| 摘要 |
PURPOSE:To obtain the titled device without parasitic bi-polar effect by a method wherein a film for ion implantation mask is deposited over the whole surface from above the first mask, and then left only on the side of a mask aperture by RIE into the second mask. CONSTITUTION:A P type Si substrate 51 is provided with an N<+> drain 53 and a P<+> layer 52 for covering the side of a source which is not contributed to transistor action. They are overed with SiO2 films 54 and 55 and an N<+> source 57 is formed by ion implantation through the aperture 56 located above the source region by means of the SiO2 54 as the first mask. Next, a poly Si 58 is deposited cover the whole surface by the CVD method, and when the film 58 on the SiO2 54 is etched away by RIE, the source region 56 is reduced in diameter because of remnant of this film only on the side surface. A shield layer 59 is formed by boron ion implantation, using this as the second mask. Since this construction enables accurate formation of semiconductor regions 57 and 59 with different sizes in self-alignment, a shield source structure which can be miniaturized and increased in sensity and is prevented from parasitic bi-polar effect can be obtained. |
