JP3915054B2 - Film forming material, film forming method, and element - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a film forming material, a film forming method, and an element.
[0002]
[Problems to be solved by the invention]
At present, the progress in the semiconductor field is remarkable, and the LSI is moving from ULSI. In order to improve the processing speed of signals, miniaturization is progressing. In particular, the distance between the source and drain is getting shorter. Along with this, the gate oxide film is also becoming extremely thin.
[0003]
By the way, at present, the gate oxide film is made of SiO ₂ , and it is expected that this thickness will be 10 nm or less. When the thickness of the gate oxide film reaches 3 nm or less, for example, 3 nm, 2 nm, or 1.5 nm, the charge accumulated between the source and the drain passes through the gate oxide film. .
[0004]
In order to solve such problems, metal oxide films have been proposed.
[0005]
However, it does not simply mean that a metal oxide film is sufficient.
[0006]
For example, it is necessary not to oxidize the underlying silicon. That is, the interface with the silicon layer must be stable. Also, the dielectric constant must be high.
[0007]
As a result of research conducted from such a viewpoint, Zr (zirconium), Hf (hafnium), and Ln (lanthanoid element) form a stable silicate at the interface with silicon. Is stable and the dielectric constant of the oxide film is high, so its effectiveness is expected. However, it has been reported that the oxide film of Zr, Hf, and Ln has a polycrystalline structure, and in particular, has a columnar polycrystalline structure in a direction perpendicular to the substrate to be formed. For this reason, if the gate oxide film is formed of such an oxide film, it is expected that the charge accumulated between the source and the drain will escape between the columnar crystal blocks in the oxide film.
[0008]
Therefore, it has been proposed to make the oxide film of Zr, Hf, and Ln amorphous, and in particular, by adding silicon to the film of Zr, Hf, and Ln, it has been confirmed that the film becomes amorphous. . However, this confirmation is only for films formed by sputtering methods.
[0009]
There are very few examples of adding silicon by CVD using a silicon compound. Although the film formed by CVD has been confirmed to be amorphous for the time being, the film produced by the conventional methods contains carbon and nitrogen derived from the raw materials. It was found that many impurities were contained, and this was not satisfactory as a gate oxide film.
[0010]
Therefore, the problem to be solved by the present invention is to provide a film forming material and a film forming method that can form a silicon-containing gate oxide film having high purity and amorphousness by CVD.
[0011]
[Means for Solving the Problems]
While intensively pursuing research on the above problems, the present inventor has developed a film formed by CVD using Si (NCO) _x H _4-x (where x is an integer of 1 to ₄ ) as the Si source. It has been found that contamination of impurities such as carbon and nitrogen is hardly a problem, is highly pure and amorphous, and has high performance as a gate oxide film. .
[0012]
The present invention has been achieved based on such findings,
A film forming material for forming a gate oxide film composed of one or more elements selected from the group consisting of Zr, Hf, and Ln, Si, and O,
Si (NCO) _x H _4-x (where x is an integer of 1 to ₄ ) as a Si source in the gate oxide film
This is solved by a film forming material characterized in that is used.
[0013]
Among them, a film forming material for forming a gate oxide film constituted by using one or more elements selected from the group of Zr, Hf, and Ln, Si, and O,
_{(I-O-C 3 H} 7) 4 Zr, (t-O-C 4 H 9) 4 Zr, (DPM) 4 Zr, (Me 2 N) 4 Zr, (Et 2 N) 4 Zr, (Et _{(Me) N) 4 Zr,} (i-O-C 3 H 7) 4 Hf, (t-O-C 4 H 9) 4 Hf, (DPM) 4 Hf, (Me 2 N) 4 Hf, (Et ₂ N) ₄ Hf, (Et (Me) N) ₄ Hf, (DPM) ₃ Ln, Ln [N (SiMe ₃ ) ₂ ] ₃ , [C ₅ H ₅ ] ₃ Ln, [(CH ₃ ) C ₅ H _{4] 3 Ln, [(C} 2 H 5) C 5 H 4] 3 Ln, [(i-C 3 H 7) C 5 H 4] 3 Ln, [(n-C 4 H 9) C 5 H 4 ] One or two or more selected from the group of ₃ Ln;
Si (NCO) _x H _4-x (where x is an integer of 1 to 4)
It solves by the film forming material characterized by comprising.
[0014]
In particular, a film forming material for forming a gate oxide film constituted by using one or more elements selected from the group of Zr, Hf, and Ln, Si, and O,
One or more selected from the group of (Et ₂ N) ₄ Zr, (Et ₂ N) ₄ Hf, Ln [N (SiMe ₃ ) ₂ ] ₃ ;
Si (NCO) ₄
It solves by the film forming material characterized by comprising.
[0015]
That is, a film formed by CVD using a compound having the above structure is almost free from contamination by impurities such as carbon and nitrogen, is highly pure and amorphous, and has a gate. It was a high performance oxide film.
[0016]
In addition, when the said compound was melt | dissolved and preserve | saved in the solvent, decomposition | disassembly was suppressed so much and it was excellent in stability. The CVD can be performed while being dissolved in a solvent. Therefore, it is extremely preferable to dissolve the CVD raw material in the solvent.
[0017]
The above problem can also be solved by a film forming method characterized in that an oxide film is formed by CVD using the above film forming material (compound) and an oxidizing agent.
[0018]
In particular, the problem is solved by a film forming method characterized in that an oxide film is formed by CVD by simultaneous decomposition using the above film forming material (compound) and an oxidizing agent. Alternatively, the problem is solved by a film forming method in which an oxide film is formed by CVD using heterogeneous decomposition using the film forming material (compound) and an oxidizing agent. Among them, a first step of decomposing a CVD film forming material that is one or more element sources selected from the group of Zr, Hf, and Ln, a second step of decomposing an oxidant that is an O source, An oxide film is formed by CVD by different time decomposition in which a third step of decomposing a CVD film forming material serving as a Si source and a fourth step of decomposing an oxidizing agent serving as an O source are sequentially performed. It is solved by the film forming method.
[0019]
The film-forming material (compound) is decomposed using any method selected from the group consisting of heat, plasma, light, and laser. The temperature during decomposition is preferably 350 to 550 ° C. The pressure is preferably 0.001 to 20 Torr. The atmosphere is preferably performed in an oxygen atmosphere diluted with nitrogen to 0.1 to 10%.
[0020]
The above-mentioned problem can also be solved by an element comprising a gate oxide film formed by the above film forming method.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
As the film forming material according to the present invention (particularly, a film forming material for forming by CVD), one or more elements selected from the group of Zr, Hf, and Ln, Si, and O are used. A film forming material for forming a gate oxide film composed of Si (NCO) _x H _4-x (where x is an integer of 1 to 4) is used as a Si source in the gate oxide film. It is what In _{particular, (i-O-C 3} H 7) 4 Zr, (t-O-C 4 H 9) 4 Zr, (DPM) 4 Zr, (Me 2 N) 4 Zr, (Et 2 N) 4 Zr, _{(Et (Me) N) 4} Zr, (i-O-C 3 H 7) 4 Hf, (t-O-C 4 H 9) 4 Hf, (DPM) 4 Hf, (Me 2 N) 4 Hf, (Et ₂ N) ₄ Hf, (Et (Me) N) ₄ Hf, (DPM) ₃ Ln, Ln [N (SiMe ₃ ) ₂ ] ₃ , [C ₅ H ₅ ] ₃ Ln, [(CH ₃ ) C _{5 H 4] 3 Ln, [} (C 2 H 5) C 5 H 4] 3 Ln, [(i-C 3 H 7) C 5 H 4] 3 Ln, [(n-C 4 H 9) C 5 1 or 2 or more selected from the group of H ₄ ] ₃ Ln and Si (NCO) _x H _4-x (where x is an integer of 1 to 4). Among these, one or more selected from the group of (Et ₂ N) ₄ Zr, (Et ₂ N) ₄ Hf, Ln [N (SiMe ₃ ) ₂ ] ₃ and Si (NCO) ₄ are used. It has. These compounds are usually placed in a solvent.
[0022]
The film forming method according to the present invention is a method of forming an oxide film by CVD using the above film forming material (compound) and an oxidizing agent. In particular, this is a method of forming an oxide film by CVD by simultaneous decomposition using the film forming material (compound) and an oxidizing agent. Alternatively, an oxide film is formed by CVD using heterogeneous decomposition using the film forming material (compound) and an oxidizing agent. Among heterochronous decompositions, a first step of decomposing a film forming material for CVD as one or two or more element sources selected from the group of Zr, Hf, and Ln, decomposing an oxidizing agent as an O source In this method, an oxide film is formed by CVD by sequentially performing a second process, a third process for decomposing a CVD film forming material serving as a Si source, and a fourth process for decomposing an oxidizing agent serving as an O source. The film-forming material (compound) is decomposed using any method selected from the group consisting of heat, plasma, light, and laser. The temperature during decomposition is 350 to 550 ° C. The pressure is 0.001 to 20 Torr. The atmosphere is an oxygen atmosphere diluted with nitrogen to 0.1 to 10%.
[0023]
An element such as LSI or ULSI according to the present invention comprises a gate oxide film formed by the above film forming method.
[0024]
Hereinafter, more specific examples will be described.
[0025]
[Example 1]
FIG. 1 is a schematic view of a film forming apparatus (CVD). In the figure, 1a and 1b are raw material containers, 2 is a heater, 3 is a decomposition reaction furnace, 4 is a Si substrate, and 5 is a flow rate controller.
[0026]
The container 1a contains (Et ₂ N) ₄ Hf and is heated to 80 ° C. Then, nitrogen was blown as a carrier gas at a rate of 20 ml / min.
[0027]
Si (NCO) ₄ was placed in the container 1b, and nitrogen was blown as a carrier gas at a rate of 20 ml / min.
[0028]
The vaporized (Et ₂ N) ₄ Hf and Si (NCO) ₄ are introduced into the decomposition reaction furnace 3 through piping along with the carrier gas. At this time, the system was exhausted to 0.1 to 1 Torr. The substrate 4 is heated to 500 ° C.
[0029]
At the time of introduction, oxygen diluted to 1% with nitrogen was supplied as a reaction gas at a rate of 10 ml / min.
[0030]
A film was formed on the surface of the Si substrate 4 as described above.
[0031]
This film was observed with a TEM (transmission electron microscope). As a result, no crystal lumps were observed, and it was confirmed to be amorphous. The interface was also stable. It was also confirmed by the electron beam diffraction pattern that it was amorphous.
[0032]
Further, the concentrations of Hf, Si, O, N, and C in the film were analyzed by XPS (X-ray photoelectron spectroscopy). According to this, C and N were not observed, and the film was composed of Hf, Si and O.
[0033]
Furthermore, when the Capacitance-Voltage characteristics of the 5 nm thick film prepared by the above method were examined, the film had leak resistance that could be used sufficiently for the next generation transistor.
[0034]
Examples 2 to 6
In Example _1, (Et 2 _N) 4 instead _{(i-O-C 3 H} 7) 4 Hf of _{Hf, (t-O-C} 4 H 9) 4 Hf, (DPM) 4 Hf, (Me 2 N) ₄ Hf, (Et (Me) N) ₄ Hf was used in the same manner.
[0035]
As a result, a film similar to that in Example 1 was obtained.
[0036]
Examples 7 to 12
In Example 1, instead of (Et ₂ N) ₄ Hf, (Et ₂ N) ₄ Zr, (i-O—C ₃ H ₇ ) ₄ Zr, (t—O—C ₄ H ₉ ) ₄ Zr, ( DPM) ₄ Zr, (Me ₂ N) ₄ Zr, (Et (Me) N) ₄ Zr were used in the same manner.
[0037]
As a result, a film similar to that in Example 1 was obtained. However, the film composition is Zr, Si, O.
[0038]
Examples 13 to 19
In Example 1, Ln [N (SiMe ₃ ) ₂ ] ₃ , (DPM) ₃ Ln, [C ₅ H ₅ ] ₃ Ln, [(CH ₃ ) C ₅ H ₄ instead of (Et ₂ N) ₄ Hf _{] 3 Ln, [(C 2} H 5) C 5 H 4] 3 Ln, [(i-C 3 H 7) C 5 H 4] 3 Ln, [(n-C 4 H 9) C 5 H 4] _{The same} procedure was performed using ₃ Ln.
[0039]
As a result, a film similar to that in Example 1 was obtained. However, the film composition is Ln, Si, O.
[0040]
As Ln, La, Pr, Nd, Sm, Tb, Er, and Yb were used.
[0041]
Examples 20 to 24
In Example 1, HSi (NCO) ₃ and H ₂ Si (NCO) ₂ were used in the same manner instead of Si (NCO) ₄ .
[0042]
As a result, a film similar to that in Example 1 was obtained.
[0043]
Examples 25-28
In Example 1, the same procedure was performed using nitrous oxide, ozone, water, and hydrogen peroxide instead of diluted oxygen.
[0044]
As a result, a film similar to that in Example 1 was obtained.
[0045]
Examples 29-31
In Example 1, it carried out similarly using plasma, light, and laser irradiation instead of the heating as a decomposition | disassembly means of a compound.
[0046]
As a result, a film similar to that in Example 1 was obtained.
[0047]
Example 32
FIG. 2 is a schematic view of a film forming apparatus (CVD). In the figure, 1a and 1b are raw material containers, 2 is a heater, 3 is a decomposition reaction furnace, 4 is a Si substrate, 5 and 6 are flow controllers, and 7 is a vaporizer.
[0048]
Using the apparatus of FIG. 2, a solution dissolved in decane so that Pr [N (SiMe ₃ ) ₂ ] ₃ is 0.1 mol / l is put in the raw material container 1a, and Si (NCO) ₄ is 0.1 mol. A solution dissolved in decane so as to be 1 / l was put into the raw material container 1 b and sent to the vaporizer 7 through the flow rate controller 6. The vaporizer 7 to which Pr [N (SiMe ₃ ) ₂ ] ₃ is transported is set to 190 ° C., and the vaporizer 7 to which Si (NCO) ₄ is transported is set to 50 ° C. Is done.
[0049]
The vaporized raw material is introduced into the decomposition reaction furnace 3 through a pipe together with a carrier gas. At this time, the substrate 4 is heated to 350 ° C.
[0050]
At the time of introduction, oxygen diluted to 1% with nitrogen was supplied as a reaction gas at a rate of 20 ml / min.
[0051]
A film was formed on the surface of the Si substrate 4 as described above.
[0052]
This film was observed with TEM. As a result, no crystal lumps were observed, and it was confirmed to be amorphous. The interface was also stable. It was also confirmed by the electron beam diffraction pattern that it was amorphous.
[0053]
Further, the concentrations of Pr, Si, O, N, and C in the film were analyzed by XPS. According to this, C and N were not observed, and the film was composed of Pr, Si and O.
[0054]
【The invention's effect】
A high-purity amorphous gate oxide film can be formed by CVD, and a high-performance device can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic view of a CVD apparatus. FIG. 2 is a schematic view of a CVD apparatus.
1a, 1b Container 2 Heater 3 Decomposition reactor 4 Si substrate 5 Flow rate controller

Claims (11)

A film forming material for forming a gate oxide film composed of one or more elements selected from the group consisting of Zr, Hf, and Ln, Si, and O,
Si (NCO) _x H _4-x (where x is an integer of 1 to 3) as a Si source in the gate oxide film
A film forming material characterized in that is used. As one or more element sources selected from the group of Zr, Hf, Ln,
_{(I-O-C 3 H} 7) 4 Zr, (t-O-C 4 H 9) 4 Zr, (DPM) 4 Zr, (Me 2 N) 4 Zr, (Et 2 N) 4 Zr, (Et _{(Me) N) 4 Zr,} (i-O-C 3 H 7) 4 Hf, (t-O-C 4 H 9) 4 Hf, (DPM) 4 Hf, (Me 2 N) 4 Hf, (Et ₂ N) ₄ Hf, (Et (Me) N) ₄ Hf, (DPM) ₃ Ln, Ln [N (SiMe ₃ ) ₂ ] ₃ , [C ₅ H ₅ ] ₃ Ln, [(CH ₃ ) C ₅ H _{4] 3 Ln, [(C} 2 H 5) C 5 H 4] 3 Ln, [(i-C 3 H 7) C 5 H 4] 3 Ln, [(n-C 4 H 9) C 5 H 4 ] One or two or more compounds selected from the group of ₃ Ln
The film-forming material according to claim 1 , characterized in that is used . The compound serving as one or two or more element sources and / or the compound serving as a Si source selected from the group consisting of Zr, Hf, and Ln is dissolved in a solvent. The film forming material according to claim 2. It is a film forming material for forming a gate oxide film composed of one or more elements selected from the group of Zr, Hf, and Ln, Si, and O by CVD. The film forming material according to claim 1, wherein the film forming material is a film forming material. An oxide film is formed by CVD using the film forming material according to any one of claims 1 to 4 and an oxidizing agent . 6. The film forming method according to claim 5, wherein the film forming materials are decomposed simultaneously or separately . A first step of decomposing a film forming material for CVD as one or more element sources selected from the group of Zr, Hf, and Ln, a second step of decomposing an oxidant as an O source, a Si source The film forming method according to claim 5 or 6, wherein the third step of decomposing the CVD film forming material and the fourth step of decomposing the oxidizing agent serving as the O source are sequentially performed . Film forming material heat, plasma, light, claim 5 claim 7 either film forming method characterized in that it is allowed to decompose using any of the techniques selected from the group of the laser. The film forming method according to any one of claims 5 to 8, wherein the film forming material is decomposed at a temperature of 350 to 550 ° C. Nitrogen diluted oxygen atmosphere from 0.1 to 10% decomposition temperature 350 to 550 ° C., either claims 5 to claim 9, characterized in that it is carried out under the conditions of the reaction chamber pressure 0.001~20Torr Film forming method. An element comprising a gate oxide film formed by the film forming method according to claim 5 .

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