A new vertical pnp transistor for integrated circuits

The need for a monolithic integrated circuit (IC) containing pnp and npn transistors has been recognized for a long time and is becoming serious, for obtaining an unique and simple circuit. The most widely used method recently for incorporating pnp transistors into the ICs has been the employment of the well-known lateral transistor with low performance, hFEof ∼ 1 and fTof ∼ 1 MHz. Other structures have been proposed. However the improvement of one parameter has come at the expense of other parameters. Sometimes the structures are costly and complex.