| 摘要 |
PURPOSE:To obtain an element which has high mutual conductance and small feedback capacity by forming polycrystalline silicon layers of different thickness in holes for forming two gate regions, and ion implanting through the holes to form gate regions of different depths. CONSTITUTION:An N-type epitaxial layer 2 is formed on a P-type silicon substrate 1, and a P<+> type separating region 3 which arrives at the substrate 1 is formed through the layer 2 to form the layer 2 as an insular region. Then, with an SiO2 film 4 as a mask phosphorus ions are diffused to form source and drain regions 5, 6. Then, the film 2 is selectively removed to form two windows 7, 8 for forming a gate region. Then, a polycrystalline silicon layer 9 is formed in the window 8, boron difluoride ions are implanted, subsequently heat treated to form gate regions of different depth in the windows 7, 8. |
