Semiconductor device with a wide-gap semiconductor layer on inner wall of trench

摘要

A conventional DRAM needs to be refreshed at an interval of several tens of milliseconds to hold data, which results in large power consumption. In addition, a transistor therein is frequently turned on and off; thus, deterioration of the transistor is also a problem. These problems become significant as the memory capacity increases and transistor miniaturization advances. A transistor is provided which includes a wide-gap semiconductor and has a trench structure including a trench for a gate electrode and a trench for element isolation. Even when the distance between a source electrode and a drain electrode is decreased, the occurrence of a short-channel effect can be suppressed by setting the depth of the trench for the gate electrode as appropriate.

主权项

1. A semiconductor device comprising:
a first insulating layer; a trench in the first insulating layer; a semiconductor layer in the trench; a source electrode and a drain electrode in contact with the semiconductor layer; a gate insulating layer adjacent to the semiconductor layer; and a gate electrode in the trench and adjacent to the semiconductor layer with the gate insulating layer interposed therebetween, wherein the gate insulating layer is in contact with the semiconductor layer in the trench, wherein the semiconductor layer has a cross-sectional shape of a rounded shape and is in contact with a whole surface of the trench, wherein the semiconductor layer comprises an oxide semiconductor having a band gap larger than 1.1 eV, and wherein the gate insulating layer is in contact with a whole surface of the semiconductor layer in the trench.