JPH06340970A - Production of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a semiconductor device capable of forming a Ti film and a TiN film in one chamber only by changing an atmospheric gas and capable of successively forming a Ti film and a TiN film on another substrate in the same chamber. CONSTITUTION:A Ti film is formed in the sputtering time shown by (I) in the figure, then gaseous nitrogen is introduced to form a Ti-rich TiN film, and a stoichiometric TiN film begins to form after 10sec in the sputtering time (II) when the partial nitrogen pressure is stabilized. The supply of gaseous nitrogen is stopped in the sputtering time (III) in the sequence of sputtering, and sputtering is conducted with gaseous argon only.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a manufacturing method suitable for manufacturing a semiconductor device in which a metal film is formed on a substrate and a metal nitride film is formed on the metal film. Regarding the method.

[0002]

2. Description of the Related Art Conventionally, a Ti film and a TiN film are sequentially formed on a surface of a Si substrate by a sputtering method as a method most often used for establishing electrical conduction between a Si substrate and a metal wiring. Then, this Si substrate is annealed at a temperature in the range of 600 ° C. to 700 ° C., and Ti and Si are reacted to produce TiS.
A method is known in which i (titanium silicide) is formed and a TiSi / Si contact is formed by contacting TiSi and a Si substrate. In order to form a Ti film and a TiN film on the surface of the Si substrate by the sputtering method, at least two sputtering steps are required. In the first sputtering process, in a sputtering chamber that uses Ti as a target, while using argon gas as the sputtering gas, S
A Ti film is formed by performing Ti sputtering on the i substrate. Subsequently, in the second sputtering step, the Si substrate on which the Ti film is formed is transferred to another sputtering chamber that also targets Ti, and nitrogen gas is introduced into this sputtering chamber to form a TiN film. Reactive sputtering is performed.

In the above sputtering process, Ti film and T
The reason why the sputtering for forming the iN film is performed in different chambers will be described. When a Ti film is formed on a Si substrate in one sputtering chamber that uses Ti as a target, and then reactive sputtering for forming a TiN film is performed in the same sputtering chamber, the Ti target is generated during this reactive sputtering. By reacting with nitrogen gas, TiN is formed on the surface of the Ti target. When Ti is sputtered on the next Si substrate in the Ti target state where TiN is formed on the surface, the material that is first sputtered and reaches the surface of the Si substrate is TiN, not Ti. Contact. Therefore, the contact is formed of an alloy of Ti and Si containing TiN, or
The alloying reaction between Si and Si is hindered by TiN and does not proceed sufficiently, resulting in a problem that a good contact is not formed. In order to solve this problem by a method of forming both a Ti film and a TiN film by using one sputtering chamber, after the TiN film is formed and before the Ti film is formed on the next Si substrate, the target surface is formed. Therefore, the number of steps for performing sputtering using a dummy wafer in order to remove TiN is increased, which is not practical in mass production.

Next, the formation of via metal in the multilayer wiring will be described. Even in the formation of via metal, since two layers of Ti film and TiN film are formed on the wiring,
It is necessary to form the film and the TiN film in this order. The TiN film serves as a base of the AlCu (Si) wiring, and as a part of the laminated wiring, EM (electromigration) and S
It is formed for the purpose of improving resistance to M (stress migration). AlCu of the lower layer wiring exposed at the bottom of the via hole without forming the TiN film on the Ti film.
When formed directly on (Si), this AlCu (S) is formed by the nitrogen gas plasma used in the reactive sputtering.
AlN (aluminum nitride) is formed on the surface of i). Since this AlN has high resistance, there arises a problem that it interferes with conduction of the via. Therefore, also in the via metal forming step, the Ti film needs to be formed before the TiN film is formed, as in the contact forming step. Therefore, similarly to the case of forming the contact, the Ti film and the TiN film need to be formed in two separate chambers.

[0005]

SUMMARY OF THE INVENTION In the above prior art,
Two sputtering chambers targeting Ti are required to form contacts and via metals that are practically good for mass production. For this reason, there is a problem that it causes an increase in capital investment and an increase in manufacturing cost. Further, it is necessary to transfer the wafer from the Ti film forming sputtering chamber to the TiN film forming sputtering chamber, which requires a long process time and lowers throughput.

In view of the above circumstances, it is an object of the present invention to provide a semiconductor device manufacturing method which suppresses an increase in capital investment and manufacturing cost and improves throughput.

[0007]

In order to achieve the above object, a method of manufacturing a semiconductor device according to the present invention is as follows: (1) Argon gas is introduced into a sputtering chamber to create an argon gas atmosphere in the argon gas atmosphere. Plasma is generated by sputtering and a target for forming a metal film is sputtered to form the metal film on the substrate. (2) After the metal film is formed, the plasma in the sputtering chamber is maintained. Introducing nitrogen gas into the argon gas atmosphere to make the argon gas atmosphere a mixed gas atmosphere of argon gas and nitrogen gas, and sputtering the target in the mixed gas atmosphere to deposit metal nitride on the metal film. Step of forming a film (3) After forming the metal nitride film, conduct the nitrogen gas while maintaining the plasma in the sputtering chamber. Stopping the mixed gas atmosphere to an argon gas atmosphere, sputtering the target in the argon gas atmosphere to form a metal film on the metal nitride film, and (4) after the step, It is characterized in that the step of taking out the substrate from the sputtering chamber and loading a new substrate into the sputtering chamber is repeated.

It is preferable that the metal film is a Ti film and the metal nitride film is a TiN film. Also,
The sputtering time for forming the TiN film is 25 seconds to 1
It is preferable to perform this for 00 seconds.

[0009]

According to the method of manufacturing a semiconductor device of the present invention, the sputtering for forming the metal film and the sputtering for forming the metal nitride film are performed in one sputtering chamber while maintaining the plasma state. The metal film is formed by sputtering using only argon gas, and then nitrogen gas is introduced into the argon gas atmosphere to form a mixed gas atmosphere in order to perform sputtering for forming the metal nitride film. As a result, the metal nitride film is formed while maintaining the plasma state. Here, when sputtering is performed for 25 seconds to 100 seconds to form the metal nitride film, the mixed gas atmosphere is stabilized in plasma after the introduction of nitrogen gas, and the metal nitride film functions as a barrier metal. Formed to have a sufficient thickness. Then, S to be processed next
A step for preparing the i substrate is performed. In this step, after the metal nitride film is formed on the Si substrate being processed, the introduction of nitrogen gas is stopped, the inside of the sputtering chamber is switched to an argon gas atmosphere, and sputtering is performed in this argon gas atmosphere. . At this time, the Si substrate being processed is in a state where the film formation by sputtering is continued. Therefore, the formed film is gradually changed from the metal nitride film to a metal-rich film, and the metal film is formed in the uppermost layer. Further, the target surface is nitrided when the metal nitride film is formed, but since the nitride is removed from the target surface in this final sputtering step, the target surface returns to a pure state.

As a result, the metal film and the metal nitride film are continuously formed in one sputtering chamber only by introducing the nitrogen gas for a short time on the way and stopping it, and by only one sputtering. It Further, the nitride is removed from the target surface after the processing of the Si substrate is completed. Therefore, the previous film forming process does not affect the next film forming process. As a result, since the Si substrate to be processed next can be directly sputtered without spattering for removing the nitride on the target surface,
It is efficient in mass production.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for manufacturing a semiconductor device of the present invention will be described below with reference to the drawings. 1 is a cross-sectional view showing a manufacturing process of a semiconductor device, FIG. 2 is a graph showing a sputtering sequence, and FIG. 3 is a perspective view showing a target having TiN formed on its surface. First, the S formed on the Si substrate 10
the iO ₂ interlayer insulation film 12, a contact hole 14 (Figure 1 (a)). Next, sputtering is performed according to the sputtering sequence shown in FIG. In this sputter sequence, the 300 Å Ti film 16 is formed as shown in FIG.
The film is formed during the sputtering time indicated by. In this (I), the total gas pressure Pr is 4 mTorr, the argon gas flow rate F _Ar is 75 sccm, and the nitrogen flow rate F _N2 is Osccm.
Sputtering is performed for 30 seconds with a DC power P of 1 Kwatt and a sputter rate R of 10Å / sec. After 30 seconds have passed, the contact hole 14 and the SiO ₂ interlayer insulating film 12 have Ti as shown in FIG.
The film 16 is formed.

Next, the TiN film is formed during the sputtering time (II) of the sputtering sequence shown in FIG. Here, the introduction of nitrogen gas is started and F _N2 is 5
It is set to 8 sccm. Further, the flow rate of the argon gas is reduced and F _Ar is set to 35 _sccm . As a result, the total gas pressure Pr gradually changed to 4.0 mTo in about 10 seconds.
It becomes stable from rr to 4.5 mTorr. Simultaneously with the introduction of nitrogen gas, the DC power P is switched to 6.5 Kwatt. In this approximately 10 seconds, the Ti-rich TiN film 18
Is formed about 200Å. Next, the stoichiometric composition of T
After the iN film has passed 10 seconds in the sputtering time of (II),
The formation starts when the nitrogen partial pressure becomes stable. The sputter rate R is 20Å / sec, and the thickness is 70 in 35 seconds.
A TiN film 20 of 0 Å is formed (FIG. 1C).

Next, in the sputtering time (III) of the sputtering sequence shown in FIG. 2, the introduction of nitrogen gas is stopped and the sputtering is switched to argon gas only. Here, the sputtering time is 15 seconds. During this period, the nitrogen partial pressure reaches 0 in about 5 to 10 seconds, and TiN 32 (see FIG. 3) on the surface of the Ti target 30 is sputtered by the argon gas, and pure Ti is exposed on the outermost surface. At the same time as this exposure, a Ti-rich TiN film is formed first, and then the lower layer is Ti-rich TiN film.
The Ti film 22 is formed as an upper layer of the film. As a result, S
The surface of the i-substrate 10 has the structure shown in FIG. After that, the Si substrate 10 is unloaded from the sputtering chamber, and a new sputtering process of the Si substrate is subsequently performed according to the sputtering sequence of FIG. After the Si substrate 10 is unloaded from the sputtering chamber, 650
A heat treatment is performed at a temperature of .degree. C., whereby the Ti film 16 (see FIG. 1) reacts with Si to form a TiSi film (not shown) and a metal / semiconductor contact is formed (not shown).

In this embodiment, Ti for contact formation is used.
The formation of the TiN film as the film and the barrier layer is completed in only 90 seconds in total. Further, both a Ti film and a TiN film can be formed in a single sputtering chamber targeting Ti. This enables mass production with high throughput. Further, since the number of chambers is small, the cost of the equipment / equipment can be reduced.

[0015]

As described above, according to the method of manufacturing a semiconductor device of the present invention, the metal film and the metal nitride film are formed by simply switching the atmospheric gas while maintaining the plasma state in one chamber. In addition, since film formation on a new Si substrate can be continuously performed using the same chamber, it is possible to suppress an increase in capital investment and manufacturing cost and improve throughput.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a method for manufacturing a semiconductor device of the present invention.

FIG. 2 is a graph showing a sequence of a sputtering process of the present invention.

FIG. 3 is a perspective view showing a target having TiN formed on its surface.

[Explanation of symbols]

10 Si substrate 12 SiO ₂ interlayer insulating film 14 Contact hole 16 Ti film 18 Ti-rich TiN film 20 TiN film 22 Lower layer is Ti-rich TiN film, upper layer is Ti film 30 Target

Claims (2)

[Claims] 1. An argon gas is introduced into a sputtering chamber to create an argon gas atmosphere, plasma is generated in the argon gas atmosphere, and a target for forming a metal film is sputtered to form the metal film on the substrate. And a step of forming a metal film, and then maintaining the plasma in the sputtering chamber, introducing nitrogen gas into the argon gas atmosphere to mix the argon gas atmosphere with argon gas and nitrogen gas. Forming a metal nitride film on the metal film by sputtering the target in a gas atmosphere and in the mixed gas atmosphere; and after forming the metal nitride film, plasma in the sputtering chamber is changed. While maintaining, the introduction of the nitrogen gas was stopped and the mixed gas atmosphere was changed to an argon gas atmosphere. Forming a metal film on the metal nitride film by sputtering a target; and, after the completion of the process, removing the substrate from the sputtering chamber and loading a new substrate into the sputtering chamber. A method for manufacturing a semiconductor device, characterized in that: 2. The method for manufacturing a semiconductor device according to claim 1, wherein the metal film is a Ti film, and the metal nitride film is a TiN film.