Study of HTO-based alternative gate oxides for high voltage transistors on advanced eNVM technology

Targeting the integration of embedded non-volatile memories on thin-silicon body technology, high temperature oxide (HTO) is evaluated on a 40nm automotive eFlash process as replacement of furnace grown thick gate oxide for high voltage transistors. Different thermal treatments are evaluated to enhance HTO quality, including growth of interfacial layer, reoxidation and high temperature annealings. Transistor performance and reliability are thoroughly studied, showing that the main challenge for HTO integration is time-dependent dielectric breakdown. Because of higher charge trapping, HTO is found to be less reliable than grown oxide. However, optimized dedicated treatments successfully improve HTO quality and reliability.