| 摘要 |
For the production of V-MOS single transistor storage cells at the surface of a silicon crystal of first conductivity type, two adjoining zones of opposite conductivity type can first be produced by masked diffusion or implantation. Then, with the use of a correspondingly oriented etching mask, a funnel-shaped depression is produced at the semiconductor surface such that the two zones of opposite conductivity type are separated from one another but reach the surface of the silicon crystal within the funnel-shaped depression. This depression is then coated with a thin SiO2 layer which is provided as a carrier of the gate electrode of the field effect transistor which forms the storage cell. The two zones of the opposite conductivity type, now separated, are used as a source and as a drain and also as a storage capacitance. For geometric reasons, the two zones of opposite conductivity type can only be produced one after the other with the use of corresponding doping masks. A mask is additionally required in order to produce the funnel-shaped depression. The masks must be carefully adjusted in relation to one another. In order to eliminate the need for an additional mask, one of the masks used for the production of the zones of opposite conductivity type is employed without change as an etching mask for the production of the funnel-shaped depression. The layer forming the doping mask must then, in addition to its impermeability for the doping material utilized, also be resistant against the etching compound to be utilized.
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