JPH06248433A - Thin film forming device - Google Patents

Abstract

PURPOSE:To form a thin film having high reliability without damaging a substrate by impressing a negative potential to a drawing out electrode installed between an ionizing means and the substrate so that ion clusters and ionizing reactive gases can be drawn out in a substrate direction. CONSTITUTION:A crucible 15 placed in a vacuum chamber 11 into which the reactive gases are introduced is heated by thermions. A material 16 for vapor deposition in the crucible 15 is heated and the clusters 19 are ejected from a nozzle 17. These clusters 19 and the reactive gases come into collision against the electrons from an ionizing filament 20 in an ionizing section 22 and turn to the ionizing clusters 23 and the ionizing reactive gases. These reactive gases and clusters 23 are drawn out by the drawing out electrode 30 impressed with the negative potential. The substrate 14 is irradiated with the clusters 23 together with the clusters 19 drawn out by these clusters, by which the thin film is formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thin film forming apparatus for forming a high quality thin film by vapor deposition.

[0002]

2. Description of the Related Art FIG. 7 is a diagram showing a structure of a conventional thin film forming apparatus by a sputtering method shown in "Latest functional film forming process technology" (published by Koushinsha in 1987). In the figure, 1 is a vacuum tank, 2 is an exhaust port provided for making the inside of the vacuum tank 1 a vacuum, 3 is a discharge gas in the vacuum tank 1,
For example, a gas inlet 4 provided to introduce an argon gas, 4 is a film-forming material provided in the vacuum chamber 1, for example, a target made of titanium, and 5 is a substrate provided so as to face the target 4. 6 is a target 4 and a substrate 5
A power supply provided to apply a DC voltage between the
Is an argon ion generated between the target 4 and the substrate 5, and 8 is an atom of the target 4.

Next, the operation of the conventional thin film forming apparatus by the sputtering method configured as described above will be described. First, the vacuum chamber 1 is evacuated from the exhaust port 2 to
^The degree of vacuum is set to about ⁻² Torr, and, for example, argon gas is introduced into the vacuum chamber 1 through the gas introduction port 3. Then, a DC voltage is applied between the target 4 and the substrate 5 by the power supply 6. Then, the argon ions 7 collide with the target 4 and the atoms 8 of the target 4 are knocked out, and these atoms adhere to the substrate 5 to form a thin film.

At this time, the mean free path of this atom 8 is 1c.
Since it is about m, the atoms 8 will collide several tens of times before reaching the substrate 5, and the directionality of the atoms 8 is almost lost. In the thin film forming apparatus using the conventional sputtering method, the film is formed in a state in which the directivity of the atoms 8 is almost lost, and when applied to a fine hole having an aspect ratio of more than 2, as shown in FIG. In addition, the film 10 on the upper part of the micropore 9 overhangs, and the film cannot be formed sufficiently inside the micropore 9, and the film 10 becomes discontinuous between the upper part and the bottom part of the micropore 9, as shown in FIG. 8B. A continuous film cannot be formed and electrical continuity occurs.

Therefore, in order to improve this, a thin film forming apparatus by a cluster ion beam vapor deposition method (hereinafter referred to as ICB method) has been developed. FIG. 9 shows, for example, Japanese Patent Laid-Open No. 61-23.
It is a sectional view showing composition of a thin film forming device by the ICB method shown in 8957. In the figure, 11 is a vacuum tank, 1
Reference numeral 2 is an exhaust port provided for making the inside of the vacuum chamber 1 a vacuum, 13 is a gas inlet provided for introducing a reactive gas such as nitrogen gas into the vacuum chamber 1, and 14 is a crucible described later. The substrate 15 is provided so as to face the substrate, and 15 is a crucible for containing a vapor deposition material 16, for example, titanium, and a nozzle 17 is provided on the upper part.

Reference numeral 18 is a heating filament for heating the crucible 15, and 19 is a vapor deposition material 16 from the nozzle 17 of the crucible 15.
Clusters formed by ejecting electrons, 20 is an ionization filament that emits electrons, 21 is a grit-shaped electron extraction electrode that extracts and accelerates the electrons from this ionization filament 20 to an ionization section, which will be described later, and 22 is ejected from the ionization filament 20. , An ionization part composed of electrons extracted by the electron extraction electrode 21, 23 an ionization cluster ionized by the ionization part 16, and 24 an acceleration electrode for accelerating the ionization cluster 17 toward the substrate 5.

Reference numeral 25 is a first AC power source for supplying a current to the heating filament 18 to raise it to a high temperature to emit thermoelectrons, and 26 heats the potential of the crucible 15 so that the electrons emitted by the heating filament 18 collide with the crucible 15. A first DC power supply that applies a bias potential that keeps the potential higher than the potential of the filament 18, a second AC power supply 27 that heats the ionization filament 20, and a reference numeral 28 that the potential of the ionization filament 20 is higher than the potential of the electron extraction electrode 21. The second DC power supply 29 keeps it low, and the third DC power supply 29 keeps the potential of the acceleration electrode 24 lower than the potential of the electron extraction electrode 21.

Next, the operation of the thin film forming apparatus according to the ICB method constructed as described above will be described. First, the inside of the vacuum chamber 11 is evacuated through the exhaust port 12 and the reactive gas is introduced into the vacuum chamber 11 through the gas introduction port 13 until the degree of vacuum is about 10 ⁻⁶ Torr. And the heating filament 18
Is heated by the first AC power source 25 to emit thermoelectrons, and the emitted thermoelectrons collide with the crucible 15 by the positive voltage applied to the crucible 15 by the first DC power source 26 to heat the crucible 15. .

Then, the vapor deposition material 16 in the crucible 15 is heated through the crucible 15, and the vapor pressure inside is 1 Tor.
When it reaches about r, the ejection cluster 19 is formed from the nozzle 17. The clusters 19 and the reactive gas collide with the electrons from the ionization filament 20 in the ionization section 22 to become the ionization clusters 23 and the ionization reactive gas. In this manner, the ionization cluster 23 and the ionized reactive gas are accelerated by the electric field generated at the acceleration electrode 24, and the substrate 14 is irradiated with the cluster 19 accelerated by the ionization cluster 23 to form a thin film.

At this time, the potential of the accelerating electrode 24 is set to a value lower than that of the electron extracting electrode 21, the ionization cluster 23 is accelerated to irradiate the substrate 14, and a sufficient amount of the ionization cluster 23 is applied to the substrate 14. To reach
A potential of 5 KV, for example, is applied to the electron extraction electrode 21 by the third DC power supply 29.

[0011]

Since the conventional thin film forming apparatus using the ICB method is configured as described above, the energy when the ionization cluster 23 is applied to the substrate 14 is the electron extraction electrode of the ionization section 22. A large difference of 5 KV, which is a potential difference between the 5 KV potential applied by 21 and the ground potential of the substrate 14, becomes acceleration energy. The ionized part cluster, 23 is irradiated onto the substrate 14 by this energy, so that the substrate 14 is damaged.
On the contrary, if the energy is reduced, the substrate 14 is not damaged, but the acceleration of the ionization clusters 23 is reduced and the required amount of the ionization clusters 23 does not reach the substrate 14, so that a desired thin film is not formed. There was a problem that it could not be formed.

The present invention has been made to solve the above problems, and an object thereof is to provide a thin film forming apparatus capable of forming a highly reliable thin film without damaging the substrate.

[0013]

[Means for Solving the Problems] Claim 1 according to the present invention
In the thin film forming apparatus, the extraction electrode for drawing out the ionized cluster and the ionized reactive gas is provided between the ionization means and the substrate in the direction of the substrate, and a negative potential is applied to this electrode.

According to a second aspect of the present invention, there is provided a thin film forming apparatus, wherein the distance between the substrate and the extraction electrode is not less than a predetermined value, the distance is set between the substrate and the extraction electrode and in the vicinity of the substrate, and the potential of the extraction electrode is set. It is provided with a transport electrode to which a potential having the same value as is applied.

Further, in the thin film forming apparatus according to the third aspect of the present invention, when the vacuum degree in the container is P (Torr) and the distance from the crucible nozzle to the substrate is L (cm), P and L The value is set so as to satisfy 1/1000 ≦ L × P ≦ 5/100.

In the thin film forming apparatus according to the fourth aspect of the present invention, the vapor deposition material and the reactive gas are titanium and nitrogen, and the number of nitrogen ions per titanium atom is 2 or more and 10 or less. is there.

[0017]

In the thin film forming apparatus according to the first aspect of the present invention, the extraction electrode to which a negative potential is applied extracts the ionized cluster and the ionized reactive gas toward the substrate.

Further, the transport electrode to which the same potential as the potential of the extraction electrode of the thin film forming apparatus according to claim 2 of the present invention is applied transports the ionized clusters extracted by the extraction electrode toward the substrate.

Further, the degree of vacuum P (Torr) in the container of the thin film forming apparatus and the distance L (cm) from the crucible nozzle to the substrate are 1 / 1000≤L in the third aspect of the present invention.
It is set to satisfy × P ≦ 5/100.

The number of nitrogen ions per titanium atom of the thin film forming apparatus according to claim 4 of the present invention is 2
It is supplied so that the number is not less than 10 and not more than 10.

[0021]

【Example】

Example 1. Embodiments of the present invention will be described below with reference to the drawings. 1 is a cross-sectional view showing the structure of a thin film forming apparatus by the ICB method according to a first embodiment of the present invention. In the figure, the same parts as those of the conventional device are designated by the same reference numerals and the description thereof will be omitted. Reference numeral 30 is an extraction electrode for extracting the ionized cluster 23 formed in the ionization section 22 toward the substrate 14,
Reference numeral 31 is a fourth DC power supply for applying a potential of −9 KV to the extraction electrode 30, and 32 is a fifth DC power supply for applying a potential of 1 KV to the electron extraction electrode 21, for example.

Next, I of the first embodiment constructed as described above.
The operation of the thin film forming apparatus using the CB method will be described. First, as in the conventional case, the inside of the vacuum chamber 11 is evacuated from the exhaust port 12 until the vacuum degree becomes 10 ⁻⁶ Torr, and the gas introduction port 13
More reactive gas is introduced into the vacuum chamber 11. The heating filament 18 is heated by the first AC power supply 25 to emit thermoelectrons, and the emitted thermoelectrons are collided with the crucible 15 by the positive voltage applied to the crucible 15 by the first DC power supply 26. The crucible 15 is heated.

Then, the vapor deposition material 16 in the crucible 15 is heated through the crucible 15, and the vapor pressure inside is 1 Tor.
When it reaches about r, the ejection cluster 19 is formed from the nozzle 17. The clusters 19 and the reactive gas collide with the electrons from the ionization filament 20 in the ionization section 22 to become the ionization clusters 23 and the ionization reactive gas. Then, the extraction electrode 30 extracts the ionized cluster 23 and the ionized reactive gas by the potential difference between the 1 KV potential of the electron extraction electrode 21 and the −9 KV potential of the extraction electrode 30, and together with the cluster 19 extracted by the ionization cluster 23. Irradiate the substrate to form a thin film.

When the ionized cluster 23 is irradiated onto the substrate 14, the energy is generally lower than 500 V, the adhesion to the substrate 14 is small, the film quality may be deteriorated, and the energy is higher than 2 KV. In some cases, the reactive gas sputters the formed thin film, which may deteriorate the film quality. Therefore, the range of 500V to 2KV is suitable. In the first embodiment, the ionization portion 22 has an electron extraction electrode 21.
As a result, a potential of 1 KV is applied, and the substrate 14 is at the ground potential. Therefore, this potential difference, that is, 1 KV becomes the energy of the ionization cluster 23, and the above-mentioned 500 V is applied.
Since it is within the range of up to 2 KV, the thin film can be formed without damaging the substrate 14.

Example 2. In the first embodiment, the extraction electrode 30
The distance from the substrate 14 to the substrate 14 was within the range in which the ionization cluster 23 reached the substrate 14 without impairing the directivity, but here, the distance from the extraction electrode 30 to the substrate 14 exceeds the above range. The case will be described. Figure 2
In 33, a transport electrode 33 is provided between the extraction electrode 30 and the substrate 14 in the vicinity of the substrate 14, and a potential of −9 KV having the same value as that of the extraction electrode 30 is applied from the fourth DC power supply 31. In the second embodiment, the transport electrode 3 is configured as described above.
Since the potential of 3 is almost the same as the potential of the extraction electrode 30, the potential between the extraction electrode 30 and the transport electrode 33 is kept constant, and the ionized cluster 23 and the ionization reactivity extracted to the extraction electrode 30 are maintained. Since the gas can be transported to the transport electrode 33 while being kept in the same state, the ionization cluster 23 and the ionization reactive gas do not impair the directivity and reach the substrate 14 to form a thin film.
Has the same effect as.

Example 3. Recently, there has been a demand for film formation of fine holes having a high aspect ratio (for example, 2 to 4). FIG. 4 shows the relationship between the bottom coverage ratio and the distance from the nozzle to the substrate / the mean free path of the vapor deposition particles when fine holes with an aspect ratio of 4 are formed using the thin film forming apparatus shown in FIG. It is a figure. In the figure, the bottom coverage ratio is the ratio of the film thickness of the bottom of the micropores to the film thickness of the flat surface of the substrate, and is said to be 10% or more in order to improve the electrical reliability.

Therefore, the mean free path of the vapor deposition particles is λ (c
m), when the degree of vacuum in the vacuum chamber 11 is P (Torr), generally P × λ = 5/100 is satisfied. From this, the distance from the nozzle 17 to the substrate 14 is L (cm)
In the case of, in order to secure a bottom coverage rate of 10% or more, 1/1000 ≦ L × P from the relationship shown on the horizontal axis of the figure.
It can be seen that the condition ≦ 5/100 must be satisfied. For example, according to the conventional ICB method, TiN
According to the case of forming a thin film, the concentration of the reaction gas is reduced to suppress the scattering of titanium atoms in the vacuum chamber 11, and the thin film is maintained in a high vacuum state of, for example, 10 ⁻⁶ Torr.
Ti ₂ N that lacked nitrogen atoms due to reduced amount of ions
A film is formed.

In the third embodiment, if L is set to, for example, 50 cm and it is applied to the above 1/1000 ≦ L × P ≦ 5/100, P
May be in the range of 2 × 10 ⁻⁵ Torr to 10 ⁻³ Torr,
It can be carried out at a vacuum lower than 10 ⁻⁶ Torr in the case of each of the above-mentioned embodiments, and the amount of the reaction gas is sufficient for this amount, so that the TiN film filled with nitrogen atoms can be formed. still,
The thin film formed under the above conditions is better than the thin film formed by the conventional ICB method, and as shown in FIG. 4A, the thin film formed by the conventional sputtering method. It is also clear from comparison with FIG. 4B showing the above case, the film was formed with a bottom coverage ratio of about 50%, and a thin film with high electrical reliability could be obtained.

Example 4. Although the thin film forming apparatus of each of the above embodiments has shown the case of forming titanium nitride, the case of using titanium nitride as the underlying film of the wiring in the thin film forming apparatus of each of the above embodiments will be described in the fourth embodiment. First, when titanium nitride is used as a base film and an aluminum alloy is to be formed thereon, as shown in FIG. 5, both aluminum alloy (111) and titanium nitride (111) are triangular lattices, and one side of The lengths are almost doubled. Therefore, in order to secure the strength by aligning with the crystal orientation (111) of the aluminum alloy, if the crystal orientation of titanium nitride is aligned with the crystal orientation (111) of the aluminum alloy, the aluminum alloy will follow this. Since the film is formed, the strength can be secured.

Therefore, the crystal orientation of titanium nitride (111)
The orientation intensity ratio of is represented by I111 / (I111 + I200) when the orientation intensities of titanium nitride (111) and (200) are set to I111 and I200, respectively. Since this orientation intensity ratio changes depending on the number of nitrogen ions per titanium atom as shown in FIG. 6, it reaches the substrate in order to satisfy the target intensity of I111 / (I111 + I200) ≧ 0.8. At least two nitrogen ions are required for each titanium atom, and the number of nitrogen ions is limited to about 10 due to practical restrictions such as the capacity and efficiency of the supply source. Therefore, if the number of nitrogen ions is 2 or more and 10 or less with respect to one titanium atom that reaches the substrate, the strength of (111) of titanium nitride as the base film can be improved, and a film is formed thereon. Since the strength of the formed aluminum alloy can be ensured, highly reliable wiring can be formed.

Example 5. In Examples 1, 2 and 3 above,
Although an example in which titanium is used as the vapor deposition material 16 and nitrogen is used as the reaction gas, the vapor deposition material 16 is not limited to these, and examples of the vapor deposition material 16 include strontium, silicon, lead,
Even if a thin film is formed by using, for example, oxygen, hydrocarbon, halogen, or the like as a reactive gas such as boron, barium, or aluminum, the same effect as that of the first, second, and third embodiments can be obtained.

[0032]

As described above, according to the first aspect of the present invention, the extraction electrode for extracting the ionized cluster and the ionized reactive gas is provided between the ionization means and the substrate in the direction of the substrate, and the negative electrode is provided in this electrode. So that the electric potential of
Further, according to claim 2, the distance between the substrate and the extraction electrode is not less than a predetermined value, the potential is provided between the substrate and the extraction electrode and in the vicinity of the substrate, and the same potential as the potential of the extraction electrode is applied. According to claim 3, when the degree of vacuum in the container is P (Torr) and the distance from the crucible nozzle to the substrate is L (cm), the values of P and L are 1 / 1000
It is set to satisfy ≦ L × P ≦ 5/100, and according to claim 4, the vapor deposition material and the reactive gas are titanium and nitrogen, and the number of nitrogen ions per titanium atom is 2 or more. Since the number is 10 or less, there is an effect that it is possible to provide a thin film forming apparatus capable of forming a highly reliable thin film without damaging the substrate.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration of a thin film forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a sectional view showing a configuration of a thin film forming apparatus according to a second embodiment of the present invention.

FIG. 3 is a diagram showing a relationship between a bottom coverage rate and a distance from a nozzle to a substrate / a mean free path of vapor deposition particles.

FIG. 4 is a diagram showing a comparison of the states of thin films formed by Example 3 of the present invention and a conventional sputtering method.

FIG. 5 is a diagram showing each (111) of an aluminum alloy and titanium nitride.

FIG. 6 is a diagram showing the relationship between the (111) orientation intensity ratio of titanium nitride and the number of nitrogen ions per titanium atom.

FIG. 7 is a cross-sectional view showing a configuration of a conventional thin film forming apparatus by a sputtering method.

8 is a diagram showing a comparison between a thin film formed by the thin film forming apparatus shown in FIG. 7 and an ideal thin film.

FIG. 9 is a cross-sectional view showing a configuration of a conventional thin film forming apparatus using an ICB method.

[Explanation of symbols]

 1, 11 Vacuum tank 5, 14 Substrate 15 Crucible 16 Deposition material 17 Nozzle 19 Cluster 22 Ionization part 23 Ionization cluster 30 Extraction electrode 31 Fourth DC power supply 32 Fifth DC power supply 33 Transport electrode

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[Procedure amendment]

[Submission date] June 17, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be corrected] Claim 1

[Correction method] Change

[Correction content]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

At this time, the mean free path of this atom 8 is 1c.
Since it is about m, the atoms 8 collide several tens of times before reaching the substrate 5, and the directionality of the atoms 8 is almost lost. In the thin film forming apparatus using the conventional sputtering method, the film is formed in a state in which the directivity of the atoms 8 is almost lost, and when applied to a fine hole having an aspect ratio of more than 2, as shown in FIG. In addition, the film 10 above the micropores 9 overhangs, and it becomes impossible to form a sufficient film inside the micropores 9, and the film 10 is formed between the top and bottom of the micropores 9.
Becomes discontinuous, and as shown in FIG. 8B, continuous film formation cannot be performed, resulting in electrical discontinuity.

Claims (4)

[Claims] 1. A container filled with a reactive gas and kept in a desired atmosphere, a crucible provided in the container, housed in a vapor deposition material, and having a nozzle at an upper portion, and the nozzle of the crucible. A substrate provided on the side opposite to the substrate, provided between the crucible and the substrate, and ionized the clusters of the vapor deposition material and the reactive gas that are heated and evaporated from the nozzle toward the substrate. And an extraction electrode provided between the ionization means and the substrate for extracting ionized clusters and ionized reactive gas generated by the ionization means toward the substrate, and a negative electrode for the extraction electrode. A thin film forming apparatus comprising: a power supply for applying a potential. 2. The distance between the substrate and the extraction electrode is not less than a predetermined value,
The thin film formation according to claim 1, further comprising a transport electrode provided between the substrate and the extraction electrode and in the vicinity of the substrate, to which a potential having the same value as the potential of the extraction electrode is applied. apparatus. 3. When the degree of vacuum inside the container is P (Torr) and the distance from the crucible nozzle to the substrate is L (cm), the values of P and L are 1/1000 ≦ L × P ≦ 5. / 1
3. The thin film forming apparatus according to claim 1, wherein the thin film forming apparatus is set so as to satisfy 00. 4. The vapor deposition material and the reaction gas are titanium and nitrogen, and the number of nitrogen ions per titanium atom is 2 or more and 10 or less, according to any one of claims 1 to 3. The thin film forming apparatus as described in.