JP2000138373A - Semiconductor device and its manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a MOS transistor equipped with a gate electrode of high melting point metallic film, where the gate electrode can be prevented from increasing in resistance, and the MOS transistor can be easily manufactured. SOLUTION: This manufacturing method is carried out in a manner where oxygen is added to a sputtering gas for a prescribed time, oxygen-containing layers 13a and 13b that contain 0.5 to 3 atm.% oxygen are each formed as thick as from about 2 to 50 nm on the uppermost surface and lowermost surface of a high-melting point metallic film 13', when the high-melting point metal film 13' is formed on a gate oxide film 12. The high-melting point metal film 13' is processed by the use of a mask insulating film 21. By this setup, the oxygen-containing layer 13a is formed on the lowermost surface of the high- milting point metallic film 13' that comes into contact with the gate oxide film 12, the oxygen-containing layer 13b is formed on the uppermost surface of the high-melting point metallic film 13' that comes into contact with the mask insulating film 21, and a gate electrode 13 is formed.

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 MOS transistor using a refractory metal for a gate electrode and the like.

[0002]

2. Description of the Related Art Conventionally, in a MOS transistor,
In order to reduce the resistance of the gate electrode and gate electrode wiring,
Various refractory metals are widely used. Among them,
High-melting metals such as Mo (molybdenum), W (tungsten), Mo-W alloy, Ru (ruthenium), Co (cobalt), and Ti (titanium) have low resistance, but have poor adhesion to oxide films. Alternatively, it is not used as a single layer because it is easily oxidized or nitrided, and is used as a silicide or a laminated structure of a refractory metal film and a silicide film.

FIG. 5 shows a schematic configuration of a conventional MOS transistor.

That is, in this MOS transistor, for example, a gate electrode 3 is formed on a main surface of a silicon (Si) substrate 1 with a gate oxide (SiO ₂ ) film 2 interposed therebetween. Except for the formation part, a diffusion layer 4 serving as a source and a drain is formed on the main surface of the Si substrate 1.

The gate electrode 3 is made of, for example, a refractory metal film 3a made of Mo and a silicide of Mo (MoS
i ₂ ) a layered structure with the films 3b, 3b;
By providing the _two films 3b, 3b, the adhesion between the gate oxide film 2 and the refractory metal film 3a and the refractory metal film 3a
Are improved in oxidation resistance and nitridation resistance.

However, since the MoSi ₂ film 3b has a high resistance, when the MoSi ₂ film 3b is provided, there is a disadvantage that the resistance of the gate electrode 3 cannot be sufficiently reduced.

[0007] In particular, when a laminated structure is adopted, there is a problem that the process for forming the gate electrode 3 becomes complicated.

[0008]

As described above, conventionally, the high melting point metal has a low resistance, but when the high melting point metal is used for forming the gate electrode, the gate electrode has a sufficiently low resistance. And the formation of the gate electrode is complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a semiconductor device and a method of manufacturing the same, which can prevent an increase in resistance and can avoid a complicated process.

[0010]

In order to achieve the above object, in a semiconductor device according to the present invention, oxygen or nitrogen is added to a surface of a refractory metal layer which is in contact with a first containing layer containing silicon. In a second content layer containing about 0.5 to 3 atomic%.

Further, in the semiconductor device of the present invention,
A second containing layer containing about 0.5 to 3 atomic% of oxygen or nitrogen between the first containing layer containing silicon and the first containing layer in contact with the first containing layer; And a high melting point metal layer provided via a layer.

In the method of manufacturing a semiconductor device according to the present invention, when the refractory metal layer is formed by the sputtering method, the surface in contact with the first containing layer containing silicon is
A second containing layer containing about 0.5 to 3 atomic% of oxygen or nitrogen is formed.

Further, in the method of manufacturing a semiconductor device according to the present invention, a step of forming a high melting point metal layer by a sputtering method; and, at a predetermined time of forming the high melting point metal layer, adding oxygen or nitrogen to the sputtering gas. Forming a second containing layer containing about 0.5 to 3 atomic% of oxygen or nitrogen on the surface in contact with the first containing layer containing silicon.

According to the semiconductor device and the method of manufacturing the same of the present invention, the adhesion between the first containing layer containing silicon and the high melting point metal layer and the high melting point metal layer can be formed without silicidation or lamination. Oxidation resistance and nitridation resistance can be improved. This makes it possible to easily form the gate electrode and the like while keeping the high melting point metal layer at a sufficiently low resistance.

[0015]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of the present invention.
1 schematically shows a configuration of a MOS transistor.
Here, a case where a gate electrode of a MOS transistor is formed using a high melting point metal will be described.

That is, this MOS transistor is formed, for example, on the main surface of a silicon (Si)
A gate electrode 13 made of a refractory metal (Mo or the like) is formed via a gate oxide (SiO ₂ ) film 12 as a layer containing the same. Except for the portion where the gate electrode 13 is formed, a diffusion layer 14 serving as a source and a drain is formed on the main surface of the Si substrate 11.

The gate electrode 13 has, for example, an oxygen-containing high melting point metal layer (hereinafter simply referred to as an oxygen-containing layer) 1 as a second containing layer on its lowermost surface and its uppermost surface.
3a and 13b are provided respectively.

It should be noted that the sheet resistance is 0.20 Ω / sq.
In order to suppress the oxygen content to below level, the oxygen-containing layers 13a, 13b
For example, as shown in FIG. 2, it is desirable to provide a film having a thickness of 50 nm or less (substantially about 2 to 50 nm).

Similarly, as shown in FIG. 3, the oxygen-containing layers 13a and 13b have an oxygen content of 3 atomic% or less (substantially about 0.5 to 3 atomic%). The sheet resistance can be suppressed to about 0.20 Ω / □ or less.

As described above, by providing the oxygen-containing layer 13a on the lowermost surface of the gate electrode 13 in contact with the gate oxide film 12, the high-melting-point metal remains at a low resistance while the gate oxide film 12 and the gate electrode 13 Can be improved. As a result, peeling (film peeling) between the gate oxide film 12 and the gate electrode 13 can be prevented without increasing the resistance of the gate electrode 13.

When the oxygen-containing layer 13b is provided on the uppermost surface of the gate electrode 13, the gate electrode 1
3 not only can improve the oxidation resistance and nitridation resistance,
Unnecessary reactions with the mask insulating film (patterned CVD oxide film or CVD nitride film) at the time of processing the gate electrode can be suppressed.

Next, a method of manufacturing the MOS transistor having the above-described configuration will be briefly described with reference to FIG.

First, a silicon substrate 11 on which a gate oxide film 12 is formed is prepared, and is set in a sputtering apparatus for forming a high melting point metal film (FIG. 2A).
reference).

Next, a desired sputtering gas is introduced into the apparatus, and the sputtering gas on the main surface of the silicon substrate 11 is removed.
The formation of the refractory metal film 13 'is started (see FIG. 3B). At this time, oxygen is added to the sputtering gas at the beginning and end of the formation of the refractory metal film 13 ′, and oxygen is added to the lowermost surface and the uppermost surface of the refractory metal film 13 ′, respectively. Is formed to a thickness of about 2 to 50 nm.

In this case, at the beginning of the film formation,
For example, oxygen is added to the sputtering gas during a period from the start of sputtering until the oxygen-containing layer 13a having a thickness of about 2 to 50 nm is formed. At the end of the film formation, for example, 2 to 50
In the period from when the refractory metal film 13 ′ is formed to be thinner than the set thickness to the end of the sputtering while leaving the formation of the oxygen-containing layer 13 b having a thickness of about Is added.

Next, CV is applied on the refractory metal film 13 '.
After a silicon oxide film or a silicon nitride film is formed by the method D, the film is patterned by a known technique to form a mask insulating film (first containing layer) 21 for forming a gate electrode (FIG. 1). (C)).

Then, using the mask insulating film 21 as a mask, a part of the refractory metal film 13 'is etched,
Gate electrode 13 having oxygen-containing layers 13a and 13b
Is formed (see FIG. 3D).

Thereafter, the above-described MOS transistor having the structure shown in FIG. 1 is completed by removing the mask insulating film 21, forming the diffusion layer 14, and the like.

As described above, by adding oxygen to the sputtering gas at a predetermined time when the refractory metal film 13 ′ is formed, the lowermost surface of the gate electrode 13 in contact with the gate oxide film 12 and the insulating film 21 for the mask are formed. Oxygen-containing layers 13a and 13b are provided on the uppermost layer surface in contact with each other. This eliminates the need for a troublesome process for forming a stacked structure as compared with a case where a gate electrode is formed by a stacked structure of a silicide layer and a high melting point metal film.
The formation can be easily performed, and the processing accuracy and yield can be remarkably improved.

As described above, the adhesion between the gate oxide film and the gate electrode and the oxidation resistance and the nitridation resistance of the gate electrode (high melting point metal film) can be improved without forming a silicide or a laminated structure. Like that.

That is, oxygen is added to the sputtering gas at a predetermined time when the refractory metal film is formed, so that an oxygen-containing layer is provided on the lowermost surface of the gate electrode in contact with the gate oxide film. This can improve the adhesion between the gate oxide film and the gate electrode,
Since the high-resistance silicide layer is not used, it is possible to suppress the gate electrode from increasing in resistance.

When an oxygen-containing layer is provided on the uppermost surface of the gate electrode in contact with the mask insulating film, not only can the oxidation or nitridation of the gate electrode (high-melting metal film) be reduced, but also the mask can be reduced. Unnecessary reaction with the insulating film for use can be prevented.

Therefore, compared to the case of using a silicide layer, the refractory metal film has a sufficiently low resistance, and
The gate electrode can be easily formed with high accuracy.

In the above-described embodiment,
The case where the oxygen-containing layer is provided on the lowermost surface and the uppermost surface of the gate electrode by adding oxygen to the sputtering gas has been described, but is not limited thereto.
For example, a nitrogen-containing layer (second containing layer) may be provided by adding nitrogen to the sputtering gas. In this case, substantially the same effect as when the oxygen-containing layer is provided can be expected.

The present invention is not limited to the case where a gate electrode is formed, but is also applicable to a case where a wiring using a high melting point metal film, a gate electrode wiring connected to a contact or a gate electrode, and the like are formed.

The present invention is not limited to the case where a high-melting-point metal film is formed on a gate oxide film. For example, a high-melting-point metal film is formed on a polysilicon film, and the polysilicon film and the high-melting-point metal film are formed. The present invention can be applied to a case where a gate electrode or the like having a stacked structure is formed.

In addition, it goes without saying that various modifications can be made without departing from the scope of the present invention.

[0039]

As described in detail above, according to the present invention, there is provided a semiconductor device capable of preventing an increase in resistance and eliminating complication of steps, and a method of manufacturing the same. it can.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a configuration of a MOS transistor according to an embodiment of the present invention.

FIG. 2 is a schematic characteristic diagram similarly illustrating a relationship between a film thickness of an oxygen-containing layer and a sheet resistance.

FIG. 3 is a schematic characteristic diagram similarly illustrating a relationship between an oxygen content and a sheet resistance in an oxygen-containing layer.

FIG. 4 is a process sectional view similarly illustrating the method of manufacturing a MOS transistor;

FIG. 5 is a diagram showing M to explain a conventional technique and its problems;
FIG. 3 is a schematic cross-sectional view of an OS transistor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Silicon substrate 12 ... Gate oxide film 13 ... Gate electrode 13a ... Oxygen-containing layer (lowest surface side) 13b ... Oxygen-containing layer (top surface side) 13 '... High melting point metal film 14 ... Diffusion layer 21 ... Mask insulation film

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4M104 AA01 BB01 BB16 BB39 CC01 CC05 DD37 DD42 DD71 EE05 FF13 GG09 GG10 GG14 HH16 5F033 HH20 LL03 PP16 QQ08 QQ28 RR04 RR06 SS11 VV06 WW00 XX02 XX00 XX00 XX00 XX00 XX00 XX00 XX00 EC08 EC12

Claims (23)

[Claims] 1. A high-melting-point metal layer provided with a second containing layer containing about 0.5 to 3 atomic% of oxygen or nitrogen on a surface in contact with the first containing layer containing silicon. Semiconductor device. 2. The wiring and the gate electrode, wherein the first containing layer is a silicon oxide film, and the refractory metal layer is provided at least with the second containing layer on its lowermost surface. 2. The semiconductor device according to claim 1, wherein the semiconductor device is any one of a gate electrode wiring connected to a gate electrode. 3. The wiring and the gate electrode, wherein the first containing layer is a polysilicon film, and the refractory metal layer is provided with at least the second containing layer on the lowermost surface thereof. 2. The semiconductor device according to claim 1, wherein the semiconductor device is any one of a gate electrode wiring connected to a gate electrode. 4. The method according to claim 1, wherein the first containing layer comprises C for patterning.
A VD oxide film or a CVD nitride film, wherein the refractory metal layer is provided with at least the second content layer on the uppermost surface thereof, and is provided with a wiring, a gate electrode, or a gate electrode connected to the gate electrode. 2. The semiconductor device according to claim 1, wherein the semiconductor device is one of a wiring. 5. The semiconductor according to claim 1, wherein the second containing layer is formed by adding oxygen or nitrogen to a sputtering gas when forming the high melting point metal layer. apparatus. 6. The semiconductor device according to claim 1, wherein the second containing layer has a thickness of about 2 to 50 nm. 7. A silicon-containing first containing layer, and oxygen or nitrogen containing about 0.5 to 3 atomic% between the first containing layer and the first containing layer. Second
And a high melting point metal layer provided with a layer containing the following. 8. The wiring and gate electrode, wherein the first containing layer is a silicon oxide film, and the refractory metal layer is provided with at least the second containing layer on the lowermost surface thereof. 8. The semiconductor device according to claim 7, wherein the semiconductor device is any one of a gate electrode wiring connected to a gate electrode. 9. The wiring and the gate electrode, wherein the first containing layer is a polysilicon film, and the refractory metal layer is provided with at least the second containing layer on the lowermost surface thereof. 8. The semiconductor device according to claim 7, wherein the semiconductor device is any one of a gate electrode wiring connected to a gate electrode. 10. The first containing layer is a CVD oxide film or a CVD nitride film for patterning, and the refractory metal layer is provided with at least the second containing layer on the uppermost surface thereof. 8. The semiconductor device according to claim 7, wherein the semiconductor device is one of a wiring, a gate electrode, and a gate electrode wiring connected to the gate electrode. 11. The semiconductor according to claim 7, wherein the second containing layer is formed by adding oxygen or nitrogen to a sputtering gas when forming the high melting point metal layer. apparatus. 12. The semiconductor device according to claim 7, wherein said second containing layer has a thickness of about 2 to 50 nm. 13. A second content layer containing about 0.5 to 3 atomic% of oxygen or nitrogen on a surface which is in contact with a first content layer containing silicon when a refractory metal layer is formed by a sputtering method. Forming a semiconductor device. 14. The first content layer is a silicon oxide film, and the refractory metal layer has at least the second content layer on the lowermost surface thereof, and has a wiring, a gate electrode, or 14. The method of manufacturing a semiconductor device according to claim 13, wherein one of the gate electrode wirings connected to the gate electrode is formed. 15. The first content layer is a polysilicon film, and the refractory metal layer has at least the second content layer on the lowermost surface thereof, and is provided with a wiring, a gate electrode, or 14. The method for manufacturing a semiconductor device according to claim 13, wherein one of the gate electrode wirings connected to the gate electrode is formed. 16. The first content layer is a CVD oxide film or a CVD nitride film for patterning, and the refractory metal layer has at least the second content layer on the uppermost surface thereof, 14. The method for manufacturing a semiconductor device according to claim 13, wherein any one of a gate electrode, and a gate electrode wiring connected to the gate electrode is formed. 17. The method according to claim 13, wherein the formation of the second containing layer is performed by adding oxygen or nitrogen to a sputtering gas when forming the high melting point metal layer. A method for manufacturing a semiconductor device. 18. The method according to claim 1, wherein the second containing layer has a thickness of about 2 to 50 nm.
4. The method for manufacturing a semiconductor device according to item 3. 19. A step of forming a refractory metal layer by a sputtering method, and at a predetermined time of forming the refractory metal layer, adding oxygen or nitrogen to the sputtering gas to form a first containing layer containing silicon. Oxygen or nitrogen 0.5 to 3
Forming a second containing layer containing about atomic% of the semiconductor device. 20. The first containing layer is a silicon oxide film, and the refractory metal layer has at least the second containing layer on the lowermost surface thereof, and has a wiring, a gate electrode, or 20. The method for manufacturing a semiconductor device according to claim 19, wherein any one of the gate electrode wirings connected to the gate electrode is formed. 21. The first content layer is a polysilicon film, and the refractory metal layer has at least the second content layer on the lowermost surface thereof, and has a wiring, a gate electrode, or 20. The method for manufacturing a semiconductor device according to claim 19, wherein any one of the gate electrode wirings connected to the gate electrode is formed. 22. The first content layer is a CVD oxide film or a CVD nitride film for patterning, and the refractory metal layer has at least the second content layer on the uppermost surface thereof, and has a wiring 20. The method of manufacturing a semiconductor device according to claim 19, wherein any one of a gate electrode, and a gate electrode wiring connected to the gate electrode is formed. 23. The formation of the second containing layer may be performed at the initial stage or at the end of the formation of the refractory metal layer, or
20. The method according to claim 19, wherein the thickness is controlled to be about 2 to 50 nm at both times.