JP2000277459A - Titanium film nitriding method and semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely reduce particles easy to occur in a process for nitriding a titanium film, by depositing a Ti film on a semiconductor substrate, then introducing only, substantially, H2 gas, NH3 gas, and Ar gas into a chamber, for nitriding the Ti film by a plasma nitriding method. SOLUTION: In the same chamber 1 as where a Ti film is deposited, the Ti film deposited on a semiconductor substrate 3 is nitrided,a gas line A8 is supplied with Ar gas while a gas line B9 supplied with a mixed gas of H2 gas and NH3, and the mixed gas of them is introduced into the chamber 1. With the content of the mixed gas in the gas line B9 being H2, no Ti film is excessively nitrided in the process where it is nitrided while the chlorine contained in the Ti film is discharged from a nitride Ti film in a Ti film deposition process. Thus, on and after the process for nitriding the Ti film, the nitride Ti film is difficult to peel off the inside wall of the chamber and shower head, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device, and more particularly to a method of nitriding a titanium film by 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,
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 technology aims to prevent an alloy reaction between a silicon substrate and Al and obtain 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 height of the Schottky barrier 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 production cost. It is known that Ti easily reacts with W to form WSi ₂ which is an intermetallic compound as it is, and it is common to form a Ti nitride film 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. For this reason, the wiring processing causes a short circuit, and causes a connection failure in a via hole. This reduces the yield and product reliability.

Conventionally, a Ti film is deposited on a contact hole or 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. , Ti film was nitrided. However, the nitriding 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 plasma nitridation. There is a method of nitriding.

According to the nitriding method in which the N ₂ gas, the NH ₃ gas and the Ar gas are introduced 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 arises in that the Ti nitride film peeled off from the inner wall of the chamber, the shower head, or the like falls as particles on the semiconductor substrate 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 Application Laid-Open No. 10-10 / 1998.
In 6974, a titanium film is formed by performing a plasma treatment on the surface of the titanium film in an atmosphere of hydrogen gas and nitrogen gas 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]

However, Japanese Patent Laid-Open Publication No.
In the method of 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 is directed to a method of depositing a titanium film on a semiconductor substrate, and reliably reducing particles generated in a step of nitriding the titanium film, so that the semiconductor device can operate normally. It is an object to provide a film nitriding method and a semiconductor device.

[0010]

According to a first aspect of the present invention, there is provided a method for nitriding a titanium film, comprising the steps of: placing a semiconductor substrate in a chamber, depositing a Ti film on the semiconductor substrate; And only H ₂ gas, NH ₃ gas, and Ar gas are introduced into the furnace.
It is characterized in that the film is nitrided.

Therefore, according to the method for nitriding a titanium film of the first invention of the present application, when the Ti film is deposited, the chlorine mixed into the Ti film is discharged, and the NH ₃ gas is brought into a plasma state. The Ti film can be nitrided, and after the step of nitriding the Ti film, it becomes difficult for the Ti nitride film to be peeled off from the shower head and the inner wall of the chamber, thereby reducing the number of particles adhering to the semiconductor substrate. become.

The capacitor for a semiconductor device according to the second aspect of the present invention is the capacitor for a semiconductor device according to the first aspect of the present invention, wherein the H ₂ gas and the NH ₃ gas are introduced into the chamber as a mixed gas. It is characterized by the following.

Therefore, according to the titanium film nitriding method of the second invention of the present application, NH ₃ gas for nitriding the Ti film and H ₂ for optimizing the degree of nitriding of the Ti nitride film formed on the inner wall of the chamber and the showerhead. When the NH ₃ gas and the H ₂ gas are turned into plasma by mixing the gases,
H ₃ and H ₂ can be brought into a more uniform plasma state, and after the step of nitriding the Ti film, it becomes difficult for the Ti nitride film to peel off from the shower head and the inner wall of the chamber. It is possible to reduce the number of particles adhering to the substrate.

According to a third aspect of the present invention, there is provided a method for nitriding a titanium film according to the first or second aspect of the present invention, wherein the mixed gas of H ₂ and NH ₃ is supplied to a predetermined hole of a shower head in a chamber. And an Ar gas is introduced into the chamber from a hole different from the predetermined hole.

Therefore, according to the method for nitriding a titanium film of the third invention of the present application, the hole in the chamber is made different from the mixed gas of Ar gas, H ₂ and NH ₃ for diluting the plasma concentration in the chamber. This makes it easier to set the plasma concentration of the Ti film to a desired concentration, which makes it difficult for the Ti nitride film to be peeled off from the showerhead and the inner wall of the chamber after the step of nitriding the Ti film. It is possible to reduce the number of particles to be generated.

According to a fourth aspect of the present invention, in the method for nitriding a titanium film according to the first to third aspects of the present invention, the plasma nitriding is performed by a plasma nitriding method using high frequency power.
It is characterized by nitriding the i film. According to a fifth aspect of the present invention, there is provided a method of nitriding a titanium film according to the first to fourth aspects of the present invention, wherein the plasma nitridation method comprises the step of:
It is characterized in that it is performed in an apparatus.

Therefore, according to the method for nitriding a titanium film according to the fourth invention or the fifth invention of the present application, it is possible to generate a sufficiently converted plasma gas in the chamber by using high-frequency power.

In the semiconductor device according to the sixth aspect of the present invention, a semiconductor substrate is set 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 substantially in the chamber. H ₂ gas and NH ₃
Gas and Ar gas alone are introduced and T
What is claimed is: 1. A semiconductor device obtained by a step of nitriding an i film, wherein the amount of chlorine contained in the Ti nitride film is 10 ²¹ atoms.
/ Cm ³ or less.

Therefore, in the semiconductor device according to the sixth aspect of the present invention, when the Ti film is nitrided, the H ₂ in the plasma state is formed.
Acts on the Ti film that is being nitrided, thereby discharging chlorine from the Ti nitride film, which facilitates the peeling of the Ti nitride film from the inner wall of the chamber, the showerhead, and the like.
The film is obtained in a state where the amount of chlorine contained in the film is 10 ²¹ atoms / cm ³ or less. As a result, after the step of nitriding the Ti film, the Ti nitride film is less likely to be peeled off from the showerhead and the inner wall of the chamber, and the number of particles adhering to the semiconductor substrate can be reduced. In addition, the etching residue due to particles is reduced, the occurrence of short circuit due to wiring processing can be reduced, and it is possible to hardly cause poor connection of wiring. 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.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A titanium film nitriding method and 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 method according to the present embodiment, an upper electrode / gas supply unit 2 is provided on the upper surface of a chamber 1 and a transmission line for supplying high frequency power 7 to the upper electrode / gas supply unit 2 is connected. Is done. A gas line A (8) and a gas line B
(9) is connected, and a mixed gas is supplied into the chamber 1 from the outside via the gas line A (8) and the gas line B (9). Gas lines A and B in chamber 1
Gas lines A and B for supplying gas through (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 installed, and a semiconductor substrate 3 on which a Ti film is deposited and the Ti film is nitrided is installed 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. 1 (A)) In addition, the shower head 10 installed in the upper electrode and the gas supply unit 2 is supplied into the chamber 1 via a gas line A (8) and a gas line B (9). In order to facilitate mixing of the gas, the positions of the gas supply holes of the gas line A (8) and the gas supply holes of the gas line B (9) are alternately arranged on the shower head 10 so as to be uniform on the surface. A gas supply hole of the gas line A (8) and a gas supply hole of the gas line B (9) are installed in FIG.
(B)).

Next, a method 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 method 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. 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
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. As a result, after the step of nitriding the Ti film, the Ti nitride film is less likely to be peeled off from the showerhead and the inner wall of the chamber, and the number of particles adhering to the semiconductor substrate can be reduced. 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. Thus, 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 in the same manner as the semiconductor substrate 3 and the showerhead 10 is nitrided.

[0023]

Next, a method of nitriding a titanium film according to an embodiment of the present invention will be described.
And the conventional N₂Gas and NH₃Gas and Ar gas
The body is introduced into the chamber where the semiconductor substrate is installed
And using a plasma nitriding method to nitride the Ti film
And the number of particles in chamber 1 with reference to FIG.
To compare. As shown in FIG.
Atmosphere adjustment in chamber 1 before installing in chamber 1
After the pre-coating, the
In this embodiment, the number of articles is 20 or less. here
First, as a specific precoating process, the semiconductor substrate 2
Titanium equivalent to process 36 semiconductor substrates in the absence
Film deposition and titanium film nitridation are performed. Also, the semiconductor substrate 2 is
After performing titanium film deposition and titanium film nitriding treatment for 5 sheets
In this embodiment, the particles generated in the chamber 1
The number of files becomes 20 or less. Further, the semiconductor substrate 2 is
After performing titanium film deposition and titanium film nitridation
In this embodiment, the particles generated in the chamber 1
The number of files can be reduced to 50 or less. Against this
And N of the comparative example₂Gas and NH₃Gas and Ar gas are semiconductive
Plasma is introduced into the chamber where the body substrate is installed.
In the method of nitriding a Ti film using a nitriding method, a semiconductor substrate is used.
Before installing the plate 3 in the chamber 1,
After pre-coating to adjust the atmosphere,
The number of generated particles is 1000 or more. Ma
In addition, titanium film deposition and titanium film deposition for 25 semiconductor substrates 2 were performed.
In the comparative example, even after the
The number of generated particles is 1000 or more. Less than
It is clear from the above examples and comparative examples.
As described above, the titanium film is formed using the titanium film nitriding method of the present invention.
By nitriding, the conventional N₂Gas and NH₃Gas and Ar gas
Into the chamber where the semiconductor substrate is
A method of nitriding the Ti film using the plasma nitriding method was adopted.
In the chamber 1 when nitriding the titanium film
Reduce the number of particles generated by up to 1/50
It becomes possible. Thus, the titanium film nitriding treatment of the present invention
Generation of particles in chamber 1
The reason why the number can be kept low is as follows.
Is recognized. That is, in the present embodiment, Ti
The film absorbs the hydrogen, and the Ti nitride film
The TiN film is reduced by the shower head 10
It is difficult to separate from the inside of the bar 1 and the gas line B
The mixed gas supplied to (9) is H ₂And NH₃As hydrogen
Reduced the number of nitrogen atoms per atom compared to conventional methods
Is suitable as a Ti nitride film deposited on the semiconductor substrate 3.
High nitridation strength, and the nitrided Ti film
It becomes hard.

As described above, a semiconductor substrate is set 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 a process of nitriding a Ti film by a plasma nitriding method by introducing only _three gases and an Ar gas, 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, the chlorine mixed in 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 becomes difficult for the TiN film to be peeled off from the shower head and the inner wall of the chamber, thereby making it possible to reduce the number of particles adhering on the semiconductor substrate. . In addition, the etching residue due to particles is reduced, the occurrence of short circuit due to wiring processing can be reduced, and it is possible to hardly cause poor connection of wiring. 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 method and a titanium film nitriding step of 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 upper electrode surface.

FIG. 2 is a diagram showing the number of particles of a titanium film nitriding method and a semiconductor device according to an example of the present invention and the number of particles of 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-sectional schematic diagram 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 nitriding method and a titanium film depositing step of 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 upper electrode surface.

[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

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/3205 H01L 21/88 MF Term (Reference) 4K029 AA06 AA24 BA17 BA60 CA04 CA13 DD02 4K030 AA03 AA16 BA18 CA04 CA12 EA03 FA03 KA20 4M104 BB30 DD44 DD45 DD86 5F033 HH33 PP04 PP12 QQ90 QQ98 WW04 XX00

Claims (6)

[Claims] 1. A semiconductor substrate is placed in a chamber, a Ti film is deposited on the semiconductor substrate, and then substantially only H ₂ gas, NH ₃ gas and Ar gas are introduced into the chamber, and plasma nitriding is performed. And nitriding a Ti film. 2. The method according to claim 1, wherein the H ₂ gas and the NH ₃ gas are introduced into the chamber as a mixed gas. _3. A method of introducing a mixed gas of H ₂ and NH ₃ from a predetermined hole of a shower head in a chamber, and introducing an Ar gas into the chamber from a hole different from the predetermined hole. The titanium film nitriding method according to claim 1 or 2, wherein 4. The method according to claim 1, wherein the plasma nitriding includes nitriding the Ti film by a plasma nitriding method using high frequency power. 5. The method according to claim 1, wherein the plasma nitriding method is a parallel plate CVD method.
(Chemical Vapor Deposition
The method according to any one of claims 1 to 4, wherein the method is performed by an apparatus (n: chemical vapor deposition). 6. A semiconductor substrate is set in a chamber, and T
An iCl ₄ gas is introduced, a Ti film is deposited on the semiconductor substrate by a plasma CVD method, and then substantially only a H ₂ gas, an NH ₃ gas and an Ar gas are introduced into the chamber, and the Ti film is formed by a plasma nitriding method. A semiconductor device obtained by a nitriding step, wherein the amount of chlorine contained in the Ti nitride film is 10 ²¹ atoms / cm ³ or less.