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
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
  • H01J37/32137—Radio frequency generated discharge controlling of the discharge by modulation of energy
• • 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
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32082—Radio frequency generated discharge
• • 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
  • H01J37/32137—Radio frequency generated discharge controlling of the discharge by modulation of energy
  • H01J37/32155—Frequency modulation
  • H01J37/32165—Plural frequencies

Definitions

• the invention relates to a method and apparatus for providing a structure on a semiconductor wafer by etching a layer over a substrate.
• a plasma etcher In semiconductor plasma etching applications, a plasma etcher is usually used to transfer a mask pattern into a circuit and line pattern of a desired thin film and/or filmstack (conductors or dielectric insulators) on a wafer. This is achieved by etching away the films (and f ⁇ lmstacks) underneath the mask materials in the opened areas of the mask pattern. This etching reaction may be initiated by the chemically active species and electrically charged particles (ions) generated by generating a plasma from a reactant mixture contained in a vacuum enclosure also referred to as a reactor or process chamber.
• a vacuum enclosure also referred to as a reactor or process chamber.
• the ions may be also accelerated towards the wafer materials through an electric field created between the gas mixture and the wafer materials, generating a directional removal of the etching materials along the direction of the ion trajectory in a manner referred to as anisotropic etching.
• the masking materials may be removed by stripping them away, leaving in its place a replica of the lateral pattern of the original intended mask patterns.
• an apparatus for providing a plasma etch of a layer over a wafer is provided.
• a capacitively coupled process chamber is provided.
• a gas source is in fluid connection with the capacitively coupled process chamber.
• a first electrode is provided within the process chamber.
• a second electrode is spaced apart and opposite from the first electrode.
• a first radio frequency power source is electrically connected to at least one of the first and second electrodes, where the first radio frequency power source provides radio frequency power of between 150 kHz and 10 MHz.
• a second radio frequency power source is electrically connected to at least one of the first and second electrodes, wherein the second radio frequency power source provides a radio frequency power of between 12 MHz and 200 MHz.
• a first modulation control is connected to the first radio frequency power source, to provide a controlled modulation of the first radio frequency power source at a frequency of between 1 kHz to 100 kHz.
• an apparatus for providing a plasma etch of a layer over a wafer is provided.
• a capacitively coupled process chamber is provided.
• a gas source is in fluid connection with the capacitively coupled process chamber.
• a first electrode is provided within the process chamber.
• a second electrode is spaced apart and opposite from the first electrode, where the second electrode is spaced apart from the first electrode forming a gap, and where the wafer is mountable between the first and second electrodes and wherein an aspect ratio of a wafer diameter to gap size is between 6: 1 to 60: 1.
• a first radio frequency power source for providing a power signal at a first frequency is electrically connected to at least one of the first and second electrodes.
• a second radio frequency power source for providing a power signal at a second frequency is electrically connected to at least one of the first and second electrodes, where the first frequency is different than the second frequency.
• a first modulation control is connected to the first radio frequency power source, to provide a controlled modulation of the first radio frequency power source at a frequency of between 1 kHz to 100 kHz.
• a second modulation control is connected to the second radio frequency power source, to provide a controlled modulation of the second radio frequency power source at a frequency of between about 1 kHz to about 100 kHz.
• FIG. 1 is a schematic view of a capacitively coupled process chamber that may be used in the preferred embodiment of the invention.
• FIG. 2 is a flow chart of a process that may use a preferred embodiment of the invention.
• FIG. 3 is a graph of concentration ratios of F + over CF 2 + versus modulation frequency.
• F + may tend to etch the photoresist. Therefore to increase etch selectivity, it maybe desirable to dissociate C F 8 to yield more CF 2 + and less F + . Therefore, it would be desirable to be able to control the ratio of resulting species generated in a plasma.
• FIG. 1 is a schematic view of a capacitively coupled process chamber 100 that maybe used in the preferred embodiment of the invention, hi this embodiment, the plasma processing chamber 100 comprises confinement rings 102, an upper electrode 104, a lower electrode 108, a gas source 110, and an exhaust pump 120.
• the substrate wafer 180 is positioned upon the lower electrode 108.
• the lower electrode 108 incorporates a suitable substrate chucking mechanism (e.g., electrostatic, mechanical clamping, or the like) for holding the substrate wafer 180.
• a process chamber top 128 incorporates the upper electrode 104 disposed immediately opposite the lower electrode 108.
• the upper electrode 104, lower electrode 108, and confinement rings 102 define the confined plasma volume 140. Gas is supplied to the confined plasma volume by gas source 110 through a gas inlet 143 and is exhausted from the confined plasma volume through the confinement rings 102 and an exhaust port by the exhaust pump 120.
• the exhaust pump 120 forms a gas outlet for the plasma processing chamber.
• a first RF source 144 and a second RF source 148 are electrically connected to the lower electrode 108.
• the first RF source 144 provides a radio frequency power with a frequency between 150 kHz to 10 MHz. Preferably, this frequency is about 2 MHz.
• the second RF source 148 provides a radio frequency power with a frequency between 12 MHz and 200 MHz. Preferably, this frequency is about 27 MHz. Preferably, the frequency from the second RF source 148 is at least ten times the frequency from the first RF source 144.
• a first pulse modulator 133 is controllable connected to the first RF source 144. The first pulse modulator 133 is able to modulate the first RF source signal at frequencies between 1 kHz to 100 kHz.
• a second pulse modulator 135 is controllably connected to the second RF source 148.
• the second pulse modulator 135 is able to modulate the second RF source signal at frequencies between 1 kHz to 100 kHz.
• the upper electrode 104 is grounded.
• a controller 137 may be controllably connected to the first pulse modulator 133, the second pulse modulator 135, the exhaust pump 120, and the gas source 110.
• the controller 137 may also be controllably connected with other devices, such as the first and second RF sources 144, 148.
• Chamber walls 152 define a plasma enclosure in which the confinement rings 102, the upper electrode 104, and the lower electrode 108 are disposed.
• the gap between the upper and lower electrodes 104, 108 is about 2 cm. Therefore, in this embodiment the aspect ratio between the diameter of the wafer 180 to be processed, which is about the diameter of the lower electrode 108, to the distance between the upper electrode and the lower electrode is 300 mm : 2 cm, which is, 15:1.
• the aspect ratio between the diameter of the wafer to be processed and the electrode gap is between 6:1 to 60:1. More preferably, the aspect ratio is between 10:1 to 40:1.
• this process chamber has an extremely narrow gap between electrodes. Such aspect ratios use gaps that allow a sheath to be a substantial fraction of the bulk plasma.
• the gap between the upper electrode and lower electrode is less than 8 cm. More preferably, the gap between the upper electrode and the lower electrode is between about 0.5 and 4 cm. Most preferably, the gap between the upper electrode and lower electrode is about 2 cm.
• FIG. 2 is a flow chart of a process that may use a preferred embodiment of the invention, hi operation, a wafer 180 with a patterned mask is placed in the process chamber 100 (step 204).
• the wafer 180 is supported by the lower electrode 108.
• An etchant gas mixture is provided by the gas source 110 into the plasma volume 140 (step 206).
• an etchant gas chemistry of Argon, C 4 F 8 , oxygen, and other component gases may be used for etching a dielectric layer over the wafer and under a photoresist mask.
• Modulated first and second RF powers are then provided (step 208) to create and sustain a plasma formed from the etchant gas.
• the plasma is used to etch the layer under the mask (step 210).
• modulation of the RF power in a capacitively coupled process chamber causes a change in the sheath of the plasma.
• Such a change in some systems may only affect a small portion of the plasma volume.
• the inventive process chamber has a thin plasma volume, defined by a thin electrode gap and high aspect ratio, so that the sheath that is affected by the modulation forms a significant part of the plasma volume.
• the modulation may be used to independently control species dissociation and loss to generation ratios for a significant part of the plasma volume.
• FIG. 3 is a graph of concentration ratios of F + over CF 2 + versus modulation frequency of the higher frequency RF source.
• the graph schematically shows that as the modulation frequency increases the ratio of F + to CF 2 + decreases and that modulation frequency may be used to control the ratio. This is an example of how the invention may be used to control the dissociation ratios of gases in a significant portion of the plasma volume.
• the plasma loss to generation ratio is dependent on various factors, such as the number of ions and electrons and their energies. Modulation may be used to change these various factors. As discussed above, such modulation may mainly affect the sheath region. Since the invention provides a sheath region that is a significant part of the volume, the modulation maybe used to affect a significant volume of the plasma.
• a change in balance is known to alter plasma parameters such as electron temperature (and thereby the plasma species fragmentation/dissociation).
• the invention also provides an added control that may be used to tailor an etch according to the type of etch. For example, in etching a high aspect ratio contact, a lot of sheath is desired, to provide higher energy ions for etching.
• the pulse modulators would have a modulation frequency favoring a high sheath potential, even allowing for increased instantaneous lower frequency power during the pulse-on than would be achievable during continuous- wave operation. If instead a trench is to be etched in a low-k dielectric, ion bombardment should be reduced and therefore the sheath should be reduced. This may be accomplished by modulating the lower frequency that typically controls the wafer sheath, allowing further fine tuning of low ion energies.
• Modulation may also used to change the percentage of the volume affected by the sheath. Therefore, the invention is able to provide an extra control, for controlling etch bias, sheath, and dissociation chemistry.
• the controller is able to cause the modulation of the RF power sources to be synchronized or to be modulated independently of each other.
• other RF power source and electrode arrangements may be used.
• another embodiment may connect the first and second RF sources to the upper electrode.
• etching benefits may be found from the inventive apparatus that has a narrow plasma volume and allows the modulation of dual RF sources.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• Plasma & Fusion (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Computer Hardware Design (AREA)
• General Physics & Mathematics (AREA)
• Manufacturing & Machinery (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Plasma Technology (AREA)
• Drying Of Semiconductors (AREA)
• Apparatus For Radiation Diagnosis (AREA)
• Magnetic Resonance Imaging Apparatus (AREA)
• ing And Chemical Polishing (AREA)

Priority Applications (6)

Applications Claiming Priority (2)

Publications (2)

Family

ID=33416370

Family Applications (1)

Country Status (9)

Cited By (2)

Families Citing this family (39)

Family Cites Families (41)

• 2003
  • 2003-05-06 US US10/431,030 patent/US7976673B2/en not_active Expired - Fee Related
• 2004
  • 2004-04-29 KR KR1020057021083A patent/KR20060013386A/ko not_active Ceased
  • 2004-04-29 EP EP04751199A patent/EP1620876B1/en not_active Expired - Lifetime
  • 2004-04-29 WO PCT/US2004/013707 patent/WO2004102638A2/en not_active Ceased
  • 2004-04-29 DE DE602004027620T patent/DE602004027620D1/de not_active Expired - Lifetime
  • 2004-04-29 CN CN2004800191395A patent/CN1816893B/zh not_active Expired - Fee Related
  • 2004-04-29 AT AT04751199T patent/ATE470949T1/de not_active IP Right Cessation
  • 2004-04-29 KR KR1020127020117A patent/KR101303969B1/ko not_active Expired - Fee Related
  • 2004-04-29 JP JP2006532543A patent/JP4794449B2/ja not_active Expired - Fee Related
  • 2004-05-04 TW TW093112507A patent/TWI460784B/zh not_active IP Right Cessation
• 2011
  • 2011-07-07 US US13/177,627 patent/US8337713B2/en not_active Expired - Fee Related

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