JPH0344469A - Plasma treatment device - Google Patents

Abstract

PURPOSE:To improve the cleaning efficiency of the inside of a reaction chamber and to enhance the rate of operation by providing the electrodes and a sample base to the inside of the reaction chamber of a plasma treatment device and forming at least the surface of the electrodes or the sample base of high-m.p. metallic silicide or high-m.p. metal. CONSTITUTION:The upper and lower electrodes 2, 3 are oppositely arranged in a reaction chamber 1 and connected to a high frequency power source 5 and a grounded electrode 6 respectively. Gas for plasma is introduced into this reaction chamber 1 through the supply port 7 of the gas. The inside of the reaction chamber is evacuated and exhausted at the prescribed pressure through an exhaust port 8. Thereby plasma is generated and CVD, etching, etc., are performed on a semiconductor base body 4 placed on the lower electrode 3 utilized is the sample base. In the above-mentioned plasma treatment device, it least the surface of the electrodes 2, 3 and the sample base is formed of high-m.p. metallic silicide or high-m.p. metal. W, Mo, Ta and Zr, etc., are utilized as this high-m.p. metal. Thereby when cleaning is performed by gas contg. NF3 and SF6, etc., such possibility is eliminated that solid of the fluorine compds. of these metals remains and cleaning efficiency is enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a plasma processing apparatus that performs plasma CVD, plasma etching, etc., and particularly relates to a plasma processing apparatus that can effectively clean the inside of a reaction chamber.

[Summary of the Invention] In the plasma processing apparatus of the present invention, at least the surface of the electrode provided in the reaction chamber maintained at a required vacuum pressure or the sample stage on which the semiconductor substrate is placed is made of high-melting point metal silicide or high-melting point metal. This prevents particles from remaining on the electrode or the sample stage, and improves the cleaning efficiency in the reaction chamber and the operating rate of the apparatus.

[Conventional technology]

2. Description of the Related Art Among plasma processing apparatuses that perform plasma CVD, plasma etching, etc., there is a parallel plate type plasma processing apparatus in which a pair of electrodes are disposed facing each other in a reaction chamber. In this parallel plate type plasma processing apparatus, a reaction chamber is maintained at a required vacuum pressure, a semiconductor substrate is placed on one electrode, and a high frequency voltage is applied between the two electrodes to generate plasma. Deposition or etching is then performed on the semiconductor substrate using intermediate active species or the like.

Conventionally, in plasma processing apparatuses, aluminum or aluminum-based alloys have been used as materials for the electrodes as described above. However, since the plasma silicon oxide film and the plasma silicon nitride film are removed, metal remains, and when cleaning is repeated, the fluorine compound grows and becomes particles. Since the adhesion of such particles causes a decrease in work efficiency, it is necessary to remove these particles by mechanical polishing.

On the other hand, devices are also known in which the material used for the electrodes is other than the aluminum-based material mentioned above. For example, JP-A-63-
Examples include a technique in which the exposed surface of the electrode is made of SiC, as in the technique described in Japanese Patent No. 138737, and a technique in which a ceramic electrode is used.

[Problem to be solved by the invention]

However, when argonium or aluminum alloy is used as the electrode material, mechanical polishing as described above requires many work steps and is extremely time consuming, resulting in a significant drop in work efficiency.

On the other hand, when the exposed surface of the electrode is formed of SiC, Si
As the C film thickness varies, the deposition rate and etch rate of the film formed on the semiconductor substrate change, resulting in uneven film thickness.

Furthermore, when a cerazinc electrode is used, the difference in etch rate between the electrode and the semiconductor substrate is small, resulting in poor selectivity and low work efficiency.

Therefore, the present invention was proposed in view of the above-mentioned conventional situation, and an object of the present invention is to provide a plasma processing apparatus that improves the efficiency of cleaning inside a reaction chamber and improves the operating rate of the apparatus. do.

[Means for Solving the Problems] The plasma processing apparatus of the present invention has been proposed to achieve the above-mentioned object, and at least the surface of the electrode or sample stage provided in the reaction chamber is made of high melting point metal silicide or high melting point metal silicide. It is characterized by being formed from a melting point metal.

In the parallel plate type plasma processing apparatus, it is sufficient that at least the surfaces of the pair of electrodes facing each other are formed of high melting point metal silicide or high melting point metal, and the high melting point metal silicide or high melting point metal is formed on the surface of each electrode. Alternatively, a sample stage on which a semiconductor substrate is placed may be installed in the reaction chamber using high melting point metal silicide or high melting point metal.

Here, as high melting point metals and high melting point metal silicides,
Tungsten (W), Molybdenum (Mo) Kuntal (T)
a), zirconium (Zr), etc. and their respective silicides can be used.

In addition, for cleaning, it is possible to use a mixed gas of NF3 and H2, a mixed gas of N'Fs and 02, a mixed gas of SF and H2, and a reactive gas such as ClF3 or F2. Cleaning is performed using a reactive gas.

[Operation] When the high melting point metal silicide or the high melting point metal reacts with the gas of the fluorine thread, there is no risk that the reactant will remain as a solid because the vapor pressure of the fluorine compound of the high melting point metal is high.

Therefore, at least the surface of the electrode or the sample stage is formed of high melting point metal silicide or high melting point metal so that the electrode can be formed on the electrode [Embodiment] A preferred embodiment of the present invention will be described with reference to the drawings.

First Embodiment This embodiment is a parallel plate type plasma CVD' apparatus,
This is an example in which a pair of electrodes are arranged vertically to face each other.

FIG. 1 is a schematic cross-sectional view showing one embodiment of the present invention, showing the internal structure of a reaction chamber. An upper electrode 2 functioning as a cathode electrode and a lower electrode 3 functioning as an anode electrode are arranged facing each other in a metal reaction chamber l. Upper electrode 2
is attached to part 1a of the reaction chamber 1. The upper electrode 2 is connected to a high frequency electric current tA5. The lower electrode 3 is attached to the bottom 1b of the reaction chamber 1. Ground voltage 6 is applied to the lower electrode 3.
is supplied. Furthermore, a semiconductor substrate 4 to be processed when performing CVD is placed on the lower electrode 3.

A gas supply lower and an exhaust port 8 are opened in the reaction chamber 1, and a reaction gas whose flow rate is appropriately controlled is introduced into the reaction chamber 1 from the gas supply lower and exhausted from the exhaust port 8 at the same time. Thereby, the inside of the reaction chamber 1 is maintained at a predetermined vacuum pressure.

Although not shown in FIG. 1, an 11 gauge, gas valve, etc. for adjusting the flow rate of the reaction gas, or a temperature control system for controlling the temperature inside the reaction chamber 1 may be used as necessary. It will be established.

In the plasma CVD apparatus of this embodiment, the upper electrode 2 and the lower electrode 3 are formed of tungsten silicide, which is a high melting point metal silicide.

In this way, the upper electrode 2. By forming the lower electrode 3 with high melting point metal silicide, electrical conductivity and heat transfer rate are ensured in the upper electrode 2 and the lower electrode 3. In addition, unlike conventional aluminum electrodes, when cleaning the electrode using fluorine gas, the vapor pressure of the fluorinated substances produced by the reaction is low, so Jc and elementary compounds remain on the electrode as solids. Therefore, the inside of the reaction chamber can be cleaned efficiently. Further, the etch rate in the semiconductor substrate 4 remains unchanged, and the efficiency of deposition and etching operations is improved.

Note that the upper electrode 2. The material for forming the lower electrode 3 may be any refractory metal or refractory metal silicide, and in addition to tungsten silicide, for example, tungsten (
W), zirconium (Zr).

Examples include tantalum (Ta), molybdenum (Mo), and their respective silicides.

The conditions for self-cleaning may be determined as appropriate, and in this example, good results were obtained when etching was performed under the following conditions. That is, 13.5 to the high frequency power supply 5
When a frequency of 6 MHz is used, the temperature is 250°C, the pressure is 2 Torr, and the reaction gas NFI flow rate and H2 flow rate are each 503 CCM, the electrode is not etched and the plasma silicon nitride film or plasma silicon film is etched. Only the oxide film is selectively etched under the same conditions with the reaction gas NF3 flow rate and 0□? Even when the IL amount was set to 503 CCM, it was possible to similarly etch a plasma silicon nitride film and a plasma silicon oxide film.

In addition to the above-mentioned reaction gas, SF, a mixed gas of H2,
ClF3 or F2 can be used.

As described above, by forming the upper electrode 2 and the lower electrode 3 with tungsten silicide, the plasma silicon nitride film and the plasma silicon oxide film can be selectively etched without etching the electrodes. .3 It is possible to prevent particles of a monoatomic compound from remaining on the surface. Therefore, the cleaning efficiency in the reaction chamber and the operating rate of the apparatus are improved.

Second Embodiment This embodiment is a parallel plate type plasma CVD apparatus, and is an example in which a tungsten silicide film is formed on the opposing surfaces of a pair of electrodes.

As shown in FIG. 2, an upper electrode 12 that functions as a cathode electrode and a lower electrode 13 that functions as an anode electrode are arranged facing each other in a metal reaction chamber 11. Upper electrode 12
．． Tungsten silicide films 19 and 20 are formed on opposing surfaces of the lower electrode 13. When performing CVD, the semiconductor substrate 14 is placed on the tungsten silicide film 20. The upper electrode 12 is connected to the reaction chamber 11.
It is attached to the upper part 11a of the. Upper electrode 12 is connected to high frequency power source 15 . The lower electrode 13 is attached to the bottom 11b of the reaction chamber 11. A ground voltage 16 is applied to the lower electrode 13.
is supplied.

Similarly to the plasma CVD apparatus of the first embodiment, a gas supply port 17 and an exhaust port are opened in the reaction chamber 11 to maintain a required vacuum pressure. Although not shown in FIG. 2, a gas flow rate controller, gas valve, etc., or a temperature control system may be provided as necessary.

The tungsten silicide films 19 and 20 may be any film formed of a high-melting point metal or a high-melting point metal silicide, such as tungsten (W), molybdenum (Mo),
Zirconium (Zr), taftal (Ta), or their respective silicides can be used.

By forming the tungsten silicide films 19 and 20 on the upper electrode 12 and the lower electrode 13 in this way, it is possible to prevent particles of the fluorine compound from remaining on the electrodes even if cleaning is performed using fluorine gas. is,
Cleaning inside the reaction chamber is performed efficiently. Further, the conditions for self-cleaning are determined as appropriate. It is preferable to perform etching under conditions in which the plasma silicon nitride film and the plasma silicon oxide film are selectively etched without etching the electrodes.

Further, the upper electrode 12. By using aluminum as the material of the lower electrode 13 and forming tungsten silicide films 19 and 20 on the surfaces of the upper electrode 12 and lower electrode 13 made of aluminum, the entire electrode can be raised as in the first embodiment. A plasma processing apparatus that is superior in electric conductivity and heat transfer rate to a structure formed of a melting point metal or a high melting point metal silicide can be obtained.

Note that in the first embodiment, the upper electrode 2. The entire lower electrode 3 is made of a refractory metal or a refractory metal silicide, and in the second embodiment, the upper electrode 12. Lower electrode 13
Although the configuration is such that the tungsten silicide films 19 and 20 are formed thereon, the present invention also has a configuration in which a sample stage made of a high melting point metal or high melting point metal silicide is installed on the electrode or at an appropriate position in the reaction chamber. You can also use it as

〔Effect of the invention〕

According to the plasma processing apparatus of the present invention, at least the surface of the sample stage on which the electrode or the semiconductor substrate is placed is formed of high-melting point metal silicide or high-melting point metal, so that the murroline compound is formed on the electrode. Particles are prevented from remaining. Therefore, it is possible to efficiently clean the inside of the reaction chamber, and there is no need to remove particles by mechanical polishing, which improves the operating rate of the equipment.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing one embodiment of the plasma processing apparatus of the present invention, and FIG. 2 is a schematic cross-sectional view showing another embodiment of the plasma processing apparatus of the present invention. 1.11 ・ 2, 12 ・ 3, I 3 ・ 4, l 4 ・ 5, 15 ・ 6 16 ・ 7, 17 ・ 8, 18 ・ 19. 20 ・Reaction chamber Upper electrode Lower electrode Semiconductor substrate High frequency power supply Ground voltage Gas Supply port exhaust port: Tungsten silicide film

Claims (1)

[Claims] A plasma processing apparatus characterized in that at least the surface of an electrode or a sample stage provided in a reaction chamber is formed of high melting point metal silicide or high melting point metal.