Enhanced performance of vertical double gate MOSFET (VDGM) with oblique rotating implantation (ORI) method

Abstract

An enhanced performance of vertical double gate MOSFET (VDGM) structure was revealed by adopting the oblique rotating ion implantation (ORI) method. The device structure was simulated based on TCAD tools and verified by good matching data with the published experimental results. With ORI method a symmetrical self-aligned source/drain regions over the silicon pillar and sharp vertical channel profile was observed. With L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> = 50nm, the V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> is 0.96V in double gate and increased to 1.2V in single gate structure. The sub threshold swing, S = 81.9 mV/dec and S = 87.7 mV/dec were obtained for double and single gate devices respectively. Similarly, large I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Dsat</inf> = 370µA/µm was observed for double gate compared to single gate device. By scaling the L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> into 50nm, the V <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T</inf> remains almost the same when the L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> is larger than 80nm. However, it decreases rapidly when scaled down to 50nm. The leakage current increases rapidly when the L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> is scaled down to 100nm and beyond. However, the ratio of I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ON</inf> – I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">OFF</inf> is seen to be increases even with shorter L <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">g</inf> . These results indicates that ORI method is essential for overcoming various SCE as scaling the channel length down to nanometer regime.