JP2021177539A - Etching device and etching method - Google Patents

Abstract

To appropriately control the tilt angle in an edge region of a substrate in etching.SOLUTION: An etching device for etching a substrate 1 includes a chamber 10, a stage 11 which is a substrate support provided inside the chamber 10, and includes an electrode 12, an electrostatic chuck 13 provided on the electrode 12, and an edge ring 14 arranged so as to surround the substrate W mounted on the electrostatic chuck 13, a first high frequency power supply 50 that supplies high frequency power to generate plasma from gas inside the chamber 10, and a second RF filter 63 that can change the impedance. The edge ring 14 and the RF filter 63 are electrically directly connected via a connection portion.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to an etching apparatus and an etching method.

Patent Document 1 discloses a plasma processing apparatus that includes a mounting table arranged in a chamber on which a wafer is placed and an edge ring arranged so as to surround the wafer on the mounting table, and performs plasma processing on the wafer. Has been done. In this plasma processing apparatus, by applying a negative DC voltage to the edge ring consumed by the plasma, the distortion of the sheath is eliminated and the ions are vertically incident on the entire surface of the wafer.

Japanese Unexamined Patent Publication No. 2008-227063

The technique according to the present disclosure appropriately controls the tilt angle in the edge region of the substrate in etching.

One aspect of the present disclosure is an apparatus for etching a substrate, which is a chamber, a substrate support provided inside the chamber, an electrode, an electrostatic chuck provided on the electrode, and the above. The substrate support having an edge ring arranged so as to surround the substrate mounted on the electrostatic chuck, a high frequency power supply for supplying high frequency power for generating plasma from the gas inside the chamber, and a high frequency power supply. An RF filter whose impedance can be changed is provided, and the edge ring and the RF filter are electrically directly connected via a connection portion.

According to the present disclosure, it is possible to appropriately control the tilt angle in the edge region of the substrate in etching.

It is a vertical cross-sectional view which shows the outline of the structure of the etching apparatus which concerns on this embodiment. It is explanatory drawing of the power-source system of the etching apparatus which concerns on this embodiment. It is explanatory drawing which shows the change of the shape of a sheath by the wear of an edge ring, and the occurrence of the inclination (tilt angle) in the incident direction of an ion. It is explanatory drawing which shows the change of the shape of a sheath, and the occurrence of the inclination (tilt angle) in the incident direction of an ion. It is explanatory drawing which shows the relationship between the DC voltage from the DC power source, the impedance of the second RF filter, and the tilt angle. It is explanatory drawing of the power-source system of the etching apparatus which concerns on another embodiment. It is explanatory drawing which shows the relationship between the impedance and the tilt angle of the 2nd RF filter. It is a vertical cross-sectional view which shows an example of the structure of the connection part which concerns on another embodiment. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a top view which shows an example of the structure of the connection part. It is a top view which shows an example of the structure of the connection part. It is a top view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is a vertical cross-sectional view which shows an example of the structure of the connection part. It is explanatory drawing which shows an example of the structure of the connection part and RF filter schematically. It is explanatory drawing which shows an example of the structure of the connection part and RF filter schematically. It is explanatory drawing which shows an example of the structure of the connection part and RF filter schematically. It is a vertical cross-sectional view which shows an example of the structure of the air supply part and the exhaust part which concerns on another embodiment. It is explanatory drawing which shows an example of the flow of the temporary adsorption sequence. It is explanatory drawing which shows an example of the flow of this adsorption sequence.

In the semiconductor device manufacturing process, a semiconductor wafer (hereinafter referred to as “wafer”) is subjected to plasma treatment such as etching. In plasma processing, plasma is generated by exciting a processing gas, and the wafer is processed by the plasma.

The plasma processing is performed by a plasma processing apparatus. Plasma processing equipment typically includes a chamber, stage, and radio frequency (RF) power supply. In one example, the high frequency power supply includes a first high frequency power supply and a second high frequency power supply. The first high frequency power supply supplies the first high frequency power to generate a plasma of gas in the chamber. The second high frequency power supply supplies a second high frequency power for bias to the lower electrode in order to draw ions into the wafer. The chamber defines its internal space as a processing space in which plasma is generated. The stage is provided in the chamber. The stage has a lower electrode and an electrostatic chuck. The electrostatic chuck is provided on the lower electrode. In one example, an edge ring is arranged on the electrostatic chuck so as to surround the wafer placed on the electrostatic chuck. Edge rings are provided to improve the uniformity of plasma processing on the wafer.

The edge ring wears out over time when the plasma treatment is performed. As the edge ring wears, the thickness of the edge ring decreases. As the thickness of the edge ring decreases, the shape of the sheath changes above the edge region of the edge ring and wafer. When the shape of the sheath changes in this way, the incident direction of ions in the edge region of the wafer is inclined with respect to the vertical direction. As a result, the openings formed in the edge regions of the wafer are inclined with respect to the thickness direction of the wafer.

In order to form an opening extending parallel to the thickness direction of the wafer in the edge region of the wafer, the shape of the edge ring and the sheath above the edge region of the wafer is controlled to determine the direction of ion incident on the edge region of the wafer. It is necessary to adjust the tilt (hereinafter, sometimes referred to as "tilt angle"). Therefore, in order to control the shape of the sheath above the edge region of the edge ring and the wafer, for example, Patent Document 1 proposes a plasma processing apparatus configured to apply a negative DC voltage to the edge ring from a DC power supply. Has been done.

By the way, depending on the DC voltage applied to the edge ring, there is an influence such as a discharge occurring between the wafer and the edge ring, so that the DC voltage that can be applied is limited. Therefore, even if an attempt is made to control the tilt angle only by adjusting the DC voltage, there is a limit to the adjustment range of the tilt angle. Further, it is desired to reduce the frequency of edge ring replacement due to wear, but as described above, the tilt angle may not be sufficiently controlled only by adjusting the DC voltage. In such a case, the edge ring replacement interval is improved. I can't cut it.

The technique according to the present disclosure appropriately controls the tilt angle in the edge region of the substrate in etching. Hereinafter, the etching apparatus and the etching method according to the present embodiment will be described with reference to the drawings. In the present specification and the drawings, elements having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

<Etching device>
First, the etching apparatus according to the present embodiment will be described. FIG. 1 is a vertical cross-sectional view showing an outline of the configuration of the etching apparatus 1. FIG. 2 is an explanatory diagram of the power supply system of the etching apparatus 1. The etching apparatus 1 is a capacitive coupling type etching apparatus. The etching apparatus 1 etches the wafer W as a substrate.

As shown in FIG. 1, the etching apparatus 1 has a chamber 10 having a substantially cylindrical shape. The chamber 10 defines a processing space S in which plasma is generated. The chamber 10 is made of, for example, aluminum. The chamber 10 is connected to the ground potential.

Inside the chamber 10, a stage 11 as a substrate support on which the wafer W is placed is housed. The stage 11 has a lower electrode 12, an electrostatic chuck 13, and an edge ring 14. An electrode plate (not shown) made of, for example, aluminum may be provided on the lower surface side of the lower electrode 12.

The lower electrode 12 is made of a conductive metal such as aluminum and has a substantially disk shape.

A refrigerant flow path 15a is formed inside the lower electrode 12. Refrigerant is supplied to the refrigerant flow path 15a from a chiller unit (not shown) provided outside the chamber 10 via the refrigerant inlet pipe 15b. The refrigerant supplied to the refrigerant flow path 15a returns to the chiller unit via the refrigerant outlet flow path 15c. By circulating a refrigerant such as cooling water in the refrigerant flow path 15a, the electrostatic chuck 13, the edge ring 14, and the wafer W can be cooled to a desired temperature.

The electrostatic chuck 13 is provided on the lower electrode 12. In one example, the electrostatic chuck 13 is a member configured to be able to attract and hold both the wafer W and the edge ring 14 by electrostatic force. The upper surface of the central portion of the electrostatic chuck 13 is formed higher than the upper surface of the peripheral portion. The upper surface of the central portion of the electrostatic chuck 13 is a wafer mounting surface on which the wafer W is mounted. In one example, the upper surface of the peripheral edge portion of the electrostatic chuck 13 is an edge ring mounting on which the edge ring 14 is mounted. It becomes a surface.

In one example, a first electrode 16a for sucking and holding the wafer W is provided in the central portion inside the electrostatic chuck 13. A second electrode 16b for attracting and holding the edge ring 14 is provided on the peripheral edge of the electrostatic chuck 13. The electrostatic chuck 13 has a configuration in which electrodes 16a and 16b are sandwiched between insulating materials made of an insulating material.

A DC voltage from a DC power supply (not shown) is applied to the first electrode 16a. Due to the electrostatic force generated by this, the wafer W is attracted and held on the upper surface of the central portion of the electrostatic chuck 13. Similarly, a DC voltage from a DC power source (not shown) is applied to the second electrode 16b. In one example, the edge ring 14 is attracted and held on the upper surface of the peripheral edge of the electrostatic chuck 13 by the electrostatic force generated by the electrostatic force.

In the present embodiment, the central portion of the electrostatic chuck 13 provided with the first electrode 16a and the peripheral portion provided with the second electrode 16b are integrated, but these central portions and peripheral portions are used. May be separate. Further, in the present embodiment, the peripheral edge portion of the electrostatic chuck 13 that holds the edge ring 14 corresponds to the edge ring support in the present disclosure. Further, both the first electrode 16a and the second electrode 16b may be unipolar or bipolar.

Further, in the present embodiment, the edge ring 14 is electrostatically attracted to the electrostatic chuck 13 by applying a DC voltage to the second electrode 16b, but the holding method of the edge ring 14 is not limited to this. For example, the edge ring 14 may be sucked and held using a suction sheet, or the edge ring 14 may be clamped and held. Alternatively, the edge ring 14 may be held by its own weight.

The edge ring 14 is an annular member arranged so as to surround the wafer W placed on the upper surface of the central portion of the electrostatic chuck 13. The edge ring 14 is provided to improve the uniformity of etching. Therefore, the edge ring 14 is made of a material appropriately selected according to etching, and may be made of, for example, Si or SiC.

The stage 11 configured as described above is fastened to a substantially cylindrical support member 17 provided at the bottom of the chamber 10. The support member 17 is made of an insulator such as ceramic or quartz.

Although not shown, the stage 11 may include a temperature control module configured to adjust at least one of the electrostatic chuck 13, the edge ring 14, and the wafer W to a desired temperature. The temperature control module may include a heater, a flow path, or a combination thereof. A temperature control fluid such as a refrigerant or a heat transfer gas flows through the flow path.

A shower head 20 is provided above the stage 11 so as to face the stage 11. The shower head 20 has an electrode plate 21 arranged so as to face the processing space S, and an electrode support 22 provided above the electrode plate 21. The electrode plate 21 functions as a pair of upper electrodes with the lower electrode 12. When the first high frequency power source 50 is electrically connected to the lower electrode 12 as described later, the shower head 20 is connected to the ground potential. The shower head 20 is supported on the upper part (ceiling surface) of the chamber 10 via an insulating shielding member 23.

The electrode plate 21 is formed with a plurality of gas outlets 21a for supplying the processing gas sent from the gas diffusion chamber 22a, which will be described later, to the processing space S. The electrode plate 21 is composed of, for example, a conductor or a semiconductor having a low electrical resistivity with less Joule heat generated.

The electrode support 22 supports the electrode plate 21 in a detachable manner. The electrode support 22 has a structure in which a plasma-resistant film is formed on the surface of a conductive material such as aluminum. This film may be a ceramic film such as a film formed by anodizing or a film formed from yttrium oxide. A gas diffusion chamber 22a is formed inside the electrode support 22. From the gas diffusion chamber 22a, a plurality of gas flow holes 22b communicating with the gas outlet 21a are formed. Further, the gas diffusion chamber 22a is formed with a gas introduction hole 22c connected to a gas supply pipe 33, which will be described later.

Further, a gas supply source group 30 for supplying the processing gas to the gas diffusion chamber 22a is connected to the electrode support 22 via a flow rate control device group 31, a valve group 32, a gas supply pipe 33, and a gas introduction hole 22c. ing.

The gas supply source group 30 has a plurality of types of gas supply sources necessary for etching. The flow rate control device group 31 includes a plurality of flow rate controllers, and the valve group 32 includes a plurality of valves. Each of the plurality of flow rate controllers in the flow rate control device group 31 is a mass flow controller or a pressure control type flow rate controller. In the etching apparatus 1, the processing gas from one or more gas supply sources selected from the gas supply source group 30 is gas through the flow rate control device group 31, the valve group 32, the gas supply pipe 33, and the gas introduction hole 22c. It is supplied to the diffusion chamber 22a. Then, the processing gas supplied to the gas diffusion chamber 22a is dispersed and supplied in a shower shape in the processing space S via the gas flow hole 22b and the gas ejection port 21a.

A baffle plate 40 is provided at the bottom of the chamber 10 between the inner wall of the chamber 10 and the support member 17. The baffle plate 40 is formed by, for example, coating an aluminum material with ceramics such as yttrium oxide. A plurality of through holes are formed in the baffle plate 40. The processing space S communicates with the exhaust port 41 via the baffle plate 40. An exhaust device 42 such as a vacuum pump is connected to the exhaust port 41, and the exhaust device 42 is configured to be able to reduce the pressure in the processing space S.

Further, a wafer W carry-in outlet 43 is formed on the side wall of the chamber 10, and the carry-in outlet 43 can be opened and closed by a gate valve 44.

As shown in FIGS. 1 and 2, the etching apparatus 1 further includes a first high frequency power supply 50, a second high frequency power supply 51, and a matching device 52. The first high-frequency power supply 50 and the second high-frequency power supply 51 are connected to the lower electrode 12 via a matching unit 52.

The first high-frequency power source 50 is a power source that generates high-frequency power for plasma generation. The frequency may be 27 MHz to 100 MHz from the first high frequency power supply 50, and in one example, a high frequency power HF of 40 MHz is supplied to the lower electrode 12. The first high frequency power supply 50 is connected to the lower electrode 12 via the first matching circuit 53 of the matching device 52. The first matching circuit 53 is a circuit for matching the output impedance of the first high-frequency power supply 50 with the input impedance on the load side (lower electrode 12 side). The first high frequency power supply 50 may not be electrically connected to the lower electrode 12, but may be connected to the shower head 20 which is the upper electrode via the first matching circuit 53.

The second high-frequency power source 51 generates high-frequency power (high-frequency bias power) LF for drawing ions into the wafer W, and supplies the high-frequency power LF to the lower electrode 12. The frequency of the high frequency power LF may be in the range of 400 kHz to 13.56 MHz, and in one example, it is 400 kHz. The second high frequency power supply 51 is connected to the lower electrode 12 via the second matching circuit 54 of the matching device 52. The second matching circuit 54 is a circuit for matching the output impedance of the second high-frequency power supply 51 with the input impedance on the load side (lower electrode 12 side). A DC (Direct Current) pulse generator may be used instead of the second high frequency power supply 51.

The etching apparatus 1 further includes a direct current (DC) power supply 60, a switching unit 61, a first RF filter 62, and a second RF filter 63. The DC power supply 60 is electrically connected to the edge ring 14 via the switching unit 61, the second RF filter 63, and the first RF filter 62.

The DC power supply 60 is a power supply that generates a negative DC voltage applied to the edge ring 14. Further, the DC power supply 60 is a variable DC power supply, and the height of the DC voltage can be adjusted.

The switching unit 61 is configured to be able to stop the application of the DC voltage from the DC power supply 60 to the edge ring 14. A person skilled in the art can appropriately design the circuit configuration of the switching unit 61.

The first RF filter 62 and the second RF filter 63 are filters that reduce or block high frequencies, respectively, and are provided to protect the DC power supply 60. The first RF filter 62 reduces or blocks high frequencies of 40 MHz from, for example, the first high frequency power source 50. The second RF filter 63 reduces or blocks the high frequency of 400 kHz from, for example, the second high frequency power supply 51.

In one example, the second RF filter 63 has a variable impedance configuration. That is, the impedance is variable by using a part of the elements of the second RF filter 63 as variable elements. The variable element may be, for example, either a coil (inductor) or a capacitor (capacitor). Further, the same function can be achieved by any variable impedance element such as an element such as a diode, not limited to a coil and a capacitor. Those skilled in the art can appropriately design the number and position of the variable elements. Further, the element itself does not have to be variable, and the impedance may be changed by switching the combination of fixed value elements using a switching circuit. The circuit configurations of the second RF filter 63 and the first RF filter 62 can be appropriately designed by those skilled in the art.

The etching apparatus 1 further includes a measuring instrument (not shown) for measuring the self-bias voltage of the edge ring 14 (or the self-bias voltage of the lower electrode 12 or the wafer W). The configuration of the measuring instrument can be appropriately designed by those skilled in the art.

The etching apparatus 1 described above is provided with a control unit 100. The control unit 100 is, for example, a computer equipped with a CPU, a memory, or the like, and has a program storage unit (not shown). The program storage unit stores a program that controls etching in the etching apparatus 1. The program may be recorded on a computer-readable storage medium and may be installed on the control unit 100 from the storage medium.

<Etching method>
Next, the etching performed by using the etching apparatus 1 configured as described above will be described.

First, the wafer W is carried into the chamber 10 and the wafer W is placed on the electrostatic chuck 13. After that, by applying a DC voltage to the first electrode 16a of the electrostatic chuck 13, the wafer W is electrostatically attracted to and held by the electrostatic chuck 13 by Coulomb force. Further, after the wafer W is carried in, the inside of the chamber 10 is depressurized to a desired degree of vacuum by the exhaust device 42.

Next, the processing gas is supplied from the gas supply source group 30 to the processing space S via the shower head 20. Further, the high-frequency power HF for plasma generation is supplied to the lower electrode 12 by the first high-frequency power source 50 to excite the processing gas to generate plasma. At this time, the high frequency power LF for attracting ions may be supplied by the second high frequency power supply 51. Then, the wafer W is etched by the action of the generated plasma.

When the etching is completed, first, the supply of the high-frequency power HF from the first high-frequency power source 50 and the supply of the processing gas by the gas supply source group 30 are stopped. Further, when the high frequency power LF is supplied during the etching, the supply of the high frequency power LF is also stopped. Next, the supply of the heat transfer gas to the back surface of the wafer W is stopped, and the adsorption and holding of the wafer W by the electrostatic chuck 13 is stopped.

After that, the wafer W is carried out from the chamber 10, and a series of etchings on the wafer W are completed.

In etching, plasma may be generated by using only the high frequency power LF from the second high frequency power supply 51 without using the high frequency power HF from the first high frequency power supply 50.

<Tilt angle control method>
Next, in the above-mentioned etching, a method of controlling the tilt angle will be described. The tilt angle is the inclination (angle) of the ions incident on the edge region of the wafer W with respect to the vertical direction.

FIG. 3 is an explanatory diagram showing a change in the shape of the sheath and an inclination of ions in the incident direction due to wear of the edge ring. The edge ring 14 shown by the solid line in FIG. 3 shows the edge ring 14 in a state where the edge ring 14 is not consumed. The edge ring 14 shown by the dotted line indicates the edge ring 14 whose thickness has been reduced due to its wear. Further, the sheath SH shown by the solid line in FIG. 3 represents the shape of the sheath SH when the edge ring 14 is not worn. The sheath SH shown by the dotted line represents the shape of the sheath SH when the edge ring 14 is in a worn state. Further, in FIG. 3, the arrow indicates the incident direction of the ion when the edge ring 14 is in a worn state.

As shown in FIG. 3, in one example, when the edge ring 14 is not worn, the shape of the sheath SH is kept flat above the wafer W and the edge ring 14. Therefore, the ions are incident on the entire surface of the wafer W in a direction substantially perpendicular (vertical direction). That is, the tilt angle is 0 (zero).

On the other hand, when the edge ring 14 is consumed and its thickness is reduced, the thickness of the sheath SH becomes smaller in the edge region of the wafer W and above the edge ring 14, and the shape of the sheath SH changes to a downward convex shape. As a result, the incident direction of the ions with respect to the edge region of the wafer W is inclined with respect to the vertical direction. In the following description, the tilt angle when the incident direction of the ions is inclined inward with respect to the wafer W is referred to as an inner tilt. When the tilt angle becomes the inner tilt in this way, an opening inclined with respect to the thickness direction is formed in the edge region of the wafer W.

As shown in FIG. 4, when the thickness of the sheath SH becomes larger in the edge region of the wafer W and above the edge ring 14 with respect to the central region of the wafer W, and the shape of the sheath SH becomes an upward convex shape. There can also be. For example, when the bias voltage generated in the edge ring 14 is high, the shape of the sheath SH can be an upward convex shape. In FIG. 4, the arrow indicates the incident direction of the ion. In the following description, the tilt angle when the incident direction of the ions is tilted outward with respect to the wafer W is referred to as an outer tilt.

In the etching apparatus 1 of the present embodiment, the tilt angle is controlled. Specifically, the tilt angle is controlled by adjusting the DC voltage from the DC power supply 60 and the impedance of the second RF filter 63.

[Adjustment of DC voltage]
First, the adjustment of the DC voltage from the DC power supply 60 will be described. In the DC power supply 60, the DC voltage applied to the edge ring 14 is set to a negative voltage having the sum of the absolute value of the self-bias voltage Vdc and the set value ΔV as the absolute value, that is, − (| Vdc | + ΔV). Will be done. The self-bias voltage Vdc is the self-bias voltage of the wafer W, and the lower electrode 12 is supplied with high-frequency power of one or both of them, and the DC voltage from the DC power supply 60 is not applied to the lower electrode 12. Self-bias voltage. The set value ΔV is given by the control unit 100.

The control unit 100 is estimated from the consumption amount of the edge ring 14 (the amount of decrease in the thickness of the edge ring 14 from the initial value) and the etching process conditions (for example, processing time) using a predetermined function or table. The set value ΔV is specified from the consumption amount of the edge ring 14. That is, the control unit 100 inputs the consumption amount of the edge ring 14 and the self-bias voltage to the above function, or refers to the above table using the consumption amount and the self-bias voltage of the edge ring 14 to set the set value ΔV. decide.

In determining the set value ΔV, the control unit 100 determines the difference between the initial thickness of the edge ring 14 and the thickness of the edge ring 14 actually measured using a measuring instrument such as a laser measuring instrument or a camera. It may be used as the amount of consumption of. Alternatively, the control unit 100 may determine the consumption amount of the edge ring 14 from a specific parameter by using another predetermined function or table for determining the set value ΔV. This particular parameter can be any of the self-bias voltage Vdc, the peak value Vpp of the high frequency power HF or the high frequency power LF, the load impedance, the edge ring 14 or the electrical characteristics around the edge ring 14. The electrical characteristics of the edge ring 14 or the periphery of the edge ring 14 may be any of voltage, current value, resistance value including the edge ring 14 and the like at any position around the edge ring 14 or the edge ring 14. Another function or table is predefined to determine the relationship between a particular parameter and the consumption of the edge ring 14. In order to determine the consumption amount of the edge ring 14, the measurement conditions for determining the consumption amount before the actual etching or during the maintenance of the etching apparatus 1, that is, the high frequency power HF, the high frequency power LF, and the processing space S. The etching apparatus 1 is operated under the settings of the pressure of the etching apparatus 1 and the flow rate of the processing gas supplied to the processing space S. Then, the specific parameter is acquired, and the consumption amount of the edge ring 14 can be reduced by inputting the specific parameter into the other function or by referring to the table using the specific parameter. Be identified.

In the etching apparatus 1, a DC voltage is applied from the DC power supply 60 to the edge ring 14 during etching, that is, during a period in which the high frequency power of one or both of the high frequency power HF and the high frequency power LF is supplied. As a result, the shape of the sheath above the edge region of the edge ring 14 and the wafer W is controlled, the inclination of the ions in the incident direction to the edge region of the wafer W is reduced, and the tilt angle is controlled. As a result, openings substantially parallel to the thickness direction of the wafer W are formed over the entire region of the wafer W.

More specifically, during etching, the self-bias voltage Vdc is measured by a measuring instrument (not shown). Further, a DC voltage is applied from the DC power supply 60 to the edge ring 14. The value of the DC voltage applied to the edge ring 14 is − (| Vdc | + ΔV) as described above. | Vdc | is an absolute value of the measured value of the self-bias voltage Vdc acquired by the measuring instrument immediately before, and ΔV is a set value determined by the control unit 100. The DC voltage applied to the edge ring 14 is determined from the self-bias voltage Vdc measured during etching in this way. Then, even if the self-bias voltage Vdc changes, the DC voltage generated by the DC power supply 60 is corrected, and the tilt angle is appropriately corrected.

[Impedance adjustment]
Next, the impedance adjustment of the second RF filter 63 will be described.

FIG. 5 is an explanatory diagram showing the relationship between the DC voltage from the DC power supply 60, the impedance of the second RF filter 63, and the tilt angle. The vertical axis of FIG. 5 shows the tilt angle, and the horizontal axis shows the DC voltage from the DC power supply 60. As shown in FIG. 5, when the absolute value of the DC voltage from the DC power supply 60 is increased, the tilt angle becomes large. The tilt angle can also be increased by adjusting the impedance of the second RF filter 63. That is, by adjusting the impedance in this way, the correlation between the DC voltage and the tilt angle can be offset to the side where the tilt angle becomes large.

As shown in FIG. 3, when the edge ring 14 is consumed, the tilt angle becomes the inner tilt. Therefore, as shown in FIG. 5, when the absolute value of the DC voltage from the DC power supply 60 is increased, the tilt angle becomes large, that is, it becomes the outer side, and the tilt angle can be corrected. However, if the absolute value of the DC voltage is made too high, a discharge will occur between the wafer W and the edge ring 14. Therefore, the DC voltage that can be applied to the edge ring 14 is limited, and even if the tilt angle is controlled only by adjusting the DC voltage, the control range of the tilt angle is limited.

Therefore, as shown in FIG. 5, the impedance of the second RF filter 63 is adjusted to offset the correlation between the DC voltage and the tilt angle to the side where the tilt angle becomes larger. In such a case, the absolute value of the DC voltage from the DC power supply 60 can be increased again to correct the tilt angle to the outer side. Therefore, according to the present embodiment, by adjusting the impedance, the control range of the tilt angle can be increased without changing the adjustment range of the DC voltage.

[Tilt angle control]
As described above, in the present embodiment, the tilt angle is controlled by adjusting the DC voltage from the DC power supply 60 and the impedance of the second RF filter 63. Hereinafter, a specific method for controlling the tilt angle will be described.

First, the edge ring 14 is installed on the electrostatic chuck 13. Then, for example, in the edge region of the wafer W and above the edge ring 14, the sheath shape becomes flat or downward convex, and the tilt angle becomes (zero) or inner tilt. In such a case, the adjustment range of the DC voltage can be increased when the DC voltage from the DC power supply 60 is adjusted to change the tilt angle to the outer side as described later.

Next, etching is performed on the wafer W. With the passage of time for etching, the edge ring 14 is consumed and its thickness is reduced. Then, the thickness of the sheath SH becomes smaller in the edge region of the wafer W and above the edge ring 14, and the tilt angle changes to the inner side.

Therefore, the DC voltage applied from the DC power supply 60 to the edge ring 14 is adjusted. Specifically, the absolute value of the DC voltage is increased according to the amount of consumption of the edge ring 14. The consumption amount of the edge ring 14 is the etching time of the wafer W, the number of processed wafers W, the thickness of the edge ring 14 measured by the measuring instrument, and the electrical characteristics around the edge ring 14 measured by the measuring instrument (for example, the edge). It is determined based on a change in the voltage and current value of an arbitrary point around the ring 14 or a change in the electrical characteristics of the edge ring 14 (for example, the resistance value of the edge ring 14) measured by a measuring instrument. .. Further, the absolute value of the DC voltage may be increased according to the etching time of the wafer W and the number of processed wafers W, regardless of the consumption amount of the edge ring 14. Further, the absolute value of the DC voltage may be increased according to the etching time of the wafer W weighted by the high frequency power and the number of wafers W processed. Then, as described above, the DC voltage is adjusted to the sum of the absolute value of the self-bias voltage Vdc and the set value ΔV, that is, − (| Vdc | + ΔV). Then, as shown in FIG. 5, the tilt angle becomes large and changes to the outer side. As a result, the tilt angle can be corrected to a desired value in the edge region of the wafer W and above the edge ring 14, and the incident direction of the ions can be corrected.

On the other hand, as the wear of the edge ring 14 progresses, the absolute value of the DC voltage increases. If the absolute value of the DC voltage becomes too high, a discharge may occur between the wafer W and the edge ring 14. For example, when the absolute value of the DC voltage reaches the potential difference between the wafer W and the edge ring 14, a discharge can occur.

Therefore, when the absolute value of the DC voltage reaches a predetermined value, the impedance of the second RF filter 63 is adjusted to offset the correlation between the DC voltage and the tilt angle to the side where the tilt angle becomes larger. When the tilt angle is offset in this way, even if the edge ring 14 is further consumed, the DC voltage can be adjusted to correct the tilt angle to a desired value (outer side). The timing for adjusting the impedance may be when the amount of wear of the edge ring 14 reaches a predetermined value. The amount of wear of the edge ring 14 is determined based on the processing time of the wafer W and the thickness measured by the measuring instrument.

As described above, according to the present embodiment, the adjustment range of the tilt angle can be increased by repeatedly adjusting the DC voltage from the DC power supply 60 and adjusting the impedance of the second RF filter 63. Therefore, the tilt angle can be appropriately controlled, that is, the incident direction of the ions can be appropriately adjusted, so that the etching can be performed uniformly.

Further, conventionally, when trying to control the tilt angle only by the DC voltage from the DC power supply 60, for example, when the absolute value of the DC voltage reaches the upper limit, it is necessary to replace the edge ring 14. In this respect, in the present embodiment, by adjusting the impedance of the second RF filter 63, the tilt angle adjustment range can be increased without replacing the edge ring 14. Therefore, the replacement interval of the edge ring 14 can be lengthened to reduce the replacement frequency.

<Other embodiments>
In the above embodiment, the DC power supply 60 is connected to the edge ring 14 via the switching unit 61, the first RF filter 62, and the second RF filter 63, but a DC voltage is applied to the edge ring 14. The power supply system to be applied is not limited to this. For example, the DC power supply 60 may be electrically connected to the edge ring 14 via the switching unit 61, the second RF filter 63, the first RF filter 62, and the lower electrode 12. In such a case, the lower electrode 12 and the edge ring 14 are directly electrically coupled, and the self-bias voltage of the edge ring 14 becomes the same as the self-bias voltage of the lower electrode 12.

Here, when the lower electrode 12 and the edge ring 14 are directly electrically coupled, the sheath thickness on the edge ring 14 cannot be adjusted due to, for example, the capacitance under the edge ring 14 determined by the hard structure, and direct current is applied. An outer tilt condition can occur even though no voltage is applied. In this regard, in the present disclosure, the tilt angle can be controlled by adjusting the DC voltage from the DC power supply 60 and the impedance of the second RF filter 63, so that the tilt angle is adjusted to the inner side. Can be done.

<Other embodiments>
In the above embodiment, the DC voltage from the DC power supply 60 is adjusted according to the amount of consumption of the edge ring 14, but the adjustment timing of the DC voltage is not limited to this. For example, the DC voltage may be adjusted according to the processing time of the wafer W. Alternatively, for example, the processing time of the wafer W and a predetermined parameter such as high frequency power may be combined to determine the adjustment timing of the DC voltage.

<Other embodiments>
In the above embodiment, the impedance of the second RF filter 63 is adjusted after adjusting the DC voltage from the DC power supply 60, but the order may be reversed. That is, after adjusting the impedance, the DC voltage may be adjusted. Further, the DC voltage may be adjusted and the impedance may be adjusted at the same time. Alternatively, the tilt angle may be controlled by adjusting only the DC voltage, or the tilt angle may be controlled by adjusting only the impedance.

For example, as shown in FIG. 6, the DC power supply 60 and the switching unit 61 may not be connected to the edge ring 14. Even in such a case, the tilt angle can be controlled only by adjusting the impedance of the second RF filter 63 as shown in FIG. 7. The vertical axis of FIG. 7 indicates the tilt angle, and the horizontal axis indicates the impedance. In the example shown in FIG. 7, the impedance and the tilt angle are in a proportional relationship. Further, in the example shown in FIG. 7, the tilt angle is increased by increasing the impedance, but depending on the configuration of the second RF filter 63, the tilt angle may be decreased by increasing the impedance. It is possible. The relationship between the impedance and the tilt angle is not limited because it depends on the design of the second RF filter 63.

Further, when adjusting only the impedance of the second RF filter 63, the impedance may be adjusted according to the amount of wear of the edge ring 14 as in the above embodiment, or the processing time of the wafer W and the like. Impedance may be adjusted according to the above. And in this embodiment as well, the same effect as that of the above embodiment can be enjoyed, that is, the tilt angle can be appropriately controlled. Moreover, since the DC power supply 60 and the switching unit 61 can be omitted, energy saving and space saving of the etching apparatus 1 can be realized.

As described above, the frequency of the high frequency power (high frequency bias power) LF supplied from the second high frequency power supply 51 is 400 kHz to 13.56 MHz, more preferably 5 MHz or less. When etching a wafer W with a high aspect ratio during the etching process, high ion energy is required to realize the vertical shape of the etched pattern. Therefore, as a result of diligent studies by the present inventors, it has been found that by setting the frequency of the high-frequency power LF to 5 MHz or less, the followability of ions to changes in the high-frequency electric field is improved, and the controllability of ion energy is improved.

On the other hand, when the frequency of the high frequency power LF is set to a low frequency of 5 MHz or less, the effect of making the impedance of the second RF filter 63 variable may be reduced. That is, the controllability of the tilt angle may be reduced by adjusting the impedance of the second RF filter 63. For example, in FIG. 6, when the electrical connection between the edge ring 14 and the second RF filter 63 is non-contact or capacitive coupling, the tilt angle can be adjusted appropriately even if the impedance of the second RF filter 63 is adjusted. I can't control it. Therefore, in the present embodiment, the edge ring 14 and the second RF filter 63 are directly electrically connected.

The edge ring 14 and the second RF filter 63 are electrically directly connected via a connecting portion. The edge ring 14 and the connection portion come into contact with each other, and a direct current is conducted through the connection portion. Hereinafter, an example of the structure of the connecting portion (hereinafter, may be referred to as “contact structure”) will be described.

As shown in FIG. 8, the connecting portion 200 has a conductor structure 201 and a conductor member 202. The conductor structure 201 connects the edge ring 14 and the second RF filter 63 via the conductor member 202. Specifically, one end of the conductor structure 201 is connected to the second RF filter 63, and the other end is exposed on the upper surface of the lower electrode 12 and comes into contact with the conductor member 202.

The conductor member 202 is provided, for example, in a space formed between the lower electrode 12 and the edge ring 14 on the side of the electrostatic chuck 13. The conductor member 202 comes into contact with the conductor structure 201 and the lower surface of the edge ring 14, respectively. The conductor member 202 is made of, for example, a conductor such as metal. The configuration of the conductor member 202 is not particularly limited, but an example is shown in each of FIGS. 9A to 9F.

As shown in FIG. 9A, a coil spring that extends in the horizontal direction while being spirally wound may be used for the conductor member 202. As shown in FIG. 9B, a leaf spring urged in the vertical direction may be used for the conductor member 202. As shown in FIG. 9C, a spring that extends in the vertical direction while being spirally wound may be used for the conductor member 202. Then, due to the weight of the edge ring 14, the conductor member 202 is brought into close contact with each of the conductor structure 201 and the lower surface of the edge ring 14, and the conductor structure 201 and the edge ring 14 are electrically connected. Further, the conductor member 202 is an elastic body, and an elastic force acts in the vertical direction. Due to this elastic force, the conductor member 202 is in close contact with the conductor structure 201 and the lower surface of the edge ring 14.

As described above, the edge ring 14 is attracted and held on the upper surface of the peripheral edge of the electrostatic chuck 13 by the electrostatic force generated by the second electrode 16b. Then, when the conductor members 202 shown in FIGS. 9A to 9C are used, the conductor member 202 is in close contact with the conductor structure 201 and the lower surface of the edge ring 14 even by this electrostatic force, and the conductor structure 201 and the edge ring 14 are brought into close contact with each other. Is electrically connected. Then, by adjusting the balance between the weight of the edge ring 14, the elastic force of the conductor member 202, and the electrostatic force acting on the edge ring 14, the conductor member 202 is desired to be applied to the conductor structure 201 and the lower surface of the edge ring 14, respectively. Adheres with the contact pressure of.

As shown in FIG. 9D, the conductor member 202 may use a pin that moves up and down by an elevating mechanism (not shown). In such a case, as the conductor member 202 rises, the conductor member 202 comes into close contact with the conductor structure 201 and the lower surface of the edge ring 14. Then, by adjusting the balance between the weight of the edge ring 14, the pressure acting when the conductor member 202 moves up and down, and the electrostatic force acting on the edge ring 14, the conductor member 202 has the conductor structure 201 and the lower surface of the edge ring 14, respectively. In close contact with the desired contact pressure.

As shown in FIG. 9E, a wire connecting the conductor structure 201 and the edge ring 14 may be used for the conductor member 202. One end of the wire is joined to the conductor structure 201, and the other end is joined to the lower surface of the edge ring 14. The wire may be joined by ohmic contact with the lower surface of the conductor structure 201 or the edge ring 14, and as an example, the wire is welded or crimped. As shown in FIG. 9F, a fixing screw for fixing the edge ring 14 to the electrostatic chuck 13 may be used for the conductor member 202. The fixing screw inserts the edge ring 14 and comes into contact with the conductor structure 201. When a wire or a fixing screw is used for the conductor member 202 in this way, the conductor member 202 is surely in contact with each of the lower surface of the conductor structure 201 and the edge ring 14, and the conductor structure 201 and the edge ring 14 are electrically connected to each other. NS. In such a case, since the edge ring 14 is fixed to the electrostatic chuck 13 by a wire or a fixing screw, the second electrode 16b for electrostatically attracting the edge ring 14 can be omitted.

As described above, regardless of which of the conductor members 202 shown in FIGS. 9A to 9F is used, the edge ring 14 and the second RF filter 63 are electrically directly connected via the connecting portion 200 as shown in FIG. can do. Therefore, the frequency of the high-frequency power LF can be set to a low frequency of 5 MHz or less, and the controllability of ion energy can be improved. Further, as described above, by adjusting the impedance of the second RF filter 63, the adjustment range of the tilt angle can be increased and the tilt angle can be controlled to a desired value.

In the above embodiment, as the conductor member 202, the coil spring shown in FIG. 9A, the leaf spring shown in FIG. 9B, the spring shown in FIG. 9C, the pin shown in FIG. 9D, and the wire shown in FIG. 9E. Although the fixing screws shown in FIG. 9F are illustrated, these may be used in combination.

Next, the arrangement of the conductor member 202 in a plan view will be described. 10A to 10C show an example of the planar arrangement of the conductor member 202, respectively. As shown in FIGS. 10A and 10B, the connecting portion 200 may include a plurality of conductor members 202, and the plurality of conductor members 202 may be provided concentrically with the edge ring 14 at equal intervals. In the example of FIG. 10A, the conductor members 202 are provided at eight locations, and in FIG. 10B, the conductor members 202 are provided at 24 locations. Further, as shown in FIG. 10C, the conductor member 202 may be provided in an annular shape on a concentric circle with the edge ring 14.

From the viewpoint of uniformly etching and making the shape of the sheath uniform (from the viewpoint of process uniformity), as shown in FIG. 10C, the conductor member 202 is provided in an annular shape with respect to the edge ring 14, and the contact with the edge ring 14 is provided. Is preferably performed uniformly on the circumference. Further, also from the viewpoint of process uniformity, even when a plurality of conductor members 202 are provided as shown in FIGS. 10A and 10B, the plurality of conductor members 202 are arranged at equal intervals in the circumferential direction of the edge ring 14 to form an edge. It is preferable that the contact points with respect to the ring 14 are provided point-symmetrically. Furthermore, it is better to increase the number of conductor members 202 as in the example of FIG. 10B as compared with the example of FIG. 10A so that the conductor members 202 are closer to an annular shape as shown in FIG. 10C. The number of conductor members 202 is not particularly limited, but in order to ensure symmetry, 3 or more are preferable, and for example, 3 to 36 are exemplified.

However, in order to avoid interference with other members due to the device configuration, it may be difficult to make the conductor member 202 annular or increase the number of conductor members 202. Therefore, the planar arrangement of the conductor member 202 can be appropriately set in consideration of the conditions for process uniformity, the constraint conditions for the device configuration, and the like.

The contact structure with respect to the edge ring 14 is not limited to the examples shown in FIGS. 8 and 9A to 9F. 11A to 11G show other examples of the configuration of the connection unit 200.

As shown in FIG. 11A, the connecting portion 200 may omit the conductor member 202 and have only the conductor structure 201. The conductor structure 201 comes into direct contact with the lower surface of the edge ring 14. At this time, the conductor structure 201 is brought into close contact with the lower surface of the edge ring 14 at a desired contact pressure due to the weight of the edge ring 14 and the electrostatic force when the edge ring 14 is attracted and held by the electrostatic chuck 13. Even in such a case, the edge ring 14 and the second RF filter 63 can be electrically directly connected via the connecting portion 200 (conductor structure 201).

As shown in FIG. 11B, the connecting portion 200 may have a clamp member 210 instead of the conductor member 202 that contacts the lower surface of the edge ring 14. The clamp member 210 comes into contact with the conductor structure 201 and the edge ring 14, respectively. The conductor member 202 is made of, for example, a conductor such as metal.

The clamp member 210 has a substantially U-shape with an opening in the radial direction in the side view. The clamp member 210 is provided so as to come into contact with the upper surface and the outer surface of the edge ring 14 on the radial outer side of the edge ring 14 and to sandwich the edge ring 14. Then, the clamp member 210 sandwiches the edge ring 14 on the conductor structure 201 side so that the edge ring 14 is brought into close contact with the conductor structure 201, and the edge ring 14 and the second RF filter 63 are electrically directly connected. Further, the clamp member 210 is brought into close contact with the conductor structure at a desired contact pressure due to the electrostatic force when the edge ring 14 is attracted and held by the electrostatic chuck 13, and the edge ring 14 and the second RF filter 63 are electrically connected. Connected directly to.

As shown in FIG. 11C, the connecting portion 200 may have a conductor member 220 that contacts the outer surface of the edge ring 14 instead of the conductor member 202 that contacts the lower surface of the edge ring 14. In such a case, the conductor structure 201 is provided on the radial outer side of the electrostatic chuck 13 and the edge ring 14. The conductor member 220 comes into contact with the conductor structure 201 and the outer surface of the edge ring 14. In the illustrated example, the coil spring shown in FIG. 9A was used for the conductor member 220, but the leaf spring shown in FIG. 9B, the spring shown in FIG. 9C, the pin shown in FIG. 9D, and the wire shown in FIG. 9E. , The fixing screw shown in FIG. 9F or the like may be used. In either case, the conductor member 220 is in close contact with the conductor structure 201 and the outer surface of the edge ring 14, and the edge ring 14 and the second RF filter 63 are electrically directly connected.

As shown in FIG. 11D, the connecting portion 200 may have a conductor member 230 that contacts the inner surface of the edge ring 14 instead of the conductor member 202 that contacts the lower surface of the edge ring 14. In such a case, a protruding portion 14a protruding downward is formed on the outer peripheral portion of the edge ring 14. The conductor member 230 comes into contact with the conductor structure 201 and the inner surface of the protrusion 14a of the edge ring 14. In the illustrated example, the coil spring shown in FIG. 9A was used for the conductor member 230, but the leaf spring shown in FIG. 9B, the spring shown in FIG. 9C, the pin shown in FIG. 9D, and the wire shown in FIG. 9E. , The fixing screw shown in FIG. 9F or the like may be used. In either case, the conductor member 220 is in close contact with the conductor structure 201 and the inner surface of the edge ring 14, and the edge ring 14 and the second RF filter 63 are electrically directly connected.

The planar arrangement of the clamp member 210 shown in FIG. 11B, the conductor member 220 shown in FIG. 11C, and the conductor member 230 shown in FIG. 11D is the same as the planar arrangement of the conductor member 202 shown in FIGS. 10A to 10C. It may be similar. That is, the clamp members 210, the conductor members 220, and 230 may be provided at equal intervals on the concentric circle with the edge ring 14, or may be provided in an annular shape on the concentric circle with the edge ring 14, respectively.

As shown in FIGS. 11E and 11F, a conductor 240 may be provided between the conductor member 202 of the connecting portion 200 and the edge ring. The conductor 240 is made of, for example, metal or the like. The conductor 240 shown in FIG. 11E contacts the conductor member 202 and the lower surface of the edge ring 14. The conductor 240 shown in FIG. 11F is formed by vapor deposition on the lower surface of the edge ring 14, for example, and comes into contact with the conductor member 202. In either case, the edge ring 14 and the second RF filter 63 are electrically directly connected. The number of conductors 240 is not particularly limited. For example, a plurality of conductors 240 may be provided, and the entire plurality of conductors 240 may have a shape close to an annular shape.

As shown in FIG. 11G, the connecting portion 200 may have conductor members 250 and 251 instead of the conductor member 202 that contacts the lower surface of the edge ring 14. In the illustrated example, as the conductor member 230, the coil spring shown in FIG. 9A was used for the conductor member 250, and the leaf spring shown in FIG. 9B was used for the conductor member 251. The spring shown in FIG. 9C, the pin shown in FIG. 9D, the wire shown in FIG. 9E, the fixing screw shown in FIG. 9F, and the like may be used.

The conductor member 250 is provided between the conductor structure 201a and the conductor structure 201b, and comes into contact with each of the conductor structure 201a and the conductor structure 201b. The conductor member 251 is provided between the conductor structure 201b and the lower surface of the edge ring 14, and comes into contact with each of the conductor structure 201b and the lower surface of the edge ring 14. Insulating members 260 are provided around the connecting portion 200 and on the radial outer side of the edge ring 14.

The plane arrangement of the conductor members 250 and 251 shown in FIG. 11G may be the same as the plane arrangement of the conductor members 202 shown in FIGS. 10A to 10C. That is, the clamp members 210, the conductor members 220, and 230 may be provided at equal intervals on the concentric circle with the edge ring 14, or may be provided in an annular shape on the concentric circle with the edge ring 14, respectively.

Next, the relationship between the connection unit 200 and the first RF filter 62 and the second RF filter 63 will be described. 12A to 12C schematically show an example of the configuration of the connection portion 200, the first RF filter 62, and the second RF filter 63, respectively.

As shown in FIG. 12A, for example, when one first RF filter 62 and one second RF filter 63 are provided for each of the eight conductor members 202, the connecting portion 200 further includes a relay member 270. You may be doing it. Although FIG. 12A shows the case where the relay member 270 is provided in the connection portion 200 shown in FIG. 10A, the relay member 270 can be provided in the connection portion 200 shown in either FIG. 10B or FIG. 10C. .. Further, a plurality of relay members 270 may be provided.

The relay member 270 is provided in an annular shape concentrically with the edge ring 14 in the conductor structure 201 between the conductor member 202 and the second RF filter 63. The relay member 270 is connected to the conductor member 202 by a conductor structure 201a. That is, eight conductor structures 201a extend radially from the relay member 270 in a plan view and are connected to each of the eight conductor members 202. Further, the relay member 270 is connected to the second RF filter 63 via the first RF filter 62 by the conductor structure 201b.

In such a case, for example, even when the second RF filter 63 is not arranged at the center of the edge ring 14, the electrical characteristics (arbitrary voltage, current value) of the relay member 270 are uniformly performed on the circumference. Further, the electrical characteristics for each of the eight conductor members 202 can be made uniform. As a result, etching can be performed uniformly and the shape of the sheath can be made uniform.

As shown in FIG. 12B, for example, for eight conductor members 202, a plurality of first RF filters 62, for example, eight may be provided, and one second RF filter 63 may be provided. As described above, the number of the first RF filters 62 can be appropriately set with respect to the number of the conductor members 202. In the example of FIG. 12B, the relay member 270 may be provided.

As shown in FIG. 12C, even if a plurality of first RF filters 62, for example eight, and a plurality of second RF filters 63, for example eight, are provided for, for example, eight conductor members 202. good. As described above, the number of the second RF filters 63 whose impedance is variable can be appropriately set with respect to the number of the conductor members 202. Also in the example of FIG. 12C, the relay member 270 may be provided.

By providing a plurality of second RF filters 63 having variable impedances, it is possible to individually and independently control the electrical characteristics of the plurality of conductor members 202. As a result, the electrical characteristics for each of the plurality of conductor members 202 can be made uniform, and the uniformity of the process can be improved.

<Other embodiments>
Next, a sequence when the edge ring 14 is electrostatically attracted to the electrostatic chuck 13 will be described. In this sequence, the air supply unit 300 and the exhaust unit 301 provided in the etching apparatus 1 as shown in FIG. 13 are used. The air supply unit 300 supplies gas, for example, helium gas, to the edge ring 14 surface via the pipe 310. The exhaust unit 301 evacuates the lower surface of the edge ring 14 via the pipe 310. The pipe 310 is provided with a pressure sensor (not shown) for measuring the pressure inside the pipe 310. In the illustrated example, the connecting portion 200 includes the conductor member 202, but the connecting portion 200 may have the other contact structure described above.

The electrostatic adsorption sequence of the edge ring 14 with respect to the electrostatic chuck 13 is divided into a temporary adsorption sequence and a main adsorption sequence. That is, in the temporary suction, the edge ring 14 is positioned and held with respect to the electrostatic chuck 13. After that, in the main adsorption, the edge ring 14 is electrostatically attracted and held with respect to the electrostatic chuck 13, and the wafer W is in a state where it can be etched (idling state). The temporary adsorption and the main adsorption may be performed continuously or intermittently.

[Temporary adsorption sequence]
FIG. 14 is an explanatory diagram showing an example of the flow of the temporary adsorption sequence of the edge ring 14. Temporary adsorption of the edge ring 14 is performed in a state where the inside of the chamber 10 is open to the atmosphere.

First, the edge ring 14 is installed on the upper surface of the electrostatic chuck 13 (step A1 in FIG. 14). Then, the lower surface of the edge ring 14 and the conductor member 202 come into contact with each other (step A2 in FIG. 14). In step A2, since the edge ring 14 is not attracted and held by the electrostatic chuck 13 and receives the elastic force (reaction force) of the conductor member 202, the edge ring 14 is moved from a predetermined installation position. It is located above.

Next, the gap between the edge ring 14 and the electrostatic chuck 13 is adjusted (step A3 in FIG. 14). Here, when the edge ring 14 is installed in step A1, if air is present between the edge ring 14 and the electrostatic chuck 13, the edge ring 14 slides sideways and is installed. Therefore, in step A3, the gap between the edge ring 14 and the electrostatic chuck 13 is adjusted to make the gap uniform in the circumferential direction. At this time, the edge ring 14 is located above the installation position predetermined by the elastic force of the conductor member 202, and the contact area with the electrostatic chuck 13 is minimized. Since the edge ring 14 is slightly separated from the electrostatic chuck 13 in this way, it is easy to adjust the gap. Moreover, since the contact area is minimized, it is possible to suppress the generation of dust due to contact.

After that, the lower surface of the edge ring 14 is held in a vacuumed state by the exhaust unit 301 (step A4 in FIG. 14). In the temporary adsorption, the edge ring 14 is not electrostatically adsorbed. In this way, the edge ring 14 is held in a positioned state.

[Main adsorption sequence]
FIG. 15 is an explanatory diagram showing an example of the flow of the main adsorption sequence of the edge ring 14. The main adsorption of the edge ring 14 is performed in a state where the inside of the chamber 10 is depressurized to a desired degree of vacuum after the temporary adsorption.

First, the inside of the chamber 10 is evacuated by the exhaust device 42 (step B1 in FIG. 15). At this time, the lower surface of the edge ring 14 is evacuated by the exhaust unit 301.

Next, a DC voltage is applied to the second electrode 16b to electrostatically attract the edge ring 14 to the electrostatic chuck 13 (step B2 in FIG. 15). At this time, the exhaust device 42 continuously evacuates the inside of the chamber 10 (step B3 in FIG. 15). Further, the exhaust unit 301 continuously evacuates the lower surface of the edge ring 14.

Next, it is confirmed whether or not the pressure inside the chamber 10 (hereinafter, referred to as “chamber pressure”) has reached a specified value (step B4 in FIG. 15). Then, when the chamber pressure does not reach the specified value, the exhaust unit 301 continuously evacuates the lower surface of the edge ring 14 and the exhaust device 42 evacuates the inside of the chamber 10 (step B5 in FIG. 15). The process ends (step B6 in FIG. 15).

On the other hand, in step B4, when the chamber pressure reaches a specified value, the evacuation of the lower surface of the edge ring 14 by the exhaust unit 301 is stopped (step B7 in FIG. 15). After that, gas is supplied from the air supply unit 300 to the lower surface of the edge ring 14, and when the pressure inside the pipe 310 stabilizes, the gas supply from the air supply unit 300 is stopped (step B8 in FIG. 15).

Next, using the pressure sensor provided in the pipe 310, the pressure acting on the lower surface of the edge ring 14 (hereinafter referred to as “bottom pressure”) is confirmed (step B9 in FIG. 15). Further, the lower surface of the edge ring 14 is evacuated by the exhaust unit 301 (step B10 in FIG. 15).

Here, if the edge ring 14 is properly adsorbed and held in a state where the inside of the pipe 310 is filled with gas, the amount of gas leaking from the pipe 310 is small. On the other hand, if the edge ring 14 is not properly adsorbed and held, a large amount of gas leaks from the pipe 310. Therefore, the pressure on the lower surface of the edge ring 14 is confirmed (step B11 in FIG. 15). That is, in step B11, a gas leak from the pipe 310 is confirmed. Then, when the pressure on the lower surface of the edge ring 14 does not reach the specified value, the exhaust unit 301 continuously evacuates the lower surface of the edge ring 14 and the exhaust device 42 evacuates the inside of the chamber 10 (FIG. 15). Step B5) ends the process (step B6 in FIG. 15).

On the other hand, in step B11, when the lower surface pressure of the edge ring 14 reaches a specified value, the process ends normally (step B12 in FIG. 15). Then, the wafer W is maintained in a state where it can be etched (idling state). In this idling state, the exhaust unit 301 continuously evacuates the lower surface of the edge ring 14, and the second electrode 16b also continuously electrostatically attracts the edge ring 14.

When the edge ring 14 is actually attracted as in the above embodiment, an electrostatic force acts between the edge ring 14 and the electrostatic chuck 13. Then, by adjusting the balance between the weight of the edge ring 14, the elastic force of the conductor member 202, and the electrostatic force acting on the edge ring 14, the conductor member 202 is desired to be applied to the conductor structure 201 and the lower surface of the edge ring 14, respectively. Adheres with the contact pressure of.

The edge ring 14 may be replaced automatically by using a transport device (not shown) provided outside the etching device 1. The replacement of the edge ring 14 can be performed without opening the inside of the chamber 10 to the atmosphere. Then, when the edge ring 14 is replaced, the temporary adsorption sequence and the present adsorption sequence of the present embodiment can be applied, and the same effect as that of the present embodiment can be enjoyed.

<Other embodiments>
In the above embodiment, the impedance of the second RF filter 63 is made variable, but the impedance of the first RF filter 62 may be made variable, or the impedance of both the RF filters 62 and 63 may be made variable. good. Further, in the above embodiment, two RF filters 62 and 63 are provided for the DC power supply 60, but the number of RF filters is not limited to this, and may be one, for example.

<Other embodiments>
The etching apparatus 1 of the above embodiment is a capacitive coupling type etching apparatus, but the etching apparatus to which the present disclosure is applied is not limited to this. For example, the etching apparatus may be an inductively coupled etching apparatus.

The embodiments disclosed this time should be considered to be exemplary in all respects and not restrictive. The above embodiments may be omitted, replaced or modified in various forms without departing from the scope of the appended claims and their gist.

1 Etching device 10 Chamber 11 Stage 12 Lower electrode 13 Electrostatic chuck 14 Edge ring 50 First high frequency power supply 51 Second high frequency power supply 62 First RF filter 63 Second RF filter W wafer

One aspect of the present disclosure is an apparatus for etching a substrate, which is a chamber, a substrate support provided inside the chamber, an electrode, an electrostatic chuck provided on the electrode, and the above. A high frequency that supplies high frequency power to generate plasma from the substrate support having a conductive edge ring arranged so as to surround the substrate mounted on the electrostatic chuck and the gas inside the chamber. A power supply, an RF filter whose impedance can be changed, and a control unit are provided, and the edge ring and the RF filter are electrically directly connected via a connection unit, and the control unit obtains the impedance. By changing the voltage, the voltage generated in the edge ring can be changed .

One aspect of the present disclosure is an apparatus for etching a substrate, which is a chamber, a substrate support provided inside the chamber, an electrode, an electrostatic chuck provided on the electrode, and the above. A high frequency that supplies high frequency power to generate plasma from the substrate support having a conductive edge ring arranged so as to surround the substrate mounted on the electrostatic chuck and the gas inside the chamber. A power supply, a high-frequency power supply for substrate bias connected to the substrate support, an RF filter whose impedance can be changed, and a control unit are provided, and the edge ring and the RF filter are electrically connected via the connection unit. The control unit is configured to be able to change the voltage generated in the edge ring by changing the impedance, and the high frequency power supply for substrate bias is connected to the edge ring. Not .

Claims (13)

A device that etches the substrate
With the chamber
A substrate support provided inside the chamber, an electrode, an electrostatic chuck provided on the electrode, and an edge ring arranged so as to surround the substrate mounted on the electrostatic chuck. With the substrate support having
A high-frequency power supply that supplies high-frequency power to generate plasma from the gas inside the chamber, and
RF filter with variable impedance and
With
An etching apparatus in which the edge ring and the RF filter are electrically directly connected via a connection portion. The etching apparatus according to claim 1, wherein the frequency of the high frequency power supplied from the high frequency power supply is 5 MHz or less. The etching apparatus according to claim 1 or 2, wherein the connecting portion includes a conductor structure for connecting the edge ring and the RF filter. The etching apparatus according to claim 3, wherein the connecting portion further includes a conductor member provided between the edge ring and the conductor structure. The conductor member is an elastic body and
The etching apparatus according to claim 4, wherein the contact pressure acting between the edge ring and the conductor structure is adjusted by the elastic force of the conductor member. The connecting portion includes a plurality of the conductor members.
The etching apparatus according to claim 4 or 5, wherein the plurality of conductor members are provided concentrically with the edge ring at equal intervals. The etching apparatus according to claim 4 or 5, wherein the conductor member is provided in an annular shape on a concentric circle with the edge ring. The etching apparatus according to claim 3, wherein the connecting portion further includes a clamp member that sandwiches the edge ring on the conductor structure side and connects the edge ring and the conductor structure. The etching apparatus according to any one of claims 3 to 8, wherein the connecting portion further includes a relay member provided in an annular shape on a concentric circle with the edge ring in the conductor structure. The edge ring is attracted and held on the edge ring support by electrostatic force.
The etching apparatus according to any one of claims 3 to 9, wherein the contact pressure acting between the edge ring and the conductor structure is adjusted by the electrostatic force. An air supply unit that supplies gas to the lower surface of the edge ring,
An exhaust unit that evacuates the lower surface of the edge ring and
A control unit that controls the air supply unit and the exhaust unit,
Further prepare
10. The control unit controls the air supply unit and the exhaust unit so that a desired pressure acts on the lower surface of the edge ring when the edge ring is held on the electrostatic chuck. Etching device. The etching apparatus according to any one of claims 1 to 11, further comprising one or more second RF filters different from the RF filter having a variable impedance. It is a method of etching a substrate using an etching device.
The etching apparatus
With the chamber
A substrate support provided inside the chamber, an electrode, an electrostatic chuck provided on the electrode, and an edge ring arranged so as to surround the substrate mounted on the electrostatic chuck. With the substrate support having
A high-frequency power supply that supplies high-frequency power to generate plasma from the gas inside the chamber, and
RF filter with variable impedance and
With
The edge ring and the RF filter are electrically directly connected via a connection.
The method is an etching method including a step of adjusting the impedance so as to correct a tilt angle in an edge region of a substrate mounted on the electrostatic chuck to a desired value.

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