| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a semiconductor device which can be manufactured easily in a short time by limiting increase in thermal diffusion time required for forming a p-type well region. <P>SOLUTION: In the method of manufacturing an SOI substrate having a semiconductor substrate 1 and a first conductivity type semiconductor layer formed on the semiconductor substrate 1 with an insulating film 2 interposed therebetween, and a lateral MOSFET where a well (here, a p-type well region 4) consisting of a second conductivity type semiconductor layer is formed in an active layer 3 consisting of the first conductivity type semiconductor layer, and source and drain regions consisting of the first conductivity type semiconductor layer is formed in the well and the first conductivity type active layer 3, the step for determining the film thickness d of a first semiconductor layer of the SOI substrate is a step for setting the film thickness d equal to n times of the channel length Lch or less. Assuming the diffusion rate of impurities, composing the second conductivity type semiconductor layer in thermal diffusion atmosphere, in the horizontal direction is V<SB POS="POST">difh</SB>in the first conductivity type semiconductor layer, and the diffusion rate in the vertical direction is V<SB POS="POST">difv</SB>, the n is selected to satisfy the relations; n=V<SB POS="POST">difv</SB>/V<SB POS="POST">difh</SB>and d/Lch<n. <P>COPYRIGHT: (C)2012,JPO&INPIT |
