Patent Application
20180144945
This application is based on and claims priority from Japanese Patent Application No. 2016-226024 filed on Nov. 21, 2016 with the Japan Patent Office, the disclosure of which is incorporated herein in its entirety by reference.
Various aspects and exemplary embodiments of the present disclosure relate to a placing unit and a plasma processing apparatus.
A plasma processing apparatus places a workpiece on a placing unit disposed in a processing container. The placing unit includes, for example, a base and an electrostatic chuck. The base is applied with a high-frequency power for plasma generation. The electrostatic chuck is formed of a dielectric and provided on the base, and has a placing region configured to place the processing target subject and an outer peripheral region configured to surround the placing region.
A heater used to control the temperature of the workpiece may be provided in the electrostatic chuck. For example, a structure has been known in which a heater is provided in the placing region of the electrostatic chuck and a wiring layer connected to the heater extends to the inside of the outer peripheral region so as to connect a contact portion of the wiring layer in the outer peripheral region with a power supply terminal for the heater. However, in the above-described structure, a portion of the high-frequency power applied to the base leaks from the power supply terminal for the heater to an external power source, and thus, high-frequency power is wasted.
In this regard, a technique has been known in which a filter is provided on a power supply line that connects a power supply terminal for a heater and an external power source so as to attenuate high-frequency power that is applied to a base and leaks from the power supply terminal for the heater to the power supply line. See, for example, Japanese Patent Laid-Open Publication Nos. 2013-175573, 2016-001688, and 2014-003179.
A placing unit of an aspect of the present disclosure includes: a base to which a high-frequency power is applied; an electrostatic chuck provided on the base and including a placing region configured to place a workpiece and an outer peripheral region configured to surround the placing region; a heater provided in the placing region; a wiring layer connected to the heater and extending to the inside of the outer peripheral region; a power supply terminal connected to a contact portion of the wiring layer in the outer peripheral region; and a conductive layer provided in the outer peripheral region or in other regions along the thickness direction of the outer peripheral region so as to overlap with the power supply terminal when viewed from the thickness direction of the outer peripheral region.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
In the following detailed description, reference is made to the accompanying drawings, which form a part thereof. The illustrative embodiments described in the detailed description, drawings, and claims are not meant to be limiting. Other embodiments may be utilized, and other changes may be made without departing from the spirit or scope of the subject matter presented here.
Since a filter is provided in correspondence to the number of heaters provided in an electrostatic chuck, when the number of the filters increases, a small filter with a low impulse value may be used as each filter from the viewpoint of avoiding the enlargement of a device. When such a small filter is applied to a placing unit, the high-frequency power leaking from a power supply terminal for a heater to a power supply line is not sufficiently attenuated and a potential locally decreases at a position corresponding to the power supply terminal for the heater in the circumferential position of a workpiece. As a result, the uniformity of an electric field strength along the circumferential direction of the workpiece may be impaired.
A placing unit according to a first aspect of the present disclosure includes: a base to which a high-frequency power is applied; an electrostatic chuck provided on the base and including a placing region configured to place a workpiece and an outer peripheral region configured to surround the placing region; a heater provided in the placing region; a wiring layer connected to the heater and extending to the inside of the outer peripheral region; a power supply terminal connected to a contact portion of the wiring layer in the outer peripheral region; and a conductive layer provided in the outer peripheral region or in other regions along the thickness direction of the outer peripheral region so as to overlap with the power supply terminal when viewed from the thickness direction of the outer peripheral region.
The above-described placing unit further includes a focus ring provided on the outer peripheral region, and the conductive region is provided in the focus ring along the thickness direction of the outer peripheral region or between the focus ring and the outer peripheral region so as to overlap with the power supply terminal when viewed from the thickness direction of the outer peripheral region.
In the above-described placing unit, the conductive layer is a conductive film that covers a surface facing the outer peripheral region of the focus ring.
In the above-described placing unit, the conductive layer is formed in a ring shape including a portion overlapping with the power supply terminal and a portion not overlapping with the power supply terminal when viewed from the thickness direction of the outer peripheral region.
In the above-described placing unit, the conductive layer is electrically insulated from other portions.
In the above-described placing unit, the conductive layer includes at least one of, for example, W, Ti, Al, Si, Ni, C, and Cu.
In the above-described placing unit, a plurality of the heaters are provided in the placing region, a plurality of the wiring layers are connected to the plurality of heaters, respectively, and extend to the inside of the outer peripheral region, the power supply terminal is provided for each of the wiring layers and is connected to a contact portion of the corresponding wiring layer in the outer peripheral region, and the conductive layer overlaps with a plurality of the power supply terminals when viewed from the thickness direction of the outer peripheral region.
The above-described placing unit further includes: a power supply line that connects the power supply terminal and an external power source; and a filter provided on the power supply line and configured to attenuate high-frequency power applied to the base and leaking from the power supply terminal to the power supply line.
In the above-described placing unit, a through hole through which a fixing member of the base penetrates is formed in the outer peripheral region, and the conductive layer is formed in other regions along the thickness direction of the outer peripheral region so as to overlap with the through hole in addition to the power supply terminal when viewed from the thickness direction of the outer peripheral region.
A placing unit according to a second aspect of the present disclosure includes: a base to which a high-frequency power is applied; an electrostatic chuck provided on the base and including a placing region configured to place a workpiece, an outer peripheral region configured to surround the placing region, and a through hole that penetrates the outer peripheral region; and a conductive layer formed in other regions along the thickness direction of the outer peripheral region so as to overlap with the through hole when viewed from the thickness direction of the outer peripheral region.
A plasma processing apparatus according to a third aspect of the present disclosure includes the above-described placing unit.
According to the above-described aspects, the placing unit of the present disclosure exhibits an effect of capable of improving the uniformity of the electric field strength along the circumferential direction of the workpiece.
Hereinafter, exemplary embodiments of the plasma processing apparatus disclosed herein will be described in detail with reference to the accompanying drawings. Meanwhile, in the respective drawings, the same or corresponding portions will be denoted by the same reference numerals.
A placing unit 16 is provided in the processing container 12. The placing unit 16 includes an electrostatic chuck 18, a focus ring FR, and a base 20. The base 20 has a substantially disc shape and its main portion is made of a conductive metal such as, for example, aluminum. The base 20 constitutes a lower electrode. The base 20 is supported by a support portion 14 and a support base 15. The support portion 14 is a cylindrical member that extends from the bottom portion of the processing container 12. The support base 15 is a cylindrical member that is disposed at the bottom portion of the processing container 12.
A first high-frequency power source HFS is electrically connected to the base 20 via a matching unit MU1. The first high-frequency power source HFS is a power source that generates high frequency power for generating plasma, and generates a high frequency power of 27 MHz to 100 MHz, for example, 40 MHz. The matching unit MU1 includes a circuit that matches an output impedance of the first high-frequency power source HFS with an input impedance of a load side (base 20 side).
Further, a second high-frequency power source LFS is electrically connected to the base 20 via a matching unit MU2. The second high-frequency power source LFS generates a high-frequency power (high-frequency bias power) for drawing ions into a wafer W to supply the high-frequency bias power to the base 20. The frequency of the high-frequency bias power is a frequency within a range of 400 kHz to 40 MHz, for example, 3 MHz. The matching unit MU2 includes a circuit that matches an output impedance of the second high-frequency power source LFS with an input impedance of the load side (base 20 side).
The electrostatic chuck 18 is provided on the base 20 and adsorbs the wafer W by an electrostatic force such as, for example, a coulomb force so as to hold the wafer W. The electrostatic chuck 18 has an electrostatic chucking electrode E1 in the main body made of dielectric material. A direct current power source 22 is electrically connected to the electrode E1 via a switch SW1. Further, a plurality of heaters HT are provided inside the electrostatic chuck 18. A heater power source HP is electrically connected to each heater HT. Each heater HT generates heat based on the power supplied individually from the heater power source HP to heat the electrostatic chuck 18. As a result, the temperature of the wafer W held by the electrostatic chuck 18 is controlled.
The focus ring FR is provided on the electrostatic chuck 18. The focus ring FR is provided to improve the uniformity of the plasma processing. The focus ring FR is made of dielectric and may be made of, for example, quartz.
A coolant flow path 24 is formed inside the base 20. The coolant flow path 24 is supplied with a coolant from a chiller unit provided outside the processing container 12 through a pipe 26a. The coolant supplied to the coolant flow path 24 is configured to be returned to the chiller unit through a pipe 26b. Further, the details of the placing unit 16 including the base 20 and the electrostatic chuck 18 will be described later.
An upper electrode 30 is provided in the processing container 12. The upper electrode 30 is disposed opposite to the base 20 above the placing unit 16, and the base 20 and the upper electrode 30 are provided substantially parallel to each other. A processing space S is defined between the base 20 and the upper electrode 30.
The upper electrode 30 is supported in the upper portion of the processing container 12 through an insulating shielding member 32. The upper electrode 30 may include an electrode plate 34 and an electrode support 36. The electrode plate 34 faces the processing space S and provides a plurality of gas ejection holes 34a. The electrode plate 34 may be made of a low-resistance conductor or semiconductor with little Joule heat.
The electrode support 36 detachably supports the electrode plate 34, and may be made of a conductive material such as, for example, aluminum. The electrode support 36 may have a water-cooled structure. A gas diffusion chamber 36a is provided in the electrode support 36. From the gas diffusion chamber 36a, a plurality of gas flowing holes 36b extend downward to be in communication with the gas ejection holes 34a. Further, a gas introduction port 36c is formed in the electrode support 36 to introduce the processing gas to the gas diffusion chamber 36a. The gas introduction port 36c is connected with a gas supply pipe 38.
The gas supply pipe 38 is connected with a gas source group 40 via a valve group 42 and a flow rate controller group 44. The valve group 42 includes a plurality of opening/closing valves, and the flow rate controller group 44 includes a plurality of flow rate controllers such as, for example, mass flow controllers. Further, the gas source group 40 includes a plurality of types of gas sources required for the plasma processing. The plurality of gas sources of the gas source group 40 are connected to the gas supply pipe 38 via the corresponding opening/closing valves and the corresponding mass flow controllers.
In the plasma processing apparatus 10, one or more gases from one or more gas sources selected from a plurality of gas sources of the gas source group 40 are supplied to the gas supply pipe 38. The gas supplied to the gas supply pipe 38 reaches the gas diffusion chamber 36a and is discharged to the processing space S through the gas flowing holes 36b and the gas discharge holes 34a.
Further, as illustrated in
Further, in the plasma processing apparatus 10, a deposit shield 46 is detachably provided along the inner wall of the processing container 12. The deposit shield 46 is also provided in the outer periphery of the support portion 14. The deposit shield 46 serves to suppress an etching byproduct (deposit) from being attached to the processing container 12, and may be formed by coating a ceramic (e.g., Y2O3) on an aluminum material.
An exhaust plate 48 is provided between the support portion 14 and the inner wall of the processing container 12 at the bottom portion side of the processing container 12. The exhaust plate 48 may be formed by coating a ceramic (e.g., Y2O3) on an aluminum material. An exhaust port 12e is provided at the lower side of the exhaust plate 48 in the processing container 12. The exhaust port 12e is connected with an exhaust device 50 via an exhaust pipe 52. The exhaust device 50 includes a vacuum pump such as, for example, a turbo molecular pump, and is capable of decompressing the space in the processing container 12 to a desired degree of vacuum. A carry-in/out port 12g of the wafer W is provided in the sidewall of the processing container 12. The carry-in/out port 12g is able to be opened/closed by a gate valve 54.
Further, the plasma processing apparatus 10 may further include a controller Cnt. The controller Cnt is a computer including, for example, a processor, a storage unit, an input device, and a display device, and controls respective portions of the plasma processing apparatus 10. In the controller Cnt, an operator may execute an input operation of a command using the input device to manage the plasma processing apparatus 10, and may visualize and display the operation status of the plasma processing apparatus 10 by the display device. Further, the storage unit of the controller Cnt stores a control program for controlling various processings to be performed in the plasma processing apparatus 10 by the processor, or a program for performing a processing on respective portions of the plasma processing apparatus 10 in accordance with a processing condition, that is, a processing recipe.
Next, the placing unit 16 will be described in detail.
As illustrated in illustrated in
Further, a through hole 18b-1 penetrating the outer peripheral region 18b in the thickness direction is formed in the outer peripheral region 18b, and a fastening member 21 for fixing the base 20 to the support base 15 is inserted through the through hole 18b-1. In the exemplary embodiment, since the base 20 is fixed to the support base 15 by a plurality of fastening members 21, a plurality of through holes 18b-1 are formed in the outer peripheral region 18b in accordance with the number of the fastening members 21.
The electrostatic chuck 18 has an electrostatic chucking electrode E1 in the placing region 18a. As described above, the electrode E1 is connected to the direct current power source 22 via the switch SW1.
Further, a plurality of heaters HT are provided in the placing region 18a. For example, as illustrated in
As illustrated in
The contact portion CT is connected to a power supply terminal ET that supplies power generated by the heater power source HP. In the exemplary embodiment, as illustrated in
In addition, as illustrated in
The operation of the conductive layer 62 will be described using an equivalent circuit of the plasma processing apparatus 10.
As illustrated in
When the conductive layer 62 is formed in the outer peripheral region 18b, the potential of the portion overlapping with the power supply terminal ET and the potential of the portion not overlapping with the power supply terminal ET become equal to each other in the conductive layer 62. Therefore, when the conductive layer 62 is formed in the outer peripheral region 18b, as illustrated in
Further, in
In the meantime, in
As illustrated in graphs 501 and 502 of
As illustrated in graphs 601 and 602 of
Next, a manner in which the conductive layer 62 according to the exemplary embodiment is installed will be described. In the exemplary embodiment, the conductive layer 62 is provided in the outer peripheral region 18b, but the conductive layer 62 may be provided in other regions along the thickness direction of the outer peripheral region 18b. That is, the conductive region 62 is formed in other regions along the thickness direction of the outer peripheral region 18b so as to overlap with the power supply terminal ET when viewed from the thickness direction of the outer peripheral region 18b.
For example, as illustrated in
As another example, as illustrated in
In addition, the conductive region 62 may be provided in other regions along the thickness direction of the outer peripheral region 18b so as to overlap with the through hole 18b-1 of the outer peripheral region 18b in addition to the power supply terminal ET when viewed from the thickness direction of the outer peripheral region 18b. For example, as illustrated in
Here, the operation of the conductive layer 62 illustrated in
As described above, when the conductive layer 62 is provided in the focus ring FR, the potential of the portion overlapping with the power supply terminal ET, the potential of the portion not overlapping with the power supply terminal ET, the potential of the portion overlapping with the through hole 18b-1, and the potential of the portion not overlapping with the through hole 18b-1 become equal to each other. Therefore, when the conductive layer 62 is provided in the focus ring FR, as illustrated in
Next, an effect by the plasma processing apparatus 10 (a measurement result of an etching rate) according to the exemplary embodiment will be described.
Graph 701 represents the measurement result obtained by measuring the distribution of the etching rate along the circumferential direction of the wafer W having a size of 300 mm using the plasma processing apparatus 10 in which the conductive layer 62 is not present (Comparative Example). Graph 702 represents the measurement result obtained by measuring the distribution of the etching rate along the circumferential direction of the wafer W having a size of 300 mm using the plasma processing apparatus 10 in which the conductive layer 62 is provided in the outer peripheral region 18b (Example 1). Graph 703 represents the measurement result obtained by measuring the distribution of the etching rate along the circumferential direction of the wafer W having a size of 300 mm using the plasma processing apparatus 10 in which the conductive layer 62 is provided in the focus ring FR (Example 2). In graphs 701 to 703, the horizontal axis indicates the circumferential angle [degree (°)] of the wafer W with respect to a predetermined position of the edge portion of the wafer W, and the vertical axis indicates the etching rate [nm/min] at a position of 3 mm from the end portion of the wafer W along the radial direction of the wafer W. Further, in each graph, the etching rate in the region corresponding to the power supply terminal ET is indicated by a white circle, and the etching rate in the region not corresponding to the power supply terminal ET is indicated by a black circle.
As illustrated in
In Example 1, the above-mentioned “amplitude” was 0.060 nm/min, and in Example 2, the above-mentioned “amplitude” was 0.068 nm/min. That is, in Examples 1 and 2, the variation in the etching rate along the circumferential direction of the wafer W was suppressed when compared with the Comparative Example. This is probably because when the conductive layer 62 was provided in the outer peripheral region 18b or the focus ring FR, the uniformity of the electric field strength along the circumferential direction of the wafer W was improved, whereby the unevenness of the etching rate along the circumferential direction of the wafer W was improved locally.
According to the exemplary embodiment described above, the conductive layer 62 superimposed on the power supply terminal ET when viewed from the thickness direction of the outer peripheral region 18b is formed in the outer peripheral region 18b of the electrostatic chuck 18 or in other regions along the thickness direction of the outer peripheral region 18b. Therefore, according to the exemplary embodiment, a local decrease in the potential at the position corresponding to the power supply terminal ET in the circumferential position of the wafer W may be avoided, and the uniformity of the electric field strength along the circumferential direction of the wafer W may be improved. As a result, the unevenness of the etching rate along the circumferential direction of the wafer W may be improved.
In addition, in the exemplary embodiment, a case where the conductive layer 62 overlaps with the power supply terminal ET when viewed from the thickness direction of the outer peripheral region 18b has been described. However, the conductive layer 62 may be provided to overlap with a portion of the wiring layer EW in addition to the power supply terminal ET when viewed from the thickness direction of the outer peripheral region 18b. In this case, the ratio of the overlapping portion between the wiring layer EW and the conductive layer 62 to the portion corresponding to the outer peripheral region 18b of the wiring layer EW may be 76% or more.
Further, in the exemplary embodiment, the first high-frequency power source HFS, which is a power supply that generates high-frequency power for generating plasma, is electrically connected to the base 20 via the matching unit MU1, but the first high-frequency power source HFS may be connected to the upper electrode 30 via the matching unit MU1.
The plasma processing apparatus 10 in the exemplary embodiment is a capacitively coupled parallel plate plasma (CCP) etching apparatus. Examples of the plasma source may include an inductively coupled plasma (ICP), a microwave plasma, a surface wave plasma (SWP), a radial line slot antenna (RLSA) plasma, and an electron cyclotron resonance (ECT) plasma.
From the foregoing, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended to be limiting, with the true scope and spirit being indicated by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-226024 | Nov 2016 | JP | national |
