PLASMA PROCESSING APPARATUS

Disclosed is a plasma processing apparatus including: a processing container; and a partition plate made of an insulating material, having a plurality of openings, and configured to partition an inside of the processing container into a plasma generating chamber and a processing chamber. A first conductive member made of a conductive material is provided on a surface of the processing chamber side of the partition plate, and the first conductive member is applied with at least one of an AC voltage, and a DC voltage of a polarity that is opposite to a polarity of charged particles guided from the plasma generating chamber into the processing chamber through each of the openings.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese Patent Application No. 2015-139019 filed on Jul. 10, 2015 with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

Various aspects and exemplary embodiments of the present disclosure relate to a plasma processing apparatus.

BACKGROUND

In a conventional processing apparatus, a partition plate having a plurality of openings is provided in a processing container, so that the processing container is partitioned into a beam generating chamber and a processing chamber by the partition plate. When ions in plasma generated in the beam generating chamber pass through the plurality of openings, the partition plate donates electrons to the ions so that the ions are neutralized. When a processing gas is irradiated with particles obtained by the neutralization of the ions (hereinafter, referred to as “neutral particles”) in the processing chamber, the processing gas is excited, and active species produced from the processing gas fall onto a workpiece placed on a placing table in the processing chamber. Accordingly, a desired processing such as, for example, film formation or etching, is performed on the workpiece. As a processing apparatus for performing a processing using the neutral particles, a neutral particle beam processing apparatus has been known (see, e.g., Japanese Patent Laid-Open Publication No. 2002-289399).

In the neutral particle beam processing apparatus, among ions and electrons produced in the beam processing chamber, the electrons reach the partition plate first because of their faster moving speed. Then, the surface of the partition plate, which is made of a dielectric, is negatively charged, and a sheath occurs near the surface of the beam generating chamber side of the partition plate. Thus, the ions in the plasma are accelerated in a direction toward the partition plate, and some of the ions pass through the openings formed in the partition plate. When the ions pass through the openings of the partition plate, the ions are electrically neutralized by charge exchange with the electrons charged on the sidewall of the openings, and become neutral particles, which are then released into the processing chamber.

SUMMARY

In an aspect of the present disclosure, a plasma processing apparatus includes a processing container and a partition plate. The partition plate is made of an insulating material, has a plurality of openings, and partitions an inside of the processing container into a plasma generating chamber and a processing chamber. Further, a first conductive member made of a conductive material is provided on a surface of the processing chamber side of the partition plate. The first conductive member is applied with at least one of an AC voltage and a DC voltage of a polarity that is opposite to a polarity of charged particles guided from the plasma generating chamber into the processing chamber through each of the openings.

DETAILED DESCRIPTION

In the neutral particle beam processing apparatus described in Japanese Patent Laid-Open Publication No. 2002-289399, the ions in the plasma may be drawn by the sheath occurring near the surface of the beam generating chamber side of the partition plate, thereby colliding with the partition plate. When the ions collide with the partition plate, the surface of the partition plate is scraped, and thus, consumption of the partition plate may be accelerated.

In addition, when the ions collide with the partition plate, the surface of the partition plate is scraped, and thus, the material of the partition plate may be scattered as particles in the beam generating chamber. When the particles are scattered in the beam generating chamber, the scattered particles may pass through the openings of the partition plate, enter into the processing chamber, and adhere to the workpiece in the processing chamber. Thus, the workpiece may be contaminated by the particles.

In an aspect of the present disclosure, a plasma processing apparatus includes a processing container and a partition plate. The partition plate is made of an insulating material, has a plurality of openings, and partitions an inside of the processing container into a plasma generating chamber and a processing chamber. Further, a first conductive member made of a conductive material is provided on a surface of the processing chamber side of the partition plate. The first conductive member is applied with at least one of an AC voltage and a DC voltage of a polarity that is opposite to a polarity of charged particles guided from the plasma generating chamber into the processing chamber through each of the openings.

In an exemplary embodiment of the disclosed plasma processing apparatus, the first conductive member may be formed by coating the conductive material on the surface of the processing chamber side of the partition plate.

In an exemplary embodiment of the disclosed plasma processing apparatus, at least a part of an inner wall of each of the plurality of openings may be coated with the conductive material. The first conductive member may be conductive with the conductive material coated on the inner wall of each of the plurality of openings.

In an exemplary embodiment of the disclosed plasma processing apparatus, the first conductive member may be formed as a member separate from the partition plate, and attached to the surface of the processing chamber side of the partition plate.

In an exemplary embodiment of the disclosed plasma processing apparatus, a second conductive member made of a conductive material may be provided on the plasma generating chamber side of the partition plate, and the second conductive member may be connected to a reference potential of the processing container.

In an exemplary embodiment of the disclosed plasma processing apparatus, a second conductive member made of a conductive material may be provided on the plasma generating chamber side of the partition plate, and the second conductive member may be applied with a DC voltage of a polarity that is equal to a polarity of charged particles included in plasma generated in the plasma generating chamber, and guided into the processing chamber through each of the openings.

In an exemplary embodiment of the disclosed plasma processing apparatus, a magnitude of the DC voltage applied to the second conductive member may be substantially equal to a magnitude of a plasma potential of the plasma generated in the plasma generating chamber.

In an exemplary embodiment of the disclosed plasma processing apparatus, each of the plurality of openings may have an opening area at the plasma generating chamber side wider than an opening area at the plasma generating chamber side.

According to various aspects and exemplary embodiments, the consumption of the partition plate and the contamination of the workpiece may be suppressed.

Hereinafter, exemplary embodiments of the plasma processing apparatus disclosed herein will be described in detail with reference to the drawings. Further, the present disclosure is not limited to the exemplary embodiments disclosed herein. In addition, respective embodiments may be appropriately combined within a range that does not contradict the processing contents.

Exemplary Embodiment

Plasma Processing Apparatus10

FIG. 1is a cross-sectional view illustrating an exemplary plasma processing apparatus10. The plasma processing apparatus10illustrated inFIG. 1includes a processing container12. The processing container12is a substantially cylindrical container that extends in a direction where an axis Z illustrated inFIG. 1extends (hereinafter, referred to as an “axis Z direction”), and defines a space therein. The space is partitioned into a plasma generating chamber S1and a processing chamber S2provided below the plasma generating chamber S1, in the axis Z direction, by a partition plate40(to be described later).

The processing chamber12includes, for example, a first sidewall12a, a second sidewall12b, a bottom12c, and a cover12d. The first sidewall12ahas a substantially cylindrical shape extending in the axis Z direction, and defines the plasma generating chamber S1.

Gas lines P11and P12are formed in the first sidewall12a. The gas line P11extends from the outer surface of the first sidewall12aand is connected to the gas line P12. The gas line P12extends substantially annularly around the axis Z in the first sidewall12a. The gas line P12is connected to a plurality of injection ports H1to inject a gas into the plasma generating chamber S1.

Further, the gas line P11is connected with a gas source G1via a valve V11, a mass flow controller M1, and a valve V12. The gas source G1supplies a gas for plasma excitation. In the present exemplary embodiment, the gas supplied from the gas source G1is, for example, Ar gas, O2gas, or H2gas. The gas source G1, the valve V11, the mass flow controller M1, the valve V12, the gas line P11, the gas line P12, and the injection ports H1constitute a plasma excitation gas supply system. The plasma excitation gas supply system controls the flow rate of the gas supplied from the gas source G1by the mass flow controller M1, and supplies the flow rate-controlled gas into the plasma generating chamber S1.

Further, the cover12dis provided on the upper end of the first sidewall12a. The cover12dis formed with an opening, and an antenna14is provided in the opening. Further, a dielectric window16is formed just below the antenna14to seal the plasma generating chamber S1.

As the antenna14radiates microwaves into the plasma generating chamber S1, plasma of the gas supplied from the plasma excitation gas supply system is generated in the plasma generating chamber S1. In the present exemplary embodiment, the antenna14is, for example, a radial line slot antenna. The antenna14includes a dielectric plate18, and a slot plate20. The dielectric plate18shortens the wavelength of the microwaves, and has substantially a disc shape. The dielectric plate18is made of a dielectric such as, for example, quartz or alumina. The dielectric plate18is interposed between the top surface of the slot plate20and the metal bottom surface of a cooling jacket22.

The slot plate20is a substantially disc-shaped metal plate including a plurality of slot pairs formed therein.FIG. 2is a plan view illustrating an example of the slot plate20. The slot plate20includes a plurality of slot pairs20aformed therein. The plurality of slot pairs20aare arranged in concentric circles which are radially spaced away from each other, in a circumferential direction in the plane of the slot plate20. Each slot pair20aincludes two slot holes20band20c, which are elongated holes extending in a direction intersecting with or orthogonal to each other.

The plasma processing apparatus10further includes a coaxial waveguide24, a microwave generator26, a tuner28, a waveguide30, and a mode converter32. The microwave generator26generates microwaves having a frequency of, for example, 2.45 GHz. The microwave generator26is connected to the upper portion of the coaxial waveguide24via the tuner28, the waveguide30, and the mode converter32. The coaxial waveguide24extends along an axis Z which is a central axis thereof. The coaxial waveguide24includes an outer conductor24aand an inner conductor24b. The outer conductor24ahas a cylindrical shape that extends around the axis Z. The lower end of the outer conductor24ais electrically connected to the upper portion of the cooling jacket22having a conductive surface. The inner conductor24bhas a substantially cylindrical shape that extends along the axis Z, and is provided inside the outer conductor24a. The lower end of the inner conductor24bis connected to the slot plate20of the antenna14.

The microwaves generated from the microwave generator26are propagated to the dielectric plate18through the coaxial waveguide24. The microwaves propagated to the dielectric plate18are propagated to the dielectric window16primarily through slot holes20b,20cof the slot plate20.

The dielectric window16has substantially a disc shape, and is made of, for example, quartz or alumina. The dielectric window16is formed just below the slot plate20. The dielectric window16radiates the microwaves, which has been propagated from the antenna14, to the plasma generating chamber S1. Accordingly, an electric field is generated just below the dielectric window16by the microwaves, and plasma is generated in the plasma generating chamber S1.

Below the first sidewall12a, the second sidewall12bextends continuously with the first sidewall12a. The second sidewall12bhas a substantially cylindrical shape extending in the axis Z direction, and defines the processing chamber S2. A placing table36is provided in the processing chamber S2to place a processing target substrate W thereon. In the present exemplary embodiment, the placing table36is supported by a support38that extends from the bottom12cof the processing container12in the axis Z direction. In the present exemplary embodiment, the placing table36includes a temperature control mechanism such as a heater or a cooler, or an attracting and holding mechanism such as an electrostatic chuck.

Further, in the processing chamber S2, a gas line P21extends annularly around the axis Z above the placing table36. The gas line P21is formed with a plurality of injection ports H2to inject a gas into the processing chamber S2. The gas line P21is connected with a gas line P22that extends to the outside of the processing container12through the second sidewall12b. The gas line P22is connected with a gas source G2via a valve V21, a mass flow controller M2, and a valve V22. The gas source G2is a gas source of the processing gas used for the processing of the substrate W such as, for example, film formation or etching. As a processing gas for a film formation processing, a precursor gas such as, for example, dimethoxytetramethyldisiloxane (DMOTMDS) is used. The gas source G2, the valve V21, the mass flow controller M2, the valve V22, the gas line P21, the gas line P22, and the injection ports H2constitute a processing gas supply system. The processing gas supply system controls the flow rate of the gas supplied from the gas source G2by the mass flow controller M2, and supplies the flow rate-controlled gas into the processing chamber S2.

In the plasma processing apparatus10of the present exemplary embodiment, a partition plate40is provided between the plasma generating chamber S1and the processing chamber S2. The plasma generating chamber S1and the processing chamber S2are separated from each other by the partition plate40. The partition plate40is a substantially disc-shaped member, and supported by the first sidewall12a. The partition plate40has a plurality of openings40hthat communicate the plasma generating chamber S1and the processing chamber S2.

The partition plate40has a shielding property against ultraviolet rays generated in the plasma generating chamber S1. That is, the partition plate40may be made of a material that does not transmit ultraviolet rays. Further, in the present exemplary embodiment, when charged particles in the plasma generated in the plasma generating chamber S1pass through the openings40hwhile colliding with the inner walls defining the openings40h, the partition plate40performs a charge exchange with the charged particles. Therefore, the partition plate40neutralizes the charged particles that pass through the openings, and releases the neutralized particles, that is, the neutral particles to the processing chamber S2. In the present exemplary embodiment, the charged particles are, for example, positively charged ions. Further, in the present exemplary embodiment, the partition plate40is made of an insulating material such as, for example, quartz or alumina.

In the present exemplary embodiment, the surface of the processing chamber S2side of the partition plate40is coated with a conductive member40amade of a conductive material such as, for example, a metal. The conductive member40ais connected with a voltage applying unit13a. The voltage applying unit13aapplies a DC voltage of a polarity that is opposite to the charge of the charged particles guided from the plasma generating chamber S1into the processing chamber S2through the openings40hof the partition plate40, to the conductive member40a. In the present exemplary embodiment, the charged particles guided from the plasma generating chamber S1into the processing chamber S2through the openings40hof the partition plate40, are positively charged ions. Thus, the voltage applying unit13aapplies a negative DC voltage to the conductive member40a. Further, the voltage applying unit13amay apply an AC voltage to the conductive member40a, or may apply square waves that alternately output a negative DC voltage of a predetermined magnitude and a negative DC voltage of a predetermined magnitude stepwise, to the conductive member40a.

In the present exemplary embodiment, the ions in the plasma generated in the plasma generating chamber S1are accelerated by the negative DC voltage applied to the conductive member40awhen passing though the openings40hof the partition plate40. Then, the neutral particles electrically neutralized by the contact with the inner wall of the openings40h, are injected into the processing chamber S2at a high speed.

The bottom12cof the processing container12is connected to an exhaust pipe48. The exhaust pipe48is connected with a pressure adjustor50and a vacuum pump52. The pressure adjustor50and the vacuum pump52constitute an exhaust device. The plasma processing apparatus10may set the pressure of the plasma generating chamber S1and the processing chamber S2to an arbitrary pressure by adjusting the flow rate of the gas for plasma excitation by the mass flow controller M1, adjusting the flow rate of the processing gas by the mass flow controller M2, and adjusting the exhaust amount from the processing chamber S2by the pressure adjustor50.

The plasma processing apparatus10further includes a controller Cnt. The controller Cnt is, for example, a computer including a storage device in which a program is stored. The controller Cnt reads a program based on a recipe stored in the storage device, and controls respective parts of the plasma processing apparatus10in accordance with the read program. For example, the controller Cnt may control the supply of the gas for plasma excitation from the gas source G1and the stop of the supply by transmitting a control signal to the valves V11and V12, and control the flow rate of the gas for plasma excitation by transmitting a control signal to the mass flow controller M1. Further, the controller Cnt may control the supply of the processing gas from the gas source G2and the stop of the supply by transmitting a control signal to the valves V21and V22, and control the flow rate of the processing gas by transmitting a control signal to the mass flow controller M2. Further, the controller Cnt may control the exhaust amount by transmitting a control signal to the pressure adjustor50. Further, the controller Cnt may control the power of the microwaves by transmitting a control signal to the microwave generator26. Further, the controller Cnt may control the supply of the voltage to be applied to the conductive member40aof the partition plate40and the stop of the supply, furthermore, the magnitude of the voltage to be applied to the conductive member40aby transmitting a control signal to the voltage applying unit13a. Furthermore, the controller Cnt may control the temperature of the placing table36by transmitting a control signal to the temperature control mechanism of the placing table36.

For example, the controller Cnt supplies the gas for plasma excitation from the respective injection ports H1into the plasma generating chamber S1, and supplies the processing gas from the respective injection ports H2into the processing chamber S1, in a state where the substrate W is placed on the placing table36. Then, the controller Cnt radiates microwaves from the antenna14to generate plasma in the plasma generating chamber S1. Then, the controller Cnt applies a predetermined voltage to the conductive member40aof the partition plate40to guide the ions included in the plasma generated in the plasma generating chamber S1to the openings40hof the partition plate40. Then, the particles neutralized by the contact with the inner wall of the openings40hof the partition plate40when passing through the openings40h, enter into the processing chamber S2at a high speed, thereby exciting the processing gas supplied into the processing chamber S2. The substrate W placed on the placing table36in the processing chamber S2is subjected to a predetermined processing such as, for example, film formation or etching by the processing gas excited by the neutral particles.

FIG. 3is an enlarged cross-sectional view illustrating an exemplary configuration of the partition plate40. In the present exemplary embodiment, the surface of the processing chamber S2side of the partition plate40is coated with a conductive member40amade of a conductive material such as, for example, a metal, for example, as illustrated inFIG. 3. The conductive member40ais applied with a DC voltage supplied from the voltage applying unit13a. Further, in the present exemplary embodiment, at least a part of the inner wall40bof each opening40hformed in the partition plate40, is coated with the conductive member40a, for example, as illustrated inFIG. 3. Therefore, the ions in the plasma generated in the plasma generating chamber S1are more effectively guided to the openings40hby the negative DC voltage applied from the voltage applying unit13ato the conductive member40a.

As such, the conductive member40aprovided on the surface of the processing chamber S2side of the partition plate40is applied with a DC voltage that is opposite to the polarity of the charged particles guided from the plasma generating chamber S1into the processing chamber S2. Therefore, the charged particles in the plasma generated in the plasma generating chamber S1is more efficiently guided into the openings40h. Thus, more neutral particles may be supplied to the processing chamber S2, and the amount of the charged particles colliding with the surface of the plasma generating chamber S1side of the partition plate40may be reduced. Accordingly, consumption of the partition plate40due to the collision of the charged particles may be suppressed. Further, generation of particles of the partition plate40due to the collision of the charged particles may be suppressed.

Further, the conductive member40ain the present exemplary embodiment is formed by coating a conductive material on the surface of the processing chamber S2side of the partition plate40, but the present disclosure is not limited thereto. For example, in another exemplary embodiment, the conductive member40amay be formed of a conductive material such as, for example, a metal, as a separate member from the partition plate40, and may be attached to the surface of the processing chamber S2side of the partition plate40.

As such, an exemplary embodiment of the plasma processing apparatus10has been described. As described above, the plasma processing apparatus10of the present exemplary embodiment may suppress consumption of the partition plate40and contamination of the processing target substrate W.

Next, a modification of the partition plate40will be described.FIG. 4is an enlarged cross-sectional view illustrating an example of the partition plate40in Modification 1. In the partition plate40in the present modification, the surface of the plasma generating chamber S1side of the partition plate40is further coated by a conductive member40cmade of a conductive material such as, for example, a metal. The conductive member40cis connected with a voltage applying unit13b. The voltage applying unit13bapplies a DC voltage of a polarity that is equal to the polarity of the charged particles (e.g., ions) guided from the plasma generating chamber S1to the processing chamber S2(e.g., a positive DC voltage), to the conductive member40c.

As such, in the partition plate40of the present modification, the conductive member40ccoated on the plasma generating chamber S1side is applied with a DC voltage of a polarity that is equal to the polarity of the charged particles guided from the plasma generating chamber S1to the processing chamber S2. Thus, the amount of the charged particles colliding with the surface of the plasma generating chamber S1of the partition plate40may be further reduced. Accordingly, consumption of the partition plate40due to the collision of the charged particles or generation of particles may be further suppressed.

Further, the magnitude of the DC voltage applied to the conductive member40cby the voltage applying unit13bmay be substantially equal to the magnitude of the plasma potential of the plasma generated in the plasma generating chamber S1. Further, in another example, the conductive member40cmay be connected to a reference potential (ground) of the plasma processing apparatus10instead of the voltage applying unit13b. Even in this case, since the surface of the plasma generating chamber S1of the partition plate40is suppressed from being charged with a charge of a polarity that is opposite to the charge of the charged particles guided from the plasma generating chamber S1to the processing chamber S2, the amount of the charged particles colliding with the surface of the plasma generating chamber S1of the partition plate40may be further reduced.

FIG. 5is an enlarged cross-sectional view illustrating an example of the partition plate40in Modification 2. In the partition plate40of the present modification, a tapered surface40dis formed on the plasma generating chamber S1of each opening40h. Thus, in each opening40h, the opening area of the plasma generating chamber S1side is wider than the opening area of the processing chamber S2side. The illustration of the surface of the plasma generating chamber S1side of the partition plate40may be found, for example, inFIG. 6.FIG. 6is a plan view illustrating an example of the partition plate40in Modification 2.

Here, as the opening area of each opening40his wider, the ions in the plasma of the plasma generating chamber S1may be efficiently guided into the opening40h. However, as the opening area of each opening40his wider, the mechanical strength of the partition plate40is reduced. Thus, as for each opening40h, in the case where the opening area of the plasma generating chamber S1side is equal to the opening area of the processing chamber S2side, the opening area of the plasma generating chamber S1side cannot be set to be so wide in order to maintain the mechanical strength of the partition plate40to some extent.

In contrast, in the partition plate40of Modification 2 illustrated inFIGS. 5 and 6, a tapered surface40dis formed on the plasma generating chamber S1of each opening40h. Accordingly, the opening area of the plasma generating chamber S1side may be set to be wide while maintaining the mechanical strength of the partition plate40to some extent. Therefore, the charged particles in the plasma generated in the plasma generating chamber S1is more efficiently guided into the openings40h.

FIG. 7is an enlarged cross-sectional view illustrating an example of the partition plate40in Modification 3. In the partition plate40of the present modification, a tapered surface40dis formed on the whole inner wall of each opening40h. Thus, in each opening40h, the opening area of the plasma generating chamber S1side is set to be wider than the opening area of the processing chamber S2side. Accordingly, in the partition plate40of Modification 3, the opening area of the plasma generating chamber S1side may be set to be wide while maintaining the mechanical strength of the partition plate40to some extent. Therefore, the charged particles in the plasma generated in the plasma generating chamber S1is more efficiently guided into the openings40h.

Thus, in each opening40h, when the opening area of the plasma generating chamber S1side is formed to be wider than the opening area of the processing chamber S2side, an inclined surface is not necessarily formed on the inner wall. For example, as in Modification 4 illustrated inFIG. 8, each opening40hmay be formed such that the opening area is narrower stepwise as it proceeds from the plasma generating chamber S1side to the processing chamber S2side.