JPH0820870A - Formation of high purity platinum film - Google Patents

Abstract

PURPOSE:To efficiently form a high purity Pt thin film on a substrate by heating a soln. obtd. by dissolving a specified organic Pt compound in an organic solvent, vaporizing the same and irradiating the vapor of the obtd. organic Pt compound with light beams having a specified wavelength. CONSTITUTION:An organic Pt compound shown by a formula {in the formula, R1 denote H, CH3 or -Si(CH3)3} is dissolved in an organic solvent such as tetrahydrofuran. This soln. is heated together with a carrier gas and is vaporized. The obtd. vapor of the organic Pt compound is introduced into a film forming chamber in which a substrate is placed at the inside, and the vapor of the organic Pt compound is irradiated with light beams having >=240nm wavelength to decompose the organic Pt compound. Pt produced by the decomposition is deposited on a substrate to form a high purity Pt film. The temps. of the film forming chamber and the substrate are preferably regulated to <=150 deg.C. Thus, the high purity Pt film contg. <=1% carbon as impurities can be formed at 100 to 500nm/min film forming rate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a high-purity platinum film, and more particularly to a method for forming a high-purity Pt thin film used as a contact or wiring of a semiconductor device at a low reaction temperature.

[0002]

2. Description of the Related Art Conventionally, Pt thin films used as contacts and wirings of semiconductor devices are vacuum vapor deposition, sputtering, and metalorganic chemical vapor deposition by thermal decomposition.
emicalVapor Deposition: Hereinafter referred to as "MOCVD method". ) Was formed.

In addition, Pt film formation by the photolysis MOCVD method has been attempted, and a Pt (hfac) ₂ compound represented by the following structural formula is used as a raw material organic Pt compound (Dan Rooney, D .Negrotti, T.Byassee, D.Macero,
abd J.Chaiken, J.Electrochem.Soc., 137, 1162-1166 (199
0)).

[0004]

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[0005]

[Problems to be Solved by the Invention] However, Pt
In the photolytic MOCVD method using (hfac) ₂ , Xe
Laser irradiation using Cl (308 nm), 10 Hz, and 20 mJ / cm ² poses a problem that about 24% of carbon remains in the film.

On the other hand, the vapor of the organic gold compound is emitted at a wavelength of 308n.
There are attempts to deposit gold by excitation decomposition with m light, but as shown in Table 1 below, the chemical form of the organic gold compound, and
It has been reported that the amount of impurities in the obtained film changes greatly depending on the combination of the chemical form of the organic gold compound and the wavelength and intensity of light (David Wexler, Jeffrey I. Zink, Lee.
W. Tutt and Sharon R. Lunt, J. Phys Chem., 97, 13563-13
567 (1993)).

[0007]

[Table 1]

The present invention solves the above-mentioned conventional problems and easily and efficiently forms a high-purity Pt film by the Pt-MOCVD method in which vapor of an organic Pt compound is photolyzed to deposit Pt on a substrate. The purpose is to provide a method.

[0009]

A method for forming a high-purity Pt film according to claim 1 is a method for forming a Pt film by depositing Pt generated by decomposition of vapor of an organic Pt compound on a substrate. A compound represented by the following general formula is used as the Pt compound, and the vapor of the organic Pt compound is irradiated with light having a wavelength of 240 nm or more to decompose the organic Pt compound.

[0010]

Embedded image

A method for forming a high-purity Pt film according to a second aspect is the method according to the first aspect, wherein a solution of an organic Pt compound dissolved in an organic solvent is heated together with a carrier gas to vaporize the organic Pt compound. The vapor of the organic Pt compound thus obtained is introduced into a film forming chamber in which a substrate is placed, and the vapor of the organic Pt compound is irradiated with light.

A method for forming a high-purity Pt film according to a third aspect is the method according to the second aspect, wherein the organic solvent is ether, aliphatic hydrocarbon or a mixed solvent thereof.

The method for forming a high-purity Pt film according to claim 4 is the method according to claim 3, wherein the organic solvent is one or more selected from the group consisting of tetrahydrofuran, dioxane, diglyme, pentane, hexane and heptane. It is a mixed solvent of.

A method for forming a high-purity Pt film according to claim 5 is characterized in that, in the method according to any one of claims 2 to 4, the temperature of the film forming chamber and the substrate is 150 ° C. or lower.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing an example of an apparatus suitable for carrying out the method for forming a high purity Pt film of the present invention.

In FIG. 1, reference numeral 1 denotes a chamber (film forming chamber), which has a heater 2 therein, and a substrate 3 is placed on the heater 2. Further, a quartz window 4 is provided in the upper part of the chamber 1 so that the light 5 can be directed toward the substrate 3 inside. The inside of the chamber 1 is evacuated by a pipe 8 equipped with a pressure gauge 6 and a needle valve 7.

Reference numeral 9 denotes a raw material container, which contains a liquid in which an organic Pt compound is dissolved in an organic solvent. 10 is a vaporization chamber.

Reference numerals 11 and 12 denote carrier gas introduction pipes. The carrier gas from the introduction pipe 11 is introduced into the raw material container 9 to convey the raw material solution to the vaporization chamber 10 through the pipe 13. The organic Pt compound vaporized in the vaporization chamber to become vapor is further supplied into the chamber 1 through the pipe 14 by the carrier gas from the introduction pipe 12. Chamber 1
In the inside, by being irradiated with light 5, the raw material organic P
The vapor of the t compound photodecomposes, and Pt generated by this
, Is deposited on the heated substrate 3 to form a Pt film.
In addition, 15 and 16 are gas flow rate control devices, 17 is a solution flow rate control device, and 18 and 19 are needle valves.
The steam generating facilities such as the raw material container 9, the vaporization chamber 10, and the pipes 13 and 14 are installed in the constant temperature bath 20.

In the method of the present invention, the light source for ultraviolet light having a wavelength of 240 nm or more to be used is not particularly limited, but normally, 240 to 360 nm, 10 to 100 Hz using KrF, XeCl, XeF or the like as a light source. , 1
Light of 50 mJ / cm ² is preferably used.

In the present invention, as the raw material organic Pt compound used for photolysis, the bond between Pt and the ligand is cut at a low temperature without decomposing the ligand by irradiation with ultraviolet light, and Pt is rapidly deposited. Therefore, Pt having a high purity can be obtained at a low temperature, and therefore a compound represented by the following general formula is used.

[0022]

[Chemical 4]

Further, as an organic solvent for dissolving such an organic Pt compound, since it is an inert solvent which does not have a large absorption in the ultraviolet region having a wavelength of 240 nm or more,
Ethers such as tetrahydrofuran (THF), dioxane, and diglyme, or aliphatic hydrocarbons such as pentane, hexane, and heptane are preferable, and the evaporation rate and the stability of the Pt complex are adjusted by appropriately mixing these solvents. It is also possible to achieve

The organic Pt compound according to the present invention is preferably dissolved in such an organic solvent at a concentration of about 5 to 50% by weight to obtain a raw material solution, which is easily vaporized at a vaporization temperature of about 30 to 100 ° C. Can be made.

On the other hand, the carrier gas is H ₂ , A
It is possible to use r, He, N ₂ or a mixed gas thereof.

The flow rates of the raw material solution and the carrier gas are appropriately determined in combination with other conditions such as temperature and wavelength according to the required film forming rate and the like.

The substrate on which the Pt film is to be formed is appropriately selected according to the intended use. In the usual case, a Si substrate, a GaAs substrate, a GaN substrate or the like is used for a semiconductor device, and a quartz is used for a photomask. For glass substrates and liquid crystal displays, Vycor glass substrates, non-alkali glass substrates and the like can be used.

In the present invention, the temperature inside the substrate and the film forming chamber is preferably 150 ° C. or lower in order to prevent the deterioration of the purity of the Pt film due to the decomposition of the ligand of the organic Pt compound. If the film-forming temperature is excessively low, the film-forming rate is lowered and the film-forming efficiency is deteriorated. Therefore, it is particularly preferably set to 100 to 150 ° C.

The film forming pressure is 10 torr or less.

According to the method of the present invention as described above, normally, 100 to 500 nm / mi is obtained at a temperature of 150 ° C. or lower.
Carbon content of 1% by weight as an impurity at a film forming rate of n
The following high-purity Pt film can be formed.

[0031]

With the organic Pt compound according to the present invention, the Pt (hfa) used in the conventional photolytic MOCVD method is used.
Compared to c) ₂ , the bond between Pt and the ligand is cut at a low temperature without decomposing the ligand by irradiation with light having a wavelength of 240 nm, and Pt can be deposited at a high speed.

Therefore, the photolytic MO of the present invention for decomposing the specific organic Pt compound by light having a wavelength of 240 nm or more.
According to the CVD method, high-speed film formation can be performed at a low temperature of 150 ° C. or lower, deterioration of film purity due to decomposition of ligands can be prevented, and a high-purity Pt film can be efficiently formed.

Incidentally, short wavelength light having a wavelength of less than 240 nm causes decomposition of the ligand of the organic Pt compound, and the amount of carbon impurities in the obtained Pt film increases, which is not preferable.

According to the method of claim 2, it is possible to increase the effective utilization efficiency of the organic Pt compound and efficiently form the Pt film.

That is, as a method of supplying the organometallic compound gas to the film forming chamber, a method of placing the organometallic compound in a vaporization container, heating and vaporizing the metalorganic compound and introducing it into the film forming chamber together with a carrier gas, and a method of supplying the organometallic compound A solution dissolved in an organic solvent,
Quantitatively introduced into the vaporization chamber and heated with carrier gas,
A liquid supply method is known in which the liquid is introduced into the film forming chamber after being vaporized, but the latter method reduces the amount of the organometallic compound decomposed during vaporization and improves the utilization rate of the organometallic compound, as compared with the former method. In addition, the amount of the organometallic compound gas supplied to the film forming chamber can be quantitatively determined.

However, depending on the organic solvent used,
Since there are solvents that hinder the evaporation properties of organometallic compounds, solvents that prevent photoexcited decomposition of organometallic compounds, and solvents that tend to remain as impurities in the film, it is necessary to select an appropriate organometallic compound / solvent and film formation method combination. Will be needed.

According to claim 3, in particular the method of claim 4,
Stable and efficient film formation can be performed without increasing the amount of impurities in the Pt film by using an inert solvent that does not have a large absorption in the ultraviolet region of wavelengths of 240 nm or more. By doing so, the evaporation rate of the organic Pt compound and the stability of the Pt complex can be optimally adjusted.

According to the method of claim 5, it is possible to reliably form a high-purity Pt film at a high film formation rate at a reaction temperature of 150 ° C. or lower.

[0039]

EXAMPLES The present invention will be described more specifically with reference to Examples and Comparative Examples below.

The organic Pt used in the examples and comparative examples
The compounds are as follows.

CpPtMe ₃ : R ₁ = H in the above general formula CpMePtMe ₃ : R ₁ = CH _{3 in the} above general formula
CpSiMe ₃ PtMe ₃ : R ₁ = Si in the above general formula
(CH ₃ ) ₃ Examples 1 to 13 and Comparative Examples 1 to 8 Pt films were formed by the photolytic MOCVD method of the present invention using the apparatus shown in FIG. A raw material solution prepared by dissolving the organic Pt compound shown in Tables 2 and 3 in the organic solvent shown in Tables 2 and 3 at a ratio of 20% by weight was fed at a flow rate of 0.1 cc / min, while H ₂ was used as a carrier gas. Are fed at the flow rates shown in Tables 2 and 3 (the flow rate of the pipe 12 is 60 sccm), and after being vaporized in the vaporization chamber at the vaporization temperatures shown in Tables 2 and 3,
The vapor was introduced into a chamber in which a Si (111) substrate was placed as a substrate, and the light shown in Tables 2 and 3 was irradiated at the substrate temperature and pressure shown in Tables 2 and 3 to form a Pt film.

The film forming rate and the film purity (carbon content (% by weight)) are as shown in Tables 2 and 3, and according to the method of the present invention of irradiating light having a wavelength of 240 nm or more, a low reaction of 150 ° C. or less. It can be seen that a high-purity Pt film can be formed at a high temperature at a high temperature.

On the other hand, in Comparative Examples 1 to 5 using light having a wavelength of less than 240 nm, it was not possible to form a high-purity Pt film. In addition, Comparative Example 6 using a conventional organic Pt compound
In Nos. 8 to 8, the film purity is lowered due to the decomposition of the ligand of the organic Pt compound.

In Examples 10 to 13, since the compatibility between the organic solvent and the organic Pt compound is not sufficient,
The film purity is slightly inferior.

[0045]

[Table 2]

[0046]

[Table 3]

[0047]

As described in detail above, the high purity Pt of the present invention is used.
According to the film forming method, it is possible to easily and efficiently form a high-purity Pt film using light at a low reaction temperature. In particular, according to the photolytic MOCVD method of the present invention, a circuit pattern of high-purity Pt can be directly and accurately formed on a substrate by, for example, direct drawing by laser scanning or transfer of a mask pattern, Its industrial utility is extremely large.

According to the method of claim 2, the Pt film can be formed with a high effective utilization efficiency of the organic Pt compound.

According to the method of claim 3, in particular of claim 4,
Efficient film formation can be performed using an optimal organic solvent for the organic Pt compound, and the evaporation rate can be controlled and the stability of the organic Pt compound can be optimized easily.

According to the method of the fifth aspect, a high-purity Pt film can be reliably formed.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an example of an apparatus suitable for carrying out a method for forming a high-purity Pt film of the present invention.

[Explanation of symbols]

 1 Chamber 2 Heater 3 Substrate 4 Quartz Window 5 Light 6 Pressure Gauge 7 Needle Valve 9 Raw Material Container 10 Vaporization Chamber 20 Constant Temperature Bath

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Katsumi Ogi 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Corporation Central Research Laboratory

Claims (5)

[Claims] 1. A method of depositing platinum produced by decomposition of vapor of an organic platinum compound on a substrate to form a platinum film, wherein a compound represented by the following general formula is used as the organic platinum compound, and A method for forming a high-purity platinum film, characterized in that vapor of an organic platinum compound is irradiated with light having a wavelength of 240 nm or more to decompose the organic platinum compound. Embedded image 2. The method according to claim 1, wherein the organic platinum compound is vaporized by heating a solution of the organic platinum compound dissolved in an organic solvent together with a carrier gas, and the vapor of the organic platinum compound thus obtained is
A method for forming a high-purity platinum film, which comprises introducing the substrate into a film forming chamber in which the substrate is placed and irradiating the vapor of the organic platinum compound with light. 3. The method for forming a high-purity platinum film according to claim 2, wherein the organic solvent is ether, aliphatic hydrocarbon or a mixed solvent thereof. 4. The method according to claim 3, wherein the organic solvent is one or more mixed solvents selected from the group consisting of tetrahydrofuran, dioxane, diglyme, pentane, hexane and heptane. Method for forming high-purity platinum film. 5. The method for forming a high-purity platinum film according to claim 2, wherein the temperature of the film forming chamber and the substrate is 150 ° C. or lower.