Ion implantation device and a method of semiconductor manufacturing by the implantation of boron hydride cluster ions
View Patent ↗A method of manufacturing a semiconductor device includes the steps of: providing a supply of molecules containing a plurality of dopant atoms into an ionization chamber, ionizing said molecules into dopant cluster ions, extracting and accelerating the dopant cluster ions with an electric field, selecting the desired cluster ions by mass analysis, modifying the final implant energy of the cluster ion through post-analysis ion optics, and implanting the dopant cluster ions into a semiconductor substrate. In general, dopant molecules contain n dopant atoms, where n is an integer number greater than 10. This method enables increasing the dopant dose rate to n times the implantation current with an equivalent per dopant atom energy of 1/n times the cluster implantation energy, while reducing the charge per dopant atom by the factor n.
1. An ion source comprising:
a source of gas;
an ionization chamber in fluid communication with said source of gas, said ionization chamber formed with one or more electron entrance apertures, for receiving one or more electron, beams generated by an ion source located outside of said ionization chamber, an ion extraction aperture for enabling an ionized beam to be extracted and a gas inlet aperture, said ionization chamber configured to enable ionization of said gas by electron bombardment;
one or more electron sources for generating one or more electron beams,
said electron source disposed outside of said ionization chamber; and
a first source of magnetic flux for generating a magnetic field within said ionization chamber, said source including a magnetic yoke assembly disposed outside of said ionization chamber.
2. The ion source as recited in claim 1 , wherein said magnetic yoke assembly includes a permanent magnet.
3. The ion source as recited in claim 1 , wherein said magnetic yoke assembly includes an electromagnet.
4. The ion source as recited in claim 1 , wherein said one or more electron sources are configured so that said electron beam is generally parallel to the plane or planes containing the one or more electron entrance apertures, further including one or more beam steerers for bending said one or more electron beams so as to be generally perpendicular to the plane or planes containing said one or more electron entrance apertures.
5. The ion source as recited in claim 1 , wherein each of said one or more beam steerers includes a second source of magnetic flux.
6. The ion source of claim 1 , further including a magnetic shield between said electron sources and said magnetic yoke assembly, to substantially prevent the field produced by said magnetic yoke assembly from penetrating into the region of said electron sources.