Method of forming transistor using step STI profile in memory device

A method of forming a memory device, comprising:

• forming first and second isolation structures on a semiconductor substrate, the first and second isolation structures defining an active region therebetween;
• forming first and second spacers provided adjacent to the first and second isolation structures, respectively, the first and second spacers exposing a portion of the substrate;
• and
• etching the exposed portion of the substrate to define a step profile, so that the active region includes first and second vertical portions and an upper primary surface, the first and second vertical portions extending above the upper primary surface, the first vertical portion being provided directly below the first spacer, the second vertical portion being provided directly below the second spacer.