JPH05175157A - Method for forming titanium compound film - Google Patents

Abstract

PURPOSE:To provide a method for forming titanium compound films by which a titanium thin film having a constant resistivity even from the point of time at which the formed number of films is small can be formed. CONSTITUTION:A sputtering device 1 for executing the title method is equipped with adhesion preventing plates 30 and adhesion preventing plate heating means 32 for heating the plates 30. Then reactive sputtering of a titanium compound is performed while the adhesion preventing plates 30 are heated to a fixed temperature.

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 titanium compound film by a sputtering apparatus equipped with a deposition preventive plate.

[0002]

2. Description of the Related Art With the high integration of LSI, the electrode wiring tends to be miniaturized. Aluminum (Al) is usually used as an electrode wiring material, but when aluminum and a silicon substrate are directly contacted with each other, Al and S
The following problems arise due to the mutual diffusion of i. That is, there is a problem that a short circuit occurs due to Al entering or penetrating into the diffusion layer portion, or Si epitaxially grows at the contact portion to close the contact hole portion and increase resistance, resulting in junction breakdown.

In order to deal with these problems, a method of suppressing mutual diffusion by adding Si in advance to Al in a proportion above the solid solution limit, for example, 1 to 2%, or for suppressing mutual diffusion. A method of forming a diffusion prevention layer (barrier metal) made of TiN, TiW or the like on the surface of a silicon substrate is generally adopted.

TiN is TiN in Ar or N ₂ gas.
It can be formed by reactive sputtering a target. Then, a barrier effect is obtained with a film thickness of about 30 to 50 nm. Since TiW uses a sintered body target, there is a concern that particles may be generated, and the barrier effect cannot be obtained unless the film thickness is increased to about 200 nm. Therefore, TiN has a great advantage as compared with TiW, and is becoming the mainstream as a barrier metal.

[0005]

[Problems to be Solved by the Invention] However, TiN
Has the following problems. That is, the first problem is that a sufficient diffusion preventing effect cannot be obtained unless oxygen is added to the TiN film. Regarding this, the present inventors announced at the integrated circuit symposium in the spring of 1990, “Al / TiO _X N _Y laminated wiring” pp. 13-1.
See 8.

The second problem is that O ₂ gas is introduced at the same time as Ar and N ₂ gas and TiO ₂ is formed by reactive sputtering.
When the N film is formed, the resistance of the formed TiON is low when the number of formed films is small, and the resistance of the formed TiON increases as the number of formed films increases.
This phenomenon is shown in FIG. The data shown in FIG. 4 is DC
Using a magnetron sputtering device, power of 3kW,
N ₂ / O ₂ gas = 47/3 sccm, pressure 0.45 Pa,
Substrate temperature 150 ° C, deposition rate 70nm / min, TiON
It is the measurement result of the resistivity of the TiON film formed under the condition of the film thickness of 100 nm. Due to this phenomenon, a TiON film having a desired resistivity cannot be obtained with good reproducibility.

It is considered that the reason why the resistivity increases is that the sputtering gas O ₂ is gettered to the TiON film attached to the deposition preventive plate provided in the sputtering apparatus. FIG. 5 shows the standard free energy of formation of Ti-based compounds. Compared with TiN, TiO ₂ and TiO have large negative free energy of standard formation and are stable. Moreover, the absolute value of the standard free energy of formation decreases as the temperature increases. As is clear from FIG. 5, the oxide is more stable in all temperature regions. That is, Ti is oxidized if oxygen is present.

Therefore, the O ₂ gettering effect of the TiON film attached to the deposition preventive plate is large before the temperature of the deposition preventive plate rises because the number of TiON films formed is small.
It decreases as the temperature rises. Therefore, TiON
In a stage before the deposition number of films is small temperature deposition preventing plate is increased, substantially reduced the amount of O ₂ gas in the sputtering gas occurs, TiON film of O ₂ which is formed on a substrate Low resistivity due to deficiency. As the number of deposited TiON films increases, the deposition preventive plate is exposed to plasma, and the temperature of the deposition preventive plate also rises, so that the O ₂ gettering effect is reduced and the resistivity of the TiON film formed on the substrate is reduced. It gradually increases. Then, when the temperature of the deposition preventive plate becomes constant and the O ₂ gettering effect reaches an equilibrium state, the resistivity of the TiON film also becomes constant.

On the other hand, in order to obtain a barrier effect with the TiN film, after forming the TiN film by reactive sputtering in Ar or N ₂ gas, and before forming the aluminum wiring layer, the substrate is once taken out from the sputtering apparatus. , RT
The surface of the TiN film is oxidized by heat treatment at about 600 ° C. by the A (Rapid Thermal Annealing) method or the furnace annealing method. Then, an aluminum layer is formed using a sputtering device. Therefore, the annealing step and 1
This requires extra sputtering processes, which is disadvantageous in terms of process steps.

Therefore, an object of the present invention is to provide a method for forming a titanium-based compound capable of forming a titanium-based thin film having a constant resistivity from the time when the number of formed films is small.

[0011]

A sputtering apparatus for carrying out the method of depositing a titanium compound according to the present invention is provided with a deposition preventive plate. Further, an anti-adhesion plate heating means for heating the anti-adhesion plate is provided, and reactive sputtering of the titanium compound is performed while the anti-adhesion plate is heated to a constant temperature.

The means for heating the deposition preventive plate may be, for example, an infrared lamp heater, an electric heating material wire or panel heater, or a gas heating means.

[0013]

In the method of the present invention, since the deposition preventive plate is heated to a constant temperature, it is possible to prevent the gettering amount of O ₂ gas from varying on the TiON film attached to the deposition preventive plate. Therefore, even when the number of TiON films formed is small,
O ₂ O ₂ in the sputtering gas by the gettering effect of the gas
It is possible to prevent the decrease of the amount, and as a result, it is possible to prevent the fluctuation of the resistivity of the TiON film formed on the substrate.

The deposition-preventing plate may be heated to a temperature above the temperature at which it rises to equilibrium by sputtering before the start of sputtering. When the temperature of the deposition preventive plate rises, TiO, TiO ₂
Increase the standard free energy of formation of
By reducing the gettering amount of the ₂ gas and maintaining the temperature of the deposition preventive plate constant, it is possible to prevent the change of the gettering amount of the O ₂ gas. The temperature rise of the deposition preventive plate due to sputtering is usually about 100 to 20.
Since it is 0 ° C, the deposition preventive plate may be heated to about 200 to 500 ° C.

[0015]

The method for depositing a titanium compound according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is a schematic view of a sputtering apparatus suitable for carrying out the method of the present invention, and is a view showing a sectional view of the sputtering apparatus. The DC magnetron type sputtering apparatus 1 includes a film forming chamber 10. Then, a target 12 made of titanium is arranged in the film forming chamber 10. Further, the substrate 14 is arranged so as to face the target. On the surface of the substrate 14 opposite to the target,
Substrate heating gas heating means 16 having a gas inlet 18
And Ar introduced through the gas inlet 18
The gas is heated by the gas heating means 16 for heating the substrate,
By blowing the r gas onto the substrate 14,
Can be heated. The sputtering device 1 includes Ar,
A film forming chamber 1 is provided with a sputtering gas composed of N ₂ and O ₂ gas.
A sputter gas introduction port 20 is provided for introducing the gas to 0. Note that the cathode mechanism and the gas exhaust system are not shown in FIG.

A deposition preventive plate 30 is disposed between the target 12 and the substrate 14. In order to heat the surface of the deposition preventive plate 30 on the side opposite to the target, the deposition preventive plate heating means 32 including an infrared lamp heater is provided. In addition, as a sputtering device provided with an infrared lamp heater in the film forming chamber, for example, ILC-1051 and AMA manufactured by Nichiden Anerva Co., Ltd.
ENDURA-5500 manufactured by T company is known. However, in these devices, the infrared lamp heater is provided for the purpose of baking out the water present in the film forming chamber. It is not provided for the purpose of using it in the sputtering process, and of course, it is not provided for the purpose of heating the deposition preventive plate.

A TiON film was formed on the substrate under the following conditions by using the above sputtering apparatus. Power 6 kW Gas flow rate Ar / N ₂ / O ₂ = 30/70 / 10s
ccm (Of these, Ar20sccm for heating the substrate) Pressure 0.5Pa Substrate heating temperature Gas heating, about 150 ° C Adhesion plate heating temperature about 300 ° C Deposition rate 60nm / min

Under the above conditions, the resistivity is 4 to 5 mΩcm.
The TiON film of No. 1 could be continuously formed without fluctuation of resistivity, that is, without fluctuation of composition.

FIG. 2 shows a modification of the sputtering apparatus shown in FIG. In the sputtering device shown in FIG.
An infrared lamp heater was used as the deposition-prevention plate heating means 32 for heating 0, but in the sputtering apparatus shown in FIG.
A wire rod or a panel heater made of an electric heating material is attached to. As the electrothermal material, a commonly used Ni-Cr system or Fe-Cr-Al system can be used. These electrothermal materials can be heated up to about 1000 ° C. The deposition preventing plate 30 can be heated to 200 to 500 ° C. by using a wire material or a panel heater of an electric heating material. The components of the sputtering apparatus shown in FIG. 2 other than the deposition preventive plate heating means 32 are the same as those of the sputtering apparatus shown in FIG.

In the example of the sputtering apparatus shown in FIG. 3, the deposition-prevention plate heating means 32 for heating the deposition-prevention plate 30 includes the substrate 14
Gas heating means 1 for heating a substrate used for heating a substrate
The gas heating means 34 is the same as that of No. 6. Ar gas is usually used as the gas for heating the substrate, but it is desirable to use N ₂ gas as the gas for heating the deposition preventing plate in the gas heating means 34 for heating the deposition preventing plate 30. The N ₂ gas introduced from the gas introduction port 36 for heating the deposition preventive plate is heated by the gas heating means 34 and sprayed onto the deposition preventive plate 30.
This method is a gas heating method and has good thermal conductivity. Therefore, the effect of heating the deposition preventive plate is superior to that of the deposition preventive plate heating means 32 shown in FIG. 1 or 2.

Using the sputtering apparatus shown in FIG. 3, TiO 2
The N film was formed on the substrate under the following conditions. The components of the sputtering apparatus shown in FIG. 3 other than the deposition preventive plate heating means 32 are the same as those of the sputtering apparatus shown in FIG. Power 6 kW Gas flow rate Ar / N ₂ / O ₂ = 30/70 / 10s
ccm (including 20 sccm of Ar for heating the substrate,
Also, for heating the deposition preventive plate, N ₂ 15 sccm) pressure 0.5 Pa substrate heating temperature gas heating, about 150 ° C. deposition plate heating temperature about 400 ° C deposition rate 60 nm / min

Under the above conditions, the resistivity is 4 to 5 mΩcm.
The TiON film of No. 2 could be continuously formed without fluctuation of resistivity, that is, without fluctuation of composition.

By using a DC magnetron multi-chamber type sputtering apparatus, the above-mentioned TiON
After forming the film on the substrate, an aluminum film can be continuously formed on the film. The aluminum film can be formed under the following conditions, for example. Target Al power 9 kW Gas flow rate Ar = 40 sccm Pressure 0.4 Pa Substrate heating temperature 500 ° C. Deposition rate 1 μm / min

[0025]

According to the titanium compound film forming method of the present invention, the deposition preventive plate is heated to a constant temperature from the start of film formation to the end of film formation, whereby sputtering due to temperature change of the deposition preventive plate is performed. It is possible to prevent the fluctuation of the gettering amount of O ₂ gas in the gas. Therefore, since a constant amount of O ₂ gas always contributes to the formation of the TiON film on the substrate, the resistivity of the TiON film can be made constant from the start to the end of the film formation. Therefore, variations in characteristics of manufactured semiconductor devices can be suppressed. Further, it becomes possible to form a TiON film having excellent barrier properties and good reproducibility of the film quality, including the upper aluminum film, by one sputtering apparatus. After the TiN film is formed, the TiN film is annealed by another apparatus. It is also advantageous in terms of manufacturing time and manufacturing cost over the conventional process of forming an aluminum film next.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a sputtering apparatus suitable for carrying out the method of the present invention.

FIG. 2 is a diagram showing a modification of the sputtering apparatus shown in FIG.

FIG. 3 is a diagram showing an example of a sputtering apparatus more suitable for carrying out the method of the present invention.

FIG. 4 is a diagram showing the relationship between the number of substrates and the resistivity of TiON.

FIG. 5 is a diagram showing values of standard free energy of formation of Ti-based compounds.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sputtering device 10 Deposition chamber 12 Target 14 Substrate 16 Substrate heating gas heating means 18 Gas introduction port 20 Sputtering gas introduction port 30 Deposition plate 32 Deposition plate heating means 34 Gas heating means 36 Deposition plate heating gas introduction port

Claims (1)

[Claims] 1. A sputtering apparatus equipped with an adhesion-preventing plate is provided with an adhesion-preventing plate heating means for heating the adhesion-preventing plate, and reactive sputtering of a titanium compound is carried out while heating the adhesion-preventing plate to a constant temperature. A method for forming a film of a titanium-based compound, comprising: