| 摘要 |
PURPOSE:To obtain a field effect transistor having short gate length, and having a favorable high-frequency characteristic by a method wherein a gate electrode is formed extending over both a thin active layer and a thick active layer. CONSTITUTION:An N type active layer 7 is formed on the surface of a semiinsulating GaAs crystal substrate 1. N type impurity ions, Si ions for example, are implanted in the GaAs crystal substrate using a photo resist 8 as a mask, after then the photo resist 8 is removed, annealing is performed using a proper method, using an SiO2 film as a protective film for example, to activate the implanted ions, and a thick active layer 6 is formed. At this time, the active layer 6 has larger sheet carrier consentration and/or has thicker thickness as compared with the active layer 7. Then a gate electrode 3 is formed extending over both the active layers 6, 7 using lithography technique. At this time, length Lg of the overlapping part of the electrode 3 and the thin active layer 7 is made to 0.2- 0.5mum. After then, a source electrode 4 and a drain electrode 5 are formed according to the usual method. |
