本发明的各个方面提出了一种带有自对准源极接触的基于高密度沟槽的功率MOSFET，以及这类器件的制备方法。源极接触与垫片自对准，垫片沿闸极盖的侧壁形成。另外，有源器件具有二阶闸极氧化物。其中闸极氧化物底部的厚度大于顶部的厚度。二阶闸极氧化物与自对准的源极接触相结合，从而制备的器件间距可以在深亚微米级别。

Aspects of the present disclosure describe a high density trench-based power MOSFET with self-aligned source contacts and method for making such devices. The source contacts are self-aligned with spacers that are formed along the sidewall of the gate caps. Additionally, the active devices may have a two-step gate oxide. A lower portion may have a thickness that is larger than the thickness of an upper portion of the gate oxide. The two-step gate oxide combined with the self-aligned source contacts allow for the production of devices with a pitch in the deep sub-micro level. It is emphasized that this abstract is provided to comply with rules requiring an abstract that will allow a searcher or other reader to quickly ascertain the subject matter of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims.