Adjustment method for filter unit and plasma processing apparatus

An adjustment method for filter units in a plasma processing apparatus includes a first measurement process of measuring a frequency characteristic of a reference filter unit selected among the filter units, and an adjustment process of adjusting a frequency characteristic of each of remaining filter units selected among the filter units excluding the reference filter unit. Further, the adjustment process includes an attachment process of attaching a capacitive member for adjusting a capacitance between wirings in each of the remaining filter units, a second measurement process of measuring a frequency characteristic of each of the remaining filter units to which the capacitive member is attached, and an individual adjustment process of adjusting a capacitance of the capacitive member such that the frequency characteristic of each of the remaining filter unit to which the capacitive member is attached becomes close to the frequency characteristic of the reference filter unit.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Japanese Patent Application No. 2018-197855, filed on Oct. 19, 2018, the entire contents of which are incorporated herein by reference.

TECHNICAL FIELD

Various aspects and embodiments of the present disclosure relate to an adjustment method for a filter unit and a plasma processing apparatus.

BACKGROUND

In a semiconductor device manufacturing process, a processing using plasma (hereinafter, referred to as plasma processing) may be performed. A plasma processing apparatus for the plasma processing includes, e.g., a chamber, a stage and a high frequency power supply and the like. In the plasma processing, a processing gas supplied into the chamber is excited by a high frequency power supplied into the chamber through the stage, and the plasma is generated. Then, the plasma processing such as etching, film formation or the like is performed on a target object mounted on the stage by the plasma thus generated.

Further, in the plasma processing apparatus, a heater may be embedded in the stage in order to control the temperature of the target object. A heater controller is connected to the heater to control a heating amount of the heater by controlling power supplied to the heater. In this plasma processing apparatus, the high frequency power supplied to the stage may flow into the heater controller through the heater, which may result in a failure or a malfunction of the heater controller. Therefore, a filter is provided in a wiring between the heater and the heater controller to remove high frequency power components. As an example of the filter, a distributed constant type filter including a passive component such as a coil may be used.

In addition, in order to increase the control accuracy of a temperature distribution of the target object, the stage may be divided into a plurality of regions and the heaters respectively provided in the regions may be controlled independently (See, e.g., Japanese Patent Application Publication No. 2011-135052).

SUMMARY

The present disclosure provides an adjustment method for a filter unit and a plasma processing apparatus that can reduce the difference in frequency characteristics between filter units connected to electric members.

In accordance with an aspect of the present disclosure, there is provided an adjustment method for filter units in a plasma processing apparatus including multiple electrical members provided in a chamber in which a target object is processed by a generated plasma, and one or more external circuits provided outside the chamber and connected to the multiple electrical members through the filter units each of which includes one or more coils and a metal housing that covers a filter provided therein, the adjustment method including: a first measurement process of measuring a frequency characteristic of a reference filter unit selected among the filter units; and an adjustment process of adjusting a frequency characteristic of each of remaining filter units selected among the filter units excluding the reference filter unit. Further, the adjustment process includes an attachment process of attaching a capacitive member for adjusting a capacitance between wirings in each of the remaining filter units; a second measurement process of measuring a frequency characteristic of each of the remaining filter units to which the capacitive member is attached; and an individual adjustment process of adjusting a capacitance of the capacitive member such that the frequency characteristic of each of the remaining filter unit to which the capacitive member is attached is adjusted to be close to the frequency characteristic of the reference filter unit.

DETAILED DESCRIPTION

Hereinafter, embodiments of an adjustment method for a filter unit and a plasma processing apparatus will be described in detail with reference to the accompanying drawings. It should be noted that the adjustment method for the filter unit and the plasma processing apparatus disclosed herein are not limited by the following embodiments.

A distributed constant type filter connected to an electrical member such as a heater includes passive components such as a coil and the like. A stray capacitor exists in a gap between such passive components and a metal housing covering the filter. Therefore, a value of the stray capacitor as well as the constants of the passive components affects the frequency characteristics of the filter.

Further, if the high frequency powers attenuated by the filters respectively connected to the heaters are different from one another, it may affect the uniformity of plasma distribution. For this reason, it is preferable that the frequency characteristics of the filters respectively provided to the heaters are the same.

However, it may be difficult to make a distance between the filter and the metal housing equal in each filter due to the restriction on a layout accompanying scaling-down of the plasma processing apparatus. For this reason, it is difficult to set the stray capacitance in each filter to the same value. As a result, the frequency characteristics of the filters respectively provided to the heaters may be different from each other, thereby deteriorating the uniformity of the plasma distribution.

Therefore, the present disclosure provides a technique capable of reducing the difference in frequency characteristics between the filter units respectively provided to the electrical members.

First Embodiment

Configuration of Plasma Etching Apparatus1

FIG. 1is a cross-sectional view schematically showing an example of a plasma etching apparatus1according to a first embodiment of the present disclosure. The plasma etching apparatus1in the first embodiment is configured as a capacitively-coupled plasma processing apparatus. The plasma etching apparatus1includes an apparatus main body2and a control device3.

The apparatus main body2includes a chamber10having a substantially cylindrical shape. The chamber is made of, e.g., aluminum, stainless steel or the like. The chamber10is frame-grounded. In the chamber10, a substantially disk-shaped susceptor12is disposed. The susceptor12is made of, e.g., aluminum or the like and serves as a lower electrode. The susceptor12is supported by a cylindrical support member14extending vertically upward from a bottom portion of the chamber10. The support member14is made of an insulating member such as ceramic or the like. Thus, the support member14is electrically isolated from the chamber10.

A conductive cylindrical support portion16is provided at an outer periphery of the support member14. The support portion16extends vertically upward from the bottom portion of the chamber10along the outer periphery of the support member14. An annular gas exhaust passage18is formed between the cylindrical support portion16and an inner wall of the chamber10. At a bottom portion of the gas exhaust passage18, a gas exhaust port20is provided. A gas exhaust device24having a turbo molecular pump or the like is connected to the gas exhaust port20through a gas exhaust line22. By operating the gas exhaust device24, a processing space in the chamber10is depressurized to a desired vacuum level. An opening is formed at a sidewall of the chamber10. A semiconductor wafer W, which is an example of a target substrate to be processed, is loaded and unloaded through the opening, and the opening is opened and closed by a gate valve26.

A high frequency power supply28is electrically connected to the susceptor12through a matching unit32and a power feeding rod34. The high frequency power supply28is configured to supply high frequency power to the susceptor12through the matching unit32and the power feeding rod34. The high frequency power has a first frequency mainly contributing to plasma generation. The first frequency is, e.g., 27 MHz or more, and preferably 60 MHz or more. The matching unit32performs impedance matching between the high frequency power supply28and a plasma load.

The power feeding rod34is a substantially columnar conductor. An upper end of the power feeding rod34is connected to a central portion of a bottom surface of the susceptor12. A lower end of the power feeding rod34is connected to the matching unit32. In addition, a substantially cylindrical conductor cover35having an inner diameter larger than an outer diameter of the power feeding rod34is disposed around the power feeding rod34. An upper end of the cover35is connected to an opening formed in the bottom portion of the chamber10, and a lower end of the cover35is connected to a housing of the matching unit32.

An edge ring36and an electrostatic chuck38are disposed on the susceptor12. The semiconductor wafer W is mounted on a top surface of the electrostatic chuck38. The electrostatic chuck38is an example of a stage. The edge ring36may be referred to as a focus ring. The edge ring has a substantially annular outer shape, and the electrostatic chuck38has a substantially disk-like outer shape. The edge ring36is disposed to surround the electrostatic chuck38. The edge ring36is made of, e.g., silicon (Si), silicon carbide (SiC), carbon (C), silicon dioxide (SiO2), or the like.

The electrostatic chuck38has a plurality of heaters40, a dielectric member42, and an electrode44. Each heater40is an example of an electrical member. The heaters40and the electrode44are embedded in the dielectric member42. A DC power supply45disposed outside the chamber10is electrically connected to the electrode44through a switch46, a resistor48and a wiring50. The semiconductor wafer W is attracted and held on the top surface of the electrostatic chuck38by a Coulomb force generated by a DC voltage applied from the DC power supply45to the electrode44. The wiring50is coated with an insulator. The wiring50passes through the inside of the power feeding rod34and penetrates the susceptor12from the bottom of the susceptor12to be connected to the electrode44of the electrostatic chuck38.

Each of the heaters40may be, e.g., a spiral-shaped resistance heating wire. For example, the top surface of the electrostatic chuck38is divided into multiple regions380as shown inFIG. 2.FIG. 2is a top view showing an example of the divided regions of the electrostatic chuck38. The heaters40are arranged in the multiple regions380, respectively. A filter unit54is connected to each of the heaters40through a wiring52coated with an insulator. Each filter unit54is connected to a heater power supply58through a wiring56coated with an insulator. The heater power supply58is an example of an external circuit.

In the plasma etching apparatus1shown inFIG. 1, two wirings52, two filter units54, two wirings56, and two heater power supplies58are illustrated. However, in practice, the wirings52, the filter units54, the wirings56, and the heater power supplies58are provided in the same number as the number of the heaters40provided to correspond to the regions380shown inFIG. 2. Alternatively, one heater power supply58may be shared by the heaters40to supply power to each of the heaters40through each of the wirings56, the filter units54and the wirings56corresponding thereto. Each of the filter units54will be described later in detail.

An annular flow path60is formed in the susceptor12. The flow path60is supplied with a coolant from a chiller unit (not shown) and the coolant is circulated therein. The susceptor12is cooled by the coolant circulated in the flow path60and the electrostatic chuck38disposed on the susceptor12is cooled. The susceptor12and the electrostatic chuck38are provided with a gas line62for supplying a heat transfer gas such as He gas to a gap between the electrostatic chuck38and the semiconductor wafer W. A heat transfer rate between the electrostatic chuck38and the semiconductor wafer W is controlled by controlling a pressure of the heat transfer gas supplied to the gap between the electrostatic chuck38and the semiconductor wafer W through the gas line62.

A shower head64is provided at a ceiling portion of the chamber10to be opposite to the susceptor12. The shower head64serves as an upper electrode opposite to the susceptor12serving as the lower electrode. A plasma generation space S is formed between the shower head64and the susceptor12. The shower head64includes an electrode plate66facing the susceptor12and a holding body68that detachably holds the electrode plate66from above. The electrode plate66is made of, e.g., Si, SiC, C, or the like. The holding body68is made of, e.g., alumite-treated aluminum.

A gas diffusion space70is formed in the holding body68. A plurality of gas injection holes72are formed to extend through the electrode plate66and the holding body68from the gas diffusion space70to the susceptor12. A gas inlet port70acommunicating with the gas diffusion space70is provided at an upper portion of the holding body68. A processing gas supply unit74is connected to the gas inlet port70athrough a gas line76. The processing gas supply unit74includes gas supply sources for supplying various gases. Each of the gas supply sources is connected to a flow rate controller, a valve, and the like. Then, various gases are individually supplied into the plasma generation space S after the flow rates thereof are controlled by the respective flow rate controllers.

The respective components of the apparatus main body2are controlled by a control device3including, e.g., memory, a processor, and an input/output interface. A control program, a processing recipe, and the like are stored in the memory. The processor reads out and executes the control program from the memory and controls the respective components of the apparatus main body2through the input/output interface based on the processing recipe stored in the memory. By controlling the respective components, the plasma etching apparatus1performs an etching using plasma on the semiconductor wafer W.

For example, the gate valve26is opened, and the semiconductor wafer W that is a target object to be processed is loaded into the chamber10by a transfer device (not shown) and mounted on the electrostatic chuck38. Then, the semiconductor wafer W is attracted and held on the top surface of the electrostatic chuck38by controlling the switch46to be turned on. Further, the coolant is supplied and circulated in the flow path60from the chiller unit (not shown), and the heat transfer gas is supplied to the gap between the electrostatic chuck38and the semiconductor wafer W through the gas line62. Then, electric power is supplied from the heater power supply58corresponding to each of the heaters40. The electric power supplied to each of the heaters40is controlled independently by the control device3. Therefore, the temperature distribution of the semiconductor wafer W can be controlled.

Then, the processing gas is supplied from the processing gas supply unit74into the chamber10at a predetermined flow rate, and the pressure in the chamber10is controlled to a desired level by the gas exhaust device24. Further, plasma of the processing gas is generated in the plasma generation space S by supplying a high frequency power of a predetermined power level from the high frequency power supply28to the susceptor12through the matching unit32and the power feeding rod34. Then, the semiconductor wafer W is etched by ions and radicals contained in the plasma.

Detailed Configuration of Filter Unit54

FIGS. 3A and 3Bshow examples of the plurality of the filter units54according to the first embodiment of the present disclosure.FIG. 3Ashows one filter unit54-1among the filter units54, andFIG. 3Bshows another filter unit54-2among the filter units54. The filter unit54-1is connected to a heater40-1through wirings52-1and is connected to a heater power supply58-1through wirings56-1. The filter unit54-2is connected to a heater40-2through wirings52-2and is connected to a heater power supply58-2through wirings56-2.

For example, as shown inFIGS. 3A and 3B, each of the filter unit54-1and the filter unit54-2includes a metal housing540, a coil541a,a coil541b,a coil541c,a coil541d,a capacitor542a,and a capacitor542b.Hereinafter, the coil541a,the coil541b,the coil541c,and the coil541dare collectively referred to as “coil541” unless otherwise distinguished. In addition, the capacitor542aand the capacitor542bare collectively referred to as “capacitor542” unless otherwise distinguished. The plurality of the coils541and the plurality of the capacitors542are accommodated in the metal housing540, and the metal housing540is grounded.

In the examples ofFIGS. 3A and 3B, four coils541and two capacitors542are accommodated in the metal housing540. The coil541aand the coil541bare connected in series in one wiring in the metal housing540, and the coil541cand the coil541dare connected in series in the other wiring in the metal housing540. In the present embodiment, the coils541aand541bconnected in series are configured as coils with unequal pitches (that is, the pitches thereof are not uniform). However, the configuration of the coils is not limited thereto, and it may be possible to configure the coil541aand the coil541bconnected in series as one coil having an equal pitch. The capacitor542ais connected between one wiring in the metal housing540and the metal housing540, and the capacitor542bis connected between the other wiring in the metal housing540and the metal housing540. However, the number of coils and the number of capacitors are not limited thereto. The number of coils connected in series to each wiring in the metal housing540may be three or more, and the number of capacitors connected between each wiring in the metal housing540and the metal housing540may be two or more.

In one wiring in the metal housing540, the coils541aand541bconnected in series and the capacitor542aconstitute an LC filter. Further, in the other wiring in the metal housing540, the coils541cand541dconnected in series and the capacitor542bconstitute an LC filter. These LC filters attenuate a predetermined frequency power flowing thereinto through the heater40. There also exist stray capacitors543between the wirings in the metal housing540and between each of the wirings in the metal housing540and the metal housing540. Therefore, the frequency characteristics of the filter unit54are the frequency characteristics of a circuit configured by the plurality of the coils541, the plurality of the capacitors542, and the stray capacitors543.

For example, in the case where “Lt” is the total inductance of the two coils541, and “Ct” is the total capacitance of the capacitor542and the stray capacitor543, a resonance frequency f of the LC filter in each wiring in the metal housing540is expressed by, e.g., the following equation (1):

Further, the capacitance C of the capacitor is generally expressed by the following equation (2):

where “d” is the distance between the electrodes, “S” is the area of the electrode, and “ε” is the permittivity of a dielectric medium between the electrodes.

Here, along with the trend toward scaling-down of the plasma etching apparatus1, the shape and the size of a place where each of the filter units54is disposed may be restricted. Accordingly, it may be difficult to allow the metal housings540to have the same size. Therefore, for example, as shown inFIGS. 3A and 3B, there may be a case where a relatively large-size metal housing540such as the filter unit54-1can be used or a case where a relatively small-size metal housing540such as the filter unit54-2has to be used depending on the place where it is arranged.

When the shape or the size of the metal housing540is changed, the distance between the wiring (or the coil541) and the metal housing540is also changed. When the wiring (or the coil541) and the metal housing540are regarded as electrodes, according to the equation (2), a capacitance Csof the stray capacitor543between the wiring (or the coil541) and the metal housing540depends on a distance dsbetween the wiring (or the coil541) and the metal housing540. Therefore, in the case where the shape or the size of the metal housing540is changed, even if the constants of the coils541and the capacitors542in the plurality of filter units54are equal, if capacitances Csof the stray capacitors in the filter units54are different from one another, the frequency characteristics of the LC filters become different from one another.

Specifically, since the capacitances Csof the stray capacitors543are different, the total capacitances Ctof the filter units54are different from one another. When the total capacitances Ctof the filter units54are different from one another, the resonance frequencies f in the equation (1) are different from one another.FIG. 4shows an example of the frequency characteristics of the impedance of each of the filter unit54-1and the filter unit54-2. For example, as shown inFIG. 4, a resonance frequency f1of the filter unit54-1having a longer distance dsbetween the wiring (or the coil541) and the metal housing540is higher than a resonance frequency f2of the filter unit54-2having a shorter distance ds.

As a result, the resonance frequency f deviates from a frequency f0of the high frequency power applied to the susceptor12from the high frequency power supply28, which makes it difficult to sufficiently attenuate the high frequency power flowing into the heater power supply58. Further, in the filter units54, the resonance frequencies f deviate depending on the shape and the size of the metal housing540, resulting in the increase of the difference in the attenuation amount of the high frequency power among the filter units54. This reduces the uniformity of the plasma distribution and reduces the accuracy of the plasma processing.

Therefore, in the present embodiment, the difference in the frequency characteristics among the filter units54is reduced by individually adjusting the capacitances of the filter units54. For example, in the case of the filter unit54including the stray capacitor543having a small capacitance, the capacitance between the wiring (or the coil541) and the metal housing540is adjusted to be increased. As a result, it becomes possible to improve the uniformity of the plasma distribution and the accuracy of the plasma processing.

For example, as shown inFIG. 5, the capacitance between the wiring (or the coil541) and the metal housing540is increased by attaching a capacitive member545into the filter unit54.FIG. 5shows an example of the filter unit54to which the capacitive member545is attached. In the example ofFIG. 5, the capacitive member545is attached to the wirings52in the metal housing540. However, the present disclosure is not limited thereto, and the capacitive member545may be connected to the wirings52disposed outside of the metal housing540.

FIG. 6is an exploded perspective view showing an example of the metal housing540, the capacitive member545and the wirings52. The metal housing540is divided into a first division housing5400and a second division housing5401. Further, the capacitive member545is a block-shaped dielectric member and is divided into a first division member5450and a second division member5451. In each of the first division member5450and the second division member5451, grooves5452are formed to respectively arrange the wirings52therein.

The wirings52are arranged in the respective grooves5452, and the first division member5450and the second division member5451lie one on top of the other with the wirings52interposed therebetween. Then, the first division housing5400and the second division housing5401lie one on top of the other so as to interpose therebetween the capacitive member545having the wirings52therein. Therefore, for example, the capacitive member545is accommodated in the filter unit54, as shown inFIG. 7. Thus, since the capacitive member545has a structure in which the wirings52are interposed therein, the capacitive member545can be easily attached and detached. Alternatively, the capacitive member545may have a structure with through holes formed in the capacitive member545to allow the wirings52to pass therethrough.

The permittivity ε of an arbitrary dielectric material is expressed as “ε=ε0εr” where “ε0” is the vacuum permittivity and “εr” is the relative permittivity defined based on the vacuum permittivity ε0. The relative permittivity εrof air is equal to about 1. The relative permittivity εrof the PCTFE is equal to about 2.6. The relative permittivity srof the PEEK is equal to about 3.2. The relative permittivity εrof the PPS is equal to about 3.6. As shown in the equation (2), the capacitance C can be changed when the dielectric medium having a different permittivity ε is interposed between the electrodes.

In the filter unit54having a relatively small-sized metal housing540, the distance between the wiring (or the coil541) and the metal housing540is short, so that the capacitance Csof the stray capacitor543is large and the resonance frequency f becomes low. On the other hand, in the filter unit54having a relatively large-sized metal housing540, the distance between the wiring (or the coil541) and the metal housing540is long, so that the capacitance Csof the stray capacitor543is small and the resonance frequency f becomes high. Therefore, in the filter unit54having the relatively large-sized metal housing540, the capacitance C between the wiring (or the coil541) and the metal housing540can be adjusted to be increased by attaching the capacitive member545made of a material having a permittivity ε larger than that of air. With such a configuration, the resonance frequency f can be lowered. Therefore, the difference in the resonance frequency f between the filter units54can be reduced.

Further, by adjusting the shape and the size of the capacitive member545, the size of the gap between the capacitive member545and the metal housing540can be adjusted. When the gap between the capacitive member545and the metal housing540is changed, the distance d shown in the equation (2) is changed, resulting in the change of the capacitance C between the wiring (or the coil541) and the metal housing540. Consequently, the resonance frequency f of the plurality of the filter unit54can be changed.

For example, in the filter unit54having the relatively large-sized metal housing540, the gap between the capacitive member545and the metal housing540is reduced in size when the capacitive member545is attached to the filter unit54. When the gap between the capacitive member545and the metal housing540is reduced, the distance d shown in the equation (2) is reduced. As the distance d is reduced, the capacitance C between the wiring (or the coil541) and the metal housing540is increased and the resonance frequency f is lowered. As described above, the difference in the resonance frequency f between the filter units54can be reduced by adjusting the shape and the size of the capacitive member545.

Adjustment Method for Filter Unit54

FIG. 8is a flowchart illustrating an example of a method for adjusting the filter unit54according to the first embodiment of the present disclosure. For example, the adjustment method shown inFIG. 8is performed when the plasma etching apparatus1is assembled, but may be performed periodically after the plasma etching apparatus1is assembled.

First, among the plurality of the filter units54, a reference filter unit54is specified (step S10). For example, the filter unit54having the smallest gap between the coil541and the metal housing540is specified as the reference filter unit54. Then, the frequency characteristics of the reference filter unit54are measured around a first frequency by using, e.g., a network analyzer or the like (step S11). Step S11is an example of a first measurement process.

Next, one of the filter units54that has not been selected is selected among the filter units54excluding the reference filter unit54(step S12). The filter unit54selected in step S12has a gap between the coil541and the metal housing540greater than the reference filter unit54. Then, the frequency characteristics of the filter unit54selected in step S12are measured around the first frequency by using, e.g., the network analyzer or the like (step S13).FIG. 13schematically represents a measurement apparatus (e.g., a network analyzer)55, connected to a filter54for step S11represented in solid line, and thereafter, to a filter54for step S13(as well as, e.g., S16discussed below) represented in broken line.

Thereafter, it is determined whether or not the frequency characteristics of the filter unit54selected in step S12satisfy an allowable condition (step S14). For example, when the difference between the resonance frequency f of the reference filter unit54and the resonance frequency f of the filter unit54selected in step S12is less than a predetermined value, it is determined that the allowable condition is satisfied. The predetermined value is, e.g., several tens of kHz.

Meanwhile, depending on a structure of the coil541, the impedance may vary considerably around the resonance frequency. The coil541having such a structure has a large impedance change even when the difference in the resonance frequency is small. Therefore, in the coil541having the structure in which the impedance varies considerably around the resonance frequency, the predetermined value is preferably set to a smaller value such as several kHz. On the other hand, in the coil541having a structure in which the impedance varies smoothly around the resonance frequency, the impedance is not greatly changed even if the difference in the resonance frequency is slightly large. Therefore, in the coil541having such a structure, the predetermined value is preferably set to a larger value such as several hundred kHz. Further, since the difference in the attenuation amount of the high frequency power among the plurality of the filter units54only needs to be small, it is not necessary to have the resonance frequencies f in the plurality of the filter units54coincide with one another.

If the frequency characteristics of the filter unit54selected in step S12satisfy the allowable condition (YES in step S14), it is determined whether or not all of the filter units54have been selected among the filter units54excluding the reference filter unit54(step S19). If there is an unselected filter unit54(NO in step S19), the process shown in step S12is executed again. On the other hand, when all of the filter units54have been selected (YES in step S19), the adjustment method for the filter unit54shown inFIG. 8is terminated.

When the frequency characteristics of the filter unit54selected in step S12do not satisfy the allowable condition (NO in step S14), the capacitive member545is attached to the filter unit54to adjust the capacitances of the wirings in the filter unit54(step S15). Step S15is an example of an attachment process. Then, the frequency characteristics of the filter unit54to which the capacitive member545is attached are measured around the first frequency by using, e.g., the network analyzer or the like (step S16). Step S16is an example of a second measurement process.

Next, it is determined whether or not the frequency characteristics of the filter unit54to which the capacitive member545is attached satisfy the allowable condition (step S17). When the frequency characteristics of the filter unit54to which the capacitive member545is attached satisfy the allowable condition (YES in step S17), the process shown in step S19is executed.

On the other hand, when the frequency characteristics of the filter unit54to which the capacitive member545is attached do not satisfy the allowable condition (NO in step S17), the capacitance added by the capacitive member545is adjusted (step S18). Step S18is an example of an individual adjustment process. The adjustment of the capacitance is performed by replacing the current capacitive member545with a new capacitive member545having a different permittivity s, or changing the shape or the size of the current capacitive member545, for example. Then, the process shown in step S13is executed again. Steps S13to S18are an example of an adjustment process.

The first embodiment has been described above. The adjustment method for the filter unit54in the first embodiment is an adjustment method for the filter unit54in the plasma etching apparatus1. The adjustment method includes a first measurement process and an adjustment process. The plasma etching apparatus1includes a plurality of the heaters40provided in the chamber10in which a target object is processed by a generated plasma and one or more heater power supplies58provided outside the chamber10and connected to the heaters40through the filter units54each of which includes the coils541. Each of the filter units54further includes the metal housing540that covers the filter provided therein. In the first measurement process, the frequency characteristics of the reference filter unit54selected among the filter units54are measured. In the adjustment process, the frequency characteristics of each of the remaining filter units54selected among the filter units54excluding the reference filter unit54are adjusted. The adjustment process includes an attachment process, a second measurement process and an individual adjustment process. In the attachment process, the capacitive member545is attached for adjusting the capacitance between the wirings in the filter unit54. In the second measurement process, the frequency characteristics of the filter unit54to which the capacitive member545is attached are measured. In the individual adjustment process, the capacitance of the capacitive member545is adjusted such that the frequency characteristics of the filter unit54to which the capacitive member545is attached are adjusted to be close to the frequency characteristics of the reference filter unit54. Therefore, the difference in frequency characteristic between the filter units54respectively provided to the heaters40can be reduced.

In the above-described embodiment, the reference filter unit54is the filter unit54having the smallest gap between the coils541and the metal housing540among the filter units54. By attaching the capacitive member545having a permittivity ε larger than that of air to the filter unit54other than the reference filter unit54, the frequency characteristics of the filter unit54to which the capacitive member545is attached become close to the frequency characteristics of the reference filter unit54.

In the above-described embodiment, the capacitive member545is a dielectric member in which the wirings in the filter unit54are interposed. Therefore, an attachment and a removal of the capacitive member545to and from the filter unit54can be easily performed.

In the individual adjustment process of the above-described embodiment, the capacitance of the capacitive member545is adjusted by changing at least one of the material, the shape and the size of the capacitive member545. Therefore, the frequency characteristics of the filter unit54to which the capacitive member545is attached can become close to the frequency characteristics of the reference filter unit54.

In the above-described embodiment, each of the electrical members is the heater40provided in the electrostatic chuck38on which the semiconductor wafer W is mounted. As a result, the filter unit54can reduce the high frequency power flowing into the heater power supply58through the heater40.

Second Embodiment

Configuration of Plasma Etching Apparatus1

FIG. 9is a cross-sectional view schematically showing an example of a plasma etching apparatus1according to a second embodiment of the present disclosure. Except for those particularly described in the followings, inFIG. 9, like reference numerals are given to like parts having the same or similar functions described inFIG. 1, and redundant description thereof will be omitted. In the plasma etching apparatus1according to the present embodiment, the high frequency power supply28and a high frequency power supply are connected to the susceptor12through the power feeding rod34and the matching unit32.

The high frequency power supply30is configured to supply high frequency power to the susceptor12through the matching unit32and the power feeding rod34. The high frequency power has a second frequency (e.g., 13 MHz or less) that mainly contributes to ion attraction with respect to the semiconductor wafer W mounted on the susceptor12. The matching unit32further performs an impedance matching between the high frequency power supply30and a plasma load.

Detail Configuration of Filter Unit54

FIG. 10shows an example of the filter unit54according to the second embodiment of the present disclosure. The filter unit54in the present embodiment includes a first unit54A and a second unit54B. In the present embodiment, the first unit54A is configured to attenuate a component of the first frequency in the high frequency power flowing into the heater power supply58through the heater40. Further, the second unit54B is configured to attenuate a component of the second frequency in the high frequency power flowing into the heater power supply58through the heater40. Therefore, the filter unit54in the present embodiment is configured to attenuate the components of the first frequency and the second frequency in the high frequency power flowing into the heater power supply58through the heater40. Alternatively, the first unit54A may attenuate the component of the second frequency in the high frequency power, and the second unit54B may attenuate the component of the first frequency in the high frequency power.

The first unit54A is connected to the heater40through the wirings52and is connected to the second unit54B through wirings53, each of which is coated with an insulator. The second unit54B is connected to the first unit54A through the wirings53and is connected to the heater power supply58through the wirings56.

The first unit54A includes a metal housing540A, a coil541a-1, a coil541b-1, a coil541c-1, a coil541d-1, a capacitor542a-1and a capacitor542b-1. Hereinafter, the coil541a-1, the coil541b-1, the coil541c-1and the coil541d-1are collectively referred to as “coil541-1” unless otherwise distinguished. Further, the capacitor542a-1and the capacitor542b-1are collectively referred to as “capacitor542-1” unless otherwise distinguished. The plurality of the coils541-1and the plurality of the capacitors542-1are accommodated in the metal housing540A, and the metal housing540A is grounded. There exist stray capacitors543-1between the wirings in the metal housing540A, and between each of the wirings in the metal housing540A and the metal housing540A.

The second unit54B includes a metal housing540B, a coil541a-2, a coil541b-2, a coil541c-2, a coil541d-2, a capacitor542a-2, and a capacitor542b-2. Hereinafter, the coil541a-2, the coil541b-2, the coil541c-2and the coil541d-2are collectively referred to as “coil541-2” unless otherwise distinguished. Further, the capacitor542a-2and the capacitor542b-2are collectively referred to as “capacitor542-2” unless otherwise distinguished. The plurality of the coils541-2and the plurality of the capacitors542-2are accommodated in the metal housing540B, and the metal housing540B is grounded. There exist stray capacitors543-2between the wirings in the metal housing540B, and between each of the wirings in the metal housing540B and the metal housing540B.

Here, along with the trend toward scaling-down of the plasma etching apparatus1, it may be difficult to allow the metal housings5410A in the first units54A of the plurality of the filter units54to have the same size. If the stray capacitors543-1in the first units54A of the filter units54are different from one another, the frequency characteristics of the first units54A may be different from one another. Therefore, in the present embodiment, for example, a capacitive member545ais attached to each of the first units54A of the filter units54excluding the reference filter unit54, as shown inFIG. 11. Therefore, the frequency characteristics of the filter unit54to which the capacitive member545ais attached become close to the frequency characteristics of the reference filter unit54around the first frequency.

In the example shown inFIG. 11, the capacitive member545ais attached to the wirings52in the metal housing540A. However, the present disclosure is not limited thereto, and the capacitive member545amay be attached to the wirings52outside the metal housing540A.

Similarly to the first unit54A, for the second units54B of the plurality of the filter units54, if the stray capacitors543-2in the second units54B are different from one another, the frequency characteristics of the second units54B may be different from one another. Therefore, in the present embodiment, for example, a capacitive member545bis attached to the wirings53in each of the first units54A connected to the second units54B of the filter units54excluding the reference filter unit54, as shown inFIG. 11. Therefore, the frequency characteristics of the filter unit54to which the capacitive member545bis attached become close to the frequency characteristics of the reference filter unit54around the second frequency.

In the example shown inFIG. 11, the capacitive member545bis attached to the wirings53in the metal housing540A. However, the present disclosure is not limited thereto, and the capacitive member545bmay be attached to, e.g., the wirings53between the metal housing540A and the metal housing540B, or may be attached to, e.g., the wirings53in the metal housing540B.

Adjustment Method for Filter Unit54

FIG. 12is a flowchart illustrating an example of a method for adjusting the filter unit54according to the second embodiment of the present disclosure. For example, the adjustment method shown inFIG. 12is performed when the plasma etching apparatus1is assembled, but may be performed periodically after the plasma etching apparatus1is assembled.

First, the frequency characteristics of the first units54A of the plurality of the filter units54around the first frequency are adjusted (step S20). In step S20, the same adjustment method as the adjustment method for the filter unit54shown inFIG. 8is performed on the first units54A of the filter units54. Hereinafter, the process of step S20will be described in detail with reference toFIG. 8.

First, among the first units54A of the plurality of the filter units54, a reference first unit54A is specified (step S10). For example, the first unit54A having the smallest gap between the coil541-1and the metal housing540A is specified as the reference first unit54A. Then, the frequency characteristics of the filter unit54including the reference first unit54A are measured around a first frequency by using, e.g., a network analyzer or the like (step S11).

Next, one of the first units54A that has not been selected is selected among the first units54A excluding the reference first unit54A (step S12). The first unit54A selected in step S12has a gap between the coil541-1and the metal housing540A greater than the gap of the reference first unit54A. Then, the frequency characteristics of the filter unit54including the first unit54A selected in step S12are measured around the first frequency by using, e.g., the network analyzer or the like (step S13).

Thereafter, it is determined whether or not the frequency characteristics of the filter unit54including the first unit54A selected in step S12satisfy an allowable condition (step S14). For example, when the difference between the resonance frequency f of the filter unit54including the reference first unit54A and the resonance frequency f of the filter unit54including the first unit54A selected in step S12is less than a predetermined value, it is determined that the allowable condition is satisfied. The predetermined value is, e.g., several tens of kHz.

If the frequency characteristics of the filter unit54including the first unit54A selected in step S12satisfy the allowable condition (YES in step S14), it is determined whether or not all of the first units54A have been selected (step S19). If there is an unselected first unit54A (NO in step S19), the process shown in step S12is executed again. On the other hand, when all of the first units54A have been selected (YES in step S19), the adjustment method for the first unit54A in step S20is terminated.

When the frequency characteristics of the filter unit54including the first unit54A selected in step S12do not satisfy the allowable condition (NO in step S14), the capacitive member545ais attached to the first unit54A (step S15). Then, the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545ais attached are measured around the first frequency by using, e.g., the network analyzer or the like (step S16).

Next, it is determined whether or not the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545ais attached satisfy the allowable condition (step S17). When the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545ais attached satisfy the allowable condition (YES in step S17), the process shown in step S19is executed.

On the other hand, when the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545ais attached does not satisfy the allowable condition (NO in step S17), the capacitance added by the capacitive member545ais adjusted (step S18). The adjustment of the capacitance is performed by replacing the current capacitive member545awith a new capacitive member545ahaving a different permittivity s, or changing the shape or the size of the current capacitive member545a.Then, the process shown in step S13is executed again.

Next, the frequency characteristics of the second units54B of the plurality of the filter units54around the second frequency are adjusted (step S30). In step S30, the same adjustment method as the adjustment method for the filter unit54shown inFIG. 8is performed on the second units54B of the filter units54. Hereinafter, the detail process of step S30will be described with reference toFIG. 8.

First, among the second units54B of the plurality of the filter units54, a reference second unit54B is specified (step S10). For example, the second unit54B having the smallest gap between the coil541-2and the metal housing540B is specified as the reference second unit54B. Then, the frequency characteristics of the filter unit54including the reference second unit54B are measured around a second frequency by using, e.g., a network analyzer or the like (step S11).

Next, one of the second units54B, which has not been selected, is selected among the second units54B excluding the reference second unit54B (step S12). The second unit54B selected in step S12has the gap between the coil541-2and the metal housing540B greater than the reference second unit54B. Then, the frequency characteristics of the filter unit54including the second unit54B selected in step S12are measured around the second frequency by using, e.g., the network analyzer or the like (step S13).

Thereafter, it is determined whether or not the frequency characteristics of the filter unit54including the second unit54B selected in step S12satisfies an allowable condition (step S14). For example, when the difference between the resonance frequency f of the filter unit54including the reference second unit54B and the resonance frequency f of the filter unit54including the second unit54B selected in step S12is less than a predetermined value, it is determined that the allowable condition is satisfied. The predetermined value is, e.g., several tens of kHz.

If the frequency characteristics of the filter unit54including the second unit54B selected in step S12satisfy the allowable condition (YES in step S14), it is determined whether or not all of the second units54B have been selected (step S19). If there is an unselected second unit54B (NO in step S19), the process shown in step S12is executed again. On the other hand, when all of the second units54B have been selected (YES in step S19), the adjustment method for the second unit54B in step S30is terminated.

When the frequency characteristics of the filter unit54including the second unit54B selected in step S12do not satisfy the allowable condition (NO in step S14), the capacitive member545bis attached to the first unit54A connected to the second unit54B (step S15). Then, the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545bis attached are measured around the second frequency by using, e.g., the network analyzer or the like (step S16).

Next, it is determined whether or not the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545bis attached satisfy the allowable condition (step S17). When the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545bis attached satisfy the allowable condition (YES in step S17), the process shown in step S19is executed.

On the other hand, when the frequency characteristics of the filter unit54including the first unit54A to which the capacitive member545bis attached do not satisfy the allowable condition (NO in step S17), the capacitance added by the capacitive member545bis adjusted (step S18). The adjustment of the capacitance is performed by replacing the current capacitive member545bwith a new capacitive member545bhaving a different permittivity s, or changing the shape or the size of the capacitive member545b.Then, the process shown in step S13is executed again.

The second embodiment has been described above. The filter unit54in the second embodiment includes the first unit54A and the second unit54B. The first unit54A is connected to the heater40and attenuates the first frequency component of the high frequency power flowing from the heater40to the heater power supply58. The second unit54B is connected between the first unit54A and the heater power supply58and attenuates the second frequency component different from the first frequency component of the high frequency power. Therefore, it is possible to suppress the high frequency power including the first frequency component and the second frequency component from flowing from the heater40to the heater power supply58.

Others

The techniques disclosed in the present application are not limited to the above-described embodiments, and various modifications may be made without departing from the scope and spirit of the present disclosure.

For example, in the first embodiment described above, by changing the material of the capacitive member545with the wirings52interposed therein, the frequency characteristics of the filter units54excluding the reference filter unit54are adjusted so as to be close to the frequency characteristics of the reference filter unit54. However, the present disclosure is not limited thereto. For example, a variable capacitor whose capacitance can be continuously changed may be connected between the wirings in the metal housing540and between the wirings in the metal housing540and the metal housing540. Then, the capacitance of the variable capacitor is adjusted to be continuously changed around a frequency of a first high frequency power such that the frequency characteristics of the filter units54excluding the reference filter unit54are close to the frequency characteristics of the reference filter unit54.

Further, in the second embodiment described above, a variable capacitor is connected between the wirings in the metal housing540and between the wirings in the metal housing540and the metal housing540. Then, the capacitance of the variable capacitor is adjusted to be continuously changed around a frequency of a second high frequency power such that the frequency characteristics of the filter units54excluding the reference filter unit54are close to the frequency characteristics of the reference filter unit54. In this case, it is also possible to reduce the difference in the frequency characteristics between the filter units54respectively connected to the heaters40.

In the above-described embodiments, the heater40has been described as an example of the electrical member. However, the present disclosure is not limited thereto. The electrical member may be a member other than the heater40as long as the member is provided in the chamber10and connected to an external circuit provided outside the chamber10through the filter unit54. Examples of members other than the heater40include the electrode44provided in the electrostatic chuck38and various sensors (temperature sensor, pressure sensor and the like) provided in the chamber10.

Further, in the above-described embodiments, the plasma etching apparatus1has been described as an example of the plasma processing apparatus, but the present disclosure is not limited thereto. As long as the apparatus performs the plasma processing, the techniques described in the present disclosure can be applied thereto. Examples of the apparatus include a film forming apparatus, a cleaning apparatus, or a modification apparatus.

Further, in the plasma etching apparatus1of the above-described embodiments, the capacitively-coupled plasma (CCP) is used as an example of a plasma source, but the present disclosure is not limited thereto. For example, inductively-coupled plasma (ICP), microwave excited surface wave plasma (SWP), electron cyclotron resonance plasma (ECP), helicon wave excited plasma (HWP), or the like may be used as the plasma source.