Method for improving the doping of a semiconductor material

• US 4,004,950 A
• Filed: 01/10/1975
• Issued: 01/25/1977
• Est. Priority Date: 01/10/1974
• Status: Expired due to Term

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation), Agence Nationale de Valorisation de la Recherche (Bpifrance SA /Old/)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation), Agence Nationale de Valorisation de la Recherche (Bpifrance SA /Old/)
• Inventors: Borel, Joseph, Monnier, Joel, Baruch, Pierre
• Primary Examiner(s): Lovell, C.
• Assistant Examiner(s): Davis, J. M.
• Application Number:
  US05/539,983
• Time in Patent Office: 746 Days
• Field of Search: 148/1.5, 357/91
• US Class Current: 438/186
• CPC Class Codes: H01L 21/22 Diffusion of impurity materials, e.g. doping materials, electrode materials, into or out of a semiconductor body, or between semiconductor regions; Interactions between two or more impurities; Redistribution of impurities
• CPC Class Codes: H01L 21/263 with high-energy radiation H01L21/261 takes precedence
• CPC Class Codes: H01L 21/26506 in group IV semiconductors
• CPC Class Codes: H01L 21/2658 of a molecular ion, e.g. decaborane
• CPC Class Codes: H01L 21/74 Making of localized buried regions, e.g. buried collector layers, internal connections substrate contacts
• CPC Class Codes: H01L 29/00 Semiconductor devices specially adapted for rectifying, amplifying, oscillating or switching and having potential barriers; Capacitors or resistors having potential barriers, e.g. a PN-junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof ; Multistep manufacturing processes therefor H01L31/00 - H01L33/00, H10K10/00, H10N take precedence; details other than of semiconductor bodies or of electrodes thereof H01L23/00; devices consisting of a plurality of solid state components formed in or on a common substrate H01L27/00

Abstract

In a first step, the semiconductor material is doped in a known manner with impurities having a given conductivity type and a given concentration profile. In a second step, the material is maintained at a high temperature, bombarded with a beam of particles which are accelerated with a given energy so as to penetrate into the crystal during a predetermined time interval. The resultant migration of impurities produces an increase in the impurity concentration irrespective of the sign of the initial concentration gradient within a zone adjacent to the zone of stopping of the particles.

Claims

1. A method for improving the doping of a semiconductor material with impurities of a given conductivity type, wherein said method consists in a first step in doping said material with said impurities which have a given concentration profile and, in a second step, in maintaining said material at a high temperature, in bombarding said material with a beam of a constant intensity of particles accelerated with a constant energy which is sufficient to penetrate into the material during a given time interval so as to obtain migration of the impurities resulting in an increase in the impurity concentration irrespective of the sign of the initial concentration gradient within a zone adjacent to the zone of stopping of the particles, said zone being in a portion of said material which is doped with said impurity.

2. A method according to claim 1, wherein the energy of the beam of non-doping ions is such that the zone of stopping of said particles is adjacent to the region in which it is desired to obtain a rise in the impurity concentration gradient.

3. A method according to claim 1, wherein said particles are non-doping and the fluence of the beam is such that the desired value of the rise in the concentration gradient is obtained.

4. A method according to claim 1, wherein the acceleration energy is within the range of 200 to 700 keV.

5. A method according to claim 1, wherein the temperature is within the range of 700°

to 1000°

C.

6. A method according to claim 1, wherein the particles are selected from the group comprising the molecules, the atoms and the ions.

7. A method according to claim 6, wherein the particles are non-doping and are selected from the group comprising the protons and the molecular ions H₂⁺.

8. A method according to claim 1, wherein the particles are doping in the case of the semiconductor material.

9. A method according to claim 1, wherein the particles are non-doping in the case of said semiconductor material.

10. A method according to claim 7, wherein the non-doping particles are protons and wherein the fluence of the proton beam is within the range of 10¹⁵ p/cm² and 10¹⁹ p/cm².

11. A method according to claim 1, wherein the doping impurities are selected from the elements which have an energy level of small depth.

12. A method according to claim 11, wherein the impurities are selected from the elements of columns III and V of the periodic table of elements.

13. A method according to claim 1, wherein the doping of the first step of said method is homogeneous.

14. A method according to claim 1, wherein the doping of the first step of said method has any concentration profile.

15. Application of the method according to claim 1 to the fabrication of a bipolar transistor, wherein said method consists in forming within the collector zone between the base and the collector contact a region having an impurity concentration which is higher than the concentration of the remainder of the collector zone.

16. Application of the method according to claim 1 to the fabrication of a diode on an insulating substrate, wherein said method consists in forming within the n-type region of said diode at the interface of said region with said substrate a thin zone having an impurity concentration which is higher than that of the remainder of said region.

17. Application of the method according to claim 1 to the fabrication of a depletion MOS transistor, wherein said method consists in forming in the zone of the conducting channel which separates the drain contact from the source contact a region which exhibits a very steep doping profile.

18. Application of the method according to claim 1 to the fabrication of a buried-electrode field-effect transistor, wherein said electrode is formed by means of said method.

19. A method according to claim 1, wherein said material is subjected to a plurality of said bombardment steps, each bombardment being with particles accelerated at a different energy, the energy being maintained constant throughout each bombardment.

20. A method of increasing the concentration of an impurity having a given conductivity type within a portion of a semiconductor material doped with said impurity comprising:

heating said material to an elevated temperature,

bombarding said heated material with a stream of particles,

maintaining the intensity of said beam constant throughout said bombardment,

maintaining the energy at which said particles are accelerated constant throughout said bombardment, said energy being at a sufficient level so that the zone in which said particles are stopped in said material is doped with said impurity.

21. A method according to claim 20 wherein said elevated temperature is between 700°

to 1000°

C, said particles are protons, said intensity is from 10¹⁵ p/cm² to 10¹⁹ p/cm², and said energy is from 200 to 700 keV.