A simple process of thin-film transistor using the trench-oxide layer for improving 1T-DRAM performance

In this paper, we propose a simple trench-oxide thin-film transistor (TO TFT) process for 1T-DRAM applications. Our proposed TO TFT structure has several novel features as follows: 1. The buried oxide and the isolation oxide are carried out simultaneously in order to achieve a goal of simple process. 2. The trench design is used to improve both the sensing current windows (∼ 72%) and the retention time (∼ 50%). 3. The thermal stability is drastically improved by its naturally formed source/drain tie. The above mentioned features help our proposed device structure to demonstrate the desired characteristics that are better than that of a conventional TFT. Additionally, the thermal instability is drastically improved which is good for long-term device operation.