JPH0633242A - Cvd device and formation of tin thin film - Google Patents

Abstract

PURPOSE:To separately supply >=2 kinds of gases and to uniformly diffuse and mix these gases so that the gaseous mixture composed thereof arrives at a substrate. CONSTITUTION:Gaseous TiCL4<66> introduced at 5sccm flow rate between a cylindrical pipe 42 and an inside pipe 44 and gaseous NH3 68 is introduced at 400sccm flow rate into the inside pipe 44. A reaction chamber 30 is evacuated by a turbo molecular pump, by which 300mTorr is maintained in the reaction chamber 30. The TiCL4 is heated by a heater 46. Two kinds of the gases blown out of the cylindrical pipe 42 collide against vanes 56 and rotate the vanes 56. As a result, two kinds of the gases are sufficiently mixed. The substrate 36 is heated to 600 deg.C by a heater 32. Two kinds of the gases react on the substrate 36 and the uniform TiN thin film is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a CVD apparatus for introducing two or more kinds of gases that need to be separately supplied into a reaction chamber to form a film on a substrate, and a TiN thin film forming method using this apparatus. With regard to and, especially CVD characterized by gas mixing method
The present invention relates to an apparatus and a TiN thin film forming method.

[0002]

2. Description of the Related Art When a thin film is formed by a CVD method using two or more kinds of starting gases, in order to obtain a uniform composition and film quality, the mixing ratio of the two or more kinds of gases is constant over the entire surface of the substrate. There is a need to. In this case, there is no problem if two or more kinds of gases can be sufficiently mixed and supplied before the gas is supplied to the reaction chamber. However, in the case of a combination of gases in which an undesired reaction occurs by premixing, a gas supply structure that separately supplies to the reaction chamber and is sufficiently mixed on the substrate is required.

As an example of supplying two kinds of gases, a CVD using a titanium compound gas and a nitrogen compound gas
A TiN thin film may be formed by the method. The TiN thin film is used as a barrier film in, for example, a highly integrated circuit IC. FIG. 6 is a plan view of a conventional gas diffusion device used as a gas supply device for forming a TiN thin film. This gas diffusion device uses two comb-shaped pipes 10 and 12, and gas is ejected from the blowout holes 20 of the ejection pipes 18 arranged alternately. In this example, TiC
After mixing the l ₄ gas and the N ₂ gas, the mixed gas 14
Is introduced from the inlets of the two comb pipes 10 and 12.
Examples of this type are, for example, “Vacuum”, Vol. 29, No. 5,
1986, pp. 156-159.

FIG. 7 is a plan view of another gas diffusion device.
This is a shower head type, in which TiCl ₄ gas 23 is introduced from one introduction pipe 22, NH ₃ gas 25 is introduced from the other introduction pipe 24, and both are mixed inside a cylindrical body 26,
The end face of the cylindrical body 26 is jetted from a blow-out hole 28 opened on the surface of the diffusion plate 27. The cylindrical body 26 is heated to about 250 ° C. An example of this type is disclosed in, for example, Japanese Patent Application Laid-Open
It is disclosed in Japanese Patent No. 64473.

[0005]

Problems to be Solved by the Invention TiN by CVD method
In forming the thin film, there are the following restrictions when the source gases TiCl ₄ and NH ₃ are mixed. Since TiCl ₄ has a low vapor pressure, it must be kept at a high temperature (boiling point above 136 ° C. at 1 atmosphere) until it is mixed. Further, after the mixing, there is a problem that impurities such as TiCl ₄ .2NH ₃ are generated at a certain temperature or lower. It is reported that the temperature at which these impurities are generated is 180 to 350 ° C. Therefore, if the temperature of the mixed gas is low, the above-mentioned impurities will adhere to the wall surface of the gas supply passage. Therefore, it is understood that it is better to supply these two kinds of gases separately and mix them just before film formation. Also,
When a film is formed on the contact hole, better coverage can be obtained when a chemical reaction occurs on the substrate surface. From this viewpoint as well, it is better to separately supply the two types of gas described above. .

However, if the gas reaches the substrate before the mixing has proceeded sufficiently, the non-uniform mixed gas comes into contact with the substrate, and the film quality becomes non-uniform even on the same substrate. .

The above-described gas diffusion device shown in FIG. 6 uses N ₂ gas as the nitrogen compound gas. If TiCl ₄ and NH ₃ are supplied using this gas diffusion device, the following problems occur. Since NH ₃ is more reactive than N ₂ , when the temperature of the comb pipe is low, TiCl ₄ and NH ₃ having a low vapor pressure react with each other in the vicinity of the gas blowing hole to generate an impurity, which is blown out. It may adhere to the holes and block the blowout holes. In addition, the comb-shaped piping structure has not solved the incompleteness of gas mixing.

In the gas diffusion device shown in FIG.
It is considered that Cl ₄ and NH ₃ are uniformly mixed inside the cylindrical body 26. However, the mixed gas is blocked by the diffusion plate 27. Depending on the temperature, the diffusion plate 27
There is a possibility that impurities or TiN may be formed in the film and block the blowing hole 28. Further, the amount of gas introduced and the amount of gas blown out may be the same, but when the amount of gas introduced is larger, the reaction product also precipitates inside. That is, the two kinds of gas may react inside the diffusion plate 27 before reacting on the substrate. Even if a measure such as heating the cylindrical body 26 and the diffusion plate 27 is taken, it is practically impossible because the temperature is limited and it is difficult to maintain it.

An object of the present invention is to provide a CVD apparatus in which two or more kinds of gases are separately supplied and which are uniformly diffused and mixed to reach a substrate, and a TiN thin film using this apparatus. It is to provide a forming method.

[0010]

[Means and Actions for Solving the Problems]

According to a first aspect of the present invention, in a CVD apparatus for introducing a plurality of types of gas into a reaction chamber and forming a film on a substrate supported by a substrate holder, a gas outlet for separating and blowing a plurality of types of gas is provided. A rotating blade is provided between the substrate holder and the substrate holder. The present invention can be applied to any type of CVD apparatus as long as it supplies two or more kinds of gases. For example, plasma CVD device, reduced pressure CV
It can be applied to a D apparatus, an atmospheric pressure CVD apparatus, a photo CVD apparatus and the like. The rotating blade may be of a type that is rotated by the flow of gas or a type that is rotated by power from the outside. When such a rotary blade is used, two or more kinds of gas discharged from the gas outlet are diffused and mixed by the blade and reach the substrate as a uniform mixed gas. Therefore, the quality of the formed film is also uniform. By supplying two or more kinds of gases separately from each other up to the position before the rotary blade, it is possible to avoid the inconvenience that would be caused by premixing the gases.

A second aspect of the invention is the same as the first aspect of the invention, in which the blade is rotated by blowing gas. In this way, if the blade is rotated using the flow of gas, it is not necessary to separately provide a device for rotationally driving the blade.

According to a third aspect of the present invention, in the second aspect of the invention, the blade is supported by a bearing device including a shaft whose tip portion is a rotary contact portion and a recessed portion which rotatably supports the tip portion of the shaft. It is something that is done. When the blade is rotated by using the flow of gas, the rotating torque received by the blade is not so large. Therefore, it is preferable that the bearing for rotatably supporting the blade has a frictional resistance during rotation as small as possible. When the tip of the shaft is supported by the concave portion as in the present invention, the area of the rotary contact portion is small, so that the blade can rotate with a small rotational torque.

A fourth invention is the mode according to the first invention.
The blade is made to rotate by a rotor.
When it is important to stably rotate the blade with a desired rotation torque, the blade can be rotated by the external motor as described above.

A fifth aspect of the present invention relates to a TiN thin film forming method by the CVD method, in which a titanium compound gas and a nitrogen compound gas are separately supplied to a reaction chamber, and these gases are supplied by a rotating blade. The TiN thin film is formed by mixing and forming a TiN thin film on the substrate by the CVD method. As the titanium compound gas, TiCl ₄ , CH ₃ TiCl ₃ ,
_{Ti (N (CH 3) 2} ) 4, Ti (N (C 2 H 5) 2) 4,
, And NH ₃ , NH ₄ , and N ₂ can be used as the nitrogen compound.

[0016]

FIG. 1 is a front sectional view of an embodiment of the present invention. This apparatus is a low pressure CVD apparatus for forming a TiN thin film. Inside the reaction chamber 30, there is a substrate holder 34 containing a heater 32, and a substrate 36 is attached to this substrate holder 34. Below the substrate holder 34 is a gas supply device 38. The gas supply device 38 includes a funnel-shaped peripheral wall 40 that extends upward, and the root of the peripheral wall 40 is connected to a cylindrical pipe 42 that extends downward. An inner tube 44 is concentrically arranged inside the cylindrical tube 42. A heater 46 is installed between the cylindrical tube 42 and the inner tube 44.

A rotary vane device 48 is provided in the center of the peripheral wall 40.
Are supported by an upper support rod 50 and a lower support rod 52. FIG. 2 is an enlarged front view of the rotary blade support device 48. Four blades 56 are fixed to the cylindrical boss 54. A shaft 57 is fixed to the upper surface of the boss 54.
The tip of 7 is sharp and is rotatably supported in a recess formed in a circular upper support 58. A shaft 62 is also fixed to the lower surface of the boss 54, and the tip of the shaft 62 is sharp and is rotatably supported in a recess formed in a conical lower support 64. That is, boss 5
4 is rotatably supported by a pair of upper and lower bearing devices, and the boss 54 rotates around a vertically extending rotation axis. The upper support 58 is the four upper support bars 50 shown in FIG.
The lower support 64 is fixed to the peripheral wall 40 by four lower support bars 52. FIG. 3 is a plan view of the gas supply device 38 seen from above. The four wings 56 and the four upper support bars 52 are clearly shown.

In FIG. 1, the distance from the gas supply device 38 to the substrate holder 34 is 6 to 10 cm, and the outer diameter of the peripheral wall 40 of the gas supply device 38 is about 13 cm. Figure 2
In, the dimension from the tip of the blade 56 to the tip of the blade on the opposite side (outer diameter of the entire rotary blade) is 6 to 7 cm, and the outer diameter of the upper support 58 is about 1 cm.

FIG. 4 is a front view showing the structure of a bearing device for supporting the boss 54 of the rotor device 48. In (A), the shaft 5 fixed to the upper surface of the boss 54 (see FIG. 2).
7 is rotatably supported by an upper support 58. The shaft 57 has a conical shape, and its tip is sharply pointed. A conical recess 60 is formed in the upper support 58, and the tip of the shaft 57 is in rotary contact with the bottom of the recess 60. The shaft 57 and the upper support 58 are in a state close to point contact, and the frictional resistance when the shaft 57 rotates is very small. The material of the tip portion of the shaft 57 and the recess 60 of the upper support 58 is preferably a material that has abrasion resistance and that generates little dust due to rotational contact. For example, stainless steel can be used.

FIG. 4A shows the bearing device between the shaft 57 fixed to the upper surface of the boss and the upper support 58. The shaft 62 fixed to the lower surface of the boss and the lower support are shown. Body 6
4 (see FIG. 2) has the same structure.

FIGS. 4B and 4C show a modified example of the bearing device. In (B), the tip of the shaft 57b is left in a sharp structure, and the bottom of the recess 60b is curved. In (C), the tip of the shaft 57c has a curved surface shape with a small radius of curvature, and the bottom of the recess 60c has a curved surface shape with a large radius of curvature.

In the rotary vane device shown in FIG. 2, the shaft is fixed to the boss 54 and the bearing device is constituted by forming the recesses in the supports 58 and 64. On the contrary, the boss 54 is formed.
The bearing device may be formed by forming recesses on the upper surface and the lower surface and fixing the shafts to the supports 58 and 64, respectively.

Next, using the CVD apparatus of this embodiment, Ti
A method of forming the N thin film will be described. In FIG. 1, 5 sccc of TiCl ₄ gas 66 is supplied between the cylindrical tube 42 and the inner tube 44.
Introduced at a flow rate of m, NH ₃ gas 68
Is introduced at a flow rate of 400 sccm. And reaction chamber 3
0 is a turbo molecular pump (exhaust speed 4000 liters /
Seconds) to evacuate the reaction chamber 30 to 300 mTo
Keep at rr vacuum. TiCl ₄ is maintained at a high temperature above the boiling point (136 ° C.) by the heater 46. Since it is under reduced pressure, the temperature does not have to be 136 ° C. or higher, but in this example, 2
It is heated to 00 ° C.

The two kinds of gas blown out from the cylindrical tube 42 collide with the blade 56 to rotate the blade 56. In this embodiment, when the gas is blown out at the above-mentioned flow rate at the pressure of 300 mTorr, the flow velocity becomes about 50 m / s, and the force of the gas colliding with the blade 56 at this time becomes 1 mgf / cm ² . As a result, the blades 56 rotate at tens to hundreds of rpm. Due to the rotation of the blades 56, the two kinds of gas diffuse and are sufficiently mixed with each other to reach the substrate 36. The use of such a rotary blade is effective in diffusing a small amount of TiCl ₄ gas into a large amount of NH ₃ gas.
The substrate 36 is heated to 600 ° C. by the heater 32, and two kinds of gases react on this substrate 36 to form a uniform thin film. Since the distance between the substrate 36 and the gas supply device 38 is as short as 6 cm, the gases are mixed and reach the substrate 36 immediately before film formation.

When the gas is rotationally mixed by the vanes 56,
The amount of gas decreases in the region directly above the central portion of the rotary vane device 48, but the mixed gas collects from the peripheral portion and becomes uniform by the time it reaches the substrate.

When the gas mixed by the blades 56 comes into contact with the low temperature upper support rod 50, impurities may be generated and adhere to the upper support rod 50. In order to prevent this, it is desirable to make the upper support rod 50 as thin as possible and to attach a heater to the upper support rod 50 to heat it.

FIG. 5A is a front sectional view of another embodiment of the present invention. In this embodiment, the rotor 70 is rotated by the motor 70 installed outside the reaction chamber 30. The motor 70 and the rotary vane device 72 can be connected by a rotation introduction machine for vacuum. Alternatively, a vacuum seal device such as a magnetic fluid seal device may be used between the output shaft of the motor 70 and the rotary blade device 72, and between the output shaft of the motor 70 and the reaction chamber 30. When the forced rotation method as in this embodiment is adopted, the rotation of the blade is stabilized, and the rotation speed of the blade can be controlled without depending on the gas flow rate. This is particularly effective when the gas flow rate is low. As shown in FIG. 5B, the TiCl ₄ gas 66 is supplied with two blow-off pipes 74 and 76.
The NH ₃ gas 68 is blown out from the other two blowoff pipes 78 and 80. Also in this embodiment, the four blowing tubes are heated by the heater.

[0028]

According to the present invention, since two or more kinds of gases are mixed by the rotating blade, two or more kinds of gases that cannot be mixed in advance are sufficiently mixed in the vicinity of the substrate and supplied to the substrate. There is an effect that can be. This makes it possible to form a thin film having excellent uniformity even when two or more kinds of gases that are separated and supplied are used.

[Brief description of drawings]

FIG. 1 is a front sectional view of an embodiment of the present invention.

FIG. 2 is an enlarged front view of a rotary blade device.

FIG. 3 is a plan view of a rotary blade device.

FIG. 4 is an enlarged front view of the bearing device.

FIG. 5A is a front sectional view of another embodiment of the present invention,
(B) is a BB line sectional view of (A).

FIG. 6 is a plan view of a conventional gas diffusion device.

FIG. 7 is a plan view showing another example of a conventional gas diffusion device.

[Explanation of symbols]

30 ... Reaction chamber 34 ... Substrate holder 36 ... Substrate 38 ... Gas supply device 42 ... Cylindrical tube 44 ... Inner tube 48 ... Rotating blade device 56 ... Blade 57, 62 ... Shaft 60 ... Recess 66 ... TiCl ₄ gas 68 ... NH ₃ gas 70 ... Motor

Claims (5)

[Claims] 1. A CVD apparatus for introducing a plurality of kinds of gases into a reaction chamber to form a film on a substrate supported by a substrate holder, the gas outlet for separating and blowing the plurality of kinds of gases, and the substrate holder. A CVD apparatus characterized in that a rotating blade is provided between the two. 2. The CVD apparatus according to claim 1, wherein the blade is rotated by blowing gas. 3. The blade is supported by a bearing device comprising a shaft having a tip portion as a rotary contact portion and a recessed portion for rotatably supporting the tip portion of the shaft. 2. The CVD apparatus described in 2. 4. The CVD apparatus according to claim 1, wherein the blade is rotated by a motor. 5. A TiN film for forming a TiN thin film on a substrate by a CVD method, wherein a titanium compound gas and a nitrogen compound gas are separately supplied to a reaction chamber, and these gases are mixed by a rotating blade. Thin film forming method.