JP3292171B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for manufacturing a semiconductor device including a step of depositing a titanium film on a semiconductor substrate and nitriding the titanium film.

[0002]

2. Description of the Related Art Conventionally, contacts on a semiconductor substrate
A Ti film is formed in a hole or via hole, and
There is a method for manufacturing a semiconductor device in which a film is nitrided. Due to a change in pattern layout on a semiconductor substrate, a reduction in power supply voltage, and an improvement in driving force, the contact surface is required to have an ohmic and low-resistance interface contact. In order to meet these demands, a barrier metal technology has been developed which is a technology for obtaining a thermally stable material capable of obtaining a low resistance contact with a shallow pn junction. The barrier metal technique aims at preventing an alloy reaction between a silicon substrate and Al and obtaining a low-resistance ohmic contact. The properties required as a barrier metal are that it is thermally stable and the alloying reaction does not easily proceed, the Schottky barrier height is low, the resistivity is low, and the reducing power for the native oxide film is large. No. Meet these requirements,
There is Ti as a material that can easily form a film and reduce the manufacturing cost. It is known that Ti easily reacts with W as it is to form WSi ₂ which is an intermetallic compound, and it is common to form a nitride film of Ti and use it in a laminated structure with Ti. When this TiN film is formed, unnecessary particles called particles are generated. If the particles adhere to the semiconductor substrate before the etching, the particles serve as a mask, and an etching residue occurs. Therefore, the processing of the wiring causes a short circuit, and causes a connection failure in the via hole. In this case, the yield decreases, and the reliability of the product also decreases.

Conventionally, a Ti film is deposited in a contact hole or a via hole on a semiconductor substrate, and H ₂ gas, N ₂ gas and Ar gas are introduced into a chamber in which the semiconductor substrate is installed. And the Ti film were nitrided. However, the nitridation method in which the H ₂ gas, the N ₂ gas, and the Ar gas are introduced into the chamber has a problem that the nitriding action is weak and the Ti film cannot be sufficiently nitrided.

In order to solve this problem, recently, N ₂ gas, NH ₃ gas and Ar gas are introduced into a chamber in which a semiconductor substrate is installed, and a Ti film is formed by a plasma nitriding method. There is a method of nitriding.

According to the nitriding method of introducing the N ₂ gas, the NH ₃ gas and the Ar gas into the chamber, the nitriding action is strong and the Ti film can be sufficiently nitrided.

However, the N ₂ gas, NH ₃ gas and Ar
In the nitridation method in which gas is introduced into the chamber, a new problem has arisen in that the Ti nitride film peeled off from the inner wall of the chamber, the showerhead, or the like falls on the semiconductor substrate as particles and hinders the operation of the semiconductor.

Therefore, a method of nitriding a titanium film intended to reduce particles which fall on a semiconductor substrate and hinder the operation of the semiconductor is disclosed in Japanese Patent Laid-Open No. 10-10 / 1998.
In 6974, a titanium film is formed by performing a plasma treatment under an atmosphere of hydrogen gas and nitrogen gas on the surface of the titanium film to form a titanium nitride film. A method is disclosed. According to the method disclosed in Japanese Patent Application Laid-Open No. H10-106974, the nitridation effect is strong to some extent.
There is a possibility that the i-film can be sufficiently nitrided and particles can be reduced to some extent.

[0008]

SUMMARY OF THE INVENTION However, Japanese Patent Laid-Open No.
In the method for continuously forming a titanium film and a titanium nitride film described in JP-A-106974, the problem of reducing the number of particles falling from a chamber or the like onto a semiconductor substrate in the process of nitriding the titanium film is still solved. However, the fact that particles fell from the inner wall of the chamber or the shower head onto the semiconductor substrate and hindered the operation of the semiconductor was still recognized.

In view of the above-mentioned problems in the prior art, the present invention reduces the particles generated in the step of depositing a titanium film on a semiconductor substrate and nitriding the titanium film to ensure that the semiconductor device operates normally. It is an object of the present invention to provide a method of manufacturing a semiconductor device configured as described above.

[0010]

Accordingly, the present invention provides a first
To, by flowing TiCl ₄ gas and Ar gas and H ₂ gas from the showerhead in the chamber, a Ti film is deposited on the semiconductor substrate, H ₂ from the showerhead in the chamber
In a method of supplying a gas, an NH ₃ gas, and an Ar gas and nitriding a Ti film by a plasma nitridation method, T is introduced into the chamber from one of the first gas supply hole and the second gas supply hole.
flowing a mixed gas of iCl ₄ gas and Ar gas and flowing H ₂ gas into the chamber from the other gas supply hole to deposit a Ti film in the chamber; a first gas supply hole and a second gas A step of flowing a mixed gas of H ₂ gas and NH ₃ gas into the chamber from one of the supply holes, and flowing an Ar gas into the chamber from the other gas supply hole to nitride the Ti film deposited in the chamber. The above problem is solved by a method of manufacturing a semiconductor device characterized by the above-mentioned.

Therefore, according to the method of manufacturing a semiconductor device according to the first aspect of the present invention, when nitriding the Ti film, by employing H ₂ instead of N ₂ , the hydrogen is deposited when the Ti film is deposited. Discharges chlorine mixed into the Ti film
Since the H ₃ gas is in a plasma state, the Ti film can be nitrided, and after the step of nitriding the Ti film, the Ti nitride film is less likely to be peeled off from the showerhead, the inner wall of the chamber, and the like. It is possible to reduce the number of attached particles.

Further, by supplying a mixed gas of Ar gas, H ₂ and NH ₃ for diluting the plasma concentration in the chamber from different gas supply holes, the plasma concentration in the chamber can be easily adjusted to a desired concentration. Can be. This makes it difficult for the Ti nitride film to peel off from the shower head and the inner wall of the chamber after the step of nitriding the Ti film, and it is possible to reduce the number of particles adhering on the semiconductor substrate.

The present invention, in the second, by flowing a TiCl ₄ gas and Ar gas and _{H 2} gas from the showerhead in the chamber, a Ti film is deposited on the semiconductor substrate, _{H 2} from the showerhead in the chamber In a method of supplying a gas, an NH ₃ gas, and an Ar gas, and nitriding a Ti film by a plasma nitridation method, a first gas supply hole and a second gas supply hole without a semiconductor substrate installed in the chamber. A mixed gas of TiCl ₄ gas and Ar gas is flowed into the chamber from one side, and H gas is introduced into the chamber from the other gas supply hole.
₍₂₎ flowing a Ti gas to deposit a Ti film in the chamber; and (2) supplying H ₂ gas into the chamber from one of the first gas supply hole and the second gas supply hole in a state where the semiconductor substrate is not installed in the chamber. A step of flowing a mixed gas of a gas and an NH ₃ gas and flowing an Ar gas into the chamber from the other gas supply hole to nitride the Ti film adhered to the chamber, and a state in which a semiconductor substrate is installed in the chamber Then, a mixed gas of TiCl ₄ gas and Ar gas flows into the chamber from one of the first gas supply hole and the second gas supply hole, and H ₂ gas flows into the chamber from the other gas supply hole. Depositing a Ti film on a semiconductor substrate;
With the semiconductor substrate installed in the chamber, the first
A mixed gas of H ₂ gas and NH ₃ gas flows into the chamber from one of the gas supply hole and the second gas supply hole, and an Ar gas flows into the chamber from the other gas supply hole to form a Ti film in the chamber. And a step of nitriding a Ti film on a semiconductor substrate.

Therefore, according to the method of manufacturing a semiconductor device according to the _{second aspect} , when nitriding the Ti film, by employing H ₂ instead of N ₂ , the hydrogen is deposited when the Ti film is deposited. Discharges chlorine mixed into the Ti film
Since the H ₃ gas is in a plasma state, the Ti film can be nitrided, and after the step of nitriding the Ti film, the Ti nitride film is less likely to be peeled off from the showerhead, the inner wall of the chamber, and the like. It is possible to reduce the number of attached particles.

Further, by supplying a mixed gas of Ar gas, H ₂ and NH ₃ for diluting the plasma concentration in the chamber from different gas supply holes, the plasma concentration in the chamber can be easily adjusted to a desired concentration. Can be. This makes it difficult for the Ti nitride film to peel off from the shower head and the inner wall of the chamber after the step of nitriding the Ti film, and it is possible to reduce the number of particles adhering on the semiconductor substrate.

Further, a step of depositing a Ti film in the chamber without placing the semiconductor substrate in the chamber; and a step of nitriding the Ti film adhered in the chamber without placing the semiconductor substrate in the chamber. A step of depositing a Ti film on the semiconductor substrate and a step of nitriding the Ti film on the semiconductor substrate. In the step of nitriding, the stress of the TiN film is reduced, the TiN film is less likely to be peeled from the showerhead or the chamber, and the number of particles generated in the chamber can be suppressed.

According to a third aspect of the present invention, each gas is supplied from a first gas supply hole and a second gas supply hole which are arranged uniformly on a surface. Therefore, even if the gas is supplied from different holes of the first gas supply hole and the second gas supply hole, the respective gases are easily mixed.

According to a fourth aspect of the present invention, each gas is supplied from a first gas supply hole and a second gas supply hole arranged alternately. Therefore, similarly, even if the gas is supplied from different holes of the first gas supply hole and the second gas supply hole, the respective gases are easily mixed.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A method for manufacturing a semiconductor device according to an embodiment of the present invention will be described with reference to FIGS.

In the plasma CVD apparatus used in the titanium film nitriding step according to the present embodiment, an upper electrode / gas supply section 2 is provided on the upper surface of a chamber 1 and a high frequency power 7 is supplied to the upper electrode / gas supply section 2. The wires are connected. A gas line A (8) and a gas line B (9) are connected to the upper electrode / gas supply unit 2, and the gas line A (8) and the gas line B (9) are connected to the inside of the chamber 1 from outside. Is supplied with a mixed gas. Gas lines A and B in chamber 1
Gas lines A and B for supplying gas via (8, 9)
At the end of (8, 9), a shower head 10 is installed. Below the showerhead 10, a resistance heater 4 grounded 6 is provided, and a semiconductor substrate 3 on which a Ti film is deposited and the Ti film is nitrided is provided on the resistance heater 4. An exhaust line 5 for exhausting gas in the chamber is connected to the bottom surface or side surface of the chamber 1. (FIG. 1A) Also, the shower head 10 installed in the upper electrode and the gas supply unit 2
In order to facilitate mixing of the gas supplied into the chamber 1 via the gas line A (8) and the gas line B (9), the gas supply hole of the gas line A (8) and the gas line B The gas supply holes of the gas line A (8) and the gas supply holes of the gas line B (9) are alternately arranged so that the positions of the gas supply holes and the gas supply holes of the gas line B (9) are uniform on the surface. Installed (FIG. 1B).

Next, a process of depositing a Ti film on the semiconductor substrate 3 and nitriding the Ti film will be described with reference to FIGS. First, a Ti film is deposited on the semiconductor substrate 3. The step of depositing a Ti film on the semiconductor substrate 3 is the same as the conventional technique. That is, a gas mixture of TiCl ₄ and Ar is supplied to the gas line A (8),
The H ₂ gas is supplied to (9), and the mixed gas is introduced into the chamber 1. Further, high-frequency power 7 is supplied to the upper electrode and the gas supply unit 2 to bring the mixed gas introduced into the chamber 1 into a plasma state. Thus, a Ti film is deposited on the semiconductor substrate 3 (FIG. 4A). Also, the shower head 10 is made of Ti, like the semiconductor substrate 3.
A film is deposited (FIG. 4B). In addition, a Ti film is deposited on the inner wall of the chamber 1 and the like, similarly to the semiconductor substrate 3 and the showerhead 10.

Next, the Ti film deposited on the semiconductor substrate 3 is nitrided in the same chamber 1 where the Ti film is deposited. An Ar gas is supplied to the gas line A (8), and a mixed gas of H ₂ and NH ₃ is supplied to the gas line B (9), thereby introducing these mixed gases into the chamber 1. . By setting the component of the gas mixture in the gas line B (9) to H ₂ , T 2
Chlorine contained in the Ti film can be discharged from the Ti nitride film in the Ti film deposition step without excessively nitriding the i film. This makes it difficult for the Ti nitride film to peel off from the shower head and the inner wall of the chamber after the step of nitriding the Ti film, and it is possible to reduce the number of particles adhering on the semiconductor substrate. Next, the high-frequency power 7 is supplied to the upper electrode and the gas supply unit 2 to bring the mixed gas introduced into the chamber 1 into a plasma state. As a result, the Ti film deposited on the semiconductor substrate 3 is nitrided by nitrogen atoms contained in the gas mixture of H ₂ and NH ₃ (FIG. 1A). Also, a Ti film deposited on the shower head 10 in the same manner as the semiconductor substrate 3 is nitrided (FIG. 1).
(B)). In addition, a Ti film deposited on the inner wall of the chamber 1 and the like in the same manner as the semiconductor substrate 3 and the showerhead 10 is nitrided.

[0023]

EXAMPLE Next, a method of manufacturing a semiconductor device according to an example of the present invention, and a conventional example of a conventional N ₂ gas, NH ₃ gas and Ar
Referring to FIG. 2, the number of particles in the chamber 1 is compared with a step of introducing a gas into a chamber in which a semiconductor substrate is installed and a step of nitriding a Ti film using a plasma nitridation method. As shown in FIG. 2, before the semiconductor substrate 3 is installed in the chamber 1, after the precoat for adjusting the atmosphere in the chamber 1, the number of particles generated in the chamber 1 becomes 20 or less in this embodiment. . here,
As a specific precoating process, a considerable amount of titanium film deposition and titanium film nitridation for processing 36 semiconductor substrates without the semiconductor substrate 3 are performed. Further, in this embodiment, the number of particles generated in the chamber 1 becomes 20 or less even after performing the titanium film deposition and the titanium film nitridation processing for 25 semiconductor substrates 3. Further, even after performing the titanium film deposition and the titanium film nitriding treatment for 500 semiconductor substrates 2,
In this embodiment, the number of particles generated in the chamber 1 can be suppressed to 50 or less. On the other hand, in the step of introducing the N ₂ gas, the NH ₃ gas, and the Ar gas into the chamber in which the semiconductor substrate is installed in the comparative example, and nitriding the Ti film using the plasma nitriding method, The number of particles generated in the chamber 1 after the pre-coating for adjusting the atmosphere in the chamber 1 before placing the particles in the chamber 1 is 1000 or more. Further, even after performing the titanium film deposition and the titanium film nitriding treatment for 25 semiconductor substrates 2, the number of particles generated in the chamber 1 is 1000 or more in the comparative example. As is clear from the above Examples and Comparative Examples,
If the titanium film is nitrided using the manufacturing method of the present invention, the conventional N ₂ gas, NH ₃ gas and Ar gas are introduced into a chamber in which the semiconductor substrate is installed, and the Ti film is formed using the plasma nitriding method. The number of particles generated in the chamber 1 can be reduced to 1/50 at the maximum as compared with the case where the method of nitriding the film is used to nitride the titanium film. The reason why the number of particles generated in the chamber 1 can be reduced by performing the titanium film nitriding treatment of the present invention as described above is recognized as follows. That is, in the present embodiment, the Ti film in the nitriding process absorbs hydrogen, thereby reducing the stress of the Ti nitride film, making it difficult for the Ti nitride film to peel off from the shower head 10 or the chamber 1, and Since the mixed gas supplied to B (9) is H2 and NH3 and the number of nitrogen atoms with respect to hydrogen atoms is reduced as compared with the conventional method, an appropriate nitriding strength can be obtained as a Ti nitride film deposited on the semiconductor substrate 3. In addition, the Ti nitride film does not easily peel off.

As described above, a semiconductor substrate is placed in a chamber, a TiCl ₄ gas is introduced, a Ti film is deposited on the semiconductor substrate by a plasma CVD method, and then H ₂ gas and NH are substantially contained in the chamber. _A semiconductor device obtained by introducing only ₃ gases and an Ar gas and nitriding a Ti film by a plasma nitridation method, wherein the amount of chlorine contained in the Ti nitride film is 10 ²¹ atoms / cm ³ or less. Accordingly, when depositing the Ti film, hydrogen mixed with the Ti film is discharged, and the NH ₃ gas is turned into a plasma state, whereby the Ti film can be nitrided. After the step of nitriding the Ti film, It is difficult for the TiN film to be peeled off from the showerhead and the inner wall of the chamber and the like, whereby the number of particles adhering on the semiconductor substrate can be reduced. . Further, the etching residue due to particles is reduced, the occurrence of short circuit due to wiring processing can be reduced, and connection failure of wiring can hardly occur. Therefore, it is possible to provide a semiconductor device in which the yield of semiconductor device products and the reliability of the products are improved.

[Brief description of the drawings]

FIG. 1 is a schematic view showing a titanium film nitriding step by a method of manufacturing a semiconductor device according to an embodiment of the present invention.
(A) It is a cross-sectional schematic diagram of a CVD chamber. (B)
It is an enlarged view of the surface of an upper electrode.

FIG. 2 is a diagram illustrating the number of particles when a method of manufacturing a semiconductor device according to an embodiment of the present invention is employed and the number of particles according to a comparative example.

FIG. 3 is a schematic view showing an apparatus for depositing and nitriding a titanium film according to an embodiment of the present invention. (A)
It is a cross section of a CVD chamber. (B) It is an enlarged view of the upper electrode surface.

FIG. 4 is a schematic view showing a titanium film deposition step by a method for manufacturing a semiconductor device according to an embodiment of the present invention.
(A) It is a cross-sectional schematic diagram of a CVD chamber. (B)
It is an enlarged view of the surface of an upper electrode.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chamber 2 Upper electrode and gas supply part 3 Semiconductor substrate 4 Resistance heater 5 Exhaust line 6 Ground 7 High frequency power 8 Gas line A 9 Gas line B 10 Shower head

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/285 301 H01L 21/285 C23C 14/06 C23C 16/14 H01L 21/3205

Claims (4)

(57) [Claims] (1)Ti from the shower head in the chamber
Cl ₄ Gas, Ar gas and H ₂ Let the gas flow,Semiconductor substrate
Deposit a Ti film on top,H from the shower head in the chamber ₂ Gas and NH
₃ Supply gas and Ar gas, By plasma nitriding, T
Nitriding the i-filmIn the method, A channel is formed from one of the first gas supply hole and the second gas supply hole.
TiCl in the chamber ₄ Flow of mixed gas of gas and Ar gas
And H is introduced into the chamber through the other gas supply hole. ₂ Flowing gas
Depositing a Ti film in the chamber, A channel is formed from one of the first gas supply hole and the second gas supply hole.
H in the member ₂ Gas and NH ₃ Flow gas mixture
Ar gas is flowed into the chamber from one of the gas supply holes,
A step of nitriding the Ti film adhered in the chamber.
M A method for manufacturing a semiconductor device, comprising: (2)Ti from the shower head in the chamber
Cl ₄ Gas, Ar gas and H ₂ Let the gas flow,Semiconductor substrate
Deposit a Ti film on top,H from the shower head in the chamber ₂ Gas and NH
₃ Supply gas and Ar gas, By plasma nitriding, T
Nitriding the i-filmIn the method, In a state where the semiconductor substrate is not installed in the chamber,
Change the channel from one of the first gas supply hole and the second gas supply hole.
TiCl in bar ₄ Flowing a mixed gas of gas and Ar gas,
H was introduced into the chamber from the other gas supply hole. ₂ Let the gas flow
Depositing a Ti film in the chamber; In a state where the semiconductor substrate is not installed in the chamber,
Change the channel from one of the first gas supply hole and the second gas supply hole.
H in the bar ₂ Gas and NH ₃ Flow a gas mixture,
Ar gas is flowed into the chamber from the gas supply hole of
Nitriding the Ti film deposited in the chamber; With the semiconductor substrate installed in the chamber, the first
Chamber from one of the gas supply hole and the second gas supply hole.
In the TiCl ₄ Flow a gas mixture of gas and Ar gas,
H into the chamber through the gas supply hole ₂ Let the gas flow,
The semiconductor substrate Depositing a Ti film thereon; With the semiconductor substrate installed in the chamber, the first
Chamber from one of the gas supply hole and the second gas supply hole.
H inside ₂ Gas and NH ₃ Flow a gas mixture and the other
Ar gas was flowed into the chamber from the gas supply hole to
Nitriding Ti film in chamber and Ti film on semiconductor substrate
Including process A method for manufacturing a semiconductor device, comprising: 3. A first gas arranged so as to be uniform on a surface.
Each gas is charged from the supply hole and the second gas supply hole.
The semiconductor device according to claim 1, wherein the semiconductor device is supplied into a member.
Manufacturing method . 4. The method according to claim 1 , wherein the first gas supply holes are arranged alternately.
Each gas from the second gas supply hole into the chamber
The method of manufacturing a semiconductor device according to claim 1, wherein the semiconductor device is supplied.
Law .