JPS56164526A - Ion implantation - Google Patents

Abstract

PURPOSE:To prevent the charge-up destruction of an insulating film resulting from the stored ions, by specifying the ion implantation current and charge density when a diffused region is formed by implanting ions into a semiconductor substrate having a floating gate electrode or the like embedded in an insulating film. CONSTITUTION:On a semiconductor substrate 1, an insulating film 2 of an oxide or the like is formed having an electrode 5 of a floating gate or the like embedded therein. A diffused region 4 is formed in the region on the substrate 1 where said insulating film 2 does not exist by implanting ions 3. On doing this, positive charges 30 are stored at the surface of the film 2, while negative charges 60 are stored at the interface between the film 2 and the substrate 1. Moreover, negative charges 40 and positive charges 50 are stored at the front and back surfaces of the electrode 5 respectively. If the quantity of the stored charges becomes large enough, discharge 200 takes place between the charges 50 and 60. Therefore, when the ions 3 are implanted, an ion beam of more than 1mA is employed, the implanted charge density is specified to be less than 12mucoul/cm<2>.scan, and implantation is performed only once to reach completion, in order to eliminate the production of pin holes in the film 2 and to prevent the charge-up destruction thereof.