US20090269231A1 - Method of Pumping Gas - Google Patents
Method of Pumping Gas Download PDFInfo
- Publication number
- US20090269231A1 US20090269231A1 US11/992,454 US99245406A US2009269231A1 US 20090269231 A1 US20090269231 A1 US 20090269231A1 US 99245406 A US99245406 A US 99245406A US 2009269231 A1 US2009269231 A1 US 2009269231A1
- Authority
- US
- United States
- Prior art keywords
- gas
- stage
- pump
- slm
- purge gas
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 238000005086 pumping Methods 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 38
- 238000010926 purge Methods 0.000 claims abstract description 77
- 238000011144 upstream manufacturing Methods 0.000 claims abstract description 17
- 230000005494 condensation Effects 0.000 claims abstract description 12
- 238000009833 condensation Methods 0.000 claims abstract description 12
- 238000013508 migration Methods 0.000 claims abstract description 10
- 230000005012 migration Effects 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 176
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 22
- 229910052757 nitrogen Inorganic materials 0.000 claims description 11
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 22
- 239000001257 hydrogen Substances 0.000 description 13
- 229910052739 hydrogen Inorganic materials 0.000 description 13
- 230000008569 process Effects 0.000 description 12
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 11
- 229910052698 phosphorus Inorganic materials 0.000 description 8
- 239000011574 phosphorus Substances 0.000 description 8
- 238000005137 deposition process Methods 0.000 description 6
- 239000004065 semiconductor Substances 0.000 description 6
- 238000000151 deposition Methods 0.000 description 5
- 239000007787 solid Substances 0.000 description 5
- 239000000758 substrate Substances 0.000 description 5
- NLXLAEXVIDQMFP-UHFFFAOYSA-N Ammonia chloride Chemical compound [NH4+].[Cl-] NLXLAEXVIDQMFP-UHFFFAOYSA-N 0.000 description 4
- XYFCBTPGUUZFHI-UHFFFAOYSA-N Phosphine Chemical compound P XYFCBTPGUUZFHI-UHFFFAOYSA-N 0.000 description 4
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 4
- 239000006227 byproduct Substances 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 238000007906 compression Methods 0.000 description 4
- 230000008021 deposition Effects 0.000 description 4
- 238000002474 experimental method Methods 0.000 description 4
- 229910052710 silicon Inorganic materials 0.000 description 4
- 239000010703 silicon Substances 0.000 description 4
- 239000010409 thin film Substances 0.000 description 4
- 238000005229 chemical vapour deposition Methods 0.000 description 3
- 230000006835 compression Effects 0.000 description 3
- 150000002431 hydrogen Chemical class 0.000 description 3
- 230000002401 inhibitory effect Effects 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 230000007246 mechanism Effects 0.000 description 3
- 235000019270 ammonium chloride Nutrition 0.000 description 2
- 238000006243 chemical reaction Methods 0.000 description 2
- KOPOQZFJUQMUML-UHFFFAOYSA-N chlorosilane Chemical class Cl[SiH3] KOPOQZFJUQMUML-UHFFFAOYSA-N 0.000 description 2
- 210000000078 claw Anatomy 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 238000002488 metal-organic chemical vapour deposition Methods 0.000 description 2
- 125000002524 organometallic group Chemical group 0.000 description 2
- 229910000073 phosphorus hydride Inorganic materials 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- -1 polysiloxanes Polymers 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- XCZXGTMEAKBVPV-UHFFFAOYSA-N trimethylgallium Chemical compound C[Ga](C)C XCZXGTMEAKBVPV-UHFFFAOYSA-N 0.000 description 2
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- ZAMOUSCENKQFHK-UHFFFAOYSA-N Chlorine atom Chemical compound [Cl] ZAMOUSCENKQFHK-UHFFFAOYSA-N 0.000 description 1
- 239000005046 Chlorosilane Substances 0.000 description 1
- GYHNNYVSQQEPJS-UHFFFAOYSA-N Gallium Chemical compound [Ga] GYHNNYVSQQEPJS-UHFFFAOYSA-N 0.000 description 1
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 1
- BLRPTPMANUNPDV-UHFFFAOYSA-N Silane Chemical compound [SiH4] BLRPTPMANUNPDV-UHFFFAOYSA-N 0.000 description 1
- 238000009825 accumulation Methods 0.000 description 1
- RBFQJDQYXXHULB-UHFFFAOYSA-N arsane Chemical compound [AsH3] RBFQJDQYXXHULB-UHFFFAOYSA-N 0.000 description 1
- 229910052785 arsenic Inorganic materials 0.000 description 1
- RQNWIZPPADIBDY-UHFFFAOYSA-N arsenic atom Chemical compound [As] RQNWIZPPADIBDY-UHFFFAOYSA-N 0.000 description 1
- 229910000070 arsenic hydride Inorganic materials 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 239000012159 carrier gas Substances 0.000 description 1
- 239000000460 chlorine Substances 0.000 description 1
- 229910052801 chlorine Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- MROCJMGDEKINLD-UHFFFAOYSA-N dichlorosilane Chemical compound Cl[SiH2]Cl MROCJMGDEKINLD-UHFFFAOYSA-N 0.000 description 1
- 230000009977 dual effect Effects 0.000 description 1
- 239000000428 dust Substances 0.000 description 1
- 238000004880 explosion Methods 0.000 description 1
- 239000002360 explosive Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 229910052733 gallium Inorganic materials 0.000 description 1
- 229910052732 germanium Inorganic materials 0.000 description 1
- GNPVGFCGXDBREM-UHFFFAOYSA-N germanium atom Chemical compound [Ge] GNPVGFCGXDBREM-UHFFFAOYSA-N 0.000 description 1
- 229910021478 group 5 element Inorganic materials 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 1
- 239000000696 magnetic material Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 229910021421 monocrystalline silicon Inorganic materials 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000002243 precursor Substances 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 229910000077 silane Inorganic materials 0.000 description 1
- ZDHXKXAHOVTTAH-UHFFFAOYSA-N trichlorosilane Chemical compound Cl[SiH](Cl)Cl ZDHXKXAHOVTTAH-UHFFFAOYSA-N 0.000 description 1
- 239000005052 trichlorosilane Substances 0.000 description 1
- IBEFSUTVZWZJEL-UHFFFAOYSA-N trimethylindium Chemical compound C[In](C)C IBEFSUTVZWZJEL-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C29/00—Component parts, details or accessories of pumps or pumping installations, not provided for in groups F04C18/00 - F04C28/00
- F04C29/0092—Removing solid or liquid contaminants from the gas under pumping, e.g. by filtering or deposition; Purging; Scrubbing; Cleaning
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C25/00—Adaptations of pumps for special use of pumps for elastic fluids
- F04C25/02—Adaptations of pumps for special use of pumps for elastic fluids for producing high vacuum
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
- F04C18/123—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with radially or approximately radially from the rotor body extending tooth-like elements, co-operating with recesses in the other rotor, e.g. one tooth
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C18/00—Rotary-piston pumps specially adapted for elastic fluids
- F04C18/08—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing
- F04C18/12—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type
- F04C18/126—Rotary-piston pumps specially adapted for elastic fluids of intermeshing-engagement type, i.e. with engagement of co-operating members similar to that of toothed gearing of other than internal-axis type with radially from the rotor body extending elements, not necessarily co-operating with corresponding recesses in the other rotor, e.g. lobes, Roots type
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2220/00—Application
- F04C2220/30—Use in a chemical vapor deposition [CVD] process or in a similar process
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C2280/00—Arrangements for preventing or removing deposits or corrosion
- F04C2280/02—Preventing solid deposits in pumps, e.g. in vacuum pumps with chemical vapour deposition [CVD] processes
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/001—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of similar working principle
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04C—ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; ROTARY-PISTON, OR OSCILLATING-PISTON, POSITIVE-DISPLACEMENT PUMPS
- F04C23/00—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids
- F04C23/005—Combinations of two or more pumps, each being of rotary-piston or oscillating-piston type, specially adapted for elastic fluids; Pumping installations specially adapted for elastic fluids; Multi-stage pumps specially adapted for elastic fluids of dissimilar working principle
Definitions
- the present invention relates to a method of pumping gas, and in particular to a method of pumping a gas stream comprising a light gas, such as hydrogen, and a condensable species.
- a light gas such as hydrogen
- a primary step in the fabrication of semiconductor devices is the formation of a thin film on a semiconductor substrate by chemical reaction of vapour precursors.
- One known technique for depositing a thin film on a substrate is chemical vapour deposition (CVD).
- CVD chemical vapour deposition
- process gases are supplied to a process chamber housing the substrate and react to form a thin film over the surface of the substrate.
- Group III-V compound semiconductors are generally formed using a form of CVD usually known as MOCVD (metal organic chemical vapour deposition).
- MOCVD metal organic chemical vapour deposition
- this process involves reacting together volatile organometallic sources of the required group III with group V elements supplied from hydride gases such as AsH 3 and PH 3 .
- group V elements supplied from hydride gases such as AsH 3 and PH 3 .
- a thin film of GaInP may be formed on a suitable substrate material by supplying to a process chamber trimethyl gallium ((CH 3 ) 3 Ga) as the source of gallium, trimethyl indium ((CH 3 ) 3 In) as the source of indium, and phosphine (PH 3 ) as the source of phosphorus.
- Hydrogen gas is generally also present, providing a carrier gas for the organometallic sources and any other process gases and to complete the reaction chemistry by mopping up dangling bonds.
- the residence time of the deposition gases in the processing chamber is relatively short, and only a small proportion of the gas supplied to the chamber is consumed during the deposition process. Consequently, much of the deposition gases supplied to the chamber is exhausted from the chamber together with by-products from the deposition process.
- the unconsumed process gas or by-product is condensable, condensation on lower temperature surfaces can result in the accumulation of powder or dust within a vacuum pump used to draw the exhaust gases from the process chamber.
- the gas exhaust from the chamber will typically include relatively large amounts of hydrogen, phosphine. and phosphorus vapour, and so there is a risk that the phosphorus vapour may condense as solid phosphorus within the pump and, over time, effectively fill the vacant running clearance between the rotor and stator elements of the pump, leading to a loss of pumping performance and ultimately pump failure.
- Epitaxial deposition processes are increasingly used for high-speed semiconductor devices, both for silicon and compound semiconductor applications.
- An epitaxial layer is a carefully grown, single crystal silicon film.
- Epitaxial deposition utilizes a silicon source gas, typically silane or one of the chlorosilane compounds, such as trichlorosilane or dichlorosilane, in a hydrogen atmosphere at high temperature, typically around 800-1100° C., and under a vacuum condition.
- Epitaxial deposition processes are often doped with small amounts of boron, phosphorus, germanium, arsenic, or carbon, as required, for the device being fabricated.
- Hydrogen chloride may also be used to clean the chamber between deposition runs.
- By-products of the epitaxial process tend to be compounds of silicon and chlorine, or compounds of silicon and hydrogen. These by-products may include chlorosilane polymers of the form Si x Cl y H z . These polymers can be converted to self-ignitable or explosive materials, for example polysiloxanes, if exposed to moisture contained in the atmosphere.
- a light gas such as hydrogen
- condensable species such as phosphorus vapour or polymeric vapours.
- the present invention provides a method of pumping a gas stream containing a condensable species and a light gas, the method comprising the steps of conveying the gas stream to a multistage vacuum pump comprising an inlet stage and an exhaust stage downstream from the inlet stage, and adding to the gas stream upstream of or at the inlet stage a purge gas heavier than the light gas to both inhibit migration of the light gas from the exhaust stage towards the inlet stage and to inhibit condensation of the condensable species within the pump.
- the introduction of the purge gas into the gas stream also serves to reduce the partial pressure of condensable species, such as phosphorus vapour, ammonium chloride or polymeric vapours.
- condensable species such as phosphorus vapour, ammonium chloride or polymeric vapours.
- the purge gas is compressed with the gas stream as it passes through the pump from the inlet stage to the exhaust stage, generating heat.
- the additional heat generated by the compression of the purge gas serves to increase the temperature of the gas stream as it passes through the pump which, coupled with the reduction in partial pressure of the condensable species due to the presence of the purge gas, serves to inhibit condensation of the condensable species within the pump without the need to provide any external heating systems.
- the pump preferably has a relatively high volume ratio, that is, the ratio between the volume of the inlet stage of the pump and the volume of the exhaust stage of the pump is relatively high.
- the exhaust stage may have a volume at least three times smaller than that of the inlet stage, more preferably a volume at least five times smaller than that of the inlet stage.
- the present invention provides a method of pumping a gas stream containing a condensable species and a light gas having a flow rate of at least 20 slm, the method comprising the steps of conveying the gas stream to a multistage vacuum pump comprising an inlet stage and an exhaust stage having a volume at least three times smaller than the inlet stage, and adding to the gas stream upstream of or at the inlet stage a purge gas heavier than said light gas at a rate of at least 10 slm.
- the purge gas is preferably added to the gas stream at a rate of at least 20 slm.
- purge gas may also supplied to the pump between stages of the pump.
- purge gas may be supplied between the third stage and the fourth stage of the pump, and/or between the fourth stage and the fifth (exhaust) stage of the pump without condensation of condensable species within the pump.
- the further purge gas is preferably supplied at a flow rate of at least 20 slm. “Splitting” the introduction of the purge gas along the pump in this manner can enable a lower pressure gas stream to be pumped.
- This invention is particularly suitable for use with a multistage vacuum pump comprising at least one, preferably a plurality of pumping stages which compress the gas stream, such as Northey (or “claw”) pumping stages.
- Northey pumping stages are essentially self-valving, in that the back-migration of gaseous species such as nitrogen towards the pump inlet is inhibited by the Northey pumping mechanism, and so the introduction of purge gas at locations between stages of the pump does not affect the pressure at the inlet of the pump.
- the present invention provides a vacuum pumping arrangement for pumping a gas stream containing a condensable species and a light gas
- the pumping arrangement comprising a multistage vacuum pump comprising an inlet stage and an exhaust stage downstream from the inlet stage, and a purge gas supply for adding to the gas stream upstream of or at the inlet stage a purge gas heavier than the light gas to both inhibit migration of the light gas from the exhaust stage towards the inlet stage and to inhibit condensation of the condensable species within the pump.
- the present invention provides a. vacuum pumping arrangement for pumping a gas stream containing a condensable species and a light gas having a flow rate of at least 20 slm, the pumping arrangement comprising a multistage vacuum pump comprising an inlet stage and an exhaust stage downstream from the inlet stage and having a volume at least three times smaller than the inlet stage, and a purge gas supply for adding to the gas stream upstream of or at the inlet stage a purge gas heavier than the light gas at a rate of at least 10 slm.
- FIG. 1 illustrates a multistage vacuum pump
- FIG. 2 illustrates the variation of the partial pressure of phosphor with temperature (i) when purge gas is supplied only to the exhaust of a multistage vacuum pump and (ii) when some of the purge gas is supplied to the inlet stage of the pump of FIG. 1 .
- a multistage vacuum pump 10 comprises a stator 12 housing a multistage rotor assembly 14 .
- the stator 12 comprises a plurality of transverse walls 16 which divide the stator 12 into a plurality of pumping chambers.
- the stator 12 is divided into five pumping stages, although the stator 12 may be divided into any number of pumping stages required to provide the pump 10 with the desired pumping capacity.
- the rotor assembly 14 comprises two intermeshing sets of rotor components 18 , 20 , 22 , 24 , 26 , each set being mounted on a respective shaft 28 , 30 .
- the rotor components may have a Roots or a Northey (or “claw” profile).
- the rotor components 18 may have a Roots profile, with the other rotor components 20 , 22 , 24 , 26 having a Northey profile.
- the sets of rotor components are preferably profiled in order to maintain a small running clearance between the faces of the rotor components and the facing surfaces of the stator 12 .
- Each shaft 28 , 30 is supported by bearings 32 , 34 for rotation relative to the stator 12 .
- the shafts 28 , 30 are mounted within the stator 12 so that each pumping chamber houses a pair of intermeshing rotor components, which together provide a stage of the pump 10 .
- a motor 36 is connected to one end of shaft 28 .
- the other shaft 30 is connected to shaft 28 by means of meshed timing gears 38 so that the shafts 28 , 30 are rotated synchronously but in opposite directions within the stator 12 .
- the gears 38 are formed from magnetic material.
- a pump inlet 40 communicates directly with the inlet pumping stage, which comprises rotor components 18 and pump exhaust 42 communicates directly with.
- the exhaust pumping stage which comprises rotor components 26 .
- Gas passageways 44 , 46 , 48 , 50 , 52 are provided within the pump 10 to permit the passage therethrough of pumped gas from the inlet 40 to the exhaust 42 .
- the volume of the pumping chambers defined within the stator 12 decreases from the inlet pumping stage, which includes rotor components 18 , to the exhaust pumping stage, which includes rotor components 26 .
- the exhaust stage may have a volume at least three times smaller than that of the inlet stage, more preferably a volume at least five times smaller than that of the inlet stage.
- the pump 10 is particularly suitable for pumping a gas stream containing a light gas, such as hydrogen, and one or more condensable species, such as phosphorus vapour, ammonium chloride or polymeric vapours, typically output from a semiconductor or flat panel process chamber.
- a purge gas supply system 60 is provided for supplying purge gas, for example, nitrogen, to the pump 10 .
- the purge gas supply system 60 comprises a manifold 62 having an inlet 64 and a plurality of outlets 66 .
- the inlet 64 is connected to a source of purge gas, typically via a conduit including a check valve and optionally a pressure regulator for controlling the pressure of a stream of purge gas conveyed to the inlet 64 .
- a source of purge gas typically via a conduit including a check valve and optionally a pressure regulator for controlling the pressure of a stream of purge gas conveyed to the inlet 64 .
- the received stream of purge gas typically passes through a mass flow transducer before being split into a plurality of streams for conveyance to the outlets 66 .
- the manifold 62 may contain an arrangement of solenoid valves, fixed flow restrictors and/or variable flow restrictors for adjusting the flow rate of each stream of purge gas supplied to an outlet 66 .
- the purge gas supply system 60 comprises a number of pipes each for conveying purge gas from a respective outlet 66 of the manifold 62 .
- One of the pipes 68 a conveys purge gas to a conduit 70 for conveying a gas stream to the inlet 40 of the pump 10 so that the purge gas mixes with the gas stream upstream of the inlet pumping stage.
- the pipe 68 a may be configured to supply purge gas to a purge port of the pump 10 so that the purge gas is supplied directly to the inlet pumping stage, or to another location upstream from the inlet pumping stage.
- a second pipe 68 b and a third pipe 68 c convey purge gas to respective purge ports 72 , 74 provided about the pump 10 .
- the purge port 72 is located between the third and fourth pumping stages of the pump 10
- the purge port 74 is located between the fourth and fifth (exhaust) pumping stages of the pump 10 .
- the pump 10 includes two purge ports, the pump 10 may be provided with any number of purge ports located at various locations about the pump 10 .
- the purge gas can perform the dual roles of (i) inhibiting migration of the light gas from the exhaust pumping stage towards the inlet pumping stage and (ii) inhibiting condensation of the condensable species within the pump 10 .
- the results of experiments to illustrate this will now be explained with reference to FIG. 2 .
- a gas stream containing 70 slm of hydrogen and 1 slm of phosphor was conveyed to a five stage Roots pump.
- a purge gas stream containing 55 slm of nitrogen was conveyed to the exhaust of this pump.
- purge gas is typically conveyed to the exhaust so that the purge gas enters the pumping mechanism through back-migration of the purge gas without causing pressure fluctuations at the pump inlet.
- the phosphor partial pressure and the temperature of the gas stream were recorded at various different locations along the pump, and at the pump inlet and pump outlet.
- Line 80 in FIG. 2 is the vapour phase equilibrium curve for phosphor, which defines the temperature and partial pressure at which phosphor will condense or sublime. Above the curve, phosphor vapour starts to condense to form as a solid. Below the line, phosphor will remain in the vapour phase.
- the purge gas when supplied to the pump exhaust, the reduction in the temperature of the gas stream typically by 10-20° C. causes the phosphor vapour to condense as phosphor, which could lead to blockage of the pump exhaust and at least the exhaust pumping stage of the pump. In this situation, external heating of the pump and/or of the purge gas would be required to inhibit phosphor condensation, undesirably increasing costs.
- the additional heat generated by this compression serves to increase the temperature of the gas stream by around 10° C. as it passes through the pump 10 , maintaining the phosphor in the vapour phase as it passes through and is exhaust from the pump 10 .
- the additional of nitrogen raises the average molecular size of the gas stream within the pump 10 , which tends to inhibit the hydrogen migration towards the inlet stage of the pump 10 and enhance the hydrogen pumping efficiency.
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Applications Or Details Of Rotary Compressors (AREA)
- Compressors, Vaccum Pumps And Other Relevant Systems (AREA)
- Chemical Vapour Deposition (AREA)
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GBGB0519742.1A GB0519742D0 (en) | 2005-09-28 | 2005-09-28 | Method of pumping gas |
| GB0519742.1 | 2005-09-28 | ||
| PCT/GB2006/003286 WO2007036689A1 (en) | 2005-09-28 | 2006-09-06 | Method of pumping gas |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| US20090269231A1 true US20090269231A1 (en) | 2009-10-29 |
Family
ID=35394887
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US11/992,454 Abandoned US20090269231A1 (en) | 2005-09-28 | 2006-09-06 | Method of Pumping Gas |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US20090269231A1 (enExample) |
| EP (1) | EP1931880A1 (enExample) |
| JP (1) | JP2009510321A (enExample) |
| KR (1) | KR20080049788A (enExample) |
| GB (1) | GB0519742D0 (enExample) |
| WO (1) | WO2007036689A1 (enExample) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100226808A1 (en) * | 2007-10-04 | 2010-09-09 | Nigel Paul Schofield | Multi stage, clam shell vacuum pump |
| WO2011077105A3 (en) * | 2009-12-24 | 2012-07-12 | Edwards Limited | Dry vacuum pump with purge gas system and method of purging |
| US20130259717A1 (en) * | 2010-12-10 | 2013-10-03 | Ateliers Busch Sa | Vacuum pump for applications in vacuum packaging machines |
| GB2535703A (en) * | 2015-02-23 | 2016-08-31 | Edwards Ltd | Gas supply apparatus |
| US20210140430A1 (en) * | 2017-06-17 | 2021-05-13 | Leybold Gmbh | Multi-stage rotary piston pump |
| US20220120279A1 (en) * | 2019-02-14 | 2022-04-21 | Pfeiffer Vacuum | Rough-vacuum pump of dry type |
| WO2023275773A1 (en) * | 2021-06-29 | 2023-01-05 | Edwards Korea Limited | Stator assembly for a roots vacuum pump |
Families Citing this family (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5481019B2 (ja) * | 2007-06-05 | 2014-04-23 | エドワーズ株式会社 | 真空ポンプ配管構造とその真空ポンプ配管の洗浄方法 |
| JP5102068B2 (ja) * | 2008-02-29 | 2012-12-19 | 株式会社荏原製作所 | 多段真空ポンプ |
| GB2500610A (en) | 2012-03-26 | 2013-10-02 | Edwards Ltd | Apparatus to supply purge gas to a multistage vacuum pump |
| GB2590663B (en) * | 2019-12-23 | 2022-06-29 | Edwards S R O | Vacuum pump |
| FR3119209B1 (fr) * | 2021-01-25 | 2023-03-31 | Pfeiffer Vacuum | Pompe à vide de type sèche et groupe de pompage |
| JP7692374B2 (ja) * | 2022-01-14 | 2025-06-13 | 三菱重工業株式会社 | 放射性物質収納容器の乾燥装置および方法 |
| GB2621854A (en) * | 2022-08-24 | 2024-02-28 | Edwards Korea Ltd | Apparatus and method for delivering purge gas to a vacuum pump |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5046934A (en) * | 1988-10-24 | 1991-09-10 | Leybold Aktiengesellschaft | Twin shaft vacuum pump with purge gas inlet |
| US5312466A (en) * | 1992-05-22 | 1994-05-17 | Alcatel Cit | Pumping installation for pumping out an enclosure containing gases which are mixed with solid particles or which generate solid condensates or particles |
| US5356275A (en) * | 1991-03-04 | 1994-10-18 | Leybold Aktiengesellschaft | Device for supplying a multi-stage dry-running vacuum pump with inert gas |
| US6471497B2 (en) * | 2000-04-26 | 2002-10-29 | Kabushiki Kaisha Toyoda Jidoshokki Seisakusho | Gas supplying device for vacuum pump |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH01177486A (ja) * | 1987-12-28 | 1989-07-13 | Ebara Corp | 真空ポンプ |
| GB8809621D0 (en) * | 1988-04-22 | 1988-05-25 | Boc Group Plc | Dry pump with closed loop filter |
| JP2733489B2 (ja) * | 1989-05-10 | 1998-03-30 | 株式会社宇野澤組鐵工所 | ガス希釈をともなう逆流冷却式多段ロータリー形真空ポンプ |
| JP3494457B2 (ja) * | 1993-07-07 | 2004-02-09 | 株式会社大阪真空機器製作所 | 真空ポンプ装置 |
| JP3079077B2 (ja) * | 1997-12-17 | 2000-08-21 | 古河電気工業株式会社 | 有機金属気相成長装置 |
| JP3758550B2 (ja) * | 2001-10-24 | 2006-03-22 | アイシン精機株式会社 | 多段真空ポンプ |
| TW200506217A (en) * | 2003-03-19 | 2005-02-16 | Ebara Corp | Positive-displacement vacuum pump |
| JP4232505B2 (ja) * | 2003-03-27 | 2009-03-04 | アイシン精機株式会社 | 真空ポンプ |
-
2005
- 2005-09-28 GB GBGB0519742.1A patent/GB0519742D0/en active Pending
-
2006
- 2006-09-06 US US11/992,454 patent/US20090269231A1/en not_active Abandoned
- 2006-09-06 EP EP06779305A patent/EP1931880A1/en not_active Withdrawn
- 2006-09-06 KR KR1020087007439A patent/KR20080049788A/ko not_active Ceased
- 2006-09-06 JP JP2008532854A patent/JP2009510321A/ja active Pending
- 2006-09-06 WO PCT/GB2006/003286 patent/WO2007036689A1/en not_active Ceased
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5046934A (en) * | 1988-10-24 | 1991-09-10 | Leybold Aktiengesellschaft | Twin shaft vacuum pump with purge gas inlet |
| US5356275A (en) * | 1991-03-04 | 1994-10-18 | Leybold Aktiengesellschaft | Device for supplying a multi-stage dry-running vacuum pump with inert gas |
| US5312466A (en) * | 1992-05-22 | 1994-05-17 | Alcatel Cit | Pumping installation for pumping out an enclosure containing gases which are mixed with solid particles or which generate solid condensates or particles |
| US6471497B2 (en) * | 2000-04-26 | 2002-10-29 | Kabushiki Kaisha Toyoda Jidoshokki Seisakusho | Gas supplying device for vacuum pump |
Cited By (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20100226808A1 (en) * | 2007-10-04 | 2010-09-09 | Nigel Paul Schofield | Multi stage, clam shell vacuum pump |
| US9279426B2 (en) * | 2007-10-04 | 2016-03-08 | Edwards Limited | Multi stage, clam shell vacuum pump |
| WO2011077105A3 (en) * | 2009-12-24 | 2012-07-12 | Edwards Limited | Dry vacuum pump with purge gas system and method of purging |
| US9334863B2 (en) | 2009-12-24 | 2016-05-10 | Edwards Limited | Pump |
| US20130259717A1 (en) * | 2010-12-10 | 2013-10-03 | Ateliers Busch Sa | Vacuum pump for applications in vacuum packaging machines |
| US9638181B2 (en) * | 2010-12-10 | 2017-05-02 | Ateliers Busch Sa | Vacuum pump for applications in vacuum packaging machines |
| GB2535703A (en) * | 2015-02-23 | 2016-08-31 | Edwards Ltd | Gas supply apparatus |
| GB2535703B (en) * | 2015-02-23 | 2019-09-18 | Edwards Ltd | Gas supply apparatus |
| US20210140430A1 (en) * | 2017-06-17 | 2021-05-13 | Leybold Gmbh | Multi-stage rotary piston pump |
| US20220120279A1 (en) * | 2019-02-14 | 2022-04-21 | Pfeiffer Vacuum | Rough-vacuum pump of dry type |
| WO2023275773A1 (en) * | 2021-06-29 | 2023-01-05 | Edwards Korea Limited | Stator assembly for a roots vacuum pump |
Also Published As
| Publication number | Publication date |
|---|---|
| EP1931880A1 (en) | 2008-06-18 |
| GB0519742D0 (en) | 2005-11-09 |
| WO2007036689A1 (en) | 2007-04-05 |
| JP2009510321A (ja) | 2009-03-12 |
| KR20080049788A (ko) | 2008-06-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| AS | Assignment |
Owner name: EDWARDS LIMITED, UNITED KINGDOM Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:BIRCH, PETER HUGH;CZERNIAK, MICHAEL ROGER;REEL/FRAME:020740/0051;SIGNING DATES FROM 20080211 TO 20080218 |
|
| STCB | Information on status: application discontinuation |
Free format text: ABANDONED -- AFTER EXAMINER'S ANSWER OR BOARD OF APPEALS DECISION |