JP4012090B2 - Method for depositing refractory metal nitride film and method for manufacturing semiconductor device - Google Patents

Description

[0001]
[Industrial application fields]
  The present inventionMethod of depositing refractory metal nitride film andMore particularly, the present invention relates to a method for manufacturing a semiconductor device, and includes a step of growing a refractory metal nitride serving as a barrier metal material interposed between a semiconductor layer and a wiring.Method of depositing refractory metal nitride film andThe present invention relates to a method for manufacturing a semiconductor device.
[0002]
In recent years, there has been a demand for higher density in semiconductor devices. In a semiconductor substrate, a diffusion layer is thinned and wirings are multilayered. Therefore, in order to prevent the electrode metal from entering the diffusion layer, improve the adhesion of the electrode, and prevent the hillock of the electrode, the refractory metal nitride is used as the electrode underlayer or the electrode surface layer. Barrier metal is used.
[0003]
[Prior art]
In the case of forming a barrier metal serving as a base of a wiring layer, a thermal chemical vapor deposition (CVD) method using a refractory metal halide gas and ammonia gas has been widely studied.
[0004]
For example, TiCl_Four And NH_Three The growth temperature at which good step coverage is obtained is 650 ° C. or higher when TiN as a barrier metal is formed by a thermal CVD method using a reactive gas.
[0005]
In this case, chlorine remains in the barrier metal and causes high resistance, so that a growth temperature higher than 600 ° C. is required to remove chlorine. The details are described in, for example, the following three documents.
[0006]
▲ 1 ▼ MJ Buiting, AF Otterloo, and AH Montree, J. Electrochem. Soc., VOL.138, No.2, Feb. 1991, ▲ 2 ▼ IJ Raaijmakers and A. Sherman, Proc. VMIC, Santa Clara, June 1990, (3) E. 0. Travis, WM Paulson, F. Pintchovski, B. Boeck, LC Parillo, ML Kottke, KY Yu, MJ Rice, JB Price, and EC Eichman, IEEE IEDM Tech. Dig., 47 ( 1990)
TiCl_Four And NH_Three The following reactions occur even at room temperature.
[0007]
TiCl_Four + NH_Three → TiCl_Four ・ N NH_Three
The following reaction also occurs in the high temperature region where TiN can grow, and NH_FourCl precipitates in the cold place of the reaction chamber.
[0008]
TiCl_Four + NH_Three → TiN + HCl + N₂ , NH_Three+ HCl → NH_FourCl
TiCl_Four ・ N NH_Three And NH_FourSince Cl is a solid at room temperature, if it adheres to the inner wall of the chamber, it will cause particles. In order to sublimate this, the inner wall of the chamber of the CVD apparatus must be heated to 120 ° C. or higher. However, if a mechanism for heating the chamber is provided, the CVD apparatus becomes larger and the amount of electricity used increases.
[0009]
In contrast, TiCl as a reactive gas_Four And N₂There is also a method of growing TiN by ECR (Electron Cyclotron Resonance) -CVD method, but the growth temperature becomes very high, and facilities for generating μ waves and ECR are complicated and large, and the cost is high. . The growth method is reported in the following literature.
[0010]
(4) T. Akahori and A. Tanihara, Extended Abstracts Solid State Devices and Materials, 180 (1991)
[0011]
[Problems to be solved by the invention]
However, when the TiN barrier metal is grown at such a high temperature as described above, the multilayer wiring structure after the aluminum wiring has a problem that aluminum melts or causes hillocks in the aluminum wiring.
[0012]
On the other hand, TiN can be grown at a growth temperature of 450 ° C. or less by thermal CVD or photo CVD using an organic titanium source. However, TiN obtained by this method has poor step coverage and high It is a resistive film. This is described in the following documents.
[0013]
▲ 5 ▼ IJ Raaijmakers, RN Vrtis, GS Sandhu, J. Yang, EKBroadbent, DA Toberts, and A. Lagendijk, June 9-10, 1992 VMIC Conf., ▲ 6 ▼ KazuyaISHIHARA et al., JAPANESE JOURNAL OF APPLIED PHYSICS VOL.29, No.10, Oct. 1990, ▲ 7 ▼ KOICHI IKEDA et al., 1990 Symposium on VLSI Technology
On the other hand, it is known that when a barrier metal made of a refractory metal nitride is formed directly on a semiconductor substrate, they do not contact well, and it is necessary to interpose a contact metal between them. This is described in the following document.
[0014]
▲ 8 ▼ C. Y. TiNG AND M. WITTMER, Thin Solid Films, 96 (1982) 327-345, ELECTRONICS AND OPTICS
When the contact metal is formed, the natural oxide film must be removed without growing. However, at present, after removing the natural oxide film with a mixed solution of hydrofluoric acid and pure water, a contact metal is formed using a sputtering apparatus, and then a barrier metal is formed using a CVD apparatus. The semiconductor wafer is moved out in the air for each different process.
[0015]
However, since there is no technique for performing such a series of processes without releasing the reduced pressure state, the natural oxide film is not completely removed when the contact metal is formed, and contact failure is likely to occur.
[0016]
  The present invention has been made in view of such a problem, and forms a refractory metal nitride serving as a barrier metal of a wiring at a low temperature and a low resistance, and in the reaction product chamber during film growth. In addition to preventing adhesion, the process from removal of the native oxide film to the growth of contact metal and barrier metal can be performed under reduced pressure.Method of depositing refractory metal nitride film andAn object is to provide a method for manufacturing a semiconductor device.
[0017]
[Means for Solving the Problems]
  The above-described problem is achieved by using a source gas containing a refractory metal and an alkylamino compound that reduces and nitrides the source gas as a reducing gas and a nitrogen source,Refractory metal nitride filmThis is achieved by a method for manufacturing a semiconductor device, including a step of forming the layer by chemical vapor deposition.
[0019]
Alternatively, the refractory metal nitride film is formed by placing the refractory metal nitride film at a temperature of 300 to 500 ° C.
[0020]
Alternatively, this is achieved by the method for manufacturing a semiconductor device, wherein the content of the refractory metal in the refractory metal nitride film is 60% or more.
[0021]
  Alternatively, the refractory metal nitride film is formed on the upper surface of the silicon layer, and the refractory metal nitride film is placed at a temperature of 450 ° C. or higher so that the refractory metal nitride film is interposed between the refractory metal nitride film and the silicon layer. This is achieved by a method for manufacturing a semiconductor device including a step of forming a layer. OrUsing a source gas containing a refractory metal and an alkylamino compound that reduces and nitrides the source gas as a reducing gas and a nitrogen source, a refractory metal nitride film is deposited.This is achieved by a method of depositing a refractory metal nitride film characterized by the above. OrThe source gas containing the refractory metal is a gas having an alkylamino compound or a cyclopentadienyl compound of the refractory metal.This is achieved by a method of depositing a refractory metal nitride film characterized by the above.
[0022]
[Operation]
According to the present invention, when the wiring electrode in contact with the silicon layer is formed, the refractory metal silicide film is provided under the refractory metal barrier metal. When the refractory metal silicide film is interposed between the silicon layer and the wiring layer, the contact with the barrier metal is improved.
[0023]
Further, according to the present invention, when growing a refractory metal nitride such as TiN as a barrier metal, NH is used as a reducing gas and a nitriding source._Three Instead, a gas containing any one of an alkyl aminated compound, an alkyl azide compound, a hydrazine, and a hydrazine alkyl compound is used.
[0024]
According to this, a barrier metal made of a refractory metal nitride is grown at a low temperature that does not cause melting or hillocks in the lower layer wiring of aluminum. Further, when the refractory metal nitride is generated, a product that becomes a solid at normal temperature is not generated by the reaction, and deposition of a product causing particles on the inner wall of the chamber is suppressed. Moreover, NH as a reducing gas and nitriding source_Three As compared with the case of using only the refractory metal, the chlorine content in the refractory metal nitride film is reduced, and corrosion of the aluminum film for the wiring electrode formed thereon is suppressed._Four Even when Ti is used as a Ti source, the coverage is good and the specific resistance is also small.
[0025]
Further, when refractory metal silicide is formed on the surface of the silicon layer as the contact metal, the content of the refractory metal in the refractory metal nitride film formed on the silicon layer is set to 60% or more, and thereafter By this heat treatment, a refractory metal silicide is grown between the refractory metal nitride film and the silicon layer. Therefore, it is not necessary to introduce polycide when growing the refractory metal silicide, and the throughput is improved.
[0026]
The above-described refractory metal nitride is similarly applied to the case where a hole formed in the insulating film is buried.
[0027]
【Example】
An embodiment of the present invention will be described below with reference to the drawings.
(A) Description of First Embodiment of the Invention FIG. 1 is a schematic configuration diagram showing a thermal chemical vapor deposition (thermal CVD) apparatus used for growth of a barrier metal according to the first embodiment of the present invention.
[0028]
This thermal CVD apparatus includes a chamber 1 for growing a film, a mounting table 2 for mounting a semiconductor substrate with a built-in heater, and a first gas inlet 3 for introducing a source gas into the chamber 1. And a second gas inlet 4 for introducing a reducing gas into the chamber 1 and an exhaust port 5 connected to an exhaust mechanism (not shown) for exhausting the gas in the chamber 1.
[0029]
Next, a process of forming TiN as a barrier metal on a semiconductor substrate using the above-described thermal CVD apparatus is shown in FIGS. 2 (A) to 2 (D) and FIGS. 3 (A) to 3 (C). The description will be given with reference.
[0030]
Prior to the description of the growth of the barrier metal, the semiconductor substrate before the barrier metal is formed and the laminated structure thereon will be described.
[0031]
FIG. 2A is a cross-sectional view showing a state where a contact hole is formed in the interlayer insulating film covering the MOSFET.
[0032]
On the upper surface of the semiconductor substrate 11 made of p-type silicon, SiO 2₂A field oxide film 12 is formed to a thickness of 6000 mm by selective thermal oxidation. A MOSFET is formed in a region surrounded by the field oxide film 12. The MOSFET is an SiO film having a thickness of about 100 mm formed on the surface of the semiconductor substrate 11 by thermal oxidation.₂A gate electrode 14 made of a polysilicon film having a thickness of about 2000 mm grown thereon by a CVD method, and an n formed on the semiconductor substrate 11 on both sides of the gate electrode 14 by an ion implantation method. + Type S / D region layers 15a and 15b.
[0033]
The S / D region layers 15a and 15b are formed by, for example, applying arsenic (As) to the semiconductor substrate 11 at a dose amount of 4 × 10.¹⁵/ cm² , With an acceleration energy of 30 KeV, and the region is activated at 850 ° C.
[0034]
Further, the gate electrode 14, the S / D region layers 15a and 15b, and the field oxide film 12 are covered with an inter-layer insulating film 16 made of a silicon oxide film having a thickness of 5000 mm, and are formed on the S / D region layers 15a and 15b. Contact holes 17a and 17b are formed.
[0035]
The semiconductor substrate 11 on which such a MOSFET is formed is mounted on the mounting table 2 of the CVD apparatus, and the temperature of the semiconductor substrate 11 is 600 ° C. or less, preferably 300 ° C. to 500 ° C. by the heater inside the mounting table 2. And heat to maintain the state. Further, the gas in the chamber 1 is exhausted through the exhaust port 5 and the inside thereof is decompressed.
[0036]
And Ti (N (CH_Three)₂)_FourN as carrier gas in liquid₂Gas was bubbled at a flow rate of 10 sccm, and Ti (N (CH_Three)₂)_FourAnd N₂ The mixed gas is introduced into the chamber 1 from the first gas inlet 3 as a source gas. At this time, the partial pressure of the source gas is about 40 mTorr, of which about 10 mTorr is Ti (N (CH_Three)₂)_FourIs the partial pressure.
[0037]
Also, dimethylhydrazine ((CH_Three)₂NNH₂) A gas is introduced into the chamber 1 from the second gas inlet 4 at a flow rate of 10 to 100 sccm. (CH_Three)₂NNH₂Since it has a vapor pressure of about 150 Torr at room temperature (25 ° C.), it is supplied directly using an MFC (Mass Flow Controller).
[0038]
When such gas is introduced, the gas exhaust amount is adjusted to maintain the internal pressure of the chamber 1 at several tens mTorr to 1 Torr.
[0039]
H₂A carrier gas such as 10 may be introduced at a flow rate of about 10 to 1000 sccm. According to this, the role of assisting the reduction is fulfilled, but it is not indispensable.
[0040]
According to such conditions, in the chamber 1, (CH_Three)₂NNH₂Is activated and Ti (N (CH_Three)₂)_FourReacts with TiN and CH_Four (Gas) and H₂(Gas) is generated. Thereby, TiN as a reaction product is deposited along the upper surfaces of the S / D region layers 15a and 15b, the inner peripheral surfaces of the contact holes 17a and 17b, and the upper surface of the interlayer insulating film 16, and the remaining CH_Four And H₂Becomes a gas at normal temperature and is exhausted from the exhaust port 25.
[0041]
This state is maintained for a predetermined time, and as shown in FIG. 2B, a TiN film 18 that is a refractory metal nitride is formed on the semiconductor substrate 11 to a thickness of about 400 mm.
[0042]
Next, as shown in FIG. 2C, an Al film 19 is deposited on the TiN film 18 by a PVD method such as sputtering to a thickness of about 5000 mm. Subsequently, the two-layer film of the TiN film 18 and the Al film 19 is patterned using the same mask to form S / D electrodes 20a and 20b drawn from the S / D region layers 15a and 15b.
[0043]
Subsequently, as shown in FIG. 2D, after forming an interlayer insulating film 21 such as PSG, via holes 21a and 21b are formed on the S / D electrodes 20a and 20b.
[0044]
Next, as shown in FIGS. 3A and 3B, a TiN film 22 having a film thickness of about 400 mm and an Al film having a film thickness of about 5000 mm are formed by the same formation method as the TiN film 18 and Al film 19 described above. 23 bilayer films are formed.
[0045]
Subsequently, as shown in FIG. 3C, the TiN film 22 and the Al film 23 are patterned by lithography to form Al wiring layers 24a and 24b connected to the S / D electrodes 20a and 20b. Thereafter, although not particularly illustrated, a wiring pad, a protective insulating film, and the like are formed to complete the semiconductor device.
[0046]
  As described above, in the first embodiment of the present invention, Ti (N (CH₃)₂)₄As the reducing and nitriding gas for the source gasHydrazine alkyl compounds(CH₃)₂NNH₂A TiN film 18 is formed on the substrate by a CVD method using a gas-containing material.
[0047]
At this time, in addition to TiN as a reaction product, only an alkyl compound, nitrogen and hydrogen gas that are in a gaseous state at room temperature are generated._Four And NH_Three NH, which becomes solid at room temperature, as in the conventional technology using_FourNothing like Cl is produced. CH_FourGas or H₂Since the gas is exhausted from the exhaust port 5 of the chamber 1, unnecessary reaction products are not deposited on the inner wall of the chamber 1, and it is not necessary to add a heater or the like for sublimating the reaction products to the CVD apparatus.
[0048]
In addition, by using the source gas and the reducing gas as described above, activation can be performed both thermally and at about 300 ° C., and the film forming temperature can be greatly lowered from the conventional 600 ° C. or higher. As a result, the thermal strain generated between the TiN film 22 and the Al films 19 and 23 formed above and below it is suppressed, and it is difficult for the S / D electrodes 20a and 20b and the Al wirings 24a and 24b to melt or hillock. Become.
[0049]
In the above description, as the source gas, Ti (N (CH_Three)₂)_FourBut Ti (N (C₂H_Five)₂)_Four It may be. Other source gases containing Ti include Ti (i-OC_ThreeH₇)_Four, Ti (t-OC_FourH₉)_FourAlkoxides such as TiCl_Four , TiCl_Three , TiCl₂ , TiF_FourGas containing halides such as Cp₂Ti (N_Three)₂, Cp₂A gas containing a cyclopentadienyl compound such as Ti may be used.
[0050]
However, Cp which is cyclopentadienylated product₂Ti (N_Three)₂, Cp₂Since Ti and the like are usually solid at ordinary temperature, they are sublimated at a temperature of about 200 ° C. and used after being gasified.
[0051]
Of these chemical formulas, i represents iso and t represents tarsal. Cp represents a cyclopentadienyl group, and Cp_FiveH_FiveIs abbreviated.
[0052]
Furthermore, as reducing gas, (CH_Three)₂NNH₂, (CH_Three) HNNH₂Besides, CH_ThreeNH₂, (CH_Three)₂NH, (CH_Three)_ThreeN, (C₂H_Five)₂NH, (C₂H_Five)_ThreeN, CH_ThreeNHNH₂, C₆H_FiveNHNH₂ Alkylamino compounds such as In addition, hydrazine N₂H_FourOr a gas containing an alkyl compound of hydrazine may be used. The hydrazine alkyl compound has the above-described (CH_Three) HNNH₂, (CH_Three)₂NNH₂Etc. Furthermore, alkyl azide compounds are also possible and (CH_Three) N_Three(C₂H_Five) N_ThreeEtc. These reducing gases also act as a nitriding source.
[0053]
In this embodiment, TiN is used as the barrier metal, but tungsten (W) or molybdenum (Mo) nitride may be used as the other refractory metal nitride. The source gas in this case is an alkyl amination product, alkoxide compound, halide, or cyclopentadienylation product of these refractory metals.
[0054]
Next, TiCl as source gas_Four And methylhydrazine ((CH_Three) HNNH₂Hereinafter, the film formation speed, specific resistance, chlorine concentration, and step coverage when using MH will be described. As a test, the pressure in the chamber was 100 mTorr, and TiN was grown in a temperature range of 400 to 700 ° C. FIG. 4 shows the case where MH is used as the reducing agent, and NH_Three The growth rate when using is shown.
[0055]
The growth rate of TiN by MH reduction is NH_Three A growth rate of 800 Å / min was obtained when the growth temperature was 400 ° C. with an MH flow rate of 10 sccm, which was an order of magnitude higher than the reduction. From this, the reactivity of MH reduction is NH_Three It can be seen that it is very high compared to reduction.
[0056]
Further, when the crystal structure of TiN grown by MH reduction was examined by X-ray diffraction, a typical NaCl type TiN crystal grew and preferentially oriented in the (200) plane, and the grain size of the crystal was 200. It was found to be ~ 260cm. SiO₂TiN grew on the film and preferentially oriented in the (200) plane. In addition, when forming on the Ti film by PVD method, it preferentially orients to the (111) plane.
[0057]
FIG. 5 shows the relationship between the specific resistance and the growth temperature. The specific resistance decreased as the growth temperature increased, and TiN grown by MH reduction became 90 μΩ · cm at 500 ° C. NH_Three In order to obtain an equivalent specific resistance by reduction, a high temperature of 700 ° C. or higher is required.
[0058]
FIG. 6 shows the relationship between the chlorine concentration in the TiN film and the growth temperature._Three The chlorine concentration in TiN grown by reduction was 3.3 atomic% at a growth temperature of 500 ° C., whereas TiN grown by MH reduction was 0.18 atomic% at the same growth temperature.
[0059]
As a result, MH gas is TiCl_Four It can be seen that the residual chlorine concentration can be reduced sufficiently. The chlorine concentration decreases with the upper layer of the growth temperature, and considering the results shown in FIG. 5, the specific resistance is considered to decrease as the residual chlorine concentration decreases.
[0060]
When the chlorine concentration is lowered, the corrosion of aluminum formed thereon is reduced. The corrosion is observed after washing with water. Therefore, TiN was formed by MH reduction, an aluminum film was laminated thereon, and after microscopic observation after washing with water, no corrosion of the aluminum surface was observed. In contrast, NH_Three According to the reduction, in order to eliminate corrosion, it is necessary to set the growth temperature to 550 ° C. or higher and reduce the chlorine content.
[0061]
NH_Three When the source gas is reduced by Ti to form TiN, corrosion of aluminum occurs at the interface between the interlayer insulating film and the aluminum film. This is thought to be because chlorine in the TiN film diffuses into the water that permeates into the interface during washing.
[0062]
With regard to step coverage, when TiN produced by MH reduction was grown to a thickness of 1700 mm, it was found that a contact hole of 0.2 μmφ and an aspect ratio of about 2.6 was completely embedded, and the coverage was also good. . It has also been confirmed that the leakage current is as large as before.
[0063]
The above-described refractory metal nitride is similarly applied to the case where a hole formed in the insulating film is buried.
(B) Description of Second Embodiment of the Invention FIG. 7 is a block diagram of a CVD apparatus for forming a refractory metal nitride according to the second embodiment of the present invention.
[0064]
FIG. 7 differs from FIG. 1 in that there is means for applying a high-frequency voltage to the parallel plate electrodes as means for activating the reducing gas.
[0065]
In the reaction chamber 31 of the CVD apparatus, a mounting table 32 for mounting a semiconductor substrate, a gas introduction port 33 for introducing a source gas into the reaction chamber 31, and an exhaust port 35 connected to an exhaust device (not shown) are provided. Have.
[0066]
A plasma chamber 36 is connected on the reaction chamber 31, and these spaces are partitioned by a mesh-like ion trap portion 37 that prevents the plasma from entering the reaction chamber 31.
[0067]
Further, a gas introduction port 34 for introducing a reducing gas is provided inside the plasma chamber 36, and a pair of electrodes 38a and 38b are arranged around the outside thereof, and an electric field is applied between the electrodes. When applied, the reducing gas in the plasma chamber 36 is activated. One electrode 38b is connected to a high-frequency power source 39 for supplying a high-frequency voltage having a frequency of 13.46 MHz, and the other electrode 38a is grounded.
[0068]
Then, a reducing gas introduced into the plasma chamber 36 is activated by applying a high frequency voltage between the two electrodes 38a and 38b. In this case, since the reducing gas is activated by the plasma, the substrate can be sufficiently grown even when the substrate heating temperature by the heater built in the mounting table 31 is 500 ° C. or less.
[0069]
Also in such a CVD apparatus, as in the first embodiment of the present invention, as a source gas containing a refractory metal element, an alkylaminated product, alkoxide product, halide or cyclopentadienylated product of a refractory metal is used. A gas containing an alkylamino compound or an alkyl azide compound, or a gas containing hydrazine or an alkyl compound thereof is used as a reducing agent for reducing the source gas.
[0070]
Due to the reaction between the source gas and the reducing gas, a refractory metal nitride such as TiN and an alkyl compound that becomes gaseous at room temperature, N₂Or H₂Is generated. These gases are exhausted from the exhaust port 35 of the reaction chamber 31 and do not remain on the inner wall of the reaction chamber 31. The TiN is formed on the semiconductor substrate as in the first embodiment, and is used as a barrier metal for wiring.
[0071]
In this embodiment, the source gas and the reducing gas are used, and the reducing gas is activated by the electric field of the high frequency voltage. Therefore, the substrate heating temperature for obtaining TiN is in the range of 300 ° C. to 500 ° C. When the wiring layer is under the electrode, the thermal influence on the lower wiring layer is further reduced, and the occurrence of melt and hillocks in the aluminum wiring is suppressed.
[0072]
Furthermore, NH as a source gas reducing agent_Three Compared with the use of the reducing agent of this example, the film formation rate is higher, the specific resistance is lower, the chlorine concentration is lower, and the step coverage is better. .
(C) Description of the third embodiment of the present invention
FIG. 8 is a block diagram of a CVD apparatus for forming a TiN film according to the third embodiment of the present invention.
[0073]
8 is different from FIG. 1 in that a mercury lamp that irradiates ultraviolet rays is used as means for activating the reducing gas.
[0074]
In the chamber 41 of the CVD apparatus, a mounting table 42 with a built-in heater for mounting a semiconductor substrate on which a film is grown, a gas inlet 43 for introducing a source gas into the chamber 41, and a reducing property in the chamber 41. A gas introduction port 44 for introducing gas, an exhaust port 45 for exhausting the gas in the chamber 41 connected to an exhaust device (not shown), and for irradiating the chamber 41 with ultraviolet rays to activate the reducing gas It has a mercury lamp 46 and a transmission window 47 that is formed in a part of the wall of the chamber 41 and transmits ultraviolet rays from the mercury lamp 45.
[0075]
In this CVD apparatus, the reducing gas and the source gas in the chamber 41 are activated by high energy ultraviolet rays generated when the mercury lamp 45 is turned on. By this ultraviolet irradiation, the substrate heating temperature is sufficient to be 500 ° C. or less.
[0076]
Further, as a source gas containing a refractory metal element introduced into the chamber 41, a gas containing an aluminide, alkoxide, halide or cyclopentadienylate of a refractory metal as in the first embodiment. In addition, as the reducing gas of the source gas, as in the first embodiment, an alkyl azide compound, a gas containing an alkylamino compound, a gas containing hydrazine or an alkyl compound thereof, etc. are used. A refractory metal nitride film to be a barrier metal is formed. This reducing gas also acts as a nitriding gas.
[0077]
In this case, in addition to the refractory metal nitride as the reaction product, an alkyl compound that is gaseous at room temperature, N₂And H₂They do not remain on the inner wall of the chamber 41.
[0078]
Further, since the source gas and the reducing gas are activated by the high-energy ultraviolet rays using the reaction gas and the reducing gas described above, the substrate heating temperature for forming the barrier metal made of TiN is 300 ° C. to 500 ° C. When the temperature range is sufficient, and there is a wiring layer under the barrier metal, the thermal influence on the lower wiring layer is further reduced, and the occurrence of hillocks in the aluminum wiring is suppressed.
[0079]
The film formation rate, specific resistance, chlorine concentration, and coverage are similar to those of the first embodiment, and are optimal as a wiring barrier metal material for semiconductor devices.
(D) Description of the fourth embodiment of the present invention
FIG. 9 is a cross-sectional view showing a manufacturing process of a semiconductor device according to the fourth embodiment of the present invention. In this embodiment, since the CVD apparatus shown in FIG. 1 used in the first embodiment is used, description of the CVD apparatus is omitted.
[0080]
A part of the cross section of the semiconductor substrate before TiN is formed as the barrier metal is in a state as shown in FIG. A field oxide film 12 is formed by a selective oxidation method in a portion surrounding the element formation region on the upper surface of the semiconductor substrate 11 made of p-type silicon, and a gate insulating film 13 and a gate electrode 14 of the MOSFET are formed in the element formation region. S / D region layers 15a and 15b are formed, and contact holes 17a and 17b for exposing the S / D region layers 15a and 15b are formed in the interlayer insulating film 16 covering them.
[0081]
A natural oxide film (SiO 2) is formed on the surfaces of the S / D region layers 15a and 15b exposed from the contact holes 17a and 17b.₂50) is growing.
[0082]
In such a state, the semiconductor substrate 11 is put into the chamber 1 of the CVD apparatus as shown in FIG. 1 and the semiconductor substrate 11 is placed on the mounting table 2. This is followed by a pretreatment process for contact metal formation.
[0083]
First, the inside of the chamber 1 is 1 × 10^-FourAfter reducing the pressure to below Torr, the semiconductor substrate 11 is heated by a heater built in the mounting table 2, and the substrate temperature in a normal temperature state is raised to 400 to 700 ° C.
[0084]
Subsequently, hydrazine (N₂H_Four) Gas is introduced into the chamber 1 at a flow rate of 100 sccm, and the upper surface of the semiconductor substrate 11 is N₂H_FourExposure to a natural oxide film (SiO 2) having a thickness of about 10 mm formed on the surface of the S / D region layers 15a and 15b exposed from the contact holes 17a and 17b.₂) 50 is removed as shown in FIG.
[0085]
The substrate temperature is 400 ° C. and N₂H_FourAlternatively, the natural oxide film 50 can be removed from the substrate even if a hydrazine alkyl compound such as methyl hydrazine (MH) is flowed at a flow rate of 100 sccm for 60 seconds.
[0086]
The natural oxide film 50 is removed in this way because N₂H_FourActive hydrogen radicals dissociated from SiO₂It is thought to be for reducing
[0087]
Next, the process of growing TiSi as a contact metal is started.
[0088]
While heating the temperature of the semiconductor substrate 11 to 400 ° C. to 700 ° C., TiCl_Four Gas 10 sccm, MH gas 5 sccm, Si₂H₆ Gas is introduced into the chamber 1 at a flow rate of 200 sccm, and the pressure in the chamber 1 is set to several tens of mTorr.
[0089]
Under this condition, TiSix grows at a growth rate of about 100 Å / min. By maintaining this state for a predetermined time, the upper surfaces of the S / D region layers 15a and 15b are maintained as shown in FIG. A TiSix film 51 is formed to a thickness of 100 mm along the inner peripheral surfaces of the contact holes 17 a and 17 b and the upper surface of the interlayer insulating film 16. In this case, the TiSix film 51 contains several ppm of nitrogen.
[0090]
Si₂H₆ Besides SiH_Four, Si_ThreeH₈ A polysilane gas such as
[0091]
Next, the process proceeds to a process of growing TiN as a barrier metal for wiring.
[0092]
While heating the semiconductor substrate 11 to 400-500 degreeC, it is TiCl_Four Are introduced into the chamber 1 at a flow rate of 10 sccm and MH at a flow rate of 10 sccm. At this time, the pressure in the chamber 1 is set to 100 m Torr. NH as carrier and nitrogen source_Three 100 sccm may be added.
[0093]
According to this condition, as shown in FIG. 10A, the TiN film 52 having a specific resistance of 100 μΩ · cm or less is formed on the S / D region layers 15a and 15b and the inner peripheral surfaces of the contact holes 17a and 17b. , Formed on the interlayer insulating film 16.
[0094]
The chlorine concentration remaining in the TiN film 52 is NH as a reducing agent._Three Compared to the case of using, it decreased to 1/40. When the density of chlorine increases, the chlorine dissolves in the water during washing and causes corrosion of the Al film laminated on the barrier metal, but if the chlorine concentration drops significantly as in this example, the corrosion The possibility of is almost gone.
[0095]
After laminating such a barrier metal, the semiconductor substrate 11 is taken out from the CVD apparatus, and then, as shown in FIG. 10B, an Al film 53 is laminated to a thickness of about 5000 mm by sputtering.
[0096]
Then, the layers from the Al film 53 to the contact metal 51 are patterned by photolithography to form S / D electrodes 54 and 55. Thereafter, an interlayer insulating film 21 is laminated by a CVD method. Next, as shown in FIG. 10 (C), upper wirings 24a and 24b made of TiN / Al are formed. Details thereof have already been described in the first embodiment, and will be omitted.
[0097]
The reducing gas may be other hydrazine alkyl compounds of MH, N₂H_FourIt may be.
[0098]
According to the process as described above, the process from the step of removing the natural oxide film 50 on the surface of the S / D region layers 15a and 15b to the process of forming the TiN film 52 as a barrier metal is performed in the chamber 1 of the same CVD apparatus. Since the process is performed without breaking the vacuum state, the natural oxide film does not re-grow, and the throughput is improved. In addition, since a series of steps from the removal of the natural oxide film to the formation of the contact metal is performed at a low temperature of 600 ° C. or lower using hydrazine or a hydrazine alkyl compound, thermal strain generated between layers is reduced.
[0099]
When Ti is 60% or more of TiN serving as a barrier metal, Ti-rich TiN is formed at the interface between the silicon surface of the S / D region layers 15a and 15b and the TiN film 52. When annealing is performed for 10 seconds at a temperature of 450 ° C. or higher, for example, 600 ° C. without forming, a TiSix layer is formed at the interface. This eliminates the need for flowing polysilane to form the contact metal.
[0100]
Further, as the reaction gas, a source gas and a reducing gas as shown in the first embodiment may be used.
[0101]
With respect to the film forming speed, specific resistance, chlorine concentration, and coverage in this example, the same results as in the first example are obtained, which is optimal as a barrier metal material for wiring of a semiconductor device.
[0102]
(E) Description of the fifth embodiment of the present invention
In the fourth embodiment, barrier metal formation is performed from natural oxide film removal in one reaction chamber, but natural oxide film removal and metal growth may be performed in separate chambers. An example is shown in FIG.
[0103]
The apparatus has two reaction chambers 61 and 62, and a vacuum transfer chamber 63 for transferring a semiconductor substrate in a reduced-pressure atmosphere is provided between the reaction chambers 61 and 62. The vacuum transfer chamber 63 is connected to a load chamber 64 and an unload chamber 65 for taking in and out the semiconductor substrate, and cassette stations 66 and 67 for storing the semiconductor substrate are connected to them.
[0104]
Note that, between the reaction chambers 61 and 62 and the vacuum transfer chamber 63, between the vacuum transfer chamber 63 and the load chamber 64, between the vacuum transfer chamber 63 and the unload chamber 65, and between the load chamber 64 and the first cassette station 66. Gate valves 67 to 73 are attached between the unload chamber 65 and the second cassette station 67, respectively. These gate valves 67 to 73 are opened and closed when the semiconductor substrate is moved, and the opening and closing thereof is omitted in the following description.
[0105]
Next, the process from the removal of the natural oxide film to the process of forming the barrier metal using the above-described apparatus will be described. In this embodiment, the growth conditions such as the type of gas, the growth temperature, and the growth film thickness are the same as those in the fourth embodiment, and the change in the stacked structure on the semiconductor substrate is as shown in FIGS. become.
[0106]
First, the semiconductor substrate 11 taken out from the first cassette station 66 by a transport system (not shown) is transported to the load chamber 64 and placed in an atmosphere where the pressure is reduced. The reaction chamber 61 is attached. The vacuum transfer chamber 63 and the reaction chamber 61 are in a reduced pressure state.
[0107]
In the first reaction chamber 61, hydrazine or a hydrazine alkyl compound is introduced, and the substrate temperature is set to 400 ° C. to 700 ° C. while the internal pressure is set to 100 mTorr.
[0108]
If this state is maintained for a predetermined time, a natural oxide film (SiO 2) formed on the surface of the S / D region layers 15a and 15b as shown in FIG.₂) 50 is removed.
[0109]
Next, after the semiconductor substrate 11 is taken out from the first reaction chamber 61 by a transfer system (not shown), the semiconductor substrate 11 is transferred into the second reaction chamber 62 through the vacuum transfer chamber 63.
[0110]
In the reaction chamber 62, as in the fourth embodiment, TiCl._Four And MH and Si₂H₆ And the substrate temperature is set to 400 to 600 ° C. Thus, as shown in FIG. 9C, the TiSix film 51 as the contact metal is formed along the inner peripheral surfaces of the contact holes 17a and 17b, the surfaces of the S / D region layers 15a and 15b, and the upper surface of the interlayer insulating film 16. Form.
[0111]
Next, the gas introduced into the second reaction chamber 62 is changed and TiCl is changed._Four And MH are introduced, and the semiconductor substrate 11 is heated to 400 ° C. to 500 ° C., thereby growing a TiN film 52 as a barrier metal as shown in FIG.
[0112]
Thereafter, the semiconductor substrate 11 is transferred from the second reaction chamber 62 to the vacuum transfer chamber 63 by the transfer system (not shown), and then transferred from the vacuum transfer chamber 63 to the unload chamber 65 in a reduced pressure state. Further, after closing the gate valve 73 between the unload chamber 65 and the vacuum transfer chamber 63, the inside of the unload chamber 65 is brought to normal pressure, and then the semiconductor substrate 11 is stored in the second cassette station 67.
[0113]
Thereafter, in the same manner as in the fourth embodiment, as shown in FIG. 10B, an Al film 53 is laminated on the barrier metal film 52 by sputtering, and then contact metal is formed from the Al film 53 by lithography. Patterns up to the film 51 are formed to form S / D electrodes 54 and 55 as shown in FIG.
[0114]
In this embodiment as well, Si is used to form the contact metal.₂H₆ If the Ti content of the TiN film 52 is set to 60% or more without annealing and annealing is performed at a temperature of 450 ° C. or more, a TiSi film between the silicon surface of the S / D region layers 15a and 15b and the TiN film 52 is formed. Will be formed.
[0115]
The source gas and the reducing gas used in this embodiment may be the same as those in the first embodiment, and the same results as in the first embodiment can be obtained with respect to the film forming rate, specific resistance, chlorine concentration, and coverage.
[0116]
【The invention's effect】
As described above, according to the present invention, when the wiring electrode in contact with the silicon layer is formed, the refractory metal silicide film is provided under the refractory metal barrier metal. I can improve my contacts.
[0117]
Further, according to the present invention, when growing a refractory metal nitride serving as a barrier metal, NH is used as a reducing and nitriding gas._ThreeIn addition, a gas containing an alkyl azide compound, an alkylamino compound, a hydrazine, and a hydrazine alkyl compound is used. According to this, when forming an aluminum wiring, a refractory metal nitride can be grown at a low temperature that does not cause melting or hillocks. Further, when the refractory metal nitride is generated, a product that becomes a solid at normal temperature is not generated by the reaction, and deposition of a product causing particles on the inner wall of the chamber can be suppressed. Furthermore, NH as the reducing gas_ThreeCompared to the case of using Ti, the content of chlorine in the refractory metal nitride film is reduced, and corrosion of the aluminum film laminated on the wiring electrode can be suppressed._FourWhen Ti is used as a Ti source, its coverage can be improved and its specific resistance can be reduced.
[0118]
According to another aspect of the present invention, since a natural oxide film is removed by supplying hydrazine or a hydrazine alkyl compound to the surface of the silicon layer in a reduced pressure atmosphere, the CVD film is continuously formed. It is possible to prevent regrowth of the natural oxide film.
[0119]
Furthermore, the removal of the natural oxide film, the growth of the refractory metal silicide film as the contact metal, and the growth of the refractory metal nitride film as the barrier metal are performed without breaking the vacuum state. Throughput can be improved.
[0120]
Furthermore, as a method of forming a refractory metal silicide on the surface of the silicon layer, the content of the refractory metal in the refractory metal nitride film formed on the silicon layer is increased to 60% or more, and a high melting point is obtained by subsequent heat treatment. Since the refractory metal silicide is grown between the metal nitride film and the silicon layer, it is not necessary to introduce polycide when growing the refractory metal silicide, and the throughput can be improved.
[Brief description of the drawings]
FIG. 1 is a configuration diagram of a CVD apparatus used for forming a TiN film according to first and fourth embodiments of the present invention.
FIG. 2 is a cross-sectional view (No. 1) for explaining the method of manufacturing the semiconductor device according to the first example of the invention.
FIG. 3 is a sectional view (No. 2) for explaining the method for manufacturing the semiconductor device according to the first embodiment of the present invention;
FIG. 4 is a characteristic diagram showing the growth rate of the TiN film according to the first embodiment of the present invention and the growth rate of the TiN film by the conventional method.
FIG. 5 is a characteristic diagram showing the specific resistance of the TiN film according to the first embodiment of the present invention and the specific resistance of the TiN film according to the conventional method.
FIG. 6 is a characteristic diagram showing the Cl concentration of the TiN film according to the first embodiment of the present invention and the Cl concentration of the TiN film by the conventional method.
FIG. 7 is a configuration diagram of a CVD apparatus used for forming a TiN film according to a second embodiment of the present invention.
FIG. 8 is a configuration diagram of a CVD apparatus used for forming a TiN film according to a third embodiment of the present invention.
FIG. 9 is a sectional view (No. 1) for explaining a method of manufacturing a semiconductor device according to fourth and fifth embodiments of the present invention;
FIG. 10 is a sectional view (No. 2) for explaining the method of manufacturing the semiconductor device according to the fourth and fifth embodiments of the present invention;
FIG. 11 is a configuration diagram of an apparatus used in processes from removal of a natural oxide film to formation of a barrier metal film according to a fifth embodiment of the present invention.
[Explanation of symbols]
1 chamber
2 mounting table
3, 4 Gas inlet
5 Exhaust port
11 Silicon substrate (semiconductor substrate)
12 Field insulating film
13 Gate insulation film
14 Gate electrode
15a, 15b S / D region layer
16 Interlayer insulation film
17a, 17b Contact metal
18 TiN film (refractory metal nitride)
19 Al film
20a, 20b S / D electrode
21 Interlayer insulation film
21a, 21b Via hole
22 TiN film (refractory metal nitride film)
23 Al film
24a, 24b wiring layer
31 reaction chamber
32 mounting table
33, 34 Gas inlet
35 Exhaust port
36 Plasma chamber
37 Ion trap
38a, 38b electrode
39 AC power supply
41 chamber
42 mounting table
43, 44 Gas inlet
45 Exhaust port
46 Mercury lamp
47 Transparent window
50 Natural oxide film
51 TiSix film (contact metal)
52 TiN film (barrier metal)
53 Al film
54, 55 S / D electrode
61, 62 Reaction chamber
63 Vacuum transfer chamber
64 load chamber
65 Unload chamber
66, 67 cassette station

Claims (8)

Using a source gas containing a refractory metal and an alkylamino compound that reduces and nitrides the source gas as a reducing gas and a nitrogen source, and forming a refractory metal nitride film by chemical vapor deposition. A method for manufacturing a semiconductor device. The method for manufacturing a semiconductor device according to claim 1 , wherein the refractory metal nitride film is formed by placing the refractory metal nitride film at a temperature of 300 to 500 ° C. 2. The method of manufacturing a semiconductor device according to claim 1 , wherein the content of the refractory metal in the refractory metal nitride film is 60% or more. The refractory metal nitride film is formed on the upper surface of the silicon layer, and the refractory metal nitride film is placed at a temperature of 450 ° C. or higher to form a refractory silicide layer between the refractory metal nitride film and the silicon layer. The method of manufacturing a semiconductor device according to claim 3 , further comprising a step of forming the semiconductor device. 5. The method of manufacturing a semiconductor device according to claim 4, further comprising a step of removing a natural oxide film on a surface of the silicon layer before the step of forming the refractory metal nitride film. 6. The method of manufacturing a semiconductor device according to claim 5, wherein in the step of removing the natural oxide film, the surface of the silicon layer is exposed to hydrazine or a hydrazine alkyl compound. Deposition of a refractory metal nitride film characterized by depositing a refractory metal nitride film using a source gas containing a refractory metal and an alkylamino compound that reduces and nitrides the source gas as a reducing gas and a nitrogen source Method. 8. The method for depositing a refractory metal nitride film according to claim 7, wherein the source gas containing the refractory metal is a gas containing an alkylamino compound or a cyclopentadienyl compound of the refractory metal.

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