US20120247954A1

US20120247954A1 - Plasma processing apparatus

Info

Publication number: US20120247954A1
Application number: US13/432,623
Authority: US
Inventors: Jun Yamawaku; Chishio Koshimizu
Original assignee: Tokyo Electron Ltd
Current assignee: Tokyo Electron Ltd
Priority date: 2011-03-29
Filing date: 2012-03-28
Publication date: 2012-10-04
Also published as: JP2012209359A; CN102737940A; JP5741124B2; CN102737940B; TWI566296B; KR101910670B1; TW201301383A; KR20120112147A

Abstract

Disclosed is a capacitively-coupled plasma etching apparatus, in which a focus ring is provided surrounding a substrate placing area of a placing table for adjusting a state of plasma. A ring type insulating member is installed along the focus ring between the top surface of the placing table and the bottom surface of the focus ring, and a heat transfer member is installed between the top surface of the placing table and the bottom surface of the focus ring to be closely attached to the top surface and the bottom surface at a position adjacent to the insulating member in a diameter direction of a wafer. During the plasma processing, the heat in the focus ring is transferred to the placing table through the heat transfer member to be cooled down and the amount of sediment attached to the rear surface of the wafer can be reduced.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese Patent Application No. 2011-072677, filed on Mar. 29, 2011, with the Japanese Patent Office, the disclosure of which is incorporated herein in its entirety by reference. Also, this application claims the benefit of U.S. Provisional Application No. 61/477,636 filed on Apr. 21, 2011, with the United States Patent and Trademark Office, the disclosure of which is incorporated herein in its entirety by reference.

TECHNICAL FIELD

The present disclosure relates to a technology that performs a plasma processing on a substrate such as a semiconductor wafer or a glass substrate for a flat panel display (FPD).

BACKGROUND

In a manufacturing process of a semiconductor substrate such as a semiconductor wafer or a glass substrate for an FPD, a predetermined plasma processing such as an etching process or a film forming process is performed with respect to a substrate. In a plasma processing apparatus that performs the process, a substrate is placed on a placing table in a vacuum chamber and processing gas becomes a plasma in an upper space of the placing table, such that the plasma processing is performed with respect to the substrate. As shown in FIG. 15A, an annular focus ring 12 made of a conductive member such as, for example, silicon is installed around a substrate, for example, a semiconductor wafer W (‘wafer W’) placed on a placing table 11 in order to perform a uniform processing by keeping plasma on wafer W and alleviating discontinuity of a bias potential in the plane of wafer W.
A temperature control fluid path (not shown) is installed in placing table 11, and plasma processing is performed in a state where wafer W is adjusted to a predetermined temperature by a balance of heat absorption from plasma and heat dissipation to placing table 11. Meanwhile, since focus ring 12 is exposed to plasma while focus ring 12 is thermally excited, focus ring 12 has a higher temperature than wafer W. In the mean time, since radical species or a reaction by-product is attached to a low-temperature portion to form a polymer (sediment) and wafer W has a lower temperature than focus ring 12 as described above, a polymer 13 is easily formed at an edge portion of wafer W. While polymer 13 formed at the edge portion of wafer W is removed by a plasma ion sputtering, polymer 13 formed at the rear surface of wafer W may not be removed by the same sputtering process because the plasma is not irradiated at the rear surface of wafer W.
As a technique of removing the polymer, Japanese Patent Application Laid-Open No. 2005-277369 and Japanese Patent Application Laid-Open No. 2007-250967 propose a configuration in which a potential difference between wafer W and a focus ring is controlled by inserting an insulating material below the focus ring. In this configuration, as shown in FIG. 15B, the potential difference between wafer W and focus ring 12 is adjusted by insulating material 14, the plasma ions are guided to the rear surface of wafer W by changing trajectories of the incident plasma ions, thereby removing polymer 13 by sputtering.
According to this configuration, although the polymer attached to the rear surface of wafer W can be removed, attachment of the polymer to the periphery of the rear surface of wafer W itself is not suppressed since the temperature of focus ring 12 cannot be controlled. Also, there is a possibility that polymer attached to wafer W may not be completely removed depending on conditions. In this case, the polymer is peeled off by, for example, a batch cleaning as a post process, but the polymer may be attached to the surface of a device through a cleaning liquid, which may cause a defect. While wafer W of a single lot is processed, the temperature of focus ring 12 is increased with plasma being irradiated and the trajectories of the plasma ions that detours into the rear surface of wafer W are changed by the change in temperature, such that the polymer may not be stably removed.
Japanese Patent Application Laid-Open No. 2007-258500 proposes a technology in which attachment of the sediment to a bevel portion of wafer W is suppressed by laminating a first heat transfer medium, a dielectric ring, a second heat transfer medium and an insulating member vertically between the focus ring and an electrode block. In this configuration, voltage applied to a sheath formed on a front surface of the focus ring is suppressed by the dielectric ring to suppress heat absorption to the focus ring and heat is transferred to the electrode block from the focus ring using the first and second heat transfer media. Therefore, the temperature of the focus ring is made to be lower than that of wafer W to suppress the attachment of the sediment to the bevel portion of wafer W.
Herein, when an insulator and a thermal conductor are formed in a laminated structure, air bubbles are easily mixed into a contact surface between the thermal conductor and the insulator. However, a contact state between the insulator and the focus ring is changed by the presence of the air bubbles, such that it is difficult to uniformly transfer heat in the plane of the focus ring. Since the removal of the polymer attached to the rear surface of the wafer by sputtering is implemented by the potential difference between the edge portion of wafer W and the focus ring, subtle impedance control by the insulator installed under the focus ring is required. However, the contact state between the insulator and focus ring is changed by the presence of the air bubbles between the insulator and the focus ring, such that a bad influence may be exerted on the impedance control as well. Moreover, when the insulator and the thermal conductor are formed in the laminated structure, the thermal conductor may be deformed or the air bubbles may be mixed into a portion between the thermal conductor and the insulator, such that the periphery of the focus ring is easily inclined downward and the control of height of the focus ring becomes difficult. As a result, the control of a plasma state of the periphery of wafer W becomes unstable.

SUMMARY

An exemplary embodiment of the present disclosure provides a plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus including: a vacuum chamber including a lower electrode and an upper electrode configured to generate the plasma by introducing a processing gas and applying a high-frequency power between the lower electrode and an upper electrode, thereby processing the substrate using the plasma; a placing table provided in the vacuum chamber serving as the lower electrode and configured to receive a substrate on a substrate placing area; a ring member installed on the placing table surrounding the substrate placing area and configured to adjust a state of the plasma generated between the lower electrode and the upper electrode; an insulating member installed along the ring member between a top surface of the placing table and a bottom surface of the ring member in a concentric pattern with a center of the substrate on the placing table and configured to adjust a potential difference between the ring member and the substrate thereby injecting ions of plasma into a rear surface of the substrate; and a heat transfer member closely attached to each of the top surface of the placing tale and the bottom surface of the ring member along the ring member between the top surface of the placing table and the bottom surface of the ring member at a position adjacent to the insulating member in a diameter direction of the substrate.
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.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal side view illustrating a plasma etching apparatus according to a first exemplary embodiment of the present disclosure.

FIG. 2 is a longitudinal cross-sectional view illustrating a part of a placing table installed in the plasma etching apparatus.

FIG. 3 is a plan view and a longitudinal cross-sectional view of the placing table.

FIG. 4 is a longitudinal cross-sectional view for illustrating an operation of the present disclosure.

FIG. 5 is a longitudinal cross-sectional view illustrating another example of the first exemplary embodiment of the present disclosure.

FIG. 6 is a longitudinal cross-sectional view illustrating a plasma etching apparatus according to a second exemplary embodiment of the present disclosure.

FIG. 7 is a plan view illustrating a placing table installed in the plasma etching apparatus of FIG. 6.

FIG. 8 is a plan view illustrating another example of the placing table of the second exemplary embodiment of the present disclosure.

FIG. 9 is a plan view illustrating yet another example of the placing table of the second exemplary embodiment of the present disclosure.

FIGS. 10A, 10B and 10C each illustrates yet another example of the placing table of the second exemplary embodiment of the present disclosure in a plan view and a longitudinal cross-sectional view.

FIGS. 11A and 11B each illustrates a plasma etching apparatus according to a third exemplary embodiment of the present disclosure in a plan view and a partial perspective view.

FIGS. 12A and 12B each illustrates another example of the placing table of the plasma etching apparatus of the present disclosure in a longitudinal cross-sectional view.

FIG. 13 is a longitudinal cross-sectional view illustrating yet another example of the placing table of the plasma etching apparatus of the present disclosure.

FIG. 14 is a feature diagram illustrating an exemplary embodiment performed to verify an effect of the present disclosure.

FIGS. 15A and 15B each illustrates a placing table in the related art in a longitudinal cross-sectional view.

DETAILED DESCRIPTION

In the following detailed description, reference is made to the accompanying drawing, which form a part hereof. The illustrative embodiments described in the detailed description, drawing, 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.
The present disclosure has been made in an effort to provide a technology that can suppress the amount of sediment attached to a rear surface of a substrate by controlling the temperature of a ring member.
An exemplary embodiment of the present disclosure provides a plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus including: a vacuum chamber including a lower electrode and an upper electrode configured to generate the plasma by introducing a processing gas and applying a high-frequency power between the lower electrode and an upper electrode, thereby processing the substrate using the plasma; a placing table provided in the vacuum chamber serving as the lower electrode and configured to receive a substrate on a substrate placing area; a ring member installed on the placing table surrounding the substrate placing area and configured to adjust a state of the plasma generated between the lower electrode and the upper electrode; an insulating member installed along the ring member between a top surface of the placing table and a bottom surface of the ring member in a concentric pattern with a center of the substrate on the placing table and configured to adjust a potential difference between the ring member and the substrate thereby injecting ions of the plasma into a rear surface of the substrate; and a heat transfer member closely attached to each of the top surface of the placing table and the bottom surface of the ring member along the ring member between the top surface of the placing table and the bottom surface of the ring member at a position adjacent to the insulating member in a diameter direction of the substrate.
In the plasma processing apparatus, the top surface of the insulating member contacts the ring member.
The insulating member is installed at both sides of the inside and the outside of the diameter direction of the substrate with respect to the heat transfer member.
A yet another exemplary embodiment of the present disclosure provides a plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus including: a vacuum chamber including a lower electrode and an upper electrode configured to generate the plasma by introducing a processing gas and applying a high-frequency power between the electrodes, thereby processing the substrate using the plasma; a placing table provided in the vacuum chamber serving as the lower electrode and configured to receive a substrate on a substrate placing area; a ring member installed on the placing table surrounding the substrate placing area and configured to adjust a state of plasma generated between the lower electrode and the upper electrode; an insulating member installed along the ring member between a top surface of the placing table and a bottom surface of the ring member in a concentric pattern with a center of the substrate on the placing table and configured to adjust a potential difference between the ring member and the substrate thereby injecting ions of the plasma into a rear surface of the substrate; a plurality of lower heat transfer members closely attached to each of the insulating member and the placing table between a top surface of the insulating member and a top surface of the placing table in a concentric pattern with a center of the substrate on the placing table along the ring member and spaced apart from one another in a diameter direction of the ring member; and a plurality of upper heat transfer members closely attached to each of the insulating member and the ring member between a bottom surface of the insulating member and a bottom surface of the ring member in the concentric pattern with the center of the substrate on the placing table along the ring member and spaced apart from one another in the diameter direction of the ring member.
In the plasma processing apparatus, at least one side of the upper heat transfer member and the lower heat transfer member is notched so that a space between the heat transfer members adjacent to each other in the diameter direction of the ring member is allowed to communicate with atmosphere within the vacuum chamber.
Another exemplary embodiment of the present disclosure provides a plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus comprising: a vacuum chamber including a lower electrode and an upper electrode configured to generate the plasma by introducing a processing gas and applying a high-frequency power between the lower electrode and an upper electrode, thereby processing the substrate using the plasma; a placing table provided in the vacuum chamber serving as the lower electrode and configured to receive a substrate on a substrate placing area; a ring member installed on the placing table surrounding the substrate placing area and configured to adjust a state of plasma generated between the lower electrode and the upper electrode; an insulating member installed along the ring member between a top surface of the placing table and a bottom surface of the ring member in a concentric pattern with a center of the substrate on the placing table and configured to adjust a potential difference between the ring member and the substrate thereby injecting ions of the plasma into a rear surface of the substrate; and a heat transfer member closely attached to each of the sides of the ring member, the insulating member, and the placing table between those sides along the ring member.
According to exemplary embodiments of the present disclosure, since a heat transfer member and insulating member are installed between a ring member and a placing table, an increase in temperature of the ring member at the time of irradiating plasma can be suppressed and attachment of sediment to a substrate can be suppressed. Even though the sediment are attached to the substrate, confusion of trajectories of plasma ions that detour into a rear surface of the substrate due to a change in temperature of the ring member is suppressed, and as a result, the sediment attached to the rear surface of the substrate can be stably removed by sputtering and the amount of the attached sediment can be reduced.
Hereinafter, a capacitively-coupled plasma etching apparatus according to an exemplary embodiment of the present disclosure will be described. FIG. 1 is a longitudinal cross-sectional view illustrating a plasma etching apparatus 2 which includes an airtight processing chamber (vacuum chamber) 20 made of, for example, aluminum for performing a plasma processing for wafer W placed therein. A placing table 3 is installed at the center of the bottom of processing chamber 20 and configured such that the periphery of the top of a cylinder is notched across the entirety of a circumference thereof and a step portion 31 is formed in a shape in which a part other than the periphery protrudes cylindrically on the top. The protruding portion forms a substrate placing area 32 (hereinafter, referred to as a ‘placing area’) where wafer W serving as a substrate is placed, and step portion 31 surrounding placing area 32 corresponds to a placing area of a ring member to be described below.
An electrostatic chuck 33 formed by placing a chuck electrode 33 a on an insulating layer is installed on the top of placing area 32 and wafer W is placed on electrostatic chuck 33 with the periphery thereof being protruded. Chuck electrode 33 a is electrically connected with a DC power supply 34 installed outside processing chamber 20 through a switch 35. A plurality of discharge openings (not shown) are formed in electrostatic chuck 33, and heat medium gas, for example, He gas is supplied to a minute space between corresponding electrostatic chuck 33 and wafer W from a gas supplying unit (not shown). An elevation pin (not shown) is installed in placing table 3 and configured to transfer wafer W between an external transportation arm (not shown) and electrostatic chuck 33.
A refrigerant circulation chamber 36 is installed in placing table 3 and refrigerants are circulated and supplied from a refrigerant supplying unit 37 installed outside placing table 3. That is, the refrigerants supplied to refrigerant circulation chamber 36 from refrigerant supplying unit 37 through a supply path 36 a are discharged outside placing table 3 through a discharge path 36 b and cooled down to a predetermined temperature by a chiller in refrigerant supplying unit 37, and thereafter, supplied to refrigerant circulation chamber 36 through supply path 36 a again. Placing table 3 also serves as a lower electrode and is connected to a high-frequency power supply unit 38 through a matching device 39. High-frequency power supply unit 38 is a bias power supply for applying a bias to the lower electrode for injecting ions within plasma.
Meanwhile, a shower head 4 is installed on a ceiling of processing chamber 20 through insulating member 21 to face placing area 32 and connected to a gas supply system 41 through a supply path 42. Shower head 4 is configured such that a buffer chamber 43 is formed therein, a plurality of discharge openings 44 are formed on the bottom thereof, and processing gas supplied to buffer chamber 43 from gas supply system 41 is discharged toward placing area 32 side through discharge openings 44. Shower head 4 also serves as an upper electrode and is connected to a plasma generating high-frequency power supply unit 46 through a matching device 45.
An exhaust port 22 is installed on the bottom of processing chamber 20 and a vacuum pump 25 as a vacuum exhaust mechanism is connected to exhaust port 22 through an exhaust path 24 in which a valve V and a pressure adjusting unit 23 are installed. A transportation opening 27 of wafer W which is opened/closed by a shutter 26 is provided on the side of processing chamber 20.
A focusing ring 5, made of a conductive material such as, for example, silicon, is installed on a bottom surface (step surface) of step portion 31 formed on the periphery of the top surface of placing table 3 through insulating member 6 and heat transfer member 7 as shown in FIG. 2 and FIG. 3. Focus ring 5 is installed on placing table 3 to surround placing area 32 and constitutes a ring member for adjusting a state of plasma. The inner periphery of focus ring 5 is notched across the entirety of a circumference thereof to form a step portion 51 and the periphery that protrudes from placement area 32 of wafer W enters into step portion 51 of focus ring 5. The shapes of placing area 32 and focus ring 5 are set so that a small gap is formed between an outer peripheral surface 32 a of placing area 32 and an inner peripheral surface 52 of a lower side of step portion 51 of focus ring 5. Therefore, when wafer W is placed in placing area 32, focus ring 5 is installed to surround the side from the rear surface of the periphery of wafer W.
Insulating member 6 and heat transfer member 7 are installed to be lined up in a diameter direction of wafer W on placing table 3, between step portion 31 of placing table 3 and the bottom surface of focus ring 5. As shown in FIG. 2 and FIG. 3, insulating member 6 is installed in a concentric pattern with respect to the center of wafer W on placing table 3 along focus ring 5 between the top surface of placing table 3 and the bottom surface of focus ring 5, and serves to adjust a potential difference between focus ring 5 and wafer W to inject ions within plasma into the rear surface of wafer W. In this example, insulating member 6 is formed in a ring type and contacts the bottom surface of focus ring 5, and is installed to fill the gap between inner peripheral surface 52 of the lower side of step portion 51 of focus ring 51 and outer peripheral surface 32 a of placing area 32 of placing table 3. Insulating member 6 may be made of, for example, silicon dioxide (SiO₂) or ceramics, and aluminum nitride (AlN), sapphire as well as quartz.
Heat transfer member 7 is positioned adjacent to insulating member 6 in the diameter direction of wafer W on placing table 3, and installed along focus ring 5 between the top surface of placing table 3 and the bottom surface of focus ring 5 in close contact with the top and the bottom surfaces. In this example, heat transfer member 7 is installed outside the diameter direction of wafer W with respect to insulating member 6. Heat transfer member 7 is composed of a high-molecular silicon gel filled with alumina as a material which has high thermal conductivity in this example and may acquire a certain degree of thermal conductivity in which an effect of suppressing attachment of radical species or reaction by-product to wafer W becomes remarkable by cooling focus ring 5. Heat transfer member 7 may be composed of a material having a high thermal conductivity coefficient such as a silicon based resin, a carbon based resin, or a fluorine based resin as well as the high-molecular silicon gel.
In this example, the height of the top surface of insulating member 6 is configured to coincide with the height of the top of heat transfer member 7, and focus ring 5 is placed on insulating member 6 and heat transfer member 7, such that focus ring 5 is installed on step portion 31 of placing table 3 while the height is restrained by insulating member 6 which is made of quartz. In this case, since the high-molecular silicon gel filled with alumina formed by an elastic body having adhesiveness is used as heat transfer member 7, adherence between heat transfer member 7 and focus ring 5 as well as between heat transfer member 7 and step portion 31 of placing table 3 is ensured by the adhesiveness thereof. When focus ring 5 is installed on insulating member 6 and heat transfer member 7, the potential difference between wafer W and focus ring 5 is adjusted to a predetermined range, and a vertical size (height L1) or a horizontal size (widths L2 and L2) are respectively set so that focus ring 5 is not inclined horizontally (in the diameter direction of wafer W on placing table 3).
Plasma etching apparatus 2 is controlled by a control unit 100 constituted with, for example, a computer and has a program, a memory, and a CPU. The program includes commands (each step) used to perform a predetermined etching process by transmitting a control signal from control unit 10 to each unit of plasma etching apparatus 2. The program is stored in a storage unit serving as a computer storage medium such as, for example, a flexible disk, a compact disk, a hard disk, and a magneto-optic (MO) disk, and installed in control unit 100.
Herein, the program includes programs for controlling a switch 35 of electrostatic chuck 33, ON/OFF of high-frequency power supply units 38 and 46, supply start and supply stop of the processing gas by gas supplying system 41, and opening/closing of valve V of vacuum pump 25, and is configured to control each unit according to a process recipe prestored in the memory of control unit 100.
Continuously, an operation of plasma etching apparatus 2 will be described. First, shutter 26 is opened and wafer W is carried into processing chamber 20 from a vacuum transportation chamber (not shown) through transportation opening 27 using a transportation arm (not shown). Wafer W is then transferred onto electrostatic chuck 33 to be adsorbed and held by cooperation between an elevation pin (not shown) and the transportation arm. After shutter 26 is closed, a predetermined processing gas (e.g., an etching gas) is supplied from gas supply system 41 through shower head 4 while the inside of processing chamber 20 is vacuum-exhausted by vacuum pump 25.
Meanwhile, a high-frequency power for generating plasma is supplied to shower head 4 from high-frequency power supply unit 46 and bias high-frequency power is supplied to placing table 3 from high-frequency power supply unit 38 to generate plasma, and an etching process is performed for wafer W with the plasma.
Since wafer W on placing table 3 is exposed to plasma during plasma processing, wafer W absorbs heat from the plasma. However, since placing table 3 is cooled down by circulation of the refrigerants and maintained to a preset reference temperature as described above, heat of wafer W is dissipated to placing table 3 through He gas. Accordingly, wafer W is maintained to a predetermined temperature by a heat balance between the operations of heat absorption from plasma and heat dissipation to placing table 3.
Focus ring 5 is also exposed to plasma to absorb heat from plasma. However, since focus ring 5 is installed on placing table 3 through heat transfer member 7 having the high thermal conductivity, and further, the bottom surface of focus ring 5, the top surface of heat transfer member 7, the bottom surface of heat transfer member 7 and the top surface of placing table 3 are closely attached to each other by the adhesiveness of heat transfer member 7, respectively, heat of focus ring 5 is rapidly transferred to placing table 3 through heat transfer member 7 as shown in FIG. 4. Therefore, as apparent from the exemplary embodiment to be described below, focus ring 5 is cooled down by heat transfer member 7 and the temperature difference between wafer W and focus ring 5 on placing table 3 is removed during plasma processing. As a result, the radical species or reaction by-products are suppressed from selectively entering into the periphery of the rear surface of wafer W. As described above, since focus ring 5 is cooled down and the temperature difference between wafer W and focus ring 5 on placing table 3 is removed, the effect of impeding the attachment of the radical species or by-products to wafer W becomes remarkable during the plasma processing.
Since the potential of focus ring 5 is adjusted by insulating member 6 and the potential difference between focus ring 5 and wafer W is adjusted so that the potential of wafer W is lower than the potential of focus ring 5 (negatively increases), the ions within plasma are injected into wafer W. As a result, as shown in FIG. 4, even though the polymer is formed on the rear surface of wafer W by controlling the trajectories of the ions within plasma to detour into the rear surface of wafer W, the polymer is removed by sputtering. Although plasma is irradiated to insulating member 6 as well, O radicals are generated from insulating member 6 made of quartz by the plasma sputtering. Further, the polymer formed on the rear surface of wafer W is removed as well by the O radicals.
After wafer W is etched for a predetermined time, the supply of the processing gas and the supply of the high-frequency power from high-frequency power supply units 38, 46 stops, the vacuum exhaust in processing chamber 20 by vacuum pump 25 stops, and wafer W is then carried out to the outside of processing chamber 20.
According to the aforementioned exemplary embodiment, since insulating member 6 and heat transfer member 7 are installed under focus ring 5, focus ring 5 is cooled down during plasma processing to suppress the attachment of the polymer (sediment) onto the periphery of the rear surface of wafer W. In this case, since heat transfer member 7 is installed in the concentric pattern with wafer W on placing table 3, focus ring 5 is substantially uniformly cooled in a circumferential direction of wafer W. Since the increase in temperature of focus ring 5 is suppressed and the temperature is stable, there is no concern that the trajectories of the ions in plasma which detour into the rear surface of wafer W will be changed due to the change in temperature of focus ring 5. As a result, the polymer formed on the rear surface of wafer W can be stably removed by the sputtering, such that the amount of polymers attached can be reduced.
Insulating member 6 and heat transfer member 7 are installed to be adjacent to each other in the diameter direction of wafer W on placing table 3, and focus ring 5 is placed on insulating member 6 and heat transfer member 7. In this case, since the height of focus ring 5 is restrained by insulating member 6 made of quartz, there is no concern that the height of focus ring 5 will be changed. Further, confusion of plasma on the periphery of wafer W is suppressed. Since heat transfer member 7 is not interposed between insulating member 6 and focus ring 5, there is no concern that impedance under focus ring 5 will be changed. Further, the potential of the focus ring during plasma processing is stabilized.
As described above, a portion that electrically connects both sides through insulating member 6 and a portion that thermally connects both sides through heat transfer member 7 are separately provided between focus ring 5 and placing table 3. As a result, since an electrical control by insulating member 6 and a temperature control by heat transfer member 7 are independently performed, complexity of the controls can be suppressed. In the aforementioned exemplary embodiment, since insulating member 6 is installed to be corresponded to placing area 32 side, insulating member 6 is positioned near wafer W on placing table 3 and the removal of the polymer by the O radicals which has been already described is rapidly performed.
In the above-mentioned exemplary embodiment, the insulating member and the heat transfer member may be installed to be adjacent to each other in the diameter direction of wafer W on placing table 3 between focus ring 5 and placing table 3, and as shown in FIG. 5, an insulating member 61 may be installed outside the diameter direction of wafer W with respect to a heat transfer member 71. In this example, heat transfer member 71 is installed so that an inner peripheral surface 70 thereof is aligned vertically to inner peripheral surface 52 of the lower side of step portion 51 of focus ring 5.
Continuously, a second exemplary embodiment of the present disclosure will be described with reference to FIG. 6 and FIG. 7. In the configuration of the present example in which the insulating member and the heat transfer member are installed in the concentric pattern outside placing area 32, a first insulating member 62 a and a second insulating member 62 b are installed adjacent to both left and right sides (both sides in the diameter direction of wafer W on placing table 3) of a heat transfer member 72, respectively. This configuration is implemented by forming insulating members 62 a, 62 b and sheet-type heat transfer member 72 in an annular pattern, respectively, and by arranging, on the top of step portion 31 of placing table 3, first insulating member 62 a, heat transfer member 72, and second insulating member 62 b to be lined up in sequence toward the outside from the inside in the diameter direction of wafer W on placing table 3.
Even in this example, focus ring 5 is installed with the height position thereof is restrained by first insulating member 62 a and second insulating member 62 b made of, for example, quartz. Since heat transfer member 72 has adhesiveness, focus ring 5 and heat transfer member 72 as well as insulating member 72 and placing table 3 are closely attached to each other by the adhesiveness, respectively.
Even in this configuration, since insulating members 62 a, 62 b and heat transfer member 72 are installed horizontally adjacent to each other between placing table 3 and focus ring 5, focus ring 5 is substantially uniformly cooled down along the circumference direction thereof and the amount of the polymers attached to the rear surface of wafer W can be reduced. Further, since insulating members 62 a, 62 b are installed at both horizontal sides of heat transfer member 72, the adhesiveness between heat transfer member 72, focus ring 5 and placing table 3 can be ensured while the change in height of focus ring 5 is further restrained. The electrical control of focus ring 5 by insulating members 62 a, 62 b and the temperature control of focus ring 5 by heat transfer member 72 may be independently performed.
Furthermore, since heat transfer member 72 is being surrounded by insulating members 62 a, 62 b, it is difficult to sputter heat transfer member 72 with plasma. As a result, since consumption or deterioration of heat transfer member 72 can be suppressed, the temperature control of focus ring 5 may be stably performed over an extended period of time.
Continuously, a modified example of the exemplary embodiment will be described with reference to FIG. 8 to FIGS. 10A, 10B and 10C. In a configuration of FIG. 8 in which an insulating member 63 and a heat transfer member 73 are installed outside placing area 32 in a concentric pattern with corresponding placing area 32, heat transfer member 73 is installed to be spaced apart from each other in the circumferential direction of wafer W on placing table 3. In this case, a cross section taken along line A-A of FIG. 8 is defined as shown in FIG. 6.
In this case, as shown in FIG. 9, a plurality of heat transfer members 74 may be installed in an insulating member 64 to be spaced apart from each other in the concentric pattern with placing area 32. In this case, a cross section taken along line B-B of FIG. 9 is defined as shown in FIG. 6.
In these configurations of FIG. 8 and FIG. 9, notches are formed to be spaced apart from one another in insulating members 63, 64 formed by, for example, a quartz ring, and heat transfer members 73, 74 formed by an elastic body having adhesiveness are buried in the notches. In this case, heat transfer members 73, 74 are installed in insulating members 63, 64, respectively, so that the top surfaces thereof are closely attached to focus ring 5 and the bottom surfaces thereof are closely attached to placing table 3.
Even in these configurations, since insulating members 63, 64 are installed to be adjacent to both left and right sides of heat transfer members 73, 74 between placing table 3 and focus ring 5, the same effect as the second exemplary embodiment can be acquired.
In a configuration of the example shown in FIGS. 10A, 10B and 10C in which the insulating member and the heat transfer member are installed in the concentric pattern with corresponding placing area 32 outside placing area 32, insulating members 65 a to 65 c and sheet type heat transfer members 75 a, 75 b are installed to be laminated in the diameter direction of wafer W on placing table 3. In this configuration, as shown in FIGS. 10A and 10B, insulating members 65 a to 65 c made by the quartz rings are prepared and annular thin sheet type heat transfer members 75 a, 75 b of which both sides are sandwiched by two insulating members 65 a, 65 b; 65 b, 65 c. Heat transfer members 75 a, 75 b are installed in insulating members 65 a to 65 c so that the top surface thereof is closely attached to focus ring 5 and the bottom surface thereof is closely attached to placing table 3.
Herein, both the top and the bottom ends of heat transfer members 75 a, 75 b are installed to be closely attached to the bottom surface of focus ring 5 and the top and the bottom surfaces of placing table 3, respectively, in order to thermally contact focus ring 5 and placing table 3. In this case, as shown in FIG. 10C, both the top and the bottom ends of heat transfer member 75 a, 75 b are installed to protrude from the top surfaces and the bottom surfaces of insulating members 65 a to 65 c, and groove portions 50, 30 corresponding to the protruded portions are provided on the bottom surface of focus ring 5 and the top surface of placing table 3, and heat transfer member 75 a, 75 b may be closely attached to focus ring 5 and placing table 3 through the protruded portions and groove portions 50, 30.
Even in this configuration, since insulating members 65 a to 65 c and heat transfer members 75 a, 75 b are installed such that insulating member 65 is placed to be adjacent to both left and right sides of heat transfer member 75 between placing table 3 and focus ring 5, the same effect as the second exemplary embodiment can be acquired.
Continuously, a third exemplary embodiment of the present disclosure will be described with reference to FIGS. 11A and 11B. In this example, a plurality of lower heat transfer members 76 a are installed between an insulating member 66 and placing table 3, and a plurality of upper heat transfer members 76 b are installed between insulating member 66 and focus ring 5. The plurality of lower heat transfer members 76 a are closely attached to both the top surfaces of insulating member 66 and placing table 3 between the top surfaces thereof, and installed in a ring type along the focus ring and to be spaced apart from one another in a diameter direction of focus ring 5, respectively. The plurality of upper heat transfer members 75 b are closely attached to both sides between the bottom surfaces of insulating member 66 and focus ring 5, and installed in the ring type along focus ring 5 to be spaced apart from one another in the diameter direction of focus ring 5, respectively.
Specifically, as shown in FIG. 11B, for example, plural rows (e.g., four rows) of annular sheet type lower heat transfer members 76 a and upper heat transfer members 76 b are attached to the top and the bottom of insulating member 66 made by, for example, the quartz ring. A plurality of notch portions 77 are formed in heat transfer members 76 a, 76 b in the circumferential direction, respectively, so that a space between heat transfer members 76 a, 76 b adjacent to each other in the diameter direction of focus ring 5 is allowed to communicate with atmosphere in processing chamber 20. In this example, lower heat transfer member 76 a and upper heat transfer member 76 b of insulating member 66 are installed so as not to be vertically overlapped with each other, but heat transfer members 76 a, 76 b may be installed to be vertically overlapped with each other. Notch portions 77 may be formed on at least one of lower heat transfer member 76 a and upper heat transfer member 76 b.
In this configuration, since the heat of focus ring 5 moves in a path of upper heat transfer member 76 b, insulating member 66, lower heat transfer member 76 a, and placing table 3 in this order during plasma processing, focus ring 5 is cooled down during the plasma processing. As a result, the amount of the polymers attached to the periphery of the rear surface of wafer W can be reduced as in the first exemplary embodiment. Since heat transfer members 76 a, 76 b are installed in the concentric pattern with placing area 32, focus ring 5 can be substantially uniformly cooled down along the circumferential direction thereof.
Since heat transfer members 76 a, 76 b is surface-contacted with insulating member 66, there is a concern that air bubbles will be mixed into a portion between insulating member 66 and heat transfer members 76 a, 76 b during an adhesion. In this case, since notch portions 77 are formed in heat transfer members 76 a, 76 b, when processing chamber 20 is vacuum-exhausted, the air bubbles are discharged from notch portions 77, and as a result, the air bubbles hardly exist between insulating member 66 and heat transfer members 76 a, 76 b during plasma processing. As a result, since contact states between heat transfer members 76 a, 76 b and insulating member 66 are constant in a plane (on the entire bottom of focus ring 5), the heat of focus ring 5 moves toward placing table 3 almost uniformly in the plane to almost uniformly adjust the temperature of focus ring 5.
In the present disclosure as described above, as shown in FIG. 12A, a case in which the height positions of the bottom surfaces of focus ring 5 are different from each other in the diameter direction of wafer W on placing table 3 is included as well in the scope of the present disclosure. As shown in FIG. 12B, for example, when an insulating member 68 and a heat transfer member 78 are arranged to be lined up in the diameter direction of wafer W, a case in which a part of heat transfer member 78 enters into insulating member 68 so that insulating member 68 and heat transfer member 78 are thus laminated vertically in a part of the diameter direction is also included in the scope of the present disclosure.
As shown in FIG. 13, an insulating member 69 is installed in the concentric pattern with respect to the center of wafer W on placing table 3 between the top surface of placing table 3 and the bottom surface of focus ring 5. And a heat transfer member 79 may be installed along focus ring 5 to be closely attached to outer surfaces across the outer surfaces of placing table 3, insulating member 69 and focus ring 5. Even in this configuration, since the heat of focus ring 5 is transferred to placing table 3 through heat transfer member 79, focus ring 5 is cooled down during the plasma processing. In this case, heat transfer member 79 may be configured in the annular pattern and installed to be spaced apart from each other in the concentric pattern with respect to the center of wafer W on placing table 3.

Example

Wafer W was plasma-processed by using the plasma etching apparatus of FIG. 1 and the temperature change of focus ring 5 was measured. Specifically, five wafers W were continuously plasma-processed by supplying CF-based gas as the processing gas to measure the temperature of focus ring 5 with a thermometer using interference of low-coherence light under the condition that 1200 W high-frequency power was supplied from plasma generating high-frequency power supply unit 46, and the temperature of wafer W on placement area 32 was set to 30° C. The quartz ring was used as insulating member 6 and a heat transfer sheet formed with a thickness of 0.5 mm of the high-molecular silicon gel filled with alumina was used as heat transfer member 7. As a Comparative Example, the same plasma processing was performed even with respect to the case in which heat transfer member 7 was not installed and the temperature of focus ring 5 at that time was measured.
This result is shown in FIG. 14. It is understood from the Comparative Example and the Example that the temperature of focus ring 5 is raised so that the heat from plasma is absorbed at the plasma generation timing. However, in the Example, it could be seen that the temperature of focus ring 5 is not substantially changed even though a processing time elapsed, the heat of focus ring 5 moves to placing table 3 and accumulation of the heat in focus ring 5 is suppressed due to the installation of heat transfer member 7, and, as a result, the temperature of focus ring 5 was cooled down to approximately 50° C. Meanwhile, in the Comparative Example, it is understood that the temperature of focus ring 5 is raised with the processing time elapsed and when plasma is continuously irradiated, heat is accumulated in focus ring 5, and as a result, the temperature of focus ring 5 was raised to approximately 230° C.
As described above, the present disclosure can be applied to a plasma processing apparatus that plasma-processes a substrate such as a glass substrate for a flat panel display (FPD) in addition to a semiconductor wafer W. The present disclosure can be applied to a plasma processing apparatus that performs a plasma processing such as an ashing process, a chemical vapor deposition (CVD), or a plasma treatment in addition to an etching process.
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.

Claims

1. A plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus comprising:

a vacuum chamber including a lower electrode and an upper electrode configured to generate the plasma by introducing a processing gas and applying a high-frequency power between the lower electrode and an upper electrode, thereby processing the substrate using the plasma;

a placing table provided in the vacuum chamber serving as the lower electrode and configured to receive a substrate on a substrate placing area;

a ring member installed on the placing table surrounding the substrate placing area and configured to adjust a state of the plasma generated between the lower electrode and the upper electrode;

an insulating member installed along the ring member between a top surface of the placing table and a bottom surface of the ring member in a concentric pattern with a center of the substrate on the placing table and configured to adjust a potential difference between the ring member and the substrate thereby injecting ions of the plasma into a rear surface of the substrate; and

a heat transfer member closely attached to each of the top surface of the placing table and the bottom surface of the ring member along the ring member between the top surface of the placing table and the bottom surface of the ring member at a position adjacent to the insulating member in a diameter direction of the substrate.

2. The plasma processing apparatus of claim 1, wherein the top surface of the insulating member contacts the ring member.

3. The plasma processing apparatus of claim 1, wherein the insulating member is installed at both sides of the inside and the outside of the diameter direction of the substrate with respect to the heat transfer member.

4. A plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus comprising:

a vacuum chamber including a lower electrode and an upper electrode configured to generate the plasma by introducing a processing gas and applying a high-frequency power between the electrodes, thereby processing the substrate using the plasma;

a ring member installed on the placing table surrounding the substrate placing area and configured to adjust a state of plasma generated between the lower electrode and the upper electrode;

an insulating member installed along the ring member between a top surface of the placing table and a bottom surface of the ring member in a concentric pattern with a center of the substrate on the placing table and configured to adjust a potential difference between the ring member and the substrate thereby injecting ions of the plasma into a rear surface of the substrate;

a plurality of lower heat transfer members closely attached to each of the insulating member and the placing table between a top surface of the insulating member and a top surface of the placing table in a concentric pattern with a center of the substrate on the placing table along the ring member and spaced apart from one another in a diameter direction of the ring member; and

a plurality of upper heat transfer members closely attached to each of the insulating member and the ring member between a bottom surface of the insulating member and a bottom surface of the ring member in the concentric pattern with the center of the substrate on the placing table along the ring member and spaced apart from one another in the diameter direction of the ring member.

5. The plasma processing apparatus of claim 4, wherein at least one side of the upper heat transfer member and the lower heat transfer member is notched so that a space between the heat transfer members adjacent to each other in the diameter direction of the ring member is allowed to communicate with atmosphere in the vacuum chamber.

6. A plasma processing apparatus that processes a substrate to be processed using plasma, the apparatus comprising:

a heat transfer member closely attached to each of the sides of the ring member, the insulating member, and the placing table between those sides along the ring member.