JPH08186108A - Manufacture of semiconductor and manufacture of semiconductor device - Google Patents

Abstract

PURPOSE: To provide a method for manufacturing a semiconductor device in which a titanium nitride film can be formed in the step bottom of a semiconductor substrate with excellent coverage. CONSTITUTION: Titanium is ionized, and a negative bias is applied to a semiconductor substrate 10 to implant titanium ions substantially perpendicularly to the substrate 10. Thus, the ions are deposited on the substrate 10, and a titanium film 16 having flat and sufficient film thickness can be formed even in the bottom of a contact hole 14. Then, after the film 16 is formed on the substrate 10 in this manner, the film 16 is nitrided to form a titanium nitride film 18. As the method for nitriding, a method for introducing the substrate 10 into a furnace having nitrogen or ammonia atmosphere, and nitriding at a high temperature, or a method for implanting nitrogen ions to the substrate 10 is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device in which a titanium nitride film used as a barrier film is formed on a semiconductor substrate having a fine pattern.

[0002]

2. Description of the Related Art Conventionally, in order to form a titanium nitride (TiN) film used as a barrier film in a semiconductor device,
The sputtering method is used. That is, in this sputtering method, in a high vacuum chamber,
A semiconductor substrate and a target made of titanium are arranged to face each other. Then, when an inert gas such as argon is introduced into the chamber and a voltage is applied between the semiconductor substrate and the target, glow discharge occurs and the argon gas is ionized. The positive argon ions collide with the surface of the target and eject titanium from the target. The ejected titanium obtains sufficient energy by the argon ions and flies toward the semiconductor substrate.
Here, all the ejected titanium does not uniformly fly in the vertical direction with respect to the semiconductor substrate, but has a certain degree of random orientation. Then, by setting a nitrogen atmosphere in the vicinity of the semiconductor substrate, the blown-off titanium reacts with nitrogen and becomes titanium nitride, which is deposited on the semiconductor substrate.

[0003]

However, in the conventional method, since the sputtered titanium has a random directional property to some extent, the generated titanium nitride also has different directions when entering the semiconductor substrate. is there. Therefore, as shown in FIG. 3, the oxide film 52 is formed on the semiconductor substrate 50.
When the contact holes 54 are formed, the titanium nitride film 56 is hard to be formed at the bottom of the contact holes 54 and has a shape having an overhang with respect to the oxide film 52. As described above, the conventional method has a problem that the titanium nitride film cannot be formed at the bottom of the step of the semiconductor substrate with good coverage. Therefore, for example, when forming a tungsten film on the titanium nitride film 56, since the titanium nitride film 56 at the bottom of the contact hole 54 is thin, a barrier against tungsten hexafluoride, which is a material gas when forming the tungsten film. And the reliability of the semiconductor device is reduced.

As a method of vertically injecting sputtered titanium into a semiconductor substrate, a collimator 66 having a large number of through holes is arranged between a semiconductor substrate 62 and a target 64, as shown in FIG. There is a way to do it. However, with this method, titanium is attached to the collimator 66, and the attached titanium falls off as dust on the semiconductor substrate 62, a so-called particle problem, and among the sputtered titanium, the incident titanium vertically enters the semiconductor substrate. Since only the ones are involved in the film formation, a new problem arises that the film formation speed becomes about 1/5 slower than in the case where the sputtering method without using the collimator is applied. Therefore, it is desired to realize a method capable of forming a titanium nitride film with good coverage on the bottom of a step of a semiconductor substrate without causing such a problem.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a method of manufacturing a semiconductor device capable of forming a titanium nitride film at the bottom of a step of a semiconductor substrate with good coverage. .

[0006]

A semiconductor manufacturing apparatus according to the present invention comprises means for irradiating titanium atoms with thermoelectrons to ionize the titanium atoms to generate titanium ions.
And a pull-out means for flying the titanium ions substantially vertically to the semiconductor substrate by using a negative bias voltage, and making the titanium ions substantially vertically incident on the semiconductor substrate,
It is characterized by depositing a titanium film.

Further, in the method for manufacturing a semiconductor device according to the present invention, a step of ionizing titanium to generate titanium ions, and the titanium ions being incident on the semiconductor substrate substantially perpendicularly, a titanium film is formed on the semiconductor substrate. And a step of forming a titanium nitride film by nitriding the titanium film.

The semiconductor film is placed in a nitrogen or ammonia atmosphere, and the titanium film is nitrided by causing a thermal nitriding reaction at a high temperature.

Further, the titanium film is nitrided by implanting nitrogen ions into the semiconductor substrate.

[0010]

The semiconductor manufacturing apparatus of the present invention has the above-described structure, and a means for ionizing titanium atoms by applying thermoelectrons to the titanium atoms to generate titanium ions, and a semiconductor device for generating titanium ions by using a negative bias voltage. By providing the substrate with the extraction means for flying substantially vertically, it is possible to efficiently extract titanium ions and make them enter the semiconductor substrate substantially vertically.

According to the method of manufacturing a semiconductor device of the present invention, with the above structure, titanium ions are made to enter the semiconductor substrate substantially perpendicularly, so that titanium having a flat and sufficient film thickness is formed at the bottom of the step of the semiconductor substrate. Since the film can be formed, the step coverage can be improved. Moreover, since it is not necessary to use a collimator to make titanium enter the semiconductor substrate substantially perpendicularly as in the conventional method, a titanium film can be formed on the semiconductor substrate without lowering the titanium film formation rate. Then, by nitriding the titanium film, the titanium nitride film can be formed at the bottom of the step of the semiconductor substrate with good coverage.

The titanium film can be easily nitrided by placing the semiconductor substrate in a nitrogen or ammonia atmosphere and causing a thermal nitriding reaction at a high temperature.

Furthermore, by implanting nitrogen ions into the semiconductor substrate, the titanium film can be easily nitrided.
Further, by implanting such nitrogen ions simultaneously with the formation of the titanium film, the time required to form the titanium nitride film can be shortened.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram for explaining a method of manufacturing a semiconductor device according to an embodiment of the present invention, and FIG. 2 is a schematic configuration diagram of a titanium film forming apparatus used in the method of manufacturing the semiconductor device.

In the method of manufacturing a semiconductor device of this embodiment, a case where a titanium nitride film is formed on a semiconductor substrate will be considered. This titanium nitride film is used as a barrier film, for example. As the semiconductor substrate, one having a fine pattern formed thereon, for example, one having an oxide film 12 deposited on a semiconductor substrate 10 and forming a contact hole 14 as shown in FIG. 1A is used. .

The method of manufacturing the semiconductor device of this embodiment comprises a first step of depositing a titanium film on the semiconductor substrate 10 and a second step of nitriding the deposited titanium film.

First, the titanium film forming apparatus used in the first step will be described with reference to FIG. This titanium film forming apparatus includes a chamber (vacuum chamber) (not shown), a titanium ionizer 20, an extraction electrode 32, and a substrate holder 34 for holding a semiconductor substrate 10 on which a titanium film is formed.
And DC power supplies 36 and 38.

The titanium ionizer 20 comprises an evaporation source 22.
And a thermoelectron generating means (not shown). Evaporation source 22
Is a heating source for evaporating the evaporation material, and has a DC power supply 22a, a resistance heater 22b, and titanium 22c as the evaporation material. The titanium 22c is heated by energizing the resistance heater 22b using the DC power supply 22a. The thermoelectron generating means generates thermoelectrons, and the thermoelectrons are applied to the titanium atoms evaporated from the evaporation source 22 to ionize the titanium atoms.

The extraction electrode 32 and the substrate holder 34 are
They are arranged parallel to each other. The DC power supply 36 is connected to the titanium ionizer 20 and the extraction electrode 32, and applies a negative bias voltage to the extraction electrode 32. On the other hand, the DC power supply 38 is connected to the extraction electrode 32 and the substrate holder 34 and applies a negative bias voltage to the substrate holder 34.

Next, a method of manufacturing the semiconductor device of this embodiment will be described with reference to FIGS. First, the first step of forming a titanium film on the semiconductor substrate 10 is performed. First,
The semiconductor substrate 10 is held by the substrate holder 34 of the titanium film forming apparatus. Then, under high vacuum, the resistance heater 22b is energized to heat the titanium 22c, thereby evaporating titanium atoms. The vaporized titanium atoms are ionized by colliding with the thermoelectrons from the thermoelectron generating means,
Becomes titanium ions. Since a DC voltage is applied between the ionizer 20 and the extraction electrode 32 and between the extraction electrode 32 and the substrate holder 34, a negative electric field gradient is formed in the direction from the extraction electrode 32 to the substrate holder 34. , Titanium ions are accelerated,
As shown in (b), the light enters the semiconductor substrate 10 substantially perpendicularly and is deposited on the semiconductor substrate 10. Therefore, as shown in FIG.
The titanium film 16 having a flat and sufficient film thickness can be formed at the bottom of No. 4 and the step coverage can be improved.

Next, after the titanium film 16 is formed on the semiconductor substrate 10 in this way, a second step of nitriding the titanium film 16 is performed. This nitriding is performed by a method that is usually used. That is, by placing the semiconductor substrate 10 in a furnace having a nitrogen or ammonia atmosphere and causing a reaction of thermal nitriding at a high temperature to form a titanium nitride film, or by implanting nitrogen ions into the semiconductor substrate 10. A method of forming a titanium nitride film or the like can be used. Whichever method is applied, since the titanium film 16 is formed in advance with good coverage on the bottom of the step of the semiconductor substrate 10, finally, as shown in FIG. 1D, titanium nitride with good coverage is obtained. A film 18 is obtained. When the method of implanting nitrogen ions into the semiconductor substrate is used as the method of nitriding the titanium film, the second step can be performed simultaneously with the first step. As a result, the time required to form the titanium nitride film can be shortened.

In the method for manufacturing a semiconductor device of this embodiment, a negative bias voltage is applied to the semiconductor substrate to cause titanium ions to enter the semiconductor substrate substantially vertically, so that the bottom of the fine step of the semiconductor substrate is sufficiently flat. Since the titanium film having various thicknesses can be formed, the step coverage can be improved. Therefore, by subsequently nitriding the titanium film, the titanium nitride film can be formed with good coverage at the bottom of the step. Therefore, for example, when a tungsten film is formed on the titanium nitride film, the barrier property of the titanium nitride film against tungsten hexafluoride, which is the material gas for forming the tungsten film, is sufficiently exerted, and the tungsten film is not easily formed. Corrosion of tungsten hexafluoride can be prevented.

Further, in the conventional method, it was necessary to use a collimator in order to make titanium enter the semiconductor substrate substantially perpendicularly. However, in this embodiment, it is not necessary to use a collimator, so that there is a problem of particles. And the film formation rate of the titanium film does not decrease.

The present invention is not limited to the above embodiment, but various modifications can be made within the scope of the invention. For example, in the above embodiment, the case where resistance heating was used was described as the method for heating titanium as the evaporation material, but electron beam heating for irradiating titanium with an electron beam or heating induced by titanium itself. Induction heating using a high frequency induction current may be used.

[0025]

As described above, according to the semiconductor manufacturing apparatus of the present invention, a means for generating titanium ions by ionizing titanium atoms by applying thermal electrons to the titanium atoms and a negative bias voltage are used. It is possible to provide a semiconductor manufacturing apparatus capable of efficiently extracting titanium ions and making them enter the semiconductor substrate substantially vertically by providing the extracting means for causing the titanium ions to fly substantially vertically to the semiconductor substrate.

Further, according to the method for manufacturing a semiconductor device of the present invention, titanium ions are made to enter the semiconductor substrate substantially perpendicularly to form a titanium film having a flat and sufficient thickness at the bottom of the step of the semiconductor substrate. Since it is possible to improve the step coverage, a method of manufacturing a semiconductor device in which a titanium nitride film can be formed on the bottom of a step of a semiconductor substrate with good coverage by nitriding the titanium film after that is provided. Can be provided.

Further, it is possible to provide a method of manufacturing a semiconductor device in which a titanium film can be easily nitrided by placing a semiconductor substrate in a nitrogen or ammonia atmosphere and causing a thermal nitriding reaction at a high temperature. .

Furthermore, by implanting nitrogen ions into the semiconductor substrate, it is possible to provide a method for manufacturing a semiconductor device in which the titanium film can be easily nitrided.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a method for manufacturing a semiconductor device that is an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a titanium film forming apparatus used in the method for manufacturing the semiconductor device.

FIG. 3 is a diagram for explaining the shape of titanium nitride formed on a semiconductor substrate using a conventional sputtering device.

FIG. 4 is a schematic configuration diagram of a conventional sputtering apparatus using a collimator.

[Explanation of symbols]

 10 semiconductor substrate 12 oxide film 14 contact hole 16 titanium film 18 titanium nitride film 20 titanium ionizer 22 evaporation source 22a direct current power supply 22b resistance heater 22c titanium 32 extraction electrode 34 substrate holder 36, 38 direct current power supply

Claims (4)

[Claims] 1. A means for ionizing titanium atoms to generate titanium ions by applying thermoelectrons to the titanium atoms, and a drawing means for causing the titanium ions to fly substantially perpendicularly to a semiconductor substrate by using a negative bias voltage. And a step of depositing a titanium film by causing the titanium ions to enter the semiconductor substrate substantially vertically. 2. A step of ionizing titanium to generate titanium ions, a step of depositing a titanium film on the semiconductor substrate by causing the titanium ions to enter the semiconductor substrate substantially perpendicularly, and a step of nitriding the titanium film. And a step of forming a titanium nitride film. 3. The semiconductor device according to claim 2, wherein the titanium film is nitrided by placing the semiconductor substrate in a nitrogen or ammonia atmosphere and causing a thermal nitriding reaction at a high temperature. Method. 4. The method of manufacturing a semiconductor device according to claim 2, wherein the titanium film is nitrided by implanting nitrogen ions into the semiconductor substrate.