| 摘要 |
<P>PROBLEM TO BE SOLVED: To suppress variation in threshold voltage due to capturing/discharging of trapped electrons. <P>SOLUTION: The semiconductor device comprises a semiconductor substrate 11, and at least one gate electrode 13 formed on the surface of the semiconductor substrate 11 through a gate insulating film and controlling movement of charges in the semiconductor substrate 11 electrically wherein the semiconductor substrate 11 is composed of a semiconductor added with impurities and the concentration of impurities is set to become lowest at the surface position and increase toward the deeper position. When the impurity concentration only on the channel interface is reduced and the concentration in the rear of the substrate 11 is raised, unevenness of current flowing through a conduction channel is relaxed while sustaining the threshold voltage Vth at a predetermined level, and variation in threshold ΔVth due to trap can be controlled. <P>COPYRIGHT: (C)2007,JPO&INPIT |
