PLASMA PROCESSING APPARATUS

A plasma processing apparatus includes a chamber, a microwave source, and a distributor. The chamber is configured to place a substrate therein and includes a plurality of radiation units that radiate microwaves, which are arranged while facing the substrate. The microwave source outputs microwaves. The distributor has one end connected to the microwave source, and the other end branched and connected to the plurality of radiation units, and distributes and transmits the microwaves output from the microwave source to the plurality of radiation units, in which when a wavelength of the microwaves is λ, a line length from the one end to the other end falls within a predetermined range beginning from n×λ/2 (n is a natural number).

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese Patent Application No. 2022-184635, filed on Nov. 18, 2022, with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a plasma processing apparatus.

BACKGROUND

Japanese Patent Laid-Open No. 2012-216745 discloses a plasma processing apparatus that includes: a processing container that accommodates a processing target; a stage disposed inside the processing container and having a placement surface on which the processing target is placed; a gas supply mechanism that supplies a processing gas into the processing container; and a microwave introduction device that generates microwaves for forming plasma of the processing gas within the processing container and introduces the microwaves into the processing container. The microwave introduction device includes: a conductive member disposed above the processing container and having a plurality of openings; and a plurality of microwave transmission windows which are fitted into the plurality of openings. The microwaves pass through the microwave transmission windows and are introduced into the processing container. The microwave transmission windows are disposed on one virtual plane parallel to the placement surface while being fitted into the openings, and include a first microwave transmission window, and second and third microwave transmission windows adjacent to the first microwave transmission window. The first to third microwave transmission windows are disposed such that a distance between the center point of the first microwave transmission window and the center point of the second microwave transmission window, and a distance between the center point of the first microwave transmission window and the center point of the third microwave transmission window are set to be equal or approximately equal to each other.

SUMMARY

According to an aspect of the present disclosure, a plasma processing apparatus includes a chamber, a microwave source, and a distributor. The chamber is configured to place a substrate therein, and includes a plurality of radiation units that radiate microwaves, which are arranged while facing the substrate. The microwave source outputs microwaves. The distributor has one end connected to the microwave source, and the other end branched and connected to the plurality of radiation units, and distributes and transmits the microwaves output from the microwave source to the plurality of radiation units, in which when a wavelength of the microwaves is λ, a line length from the one end to the other end falls within a predetermined range beginning from n×λ/2 (n is a natural number).

DETAILED DESCRIPTION

Hereinafter, embodiments of a plasma processing apparatus will be described in detail with reference to drawings. The disclosed plasma processing apparatus is not limited by the following embodiments.

In the related art, there has been a plasma processing apparatus in which radiation units that radiate microwaves are provided at a plurality of places of a chamber, and microwaves are radiated into the chamber from the radiation units to form plasma. In such a plasma processing apparatus, when microwave sources are provided for the radiation units, respectively, the number of microwave sources increases, resulting in an increase in cost. Therefore, a configuration may be considered in which microwaves are distributed from one microwave source to two or more radiation units.

However, when microwaves are distributed from a microwave source to two or more radiation units, the transmission line becomes longer due to a distributor that distributes the microwaves. For short-wavelength electromagnetic waves such as microwaves, in some cases, the length of the transmission line in the portion of the distributor that distributes the microwaves may also affect the impedance, thereby affecting impedance matching. For example, in some cases, impedance matching between the input side and the output side may not be achieved, and then reflection or loss of microwaves may occur. Therefore, there are expectations for a technique that may distribute microwaves while suppressing the influence of the portion of the distributor on the impedance.

First Embodiment

Apparatus Configuration

Hereinafter, an example of a plasma processing apparatus of the present disclosure will be described by using embodiments. First, a first embodiment will be described.FIG.1is a cross-sectional view schematically illustrating an example of a plasma processing apparatus100according to a first embodiment. The plasma processing apparatus100illustrated inFIG.1includes a processing container101, a stage102, a gas supply mechanism103, an exhaust device104, a microwave introduction device105, and a control unit200. In the embodiment, the plasma processing apparatus100corresponds to the plasma processing apparatus of the present disclosure.

The processing container101accommodates a substrate W such as a semiconductor wafer. The stage102is provided inside the processing container101. The substrate W is placed on the stage102. The gas supply mechanism103supplies various gases into the processing container101. The exhaust device104exhausts gases within the processing container101. The microwave introduction device105generates microwaves and outputs the generated microwaves. The control unit200controls the operation of each unit of the plasma processing apparatus100. In the embodiment, the microwave introduction device105corresponds to a microwave source of the present disclosure.

The processing container101is made of, for example, a metal material such as aluminum or an alloy thereof, and is formed into a substantially cylindrical shape. The processing container101has a plate-shaped ceiling wall111and a bottom wall113and a side wall112connecting the ceiling wall111to the bottom wall113. The inner wall of the processing container101is coated with, for example, yttria (Y2O3) so that a protective film is formed. The side wall112has a loading/unloading port114through which the substrate W is loaded or unloaded to/from a transfer chamber (not illustrated) adjacent to the processing container101. The loading/unloading port114is opened/closed by a gate valve115.

The stage102is formed into a disk shape. The stage102is made of a dielectric. For example, the stage102is made of aluminum whose surface is anodized or a ceramic material, for example, aluminum nitride (AlN). The substrate W is placed on the top surface of the stage102. The substrate W is placed such that its center is aligned with the center position of the stage102. The stage102is supported by a cylindrical support member120, which is made of ceramic such as AlN and extends upwards from the center of the bottom wall113of the processing container101, and a base member121. A guide ring181for guiding the substrate W is provided at the outer edge of the stage102. A lifting pin (not illustrated) for raising and lowering the substrate W is provided within the stage102such that the lifting pin may protrude and retract from the upper surface of the stage102.

Further, a resistance heating-type heater182is embedded in the stage102. When power is supplied to the heater182from a heater power source183, the heater182heats the substrate W placed on the stage102. A thermocouple (not illustrated) is inserted into the stage102, and the heating temperature of the substrate W may be controlled on the basis of a signal from the thermocouple. Furthermore, an electrode184having substantially the same size as the substrate W is buried above the heater182in the stage102. A DC power supply unit122is electrically connected to the electrode184. The DC power supply unit122periodically applies a DC voltage to the electrode184in the stage102. For example, the DC power supply unit122includes a DC power supply and a pulse unit. The DC voltage supplied by the DC power supply is turned ON/OFF by the pulse unit, so that the DC power supply unit122periodically applies the pulsed DC voltage to the electrode184.

The gas supply mechanism103includes gas introduction nozzles123and124, a gas supply pipe125, and a gas supply unit127. The gas introduction nozzle123is provided in the ceiling wall111. In the first embodiment, the gas introduction nozzle123is provided at a position through which the central axis of the stage102passes. The center of the substrate W placed on the stage102is aligned with the center position of the stage102. Thus, the gas introduction nozzle123is located above the center of the substrate W. The gas introduction nozzle124is provided in the side wall112of the processing container101. The gas supply unit127is connected to the gas introduction nozzles123and124through the gas supply pipe125. The gas supply unit127has supply sources of various gases. Further, the gas supply unit127includes opening/closing valves that start and stop the supply of various gases, or flow rate regulators that adjust the flow rates of gases. The gas supply unit127supplies various gases, such as a processing gas to be used for plasma processing. The arrangement of the gas introduction nozzles123and124is merely an example, and the present disclosure is not limited to this. For example, a plurality of gas introduction nozzles123may be provided so as to surround the center of the ceiling wall111.

An opening is formed in the bottom wall113, and the exhaust device104is provided through an exhaust pipe116connected to the opening. The exhaust device104includes a vacuum pump and a pressure control valve. The gas within the processing container101is exhausted through the exhaust pipe116by the vacuum pump of the exhaust device104. The pressure inside the processing container101is controlled by the pressure control valve of the exhaust device104.

The microwave introduction device105is provided above the processing container101. The microwave introduction device105introduces electromagnetic waves (microwaves) into the processing container101so as to generate plasma.

FIG.2is a view schematically illustrating an example of the configuration of the microwave introduction device105according to the first embodiment. The microwave introduction device105includes a microwave output unit130and a microwave radiation unit140.

The microwave output unit130includes a microwave power source131, a microwave oscillator132, an amplifier133, and a distributor134. The microwave oscillator132is a solid state oscillator, and oscillates microwaves at, for example, 860 MHz (e.g., PLL oscillation). The frequency of microwaves is not limited to 860 MHZ, and those falling within a range of 700 MHz to 10 GHz, such as 2.45 GHZ, 8.35 GHz, 5.8 GHz, and 1.98 GHz, may be used. The amplifier133amplifies the microwaves oscillated by the microwave oscillator132. The distributor134distributes the microwaves amplified by the amplifier133to a plurality of paths. The distributor134distributes the microwaves while matching the impedance on the input side to the impedance on the output side.

The microwave radiation unit140includes a plurality of microwave transmission modules141. The microwaves distributed by the distributor134are input to each of the microwave transmission modules141. The configurations of the microwave transmission modules141are all the same configurations. Each microwave transmission module141amplifies and radiates (outputs) the distributed microwaves. In the embodiment, the microwave transmission module141corresponds to a microwave transmitter of the present disclosure.

Each microwave transmission module141includes an amplification section142that mainly amplifies and outputs distributed microwaves, and a microwave radiation mechanism143that transmits the microwaves output from the amplification section142while performing matching with the load side impedance.

The amplification section142includes a phase shifter145, a variable gain amplifier146, a main amplifier147, and an isolator148. The phase shifter145changes the phase of microwaves to change the radiation characteristics of the microwaves. The variable gain amplifier146adjusts the power level of the microwaves to be input to the main amplifier147. The main amplifier147is configured as a solid state amplifier. The isolator148separates the reflected microwaves which are reflected from the microwave radiation mechanism143side and are directed toward the main amplifier147. When the radiation characteristics of the microwaves are not adjusted, the phase shifter145may not be provided.

FIG.3is a view schematically illustrating an example of the microwave radiation mechanism143according to the first embodiment. The microwave radiation mechanism143is configured as a slug tuner. In the embodiment, the microwave radiation mechanism143corresponds to a matching unit of the present disclosure. The microwave radiation mechanism143has a cylindrical outer conductor152and a tubular inner conductor153coaxially provided within the outer conductor152.

A space between the outer conductor152and the inner conductor153functions as a microwave transmission path. An impedance converter156is provided at one ends of the outer conductor152and the inner conductor153. The impedance converter156is made of a dielectric. Examples of the dielectric may include quartz, ceramic such as alumina (Al2O3), and resins such as polytetrafluoroethylene and polyimide. Two slugs154aand154bare provided between the outer conductor152and the inner conductor153. The slugs154aand154bare made of a dielectric material such as ceramic and are formed into plate-like ring shapes. The slugs154aand154bare disposed between the outer conductor152and the inner conductor153in a state where the inner conductor153passes through the respective central holes of the slugs154aand154b.Each of the slugs154aand154bis movable along the inner conductor153by a driving mechanism (not illustrated).

The microwave radiation mechanism143has a power feeding section155. The power feeding section155is provided on the other end side of the outer conductor152. The power feeding section155outputs the microwaves output from the amplification section142, to the microwave transmission path. The microwave radiation mechanism143outputs the microwaves from the impedance converter156, via the microwave transmission path. The microwave radiation mechanism143performs impedance matching between the input side and the output side by moving the two slugs154aand154b.The microwave radiation mechanism143may have another configuration as long as impedance matching may be performed.

FIG.4is a top view illustrating an example of a schematic configuration of the ceiling wall111of the processing container101according to the first embodiment. The ceiling wall111of the processing container101is formed into a disk shape. In the processing container101, a plurality of radiation units160that radiate microwaves is disposed while facing the substrate W. For example, the gas introduction nozzle123is provided at the center position of the disk shape of the ceiling wall111. The ceiling wall111is provided with the radiation units160which have different diameters from the center, are spaced apart from each other in the circumferential direction, and radiate microwaves. In the embodiment, the ceiling wall111is provided with radiation units160ato160cwhich have three diameters from the center side of the ceiling wall111.

The radiation units160ato160care disposed on concentric circles from the center of the ceiling wall111, respectively. In the embodiment, four radiation units160a,four radiation units160b,and four radiation units160care arranged. The radiation units160a(160band160c) are arranged at equal intervals in the circumferential direction on the circumference of each concentric circle. In the embodiment, the radiation units160a(160band160c) are arranged at angular intervals of 90 degrees with respect to the center of the ceiling wall111.

The plurality of microwave transmission modules141is provided in the microwave radiation unit140. Each microwave transmission module141is connected to the radiation units160via each distribution unit170. In the first embodiment, six microwave transmission modules141(141ato141f) are provided in the microwave radiation unit140. Each of the microwave transmission modules141ato141fis connected to two radiation units160via the distribution unit170(170ato170f).

FIG.4andFIG.5described above illustrate the connection relationship between the microwave transmission modules141ato141fand the radiation units160ato160c.FIG.5is a view illustrating the connection relationship between the microwave transmission modules141ato141fand the radiation units160ato160caccording to the first embodiment. InFIG.4andFIG.5, the microwave radiation mechanisms143of the microwave transmission modules141ato141fare illustrated as microwave radiation mechanisms143ato143f.In the illustration ofFIG.5, in order to clearly illustrate the connection relationship, the microwave radiation mechanisms143(143ato143f) and the distributors170(170ato170f), which are connected to the radiation units160ato160c,respectively, are divided into upper and lower parts.

The other end side of the distribution unit170, which is connected to the radiation units160, diverges into two by bifurcating once. One end of the distribution unit170is connected to the microwave radiation mechanism143of the microwave transmission module141, and the other ends as two branches are connected to two radiation units160. For example, one end of the distribution unit170ais connected to the microwave radiation mechanism143aof the microwave transmission module141a, and the other ends as two branches are connected to two circumferentially adjacent radiation units160a.One end of the distribution unit170bis connected to the microwave radiation mechanism143bof the microwave transmission module141b,and the other ends as two branches are connected to two remaining radiation units160a.One end of the distribution unit170cis connected to the microwave radiation mechanism143cof the microwave transmission module141c,and the other ends as two branches are connected to two circumferentially adjacent radiation units160b.One end of the distribution unit170dis connected to the microwave radiation mechanism143dof the microwave transmission module141d,and the other ends as two branches are connected to two remaining radiation units160b.One end of the distribution unit170eis connected to the microwave radiation mechanism143eof the microwave transmission module141e,and the other ends as two branches are connected to two circumferentially adjacent radiation units160c.One end of the distribution unit170fis connected to the microwave radiation mechanism143fof the microwave transmission module141f,and the other ends as two branches are connected to two remaining radiation units160c.In the illustration ofFIG.4andFIG.5, the branch portions of each of the distributors170ato170freaching the radiation units160have a curved shape in the circumferential direction, but may have a straight shape.

The distribution unit170distributes and transmits microwaves output from the microwave radiation mechanism143, to the plurality of radiation units160. For example, the distribution unit170adistributes and transmits microwaves output from the microwave radiation mechanism143a,to the two radiation units160a.The distribution unit170bdistributes and transmits microwaves output from the microwave radiation mechanism143b,to the two radiation units160a.The distribution unit170cdistributes and transmits microwaves output from the microwave radiation mechanism143c,to the two radiation units160b.The distribution unit170ddistributes and transmits microwaves output from the microwave radiation mechanisms143d,to the two radiation units160b.The distribution unit170edistributes and transmits microwaves output from the microwave radiation mechanism143e,to the two radiation units160c.The distribution unit170fdistributes and transmits microwaves output from the microwave radiation mechanism143f,to the two radiation units160c.

FIG.6is a view illustrating a schematic configuration of the distribution unit170according to the first embodiment. The distributors170ato170fhave the same configuration and the radiation units160ato160chave the same configuration. Hereinafter, the configurations of the distribution unit170aand the radiation unit160awill be described.

The distribution unit170ais configured as a coaxial line in which the periphery of an inner conductor171is covered by a dielectric172, and the periphery of the dielectric172is covered by an outer conductor173. One end of the distribution unit170ais connected to the impedance converter156of the microwave radiation mechanism143a,and the other end side is branched and each is connected to the radiation unit160a.

The radiation unit160includes a microwave transmission plate161, an antenna162, and a slow-wave material163.

The microwave transmission plate161is fitted into the ceiling wall111of the processing container101. The bottom surface of the microwave transmission plate161is exposed to the internal space of the processing container101. The antenna162has a disk shape and is disposed on the top surface of the microwave transmission plate161.

The slow-wave material163is disposed on the top surface of the antenna162. A conductor163ais provided while passing through the slow-wave material163. One end of the conductor163ais connected to the antenna162, and the other end of the conductor163ais connected to the other end of the inner conductor171of the distribution unit170a.The slow-wave material163is made of a dielectric. Examples of the dielectric may include quartz, ceramic such as alumina (Al2O3), and resins such as polytetrafluoroethylene and polyimide. The slow-wave material163may adjust the phase of microwaves depending on its thickness, and may maximize the radiation energy of microwaves. The microwave transmission plate161is also made of a dielectric, and has a shape that allows microwaves to be efficiently radiated in a TE mode. Then, the microwaves that have passed through the microwave transmission plate161are radiated into the space within the processing container101to generate plasma. As for the material for forming the slow-wave material163and the microwave transmission plate161, it is possible to use, for example, quartz or ceramic, fluorine-based resins such as polytetrafluoroethylene resin, and polyimide resins.

Meanwhile, when the distribution unit170distributes microwaves to two radiation units160as in the embodiment, the transmission line becomes longer due to the distribution unit170. For short-wavelength electromagnetic waves such as microwaves, in some cases, the length of the transmission line in the portion of the distribution unit170may also affect the impedance, thereby affecting impedance matching. For example, in some cases, impedance matching between the input side and the output side may not be achieved, and then reflection or loss of microwaves may occur.

Therefore, in the first embodiment, the distribution unit170is configured as follows.FIG.7is a view illustrating the characteristic impedance of the distribution unit170according to the first embodiment. The line length between the one end of the distribution unit170connected to the microwave radiation mechanism143and the other end connected to the radiation unit160is set as L. The line length L is the length along the center of the inner conductor171from one end to the other end. The characteristic impedance of the transmission line in the portion of the distribution unit170is set as Z0. The characteristic impedance of the transmission path after the distribution unit170is set as Zi. The characteristic impedance of the transmission path after the radiation unit160is set as ZR. The characteristic impedances Z0, ZR, and Zi have the relationship of the following equation (1):

Here, λ is the wavelength of microwaves.

In the equation (1), when the line length L=0, λ/2, λ, 3λ/2, . . . , that is, the line length L is an integer multiple of λ/2, Zi=ZR. That is, when the line length L is an integer multiple of λ/2, it is possible to distribute microwaves without affecting impedance.

For example, it is assumed that the frequency of microwaves is 860 MHz. When the dielectric172of the distribution unit170is made of Teflon (registered trademark), λ/2 becomes 120 mm. When the portion of the dielectric172of the distribution unit170is made of alumina, λ/2 becomes 56.3 mm. When the portion of the dielectric172of the distribution unit170is a vacuum space, λ/2 becomes 174 mm.

Here, a specific example of the line length L of the distribution unit170awill be described. The frequency of microwaves is assumed to be 860 MHZ. The dielectric172of the distribution unit170ais made of Teflon (registered trademark). In this case, λ/2 becomes 120 mm. Regarding the distribution unit170a,impedance matching states were theoretically obtained in cases where the line length L was set as 90 mm, 100 mm, 110 mm, and 120 mm.FIG.8is a smith chart illustrating the impedance matching states. InFIG.8, plotting is made for each of cases where the line length L is set as 90 mm, 100 mm, 110 mm, and 120 mm. Theoretically, the matching comes close to perfection (1.00) when the line length L of the distribution unit170ais 120 mm. However, in actuality, as illustrated inFIG.8, when the line length L of the distribution unit170ais 110 mm, the matching comes close to perfection, and the absolute value of the reflection coefficient Γ is 0.06. The reason for this is thought to be that the characteristic impedance is not constant at the branched portion or the curved portion of the distribution unit170a.Therefore, the distribution unit170ais configured such that the line length L falls within a predetermined range from n×λ/2 (n is a natural number) in consideration of the influence of the branched portion or the curved portion. The predetermined range is, for example, a range where the matching comes closer to perfection (1.00), than that when the line length L is set as n×λ/2. For example, in the configuration of the distribution unit170a,the line length L is 110 mm. The distributors170bto170fare also configured to have line lengths L falling within a predetermined range from n×λ/2. Accordingly, the distributors170ato170fmay distribute microwaves while the influence of the portions of the distributors170ato170fon the impedance is suppressed. Therefore, it is possible to suppress impedance matching from not being achieved due to the influence of the distributors170ato170f.

When the line length L of each of the distributors170ato170fis around n×λ/2, the matching comes close to perfection. Therefore, the predetermined range may be a range of ±λ/8, and the distributors170ato170fmay be configured to have line lengths L falling within n×λ/2±λ/8. Accordingly, the distributors170ato170fmay distribute microwaves while the influence of the portions of the distributors170ato170fon the impedance is suppressed.

The microwave radiation mechanisms143ato143fto which the distributors170ato170fare connected, respectively, are configured as slug tuners, and may perform matching adjustment. Therefore, in the configuration of the distributors170ato170f,the line length L may be set within a range where impedance matching may be performed by the microwave radiation mechanisms143ato143f,from n×λ/2. Accordingly, the distributors170ato170fmay distribute microwaves while the microwave radiation mechanisms143ato143fare performing matching adjustment to achieve the impedance matching.

Next, the operation of the plasma processing apparatus100will be described.

In loading the substrate W into the plasma processing apparatus100, the gate valve115is in an open state. The substrate W is loaded into the processing container101via the loading/unloading port114by a transport mechanism such as a transport arm, and is placed on the stage102. Under the control of the control unit200, the plasma processing apparatus100performs plasma processing on the substrate W placed on the stage102. For example, the control unit200controls the exhaust device104so as to exhaust gases within the processing container101to a predetermined degree of vacuum. The control unit200controls the gas supply unit127, so that a processing gas to be used for plasma processing is supplied into the processing container101from the gas supply unit127. Then, the control unit200controls the microwave introduction device105, so that microwaves are generated by the microwave introduction device105and are output from each microwave transmission module141. The microwaves output from each microwave transmission module141are radiated into the processing container101from the radiation units160via each distribution unit170. Accordingly, plasma is generated within the processing container101, and plasma processing is performed on the substrate W.

In the plasma processing apparatus100according to the first embodiment, each microwave transmission module141is connected to two radiation units160via the distribution unit170. Accordingly, in the plasma processing apparatus100according to the first embodiment, for example, the number of microwave transmission modules141may be reduced by half as compared to when the microwave transmission modules141are provided for the radiation units160, respectively.

In the plasma processing apparatus100according to the first embodiment, the ceiling wall111of the processing container101is provided with the radiation units160ato160cwhich have different diameters from the center, and are spaced apart from each other in the circumferential direction. Four radiation units160a,four radiation units160band four radiation units160care disposed on concentric circles from the center of the ceiling wall111, respectively. The microwave transmission module141ais connected to two circumferentially adjacent radiation units160avia the distribution unit170a.The microwave transmission module141bis connected to two remaining radiation units160avia the distribution unit170b.The microwave transmission module141cis connected to two circumferentially adjacent radiation units160bvia the distribution unit170c.The microwave transmission module141dis connected to two remaining radiation units160bvia the distribution unit170d.The microwave transmission module141eis connected to two circumferentially adjacent radiation units160cvia the distribution unit170e.The microwave transmission module141fis connected to two remaining radiation units160cvia the distribution unit170f.

The control unit200may individually control the power of microwaves output from the microwave transmission modules141ato141fby controlling the amplification sections142of the microwave transmission modules141ato141f.Accordingly, it is possible to control the power of microwaves radiated from each of the radiation units160ato160c,and to control the distribution of plasma generated within the processing container101. For example, it is possible to control the plasma density near the center of the ceiling wall111by controlling the power of microwaves output from the microwave transmission modules141aand141b.It is possible to control the plasma density in the annular portion surrounding the center of the ceiling wall111by controlling the power of microwaves output from the microwave transmission modules141cand141d.It is possible to control the plasma density in the peripheral portion of the ceiling wall111by controlling the power of microwaves output from the microwave transmission modules141eand141f.It is possible to control a deviation in the plasma distribution by changing the microwave power in the microwave transmission module141aand the microwave transmission module141b,in the microwave transmission module141cand the microwave transmission module141d,and in the microwave transmission module141eand the microwave transmission module141f.

Second Embodiment

Next, a second embodiment will be described. The configurations of the plasma processing apparatus100, the microwave introduction device105, and the microwave radiation mechanism143according to the second embodiment are the same as the configurations in the first embodiment illustrated inFIGS.1to3, and thus the descriptions thereof will be omitted.

FIG.9is a top view illustrating an example of a schematic configuration of the ceiling wall111of the processing container101according to the second embodiment. The ceiling wall111is provided with the radiation units160ato160cwhich have three diameters from the center side of the ceiling wall111. Four radiation units160a,four radiation units160band four radiation units160care arranged at equal intervals on concentric circles from the center of the ceiling wall111, respectively.

In the second embodiment, three microwave transmission modules141(141gto141i) are provided in the microwave radiation unit140. Each of the microwave transmission modules141gto141iis connected to four radiation units160via the distribution unit170(170gto170i).

FIG.9andFIG.10described above illustrate the connection relationship between the microwave transmission modules141gto141iand the radiation units160ato160c.FIG.10is a view illustrating the connection relationship between the microwave transmission modules141gto141iand the radiation units160ato160caccording to the second embodiment. InFIG.9andFIG.10, the microwave radiation mechanisms143of the microwave transmission modules141gto141iare illustrated as microwave radiation mechanisms143gto143i.In the illustration ofFIG.10, in order to clearly illustrate the connection relationship, the microwave radiation mechanisms143(143gto143i) and the distributors170(170gto170i), which are connected to the radiation units160ato160c,respectively, are divided into upper and lower parts.

The other end side of the distribution unit170, which is connected to the radiation units160, diverges into four by bifurcating twice. One end of the distribution unit170is connected to the microwave radiation mechanism143of the microwave transmission module141, and the other ends as four branches are connected to four radiation units160. For example, one end of the distribution unit170gis connected to the microwave radiation mechanism143gof the microwave transmission module141g, and the other ends as four branches are connected to four radiation units160a.One end of the distribution unit170his connected to the microwave radiation mechanism143hof the microwave transmission module141h,and the other ends as four branches are connected to four radiation units160b.One end of the distribution unit170iis connected to the microwave radiation mechanism143iof the microwave transmission module141i, and the other ends as four branches are connected to four radiation units160c.

The distribution unit170distributes and transmits microwaves output from the microwave radiation mechanism143, to the plurality of radiation units160. For example, the distribution unit170gdistributes and transmits microwaves output from the microwave radiation mechanism143g,to the four radiation units160a.The distribution unit170hdistributes and transmits microwaves output from the microwave radiation mechanism143h,to the four radiation units160b.The distribution unit170idistributes and transmits microwaves output from the microwave radiation mechanism143i,to the four radiation units160c.

FIG.11is a view illustrating a schematic configuration of the distribution unit170according to the second embodiment. The distributors170gto170ihave the same configuration and the radiation units160ato160chave the same configuration. Hereinafter, the configurations of the distribution unit170gand the radiation unit160awill be described.

One end of the distribution unit170gis connected to the impedance converter156of the microwave radiation mechanism143g,and the other end side is bifurcated twice and each is connected to the radiation unit160a.

On the distribution unit170g,a line length L is illustrated between one end connected to the microwave radiation mechanism143gand the other end connected to the radiation unit160a.The line length L is the length along the center of the inner conductor171from one end to the other end.

The distribution unit170gis configured such that the line length L falls within a predetermined range from n×λ/2 in consideration of the influence of the branched portion or the curved portion. The distributors170hand170iare also configured to have line lengths L falling within a predetermined range from n×λ/2. Accordingly, the distributors170gto170imay distribute microwaves while the influence of the portions of the distributors170gto170ion the impedance is suppressed. Therefore, it is possible to suppress the distributors170gto170ifrom affecting impedance matching and making it impossible to achieve the impedance matching.

When the line length L of each of the distributors170gto170iis around n×λ/2, the matching comes close to perfection. Therefore, the predetermined range may be a range of ±λ/8, and the distributors170gto170imay be configured to have line lengths L falling within n×λ/2±λ/8. In the configuration of the distributors170gto170i,the line length L may be set within a range where impedance matching may be performed by the microwave radiation mechanisms143gto143i,from n×λ/2. Accordingly, the distributors170gto170imay distribute microwaves while the influence of the portions of the distributors170gto170ion the impedance is suppressed.

Next, the operation of the plasma processing apparatus100will be described.

The substrate W as a processing target is loaded into the processing container101via the loading/unloading port114and is placed on the stage102. Under the control of the control unit200, the plasma processing apparatus100performs plasma processing on the substrate W placed on the stage102. For example, the control unit200controls the exhaust device104so as to exhaust gases within the processing container101to a predetermined degree of vacuum. The control unit200controls the gas supply unit127, so that a processing gas to be used for plasma processing is supplied into the processing container101from the gas supply unit127. Then, the control unit200controls the microwave introduction device105, so that microwaves are generated by the microwave introduction device105and are output from each microwave transmission module141. The microwaves output from each microwave transmission module141are radiated into the processing container101from the radiation units160via each distribution unit170. Accordingly, plasma is generated within the processing container101, and plasma processing is performed on the substrate W.

In the plasma processing apparatus100according to the second embodiment, each microwave transmission module141is connected to four radiation units160via the distribution unit170. Accordingly, in the plasma processing apparatus100according to the second embodiment, for example, the number of microwave transmission modules141may be reduced to ¼ as compared to when the microwave transmission modules141are provided for the radiation units160, respectively.

In the plasma processing apparatus100according to the second embodiment, the ceiling wall111of the processing container101is provided with the radiation units160ato160cwhich have different diameters from the center, and are spaced apart from each other in the circumferential direction. Four radiation units160a,four radiation units160b,and four radiation units160care disposed on concentric circles from the center of the ceiling wall111, respectively. The microwave transmission module141gis connected to four radiation units160avia the distribution unit170g.The microwave transmission module141his connected to four radiation units160bvia the distribution unit170h.The microwave transmission module141iis connected to four radiation units160cvia the distribution unit170i.

The control unit200may individually control the power of microwaves output from the microwave transmission modules141gto141iby controlling the amplification sections142of the microwave transmission modules141gto141i.Accordingly, it is possible to control the power of microwaves radiated from each of the radiation units160ato160c,and to control the distribution of plasma. For example, it is possible to control the plasma density near the center of the ceiling wall111by controlling the power of microwaves output from the microwave transmission module141g.It is possible to control the plasma density in the annular portion surrounding the center of the ceiling wall111by controlling the power of microwaves output from the microwave transmission module141h.It is possible to control the plasma density in the peripheral portion of the ceiling wall111by controlling the power of microwaves output from the microwave transmission module141i.

In the first and second embodiments described above, descriptions have been made using an example of a case where the microwave transmission module141is connected to two or four radiation units160via the distribution unit170. However, the disclosed technology is not limited to this. More radiation units160may be connected to the microwave transmission module141via the distribution unit170. When the number of times of bifurcating is increased by one at the other end side of the distribution unit170, the number of the radiation units160to be connected may be doubled. In this case as well, in the configuration of the distribution unit170, the line length L from one end connected to the microwave radiation mechanism143gto the other end connected to the radiation unit160may fall within a predetermined range from n×λ/2. Then, it is possible to distribute microwaves while suppressing the influence of the portion of the distribution unit170on the impedance.

In the first and second embodiments described above, descriptions have been made using an example of a case where the other end side of the distribution unit170diverges into two each time, and thus the number of the other ends is increased. However, the disclosed technology is not limited to this. The other end side of the distribution unit170may diverge into three or more each time. In this case, in the configuration of the distribution unit170, each line length L from one end connected to the microwave radiation mechanism143gto the other end connected to the radiation unit160may fall within a predetermined range from n×λ/2. Then, it is possible to distribute microwaves while suppressing the influence of the portion of the distribution unit170on the impedance.

In the first and second embodiments described above, descriptions have been made using an example of a case where the other end side of the distribution unit170diverges into two, and the transmission line is divided in a tree form. However, the disclosed technology is not limited to this. A ring-shaped transmission line that transmits microwaves may be formed in a part of the distribution unit170.FIGS.12and13are views illustrating an example of the distribution unit170having a ring-shaped transmission line according to the second embodiment.FIGS.12and13illustrate a case where ring-shaped transmission lines175are provided in the distributors170gto170iaccording to the second embodiment. In the illustration ofFIG.13, in order to clearly illustrate the connection relationship, the microwave radiation mechanisms143(143gto143i) and the distributors170(170gto170i), which are connected to the radiation units160ato160c,respectively, are divided into upper and lower parts. From one end of each of the distributors170gto170iconnected to the microwave radiation mechanisms143, two branches diverge once, and each is connected to the ring-shaped transmission line175. Then, four other ends of each of the distributors170gto170i,which diverge from the ring-shaped transmission line175, are connected to four radiation units160. Since the ring-shaped transmission line175is provided in the distribution unit170, the branched microwaves are transmitted to the ring-shaped transmission line175. Accordingly, even when a deviation occurs in the microwave power due to branching, the deviation in the microwave power may be suppressed through the ring-shaped transmission line175. Thus, the distribution unit170may transmit microwaves with equal power to the four radiation units160. In this case, in the configuration of the distribution unit170, each shortest line length L from one end connected to the microwave radiation mechanism143to the other end connected to the radiation unit160falls within a predetermined range from n×λ/2. Accordingly, it is possible to distribute microwaves while suppressing the influence of the portion of the distribution unit170on the impedance.

In the first and second embodiments described above, descriptions have been made using an example of a case where the distribution unit170is configured as a coaxial line. However, the disclosed technology is not limited to this. The distribution unit170may have any configuration as long as microwaves may be distributed and transmitted to the plurality of radiation units160. For example, the distribution unit170may be configured with a coaxial line and a strip line. The strip line may be manufactured using, for example, a printed circuit board. By using the strip line for the distribution unit170, the distribution unit170may be easily manufactured.

Effects

So far, the embodiments have been described. As described above, the plasma processing apparatus100according to the embodiments includes the processing container101(chamber), the microwave introduction device105(microwave source), and the distribution unit170. The processing container101is configured such that within the processing container101, the substrate W may be disposed, and the radiation units160that radiate microwaves are arranged while facing the substrate W. The microwave introduction device105is configured to output microwaves. The distribution unit170has one end connected to the microwave introduction device105and the other end connected to the radiation units160through branching, and is configured to distribute and transmit the microwaves output from the microwave introduction device105to the radiation units160, in which when a wavelength of the microwaves is λ, a line length L from one end to the other end falls within a predetermined range from n×λ/2 (n is a natural number). Accordingly, the plasma processing apparatus100may distribute microwaves while suppressing the influence of the impedance in the portion of the distribution unit170, on the impedance.

The microwave introduction device105includes the microwave radiation mechanism143(a matching unit) that performs matching with load impedance, in the microwave transmission module141(a microwave transmitter) that outputs the microwaves, in which the microwave radiation mechanism143(the matching unit) is connected to one end of the distribution unit170. The distribution unit170is configured such that the line length L falls within a range where impedance matching may be performed by the microwave radiation mechanism143, from n×λ/2. Accordingly, the plasma processing apparatus100may distribute microwaves while suppressing the influence in the portion of the distribution unit170on impedance.

The distribution unit170is configured such that the line length L falls within n×λ/2±λ/8. Accordingly, the plasma processing apparatus100may distribute microwaves while suppressing the influence in the portion of the distribution unit170on impedance.

The distribution unit170is configured such that a ring-shaped transmission line that transmits the microwaves is formed in a part of the distribution unit170, and a shortest line length L from one end to the other end falls within a predetermined range from n×λ/2. Accordingly, the plasma processing apparatus100may distribute microwaves while achieving impedance matching.

The distribution unit170is configured such that the other end is bifurcated one or more times, and is connected to the radiation units160. Accordingly, in the plasma processing apparatus100, the number of the microwave transmission modules141may be reduced as compared to when the microwave transmission modules141are provided for the radiation units160, respectively.

The distribution unit170is configured with a coaxial line and a strip line. Accordingly, the distribution unit170may be easily manufactured.

The processing container101is configured such that the radiation units160are provided on a wall surface (the ceiling wall111) facing the substrate W so as to surround a position corresponding to a center of the substrate W. The microwave transmission modules141(microwave transmitters) that output the microwaves are provided in the microwave introduction device105, and the number of the microwave transmission modules141is half or less than half the number of the radiation units160. The distributors170are provided corresponding to the number of the microwave transmission modules141, in which one end of each of the distributors170is connected to the microwave transmission module141so as to connect each of the microwave transmission modules141to the two or more radiation units160. Accordingly, the plasma processing apparatus100may generate plasma over a wide range from the center of the substrate W by the microwaves radiated from the radiation units160, and may perform plasma processing on the entire surface of the substrate W. In the plasma processing apparatus100, for example, the number of the microwave transmission modules141may be reduced as compared to when the microwave transmission modules141are provided for the radiation units160, respectively.

The processing container101is configured such that the radiation units160are provided on the wall surface (the ceiling wall111), which have different diameters from the position corresponding to the center of the substrate W, and are spaced apart from each other in a circumferential direction. The number of the microwave transmission modules141provided for each of the diameters is half the number of the radiation units160provided in the circumferential direction for the diameter. For each of the diameters, the distributors170are provided corresponding to the number of the microwave transmission modules141for the diameter, so as to connect the microwave transmission module141for the diameter to the two or more circumferentially adjacent radiation units160for the diameter. Accordingly, the plasma processing apparatus100may generate plasma over a wide range from the position corresponding to the center of the substrate W by the microwaves radiated from the radiation units160, and may perform plasma processing on the entire surface of the substrate W. In the plasma processing apparatus100, for example, the number of the microwave transmission modules141may be reduced as compared to when the microwave transmission modules141are provided for the radiation units160, respectively.

The plasma processing apparatus100according to the second embodiment further includes the control unit200. The control unit200is configured such that for each of the diameters, power of the microwaves output by the microwave transmission modules141for the diameter is controlled. Accordingly, the plasma processing apparatus100may control the distribution of plasma generated in the processing container101.

One microwave transmission module141is provided for each of the diameters. One distribution unit170is provided for each of the diameters, so as to connect the microwave transmission module141for the diameter to the radiation units160for the diameter. Accordingly, in the plasma processing apparatus100, the number of the microwave transmission modules141may be reduced and the plasma distribution in the radial direction from the center of the substrate W may be controlled.

The processing container101is configured such that four radiation units160are provided on the wall surface (the ceiling wall111), at equal intervals in the circumferential direction, for each of the different diameters from the position corresponding to the center of the substrate W. Accordingly, in the plasma processing apparatus100, the number of the microwave transmission modules141may be reduced and uniform plasma may be generated in the circumferential direction.

Regarding the above embodiments, the following additional notes are further disclosed.

A plasma processing apparatus including:a chamber configured to place a substrate therein, and including a plurality of microwave radiators that is arranged while facing the substrate;a microwave source configured to output microwaves; anda distributor having one end connected to the microwave source and an other end branched and connected to the plurality of microwave radiators, and configured to distribute and transmit the microwaves output from the microwave source to the plurality of microwave radiators, wherein when a wavelength of the microwaves is λ, a line length from the one end to the other end falls within a predetermined range beginning from n×λ/2 (n is a natural number).

The plasma processing apparatus described in Appendix 1, wherein the microwave source includes a matching box that performs matching with load impedance, in a microwave transmitter that outputs the microwaves, the matching box being connected to the one end of the distributor, andthe distributor is configured such that the line length falls within a range where impedance is matched by the matching box, from n×λ/2.

The plasma processing apparatus described in Appendix 1, wherein the distributor is configured such that the line length falls within n×λ/2±λ/8.

The plasma processing apparatus described in any one of Appendixes 1 to 3, wherein the distributor is configured such that a ring-shaped transmission line that transmits the microwaves is formed in a portion of the distributor, and a shortest line length from the one end to the other end falls within a predetermined range beginning from n×λ/2.

The plasma processing apparatus described in any one of Appendixes 1 to 4, wherein the distributor is configured such that the other end is bifurcated one or more times, and is connected to the plurality of microwave radiators.

The plasma processing apparatus described in any one of Appendixes 1 to 5, wherein the distributor is configured with a coaxial line and a strip line.

The plasma processing apparatus described in any one of Appendixes 1 to 6, wherein the chamber is configured such that the plurality of microwave radiators are provided on a wall surface facing the substrate to surround a position corresponding to a center of the substrate,the microwave source is provided with a number of microwave transmitters that output the microwaves, the number of which is half or less than half a number of the plurality of microwave radiators, anda plurality of distributors are provided corresponding to the number of the microwave transmitters, each of the plurality of distributors having one end connected to the microwave transmitter and connecting each of the microwave transmitters to two or more microwave radiators.

The plasma processing apparatus described in Appendix 7, wherein the chamber is configured such that the plurality of microwave radiators are provided on the wall surface with a plurality of diameters differing from a position corresponding to the center of the substrate and are spaced apart from each other in a circumferential direction,the number of the microwave transmitters provided for each of the plurality of diameters is half or less than half the number of the plurality of microwave radiators provided in the circumferential direction of the plurality of diameters, andthe plurality of distributors are provided for each of the plurality of diameters with the number of the microwave transmitters of the diameter, and configured to connect the microwave transmitter of the diameter to two or more microwave radiators adjacent in the circumferential direction of the diameter.

The plasma processing apparatus described in Appendix 8, further including a controller configured to control, for each of the plurality of diameters, power of the microwaves output by the microwave transmitter of the diameter.

The plasma processing apparatus described in Appendix 8 or 9, wherein one microwave transmitter is provided for each of the plurality of diameters, andone distributor is provided for each of the plurality of diameters, thereby connecting the microwave transmitter of the diameter to the microwave radiator of the diameter.

The plasma processing apparatus described in any one of Appendixes 8 to 10, wherein the chamber is configured such that the wall surface is provided with four microwave radiators for each of a plurality of diameters differing from the position corresponding to the center of the substrate, at equal intervals in the circumferential direction.

According to the present disclosure, it is possible to distribute microwaves while suppressing the influence in the portion of the distributor, on the impedance.