JP2016046357A - Plasma processing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing device which enables the increase in process yield.SOLUTION: A plasma processing device comprises: a first RF power source which is electrically connected to an upper electrode opposed to an upper surface of a sample holder disposed in a process chamber and serving to form an electric field for forming plasma in the process chamber and which outputs a first high frequency power; a second RF power source which is connected to a lower electrode disposed in the sample holder, and supplied with a second high frequency power of a frequency lower than the first high frequency power while a sample is processed, and which supplies the second high frequency power through a biasing power-supply path; and a conducting plate arranged to surround the outer periphery of the lower electrode with an insulator layer sandwiched between the lower electrode and itself, facing the plasma on an outer peripheral side of the sample holder, and set at an earth potential. A current of the first high frequency power flows along a circuit running from the upper electrode, via the sample holder upper surface, the conductor plate, a member making an inner side wall face of the process chamber and then, back to the RF power source.SELECTED DRAWING: Figure 1

Description

The present invention manufactures a semiconductor device by processing a sample to be processed such as a semiconductor wafer placed on and adsorbed on a sample table disposed in a processing chamber inside a vacuum vessel using plasma formed in the processing chamber. The present invention relates to a plasma processing apparatus. In particular, a film structure made of a semiconductor or dielectric material such as silicon or silicon oxide film formed in advance on a sample surface is supplied with high-frequency power to an electrode inside the sample table. The present invention relates to a plasma processing apparatus that performs etching into a desired shape while forming a bias potential.

In the plasma processing apparatus that performs processing such as etching on a substrate-like sample such as a semiconductor wafer as described above, the plasma processing apparatus is arranged inside the vacuum container by a vacuum exhaust means including a vacuum pump such as a turbo molecular pump connected to the vacuum container. A plasma is formed in the processing chamber while evacuating the processed chamber, a processing gas used for processing the sample is introduced, and the gas is excited by using an electric field or a magnetic field supplied into the processing chamber to be converted into plasma. Then, the film to be processed is processed into a desired shape by etching a film other than a resin resist or oxide mask having a film structure arranged in advance on the surface of the sample. As a configuration for generating plasma, in general, an inductive coupling, an electron cyclotron resonance, or a capacitive coupling between flat plates arranged in parallel (including a magnetron system) is mainly used.

For the generation of plasma by inductive coupling, an electric field of 13.56 MHz is mainly used, and in the case of electron cyclotron resonance, a microwave electric field of 2.45 GHz is mainly used. Further, in these inductive coupling method and electron cyclotron resonance method, in addition to the generation of plasma, the ions in the plasma are attracted to the surface of the sample to accelerate the etching process, so that an electric field in the radio frequency (RF) band is applied to the sample or this. Apply to the electrode inside the sample table to be placed, adjust the RF power, adjust the value of the bias potential formed above the sample, and adjust the energy of ions incident on the sample surface. It has been practiced that the shape of the processing is brought close to the intended one by controlling to.

On the other hand, in the case of the parallel plate, an electric field of 13.56 MHz has been conventionally used for plasma generation. However, in recent years, in order to improve plasma density and enable plasma generation in a low pressure region, the VHF band is used. An electric field of (30 MHz to 300 MHz) has been used. Furthermore, electromagnetic waves in the RF band that independently control the energy of ions incident on the sample surface have been used separately from plasma generation.

Conventionally, the frequency of an electric field supplied to adjust the energy of incident ions by forming the bias potential has been several hundred kHz to several MHz. The frequency of the electric field for forming such a bias potential also tends to be used in the MHz band or higher from the viewpoint of energy controllability of incident ions.

In such a plasma processing apparatus, in general, in order to adjust the temperature of the sample being processed to an appropriate range for processing, the dielectric constituting the sample mounting surface of the upper part of the sample stage where the temperature is in a predetermined range A film-like electrode for electrostatically adsorbing the sample by electrostatic force is disposed on the dielectric film. Further, heat transfer gas such as He is supplied from the mounting surface to the space between the back surface of the adsorbed sample and the mounting surface described above in order to promote heat transfer between the two.

Furthermore, the temperature of the sample stage is set to a relative value within a predetermined range inside the flow path arranged concentrically or spirally inside the metal disk or cylindrical base material constituting the sample stage. Conventionally, what is performed by supplying and circulating the refrigerant is known. Further, in addition to adjusting the temperature of the sample with the refrigerant, it has been conventionally performed to use heating from a heater disposed on the upper part of the sample stage.

As an example of such a prior art, the thing of Unexamined-Japanese-Patent No. 2006-114767 (patent document 1) and Unexamined-Japanese-Patent No. 2011-258614 (patent document 2) was known. In patent document 1, it has the support table arrange | positioned in the plasma processing chamber in the cylindrical vacuum chamber made from aluminum, and supports the semiconductor wafer W on the mounting surface which is the upper surface, An electrostatic chuck having electrodes arranged between insulators for adsorbing the semiconductor wafer W is provided, and a voltage from a DC power source is applied to the electrodes so that the semiconductor wafer W is placed on the insulator by Coulomb force. To be adsorbed.

Further, in the support table, there is a refrigerant flow path for circulating the refrigerant, and a gas introduction mechanism for supplying He gas for improving the efficiency of heat transfer between the refrigerant and the semiconductor wafer W to the back surface of the semiconductor wafer W. Is provided. Furthermore, a high frequency power source is electrically connected to the support table, high frequency power in the range of 13.56 to 150 MHz is supplied, and 500 KHz to 13.56 MHz for forming a bias potential for drawing ions in the plasma. A high frequency power supply for supplying a range of high frequency power is electrically connected. Furthermore, in the present prior art, a shielding plate is provided that extends from the outer peripheral side surface of the support table toward the space inside the plasma processing chamber outside and surrounds the support table. It is installed to prevent the plasma in the upper processing chamber from diffusing toward the downstream space below the support table.

JP 2006-114767 A

The prior art described above has a problem due to insufficient consideration of the following points. That is, in Patent Document 1, when plasma is generated in a processing chamber, high-frequency power output from a high-frequency power source for plasma formation and supplied into the processing chamber causes the processing chamber to have an upper portion of the processing chamber above the sample stage. Thus, an equivalent circuit is formed in which a current flows between the flat antenna or electrode disposed on the substrate and the high-frequency power source for forming plasma grounded through the sample stage.

Such a high-frequency current is generated by a sample on a sample table or a semiconductor or a semiconductor shower plate 5 and a plasma 11 for dispersing a processing gas generally disposed below an antenna or an upper electrode. It can be considered equivalent on a circuit that it flows to the ground through a high-frequency power source for forming a bias potential through a conductor side wall or base material of the sample stage. On the other hand, when one end of a power source for supplying power to the electrostatic adsorption electrode or heater is electrically connected to the ground or grounded, the plasma forming power supplied to the processing chamber is supplied. Some of the electrodes are a film-like electrostatic adsorption electrode or heater arranged on the sample stage, and a power supply wiring or the like arranged below the sample stage via these and a connector and electrically connected thereto. Through the path, it flows into the ground through the electrode for electrostatic adsorption and the power supply for the heater.

The current of the high-frequency power for forming plasma in such a power supply path (hereinafter referred to as high-frequency current) has sufficient input impedance in the entire power supply path including the low-pass filter and the high-frequency power matching unit with respect to the high-frequency power. It can be suppressed by setting it high. However, when a high frequency power higher than the VHF band is used as the high frequency power for plasma formation, the parasitic capacitance and parasitic inductance of each circuit and connection cable are greatly affected, and the high frequency power for plasma formation It becomes difficult to realize a sufficiently high input impedance that can stably suppress the high-frequency current.

For example, when a coaxial cable is used as a cable connecting the electrode and the low-pass filter, in one example, even if the length of the cable is about 10 cm, the capacitance between the cable core wire and the shield line is about 10 pF. Therefore, for a current in the VHF band around 200 MHz, the impedance between the ground and the ground is about 80Ω. Furthermore, the parasitic impedance in the low-pass filter is also affected. For this reason, the input impedance in the power supply path using such a cable greatly varies due to the influence of variations in characteristics, constants, and wiring lengths of elements arranged on the path.

The power from the high-frequency power source for plasma formation that flows through such a path and constitutes the circuit fluctuates due to the influence of the above-described input impedance variation on the path from the electrode to the ground, and this fluctuation causes the plasma to There will be fluctuations in the power input to the formation of. Such fluctuations in the power used to form the plasma reduce the reproducibility of the conditions for processing the sample and increase the variation in the processed shape obtained after processing, or between plasma processing apparatuses. The prior art has not taken into account that the performance difference (so-called machine difference) is increased and the processing yield and the reliability of the apparatus are impaired.

An object of the present invention is to provide a plasma processing apparatus with improved processing yield.

The purpose of the above is to provide a processing chamber disposed inside the vacuum vessel, a sample table disposed in the processing chamber and on which a sample to be processed is placed, and a sample table disposed above the sample table. An upper electrode disposed opposite to the upper surface and supplying an electric field for forming plasma in the processing chamber, and a first high-frequency electric power that is electrically connected to the upper electrode and forms the electric field is output. A high frequency power source, a lower electrode disposed inside the sample stage and supplied with a second high frequency power having a frequency lower than the first high frequency power during the processing of the sample, and connected to the lower electrode for bias A second high-frequency power source for supplying the second high-frequency power via a power supply path; and a dielectric film disposed on an upper portion of the sample table and constituting the mounting surface. Electrostatic absorption placed inside An electrode for electrostatic adsorption to which direct current power is supplied through a power feeding path, and an outer periphery of the lower electrode with the insulating layer interposed therebetween, is arranged to face the plasma and to be grounded on the outer peripheral side of the sample stage And the insulating layer has an impedance smaller than that of the bias feeding path and the electrostatic attraction feeding path for the first high-frequency power, and the current of the first high-frequency power Is achieved by a plasma processing apparatus that flows from the upper electrode through the upper surface of the sample stage through the member that forms the inner wall surface of the processing chamber from the conductive plate to the high-frequency power source.

According to the present invention, the plasma generating electromagnetic wave is formed with a circuit that flows into the vacuum vessel wall from the side surface of the sample stage to be processed through the conductor plate, thereby reducing the influence of various functional parts connected to the sample stage portion to be processed. Can do. As a result, it is possible to suppress fluctuations in plasma generation due to differences in the characteristics of various functional units connected to the sample stage to be processed, and to suppress deterioration in reproducibility and differences between apparatuses.

It is a longitudinal section showing an outline of composition of a plasma treatment apparatus concerning an example of the present invention typically. It is a longitudinal cross-sectional view which expands and shows the vicinity of the shielding board of the side wall of the sample stand of the Example shown in FIG. It is a longitudinal cross-sectional view which shows typically the outline of the structure of the plasma processing apparatus which concerns on the comparative example of this invention. It is a longitudinal cross-sectional view which shows typically the flow of the high frequency current for plasma formation in the Example shown in FIG. It is a longitudinal cross-sectional view which shows the outline of a structure of the modification of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the outline of a structure of another modification of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the outline of a structure of another modification of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the outline of a structure of another modification of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the outline of a structure of another modification of the Example shown in FIG. It is a longitudinal cross-sectional view which shows the outline of a structure of another modification of the Example shown in FIG.

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

An embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a plasma processing apparatus according to the present invention. First, the apparatus configuration in FIG. 1 will be described.

The plasma processing apparatus according to FIG. 1 is a magnetic field parallel plate type plasma processing apparatus using an electromagnetic coil 1 which is a solenoid coil. The plasma processing apparatus according to the present embodiment is a process in which a vacuum vessel 10 and a space inside the vacuum vessel 10 disposed above the vacuum vessel 10 are placed, a sample to be processed is placed, a processing gas is supplied, and plasma is formed inside. And a plasma forming unit that is disposed above the vacuum chamber 10 and generates an electric field or a magnetic field for forming plasma inside the processing chamber, and is connected to a lower portion of the vacuum chamber 10 and is a processing chamber. And an exhaust device including a vacuum pump such as a turbo molecular pump that exhausts the inside to reduce the pressure.

In the processing chamber inside the vacuum vessel 10, a sample stage 2 having a cylindrical shape disposed below and a mounting surface on which a substrate-like sample 3 such as a semiconductor wafer is mounted thereon. A disk-shaped upper electrode 4 that is disposed opposite to the substrate and is supplied with high-frequency power for forming plasma, and is opposed to the mounting surface of the sample stage 2 on the sample 3 side of the upper electrode 4. And a disc-shaped shower plate 5 having a plurality of through holes that constitute the ceiling surface of the processing chamber and distribute and supply gas into the processing chamber. The shower plate 5 and the upper electrode 4 that is an antenna disposed above the shower plate 5 are arranged so that a gap is formed between them when they are attached to the vacuum vessel 10 and are supplied into the processing chamber. Gas used for processing the sample 3 to be processed or is not directly used for processing, but is supplied to the inside of the processing chamber while the processing gas is diluted or the processing gas is not supplied. The inert gas exchanged with the gas for use is supplied to the gap through the gas flow path provided in the upper electrode 4 from the gas introduction line 6 outside the vacuum vessel 10 connected to the gap, and dispersed therein. Then, it passes through the plurality of through holes arranged in the region including the central portion of the shower plate 5 and is supplied into the processing chamber.

The upper electrode 4 is a disk-shaped member made of a conductive material such as aluminum or stainless steel, and a coaxial cable for transmitting high-frequency power for plasma formation is electrically connected to the center of the upper surface thereof. And an upper electrode refrigerant flow path 7 connected to a temperature control device such as a chiller for adjusting the temperature of the refrigerant to a predetermined range and supplied with the refrigerant, and heat exchange while the refrigerant circulates in the inside As a result, the temperature of the upper electrode 4 is adjusted within a range of values appropriate for processing. The shower plate 5 of the present embodiment is made of a dielectric material such as quartz or a semiconductor such as silicon, through which an electric field formed on or emitted from the surface of the shower plate 5 is applied.

The upper electrode 4 is supplied with plasma-forming high-frequency power from a discharge high-frequency power source 8 electrically connected thereto via a coaxial cable via a discharge high-frequency power matching unit 9, and the surface of the upper electrode 4 Then, the electric field is emitted into the processing chamber through the shower plate 5. Furthermore, in this embodiment, a magnetic field formed by the electromagnetic coil 1 arranged outside the vacuum vessel 10 and surrounding the upper part and the side of the upper part of the processing chamber is supplied into the processing chamber.

By the interaction between the magnetic field and the high-frequency electric field, the processing gas or inert gas atoms or molecules supplied to the inside of the processing chamber are excited, and the plasma 11 is formed in the processing chamber. In this example, power of 200 MHz, which is a frequency in the very high frequency band (VHF band), was used as the high frequency power for forming plasma.

Further, the upper electrode 4 is arranged on the upper side or the side thereof, is made of a dielectric material such as quartz or Teflon, and the upper part of the vacuum vessel 10 is constituted by the ring-like upper electrode insulator 12 to open and close the vacuum vessel 10. It is electrically insulated from the member. Similarly, an insulating ring 13 made of a dielectric material such as quartz is disposed around the shower plate 5 and insulated from the lid member. The upper electrode insulator 12, the insulating ring 13, the upper electrode 4, and the shower plate 5 rotate together with the lid member when the lid member is opened and closed.

The side wall of the vacuum container 10 having a cylindrical shape is connected to a transport container through which the sample 2 is transported through a decompressed interior of a vacuum container (not shown). A gate valve is provided that closes the gate and hermetically seals the inside of the vacuum vessel 10 when the gate as an opening is arranged and the sample 2 is processed inside the vacuum vessel 10.

An exhaust opening communicating with a vacuum pump for exhausting the inside of the processing chamber is disposed under the vacuum vessel 10 below the sample stage 2 in the processing chamber, and exhaust for connecting these between the exhaust port and the vacuum pump. A pressure adjusting valve 26, which is a plate-like valve that rotates around an axis disposed across the flow path to increase or decrease the cross-sectional area, is disposed inside the path of the path, and the angle of rotation is adjusted. As a result, the flow rate or speed of the exhaust gas from the processing chamber is increased or decreased. The pressure in the processing chamber is within a desired range depending on the balance between the flow rate or speed of the gas supplied from the through hole of the shower plate 5 and the flow rate or speed of the gas or particles discharged from the exhaust opening. In this way, it is adjusted by a control device (not shown).

Next, the structure around the sample stage 2 will be described. The sample stage 2 of the present embodiment is a stage having a cylindrical shape disposed in the central portion below the processing chamber, and includes a metal base 2a having a cylindrical shape or a disk shape therein. Yes. The substrate 2a of the present embodiment is electrically connected to the bias high-frequency power source 20 via a bias high-frequency power matching unit 21 disposed on the power supply path by a power supply path including a coaxial cable, and is used for plasma generation. In addition to the high frequency power, high frequency power having a different frequency (4 MHz in this example) is supplied.

A bias potential for attracting charged particles such as ions in plasma to the upper surface of the sample 3 or the sample mounting surface is formed above these by the high-frequency power supplied to the substrate 2a. That is, the base material 2a functions as a lower electrode to which the bias high frequency power is applied below the upper electrode 4. A coolant having a predetermined temperature supplied to adjust the temperature of the substrate 2a or the sample mounting surface to a temperature suitable for the processing of the sample 3 circulates inside the substrate 2a. The refrigerant flow paths 19 are arranged in multiple concentric or spiral shapes.

On the upper surface of the base material 2a, an electrostatic adsorption film 14 made of a dielectric material such as alumina or yttria having a built-in tungsten electrode 15 to which direct current power for electrostatic adsorption of the sample 3 is supplied is disposed. Yes. The back side of the Dunsten electrode 15 is electrically connected to the DC power source 17 via a power supply path 27 disposed in a through hole that penetrates the base material 2a.

In addition, an element 32 such as a resistor or a coil is disposed below the substrate 2a and on the power supply path 27 inside the sample table 2. The element 32 is connected to the grounded bias high-frequency power matching unit 21 and this. Like the high-frequency power source 20 for bias, it is connected by a power feeding path provided with a coaxial cable. Furthermore, an element 32 such as a resistor or a coil is disposed below the through hole and on the power supply path 27 inside the sample stage 2, and the element 32 is connected to the DC power source 17 via the grounded low-pass filter 16. Connected with.

The DC power supply 17 and the bias high-frequency power supply 20 of the present embodiment have their one end terminals grounded or electrically connected to ground. The low-pass filter 16 and the bias high-frequency power matching unit 21 are arranged to suppress high-frequency power for plasma formation from the discharge high-frequency power source 8 from flowing into the DC power source 17 and the bias high-frequency power source 20. Yes. The low-pass filter 16 that filters the current flow at a higher frequency is filtered, so that the DC power from the DC power supply 17 or the high-frequency power from the biasing high-frequency power supply 20 is not lost, and the electrostatic adsorption film 14 and the sample stage are not lost. 2 is supplied to the DC power source 17 and the bias high-frequency power source 20 from the sample stage 2 side, but flows to the ground via the low-pass filter 16 or the bias high-frequency power matching unit 21. It is. Note that the low-pass filter 16 is not shown on the power supply path from the bias high-frequency power source 20 in FIG. 1, but a circuit having the same effect is incorporated in the bias high-frequency power matching unit 21 shown in the figure. Has been.

In such a configuration, the impedance of the power from the discharge high-frequency power source 8 when the DC power source 17 and the bias high-frequency power source 20 are viewed from the sample stage 2 is relatively low. In the present embodiment, an element 32 for increasing impedance such as a resistance or a coil is inserted between the electrode, the low-pass filter 16 and the bias high-frequency power matching unit 21 on the feeding path, thereby arranging the sample table 2. When the DC power source 17 or the bias high-frequency power source 20 side is viewed from the substrate 2a side, the impedance of the plasma-forming high-frequency power is increased (in this embodiment, 100Ω or more).

The embodiment shown in FIG. 1 includes a plurality of tungsten electrodes 15 arranged inside the electrostatic adsorption film 14, and both polarities to which a DC voltage is supplied so that one of the electrodes has a different polarity from the other. It is intended to perform electrostatic adsorption. For this reason, the tungsten electrode 15 is divided into two regions with a value within a range in which the area of the contact surface between the electrostatic adsorption film 14 and the sample 3 is divided into two equal parts or approximated to the extent. Then, DC power having an independent value is supplied to each of them, and the voltages are maintained at different values. Helium gas is supplied from the helium supply means 18 between the electrostatic adsorption film 14 and the back surface of the sample 3 to improve heat transfer between the sample 3 and the electrostatic adsorption film 14, and the base material 2 a. The efficiency of adjusting the temperature of the sample 3 is increased by increasing the amount of heat exchange with the internal refrigerant flow path 19.

A disc-shaped insulating plate 22 formed of Teflon or the like is disposed below the base material 2a, so that the base material 2a that is grounded or electrically connected to the ground and brought to the ground potential is insulated from the lower member. Has been. Further, a ring-shaped insulating layer 23 made of a dielectric material such as alumina is disposed around the side surface of the base material 2a so as to surround and be connected thereto. A conductive material which is grounded or electrically connected to the ground and is connected to the ground is provided below and around the insulating plate 22 disposed below and connected to the base 2a and around the insulating layer 23 above the insulating plate 22. A conductive plate 29 made of a conductive material is disposed.

The conductive plate 29 is a plate member having a circular shape as viewed from above or an approximate shape that can be considered to be circular, and the base 2a is disposed inside the insulating plate 22 and the insulating layer 23 at the center thereof. The dent part is arranged so that the lower surface and the side surface of the substrate 2a are surrounded. In addition, a shielding plate 24 that is a plate-like flange portion extending in the horizontal direction from the central side to the outer peripheral side is provided at a position on the outer peripheral side of the recess. The shielding plate 24 is disposed so as to bias the plasma formed above the sample stage 2 in the processing chamber toward the upper portion of the processing chamber, so-called confinement. Are provided with a plurality of holes for allowing the to pass in the vertical direction.

Further, a ring-shaped susceptor made of a dielectric material having plasma resistance, such as quartz, is provided on the outer peripheral side of the sample mounting surface having a substantially circular shape of the electrostatic adsorption film 14 at the upper part of the sample stage 2. 25 is placed above the upper surface of the outer peripheral portion of the substrate 2a and is disposed so as to surround the sample placement surface. The outer peripheral edge of the susceptor 25 is placed on the upper surface of the insulating layer 23 so as to cover it.

FIG. 3 is a longitudinal sectional view showing an outline of the configuration of a plasma processing apparatus as a comparative example that does not include a part of the configuration of the embodiment shown in FIG. The plasma processing apparatus shown in the figure does not include the shielding plate 24, the insulating layer 23, and the element 32 in the plasma processing apparatus according to the present embodiment, and other configurations are the same as those shown in FIG. Is. The description of the configuration equivalent to that of the embodiment of FIGS. 1 and 2 is omitted.

Moreover, it is a longitudinal cross-sectional view which shows typically the path | route through which the electric current of the high frequency electric power for plasma formation in a plasma processing apparatus flows. In FIG. 3, a path 328 through which the discharging high-frequency current flows is schematically shown using a dotted line.

In the plasma processing apparatus shown in this figure, in the vacuum vessel 10, high-frequency power for forming plasma in the processing chamber is plasma 11 as a dielectric formed in the processing chamber from the upper electrode 4 through the shower plate 5. A path through which a current flowing through the sample stage 2 sandwiching the electrode is formed. As shown in FIG. 3, in the case where the element 32 is not provided and the impedance of the power supply path 27 to the tungsten electrode 15 or the power supply path to the substrate 2a is relatively small, the discharge indicated by the broken line in FIG. As indicated by the path 328 for the high frequency current for use, the current of the high frequency power output from the discharge high frequency power supply 8 is high frequency after flowing into the sample stage 2 on which the sample 3 is placed. From the upper surface of the mounting surface or the sample 3 and from the susceptor 25 portion arranged on the outer peripheral side to the lower surface of the base material 2a and the insulating plate 22 from the side surface of the metal base material 2a (the surface of the lower surface of the base material 2a) ) To reach the center of the lower surface of the base material 2a. Furthermore, the discharge high-frequency power source is connected to the discharge high-frequency power source via a coaxial cable that is a high-frequency power supply path for plasma formation that is disposed on the vacuum vessel 10 through the inner surface of the member constituting the vacuum vessel below the sample stage 2. A reaching closed circuit is formed.

Further, in the example of this figure, the shielding plate 24 is not provided, and the high frequency power for plasma formation propagating on the side wall or the lower surface of the base material 2a is surrounded by an insulating material such as Teflon, and the side or lower side thereof. The formation of a current path from the side wall of the base material 2a whose surface is covered to the outer peripheral side is suppressed. For this reason, the high-frequency current flowing into the lower surface of the base material 2a is connected to the lower side of the cable via a cable that is a DC power feeding path 27 to the tungsten electrode 15 for electrostatic adsorption penetrating the lower surface of the base material 2a. The low-pass filter 16 or the coaxial high-frequency power feeding path connected to the lower surface of the substrate 2a flows through the coaxial cable toward the bias high-frequency power matching unit 21.

Further, a part of the plasma-forming high-frequency power flowing into the upper surface of the sample stage 2 flows directly from the tungsten electrode 15 inside the electrostatic adsorption film 14 to the power supply path 27 and passes through the grounded low-pass region below. It flows into the filter 16. The amount of the plasma-forming high-frequency power flowing into the low-pass filter 16 and the biasing high-frequency power matching unit 21 is such that the low-pass filter 16 and the biasing high-frequency power matching unit 21 (with them) (Including cables such as the power supply path 27 that is connected and supplied with power) is suppressed by setting the input impedance sufficiently high. However, when using a frequency band higher than the VHF band for the discharge high frequency, The parasitic capacitance and parasitic inductance on the flowing circuit and connecting cable are greatly affected, and a sufficiently high input impedance (in this embodiment, 200 MHz is used for the discharge high frequency, so that the input impedance of 100 Ω or more with respect to 200 MHz) is stabilized. It becomes difficult to realize.

For example, when a coaxial cable is used as the cable connecting the sample stage 2 and the low-pass filter 16, the capacitance between the cable core wire and the shield wire is about 10 pF even when the cable length is about 10 cm, and for 200 MHz. In this case, the impedance to ground is about 80Ω. Furthermore, since the parasitic impedance in the low-pass filter 16 is also affected, it is extremely difficult to realize an input impedance of 100Ω or more for 200 MHz. The input impedance fluctuates relatively greatly due to variations in element constants in each circuit and the influence of wiring arrangement.

Therefore, the electric power output from the discharge high-frequency power supply 8 and applied to the plasma 11 includes a low-pass filter 16 and a bias high-frequency power matching unit 21 for the high-frequency power for plasma formation (the cable connecting them to the sample stage 2). Of the impedance of the power supply path 27 to the tungsten electrode 15 serving as an electrode for electrostatic attraction or the impedance of the power supply path to the substrate 2a as the lower electrode for forming a bias potential during processing of the wafer 3 Will cause fluctuations. As described above, in the comparative example, the fluctuation of the electric power applied to the plasma 11 which appears when the amount of current flowing through the plasma 11 fluctuates effectively reduces the reproducibility of the processing conditions of the wafer 3 or between the apparatuses. This causes a difference in performance.

Hereinafter, description will be made with reference to FIGS. As described above, the present embodiment is made of a dielectric material such as ceramic having a high relative dielectric constant (relative dielectric constant of 4 or more) which is connected to and surrounds the outer periphery of the side wall of the substrate 2a of the sample stage 2. A ring-shaped insulating layer 23 is provided. Further, the base plate 2a and the ring-shaped insulating layer 23 and a disk-shaped insulating plate 22 disposed below and in contact with the lower surface thereof are provided inside the recess of the central portion, and the insulating plate 22 and the insulating layer A conductive plate 29 having a ground potential, which is disposed so that the side wall of the concave portion surrounds the side surface thereof, and an outer peripheral portion of the conductive plate 29 that extends from the central side to the outer peripheral side and extends to the processing chamber wall surface of the vacuum vessel 10. Is provided with a shielding plate 24 that is close to or in contact with. In addition, although not shown, the conductor plate 29 of the present embodiment is grounded or electrically connected to the ground to be at a ground potential.

The conductive plate 29 is made of a conductive material, but the shielding plate 24 facing the plasma is at least a member made of a conductive material such as aluminum and an anodized film formed by anodizing the surface. Or it has a film formed by spraying a dielectric material such as ceramics. Further, as described above, the shielding plate 24 is formed with a plurality of gas passage holes 30, and the process gas supplied from the shower plate 5, the plasma in the processing chamber, or the particles of the product are inside the gas passage holes 30. The flow passes through the processing chamber space on the outer peripheral side of the sample stage 2 toward the exhaust opening below the sample stage 2.

Furthermore, a feeding path 27 that electrically connects the DC power supply 17 for electrostatic adsorption and the tungsten electrode 15 and a coaxial cable that electrically connects them between the high frequency power supply 20 for bias and the base material 20a. An element 32 including a resistor or a coil is disposed in the shape of the power feeding path including the resistor. In this embodiment, it is assumed that the element 32 disposed between the low-pass filter 16 and the tungsten electrode 15 on the power supply path 27 is configured with a resistance of 1000Ω, and between the bias power source 20 and the substrate 2a. The element 32 disposed between the bias high-frequency power matching unit 21 and the substrate 2a is 0.5 μH (having an impedance of 628Ω with respect to the power of 200 MHz used for the plasma-forming high-frequency power). 1) having an inductance, for example, an element including a coil.

In this embodiment, in FIG. 2, the thickness of the ring-shaped portion of the insulating layer 23 disposed between the side surface of the disk-shaped or cylindrical substrate 2a and the side wall of the recessed portion of the conductive plate 29 having the ground potential. And the capacitance C of the insulating layer 23 portion made of a material having a relative dielectric constant having a value of 4 or more (t1 and h in FIG. 2) is approximately equal to the approximate expression of Expression (1). T1, h and the relative dielectric constant of the insulating layer 23 are selected so as to be 500 pF. Specifically, alumina having a relative dielectric constant of about 10 is used for the insulating layer 23, and T1 is about 3.5MM and h is 20MM. The insulating plate 22 arranged between the base material 2a and the conductor plate 29 is compared with the insulating layer 23 in order to realize insulation other than the power feeding path between the base material 2a and the conductor plate 29. Dimensions such as material and thickness with high impedance (with relatively small capacitance) are selected and placed.

Further, the plasma processing apparatus according to the embodiment shown in FIG. 1 and FIG. 2 is for etching a wafer having a diameter of 300 mm, and the outer diameter of the base 2a having a cylindrical shape inside the sample table 2 (FIG. 2). d1) was 330 mm. Here, ε represents the relative dielectric constant (ε = 10) of the insulating layer 23. The unit of d1, t1, and h in the formula (1) is cm, and the unit of C is F. The actual value of C varies somewhat depending on the dimensional accuracy of each part, the influence of a gap existing between the insulating layer 23 and the side surface of the sample table 2 and the conductor part 29 of the ground potential, but is roughly estimated by the equation (1). be able to.

C = 8.854 × 10 −14 × (ε (π (d1 + t1 / 2) h / t1) (1)

In the present embodiment shown in FIGS. 1 and 2, the discharge high frequency f (200 MHz in the present embodiment) from the side surface of the sample stage 2 to the ground potential conductor portion 29 arranged around the sample table 2 using the obtained C value. ) Impedance Z is about 1.6Ω from equation (2).

Z = 1 / (2πfC) (2)

As shown in FIG. 4, in such a configuration, the shielding plate 24 constituting a part of the ground potential conductive plate 29 extends from the side wall of the sample table 2 to the outer peripheral side, and the tip thereof is cylindrical. By being disposed at a position in contact with the inner wall surface of the processing chamber or in the vicinity of a small gap, the plasma 11 is output from the discharge high-frequency power source 8 and supplied to the processing chamber through the upper electrode 4 and the shower plate 5. The current of the plasma-forming high-frequency power that has flowed into the sample table 2 on which the sample 3 is placed on the mounting surface via the surface of the shielding plate 24 brought to the ground potential from the side surface of the sample table 2 and the sheath via the sheath It flows into the member of the vacuum vessel 10 which constitutes the inner wall of the processing chamber via the plasma 11 in contact therewith. The current flowing through the side wall member of the vacuum vessel 10 includes a coaxial cable electrically connected to the discharge high-frequency power source 8 through a metal lid member constituting the upper portion of the vacuum vessel 10 and a discharge disposed thereon. It flows through the high frequency power matching unit 9 to the discharge high frequency power source 8 and further to the ground (ground electrode), and a closed path 428 through which the current of the plasma forming high frequency power flows is formed.

As described above, the input impedance of the electrostatic adsorption power supply path 27 connected to the sample stage 2 and the high frequency power supply path for bias are 1000 Ω resistance elements and 0.5 μH (impedance of 628 Ω with respect to 200 MHz), respectively. An element 32 having a certain inductance is built in the insulating plate 22 between the low-pass filter 16 and the tungsten electrode 15 or between the bias high-frequency power matching device 21 and the base material 2a inside the recess of the conductor plate 29. Are arranged in series. In the present embodiment described in FIGS. 1, 2 and 4, the current of the plasma-forming high-frequency power configured to pass through the side wall member of the vacuum vessel 10 through the shielding plate 24 from the side surface of the sample stage 2 or the substrate 2a. The magnitude of the impedance of the flowing path 428 is set to a value of about 1/300 to 1/500 with respect to the input impedance of the power feeding path.

In the present embodiment, the impedance in the insulating layer 23 is dominant in the impedance of the current path from the sample stage 2 through the shielding plate 24 (or the plasma 11). In the present embodiment having the values of d1, t1, h, and C described above, the impedance is about 2Ω or less, so that the impedance of the insulating layer 23 is about 1/300 of that of the element 32 and is extremely small. Become. As a result, the current of the plasma-forming high frequency power stably flows from the sample stage 2 having a relatively small impedance through the shielding plate 24 to the path 428 that flows to the vacuum vessel 10.

As described above, in this embodiment, the output from the discharge high-frequency power supply 8 passes through the supply cable and is supplied from the upper electrode 4 through the shower plate 5 into the processing chamber and flows into the upper surface of the sample stage 2 or the sample 3. A high-frequency power current for plasma formation of 200 MHz passes through the upper surface of the sample table 2 or the sample 3 and is transmitted from the side wall surface of the base material 2a to the side wall of the recessed portion of the conductor plate 29 through the insulating layer 23. Alternatively, the tungsten electrode on the upper side of the sample stage 2 is stably flowed through a closed circuit that is transmitted from the front end portion of the shielding plate 24 to the processing chamber wall surface via the plasma 11 facing this and returned to the original discharge high-frequency power supply 8. 15 is suppressed from flowing through the power supply path 27 connected to the power supply path 15 and the power supply path connected to the base material 2a. By forming such a current path, it is possible to suppress a decrease in reproducibility of sample processing and occurrence of a difference between apparatuses.

In this embodiment, the impedance of the resistor or inductance element inserted in series in various circuits connected to the sample stage 2 is set to about 628 to 1000Ω, but the same effect can be obtained even when the impedance is 100Ω or more with respect to the discharge frequency. Further, the capacitance between the side surface of the sample stage 2 through the insulating layer 23 and the conductor portion 29 of the ground potential is set, and the impedance is set to about 1.6Ω with respect to the discharge frequency. .

The resistance or inductance element connected to the DC power supply 17 for electrostatic adsorption was a 1000Ω resistance element. This is because the electrostatic adsorption film usually has a resistance of 1 MΩ or more, and even if a resistance is inserted in series, the DC potential of the DC power source 17 can be sufficiently applied to the electrostatic adsorption film. Therefore, it is possible to insert a resistance up to about 1/10 of the resistance value of the electrostatic adsorption film (100 kΩ in the case of 1 MΩ).

The same effect can be obtained by inserting an inductance block having an impedance of 100Ω or higher with respect to the discharging high frequency without using a resistor for the element inserted in the electrostatic adsorption circuit. On the other hand, if a resistor is used as a resistor or an inductance element connected to the bias power source 20, power loss occurs.

Therefore, the element inserted into the connection circuit of the bias power supply 20 is preferably an inductance element with no power loss. In the present invention, the value of the inductance element inserted into the connection circuit of the bias power supply 20 is set to 0.5 μH. However, an inductance element of 0.08 μH or more having an impedance of about 100Ω with respect to the high frequency for discharge has the same effect. .

As the electrostatic capacitance between the side surface of the sample table 2 formed through the insulating layer 23 according to this embodiment and the conductor plate 29 at the ground potential is larger (impedance is smaller), a current path of high-frequency power for plasma formation is formed. Although it is advantageous in terms of the point, it acts on the bias high-frequency power supply in the same manner. Therefore, if the capacitance is increased too much, the reactive current of the bias high-frequency power supply increases and power loss increases, which is not desirable. In this embodiment, 4 MHz is used for the bias high-frequency power source 20.

Therefore, the impedance between the side surface of the sample table 2 and the ground potential conductor plate 29 as viewed from the bias high frequency power is about 80Ω. The impedance between the side surface of the sample stage 2 and the ground potential conductor is preferably about 50Ω or more with respect to the bias high frequency power, and when it is less than that, particularly when a high voltage amplitude (for example, a voltage amplitude of 1000 V or more) is applied, Loss becomes relatively large, causing a failure due to a decrease in power application efficiency and heat generation in the high-frequency power path. From the above, it is desirable that the impedance between the side surface of the sample stage 2 and the conductor portion of the ground potential through the insulating layer 23 is set to be 10Ω or less for the high frequency for discharge and 50Ω or more for the high frequency for bias.

A resistance or inductance element 32 according to the present invention shown in FIG. 1 is applied with a sample base 2, in particular, a base material 2 a that is a conductor material supplied with a high-frequency power source for bias, or DC power for electrostatic attraction. It is desirable to arrange it as close as possible to the tungsten electrode 15. When high-frequency power having a frequency equal to or higher than the VHF band is used for plasma formation, the impedance to the high-frequency power greatly changes due to a slight parasitic capacitance or parasitic inductance. For this reason, when the sample stage 2 and the resistance or inductance element 32 are connected with a long coaxial cable or the like, the ground capacitance of the cable becomes the dominant factor of the impedance with respect to the high frequency for discharge, and it becomes difficult to secure the target impedance. It is.

In the embodiment shown in FIG. 1 and FIG. 2, 200 MHz is used for the discharge high-frequency power source 8 and 4 MHz is used for the bias high-frequency power source 20, but in the discharge high-frequency power source, the VHF band (30 MHz to 300 MHz) or higher, The same effect can be obtained by using a frequency in the range of 100 kHz to 14 MHz. In addition, although alumina is used for the insulating layer 23, other insulating materials such as quartz, yttria, and aluminum nitride may be used. In any case, the side surface of the substrate 2a through the insulating layer 23 and the conductor plate 29 having the ground potential. By adjusting the impedance between them to 10Ω or less for the high-frequency power for plasma formation and to 50Ω or more for the high-frequency power for biasing, the above effect can be obtained.

Modification 2 of the above embodiment is shown in FIG. FIG. 5 shows an example in which the shielding plate 24 used in the first embodiment of FIG. 1 is not provided.

That is, the conductor plate 29 forming the side wall of the sample stage 2 of the present example includes the shielding plate 24 extending from the center to the outer peripheral side on the outer circumference side of the cylindrical sample stage 2 provided in the embodiment of FIG. Absent. That is, a conductor member that is brought into contact with the plasma 11 by being grounded is disposed in the space on the outer peripheral side of the side wall of the sample stage 2 and between the side wall of the sample stage 2 and the inner side wall of the processing chamber. Absent. The plasma 11 comes into contact with the side wall of the sample stage 2 and the inner side wall of the processing chamber.

Also in this example, high-frequency power for plasma formation that can be considered to flow from the upper electrode 4 to the processing chamber from the shower plate 5 and flow to the upper surface of the sample table 2 or the wafer 3 through the plasma 11 as a dielectric. The current flows from the side surface of the base material 2a to the conductor plate 29 that constitutes the side wall of the sample table 2 that is disposed with the side surface and the ring-shaped upper member at the outer peripheral edge of the insulating plate 22 interposed therebetween. Also in this example, as a result of appropriately selecting the material of the ring-shaped upper member on the outer peripheral edge of the insulating plate 22 and the thickness and the like, the input impedance of the upper member with respect to the high-frequency power for plasma formation is fed. Compared to the power supply path between the path 27 or the base material 2a and the bias high-frequency power source 20, it is set to about 1/300 or less. This suppresses the flow of high-frequency power for plasma formation from the sample stage 2 to the DC power source 17 and the bias high-frequency power source 20 connected thereto, through these power supply paths.

The path (path) through which the current of the plasma-forming high-frequency power returning from the sample stage 2 to the discharge high-frequency power supply 8 flows is the lower part of the vacuum vessel 10 connected to the conductor plate 29 that is the side wall of the sample stage 2. The surface of the member constituting the lower surface (inner side wall surface) of the processing chamber passes through the inner wall surface of the processing chamber and is connected to this from the inner surface of the member constituting the upper portion of the vacuum vessel 11 as in the embodiment of FIG. The discharge high-frequency power supply 8 and the upper electrode 4 are returned to the discharge high-frequency power supply 8 from a power feeding path such as a coaxial cable. As a member constituting such a path for passing a current, the shielding plate 24 shown in FIG. 1 may not be used, but a conductor plate 29 facing the plasma 11 or a part of the vacuum vessel 11 as in the example shown in FIG. Thus, the conductive member constituting the inner wall of the processing chamber can provide the same action as the embodiment of FIG. Also in this example, the conductor plate 29 and the vacuum vessel 11 are grounded and have the same potential as the ground.

Next, another modification of the above embodiment is shown in FIG. In the embodiment of FIG. 6, in the plasma processing apparatus shown in FIG. 1, instead of the configuration in which the insulating layer 22 and the insulating material 23 are arranged vertically, the insulating layer 22 is arranged at the place where the insulating material 23 is arranged. The capacitor 31 is disposed on a circuit that is configured as one member and electrically connects the inside of the recessed portion of the conductor plate 29 that is set to the ground potential and the lower surface of the substrate 2a.

In this example, four capacitors 31 are arranged at positions that form an angle of a value close to the side of the base material 2a in the sample stage 2 as viewed from above, or to the extent that it can be regarded as this. The capacitor 31 has a total capacity of 400 pF (100 pF per piece). The example of FIG. 6 is a structure when a necessary impedance cannot be ensured by the side structure of the sample stage 2 disclosed in FIG.

In this example, the capacitor 31 is disposed between the base member 2a and the recessed portion of the conductor plate 29 having the ground potential so that the same effect as that of the embodiment shown in FIG. be able to. In addition, since the capacitor 31 is disposed at a position that makes an equal angle with respect to the center of the circumferential direction of the sample stage 2 having a cylindrical shape, a path through which high-frequency power for plasma formation flows out of the sample stage 2 or these It is possible to suppress the occurrence of a bias in the circumferential direction in the amount of power flowing out from the path.

Further, the total capacity of the plurality of capacitors 31 arranged is the same as that of the insulating layer 23 in the embodiment shown in FIG. In addition, the high-frequency power for plasma formation is output from the high-frequency power source 8 for discharge and stabilizes the closed circuit that returns from the substrate 2a to the original high-frequency power source 8 for discharge from the side wall of the processing chamber through the capacitor 31 and the shielding plate 24. Flow to the power supply path 27 connected to the tungsten electrode 15 at the upper part of the sample stage 2 and the power supply path connected to the base material 2a, thereby reducing the reproducibility of the processing of the sample and the occurrence of differences between apparatuses. Can be suppressed. In the example shown in FIG. 7, the total capacity of the capacitor 31 is 400 pF. However, as shown in the embodiment, the capacity is 10Ω or less with respect to the 200 MHz plasma forming high frequency power and the bias high frequency power. Any element other than a capacitor may be used.

In the example shown in FIGS. 1, 5, and 6, an element 32 having a resistor or a coil or the like on a power supply path from the DC power supply 17 for electrostatic adsorption and the high frequency power supply 20 for bias connected to the sample stage 2. However, in the case where the sample stage 2 includes a heater and a path for supplying power to the sample stage 2, the element 32 is disposed on the path in the same manner as in the above example, so that the above-described operation can be achieved. .

Another modification of the above embodiment will be described with reference to FIG. FIG. 7 is a longitudinal sectional view showing the outline of the configuration of still another modified example of the embodiment shown in FIG.

In this example, as the element 32 shown in FIG. 1, an inductance element using a magnetic material, for example, a position where the ferrite core 33 is brought close to the sample stage 2, in this example, the sample stage inside the recess of the conductor plate 29. 2 is electrically connected between the DC power supply 17 and the tungsten electrode 15, and on the power supply path 27 through which the DC power for electrostatic attraction from the DC power supply 17 flows, and the tungsten electrode 15 and the low-pass filter 16 is arranged. A power supply line 34 constituting the inside of the power supply path 27 is wound around the ferrite core 33 several times (once in the drawing) and is electrically connected to the tungsten electrode 15. Further, the ferrite core 33 is adjusted so that the temperature falls within a desired range by a temperature adjusting mechanism 37 disposed so as to surround the ferrite core 33 on the outer peripheral side thereof.

The temperature adjustment mechanism 37 is disposed around the ferrite core 33 around the axis of the power supply path 27. A temperature control medium (for example, industrial water) is introduced into the space inside the temperature control cover 36 having a sealing function and surrounding the ferrite core 33 from an inflow path 38 a disposed at the bottom of the temperature control cover 36. Then, the medium flows through the inside and then is discharged from the discharge path 38b disposed at the bottom, thereby suppressing the temperature of the ferrite core 33 from rising beyond the intended range.

In addition, a temperature sensor 35 is attached to the ferrite core 33 so that the temperature of the ferrite core 33 and its change can be detected. Even if the supply amount, speed, or temperature of the temperature control medium is adjusted according to the temperature detected from the output from the temperature sensor 35, the temperature of the ferrite core 33 is adjusted to be within a desired range. good.

The element 32 is arranged to suppress the discharge high-frequency power for forming the plasma 11 in the processing chamber from flowing into the low-pass filter 16 via the feeding path 27, and is shown in this embodiment. The ferrite core 33 acts to prevent the high frequency power from flowing to the filter side by absorbing the high frequency power for discharge flowing through the power supply path 27 and consuming it as heat.

However, the temperature of the ferrite core 33 increases as the discharge high-frequency power increases. On the other hand, the magnetic permeability of the ferrite magnet depends on temperature, and its impedance changes due to a change in temperature. This also changes the impedance of the sample, which may adversely affect the stability and reproducibility of the sample processing results.

By providing the temperature adjustment mechanism 37 as shown in this example and adjusting the temperature value of the element 32 to be within a predetermined range, the above-described problems can be solved. It is possible to suppress the fluctuation of the temperature and the reproducibility of the processing by suppressing the fluctuation of the temperature of the ferrite core 33, that is, the impedance.

Furthermore, by arranging the element 32 in a vacuum or a space having a degree of vacuum higher than a predetermined frequency, the heat insulation and cold insulation effects of the element 32 by vacuum insulation can be expected. In this example, the temperature control medium is industrial water, but liquids such as fluorinate, air, and gases such as nitrogen gas may be used. Furthermore, although the structure which cools the element 32 was demonstrated in this example, you may provide the structure which heats and heats up.

An example of another configuration of such temperature adjustment will be described with reference to FIG. FIG. 8 is a longitudinal sectional view schematically showing still another modification of the plasma processing apparatus according to the embodiment shown in FIG.

In this example as well, the ferrite core 33 is arranged as the element 32 arranged on the power supply path 27 between the tungsten electrode 15 and the low-pass filter 16 as in the example of FIG. 7, and the ferrite core 33 surrounds the outer peripheral side thereof. The temperature is adjusted by the temperature control mechanism 37 arranged in (1). In this example, a temperature control medium (refrigerant) introduced into the refrigerant flow path 19 disposed in the sample stage 2 is introduced into the temperature adjustment mechanism 37 as a temperature control medium used for adjusting the temperature of the element 32. To do. In this example, the refrigerant supplied from a refrigerant temperature control device such as a chiller (not shown) is first introduced into the temperature adjustment mechanism 37 from the inflow path, and is then discharged from the temperature adjustment mechanism 37 and flows through the refrigerant flow of the sample stage 2. A circulation path is configured so that it flows into the path 19 and flows through the flow path, then flows into the temperature control mechanism 37 of another element 32, adjusts the temperature, and is discharged again to return to the temperature control device. ing.

The sample stage 2 of this example has a tungsten electrode 15 and has an electrostatic adsorption function, and a heat transfer gas such as helium is placed in the gap between the back surface of the sample 3 and the upper surface of the electrostatic adsorption film 14. The heat supply is promoted by being supplied from the opening on the upper surface of the electrostatic adsorption film 14 communicated with the helium supply means 18 and filling the gap. That is, in this example as well as the example of FIG. 1, the processing is performed while adjusting the temperature of the sample 3 placed and held on the upper surface of the sample table 2 to a value within the range suitable for the processing. The refrigerant whose temperature is adjusted to a predetermined value during the period in which each sample 3 is placed and processed in the refrigerant flow path 19 inside the sample stage 2 and during the period when the process is not performed. Have been supplied. In this example, the temperature control refrigerant is used to adjust the temperature of the ferrite core 33, whereby the supply source of the temperature adjustment medium for the element 32 and the supply and discharge paths thereof are arranged independently of the refrigerant flow path 19. The necessity is eliminated, the structure is simplified, and an increase in manufacturing cost can be suppressed.

FIG. 9 shows still another modification of the above embodiment. FIG. 9 is a longitudinal sectional view showing an outline of the configuration of still another modified example of the embodiment shown in FIG.

In this example, the temperature of the ferrite core 33 is controlled as in the examples of FIGS. In this example, a ferrite core 33 is arranged inside the base material 2a of the sample stage 2.

As described above, the temperature of the base material 2a of the sample stage 2 is such that the refrigerant whose temperature is adjusted to a value within a predetermined range suitable for processing flows through the refrigerant flow path 19 disposed therein. It is adjusted with. By arranging the ferrite core 33 in the base material 2a, the temperature of the ferrite core 33 is indirectly adjusted through the member of the metal base material 2a.

With such a configuration, the temperature can be adjusted without disposing the temperature adjustment mechanism 37 in the substrate 2a, and further cost reduction can be achieved. Further, since it is desirable that the ferrite core 33 is as close as possible to the sample stage 2, further process performance stability can be obtained.

Another modification of the above embodiment will be described with reference to FIG. FIG. 10 is a longitudinal sectional view schematically showing the outline of the configuration of the element according to the embodiment shown in FIG.

The element of this example shows a matching circuit 39 arranged on the power feeding path 27 as another example of the element 32 shown in FIG. The matching circuit 39 of this example includes a stripline 40 with low attenuation disposed on the feed line 34 of the feed path 27, and a feed line 34 and an earth connected to the input side terminal of the strip line 40. This is a short stub circuit including a capacitor 41 connected therebetween. The example of the matching circuit 39 shown in FIG. 10 has a structure that can block the inflowing high frequency.

Since the matching circuit 39 of this example is not configured to consume the high frequency that flows in as heat and cut off or reduce the high frequency as compared with the ferrite core 33, the matching circuit 39 and surrounding devices are damaged by heat generation and the performance is degraded. Can be reduced, and it is not necessary to use temperature control means as in the examples of FIGS.

As described above, according to the above-described embodiment, the plasma processing of the semiconductor device manufacturing apparatus, particularly the plasma etching apparatus or the like that performs the etching process of the lower film structure using the etching circuit pattern formed by the lithography technique as a mask. In the apparatus, when plasma is generated at a high frequency higher than the VHF band, which is superior in plasma generation characteristics in a wide range of pressures, the influence of the current of the high frequency power for plasma generation is suppressed, and stable plasma generation can be realized. As a result, it is possible to suppress a decrease in process reproducibility in the plasma processing apparatus and occurrence of differences between apparatuses.

1 ... electromagnetic coil,
2 ... Sample stage,
3 ... Sample,
4 ... Upper electrode,
5 ... shower plate,
6 ... Gas introduction line,
7: Refrigerant flow path for upper electrode,
8 ... High frequency power supply for discharge,
9: High frequency power matching unit for discharge,
10 ... Vacuum container,
11 ... Plasma,
12 ... Upper electrode insulator,
13: Insulating ring,
14 ... electrostatic adsorption film,
15 ... Tungsten electrode,
16 ... low-pass filter,
17 ... DC power supply,
18 ... helium supply means,
19 ... refrigerant flow path,
20 ... High frequency power supply for bias,
21... High frequency power matching device for bias,
22: Insulating plate,
23. Insulating layer,
24 ... shielding plate,
25 ... Susceptor,
26 ... Pressure adjusting valve,
27: Feeding path,
29 ... Conductor plate,
30: Gas passage hole,
31: Capacitor,
32: Element.

Claims (8)

A processing chamber disposed inside the vacuum vessel, a sample table disposed in the processing chamber and having a sample to be processed placed on the upper surface thereof, and disposed above the sample table and facing the upper surface of the sample table An upper electrode that is arranged and supplies an electric field for forming plasma in the processing chamber; and a first high-frequency power source that is electrically connected to the upper electrode and outputs a first high-frequency power for forming the electric field; A lower electrode disposed inside the sample stage and supplied with a second high-frequency power having a frequency lower than the first high-frequency power during processing of the sample, and connected to the lower electrode via a bias feeding path A second high-frequency power source for supplying the second high-frequency power; and a dielectric film disposed on an upper portion of the sample stage and constituting the mounting surface, and disposed within the lower electrode. Power supply path for electrostatic adsorption An electrode for electrostatic adsorption to which direct current power is supplied, and a conductive material that is arranged to surround the outer periphery of the lower electrode with an insulating layer in between and faces the plasma on the outer peripheral side of the sample stage and is set to the ground potential With a board,
The insulating layer has an impedance smaller than that of the bias feeding path and the electrostatic adsorption feeding path for the first high-frequency power, and the current of the first high-frequency power passes from the upper electrode to the upper surface of the sample table. And a plasma processing apparatus that flows through a circuit that returns from the conductive plate to a high-frequency power source through a member that forms an inner wall surface of the processing chamber.
The plasma processing apparatus according to claim 1,
A grounded matching unit arranged on the bias power supply path for matching power from the second high-frequency power source or a grounded low-pass filter arranged on the electrostatic adsorption power supply path for preventing high-frequency currents A plasma processing apparatus comprising:
The plasma processing apparatus according to claim 1,
An element disposed on the bias feeding path or the electrostatic adsorption feeding path, wherein the impedance of the first high-frequency power including the element in the feeding path is the first high-frequency of the insulating layer; A plasma processing apparatus that is made larger than the impedance for electric power.
The plasma processing apparatus according to claim 2,
An element disposed between the matching unit and the lower electrode on the bias feeding path, or between the low-pass filter and the electrostatic chucking electrode on the electrostatic suction feeding path. A plasma processing apparatus, wherein the impedance of the first high-frequency power including the element of the power supply path is greater than the impedance of the insulating layer for the first high-frequency power.
The plasma processing apparatus according to claim 3 or 4,
A plasma processing apparatus, comprising: an insulating plate disposed below the lower electrode to insulate the lower electrode, wherein the element is disposed inside the insulating plate.
A plasma processing apparatus according to any one of claims 1 to 5,
A plasma processing apparatus, wherein an impedance of the bias feeding path or the electrostatic adsorption feeding path is 100Ω or more.
The plasma processing apparatus according to any one of claims 1 to 6,
A plasma processing apparatus, wherein the frequency of the first high-frequency power is in the VHF band of 30 MHz to 300 MHz.
The plasma processing apparatus according to claim 7,
The plasma processing apparatus whose frequency of said 2nd high frequency electric power is 100 kHz or more and 14 MHz or less.