JP3225706B2 - Method of forming barrier metal layer in semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming a barrier metal layer in a semiconductor device, and more particularly, to a method for forming a barrier metal layer formed by a chemical vapor deposition method.

[0002]

2. Description of the Related Art A large number of through holes or via holes (hereinafter, also referred to as connection holes) are formed in a semiconductor device. Usually, this connection hole forms an insulating layer on an impurity diffusion region formed on a semiconductor substrate or on various electrodes, or forms an insulating layer on a lower insulating layer provided on a semiconductor substrate and having a lower wiring layer formed thereon. It is formed by forming an opening in the insulating layer, and then embedding a metal wiring material in the opening. With the increase in the degree of integration of semiconductor devices, the dimensional rules of the semiconductor manufacturing process are becoming finer, and a technique for filling an opening having a high aspect ratio with a metal wiring material has become an important issue. Note that the semiconductor substrate on which the impurity diffusion regions and various electrodes are formed, or the lower insulating layer on which the lower wiring layer is formed, will hereinafter be collectively referred to as a base.

As a method of filling the openings with a metal wiring material, a sputtering method using pure aluminum or an aluminum alloy (hereinafter, also referred to as an Al-based alloy) is generally employed. However, in this sputtering method,
As the aspect ratio of the opening increases, spatter particles made of an Al-based alloy become less likely to deposit on the bottom of the opening or on the side wall of the opening due to the so-called shadowing effect. Here, the shadowing effect refers to a phenomenon in which sputter particles made of an Al-based alloy are hardly deposited on an optically shadowed portion formed on a side wall or a bottom of an opening.
As a result, there is a problem that the step coverage of the Al-based alloy on the bottom of the opening or on the side wall of the opening in the vicinity thereof deteriorates, and disconnection failure easily occurs in such a portion.

As means for solving such a problem, a so-called blanket CVD method, a high-temperature aluminum sputtering method or an aluminum reflow method has been receiving attention.

[0005] In the blanket CVD method, as shown in FIG.
For example, a tungsten layer 114 is deposited by chemical vapor deposition (CVD) on the insulating layer 104 formed on the insulating layer 104 and in the opening 106 formed in the insulating layer 104 (FIG. A)). After that, the insulating layer 104
The tungsten layer 114 formed on the substrate is etched back and removed. As a result, a connection hole in which the metal plug 116 made of tungsten is formed in the opening 106 is completed (see FIG. 4B). Such a method is hereinafter referred to as a tungsten blanket CVD method.
In FIG. 4, reference numeral 102 denotes an impurity diffusion region formed on the semiconductor substrate.

When a tungsten layer is formed by a tungsten blanket CVD method, it is necessary to form a barrier metal layer having a two-layer structure of, for example, a Ti layer 110 / TiN layer 112 from below the tungsten layer. The tungsten layer formed by the tungsten blanket CVD method has excellent step coverage, but has poor adhesion to the insulating layer 104 due to a difference in internal stress at the interface between the different material layers. Therefore, to improve the adhesion, TiN
A layer 112 is formed. Further, in order to reduce the resistance between the TiN layer 112 and the impurity diffusion region 102, the Ti layer 1
Form 10. These Ti layer 110 and TiN layer 1
12 is usually formed by, for example, a bias sputtering method.

In the high-temperature aluminum sputtering method,
FIG. 5 shows a schematic partial cross-sectional view of the semiconductor element.
The base 10 is placed on the insulating layer 104 formed on the base 100 and in the opening 106 formed in the insulating layer 104.
0 is heated to a high temperature (for example, about 500 ° C.)
The Al-based alloy layer 124 is formed by a sputtering method.
Upper wiring layer 126 made of an Al-based alloy on insulating layer 104
To form Since the base 100 is heated to a high temperature,
The Al-based alloy deposited on the insulating layer 104 enters a fluid state and flows into the opening 106. Thereby, the opening 10
6 is reliably filled with an Al-based alloy to form a connection hole. In FIG. 5, reference numeral 102 denotes an impurity diffusion region. A high-temperature bias sputtering method in which high-temperature sputtering is performed while applying a bias voltage to a semiconductor substrate or the like is also included in the high-temperature aluminum sputtering method in this specification. These are collectively referred to simply as high-temperature aluminum sputtering.

[0008] In the aluminum reflow method, an Al-based alloy is deposited by sputtering on an insulating layer including the inside of an opening while the substrate is heated to about 150 ° C. Thereafter, the base is heated to a high temperature (for example, about 500 ° C.), and the Al-based alloy deposited on the insulating layer is caused to flow into the opening in a fluid state, and the opening is filled with the Al-based alloy to form a connection hole. I do. At the same time, the Al-based alloy on the insulating layer is planarized to form an upper wiring layer.

In these high-temperature aluminum sputtering and aluminum reflow methods, the A
In order to prevent the l-based alloy from penetrating into the impurity diffusion region 102, at least the barrier metal layer 12 is formed in the opening 106 before the Al-based alloy is deposited by sputtering.
0,122 must be formed. Further, when a connection hole is provided for the lower wiring layer made of an Al-based alloy, the base is heated to a high temperature, so that the Al-based alloy in the lower wiring layer is sucked into the opening embedded with the Al-based alloy. In some cases, voids may occur in the lower wiring layer. In order to prevent this, it is necessary to form a barrier metal layer at least in the opening 106 before depositing the Al-based alloy by a sputtering method. These barrier metal layers 120 and 122 are
For example, it has a two-layer structure of a Ti layer 120 / TiN layer 122 from below. The TiN layer 122 effectively prevents penetration or absorption of the Al-based alloy. In order to reduce the resistance between the TiN layer 122 and the impurity diffusion region 102 or the like, Ti
The layer 120 is formed.

[0010] As described above, in any of these connection hole forming methods, a barrier metal layer composed of a Ti layer / TiN layer or the like is required. However, as the openings have higher aspect ratios, it is becoming more difficult to form a barrier metal layer having high barrier properties and excellent step coverage by sputtering. Therefore, a method of continuously forming a barrier metal layer composed of a Ti layer / TiN layer by an electron cyclotron resonance plasma CVD method (ECR plasma CVD method) having excellent step coverage has been studied.

[0011]

SUMMARY OF THE INVENTION ECR plasma CVD
When a barrier metal layer composed of a Ti layer / TiN layer is formed by an ECR plasma CVD method using an apparatus, the growth rate of the Ti layer is about 2 nm / min, which is lower than the growth rate of the TiN layer. The growth rate is remarkably slow at about 1/10. Therefore, there is a problem that it takes a long time to form the barrier metal layer composed of the Ti layer / TiN layer.

A method of forming a Ti-rich TiN layer by ECR plasma CVD while adding a small amount of nitrogen is as follows.
Proceedings of the 40th Annual Conference of the Japan Society of Applied Physics 31p-Z
Y-16 (page 785). By such a method, a Ti-rich TiN layer can be formed at a higher growth rate than the Ti layer, and the contact resistance is lower than that of TiN having a stoichiometric composition (Ti: N = 1: 1). Is reported to be obtained. However, T
When an i-rich TiN layer is formed on an insulating layer, TiN
Has a large internal stress, so that TiN
There is a problem that the adhesion of the layer is poor.

Accordingly, an object of the present invention is to provide a method for forming a barrier metal layer which has excellent coverage, can be formed at a higher growth rate than conventional ones, has excellent adhesion to an insulating layer, and has low contact resistance. Is to do.

[0014]

According to the present invention, there is provided a method for forming a barrier metal layer in a semiconductor device, comprising the steps of: forming a barrier comprising first and second barrier metal layers constituting a wiring in the semiconductor device; A method for forming a metal layer, comprising: (a) forming a lower layer of a first barrier metal layer by a chemical vapor deposition method using a first source gas containing a metal element constituting a barrier metal layer; Subsequently, the second raw material gas and the first raw material gas containing the metal element and the element capable of forming the compound are used, and the ratio of the second raw material gas amount / the first raw material gas amount is changed from 0 to 0. The upper layer of the first barrier metal layer is formed by chemical vapor deposition (CVD) while increasing to a predetermined ratio, and then (b) the amount of the second source gas / the amount of the first source gas. Increase the percentage of the In a state where the chemical vapor deposition of the second barrier metal layer on the first barrier metal layer (CVD
Method).

When the first barrier metal layer is formed by the CVD method, the amount of change in the ratio of the amount of the second source gas / the amount of the first source gas may be constant, or the ratio may be changed stepwise. May be changed.

In the method of forming a barrier metal layer according to the present invention, the metal element is desirably titanium, hafnium, or zirconium. Further, it is desirable that the second source gas is a nitrogen gas.

In the method of forming a barrier metal layer according to the present invention, an oxygen gas can be further used in the step (b).

Alternatively, in the step (b),
A third source gas containing an element generating a metal element and a compound can be further used. In this case, the third source gas may contain carbon or boron. Further, in the step (b), oxygen gas can be further used.

In the method of forming a barrier metal layer according to the present invention, the first and second barrier metal layers are formed by an electron cyclotron resonance plasma CVD (ECR plasma CV).
(Method D).

[0020]

According to the present invention, since the first and second barrier metal layers are formed by the chemical vapor deposition method, the coverage of the barrier metal layer is excellent. Further, since the first barrier metal layer is formed separately in the lower layer and the upper layer, the first barrier metal layer is formed at a higher growth rate than when the first barrier metal layer is formed only from the metal element constituting the lower layer. can do. In addition, since the lower layer is composed only of the metal element, the first barrier metal layer has excellent adhesion to the insulating layer, and a low contact resistance can be obtained. Furthermore, since the second barrier metal layer is formed, the barrier properties are excellent.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on embodiments with reference to the drawings.

(Embodiment 1) In Embodiment 1, a method of forming a barrier metal layer according to the present invention uses a blanket tungsten CV.
This is an example applied to a case where a contact hole is formed by the method D. As shown in FIG. 2, the barrier metal layer according to the first embodiment includes first barrier metal layers 20A and 20B and a second barrier metal layer 22.

The first barrier metal layer includes a lower layer 20A and an upper layer 20B. The lower layer 20A is made of a metal (titanium or Ti in the first embodiment). Also,
The upper layer 20B is made of a metal (titanium or Ti in Example 1) similarly to the lower layer, and contains nitrogen (N) which is an element forming a compound with Ti.

The second barrier metal layer 22 is made of a metal compound (TiN in the first embodiment) containing a metal (Ti) constituting the first barrier metal layer.

In FIG. 2, reference numeral 10 is a substrate made of a semiconductor substrate, reference numeral 12 is an impurity diffusion region formed in the substrate, reference numeral 14 is an insulating layer made of SiO ₂ , and reference numeral 24 is a metal wiring made of tungsten. Material layer, reference numeral 26 is a metal plug made of tungsten, reference numeral 2
8 is an upper wiring layer. In the first embodiment, the metal wiring material layer 24 is formed by a tungsten blanket CVD method.

First, an outline of an ECR plasma CVD apparatus suitable for implementing the barrier metal layer forming method of the present invention will be described with reference to FIG. ECR plasma CVD equipment
It comprises a film forming chamber 50 and a plasma chamber 60.
In the film forming chamber 50, a susceptor 52 for mounting the semiconductor substrate 100 is arranged. Below the susceptor 52, a lamp heating means 54 is arranged. The semiconductor substrate 100 can be heated by the lamp heating means 54.

The plasma chamber 60 is a film forming chamber 50
It communicates with the upper part. A microwave introduction window 62 is provided above the plasma chamber 60, and a rectangular wave guide 66 for introducing a microwave of 2.45 GHz is provided above the microwave introduction window 62. A magnetic coil 64 is provided around the plasma chamber 60. RF power is applied to microwave introduction window 62 from RF power supply 68. Argon gas and N ₂ O are supplied through a gas inlet 80 into the plasma chamber 60.
Gas is supplied. These gases are supplied to the microwave introduction window 6
2 to perform the cleaning.

The first source gas is supplied from the first source gas supply unit to the film forming chamber 50 through the mass flow controller and the first gas introduction unit 70. Similarly, the second and third source gases are supplied to the film forming chamber 50 from the second and third source gas supply units through the mass flow controller and the second and third gas introduction units 72 and 74.
Further, various process gases are supplied from the process gas supply unit to the film formation chamber 50 through the mass flow controller and the process gas introduction unit 76. Note that various process gases, second and third source gases, and the like can also be introduced into the plasma chamber 60.

The gas in the film forming chamber 50 is
The gas is exhausted out of the system from 6. In FIG. 3, reference numeral 102
Is the plasma flow. Reference numeral 100 denotes a semiconductor substrate having the structure shown in FIG. Monitoring the temperature of the semiconductor substrate 100 with a thermocouple (not shown),
The power supplied to the lamp heating means 54 is controlled by a known temperature control means (not shown) to keep the temperature of the semiconductor substrate 100 constant.

Hereinafter, a method of forming the barrier metal layer of the first embodiment will be described.

[Step-100] First, for example, a Si layer is formed on a substrate 10 made of a semiconductor substrate on which an impurity diffusion region 12 is formed by a known method by a known method such as a CVD method.
An insulating layer 14 made of O ₂ is formed. Next, a photolithography technique and, for example, a reactive ion etching (R
The opening 16 is formed by using the IE) technique (see FIG. 1A). Etching can be performed, for example, under the following conditions. Working gas: CHF ₃ / O ₂ = 50/5 sccm Pressure: 5 Pa Power: 1 kW

[Step-110] Next, the first method of forming the barrier metal layer according to the present invention is performed so that the entire thickness is 5 nm.
Is formed. Using the ECR plasma CVD apparatus shown in FIG. 3, a first source gas (TiC) containing a metal element (Ti) constituting a barrier metal layer is used.
l ₄ ), the lower layer 20A of the first barrier metal layer is
It is formed by CR plasma CVD. ECR Plasma C
The conditions for forming the lower layer 20A of the first barrier metal layer by VD can be, for example, as follows. First raw material gas: TiCl ₄ = 20 sccm Process gas: H ₂ / Ar = 26/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 420 ° C Microwave output: 2.8 kW Film formation time: 10 seconds

[Step-120] Subsequently, the metal element (T
i) a second source gas (nitrogen gas) and a first source gas (TiCl ₄ ) containing an element (N) capable of producing a compound (TiN) with the second source gas amount / First
The upper layer 20B of the first barrier metal layer is formed by the ECR plasma CVD method while increasing the ratio of the source gas amount from 0 to a predetermined ratio. The first source gas amount was kept constant, and the second source gas amount was gradually increased from 0 to 1.5 sccm. The amount of change was constant. First source gas: TiCl ₄ = 20 sccm Second source gas: N ₂ = 0 to 1.5 sccm Process gas: H ₂ / Ar = 26/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 420 ° C Microwave output: 2.8 kW Film formation time: 60 seconds

Thus, the upper layer 20B of the first barrier metal layer mainly composed of Ti is formed. Nitrogen (N) can be slightly contained in the upper layer 20B of the first barrier metal layer.

The lower layer 20A of the first barrier metal layer is made of T
Since it is composed only of i, it has excellent adhesion to the insulating layer 14 made of SiO ₂ as a base. By forming the first barrier metal layer from the lower layer / upper layer, the film formation rate of the first barrier metal layer can be reduced by about 10
0% could be increased.

[Step-130] Then, the second ratio of the second source gas amount / the first source gas amount is set to be higher than the predetermined ratio in [Step-120], and the second material gas of TiN is used. A barrier metal layer 22 is formed on the first barrier metal layer by a chemical vapor deposition method. The thickness of the second barrier metal layer 22 was set to 50 nm. ECR plasma CV
The conditions for forming the second barrier metal layer 22 by the method D can be, for example, as follows. First source gas: TiCl ₄ = 20 sccm Second source gas: N ₂ = 8 sccm Process gas: H ₂ / Ar = 26/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 420 ° C Microwave output: 2.8 kW

[Step-140] Thereafter, a metal wiring material layer 24 made of tungsten is deposited on the second barrier metal layer 22 by a tungsten blanket CVD method (see FIG. 1C). Blanket tungsten C
The condition of VD can be, for example, as follows. First step (nucleation stage) WF ₆ / SiH ₄ = 25/10 sccm Pressure 1.06 × 10 ⁴ Pa Temperature about 475 ° C Second step (high-speed growth stage) WF ₆ / H ₂ = 60/360 sccm Pressure 1. 06 × 10 ⁴ Pa Temperature about 475 ° C

Next, the metal wiring material layer 2 on the insulating layer 14
4, second and first barrier metal layers 22, 20B,
20A is removed, and a via hole 26 is formed leaving a metal wiring material layer 24 (tungsten plug) made of tungsten in the opening. Thus, the wiring structure of the semiconductor device shown in FIG. On the insulating layer 14 and the via hole 26 of this semiconductor device, for example,
An upper wiring layer made of an Al-based alloy such as 1-1% Si can be formed by a sputtering method, an etching method, or the like.

Alternatively, as shown in a schematic partial cross-sectional view of FIG.
4, second and first barrier metal layers 22, 20B,
The upper wiring layer 28 is formed on the insulating layer 14 by selectively removing 20A. At the same time, a via hole 26 is formed while leaving the metal wiring material layer 24 (tungsten plug) in the opening. The upper wiring layer 28 is formed of the insulating layer 1
4 comprises a first and a second barrier metal layer formed on the surface of the substrate 4 and a metal wiring material layer 24 made of tungsten.

Second Embodiment A second embodiment is a modification of the first embodiment. The second embodiment differs from the first embodiment in that the second barrier metal layer 22 is made of TiON. Other points are the same as the first embodiment. Hereinafter, a method of forming the barrier metal layer according to the second embodiment will be described.

[Step-200] First, an insulating layer made of, for example, SiO ₂ is formed by a known method such as a CVD method on a base made of a semiconductor substrate having an impurity diffusion region formed by a known method. Next, an opening is formed in the insulating layer above the impurity diffusion region by using a photolithography technique and, for example, a reactive ion etching (RIE) technique. This step is performed in the same manner as in Example 1, [Step-10].
0].

[Step-210] Next, in the same manner as in [Step-110] and [Step-120] of Example 1, Ti
A first barrier metal layer having a thickness of 5 nm and including a lower layer made of Ti and an upper layer mainly made of Ti is formed.

[Step-220] Subsequently, the second ratio of the second source gas amount / the first source gas amount is set to be higher than the predetermined ratio in [Step-210], and the second source gas of Ti0N is formed. A barrier metal layer 22 is formed on the first barrier metal layer by a chemical vapor deposition method. The thickness of the second barrier metal layer 22 was set to 50 nm. ECR Plasma C
The conditions for forming the second barrier metal layer 22 by VD can be, for example, as follows. First source gas: TiCl ₄ = 20 sccm Second source gas: N ₂ = 8 sccm Other source gas: O ₂ = 5 sccm Process gas: H ₂ = 26 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 420 ° C Microwave output: 2.8 kW

[Step-230] Next, a metal wiring material layer made of tungsten is deposited on the second barrier metal layer by a tungsten blanket CVD method. Thereafter, the metal wiring material layer on the insulating layer and the second and first barrier metal layers are removed, leaving a metal wiring material layer (tungsten plug) made of tungsten in the opening to form a via hole. Alternatively, an upper wiring layer is formed on the insulating layer by selectively removing the metal wiring material layer on the insulating layer and the second and first barrier metal layers, and the metal wiring material layer is formed in the opening. A via hole is formed while leaving the layer (tungsten plug). These steps can be the same as [Step-140] in Example 1.

Instead of forming the second barrier metal layer from TiON, TiBN, TiCN or TiCNO
Can be composed of In this case, the conditions of the ECR plasma CVD in [Step-220] of the second embodiment may be replaced with the conditions exemplified below. (Formation of TiBN) First source gas: TiCl ₄ = 20 sccm Second source gas: N ₂ = 8 sccm Third source gas: BCl ₃ = 10 sccm Process gas: H ₂ = 26 sccm Pressure: 0.13 Pa (9) .6 × 10 ^-4 T
orr) Temperature: about 420 ° C. Microwave output: 2.8 kW (TiCN film formation) First source gas: TiCl ₄ = 20 sccm Second source gas: N ₂ = 8 sccm Third source gas: CH ₄ = 10 sccm Process gas: H ₂ = 26 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 420 ° C. Microwave output: 2.8 kW (TiCNO film formation) First source gas: TiCl ₄ = 20 sccm Second source gas: N ₂ = 8 sccm Third source gas: CH ₄ = 10 sccm Other source gas: O ₂ = 5 sccm Process gas: H ₂ = 26 sccm Pressure: 0.13 Pa (9.6 × 10 ^-4 T)
orr) Temperature: about 420 ° C Microwave output: 2.8 kW

(Embodiment 3) In Embodiments 1 and 2, titanium (T) was used as the metal constituting the barrier metal layer.
i) was used. In the third embodiment, hafnium (Hf) is used as the metal material forming the barrier metal layer.
Also in the third embodiment, the metal wiring material layer is formed by a tungsten blanket CVD method. Hereinafter, a method of forming the barrier metal layer according to the third embodiment will be described.

[Step-300] First, an insulating layer made of, for example, SiO ₂ is formed by a known method such as a CVD method on a base made of a semiconductor substrate having an impurity diffusion region formed by a known method. Next, an opening is formed in the insulating layer above the impurity diffusion region by using a photolithography technique and, for example, a reactive ion etching (RIE) technique. This step is performed in the same manner as in Example 1, [Step-10].
0].

[Step-310] Next, the first metal film having a total thickness of 5 nm is formed by the barrier metal layer forming method of the present invention.
Is formed. Using the ECR plasma CVD apparatus shown in FIG. 3, a first source gas (HfOCl) containing a metal element (Hf) constituting a barrier metal layer is used.
The lower layer of the first barrier metal layer is formed by ECR plasma CVD using ₂ ). The conditions for forming the lower layer of the first barrier metal layer by ECR plasma CVD can be, for example, as follows. First raw material gas: HfOCl ₂ = 10 sccm Process gas: H ₂ / Ar = 50/40 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 400 ° C. Microwave output: 2.8 kW Film formation time: 10 seconds

Note that HfOCl ₂ was used as the first source gas.
Hf (OtC ₄ H ₉ ) ₄ can be used instead of HfOCl ₂ and Hf (OtC ₄ H ₉ ) ₄ are liquid raw materials. Therefore, HfOCl ₂ is converted to water, Hf (O−
After dissolving t-C ₄ H ₉ ) ₄ in a solvent such as alcohol,
Bubbling with e gas or the like is used as a source gas.

[Step-320] Subsequently, the metal element (H
f) using a second source gas (BCl ₃ gas) and a first source gas (HfOCl ₂ ) containing an element (B) capable of producing a compound (HfB _x ) with the second source gas The upper layer of the first barrier metal layer is formed by ECR plasma CVD while increasing the ratio of amount / first source gas amount from 0 to a predetermined ratio. The first source gas amount was kept constant, and the second source gas amount was gradually increased from 0 to 1.5 sccm. The amount of change was constant. First source gas: HfOCl ₂ = 10 sccm Second source gas: BCl ₃ = 0 to 1.5 sccm Process gas: H ₂ / Ar = 30/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 650 ° C. Microwave output: 2.8 kW Film formation time: 60 seconds As the second source gas, instead of BCl ₃ , BB
r ₃ or B ₂ H ₆ can also be used.

Thus, an upper layer of the first barrier metal layer mainly composed of Hf is formed. Boron (B) may be slightly contained in the upper layer of the first barrier metal layer.

Since the lower layer of the first barrier metal layer is composed only of Hf, it has excellent adhesion to the underlying insulating layer made of SiO ₂ . Also, by forming the first barrier metal layer from the lower layer / upper layer as compared with the case where the entire first barrier metal layer is formed only from Hf, the deposition rate of the first barrier metal layer can be reduced by about 100%. % Could be increased.

[Step-330] Subsequently, with the ratio of the second source gas amount / the first source gas amount being increased from the predetermined ratio in [Step-320], HfB
_X (0 <X ≦ 2)
Is formed by chemical vapor deposition on the barrier metal layer.
The thickness of the second barrier metal layer was set to 50 nm. ECR
The conditions for forming the second barrier metal layer by plasma CVD can be, for example, as follows. First source gas: HfOCl ₂ = 10 sccm Second source gas: BCl ₃ = 30 sccm Process gas: H ₂ / Ar = 30/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 650 ° C Microwave output: 2.8 kW

[Step-340] Then, a metal wiring material layer made of tungsten is deposited on the second barrier metal layer by a tungsten blanket CVD method. Thereafter, the metal wiring material layer on the insulating layer and the second and first barrier metal layers are removed, leaving a metal wiring material layer (tungsten plug) made of tungsten in the opening to form a via hole. Alternatively, an upper wiring layer is formed on the insulating layer by selectively removing the metal wiring material layer on the insulating layer and the second and first barrier metal layers, and the metal wiring material layer is formed in the opening. A via hole is formed while leaving the layer (tungsten plug). These steps can be the same as [Step-140] in Example 1.

Hf is used as the metal constituting the barrier metal layer.
Can be used instead of zirconium (Zr). In this case, [Step-310] and [Step-
320] and [Step-330] may be replaced with the conditions exemplified below. (Formation of Lower Layer of First Barrier Metal Layer) First source gas: ZrCl ₄ = 10 sccm Process gas: H ₂ / Ar = 50/40 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 400 ° C. Microwave output: 2.8 kW Film formation time: 10 seconds (formation of an upper layer of the first barrier metal layer) First source gas: ZrCl ₄ = 10 sccm Second source gas: BCl ₃ = 0 to 1.5 sccm Process gas: H ₂ / Ar = 30/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 650 ° C. Microwave output: 2.8 kW Film formation time: 60 seconds (Formation of second barrier metal layer (ZrB _x , 0 <X ≦ 2)) First source gas: ZrCl ₄ = 10 sccm Second source gas: BCl ₃ = 30 sccm Process gas: H ₂ / Ar = 30/50 sccm Pressure: 0.13 Pa (9.6 × 10 ⁻⁴ T)
orr) Temperature: about 650 ° C Microwave output: 2.8 kW

As the first source gas, ZrCl ₃ can be used instead of ZrCl ₄ . ZrCl ₄ and ZrCl ₃ are liquid raw materials. Therefore, after dissolving them in water, bubbling with He gas or the like is used as a source gas. Also, BBr ₃ or B ₂ H ₆ can be used instead of BCl ₃ as the second source gas. In forming the upper layer of the first barrier metal layer, the first source gas amount is kept constant, and the second source gas amount is gradually increased from 0 to 1.5 sccm.

Although the method for forming the barrier metal layer of the present invention has been described based on the embodiments, the present invention is not limited to these embodiments. Instead of a blanket CVD method using tungsten, Mo, Ti, Ni,
Co, Al, Cu, etc., or W, Mo, Ti, N
Blanket C using various silicides such as i and Co
The present invention can be applied to the VD method. Alternatively, a metal plug can be formed by selective CVD using aluminum.

In each of the embodiments, the first and second barrier metal layers are formed using one ECR plasma CVD apparatus. Instead, the first film forming chamber and the first film forming chamber connected via a gate valve may be used. An ECR plasma CVD apparatus provided with a second film formation chamber can also be used. In this case, for example, a first barrier metal layer is formed in the first film formation chamber, and then the semiconductor substrate is carried into the second film formation chamber without breaking vacuum, and is then transferred to the second film formation chamber. To form a second barrier metal layer.

Further, instead of the blanket CVD method, pure Al or Al-1% Si, Al--Si--
It is also possible to form a metal plug by a so-called high-temperature aluminum sputtering method or an aluminum reflow method using an aluminum alloy such as Cu, Al-Cu, or Al-Ge. In these sputtering methods, since the semiconductor substrate is heated to a high temperature, the metal wiring material made of aluminum or an aluminum alloy deposited in the opening is also heated to about 400 ° C. or more and the melting point or less. as a result,
The softened metal wiring material becomes in a flowing state, and can flow in the opening.

After the formation of the first and second barrier metal layers, Al-1% is continuously applied in another chamber without breaking the vacuum.
An aluminum alloy made of Si can be formed, for example, by a high-temperature aluminum sputtering method under the following conditions. Film formation power DC 10 kW Sputter pressure 0.4 Pa Substrate heating temperature 500 ° C. Process gas Ar: 100 sccm Film formation rate 0.3 to 0.9 μm / min

Alternatively, after forming the first and second barrier metal layers, an aluminum alloy made of Al-1% Si is continuously formed in another chamber without breaking vacuum, for example, under the following conditions. The film can be formed according to a reflow method. (Aluminum sputtering conditions) Process gas: Ar = 100 sccm DC power: 20 kW Sputtering pressure: 0.4 Pa Substrate heating temperature: 150 ° C. Film formation rate: 1200 nm / min (Aluminum reflow conditions) Heating method: Substrate backside gas heating Heating Temperature: 500 ° C. Heating time: 2 minutes Process gas: Ar = 100 sccm Process gas pressure: 1.1 × 10 ³ Pa Here, the substrate backside gas heating method means that a heater block disposed on the backside of the substrate is heated to a predetermined temperature ( (A heating temperature) and a process gas is introduced between the heater block and the back surface of the substrate to heat the substrate. As a heating method, a lamp heating method or the like can be used in addition to this method.

The insulating layer is made of not only SiO ₂ but also PSG,
It can be made of BSG, BPSG, AsSG, PbSG, SbSG, a silicon nitride film, SiON, SOG, SiON or the like, and can be formed by a conventional CVD method.

Although the present invention has been described based on the embodiment in which a contact hole is formed in an impurity diffusion region, the method of forming a barrier metal layer according to the present invention uses a lower wiring layer and an upper wiring layer formed of a metal wiring material. The present invention can be applied to formation of a so-called via hole for electrically connecting layers, or formation of a through hole.

When the underlying layer for forming the first barrier metal layer of the present invention is silicon, the lower layer of the first barrier metal layer reacts with the underlying silicon depending on the formation conditions of the lower layer of the first barrier metal layer. May form a silicide layer.

[0065]

According to the present invention, excellent coverage is obtained.
A barrier metal layer which can be formed at a growth rate higher than that of the related art, has excellent adhesion to an insulating layer, and has low contact resistance can be obtained. Therefore, the next generation super LS
I can be manufactured with high productivity by a highly reliable process.

[Brief description of the drawings]

FIG. 1 is a schematic partial cross-sectional view of a semiconductor device for explaining a method of forming a barrier metal layer according to the present invention.

FIG. 2 is a schematic partial sectional view of a semiconductor device obtained by a method for forming a barrier metal layer according to the present invention.

FIG. 3 is a diagram showing an outline of an ECR plasma CVD apparatus suitable for carrying out the present invention.

FIG. 4 is a schematic partial sectional view of a semiconductor device for explaining a blanket CVD method.

FIG. 5 is a schematic partial cross-sectional view of a semiconductor device for explaining a high-temperature aluminum sputtering method.

[Explanation of symbols]

 REFERENCE SIGNS LIST 10 base 12 impurity diffusion region 14 insulating layer 16 opening 20A lower layer of first barrier metal layer 20B upper layer of first barrier metal layer 22 second barrier metal layer 24 metal wiring material layer 26 metal plug 28 upper wiring layer 50 Deposition chamber 52 Susceptor 54 Lamp heating means 56 Gas exhaust unit 60 Plasma chamber 62 Microwave introduction window 66 Rectangular wave guide 64 Magnetic coil 68 RF power supply 70 First gas introduction unit 72, 74 Second, third gas introduction unit 76 Process gas inlet 80 Gas inlet 100 Semiconductor substrate 102 Plasma flow

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01L 21/205 G01R 33/64 H01L 21/285 301 H01L 21/3205 H01L 21/768

Claims (8)

(57) [Claims] 1. A method for forming a barrier metal layer comprising first and second barrier metal layers constituting a wiring in a semiconductor device, comprising: (a) a first method comprising forming a metal element constituting a barrier metal layer; A lower layer of the first barrier metal layer is formed by a chemical vapor deposition method using a source gas, and subsequently, a second source gas containing the metal element and an element capable of forming a compound, and a first source gas. The upper layer of the first barrier metal layer is formed by chemical vapor deposition while using a gas and increasing the ratio of the second source gas amount / the first source gas amount from 0 to a predetermined ratio. And (b) the ratio of the amount of the second source gas / the amount of the first source gas,
Forming a second barrier metal layer on the first barrier metal layer by a chemical vapor deposition method in a state in which the barrier metal layer is increased above the predetermined ratio. Method. 2. The method according to claim 1, wherein the metal element is one of titanium, hafnium, and zirconium. 3. The method for forming a barrier metal layer in a semiconductor device according to claim 1, wherein said second source gas is nitrogen gas. 4. The method for forming a barrier metal layer in a semiconductor device according to claim 1, wherein an oxygen gas is further used in the step (b). 5. The method according to claim 1, wherein in the step (b), a third source gas containing an element generating a compound with the metal element is further used. 7. A method for forming a barrier metal layer in a semiconductor device according to item 5. 6. The method according to claim 5, wherein the third source gas contains carbon or boron. 7. The method according to claim 6, wherein oxygen gas is further used in the step (b). 8. The barrier according to claim 1, wherein the first and second barrier metal layers are formed by an electron cyclotron resonance plasma CVD method. A method for forming a metal layer.