| 摘要 |
PURPOSE:To improve a high frequency characteristic and a noise characteristic by imbedding an insulative layer at the center of a channel area constituting J-FET or forming a concave part and specifying the height of the said part. CONSTITUTION:On a p type semiconductor substrate 1 which serves as a gate area, an n type layer 2 is caused to epitaxially grow and is surrounded by a p type separation area 4 adjoining a substrate 1 to constitute an island. Then, inside the channel area 2a of this island layer 2, a N type source area 5 and a drain area 6 are diffused and formed. Next, an insulative layer 7 having a prearranged depth t1 is imbedded in a channel area 2a located between the areas 5, 6. Or in the area 2a, a concave part 8 is carved out in the same depth and then, is covered with an oxidized film 9 on the surface and the height h of the area 2a located under the oxidized film 9 is a desired height. In this way, it is not necessary to provide the p type surfacial gate area between the areas 5, 6, but a substrate gate 1 has only to be provided. In addition, a bonding capacity between the surfacial gate and the channel is no longer generated, improving the characteristics. |
