JP2003277930A - Titanium complex-containing solution as raw material for organometallic chemical vapor deposition and titanium-containg thin film produced by using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solution serving as a raw material for organometallic chemical vapor deposition with which uniform, stable vaporization can be performed and a desired titanium-containing thin film of high purity can be obtained at a high film deposition rate, and to provide a titanium-containing thin film which has excellent barrier properties as the base of a copper thin film. <P>SOLUTION: The solution as the raw material for an organometallic chemical vapor deposition method is obtained by dissolving a titanium complex expressed by the formula (1) into an organic solvent. In the formula (1), R is a 1 to 4C normal chain or branched alkyl group. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solution raw material for forming a titanium-containing thin film as a base barrier when forming and processing a copper (Cu) thin film used for wiring of a semiconductor device. For more details, see Metal Orga
nic Chemical Vapor Deposition, hereinafter referred to as MOCVD. The present invention relates to a solution raw material containing a titanium complex for forming a titanium-containing thin film by the method) and a titanium-containing thin film made from the same.

[0002]

2. Description of the Related Art Copper and copper-based alloys are used as wiring materials for LSIs because of their high conductivity and resistance to electromigration. Since copper easily diffuses into the substrate through the silicon oxide film and adversely affects the electrical characteristics of transistor elements, etc., when wiring is performed with copper, a barrier metal thin film between the copper thin film and the silicon oxide film is used as a base. To prevent the diffusion of copper.

A titanium nitride film, which is a thermally stable nitride of a refractory metal, is known as this type of underlying barrier metal thin film. Up to now, there have been few reports of producing a titanium nitride film by the MOCVD method, and recently, a titanium nitride film is formed using a tetrakisdimethylaminotitanium (hereinafter referred to as TDMAT) complex or tetrakisdiethylaminotitanium (hereinafter referred to as TDEAT). Attempts have been made to make it.

[0004]

However, when a titanium nitride film is formed by the MOCVD method using the above solution raw material, the compound contained in the raw material has poor thermal stability and decomposes inside the vaporizer as the film formation progresses. Occurs at an accelerating rate, and in the film deposition chamber where the film should be deposited, only the organic substances resulting from the decomposed ligands vaporize and prevent the vaporization of other organic substances, and non-uniform and unstable raw materials are supplied. It was Therefore, with the conventional solution raw material for forming the titanium nitride film, the film formation rate is low,
Further, carbon and oxygen remained in the film in an as-deposited state (30 atm% or more), which made it difficult to produce a desired titanium nitride film with high purity. Further, when a copper thin film is formed on the formed titanium nitride film, there is a problem that the titanium nitride film and the copper have poor adhesion and are very easily peeled off.

An object of the present invention is to provide a solution raw material for metal organic chemical vapor deposition, which is capable of uniformly and stably vaporizing and obtaining a desired titanium-containing thin film of high purity at a high film forming rate. Another object of the present invention is to provide a high-purity titanium-containing thin film having excellent barrier properties as a base of a copper thin film.

[0006]

The invention according to claim 1 is
A solution raw material for a metal organic chemical vapor deposition method, characterized in that a titanium complex represented by the following formula (1) is dissolved in an organic solvent.

[0007]

[Chemical 2] However, R is a linear or branched alkyl group having 1 to 4 carbon atoms.

The invention according to claim 2 is the solution raw material according to claim 1, wherein R of the titanium complex represented by the formula (1) according to claim 1 is a methyl group, an ethyl group or a t-butyl group. When the solution raw material according to claim 1 or 2 is vapor-phase grown by the MOCVD method, uniform and stable vaporization is performed, and a desired high-purity titanium-containing thin film can be obtained at a high film formation rate.

The invention according to claim 3 is the invention according to claim 1, which is a solution raw material in which the organic solvent is one or more compounds selected from the group consisting of saturated hydrocarbons and ester compounds. is there. The invention according to claim 4 is claim 3
The invention according to claim 1, wherein the saturated hydrocarbon has 6 to 10 carbon atoms.
Is a solution raw material which is a linear or branched hydrocarbon. The invention according to claim 5 is the invention according to claim 3 or 4, wherein the saturated hydrocarbon is selected from the group consisting of hexane, cyclohexane, n-octane, isooctane, n-decane and n-dodecane. It is a solution raw material which is one kind or two or more kinds of compounds. The invention according to claim 6 is the invention according to claim 3, wherein the ester compound is one or two selected from the group consisting of methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, pentyl acetate and isopentyl acetate. It is a solution raw material that is a compound of one or more kinds.

The invention according to claim 7 relates to claims 1 to 6.
It is a titanium-containing thin film produced by a metal organic chemical vapor deposition method using any one of the solution raw materials. The titanium-containing thin film produced by using the solution raw material according to any one of claims 1 to 6 has an excellent barrier property as a base of a copper thin film and has a feature of high purity.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Next, embodiments of the present invention will be described. The solution raw material of the present invention is a solution raw material for a metal organic chemical vapor deposition method characterized by dissolving the titanium complex represented by the above formula (1) in an organic solvent. The compounding ratio of the titanium complex and the organic solvent is arbitrary, and it is preferable that the titanium complex and the organic solvent are appropriately adjusted depending on the intended use and the type of the organic solvent. As the organic solvent of the present invention, one or more compounds selected from the group consisting of saturated hydrocarbons and ester compounds are used.
The saturated hydrocarbon is a linear or branched hydrocarbon having 6 to 10 carbon atoms. Specific examples include one or more compounds selected from the group consisting of hexane, cyclohexane, n-octane, isooctane, n-decane and n-dodecane. Examples of the ester compound include one or more compounds selected from the group consisting of methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, pentyl acetate and isopentyl acetate.

The titanium complex can be obtained by using the above formula (1) as a general formula.
And R is preferably a methyl group, an ethyl group or a t-butyl group.
Good Specifically, when R is a methyl group, its structural formula is
Is (H ₃C)₂Ti (C_FiveH_Five)₂(Hereafter, DMTiCp₂Toi
U ) And R is an ethyl group, the structural formula is
(H_FiveC₂)₂Ti (C_FiveH_Five)₂(Hereafter, DETiCp₂Toi
U ) And R is a t-butyl group, its structural formula
Is ((H₃C)₃C)₂Ti (C_FiveH_Five) ₂(Hereafter, DBTiCp₂
Say. ).

In the present embodiment, the MOCVD method uses a solution vaporization CVD method in which each solution is supplied to a heated vaporizer, where each solution raw material is instantly vaporized and sent to a film forming chamber. As shown in FIG. 1, the MOCVD apparatus includes a film forming chamber 10
And a steam generator 11. A heater 12 is provided inside the film forming chamber 10, and a substrate 13 is held on the heater 12. The inside of the film forming chamber 10 is evacuated by a pipe 17 including a pressure sensor 14, a cold trap 15 and a needle valve 16. An NH ₃ gas introducing pipe 37 is connected to the film forming chamber 10 via a needle valve 36 and a gas flow rate adjusting device 34. The steam generator 11 includes a raw material container 18, and the raw material container 18 stores a solution raw material.
A carrier gas introduction pipe 21 is connected to the raw material container 18 via a gas flow rate control device 19, and a supply pipe 22 is connected to the raw material container 18. The supply pipe 22 is provided with a needle valve 23 and a solution flow rate adjusting device 24.
Is connected to the vaporizer 26. A carrier gas introducing pipe 29 is connected to the vaporizer 26 via a needle valve 31 and a gas flow rate adjusting device 28. The vaporizer 26 is further connected to the film forming chamber 10 by a pipe 27. A gas drain 32 and a drain 33 are connected to the vaporizer 26, respectively. In this apparatus, a carrier gas composed of an inert gas such as N ₂ , He, Ar is introduced into the raw material container 18 from the carrier gas introduction pipe 21, and the solution raw material stored in the raw material container 18 is vaporized by the supply pipe 22. It is conveyed to the container 26. The titanium complex vaporized in the vaporizer 26 to become vapor is further supplied into the film forming chamber 10 via the pipe 27 by the carrier gas introduced into the vaporizer 26 from the carrier gas introduction pipe 28. In the film forming chamber 10, the vapor of the titanium complex is thermally decomposed and reacted with the NH ₃ gas introduced into the film forming chamber 10 through the NH ₃ gas introducing pipe 37, so that the produced titanium nitride is heated. A titanium nitride thin film is formed by depositing on Titanium.

The titanium nitride thin film produced by using the solution raw material of the present invention is excellent in its barrier property as an underlayer of a copper thin film and has the features of high purity. This titanium nitride thin film is, for example, a MOCV film on a SiO ₂ film on the surface of a silicon substrate.
It is formed by the D method, and a copper thin film is formed on this titanium nitride thin film by the MOCVD method. The type of the substrate of the present invention is not particularly limited.

[0015]

EXAMPLES Next, examples of the present invention will be described in detail together with comparative examples. <Example 1> A DMTiCp ₂ complex was prepared as a titanium complex, and the DMTiCp ₂ was dissolved in n-octane, which is an organic solvent, so that the concentration of each DMTiCp ₂ was 0.1 mol% to prepare a MOCVD solution raw material. . Example 2 A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that the organic solvent was isooctane. <Example 3> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that n-hexane was used as the organic solvent.

<Example 4> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that n-decane was used as the organic solvent. <Example 5> Example 1 except that the organic solvent was dodecane
A solution raw material for MOCVD was prepared in the same manner as. <Example 6> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that cyclohexane was used as the organic solvent.

<Example 7> DETiCp ₂ was used as a titanium complex.
A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that the complex was used and the organic solvent was n-octane. <Example 8> A solution raw material for MOCVD was prepared in the same manner as in Example 7, except that the organic solvent was isooctane. <Example 9> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that n-hexane was used as the organic solvent.

<Example 10> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that the organic solvent was decane. <Example 11> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that the organic solvent was dodecane. <Example 12> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that cyclohexane was used as the organic solvent.

<Example 13> A titanium complex was added to DBTiCp.
_A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that _two complexes were used and the organic solvent was n-octane. <Example 14> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was isooctane. <Example 15> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that n-hexane was used as the organic solvent.

<Example 16> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was decane. <Example 17> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was dodecane. <Example 18> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that cyclohexane was used as the organic solvent.

<Example 19> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that butyl acetate was used as the organic solvent. <Example 20> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that the organic solvent was isobutyl acetate. <Example 21> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that the organic solvent was methyl acetate.

Example 22 A MOCVD solution raw material was prepared in the same manner as in Example 1 except that the organic solvent was ethyl acetate. Example 23 A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that the organic solvent was pentyl acetate. <Example 24> A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that isopentyl acetate was used as the organic solvent.

<Example 25> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that butyl acetate was used as the organic solvent. <Example 26> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that the organic solvent was isobutyl acetate. <Example 27> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that methyl acetate was used as the organic solvent.

Example 28 A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that the organic solvent was ethyl acetate. <Example 29> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that pentyl acetate was used as the organic solvent. <Example 30> A solution raw material for MOCVD was prepared in the same manner as in Example 7 except that isopentyl acetate was used as the organic solvent.

<Example 31> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that butyl acetate was used as the organic solvent. <Example 32> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was isobutyl acetate. <Example 33> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was methyl acetate.

<Example 34> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was ethyl acetate. <Example 35> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that pentyl acetate was used as the organic solvent. <Example 36> A solution raw material for MOCVD was prepared in the same manner as in Example 13 except that the organic solvent was isopentyl acetate.

Comparative Example 1 A solution raw material for MOCVD was prepared in the same manner as in Example 1 except that the titanium complex was changed to the TDMAT complex and the organic solvent was changed to hexane. <Comparative Example 2> A solution raw material for MOCVD was prepared in the same manner as in Comparative Example 1 except that the titanium complex was changed to the TDEAT complex.

<Comparative Example 3> A solution raw material for MOCVD was prepared in the same manner as in Comparative Example 1 except that butyl acetate was used as the organic solvent. <Comparative Example 4> A solution raw material for MOCVD was prepared in the same manner as Comparative Example 2 except that the organic solvent was ethyl acetate.

<Comparative Test> Examples 1-36 and Comparative Example 1
5 kinds of solution raw materials obtained in each of 4 were prepared. As the substrate, a silicon substrate having a SiO ₂ film (thickness 5000 Å) formed on the surface of the substrate by thermal oxidation was prepared. The prepared substrate was placed in the film forming chamber of the MOCVD apparatus shown in FIG. 1 and the substrate temperature was 300 ° C. The vaporization temperature was 70 ° C. and the pressure was 2 Torr, that is, about 266 Pa.
Ar gas was used as the carrier gas and its flow rate was 100
It was set to ccm. Further, NH ₃ gas is used as a reaction gas,
The flow rate was 500 ccm. 0.01c of solution raw material
A titanium nitride thin film which is a titanium-containing thin film formed on a substrate by supplying at a rate of c / min and taking out from the film forming chamber for each one at 1, 5, 10, 20 and 30 minutes. The following test was performed on the.

Film Thickness Measurement The film thickness of the copper thin film on the substrate after film formation was measured from a cross-sectional SEM (scanning electron microscope) image. Peeling test A thickness of 50 on the titanium nitride thin film taken out at each film formation time
nm copper thin film is formed by a sputtering method, and a peeling test (JISK 56
00-5-6) was performed. Specifically, first, a lattice pattern was formed on the substrate by making 6 incisions in the copper thin film on the substrate so as to penetrate the film at equal intervals in the vertical and horizontal directions. Then brushed back and forth with a soft brush along both diagonals of the formed grid pattern. Thermal stability evaluation test The following test was performed using the test apparatus shown in FIG. The apparatus shown in FIG. 2 has a structure in which the film forming chamber of the MOCVD apparatus shown in FIG. 1 is removed. First, the solution raw material is conveyed to the vaporizer 26 heated to 70 ° C. at room temperature, heated to 70 ° C. under reduced pressure of 10 Torr, that is, about 1.33 kPa to vaporize the solution raw material, and then the pump side of the lower stage of the vaporizer 26. The compound after vaporization was captured by the cold trap 15 provided in. The trap recovery rate was calculated from the trapped amount of the raw material charged into the apparatus. Further, the pressure sensor measured the pressure rise inside the vaporizer. For example, if the numerical value in the table is 60% occlusion, it means that a pressure of 1.60 times 10 Torr occurs in the vaporizer. Examples 1 to 8 are shown in Table 1, Examples 9 to 16 are shown in Table 2, Examples 17 to 24 are shown in Table 3, Examples 25 to 32 are shown in Table 4, and Examples 33 to 36 are shown.
Table 5 shows the test results obtained for Comparative Examples 1 to 4 and Comparative Examples 1 to 4, respectively.

[0031]

[Table 1]

[0032]

[Table 2]

[0033]

[Table 3]

[0034]

[Table 4]

[0035]

[Table 5]

As is clear from Tables 1 to 3, Comparative Example 1
It can be seen that the titanium-containing thin films formed by using the solution raw materials of Nos. 4 to 4 have different film thicknesses per film forming time, and the film forming reproducibility is poor. In addition, the film formation rate is also very slow. Moreover, in the adhesion evaluation test, the copper thin film was peeled from the substrate surface in most of the samples. In the thermal stability evaluation test,
It is considered that the trap recovery rate was low and most of the traps adhered to the inside of the device. Further, the pressure rise value inside the vaporizer also rises as the film forming time becomes longer, and it is considered that the decomposition product adhered to the inside of the vaporizer and the inside of the pipe to raise the pressure. On the other hand, the titanium-containing thin films produced using the solution raw materials of Examples 1 to 36 have a larger film thickness as the film forming time progresses, and it can be seen that the film forming stability is high. In the adhesion evaluation test, it is found that the rate of peeling of the copper thin film is low and the adhesion is very high. In the thermal stability evaluation test, the trap recovery rate was high, and the pressure rise value inside the carburetor was also 1.
There is almost no risk of blockage at about%.

[0037]

As described above, the present invention in which the titanium complex represented by the above formula (1) is dissolved in one or more compounds selected from the group consisting of organic solvents, saturated hydrocarbons and ester compounds. The MOCVD solution raw material is excellent in its barrier property as an underlayer of a copper thin film and has a feature of high purity. When vapor-depositing a titanium-containing thin film on a SiO ₂ film using the solution raw material of the present invention, stable film formation can be achieved at a high film formation rate. When a copper thin film is formed on the obtained titanium-containing thin film, a copper thin film having excellent adhesion can be prepared regardless of the film forming method.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a MOCVD apparatus.

FIG. 2 is a schematic diagram showing an apparatus used in an embodiment of the present invention.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Katsumi Ogi             1002 Mukayama, Naka-machi, Naka-machi, Naka-gun, Ibaraki Prefecture 14 Mitsubishi             Materials Research Laboratories Naka Research Center             In the center F term (reference) 4H049 VN05 VP01 VQ05 VR24 VU24                       VW02                 4K030 AA11 BA18 BA38 FA10                 4M104 BB30 DD45 FF18

Claims (7)

[Claims] 1. A solution raw material for a metal organic chemical vapor deposition method, characterized in that a titanium complex represented by the following formula (1) is dissolved in an organic solvent. [Chemical 1] However, R is a linear or branched alkyl group having 1 to 4 carbon atoms. 2. The solution raw material according to claim 1, wherein R of the titanium complex represented by the formula (1) according to claim 1 is a methyl group, an ethyl group or a t-butyl group. 3. The solution raw material according to claim 1, wherein the organic solvent is one or more compounds selected from the group consisting of saturated hydrocarbons and ester compounds. 4. The solution raw material according to claim 3, wherein the saturated hydrocarbon is a linear or branched hydrocarbon having 6 to 10 carbon atoms. 5. The saturated hydrocarbon is one or two or more compounds selected from the group consisting of hexane, cyclohexane, n-octane, isooctane, n-decane and n-dodecane. Solution raw material. 6. The solution raw material according to claim 3, wherein the ester compound is one or more compounds selected from the group consisting of methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, pentyl acetate and isopentyl acetate. . 7. A titanium-containing thin film produced by a metal organic chemical vapor deposition method using the solution raw material according to claim 1.