JP3321960B2 - Metal plug formation method - Google Patents

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 metal plug, and more particularly, to a method for selectively embedding a metal material in a contact hole on a semiconductor substrate by physical vapor deposition. The present invention can be used in the field of manufacturing various semiconductor devices.

[0002]

2. Description of the Related Art Conventionally, to form a metal plug in a contact hole, a metal film is deposited on the entire surface by a sputtering method, and the metal film outside the contact hole is removed. In addition to such a sputtering method, a physical vapor deposition method of a metal film includes an ICB (Ionized Cluster).
Beam) method and MBE (Molecular Beam)
m Epitaxy) method and the like are known. The ICB method is a method in which an aggregate of metal atoms is ionized and irradiated on a substrate to deposit a metal film. The MBE method is a method of irradiating a metal molecular beam onto a substrate to deposit a metal film. The ICB method and the MBE method are known as methods for depositing an Al film, a Ti-based film, and the like on silicon with good orientation.

[0003]

However, the sputtering method has a problem in that the orientation of the buried metal material is not uniform, and the contact hole having a high aspect ratio cannot be satisfactorily buried, thus lowering the reliability. Was. FIG. 5 shows a state in which an aluminum film 3 is deposited on a contact hole 2A formed in an interlayer insulating film 2 on a silicon substrate 1 by a sputtering method. In such a sputtering method, as shown in the figure, although aluminum 3A adheres to the bottom of contact hole 2A, void 4 is formed in contact hole 2A because aluminum film 3 overhangs at the shoulder of contact hole 2A. As a result, there is a problem that the embedding is defective and the reliability as wiring is remarkably reduced.

Even if a metal film is densely filled in a contact hole by using the ICB method, the MBE method or the sputtering method, the metal film is deposited also on SiO ₂ which is an interlayer insulating film. Is required, and the amount of the etch back increases as shown by the broken line in FIG. Furthermore, as the aspect ratio of the contact hole increases, these conventional methods can
There is a problem that good embedding becomes impossible.

The problem to be solved by the present invention is that an IC
What means should be taken to obtain a method of forming a metal plug in which a metal can be selectively buried in a wiring opening by physical vapor deposition such as the B method or the MBE method.

[0006]

[ MEANS FOR SOLVING THE PROBLEMS] The structure of the invention according to claim 1 is as follows.
The connection is made by opening a connection hole in the interlayer insulating film formed on the surface of the base.
Opening a part, heating the surface of the substrate, and
While cooling the surface, physically deposit a metallic material on the substrate.
Then, a metal material is selectively embedded in the connection opening.
In the method of forming a tall plug, the heating is performed by a heat ray irradiation method.
The heat rays emitted from the heat ray irradiating means are performed in stages.
So that it does not enter the bottom of the connection opening
And is irradiated obliquely.

According to a second aspect of the present invention, there is provided the above-mentioned metal material.
The material is aluminum, titanium or titanium nitride
It is characterized by the following.

According to a third aspect of the present invention, the heating is performed by
Set so that the surface of the interlayer insulating film is close to 400 ° C.
The cooling is performed when the temperature of the connection opening becomes approximately 200 ° C. or less.
It is characterized by setting so that.

[0009]

According to the present invention, the surface side of the substrate is heated.
At the same time, cooling the back side for connectionAperture
(Contact holes, through holes, via holes, etc.)
Function of preferentially depositing metallic material at the bottom
Having.And means for heating the surface of the interlayer insulating film;
Using a heat irradiation means such as lamp heating
Irradiates heat rays from the bottom of the connection opening.
Heating only the surface of the interlayer insulating film without heating
To play. This, For connectionApertureBetween the layers with
Since heating is performed on the upper surface of the insulating film, the metal material is recycled.
Evaporates and does not adhere to the surface of the interlayer insulating film
You. Therefore, for connectionApertureMetal material is selectively embedded in
Can be embedded. This physical vapor deposition is performed by the ICB method.
If done, connect a metal plug with better crystallinityOpening
DepartmentIt is possible to grow from the bottom.

[0010] Further, the temperature of the substrate surface is set to approximately 400 ° C.
And set the temperature to about 200 ° C on the back side of the substrate.
With, for example, aluminum at the bottom of the connection opening
It can be crystallized reliably, and on the surface of the interlayer insulating film
Aluminum is re-evaporated and aluminum film does not adhere
It has the effect of reducing

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of a method for forming a metal plug according to the present invention will be described below with reference to embodiments shown in the drawings.

FIG. 1 shows that an interlayer insulating film 12 made of SiO ₂ is formed on a silicon substrate 11, and a contact hole 13 is opened in the interlayer insulating film 12, which is mounted on an ICB film forming apparatus to which the present method is applied. This shows a state in which an aluminum film is formed.

As shown in FIG. 1, the ICB film forming apparatus includes a substrate holder 14 on which a film-forming object is placed, and a material source for irradiating ionized aluminum atom blocks toward the substrate holder 14 side. It is roughly composed of a part 16 and a heat lamp 17 for heating. On the lower surface of the substrate holder 14, a cooling pipe 15 is uniformly disposed. A cooling medium is circulated through the cooling pipe 15, and the temperature of the back surface of the silicon substrate 11 is set to about 200 ° C. when an aluminum film is formed by the ICB film forming apparatus.

The heat lamp 17 is mounted on the substrate holder 1.
The surface of the silicon substrate 11 (the surface of the interlayer insulating film 12), which is a deposition target substrate mounted on the substrate 4, is arranged so as to irradiate heat rays from an oblique direction. The angle in the oblique direction is determined by contact hole 1 opened in interlayer insulating film 12.
According to the aspect ratio of 3, the angle is set such that the bottom of the contact hole is not irradiated with heat rays. In this embodiment, the temperature of the surface of the interlayer insulating film 12 is set to about 400 ° C. when the aluminum film is formed. In addition,
In this embodiment, since the configuration is such that the heat rays are irradiated obliquely, the substrate is rotated so that the heating becomes uniform.

Further, the material source section 16 is provided with various functional sections for heating and melting the aluminum to ionize the atomic mass and draw it out to the substrate holder 14 side.

When the aluminum film 18 is formed by such an ICB film forming apparatus, the aluminum film 18 is preferentially crystallized at the bottom of the contact hole 13 as shown in FIG. This is because the back side of the silicon substrate 11 is about 2
Since the temperature is cooled to 00 ° C., the bottom of the contact hole 13 is also cooled by heat conduction in the silicon substrate 11. For this reason, the ionized aluminum atomic mass from the material source portion 16 is cooled at the bottom of the contact hole 13, changes from a molten state to a crystallized state, and starts film formation. At this time, the surface of the interlayer insulating film 12 has a thickness of about 400
Because it is heated to ℃, the aluminum evaporates without adhering. Therefore, the aluminum film 18 is selectively grown only in the contact hole 13.

FIG. 3 shows a silicon substrate 11 in this embodiment.
5 is a graph showing a temperature distribution from the back surface to the surface of the interlayer insulating film 12. According to this graph, the temperature at the bottom of the contact hole 13 is about 200 ° C.
It can be seen that the surface temperature was about 400 ° C. This is because the thermal conductivity between the crystalline Si and SiO ₂ is relatively large, so that the temperature in the contact hole 13 can be kept low. FIG. 4 shows changes in the adhesion coefficient and the diffusion distance of aluminum when an aluminum film is deposited by the above-mentioned ICB method while changing the temperature of the substrate in various ways. From this graph, it can be seen that the adhesion coefficient and the diffusion distance increase around 200 ° C., and the adhesion of aluminum is more likely to occur. In particular, an increase in the diffusion distance means that aluminum atoms are easily diffused and grow as crystals, so that a favorable single crystal structure can be obtained. At around 400 ° C., the adhesion coefficient and the diffusion distance are small, and it can be seen that reevaporation is likely to occur.

FIG. 2 shows an aluminum film 18 which is a metal plug formed according to this embodiment. The aluminum film 18 is selectively formed on the interlayer insulating film 12 only by performing the ICB method. A metal plug can be formed.

Although the present embodiment has been described above, the present invention is not limited to this, and the back surface temperature of the substrate is set substantially lower than the surface temperature to reduce the adhesion coefficient of the substrate surface. If so, various changes are possible.

For example, in the above embodiment, the ICB method is used as the physical vapor deposition, but a selective metal plug can be formed similarly by applying the MBE method or the sputtering method.

In the above embodiment, the metal material is
Aluminum was deposited, but titanium (T
i), the present invention can be applied to vapor deposition of titanium nitride (TiN) and the like.

Further, in the above-described embodiment, the heat lamp 17 is used as the heating means and the heat rays are set to be emitted obliquely. However, if a temperature difference can be set at least on the front and back surfaces of the substrate, such a heating method can be used. It does not have to be a means.

[0023]

As is apparent from the above description, according to the present invention , the connection to the interlayer insulating film formed on the surface of the substrate is achieved.
Opening an opening for heating, heating the surface of the base,
While cooling the back of the body, physically place the metallic material on the substrate
Vapor deposition to selectively fill metal material in the connection opening
In the method of forming a metal plug to be inserted,
Heat rays emitted by the irradiation means and emitted from the heat ray irradiation means
Is the base so that it does not enter the bottom of the connection opening.
Is obliquely applied to the substrate, and therefore, it is possible to easily form a metal plug selectively in the connection opening without increasing the number of steps. In addition, there is an effect that a good embedding can be performed even in a connection opening having a high aspect ratio without overhang by a metal material film.
Therefore, there is an effect that a highly reliable contact can be formed.

[Brief description of the drawings]

FIG. 1 is an explanatory sectional view showing an embodiment of the present invention.

FIG. 2 is an explanatory sectional view showing an embodiment of the present invention.

FIG. 3 is a graph showing a temperature distribution from the back surface of the substrate to the surface of the interlayer insulating film.

FIG. 4 is a graph showing a relationship between a substrate temperature, an adhesion coefficient, and a diffusion distance.

FIG. 5 is a sectional view showing a conventional problem.

FIG. 6 is a sectional view of a conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 ... Silicon substrate 12 ... Interlayer insulating film 13 ... Contact hole 14 ... Substrate holder 15 ... Cooling pipe 16 ... Material source 17 ... Heat lamp 18 ... Aluminum film

Claims (3)

(57) [Claims] An opening for connection is opened in an interlayer insulating film formed on a surface of a substrate, and the surface of the substrate is heated.
While cooling the rear surface of the substrate, by physical vapor deposition of metal material on said substrate, method of forming a metal plug that writing selectively implanting <br/> Me a metallic material to said connection opening, the heating The heating is performed by the heat ray irradiating means.
The irradiated heat ray does not enter the bottom of the connection opening.
A method for forming a metal plug , wherein the substrate is irradiated obliquely as described above . 2. The metal material is aluminum or titanium.
2. The method according to claim 1, wherein the metal plug is titanium nitride . 3. The heating is performed when the surface of the interlayer insulating film is 400.
° C, and the cooling is performed using the connection opening
2. The method for forming a metal plug according to claim 1, wherein the temperature of the portion is set to approximately 200 [deg.] C. or less.