JP2002543589A - Formation of CVD TiN plug from titanium halide precursor - Google Patents

Abstract

Abstract: A method of depositing a high quality titanium nitride (TiN) film and filling small contacts with high aspect ratio features using TiN. This method uses a CVD method using titanium tetraiodide (TiI ₄ ) as a precursor material. This method allows TiN films having a thickness greater than about 0.3 μm to be deposited without crack formation. For a sufficiently high TiN deposition rate and a sufficiently low TiN resistivity, the process temperature is at least about 500 ° C. This method varies the process pressure to achieve seamless plug filling in high aspect ratio structures.

Description

DETAILED DESCRIPTION OF THE INVENTION

TECHNICAL FIELD [0001] The present invention relates to the formation of integrated circuits, and specifically to the chemical vapor deposition of titanium nitride films from titanium halide precursors.

BACKGROUND OF THE INVENTION Integrated circuits provide a signal transport path for electrical devices. An integrated circuit (IC) in one device is made up of a number of active transistors contained in a silicon base layer of a semiconductor substrate. To increase the capacity of the IC, one of the
Numerous connections are made by metal "wires" between one active transistor and another active transistor in the silicon base of the substrate. These connections, collectively known as circuit metal connections, are made through features such as holes, vias or trenches cut into the substrate. The specific metal connection that actually makes contact with the silicon base is what is known as a contact. The rest of the holes, vias or trenches are filled with a conductive material called a contact plug. Higher levels of IC as transistor density continues to increase
Is formed, the diameter of the contact plugs accordingly increases with an increased number of connections,
Multilayer metallization structures and aspect ratios must be reduced to account for larger vias.

[0003] Vias larger than about 0.16 μm in diameter are typically filled as follows. An approximately 100 ° titanium (Ti) liner is first deposited by CVD or PVD.
Is vapor-deposited using any of the above. This Ti layer improves the electrical contact to the silicon base layer. Next, a titanium nitride (TiN) liner of about 500 ° is deposited on the Ti layer. Deposition may be by either CVD or PVD,
Low pressure CVD (LPCVD) is preferred. Because only LPCVD provides the conformity defined as the ability to accurately replicate the underlying substrate topography needed to cover the bottom and sidewalls of high aspect ratio submicron structures. is there. This TiN layer is made of tungsten (W) from the following WF _6.
Serves as a metal diffusion barrier to protect Ti from corrosion attack by fluorine (F) during the deposition of Ti. Since W does not adhere to metal oxides, TiN also serves as an adhesion layer for W. Although TiN provides an excellent contact barrier, the TiN must have a thickness of about 500 ° to be effective as a barrier. TiN
If the thickness is less than about 500 °, the Ti metal will diffuse into the silicon. The remainder of the plug is then filled with W deposited by CVD. W is used because it has a low electric resistivity and is reliable in forming a contact plug.
This W layer provides a low resistance region that is important for current conduction in the IC. Next, the surface of the contact plug is etched or polished. The resulting planarized surface is necessary for optimal metallization and thus for optimal functioning of the IC.

As the density of transistors continues to increase, features continue to shrink, that is, their diameters are less than 0.25 μm. The diameter of the contact plug must be reduced in view of its increased number of connections. About 0.16μ in diameter
For vias less than m, however, the resistance of the metallization layer of the contact plug is dominated by the TiN diffusion barrier layer. Since the TiN barrier layer must be at about 500 ° for durability as a diffusion barrier, the portion of the contact plug filled with W is reduced. For example, a 0.15 μm diameter structure has a film or “core” of W at only about 300 ° at the center of the plug. Thus, the effective plug resistance becomes dominated by the higher resistivity TiN and, more importantly, by the resistance at the interface between the TiN layer and the W layer.

[0005] The subsequent filling of the contact plug with W then constitutes a special operating step with no significant effect on the total resistance of the contact plug. Thus, it is believed that the process steps in the formation of the IC can eliminate this, thus increasing manufacturing efficiency by filling vias with TiN-only contact plugs rather than with TiN and W. Therefore, what is needed is a C
In this method, a TiN contact plug is formed by VD, and the W layer of the contact plug is eliminated when an IC is formed.

[0006] TiN films deposited by CVD, however, have relatively high stresses. A membrane with high stress has a greater strength of internally dispersed forces or force components that resist changes in volume or shape of the membrane when it is subjected to external forces. This high stress limits the maximum film thickness that can be deposited. Typically, the maximum thickness of a TiN film deposited over a conventional first level oxide deposited by CVD is about 800 °. About 800Å
Thicker TiN films begin to crack due to internal stresses in the film. TiN, defined as a discontinuity in the surface material that is large enough to increase the resistance of the TiN film
Microcracks appearing on the film surface thus provide sub-optimal performance for the IC.

[0007] The absolute thickness of the W layer can vary according to the dimensions of the via to be filled, but its relative thickness is about 80% of the via diameter. This is because the deposited film must not only fill the entire volume of the via with the contact plug, but also the "dent" above the contact plug. This "dent", defined as a dent in the TiN formed during via filling, is eliminated by further depositing TiN on the top surface of the plug to provide a capping layer. Thus, a 0.25 μm feature requires a TiN film having a thickness of 2000 ° (0.8 × 2500 °). For good plug filling, it is also very important that the TiN film be continuous, perfectly consistent and seamless.
A conformable film is one that accurately reproduces the surface profile of the underlying substrate. A seamless film is one that does not contain cracks.

A CVD method in which a via in a substrate is filled with a TiN plug and the upper surface is covered with a TiN layer
Is hereby incorporated by reference in its entirety.
U.S. patent application Ser. No. 08 / assigned to US Electron Limited.
964,532. These features are TiCl _Four It can be obtained by the existing TiN deposition method by the CVD method using the precursor.
I can't. TiCl_FourAccording to the precursor, the film has a thickness of more than about 500-800Å
Then you can always crack. The formation of cracks depends on the underlying layer
Acceptable because it prevents the adhesion of the membrane and "peels" the membrane, thus putting the subsequent process at risk
Can not. The formation of cracks also increases the expected electrical resistivity of the plug.

[0009] Therefore, a method of filling high aspect ratio vias with high quality conformal contact plugs of TiN without crack formation is desired. Such a film would eliminate the W deposition step and thus reduce the number of process steps to fill the contacts. This would be a significant savings in device processing.

SUMMARY OF THE INVENTION To this end, according to the principles of the present invention, high aspect ratio vias are made of TiN
A method of filling with a plug to eliminate the tungsten deposition step is disclosed. TiN
The plug is deposited from a titanium iodide (TiI) precursor by CVD. Preferred TiI precursor is a titanium tetraiodide (TiI _4), which is deposited by thermal CVD.

The present invention also relates to a method for completely filling high aspect ratio vias having a diameter of less than about 0.16 μm with a CVD deposited TiN layer.

[0012] The present invention also provides a method of forming a ICN by CVD of a TiN layer provided with a TiI ₄ precursor.
And forming a contact plug in the via. The via is a high aspect ratio via having a diameter of less than about 0.16 μm.

The TiN film filling the contact plug according to the present invention has a shape
0% consistency. Films that are 100% compatible are beneficial because they accurately reproduce the topography of the underlying substrate, which allows for optimal functioning of the IC. Thus, this method is useful for completely filling high aspect ratio features. Another advantage of this method is that the separate process step of depositing W is eliminated, saving both time and money. This method also involves the T layer of the W layer.
It also eliminates the problem of adhesion to iN. These and other objects and advantages of the present invention will be apparent from the accompanying drawings and description thereof.

DETAILED DESCRIPTION In a chemical vapor deposition (CVD) method, a gas precursor is activated using either thermal energy or electrical energy. Once activated, the gas precursor reacts chemically to form a film. One preferred method of CVD is illustrated in FIG. 1, which is assigned to Tokyo Electron, Westen Dope, Inc., filed on the same day as the present application and incorporated herein by reference in its entirety. Westen
Dorp) et al., in a co-pending application entitled "Apparatus and method for delivering vapor from a solid source to a CVD chamber." Chemical vapor deposition (CVD) system 10
Includes a CVD reaction chamber 11 and a precursor delivery system 12. Reaction chamber 1
In 1, a reaction is performed to convert a precursor gas comprising a titanium halide compound, for example, titanium iodide (TiI), to a film such as a barrier layer film of TiN.

The precursor delivery system 12 includes a source 13 of precursor gas having a gas outlet 14, the gas outlet 14 passing through a metering system 15 and the gas inlet 16 and the CVD reaction chamber 11.
It is connected to. Source 13, the precursor gas, for example, each TiI compound TiI vapor, preferably to produce from TiI _4. This compound is a compound that is in a solid state at standard temperature and pressure. The precursor source is maintained at a temperature that provides the desired precursor vapor pressure, preferably by controlled heating. The vapor pressure is itself a vapor pressure sufficient to deliver the precursor vapor to the reaction chamber 11, preferably without a carrier gas. The metering system 15 maintains the flow of the precursor gas vapor from the source 13 into the reaction chamber 11 at a rate sufficient to maintain an industrially viable CVD process in the reaction chamber 11.

The reaction chamber 11 is a commonly used CVD reactor and includes a vacuum chamber 20 whose boundary is defined by an airtight chamber wall 21. In the chamber 20, a substrate support for supporting a substrate such as a semiconductor wafer 23, that is, a susceptor 22 is arranged. The chamber 20 includes a semiconductor wafer substrate 23
A vacuum is maintained that is appropriate for performing a CVD reaction on which to deposit a film such as a TiN barrier layer. The preferred pressure range is 0.2-5.0 torr. This vacuum is maintained by controlled operation of vacuum pump 24 and inlet gas supply 25. The inlet gas supply 25 includes a delivery system 12 and a hydrogen (H ₂ ), nitrogen (N ₂ ) or ammonia (NH ₃ ) reducing gas supply, for example, for use in performing a Ti reduction reaction. 26 and an inert gas supply 27 for a gas such as argon (Ar) or helium (He). Gases from a source 25 enter the chamber 20 through a showerhead 28, which is positioned at one end of the chamber 20 facing the substrate 23, generally facing parallel to the substrate 23.

The precursor gas supply 13 includes a sealed evaporator 30, which includes a cylindrical evaporator 31 having a vertically oriented axis 32. The vessel 31 is delimited by a cylindrical wall 33 made of a high temperature resistant non-corrosive material, such as the alloy INCONEL 600, whose inner surface 34 is highly polished. It is smooth. The wall 33 has a flat closed circular bottom 35 and an open top, the top of which is sealed with a cover 36 of the same heat-resistant, non-corrosive material as the wall 33. The outlet 14 of the source 13 is located in the cover 36. When high temperatures are used, such as when using TiI ₄ or TaBr ₅ , the cover 36
A high temperature resistant, vacuum-fitting metal seal 38, such as a HELICOFLEX seal, formed from a C-shaped nickel tube surrounding an Inconel coil spring, is integrated with the top of the wall 33. The flange ring 37 is sealed. When using a material requiring lower temperatures, such as TaCl ₅ and TaF _5, elastomeric O- ring seal 38 conventional to seal the cover can be used.

A supply 39 of a carrier gas, preferably an inert gas such as He or Ar, is connected to the container 31 through a cover 36. Source 13 is loaded in the container 31 in a solid state at normal temperature and pressure, TiI, preferably comprises an amount of the precursor material with such as TiI ₄ in the bottom of the container 31. Container 3
1 is filled with TiI vapor by enclosing the solid agglomerate of TiI therein in this container 31. The TiI is supplied as a precursor agglomerate 40 and is placed at the bottom of the container 31. At the bottom, the precursor is preferably heated to a liquid state as long as the resulting vapor pressure is acceptable. If the agglomerate 40 is liquid, the vapor is above the level of the liquid agglomerate 40. Since the wall 33 is a vertical cylinder, TiI
The surface area of the agglomerate 40, if it is a liquid, remains constant regardless of the depletion level of TiI.

The delivery system 12 is not limited to the direct delivery of the precursor 40, but includes a gas supply 39
Alternative methods of delivering the precursor 40 with a carrier gas that can be introduced from the can be used. Such a gas may be hydrogen (H ₂ ) or an inert gas such as helium (He) or argon (Ar). If a carrier gas is used, it can be introduced into the vessel 31 so as to be distributed throughout the top surface of the precursor agglomerate 40, or
Can be introduced into the vessel 31 in an upward diffusion to penetrate through the agglomerate 40 from the bottom 35 of the vessel 31 to achieve maximum surface area exposure to the carrier gas. Yet another alternative is to vaporize the liquid present in the container 31. However, such an alternative would add undesirable particulates and would not achieve the controlled delivery rate achieved by direct delivery of the precursor, i.e., delivery without a carrier gas. Therefore, direct delivery of the precursor is preferred.

To maintain the temperature of the precursor 40 in the container 31, the bottom 35 of the wall 33 is kept in thermal communication with a heater 44. The heater 44 converts the precursor 40 to a vapor pressure greater than about 3 Torr in the absence of a carrier gas (ie, a direct delivery system) and a lower vapor pressure such as about 1 Torr when a carrier gas is used. , Preferably above the melting point of the precursor. The exact vapor pressure will depend on other variables, such as the amount of carrier gas, the surface area of substrate 23, and the like. T
iI, in particular a direct delivery system TiI _4, such temperature is in the range of about 180 to 190 ° C.. The temperature should not be so high in the showerhead 28 that it would otherwise cause the gas to react prematurely before contacting the wafer 23.

For the purpose of example, assume that a temperature of 180 ° C. is the control temperature for heating the bottom 35 of the container 31. This temperature is a suitable temperature to provide a vapor pressure that is desired using TiI ₄ precursor. Given this temperature at the bottom 35 of the container 31, the cover is separately controlled in thermal contact with the outside of the cover 36 to prevent condensation of the precursor vapor on the wall 33 and the cover 36 of the container 31. The heater 45 maintains the bottom 35 of the wall 33 at a higher temperature than the heater 44, for example, at 190 ° C. The sides of the chamber wall 33 are included between the chamber wall 33 and a concentric outer aluminum wall or can 47 surrounding it.
It is surrounded by an annular space 46 in which air is trapped. The can 47 is
It is surrounded by an annular insulating layer 48 of silicon foam. This temperature holding arrangement
The precursor vapor in the volume of the chamber bounded by the cover 36, the sides of the wall 33 and the surface 42 of the precursor agglomerate 40 is reduced from the desired exemplary temperature range of 180-190 ° C. and about 3 Torr. Maintain high pressure, preferably greater than 5 torr. The appropriate temperature to maintain the desired pressure depends on the precursor material,
The material is believed to be primarily a titanium halide compound.

The vapor flow metering system 15 has at least about 2 standard cubic centimeters per minute (
sccm) and at a desired flow rate of up to 40 sccm, so as not to give an appreciable pressure drop, or at least 1/2 inch in diameter or at least 10 mm in inner diameter, preferably Includes a larger delivery tube 50. The delivery tube 50 extends from the precursor gas supply 13 to the reaction chamber 11, where the tube 50 connects to the outlet 14 at its upstream end and to the inlet 16 at its downstream end. The total length of the tube 50 from the evaporator outlet 14 to the reactor inlet 16 and the showerhead 28 of the reaction chamber 20 is also preferably heated to a temperature above the evaporation temperature of the precursor material 40, for example to 195 ° C.

Provided within the tube 50 is a baffle 51 in the center of which is disposed a circular orifice 52, preferably about 0.089 inches in diameter. Gauge 1 (56)
The pressure drop from to the gauge 2 (57) is regulated by the control valve 53. Control valve 5
After 3, and through orifice 52 to reaction chamber 11, this pressure drop is greater than about 10 millitorr, which is proportional to the flow rate. Outlet 1 of evaporator 13
In a line 50 between the control valve 4 and the control valve 53, a shutoff valve 54 is provided for closing the container 31 of the evaporator 13.

The system 10 includes information to the controller 60 for use in controlling the system 10, including controlling the flow rate of the precursor gas from the delivery system 15 to the chamber 20 of the CVD reaction chamber 11. Pressure sensors 55-58 are provided. These pressure sensors are used to monitor the pressure in the evaporation vessel 31.
It includes a sensor 55 connected to the pipe 50 between the outlet 14 of the evaporator 13 and the shut-off valve 54. The pressure sensor 56 monitors the pressure upstream of the orifice 52,
The pressure sensor 57 is connected to the pipe 50 between the control valve 53 and the baffle 51,
It is connected to a tube 50 between the baffle 51 and the reactor inlet 16 to monitor the pressure downstream of the orifice 52. Yet another pressure sensor 58 is C
It is connected to the chamber 20 of the reaction chamber 11 to monitor the pressure in the VD chamber 20.

Control of the flow of the precursor vapor into the CVD chamber 20 of the reaction chamber 11
Achieved by controller 60 in response to pressure sensed by sensors 55-58, particularly sensors 56 and 57, which measure the pressure drop across orifice 52. When the conditions are such that the flow of precursor vapor through orifice 52 is unchoked, the actual flow of precursor vapor through tube 52 is a function of the pressure monitored by pressure sensors 56 and 57. Which can be determined from the ratio of the pressure measured by sensor 56 upstream of orifice 52 to the pressure measured by sensor 57 downstream of orifice 52.

When the conditions are such that the flow of precursor vapor through orifice 52 is choked, the actual flow of precursor vapor through tube 52 is
7 is a function of only the pressure monitored. In any case, the presence of choked flow or non-choked flow can be ascertained by controller 60 by interpreting the process conditions. When this confirmation is made by the controller 60, the flow rate of the precursor gas can be determined by calculation by the controller 60.

An accurate determination of the actual flow rate of the precursor gas can be made computationally by retrieving flow rate data from a look-up or multiplier table stored in a non-volatile memory 61 accessible by the controller 60. preferable. Once the actual flow rate of the precursor vapor is determined, one or two of the control of the pressure of the CVD chamber by the variable orifice control valve 53, the exhaust pump 24, or the reducing or inert gas from the sources 26 and 27. The desired flow rate can be maintained by the above-described closed loop feedback control or by controlling the temperature and vapor pressure of the precursor gas in the vessel 31 by adjusting the heaters 44 and 45.

[0028] TiI ₄ is widely available in 99.99% purity. It is about 15
It is a purple-black solid at ambient temperature (18-22 ° C.) with a melting point of 0 ° C. and is moisture-sensitive. As shown in FIG. 1, the solid TiI ₄ precursor material 40 comprises
A cylindrical corrosion-resistant metal container 3 which maximizes the effective surface area of the precursor material.
It is enclosed in 1. Vapor from the TiI ₄ was delivered directly, ie, without the use of a carrier gas, in a high conductance delivery system to the reaction chamber 11. Reaction chamber 11 is at least about 100 ° C. to prevent condensation of deposition by-products.
Was heated to the temperature. In order to precisely control the thickness of the deposited film, it was desired not to use a carrier gas.

The TiI ₄ controlled directly delivered to the reaction chamber of the steam is greater than about 3 Torr, preferably in order to obtain a higher 5 torr sufficient vapor pressure, about the TiI ₄ precursor solid 180-190 Achieved by heating to a temperature in the range of ° C. This pressure maintains a constant pressure drop across the orifice defined in the high conductance delivery system while simultaneously providing up to about 50 sccm to the process chamber operating in the range of about 0.1 to 2.0 Torr. Required to deliver the TiI ₄ precursor. The temperature to obtain this pressure was about 185 ° C. for TiI ₄ .

When the drive electrode was a gas delivery showerhead and the susceptor 22 or step on the wafer, ie substrate 23, was at RF ground, a parallel plate RF discharge was used. TiI ₄ vapor was allowed to combine with process gas comprising from about 300 to 500 ° C. Ammonia above the substrate being heated to a temperature of (NH _3). As process gases, argon (Ar), nitrogen (N ₂ ), hydrogen (H ₂ ) and helium (H
e) could be used either alone or in combination.

The deposition requirements for a TiN film from a TiI ₄ precursor are as follows. To ensure the integrity of the underlying material on the substrate, ie, wafer 23, the deposition temperature must be less than about 650 ° C. To be able to achieve an acceptable throughput, the deposition rate must be higher than about 300 ° per minute. The chamber pressure can be varied to obtain the desired film thickness.
For example, at 3000 sccm NH ₃ and 25 sccm TiI ₄ and no carrier gas, at a wafer temperature of about 550 ° C., about 2.
A pressure of 0 torr provides a deposition rate in the range of about 500-600 ° per minute. Under these same conditions, a pressure of about 1.5 Torr provides a deposition rate of about 300 ° per minute, and a pressure of about 1.0 Torr provides a deposition rate of about 150 ° per minute. The deposited film must have low stress, measured as force per unit area. The film stress must be less than about 1 × 10 ¹⁰ dynes / cm ² , in which case the crack formation threshold is higher than about 2000 °. The electric resistivity of the deposited film is about 250μΩ
cm. The film has a 100 aspect ratio in high aspect ratio structures.
% Consistency should be indicated. The high aspect ratio structure used in the present invention is:
Include structures having aspect ratios greater than 8.0 and up to 10.0 or even greater. The features can be vias, holes, trenches, etc. There should be no erosion or corrosion in subsequently deposited films, such as aluminum (Al) films. Impurities in the film should be minimal, ideally less than about 2 atomic percent. Finally, He, Ar, a process gas such as H ₂ and N ₂ should be used industrially at reasonable amount.

Preferred ranges for the deposition of CVD TiN films are given in Table 2, where the preferred conditions are shown in parentheses. Slm is standard liters per minute and W / cm ² is watts per square centimeter.

[0033]

The TiN films deposited by CVD from the TiI ₄ precursor according to the present invention meet all the desired criteria; they show no erosion on the subsequently deposited Al layer, and 10.0 100% consistency in features with even greater aspect ratios. Higher deposition temperatures resulted in lower resistivity, lower residual iodine concentration and higher deposition rates, without sacrificing integrity or cracking threshold.

A TiN film deposited according to the present invention using a TiI ₄ precursor has a higher crack formation threshold than a TiN film deposited using another titanium halide precursor such as TiCl ₄ . FIG. 2 is a graph comparing stresses of TiI ₄ -based and TiCl ₄ -based TiN films, that is, crack formation. Circles are 580 from TiCl ₄ precursor
Figure 2 shows a TiN film deposited at ° C. Triangles indicate TiN films deposited at 550 ° C. from TiI ₄ precursor. The arrow indicates the point where crack formation was observed in the TiCl ₄ film.
Dyne / cm ² with a small increase in film thickness measured in Angstroms (Å)
The sharp drop in film stress measured in step (1) corresponds to the formation of extensive cracks.

As shown in FIG. 2, TiCl ₄ -based films show a rapid drop in film stress for thicknesses less than about 1000 °. Scanning electron micrographs (SEM) of TiN films deposited using TiCl ₄ -based precursors showed extensive crack formation in films greater than about 600 °. No evidence of crack formation was observed at any point in the TiI ₄ film having a thickness greater than 4000 °. FIG. 3 shows a 2000 ° crack free TiI ₄ filled and deposited trench according to the present invention.
It is a scanning electron microscope photograph (SEM) of a system TiN film. The TiN layer 60 is deposited on the silicon dioxide layer 62 at 2000 °.

The TiN film deposited using the TiI ₄ precursor has a higher crack formation threshold 1
One reason is that the grain size in the film is such that the TiCl ₄ precursor deposited Ti
This is inherently smaller than the N film. A film composed of a matrix of small grains has a smaller size than a film composed of larger TiN grains.
It seems to suppress crack growth. FIG. 4 is a transmission electron micrograph (TEM) of a TiN film deposited by CVD using a TiI ₄ -based and TiCl ₄ -based precursor at 550 ° C. and 580 ° C. according to the present invention, respectively. As shown in FIG. 4, the TiI ₄ -based film has substantially smaller crystal grains. This smaller crystal grain is a possible reason for the excellent crack formation threshold of the TiI ₄ -based TiN film.

As shown in FIGS. 5 and 6, in structures with high aspect ratio features, film integrity was dependent on process pressure when all other process conditions were identical. . These conditions were as follows: temperature 550 ° C.,
Flow 3slm and TiI ₄ flow 25sccm of NH _3. FIG.
5 is a SEM of a 10: 1 aspect ratio structure filled with TiN deposited at a pressure of 5 Torr. FIG. 6 is a SEM of a 10: 1 aspect ratio structure filled with TiN deposited by CVD at a pressure of 1.0 Torr.

For high aspect ratio structures, a very highly saturated process is required to form good plugs without “keyholes”. The "keyhole" effect occurs when TiN deposited in a via to form a contact plug does not completely fill the via, leaving an area referred to as a keyhole that does not contain TiN. The effect is that the vias are substantially vertical walls,
That is, it occurs when it has a wall that is substantially perpendicular to the base. In vias with sloping walls, the keyhole effect disappears. For filling these structures, 3 sl
while maintaining a gas flow rate of NH ₃ m and 25 sccm TiI ₄ .
It was observed that low process pressures of less than 5 Torr were required. A good plug filling process is possible at lower flow rates, but only at the expense of deposition rate. Conversely, higher deposition rates are possible with flow rates greater than those listed in Table 2.

FIG. 7 shows contact resistance data for an electrical test structure. Ti and TiN plugs (filled circles) deposited from a TiI ₄ precursor according to the present invention are filled with typical Ti / TiN and W fills using the TiI ₄ precursor (open circles). Circle). The contact dimensions were 0.3 μm and the aspect ratio was 4: 1. As shown in FIG. 7, when filling the contact plug, replacement of the normal Ti, TiN and W layers with Ti and TiN results in equivalent contact resistance. This suggested that the increase in bulk material resistivity from W to TiN was more than compensated for by the decrease in the number of metal interfaces.

Thus, the plug filling process from TiI ₄ is a viable solution as an alternative to the currently used W plug in the formation of IC devices.
The contact resistance is the same with the present invention as it is with a standard W plug.
This is 1% higher than that of W in which the bulk resistivity of TiN is 10 μΩcm.
Considering that it is 5 to 20 times larger, it is worth noting. This emphasizes the advantages of a single process and a reduced number of interfaces in the plug.

The films deposited by the method of the present invention exhibit important properties for IC formation. This film has a low enough electrical resistivity for low wiring impedance, the deposition rate is sufficient for throughput considerations (greater than 100 ° / min), and the film is less than 0.3 μm without crack formation. It can be deposited with a large thickness. The method of the present invention can be used to fill features with aspect ratios greater than 10: 1, as small as 0.15 μm in diameter.

It is understood that the embodiments of the invention shown and described herein are only those preferred by the inventor skilled in the art and are not limiting in any way. Should. For example, each is disclosed in the following applications,
A Ta film can be deposited by PECVD and a TaN _x film can be
D, can be deposited by PECVD and plasma processing thermal CVD (PTTCVD): Tokyo Electron, a pending application filed on even date herewith, which is expressly incorporated by reference herein in its entirety. "PECVD of tantalum halide precursor to Ta film", "Thermal CVD of TaN film from tantalum halide precursor", "Halogenation", all of which are transferred to Hautala and Westen-doped inventions. PECV of TaN film from tantalum precursor
Plasma treatment / thermal CVD of TaN film from tantalum halide precursor
". Further, although the disclosed respective application below, Ta / TaNx two layers can be deposited this with CVD, also TaN _x can be used for plug fill according to the present invention by: the same day as the present application A pending application filed in
"Integration of CVD Ta and TaN _x films from tantalum halide precursors, both transferred to Tokyo Electron and both invented as Houtara and Westen-doped, which are hereby expressly incorporated by reference herein in their entirety.
)) And "Formation of CVD TaN _x plugs from tantalum halide precursors"
. Accordingly, various changes, modifications, or alterations may be made to these embodiments without departing from the spirit of the invention and the scope of the appended claims, or rely on such alterations, modifications, or alterations. Can be.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus for chemical vapor deposition (CVD).

FIG. 2 is a graph comparing stresses in titanium halide (TiX) -based titanium nitride (TiN) films.

FIG. 3 is an SEM photograph of a titanium tetraiodide (TiI ₄ ) -based TiN film.

FIGS. 4A and 4B are transmission electron micrographs of a Ti halide-based TiN film.

FIG. 5 is filled with TiN deposited by CVD at a pressure of 1.5 Torr.
It is a SEM photograph of the structure of 0: 1 aspect ratio.

FIG. 6 is filled with TiN deposited by CVD at a pressure of 1.0 Torr.
It is a SEM photograph of the structure of 0: 1 aspect ratio.

FIG. 7: Filled with TiN deposited by CVD at a pressure of 1.0 Torr.
It is a SEM photograph of the structure of 0: 1 aspect ratio.

[Explanation of symbols]

 Reference Signs List 10 Chemical vapor deposition (CVD) system 11 CVD reaction chamber 12 Precursor delivery system 13 Precursor gas supply source 14 Gas outlet 15 Metering system 16 Gas inlet 20 Vacuum chamber 21 Chamber wall 22 Susceptor 23 Substrate 24 Vacuum pump 25 Inlet gas supply 26 Reducing gas supply source 27 Inert gas supply source 28 Shower head 30 Evaporator 31 Cylindrical evaporation container 33 Cylindrical wall 34 Inner surface 35 Bottom 36 Cover 37 Flange ring 38 Metal seal 39 Carrier gas supply source 40 Precursor 42 Surface 44 , 45 heater 47 can 48 annular insulating layer 50 delivery pipe 51 baffle plate 52 orifice 53 control valve 54 shutoff valve 55, 56, 57, 58 pressure sensor 60 controller 61 non-volatile memory 60 TiN layer 62 silicon dioxide layer

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission Date] March 28, 2001 (2001. 3.28)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Contents of correction]

[0010] Journal of the Electrochemical Society, March 1997, Electrochem. S
oc. USA, Vol. 144, No. 3, pp. 1002-1008, XP0009386.
Fartemire C. 72 ISSN: 0013-4651. (Faltemeier C.
) Disclose a method of forming a TiN film that can be used for step coverage, such as "barrier properties of a titanium nitride film grown by low-temperature chemical vapor deposition from titanium tetraiodide". The method involves applying TiI ₄ to the reaction zone with a H ₂ carrier gas at a flow rate of 30 sccm. TiI ₄ is ammonia and 0.3 torr (39.
At a reactor pressure of 97 N / m ² ). The use of a carrier gas for this precursor is one feature of other known film forming methods.

[Procedural Amendment] Submission of translation of Article 34 Amendment of the Patent Cooperation Treaty

[Submission date] June 26, 2001 (2001.6.26)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0010

[Correction method] Change

[Contents of correction]

[0010] Journal of the Electrochemical Society, March 1997, Electrochem. S
oc. USA, Vol. 144, No. 3, pp. 1002-1008, XP0009386.
Fartemire C. 72 ISSN: 0013-4651. (Faltemeier C
")," A barrier property of a titanium nitride film grown by low-temperature chemical vapor deposition from titanium tetraiodide "discloses a method of forming a TiN film that can be used for step coverage. The method involves applying TiI ₄ to the reaction zone with a H ₂ carrier gas at a flow rate of 30 sccm. TiI ₄ is 0.3 torr (39
. At a reactor pressure of 97 N / m ² ). The use of a carrier gas for this precursor is one feature of other known film forming methods. This leads to the problem that unwanted particulates may be added and hinders accurate metering of the precursor.

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SUMMARY OF THE INVENTION In accordance with the principles of the present invention, a method of providing a conformable seamless titanium nitride (TiN) plug in a high aspect ratio feature of a substrate in a reaction chamber comprises the steps of: Heating the precursor vapor to a temperature in the range of 0.degree. C. and heating the precursor to a temperature sufficient to vaporize the titanium tetraiodide precursor without using a carrier gas. Into the chamber at a flow rate in the range of about 5-40 sccm.
applying a pressure of less than m ² ) and then combining the vapor with a nitrogen-containing process gas to deposit the TiN by chemical vapor deposition.

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Preferably, a titanium tetraiodide (TiI ₄ ) precursor is deposited by thermal CVD.

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[Claims]

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventors Westen Dope, Johnny's, F, M Massachusetts, United States of America, Rockport, Woodbury Lane 9 (72) Inventors Nemoto, Takenoo, Arizona, United States of America, Phoenix, Number 1108 Es, Forty fourth street 13820 F term (reference) 4K030 AA02 AA13 BA18 BA38 FA10 JA01 JA05 JA09 JA10 LA15 4M104 BB14 BB30 DD45 FF13 FF21 FF22

Claims (16)

[Claims] 1. A method of filling a feature in a substrate having a deposited titanium (Ti) film therein, comprising: depositing a vapor of a Ti halide precursor in a reaction chamber containing the substrate. By heating the precursor to a temperature sufficient to vaporize it, and then combining the vapor with a process gas containing nitrogen to deposit titanium nitride (TiN) by a chemical vapor deposition (CVD) process. The Ti
The above method comprising the step of depositing N. 2. The method of claim 1, wherein the features have an aspect ratio greater than 8.0. 3. The method of claim 1, wherein the features have a diameter of less than about 0.16 μm. 4. The method according to claim 1, wherein the titanium halide precursor is titanium tetraiodide (TiI ₄ ). 5. The method according to claim 4, wherein the substrate is heated to a temperature in the range of about 400-650 ° C. 6. The precursor delivery in the range of about 5 to 40 sccm.
The described method. 7. The method of claim 4, wherein the TiN is deposited at a rate in the range of about 100-600 ° / min. 8. The method of claim 1, wherein the nitrogen-containing gas is ammonia. 9. The method according to claim 8, wherein the flow rate of ammonia is about 3 slm. 10. The method according to claim 1, wherein the chemical vapor deposition method is a thermal CVD method. 11. A method of providing a compatible seamless titanium nitride (TiN) plug into a high aspect ratio feature of a substrate in a reaction chamber, the method comprising: depositing titanium tetraiodide precursor vapor into the chamber. Applying a pressure of less than 1.5 Torr into the chamber while providing a temperature sufficient to evaporate and then combining the vapor with a process gas containing nitrogen at a flow rate in the range of about 5-40 sccm; The above method comprising the step of depositing the TiN by a chemical vapor deposition method. 12. A substrate comprising a high aspect ratio feature filled with a conformable seamless TiN film deposited on a Ti film from a Ti halide precursor, wherein the TiN film is about 1-15 × 10 ^9. Such a substrate, which can withstand stress in the range of dynes / cm ² and has a resistivity in the range of about 85-400 μΩcm. 13. The substrate of claim 12, wherein the TiN film has a thickness of at least 4000 °. 14. The substrate of claim 12, wherein the TiN film has no more than about 2 atomic percent of impurities. 15. The method according to claim 12, wherein the Ti halide precursor is titanium tetraiodide.
The substrate as described. 16. The Ti halide precursor heats the precursor to a temperature sufficient to vaporize the precursor, then combines the vapor with a process gas containing nitrogen, and deposits TiN on the substrate. 13. The substrate of claim 12, wherein said substrate is provided to said reaction chamber containing said substrate by chemical vapor deposition.