Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
  • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
  • H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
  • H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
  • H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
  • H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
  • H01L21/302—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to change their surface-physical characteristics or shape, e.g. etching, polishing, cutting
  • H01L21/306—Chemical or electrical treatment, e.g. electrolytic etching
  • H01L21/3065—Plasma etching; Reactive-ion etching
• • 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
  • H01J37/32532—Electrodes
• • 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
• • 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
  • H01J37/3244—Gas supply 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
  • H01J37/3244—Gas supply means
  • H01J37/32449—Gas control, e.g. control of the gas flow

Definitions

• the present invention relates to a plasma processing apparatus for performing plasma processing to a processing object such as a wafer or the like.
• a plasma processing apparatus operates to produce plasma under a reduced-pressure atmosphere to allow a surface of a processing object to be subjected to etching processing or the like by physical and chemical actions of the plasma.
• Plasma is generated by applying a high-frequency voltage to an upper electrode or lower electrode while the internal pressure within a sealed processing chamber of the plasma processing apparatus is reduced to a specified pressure with a plasma-generation gas (hereinafter, referred to simply as 'gas') fed thereto.
• 'gas' plasma-generation gas
• a process of uniformly spraying and feeding a relatively high-pressure gas to a surface of a silicon wafer is used with a view to improving the processing efficiency.
• Known parallel-plate electrode members suited for such plasma processing formed of a gas-permeable porous plate which is a sintered body of ceramic particles (see, e.g., Japanese unexamined patent publication No. 2002- 231638 A, JP 2003-7682 A and JP 2003-282462 A) .
• a porous plate With the use of such a porous plate, it becomes possible to uniformly generate high-density plasma so that a stable plasma processing is carried out with high etching efficiency.
• the porous plate With a processing object set on a stage which is the lower electrode within the processing chamber, as plasma processing is started by applying a high-frequency voltage to the upper electrode or lower electrode, the porous plate provided on one side closer to the upper electrode, which is a counter electrode to the lower electrode, rapidly increases in temperature.
• the porous plate typically has a diameter of about 220. mm or 320 mm and a thickness of about 2 to 10 mm, the porous plate does not increase in temperature uniformly as a whole, but does increase in temperature first rapidly in vicinities of a central portion of a counter surface
• an object of the present invention lying in solving the above problem, is to provide a plasma processing apparatus in which damage due to occurrence of cracks in an outer edge portion of a porous plate caused by thermal expansion due to rapid temperature increases in plasma processing can be prevented, thus allowing a stable plasma processing to be carried out.
• a plasma processing apparatus comprising a first electrode unit having a placement surface on which a processing object is to be placed, and a second electrode unit facing the placement surface of the first electrode unit, and a processing vessel that defines a processing chamber in which the first and second electrode units are to be located, wherein a plasma- generation gas is supplied into a plasma processing space between the first and second electrode units so as to generate a plasma and then plasma processing on the processing object is performed,
• the second electrode unit comprising: a body portion having a gas supply port communicating with a gas supply passage; a porous plate which is placed so as to cover the gas supply port and face the plasma processing space and which has gas permeability such that the gas supplied from the gas supply port is supplied to the plasma processing space through inside thereof; and a support member which supports the porous plate on its outer edge portion so that the porous plate is fixedly placed to the body portion, wherein a plurality of cutout portions are formed in the outer edge portion of the porous plate at a specified
• the plasma processing apparatus as defined in the first aspect, wherein the porous plate has a disc-like shape, the support member includes an annular member located on a lower surface of the body portion, and a protruding portion annularly protruded inward of an end portion of the annular member, and the outer edge portion of the porous plate located inward of the annular member in the lower surface of the body portion is supported by the protruding portion from below.
• the plasma processing apparatus as defined in the second aspect, wherein the protruding portion is formed so as to project over the individual cutout portions so that gaps of the individual cutout portions of the porous plate are closed against the plasma processing space.
• the porous plate has a support region which is an annular region located in an outer edge portion of the disc-like shape and on which the plate is supported by the protruding portion of the support member, and a gas passage region which is a circular region located inside the outer edge portion of the disc-like shape and surrounded by the support region and in which the plasma-generation gas is allowed to pass therethrough, and each of the cutout portions is formed in the support region so as to be in close proximity to a boundary with the gas passage region.
• the plasma processing apparatus as defined in the fourth aspect, wherein in each of the cutout portions of the porous plate, at least an inner circumferential surface on one side closer to a center of the porous plate is formed into a curved surface.
• each of the cutout portions is so formed that an entirety of its inner circumferential surface becomes a curved surface.
• each of the cutout portions has a slit-like shape.
• the porous plate when plasma processing is started, the porous plate increases in temperature rapidly first in vicinities of its central portion, causing large temperature differences between its outer edge portion and vicinities of the central portion, so that strain due to temperature increases occurs, in particular, to the outer edge portion. Since such occurred strain can be absorbed by respective cutouts portions provided at the outer edge portion, the porous plate can be prevented from being damaged due to occurrence of cracks at the outer edge portion of the plate or other reasons. Further, the individual cutout portions of the porous plate are closed against the plasma processing space by support member, thereby it becomes possible to prevent a gas leakage through the cutout portions and to uniformly generate plasma in the whole plasma processing space.
• Fig. 1 is a sectional view of a plasma processing apparatus according to an embodiment of the present invention
• Fig. 2 is a perspective view of a porous plate of the embodiment
• Fig. 3 is a perspective view (including a partly cut-out cross section) of a support member in which the porous plate is housed in the embodiment;
• Fig. 4 is a partly enlarged sectional view of an upper electrode portion in the embodiment;
• Fig. 5A is a schematic plan view of a conventional porous plate
• Fig. 5B is a schematic sectional view taken along the line A-A in the conventional porous plate of Fig. 5A;
• Fig. 6A is a schematic plan view of the porous plate according to the embodiment of the present invention.
• Fig. 6B is a schematic sectional view taken along the line B-B in the porous plate of Fig. 6A;
• Fig. 7 is a partial schematic plan view showing a configuration of a slit of a porous plate according to a modification example of the embodiment of the present invention;
• Fig. 8 is a schematic explanatory view for explaining the formation method for the slit of Fig. 7;
• Fig. 9 is a partial schematic plan view showing a configuration of a cutout portion of a porous plate according to another modification example of the embodiment of the present invention
• Fig. 10 is a schematic explanatory view for explaining the formation method for the cutout portion of Fig. 9.
• a vacuum chamber (or a vacuum vessel) 1 which is an example of a processing vessel, internally has a processing chamber 2 for performing plasma processing, and a lower electrode 3 which is an example of a first electrode unit and an upper electrode 4 which is an example of a second electrode unit are placed in up-and-down opposition to each other inside the processing chamber 2, by which a parallel-plate type plasma processing apparatus is made up.
• the lower electrode 3 which includes a stage 31 serving as a high-frequency electrode and a protruding portion 32 that protrudes downward from a central portion of the stage 31, is fitted inside the vacuum chamber 1 via an insulating member 33 provided around the outer edge portion of the stage 31.
• a high-frequency power supply unit 5 is electrically connected to the protruding portion 32 of the lower electrode 3.
• An exhaust passage 6 is formed at a side portion of the insulating member 33, serving for vacuum suction of the interior of the processing chamber 2 by an exhaust unit 7 such as a vacuum pump.
• a processing object W such as a wafer is to be mounted.
• the upper electrode 4 which is the counter electrode, includes a flat plate (disc-like plate) -shaped body portion 41, an annular support member 45 provided around a lower-surface outer peripheral portion of the body portion 41, and a porous plate 43 housed inside the support member 45 below the body portion 41.
• the upper electrode 4 is fitted to the vacuum chamber 1 via a protruding portion 42 that protrudes upward from a central portion of the body portion 41.
• the porous plate 43 is a ceramic porous plate formed into a disc-like shape from a porous material which is formed from a sintered body of ceramic particles and which has gas permeability. More specifically, the porous plate 43, i.e.
• ceramic porous plate has a three- dimensional mesh-like structure having ceramic skeletal portions formed continuously into a three-dimensional mesh and having a multiplicity of void portions (gaps) inside. Then, the individual void portions of this three- dimensional mesh-like structure are communicated with one another, and a multiplicity of irregular passages are formed so as to allow gas fed to one surface of the porous plate 43 to pass to the other surface.
• the support member 45 has such an annular shape so as to allow the porous plate 43 to be placed inside thereof and supported. Further, the support member 45 is further provided with a protruding portion (or annular support end portion) 45' that annularly protrudes inward
• the porous plate 43 is housed in an internal space defined by the body portion 41 and the support member 45 with the outer edge portion (outer peripheral edge portion because the porous plate 43 of this embodiment is disc-like-shaped) entirely rested on the protruding portion 45' .
• the porous plate 43 provided on the upper electrode 4 side is disc-like-shaped, and slits S, which are an example of cutout portions, are formed at specified intervals on its outer peripheral edge portion so as to extend thicknesswise (vertically) through the porous plate 43 with the radial direction of the porous plate 43 aligned with the longitudinal direction of the slits S.
• each slit S desirably has a length Ll of about 3 to 10 mm as well as a width L2 of about 0.5 mm to 1.0 mm, and moreover, desirably, the slits S are formed at an interval pitch L3 of 120 mm or less. It is noted that such a cutout portion can also be said to be a recess portion, as the porous plate 43 is seen along its radial direction.
• Fig. 4 shows a desirable connecting structure among the body portion 41, the support member 45 and the porous plate 43.
• the support member 45 is coupled to the body portion 41 by fittings such as bolts 10 or nuts 11.
• An upper surface “a” of the protruding portion 45' is a inwardly descending sloped tapered surface, and a lower surface “b" of the outer peripheral edge portion of the porous plate 43 is an outwardly ascending tapered surface, where the upper surface "a” and the lower surface “b” are joined together in close contact so as not to form any gap. Also, the protruding portion 45' extends inward (toward the central portion) more than the slits S, so that the slits S are closed at lower side thereof by the protruding portion 45'.
• a gas supply port T (described later) on the lower side of the body portion 41 is kept hermetic, so that a gas supplied to the gas supply port T is prevented from leaking to a plasma generation space A through the slits S.
• the outer peripheral edge portion of the porous plate 43 and the protruding portion 45' of the support member 45 each have a tapered surface, the lower surface of the porous plate 43 and the lower surface of the support member 45 can be made generally flush with each other in height position in the state that the porous plate 43 is supported by the protruding portion 45', so that the discharge stability in plasma processing can be improved, compared with cases where no tapered surfaces are provided.
• the upper surface of the porous plate 43 near the outer peripheral edge portion is an outwardly descending tapered surface "c", and a cushioning member 12 is provided between the tapered surface "c" and a portion of the body portion 41 near the outer peripheral edge portion of the porous plate 43.
• the cushioning member 12, which is made from an elastic material such as resin rubber, is ring- shaped as viewed in plan view, ensuring the hermeticity of the gas supply port (or a space for supplying the gas) T, which is a narrow gas flow space between the cushioning member 12 and a portion of the porous plate 43 on the lower surface side of the body portion 41.
• a gas supply passage 46 is formed so as to vertically extend through those members.
• the body portion 41 is electrically grounded to a ground portion 44.
• the gas at the gas supply portion 13 is supplied through the gas supply passage 46 to the gas supply port T, passing inside the porous plate 43, so as to be supplied to the plasma generation space (plasma processing space) A between the lower electrode 3 and the upper electrode 4.
• the upper electrode 4 is electrically grounded in this embodiment, it is also possible that the lower electrode 3 is grounded while the upper electrode 4 is electrically connected to the high-frequency power supply.
• the plasma generation space A rapidly increases in temperature, so that the porous plate 43 increases in temperature first rapidly in vicinities of the central portion of the counter surface (lower surface) of the porous plate 43 confronting the lower electrode 3. Because of thermal expansion due to this temperature increase, there occurs strain to the porous plate 43 especially at its outer peripheral edge portion. However, since the strain is absorbed by the slits S, no cracks, which may cause gas leakage, occur to the outer peripheral edge portion, so that a uniform, stable plasma processing is carried out. Now the principle of absorption of strain due to thermal expansion by the porous plate 43 of this embodiment is concretely explained with reference to the accompanying drawings.
• a schematic plan view of a conventional porous plate 543 having a structure that no cutout portions such as slits are formed is shown in Fig. 5A, and a schematic sectional view taken along the line A-A in the conventional porous plate 543 of Fig. 5A is shown in Fig. 5B.
• a schematic plan view of the porous plate 43 with the slits S formed therein according to this embodiment of the present invention is shown in Fig. 6A
• a schematic sectional view taken along the line B-B in the porous plate 43 of Fig. 6A is shown in Fig. 6B.
• the porous plate 543 having a disc-like shape is supported at the entire lower surface of its annular outer peripheral edge portion by a protruding portion 545' of a support member 545, where the supported portion serves as a support region Rl, which is an annular region (or an planar annular region) , with which the lower surface of the porous plate 543 is covered without being exposed to the plasma generation space A. Meanwhile, inside this outer peripheral edge portion, the lower surface of the porous plate 543 is exposed to the plasma generation space A and serves as a gas passage region R2 that allows the plasma- generation use gas supplied to the gas supply port T to pass through within the porous plate 543 so as to be supplied to the plasma generation space A.
• end portions of the slits S are positioned in the support region Rl so as to be in close proximity to its boundary with the gas passage region R2, i.e., the slits S are formed in the support region Rl so that the radial cut-in depth of the slits S becomes more deeper.
• Fig. 7 which is a partly enlarged schematic plan view of an outer peripheral edge portion of a porous plate 143 of Fig. 7, roughly U- shaped slits S' may be formed.
• a central side inner circumferential surface of the porous plate 143 is formed of a curved surface, an effect of suppressing stress concentration can be obtained, so that occurrence of cracks or the like to the inner circumferential surface of the slit S 1 can be prevented.
• Such a slit S' can be formed by, for example, cutting process with the use of a disc-shaped cutting tool 150 having an outer peripheral end portion formed of a curved surface, as shown in the schematic explanatory view of Fig. 8. It is noted that the curved surface to be formed in such a slit S' is preferably formed into a gently curved surface from the viewpoint of suppressing stress concentration .
• a generally semicircular-shaped cutout portion C having an inner circumferential surface formed of a curved surface alone may be formed as shown in Fig. 9, which is a partly enlarged schematic plan view of an outer peripheral edge portion of a porous plate 243.
• This cutout portion C although having a cut-in depth Al in the radial direction of the porous plate equal to the cut-in depth Al of the slit S' of Fig. 7, yet has an opening size B2, which is the circumferential width, formed larger than an opening size Bl of the slit S 1 because of the circumferential surface formed entirely of a curved surface.
• cutout portion C is formed of a curved surface alone (or formed of a curved surface in most part) , it becomes possible to disperse the stresses to more extent, so that occurrence of cracks or the like can be prevented more reliably.
• cutout portions C can be formed by, for example, cutting process with the use of a bar-shaped cutting tool 250 having a circular-shaped cross section as shown in a schematic explanatory view of Fig. 10.
• the individual cutout portions are preferably made identical in configuration and size and, besides, arranged at an equidistant pitch in order to more uniformly relax stresses that occurs at the outer peripheral edge portion of the porous plate.
• relatively large cutout portions and small cutout portions may be formed compositely in the outer peripheral edge portion of the porous plate (that is, mixed-arrangement of the large and small cutout portions may be applied) .
• other members may be arranged within the individual cutout portions of the porous plate unless elastic deformation of the cutout portions serving for the absorption of any strain due to thermal expansion is inhibited.
• the inner circumferential surfaces of the cutout portions may be subjected to surface finishing or the like in order to suppress gas passage. With such an arrangement, the gas passage through the inner circumferential surfaces of the cutout portions in the porous plate may be suppressed.
• the plasma processing apparatus including such a porous plate is useful as those of plasma processing apparatuses for use of, in particular, surface etching of wafer or the like.

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• Engineering & Computer Science (AREA)
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• Condensed Matter Physics & Semiconductors (AREA)
• Manufacturing & Machinery (AREA)
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• Drying Of Semiconductors (AREA)
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• 2005
  • 2005-04-05 JP JP2005108385A patent/JP4654738B2/ja active Active
• 2006
  • 2006-04-04 US US11/887,758 patent/US20090266488A1/en not_active Abandoned
  • 2006-04-04 KR KR1020077021575A patent/KR101198543B1/ko not_active IP Right Cessation
  • 2006-04-04 TW TW095111954A patent/TW200701346A/zh unknown
  • 2006-04-04 EP EP06731469A patent/EP1869692A1/en not_active Withdrawn
  • 2006-04-04 WO PCT/JP2006/307522 patent/WO2006107114A1/en active Application Filing
  • 2006-04-04 CN CN200680010657XA patent/CN101151703B/zh not_active Expired - Fee Related

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