CN109300778B - Ion implantation method - Google Patents
Ion implantation method Download PDFInfo
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- CN109300778B CN109300778B CN201811154466.1A CN201811154466A CN109300778B CN 109300778 B CN109300778 B CN 109300778B CN 201811154466 A CN201811154466 A CN 201811154466A CN 109300778 B CN109300778 B CN 109300778B
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having at least one potential-jump barrier or surface barrier, e.g. PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic System or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/26—Bombardment with radiation
- H01L21/263—Bombardment with radiation with high-energy radiation
- H01L21/265—Bombardment with radiation with high-energy radiation producing ion implantation
Abstract
The invention relates to an ion implantation method, which relates to the semiconductor integrated circuit manufacturing technology and comprises the step of taking an isotope ion source gas BF3 composed of boron isotopes and/or fluorine isotopes as an ion source of an ion implanter, wherein the ion implanter ionizes the isotope ion source gas BF3 to form BF2+ doped ions so as to increase or reduce the equivalent mass-to-charge ratio of the BF2+ doped ions formed by the ionization of the ion source gas BF3 by the ion implanter, and thus when the excitation current of an analysis magnetic field is adjusted to be a current, the BF2+ doped ions are easier to separate from molybdenum Mo2+, and when the doped ions are implanted into a wafer, the molybdenum Mo2+ pollution is avoided.
Description
Technical Field
The present invention relates to semiconductor integrated circuit manufacturing technology, and more particularly, to an ion implantation method.
Background
In semiconductor integrated circuit manufacturing technology, a doping process for introducing a prescribed impurity into a semiconductor is one of the key steps. The doping process includes a diffusion process and an ion implantation process, wherein the diffusion process is gradually replaced by the ion implantation process due to poor doping control and generation of dislocations on the surface of the wafer. The ion implantation process allows for better control over the location and amount of doping within the wafer. In the ion implantation process, ion source gas is ionized, separated, accelerated (acquiring kinetic energy) to form a doped ion beam, and the doped ion beam is swept across the wafer. The doping ions physically bombard the wafer to generate Gaussian distribution on the surface of the wafer.
Currently, the acceptor impurity used in ion implantation processes is mainly boron (B), the ion source gas is usually BF3 (boron trifluoride), and after the ion source gas is ionized by an ion implanter, it is generally implanted into the substrate in the form of B + or BF2+ dopant ions. Ion implanters are generally classified as gas systems, motor systems, vacuum systems, control systems, and radiation systems. The ray system comprises an ion source, an extraction electrode, a mass spectrometer, an acceleration system, an injection system and a terminal analysis system. In the ion implantation dissociation process, the whole machine table of the ion implanter is made of metal, so that the sputtering of ion beams on an ion source cavity and a running path can generate metal pollution.
Because the critical dimension of semiconductor devices is continuously reduced, the semiconductor technology is continuously pushed to smaller process nodes, semiconductor products are more and more sensitive to metal pollution, yield loss is always the focus of attention of manufacturing factories, and metal pollution control becomes a difficult problem.
Before the micron technology node, the influence of metal pollution existing in the ion implantation process on the process can be ignored due to the larger critical dimension. After entering the nano technology node, the metal pollution existing in the ion implantation process has a great influence on the process due to the small critical dimension. Particularly 55nm products, in order to obtain PP S/D with shallow junction depth and stability, when BF2+ source seeds are adopted for injection, isotope ion source gas BF3 generates high-energy ion beams in ionization, collides with an ion source cavity and walls on a running path, generates Mo2+ through reaction, and BF2+ and Mo2+ with the same energy have similar equivalent mass-to-charge ratio, and part of Mo2+ is injected into a wafer along with BF2+ to bring molybdenum metal pollution.
Currently, the metal molybdenum of an ion implanter is usually monitored by measuring the metal content of a control wafer through an inductively coupled plasma analyzer (ICPMS), and an ICPMS test has the defects of long test time, high cost, easy control of wafer quality influence, poor test stability and incapability of controlling metal pollution.
In the semiconductor integrated circuit manufacturing technology, how to reduce and control the metal molybdenum pollution is a difficult problem.
Disclosure of Invention
The invention aims to provide an ion implantation method, which comprises the step of taking an isotope ion source gas BF3 consisting of boron isotopes and/or fluorine isotopes as an ion source of an ion implanter, wherein the ion implanter ionizes the isotope ion source gas BF3 to form BF2+ doped ions so as to increase or reduce the equivalent mass-to-charge ratio of the BF2+ doped ions formed by the ionization of the ion source gas BF3 by the ion implanter.
Furthermore, the difference between the equivalent mass-to-charge ratio of BF2+ doped ions formed by ionizing the isotope ion source gas BF3 and the equivalent mass-to-charge ratio of Mo2+ by the ion implanter is not less than 1.
Further, fluorine F in the isotope ion source gas BF3 is an isotope 17F of fluorine F.
Further, an ion source gas B17F3 composed of an isotope 17F of boron and fluorine is used as an ion source of an ion implanter, and the ion implanter ionizes the ion source gas B17F3 to form B17F2+ dopant ions.
Further, boron B in the isotope ion source gas BF3 is an isotope of boron B having a relative atomic mass of less than 9.8.
Further, boron B in the isotope ion source gas BF3 is an isotope 9B of boron B.
Further, boron B in the isotope ion source gas BF3 was an isotope 10B of boron B, and fluorine F was an isotope 18F of fluorine F.
Further, an ion source gas 10B18F3 containing an isotope 10B of boron and an isotope 18F of fluorine is used as an ion source of the ion implanter to form 10B18F2+ dopant ions.
Further, an isotope ion source gas BF3 composed of an isotope of boron and/or an isotope of fluorine is used as an ion source of an ion implanter which ionizes an isotope ion source gas BF3 to form BF2+ dopant ions, wherein the equivalent mass-to-charge ratio of the BF2+ dopant ions is at least 1 greater than that of molybdenum metal Mo2 +.
Further, an isotope ion source gas BF3 composed of an isotope of boron and/or an isotope of fluorine is used as an ion source of an ion implanter, and the ion implanter ionizes the isotope ion source gas BF3 to form BF2+ doped ions, wherein the equivalent mass-to-charge ratio of the BF2+ doped ions is at least 1 less than that of molybdenum metal Mo2 +.
In an embodiment of the present invention, an isotope ion source gas BF3 composed of boron isotopes and/or fluorine isotopes is used as an ion source of an ion implanter, and the ion implanter ionizes an isotope ion source gas BF3 to form BF2+ doped ions, so as to increase or decrease the equivalent mass-to-charge ratio of BF2+ doped ions, and make the difference between the equivalent mass-to-charge ratio of BF2+ doped ions and the equivalent mass-to-charge ratio of Mo2+ not less than 1, so that when the excitation current of the analysis magnetic field is adjusted to be a current, it is easier to separate BF2+ doped ions from molybdenum metal Mo2+, and when the doped ions are implanted into the wafer, molybdenum metal Mo2+ contamination is not brought, so as to control molybdenum metal contamination from the root.
Drawings
FIG. 1 is a schematic diagram of a mass spectrometer analyzing magnetic fields.
The reference numerals of the main elements in the figures are explained as follows:
100. a vacuum chamber; 200. and a magnet.
Detailed Description
The technical solutions in the present invention will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are some, but not all embodiments of the present invention. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.
In an embodiment of the present invention, an ion implantation method is provided, including: an isotope ion source gas BF3 composed of boron isotopes and/or fluorine isotopes is used as an ion source of an ion implanter, the ion implanter ionizes the isotope ion source gas BF3 to form BF2+ doped ions, and the difference between the equivalent mass-to-charge ratio of the BF2+ doped ions and the equivalent mass-to-charge ratio of molybdenum metal Mo2+ is not less than 1.
Mass spectrometer analytical magnetic fields in ion implanters are a major component of ion screening in ion implanters. Referring to fig. 1, fig. 1 is a schematic diagram of a mass spectrometer analyzing magnetic field. As shown in fig. 1, the mass spectrometer analysis magnetic field mainly comprises an arc-shaped vacuum chamber 100 and a pair of upper and lower magnets 200. When the charged ions are accelerated by the attractor electric field, certain energy E is obtained:
wherein q is the charge amount of the ion; u is the voltage of the suction electrode electric field; m is the ion mass; v is the ion velocity.
When the charged ions move in the magnetic field and the moving direction is perpendicular to the direction of the magnetic field, the charged ions will make circular motion under the influence of the Lorentz force, i.e. the charged ions will move in the magnetic field
Wherein B represents the magnetic field strength; r is the radius of circular motion, i.e. the radius of curvature of the analyzing magnetic field. The radius of curvature R of the analyzing magnetic field of the ion implanter is generally fixed, and only ions satisfying formula 2 can enter the variable slit to select the dopant ions to be implanted. The mixed ion beam is deflected after being added into the magnetic field, ions with large equivalent mass-to-charge ratio (m/q) bombard the outer wall of the analysis magnetic field, small ions bombard the inner wall, and only required ions with the ratio just meeting the set value smoothly pass through the area, but the non-required ions are blocked. Generally, ions of a certain mass-to-charge ratio are selected by changing the magnetic field strength by adjusting the excitation current of the analyzing magnetic field. However, if an isotope ion source gas BF3 is adopted to ionize to form BF2+ doping ions, the mass-to-charge ratio of BF2+ doping ions is similar to the mass-to-charge ratio of molybdenum metal Mo2+ generated in the process of forming BF2+ doping ions, generally the mass-to-charge ratio of BF2+ doping ions is 48.8, and the mass-to-charge ratio of Mo2+ is 48, so when the excitation current of the analysis magnetic field is adjusted to be one current, BF2+ doping ions and molybdenum metal Mo2+ with similar mass-to-charge ratios are difficult to be completely separated, and therefore, part of the molybdenum metal Mo2+ is injected into the wafer along with the BF2+ doping ions, and metal pollution is brought.
In the invention, the isotope ion source gas BF3 composed of boron isotope and/or fluorine isotope is used as the ion source of the ion implanter to increase or decrease the equivalent mass-to-charge ratio of BF2+ doped ions formed by ionizing the isotope ion source gas BF3 by the ion implanter, so that the difference between the equivalent mass-to-charge ratio of the BF2+ doped ions and the equivalent mass-to-charge ratio of Mo2+ is not less than 1, therefore, when the excitation current of the analysis magnetic field is adjusted to be one current, the BF2+ doped ions are easier to separate from the Mo2+ molybdenum metal, and when the doped ions are implanted into the wafer, the Mo2+ molybdenum pollution is not brought.
Specifically, in an embodiment of the present invention, the fluorine F in the isotope ion source gas BF3 is an isotope 17F of fluorine F. An ion source gas B17F3 composed of isotopes 17F of boron and fluorine is used as an ion source of an ion implanter, and the ion implanter ionizes the ion source gas B17F3 to form B17F2+ doped ions, wherein the mass-to-charge ratio of B17F2+ is 44.8, and the mass-to-charge ratio of Mo2+ is 48, so that when the excitation current of an analysis magnetic field is adjusted to be one current, the B17F2+ doped ions are easily separated from molybdenum metal Mo2+, and when the doped ions are implanted into a wafer, molybdenum metal Mo2+ pollution is not brought. Of course, the fluorine F in the isotope ion source gas BF3 is not limited to the isotope 17F of fluorine F, and in one embodiment of the present invention, an isotope of fluorine F with a relative atomic mass of less than 18.5 may be used in the present invention.
Of course, in one embodiment of the present invention, the boron B in the isotope ion source gas BF3 may be the isotope 9B thereof. The ion source gas 9BF3 composed of boron isotope 9B and fluorine is used as an ion source of an ion implanter to form 9BF2+ doped ions so as to reduce the mass-to-charge ratio of 9BF2+, in one embodiment of the invention, the mass-to-charge ratio of 9BF2+ is 47, so that the difference between the equivalent mass-to-charge ratio of 9BF2+ doped ions and the equivalent mass-to-charge ratio of Mo2+ is not less than 1, when the excitation current of an analysis magnetic field is adjusted to be a current, the 9BF2+ doped ions are easier to separate from molybdenum metal Mo2+, and when the doped ions are implanted into a wafer, the molybdenum metal Mo2+ pollution is not brought. Of course, the isotope ion source gas BF3 is not limited to the isotope 9B, and in one embodiment of the present invention, isotopes of boron B having a relative atomic mass of less than 9.8 may be applied to the present invention.
Of course, in an embodiment of the present invention, the isotope ion source gas BF3 has boron B as its isotope 10B and fluorine F as its isotope 18F. An ion source gas 10B18F3 composed of boron isotope 10B and fluorine isotope 18F is used as an ion source of an ion implanter to form 10B18F2+ doped ions so as to reduce the mass-to-charge ratio of 10B18F2+, in an embodiment of the invention, the mass-to-charge ratio of 10B18F2+ is 46, so that the difference between the equivalent mass-to-charge ratio of 10B18F2+ doped ions and the equivalent mass-to-charge ratio of Mo2+ is not less than 1, and when the excitation current of an analysis magnetic field is adjusted to be a current, the 10B18F2+ doped ions are easily separated from molybdenum metal Mo2+, and when the doped ions are implanted into a wafer, molybdenum metal Mo2+ pollution is not brought.
In one embodiment of the present invention, an isotope ion source gas BF3, which is composed of isotopes of boron and/or fluorine, is used as an ion source of an ion implanter, which ionizes an isotope ion source gas BF3 to form BF2+ dopant ions, wherein the equivalent mass-to-charge ratio of the BF2+ dopant ions is at least 1 greater than the equivalent mass-to-charge ratio of molybdenum metal Mo2 +.
In one embodiment of the present invention, an isotope ion source gas BF3, which is composed of isotopes of boron and/or fluorine, is used as an ion source of an ion implanter, which ionizes an isotope ion source gas BF3 to form BF2+ dopant ions, wherein the equivalent mass-to-charge ratio of the BF2+ dopant ions is at least 1 less than the equivalent mass-to-charge ratio of molybdenum metal Mo2 +.
Thus, in an embodiment of the present invention, the isotope ion source gas BF3 composed of boron isotopes and/or fluorine isotopes is used as an ion source of the ion implanter, and the ion implanter ionizes the isotope ion source gas BF3 to form BF2+ dopant ions, so as to increase or decrease the equivalent mass-to-charge ratio of the BF2+ dopant ions, so that the difference between the equivalent mass-to-charge ratio of the BF2+ dopant ions and the equivalent mass-to-charge ratio of the Mo2+ is not less than 1, and thus, when the excitation current of the analysis magnetic field is adjusted to be one current, the BF2+ dopant ions are more easily separated from the molybdenum metal Mo2+, and when the dopant ions are implanted into the wafer, the molybdenum metal Mo2+ contamination is not brought. Compared with the method for monitoring the molybdenum metal by measuring the metal content of the control wafer by using an inductance coupling plasma analyzer (ICPMS) which is commonly used at present, the method can radically control the molybdenum metal pollution.
Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.
Claims (1)
1. An ion implantation method, comprising: the ion source gas 10B18F3 composed of the boron isotope 10B and the fluorine isotope 18F is used as the ion source of the ion implanter, the ion implanter ionizes the isotope ion source gas 10B18F3 to form 10B18F2+ doped ions with the mass-to-charge ratio of 46, the difference between the equivalent mass-to-charge ratio and Mo2+ with the mass-to-charge ratio of 48 is not less than 1, the excitation current of the analysis magnetic field is adjusted to be one current, the BF2+ doped ions are separated from molybdenum metal Mo2+, and when the doped ions are implanted into the wafer, molybdenum metal Mo2+ pollution is not brought.
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| CN103153858A (en) * | 2010-08-18 | 2013-06-12 | 先进技术材料股份有限公司 | Isotopically-enriched boron-containing compounds, and methods of making and using same |
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| TWI386983B (en) * | 2010-02-26 | 2013-02-21 | Advanced Tech Materials | Method and apparatus for enhanced lifetime and performance of ion source in an ion implantation system |
| US9570271B2 (en) * | 2014-03-03 | 2017-02-14 | Praxair Technology, Inc. | Boron-containing dopant compositions, systems and methods of use thereof for improving ion beam current and performance during boron ion implantation |
| CN107680904A (en) * | 2017-09-04 | 2018-02-09 | 天津大学 | Application and method of the isotope of boron 11 in the semiconductor doping of integrated circuit |
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| CN103153858A (en) * | 2010-08-18 | 2013-06-12 | 先进技术材料股份有限公司 | Isotopically-enriched boron-containing compounds, and methods of making and using same |
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