JPH0766143A - Formation of barrier metal layer in semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for forming a barrier metal layer having low contact resistance and excellent in coverage and intimate contact with an insulation layer at a higher grow rate as compared with conventional technology. CONSTITUTION:When a barrier metal layer composing the wiring in a semiconductor device is formed, the lower layer 20A of a first barrier metal layer is formed by CVD using first material gas containing a metal element composing the barrier metal layer. Subsequently, the upper layer 20B of first barrier metal layer is formed by CVD using the first material gas and a second material gas containing an element reacting on the metal element to produce a compound while increasing the volumetric ratio of the second material gas to the first material gas from zero to a predetermined value. A second barrier metal layer 22 is then formed on the first barrier metal layer by CVD while increasing the volumetric ratio above the predetermined value.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a barrier metal layer in a semiconductor device, and more particularly to a method for forming a barrier metal layer formed by chemical vapor deposition.

[0002]

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

As a method of filling the opening with a metal wiring material, a sputtering method using pure aluminum or an aluminum alloy (hereinafter, also referred to as an Al alloy) is generally adopted. However, in this sputtering method,
As the aspect ratio of the opening becomes higher, it becomes more difficult for sputtered particles made of an Al-based alloy to deposit on the bottom of the opening or on the sidewall of the opening in the vicinity thereof due to the so-called shadowing effect. Here, the shadowing effect refers to a phenomenon in which sputtered particles made of an Al-based alloy are hard to be deposited on an optically shadowed portion formed on the side wall or the bottom of the 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 of the opening deteriorates, and disconnection failure easily occurs at such a portion.

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

In the blanket CVD method, as shown in a schematic partial cross-sectional view of a semiconductor device in FIG.
For example, a tungsten layer 114 is deposited by chemical vapor deposition (CVD method) on the insulating layer 104 formed on the insulating film 104 and in the opening 106 formed in the insulating layer 104 ((in FIG. 4). See A)). Then, on the insulating layer 104
The tungsten layer 114 formed on the substrate is etched back and removed. This completes the connection hole in which the metal plug 116 made of tungsten is formed in the opening 106 (see FIG. 4B). Note that such a method will be hereinafter referred to as a tungsten blanket CVD method.
In FIG. 4, 102 is an impurity diffusion region formed in the semiconductor substrate.

When the tungsten layer is formed by the 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 under 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 the difference in internal stress at the interface between different material layers. Therefore, to improve adhesion, TiN
The layer 112 is formed. Further, the Ti layer 1 is formed for the purpose of reducing the resistance between the TiN layer 112 and the impurity diffusion region 102.
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,
As shown in the schematic partial sectional view of the semiconductor element in FIG.
The substrate 10 is formed on the insulating layer 104 formed on the substrate 100 and in the opening 106 formed in the insulating layer 104.
With 0 heated to a high temperature (for example, about 500 ° C),
The Al-based alloy layer 124 is formed by the sputtering method, and at the same time,
An upper wiring layer 126 made of an Al alloy on the 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 becomes a fluid state and flows into the opening 106. As a result, the opening 10
The interior of 6 is surely filled with an Al-based alloy to form a connection hole. In FIG. 5, 102 is an impurity diffusion region. The 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 the present specification. These are collectively referred to simply as a high temperature aluminum sputtering method.

Further, in the aluminum reflow method, an Al-based alloy is deposited by sputtering on the insulating layer including the inside of the opening while the substrate is heated to about 150 ° C. After that, the substrate is heated to a high temperature (for example, about 500 ° C.), the Al-based alloy deposited on the insulating layer is made to flow into the opening, and the opening is filled with the Al-based alloy to form a connection hole. To do. At the same time, the Al-based alloy on the insulating layer is flattened to form the upper wiring layer.

In these high temperature aluminum sputtering method and aluminum reflow method, A in the opening 106 is
In order to prevent the l-based alloy from penetrating into the impurity diffusion region 102, the barrier metal layer 12 is formed at least in the opening 106 before the Al-based alloy is deposited by the sputtering method.
It is necessary to form 0,122. Further, when the connection hole is formed in the lower wiring layer made of an Al-based alloy, the substrate is heated to a high temperature, and as a result, the Al-based alloy in the lower-layer wiring layer is sucked up into the opening filled with the Al-based alloy. A void may be generated 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 the sputtering method. These barrier metal layers 120 and 122 are
For example, it has a two-layer structure of Ti bran 120 / TiN layer 122 from the bottom. The TiN layer 122 effectively prevents penetration and wicking of the Al-based alloy. In order to reduce the resistance between the TiN layer 122 and the impurity diffusion region 102, etc., Ti
Form the layer 120.

As described above, in any of the methods for forming these connection holes, a barrier metal layer composed of a Ti layer / TiN layer or the like is required. However, as the opening has a high aspect ratio, it is becoming difficult to form a barrier metal layer having a high barrier property and excellent step coverage by a sputtering method. 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) excellent in step coverage has been studied.

[0011]

[Problems to be Solved by 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 higher than that of the TiN layer. The growth rate is about 1/10, which is extremely slow. 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 the ECR plasma CVD method while adding a slight amount of nitrogen is as follows.
Proceedings of the 40th Joint Lecture of the Japan Society of Applied Physics 31p-Z
It is known from Y-16 (page 785). With such a method, a Ti-rich TiN layer can be formed at a higher growth rate than that of the Ti layer, and a contact resistance 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 the insulating layer, TiN
Has a large internal stress, the TiN to the insulating layer
There is a problem that the adhesion of the layer is poor.

Therefore, 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 in the past, has excellent adhesion to an insulating layer, and has low contact resistance. To do.

[0014]

A method of forming a barrier metal layer in a semiconductor device according to the present invention for achieving the above object comprises a barrier composed of 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 the first barrier metal layer by a chemical vapor deposition method using a first source gas containing a metal element forming the barrier metal layer. Subsequently, the second source gas and the first source gas containing the element capable of forming a compound with the metal element are used, and the ratio of the second source gas amount / the first source gas amount is 0 to The upper layer of the first barrier metal layer is formed by a chemical vapor deposition method (CVD method) while increasing it to a predetermined ratio, and then (b) the second source gas amount / the first source gas amount. Increase the percentage above the prescribed percentage 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 change amount of 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. You may change to.

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

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

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

In the method of forming the barrier metal layer of the present invention, the formation of the first and second barrier metal layers is performed by electron cyclotron resonance plasma CVD (ECR plasma CV).
It is preferable to carry out the method D).

[0020]

In the present invention, since the first and second barrier metal layers are formed by the chemical vapor deposition method, the barrier metal layer has excellent coverage. In addition, 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 growth rate faster than that of forming the first barrier metal layer only from the metal element forming the lower layer. can do. Moreover, since the lower layer is composed of only the metal element, the adhesion of the first barrier metal layer to the insulating layer is excellent, and a low contact resistance can be obtained. Furthermore, since the second barrier metal layer is formed, the barrier property is excellent.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described based on embodiments with reference to the drawings.

(Example 1) Example 1 is a method for forming a barrier metal layer according to the present invention, in which a blanket tungsten CV is used.
This is an example applied when a contact hole is formed by the D method. As shown in FIG. 2, the barrier metal layer in Example 1 is composed of first barrier metal layers 20A and 20B and a second barrier metal layer 22.

The first barrier metal layer is composed of a lower layer 20A and an upper layer 20B. The lower layer 20A is made of metal (titanium, Ti in the first embodiment). Also,
The upper layer 20B is made of a metal (titanium or Ti in the first embodiment) like 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) forming the first barrier metal layer.

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

First, an outline of an ECR plasma CVD apparatus suitable for carrying out the method for forming a barrier metal layer 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.
A susceptor 52 for mounting the semiconductor substrate 100 is arranged in the film forming chamber 50. A lamp heating means 54 is arranged below the susceptor 52. The semiconductor substrate 100 can be heated by the lamp heating means 54.

The plasma chamber 60 is the film forming chamber 50.
Communicates with the upper part of. 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 arranged around the plasma chamber 60. RF power is applied to the microwave introduction window 62 from the RF power supply 68. Argon gas and N ₂ O are introduced into the plasma chamber 60 through the gas inlet 80.
Gas is supplied. These gases are introduced through the microwave introduction window 6
Introduced to perform 2 cleaning.

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

The gas in the film forming chamber 50 is a gas exhaust unit 5.
It is exhausted from 6 to the outside of the system. In FIG. 3, 102 is a plasma flow. Further, 100 is a semiconductor substrate having the structure shown in FIG. The temperature of the semiconductor substrate 100 is monitored by a thermocouple (not shown), the power supplied to the lamp heating means 54 is controlled by a known temperature control means (not shown), and the temperature of the semiconductor substrate 100 is kept constant.

The method for forming the barrier metal layer of Example 1 will be described below.

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

[Step-110] Next, according to the method for forming a barrier metal layer of the present invention, a first layer having a total thickness of 5 nm is formed.
Forming a barrier metal layer. By using the ECR plasma CVD apparatus shown in FIG. 3, the first source gas (TiC containing the metal element (Ti) forming the barrier metal layer is formed.
L ₄ ) is used to remove the lower layer 20A of the first barrier metal layer by E
It is formed by the CR plasma CVD method. ECR plasma C
The conditions for forming the lower layer 20A of the first barrier metal layer by VD can be set as follows, for example. First source 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 raw material gas (nitrogen gas) containing an element (N) capable of forming a compound (TiN) with the first raw material gas (TiCl ₄ ) and a second raw material 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 raw material 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: Approx. 420 ° C Microwave output: 2.8kW Film formation time: 60 seconds

As a result, the upper layer 20B of the first barrier metal layer mainly made of Ti is formed. Nitrogen (N) may 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 T
Since it is composed of only i, it has excellent adhesion to the insulating layer 14 made of SiO ₂ as the base. Further, as compared with the case where the entire first barrier metal layer is composed of only Ti, by forming the first barrier metal layer from the lower layer / upper layer, the film formation rate of the first barrier metal layer is about 10
It was possible to increase by 0%.

[Step-130] Subsequently, in a state in which the ratio of the second raw material gas amount / the first raw material gas amount is made higher than the predetermined ratio in the [step-120], the second TiN-containing second gas is formed. The barrier metal layer 22 is formed on the first barrier metal layer by chemical vapor deposition. 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 D method can be set as follows, for example. 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: Approx. 420 ° C Microwave output: 2.8kW

[Step-140] After that, the metal wiring material layer 24 made of tungsten is deposited on the second barrier metal layer 22 by the tungsten blanket CVD method (see FIG. 1C). Blanket Tungsten C
The conditions of VD can be set as follows, for example. 1st step (nucleation stage) WF ₆ / SiH ₄ = 25/10 sccm pressure 1.06 × 10 ⁴ Pa temperature about 475 ° C 2nd step (fast 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 and the second and first barrier metal layers 22, 20B,
20A is removed to leave a metal wiring material layer 24 (tungsten plug) made of tungsten in the opening, and a via hole 26 is formed. Thus, the wiring structure of the semiconductor device shown in FIG. 2A is manufactured. On the insulating layer 14 and the via hole 24 of this semiconductor device, further, for example, A
The 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 the schematic partial sectional view of FIG. 2B, the metal wiring material layer 2 on the insulating layer 14 is formed.
4 and the second and first barrier metal layers 22, 20B,
By selectively removing 20A, the upper wiring layer 28 is formed on the insulating layer 14. At the same time, the via hole 26 is formed while leaving the metal wiring material layer 24 (tungsten plug) in the opening. The upper wiring layer 28 is the insulating layer 1
4 and the first and second barrier metal layers and the metal wiring material layer 24 made of tungsten.

(Embodiment 2) Embodiment 2 is a modification of Embodiment 1. The second embodiment is different from the first embodiment in that the second barrier metal layer 22 is made of TiON. The other points are the same as in the first embodiment. The method of forming the barrier metal layer of Example 2 will be described below.

[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 substrate made of a semiconductor substrate in which an impurity diffusion region is 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 corresponds to [Step-10 of Example 1].
0].

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

[Step-220] Subsequently, in a state where the ratio of the second raw material gas amount / the first raw material gas amount is made higher than the predetermined ratio in the [step-210], the second TiON-containing second gas is formed. The barrier metal layer 22 is formed on the first barrier metal layer by chemical vapor deposition. 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 set as follows, for example. 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: Approx. 420 ° C Microwave output: 2.8kW

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

Instead of forming the second barrier metal layer from TiON, TiBN, TiCN or TiCNO is used.
Can consist of: In this case, the conditions of ECR plasma CVD in [Step-220] of Example 2 may be replaced with the conditions exemplified below. (Film 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: Approx. 420 ° C Microwave output: 2.8kW

(Embodiment 3) In Embodiments 1 and 2, titanium (T) is used as the metal constituting the barrier metal layer.
i) was used. In Example 3, 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 the tungsten blanket CVD method. The method for forming the barrier metal layer of Example 3 will be described below.

[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 substrate made of a semiconductor substrate in which an impurity diffusion region is 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 corresponds to [Step-10 of Example 1].
0].

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

As the first source gas, HfOCl ₂
Instead of, Hf (O-t-C 4 H 9) 4 can also be used. HfOCl ₂ and Hf (Ot-C ₄ H ₉ ) ₄ are liquid raw materials. Therefore, HfOCl ₂ was added to water, Hf (O-
After dissolving t-C ₄ H ₉ ) ₄ in a solvent such as alcohol, H-
Bubbling with e gas or the like is used as a raw material 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 forming a compound (HfB _x ) with the second source gas The upper layer of the first barrier metal layer is formed by the ECR plasma CVD method 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 In addition, BB instead of BCl ₃ was used as the second source gas.
It is also possible to use r ₃ or B ₂ H ₆ .

As a result, an upper layer of the first barrier metal layer mainly composed of Hf is formed. A slight amount of nitrogen (N) may be 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 . Further, as compared with the case where the entire first barrier metal layer is composed of only Hf, by forming the first barrier metal layer from the lower layer / upper layer, the film formation rate of the first barrier metal layer is about 100. % Could be increased.

[Step-330] Then, in a state where the ratio of the second source gas amount / the first source gas amount is made higher than the predetermined ratio in [Step-320], HfB is set.
The second barrier metal layer composed of _X (0 <X ≦ 2) is formed as the first
Is formed on the barrier metal layer by chemical vapor deposition.
The thickness of the second barrier metal layer was 50 nm. ECR
The conditions for forming the second barrier metal layer by plasma CVD can be set as follows, for example. 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: 2.8kW

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

Hf as a metal forming the barrier metal layer
Zirconium (Zr) can be used instead of. In this case, [Process-310], [Process- of Example 3]
320] and [step-330], the conditions of ECR plasma CVD 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 the 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: 2.8kW

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 these are dissolved in water, bubbling with He gas or the like is used as a raw material gas. Further, BBr ₃ or B ₂ H ₆ may be used as the second source gas instead of BCl ₃ . 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 the 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, the metal plug can be formed by selective CVD using aluminum.

In each example, the first and second barrier metal layers were formed by using one ECR plasma CVD apparatus, but instead, the first film forming chamber and the first film forming chamber connected through the gate valve were used. An ECR plasma CVD apparatus equipped with a second film forming chamber can also be used. In this case, for example, the first barrier metal layer is formed in the first film forming chamber, then the semiconductor substrate is carried into the second film forming chamber without breaking the vacuum, and then the second film forming chamber is placed in the second film forming chamber. As a result, the second barrier metal layer can be formed.

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

After forming the first and second barrier metal layers, Al-1% is continuously formed in another chamber without breaking the vacuum.
An aluminum alloy made of Si can be formed by, for example, a high temperature aluminum sputtering method under the following conditions. Film forming power DC 10 kW Sputtering pressure 0.4 Pa Substrate heating temperature 500 ° C. Process gas Ar: 100 sccm Film forming 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 used in another chamber without breaking the vacuum, for example, aluminum under the following conditions: The film can be formed according to the reflow method. (Aluminum sputtering conditions) Process gas: Ar = 100 sccm DC power: 20 kW Sputtering pressure: 0.4 Pa Substrate heating temperature: 150 ° C Deposition rate: 1200 nm / min (Aluminum reflow conditions) Heating method: Substrate backside gas 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 refers to a heater block arranged on the backside of the substrate at a predetermined temperature ( It is a method of heating the substrate by heating it to a heating temperature) and introducing a process gas between the heater block and the back surface of the substrate. As the heating method, other than this method, a lamp heating method or the like can be used.

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

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

When the underlayer forming the first barrier metal layer of the present invention is silicon, the underlayer of the first barrier metal layer may react with the underlying silicon depending on the formation conditions of the underlayer of the first barrier metal layer. May become a silicide layer.

[0065]

In the present invention, excellent coverage,
It is possible to obtain a barrier metal layer that can be formed at a higher growth rate than in the past and that has excellent adhesion to the insulating layer and low contact resistance. Therefore, next-generation ultra LS
I can be manufactured with high productivity in a highly reliable process.

[Brief description of drawings]

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

FIG. 2 is a schematic partial cross-sectional view of a semiconductor device obtained by the method for forming a barrier metal layer of 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 cross-sectional view of a semiconductor device for explaining a blanket CVD method.

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

[Explanation of symbols]

 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 section 60 Plasma chamber 62 Microwave introduction window 66 Rectangular wave guide 64 Magnetic coil 68 RF power source 70 First gas introduction section 72, 74 Second and third gas introduction section 76 Process gas inlet 80 Gas inlet 100 Semiconductor substrate 102 Plasma flow

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical indication H01L 21/3065 21/3205 21/768 H01L 21/88 R 21/90 C

Claims (8)

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