JP2010238730A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve stability and reproducibility of a plasma process by stably and smoothly performing a matching operation of a matcher even when RF power fed to plasma is varied over a wide range (in particular, when a lower power range is selected) or when impedance of the plasma varies large. <P>SOLUTION: In a capacity coupling type plasma etching device, a high-frequency power source 28 is electrically connected to a susceptor 12 mounted with a semiconductor wafer W in a chamber 10 through a matching unit 30 and a feed rod 32. A portion of the RF power is branched to and absorbed by an RF power branch absorption unit 44 halfway on the feed rod 32 or behind a matcher in the matching unit 30 to reduce variation in apparent load impedance viewed from the matcher. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a plasma processing technique for performing plasma processing on a substrate to be processed using a high frequency, and in particular, a high frequency for supplying a high frequency from a high frequency power source in an impedance matching state to plasma generated in a processing container. It relates to the improvement of the power feeding section.

  In a manufacturing process of a semiconductor device or an FPD (Flat Panel Display), a plasma processing apparatus that performs processing such as etching, deposition, oxidation, and sputtering using plasma is often used. In general, in a plasma processing apparatus, a high frequency electrode is provided in or outside a vacuum chamber (processing container), and a high frequency is applied to the high frequency electrode from a high frequency power supply unit. The high-frequency power supply unit is provided with not only a power source that outputs a high frequency, but also a matching unit for matching between the impedance of the high-frequency power source and the impedance on the load side. Since the high frequency power supply is normally designed to have a pure resistance output of 50Ω, the impedance in the matching device is set or adjusted so that the impedance on the load side including the matching device becomes 50Ω (for example, Patent Document 1). reference).

  In general, this type of matching device includes one or a plurality of variable reactance elements such as a variable capacitor or a variable inductance coil, and each step position or position within a variable range is selected by a step motor or the like, so that the inside of the matching device. The load impedance and the load impedance can be variably adjusted. During plasma processing, if the impedance of the plasma changes due to pressure fluctuations, etc., the impedance position of these variable reactance elements is variably adjusted to automatically correct the load impedance to match the matching point (50Ω). It has become. In order to perform this automatic matching, a circuit that measures load impedance, a controller that variably controls the impedance position of each variable reactance element through a step motor so that the measured value of load impedance matches the matching point (50Ω), etc. are used. It is done.

JP-A-11-61456

  In a high frequency excitation type plasma processing apparatus, the RF power is one of the main parameters of the plasma process, and is selected in a wide range according to the type / content of the process or other conditions. In particular, the amount of RF power input varies greatly depending on the material of the material to be etched, and a single plasma etching apparatus ranging from a recipe for setting RF power of about several tens of watts to a recipe for setting RF power of about several kW. It ’s getting better.

  However, a normal high frequency power source used in a plasma processing apparatus has a limited dynamic range of RF output characteristics, and it is difficult to accurately output a low power of about several tens of watts at a rated output of several kW, resulting in variations. Cheap. On the other hand, plasmas that are ignited or generated with such a low power of about several tens of watts generally have poor stability, high plasma impedance, and large fluctuations. For this reason, the matching unit cannot smoothly follow, causing problems such as reflecting power to the high-frequency power supply and causing hunting to determine a matching point for a long time.

  The present invention has been made in view of the problems of the prior art, and is an RF power input to plasma in a high-frequency power feeding unit having an impedance matching function for supplying a high frequency from a high-frequency power source to plasma in a processing container. Even if the range is changed over a wide range (especially when the low power range is selected) or even when the impedance of the plasma fluctuates significantly, the matching operation of the matching unit is performed stably and smoothly, improving the stability and reproducibility of the plasma process. An object of the present invention is to provide an improved plasma processing apparatus.

  In order to achieve the above object, the plasma processing apparatus of the present invention applies a high frequency of a predetermined frequency from a high frequency power source to a high frequency electrode provided inside or outside a processing vessel in which a desired plasma process is performed via a matching unit. A plasma processing apparatus that applies impedance and matches impedance between the high-frequency power source and its load by the matching unit, wherein a part of the high-frequency power output from the matching unit is disposed in front of the high-frequency electrode. An RF power branching / absorbing part for branching and absorbing is provided.

  In the above configuration, in order to perform a desired plasma process, particularly when the RF power to be applied to the plasma is small, the RF power branching / absorbing unit is operated, and a part of the RF power is branched and absorbed at the front stage of the high-frequency electrode. Let Thereby, the fluctuation range of the apparent load impedance seen from the matching unit is greatly reduced, and the matching unit can perform the matching operation stably and smoothly without causing hunting. In addition, since the reflection of the RF power is small, the RF output operation of the high frequency power supply is also stabilized.

  Further, the high frequency power source outputs RF power that is the sum of the amount that is input to the plasma and the amount that is absorbed by the RF power branching absorption unit. As a result, it is possible to compensate for variations in RF output characteristics in the low power region of the high frequency power supply, thereby reducing the apparatus difference in plasma input RF power and improving process reproducibility.

  In a preferred aspect of the present invention, the RF power branch absorber includes a capacitor and a resistor electrically connected in series between the output terminal of the matching unit and the ground member. Here, the capacitor contributes to drawing RF power from the high-frequency power supply line, and has a capacitance (preferably 200 pF to 1000 pF) larger than the stray capacitance existing between the high-frequency electrode and the surrounding ground member. Good. The resistor contributes to stabilization of plasma input RF power, and preferably has a resistance value of 0.1Ω to 10Ω.

  In another preferred embodiment, the RF power branch absorber has a switch electrically connected in series with a capacitor and a resistor between the output terminal of the matching device and the ground member, and is a recipe for a plasma process. The switch open / close state is controlled according to When the plasma input RF power is selected in a wide range according to the type / content of the process or other conditions, the use / non-use of the RF power branch absorption unit may be arbitrarily switched by a switch.

  In another preferred embodiment, a high-frequency power supply rod having one end coupled to the back surface of the high-frequency electrode and the other end electrically connected to the output terminal of the matching device, and an electric power surrounding the high-frequency power supply rod A grounded cylindrical outer conductor is provided, and an RF power branch absorbing portion is provided between the high-frequency power feeding rod and the outer conductor.

  In this case, as a preferred form of the RF power branching absorption section, a resistor is coupled to the inner wall of the outer conductor with a certain gap space from the high-frequency feeding rod, or a high-frequency power feeding with a certain gap space from the outer conductor. The capacitor has a ring-shaped dielectric that fills the gap space. The ring-shaped dielectric may be inserted in the gap space so as to be insertable / removable. Between the first position (on position) where the gap space is filled and the second position (off position) where the gap is removed from the gap space and retracted. It may be configured to be movable.

  In the RF power branch absorption unit, the resistor may be configured by a variable resistor, or the capacitor may be configured by a variable capacitor. In this case, the resistance value of the variable resistor or the capacitance of the variable capacitor may be varied according to the recipe of the plasma process or based on measurement value information such as RF power or plasma impedance.

  Furthermore, the RF power branch absorber is electrically connected in parallel with each other between the output terminal of the matching unit and the ground member, and the plurality of selections are respectively connected in series with the resistors. It is also possible to suitably adopt a configuration in which each of the plurality of selection switches is controlled according to a plasma process recipe.

  Alternatively, the RF power branch absorber is electrically connected in parallel with each other between the output terminal of the matching unit and the ground member, and the plurality of capacitors are connected in series with the capacitors. It is also possible to preferably employ a switch and control the open / closed state of each of the plurality of selection switches according to the plasma process recipe.

  In a preferred embodiment, a counter electrode facing the high-frequency electrode is provided in the processing container in parallel, and a plasma of the processing gas is generated between the high-frequency electrode and the counter electrode by high-frequency discharge. The high frequency is applied to the high frequency electrode via the matching unit.

  In another preferred embodiment, a substrate to be processed is placed on the high-frequency electrode, and a high-frequency power from a high-frequency power source is used to control the drawing of ions from the plasma of the processing gas generated in the processing container into the substrate. Is applied to the high-frequency electrode through a matching unit.

  According to the plasma processing apparatus of the present invention, the RF power input to the plasma in the high frequency power supply unit having the impedance matching function for supplying the high frequency from the high frequency power source to the plasma in the processing container by the above configuration and operation. Even if the range is changed over a wide range (especially when the low power range is selected) or even when the impedance of the plasma fluctuates significantly, the matching operation of the matching unit is performed stably and smoothly, improving the stability and reproducibility of the plasma process. Can be improved.

It is sectional drawing which shows the structure of the plasma processing apparatus in one Embodiment of this invention. It is sectional drawing which shows typically one Example of RF power branch absorption part integrated in the high frequency electric power feeding part of the plasma processing apparatus of FIG. It is a circuit diagram which shows the equivalent circuit of the high frequency electric power feeding part in embodiment. It is a figure which shows the change of the reactance of the load impedance in a chamber when a plasma sheath capacity | capacitance is changed in a fixed range, and a synthetic | combination load impedance. It is a figure which shows the change of the resistance of the load impedance in a chamber when a plasma sheath capacity | capacitance is changed in a fixed range, and synthetic | combination load impedance. It is a figure which shows an example of the dispersion | variation in the RF output characteristic in a high frequency power supply. It is a figure which compares and shows each plasma injection power at the time of using two high frequency power supplies separately with the conventional apparatus structure. It is a figure which compares and shows each plasma injection power at the time of using two high frequency power supplies separately with the apparatus structure of embodiment. It is a figure which shows the characteristic of the power absorption factor with respect to the capacitor | condenser capacity | capacitance of RF power branch absorption part. It is a circuit diagram which shows the circuit structure of the high frequency electric power feeding part containing the RF power branching absorption part by a 2nd Example. It is a circuit diagram which shows the circuit structure of the high frequency electric power feeding part containing the RF power branching absorption part by a 3rd Example. It is a circuit diagram which shows the circuit structure of the RF power branch absorption part in a 4th Example. It is a circuit diagram which shows the circuit structure of the RF power branching absorption part by one modification of a 4th Example. It is a longitudinal cross-sectional view which shows the whole structure of the plasma processing apparatus of the lower 2 frequency application system by 5th Example. It is a block diagram which shows the structure of the principal part of a high frequency electric power feeding part provided with the RF power branching absorption part by a 5th Example. In a 6th Example, it is sectional drawing which shows typically the structure which equips a high frequency electric power feeding part with RF power branching absorption part and a resistor with a short circuit switch of a serial insertion type. It is a circuit diagram which shows the equivalent circuit of the high frequency electric power feeding part in a 6th Example.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows the configuration of a plasma processing apparatus according to an embodiment of the present invention. The plasma processing apparatus is configured as a cathode-coupled capacitively coupled plasma etching apparatus, and has a cylindrical chamber (processing vessel) 10 made of metal such as aluminum or stainless steel. The chamber 10 is grounded for safety.

  In the chamber 10, a disk-shaped susceptor 12 on which, for example, a semiconductor wafer W is placed as a substrate to be processed is horizontally installed as a lower electrode. The susceptor 12 is made of aluminum, for example, and is supported ungrounded by an insulating cylindrical support 14 made of ceramic, for example, extending vertically upward from the bottom of the chamber 10. An annular exhaust path 18 is formed between the conductive cylindrical support section 16 extending vertically upward from the bottom of the chamber 10 along the outer periphery of the cylindrical support section 14 and the inner wall of the chamber 10. An exhaust port 20 is provided at the bottom. An exhaust device 24 is connected to the exhaust port 20 via an exhaust pipe 22. The exhaust device 24 includes a vacuum pump such as a turbo molecular pump, and can reduce the processing space in the chamber 10 to a desired degree of vacuum. A gate valve 26 that opens and closes the loading / unloading port of the semiconductor wafer W is attached to the side wall of the chamber 10.

  A high frequency power supply 28 is electrically connected to the susceptor 12 via a matching unit 30 and a power feed rod 32. The feed rod 32 is surrounded by a cylindrical conductor cover or outer conductor 33 that is electrically grounded. The high frequency power supply 28 generates a high frequency of, for example, 13.56 MHz suitable for generating plasma of a processing gas by high frequency discharge in the chamber 10 with a desired RF power (for example, a variable range of 0 W to 3 kW) according to the process. Output. The matching unit 30 accommodates a matching unit 34 (FIGS. 3 and 5) for matching between the internal impedance of the high frequency power supply 28 and the impedance on the load side.

  In the middle of the power feed rod 32, an RF power branch absorption unit 44 is provided that branches and absorbs a part of the high-frequency power output from the matching unit 34 before the susceptor 12. The configuration and operation of the RF power branch absorption unit 44 will be described later.

  The susceptor 12 has a diameter or diameter that is slightly larger than that of the semiconductor wafer W. The main surface or upper surface of the susceptor 12 is a central region having the same shape (circular) and substantially the same size as the wafer W in the radial direction, that is, the wafer mounting portion, and an annular periphery extending outside the wafer mounting portion. A semiconductor wafer W to be processed is placed on the wafer placement portion, and a focus ring 36 having an inner diameter slightly larger than the diameter of the semiconductor wafer W is placed on the annular peripheral portion. It is attached. The focus ring 36 is made of, for example, any one of Si, SiC, C, and SiO 2 depending on the material to be etched of the semiconductor wafer W.

  An electrostatic chuck 38 for wafer adsorption is provided on the wafer mounting portion on the upper surface of the susceptor 12. The electrostatic chuck 38 encloses a sheet-like or mesh-like DC electrode 38b in a film-like or plate-like dielectric 38a, and is integrally formed or integrally fixed to the upper surface of the susceptor 12. The DC electrode 38 b is electrically connected to a DC power supply 40 disposed outside the chamber 10 through wiring and a switch 42. By applying a high DC voltage from the DC power supply 40 to the DC electrode 38b, the semiconductor wafer W can be attracted and held on the electrostatic chuck 38 by Coulomb force.

  Inside the susceptor 12, for example, an annular refrigerant chamber 46 extending in the circumferential direction is provided. A refrigerant having a predetermined temperature, such as cooling water, is circulated and supplied to the refrigerant chamber 46 through pipes 48 and 50 from a chiller unit (not shown). In order to control the temperature of the semiconductor wafer W through the susceptor 12, a heat transfer gas such as He gas from a heat transfer gas supply unit (not shown) is supplied from the gas supply pipe 52 and the gas passage 54 inside the susceptor 12. Is supplied between the electrostatic chuck 38 and the semiconductor wafer W.

  On the ceiling of the chamber 10, a shower head 56 that is parallel to the susceptor 12 and also serves as a parallel plate upper electrode is provided directly attached to the chamber 10 (anode grounding). The shower head 56 includes an electrode plate 58 that faces the susceptor 12 and an electrode support 60 that detachably supports the electrode plate 58 from the back (upper) thereof. A gas chamber 62 is provided inside the electrode support 60. A number of gas discharge holes 64 penetrating from the gas chamber 62 toward the susceptor 12 are formed in the electrode support 60 and the electrode plate 58. A space between the electrode plate 58 and the susceptor 12 is a plasma generation space or a processing space. A gas supply pipe 66 from the processing gas supply unit 65 is connected to a gas introduction port 62 a provided in the upper part of the gas chamber 62. The electrode plate 58 is made of, for example, Si, SiC, or C, and the electrode support 60 is made of, for example, anodized aluminum.

  The control unit 68 is composed of, for example, a microcomputer. Each unit in the plasma etching apparatus, for example, the exhaust device 24, the high frequency power supply 28, the matching unit 30, the switch 42 for the electrostatic chuck 38, a chiller unit (not shown), heat transfer, and the like. Individual operations of the gas supply unit (not shown), the processing gas supply unit 65, and the like, and the operation (sequence) of the entire apparatus are controlled.

  In order to perform etching in this plasma etching apparatus, first, the gate valve 26 is opened, and the semiconductor wafer W to be processed is loaded into the chamber 10 and placed on the electrostatic chuck 38. Then, an etching gas (generally a mixed gas) is introduced into the chamber 10 from the processing gas supply unit 65 at a predetermined flow rate and flow rate ratio, and the pressure in the chamber 10 is set to a set value by the exhaust device 24. Further, the high frequency power supply 28 is turned on to output a high frequency (13.56 MHz) at a predetermined RF power, and this high frequency is applied to the susceptor 12 via the matching unit 34 and the power supply rod 32 in the matching unit 30. Further, the heat transfer gas (He gas) is supplied from the heat transfer gas supply unit to the contact interface between the electrostatic chuck 38 and the semiconductor wafer W, and the switch 42 is turned on to turn on the electrostatic chucking force of the electrostatic chuck 38. The heat transfer gas is confined in the contact interface. The etching gas discharged from the shower head 56 is plasma generated by high-frequency discharge between the electrodes 12 and 56, and the film to be processed on the surface of the semiconductor wafer W is etched into a desired pattern by radicals and ions generated by the plasma PR. The

In this plasma etching, the RF power applied to the plasma PR varies depending on the type and content of the process, and varies greatly depending on the material of the film to be etched. For example, in the case of etching a hard film such as SiO ₂ , a high RF power of several kW is normally input, whereas the RF power input in the etching of a soft film such as polysilicon or copper is remarkably low and several Sometimes it is less than 10W. The plasma processing apparatus of this embodiment can cope with a wide variety of plasma processes with different RF powers in a single unit.

  Next, the configuration and operation of the high-frequency power feeding unit, which is a main characteristic part of the plasma etching apparatus, will be described.

  FIG. 2 shows an embodiment of the RF power branching absorption unit 44 attached to the power supply rod 32 in the high frequency power supply unit of the plasma etching apparatus.

  The RF power branch absorbing portion 44 is inserted into the gap space G so as to be insertable / removable, and a ring-shaped resistor 70 coupled or connected to the inner wall of the outer conductor 33 with a certain gap space G from the feed rod 32. And a ring-shaped dielectric 72 also serving as a switch.

  The ring-shaped resistor 70 is preferably composed of a high-frequency fixed resistor (for example, a fixed resistor containing a ceramic sintered body) that is excellent in temperature characteristics or temperature coefficient and has a small inductance component. The value is selected within the range of 0.1Ω to 10Ω. The ring-shaped dielectric 72 also serving as a switch is made of, for example, Teflon (registered trademark) or ceramics. The ring-shaped dielectric 72 is slidably fitted to the power supply rod 32, and fills the gap space G with a first position (on position). It is configured to be movable between a second position (off position) where it escapes from and retracts.

When the ring-shaped dielectric 72 is in the first position and fills the gap space G, the power feed rod 32 and the ring-shaped resistor 70 are capacitively coupled via the ring-shaped dielectric 72. The capacitance of the capacitive coupling or the capacitor C ₇₂ can be arbitrarily selected according to the area of the ring-shaped resistor 70, the distance interval of the gap space G, and the dielectric constant of the ring-shaped dielectric 72, and is included in the in-chamber load impedance described later. A value larger than the RF electrode stray capacitance _CFL is preferable. When the ring-shaped dielectric 72 is in the second position and is retracted out of the gap space G, a capacitively coupled capacitor C ₇₂ is formed between the power supply rod 32 and the ring-shaped resistor 70. Instead, both (32, 70) are electrically separated. The switch operation of the ring-shaped dielectric 72 may be performed manually, or an actuator (not shown) may be used.

  FIG. 3 shows an equivalent circuit of the high-frequency power feeding unit in this plasma etching apparatus, particularly an equivalent circuit of the RF power branching absorption unit 44 and the load in the chamber.

As described above, in this plasma etching apparatus, when plasma etching is performed in the chamber 10, plasma PR is generated between the electrodes 12 and 56 facing in parallel by high-frequency discharge of the etching gas. This plasma PR is physically composed of a bulk plasma portion where electrons and ions are mixed in the same number or in a neutral state and a space charge layer so-called sheath portion in the vicinity of both electrodes 12 and 56, and is electrically good. It is represented as a circuit in which a resistance (hereinafter referred to as “plasma resistance”) R _PR of a bulk plasma portion that can be regarded as a conductive conductor and a capacitor C _{PR of a} sheath portion that can be regarded as a capacitor are connected in series.

Here, the value of the plasma resistance R _PR is usually 0.1Ω to 10Ω, and the value of the sheath capacitor C _PR is usually 50 pF to 500 pF, and varies depending on the type of processing gas, gas pressure, RF power, and the like. To do.

In the chamber 10, there is also a stray capacitance between the susceptor 12 and the surrounding ground member, that is, the conductive cylindrical support portion 16 and the chamber 10, that is, a RF electrode stray capacitance C _FL . The RF electrode stray capacitance C _FL is determined by a hardware structure around the susceptor 12 and usually has a capacitance of 100 pF to 200 pF. Further, the inductance L ₃₂ of the feed bar 32 is also included in the load circuit in normal 100nH following values.

Hereinafter, an impedance composed of the plasma resistance R _PR , the sheath capacitor C _PR , the RF electrode stray capacitance C _FL and the feed rod inductance L ₃₂ will be referred to as an in-chamber load impedance Z ₁₀ .

As shown in FIG. 3, the RF power branching / absorbing unit 44 can be electrically connected in parallel with the plasma PR when viewed from the matching unit 34 accommodated in the matching unit 30 (FIGS. 1 and 2). In the RF power branch absorber 44, the resistor R ₇₀ and the capacitor C ₇₂ are provided by the ring resistor 70 and the ring dielectric 72 (FIG. 2), respectively, and form the impedance Z ₄₄ of the series RC circuit. Switch S ₇₂ is turned on when the ring shaped dielectric 72 is in the first position, it turned off when the ring-shaped dielectric 72 is in the second position.

When the switch S ₇₂ is turned on, the combined load impedance Z _10/44 composed of the in-chamber load impedance Z ₁₀ and the impedance Z _{44 of the} RF power branching absorption unit 44 becomes an apparent load impedance seen from the matching unit 34. Turning off the switch S _72, the RF power branching absorbing portion 44 disengaged from the load of the high-frequency power supply system, the chamber in the load impedance Z ₁₀ is the load impedance apparent on and substantially visible from the matching unit 34.

  In this high-frequency power supply section, resistance components such as the power supply rod 32, the susceptor (lower electrode) 12, and the shower head (upper electrode) 56 are usually several tens mΩ or less and can be ignored in an equivalent circuit. The high frequency power supply 28 and the matching unit 34 are connected by an electric cable 29 having a characteristic impedance of 50Ω.

In this plasma etching apparatus, the RF power branching / absorbing unit 44 is used when the resistance R _{PR of the} plasma _PR or the sheath capacitor C _PR fluctuates greatly when the plasma process is performed (particularly when the plasma input RF power is small). The first function or role is useful in that it is connected in parallel with the plasma PR in the load of the high-frequency power supply system, thereby suppressing the fluctuation of the apparent load impedance seen from the matching unit 34 and matching. This is to stabilize the operation.

4, a sheath capacitor C _PR capacitance change and combined load reactance (imaginary component) X ₁₀ of the chamber in the load impedance Z ₁₀ when the (plasma sheath capacitance) was changed in the range of 50pF~500pF impedance Z _{The change} of _10/44 reactance (imaginary component) X _10/44 is indicated by a dotted line and a solid line, respectively. However, the RF electrode stray capacitance C _FL = 150 pF, the feed rod inductance component L ₃₂ = 90 nH in the chamber load, the capacitor C ₇₂ = 400 pF, and the resistance R ₇₀ = 1Ω in the RF power branching absorber 44. The plasma resistance R _PR is assumed to be 1Ω (constant).

As shown in FIG. 4, with respect to the change in C _PR = 50pF~500pF, the reactance X ₁₀ of the chamber in the load impedance Z ₁₀ relative to changes in the large width of about -51Ω~ about -11Omu, combined load The reactance X _10/44 of the impedance Z _10/44 varies with a small width of about −18Ω to −7Ω. In this way, by adding the RF power branch absorption unit 44 to the load of the high-frequency power feeding system, an effect of reducing the apparent load reactance fluctuation range seen from the matching unit 34 to about ¼ can be obtained.

5, the chamber changes and combined load impedance of the resistance (real component) R ₁₀ of the load impedance Z ₁₀ when the resistance value of the plasma resistance R _PR (the plasma resistance) varied from 0.5Ω~5Ω The _change of the resistance (real number component) R _10/44 of Z _10/44 is shown by a dotted line and a solid line, respectively. However, in the same manner as described above, the RF electrode stray capacitance C _FL = 150 pF, the feed rod inductance L ₃₂ = 90 nH at the in-chamber load, the capacitor C ₇₂ = 400 pF, and the resistance R ₇₀ = 1Ω at the RF power branch absorber 44. Also, it is assumed the volume of the sheath capacitor C _PR and 100 pF (constant).

As shown in FIG. 5, the resistance R ₁₀ of the in-chamber load impedance Z ₁₀ varies in a large range of about 0.07Ω to about −0.8Ω for a change of R _PR = 0.5Ω to 5Ω. In contrast, the resistance R _10/44 of the combined load impedance Z _10/44 varies with a small width of about −0.34Ω to −0.48Ω. In this manner, by adding the RF power branching absorption unit 44 to the load of the high-frequency power feeding system, an effect of reducing the apparent load resistance fluctuation range seen from the matching unit 34 to about 1/5 can be obtained.

  In general, in a process with low plasma input RF power, the plasma impedance is high and easily fluctuates. In particular, immediately after plasma ignition, it fluctuates unstably. When the fluctuation of the load reactance or the load resistance visible from the matching unit 34 is large and the matching unit 34 cannot follow it, the RF power is reflected at the entrance of the matching unit 34, and the RF power enters the plasma PR smoothly. It becomes difficult and the plasma process becomes unstable. Further, when the reflection of RF power exceeds a certain limit, a protection function works on the high frequency power supply 28 side to lower or stop the RF output, thereby undesirably interrupting the plasma process.

  However, in this embodiment, the RF power branch absorption unit 44 is added to the load of the high-frequency power feeding system, and the RF power branch absorption unit 44 absorbs a part or most of the RF power supplied to the load. Thus, the fluctuation range of the apparent load impedance that can be seen from the matching unit 34 can be significantly reduced. This makes it easier for the matching unit 34 to follow, and the reflection of the RF power is reduced. RF power is supplied smoothly and the plasma process is stabilized. Further, since the reflection of the RF power is small, the RF output operation of the high frequency power supply 28 is also stabilized.

In this way, even if the impedance (R _PR , C _PR ) of the plasma PR fluctuates greatly, the impedance fluctuation on the plasma PR side is hidden behind due to the presence of the RF power branching absorption unit 44 that absorbs the RF power before that. The apparent load impedance Z _10/44 visible from the matching unit 34 does not vary much. Thereby, the matching unit 34 can perform the matching operation stably and smoothly without causing hunting.

  Further, by providing the RF power branching absorption section 44, as shown below, even when the plasma input RF power is small, the effect of improving the reproducibility of the plasma process by compensating for the variation in the RF output characteristics of the high frequency power source is also obtained. It is done.

  FIG. 6 shows an example of RF output characteristics of two high frequency power supplies A and B that can be used as the high frequency power supply 28 for the plasma etching apparatus of FIG. As shown in FIG. 6A, when viewed in a macro range of 0 V to 2000 W, the RF output characteristics of the high frequency power supplies A and B are both ideal characteristics with an inclination of 45 degrees passing through the origin (0, 0). looks like. However, as shown in FIG. 6B, when the low power region of 0 V to 100 W is enlarged, the RF output characteristics of the high frequency power supplies A and B are about 12 W and about 5 W on the positive side from the ideal characteristics, respectively. You can see that it is shifted.

  In the plasma etching apparatus of FIG. 1, an apparatus configuration in which the RF power branch absorption unit 44 is omitted and the high frequency power supplies A and B are individually used for the high frequency power supply 28 is considered. In such a device configuration, that is, a conventional device configuration, if the plasma process is performed with a low RF power setting value near 50 W, for example, the RF output characteristics of both the high-frequency power supplies A and B have the above-described variations. As shown in FIG. 7A, the RF power actually applied to the plasma is about 52 W in the conventional apparatus configuration using the high-frequency power source A, whereas it is about 46 W in the conventional apparatus configuration using the high-frequency power source B. And a machine difference of about 13% occurs. When the difference in the RF power applied to the plasma becomes this large, the process reproducibility is affected. In the simulation of FIG. 7A, the set value of the power output is 40W.

  On the other hand, in the configuration (apparatus configuration of the embodiment) in which the high frequency power sources A and B are individually used for the high frequency power source 28 in the plasma etching apparatus of FIG. When the plasma process of RF power set value = 50 W) is performed, as shown in FIG. 7B, the RF power actually applied to the plasma in each of the apparatuses using the high-frequency power sources A and B is around 50 W. Can be reduced to about 0.6%. In the simulation of FIG. 7B, the set value of the power supply output is set to 610W.

  As described above, in the apparatus configuration of the embodiment, in order to input the RF power of 50 W to the plasma, the RF power 28 (A, B) outputs the RF power of 610 W, and most of the difference (about 560 W) (about 90%) is absorbed by the RF power branching absorption unit 44.

FIG. 8 shows a relationship (characteristic) between the capacitance (capacitance) of the capacitor C ₇₂ and the RF power absorption rate in the RF power branching absorption unit 44. Note that the resistance R ₇₀ = 1Ω. As shown in the figure, the characteristic of the logarithmic function is shown in the range of C ₇₂ = 25 pF to 1000 pF, about 75% at 200 pF, about 85% at 300 pF, about 92% at 500 pF, about 96% at 600 pF, and about 96% at 800 pF. Saturates to about 100%. As described above, the more RF power is absorbed by the RF power branching / absorbing unit 44, the greater the effect of stabilizing the matching operation and reducing the mechanical difference of the plasma input RF power. However, the net RF power input efficiency with respect to the plasma PR increases. descend.

That is, if the capacitance of the capacitor C ₇₂ is small, the RF power absorption rate in the RF power branching absorption unit is small, and if the capacitance of the capacitor C ₇₂ is large, the charging efficiency to the chamber 10 is deteriorated.

Considering the RF power absorption rate, the capacitance of the capacitor C ₇₂ is 200 larger than the RF electrode stray capacitance C _FL (about 200 pF at maximum) out of 100 to 1000 pF corresponding to twice the sheath capacitor C _PR (50 to 500 pF). ˜1000 pF is preferred. Furthermore, considering the RF power input efficiency to the chamber 10, the capacitance of the capacitor C ₇₂ is most preferably 300 pF to 500 pF.

  As described above, the provision of the RF power branching / absorbing unit 44 uses or consumes more RF power than the net RF power input to the plasma PR in the plasma process with low RF power. It is possible to stabilize the matching operation of the matching unit 34 or the RF output of the high frequency power supply 28 to reduce the machine difference (variation) between a plurality of plasma etching apparatuses that perform the plasma process of the same recipe. This can greatly improve the reproducibility and reliability of the plasma process.

Incidentally, the net power, i.e. the effective power consumed by the RF power branching absorbing portion 44 is dependent on the resistance value of the resistor R _70. The impedance Z ₄₄ of the RF power branch absorber 44 is dominated by the reactance of the capacitor C ₇₂ , and the branch current flowing through the RF power branch absorber 44 depends on the capacitance of the capacitor C ₇₂ . Therefore, the higher the resistance value of the resistor R _70, the higher the power consumption of the RF power branch absorbing unit 44, and the lower the resistance value of the resistor R ₇₀ , the lower the power consumption of the RF power branch absorbing unit 44. However, if the resistance value of the resistor R ₇₀ is extremely low, the resistance R _10/44 of the combined load impedance Z _10/44 becomes too small, and the RF power transmission efficiency to the load of the high-frequency power feeding section becomes remarkably and indefinite. And the plasma process becomes unstable. Therefore, it is not good that the resistance value of the resistor R ₇₀ is too low, and an optimum value may be selected.

In this embodiment, the resistor R ₇₀ of the RF power branching absorber 44 is a fixed resistor, and the resistance value cannot be arbitrarily varied. Therefore, the resistance value of the resistor R ₇₀ is preferably selected within the range of 0.1Ω to 10Ω, which is the same as the plasma load resistance, from the viewpoint of achieving both RF power consumption efficiency and transmission efficiency.

Further, when the RF power specified in the process recipe is never low, for example, when the power is 100 W or more, the switch S ₇₂ is turned off (opened) to electrically connect the RF power branch absorption unit 44 from the plasma load circuit. It is preferable to remove it.

  In the first embodiment described above, the RF power branching absorption part 44 is attached in the middle of the power feeding rod 32 in the high frequency power feeding part. However, as a second embodiment, as shown in FIG. 9, an RF power branch absorption unit 74 having the same function as the RF power branch absorption unit 44 is incorporated in the matching unit 30 together with the matching unit 34. In this case, the equivalent circuit is the same as that of the first embodiment (FIG. 3).

  9, the high frequency power supply 28 amplifies an oscillator 76 that oscillates and outputs a sine wave having a constant frequency, and amplifies the high frequency power output from the oscillator 76 with a variable amplification factor under the control of the control unit 68. And a power amplifier 78.

  The matching unit 34 includes a matching circuit 80 including at least one variable reactance element, a controller 82 for variably controlling the impedance position of each variable reactance element of the matching circuit 80, and a load including the matching circuit 80. And an RF sensor 84 having a function of measuring impedance.

In the illustrated example, the matching circuit 80 is configured as a T-shaped circuit including two variable capacitors C ₁ and C ₂ and one inductance coil L _1, and the controller 82 passes through the step motors 86 and 88 and the variable capacitors C ₁ and C are connected. The impedance position of ₂ is variably controlled. The RF sensor 84 measures the load-side impedance or reflected wave power viewed from the position. The controller 82 receives various setting values and commands from the control unit 68 and also receives the output signal of the RF sensor 84 so that the load impedance measurement value becomes the matching impedance (50Ω), or the reflected wave power measurement value is The impedance positions of the variable capacitors C ₁ and C ₂ are variably controlled through the step motors 86 and 88 so as to be minimized.

In this embodiment, an RF power branch absorption unit 74 is accommodated in the matching unit 30 together with the matching unit 34. The RF power branch absorption unit 74 includes a fixed resistor R ₇₄ and a fixed capacitor C ₇₄ connected in series between the output terminal or node N of the matching unit 34 and a ground member (not shown) in the matching unit 30. and a switch S _74.

The fixed resistor R ₇₄ is preferably a fixed resistor having excellent high-frequency characteristics, like the fixed resistor R ₇₀ of the first embodiment described above, and its resistance value is preferably in the range of 0.1Ω to 10Ω. May be chosen. The fixed capacitor C ₇₄ is made of, for example, a ceramic capacitor, and the capacitance thereof may preferably be selected within the range of 200 pF to 1000 pF, and most preferably 300 pF to 500 pF. The switch _S74 is an electronic or electric switch that can be turned on / off under the control of the control unit 68, and may be a relay switch, for example. The high frequency output from the high frequency power supply 28 is transmitted to the plasma PR side through the RF power branching absorption unit 74 when the switch _S74 is in the off state, and secondarily at the node N when the switch _S74 is in the on state. Divided, a part branches to the RF power branch absorption part 74 and is absorbed, and the rest is sent to the plasma PR side in the chamber 10.

Further, in this embodiment, in order to improve the temperature characteristics of the fixed resistors R _74, provided temperature controller 90 to maintain the temperature of the fixed resistor R ₇₄ constant. The temperature controller 90 is, for example, a fixed resistor R ₇₄ and thermally coupled water-cooled or air-cooled condenser, energizing period clogging fixed resistor R ₇₄ to hold the switch S ₇₄ to the ON state It may be controlled by the control unit 68 so as to operate only during the period.

Also in this embodiment, since the RF power branch absorption unit 74 is provided in the matching unit 30, the switch S ₇₄ is controlled under the control of the control unit 68 when a very low RF power is set in the process recipe. The RF power branch absorber 74 may be added to a part of the load in the on state. As a result, as in the first embodiment described above, the matching unit 34 can stably perform the matching operation even when the impedance of the plasma PR fluctuates greatly, and a plurality of plasma etchings of the same model that performs the plasma process of the same recipe. It is possible to reduce the machine difference (variation) in the plasma input RF power amount between apparatuses and improve the reproducibility and reliability of the plasma process.

Further, the temperature characteristic in this embodiment, since the fixed resistor R ₇₄ of the RF power branching absorbing portion 74 by temperature controller 90 can be kept at a constant temperature, and minimize the effect of self-heating or ambient temperature It is possible to improve the resistance of the combined load impedance and the accuracy of the plasma input RF power.

  FIG. 10 shows the configuration of the high-frequency power feeding unit according to the third embodiment. The third embodiment is characterized in that the matching unit 30 is provided with a variable impedance type RF power branching and absorbing section 92, and an RF power measurement sensor 94 or a plasma impedance measurement RF sensor 96 is provided. To do. Other parts are the same as those of the second embodiment described above.

The variable impedance type RF power branch absorption unit 92 includes a variable resistor R ₉₂ and a variable capacitor C ₉₂ connected in series between the output terminal of the matching unit 34 and a ground member (not shown) in the matching unit 30. And a switch _S92 .

The variable resistor R ₉₂ can continuously vary the resistance value within the range including 0.1Ω to 10Ω by driving the step motor 98 under the control of the control unit 68. The variable capacitor C ₉₂ can continuously vary the capacitance within the range including 200 pF to 1000 pF (300 pF to 500 pF) by driving the step motor 100 under the control of the control unit 68. The switch S ₉₂ is turned on / off under the control of the control unit 68.

  The RF power measurement sensor 94 includes, for example, a voltage sensor and an arithmetic circuit, measures the voltage at the node N, and absorbs RF power branching from the voltage measurement value and the impedance (predetermined value) of the RF power branching absorption unit 92. The measured value of the RF power absorbed by the unit 92 is calculated, and the calculation result is given to the control unit 68. The RF power measurement sensor 94 can directly monitor the RF power actually supplied to the plasma PR using a commercially available power sensor called a so-called VI probe.

The control unit 68 can monitor the RF power absorbed by the RF power branch absorption unit 92 based on the measurement value information from the RF power measurement sensor 94 and also outputs the RF power to the high frequency power supply 28. It is also possible to monitor the RF power input to the plasma PR by subtracting the RF power absorbed by the RF power branching absorption unit 92 from the RF power, and further, the RF output of the high frequency power supply 28 can be changed or changed. The resistance value of the resistor R ₉₂ and / or the capacitance of the variable capacitor C ₉₂ may be varied.

The RF sensor 96 measures the impedance of the load in the chamber viewed from the position. The control unit 68 may switch, for example, connection (on) / separation (off) of the RF power branch absorption unit 92 based on the in-chamber load impedance information from the RF sensor 96, and further, the RF output of the high frequency power supply 28 may be switched. The resistance value of the variable resistor R ₉₂ and / or the capacitance of the variable capacitor C ₉₂ may be varied.

As a fourth embodiment, instead of the impedance variable RF power branching and absorbing unit 92, an output terminal or node N of a matching unit 34 (not shown) and a grounding member (not shown) in the matching unit 30 between, as shown in FIG. 11, the fixed resistance R _(i), a fixed capacitor C _(i) and the switch S _(i) n pieces in parallel RF power branching absorption series circuit RCS _(i) consisting of (i = 1 to n) A configuration in which an RF power branching absorption parallel network 102 to be connected is provided is also possible.

In this RF power branching absorption parallel network 102, by selecting the on / off state of _n switches S ₍₁₎ , S ₍₂₎ ,. The impedance can be selected in 2 ⁿ −1 ways.

FIG. 12 shows another modification. This RF power branching absorption parallel network 104 selects _n fixed resistors R _{(i) to} R _(n) parallel to one fixed capacitor C _{(0 )} and selects switches S _{(i) to} S _{(n )} Can be connected selectively. The switch S ₍₀₎ is used to select use / non-use of the RF power branching absorption parallel network 104 as a part of the load of the high-frequency transmission line.

Furthermore, as another modification, a configuration in which the fixed capacitor C ₍₀₎ and n fixed resistors R _{(i) to} R _(n) in FIG. 12 are replaced, that is, although not shown, one fixed resistor R _{(0 )} And n fixed capacitors C _{(i) to} C _(n) may be configured as an RF power branching absorption parallel network 104.

  FIG. 13 and FIG. 14 show an embodiment in which the present invention is applied to a capacitively coupled plasma etching apparatus adopting a lower RF two-frequency application method. In the drawing, parts having the same configuration and function as those of the above-described plasma etching apparatus (FIGS. 1 to 12) are denoted by the same reference numerals.

  This plasma etching apparatus is suitable for a first high frequency power supply 106H that outputs a first high frequency HF of a relatively high frequency, for example, 60 MHz, suitable for plasma generation, and for drawing ions from the plasma into the semiconductor wafer W on the susceptor 12. And a second high-frequency power source 106L that outputs a second high-frequency LF of a relatively low frequency, for example, 3.2 MHz, and the first and second high-frequency HF and LF output from both the high-frequency power sources 106H and 106L, respectively. The voltage is applied to the susceptor 12 via the unit 30 and the power feed rod 32.

  Also in this plasma etching apparatus, as shown in FIG. 13, the same RF power branch absorption part 44 as that of the first embodiment can be attached in the middle of the power feed rod 32. Alternatively, as shown in FIG. 14, for example, RF power branching absorbers 74 </ b> H and 74 </ b> L similar to those in the second embodiment can be incorporated in the matching unit 30.

  In the configuration example of FIG. 14, the output terminal of the first high-frequency power source 106H for plasma generation is connected to the power feed rod 32 via the first matching unit 34H and the first RF power branching absorption unit 74H. The output terminal of the second high-frequency power source 106L for controlling the ion attraction is connected to the power feed rod 32 via the second matching unit 34L and the second RF power branch absorption unit 74L. The first and second matching units 34H and 34L may have the same configuration and function as the matching unit 34 (FIGS. 9 and 10) described above.

  As described above, in the present invention, a technique for inserting and connecting an RF power branching absorption section having an appropriate impedance in parallel with a load in the chamber is a plasma input RF such as etching of a soft film such as polysilicon or copper. Great effect in low power plasma process.

  However, in the same plasma etching apparatus, not only a process recipe using such a low RF power region but also a process recipe having a very high RF power (for example, several kW) may be selected. When the plasma input RF power is high, the RF power branch absorption section may be disconnected from the load circuit of the high-frequency transmission system as described above, but it may still be insufficient.

That is, the plasma input RF power is high when the plasma resistance P _RP is low. However, when the plasma resistance P _RP is in a considerably low region (usually 1Ω or less), the RF power transmission efficiency with respect to the plasma load is drastically reduced with the difference (variation) of the matching unit, and the process reproducibility is deteriorated.

  Therefore, in this embodiment, in addition to the parallel insertion type RF power branch absorption section 44 (74, 92, 102, 104) according to the first to fifth embodiments, a series insertion type short-circuit switch is added to the high frequency power feeding section. It is set as the structure provided with the attached resistor 35 (FIG. 15, FIG. 16).

The resistor 35 with the short-circuit switch is a fixed resistor (or fixed resistor) R ₃₅ inserted and connected between the feeding rods 32 (1) and 32 (2) divided into two along the high-frequency transmission path. When, and a the fixed resistor radially outwardly at the feed rod R ₃₅ 32 (1), 32 tubular conductor S ₃₅ for short-circuiting switch which is slidably mounted (2).

The fixed resistor R ₃₅ is preferably composed of a high-frequency fixed resistor (for example, a fixed resistor containing a ceramic sintered body) having excellent temperature characteristics or temperature coefficient and having a small inductance component, and its resistance value is preferably It is selected within the range of 0.1Ω to 10Ω. Tubular conductor S ₃₅ is made higher metal e.g. copper conductivity, feed bar 32 across the fixed resistor R ₃₅ (1), a first position connecting to both 32 (2) (a solid line in FIG. And a second position (a position indicated by an imaginary line in the drawing) connected to only one of the power supply rods 32 (1) and 32 (2).

When the tubular conductor S ₃₅ is switched to the first position, the feed bar 32 (1), 32 (2) between is short-circuited through the tubular conductor S _35, the fixed resistor R ₃₅ Almost no high frequency flows. When the cylindrical conductor _S35 is switched to the second position, the cylindrical conductor _S35 is substantially in a floating state, and instead the fixed resistor _R35 is energized to pass all of the high frequency. ing. Switch operation of the tubular conductor S ₃₅ may be performed manually, or may be used actuator. A conductive member (not shown) may be provided between the cylindrical conductor _S35 and the power feed rods 32 (1) and 32 (2) to increase electrical conductivity and reduce sliding friction.

As shown in FIG. 15, the RF power branching and absorbing portion 44 has a configuration in which the arrangement positions of the ring resistor R ₇₀ and the ring dielectric C ₇₂ are replaced in the radial direction between the feed rod 32 and the outer conductor 33. Is possible. In the configuration of FIG. 15, the ring-shaped resistor R ₇₀ is coupled to the outer peripheral surface of the lower feed rod 32 (1) with a certain gap space G from the outer conductor 33, and the ring-shaped dielectric C _{72 connects the} switch S ₇₀ . In addition, it is inserted into the gap space G so as to be insertable / removable.

Usually, both the RF power branch absorber 44 and the resistor 35 with the short-circuit switch may be selectively used according to the process recipe. For example, the following process plasma applied RF power (setting value) is 100W, the fixed resistors R ₇₀ and capacitor C ₇₂ and switches on-off switch S ₇₂ in RF power branching absorbing portion 44 parallel to the chamber load a is inserted connecting the fixed resistor R ₃₅ is switched to select the short-circuit switch S ₃₅ in the short-circuit switch with the resistor 35 may be removed from the high-frequency transmission line. The operation in this case is exactly the same as in the above-described embodiment.

Further, in a process in which the plasma input RF power (set value) is, for example, several kW or more and the value of the plasma resistance R _PR is lower than 1Ω, the short-circuit switch S ₃₅ is switched off in the resistor 35 with the short-circuit switch. The fixed resistor R ₃₅ is inserted and connected in series with the plasma PR, and the cutoff switch S ₇₂ is switched off in the RF power branch absorption unit 44 to remove the fixed resistor R ₇₀ and the capacitor C ₇₂ from the high-frequency transmission line. Good.

  Thus, by inserting and connecting the resistor 35 in series on the high-frequency transmission line, an effect of increasing the apparent load resistance seen from the matching unit 34 is obtained, whereby the matching operation of the matching unit 34 and the RF transmission are obtained. It becomes possible to stabilize the characteristics. In this case as well, it is possible to greatly reduce machine differences (variations) between a plurality of plasma etching apparatuses that perform the plasma process of the same recipe, thereby greatly improving the reproducibility and reliability of the plasma process. Can do.

In addition, the structure which arrange | positions the resistor 35 with a short circuit switch in the front | former stage of the RF power branch absorption part 44 on the high frequency transmission line is also possible. In addition, it is possible to incorporate the resistor 35 with a short-circuit switch into the matching unit 30 together with the RF power branching absorption unit 74 (92, 102, 104), or in this case, the resistor R ₃₅ , capacitance Commercially available resistor elements, capacitors, and open / close switches can be used for C ₃₅ and the short-circuit switch S ₃₅ , respectively. A configuration using a variable resistor or a parallel resistor network for the resistor R ₃₅ is also possible.

Other embodiments

In the above-described embodiment, the RF power branch absorption unit 74 (92, 102, 104) with a switch is inserted and connected between the matching unit and the grounding member before the susceptor (high frequency electrode) 12 in the high frequency power supply system of the plasma processing apparatus. It was the composition to do. However, as another embodiment, cut-off switch _{S 72 (S 74, S 92} , S (0), S (i)) by omitting resistor _{R 70 (R 74, R 92} , R (i)) and A configuration in which the capacitor C ₇₂ (C ₇₄ , C ₉₂ , C _(i) ) is always inserted and connected to the high-frequency power supply line is also possible. In particular, when the type or recipe of the plasma process to be performed is almost fixed and it is known that the set value of the susceptor input RF power is always several tens of watts or less, a resistor having a resistance value of 0.1Ω to 10Ω. Instrument _{R 70 (R 74, R 92} , R (i)) and 200pF~1000pF capacitor C ₇₂ with a capacitance of _{(300pF~500pF) (C 74, C} 92, C (i)) without the cut-off switch to Thus, it is possible to suitably adopt a configuration in which the high frequency power supply line is always inserted and connected.

  In the capacitively coupled plasma etching apparatus of the above embodiment, the present invention can also be applied to a method of connecting a high frequency power source for plasma generation to a shower head (upper electrode) as a method of connecting a high frequency power source to parallel plate electrodes. .

  The present invention is not limited to a capacitively coupled plasma etching apparatus, and an inductively coupled plasma processing apparatus that generates plasma under a dielectric magnetic field by arranging a coil-type high-frequency electrode on or around the upper surface of a chamber, The present invention can be applied to a microwave plasma processing apparatus or the like that generates plasma using microwave power, and can also be applied to other plasma processing apparatuses such as plasma CVD, plasma oxidation, plasma nitridation, and sputtering. Further, the substrate to be processed in the present invention is not limited to a semiconductor wafer, and various substrates for flat panel displays, photomasks, CD substrates, printed substrates, and the like are also possible.

10 chamber (processing vessel)
12 Susceptor (lower electrode)
24 exhaust device 28 high frequency power supply 30 matching unit 32 feeding rod 32 (1) first feeding rod 32 (2) second feeding rod 34, 34H, 34L matching device 44, 74, 92, 102, 104 RF power branch absorption unit 56 Shower head (upper electrode)
65 the processing gas supply unit 68 control unit 70 a ring-shaped resistor 72 ring-shaped dielectric 106H, 106L high-frequency power supply R _70, R ₇₄ fixed resistor R ₉₂ variable resistor _{R (1) ·· R (n} ) fixed resistor C ₇₂ , C ₇₄ fixed capacitor C ₉₂ variable capacitor C ₍₁₎ · · C _(n) fixed capacitor S ₇₂ , S ₇₄ , S _92, S ₍₀₎ cutoff switch S ₍₁₎ · · S _(n) cutoff / selection Switch

Claims (15)

A high frequency of a predetermined frequency is applied from a high frequency power source to a high frequency electrode provided inside or outside a processing vessel in which a desired plasma process is performed, and between the high frequency power source and its load by the matching device. A plasma processing apparatus for matching impedance,
A plasma processing apparatus having an RF power branching and absorbing unit that divides and absorbs a part of the high-frequency power output from the matching unit at a front stage of the high-frequency electrode. The RF power branch absorber includes a capacitor and a resistor electrically connected in series between the output terminal of the matching unit and a ground member.
The plasma processing apparatus according to claim 1.   The plasma processing apparatus according to claim 2, wherein a resistance value of the resistor is 0.1Ω to 10Ω. The capacitance of the capacitor is larger than the capacitance of the stray capacitance existing between the high-frequency electrode and the surrounding ground member.
The plasma processing apparatus of Claim 2 or Claim 3.   The plasma processing apparatus according to claim 2, wherein the capacitor has a capacitance of 200 pF to 1000 pF. The RF power branch absorption unit includes a switch electrically connected in series with the capacitor and the resistor between an output terminal of the matching unit and a grounding member, and according to a recipe of the plasma process, Control the open / close state of the switch,
The plasma processing apparatus as described in any one of Claims 2-5. A high-frequency power supply rod having one end coupled to the back surface of the high-frequency electrode and the other end electrically connected to the output terminal of the matching unit, and an electrically grounded cylindrical outer surrounding the high-frequency power supply rod A conductor,
Providing the RF power branch absorbing portion between the high-frequency feed rod and the outer conductor;
The plasma processing apparatus as described in any one of Claims 1-6. The resistor is coupled to the inner wall of the outer conductor with a certain gap space from the high-frequency power feeding rod, or to the outer peripheral surface of the high-frequency power feeding rod with a certain gap space separated from the outer conductor. A resistor of shape,
The capacitor has a ring-shaped dielectric filling the gap space;
The plasma processing apparatus according to claim 7. The ring-shaped dielectric is movable between a first position that fills the gap space and a second position that exits and retracts from the gap space;
The plasma processing apparatus according to claim 8.   The plasma processing apparatus according to claim 2, wherein the resistor is a variable resistor. The RF power branching and absorption unit includes a plurality of resistors electrically connected in parallel between the output terminal of the matching unit and the ground member, and a plurality of selection switches connected in series with the plurality of resistors, respectively. And
Controlling the open / closed state of each of the plurality of selection switches according to the plasma process recipe;
The plasma processing apparatus according to any one of claims 1 to 7.   The plasma processing apparatus according to any one of claims 2 to 7, 10, and 11, wherein the capacitor is a variable capacitor. The RF power branching absorption unit includes a plurality of capacitors electrically connected in parallel between the output terminal of the matching unit and the ground member, and a plurality of selection switches connected in series with the plurality of capacitors, respectively. And
Controlling the open / closed state of each of the plurality of selection switches according to the plasma process recipe;
The plasma processing apparatus according to any one of claims 1 to 7, 10, and 11. A counter electrode facing in parallel with the high-frequency electrode is provided in the processing container,
In order to generate plasma of the processing gas by high frequency discharge between the high frequency electrode and the counter electrode, the high frequency from the high frequency power source is applied to the high frequency electrode through the matching unit,
The plasma processing apparatus as described in any one of Claims 1-13. A substrate to be processed is placed on the high-frequency electrode,
The high frequency from the high frequency power source is applied to the high frequency electrode via the matching unit in order to control the drawing of ions from the plasma of the processing gas generated in the processing container into the substrate.
The plasma processing apparatus as described in any one of Claims 1-13.

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