JPH10199860A - Plasma processing method and apparatus - Google Patents

Abstract

(57) [Summary] In a plasma processing apparatus, prevention of adhesion of reaction products on the entire inner surface of a processing chamber, formation of a large-area uniform plasma,
Achieve lower plasma generation pressure. The plasma processing apparatus includes a means for supplying a processing gas, a means for exhausting the processing chamber, a means for controlling a pressure in the processing chamber, a means for flowing a high-frequency current over the entire wall surface of the processing chamber, and a plasma. , Means for not diffusing the outside.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching apparatus and an etching method suitable for an etching process for forming a fine pattern of an integrated circuit element, and a plasma CVD apparatus and a plasma CVD apparatus suitable for forming a flat insulating film. A film forming method.

[0002]

2. Description of the Related Art Japanese Patent Application Laid-Open No. 57-131374 discloses a parallel plate electrode type plasma processing electrode suitable for etching and plasma CVD. By using two high-frequency power sources having different frequencies, the etching processing characteristics such as damage to the device and deterioration of the resist are improved. However, these conventional technologies take into account the reduction of dust generated when processing a large number of substrates in mass production, uniform processing of large-diameter substrates corresponding to large-diameter substrates, and high-precision processing of fine patterns. However, it is a bottleneck in mass-producing highly integrated circuit elements.

[0003]

[Problems to be solved by the invention]

1) It is necessary to reduce the dust generated during the plasma processing by preventing the products such as reaction products generated by the chemical reaction and the etching reaction in the plasma in the plasma processing chamber from adhering to the processing chamber wall and preventing the deterioration of the processing chamber wall.

2) With the increase in the diameter of the processing substrate, it is necessary to make the large-diameter substrate uniform.

[0005] 3) With the miniaturization of patterns, it is necessary to form fine shapes with high precision.

4) The process window becomes narrower as the pattern becomes finer, and it is necessary to stabilize plasma processing and improve reproducibility.

[0007]

[Means for Solving the Problems]

1) The ions in the plasma are made to be incident on the entire wall surface of the processing chamber at a controlled energy, and the reaction products attached to the wall surface of the processing chamber and the altered layer on the inner wall surface are removed by the energy of the incident ions. Prevent dust generated.

[0008] 2) By the above method, the reaction products are prevented from adhering to the wall surface of the processing chamber, and the reproducibility of the process is prevented from being reduced due to the generation of gas from the reaction product.

3) In order to form uniform plasma required for uniform processing of a large-diameter substrate, the entire wall surface of the processing chamber is used as a plasma generation region. By using the entire wall surface of the processing chamber as the plasma generation source, the density distribution gradient of the plasma in the processing chamber is eliminated and uniform plasma can be formed.

4) One of the factors that hinder high-precision etching is that the scattering angles of ions and electrons incident on the substrate are different.
The amount of electrons and ions incident on the uneven surface varies from place to place, and a charge distribution is formed, thereby increasing the influence of ion trajectories.

For this purpose, it is necessary to increase the effective acceleration voltage at the time of electron incidence, and it is necessary to increase the frequency of the high-frequency voltage applied to the electrode on which the substrate is placed, and to increase the effective acceleration voltage at the time of electron incidence. . However, when the frequency is increased, the applied voltage decreases and the acceleration voltage of the ions decreases. As a solution of the present invention, a high-frequency voltage having a high frequency for accelerating electrons and a high-frequency voltage having a low frequency for accelerating ions to generate a high accelerating voltage are used to reduce the scattering angle between electrons and ions, thereby increasing the etching efficiency. Accuracy was improved.

5) One of the factors inhibiting high-precision etching is that ions accelerated by a sheath between the plasma and the substrate collide with neutral gas molecules between the sheaths and scatter. In the present invention, the entire surface of the inner wall of the processing chamber is used as a plasma generation region, confining the plasma, and increasing the frequency of the high-frequency power so that the high-frequency power is efficiently absorbed by the plasma, thereby realizing high-density plasma generation at a low pressure. did. As a result, the mean free path in which ions collide with neutral gas molecules is lengthened, and ion scattering due to collision between sheaths is reduced.

[0013]

FIG. 1 shows an embodiment of the present invention.

In the processing chamber 1, a stage electrode 2 and a counter electrode 3 are provided. There is a sub-electrode: 4 around the stage electrode: 2, an insulator: 5 around the stage electrode: 2, and the sub-electrode: 4, and an earth shield: 6
Insulation between them is maintained. The stage electrode 2 has a structure in which the bellows 7 can move up and down while maintaining a vacuum.

On the sub-electrode 4: silicon carbide cover:
8 are provided. 80M from the signal generator: 9 to the stage electrode: 2 via the power amplifier: 10
A matching box 1:11 for Hz and a matching box 2:12 for 10 MHz are connected. The sub-electrode 4 is connected to an earth shield 6 via a band-pass filter 13 for 40 MHz, and the earth shield is grounded.

The stage electrode has a structure in which a refrigerant circulates from a temperature control unit (not shown), so that the temperature of the stage can be maintained at a set temperature. Further, the stage electrode: a means for supplying helium gas to the surface on which the two substrates are placed, and a function for electrostatically adsorbing the substrate to the stage electrode surface are built in, and the temperature of the substrate during plasma processing is kept constant. be able to.

Around the counter electrode: 3, the sub-electrode: 20,
There are sub-electrodes: 21, each of which is insulated by an insulator: 22, and is also insulated by a processing chamber: 1, and an earth shield:. A plasma processing gas is supplied to the counter electrode 3 from a supply source (not shown) at a set flow rate, and the processing gas is blown out from the front surface of the electrode surface by a dispersion plate provided in the counter electrode 3. It has a structure. A 27 MHz high frequency power supply: 24 is connected to the counter electrode: 3 via a matching box: 25, and 8
0 MHz and 10 MHz band pass filters: 26
(A) and 26 (b) are connected to the counter electrode: 3 and are grounded to ground.

A sub-electrode 20 is connected to a 40 MHz high-frequency power supply 27 via a matching box 28, and a sub-electrode 21 is connected to an earth shield 23 via a 27 MHz band-pass filter 29. And grounded. A cover 30 of silicon carbide is provided on the surfaces of the sub-electrodes 20 and 21.

Magnets 31 (a) and (b) are provided on the outer periphery of the earth shields 6 and 23 to form a magnetic field 33.

In the processing chamber 1, a cleaning electrode 35 is provided via an insulator 34 and a switching box:
It is connected to a matching box 25 through 36.

The inside of the processing chamber 1 is exhausted by an exhaust system 37, and the exhaust amount is controlled so that the pressure can be controlled to a constant value. The processing chamber and the joint between the electrodes have a vacuum seal structure, and the processing chamber 1 can be evacuated to a vacuum.

Next, an example of the operation in the etching process according to this embodiment will be described.

The stage electrode 2 is lowered, an etching substrate 40 is carried in from a substrate entrance (not shown), and placed on the stage electrode 2. The stage electrode 2 is raised and stopped at a position where the gap 41 between the counter electrode 3 and the outer periphery becomes 5 mm.

An etching gas (chlorine gas) at a set flow rate is supplied from a plasma processing gas supply source (not shown), and the exhaust is controlled so that the pressure in the processing chamber becomes 1 Pa. The processing substrate is electrostatically attracted to the stage electrode: 2, and
Helium gas is supplied from a helium gas supply source (not shown) so that a pressure of 1000 Pa is applied between the substrate and the surface of the stage electrode.

27 MHz high frequency power supply: 800 from 24
The power of w is supplied to the counter electrode 3. The high-frequency current flows from the counter electrode: 3 to the sub-electrode: 21, and the counter electrode: 3
Plasma is mainly generated near the surface and near the surface of the sub-electrode 21. 40MHz high frequency power supply: 6 from 27
A power of 00 W is supplied to the sub-electrode 20. The high-frequency current flows from the sub-electrode 20 to the sub-electrode 4 at the outer periphery of the stage electrode 2 to generate plasma near the surfaces of the sub-electrodes 20 and 4. As described above, since plasma is generated on the entire surface surrounding the substrate, a plasma density gradient is hardly generated, and uniform plasma can be easily generated. Magnet: 31 (a) (b)
Generates a local magnetic field: 33 to prevent the plasma from diffusing to the outside.

The density distribution of the plasma can be adjusted by controlling the power of the high frequency power supply: 24 for supplying power to the counter electrode: 3 and the power of the high frequency power supply: 27 for supplying power to the sub-electrode: 20; Uniform processing can be easily performed even on a substrate having a large diameter.

Since a high-frequency current flows between the stage electrode 2, the counter electrode 3, and the sub-electrodes 4, 20, 21, ions enter the surfaces of these electrodes with energy, and are cleaned. I have. In the present invention, since these electrodes are arranged close to each other, the entire surface of the processing chamber is cleaned with ions. When the material of the inner surface of the processing chamber reacts with a chlorine-based or fluorine-based etching gas to generate non-volatile reaction products, these become sources of foreign matter. For example, when the surface of aluminum is fluorinated, aluminum fluoride is formed, which peels off and becomes foreign matter. Therefore, the material on the inner wall of the processing chamber reacts with chlorine-based or fluorine-based etching gas to form volatile reaction products, such as quartz, silicon carbide,
Materials such as silicon and nitrite are preferred.

By these measures, the processing chamber of this embodiment has a structure in which reaction products do not adhere and foreign substances are hardly generated, and the reaction products do not gasify and enter the processing chamber. Therefore, stable processing can be performed.

In addition, since plasma is generated on the entire surface surrounding the substrate, the plasma density does not decrease due to diffusion. Further, the increase in the density reduces the thickness of the sheath formed between the plasma and the electrode. Among them, the power consumed by the sheath decreases, the proportion of power consumed in the plasma increases, and the plasma density further improves. These and the frequency of the high frequency power are 27 MHz, 40 MHz
By using a frequency higher than 13.56 Mhz, which is often used in the related art, the power consumption in the sheath is further reduced, and the power consumption ratio in the plasma is increased. By these, 1
Even at a low pressure of Pa to 3 Pa, high-density plasma of 10E10 to 10E11 cells / cm ³ can be generated. As a result, the processing pressure is reduced, and highly accurate etching can be performed.

Signal generator: 80 MHz from 9
And the signal of the frequency of 10MHz are output alternately,
The time ratio can be adjusted. This signal is amplified by the power amplifier 10 and applied to the stage electrode 2 from the matching boxes 11 and 12. 8
Under the condition of 0 MHz, since the frequency is high, the influence of the surface charging by the electrons can be reduced, and the acceleration of the electrons incident on the substrate can be increased. Under the condition of 10 MHz, a voltage sufficient to accelerate the ions between the sheaths is provided. Can occur,
The ion energy can be controlled.

As described above, according to the present invention, since both electrons and ions can be accelerated, the distribution of electrons and ions incident on the uneven etching surface can be made uniform, and non-uniform charge can be prevented. Therefore, it is possible to prevent an etching shape defect due to non-uniform charge, and to realize highly accurate etching. Also, as mentioned earlier, 1 to 3P
Since high-density plasma can be generated at a low pressure a, collision between ions and neutral gas molecules between the sheaths can be reduced, and defective etching shapes due to ion scattering can be reduced.

Further, in the present invention, the cleaning electrode: 35
By applying high-frequency power to the power supply and generating a discharge between the ground shields 6 and 23, the lower part of the processing chamber can be cleaned, and the generation of foreign substances and gas release from these parts can be prevented, and stable processing can be realized.

Although the processing example of the etching apparatus has been described above, the present invention can also be applied to film formation such as plasma CVD. In the case of a plasma CVD process in which an organic silane gas and oxygen are mixed to form a silicon oxide film and a film forming surface is sputtered with ions and flattened, when a process is performed by adding a silane fluoride gas, the film is formed on the inner wall of the processing chamber. Since the silicon oxide film to be etched is etched with fluorine gas, it is always etched, so that a film can be formed without adhesion of the film and without generation of foreign matter.

[0034]

According to the present invention, stable processing can be performed without generation of foreign matter, and a large-diameter substrate can be uniformly processed with high accuracy, so that plasma processing with high yield and high productivity can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing a cross section of a plasma processing chamber of the present invention.

[Explanation of symbols]

1: processing chamber, 2: stage electrode, 3: counter electrode, 4 sub-electrodes, 8: cover, 9: signal generator, 10:
Power amplifier, 11, 12: matching box, 1
3: bandpass filter, 20, 21: sub-electrode, 2
4: High frequency power supply, 25: Matching box, 26: Band pass filter, 27 High frequency power supply, 29: Band pass filter, 30: Cover, 31: Magnet, 35: Cleaning electrode

Continued on the front page (72) Inventor Tetsunori Kaji 794, Higashi-Toyoi, Kazamatsu-shi, Yamaguchi Prefecture Inside the Kasado Plant of Hitachi, Ltd. Inside the factory

Claims (2)

[Claims] 1. A plasma processing apparatus having a means for supplying a processing gas, a means for exhausting a processing chamber, a means for controlling a pressure in a processing chamber, a means for flowing a high-frequency current over the entire wall surface of the processing chamber, and a means for diffusing plasma to the outside. A plasma processing apparatus comprising means for preventing the plasma processing. 2. A plasma processing apparatus comprising: means for supplying a processing gas; means for evacuating the processing chamber; means for controlling the pressure in the processing chamber; and a frequency and ions suitable for accelerating electrons on an electrode on which a processing substrate is mounted. A plasma processing apparatus having means for applying high-frequency power having a frequency suitable for accelerating the plasma.