WO2013068796A2 - Source d'ions moléculaires pour implantation ionique - Google Patents

Source d'ions moléculaires pour implantation ionique Download PDF

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Publication number
WO2013068796A2
WO2013068796A2 PCT/IB2012/000830 IB2012000830W WO2013068796A2 WO 2013068796 A2 WO2013068796 A2 WO 2013068796A2 IB 2012000830 W IB2012000830 W IB 2012000830W WO 2013068796 A2 WO2013068796 A2 WO 2013068796A2
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WIPO (PCT)
Prior art keywords
molecular
ion source
discharge chamber
dissociator
ions
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PCT/IB2012/000830
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English (en)
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WO2013068796A3 (fr
Inventor
Ady Hershcovitch
Vasiliy GUSHENETS
Alexey BUGAEV
Timur KULEVOY
Efim OKS
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Brookhaven Science Associates, Llc
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Publication of WO2013068796A2 publication Critical patent/WO2013068796A2/fr
Publication of WO2013068796A3 publication Critical patent/WO2013068796A3/fr

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement, ion-optical arrangement
    • H01J37/08—Ion sources; Ion guns
    • 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
    • H01J37/30—Electron-beam or ion-beam tubes for localised treatment of objects
    • H01J37/317—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation
    • H01J37/3171—Electron-beam or ion-beam tubes for localised treatment of objects for changing properties of the objects or for applying thin layers thereon, e.g. for ion implantation for ion implantation
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
    • H01J2237/006—Details of gas supplies, e.g. in an ion source, to a beam line, to a specimen or to a workpiece

Definitions

  • Patent Application Registration No. 201 1145645 filed on November 9, 2011, the content of which is incorporated herein in its entirety.
  • the invention relates to the generation of molecular ions for ion implantation in a semiconductor substrate. More particularly, the invention relates to the design and manufacture of an ion source with a gas dissociator that can convert phosphine gas into molecular phosphorous (P 2 & P 4 ) ions in safe and effective way. The invention also relates to the design and manufacture of an ion source with a gas dissociator that can convert arsine and stibine gas into molecular arsenic (As 2 & As 4 ) ions or molecular antimony (Sb 2 & Sb 4 ) ions.
  • As 2 & As 4 molecular arsenic
  • Sb 2 & Sb 4 molecular antimony
  • semiconductor substrates are implanted with dopants.
  • the semiconductor substrate is made from a single crystal silicon wafer and the dopants may be atoms or molecules with properties that differ from those of the original semiconductor substrate.
  • the dopants may alter the properties of the implanted regions such that the resulting substrate may have discrete regions with different properties.
  • discrete regions with different properties in the substrate may be formed by specific ion implantation.
  • the most widely used dopants for implantation are boron and phosphorous. Boron can be used to make the p-type semiconductors and phosphorous can be used to make the n-types semiconductors. After the boron and/or phosphorous dopants are implanted, other dopants can be implanted to form more complex devices.
  • One method of introducing dopants into a semiconductor substrate is through the use of an ion implanter which includes an ion source for converting a gas or a solid material into a well-defined ion beam.
  • the ion beam typically is mass analyzed to eliminate undesired ion species, accelerated to a desired energy, and then the ions are implanted into a target.
  • the ion beam may be distributed over the target area by electrostatic or magnetic beam scanning, by target movement, or by a combination of beam scanning and target movement.
  • the ion beam is typically a spot beam or a ribbon beam.
  • phosphine gas that can be used as a working mixture in discharge systems of ion sources mainly to obtain both singly charged and multiply charged atomic P ions.
  • the use of phosphine allows efficient control and stabilization of the gas flow rate to the discharge chamber.
  • the use of phosphine (PH3) gas allows for efficient control and stabilization of the gas flow rate to the discharge chamber
  • the ion beam typically contains PH + and P3 ⁇ 4 + ions along with P + , P 2+ , P 3+ , and P 4+ ions, and the amount of PH + and P3 ⁇ 4 + ions can reach about 25-30 % of the total beam current.
  • junction depth has not been scaled quite as aggressively, and in particular, ultra-shallow junctions have been hard to achieve with current technology.
  • decreasing junction depth can be achieved by decreasing ion energy.
  • decreasing the ion energy e.g., the accelerating voltage
  • One example of the observed production rates are found in the implantation of single/atomic phosphorous ions generated from phosphine.
  • One of the possible ways to decrease the energy per dopant atom is to generate molecular ion beams that contain two or more dopant atoms, i.e., polyatomic conglomerates or clusters (M n ).
  • the implanted energy per atom in a molecular ion at a given accelerating voltage decreases by a value multiple of the number of atoms (n) in the molecule or cluster.
  • the implanted dose increases by a square of the number of atoms (n 1'5 ) compared to the implanted energy of monatomic ions.
  • the use of molecular ions instead of monoatomic ions is very promising for generating shallow junctions.
  • Horsky T. N. proposed generating molecular ions using furnace generated molecular phosphorous vapors from a solid red phosphorous and a conventional beam line implanter with a dual-mode ion source that operates in a cluster formation mode and a monomer formation mode.
  • the cluster formation mode is mediated by electron impact ionization and the monomer formation mode is mediated by an arc discharge.
  • the discharge chamber in the Horsky ion source is an extended rectangular parallelepiped with an ion extraction slit along its longest dimension.
  • the electron gun creates an energetic electron beam, which is deflected by 90 degrees (90°) through the source by a magnetic dipole field.
  • the deflected electron beam enters the source ionization chamber through a small entrance aperture.
  • the electron beam is guided along a path parallel to and directly behind the ion extraction slit by a uniform axial magnetic field produced by a permanent magnet surrounding the ionization chamber. Ions are thus created along the electron beam path and adjacent to the extraction slit.
  • Implanter optics are located outside of the discharge chamber on the source side of the emission slit.
  • this serves to provide good extraction efficiency of the ions, such that an ion current density of up to 1 mA/cm 2 can be extracted from the source.
  • the ion source system of Horsky is difficult to operate due to its design complexity and the use of the electron gun with electron beam rotation.
  • Gushenets et al. proposed generating molecular ions using furnace generated molecular phosphorous vapors from a solid red phosphorous and a hot-cathode ion source.
  • Molecular Phosphorus Ion Source for Semiconductor Technology Proc. of the 10th Int. Conf. on Modification of Materials with Particle Beams and Plasma Flows, Tomsk 2010, pp. 783; incorporated herein by reference in its entirety
  • the Gushenets, et al. ion-source system has a discharge chamber with a hollow anode.
  • the anode has an emission slit located along the side of the discharge chamber opposite the vapor entrance.
  • the anode has two holes at the faces of the discharge chamber through which electrons emitted from the hot cathode and electrons are reflected from the anticathode.
  • Gushenets et al. describe a procedure of evaporating red phosphorus in a crucible with phosphorus in a furnace maintained at about 800 °C. Once the molecular phosphorous from the oven enters the discharge chamber, it comes in contact with a discharge plasma from the arc discharge current (i.e., an electron beam), which is guided along a path parallel to and directly behind the ion emission slit by a uniform axial magnetic field.
  • the arc discharge current i.e., an electron beam
  • a molecular phosphorous (phosphorus) ion-source contains a dissociator that splits phosphine molecule(s) into hydrogen and molecular phosphorous components before they are delivered to a discharge chamber, preferably via a vapor line.
  • the dissociator has a heater spiral within a heat-resistant tube covered by a thermal shield. The dissociator converts the phosphine gas into the molecular phosphorous and advantageously provides on demand feed for the discharge chamber that permits the generation of phosphorous ions for low energy ion implantation.
  • the use of the dissociator avoids production of a gaseous stream of molecular phosphorous by the undesirable process of heating the solid red phosphorous in a furnace (oven).
  • molecular phosphorous ions are generally used to produce n-type semiconductors
  • other atomic or molecular species in gaseous form can be used in the subsequent implantation to form more complex devices.
  • other ionic species can be derived from other gaseous sources such as (3 ⁇ 4, N 2 , and Ar, or when gaseous species are not available, the ionic species can be derived from vapor sources such as As, Sb, Ga, and Ge vapors.
  • the disclosed discharge chamber is an extended hollow anode with an emission slit for ion extraction and two diaphragm-type holes at opposite ends.
  • the diaphragm-type holes provide the access points for the arc discharge current generated by a directly heated Penning-type cathode at one end and an anticathode (electron reflector) at the opposite end.
  • the high operating temperature and/or the high discharge current density in the discharge chamber causes the molecular phosphorous to ionize.
  • the ion-source system further has a suppressor with an accelerating electrode located outside of the discharge chamber at opposite ends of the emission slit.
  • the molecular phosphorous ions are preferably directed into a bending magnet to select desired ions of a desired energy, which are then used to impinge the silicon wafer target.
  • a method of producing a molecular phosphorous ion beam employs the steps of injecting phosphine (P3 ⁇ 4) gas into a dissociator; splitting phosphine into hydrogen and molecular phosphorous components free of Pt3 ⁇ 4 and PH; directing the phosphorous component generated in the dissociator into a discharge chamber, preferably via a short vapor line; generating molecular phosphorous ions in the discharge unit by a collision of electrons with molecular phosphorous; and collecting the generated molecular phosphorous ions.
  • a method of low- energy ion implantation is provided based on the production of molecular phosphorous ions.
  • gaseous phosphorus as a molecular P vapor source in combination with the dissociator makes it possible to speed up the adjustment of the flow rate from tens of minutes to a few seconds and to stabilize the gas supply.
  • decomposition of phosphine into P 4 and molecular hydrogen in the dissociator makes it possible to completely exclude the presence of phosphorous-hydrogen compounds at the output of the ion source. This fully eliminates the problem of utilization of the toxic PH + and Pt3 ⁇ 4 + ions and simultaneously increases the fraction of molecular P 4 and P 2 ions generated by the ion source.
  • FIG. 1 schematically illustrates the ion source proposed by Horsky (2006).
  • FIG. 2 schematically illustrates the ion source proposed by Gushenets et al. (2010).
  • FIG. 3 schematically illustrates an exemplary gas-discharge molecular ion source with a phosphine dissociator.
  • FIG. 4 illustrates one embodiment of a phosphine dissociator.
  • FIG. 5 is an ion beam spectrum showing ion beam composition with phosphine flow under three different temperatures of the heater.
  • the insert window is an enlarged view of the first major peak that shows the influence of temperature of dissociator on phosphine decomposition.
  • a gas-discharge molecular phosphorous ion source is provided that can be used in low-energy ion implanters to manufacture shallow junctions in semiconductor devices including highly integrated circuits.
  • the present ion source can safely and effectively produce molecular phosphorous ion beam(s) from phosphine (PH3) gas without the need to create a gaseous ion stream by heating solid phosphorous source in the oven.
  • the ion source has a discharge chamber and a phosphine dissociator interconnected by a vapor line. The dissociator splits phosphine (PH 3 ) molecule(s) into their hydrogen and phosphorous components according to the reaction (1).
  • FIG. 3 An exemplary ion source is shown in FIG. 3. It has a number of individual components or subsystems: (1) ⁇ 3 ⁇ 4 gas as a source of molecular phosphorous; (2) dissociator 10; (3) discharge chamber 20; and (4) vapor line 30. Each component or subsystem will be considered and described in detail herein below.
  • the ion source is configured as a provider for low-energy ion implantation in highly integrated circuits, such as semiconductors.
  • the molecular phosphorous ions can be used to produce n-type semiconductors from a solid silicon wafer, while other atomic or molecular species in gaseous form can be used in the subsequent implantation to form more complex devices.
  • phosphine gas source instead of using phosphine gas source, other trihydride group 15 gases can be used due to their molecular similarity to phosphine.
  • an arsine (Astt) gas or a stibine (Sbtt) gas can be used because in a similar fashion to phosphine, it is contemplated that the dissociator can split arsine (Astt) and stibine (Sbtt) molecule(s) into their hydrogen and arsenic or antimony components according to the reaction (5) and (6), respectively.
  • the source of phosphorus, including molecular phosphorus, used in generation of phosphorous clusters and molecular ions for low-energy ion implantation is preferably phosphine.
  • Phosphine IUPAC name: phosphane
  • phosphine is a gaseous compound of phosphorus and hydrogen under normal conditions having a chemical formula PH 3 . It is a colorless, flammable, toxic gas and if pure it is also odorless.
  • Phosphine may be prepared in a variety of ways (A. D. F. Toy, The Chemistry of Phosphorus, Pergamon Press, Oxford, UK, 1973; incorporated herein by reference in its entirety) or purchased in pure form (electronic grade; >99.9995%), for example, from Sigma- Aldrich, St. Louis, MO. Industrially it can be made by the reaction of white phosphorus with sodium hydroxide, producing sodium hypophosphite and sodium phosphite, as a by-product. Alternatively the acid-catalyzed disproportioning of white phosphorus may be used, which yields phosphoric acid and phosphine. Both routes have industrial significance. However, the acid route requires additional purification and pressurization steps.
  • Phosphine can also be made by the hydrolysis of a metal phosphide, such as aluminum phosphide or calcium phosphide, or a reaction of potassium hydroxide with phosphonium iodide (PH4I), which can generate pure phosphine, free from P2H4. Since technical grade phosphine has traces of P2H4, and the mixture is spontaneously flammable in air, burning with a luminous flame, it is preferred that the supplied phosphine is pure and free of P2H4.
  • a metal phosphide such as aluminum phosphide or calcium phosphide
  • P4I phosphonium iodide
  • the phosphine gas in one exemplary embodiment is injected into a dissociator 10 through a specifically designed valve.
  • the amount of phosphine supplied to a dissociator is between about 1 to about 10 seem (standard cubic centimeter per minute). In a preferred embodiment, the amount of phosphine supplied to a dissociator is about 3 to about 6 seem.
  • the phosphine gas initially enters the phosphine dissociator 10 where the phosphine is split into its phosphorous and hydrogen components according to reaction (1).
  • the dissociator can have other components and elements, in general, the dissociator 10 has a chamber 14, a thermal shield 13, a heat resistant tube 12, and heater spiral 11. The space between the heat resistant tube 12 and the heater spiral 11 is considered an active zone of the dissociator 10.
  • the active zone of the dissociator 10 is heated to no greater than 1000 °C, suitably between 300 °C and 1000 °C, preferably between 500 °C and 900 °C, and most preferably between 700 °C and 850 °C.
  • the dissociator 10 has a heater spiral 11 confined within a heat resistant tube 12.
  • the heater spiral 11 can be made from various materials, such as tungsten, iron- chrome aluminum, nickel-chrome, nickel-iron, nickel, stainless steel, copper, molybdenum, and M0S1 2 / MoSi.
  • the heater spiral 11 is made from a tungsten wire having a diameter of about 0.4 mm.
  • the maximum value of the heated current supplied to the heater spiral 11 can be as high as 2.4 A, although the current is preferably set to a value between 1.8 A to 2.4 A.
  • the heat resistant tube 12 can be made from any heat resistant material such as quartz, aluminum, and ceramic.
  • the heat resistant tube 12 is made from high quality quartz.
  • the heater spiral 11 and the heat resistant tube 12 form an active zone of the dissociator 10 in which phosphine flows and dissociates.
  • the length of the active zone is defined as the length of the heater spiral 11 confined by the heat resistant tube 12 and is preferably between 10 cm and 30 cm, and more preferably about 20 cm. In one exemplary embodiment, the length of the active zone is about 19 cm.
  • the heat resistant tube 12 with the heater spiral 11 is placed within a chamber (14 in FIG. 3) having a cylindrical tube 14a made of resilient material, such as stainless steel, running along the longitudinal axis of the heat resistant tube 12.
  • the rims of the tube 14a at opposite ends support two flanges 14b and 14c to form the body of the chamber identified as 14 in FIG. 3.
  • the tube 14a can have a diameter of about 10 mm to 100 mm, although, 30 mm diameter is more preferred in this particular embodiment.
  • the heat resistant tube 12 is attached to a support element 16 that sits on top of the flange 14b to avoid any contact between the cylindrical tube 14a of the chamber and the heat resistant tube 12.
  • the heat-resistant tube 12 is also preferably thermally insulated from the tube 14a by thermal screen 13, which can be a thin titanium foil with a mirror polished surface. However, to avoid overheating of the system, the cylindrical tube 14a is connected to an arc cooling radiator 15.
  • the tube 14a On one side of the tube 14a is an active zone housing 17, which is connected to a vapor drift line 30 (see FIG. 3) through a metal- ceramic valve 19.
  • the other the tube 14a has a gas feed cover 18 attached to a gas flow valve, e.g., "Micromate” made by Hoke Inc. (Spartanburg, SC) that supplies the phosphine gas.
  • a gas flow valve e.g., "Micromate” made by Hoke Inc. (Spartanburg, SC) that supplies the phosphine gas.
  • the size, shape, form, etc. of the dissociator depends on the overall system and can be adjusted accordingly. For instance, if the size of the discharge chamber is modified, it is also contemplated that the size of the dissociator may have to be adjusted as well. For example, if the discharge chamber is increased in size (dimension) to accommodate the need for more molecular ions, the dissociator can be proportionally increased to accommodate the prescribed discharge chamber.
  • dissociators such as an RF dissociator described in Hershcovitch et al. (Rev. of Set Instrum. 58, 547, 1987; the disclosure of which incorporated herein by reference) and Hershcovitch (Phys. Rev. Lett. 63, 750 (1989); the disclosure of which incorporated herein by reference) may also be used in the disclosed ion source to generate molecular phosphorous gaseous stream.
  • the phosphine gas is split into its phosphorous and hydrogen components, the two gases are allowed to enter the discharge chamber.
  • the ion-source system utilizes a similar discharge chamber proposed by Gushenets et al. and illustrated in FIG. 2.
  • the discharge chamber 20 has a hollow anode 21 shaped as an extended rectangular parallelepiped. The dimensions of the anode 21 can vary widely depending on desired implanter ion beam cross section.
  • the dimensions of the anode 21 are about 8 mm x 14 mm x 70 mm.
  • the anode 21 has an emission slit 28 located along the side of the discharge chamber 20 opposite the vapor entrance, which is connected to the vapor line 30.
  • the slit 28 covers at least 50 % of the anode 21 in length.
  • the length of the slit 28 can range between about 2 mm and about 750 mm, or between about 40 mm and about 75 mm. In one exemplary embodiment, the length of the slit 28 is about 40 mm.
  • the slit 28 can be long as compared to the length of the anode 21, the slit 28 is preferably substantially narrow as compared to the depth of the anode 21.
  • the width of the slit can range between about 1 mm and about 50 mm or between about 3 and about 7 mm. In one exemplary embodiment, the slit 28 is about 1 mm wide.
  • the anode 21 has at least two diaphragm-type holes (unmarked), one each at the opposite ends of the anode. One hole is near a heated Penning-type U-shaped filamentary cathode 22 and a shield 23, and the other hole is near an electron reflector or anticathode 24.
  • the diaphragm-type holes are preferably about 3 x 6 mm 2 and provide the access points for the arc discharge current generated by the cathode 22.
  • the molecular phosphorous from the phosphine dissociator 10 enters the discharge chamber 20, it comes in contact with a discharge plasma from the arc discharge current, which is guided along a path parallel to and directly behind the ion emission slit 28 by a uniform axial magnetic field produced by a permanent or an electro magnet 25 surrounding the discharge chamber 20.
  • the high operating temperature and/or the high discharge current density in the discharge chamber 20 causes the molecular phosphorous to dissociate into molecular phosphorous ions.
  • the anticathode 24 is connected to the anode 21.
  • the ion-source system further has an ion-optical system located outside of the discharge chamber at opposite ends of the emission slit 28.
  • the ion-optical system is a standard two-electrode setup known in the art. In particular, it has a suppressor (deceleration) electrode 26 and accelerating electrode 27 that are aligned with the emission slit 28.
  • the molecular phosphorous ions in the ion beam 40 are preferably directed into a bending magnet (not shown) to select ions of a desired energy, which are then used to impinge the target, such as the silicon wafer.
  • the ion beam 40 can be accelerated to a voltage of between about 400 V and about 30 kV, depending on the desired depth of implantation.
  • discharge chamber 20 instead of employing the discharge chamber 20 to generate the molecular ion beam, other discharge chambers are also contemplated for production of an ion beam for semiconductor implantation such as Bernas discharge chamber, Freeman discharge chamber, Calutron discharge chamber, Electron-Cyclotron Resonance (ECR) discharge chamber, and microwave discharge chamber.
  • ECR Electron-Cyclotron Resonance
  • the vapor line 30 is a tube made from a resilient material, such as stainless steel.
  • the length of the vapor line 30 is not particularly limited but preferably is chosen to be as small as possible permitted by the ion source design. This is necessary to keep the walls of the vapor line 30 at a sufficiently high temperature, due to the heat released in the discharge chamber 20 and active zone of the dissociator 10, to preclude phosphorus vapor condensation on the walls of the vapor line 30. At the same time, the length of the vapor line 30 cannot be too small because the vapor line 30 ensures a required pressure difference between the active zone of the dissociator 10 and the discharge chamber 20.
  • the length of the vapor line with diameter of about 5 mm is between 10 cm to 15 cm, depending on the implanter selected and the number of other gas sources that are added to the vapor line.
  • other vapor lines (not shown) can be attached to directly to the discharge chamber 20 or through a valve 31 to provide a supply of other atomic or molecular species in gaseous form to be used in the subsequent implantation.
  • the molecular phosphorous can be used to prepare n-type semiconductors, while other ionic species derived from gaseous sources such as (3 ⁇ 4, N 2 , and Ar, or vapor sources such as As, Sb, Ga, and Ge, can be used to form more complex devices.
  • a method of producing molecular phosphorus ion beams that can be used in low-energy ion implanters to manufacture highly integrated circuits.
  • the method includes the steps of injecting phosphine gas into a dissociator; splitting phosphine (PH 3 ) molecule(s) into its hydrogen and phosphorous components; directing the phosphorous components into the discharge chamber; generating P 4 + and/or P2 + ions in the discharge unit by an arc discharge current; accelerating P 4 + and/or P2 + ions; and directing P 4 + and/or P2 + ions to a bending magnet.
  • An ion implantation system typically includes an ion source to produce the molecular or monoatomic ions, an accelerator to increase the energy of the generated ions, a separation magnet to select the ion(s) of a desired energy, and a target chamber, where the generated ions impinge on a target to produce, for example, shallow junctions in silicon wafers.
  • an ion source to produce the molecular or monoatomic ions
  • an accelerator to increase the energy of the generated ions
  • a separation magnet to select the ion(s) of a desired energy
  • a target chamber where the generated ions impinge on a target to produce, for example, shallow junctions in silicon wafers.
  • the generated ions are then passed through a bending (separation) magnet well known in the art to select ions of only desired mass energy profile, and then they are allowed to impact the preselected target, e.g., silicon wafer to convert the silicon wafer into an n-type semiconductor.
  • a bending (separation) magnet well known in the art to select ions of only desired mass energy profile, and then they are allowed to impact the preselected target, e.g., silicon wafer to convert the silicon wafer into an n-type semiconductor.
  • FIG. 3 A schematic illustration of the designed ion source system is shown in FIG. 3.
  • the production of molecular phosphorous from phosphine was examined using the ion-source system.
  • the dissociator was designed according to FIG. 4. It had a stainless steel tube of 30 mm diameter and two flanges crossed the two end of the tube. One end of the tube had a gas flow "Micromate" valve made by Hoke Inc. (Spartanburg, SC). The other end was connecter to vapor drift line, which provided gas flow to the discharge unit.
  • Inside the stainless steel tube there was quartz tube with a heater spiral.
  • the quartz tube was thermally insulated from the stainless steel tube by thermal screen made from thin titanium foil with mirror polished surface.
  • the heater spiral was made from a thin tungsten wire of 0.4 mm in diameter.
  • the heater spiral and the quartz tube formed an active zone of a dissociator in which phosphine flows. The length of the active zone was 19 cm.
  • the discharge chamber was designed according to Gushenets et al. (2010).
  • the discharge chamber has a hollow anode shaped as an extended rectangular parallelepiped with dimensions of 8 mm x 14 mm x 70 mm.
  • the anode has an emission slit located along the side of the discharge chamber opposite the vapor entrance, which is connected to the vapor line.
  • the emission slit was set to 1 x 40 mm 2 .
  • the anode has at least two diaphragm-type holes at the opposite ends, one near a heated Penning-type U- shaped filamentary cathode provided with a shield, and the other near an electron reflector or anticathode.
  • the diaphragm-type holes were set to 3 x 6 mm 2 .
  • the ion source also has a permanent or an electro magnet surrounding the discharge chamber that produces a uniform axial magnetic field. During production of molecular phosphorous ions, the anticathode was connected to the anode.
  • the ion-source system further has an ion-optical system located outside of the discharge chamber at opposite ends of the emission slit. It has a suppressor (deceleration) electrode and accelerating electrode that are aligned with the emission slit.
  • the ion source was tested under 300 V discharge burning voltage with the discharge current set to about 120-130 mA.
  • An ion extracting beam current was set to 0.6 mA.
  • the ion accelerating voltage for the electrode 27 was set to 15 kV and the suppression voltage for the electrode 26 was set to -4.5 kV.
  • the gas flow rate was not measured but the working gas pressure was monitored in vacuum vessel near the entrance of a bending magnet.
  • the working gas pressure was as low as 6 x 10 "5 Torr.
  • the ion source operated in a so called "beam plasma" mode when the anticathode electrode 4 was electrically connected to the anode 1 of discharge system (as illustrated in FIG. 3) in order to test splitting of molecule of phosphine (Pt1 ⁇ 4) into its hydrogen and phosphorous components.
  • FIG. 5 shows an ion beam spectrum.
  • FIG. 5 shows the ion beam composition for three different temperatures of the dissociator. The temperature was estimated based on the current supplied to the heater spiral. Measurements of the ion composition were made, step-by-step, after each increase in the current.
  • the line 1 in FIG. 5 illustrates a case where the heater spiral current is relatively low, i.e., less than 1.6 A, and process of phosphine dissociation is not optimal.
  • the line 2 illustrates the situation where the heater spiral current is about 1.7 A.
  • the line 3 illustrates the situation where the heater spiral current is about 1.8 A. When the heater spiral current was set above 1.8 A further changes in the ion beam composition were not observed.
  • FIG. 5 An insert in FIG. 5 shows that an increase in the dissociator temperature causes a nearly full disappearance of PH + and PI3 ⁇ 4 + fractions in the generated ion beam.
  • This demonstrates a high efficiency in the operation of the dissociator.
  • the use of the dissociator in the ion source ensures almost doubling of P2 and P 4 ions and almost complete absence of phosphorous-hydrogen compounds in the ion beam.
  • the absence of phosphorous-hydrogen compounds in the ion beam solves the problem of utilization of phosphine because these compounds are potential environmental hazards and threat to attending personnel.
  • the use of the gaseous compound of phosphorus with hydrogen as a molecular phosphorus vapor source in combination with the dissociator makes it possible to stabilize the gas supply and to speed up the adjustment of the flow rate from minutes to seconds.
  • the ion source system was compared to Clusterlon® source shown in FIG. 1, which was developed by Horsky (2006).
  • the Clusterlon® source has an oven for generation of the molecular phosphorous vapor from the red phosphorous and a discharge chamber to generate molecular phosphorous ions.
  • the discharge chamber of Horsky has an anode with an emission slit having dimensions of 8 x 48 mm that can provide a phosphorous ion current close to 3 mA.
  • the emission surface area in the Clusterlon® Source is an order of magnitude larger than the emission surface area in the ion source described in Example 1 , however, both sources have nearly the same emission current density of about 1 mA/cm 2 .
  • Example 1 the plasma parameters inside the discharge chambers for Clusterlon® source and the ion source described in Example 1 are identical.
  • the ion source described in Example 1 and illustrated in FIG. 3 has a much simpler design because it does not use an electron gun with a bending magnet.
  • the ion source described in Example 1 and illustrated in FIG. 3 almost completely eliminates PH and P3 ⁇ 4 ions in the ion beam.
  • the present ion source increases the gas and energy efficiency and fully eliminates the problem of phosphine utilization.

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  • Physical Vapour Deposition (AREA)

Abstract

L'invention concerne la production de faisceaux d'ions phosphoreux moléculaires utilisables dans des implanteurs d'ions basse énergie pour la fabrication de dispositifs semi-conducteurs. L'invention concerne plus particulièrement la conception et l'utilisation d'une source d'ions avec un dissociateur de la phosphine pouvant produire des vapeurs moléculaires P4 à partir de la phosphine. L'utilisation du composé phosphore gazeux-hydrogène comme source de vapeur moléculaire P, en association avec le dissociateur, accélère le déclenchement et la stabilisation du gaz injecté dans la chambre de décharge qui passent de quelques dizaines de minutes à quelques secondes dans les systèmes d'alimentation de four de l'invention. La décomposition de la phosphine en phosphore moléculaire et hydrogène dans la dissociateur exclut complètement la présence de composés P-H à la sortie de la source d'ions, ce qui élimine le problème d'utilisation de ce gaz toxique, et augmente simultanément la fraction des ions moléculaires P4 et P2 dans le faisceau d'ions.
PCT/IB2012/000830 2011-11-09 2012-03-16 Source d'ions moléculaires pour implantation ionique WO2013068796A2 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016036512A1 (fr) * 2014-09-01 2016-03-10 Entegris, Inc. Implantation d'ions phosphore ou arsenic au moyen de techniques de sources améliorées
CN109729636A (zh) * 2017-10-31 2019-05-07 中国科学院大连化学物理研究所 一种结构紧凑且调节温度范围广的连续分子束源系统
EP3837712A4 (fr) * 2018-08-13 2022-10-05 Varian Semiconductor Equipment Associates, Inc. Traversée de gaz thermique pour source d'ions
TWI780143B (zh) * 2017-04-13 2022-10-11 瑞士商史華曲集團研發有限公司 用於植入單電荷離子或多電荷離子至被處理物件的表面中之方法及用於實施此方法之裝置

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Publication number Priority date Publication date Assignee Title
WO2001043157A1 (fr) * 1999-12-13 2001-06-14 Semequip, Inc. Source d'ions, systeme et procede pour implantation ionique
US7838842B2 (en) * 1999-12-13 2010-11-23 Semequip, Inc. Dual mode ion source for ion implantation
KR20090029209A (ko) * 2006-06-13 2009-03-20 세미이큅, 인코포레이티드 이온 주입을 위한 이온 빔 장치 및 방법
TWI413149B (zh) * 2008-01-22 2013-10-21 Semequip Inc 離子源氣體反應器及用於將氣體饋給材料轉化成不同分子或原子物種之方法
US7863582B2 (en) * 2008-01-25 2011-01-04 Valery Godyak Ion-beam source

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2016036512A1 (fr) * 2014-09-01 2016-03-10 Entegris, Inc. Implantation d'ions phosphore ou arsenic au moyen de techniques de sources améliorées
KR20170048517A (ko) * 2014-09-01 2017-05-08 엔테그리스, 아이엔씨. 향상된 소스 기술을 이용한 인 또는 비소 이온 주입
US10109488B2 (en) 2014-09-01 2018-10-23 Entegris, Inc. Phosphorus or arsenic ion implantation utilizing enhanced source techniques
KR102214208B1 (ko) 2014-09-01 2021-02-08 엔테그리스, 아이엔씨. 향상된 소스 기술을 이용한 인 또는 비소 이온 주입
TWI780143B (zh) * 2017-04-13 2022-10-11 瑞士商史華曲集團研發有限公司 用於植入單電荷離子或多電荷離子至被處理物件的表面中之方法及用於實施此方法之裝置
CN109729636A (zh) * 2017-10-31 2019-05-07 中国科学院大连化学物理研究所 一种结构紧凑且调节温度范围广的连续分子束源系统
EP3837712A4 (fr) * 2018-08-13 2022-10-05 Varian Semiconductor Equipment Associates, Inc. Traversée de gaz thermique pour source d'ions

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