JP2022007865A - Etching device and etching method - Google Patents

Abstract

To appropriately control a tilt angle in an edge region of a substrate in etching.SOLUTION: A device for etching a substrate comprises: a chamber; a substrate supporting body that is provided inside the chamber and has an electrode, an electrostatic chuck provided on the electrode, and an edge ring arranged so as to surround the substrate placed on the electrostatic chuck; a high-frequency power supply that supplies a high-frequency power for generating a plasma from a gas in the chamber; a DC power supply that applies a DC voltage of negative polarity to the edge ring; an RF filter with variable impedance; and a controller that controls the DC voltage and the impedance to adjust a tilt angle in an edge region of the substrate placed on the electrostatic chuck.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 provided with 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 plasma-treats the wafer. Has been done. In this plasma etching 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. As a result, in the edge region of the wafer, the tilt angle indicating the inclination of the recess formed by etching with respect to the thickness direction of the wafer is corrected.

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 a device 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. A DC power supply that applies a negative DC voltage to the edge ring, an RF filter that can change the impedance, and an edge region of a substrate that is mounted on the electrostatic chuck by controlling the DC voltage and the impedance. It is provided with a control unit for adjusting the tilt angle in.

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 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 and the occurrence of the inclination of an ion in the incident direction due to the wear of an edge ring. It is explanatory drawing which shows the change of the shape of a sheath, and the occurrence of the inclination of an ion in the incident direction. 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 correction angle. It is explanatory drawing which shows the control method of a tilt angle. It is explanatory drawing which shows the control method of a tilt angle. It is explanatory drawing which shows the control method of a tilt angle. It is explanatory drawing which shows the control method of a tilt angle. It is a vertical sectional view which shows an example of the structure of the connection part which concerns on another embodiment. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical 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 sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical sectional view which shows an example of the structure of the connection part. It is a vertical 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 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. It is explanatory drawing of the power-source system of the etching apparatus which concerns on other embodiment. It is explanatory drawing which shows the relationship between the impedance of the 2nd RF filter and the tilt correction angle. It is a vertical sectional view which shows an example of the structure of the connection part which concerns on another embodiment. It is a vertical sectional view which shows an example of the structure of the air supply part and the exhaust part which concerns on another embodiment.

In the semiconductor device manufacturing process, a semiconductor wafer (hereinafter referred to as “wafer”) is subjected to plasma processing 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 the 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 comprises 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. Plasma is generated in the interior space of the chamber. The stage is provided in the chamber. The stage has a lower electrode and an electrostatic chuck 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 and the thickness of the edge ring decreases with the passage of time when the plasma treatment is performed. As the thickness of the edge ring decreases, the shape of the sheath changes above the edge ring and the edge region of the wafer. When the shape of the sheath changes in this way, the incident direction of the ions in the edge region of the wafer is inclined with respect to the vertical direction. As a result, the recess formed in the edge region of the wafer is inclined with respect to the thickness direction of the wafer.

In order to form a recess extending in 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 tilt the ion in the direction of incidence on the edge region of the wafer. Need to be adjusted. 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 from a DC power supply to the edge ring. 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 there is a limitation on the magnitude of the DC voltage that can be applied. Therefore, even if an attempt is made to control the incident angle of ions only by adjusting the DC voltage, the adjustment range is limited. In addition, it is desirable to reduce the frequency of edge ring replacement due to wear, but as described above, it may not be possible to sufficiently control the ion incident angle simply by adjusting the DC voltage. In such cases, the frequency of edge ring replacement should be reduced. I can't improve it.

The technique according to the present disclosure appropriately controls the tilt angle by vertically incident ions 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, the elements having substantially the same functional configuration are designated by the same reference numerals, so that duplicate description will be omitted.

<Etching equipment>
First, the etching apparatus according to this 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 device 1 is a capacitive coupling type etching device. 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. 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 material, for example, a metal such as aluminum, and has a substantially disk shape.

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 medium such as a refrigerant or a heat transfer gas flows through the flow path.

In one example, the flow path 15a is formed inside the lower electrode 12. A temperature control medium is supplied to the flow path 15a from a chiller unit (not shown) provided outside the chamber 10 via an inlet pipe 15b. The temperature control medium supplied to the flow path 15a returns to the chiller unit via the outlet flow path 15c. By circulating a temperature control medium, for example, a refrigerant such as cooling water, in the 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 electrostatic chuck 13 is formed so that the upper surface of the central portion is higher than the upper surface of the peripheral portion. The upper surface of the central portion of the electrostatic chuck 13 is the wafer mounting surface on which the wafer W is mounted, and in one example, the upper surface of the peripheral edge portion of the electrostatic chuck 13 is the edge ring mounting on which the edge ring 14 is mounted. It becomes a face.

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. Inside the electrostatic chuck 13, a second electrode 16b for sucking and holding the edge ring 14 is provided on the peripheral edge portion. 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 source (not shown) is applied to the first electrode 16a. Due to the electrostatic force generated by this, the wafer W is adsorbed 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 integrated. May be separate. 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.

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 facing 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 coupled 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 the 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 little 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 film formed by anodizing or a ceramic film such as 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 ejection port 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 configured 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 unit 52. The first high frequency power supply 50 and the second high frequency power supply 51 are coupled to the lower electrode 12 via the 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 source 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 coupled 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 coupled to the lower electrode 12, or may be coupled to the shower head 20 which is the upper electrode via the first matching circuit 53.

The second high-frequency power supply 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 a frequency 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 coupled 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 generation unit may be used instead of the second high frequency power supply 51. In this case, the pulse frequency may be a frequency in the range of 100 kHz to 2 MHz.

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. The circuit configuration of the switching unit 61 can be appropriately designed by those skilled in the art.

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 cuts off a high frequency of 40 MHz from, for example, the first high frequency power source 50. The second RF filter 63 reduces or cuts off a 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 positions 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 has 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). A program for controlling etching in the etching apparatus 1 is stored in the program storage unit. The program may be recorded on a storage medium readable by a computer 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 ion attraction 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 supply 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 recess formed by etching in the edge region of the wafer W with respect to the thickness direction of the wafer W. The tilt angle is substantially the same as the tilt of the ion incident on the edge region of the wafer W with respect to the vertical direction. In the following description, the direction inside (center side) with respect to the thickness direction of the wafer W is referred to as the inner side, and the direction outside with respect to the thickness direction of the wafer W is referred to as the outer side.

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

As shown in FIG. 3A, 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 to the surface (vertical direction). Therefore, the tilt angle is 0 (zero) degrees.

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, when the incident direction of the ions is tilted inward by an angle θ1 with respect to the vertical direction as shown in FIG. 3 (b), the phenomenon that the recess formed by etching is tilted by an angle θ1 toward the inner side is described. , Inner Tilt. The cause of the inner tilt is not limited to the wear of the edge ring 14 described above. For example, when the bias voltage generated in the edge ring 14 is lower than the voltage on the wafer W side, the inner tilt occurs in the initial state. Further, for example, the tilt angle may be corrected by intentionally adjusting the inner tilt in the initial state of the edge ring 14 and adjusting the DC power supply 60 described later.

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. Is also possible. 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. 4A, the arrow indicates the incident direction of the ion. In the following description, when the incident direction of the ions is tilted outward by an angle θ2 with respect to the vertical direction as shown in FIG. 4 (b), the recess formed by etching is tilted toward the outer side by an angle θ2. The phenomenon is called 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 to control the incident angle of the ions.

[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, the 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 estimate 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 around the edge ring 14 or the edge ring 14 can be any one of a voltage, a current value, a 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 estimate the consumption amount of the edge ring 14, the measurement conditions for estimating 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 setting of the pressure of the above 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, recesses 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 correction angle (hereinafter referred to as “tilt correction angle”). The vertical axis of FIG. 5 shows the tilt correction 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 correction angle becomes large. Further, the tilt correction angle is also 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 correction angle can be offset to the side where the tilt correction angle becomes large.

As shown in FIG. 3, for example, when the edge ring 14 is consumed, the incident angle of the ions is tilted inward with respect to the vertical direction, resulting in an 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 correction angle becomes large, the tilt angle inclined toward the inner side is changed to the outer side, and the tilt angle is set to 0. It can be corrected to (zero) degrees. 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, there is a limit to the DC voltage that can be applied to the edge ring 14, and even if an attempt is made to control the tilt angle only by adjusting the DC voltage, the control range 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 correction angle to the side where the tilt correction 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 (return to 0). 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 a flat or downward convex shape, and the tilt angle becomes 0 (zero) degrees or an inner tilt. In such a case, when the DC voltage from the DC power supply 60 is adjusted to change the tilt angle to the outer side as described later, the adjustment range of the DC voltage can be increased.

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 wear 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). Estimated based on changes in the voltage and current values of arbitrary points around the ring 14 or changes 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 processed wafers W. 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 correction angle becomes large, and by changing the tilt angle to the outer side, the tilt angle tilted to the inner side is corrected and the tilt angle is set to 0 (zero) degrees. Can be done. As a result, the incident angle of the ions can be adjusted to a desired value in the edge region of the wafer W and above the edge ring 14, and the tilt angle 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, for example, the upper limit value, the impedance of the second RF filter 63 is adjusted to increase the correlation between the DC voltage and the tilt correction angle. Offset to the side that becomes. When the tilt correction 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 0 (zero) degrees. The timing for adjusting the impedance may be when the consumption amount of the edge ring 14 reaches a predetermined value. The consumption of the edge ring 14 is estimated based on the processing time of the wafer W and the thickness measured by the measuring instrument.

At this time, the tilt angle is corrected by adjusting the DC voltage. Further, adjusting the impedance offsets the correlation between the DC voltage and the tilt correction angle described above. That is, the absolute value of the DC voltage is reduced while maintaining the tilt correction angle. Then, as shown in FIG. 5, the tilt correction angle can be adjusted to the target angle θ3, and the tilt angle can be set to 0 (zero) degrees. As shown in FIG. 6, the adjustment of the DC voltage from the DC power supply 60 and the adjustment of the impedance of the second RF filter 63 may be repeated.

As described above, according to the present embodiment, the tilt angle adjustment range can be increased by 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 the tilt angle is controlled 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, and the replacement frequency can be suppressed.

<Other embodiments>
In the above embodiment, the impedance of the second RF filter 63 is adjusted to offset the correlation between the DC voltage and the tilt correction angle, but the tilt angle may be corrected by adjusting the impedance.

As shown in FIG. 7, first, the DC voltage from the DC power supply 60 is adjusted to correct the tilt angle. Next, when the absolute value of the DC voltage reaches a predetermined value, for example, an upper limit value, the impedance of the second RF filter 63 is adjusted and adjusted to the tilt correction angle target angle θ3, and the tilt angle is set to 0 ( Set to zero) degree. In such a case, the number of times of DC voltage adjustment and impedance adjustment can be reduced, and the operation of tilt angle control can be simplified.

Here, the resolution of the tilt angle correction by adjusting the DC voltage and the resolution of the tilt angle correction by adjusting the impedance depend on the performance of the DC power supply 60 and the second RF filter 63, respectively. The resolution of tilt angle correction is the amount of tilt angle correction in one adjustment of DC voltage or impedance. Then, for example, when the resolution of the second RF filter 63 is higher than the resolution of the DC power supply 60, in the present embodiment, the impedance of the second RF filter 63 is adjusted to correct the tilt angle, so that the tilt as a whole is tilted. The resolution of angle correction can be improved.

As described above, according to the present embodiment, it is possible to improve the resolution of the tilt angle correction while simplifying the operation of the tilt angle control. Then, it is possible to increase the variation of the operation of the tilt angle control.

In the example shown in FIG. 7, the DC voltage adjustment and the impedance adjustment were performed once each to adjust the tilt correction angle to the target angle θ3, but the number of times of these DC voltage adjustments and impedance adjustments was Not limited to this. For example, as shown in FIG. 8, the DC voltage adjustment and the impedance adjustment may be performed a plurality of times. Even in such a case, 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 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.

As shown in FIG. 9, first, the impedance of the second RF filter 63 is adjusted to correct the tilt angle. Next, when the impedance reaches a predetermined value, for example, an upper limit value, the DC voltage from the DC power supply 60 is adjusted, the tilt correction angle is adjusted to the target angle θ3, and the tilt angle is set to 0 (zero) degrees. do.

Also in this embodiment, the same effects as those in the above embodiment can be enjoyed. That is, it is possible to improve the resolution of tilt angle correction while simplifying the operation of tilt angle control. The number of impedance adjustments and DC voltage adjustments is not limited to this embodiment, and may be performed a plurality of times. Further, the impedance of the second RF filter 63 may be adjusted without applying the DC voltage from the DC power supply 60.

<Other embodiments>
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 with a high aspect ratio with respect to the wafer W during etching, high ion energy is required to realize the vertical shape of the pattern after etching. 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. 2, when the electrical connection between the edge ring 14 and the second RF filter 63 is non-contact or capacitive coupling, even if the impedance of the second RF filter 63 is adjusted, the tilt angle is appropriately 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 the connection portion. The edge ring 14 and the connection portion are in contact with each other, and a direct current is conducted through the connection portion. Hereinafter, an example of the structure of the connection portion (hereinafter, may be referred to as “contact structure”) will be described.

As shown in FIG. 10, 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 the 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 each of the conductor structure 201 and the lower surface of the edge ring 14. Further, the conductor member 202 is made of 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. 11A to 11F. 11A to 11F are examples in which an elastic body is used as the conductor member 202. In FIGS. 11A to 11F, the elastic force of the conductor member 202 adjusts the contact pressure acting between the edge ring 14 and the conductor structure 201.

As shown in FIG. 11A, a coil spring that is spirally wound and extends in the horizontal direction may be used for the conductor member 202. As shown in FIG. 11B, a leaf spring urged in the vertical direction may be used for the conductor member 202. As shown in FIG. 11C, a spring that extends in the vertical direction while being spirally wound may be used in the conductor member 202. Then, due to the weight of the edge ring 14, the conductor member 202 is in close 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. 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 member 202 shown in FIGS. 11A to 11C is used, the conductor member 202 is in close contact with each of 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 for each of the conductor structure 201 and the lower surface of the edge ring 14. Adhere with the contact pressure of.

As shown in FIG. 11D, 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 each of 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. 11E, 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 joining of the wires may be ohmic contact with the lower surface of the conductor structure 201 or the edge ring 14, and as an example, the wires are welded or crimped. As shown in FIG. 11F, 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. Ru. 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 adsorbing the edge ring 14 can be omitted.

As described above, regardless of which of the conductor members 202 shown in FIGS. 11A to 11F 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 the 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. 11A, the leaf spring shown in FIG. 11B, the spring shown in FIG. 11C, the pin shown in FIG. 11D, and the wire shown in FIG. 11E. Although the fixing screws shown in FIG. 11F are exemplified, these may be used in combination.

Next, the arrangement of the conductor member 202 in a plan view will be described. 12A to 12C each show an example of the planar arrangement of the conductor member 202. As shown in FIGS. 12A and 12B, 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. 12A, the conductor member 202 is provided at eight places, and in FIG. 12B, the conductor member 202 is provided at 24 places. Further, as shown in FIG. 12C, the conductor member 202 may be provided in an annular shape on a concentric circle with the edge ring 14.

From the viewpoint of making the shape of the sheath uniform by performing etching uniformly (from the viewpoint of process uniformity), the conductor member 202 is provided in an annular shape with respect to the edge ring 14 as shown in FIG. 12C, 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. 12A and 12B, 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. 12B as compared with the example of FIG. 12A so that the conductor members 202 are closer to an annular shape as shown in FIG. 12C. 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 to 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 on the device configuration, and the like.

The contact structure for the edge ring 14 is not limited to the examples shown in FIGS. 10 and 11A to 11F. 13A to 13G show other examples of the configuration of the connection unit 200.

As shown in FIG. 13A, 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 and directly connected via the connecting portion 200 (conductor structure 201).

As shown in FIG. 13B, 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 contacts each of the conductor structure 201 and the edge ring 14. Further, the clamp member 210 is made of a conductor such as metal.

The clamp member 210 has a substantially U-shape with the inside 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 in 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. 13C, 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. 11A was used for the conductor member 220, but the leaf spring shown in FIG. 11B, the spring shown in FIG. 11C, the pin shown in FIG. 11D, and the wire shown in FIG. 11E. , The fixing screw shown in FIG. 11F 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. 13D, 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. 11A was used for the conductor member 230, but the leaf spring shown in FIG. 11B, the spring shown in FIG. 11C, the pin shown in FIG. 11D, and the wire shown in FIG. 11E. , The fixing screw shown in FIG. 11F may be used. In either case, the conductor member 220 is in close contact with the inner surface of the conductor structure 201 and 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. 13B, the conductor member 220 shown in FIG. 13C, and the conductor member 230 shown in FIG. 13D is the same as the planar arrangement of the conductor member 202 shown in FIGS. 12A to 12C. It may be similar. That is, the clamp member 210, the conductor member 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. 13E and 13F, 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. 13E contacts the conductor member 202 and the lower surface of the edge ring 14, respectively. The conductor 240 shown in FIG. 13F 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. 13G, 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, the coil spring shown in FIG. 11A was used for the conductor member 250, and the leaf spring shown in FIG. 11B was used for the conductor member 251. The conductor members 250 and 251 used the coil springs shown in FIG. 11B, respectively. The spring shown in FIG. 11C, the pin shown in FIG. 11D, the wire shown in FIG. 11E, the fixing screw shown in FIG. 11F, 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 planar arrangement of the conductor members 250 and 251 shown in FIG. 13G may be the same as the planar arrangement of the conductor members 202 shown in FIGS. 12A to 12C. That is, the conductor members 250 and 251 may be provided concentrically with the edge ring 14 at equal intervals, 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. 14A to 14C 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. 14A, for example, when one first RF filter 62 and one second RF filter 63 are provided for each of eight conductor members 202, the connecting portion 200 further has a relay member 270. You may be doing it. Although FIG. 14A shows the case where the relay member 270 is provided in the connection portion 200 shown in FIG. 12A, the relay member 270 can be provided in the connection portion 200 shown in either FIG. 12B or FIG. 12C. .. Further, a plurality of relay members 270 may be provided.

The relay member 270 is provided in an annular shape on a concentric circle 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. 14B, 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 addition, also in the example of FIG. 14B, the relay member 270 may be provided.

As shown in FIG. 14C, even if a plurality of first RF filters 62, for example, eight are provided 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. 14C, 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. 15 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 adsorbed and held with respect to the electrostatic chuck 13, and is in a state where etching is possible with respect to the wafer W (idling state). The temporary adsorption and the main adsorption may be performed continuously or intermittently.

[Temporary adsorption sequence]
FIG. 16 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. 16). Then, the lower surface of the edge ring 14 and the conductor member 202 come into contact with each other (step A2 in FIG. 16). 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. 16). 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. 16). 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. 17 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. 17). 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. 17). At this time, the inside of the chamber 10 is continuously evacuated by the exhaust device 42 (step B3 in FIG. 17). 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 the specified value (step B4 in FIG. 17). 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. 17). The process is terminated (step B6 in FIG. 17).

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. 17). 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. 17).

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. 17). Further, the lower surface of the edge ring 14 is evacuated by the exhaust unit 301 (step B10 in FIG. 17).

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. 17). That is, in step B11, a gas leak from the pipe 310 is confirmed. 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. 17). Step B5) ends the process (step B6 in FIG. 17).

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. 17). Then, it is maintained in a state where it can be etched (idling state) with respect to the wafer W. 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 adsorbed 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 for each of the conductor structure 201 and the lower surface of the edge ring 14. Adhere 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, even 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 DC voltage from the DC power supply 60 and the impedance of the second RF filter 63 are individually adjusted, but the DC voltage and the impedance may be adjusted at the same time.

<Other embodiments>
In the above embodiment, both the DC voltage from the DC power supply 60 and the impedance of the second RF filter 63 are adjusted, but the tilt angle may be controlled by adjusting only the DC voltage, or the impedance of the impedance. The tilt angle may be controlled by making only adjustments.

For example, as shown in FIG. 18, 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. The vertical axis of FIG. 19 shows the tilt correction angle, and the horizontal axis shows the impedance. In the example shown in FIG. 19, the impedance and the tilt correction angle have a linear relationship. Further, in the example shown in FIG. 19, the tilt correction angle is increased by increasing the impedance, but depending on the configuration of the second RF filter 63, the tilt correction angle is decreased by increasing the impedance. It is also possible. The relationship between the impedance and the tilt correction angle is not limited because it depends on the design of the second RF filter 63.

Further, even when the DC power supply 60 and the switching unit 61 are not connected to the edge ring 14 as in the present embodiment, the edge ring 14 and the second RF filter 63 are connected as in the above embodiment. It may be directly connected electrically via the unit. For example, as shown in FIG. 20, the edge ring 14 and the second RF filter 63 may be electrically directly connected via the connection portion 200. The configuration and arrangement of the connection unit 200 are the same as those shown in FIGS. 11A to 11F and 12A to 12C, for example. Alternatively, the contact structure with respect to the edge ring 14 is not limited to this example, and may be the example shown in FIGS. 13A to 13G. Further, the configurations of the connection unit 200, the first RF filter 62, and the second RF filter 63 are also shown in FIGS. 14A to 14C, except that they are not connected to the edge ring 14 from the DC power supply 60 and the switching unit 61. It may be an example.

Further, when the DC power supply 60 and the switching unit 61 are not connected to the edge ring 14 as in the present embodiment, the sequence when the edge ring 14 is electrostatically attracted to the electrostatic chuck 13 is the same as that of the above embodiment. The same is true. That is, in this sequence, the air supply unit 300 and the exhaust unit 301 provided in the etching apparatus 1 as shown in FIG. 20 are used. The configurations of the air supply unit 300 and the exhaust unit 301 are the same as those shown in FIG. Then, the temporary adsorption sequence shown in FIG. 16 and the main adsorption sequence shown in FIG. 17 are performed.

<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 the 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, since 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, the tilt angle is changed to the inner side. With, the tilt angle can be adjusted to 0 (zero) degrees.

<Other embodiments>
In the above embodiment, the DC voltage from the DC power supply 60 or the impedance of the second RF filter 63 is adjusted according to the consumption amount of the edge ring 14, but the DC voltage or the impedance adjustment timing is this. Not limited to. For example, the DC voltage or impedance 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 or impedance.

<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 and not restrictive in all respects. 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 60 DC power supply 62 First RF filter 63 Second RF filter 100 Control unit W wafer

Claims (17)

It is a device that etches the substrate.
With the chamber
A substrate support provided inside the chamber, the 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,
A DC power supply that applies a negative DC voltage to the edge ring,
RF filter that can change impedance and
A control unit that controls the DC voltage and the impedance to adjust the tilt angle in the edge region of the substrate mounted on the electrostatic chuck.
Equipped with an etching device. The control unit
(A) The step of adjusting the DC voltage and
(B) A step of adjusting the impedance after the absolute value of the DC voltage in the step (a) reaches a predetermined value.
The etching apparatus according to claim 1, wherein the apparatus is controlled so as to perform a process including. The etching apparatus according to claim 2, wherein the predetermined value in the step (b) is an upper limit value of the absolute value of the DC voltage. The control unit
In the step (a), the DC voltage is adjusted so as to correct the tilt angle.
The etching apparatus according to claim 2 or 3, wherein in the step (b), the impedance is adjusted so as to reduce the absolute value of the DC voltage while maintaining the tilt angle. The control unit
In the step (a), the DC voltage is adjusted so as to correct the tilt angle.
The etching apparatus according to claim 2 or 3, wherein the impedance is adjusted so as to correct the tilt angle in the step (b). The etching apparatus according to any one of claims 2 to 5, wherein the control unit adjusts the DC voltage according to the amount of wear of the edge ring in the step (a). The control unit
(C) The step of adjusting the impedance and
(D) A step of adjusting the DC voltage after the impedance in the step (c) reaches a predetermined value, and a step of adjusting the DC voltage.
The etching apparatus according to claim 1, wherein the apparatus is controlled so as to perform a process including. The etching apparatus according to claim 7, wherein the predetermined value in the step (d) is the upper limit value of the impedance. The control unit
In the step (c), the impedance is adjusted so as to correct the tilt angle.
The etching apparatus according to claim 7 or 8, wherein in the step (d), the DC voltage is adjusted so as to correct the tilt angle. The etching apparatus according to any one of claims 7 to 9, wherein the control unit adjusts the impedance according to the amount of wear of the edge ring in the step (c). The etching apparatus according to claim 6, wherein the control unit calculates the amount of wear of the edge ring based on the etching time of the substrate. Further equipped with a measuring instrument for measuring the thickness of the edge ring,
6. The control unit calculates, as the consumption amount of the edge ring, the difference between the initial thickness of the edge ring measured in advance and the thickness of the edge ring after etching using the measuring instrument. Or the etching apparatus according to 10. Further equipped with a measuring instrument for measuring the electrical characteristics of the edge ring or the periphery of the edge ring.
The etching apparatus according to claim 6 or 10, wherein the control unit calculates the consumption amount of the edge ring based on the change in the electrical characteristics by using the measuring instrument. The etching apparatus according to any one of claims 1 to 13, wherein the DC power supply is connected to the edge ring via the RF filter. The etching apparatus according to any one of claims 1 to 13, wherein the DC power supply is connected to the edge ring via the RF filter and the electrode. The etching apparatus according to any one of claims 1 to 15, further comprising one or more second RF filters having a variable impedance different from the RF filter. It is a method of etching a substrate using an etching device.
The etching device
With the chamber
A substrate support provided inside the chamber, the 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,
A DC power supply that applies a negative DC voltage to the edge ring,
RF filter that can change impedance and
Equipped with
In the method, an etching method in which the DC voltage and the impedance are controlled to adjust the tilt angle in the edge region of the substrate mounted on the electrostatic chuck.

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