WO2011008596A2 - Plasma reactor with uniform process rate distribution by improved rf ground return path - Google Patents

Plasma reactor with uniform process rate distribution by improved rf ground return path Download PDF

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Publication number
WO2011008596A2
WO2011008596A2 PCT/US2010/041086 US2010041086W WO2011008596A2 WO 2011008596 A2 WO2011008596 A2 WO 2011008596A2 US 2010041086 W US2010041086 W US 2010041086W WO 2011008596 A2 WO2011008596 A2 WO 2011008596A2
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WIPO (PCT)
Prior art keywords
plasma
chamber
liner
confinement ring
side wall
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Ceased
Application number
PCT/US2010/041086
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French (fr)
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WO2011008596A3 (en
Inventor
Andrew Nguyen
Hiroji Hanawa
Kartik Ramaswamy
Samer Banna
Anchel Sheyner
Valentin N. Todorow
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Applied Materials Inc
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Applied Materials Inc
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Publication of WO2011008596A3 publication Critical patent/WO2011008596A3/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/16—Vessels; Containers
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
    • H01J37/32082—Radio frequency generated discharge
    • H01J37/321—Radio frequency generated discharge the radio frequency energy being inductively coupled to the plasma
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32623—Mechanical discharge control means
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32623—Mechanical discharge control means
    • H01J37/32633—Baffles
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/32—Gas-filled discharge tubes
    • H01J37/32431—Constructional details of the reactor
    • H01J37/32623—Mechanical discharge control means
    • H01J37/32642—Focus rings
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10F—INORGANIC SEMICONDUCTOR DEVICES SENSITIVE TO INFRARED RADIATION, LIGHT, ELECTROMAGNETIC RADIATION OF SHORTER WAVELENGTH OR CORPUSCULAR RADIATION
    • H10F71/00—Manufacture or treatment of devices covered by this subclass

Definitions

  • Plasma processing of semiconductor wafers or other types of workpieces is employed to perform etch processes, deposition processes and plasma immersion ion implantation processes, for example.
  • the plasma source may be an RF source having a capacitively coupled source power applicator such as a ceiling electrode or an inductively coupled source power applicator such as a coil antenna.
  • the rate at which the plasma process is carried out is typically different at different locations on the workpiece surface.
  • a plasma etch process may have a non-uniform etch rate distribution across the workpiece surface. It is critical that the process rate distribution across a workpiece surface be as uniform as possible. This is particularly true in the fabrication of integrated circuits on a semiconductor wafer, in which critical dimensions of thin film
  • etch rate distribution can cause etch stop in some portions of the wafer and over-etching in other portions of the wafer.
  • Such process rate distribution non-uniformities may have a radial pattern, in which the spatial distribution of etch rate across the workpiece surface is center-high, or center-low, for examples.
  • Such radial non- uniformity can be ameliorated or eliminated by employing independently controlled RF source power applicators at different radial locations relative to the plasma reactor chamber.
  • the RF power applicator may consist of inner and outer coil antennas overlying radially inner and outer zones of the work/piece. Radial non-uniformity In distribution of plasma process rate is removed or minimized by adjusting the relative amounts of RF power applied to the inner and outer coil antennas.
  • the process rate distribution may also have an azimuthal pattern of non-uniformity, which may be
  • skew in which the process rate varies with the rotational angle about the central axis of symmetry of the workpiece and reactor chamber. Because the skew pattern is inherently asymmetrical, it is challenging to provide an RF source power applicator that may be adjusted to remove or minimize a particular skew pattern exhibited by a plasma reactor.
  • a plasma reactor includes a reactor chamber enclosed by a chamber side wall, a floor and an overhead ceiling.
  • a workpiece support pedestal is in the chamber and has a pedestal side wall coaxial with the chamber side wall, and a workpiece support surface at a top end of the pedestal and facing the overhead ceiling.
  • the chamber and pedestal side walls define therebetween a pumping anrvulus extending from the top end of the
  • a plasma source power applicator is adjacent the ceiling and a source of RF power is coupled between RF ground and the plasma source power applicator.
  • the plasma reactor further includes an integrally formed ground return path liner.
  • integrally formed ground return path liner includes a plasma confinement ring extending radially outwardly from the pedestal side wall and being adjacent or at least nearly co-planar with the workpiece support surface, the plasma confinement ring comprising an annular array of radial slots, each of the slots having a narrow width corresponding to an 1on co111 sion mean free path 1ength of a plasma.
  • the integrally formed ground return path liner further includes a side wall, liner covering an interior surface of the side wall and extending axially from a height near a height of the workplace support surface to the ceiling,
  • the integrally formed ground return path liner also includes an intermediate section having a curved cross-sectional shape and integrally joining together a radially outward end of the plasma confinement ring and a bottom end of the removable side wall liner.
  • the integrally formed ground return path liner eliminates or minimizes skew or asymmetries in plasma process distribution across the workpiece surface by providing a uniform RF ground return of minimum length for RF power from the RF source power applicator ,
  • FIG. I is a cut-away side view of a plasma reactor chamber in accordance with a first embodiment .
  • FIG. 2 is a plan view of a portion of the embodiment of FIG. 1.
  • FIG. 3 is a cut-away side view of a plasma reactor chamber in accordance with a second embodiment
  • FIG. 4 is a perspective view of a portion of the embodiment of FIG. 3.
  • FIG. 5A is a graph of two-dimensional spatial distribution of etch rate obtained with a conventional RF ground return path.
  • FIG. SB is a graph of two-dimensional spatial distribution of etch rate obtained with a uniform RF ground return path in accordance with one embodiment.
  • FIGS. 6A, 6B and 6C are comparative graphs of etch rates as a function of asimuthal angle at respective radial locations using a conventional RF ground return path and using a uniform RF ground return path in
  • a plasma reactor chamber 100 is defined by a cylindrical side wall 102, a ceiling 104 and a floor 106, A cylindrical liner 108 has an outer shoulder 110 resting on a top surface of the side wail 102 and an inner shoulder 112 supporting the ceiling 104.
  • the cylindrical liner is a consumable component of the chamber and is readily removed and replaced
  • workpiece support pedestal 116 extends through an opening 118 in the floor 106 and includes a cylindrical pedestal wall 120 having an outer shoulder 122 supported by the floor 106, The pedestal 116 further includes an
  • the ESC 124 includes an internal electrode 128 and a workpiece support surface 130 overlying and insulated from the electrode 128, A D, C, voltage source 132 provides an electrostatic clamping voltage to the ESC electrode 128 for holding a semiconductor workplace or wafer 134 to the support surface 130.
  • RF bias power from an RF bias power generator 136 may be applied to the electrode 128 through an impedance match 138 and an isolation capacitor 139.
  • An inductively coupled RF source power applicator 140 overlies the ceiling 104.
  • the RF source power applicator may consist of radially inner and outer applicator portions 140-1, 140-2 that are independently driven by respective RF source power generators 142-1, 142-2 through respective RF impedance matches 144-1, 144-2.
  • Each RF source power applicator portion 140-1, 140-2 is a solenoidal coil antenna.
  • the ceiling 104 is formed of a dielectric or semiconductor material that enables the inductive RF field from the RF source power applicator 140 to pass through the ceiling 104.
  • a metallic shield 150 surrounds the coil antennas 140-1, 140-2 and consists of a metallic cylindrical wall. 152 and a discoid ceilinq 154.
  • the shield 150 rests on top of the cylindrical liner IQS, the connection between the shield ISO and the cylindrical liner 108 providing a around return path extending axially up the length of the cylindrical shield and terminating at the ceiling adjacent the touching surfaces of the shield 150 and liner .1.08.
  • the pedestal vail 120 and the chamber side wall. 102 define an annular volume or pumping annuius 156 through which a vacuum pump 158 evacuates the chamber 100.
  • So ⁇ ae plasma may be lost from the processing region overlying the workpiece 134 into the pumping annuius, thereby affecting process rate and attacking chamber surfaces in the pumping annul us 156.
  • a plasma confinement grid 160 extends radially from the wafer support pedestal 116 into the pumping ann ⁇ lus 156, The grid 160 is supported on a top edge of the cylindrical pedestal, wail 120, as shown in FIG. 1.
  • the top surface of the plasma confinement grid 160 is co-planar or nearly co-planar with the workpiece 134 or with the workpiece support surface 130 or slightiy below it.
  • the grid 160 reduces or biocks plasma flow into the pumping annuius 156 without
  • a gap 162 is provided between the outer edge of the confinement grid 160 and the cylindrical liner 108. In one embodiment, the gap 162 ensures adequate gas flow past the confinement grid 160 «
  • the grid 160 has radial slots 164 eztending between two radii Ri, R2, corresponding to a radial length R2-R.1, and arrayed in an annular pattern, best shown in FIG. 2. The radial slots 164 further enhance gas flow into the p ⁇ raping annul ⁇ s 156.
  • each slot 16*3 has an az i ⁇ v ⁇ thai width W that is less than the ion collision mean free path length of the plasma generated in the process region between the workplace 134 and the ceiling 104 « In one embodiment, W is about 0.2 inch,
  • brackets 170 are fastened between the grid 160 and the liner 108.
  • Each bracket 170 is fastened, for example by screws, to an outer periphery of the grid 160 and to the nearest surface.
  • the brackets 170 are arrayed at uniform intervals around the grid 160. The introduction of the discrete brackets 170 does not noticeably interfere with gas flow into the pumping annulus 156 «
  • FIGS. 3 and 4 depict an embodiment in which the direct RF current path provided, by the brackets 170 is instead provided by forming the plasma confinement grid 160 of FIG. 1 and the cylindrical liner 103 of FIG. I as a monolithic integrally formed grid-liner 180.
  • the grid- liner ISO of FIGS. 3 and 4 has a radial section 182 corresponding to the plasma confinement grid 160 of FIGS. 1 and 2, an axial section 184 corresponding to the cylindrical liner 10S, and an intermediate section 186 joining the radial and axial sections 182, 184.
  • the intermediate section .186 is formed of metal and therefore provides a conductive path between the radial and axial sections 182, 184, and has an arcuate cross-sectional shape to provide a smooth surface transition and minimize undesirable interaction with plasma «
  • the radial section 182 includes an annular array of radial slots 188
  • each radial slot 188 may be increased without increasing its width W beyond the ion collision mean free path length, by increasing its radial length. For this purpose, each slot 188 in the
  • 3 and 4 lies between two radii R3, R4 defining a radial length R4-R3 greater than that of the embodiment of FIGS. 1 and 2 (i.e., R2-R1).
  • This increase may correspond to a 5% to 20% increase in radial length, for example.
  • FIG. 5A depicts the two-dimensional
  • FIG. SA depicts a very large skew 300 in the etch rate
  • FIG. 5B depicts the two-dimensional distribution of etch rate on a semiconductor wafer subjected to the same plasma etch process in the reactor chamber of FlG. 1 with the brackets 170 installed.
  • FIG. SB shows that there is relatively little skew in the etch rate distribution when the brackets 170 are installed.
  • FIG. 1 indicate the circuitous RF ground return path that exists in absence of. the brackets .170.
  • RF power delivered by the RF source power applicator 140 develops a ground return current that flows radially outwardly on the top surface of the wafer 134 and of the grid 160, then wraps underneath to flow radially inwardly along the bottom surface of the grid 160, then axially downward along the outside surface of the pedestal wail 120, radially outwardly along the floor 106 and the vertically up along the interior surface of the side wall 102 and the up along the interior surface of the liner 108,
  • Arrows 205 of FlG, 3 indicate the direct path that is provided, for the RF ground return current s t the direct path of FIG.
  • FIGS. 6A, 68 and 6C compare measured data obtained with and without the brackets 170 of FlG, 1.
  • Each point in FIG. 6A is a measured etch rate at an inner radius at a particular azimuthal angle.
  • the diamond- ⁇ haped points correspond to an absence of the brackets 170 and the circular-shaped points correspond to data obtained with the brackets 170 in place as shown in FIG. 1.
  • FIG. 6B depicts the same type of data as FIG. 6A except that the measurements -were taken at an
  • FIG. 6C depicts the same type of data as FIG, 6A except that the measurements were taken at an outer radius. Analysis of the data of FIGS, 6A-6C indicates the following: In the inner radius ⁇ FIG, 6A), without the brackets 170 the variation in etch rate was 48.2 A/min with a variance of 7.06%, while introduction of the brackets 170 reduced the variation to 28,4 A/rnin and the variance to 4.25)%. In the intermediate radius (FlG. 6B), without the brackets ⁇ 70 the variation in etch rate was 55,7 A/min with a variance of 7.71%, while introduction of the brackets .1.70 reduced the variation to 26.4 A/min and the variance to 3,75's, In the outer radius (FIG. 6C) , without the brackets 170 the variation in etch rate was 59.1 A/min with a variance of 7.75 % , while introduction of the brackets 170 reduced the variation to 36.4 A/min and the variance to 4.84%.

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • Plasma Technology (AREA)
  • Drying Of Semiconductors (AREA)

Abstract

In a plasma reactor having an RF plasma source power applicator at its ceiling, an integrally formed grid liner includes a radially extending plasma confinement ring and an axiaily extending side wall liner. The plasma confinement ring extends radially outwardly near the plane of a workpiece support: surface from a pedestal side wail, and includes an annular array of radial slots, each of the siots having a narrow width corresponding to an ion collision mean free path length of a plasma in the chamber. The side wail liner covers an interior surface of the chamber side wall and extends axiaily from a height near a height of said workplace support surface to the chamber ceiling.

Description

PLASM& REACTOR WITH UNIFORM PROCESS RATE DISTRIBUTION BY IMPROVED RF GROUND RETURN PATH
Inventors :
Andrew Nguyen, Hiroji Hanawa, Kartik Ramaswamy, Samer Banna, Anchel Sheyner and Valentin N. Todorov
BACKGROUND
[001] Plasma processing of semiconductor wafers or other types of workpieces, such as plasma displays, soiar panels or photolithographic masks, is employed to perform etch processes, deposition processes and plasma immersion ion implantation processes, for example. The plasma source may be an RF source having a capacitively coupled source power applicator such as a ceiling electrode or an inductively coupled source power applicator such as a coil antenna. The rate at which the plasma process is carried out is typically different at different locations on the workpiece surface. For example, a plasma etch process may have a non-uniform etch rate distribution across the workpiece surface. It is critical that the process rate distribution across a workpiece surface be as uniform as possible. This is particularly true in the fabrication of integrated circuits on a semiconductor wafer, in which critical dimensions of thin film
structures have been reduced to 32 nanometers or less, At such small feature sizes, a non-uniform etch rate distribution can cause etch stop in some portions of the wafer and over-etching in other portions of the wafer.
[002] Such process rate distribution non-uniformities may have a radial pattern, in which the spatial distribution of etch rate across the workpiece surface is center-high, or center-low, for examples. Such radial non- uniformity can be ameliorated or eliminated by employing independently controlled RF source power applicators at different radial locations relative to the plasma reactor chamber. For example, in the case of an inductively coupled P.F source power applicator overlying the plasma chamber ceiling, the RF power applicator may consist of inner and outer coil antennas overlying radially inner and outer zones of the work/piece. Radial non-uniformity In distribution of plasma process rate is removed or minimized by adjusting the relative amounts of RF power applied to the inner and outer coil antennas.
[003] The process rate distribution may also have an azimuthal pattern of non-uniformity, which may be
referred to as "skew", in which the process rate varies with the rotational angle about the central axis of symmetry of the workpiece and reactor chamber. Because the skew pattern is inherently asymmetrical, it is challenging to provide an RF source power applicator that may be adjusted to remove or minimize a particular skew pattern exhibited by a plasma reactor.
SUMMARY
[004] A plasma reactor includes a reactor chamber enclosed by a chamber side wall, a floor and an overhead ceiling. A workpiece support pedestal is in the chamber and has a pedestal side wall coaxial with the chamber side wall, and a workpiece support surface at a top end of the pedestal and facing the overhead ceiling. The chamber and pedestal side walls define therebetween a pumping anrvulus extending from the top end of the
pedestal side wall, to the floor. A plasma source power applicator is adjacent the ceiling and a source of RF power is coupled between RF ground and the plasma source power applicator. The plasma reactor further includes an integrally formed ground return path liner. The
integrally formed ground return path liner includes a plasma confinement ring extending radially outwardly from the pedestal side wall and being adjacent or at least nearly co-planar with the workpiece support surface, the plasma confinement ring comprising an annular array of radial slots, each of the slots having a narrow width corresponding to an 1on co111 sion mean free path 1ength of a plasma. The integrally formed ground return path liner further includes a side wall, liner covering an interior surface of the side wall and extending axially from a height near a height of the workplace support surface to the ceiling, The integrally formed ground return path liner also includes an intermediate section having a curved cross-sectional shape and integrally joining together a radially outward end of the plasma confinement ring and a bottom end of the removable side wall liner. The integrally formed ground return path liner eliminates or minimizes skew or asymmetries in plasma process distribution across the workpiece surface by providing a uniform RF ground return of minimum length for RF power from the RF source power applicator ,
BRIEF DESCRIPTION OF THE DRAWINGS
[005] So that the manner in which the exemplary embodiments of the present invention are attained and can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to the embodiments thereof which are
illustrated in the appended drawings. it is to be appreciated that certain well known processes are not discussed herein in order to not obscure the invention.
[006] FIG. I is a cut-away side view of a plasma reactor chamber in accordance with a first embodiment .
[007] FIG. 2 is a plan view of a portion of the embodiment of FIG. 1.
[008] FIG. 3 is a cut-away side view of a plasma reactor chamber in accordance with a second embodiment ,
[009] FIG. 4 is a perspective view of a portion of the embodiment of FIG. 3.
[0010] FIG. 5A is a graph of two-dimensional spatial distribution of etch rate obtained with a conventional RF ground return path.
[0011] FIG. SB is a graph of two-dimensional spatial distribution of etch rate obtained with a uniform RF ground return path in accordance with one embodiment.
[0012] FIGS. 6A, 6B and 6C are comparative graphs of etch rates as a function of asimuthal angle at respective radial locations using a conventional RF ground return path and using a uniform RF ground return path in
accordance with one embodiment,
[0013] To facilitate understanding, identical
reference numerals have been used, where possible, to designate identical elements that are comtnon to the figures. It is contemplated that elements and features of one embodiment may be beneficially incorporated in other embodiments without further recitation. It is to be noted, however, that the appended drawings illustrate only exemplary embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments .
DETAILED DESCRIPTION
[0014] We have discovered that one of the causes of asymmetrical or skew non-uniformities in plasma process distribution across a workplece lies in the effects of an RF ground return path that is followed by RF source power applied at the chamber ceiling, the RF ground return path extending through the wafer or workpiece and reaching RF ground through the chamber side wall. We have discovered that the undesirable effects of the Rl1 ground return path arise from the fact that it is relatively long,
circuitous and extends through several chamber
components. Such chamber components themselves may have asymmetrical properties. We have further discovered that this skew problem is solved by introducing a structure that provides the most direct path to RF ground for RF ground currents returning through the workpiece.
Embodiments of the present invention provide a reduction or virtual elimination of asymmetries or skew
nonuniformiti.es in process rate distribution across the workpiece surface, as will be described below.
[0015] Referring to FIG. I, a plasma reactor chamber 100 is defined by a cylindrical side wall 102, a ceiling 104 and a floor 106, A cylindrical liner 108 has an outer shoulder 110 resting on a top surface of the side wail 102 and an inner shoulder 112 supporting the ceiling 104. The cylindrical liner is a consumable component of the chamber and is readily removed and replaced
periodically. It is generally formed of a metal. A.
workpiece support pedestal 116 extends through an opening 118 in the floor 106 and includes a cylindrical pedestal wall 120 having an outer shoulder 122 supported by the floor 106, The pedestal 116 further includes an
electrostatic chuck (ESC) 124 supported on an inner shoulder 126 of the pedestal wail 120. The ESC 124 includes an internal electrode 128 and a workpiece support surface 130 overlying and insulated from the electrode 128, A D, C, voltage source 132 provides an electrostatic clamping voltage to the ESC electrode 128 for holding a semiconductor workplace or wafer 134 to the support surface 130. An annular process ring 135
surrounds the wafer or workplace 134 and has a top surface 135a generally co-planar with the top surface of the workpiece 134. The process ring 135 may be formed of the same material as the workpiece 134. Optionally, RF bias power from an RF bias power generator 136 may be applied to the electrode 128 through an impedance match 138 and an isolation capacitor 139. An inductively coupled RF source power applicator 140 overlies the ceiling 104. Optionally, the RF source power applicator may consist of radially inner and outer applicator portions 140-1, 140-2 that are independently driven by respective RF source power generators 142-1, 142-2 through respective RF impedance matches 144-1, 144-2. Each RF source power applicator portion 140-1, 140-2 is a solenoidal coil antenna. The ceiling 104 is formed of a dielectric or semiconductor material that enables the inductive RF field from the RF source power applicator 140 to pass through the ceiling 104. A metallic shield 150 surrounds the coil antennas 140-1, 140-2 and consists of a metallic cylindrical wall. 152 and a discoid ceilinq 154. The shield 150 rests on top of the cylindrical liner IQS, the connection between the shield ISO and the cylindrical liner 108 providing a around return path extending axially up the length of the cylindrical shield and terminating at the ceiling adjacent the touching surfaces of the shield 150 and liner .1.08. The pedestal vail 120 and the chamber side wall. 102: define an annular volume or pumping annuius 156 through which a vacuum pump 158 evacuates the chamber 100.
[0016] Soτae plasma may be lost from the processing region overlying the workpiece 134 into the pumping annuius, thereby affecting process rate and attacking chamber surfaces in the pumping annul us 156.
[0017] Optionally, a plasma confinement grid 160 extends radially from the wafer support pedestal 116 into the pumping annυlus 156, The grid 160 is supported on a top edge of the cylindrical pedestal, wail 120, as shown in FIG. 1. The top surface of the plasma confinement grid 160 is co-planar or nearly co-planar with the workpiece 134 or with the workpiece support surface 130 or slightiy below it. The grid 160 reduces or biocks plasma flow into the pumping annuius 156 without
significantly blocking gas flow to the pumping annuius 156, in order to permit the vacuum pump 158 to evacuate the chamber 100. A gap 162 is provided between the outer edge of the confinement grid 160 and the cylindrical liner 108. In one embodiment, the gap 162 ensures adequate gas flow past the confinement grid 160« The grid 160 has radial slots 164 eztending between two radii Ri, R2, corresponding to a radial length R2-R.1, and arrayed in an annular pattern, best shown in FIG. 2. The radial slots 164 further enhance gas flow into the pυraping annulυs 156. Tn order to confine plasma above the grid 160, each slot 16*3 has an az iπvυthai width W that is less than the ion collision mean free path length of the plasma generated in the process region between the workplace 134 and the ceiling 104« In one embodiment, W is about 0.2 inch,
[0018] We have discovered that skew in plasma process rate distribution across the workplace surface is either dramatically reduced or eliminated by providing an RF current path directly from an outer edge l€Oa of the grid 160 to the cylindrical liner 108. For this purpose, metallic brackets 170 are fastened between the grid 160 and the liner 108. Each bracket 170 is fastened, for example by screws, to an outer periphery of the grid 160 and to the nearest surface. As shown in I1IG, 2, the brackets 170 are arrayed at uniform intervals around the grid 160. The introduction of the discrete brackets 170 does not noticeably interfere with gas flow into the pumping annulus 156«
[0019] FIGS. 3 and 4 depict an embodiment in which the direct RF current path provided, by the brackets 170 is instead provided by forming the plasma confinement grid 160 of FIG. 1 and the cylindrical liner 103 of FIG. I as a monolithic integrally formed grid-liner 180. The grid- liner ISO of FIGS. 3 and 4 has a radial section 182 corresponding to the plasma confinement grid 160 of FIGS. 1 and 2, an axial section 184 corresponding to the cylindrical liner 10S, and an intermediate section 186 joining the radial and axial sections 182, 184. The intermediate section .186 is formed of metal and therefore provides a conductive path between the radial and axial sections 182, 184, and has an arcuate cross-sectional shape to provide a smooth surface transition and minimize undesirable interaction with plasma « The radial section 182 includes an annular array of radial slots 188
corresponding to the radial slots 164 of FIGS. I and 2, and may have dimensions corresponding thereto. The presence of the curved intermediate section 186
eliminates the gap 162: of. FIGS. 1 and 2, forcing all of the gas drawn by the vacuum pump 158 to flow through the radial slots .188. In order to compensate for elimination of the gap and in order to avoid an increase in gas flow resistance, the area of each radial slot 188 may be increased without increasing its width W beyond the ion collision mean free path length, by increasing its radial length. For this purpose, each slot 188 in the
embodiment of FIGΣ5, 3 and 4 lies between two radii R3, R4 defining a radial length R4-R3 greater than that of the embodiment of FIGS. 1 and 2 (i.e., R2-R1). This increase may correspond to a 5% to 20% increase in radial length, for example.
[0020] FIG. 5A depicts the two-dimensional
distribution of etch rate on a semiconductor wafer subjected to a plasma etch process in the reactor chamber of FIG, I in absence of the array of brackets 170. FIG. SA depicts a very large skew 300 in the etch rate
distribution. FlG. 5B depicts the two-dimensional distribution of etch rate on a semiconductor wafer subjected to the same plasma etch process in the reactor chamber of FlG. 1 with the brackets 170 installed. FIG. SB shows that there is relatively little skew in the etch rate distribution when the brackets 170 are installed.
[0021] Our discovery involves the effects of the RF ground return current paths. Arrows 200 of FIG. 1 indicate the circuitous RF ground return path that exists in absence of. the brackets .170. RF power delivered by the RF source power applicator 140 develops a ground return current that flows radially outwardly on the top surface of the wafer 134 and of the grid 160, then wraps underneath to flow radially inwardly along the bottom surface of the grid 160, then axially downward along the outside surface of the pedestal wail 120, radially outwardly along the floor 106 and the vertically up along the interior surface of the side wall 102 and the up along the interior surface of the liner 108, Arrows 205 of FlG, 3 indicate the direct path that is provided, for the RF ground return current st the direct path of FIG. 3 flowing radially outwardly along the top surface of the wafer 134 and then along the interior surface of the liner-grid 180, This short and more direct path is apparently distributed more uniformly and therefore does not introduce the asymmetries manifest in the data of FIG. 5Α.
[0022] FIGS. 6A, 68 and 6C compare measured data obtained with and without the brackets 170 of FlG, 1. Each point in FIG. 6A is a measured etch rate at an inner radius at a particular azimuthal angle. The diamond- εhaped points correspond to an absence of the brackets 170 and the circular-shaped points correspond to data obtained with the brackets 170 in place as shown in FIG. 1. FIG. 6B depicts the same type of data as FIG. 6A except that the measurements -were taken at an
intermediate radius. FlG. 6C depicts the same type of data as FIG, 6A except that the measurements were taken at an outer radius. Analysis of the data of FIGS, 6A-6C indicates the following: In the inner radius {FIG, 6A), without the brackets 170 the variation in etch rate was 48.2 A/min with a variance of 7.06%, while introduction of the brackets 170 reduced the variation to 28,4 A/rnin and the variance to 4.25)%. In the intermediate radius (FlG. 6B), without the brackets Ϊ70 the variation in etch rate was 55,7 A/min with a variance of 7.71%, while introduction of the brackets .1.70 reduced the variation to 26.4 A/min and the variance to 3,75's, In the outer radius (FIG. 6C) , without the brackets 170 the variation in etch rate was 59.1 A/min with a variance of 7.75%, while introduction of the brackets 170 reduced the variation to 36.4 A/min and the variance to 4.84%.
These results indicate that the improvement gained by changing the ground return path from the circuitous one of FTG. 1 to the direct one of FTG. 3 is a factor of 1.5 or more in reduction of asymmetry or skew.
[0023] While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

What is claimed is:
1. A plasma reactor comprising:
a reactor chamber enclosed by a chamber side wall, a floor and an overhead ceiling;
a workpiece support pedestal in said chamber and comprising a pedestal side wall coaxial with said chamber side wall, and a workplace support surface at a top end of said pedestal and facing said overhead
ceiling, said chamber and pedestal side walls defining therebetween a pumping annuius extending froin the top end of said pedestal side wail to said floor;
a plasma source power applicator adjacent said ceiling and a source of RF power coupled between RF ground and said, plasma source power applicator;
an integrally formed ground return path iiner, comprising:
a plasma confinement ring extending radially outwardly from said pedestal side wail and being adjacent or at least nearly co-planar with said workpiece support surface, said plasma confinement ring comprising an annular array of radial slots, each of said slots having a narrow width corresponding to an ion collision mean free path length of a plasma;
a side wall liner covering an interior surface of said side wall and extending axial Iy from a height near a height of said workplace support surface to said ceiling; and
an intermediate section having a curved cross-sectional shape and integrally joining together a radially outward end of said plasma confinement ring and a bottom end of said removable side wall iiner.
2. The plasma reactor of Claim 1 wherein said intermediate member is continuous along an entire
circumference of said, outward, end. of said, plasma
confinement ring.
3. The plasma reactor of Claim 1 wherein said side vail liner is coupled to RF ground.
4. A plasma reactor comprising :
a reactor chamber enclosed by a chamber side wail, a floor and an overhead ceiling;
a workpiece support pedestal in said chamber and comprising a pedestal side wall coaxial with said chamber side wall, and a workpiece support surface at a top end of said, pedestal and facing said overhead
ceiling, said chamber and pedestal side wails defining therebetween a pumping annulus extending from the top end of said pedestal side wall to said floor;
a plasma source power applicator adjacent, said ceiling and a source of RF power coupled between RF ground and said plasma source power applicator;
a plasma confinement ring extending radially outwardly from said pedestal side wail and being nearly co-planar or slightly below said workpiece support surface, said plasma confinement ring comprising an annular array of radial slots, each of said slots having a narrow width corresponding to an ion collision mean free path length of a plasma;
a removable side wall liner covering an
interior surface of said side wall and extending azially from a height, near a height of said workpiece support, surface to said ceiling; and a direct conductive path element between a radially outer edge of said plasma confinement ring and a bottom end of said removable side wail liner,
5, The plasma reactor of Claim 4 wherein said direct conductive path element comprises a continuous metal annulus integrally formed with a bottom end of said removable side wall liner and a radially outward end of said plasma confinement ring.
6, The plasma reactor of Claiiti 5 wherein said continuous metal annuius extends along an entire
circumference of said radially outward end of said plasma confinement ring.
7. The plasma reactor of Claim 6 wherein said removable liner is coupled to RF ground.
8. The plasma reactor of Claim 4 wherein said direct conductive path element comprises a plurality of metal brackets each fastened to a bottom end of said removable liner and to a radially outward end of said plasma confinement ring, said brackets being distributed along a circumference of said piasma confinement ring.
9. The plasma reactor of Claim 8 further
comprising a circumferential gas flow ςraρ> between said bottom end of said removable liner and said radially outward end of said plasma confinement ring, said metal brackets spanning said circumferential gas flow gap.
10, An integrally formed chamber liner for a process chamber comprising: an annular plasma confinement ring configured to radially" extend outwardly Irs. a support plane of a substrate support of said, chamber, said plasma
confinement ring comprising an annular array of radial slots, each of said slots having a width less than a radial length of the slot;
a side wail liner extending axial Iy from a periphery of said, annular plasma confinement ring and. having an axial height corresponding to a substrate support-to-ceiling height of the chamber; and
an intermediate section having a curved cross- sectional shape and. integrally joining together a
radially outward end of said plasma confinement ring and a bottom end of said removable side wall liner, wherein said annular plasma confinement section, said side wail liner and said intermediate section are integrally formed together of conductive material.
11. The chamber liner of Claim IG wherein said intermediate member is continuous along an entire
circumference of said outward end of said plasma
confinement ring.
12, A chamber liner for a process chamber
comprising :
an annular plasma confinement ring formed of a conductive material and configured to radially extend outwardly in a support plane of a substrate support, of said chamber, said plasma confinement ring comprising an annular array of radial slots, each of said slots having a width less than a radial length of the slot;
a side ^aii liner extending axiaiiy from a periphery of said annular plasma confinement ring and having an axial height corresponding to a substrate support-to-ceiling height of the chamber; and
a direct conductive path element between a radially outer edge of said plasma confinement ring and a bottom end of said side wall liner,
13« The chamber liner of Claim 12 wherein said direct conductive path element comprises a continuous metal anπuius integrally formed with a bottom end of said side wall liner and a radially outward end of said plasma conf1neJTient r.1.ng .
14. The chamber liner of Claim 13 wherein said continuous metal annulus extends along an entire
circumference of said radially outward end of said plasma confinement ring,
15, The chamber liner of Claim 12 wherein said- direct conductive path element comprises a plurality of metal brackets each fastened to a bottom end of said removable liner and to a radially outward end of said plasma confinement ring, said brackets being distributed along a circumference of said plasma confinement ring.
16« The chamber liner of Claim 15 further
comprising a circumferential gas flow gap between said bottom end of said side wall liner and said radially outward end of said plasma confinement ring, said metal brackets spanning said circumferential gas flow gap.
PCT/US2010/041086 2009-07-13 2010-07-06 Plasma reactor with uniform process rate distribution by improved rf ground return path Ceased WO2011008596A2 (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI771770B (en) * 2019-10-18 2022-07-21 大陸商中微半導體設備（上海）股份有限公司 Plasma processor and method for preventing arc damage to confinement rings

Families Citing this family (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101663421A (en) 2007-04-27 2010-03-03 应用材料股份有限公司 Annular baffle
WO2012166265A2 (en) 2011-05-31 2012-12-06 Applied Materials, Inc. Apparatus and methods for dry etch with edge, side and back protection
TW201325326A (en) * 2011-10-05 2013-06-16 應用材料股份有限公司 Plasma processing equipment and substrate support assembly thereof
US20130122711A1 (en) * 2011-11-10 2013-05-16 Alexei Marakhtanov System, method and apparatus for plasma sheath voltage control
US10777387B2 (en) * 2012-09-28 2020-09-15 Semes Co., Ltd. Apparatus for treating substrate
WO2015023435A1 (en) * 2013-08-12 2015-02-19 Applied Materials, Inc. Recursive pumping for symmetrical gas exhaust to control critical dimension uniformity in plasma reactors
CN103811263B (en) * 2014-02-25 2016-06-01 清华大学 Plasm restraint device and there is its plasma processing apparatus
JP6906377B2 (en) * 2017-06-23 2021-07-21 東京エレクトロン株式会社 Exhaust plate and plasma processing equipment
US11127572B2 (en) * 2018-08-07 2021-09-21 Silfex, Inc. L-shaped plasma confinement ring for plasma chambers
US11270898B2 (en) * 2018-09-16 2022-03-08 Applied Materials, Inc. Apparatus for enhancing flow uniformity in a process chamber
CN208835019U (en) * 2018-11-12 2019-05-07 江苏鲁汶仪器有限公司 A reaction chamber lining
TWI765213B (en) 2019-01-23 2022-05-21 大陸商北京北方華創微電子裝備有限公司 Lined cooling components, reaction chambers and semiconductor processing equipment
US20220139661A1 (en) * 2019-04-01 2022-05-05 One Semicon. Co., Ltd. Manufacturing method of plasma focus ring for semiconductor etching apparatus
CN114174556B (en) * 2019-07-29 2025-08-19 朗姆研究公司 Susceptor arrangement using camera wafer
KR20220137989A (en) * 2020-02-10 2022-10-12 램 리써치 코포레이션 Tunability of Edge Plasma Density for Tilt Control
CN115917702A (en) * 2020-10-30 2023-04-04 朗姆研究公司 wear compensating restraint ring
CN114639585B (en) * 2020-12-16 2025-02-14 中微半导体设备(上海)股份有限公司 Confinement ring assembly, plasma processing device and exhaust control method thereof

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6129808A (en) * 1998-03-31 2000-10-10 Lam Research Corporation Low contamination high density plasma etch chambers and methods for making the same
US6221221B1 (en) * 1998-11-16 2001-04-24 Applied Materials, Inc. Apparatus for providing RF return current path control in a semiconductor wafer processing system
JP4831853B2 (en) 1999-05-11 2011-12-07 東京エレクトロン株式会社 Capacitively coupled parallel plate plasma etching apparatus and plasma etching method using the same
US20050022736A1 (en) * 2003-07-29 2005-02-03 Lam Research Inc., A Delaware Corporation Method for balancing return currents in plasma processing apparatus
US7906032B2 (en) * 2006-03-31 2011-03-15 Tokyo Electron Limited Method for conditioning a process chamber
US7976671B2 (en) 2006-10-30 2011-07-12 Applied Materials, Inc. Mask etch plasma reactor with variable process gas distribution
US20080193673A1 (en) 2006-12-05 2008-08-14 Applied Materials, Inc. Method of processing a workpiece using a mid-chamber gas distribution plate, tuned plasma flow control grid and electrode
US7972470B2 (en) 2007-05-03 2011-07-05 Applied Materials, Inc. Asymmetric grounding of rectangular susceptor
US7988815B2 (en) * 2007-07-26 2011-08-02 Applied Materials, Inc. Plasma reactor with reduced electrical skew using electrical bypass elements

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
TWI771770B (en) * 2019-10-18 2022-07-21 大陸商中微半導體設備（上海）股份有限公司 Plasma processor and method for preventing arc damage to confinement rings

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TWI407844B (en) 2013-09-01

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