JP2021098876A - Plasma treatment apparatus - Google Patents

Abstract

To sufficiently decompose even a gas used for film deposition which is a strongly coupled gas.SOLUTION: A plasma treatment apparatus 100 feeds a high-frequency current IR to an antenna 3 arranged in a vacuum container 2 to generate induction coupled plasma P in the vacuum container 2, and uses the induction coupled plasma P to treat a substrate W. The plasma treatment apparatus comprises a first gas introduction member 7 which has a first gas flow path 7c where a first gas flows, and introduces the first gas into the induction coupled plasma P, and a power source V which applies a negative voltage to the first gas introduction member 7, and the first gas introduction member 7 functions as a hollow cathode which confines electrons into the first gas flow path 7c with the negative voltage.SELECTED DRAWING: Figure 3

Description

The present invention relates to a plasma processing apparatus.

As a plasma processing apparatus, as shown in Patent Document 1, there is an apparatus that generates inductively coupled plasma (abbreviated as ICP) and processes a substrate using this inductively coupled plasma.

Specifically, this plasma processing apparatus includes a vacuum vessel in which the substrate is housed and an antenna provided in the vacuum vessel so as to face the substrate, supplies gas for film formation into the vacuum vessel, and the antenna. A high-frequency current is passed through the substrate to generate an induction-coupled plasma, so that the substrate is subjected to processing such as film formation.

However, when used as a strong bond such as for example N ₂ gas as the film forming gas, it may be impossible to sufficiently decompose the gas, when used in combination with weak gas bonds, for example binding is weak There may be a problem that a desired film quality cannot be obtained due to the tendency of gas decomposition to proceed.

JP-A-2018-156880

Therefore, the present invention has been made to solve the above problems, and the main object of the present invention is to enable sufficient decomposition even if the film-forming gas is a gas having a strong bond.

That is, the plasma processing apparatus according to the present invention generates an inductively coupled plasma in the vacuum vessel by passing a high-frequency current through an antenna arranged in the vacuum vessel, and processes the substrate using the inductively coupled plasma. A plasma processing apparatus having a first gas flow path through which a first gas flows, and having a first gas introduction member that introduces the first gas into the induction-coupled plasma, and a negative first gas introduction member. A power source for applying a voltage is provided, and the first gas introducing member functions as a hollow cathode for confining electrons in the first gas flow path by the negative voltage.

According to the plasma processing apparatus configured in this way, since the first gas introduction member functions as a hollow cathode, even if the first gas is a gas having a strong bond, the electrons confined in the first gas flow path are used. The first gas can be sufficiently decomposed.

As a specific configuration for exerting the function as a hollow cathode, the first gas introduction member is larger than the introduction port into which the first gas is introduced and the introduction port, and the first gas is derived. The first gas flow path has an upstream side flow path connected to the introduction port and a downstream side flow path having a larger cross section than the upstream side flow path and connected to the outlet. A configuration having a side flow path can be mentioned.
With such a configuration, since the cross section of the downstream flow path is larger than that of the upstream side flow path, electrons can be confined in this downstream side flow path and pass through this downstream side flow path. At this time, the first gas can be sufficiently decomposed.

As a more specific embodiment, the downstream flow path has a cylindrical shape, a diameter of 3 mm or more and 40 mm or less, and an axial length of 1 time or more and 1.5 times or less of the diameter. Can be done.

It has a second gas flow path through which a second gas different from the first gas flows, and further includes a second gas introduction member that introduces the second gas into the inductively coupled plasma, and the first gas is: It is preferably a gas having a stronger bond than the second gas.
With such a configuration, in a configuration in which a plurality of types of film-forming gases are used to form a film, the film-forming process can be performed after the gas having a strong bond (first gas) is sufficiently decomposed.

In order to be able to form a homogeneous film using a plurality of types of film forming gases, the first gas introducing member is a long one having a plurality of the first gas flow paths. The second gas introduction member is a long one having a plurality of the second gas flow paths, and the plurality of the first gas introduction members and the plurality of the second gas introduction members are in the longitudinal direction of the antenna. It is preferable that the antennas are alternately provided along the antenna or along the direction orthogonal to the longitudinal direction of the antenna.

The aspect effects of the present invention are more remarkably exhibited, the first _{gas, N 2, O 2, HF} X, SiF X, SF X, or CF _X of the like when at least one Can be done.

According to the present invention configured as described above, even if the film-forming gas is a gas having a strong bond, it can be sufficiently decomposed.

The schematic diagram which shows the structure which looked at the plasma processing apparatus of this embodiment from above. AA'line sectional view showing an internal configuration of the plasma processing apparatus of the same embodiment. BB'line sectional view showing the internal structure of the plasma processing apparatus of the same embodiment. BB'line sectional view showing the internal configuration of the plasma processing apparatus of the modified embodiment. BB'line sectional view showing the internal configuration of the plasma processing apparatus of the modified embodiment. The schematic diagram which shows the structure which looked at the plasma processing apparatus of a modified embodiment from above.

Hereinafter, an embodiment of the plasma processing apparatus according to the present invention will be described with reference to the drawings.

<Device configuration>
As shown in FIGS. 1 and 2, the plasma processing apparatus 100 of the present embodiment processes the substrate W using the inductively coupled plasma P. Here, the substrate W is, for example, a substrate for a flat panel display (FPD) such as a liquid crystal display or an organic EL display, a flexible substrate for a flexible display, or the like. The treatment applied to the substrate W is, for example, film formation, etching, ashing, sputtering, etc. by the plasma CVD method.

The plasma processing apparatus 100 includes a plasma CVD apparatus when forming a film by a plasma CVD method, a plasma etching apparatus when performing etching, a plasma ashing apparatus when performing ashing, and a plasma sputtering apparatus when performing sputtering. be called.

Specifically, as shown in FIGS. 1 and 2, the plasma processing apparatus 100 is inductively coupled to the vacuum vessel 2 to be evacuated, the linear antenna 3 arranged in the vacuum vessel 2, and the vacuum vessel 2. It includes a high-frequency power source 4 that applies a high frequency to generate a type of plasma P to the antenna 3. By applying a high frequency from the high frequency power supply 4 to the antenna 3, a high frequency current IR flows through the antenna 3, an inductive electric field is generated in the vacuum vessel 2, and an inductively coupled plasma P (hereinafter, simply referred to as a plasma P) is generated. Is generated.

As shown in FIG. 2, the vacuum container 2 is, for example, a metal container, and the inside thereof is evacuated by the vacuum exhaust device 6. The vacuum vessel 2 is electrically grounded in this example.

A substrate holder 8 for holding the substrate W is provided in the vacuum container 2. As in this example, a bias voltage may be applied to the substrate holder 8 from the bias power supply 9. The bias voltage is, for example, a negative DC voltage, a negative bias voltage, or the like, but is not limited thereto. With such a bias voltage, for example, the energy when the cations in the plasma P are incident on the substrate W can be controlled to control the crystallinity of the film formed on the surface of the substrate W. .. A heater (not shown) for heating the substrate W may be provided in the substrate holder 8.

The antenna 3 is arranged above the substrate W in the vacuum vessel 2 along the surface of the substrate W (for example, substantially parallel to the surface of the substrate W). The number of antennas 3 is not particularly limited, and may be one, or a plurality of antennas 3 may be arranged in parallel with each other.

As shown in FIG. 2, the vicinity of both ends of the antenna 3 penetrates a pair of side walls 2a and 2b of the vacuum vessel 2 facing each other. Insulating members 11 are provided at portions that allow both ends of the antenna 3 to penetrate the outside of the vacuum vessel 2. Both ends of the antenna 3 penetrate each of the insulating members 11, and the penetrating portions are vacuum-sealed by, for example, packing. The antenna 3 is supported via the insulating member 11 in a state of being electrically insulated from the side walls 2a and 2b of the vacuum vessel 2 facing each other. The material of the insulating member 11 is, for example, ceramics such as alumina, quartz, or engineering plastics such as polyphenylene sulfide (PPS) and polyetheretherketone (PEEK).

The material of each antenna 3 is, for example, copper, aluminum, alloys thereof, stainless steel, and the like, but the material is not limited thereto. It is also possible to make the antenna 3 hollow and allow a refrigerant such as cooling water to flow through the antenna 3 to cool the antenna 3.

Further, in the antenna 3, a portion of the antenna 3 located inside the vacuum container 2 is covered with a straight tubular insulating cover 10. Both ends of the insulating cover 10 are supported by the insulating member 11. The material of the insulating cover 10 is, for example, quartz, alumina, fluororesin, silicon nitride, silicon carbide, silicon, or the like.

By providing the insulating cover 10, it is possible to suppress the incident of charged particles in the plasma P on the antenna 3, so that the increase in plasma potential due to the incident of charged particles (mainly electrons) on the antenna 3 is suppressed. At the same time, it is possible to prevent the antenna 3 from being sputtered by charged particles (mainly ions) and causing metal contamination (metal contamination) on the plasma P and the substrate W.

As shown in FIG. 1, each antenna 3 has a feeding end portion 3a to which a high frequency is supplied in the antenna direction (longitudinal direction X) and a grounded end portion 3b that is grounded. Specifically, at both ends of each antenna 3 in the longitudinal direction X, the portion extending outward from one side wall 2a or 2b becomes the feeding end portion 3a, and the portion extending outward from the other side wall 2a or 2b becomes. It becomes the grounding end portion 3b.

Here, a high frequency is applied from the high frequency power supply 4 to the feeding end 3a of each antenna 3 via the matching unit 41. The high frequency frequency is, for example, 13.56 MHz, which is common, but is not limited to this.

Further, as shown in FIGS. 1 and 2, the plasma processing apparatus 100 is placed on a wall 2c (hereinafter, also referred to as an upper wall 2c) opposite to the substrate W with respect to the antenna 3 in the vacuum vessel 2. A gas supply port 2x for supplying a film-forming gas is provided in the vacuum vessel 2.

The plasma processing apparatus 100 of the present embodiment is particularly useful when forming a film on the substrate W using a plurality of types of film forming gases, and vacuums the plurality of types of film forming gases separately (independently). As shown in FIG. 1, a plurality of gas supply ports 2x (1) and 2x (2) are provided so that the gas can be supplied into the container 2.

Hereinafter, a case where two types of film forming gases having different bond strengths are used will be described.
More specifically, one film-forming gas (hereinafter, also referred to as a first gas) is a gas having a stronger bond than the other film-forming gas (hereinafter, also referred to as a second gas), and is a first gas. Examples of the _{gas include N 2} , O ₂ , HF _X , SiF _X , SF _X , CF _{X, and the} like, and examples of the second gas include SiH ₄ , H ₂ , NH ₃ , N ₂ O, and NF. ₃ or Ar and the like can be mentioned. Note that x is a natural number of 1 or more.

Here, since the plasma processing apparatus 100 of the present embodiment is characterized by the introduction of the first gas, the configuration for introducing the second gas will be described first, and then the configuration for introducing the first gas will be described. explain.

As shown in FIG. 2, the plasma processing apparatus 100 includes a second gas introduction member 5 that introduces the second gas supplied from the gas supply port 2x (2) for the second gas into the inductively coupled plasma P. There is.

More specifically, in the vacuum vessel 2 of the present embodiment, a second gas space 5S that communicates with the gas supply port 2x (2) for the second gas and is filled with the second gas is provided. The second gas filled in the second gas space 5S is introduced into the inductively coupled plasma P via the second gas introduction member 5.

The second gas introduction member 5 is arranged in the vacuum vessel 2 and separates the plasma generation space PS in which the inductively coupled plasma P is generated from the above-mentioned second gas space 5S. As the second gas introduction member 5, for example, a metal member integrally formed with the vacuum vessel 2 can be mentioned. However, the second gas introduction member 5 may be a separate body from the vacuum container 2, and the material is not limited to metal.

Specifically, the second gas introduction member 5 opens toward the second gas space 5S and introduces the second gas into the second gas introduction port 5a, and opens toward the plasma generation space PS to derive the second gas. It has a second gas outlet 5b and a second gas flow path 5c that communicates with the second gas introduction port 5a and the second gas outlet 5b.

The second gas introduction member 5 of the present embodiment is a long, for example, flat plate member, and is arranged along the antenna 3, that is, substantially parallel to the longitudinal direction of the antenna 3.

A plurality of second gas introduction ports 5a are formed on the upper surface of the second gas introduction member 5, and a plurality of second gas outlets 5b are formed on the lower surface thereof corresponding to the second gas introduction ports 5a. Has been done. That is, the second gas introduction member 5 of the present embodiment has a plurality of second gas flow paths 5c, and these second gas flow paths 5c are formed in the same shape as each other in this embodiment. ..

Specifically, the second gas flow path 5c has a cross-sectional shape that extends from the second gas introduction port 5a to the second gas outlet 5b, and has a diameter of, for example, 0.1 mm or more. It has a columnar shape of 5 mm or less. The flow path cross section in the present specification is a cross section orthogonal to the flow direction of the flow path, that is, a cross section of the flow path.

Therefore, as shown in FIG. 3, the plasma processing apparatus 100 of the present embodiment introduces the first gas supplied from the gas supply port 2x (1) for the first gas into the induction-coupled plasma P. The introduction member 7 is further provided with a power supply V that applies a negative voltage to the first gas introduction member 7, and the first gas introduction member 7 is subjected to a negative voltage from the above-mentioned power supply V. It is configured to function as a hollow cathode that traps electrons.

More specifically, in the vacuum vessel 2 of the present embodiment, a first gas space 7S that communicates with the gas supply port 2x (1) for the first gas and is filled with the first gas is provided. The first gas filled in the first gas space 7S is introduced into the inductively coupled plasma P via the first gas introduction member 7. Here, the gas supply port 2x (1) for the first gas is larger than the gas supply port 2x (2) for the second gas.

The first gas introduction member 7 is arranged in the vacuum vessel 2 and separates the plasma generation space PS in which the inductively coupled plasma P is generated from the above-mentioned first gas space 7S.

The first gas introduction member 7 is made of metal and is insulated from the vacuum container 2 via an insulating member Z.

Specifically, the first gas introduction member 7 opens toward the first gas space 7S and opens toward the first gas introduction port 7a into which the first gas is introduced, and opens toward the plasma generation space PS to derive the first gas. It has a first gas outlet 7b and a first gas flow path 7c communicating the first gas introduction port 7a and the first gas outlet 7b.

The first gas introduction member 7 of the present embodiment is a long, for example, flat plate member, and is arranged along the antenna 3, that is, substantially parallel to the longitudinal direction of the antenna 3. In this embodiment, the first gas introduction member 7 and the second gas introduction member 5 are alternately provided along the direction orthogonal to the longitudinal direction of the antenna 3 (see FIG. 1).

A plurality of first gas introduction ports 7a are formed on the upper surface of the first gas introduction member 7, and a plurality of first gas outlets 7b are formed on the lower surface thereof corresponding to the first gas introduction ports 7a. Has been done. That is, the first gas introduction member 7 of the present embodiment has a plurality of first gas flow paths 7c, and these first gas flow paths 7c are formed in the same shape as each other in this embodiment. ..

Here, the first gas outlet 7b is formed larger than the first gas introduction port 7a, and the first gas flow path 7c is the upstream flow path 7c1 connected to the first gas introduction port 7a. It is connected to the first gas outlet 7b and has a downstream flow path 7c2 having a cross section larger than that of the upstream flow path 7c1. That is, the first gas flow path 7c is formed with a recess (recess) that opens toward the antenna 3, and this recess serves as the downstream flow path 7c2.

The upstream side flow path 7c1 has a cross section of the flow path having an equal cross section from one end to the other end, and has, for example, a columnar shape having a diameter of 0.1 mm or more and 1.5 mm or less. The diameter dimension of the upstream side flow path 7c1 here is equal to the diameter dimension of the second gas flow path 5c described above.

In the downstream flow path 7c2, the flow path cross section has an equal cross section shape from one end to the other end, and one or both of the size and the flow path length of the flow path cross section are mean free path of electrons. It is preferably longer than the stroke. The mean free path of electrons is calculated based on the mean free path of the molecule of the first gas, the diameter of the molecule of the first gas, and the like.

The downstream flow path 7c2 of the present embodiment has, for example, a columnar shape having a diameter of 3 mm or more and 40 mm or less, and an axial length of, for example, 1 times or more and 1.5 times or less of the diameter. Then, when a negative voltage is applied to the first gas introduction member 7 from the power source V described above, the downstream flow path 7c2 functions as a hollow cathode that traps the electrons emitted from the inductively coupled plasma P. It will be demonstrated.

<Effect of this embodiment>
According to the plasma processing apparatus 100 of the present embodiment configured, the first gas introduction member 7, since confine electrons functions as a hollow cathode, thoroughly first gas strong example N ₂ or the like bonds The film can be formed after being disassembled.

Specifically, since the cross section of the downstream flow path 7c2 is larger than that of the upstream side flow path 7c1, electrons can be confined in the downstream side flow path 7c2 and pass through the downstream side flow path 7c2. At that time, the first gas can be sufficiently decomposed.

Further, since the first gas introducing member 7 and the second gas introducing member 5 are arranged alternately, a homogeneous film can be formed.

<Other modified embodiments>
The present invention is not limited to the above embodiment.

For example, in the above embodiment, the cross section of the downstream flow path 7c2 has an equal cross section from one end to the other end, but as shown in FIG. 4, one end (upstream side). ) To the other end (downstream side), the cross section of the flow path may become larger, or the first gas outlet 7b may be narrowed down by an orifice or the like, although not shown.

Further, in the above embodiment, the plurality of first gas flow paths 7c have the same shape as each other, but as shown in FIG. 5, for example, the cross section of the first gas flow path 7c at both ends in the longitudinal direction is centered. The flow path cross section, the flow path length, and the like of the plurality of first gas flow paths 7c may be different in size, such as making the section larger than the flow path cross section of the first gas flow path 7c.

Further, in the above-described embodiment, the first gas introduction member 7 and the second gas introduction member 5 are provided along the longitudinal direction of the antenna 3, but as shown in FIG. 6, the first gas introduction member 7 and the second gas introduction member 5 and the second gas introduction member 5 are provided. The second gas introduction member 5 may be provided along the direction orthogonal to the longitudinal direction of the antenna 3.

In the above embodiment, the film-forming gas is introduced from the upper wall 2c, but it may be introduced from the side walls 2a and b.

In the above embodiment, the entire first gas introduction member 7 has been described as being made of metal, but if at least the portion forming the downstream flow path 7c2 is made of metal, a negative voltage is applied to that portion. It is not necessary to make the whole metal because it can be used.

Further, in the above embodiment, the case where a plurality of types (for example, two types) of gas for film formation are independently introduced into the vacuum vessel 2 has been described. It may be introduced into the container 2. The plasma processing apparatus 100 in this case may not include the second gas introduction member 5.

Further, as the first gas flow path 7c, the cross section of the flow path from the first gas introduction port 7a to the first gas outlet 7b is an equal cross section, and the cross section of the flow path is the same as that of the downstream flow path 7c2 of the embodiment. It may be the size of. That is, the first gas flow path 7c does not necessarily have to be provided with a recessed portion as long as it has a flow path cross section having a size that functions as a hollow cathode.

In addition, the present invention is not limited to the above-described embodiment, and it goes without saying that various modifications can be made without departing from the spirit of the present invention.

100 ・ ・ ・ Plasma processing device W ・ ・ ・ Substrate P ・ ・ ・ Induction coupling plasma 2 ・ ・ ・ Vacuum container 3 ・ ・ ・ Antenna 2x ・ ・ ・ Gas supply port 5 ・ ・ ・ Second gas introduction member 5a ・ ・ ・2nd gas introduction port 5b ・ ・ ・ 2nd gas outlet 5c ・ ・ ・ 2nd gas flow path 5S ・ ・ ・ 2nd gas space PS ・ ・ ・ Plasma generation space 7 ・ ・ ・ 1st gas introduction member 7a ・ ・1st gas introduction port 7b ・ ・ ・ 1st gas outlet 7c ・ ・ ・ 1st gas flow path 7c1 ・ ・ ・ upstream side flow path 7c2 ・ ・ ・ downstream side flow path 7S ・ ・ ・ 1st gas space Z ・・ ・ Insulation member V ・ ・ ・ Power supply

Claims (6)

A plasma processing apparatus that generates inductively coupled plasma in the vacuum vessel by passing a high-frequency current through an antenna arranged in the vacuum vessel and processes the substrate using the inductively coupled plasma.
A first gas introduction member having a first gas flow path through which the first gas flows and introducing the first gas into the inductively coupled plasma.
A power supply that applies a negative voltage to the first gas introduction member is provided.
A plasma processing apparatus characterized in that the first gas introducing member functions as a hollow cathode that confine electrons in the first gas flow path by the negative voltage. The first gas introduction member
The inlet into which the first gas is introduced and
It is larger than the introduction port and has an outlet for leading out the first gas.
The first gas flow path
The upstream flow path connected to the introduction port and
The plasma processing apparatus according to claim 1, which has a flow path cross section larger than that of the upstream side flow path and has a downstream side flow path connected to the outlet. The plasma processing apparatus according to claim 2, wherein the downstream flow path has a cylindrical shape, a diameter of 3 mm or more and 40 mm or less, and an axial length of 1 time or more and 1.5 times or less of the diameter. It has a second gas flow path through which a second gas flows different from the first gas, and further includes a second gas introduction member for introducing the second gas into the inductively coupled plasma.
The plasma processing apparatus according to any one of claims 1 to 3, wherein the first gas is a gas having a stronger bond than the second gas. The first gas introduction member is a long one having a plurality of the first gas flow paths.
The second gas introduction member is a long one having a plurality of the second gas flow paths.
Claims that a plurality of the first gas introduction members and a plurality of the second gas introduction members are alternately provided along the longitudinal direction of the antenna or along the direction orthogonal to the longitudinal direction of the antenna. Item 4. The plasma processing apparatus according to item 4. Wherein the first _{gas, N 2, O 2, HF} X, SiF X, at least one of SF _X, or CF _X, the plasma processing apparatus according to any one of claims 1 to 5.

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