JPH10321799A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable preventing deterioration of characteristics of a semiconductor element caused by hydrogen, in a semiconductor device having a manufacturing process using a gas containing hydrogen. SOLUTION: A semiconductor device is constituted of a base substrate 10, a capacitor which is formed on the base substrate and has a storage electrode 46, a dielectric film 48 formed on the storage electrode 46, and counter electrodes 54 formed on the dielectric film 48, and a hydrogen occlusion metal film 56 formed on the counter electrodes 54. Then hydrogen permeating from the surface side of the substrate is trapped by the hydrogen occlusion metal film 56, and hydrogen reaching the dielectric film 48 and deteriorates capacitor characteristics is prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device and a method of manufacturing the same, and more particularly, to a semiconductor device and a method of manufacturing a semiconductor device which prevent deterioration of characteristics of a semiconductor element due to hydrogen in a manufacturing process using a gas containing hydrogen.

[0002]

2. Description of the Related Art With the recent demand for large-scale integration and high performance of LSIs, further miniaturization of semiconductor elements themselves has been attempted. Accordingly, there is an increasing need to strictly control electrical characteristics required for semiconductor elements. The electrical characteristics of a semiconductor device are adjusted according to various parameters in the manufacturing process, but the manufacturing process itself may affect the characteristics of the semiconductor device, and how to suppress such process-induced characteristic deterioration. Is one of the future issues.

[0003] The manufacturing process itself depends on the electrical characteristics of the semiconductor device.
One of the effects on water quality is the water used in the manufacturing process.
The effects of gases containing sulfur are known. For example, silicon
In MOS integrated circuit devices,
If hydrogen is present in the process atmosphere, hydrogen will be trapped in the device.
Interface state and SiO _TwoFixed charge or
MOS transistors may cause an increase in the lap level.
Threshold voltage V_thAnd channel conductance g_m
May result in a decrease.

Further, in a capacitor used in a DRAM or the like, when hydrogen is taken into a capacitor dielectric film such as a nitrided oxide film or a high dielectric film, a leak current increases, resulting in deterioration of charge retention characteristics and the like. Sometimes. In a recent semiconductor device, such an influence of hydrogen on electric characteristics cannot be ignored, and a semiconductor device and a method of manufacturing the semiconductor device that effectively eliminates the influence of hydrogen are desired.

As a semiconductor device for preventing a change in the electrical characteristics of a semiconductor element due to hydrogen, for example, a semiconductor device using a hydrogen storage metal is disclosed in, for example, Japanese Patent Application Laid-Open No. Sho 59-10054.
No. 1 proposes this. JP-A-59-100
No. 541 discloses a semiconductor device comprising SiH ₄ or N 2 used for depositing an insulating film 108 by a plasma CVD method.
In order to prevent the effect of hydrogen contained in H ₃ ,
The Ti film 106, which is a hydrogen storage metal,
10 is deposited, and hydrogen mixed into the insulating film 108 at the same time that the insulating film 108 is deposited is captured by the Ti films 106 and 110 (see FIG. 7).

By capturing hydrogen with the Ti films 106 and 110 as described above, it is possible to prevent hydrogen in the film from entering the lower layer region which affects the electrical characteristics of the element, thereby improving the reliability of the semiconductor device. Can be improved.

[0007]

However, in the semiconductor device described in Japanese Patent Application Laid-Open No. 59-100541, a hydrogen storage metal is inserted between the interlayer insulating films, so that a multilayer wiring structure in which wiring is performed via the interlayer insulating film. In such cases, it is necessary to previously pattern the hydrogen storage metal film.
For this reason, in the current semiconductor device, it is not currently employed for reasons such as complicating the manufacturing process, and it has not been possible to prevent deterioration of electrical characteristics such as a capacitor due to hydrogen in the film. .

Further, the semiconductor device described in Japanese Patent Application Laid-Open No. Sho 59-100541 discloses a P-type semiconductor device used as a final insulating protective film.
-To prevent the influence of hydrogen in the SiN film (silicon nitride film formed by the plasma CVD method),
It was not possible to prevent the effect of the hydrogen introduced in the earlier steps. For example, when Al is used as a wiring material, annealing with a mixed gas of hydrogen and nitrogen is generally performed after forming a wiring (corresponding to the wiring layer 102 in FIG. 7). However, it was not possible to prevent the intrusion of hydrogen by this annealing.

An object of the present invention is to provide a semiconductor device capable of improving the electrical characteristics of a semiconductor device by preventing diffusion of hydrogen existing in an insulating film or hydrogen from a gas phase, and a method of manufacturing the same. It is in.

[0010]

An object of the present invention is to provide a base substrate, a storage electrode formed on the base substrate, a dielectric film formed on the storage electrode, and a dielectric film formed on the dielectric film. And a hydrogen storage metal film formed on the counter electrode. If the semiconductor device is configured as described above and the hydrogen storage metal film is provided on the counter electrode, even if a process using a gas containing hydrogen is performed in the process after the formation of the capacitor, the hydrogen invading from the surface side of the substrate can be used. Is trapped by the hydrogen storage metal film and does not reach the dielectric film, so that deterioration of the characteristics of the capacitor due to hydrogen can be suppressed. The hydrogen penetration, such as the threshold voltage V _th and the channel conductance g _m, it also influences the characteristics of the MOS transistor, significantly the probability that hydrogen reaches the underlying substrate by providing a hydrogen storage metal film on the counter electrode Therefore, the reliability of the characteristics of the transistor formed on the base substrate can be improved.

[0011] Further, the object is to provide a base substrate, a storage electrode formed on the base substrate, a dielectric film formed on the storage electrode, and a counter electrode formed on the dielectric film. In the semiconductor device having the capacitor having the above structure, the counter electrode and / or the storage electrode has a hydrogen storage metal film. The same effect can be obtained even if the hydrogen storage metal is configured to be included in a part of the counter electrode.

[0012] Further, the object is to form an insulating film on a base substrate, to form a hydrogen storage metal film on the insulating film, and to perform a predetermined heat treatment to reduce the hydrogen in the insulating film. The method is also achieved by a method of manufacturing a semiconductor device, comprising: a hydrogen desorbing step of taking in a hydrogen storage metal film in a hydrogen storage metal film; and a hydrogen storage metal film removing step of removing the hydrogen storage metal film in which the hydrogen has been captured. You. By manufacturing a semiconductor device in this manner, the concentration of hydrogen in the insulating film can be reduced, so that the effect of hydrogen contained in the insulating film on device characteristics can be reduced. Further, since no hydrogen storage metal film remains in the final semiconductor device, heavy metal contamination by the hydrogen storage metal can be prevented.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION

[First Embodiment] The semiconductor device and the method for fabricating the same according to a first embodiment of the present invention will be explained with reference to FIGS.
FIG. 1 is a schematic sectional view showing the structure of the semiconductor device according to the present embodiment, FIGS. 2 to 4 are process sectional views showing a method of manufacturing the semiconductor device according to the present embodiment, and FIG. 5 is a semiconductor device according to a modification of the present embodiment. It is a schematic sectional drawing which shows the structure of.

First, the structure of the semiconductor device according to the present embodiment will be explained. The semiconductor device according to the present embodiment includes:
The present invention is applied to the semiconductor device described in JP-A-8-274278, and is characterized in that a hydrogen storage metal film is provided on a capacitor counter electrode of a DRAM. An element isolation film 12 is formed on the silicon substrate 10, and an element region is defined by the element isolation film 12. Source / drain diffusion layers 24 and 26 are independently formed in the element region. A gate electrode 20 is formed on the semiconductor substrate 10 between the source / drain diffusion layers 24 and 26 via a gate oxide film 16. Thus, a memory cell transistor including the gate electrode 20 and the source / drain diffusion layers 24 and 26 is formed.

On the semiconductor substrate 10 on which the memory cell transistor is formed, a through hole 38 opened on the source / drain diffusion layer 26 and a through hole 40 opened on the source / drain diffusion layer 24 are formed. The formed interlayer insulating film 36 is formed. The gate electrode 20
Has an insulating film 42 formed in a self-aligned manner so as to surround the gate electrode 20.
0 is formed in the insulating film 42 by self-alignment.

A storage electrode 46 is formed on the inner wall of the through hole 40 and on the source / drain diffusion layer 24.
The bottom of the through hole 40 is connected to the source / drain diffusion layer 24. On the inner surface and the upper surface of the storage electrode 46, a dielectric film 48 is formed. A counter electrode 54 is formed in the through hole 40 where the storage electrode 46 and the dielectric film 48 are formed and on the interlayer insulating film 36. Thus, a capacitor including the storage electrode 46, the dielectric 48, and the counter electrode 54 is formed.

On the counter electrode 54, a Ti film, a Mg film,
A hydrogen storage metal film 56 made of a metal film having a property of storing hydrogen, such as an i film, is formed. Through hole 3
8, a contact conductive film 44 is formed on the inner wall,
It is connected to a bit line 62 arranged in a direction orthogonal to a word line (gate electrode 20) via an interlayer insulating film 58 formed on the counter electrode 54.

Further, a wiring layer 70 is formed above the bit line 62 with an interlayer insulating film 64 interposed therebetween, and a DRAM comprising one transistor and one capacitor is formed. As described above, in the semiconductor device according to the present embodiment, since the hydrogen storage metal film 56 is provided on the counter electrode 54, even when a process using a gas containing hydrogen is performed in the step after the formation of the capacitor, the surface side of the substrate can be used. Hydrogen invading from the metal is trapped by the hydrogen storage metal film 56 and does not reach the dielectric film 48, so that deterioration of the characteristics of the capacitor due to hydrogen can be suppressed.

For example, the interlayer insulating films 58 and 6 are formed by a CVD method using a gas containing hydrogen such as SiH ₄ gas or H ₂ gas.
In the case of forming the silicon nitride film 4, a large amount of hydrogen may be mixed into the film. However, even if this hydrogen atom is diffused by a heat treatment in a later process, the hydrogen is trapped in the hydrogen storage metal film 56 and the dielectric film is formed. Since it does not reach 48, the characteristics of the capacitor do not deteriorate.

When the wiring layer 70 made of an Al film is formed, annealing using a mixed gas of hydrogen and nitrogen is performed after the formation of the wiring layer 70 in order to remove oxygen contained in the Al film. Even if the hydrogen contained therein penetrates into the substrate, it is trapped by the hydrogen storage metal film 56 and the dielectric film 48
, The characteristic of the capacitor is not degraded in this case.

Although the intrusion of hydrogen affects the characteristics of the MOS transistor, such as the threshold voltage V _th and the channel conductance g _m , the provision of the hydrogen absorbing metal film 56 on the counter electrode 54 allows hydrogen to enter the transistor. Since the probability of reaching the transistor can be greatly reduced, the reliability of transistor characteristics can be improved. Next, the method for fabricating the semiconductor device according to the present embodiment will be explained.

First, in the same manner as in a normal MOS transistor forming method, a silicon substrate 1 on which an element region is defined is formed.
0, the source / drain diffusion layers 24 and 26 and the gate electrode 20 are provided.
(See FIG. 2)
(A)). Next, the source / drain diffusion layers 2 are formed on the silicon substrate 10 on which the memory cell transistors are formed.
An interlayer insulating film 36 having through holes 38 and 40 reaching the holes 4 and 26 is formed (FIG. 2B).

Subsequently, after the conductive film is deposited, the conductive film on the interlayer insulating film 36 is selectively removed, and the contact conductive film 44 formed on the inner wall of the through hole 38 and the conductive film 44 formed on the inner wall of the through hole 40 are formed. The storage electrode 46 is formed (FIG. 2C). Thereafter, a dielectric film 48 made of, for example, a nitrided oxide film or a tantalum oxide film is formed on the surface of the storage electrode 46. Note that the effect of the present invention can be particularly expected in a semiconductor device using a tantalum oxide film, since the tantalum oxide film significantly increases the leakage current due to hydrogen.

Next, a conductive film 50 serving as a counter electrode, a hydrogen storage metal film 56, and an interlayer insulating film 58 are successively formed (FIG. 3A), and these laminated films are formed in a single lithography step. Simultaneously pattern. Thus, the counter electrode 54 whose upper surface is covered with the hydrogen storage metal film 56 is formed (FIG. 3B). Thereafter, for example, Japanese Patent Application Laid-Open No. 8-27427
No. 8, a bit line 62, an interlayer insulating film 64, a wiring layer 70, etc.
A DRAM having a memory cell including a transistor and a capacitor is manufactured (FIG. 4).

As described above, according to the method for fabricating the semiconductor device according to the present embodiment, the hydrogen storage metal film is provided without complicating the fabrication process of the conventional semiconductor device, particularly without increasing the number of lithography processes. be able to. Note that the present invention is not limited to the above embodiment, and various modifications are possible. For example, in the above embodiment, Japanese Patent Application Laid-Open No. 8-2742
Although an example in which the present invention is applied to the semiconductor device described in Japanese Patent Publication No. 78 is shown, the present invention can be similarly applied to a semiconductor device having capacitors having various structures. In this case, if the counter electrode is formed of a conductive film including a hydrogen storage metal film instead of the conventional counter electrode, the above effects can be obtained without complicating the manufacturing process.

In the above embodiment, the hydrogen storage metal film 56 is provided on the counter electrode 54, but a hydrogen storage metal film may be inserted into a part of the counter electrode 54. For example, as shown in FIG. 5, a hydrogen storage metal film 56 made of a Ti film is
The opposing electrode 54 may be constituted by the laminated films formed between the N films 54a and 54b. Also,
Not only the counter electrode 54 but also the storage electrode 46 may have such a structure. Further, only the storage electrode may have such a structure.

[Second Embodiment] The method for fabricating a semiconductor device according to a second embodiment of the present invention will be explained with reference to FIG. FIG. 6 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the present embodiment. In the method for fabricating a semiconductor device according to the first embodiment, a semiconductor device capable of preventing intrusion of hydrogen by forming a hydrogen storage metal film on the capacitor counter electrode 54 and a method for fabricating the same are provided.

However, depending on the hydrogen storage metal,
It may cause heavy metal contamination such as formation of a deep level in a semiconductor, and it may be desirable that the metal does not remain in the final form. The present embodiment provides a method for manufacturing a semiconductor device capable of reducing the influence of hydrogen in the course of a process while preventing contamination by a hydrogen storage metal.

First, a contact conductive film 44 and a storage electrode 46 are formed in the same manner as in FIGS. 2A to 2C. Next, a dielectric film 48 made of, for example, a nitrided oxide film or a tantalum oxide film is formed on the surface of the storage electrode 46. Subsequently, a conductive film 50 serving as a counter electrode, an interlayer insulating film 58, and a hydrogen storage alloy film 60 are successively deposited (FIG. 6A).

Thereafter, a predetermined heat treatment for desorbing hydrogen is performed. When hydrogen is contained in the interlayer insulating film 58, this heat treatment accelerates the dehydrogenation reaction at the interface between the interlayer insulating film 58 and the hydrogen storage metal film 60, and selectively converts hydrogen in the interlayer insulating film 58 to hydrogen. It can be stored in the storage metal film 60. As a result, the hydrogen concentration in the interlayer insulating film 58 decreases, and the interlayer insulating film 58 with the reduced hydrogen concentration
a will be formed. Therefore, the amount of hydrogen diffused in the direction of the capacitor due to the heat treatment in the subsequent step is significantly reduced, and deterioration of the capacitor characteristics can be prevented.

As a heat treatment for desorbing hydrogen, for example, a heat treatment in a nitrogen atmosphere at a temperature of about 300 to 500 ° C. in a vacuum is effective. It is desirable that the heat treatment conditions are appropriately set according to the material of the insulating film and the like. Subsequently, the hydrogen storage metal film 60 in which hydrogen has been stored is selectively removed (FIG. 6B). Thereby, it is possible to prevent the occurrence of contamination due to the hydrogen storage metal film 60 due to a heat treatment in a later step. Further, there is no occurrence of re-desorption of hydrogen from the hydrogen storage metal film 60 storing hydrogen.

After that, when the semiconductor device is manufactured in the same manner as the method of manufacturing the semiconductor device according to the first embodiment shown in FIGS. 3B to 4, the semiconductor device in which the hydrogen concentration of the interlayer insulating film 58 is reduced. Can be manufactured. in this way,
According to the present embodiment, a hydrogen storage metal film is deposited on an insulating film containing hydrogen at a high concentration in the film, and a predetermined heat treatment is performed to trap the hydrogen in the insulating film. Since the occluded metal is removed, the effect of hydrogen contained in the insulating film on device characteristics can be reduced. Further, since no hydrogen storage metal film remains in the final semiconductor device, heavy metal contamination by the hydrogen storage metal can be prevented.

In the above embodiment, an example in which hydrogen is trapped in the interlayer insulating film 58 on the counter electrode 54 has been described. However, the present invention can be applied to an interlayer insulating film of any semiconductor device. it can. [Modified Embodiments] The present invention is not limited to the above embodiment, and various modifications are possible.

For example, in the above embodiment, an example was shown in which Ti, Mg, and Ni were used as the hydrogen storage metal, but V (vanadium), Nb (niobium), Zr (zirconium),
Hf (hafnium), Ta (tantalum), Sc (scandium), Y (yttrium), Lu (lutetinium), lanthanum-based metals, alloys or composites composed of at least two or more metal elements selected from these metallurgical groups Film, Fe-Ti alloy, Mg-Cu alloy, Zr-Ni
The same effect can be obtained by using another metal having a function of absorbing hydrogen, such as an alloy, a Ti-Ni alloy, or a Ti-Cu alloy.

In the above embodiment, a DRAM has been described as an example. However, the present invention can be widely applied to a semiconductor device in which characteristics may be degraded by hydrogen. In this case, it is effective to provide a hydrogen storage metal at least in a portion where characteristics are deteriorated by hydrogen.

[0036]

As described above, according to the present invention, the base substrate, the storage electrode formed on the base substrate, the dielectric film formed on the storage electrode, and the dielectric film formed on the dielectric film are formed. Since a semiconductor device is constituted by a capacitor having a counter electrode and a hydrogen storage metal film formed on the counter electrode, even when a process using a hydrogen-containing gas is performed in a step after formation of the capacitor, the substrate is Hydrogen that has entered from the surface side is trapped by the hydrogen storage metal film and does not reach the dielectric film, so that deterioration of the characteristics of the capacitor due to hydrogen can be suppressed. The hydrogen penetration, such as the threshold voltage V _th and the channel conductance g _m, it also influences the characteristics of the MOS transistor, significantly the probability that hydrogen reaches the underlying substrate by providing a hydrogen storage metal film on the counter electrode Therefore, the reliability of the characteristics of the transistor formed on the base substrate can be improved.

A base substrate; a storage electrode formed on the base substrate; a dielectric film formed on the storage electrode;
In a semiconductor device having a capacitor having a counter electrode formed on a dielectric film and a capacitor having a hydrogen storage metal film, a similar effect can be obtained by configuring a storage electrode. Further, a step of forming an insulating film on the base substrate, a step of forming a hydrogen storage metal film on the insulating film, and a predetermined heat treatment are performed to take in hydrogen in the insulating film into the hydrogen storage metal film. By manufacturing the semiconductor device by the step and the step of removing the hydrogen storage metal film in which hydrogen has been taken in, the concentration of hydrogen in the insulating film can be reduced. Thus, the effect of hydrogen contained in the insulating film on device characteristics can be reduced. Further, since no hydrogen storage metal film remains in the final semiconductor device, heavy metal contamination by the hydrogen storage metal can be prevented.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing the structure of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a process sectional view (part 1) illustrating the method for fabricating the semiconductor device according to the first embodiment of the present invention;

FIG. 3 is a sectional view (part 2) illustrating the method for manufacturing the semiconductor device according to the first embodiment of the present invention;

FIG. 4 is a process sectional view (part 3) illustrating the method for fabricating the semiconductor device according to the first embodiment of the present invention;

FIG. 5 is a schematic sectional view showing the structure of a semiconductor device according to a modification of the first embodiment.

FIG. 6 is a process sectional view illustrating the method for manufacturing the semiconductor device according to the second embodiment of the present invention;

FIG. 7 is a schematic sectional view showing the structure of a conventional semiconductor device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Silicon substrate 12 ... Element isolation film 16 ... Gate oxide film 20 ... Gate electrode 24 ... Source / drain diffused layer 26 ... Source / drain diffused layer 36 ... Interlayer insulating film 38 ... Through hole 40 ... Through hole 42 ... Insulating film 44 ... conductive film for contact 46 ... storage electrode 48 ... dielectric film 50 ... conductive film 54 ... counter electrode 56 ... hydrogen storage metal 58 ... interlayer insulation film 60 ... hydrogen storage metal 62 ... bit line 64 ... interlayer insulation film 70 ... wiring layer Reference Signs List 100 silicon substrate 102 wiring layer 104 interlayer insulating film 106 Ti film 108 interlayer insulating film 110 Ti film

Claims (3)

[Claims] A capacitor formed on the base substrate and having a storage electrode; a dielectric film formed on the storage electrode; and a counter electrode formed on the dielectric film. And a hydrogen storage metal film formed on the counter electrode. A capacitor formed on the base substrate, the storage electrode, a dielectric film formed on the storage electrode, and a counter electrode formed on the dielectric film. The semiconductor device according to claim 1, wherein the counter electrode and / or the storage electrode includes a hydrogen storage metal film. A step of forming an insulating film on the base substrate; a step of forming a hydrogen storage metal film on the insulating film; and performing a predetermined heat treatment to reduce the hydrogen in the insulating film to the hydrogen storage metal film. A method for manufacturing a semiconductor device, comprising: a step of desorbing hydrogen to be taken in; and a step of removing a hydrogen storage metal film that removes the hydrogen storage metal film in which the hydrogen is taken.