| 摘要 |
PURPOSE:To prevent the variation of threshold voltage in the vicinity of a drain by bringing a gate insulating film to a film with stepped sections thick on the source region side and thin on the drain region side without equalizing the thickness of the gate insulating film when a source region and a drain region are formd to a semicouductor substrate and a gate electrode is shaped between the source region and the drain region through the gate insulating film. CONSTITUTION:A gate insulating film 2 on which boron is diffused in order to control threshold voltage is applied on a P type Si substrate 1, and a stepped section is generated in the film 2 as a gate insulating film 3 in thin thickness by using an HF solution only on the drain side of the film 2 on a region as a channel through selective etching. A polycrystalline Si gate electrode 4 of a predetermined shape is formed extending over the films 2 and 3 while containing the stepped section, and the films 2 and 3 protruding to both sides of the electrode 4 are removed through etching. A source region 5 is diffused and formed to the substrate 1 on the film 2 side and a drain region 6 to the substrate 1 on the film 3 side respecively. Accordingly, the variation of threshold voltage in the vicinity of the region 6 by hotelectrons is avoided. |
