JPH09283511A - Vapor growth system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dispense with a posttreatment and to form a Ta2 O5 film having a full capacity by a method wherein a plasma generating chamber and a reduced thermal CVD reaction chamber are separated from each other by more than one piece of orifices, which respectively have an open. SOLUTION: A plasma generating chamber 3 and a reduced thermal CVD reaction chamber 5 are separated from each other by orifices 7. The orifices 7 respectively have an open 23 in their roughly central parts. Active species generated in the chamber 3 are transferred on the surface of a wafer 21 placed on the upper surface of a susceptor 15 in the chamber 5 through the opens 23 formed in the orifices 7 by a pressure difference between the pressures in both chambers of the chambers 3 and 5. As the wafer 21 is heated to 400 to 600 deg.C by a heating means 17 of the susceptor 15, a thermal CVD film formation reaction due to the active species is caused in the surface of the wafer and a Ta2 O5 film is formed on the surface of the wafer. Thereby, a leakage current due to the formation of an SiO2 film on a lower electrode due to a plasma ion impact can be eliminated, a posttreatment is unnecessary and a high- dielectric constant insulating film having not the leakage current can be formed.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vapor phase growth apparatus. More particularly, the present invention relates to plasma enhanced thermal CVD equipment.

[0002]

2. Description of the Related Art In manufacturing a semiconductor IC, there is a step of forming an insulating film such as silicon oxide (SiO ₂ ) on the surface of a wafer. Chemical vapor deposition (CVD) is used as a method for forming such an insulating film.

For example, SiH ₄ which is a monosilane gas has been used as a material for forming a silicon oxide film, but with the miniaturization of semiconductor devices, a decrease in step coverage has become a problem.

In particular, as a high dielectric insulating film for capacitors after the quarter micron process, T by thermal CVD is used.
An a ₂ O ₅ film has been investigated. Ta ₂ O ₅ of tantalum oxide film
The film is formed by vaporizing liquid Ta (OC ₂ H ₅ ) ₅ and introducing it into the reaction furnace. Vaporized Ta (OC
₂ H ₅ ) ₅ gas is mixed with oxygen gas or ozone gas and used for film formation reaction.

However, that in the case of forming a the Ta ₂ O ₅ film as a high dielectric insulating film for a capacitor, the leakage current increases by oxygen deficiency the Ta ₂ O ₅ film is deposited, as a result, sufficient capacity can not be secured There's a problem. As a countermeasure against this oxygen deficiency, there is a method of performing O ₂ annealing, O ₂ plasma treatment or the like as a post-treatment after deposition of the Ta ₂ O ₅ film.
Undergoes an oxidation reaction between the polysilicon surface of the base electrode O ₂ ions excited by plasma is transmitted through the the Ta ₂ O ₅ film, SiO ₂ film is formed between the Ta ₂ O ₅ film and polysilicon, leakage current Can be suppressed. However, there is a problem that it is difficult to secure capacitance as a high dielectric constant insulating film for capacitors. Further, the O ₂ annealing has a problem that the absolute leak current amount cannot be suppressed as compared with the O ₂ plasma treatment.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to form a vapor phase Ta ₂ O ₅ film which does not require post-treatment and has a sufficient capacity as a high dielectric insulating film for a capacitor. It is to provide a growth device.

[0007]

An object of the present invention is to provide an orifice having a plasma generation chamber and a reduced pressure thermal CVD reaction chamber, and an orifice having one or more openings between the plasma generation chamber and the reduced pressure thermal CVD reaction chamber. It is solved by a vapor phase growth apparatus characterized by being isolated by.

[0008]

1 is a schematic sectional view of an example of a vapor phase growth apparatus 1 of the present invention. The vapor phase growth apparatus of the present invention basically comprises a plasma generation chamber 3 and a low pressure thermal CVD reaction chamber 5.
It has a room structure. An orifice 7 is provided between the plasma generation chamber 3 and the low pressure thermal CVD reaction chamber 5 to separate the two chambers.

A coil 9 is provided on the outer peripheral side wall of the plasma generating chamber 3.
Is wound, and the end of the coil 9 has a high frequency power source 1
1 connected. The frequency of the high frequency power source 11 is not particularly limited, but generally, a frequency of 13.56 MHz is preferably used. Further, a reaction gas feed pipe 13 is connected to an appropriate portion of the plasma generation chamber 3, and this pipe 13
As a result, a mixed gas of vaporized Ta (OC ₂ H ₅ ) ₅ gas and oxygen gas or N ₂ O gas is fed into the plasma generation chamber 3.
The plasma generating chamber 3 is made of an insulating material such as quartz. Other insulating materials such as alumina, sapphire glass, and aluminum nitride can be used as well.

The low-pressure thermal CVD reaction chamber 5 has a room temperature of 0.1 to 10.
A vacuum pump 14 is connected in order to enable a reduced pressure state within a range of about 1 Torr. It is not necessary to dispose two vacuum pumps as shown in the drawing, and only one vacuum pump can be formed as long as a predetermined reduced pressure state can be formed.
It may be a base. A susceptor 15 is arranged in the reduced pressure thermal CVD reaction chamber 5. The susceptor 15 can be heated to a temperature within the range of 400 to 600 ° C. by a suitable heating means 17. This processed material 21 is heating means 1
7 is heated to a predetermined temperature through the susceptor 15.
The low pressure thermal CVD reaction chamber 5 can be formed of a conductor such as aluminum. Further, the susceptor 15 can also be formed of a known and commonly used material. Such materials are, for example, alumite-treated aluminum and Si-C.

Plasma generation chamber 3 and low pressure thermal CVD reaction chamber 5
An orifice 7 separates the space between and. The orifice 7 is preferably made of an insulating material. If the orifice 7 is not an insulator, an internal discharge is generated between the plasma generation chamber 3 and the orifice 7 and activated ions are not efficiently supplied to the low pressure thermal CVD reaction chamber side. As the insulator for forming the orifice 7, for example, quartz, alumina, aluminum nitride or the like can be appropriately selected and used.

The orifice 7 has an opening 23 at its substantially central portion. The opening diameter of the opening 23 may be fixed, but in the vapor phase growth apparatus of the present invention, the opening diameter of the opening 23 of the orifice 7 can be changed. The effect of improving the uniformity of the formed film can be obtained by changing the opening diameter. The opening diameter can be changed steplessly or can be changed stepwise.
When the aperture diameter is changed steplessly, the orifice 7 can use a known and conventional mechanical aperture stop mechanism such as an iris stop. When changing the opening diameter stepwise, use by exchanging a plurality of plates having different opening diameters, or stacking these plates,
Alternatively, it can be carried out by removing. The opening diameter of the opening 23 is preferably adjusted so that the pressure difference between the plasma generation chamber 3 and the low pressure thermal CVD reaction chamber 5 is about 10 to 100 times. Such a relationship between the pressure difference between the two chambers and the opening diameter can be easily determined by repeating the experiment.

In the embodiment shown in FIG. 1, the orifice 7
Has only one opening 23. However, the number of openings provided is not limited to one. For example, an orifice 7 having a plurality of openings 23 as shown in FIG. 2 can be used.
The number of openings 23 and / or the opening diameter of each opening is
It can be appropriately determined by repeating the experiment in consideration of the desired pressure difference between the plasma generation chamber 3 and the low pressure thermal CVD reaction chamber 5.

Next, a method of forming an insulating film by the vapor phase growth apparatus of the present invention will be described. First, vaporized Ta (OC ₂ H ₅ ) ₅ gas and oxygen gas or ozone gas are supplied from a supply source (not shown), and these are mixed and fed into the plasma generation chamber 3 through the reaction gas feed pipe 13. . The high frequency power supply 11 is driven to apply a high frequency of 13.56 MHz to the coil 9 to generate plasma in the plasma generation chamber 3.
The generation of plasma excites the reaction gas in the plasma generation chamber 3 to generate various active species. As described above, the internal pressure of the reduced pressure thermal CVD reaction chamber 5 is in a reduced pressure state of about 0.1 to 1 Torr, while the internal pressure of the plasma generation chamber 3 is about 1 to 10 Torr. Therefore, the activated species generated in the plasma generation chamber 3 are
It moves through the opening 23 of the orifice 7 to the surface of the wafer 21 mounted on the upper surface of the susceptor 15 in the low pressure thermal CVD reaction chamber 5. Since the wafer 21 is heated to 400 to 600 ° C. by the heating means 17 of the susceptor 15, the thermal CVD film formation reaction by the active species occurs on the wafer surface, and a Ta ₂ O ₅ film is formed on the wafer surface.

In the apparatus of the present invention, the plasma active species are transferred to the wafer surface due to the pressure difference, so that the SiO ₂ on the lower electrode due to the ion bombardment of plasma as in the conventional apparatus.
Does not occur. As a result, it is possible to form a high-dielectric-constant insulating film having a low leak current without any post-treatment process.

Although the apparatus of the present invention has been described with respect to the formation of a Ta ₂ O ₅ film, the reaction gas in the apparatus of the present invention is not limited to the vaporized Ta (OC ₂ H ₅ ) ₅ gas, and other vaporizations are possible. Gas can be used as well. For example, Ta (OC
H ₃ ) ₅ gas, etc. can also be used.

[0017]

As described above, in the vapor phase growth apparatus of the present invention, the activated species excited in the plasma generation chamber are heated under reduced pressure C.
Since it is transferred to the VD reaction chamber on the surface of the wafer due to the pressure difference, there is no leak current due to the SiO ₂ film formation on the lower electrode due to the ion bombardment of plasma unlike the conventional apparatus. As a result, it becomes possible to form an excellent high-dielectric-constant insulating film that does not require a post-treatment process and has no leakage current.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an example of a vapor phase growth apparatus of the present invention.

2 is a cross-sectional view of another example of an orifice used in the device shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Vapor phase growth apparatus of this invention 3 Plasma generation chamber 5 Decompression thermal CVD reaction chamber 7 Orifice 9 Coil 11 High frequency power supply 13 Reactive gas inlet pipe 14 Vacuum pump 15 Susceptor 17 Heating means 19 Elevating support 21 Wafer 23 Orifice opening

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H01L 21/316 H01L 21/316 X

Claims (11)

[Claims] 1. A plasma generation chamber and a low pressure thermal CVD reaction chamber, wherein the plasma generation chamber and the low pressure thermal CVD reaction chamber are separated by an orifice having one or more openings. And vapor phase growth equipment. 2. The orifice has one opening, the opening diameter of the opening can be changed stepwise or steplessly, and the pressure between the two chambers is about 10 to 100 times. The vapor phase growth apparatus according to claim 1, wherein 3. The orifice has a plurality of openings, the opening diameter of each opening is fixed, and the pressure between both chambers is 10 mm.
The vapor phase growth apparatus according to claim 1, wherein the difference is about 100 times. 4. The plasma generation chamber is formed of an insulating material, a coil is wound around the outer peripheral side wall thereof, the end of the coil is connected to a high frequency power source, and the low pressure thermal CVD reaction chamber is made of a conductive material. 2. A susceptor having a heating means is disposed inside the susceptor.
Vapor growth equipment. 5. The vapor phase growth apparatus according to claim 4, wherein a high frequency power source of 13.56 MHz or less is used. 6. The distance between the orifice and the susceptor is 5
The vapor phase growth apparatus according to claim 4, which is within a range of 0 to 100 mm. 7. The vapor phase growth apparatus according to claim 4, wherein the temperature of the susceptor is heated to 200 to 500 ° C. 8. A reaction gas is fed into a plasma generation chamber, the reaction gas is excited by plasma, and the excited active species are introduced into a low pressure thermal CVD reaction chamber through an orifice and at a substantially central portion of the orifice. The pressure difference between the plasma generation chamber and the low pressure thermal CVD reaction chamber is passed through the provided opening, and transferred to the surface of the workpiece on the susceptor in the low pressure thermal CVD reaction chamber to form an oxide film by the thermal CVD reaction. A film forming method characterized by the above. 9. The method according to claim 8, wherein the reaction gas is a mixed gas of vaporized Ta (OC ₂ H ₅ ) ₅ gas and oxygen gas or nitrous oxide gas, and the oxide film is a Ta ₂ O ₅ film. 10. The film forming method according to claim 8, wherein the distance between the orifice and the susceptor is in the range of 50 to 100 mm. 11. The film forming method according to claim 8, wherein the temperature of the susceptor is heated to 200 to 500 ° C.