JP2014099585A - Plasma processing device - Google Patents

Abstract

In providing a filter unit on a heater power supply line that electrically connects a heating element inside a mounting table arranged in a processing vessel and a heater power source arranged outside the processing vessel, an electron density on the mounting table is provided. Minimize the impact on the in-plane uniformity of distribution and process characteristics.
In this plasma processing apparatus, a heating element 50 provided inside a susceptor 12 includes an internal conductor 51 passing through the susceptor 12, a feed conductor 52 that vertically cuts a space SP, a filter unit 54, and an electric cable 56. And is electrically connected to a heater power supply 58 (IN) outside the chamber 10. The casing 110 of the filter unit 54 is vertically fitted from the bottom of the chamber 10 into an opening 114 formed in the bottom wall (base) 10a of the chamber 10 adjacent to the cylindrical conductor cover 42 surrounding the power supply rod 40. It is physically and electrically coupled to the chamber bottom wall 10a.
[Selection] Figure 2

Description

  The present invention relates to a plasma processing apparatus for performing plasma processing on a substrate to be processed using high frequency, and in particular, a heater power supply line via a high frequency electrode and a heating element provided on a mounting table for mounting the substrate to be processed in a processing container. The present invention relates to a plasma processing apparatus including a filter for blocking incoming high frequency noise.

  In microfabrication for manufacturing semiconductor devices using plasma or FPD (Flat Panel Display), control of plasma density distribution on the substrate to be processed (semiconductor wafer, glass substrate, etc.) and control of substrate temperature or temperature distribution. Is very important. If the temperature control of the substrate is not properly performed, the substrate surface reaction and thus the uniformity of process characteristics cannot be secured, and the manufacturing yield of the semiconductor device or the display device is lowered.

  Generally, a mounting table or susceptor for mounting a substrate to be processed in a chamber of a plasma processing apparatus, particularly a capacitively coupled plasma processing apparatus, functions as a high-frequency electrode that applies a high frequency to a plasma space, and electrostatically attracts the substrate. And a function of a temperature control unit for controlling the substrate to a predetermined temperature by heat transfer. Regarding the temperature control function, it is desired that the distribution of heat input characteristics to the substrate due to non-uniformity of radiant heat from plasma and chamber walls and the heat distribution by the substrate support structure can be corrected appropriately.

  Conventionally, in order to control the temperature of the susceptor and thus the temperature of the substrate, a heater system in which a heating element that generates heat by energization is incorporated in the susceptor and the Joule heat generated by the heating element is controlled is often used. However, when the heater method is adopted, a part of the high frequency applied from the high frequency power source to the high frequency electrode of the susceptor easily enters the heater power supply line via the heating element. If high-frequency noise passes through the heater power supply line and reaches the heater power supply, the operation or performance of the heater power supply may be impaired. Further, when a high-frequency current flows on the heater power supply line, high-frequency power is wasted. Under such circumstances, it is customary to provide a filter on the heater power supply line for attenuating or preventing high-frequency noise coming from a heating element with a built-in susceptor.

  In the patent document 1, the present applicant provides an air core coil having a very large inductance at the first stage of this type of filter, and this air core coil is placed in a conductive casing that is installed near (usually below) the susceptor. Discloses a plasma processing apparatus. In this plasma processing apparatus, when a single high frequency, particularly, a high frequency of 13.56 MHz or less is applied to the high frequency electrode inside the susceptor, the filter configured as described above using the air-core coil functions effectively, and the heater power supply line The high frequency noise of 13.56 MHz or less can be efficiently and stably interrupted while flowing a large heater current of 30 A or more.

  Further, the present applicant discloses in Patent Document 2 a technique for improving the filter performance for blocking high-frequency high-frequency noise entering the heater power supply line from the susceptor in the processing container in the plasma processing apparatus. This filter technology utilizes the regular multiple parallel resonance characteristics of the distributed constant line so that a high frequency of a low frequency as well as a high frequency (for example, 27 MHz or more) is applied to the high frequency electrode inside the susceptor. A single air-core coil can be used for the coil housed in the casing.

JP2008-198902 JP2011-135052

  However, in a conventional plasma processing apparatus having a filter for blocking high-frequency noise that enters the heater power supply line via the high-frequency electrode and the heating element inside the susceptor, the position of the filter directly under the susceptor and the heater power supply The problem is that the routing of the line adversely affects the electron density distribution on the susceptor and the in-plane uniformity of the process characteristics, and further adversely affects the frequency-impedance characteristics of the filter.

  The present invention solves such a problem of the prior art, and is a heater power supply that electrically connects a heating element inside a mounting table arranged in a processing container and a heater power source arranged outside the processing container. When a filter unit is provided on a line, a plasma processing apparatus that minimizes the influence on the in-plane uniformity of the electron density distribution and process characteristics on the mounting table and obtains stable frequency-impedance characteristics in the filter unit. I will provide a.

  A plasma processing apparatus according to the present invention includes a processing container in which plasma processing is performed, and a mounting table that is disposed on a plate-like conductive base in the processing container via a space and mounts and holds a substrate to be processed. A high-frequency electrode provided on the mounting table, a high-frequency power supply unit for applying a high frequency of a certain frequency to the high-frequency electrode, a heating element provided on the mounting table, and the heating element outside the processing container A heater power supply line for electrically connecting to a heater power supply disposed, a coil for attenuating or preventing high-frequency noise entering the heater power supply line via the heating element, and this coil A filter unit having a casing for accommodating the filter unit, and the filter unit is configured so that an upper end of the casing is flush with an upper surface of the base just below the mounting table. Is arranged lower than the upper surface of the base, and an opening through which the heater power supply line passes without contact is formed in the base, and the heater power supply line is located inside or below the opening of the base. A pin-shaped or bar-shaped first conductor extending through the space from the first terminal to the lower surface of the mounting table.

  In said apparatus structure, it is set as the arrangement structure which cannot put a filter unit in the space immediately under a mounting base. And, the upper end of the casing of the filter unit is directly below the mounting table and at the same height as the upper surface of the base or lower than the upper surface of the base, and the coil accommodated in the casing is attached to the opening of the base. Since it is disposed at a position lower than the upper surface of the base at the ground potential, it is electromagnetically shielded from the high-frequency electrode by the base, is not projected onto the plasma generation space, and does not become a singular point that disturbs the plasma density distribution.

  According to the plasma processing apparatus of the present invention, the heater that electrically connects the heating element inside the mounting table arranged in the processing container and the heater power source arranged outside the processing container by the configuration and operation as described above. When the filter unit is provided on the power supply line, the influence on the in-plane uniformity of the electron density distribution and process characteristics on the mounting table can be minimized, and a stable frequency-impedance characteristic can be obtained in the filter unit.

It is sectional drawing which shows the structure of the plasma processing apparatus in one Embodiment of this invention. It is a schematic plan view which shows the structure of the heat generating body provided in the susceptor of the said plasma processing apparatus. It is a figure which shows the circuit structure of the heater electric power feeding part for supplying electric power to the heat generating body in the said susceptor. It is sectional drawing which shows the physical structure and arrangement configuration of the filter unit in embodiment. It is a perspective view which shows the external appearance structure of the coil winding of two systems of air-core coils with which a common rod axis | shaft is mounted | worn in the said filter unit. It is a top view which shows the structure of the upper end part of the said filter unit. It is a longitudinal cross-sectional view which shows the layout of the routing of the heater power supply line inside and immediately below the septa 12. FIG. 6 is a schematic plan view showing a layout of routing of a heater power supply line inside and immediately below the susceptor. It is a longitudinal cross-sectional view which shows one modification of the routing of the heater power supply line inside the susceptor. It is a figure which shows an example which is not desirable about arrangement | positioning of the filter unit in embodiment, and the routing of a feeding conductor. It is a figure which shows another example which is not desirable about arrangement | positioning of the filter unit in embodiment, and routing of an electric power feeding conductor. It is a figure which shows the equivalent circuit of the high frequency propagation path in which high frequency noise flows in a ground through a heater electric power feeding line in embodiment. It is a figure which shows the frequency-impedance characteristic of the filter in the said equivalent circuit. It is a figure which shows the frequency-impedance characteristic of LC series circuit in the said equivalent circuit. It is sectional drawing which shows the structural example which uses the backplate of an insulator for a susceptor in the said plasma processing apparatus. It is a fragmentary sectional view which shows the structure of the principal part of the apparatus of FIG. It is a schematic plan view which shows an example of arrangement | positioning of the filter unit in the case of making a heat generating body into 3 division type, and routing of a heater feed line in embodiment. It is a schematic plan view which shows another example of arrangement | positioning of the filter unit in the case of making a heat generating body into 3 division types, and routing of a heater feed line. It is a schematic plan view which shows an example of arrangement | positioning of a filter unit in the case of making a heat generating body into 4 types, and the routing of a heater feed line. It is a schematic plan view which shows another example of arrangement | positioning of the filter unit in the case of making a heat generating body into 4 division types, and the routing of a heater feed line. It is a schematic plan view which shows the other example of arrangement | positioning of the filter unit in the case of making a heat generating body into 4 division types, and the routing of a heater feed line. It is a longitudinal cross-sectional view which shows the structural example in the case of making a susceptor movable in an up-down direction in the said plasma processing apparatus. It is sectional drawing which shows an example of the filter unit attachment structure in a microwave plasma processing apparatus. It is sectional drawing which shows another example of the filter unit attachment structure in a microwave plasma processing apparatus. It is sectional drawing which shows an example of the filter unit attachment structure in a microwave plasma processing apparatus. It is sectional drawing which shows another example of the filter unit attachment structure in a microwave plasma processing apparatus. It is sectional drawing which shows another example of the filter unit attachment structure in a microwave plasma processing apparatus. It is sectional drawing which shows the filter unit attachment structure of the Example used for the electromagnetic field simulation for verifying a microwave leakage. It is sectional drawing which shows the filter unit attachment structure of the comparative example used for the electromagnetic field simulation for verifying microwave leakage. It is a figure which shows the result of the electromagnetic field simulation in an Example. It is a figure which shows the result of the electromagnetic field simulation in a comparative example. It is a figure which shows the result of the electromagnetic field simulation at the time of providing a round hole with a diameter of 13 mm between a cover body and a casing in the filter unit attachment structure of FIG. 20A. It is a figure which shows the result of the electromagnetic field simulation at the time of providing a round hole with a diameter of 17 mm in the filter unit mounting structure of FIG. 20A. It is a figure which shows the result of the electromagnetic field simulation at the time of providing a round hole with a diameter of 23 mm in the filter unit attachment structure of FIG. 20A. It is a figure which shows the result of the electromagnetic field simulation at the time of providing a round hole with a diameter of 27 mm in the filter unit mounting structure of FIG. 20A. It is a figure which shows the result of the electromagnetic field simulation at the time of providing the 35 mm aperture round hole in the filter unit attachment structure of FIG. 20A.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.
[Configuration of the entire plasma processing apparatus]

  FIG. 1 shows the configuration of a plasma processing apparatus according to an embodiment of the present invention. This plasma processing apparatus is configured as a capacitively coupled plasma processing apparatus of a lower two-frequency application system, and has a cylindrical chamber (processing container) 10 made of metal such as aluminum or stainless steel. The chamber 10 is grounded.

  In the chamber 10, for example, a disk-shaped mounting table or a susceptor 12 on which a semiconductor wafer W is mounted as a substrate to be processed is disposed horizontally. The susceptor 12 is supported in a non-grounded manner by a cylindrical support portion 14 made of a dielectric, for example, ceramic, extending vertically upward from the bottom of the chamber 10. A space SP communicating with the atmospheric space is formed between the bottom wall (base in this embodiment) 10 a of the chamber 10, the lower surface of the susceptor 12, and the inner wall of the dielectric cylindrical support portion 14. The lower surface of the susceptor 12 is a horizontal flat surface without irregularities, and the upper surface of the bottom wall 10a of the chamber 10 is also a horizontal flat surface without irregularities except for openings (10b, 114) described later.

  An annular exhaust path 18 is formed between the conductive cylindrical support portion 16 extending vertically upward from the bottom wall 10b of the chamber 10 along the outer periphery of the dielectric cylindrical support portion 14 and the inner wall of the chamber 10, and this An exhaust port 20 is provided at the bottom of the exhaust path 18. 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.

  The susceptor 12 is configured by laminating a back plate 28 made of a conductor such as aluminum, a lower high-frequency electrode 30 made of a conductor such as aluminum, and an electrostatic chuck 32 for attracting a wafer in this order from the bottom. First and second high-frequency power sources 34 and 36 are electrically connected to the lower high-frequency electrode 30 via a matching unit 38, a power feed rod 40 and a back plate 28.

  The first high-frequency power source 34 outputs a first high-frequency HF having a constant frequency (usually 27 MHz or higher, preferably 60 MHz or higher) that mainly contributes to plasma generation. On the other hand, the second high-frequency power source 36 outputs a second high-frequency LF having a constant frequency (usually 13 MHz or less) that mainly contributes to the drawing of ions into the semiconductor wafer W on the susceptor 12. The matching unit 38 accommodates first and second matching units (not shown) for matching impedance between the first and second high-frequency power sources 34 and 36 and the plasma load.

  The power feed rod 40 is made of a cylindrical or columnar conductor having a predetermined outer diameter, and its upper end is connected to the center of the lower surface of the susceptor 12 (back plate 28), and its lower end is the above-mentioned first in the matching unit 38. The high frequency output terminals of the first and second matching units are connected. A cylindrical conductor cover 42 is provided between the bottom wall 10 a of the chamber 10 and the matching unit 38 so as to surround the power feed rod 40. More specifically, a circular opening 10b having a predetermined diameter that is slightly larger than the outer diameter of the power supply rod 40 is formed in the bottom wall 10a of the chamber 10, and the upper end of the conductor cover 42 is formed in the chamber opening 10b. In addition to being connected, the lower end of the conductor cover 42 is connected to the ground (return) terminal of the matching unit.

  The susceptor 12 has a diameter or diameter that is slightly larger than that of the semiconductor wafer W. The upper surface of the susceptor 12 is partitioned into a central region that is substantially the same shape (circular) and substantially the same size as the wafer W, that is, a wafer mounting portion, and an annular peripheral portion that extends outside the wafer mounting portion. . A semiconductor wafer W to be processed is placed on the wafer placement portion. On the annular peripheral portion, a ring-shaped plate material so-called a focus ring 44 having an inner diameter larger than the diameter of the semiconductor wafer W is attached. The focus ring 44 is made of, for example, any one of Si, SiC, C, and SiO 2 according to the material to be etched of the semiconductor wafer W.

  The electrostatic chuck 32 provided on the upper surface of the susceptor 12 encloses a DC electrode 32 b in a dielectric layer 32 a that is integrally formed on or fixed to the upper surface of the high-frequency electrode 30. An external DC power supply 45 disposed outside the chamber 10 is electrically connected to the DC electrode 32 b via a switch 46, a high resistance resistor 47 and a DC high voltage line 48. When a high-voltage DC voltage from the DC power supply 45 is applied to the DC electrode 32b, the semiconductor wafer W can be attracted and held on the electrostatic chuck 32 by electrostatic force. The DC high voltage line 48 is a covered wire, passes through the cylindrical lower power feed rod 40, penetrates the back plate 28 and the lower high-frequency electrode 30 of the susceptor 12 from below, and the DC electrode 32 b of the electrostatic chuck 32. It is connected to the.

  In the dielectric layer 32a of the electrostatic chuck 32, the heating element 50 is also sealed together with the DC electrode 32b. The heating element 50 is composed of, for example, a spiral resistance heating wire. In this embodiment, as shown in FIG. 2, an inner heating wire 50 (IN) and an outer heating wire 50 (OUT) in the radial direction of the susceptor 12 It is divided into two.

  Among these, the inner heating wire 50 (IN) includes an inner conductor 51 (IN) passing through the susceptor 12, a power supply conductor 52 (IN) vertically passing through the space SP, a filter unit 54 (IN), and an electric cable 56 (IN). And is electrically connected to a dedicated heater power source 58 (IN) disposed outside the chamber 10. The outer heating wire 50 (OUT) is routed through an inner conductor 51 (OUT) passing through the susceptor 12, a feed conductor 52 (OUT) passing through the space SP, a filter unit 54 (OUT), and an electric cable 56 (OUT). Also, it is electrically connected to a dedicated heater power source 58 (OUT) that is also disposed outside the chamber 10.

  The arrangement configuration of the filter units 54 (IN) and 54 (OUT) and the configuration in which the heater power supply line is routed between the filter units 54 (IN) and 54 (OUT) and the heating element 50 are the main features in this embodiment. This will be described in detail later.

  In the susceptor 12, for example, an annular refrigerant passage 60 extending in the circumferential direction is provided inside the lower high-frequency electrode 30. A refrigerant having a predetermined temperature, such as cooling water cw, is circulated and supplied to the refrigerant passage 60 via a refrigerant supply pipe 62 from a chiller unit (not shown). The temperature of the susceptor 12 can be controlled to decrease according to the temperature of the refrigerant. In order to thermally couple the semiconductor wafer W to the susceptor 12, a heat transfer gas such as He gas from a heat transfer gas supply unit (not shown) is supplied to the electrostatic chuck 32 and the semiconductor via the gas supply pipe 62. It is supplied to the contact interface with the wafer W.

  On the ceiling of the chamber 10, there is provided a shower head 64 that is parallel to the susceptor 12 and also serves as an upper electrode. The shower head 64 includes an electrode plate 66 facing the susceptor 12 and an electrode support 68 that detachably supports the electrode plate 66 from the back (upper side) thereof. A gas chamber 70 is provided inside the electrode support 68. A number of gas discharge holes 72 penetrating from the gas chamber 70 to the susceptor 12 side are formed in the electrode support 68 and the electrode plate 66. A space between the electrode plate 66 and the susceptor 12 is a plasma generation space or a processing space. A gas supply pipe 76 from the processing gas supply unit 74 is connected to the gas introduction port 70 a provided in the upper part of the gas chamber 70. The electrode plate 66 is made of, for example, Si, SiC, or C, and the electrode support 68 is made of, for example, anodized aluminum.

  Each part in this plasma processing apparatus, for example, exhaust device 24, high frequency power supplies 34, 36, switch 46 of DC power supply 45, heater power supplies 58 (IN), 58 (OUT), chiller unit (not shown), heat transfer gas supply section Individual operations such as (not shown) and the processing gas supply unit 74 and the operation (sequence) of the entire apparatus are controlled by a control unit 75 including a microcomputer.

  In this plasma processing apparatus, for example, in order to perform etching, 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 32. Then, an etching gas (single gas or mixed gas) is introduced into the chamber 10 from the processing gas supply unit 74 at a predetermined flow rate, and the pressure in the chamber 10 is set to a set value by the exhaust device 24. Further, the first and second high-frequency power sources 34 and 36 are turned on to output the first high-frequency HF and the second high-frequency LF at predetermined powers. The high-frequency HF and LF are supplied to the matching unit 38 and the power supply rod 40, respectively. To the lower high-frequency electrode 30 of the susceptor 12. Further, the heat transfer gas (He gas) is supplied from the heat transfer gas supply unit to the contact interface between the electrostatic chuck 32 and the semiconductor wafer W, and the electrostatic chuck switch 46 is turned on to perform electrostatic adsorption. The heat transfer gas is confined in the contact interface by force. On the other hand, the heater power supplies 58 (IN) and 58 (OUT) are turned on to cause the inner heating element 50 (IN) and the outer heating element 50 (OUT) to generate heat with independent Joule heat, respectively. Control the temperature distribution to the set value. The etching gas discharged from the shower head 64 is turned into plasma by high-frequency discharge in the plasma generation space between the susceptor 12 and the shower head 64, and the film to be processed on the surface of the semiconductor wafer W is formed by radicals and ions generated by the plasma. It is etched into a desired pattern.

  This capacitively coupled plasma processing apparatus applies a first high-frequency HF having a relatively high frequency (preferably 60 MHz or more) suitable for plasma generation to the lower high-frequency electrode 30 inside the susceptor 12 so that the plasma is in a preferable dissociated state. Density is increased, and high-density plasma can be formed even under lower pressure conditions. At the same time, by applying a second high frequency LF having a relatively low frequency (13 MHz or less) suitable for ion attraction to the lower high frequency electrode 30, the anisotropic property having high selectivity with respect to the semiconductor wafer W on the susceptor 12 is obtained. Etching can be performed.

Further, in this capacitively coupled plasma processing apparatus, the susceptor 12 is simultaneously supplied with cooling of the chiller and heating of the heater, and the heating of the heater is controlled independently at the central portion and the edge portion in the radial direction. Switching or raising / lowering temperature is possible, and the profile of the temperature distribution can be controlled arbitrarily or in various ways.

[Circuit configuration in the filter unit]

  Next, the circuit configuration in the filter units 54 (IN) and 54 (OUT) in this plasma processing apparatus will be described.

  FIG. 3 shows a circuit configuration of a heater power supply unit for supplying power to the heating element 50 for controlling the wafer temperature built in the susceptor 12. In this embodiment, individual heater power supply units having substantially the same circuit configuration are connected to the inner heating wire 50 (IN) and the outer heating wire 50 (OUT) of the heating element 50, respectively. The heat generation amount or the heat generation temperature of 50 (IN) and the outer heating wire 50 (OUT) are controlled independently. In the following description, the configuration and operation of the heater power supply unit with respect to the inner heating wire 50 (IN) will be described. The configuration and operation of the heater power supply unit for the outer heating wire 50 (OUT) are exactly the same.

The heater power supply 58 (IN) is an AC output type power supply that performs, for example, commercial frequency switching (ON / OFF) operation using SSR, and is connected to the inner heating wire 50 (IN) by a closed loop circuit. . More specifically, of the pair of output terminals of the heater power supply 58 (IN), the first output terminal is the first terminal h of the inner heating line 50 (IN) via the first heater power supply line 100 (1). _1A to be electrically connected to the second output terminal is electrically connected to the second terminal h _2A of the inner heating wire 50 through the second heater power supply lines 100 (2) (iN).

  The filter unit 54 (IN) has first and second filters 102 (1) and 102 (2) provided in the middle of the first and second heater power supply lines 100 (1) and 100 (2), respectively. doing. The circuit configurations of both filters 102 (1) and 102 (2) are substantially the same.

More specifically, both filters 102 (1) and 102 (2) have a single coil 104 (1) and 104 (2), respectively. The upper terminals (first terminals) or the filter terminals T (1) and T (2) of the coils 104 (1) and 104 (2) are connected to a pair of power supply conductors 52 (IN1) and 52 (IN2) and a pair of internal terminals. The conductors 51 (IN1) and 51 (IN2) are connected to both terminals h _1A and h _2A of the inner heating wire 50 (IN), respectively. The lower terminals (second terminals) of the coils 104 (1) and 104 (2) are connected to a grounded conductive member (for example, the chamber 10) via the capacitors 106 (1) and 106 (2). Are connected to the first and second output terminals of the heater power supply 58 (IN) via connection points n (1), n (2) and an electric cable (pair cable) 56 (IN), respectively.

In the heater power supply unit configured as described above, the current output from the heater power supply 58 (IN) is the first heater power supply line 100 (1), that is, the electric cable 56 (IN), the coil 104 (1) in the positive cycle. Then, it passes through the feeding conductor 52 (IN1) and the inner conductor 51 (IN1), enters the inner heating wire 50 (IN) from one heating wire terminal h _1A, and generates Joule heat by energization at each part of the inner heating wire 50 (IN). After being generated and exiting from the other heating wire terminal h _2A , the second heater feed line 100 (2), that is, the internal conductor 51 (IN2), the feed conductor 52 (IN2), the coil 104 (2), and the electric cable 56 Return via (IN). In the negative cycle, a current flows through the same circuit in the opposite direction. Since the current of the heater AC output is a commercial frequency, the impedance of the coils 104 (1), 104 (2) or the voltage drop thereof is negligibly small, and is grounded through the capacitors 106 (1), 106 (2). The leakage current that escapes is negligibly small.

[Physical structure and arrangement of filter unit]

  4 to 6 show the physical structure and arrangement of the filter unit 54 (IN) in this embodiment. As shown in FIG. 4, the filter unit 54 (IN) includes a coil 104 (1) of the first filter 102 (1) and a second filter 102 (2) in a cylindrical conductive casing 110 made of, for example, aluminum. Of the first filter 102 in a conductive capacitor box 112 that is coaxially housed and is coupled to the lower end of the casing 110 on the opposite side of the filter terminals T (1), T (2). The capacitor 106 (1) on the (1) side and the capacitor 106 (2) (FIG. 3) on the second filter 102 (2) side are accommodated together.

  The casing 110 is vertically fitted from the outside of the chamber 10 into the opening 114 formed in the bottom wall (base) 10 a of the chamber 10 adjacent to the cylindrical conductor cover 42 (FIG. 1) surrounding the power supply rod 40. It is physically and electrically coupled to the chamber bottom wall 10a. Here, the casing 110 has a chamber bottom so that the upper surfaces of the filter terminals T (1) and T (2) are not higher than the upper surface of the chamber bottom wall 10a (most preferably at the same height). It is attached to the opening 114 of the wall 10a. In this case, it is preferable that the upper end of the casing 110 is not higher than the upper surface of the chamber bottom wall 10a.

  Each of the coils 104 (1) and 104 (2) is an air-core coil, and functions as a power supply line for flowing a sufficiently large current (for example, about 30A) to the inner heating wire 50 (IN) from the heater power supply 52 (IN). In addition, in order to prevent heat generation (power loss), to obtain a very large inductance with an air core without having a magnetic core such as ferrite, and to obtain a large line length, a thick coil wire and a large coil size (For example, the diameter is 22 to 45 mm and the length is 130 to 280 mm).

  In the cylindrical casing 110, both the coils 104 (1) and 104 (2) are formed in a cylindrical or columnar shape made of an insulator, such as a resin, which stands vertically on a lower connector 116 made of an insulator, such as a resin. Along the outer peripheral surface of the rod shaft (bobbin) 118, the coils are spirally wound at the same winding interval and coil length s while being translated while overlapping in the axial direction. As shown in FIG. 5, the coil conductors of both coils 104 (1) and 104 (2) are preferably made of a thin plate or a flat copper wire having the same cross-sectional area, and one air-core coil 104 (2 ) Is covered with an insulating tube 120. Note that the rod shaft 118 can be omitted as long as both the coils 104 (1) and 104 (2) can be integrally and stably held by an adhesive or a support member other than the rod shaft 118.

  The lower ends of the coils 104 (1) and 104 (2) are electrically connected to the connection conductors 122 (1) and 122 (2) in the lower connector 116, respectively. These connection conductors 122 (1) and 122 (2) are connected to connection points n (1) and n (2) and capacitors 106 (1) and 106 (2) (FIG. 3) in the capacitor box 112, respectively. ing.

  An upper connector 124 made of an insulator, such as resin, is coupled to the upper end of the rod shaft 118 at a position close to the upper end of the casing 110. On the upper surface of the upper connector 124, plate-like or block-like filter terminals T (1) and T (2) made of, for example, copper are provided so as to be exposed. These filter terminals T (1) and T (2) are connected to the upper ends of the coils 104 (1) and 104 (2) in the upper connector 124, respectively.

  The upper end of the casing 110 is open. The upper surfaces of the filter terminals T (1) and T (2) are not shielded and face the space SP immediately below the susceptor 12 in an open state. The filter terminals T (1) and T (2) are respectively connected to the lower ends of pin-shaped or rod-shaped power supply conductors 52 (IN1) and 52 (IN2) enclosed in an insulating support rod 126. .

The filter unit 54 (OUT) has the same circuit configuration and physical structure as the filter unit 54 (IN), and the filter unit 54 (IN) is at a position opposite to the power feed rod 40, that is, a point-symmetrical position. And attached to the bottom wall (base) 10a of the chamber 10 (FIG. 8).

[Electrical functions of filter unit]

  In the filter unit 54 (IN) of this embodiment, distribution is made between the coils 104 (1) and 104 (2) of the first and second filters 102 (1) and 102 (2) and the outer conductor casing 110. A constant line 105 is formed.

In general, the characteristic impedance Z _o of the transmission line is given by Z _o = √ (L / C) using the capacitance C and the inductance L per unit length when there is no loss. The wavelength λ is given by the following equation (1).
λ = 2π / (ω√ (LC) (1)

A general distributed constant line (especially a coaxial line) is different in that the center of the line is a rod-shaped cylindrical conductor, whereas the filter unit 54 (IN) uses a cylindrical coil as the central conductor. The inductance L per unit length is considered to be predominantly the inductance due to this cylindrical coil. On the other hand, the capacitance per unit length is defined by the capacitance C of the capacitor formed by the coil surface and the outer conductor. Therefore, also in this filter unit 54 (IN), when the inductance and the capacitance per unit length are L and C, respectively, the distributed constant line given by the characteristic impedance Z _o = √ (L / C) It can be considered that it is formed.

  When the filter unit having such a distributed constant line is viewed from the terminal T side, the opposite side is pseudo short-circuited by a capacitor having a large capacitance (for example, 5000 pF), so that a large impedance is repeated at a constant frequency interval. A frequency-impedance characteristic is obtained. Such impedance characteristics are obtained when the wavelength and the distributed line length are equal.

  In this filter unit 54 (IN), not the winding length of the coils 104 (1) and 104 (2) but the axial coil length s (FIG. 4) is the distributed line length. Since the coils 104 (1) and 104 (2) are used as the central conductor, L can be made much larger and λ can be made smaller than in the case of a rod-shaped cylindrical conductor, so that a relatively short line Although it is long (coil length s), it is possible to realize an effective length equal to or greater than the wavelength, and it is possible to obtain an impedance characteristic that repeats having a large impedance at a relatively short frequency interval.

  Here, on the distributed constant line 105 formed between the coils 104 (1), 104 (2) and the casing (outer conductor) 110, the characteristic impedance (particularly, inductance and capacitance per unit length) is constant. Is desirable. In this regard, in the configuration example shown in the figure, the cylindrical coils 104 (1) and 104 (2) are coaxially arranged in the cylindrical casing (outer conductor) 110. Is satisfied. However, even if there are some irregularities in the gap (distance interval) between the coils 104 (1), 104 (2) and the casing (outer conductor) 110, the tolerance (generally 1/1 of the wavelength of the high frequency to be cut off). 4 or less), the characteristic impedance constant requirement is substantially satisfied.

As described above, each of the filters 102 (1) and 102 (2) can achieve a filter characteristic having multiple parallel resonance and excellent impedance characteristic stability and reproducibility.

[Heater feed line routing configuration]

  7 and 8 show the configuration of routing of the heater power supply lines 100 (1) and 100 (2) inside and immediately below the susceptor 12. FIG. As shown in FIG. 7, the insulating support rod 126 and the power supply conductors 52 (IN 1) and 52 (IN 2) enclosed therein extend straight in the vertical direction without bending in the middle, and vertically cut the space SP. ing. And the front-end | tip part of electric power feeding conductor 52 (IN1) and 52 (IN2) is inserted in the socket terminal 128 electrically insulated and attached to the lower surface of the susceptor 12 (back board 28).

The filter terminals T (1) and T (2) and the socket terminal 128 are located closer to the center of the chamber 10 than the terminals h _1A and h _2A of the inner heating wire 50 (IN) (FIG. 8). The back plate 28 and the lower high-frequency electrode 30 of the susceptor 12 are formed with tunnel-shaped passages 132 (132a, 132b, 132c) through which the internal conductors 51 (IN1) and 51 (IN2) pass (FIG. 7). .

More specifically, inside the back plate 28, a horizontal passage 132 a that extends horizontally from the socket terminal 128 to just below the heating wire terminals h _1A and h _2A , and vertically upward from the end of the horizontal passage 132 a to the upper surface of the back plate 28. A vertical passage 132b extending in the direction is formed. The lower high-frequency electrode 30 is formed with a vertical passage 132c having a through hole extending in the vertical direction at a position overlapping the vertical passage 132b on the back plate 28 side. The inner conductors 51 (IN 1) and 51 (IN 2) are made of, for example, a metal having a high conductivity, such as copper, and are electrically insulated from the back plate 28 and the lower high-frequency electrode 30 by an insulator 134 made of, for example, resin. The socket terminal 128 and the heating wire terminals h _1A and h _2A in the electrostatic chuck 32 are electrically connected through 132 (132a, 132b, 132c). The inner conductors 51 (IN1) and 51 (IN2) may take any form such as a pin shape, a bar shape, or a plate shape.

In order to minimize the insulator 134 provided in the passage 132, as shown in FIG. 9, insulation is provided only under the inner conductors 51 (IN1) and 51 (IN2) in the horizontal passage 132a of the back plate 28. The body 134 may be provided (laid), and the insulator 134 may be omitted entirely in the vertical passage 132b of the back plate 28 and the vertical passage 132 of the lower high-frequency electrode 30.

[Operation in Embodiment]

  This plasma processing apparatus adopts the above-described configuration with respect to the arrangement of the filter units 54 (IN) and 54 (OUT) and the routing of the heater power supply lines 100 (1) and 100 (2) around the susceptor 12. The in-plane uniformity of the plasma density distribution characteristics on the semiconductor layer 12 and the process characteristics (for example, etching rate characteristics) on the semiconductor wafer W can be greatly improved.

  As described above, in a conventional plasma processing apparatus including a heating element built in a susceptor and a filter for preventing or attenuating high frequency noise on a heater power supply line that supplies power to the heating element, a filter unit The location of the heater and the routing of the heater power supply line around the susceptor contribute to the asymmetric structure with respect to the plasma density distribution characteristics on the susceptor and the process characteristics on the semiconductor wafer. Specifically, a part of the high frequency applied from the high frequency power source to the lower high frequency electrode of the susceptor leaks onto the heater power supply line through the heating element, so that the vicinity of the heater power supply line extending in the space immediately below the susceptor The plasma density and the etching rate are lowered so as to be pulled down. That is, the planar image of the heater power supply line extending in the space immediately below the susceptor is reflected or projected on the plasma generation space as a singular point that disturbs the plasma density distribution on the susceptor.

  The inventor analyzed the potential distribution and electric field distribution around the susceptor (especially immediately below) by electromagnetic field calculation. As a result, the potential on the heater power supply line It was found that the voltage was about the same (for example, about several thousand volts), and when it entered the filter unit, it gradually dropped along the coil axis direction due to the impedance of the coil and became several tens of volts at the end of the coil.

  However, in the conventional plasma processing apparatus, the filter unit is disposed in the space between the susceptor and the bottom wall of the chamber, and the heater power supply line (power supply conductor) is routed laterally in the space. In this case, the planar image of the heater power supply line (feeding conductor) extending in the lateral direction in the space and the planar image of the upper surface (lid) of the filter unit are asymmetrical to the plasma density distribution on the susceptor. Projected in a large area.

  Further, in the conventional plasma processing apparatus, the arrangement position of the filter unit (especially the filter unit for the outer heating element) is not taken into consideration even in the radial direction of the chamber, and may be arranged immediately below the peripheral portion of the susceptor. In that case, a high-voltage heater feed line (feed conductor) routed in the space becomes an antenna, and from there to a surrounding ground potential member, for example, a dielectric cylindrical support that easily transmits high frequency High-frequency radio waves may be radiated to the conductive cylindrical support portion (16) having the ground potential via (14), thereby significantly reducing the high-frequency cutoff function of the filter.

  In this regard, the present invention has an arrangement configuration in which the filter units 54 (IN) and 54 (OUT) are not placed in the space SP immediately below the susceptor 12. In particular, in this embodiment, the upper end of the casing 110 of the filter unit 54 (IN) is directly under the susceptor 12 and the same height as the upper surface of the bottom wall (base) 10a of the chamber 10, or from the upper surface of the chamber bottom wall 10a. It is lowered and attached to the opening 114 of the chamber bottom wall 10a. As a result, the coils 104 (1) and 104 (2) housed in the casing 110 are disposed at a position lower than the upper surface of the chamber bottom wall 10a at the ground potential, so that the susceptor 12 is electromagnetically moved by the chamber bottom wall 10a. And is not projected onto the plasma generation space. That is, it does not become a singular point that disturbs the plasma density distribution. The same applies to the coils 104 (1) and 104 (2) on the filter unit 54 (OUT) side.

  On the other hand, the feed conductors 52 (IN 1) and 52 (IN 2) routed in the space SP are projected on the plasma density distribution on the susceptor 12, but extend straight in the vertical direction without bending sideways. The projected area is as small as possible. Moreover, it is located closer to the center of the chamber 10. For this reason, the degree of influence on the plasma density distribution on the susceptor 12 is very small. The same applies to the power supply conductors 52 (OUT1) and 52 (OUT2) on the filter unit 54 (OUT) side.

  The inner conductors 51 (IN 1) and 51 (IN 2) routed inside the susceptor 12 are all contained (hidden) in the conductor back plate 28 and the passage 132 of the lower high-frequency electrode 30. Therefore, the plasma generation space is not affected and there is no possibility of disturbing the plasma density distribution on the susceptor 12.

  Further, in this embodiment, the power supply conductors 52 (IN1) and 52 (IN2) are arranged near the center of the chamber 10 and are separated from the dielectric cylindrical support portion 14, so that the power supply conductors 52 (IN1) and 52 There is no possibility that high-frequency radio waves are radiated from (IN2) to the conductive cylindrical support 16 having the ground potential via the dielectric cylindrical support 14. The same applies to the power supply conductors 52 (OUT1) and 52 (OUT2) on the filter unit 54 (OUT) side.

  Further, in the filter unit 54 (IN), the upper end of the casing 110 is opened, and the filter terminals T (1) and T (2) are exposed and are not shielded and face the space SP immediately below the susceptor 12 in an open state. It is out. Further, not only the power supply conductors 52 (IN 1) and 52 (IN 2), but also the insulating support rod 126 enclosing them does not contact the chamber bottom wall 10 a (the inner surface of the opening 114). As a result, as will be described later, the stray capacitances near the filter terminals T (1) and T (2) are sufficiently reduced to stabilize the frequency-impedance characteristics of the filters 102 (1) and 102 (2). Can do. The same applies to the filter unit 54 (OUT).

10A and 10B, the arrangement of the filter units 54 (IN) and 54 (OUT) and the routing of the feeding conductors 52 (IN1), 52 (IN2), 52 (OUT1), and 52 (OUT2) in this embodiment are as follows. Some undesired examples X _{1 to} X ₅ are shown.

For example, when the feeding conductors 52 (OUT1) and 52 (OUT2) are routed in the lateral direction in the space SP (X _{1 in} FIG. 10A), the feeding conductor 52 projected onto the plasma density distribution on the susceptor 12 as described above. Since the two-dimensional image of (OUT1) and 52 (OUT2) becomes large, it is not desirable. Further, when the power supply conductors 52 (IN1) and 52 (IN2) are routed horizontally in the vicinity of the opening 114 of the chamber bottom wall 10a (X _{2 in} FIG. 10A), the power supply conductors 52 (IN1) and 52 (IN2) are connected to the bottom of the chamber. This is not desirable because the stray capacitance increases as the wall 10a is approached. It is also undesirable to make the casing 110 of the filter unit 54 (OUT) higher than the upper surface of the chamber bottom wall 10a (X _{3 in} FIG. 10A) because that portion is projected onto the plasma density distribution on the susceptor 12.

The feeding conductors 52 (OUT1) and 52 (OUT2) are brought close to the dielectric cylindrical support portion 14 (X _{4 in} FIG. 10B) from the feeding conductors 52 (OUT1) and 52 (OUT2) as described above. This is not desirable because high-frequency electromagnetic waves are likely to be radiated to the conductive cylindrical support 16 having the ground potential via the support 14. For example, the dielectric cylindrical support portion 14 made of ceramic having a relative dielectric constant of 10 has a high frequency permeability equivalent to a space having a thickness of 1/10. That is, the dielectric cylindrical support portion 14 is interposed, so that the power supply conductors 52 (OUT1) and 52 (OUT2) are closer to the conductive cylindrical support portion 16 having the ground potential.

Further, a cover 136 that covers the lower ends of the filter terminals T (1), T (2) or the power feeding conductors 52 (IN1), 52 (IN2) is provided in the opening 114 of the chamber bottom wall 10a (X in FIG. 10B). ₅ ) is undesirable because it projects onto the plasma density distribution on the susceptor 12 if it protrudes above the chamber bottom wall 10a regardless of the material (whether it is a conductor or a dielectric). This is not desirable because the stray capacitance near the filter terminals T (1) and T (2) increases.

  Although not shown, it is not desirable that there are protrusions protruding from the lower surface of the susceptor 12 or the bottom surface 10a of the chamber 10 into the space SP because the plasma density distribution on the susceptor 12 is affected.

  FIG. 11 shows an equivalent circuit of a high-frequency propagation path in which high-frequency noise flows from the high-frequency power supply 34 (36) to the ground through the first heater power supply line 100 (1) in this embodiment. In this equivalent circuit, the capacitor 140 is a capacitance between the high-frequency electrode 30 and the inner heating wire 50 (IN) or the inner conductor 51 (IN1). The resistor 140 is mainly a resistor of the inner heating wire 50 (IN). The inductor 144 is an inductance of the power supply conductor 52 (IN1), and the capacitor 146 is a stray capacitance near the power supply conductor 52 (IN1) and the filter terminal T (1). The stray capacitance and resistance in the filter 102 (1) are ignored (omitted).

  In this equivalent circuit, a high-frequency propagation path from the susceptor 12 to the ground potential via the inductor 144, the capacitor (stray capacitance) 146, the coil 104 (1) in the filter 102 (1) and the capacitor 106 (1) is expected. The frequency-impedance characteristic ZA (f) at this time is, for example, as shown in FIG. Further, the frequency-impedance characteristic ZB (f) when a high-frequency propagation path from the susceptor 12 to the ground potential via the inductor 144 and the capacitor (stray capacitance) 146 is expected is as shown in FIG. 13, for example.

The frequency-impedance characteristic ZA (f) of the filter 102 (1) includes the frequency-impedance characteristic (multiple parallel resonance characteristic) of the distributed constant line 105 formed by the coil 104 (1) and the outer conductor casing 110, and the inductor. The frequency-impedance characteristic ZB (f) of the LC series circuit 150 composed of 144 and a capacitor (stray capacitance) 146 is synthesized. That is, the frequency-impedance characteristic of the distributed constant line 105 is governed by the frequency-impedance characteristic of the LC series circuit 150 located in the preceding stage, and the frequency is increased as the frequency increases toward the series resonance frequency f _SR of the LC series circuit 150. The peak value of the parallel resonance point in the parallel resonance characteristic gradually decreases.

Here, in the frequency-impedance characteristic ZB (f) of the LC series circuit 150, as the capacitance of the capacitor 146 increases, the series resonance frequency f _SR becomes lower as shown in FIG. 13 (f _SR → f _SR '), the impedance in the lower frequency region becomes lower overall (ZB (f) → ZB (f)'). Then, as shown in FIG. 12, the frequency of the filter 102 (1) - even in the impedance characteristics ZA (f), the impedance is low in all the parallel resonance point and a frequency domain lower than the series resonance frequency f _SR (ZA ( f) → ZA (f) ').

Further, when the fundamental frequency of the first high frequency HF for plasma generation is 100 MHz, for example, the frequency of the second harmonic is 200 Mz. Here, for example, as shown in FIG. 13, when the series resonance frequency f _SR moves to a low frequency region and approaches the second harmonic frequency (200 Mz), the second harmonic wave is generated on the heater power supply line 100 (1). A large current flows.

Therefore, in order to stabilize the high-frequency cutoff function of the filter 102 (1), it is important to make the stray capacitance 146 around the power supply conductor 52 (OUT1) and the filter terminal T (1) as small as possible. In this embodiment, as described above, in the filter unit 54 (IN), the upper end of the casing 110 is open, the filter terminal T (1) is exposed, and the space SP just below the susceptor 12 is open without being shielded. Opposite to. Further, not only the power supply conductor 52 (IN1) but also the insulating support rod 126 enclosing it is not in contact with the chamber bottom wall 10a (the inner surface of the opening 114). As a result, the stray capacitance 146 is made as small as possible, the series resonance frequency f _SR of the LC series circuit 150 is set as high as possible, and the frequency-impedance characteristic (particularly the multiplexing) of the filter 102 (1). Parallel resonance characteristics) are stabilized. The same applies to the second heater power supply line (2).

In this embodiment, it is possible to dispose the casing 110 of the filter units 54 (IN) and 54 (OUT) away from the opening 114 of the chamber bottom wall 10a but below the chamber bottom wall 10a, but it is preferable. is not. That is, when the opening 114 of the chamber bottom wall 10a is opened through, this not only becomes a singular point in the reverse direction that raises the plasma density distribution on the susceptor 12, but also the feed conductor 52 (IN1), When 52 (IN2) passes through the opening 114, the stray capacitance 146 around the power supply conductors 52 (IN1) and 52 (IN2) increases. Also, it is not desirable in that dust, dust, moisture, etc. in the atmosphere enter and exit the opening 114. Therefore, the casing 110 of the filter units 54 (IN) and 54 (OUT) is preferably attached so as to close the opening 114 of the chamber bottom wall 10a, and the filter terminals T (1), T ( Most preferably, the upper surface of 2) is mounted so as to be the same height as the upper surface of the chamber bottom wall 10a.

[Other Embodiments or Modifications]

  Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the technical idea.

  For example, in the plasma processing apparatus of the above-described embodiment, as shown in FIGS. 14 and 15, a configuration in which an insulator back plate 152 is provided on the susceptor 12 is also possible. The back plate 152 has an upper surface joined to the upper surface of the lower high-frequency electrode 30 and a lower surface facing the space SP.

  A through hole 153 for passing the power feeding rod 40 to the lower high-frequency electrode 30 side is formed at the center of the back plate 152. Furthermore, power feeding conductors 52 (IN 1), 52 (IN 12) and power feeding conductors 52 (OUT 1), 52 (OUT 2) are located at portions of the back plate 152 located immediately above the filter units 54 (IN), 54 (OUT). Through-holes 154 (IN) and 154 (OUT) are also formed for passing through to the lower high-frequency electrode 30 side.

On the lower surface of the lower high-frequency electrode 30, a socket terminal 156 that receives the upper ends of the power supply conductors 52 (IN1) and 52 (IN2) is provided. Further, the lower high-frequency electrode 30 is formed with a groove 158 that extends horizontally from the socket terminal 156 to just below the heating wire terminals h _1A and h _2A , and extends vertically upward from the end of the groove 158 to the upper surface of the electrode 30. A vertical passage 160 of the through hole is formed. The inner conductors 51 (IN 1) and 51 (IN 2) pass through the groove 158 so as to face the upper surface of the back plate 152 from the socket terminal 156, and then go up in the vertical passage 160 from the end of the groove 158 to generate the heating wire terminal. It has reached h _1A and h _2A .

  As described above, when the insulator back plate 152 is provided on the susceptor 12, the inner conductors 51 (IN 1) and 51 (IN 2) are wound in the lateral direction in the groove 158 formed on the lower surface of the lower high-frequency electrode 30. By adopting the configuration, the inner conductors 51 (IN 1) and 51 (IN 2) are hidden in the lower high-frequency electrode 30 and the flatness of the lower surface of the lower high-frequency electrode 30 is substantially ensured. Therefore, the plasma density distribution on the susceptor 12 is not affected by the routing of the inner conductors 51 (IN1) and 51 (IN2).

In the embodiment described above, the heating element 50 built in the susceptor 12 is divided into two in the radial direction of the susceptor 12 into an inner heating line 50 (IN) and an outer heating line 50 (OUT). However, for example, in the radial direction, the heating element 50 is divided into an inner heating wire 50 (IN), an intermediate heating wire 50 (MI), and an outer heating wire 50 (OUT), or the inner heating wire 50 (OUT). 50 (IN), an intermediate heating line 50 (MI _in ), an outer intermediate heating line 50 (MI _out ), and an outer heating line 50 (OUT) can be divided into four.

In the three-split type, as shown in FIG. 16A, three filter units 54 (IN), 54 respectively corresponding to the inner heating line 50 (IN), the intermediate heating line 50 (MI), and the outer heating line 50 (OUT). (MI) and 54 (OUT) are preferably arranged at equal intervals (120 ° intervals) on a concentric circle near the center of the chamber 10, that is, near the power feed rod 40. In this case, the filter unit 54 (IN) is disposed on the inner side (near the center) in the radial direction than the terminals h _1A and h _2A of the inner heating wire 50 (IN).

However, when a sufficient distance can be provided between the filter units 54 (IN), 54 (MI), 54 (OUT) and the dielectric cylindrical support 14, as shown in FIG. 54 (IN) may be arranged on the outer side in the radial direction from the terminals h _1A and h _2A of the inner heating wire 50 (IN). However, even in this case, it is preferable that the three filter units 54 (IN), 54 (MI), and 54 (OUT) are arranged at equal intervals (120 ° intervals) on a concentric circle.

Similarly, in the four-split type, as shown in FIG. 17A, the inner heating wire 50 (IN), the inner intermediate heating wire 50 (MI _in ), the outer intermediate heating wire 50 (MI _out ), and the outer heating wire 50. Four filter units 54 (IN), 54 (MI _in ), 54 (MI _out ), 54 (OUT) corresponding to (OUT) are arranged at equal intervals on the center of the chamber 10, that is, near the power supply rod 40 on a concentric circle ( It is preferable to arrange them at intervals of 90 °. In this case, the filter unit 54 (IN) is disposed on the inner side (near the center) in the radial direction than the terminals h _1A and h _2A of the inner heating wire 50 (IN).

However, _{in the} case where a sufficient distance between the filter units 54 (IN), 54 (MI _in ), 54 (MI _out ), 54 (OUT) and the dielectric cylindrical support portion 14 can be obtained, FIG. These filter units can be arranged outside in the radial direction from the inner heating wire 50 (IN) or the inner intermediate heating wire 50 (MI _in ) as shown in FIG. Also in this case, as shown in FIG. 17C, the four filter units 54 (IN), 54 (MI _in ), 54 (MI _out ), (54 (OUT) are concentrically arranged at equal intervals (90 ° intervals). Preferably they are arranged.

  In the present invention, various modifications can be made to the internal configuration of the filter unit 54. For example, the filters 102 (1) and 102 (2) provided in the filter unit 54 have a single air-core coil 102 (1) and 102 (2) in the above-described embodiment. A configuration in which the coils are connected in series, a configuration having a cored coil (for example, a toroidal coil), and the like are also possible.

  In the above embodiment, the susceptor 12 is arranged on the bottom wall 10a to which the chamber 10 is fixed at a certain height position via the space SP. However, as shown in FIG. 18, in the plasma processing apparatus in which the susceptor 12 is configured to be movable up and down in the chamber 10, the susceptor 12 is supported via the dielectric cylindrical support portion 14. Filter units 54 (IN) and 54 (OUT) can be attached to the movable base 162 that can be moved up and down. Here, a space SP communicating with the atmospheric space is formed between the susceptor 12, the dielectric cylindrical support portion 14, and the movable base 162.

  A cylindrical bellows 164 is provided between the movable base 162 and the bottom wall 10 a of the chamber 10. The bellows 164 extends the exhaust path 18 communicating with the plasma generation space (processing space) through the baffle plate 166 downward, and isolates or blocks the exhaust path 18 and the plasma generation space (processing space) from the atmospheric space. ing.

  In the space surrounded by the bellows 164, an upper leg 168, an annular plate 170, and a lower leg 172 are connected in the vertical direction. The upper end of the upper leg 168 is coupled to the lower surface of the movable base 162, and the lower end of the upper leg 168 is coupled to the upper surface of the annular plate 170. The upper end of the lower leg 172 is coupled to the lower surface of the annular plate 170. The lower end of the lower leg portion 172 is coupled to the plate portion 174 a of the link 174.

  The link 174 includes the plate portion 174a and the two columnar portions 174b. The plate portion 174 a is provided below the lower portion of the chamber 10. In this configuration example, the lower matching unit 38 is attached to the plate portion 174a.

  The plate portion 174a, the annular plate 170, and the movable base 162 are formed with through holes extending in the axis Z direction, and the lower power feed rod 40 passes through these through holes to the lower surface of the susceptor 12 (conductor back plate 28). It extends in the vertical direction.

  The columnar portion 174b extends upward from the peripheral edge of the plate portion 174a. In addition, the columnar shape 174 b extends outside the chamber 10 and substantially parallel to the side wall 10 d of the chamber 10. A feed mechanism made of, for example, a ball screw is connected to these columnar portions 174b. Specifically, the two screw shafts 176 extend substantially parallel to the two columnar portions 174b outside the chamber side wall 10d. These screw shafts 176 are connected to two motors 178, respectively. Two nuts 180 are attached to the screw shafts 176, respectively. Two columnar portions 174b are coupled to these nuts 180, respectively.

  According to such a lift drive mechanism, the nut 180 moves in the axis Z direction, that is, moves up and down by rotating the motor 178. As the nut 180 moves up and down, the susceptor 12 indirectly supported by the link 174 via the movable base 162 can move in the axis Z direction, that is, move up and down. Further, as the susceptor 12 moves up and down, the bellows 164 expands and contracts. As a result, the distance between the susceptor 12 and the upper electrode 64 can be variably adjusted.

  In this plasma processing apparatus, the heating element 50 built in the septa 12 is provided in an insulating sheet 181 sandwiched between the electrostatic chuck 32 and the high frequency electrode 30. The upper electrode 64 is attached to the upper surface of the chamber 10 via a ring-shaped insulator 182. The high frequency power source 34 that outputs the first high frequency HF for plasma generation is electrically connected to the upper electrode 64 via the upper matching unit 184 and the upper power feed rod 186. The high frequency power source 36 that outputs the second high frequency LF for ion attraction is electrically connected to the susceptor 12 via a matching unit (not shown) in the lower matching unit 38 and the lower power feed rod 40.

  The present invention is not limited to a capacitively coupled plasma etching apparatus, but can be applied to a microwave plasma etching apparatus, an inductively coupled plasma etching apparatus, a helicon wave plasma etching apparatus, and the like. The present invention can also be applied to other plasma processing apparatuses such as plasma nitriding and sputtering. In addition, the substrate to be processed in the present invention is not limited to a semiconductor wafer, and a flat panel display, organic EL, various substrates for solar cells, a photomask, a CD substrate, a printed substrate, and the like are also possible.

  Also in a microwave discharge type plasma processing apparatus, particularly a plasma etching apparatus, a mounting table or a susceptor for mounting a substrate to be processed, for example, a semiconductor wafer, is held in a chamber (chucking) in the same manner as a capacitively coupled plasma processing apparatus. ) Function, bias function and temperature control function.

  In particular, when a heating element is provided in the susceptor for the temperature control function, for example, AC frequency power is supplied to the heating element inside the susceptor from the heater power supply installed outside the chamber via the heater power supply line. . Also in this case, a part of the high frequency for bias (ion attraction) applied to the high frequency electrode of the susceptor easily enters the heater power supply line via the heating element. For this reason, a filter for attenuating or preventing high frequency noise on the heater power supply line is provided. Therefore, the configuration of the filter units 54 (IN) and 54 (OUT) in the above-described embodiment and the routing configuration of the heater power supply lines 100 (1) and 100 (2) inside and immediately below the susceptor 12 are added to the microwave plasma processing apparatus. Can be applied as is.

  However, in the microwave plasma processing apparatus, a part of the normal 2.45 GHz microwave for plasma generation radiated into the chamber from the antenna on the ceiling through the dielectric window passes through the plasma and the susceptor. Enter the filter units 54 (IN) and 54 (OUT). Here, if the microwaves that enter the filter units 54 (IN) and 54 (OUT) leak out, radio noise may be caused.

  19A to 19D show a configuration example that can reliably prevent a microwave leakage failure when the filter unit 54 (IN) is attached to the bottom wall 10a of the chamber 10 in the microwave plasma processing apparatus according to the present invention. The filter unit 54 (OUT) has the same configuration.

  In the filter unit mounting structure shown in FIG. 19A, a flange-like flange 200 made of a conductor, for example, aluminum is integrally formed or coupled to the upper portion of the casing 110 of the filter unit 54 (IN), and the upper surface of the flange 200 is used as the base or chamber bottom. The wall 10a is in close contact with the lower surface. The chamber bottom wall 10a is formed with a counterbore 202 for accommodating the upper connector 124 and an opening 204 through which the insulator rod 126 sealing the pin-shaped power supply conductors 52 (IN1) and 52 (IN2) is formed. Yes. An air-cooling vent hole 110a having a diameter of preferably 3 mm or less is formed on the side surface of the casing 110 by punching.

  In this mounting structure, since there is almost no gap for microwave leakage between the chamber bottom wall 10a and the filter unit 54 (IN), it is possible to reliably prevent a microwave leakage failure. In addition, since the diameter of the ventilation hole 110a of the casing 110 is 3 mm or less, a microwave does not leak from the ventilation hole 110a.

  In the filter unit mounting structure of FIG. 19B, the flange 200 is fitted into the counterbore 202 formed in the chamber bottom wall 10a from below. In this case, the flange 200 is in close contact with the chamber bottom wall 10a not only on the top surface but also on the side surface. Also in this mounting structure, since there is almost no gap for microwave leakage between the chamber bottom wall 10a and the filter unit 54 (IN), it is possible to reliably prevent a microwave leakage failure. In this mounting structure, the flange 200 integrally formed with or coupled to the casing 110 is fitted into the counterbore 202 of the chamber bottom wall 10a, thereby defining the positions of the filter terminals T (1) and T (2). As a result, the feed conductors 52 (IN1) and 52 (IN2) are positioned with respect to the socket terminal 128 (156) (FIGS. 7 and 15) on the susceptor 12 side.

  19C to 19E show a configuration example in which the characteristic impedance of the distributed constant line 105 is kept constant in the casing 110 in the filter unit mounting structure that prevents the microwave leakage failure as described above.

  When the upper surface of the flange 200 is brought into close contact with the lower surface of the base or the chamber bottom wall 10a as described above (FIG. 19A), if the upper ends of the coils 104 (1) and 104 (2) protrude beyond the flange 200, The outer conductor facing the protruding coil portion in the radial direction is not the casing 110 but the inner wall of the counterbore hole 202 of the chamber bottom wall 10a having a larger diameter, whereby the distributed constant line (coaxial line) 105 The characteristic impedance may be disturbed.

  Therefore, in the configuration example of FIG. 19C, a cap-type spacer 206 made of a conductor having an open center, for example, aluminum, is inserted between the upper connector 124, the flange 200, and the counterbore 202 of the chamber bottom wall 10a. The inner peripheral surface of the spacer 206 and the inner peripheral surface of the flange 200 are aligned with the inner peripheral surface of the casing 110, and the distance d between the coils 104 (1), 104 (2) and the outer conductor is set as a distributed constant line. (Coaxial line) 105 is kept constant from end to end. Further, the conductor spacer 206 is connected to the filter terminals T (1) and T (2) and the power supply conductors 52 (IN1) and 52 (IN2) with respect to the socket terminal 128 (158) (FIGS. 7 and 15) on the susceptor 12 side. It also functions as a shim for easy and accurate alignment.

  In the configuration example of FIG. 19D, instead of providing the conductor spacer 206, the opening 114 of the chamber bottom wall 10a is formed to have the same diameter as the inner diameter of the casing 110, and the inner wall of the opening 114 and the inner peripheral surface of the flange 200 are formed inside the casing 110. The distance d between the coils 104 (1), 104 (2) and the outer conductor is kept constant so as to be flush with the peripheral surface. Further, in order to align the filter terminals T (1), T (2) and the power feeding conductors 52 (IN1), 52 (IN2), a ring-shaped or cylindrical shape made of an insulator that fits into the opening 114 of the chamber bottom wall 10a. A flange portion 208 is integrally formed or coupled to the side surface of the upper connector 124.

  In the configuration example of FIG. 19E, when the flange 200 on the casing 110 side is fitted into the opening 114 or the counterbore 202 of the chamber bottom wall 10a, the inner peripheral surface of the flange 200 is flush with the inner peripheral surface of the casing 110. The coils 104 (1) and 104 (2) are opposed to the upper end portions.

  The inventor verified the microwave leakage phenomenon in the case where there is a gap in the filter unit 54 (IN) by simulation of electromagnetic field calculation. In this simulation, a cylindrical cover body 210 made of aluminum was connected to the upper end of the casing 110 instead of the opening 114 of the chamber bottom wall 10a. Here, a configuration in which no gap is formed between the lower end of the cover body 210 and the upper end of the casing 110 as shown in FIG. 20A is taken as an example, and a configuration in which the gap G is formed as shown in FIG. 20B is a comparative example. It was. The size of the gap G was 8 mm in length (height) and 60 mm in width (width).

  When the electric field distribution inside and around the casing 110 when a microwave of 2.45 GHz is put into the filter unit 54 (IN) from above is obtained by electromagnetic field calculation, in the example (FIG. 20A), As shown in 21A, there was no microwave leakage. Further, there was no leakage at the vent hole (punching metal) 110a of the casing 110. On the other hand, in the comparative example (FIG. 20B), it was clearly confirmed that a large amount of microwaves leaked from the gap G as shown in FIG. 21B.

  In addition, in the filter unit mounting structure of the above-described embodiment (FIG. 20A) and comparative example (FIG. 20B), the present inventor calculated whether or not there is an electromagnetic field leakage even at a high frequency of 100 MHz. Determined by As a result, although not shown, there was no leakage of the electromagnetic field in the comparative example (FIG. 20B) as well as in the above-described example (FIG. 20A).

  In general, when an electromagnetic wave (traveling wave) reaches the opening of a conductor, if the half wavelength of the electromagnetic wave is smaller than the maximum opening width of the opening, it is a general theory that the electromagnetic wave cannot pass through the opening. . In the case of the comparative example (FIG. 20B), the half wavelength of the microwave (2.45 GHz) is 61 mm, whereas the size of the gap G formed at the upper end of the filter unit 54 (IN) is 8 mm × Since it is 60 mm, according to the above-mentioned general rule, the microwave of 2.45 GHz can finally pass through the gap G, and the result of the simulation roughly agrees with it.

  Therefore, if a gap is inevitably formed between the filter unit 54 (IN) and the chamber 10 due to the design circumstances on the filter unit 54 (IN) side and / or the chamber 10 side, If the maximum opening width of the gap is suppressed to about half or less (about 30 mm or less) of the half wavelength of the microwave, leakage of the microwave can be prevented.

  The inventor also performed a simulation to confirm this point. That is, as a mounting structure with a gap according to the comparative example (FIG. 20B), a round hole (opening) g is provided between the cover body 210 and the casing 110, and the diameter of the round hole g is 13 mm, 17 mm, 23 mm. , 27 mm, and 35 mm, and in each case, the electric field distribution inside and around the casing 110 when microwaves of 2.45 GHz are put into the filter unit 54 (IN) from above by electromagnetic field calculation. Asked. 22A to 22E show the simulation results.

  As shown in FIG. 22A, there was leakage of about several V / m even when the diameter of the round hole g was 13 mm. As the diameter of the round hole g increases to 17 mm, 23 mm, and 27 mm, the amount of leakage of the electric field (microwave) increases (FIGS. 22B, 22C, and 22D), and leakage of 100 V / m or more occurs at the 35 mm diameter. It was found (FIG. 22E).

  From the above simulation, in order to ensure the microwave leakage prevention around the filter unit 54 (IN) mounting structure in the microwave plasma processing apparatus to which the present invention is applied, the filter unit 54 (IN), the chamber 10, As for the gap formed between the half-wavelengths (about 30 mm) as well as the maximum aperture width of about half-wavelength of microwaves (about 60 mm), it is still insufficient. It was found that it was necessary to make it 1 or less (about 3 mm or less).

10 Chamber 12 Susceptor (lower electrode)
14 dielectric cylindrical support 28 (conductor) back plate 32 electrostatic chuck 34, 36 high frequency power supply 40 feeding rod 50 heating element 50 (IN) inner heating wire 50 (OUT) outer heating wire 51 (IN1), 51 (IN2) ), 51 (OUT1), 51 (OUT2) Inner conductor 52 (IN1), 52 (IN2), 52 (OUT1), 52 (OUT2) Feeding conductor 54 (IN), 54 (OUT), 54 (MI), 54 (MIin), 54 (MIout) Filter unit 100 (1), 100 (2) Heater feed line 102 (1), 102 (2) Filter 104 (1), 104 (2) Coil T (1), T (2 ) Coil first terminal (filter terminal)
152 (Insulator) Backboard

Claims (22)

A processing vessel in which plasma processing is performed;
Placed on the plate-like conductive base in the processing container via a space, a mounting table for mounting and holding the substrate to be processed;
A high-frequency electrode provided on the mounting table;
A high-frequency power feeding section for applying a high-frequency wave to the high-frequency electrode;
A heating element provided on the mounting table;
A heater power supply line for electrically connecting the heating element to a heater power source disposed outside the processing container;
A filter unit having a coil for attenuating or preventing high-frequency noise that enters the heater power supply line via the heating element, and a casing that accommodates the coil;
The filter unit is arranged such that the upper end of the casing is directly below the mounting table at the same height as the upper surface of the base or lower than the upper surface of the base.
An opening through which the heater power supply line is passed in a non-contact manner is formed in the base,
The heater power supply line has a pin-shaped or bar-shaped first conductor extending through the space from the first terminal of the coil located inside or below the opening of the base to the lower surface of the mounting table.
Plasma processing equipment.   The plasma processing apparatus according to claim 1, wherein the first conductor extends straight without being bent in the space or the opening.   The plasma processing apparatus according to claim 2, wherein the first conductor extends straight in the vertical direction in the space or in the opening.   The plasma processing apparatus according to claim 1, wherein the first conductor is enclosed in an insulator rod, and the insulator rod does not contact an inner surface of the opening of the base. .   The plasma processing apparatus according to claim 1, wherein the first terminal of the coil is exposed.   The plasma processing apparatus according to claim 1, wherein an upper surface of the first terminal of the coil has the same height as an upper surface of the base.   The plasma processing apparatus according to claim 1, wherein an upper surface of the first terminal of the coil is opposed to the space without being shielded.   In order to electrically connect the socket terminal provided on the lower surface of the mounting table in order to insert the upper end of the first conductor into the heater power supply line, and the socket terminal and the terminal of the heating element. The plasma processing apparatus according to any one of claims 1 to 7, further comprising a pin-like, rod-like, or plate-like second conductor extending in the mounting table.   The plasma processing apparatus according to claim 8, wherein the first terminal of the coil and the socket terminal are located closer to the center of the processing container than the terminal of the heating element. The mounting table includes a conductor back plate whose upper surface is bonded to the lower surface of the high-frequency electrode and whose lower surface faces the space;
The second conductor has a section extending in a horizontal direction in an insulator embedded in the back plate.
The plasma processing apparatus according to claim 8 or 9. The mounting table has an insulating back plate whose upper surface is bonded to the lower surface of the high-frequency electrode and whose lower surface faces the space;
The second conductor has a section extending in a horizontal direction in a groove formed on a lower surface of the high-frequency electrode.
The plasma processing apparatus according to claim 8 or 9.   In the mounting table, a lower surface is bonded to an upper surface of the high-frequency electrode, and an upper surface is provided in the dielectric layer that forms a mounting surface on which the substrate is mounted, and adsorbs the substrate. The plasma processing apparatus according to claim 1, further comprising an electrostatic chuck having a DC electrode to which a high-voltage direct voltage is applied.   The plasma processing apparatus according to claim 12, wherein the heating element is provided in the insulating layer at a position lower than the DC electrode.   The plasma processing apparatus according to claim 12, wherein the heating element is provided in an insulating sheet sandwiched between the insulating layer and the high-frequency electrode.   The plasma processing apparatus according to any one of claims 1 to 14, wherein the mounting table is provided on the base via a cylindrical support member made of a dielectric.   The plasma processing apparatus according to claim 1, wherein the base forms a bottom wall of the processing container. The base is configured to be movable or displaced up and down above the bottom wall of the processing vessel,
The filter unit is disposed between the base and the bottom wall of the processing container.
The plasma processing apparatus as described in any one of Claims 1-15.   The plasma processing apparatus according to claim 1, wherein the base is electrically grounded.   The plasma processing apparatus according to claim 1, wherein a casing of the filter unit is made of a conductor and is electrically grounded.   The plasma processing apparatus according to any one of claims 1 to 19, wherein the high frequency contributes mainly to generating plasma of a processing gas in the processing container.   The plasma processing apparatus according to any one of claims 1 to 19, wherein the high frequency contributes mainly to drawing ions from the plasma into the substrate placed on the mounting table.   The plasma processing apparatus according to any one of claims 1 to 21, wherein the filter unit includes a capacitor that is electrically connected between a second terminal of the coil and a ground potential member.