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
  • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
  • H01L21/67005—Apparatus not specifically provided for elsewhere
  • H01L21/67011—Apparatus for manufacture or treatment
  • H01L21/67017—Apparatus for fluid treatment
  • H01L21/67028—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like
  • H01L21/6704—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing
  • H01L21/67051—Apparatus for fluid treatment for cleaning followed by drying, rinsing, stripping, blasting or the like for wet cleaning or washing using mainly spraying means, e.g. nozzles
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
  • B08B3/02—Cleaning by the force of jets or sprays
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B3/00—Cleaning by methods involving the use or presence of liquid or steam
  • B08B3/02—Cleaning by the force of jets or sprays
  • B08B3/024—Cleaning by means of spray elements moving over the surface to be cleaned
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B08—CLEANING
  • B08B—CLEANING IN GENERAL; PREVENTION OF FOULING IN GENERAL
  • B08B5/00—Cleaning by methods involving the use of air flow or gas flow
  • B08B5/02—Cleaning by the force of jets, e.g. blowing-out cavities
• • C—CHEMISTRY; METALLURGY
  • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
  • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
  • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
  • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
  • C23C16/4401—Means for minimising impurities, e.g. dust, moisture or residual gas, in the reaction chamber
  • C23C16/4407—Cleaning of reactor or reactor parts by using wet or mechanical methods

Definitions

• the present disclosure relates generally to semiconductor manufacturing equipment and, more particularly, to a technique for reducing backside particles.
• microelectronic products such as microprocessors, integrated circuits (ICs) and other micro- devices
• ICs integrated circuits
• Such a clean environment is typically provided by housing semiconductor manufacturing equipment inside clean- rooms and by controlling contamination inside the equipment.
• contaminant particles may originate from the ESC itself due to normal wear.
• contaminant particles may be transferred to the ESC from other US2005/044987 of the automatic wafer handling system such as pick arm pads, orienter pads, pass-through cassettes, and buffer robot end effectors. These contaminant particles may be transferred to the semiconductor wafers, typically on the backside. Hence, these contaminant particles are often referred to as backside particles (BSP' s) .
• BSP' s backside particles
• a technique for reducing backside particles is disclosed.
• the technique may be realized as an apparatus for reducing backside particles.
• the apparatus may comprise a delivery mechanism configured to supply a cleaning substance to a platen, wherein the platen is housed in a process chamber.
• the apparatus may also comprise a control unit configured to cause the process chamber to reach a first pressure level, cause the cleaning substance to be supplied to a surface of the platen, and cause the process chamber to reach a second pressure level, thereby removing contaminant particles, together with the cleaning substance, from the surface of the platen.
• the establishment of the second pressure level in the process chamber may cause at least a portion of the cleaning substance to sublimate, thereby removing the contaminant particles from the surface of the platen.
• the platen may be an electrostatic clamp having a composite surface coating.
• the apparatus may comprise a wafer handling mechanism that transfers a clean wafer onto and then from the platen, thereby removing contaminant particles from the surface of the platen.
• the delivery mechanism may comprise a nozzle and a drive assembly.
• the drive assembly may be configured to position the nozzle proximate to the surface of p(I I!' .. •• 'Ij itiQIi"ftiq; ,.• • ⁇ the' pTat l eW "ftild unit may be configured to cause the nozzle to spray the surface of the platen with the cleaning substance.
• the nozzle may be an articulated nozzle. The nozzle may be positioned approximately six inches above the surface of the platen.
• control unit may be capable of causing the drive assembly to sweep the nozzle across the surface of the platen, thereby applying a substantially uniform coating of the cleaning substance to the surface.
• control unit may be capable of causing the drive assembly to move the platen in a sweeping motion relative to the nozzle, thereby applying a substantially uniform coating of the cleaning substance to the surface.
• the delivery mechanism may comprise a flat member that is positioned above the surface of the platen at such a small distance that the space between the flat member and the surface of the platen causes the cleaning substance to be spread across the surface.
• the cleaning substance comprises one or more substances selected from a list consisting of: DI water, alcohol, carbon dioxide, ionized dry air, and ionized dry nitrogen.
• the technique may be realized as a method for reducing backside particles. The method may comprise the step of positioning a platen inside a process chamber. The method may also comprise the step of venting the process chamber to a first pressure level.
• the method may further comprise the step of supplying a cleaning substance to a surface of the platen.
• the method may additionally comprise the step of pumping the process chamber to a second pressure level, thereby removing contaminant particles, together with the cleaning substance, from the sPurCfaTce/UofSt Q heSp/laiten.
• the pumping of the process chamber may cause at least a portion of the cleaning substance to sublimate, thereby removing the contaminant particles from the surface of the platen.
• the platen may be an electrostatic clamp having a composite surface coating.
• the method may further comprise the step of spraying the cleaning substance onto the surface of the platen in a sweeping pattern, thereby applying a substantially uniform coating of the cleaning substance on the surface.
• the cleaning substance may comprise deionized water, and a mist of the deionized water may be sprayed onto the surface of the platen to coat the surface with droplets of the deionized water.
• the cleaning substance may comprise carbon dioxide, and the surface of the platen may be sprayed with a snow of the carbon dioxide, the snow comprising solid carbon dioxide particles.
• the cleaning substance may comprise an ionized gas, and the surface of the platen may be sprayed with the ionized gas.
• Figure 1 shows a block diagram illustrating an exemplary system for reducing backside particles in accordance with an embodiment of the present disclosure.
• Figure 2 shows a block diagram illustrating another exemplary system for reducing backside particles in accordance with an embodiment of the present disclosure.
• Figure 3 shows a flow chart illustrating an exemplary method for reducing backside particles from an electrostatic clamp in accordance with an embodiment of the present disclosure .
• Figure 4 shows a block diagram illustrating an exemplary system for reducing backside particles in accordance with an embodiment of the present disclosure.
• Figure 5 shows a block diagram illustrating another exemplary system for reducing backside particles in accordance with an embodiment of the present disclosure.
• embodiments of the present disclosure introduce an in situ cleaning technique that effectively reduces backside particles transferred to semiconductor wafers.
• One or more cleaning substances may be supplied to a surface of a platen (or other components) located inside a process chamber. When the process chamber is pumped down, the cleaning substance (s) may be removed from the platen (or component) surface, together with contaminant particles thereon.
• the following description will focus on the cleaning of a platen. However, it should be appreciated that the exemplary embodiments described herein may be easily adapted to clean other components in semiconductor manufacturing equipment.
• the system 100 may comprise a process chamber 102 that is coupled to, for example, a turbo pump 120 and a mechanical pump 122.
• the vacuum pumps (120 and 122), individually or in combination, may cause the process chamber 102 to reach a desired vacuum level.
• the process chamber 102 may be part of semiconductor manufacturing equipment, and may serve one or more semiconductor processing functions such as, for example, chemical vapor deposition (CVD) , physical vapor deposition (PVD), ion implantation, or plasma etching.
• CVD chemical vapor deposition
• PVD physical vapor deposition
• ion implantation ion implantation
• plasma etching plasma etching
• a platen 104 capable of holding one or more wafers may be housed inside the process chamber 102.
• the platen 104 may be part of an automatic wafer handling assembly that is capable of transferring wafers to or from an adjacent chamber (not shown) .
• the platen 104 may comprise an electrostatic clamp which typically may have a composite surface coating, although it should be understood that a non-electrostatic clamp with or without a composite surface coating may be used as well.
• the system 100 may also comprise a control unit 106 which may facilitate control over a number of other components of the system 100.
• the system 100 may further comprise a drive a!3sfer ⁇ ily ⁇ . : ⁇ ⁇ y lJ w ⁇ c ⁇ t -LS*?crf ⁇ trolled by the control unit 106 and coupled to a spray arm 110.
• a spray arm 110 At the end of the spray arm 110, there may be a nozzle 112.
• a source 114 of a cleaning substance may be coupled to the spray arm 110 via a pipeline 116, and the cleaning substance may be delivered through the spray arm 110 to the nozzle 112, which may be articulated.
• the cleaning substance source 114 may contain one or more cleaning substances typically in either liquid or gaseous states .
• a preferred cleaning substance should be a gas or fluid that is readily available and easy to store or handle in a clean-room.
• a preferred cleaning substance can also be delivered in small amounts and its residual vapor can be easily removed from a vacuum chamber.
• Typical cleaning substances may include but are not limited to: DI water, alcohol, carbon dioxide (e.g., CO 2 snow with solid CO 2 particles), ionized dry air, or ionized dry nitrogen, etc.
• the ionized dry air or nitrogen may be particularly effective in removing those particles that are held to the platen surface by electrostatic forces.
• ionized gases may be produced, for example, from an AirForceTM Ionizing Blow-Off Gun available from Ion Systems, Inc.
• a mixture of DI water and alcohol may be delivered through the spray arm 110 to the nozzle 112.
• Such a combination of two or more cleaning substances may also be referred to as one cleaning substance (i.e., in singular form) .
• the spray arm 110 may be a telescopic type as shown in Figure 1, or it may be any other type of assembly that can be driven by the drive assembly 108 and controlled by the control unit 106.
• the nozzle 112 Through movements of the spray arm 110, the nozzle 112, which may be articulated, may be positioned in a desired location relative to a surface of the platen 104.
• IP H Ii' / 1 B jpc fj i ⁇ / ILj ⁇ tj ⁇ U Rj '7 t ⁇ h4" 11" no l zz ⁇ e J rl2 1 ' > is"p(bsiri 1 bned proximate to and above the platen
• the nozzle 112 may be approximately six inches above the platen 104.
• the nozzle 112 may be capable of spraying out a controlled stream or mist of gases, liquids, or solid particles. That is, flow rates of the cleaning substance through the nozzle 112, as well as spray density, may be controlled, for example, by the control unit 106.
• the spray arm 110 and the nozzle 112 may also be adjusted to provide desired angles of incidence on the surface of the platen 104. When spraying, the nozzle 112 may remain stationary. Alternatively, the spray arm 110 may move the nozzle 112 in predetermined patterns, single- or multi-dimensionally, across the surface of the platen 104. Through controlled movement of the nozzle 112, as well as regulated flow rate and spray density, the surface of the platen 104 may be spray-coated with selected cleaning substance (s) .
• the process chamber 102 may be vented to approximately atmospheric pressure (or a pressure level in the rough vacuum regime depending upon the cleaning substance's thermodynamic properties as well as conditions such as vacuum pumping flow rate, pump down time, and temperature, etc.) and the platen 104 may be placed in a safe position.
• the control unit 106 may, either automatically or while operated by a human operator, cause the nozzle 112 to be positioned above the platen 104 and to spray a selected cleaning substance onto the platen surface. Then, the process chamber 102 may be pumped down to a desired vacuum level (e.g., rough vacuum, or high vacuum at 10 ⁇ 7 -10 ⁇ 6 Torr) .
• the cleaning substance sublimates (i.e., leaving the surface of the platen 104 in vapor)
• contaminant particles on the platen surface may be removed, either out of the process chamber 102 or onto the chamber floor.
• the platen 104 (and/or the pro'ces ⁇ be optionally gettered with a clean wafer having a low particle count.
• the clean wafer may be briefly transferred to the platen 104 and then returned to a cassette, which process may be repeated to further reduce contaminant particles from the platen surface.
• the drive assembly 108, spray arm 110, nozzle 112, cleaning substance source 114, and pipeline 116 may be collectively referred to as a "delivery mechanism.”
• delivery mechanism There may be great flexibility as to where the delivery mechanism is mounted relative to the process chamber 102. As shown in Figure 1, a good portion of the delivery mechanism (including the spray arm 110) and the control unit 106 may be externally mounted.
• the spray arm 110 may be configured to enter the process chamber 102 via a sealed pass-through or cut-out that is sufficient for the movement of the spray arm 110. Alternatively, at least a portion of the delivery mechanism may be mounted inside the process chamber, one example of which is shown in Figure 2.
• Figure 2 shows a block diagram illustrating an exemplary system 200 for reducing backside particles in accordance with an embodiment of the present disclosure.
• the system 200 similarly comprises a process chamber 202 that is coupled to a turbo pump 220 and a mechanical pump 222.
• a platen 204 may be housed inside the process chamber 202.
• the system 200 may also comprise a control unit 206 and a drive assembly 208 coupled to a nozzle 212, which may be articulated, via a spray arm 210.
• the drive assembly 208 of the system 200 is mounted inside the process chamber 202, in a corner of the process chamber 202 or another unobtrusive location.
• a source 214 of a cleaning substance may be coupled to the spray arm 210 via a feed- through or cut-out 216 in a wall of the process chamber 202. Since the control unit 206 is externally mounted, the feed- through or cut-out 216 may also accommodate electrical control lines from the control unit 206 to the drive assembly 208.
• Figure 3 shows a flow chart illustrating an exemplary method for reducing backside particles from an electrostatic clamp in accordance with an embodiment of the present disclosure.
• the ESC platen may be inside a process chamber or a similar vacuum chamber.
• the exemplary method steps may be performed before a semiconductor processing job starts in the process chamber, after a job finishes, in between different jobs, or at any other time as desired. Also, these method steps may be repeated to reach a desired cleaning result.
• the ESC platen may, for example, be secured in a "safe" position. It should be understood to those skilled in the art that the platen may be secured in other positions as well.
• the process chamber may be vented to approximately atmospheric pressure.
• a spray nozzle may be positioned above the ESC platen.
• the spray nozzle may be adjusted to provide a fine mist. Adjustment of the spray nozzle flow rate and spray density may typically depend on properties of a cleaning substance to be sprayed, as well as the expected interaction between the ESC platen surface and the cleaning substance.
• the nozzle may spray a mist of DI water onto the ESC platen surface. While spraying, the nozzle may be moved in a sweeping motion across the ESC platen surface in order for the DI water droplets to cover the surface uniformly.
• the spray nozzle which may or may not be articulated, may be in a fixed position, and the platen may move in a sweeping motion beneath the nozzle.
• DI water a mixture of DI water and alcohol or other solvents may be sprayed.
• ionized dry air or ionized dry nitrogen may be used to spray the platen surface.
• the nozzle may supply the cleaning substance to the ESC platen s PurCfaTce/ UeiStphers/at.H-a'Mh'ygeSnt ' Zle speed . _to coat . t . .he surface or at a relatively forceful speed to remove particles through momentum transfer. Further, the spraying of the cleaning substance does not have to fully cover the ESC platen surface. When desired or when necessary, a specified portion of the surface may be sprayed and cleaned through precision movement and/or orientation of the spray nozzle (and/or the platen) .
• a snow of carbon dioxide may also be used as a cleaning substance.
• the CO 2 snow may comprise solid CO 2 particles that can effectively blast contaminant particles off the ESC platen surface or remove particles through other surface interactions.
• the CO 2 snow may be created from the conversion of liquid CO 2 to solid CO 2 and CO 2 gas.
• the liquid CO 2 may be delivered to the spray nozzle via a high purity pipeline. Within the spray nozzle, the CO 2 liquid may expand through an orifice and be transformed into a mixture of solid CO 2 particles and CO 2 gas. This mixture may then be directed at the ESC platen surface for cleaning purposes .
• the process chamber may be pumped down to a desired vacuum level. Pumping gases from the process chamber helps remove residue of the cleaning substance to carry away contaminant particles from the ESC platen surface.
• the ESC platen may be optionally gettered with a clean wafer to further reduce its particle count.
• the above-described cleaning method may significantly reduce the presence of contaminant particles from an ESC platen.
• a 200mm ESC with a composite surface coating had a particle count of approximately 24,933 prior to cleaning. After the 200mm ESC was cleaned using a DI water mist spray as described above, the particle count was reduced to approximately 11,374, a reduction of over 50%.
• a 300mm ESC was found to have a particle count of 8afZte. r being manually cleaned with a semiconductor wipe. However, after the same 300mm ESC was cleaned with a DI water mist spray, only about 2,816 particles remained, which realized a particle reduction of ⁇ 70% compared with the conventional cleaning process.
• FIG. 4 shows a block diagram illustrating an exemplary system 400 for reducing backside particles with this alternative approach.
• the system 400 may comprise a process chamber 404 coupled to a turbo pump 420 and a mechanical pump 422.
• a platen 404 may be housed inside the process chamber 402.
• the platen 404 may have at least one feed-through channel 412 coupled with a matching pipeline 410.
• the feed-through channel 412 and the pipeline 410 may be part of an existing coolant delivery system (not shown) for cooling the platen 404 and any wafer thereon.
• a control unit 406 may control a supply of a cleaning substance (s) from a source 414 of a cleaning substance (s) , via pipelines 416 and 410 and through the feed-through channel 412, to the surface of the platen 404.
• a flat member 408 may be positioned proximately above the surface of the platen 404 prior to the flowing of the cleaning substance.
• the flat member 408 may have a bottom surface that is substantially flat or otherwise comparable to the surface of the platen 404.
• the flat member 408 may be a semiconductor wafer or a similarly shaped object.
• the flat member 408 may be positioned at such as a small distance (e.g., 0.02-0.5 mm) IrSm ⁇ thJ' ⁇ pla ' -IIVI ⁇ i ⁇ tlial'" 1 a small gap 411 may be formed between the bottom surface of the flat member 408 and the surface of the platen 404.
• the small gap 411 may help spread the cleaning substance across the surface of the platen 404 and thus improve surface interaction. Gas channels in the platen surface will facilitate an even distribution of the cleaning substance.
• the process chamber 402 may be pumped down to a desired vacuum level to facilitate the removal of the cleaning substance together with contaminant particles from the platen 404.
• FIG. 5 shows a block diagram illustrating an exemplary system 500 for reducing backside particles in which an add-on subsystem 50 may be incorporated with an existing gas cooling and ballast system.
• a platen 502 may be mounted on a tilt/rotate assembly 506.
• the gas cooling and ballast system may comprise a ballast tank 520, a gas system 522, a ballast valve 516, an air bearing 512, a pipeline 510, a gas cooling valve 508, and a feed-through channel 504, which, together, serve to cool the semiconductor wafer.
• the add-on subsystem 50 may comprise one or more sources of a cleaning substance (s) (e.g., Cleaning Substance 1, Cleaning Substance 2, and Cleaning Substance 3) . These cleaning substance sources may be coupled to a two-way valve 514 via on/off valves 518 and pipelines 517.
• the add-on subsystem 50 may take advantage of the existing setup for gas cooling.
• the add-on subsystem 50 may further comprise a control unit 515 that may be coupled to a control module (not shown) for the gas cooling system.
• the control unit 515 may regulate the valves 514 and 518 in the as values 508 and 516# thereby controlling the flow of either cleaning substances or cooling gases to the platen 502.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• General Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• Computer Hardware Design (AREA)
• Microelectronics & Electronic Packaging (AREA)
• Power Engineering (AREA)
• Condensed Matter Physics & Semiconductors (AREA)
• General Physics & Mathematics (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Cleaning Or Drying Semiconductors (AREA)
• Devices For Medical Bathing And Washing (AREA)

Priority Applications (1)

Applications Claiming Priority (4)

Publications (2)

Family

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Family Applications (1)

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• 2005
  • 2005-09-30 US US11/239,000 patent/US20060124155A1/en not_active Abandoned
  • 2005-12-13 KR KR1020077015884A patent/KR20070095943A/ko not_active Withdrawn
  • 2005-12-13 TW TW094144120A patent/TW200633036A/zh unknown
  • 2005-12-13 JP JP2007545713A patent/JP2008523632A/ja active Pending
  • 2005-12-13 WO PCT/US2005/044987 patent/WO2006065778A2/en not_active Ceased

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