen to a reaction gas containing nitrogen such as ammonia. The vapor of the compound comprising silicon of formula (II) is also introduced into the deposition reactor together with the reaction gas containing nitrogen. Under these inverted reaction conditions, x and y are deposited on the initially deposited pure tantalum film of TaN _x Si _y as defined above to provide a double layer on the substrate.

Based on this disclosure, none of the above-described embodiments may be modified or changed differently depending on each step, for example, any one of tantalum nitride, tantalum silicide or tantalum nitride nitride films may be first deposited on a substrate. Followed by deposition of a film based primarily on tantalum or other tantalum. Preferably, a pure tantalum film is first deposited in contact with the substrate, and the substrate is preferably a substrate comprising silicon or silicon. Based on this disclosure, it can be appreciated that two or more different layers can be deposited on the substrate without having to remove the substrate from the reaction zone.

In addition, according to this disclosure, it can be seen that any suitable CVD technique for producing tantalum or a tantalum based film can be used alone or in combination according to the method of the present invention. For example, thermal CVD using hydrogen carrier gas may be used to deposit pure tantalum, and then react gas containing nitrogen and / or at least one to deposit a tantalum nitride film to form a double film on the substrate. There is a use of plasma promoter CVD using nitrogen and hydrogen as carrier gas.

In situ, depositing tantalum and tantalum-based bilayers and multilayers as described above is very convenient for the manufacture of ULSI devices. The method of the present invention allows the formation of a double layer or multiple layers without the risk that the partially coated substrate is exposed to air and transported between the reaction chambers. The fact that bilayers or multiple layers can be made in a single reaction chamber can minimize the risk of contamination of the film that may occur during the transfer of the partially coated substrate between the reaction chambers. Contamination is particularly problematic for tantalum and tantalum-based membranes, because tantalum is highly reactive with oxygen, and even such minor contamination can compromise the usefulness of tantalum or tantalum-based coatings in ULSI devices. have.

The method of the present invention uses selected perhydrogenated tantalum compounds as source precursors that can be converted to high quality tantalum and tantalum based films by the use of thermal CVD or plasma promoter CVD. Similarly, the present invention provides an electron-grade tantalum nitride film by reacting the same perhydrogenated tantalum composite source precursor with a reaction gas containing nitrogen, wherein the same precursor comprises at least one carrier and / or reaction gas, silicon Electron-grade tantalum silicide and / or tantalum silicide are provided by reacting a vapor of a compound and / or a reaction gas comprising nitrogen which may be the same or different from at least one carrier and / or reaction gas. Exemplary schemes suitable for the process of the present invention are summarized below, wherein TaBr ₅ and SiI ₄ are included as compounds comprising exemplary tantalum source precursors and silicon:

Plasma Promote or Thermal CVD:

(Ⅲ)

(Main byproduct)

Plasma Promo CVD:

(Ⅳ)

(Main byproduct)

Thermal CVD:

(Ⅴ)

(Main byproduct)

Plasma Promote or Thermal CVD:

(Ⅵ)

(Main byproduct)

Plasma Promo CVD:

(Ⅶ)

(Main byproduct)

Thermal CVD:

(Ⅷ)

(Main byproduct)

Thermal CVD:

(Ⅸ)

(Main byproduct)

The present invention is described in accordance with the following non-limiting examples, together with the composition and shape of the film which is pure tantalum or other tantalum based film deposited according to the method of the present invention.

Example 1

Pure tantalum films were prepared in a standard CVD deposition chamber by the plasma promoter CVD method. The source precursor was tantalum bromide with a sublimation temperature in the range of 140 ° C to 200 ° C. The films were prepared under working reaction pressure in a deposition reactor of 100 mtorr to 10 torr. The carrier gas was hydrogen with a flow rate in the range between 10 standard cm ³ / min and 100 standard cm ³ / min. The reaction gas was also selected as hydrogen having a flow rate in the range between 100 standard cm ³ / min and 1000 standard cm ³ / min. Substrate temperature was 300 to 500 degreeC. RF plasma was used at a power density in the range of 0.1 W / cm ² to 0.25 W / cm ² . This film was deposited on silicon and silicon dioxide wafer substrates.

The tantalum film produced was metallic, continuous and mirrored. Fig. 1 shows the X-ray rotation analysis of a tantalum film grown at 800 standard cm ³ / min labor, sublimation temperature of 160 ° C., hydrogen power density 0.35 kPa, and working pressure in the reaction chamber at 700 mtorr. The formed film has a thickness measured in the direction perpendicular to the plane of the 350 mm 3 film on the silicon wafer substrate. X-ray diffraction analysis of FIG. 1 shows multiple diffraction peaks corresponding to polycrystalline tantalum phases. X-ray optoelectronic spectroscopes were performed on the same sample using a physical electronic model 10-360 spherical capacitor analyzer. The gold f _7/2 line at 83.8 eV was adopted as the baseline, and the scale of the analyzer was adjusted accordingly. All spectra were obtained using a pass energy of 5 eV at a resolution of 0.8 eV. Primary ke-rays of 15 keV and 300 W (MgKa, 1274 eV) were selected. The pressure in the chamber was in the range of 10 ^-10 torr and the results were normalized using high purity sputtered tantalum samples. All samples were cleaned by sputtering before data acquisition. The choice of composition and chemical environment and bonding standards similar to CVD films allows high precision in x-ray optoelectronic spectroscopy analysis. The results are based on the expectation that the chemical and structural changes inherent during the cleaning process, if any, will be essentially the same as in standard and CVD prepared films. The x-ray photoelectron spectrum is shown in FIG. 2 and shows pure tantalum at contamination levels below the 1 at% detection limit of the x-ray photoelectron spectroscope.

The chemical composition of the same membrane was again tested by Auger electron spectroscopy using a physical electronic model 15-110B cylindrical mirror analyzer. The gold f _7/2 line at 83.8 eV was chosen as the reference stone and the analyzer scale was adjusted accordingly. The primary electron energy of 5 keV at 1 mA was used. The pressure in the chamber was in the range of 10 ^-10 torr and the results were normalized using high purity sputtered tantalum samples. All samples were cleaned by sputtering before data acquisition. High precision in Auger Spectroscopy analysis was obtained by selecting standards of bonding and chemical environment and composition similar to CVD films. As with the x-ray optoelectronic spectroscopy, the results are based on the expectation that the chemical and structural changes induced during the cleaning process are basically the same as the standard and plasma promoter CVD prepared films. The Auger electron spectrum shown in FIG. 3 confirms the results of the X-ray photoelectron spectroscopy on the purity of tantalum phase at a contamination level below 1 at% detection error of the Auger electron spectroscopy. Four-point probe resistivity measurements revealed that the film had a resistivity of 117 μohm-cm.

Rutherford backscattering spectra were obtained using a 2 MeVHe ⁺ line and calibrated with bulk samples of high purity gold and carbon films and silicon. Rutherford backscattering spectra are shown in FIG. 4. This measurement confirms the facts found in Auger Spectroscopy and X-ray Photoelectron Spectroscopy in relation to the purity of tantalum phase, especially the absence of contamination of heavy elements in the tantalum film. In particular, Rutherford backscattering spectra indicate that there is less than 3 at% bromine in the film.

The properties of tantalum films related to silicon substrates were investigated next. Tantalum films were observed to adhere well to silicon or silicon dioxide. Cross-sectional scanning electron microscopy analysis of membrane step coverage was also adopted. The term "insulation protection" refers to a film or coating that uniformly covers a substrate having a composite topography. Uniformity of the coating can be measured, for example, by testing the thickness of the coating along the walls and bottoms of the holes in the substrate and also determining the change in the thickness of the coating. This measurement yields a value for step coverage, which is the ratio of the thickness at the bottom of the hole to the thickness at the substrate surface outside the hole. Single-sided scanning electron microscopy was performed using a Zeiss DSM940 microscope employing a primary electron beam of 20 keV and a beam current of 4 μA. The cross-sectional scanning electron micrograph shown in FIG. 5 is for a 350 mm thick tantalum film showing the insulation protection step coverage of a 0.25 μm via having an aspect ratio of 4 (defined as the height of the via divided by its diameter).

The micrograph of FIG. 5 shows that a tantalum film deposited on a substrate with a 4: 1 aspect ratio and a 0.25 μm diameter trench using plasma promoter CVD has 80% step coverage. 5 shows that even after an extended deposition time yielding a thick tantalum nitride film, the plasma promoter CVD used in the method of the present invention provides an insulating protective film with high step coverage. This membrane was prepared using hydrogen and tantalum 5 bromide.

Example 2

Pure TaN _x films were prepared by thermal CVD in a standard CVD deposition chamber. The source precursor was tantalum bromide with a sublimation temperature in the range of 140 ° C to 200 ° C. The membrane was prepared using hydrogen as a carrier gas at a flow rate of 10 standard cm ³ / min to 100 standard cm ³ / min and using a working pressure inside the deposition reactor of 100 mtorr to 10 torr. The reaction gas containing nitrogen was ammonia at a flow rate of 100 standard cm ³ / min to 1000 standard cm ³ / min. The substrate temperature and the reactor temperature were 250 ° C to 500 ° C. This film was deposited on silicon and silicon dioxide wafer substrates.

The resulting tantalum nitride film was metallic, continuous, and mirrored. X-ray diffraction analysis was adopted for the growth of a TaN _1.2 film at 425 ° C. with 600 standard cm ³ / min ammonia with a sublimation temperature of 170 ° C. The working pressure of the reactor was 950 mtorr. 6 shows an x-ray diffraction pattern for a film with a film having a thickness of 1900 μs deposited on a silicon substrate. The x-ray rotation pattern exhibited a corresponding rotation peak mostly on amorphous TaN _1.2 . X-ray photoelectron spectroscopy was performed using a physical electronic Model 10-360 spherical capacitor analyzer. The gold f _7/2 line at 83.8 eV was chosen as the baseline and the analyzer calibrated accordingly. Primary x-rays (MgKa, 1274 eV) of 15 keV and 300 W were used. The pressure in the assay chamber ranged from 10 ^-10 torr and the results were normalized using TaN samples sputtered with high purity. All samples were cleaned by sputtering before data acquisition. Choosing standards such as composition and chemical environment and the like, similar to CVD films, allows for high precision in x-ray optoelectronic spectroscopic analysis. The results are based on the expectation that the chemical and structural changes induced during the cleaning process are essentially the same as in films made by standard and CVD. X-ray photoelectron spectra are shown for the same sample in FIG. 7A, showing pure TaN _1.2 phase of contamination levels below the 1 at% detection limit of x-ray photoelectron spectroscopy. The x-ray photoelectron high resolution spectrum of the N peak in TaN produces a binding energy of 398.2 eV corresponding to the nitride image as shown in FIG. 7B.

The chemical composition of the membrane was likewise tested by Auger Spectroscopy using a Physical Electronics Model 15-110B Cylindrical Mirror Analyzer. The gold _7/2 line at 83.8 eV was taken as the baseline and the scale of the analyzer was adjusted accordingly. All spectra were obtained using a pass energy of 23.5 eV. At 1 mA, 5 keV of primary electron energy was used. The pressure in the assay chamber was in the range of 10 ^-10 torr and the results were normalized using high purity sputtered TaN samples. All samples were cleaned by sputtering before data acquisition.

High precision in Auger Spectroscopy analysis was obtained by selecting standards of bonding and chemical environment and composition similar to CVD films. As with the x-ray optoelectronic spectroscopy, the results are based on the expectation that the chemical and structural changes induced during the cleaning process are basically the same as the standard and plasma promoter CVD prepared films. The Auger electron spectrum shown in FIG. 8 confirms the results of the X-ray photoelectron spectroscopy on the purity of the TaN phase at a contamination level below 1 at% detection error of the Auger electron spectroscopy. Four-point probe resistivity measurements revealed that the film had a resistivity of 2 × 10 ⁴ μohm-cm.

Rutherford backscattering spectra were obtained using 2 MeVHe ⁺ lines and calibrated with bulk samples of high purity sputtered TaN film, carbon film and silicon. Rutherford backscattering measurements of the membranes are shown in FIG. 9, confirming the fact that they were found in Auger X-ray photoelectron spectroscopy with respect to the purity of TaN phase, especially the absence of heavy element contamination in the TaN _1.2 membrane. In particular, Rutherford backscattering spectra indicate that there is less than 1 at% bromine in the film.

The nature of the TaN _1.2 film associated with the silicon substrate was also investigated. Tantalum nitride films were observed to adhere well to silicon or silicon dioxide. Cross-sectional scanning electron microscopy analysis of membrane step coverage was also adopted. Single-sided scanning electron microscopy was performed using a Zeiss DSM940 microscope employing a primary electron beam of 20 keV and a beam current of 4 μA. The cross-sectional scanning electron micrograph shown in FIG. 10 is for a 1900 mm thick TaN film showing the insulation protection step coverage of a 0.25 μm via having an aspect ratio of 4.

The micrograph of FIG. 10 shows that a tantalum film deposited on a substrate with a 4: 1 aspect ratio and a nominal 0.25 μm diameter trench using thermal CVD has 80% step coverage. These micrographs show that even after an extended deposition time yielding a thick tantalum nitride film, thermal CVD used in the method of the present invention provides an insulating protective film with high step coverage. This membrane was prepared using tantalum 5 bromide as the source precursor and ammonia as the reaction gas.

Example 3

Plasma promoter chemical deposition was performed using TaBr ₅ as a tantalum source precursor. The source precursor was placed in a sublimer heated to a temperature between 140 ° C. and 200 ° C. by a combination of heating tape and associated power source during the CVD process. The mass flow controller, separated from the sublimer by a high pressure vacuum valve, regulated the hydrogen carrier gas at a flow rate of 10 to 100 standard cm ³ / min into the sublimer. A mixture of source precursor steam and hydrogen carrier gas was returned to the CVD reactor. All return and transmission lines and high pressure vacuum separation valves were maintained at temperatures in the range of 140 ° C. and 200 ° C. to prevent precursor recondensation.

Deposition was performed in a cold wall, stainless steel CVD reactor, for 6 inch wafers. The reactor is equipped with a diode type, flat plate plasma device made of two electrodes. The top plate functions as an active electrode and is driven by a radio frequency (13.56 MHz) power supply. It consists of a "mesh" type and allows the reactants to flow into the substrate without clogging. Hydrogen plasma was used for predeposited substrates cleaned at a plasma power density in the range of 0.1 to 0.5 W / cm ² , and hydrogen plasma having a power density of 0.1 to 0.25 W / cm ² was used for the actual deposition. The substrate (wafer) was placed on a lower, grounded plasma electrode and heated by a resistive heater to a processing temperature in the range of 350 to 500 ° C. In order to ensure the cleanliness of the process, the reactor was baked periodically under nitrogen or argon atmosphere of 0.3 torr or less, and reduced to 10 ^-6 torr for 1 hour at 150 ° C. The pump device consisting of two pumps, one was a cryogenic pump and the second was a Roots blower pump, which were separated from the reactor by a high vacuum gate valve. Cryogenic pumps are used to ensure high vacuum base pressure in the reactor, and Roots blower pumps are used to properly handle high gas yields during actual CVD. A high pressure vacuum loadlock system was used to transport and load 6 inch wafers into the reactor. Finally, sidelines were used to feed hydrogen (H ₂ ) gas into the reactor. The flow rate of hydrogen was 100-1000 liters / minute and was controlled using a massflow controller and associated isolation valves.

The resulting tantalum film was metallic, continuous and mirrored. These structural and electrical properties and chemical compositions were analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Rutherford backscattering, 4-point probes, and cross-sectional scanning electron microscopy as discussed in Examples 1 and 2 above. It became. Based on these analyzes, the tantalum films exhibited the typical properties of the tantalum film described in Example 1 above.

Example 4

Tantalum nitride film deposition of a TaN film was performed by thermal CVD using tantalum pentabromide as a chemical source precursor. It was performed under similar processing conditions as described in Example 3 for pure tantalum deposition, except that no plasma was used during the actual deposition. In this case, the substrate was heated to a treatment temperature in the range of 250 ° C to 500 ° C by a resistive heater, and ammonia was used as the reaction gas and carrier gas containing nitrogen. Through the sidelines NH ₃ at a flow rate of 100 to 1000 liters / minute was controlled by the massflow controller and associated separation valves.

The resulting tantalum film was metallic, continuous and mirrored. These structural and electrical properties and chemical compositions were analyzed by x-ray diffraction, x-ray photoelectron spectroscopy, Rutherford backscattering, four-point probe and cross-sectional scanning electron microscopy. Based on these analyzes, the tantalum films exhibited the typical properties of the tantalum film described above in Example 2.

Example 5

Successive depositions of two layers of pure tantalum and tantalum nitride were performed in situ using tantalum pentabromide as the source precursor. The pure tantalum layer was first grown using the plasma promoter CVD described in Example 3 above with argon as the carrier gas. Then, the tantalum nitride layer was grown on top of the tantalum layer by turning off the plasma, replacing argon with ammonia functioning as a reaction gas containing nitrogen, and using thermal CVD in the manner described in Example 4. These films were analyzed as above and were found to exhibit the properties of tantalum and tantalum nitride as described in Examples 1 and 2. Under certain conditions, nitrogen doping of the tantalum layer was possible even during the deposition of tantalum nitride. This example is shown in relation to the film formed in Example 2 and is illustrated in the Auger electron spectrum as shown in FIG. 10.

Membranes prepared according to the method of the present invention have an electronic grade of purity and are therefore suitable for use in applications such as microelectronic applications requiring extremely stringent purity. Membranes prepared as described in the claims of the present invention have carbon and oxygen purity levels of 1 at% or less. The membranes prepared from the process of the invention also had little contamination of halogens such as iodine, bromine, chlorine or fluorination. Thus, by the method of the present invention, the membranes can achieve halogen contamination of about 5 at% or less and more preferably contamination level of 1 at% or less.

With this high purity, pure tantalum and tantalum based films formed by the present invention have low resistance. The membranes of the present invention have a resistivity of about 50 to 5,000 μohm-cm, preferably 50 to 1000 μohm-cm, more preferably 40 to 150 μohm-cm.

Compared with the prior art chemical vapor deposition methods, the method of the present invention provides an electrotechnical grade film with little carbon, oxygen or halide contamination. Compared to sputtering techniques, the present invention has the superior advantages of the features inherent in the manufacture of microelectronic devices.

It will be apparent to those skilled in the art that various modifications can be made to the above-described embodiments without departing from the broad inventive concept of the invention. Accordingly, the invention is not intended to be limited to the specific embodiments described above, but these embodiments are intended merely to cover modifications within the spirit and scope of the invention as defined in the appended claims.

Claims (26)

(a) (iii) a substrate; (Ii) a vapor source precursor having general formula (I): and (I) Where m is an integer from 0 to 5, n is an integer from 0 to 4, p is An integer from 0 to 4, R is selected from the group consisting of hydrogen and lower alkyl) (Iii) introducing at least one carrier gas into the deposition chamber; (b) maintaining the temperature of the substrate in the deposition chamber at a temperature of about 70 ° C. to about 675 ° C. for a time sufficient to deposit a film comprising tantalum on the substrate. A method of chemical vapor deposition of a film comprising tantalum. The method of claim 1, wherein the at least one carrier gas is selected from the group consisting of hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide, nitrogen, ammonia, hydrazine, nitrous oxide and water vapor. Which method is chosen. The method of claim 1 wherein the flow rate of the at least one gas is greater than 0 and less than 10 l / min. The method of claim 1, wherein a plasma having a plasma power density of about 0.01 W / cm ² to about 10 W / cm ² is introduced into the deposition chamber for a time period sufficient to deposit a film comprising tantalum on a substrate. The method further comprises the steps. The method of claim 4, wherein the plasma has a frequency of about 0 Hz to 10 ⁸ kHz. The method of claim 1, further comprising applying one of at least a direct current bias, a low frequency bias of 500 kHz, a high frequency bias of 500 kHz to 10 ⁶ kHz, and a micro frequency bias of 10 ⁶ kHz to 10 ⁸ kHz to the substrate. How to be. 7. The method of claim 6, wherein the electrical bias has a power density of at least 0 Watts / cm ² and at most about 10 ³ Watts / cm ² . 8. The method of claim 7, wherein the electrical bias has a power density of at least 0 Watts / cm ² and at most about 10 Watts / cm ² . The method of claim 1, wherein the substrate comprises a material selected from the group consisting of metal, glass, plastic, and polymer. The method of claim 9, wherein the substrate is aluminum, beryllium, cadmium, cerium, chromium, cobalt, copper, gallium, gold, iron, lead, manganese, molybdenum, nickel, palladium, platinum, rhenium, rhodium, silver, stainless steel And a metal selected from the group consisting of steel, iron, strontium, tin, titanium, tungsten, zinc, zirconium and their alloys and their compounds. The method of claim 1, wherein the temperature of the substrate in the deposition chamber is maintained at about 250 ° C. to about 500 ° C. 7. The method of claim 1, wherein the source precursor is tantalum pentabromide. The method of claim 1 wherein said at least one carrier gas is hydrogen. 2. The film of claim 1, wherein the film comprising tantalum is a pure tantalum film; The at least one carrier gas is selected from the group consisting of hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide and water vapor; The temperature of the substrate in the deposition chamber is maintained at about 100 ° C to about 675 ° C. The film of claim 1, wherein the film comprising tantalum is a TaSi _y film, wherein y is 0 or more and 3 or less; Process (a) is carried into the deposition chamber: (Iii) introducing a compound comprising silica in the vapor state; The at least one carrier gas is selected from the group consisting of hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide and water vapor. The method of claim 15, wherein the compound comprising silicon has general formula (II): (II) Wherein m is an integer of 0 to 4, n is an integer of 0 to 4, p is an integer of 0 to 4, R is selected from the group consisting of hydrogen and lower alkyl. 2. The film of claim 1, wherein the film comprising tantalum is a TaN _x film, wherein x is 0 or more and 2 or less; Process (a) is carried into the deposition chamber: And (iii) introducing a reaction gas comprising nitrogen, the same or different as said at least one carrier gas. 18. The method of claim 17, wherein the reaction gas comprising nitrogen is selected from the group consisting of nitrous oxide, ammonia, nitrogen, and hydrazine. 2. The film of claim 1, wherein the film comprising tantalum is a TaN _x Si _y film, wherein x is 0 or more and 2 or less, and y is 0 or more and 3 or less; Process (a) is carried into the deposition chamber: (Iii) a compound comprising silicon in vapor form; And (Iii) introducing a reaction gas comprising nitrogen, which may be the same as or different from at least one carrier gas; Wherein said at least one carrier gas is selected from the group consisting of hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, nitrogen, ammonia, hydrazine, nitrous oxide, carbon monoxide, carbon dioxide and water vapor. 20. The method of claim 19, wherein the compound comprising silicon comprises the following general formula (II): (II) M is an integer of 0-4, n is an integer of 0-4, p is a testicular of 0-4, R is chosen from the group which consists of hydrogen and lower alkyl. The method of claim 1, (c) depositing a second film comprising tantalum on the film deposited on the substrate to form a multi-layer structure while the substrate is fixed in the deposition chamber, the second film comprising tantalum; 2 film is pure tantalum film, TaN _x film (x is 0 or more and 2 or less); TaSi _y film (y is 0 or more and 2 or less); And a TaN _x Si _y film. The film of claim 21, wherein the second film is a pure tantalum film, Process (c) comprises: said source precursor in vapor form and at least one carrier gas selected from the group consisting of hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide and water vapor; It further comprises a step of introducing into the deposition chamber, Maintaining the deposition chamber at a temperature of about 100 ° C to about 675 ° C. The method of claim 21, wherein the second film is a TaN _x film, wherein x is 0 or more and 2 or less, The step (c) introduces into the deposition chamber a reaction gas comprising the source precursor in the vapor state and the at least one carrier gas and nitrogen which may be the same as or different from the at least one gas. Further comprising a process; Maintaining the deposition chamber at a temperature of about 100 ° C to about 675 ° C. The film of claim 21, wherein the second film is a TaSi _y film, wherein y is 0 or more and 2 or less; Step (c) is carried out into the deposition chamber: The source precursor in the vapor state; At least one carrier gas selected from the group consisting of hydrogen, helium, oxygen, fluorine, neon, chlorine, argon, krypton, xenon, carbon monoxide, carbon dioxide and water vapor; And introducing a compound comprising vaporized silicon. The method of claim 21, wherein the second film is a TaN _x Si _y film, wherein x is 0 or more and 2 or less, and y is 0 or more and 3 or less; Step (c) is carried out into the deposition chamber: The source precursor in the vapor state; The at least one carrier gas; A compound comprising silicon in vapor state; And And introducing a reaction gas comprising nitrogen which may be the same as or different from at least one carrier gas. The substrate of claim 1, wherein the substrate comprises silicon: (c) further comprising heating the substrate and the deposited film comprising tantalum to a temperature of about 700 ° C. to about 950 ° C. to provide silicon on the deposited film comprising tantalum.