Lateral-Transistor Test Structures for Evaluating the Effectiveness of Surface Doping Techniques

This paper presents a lateral-transistor test structure for evaluating the effectiveness of surface doping techniques used to fabricate ultrashallow diodes and ohmic contacts. The test structure requires very limited processing, and simple I-V measurements provide a separation of the hole and electron currents across the junction under investigation. The theoretical behavior is verified by Sentaurus simulations. The ability to discern between Schottky-like and pn-junction diodes is demonstrated by the measurement of a series of junctions fabricated by arsenic dopant deposition plus laser annealing. The activation and drivein of the deposited arsenic is tuned by the laser energy. The anomalous behavior theoretically predicted for very thin, lightly-doped junctions is observed experimentally. Considerations for an optimal design of the test structures are given.