Abstract:

A bulk MOSFET with poly-Si spacers has been fabricated by using the mix-and-match technique. The spacers have a different work function from the gate. In this work, p+ poly-Si is used for the main gate. The spacers are electrically connected to the source/drain. Due to n+ poly-Si spacers on both sides of the main gate, an inversion layer is easily induced below the poly-Si spacers, due to the low doping concentration, and it acts as extended source/drain regions. By performing boron halo doping, the short-channel effect was suppressed while keeping a relatively low channel-doping concentration, which leads to higher channel mobility and lower threshold-voltage fluctuation due to random dopant. From the I-V characteristics, we obtained Ion = 165 µA/µm at VGS-VTH = 0.7 V and VDS = 1.5 V. We also investigated the effect of n+ poly-Si spacer and p+ poly-Si gate on the device characteristics.