Method of forming a trench capacitor on a semiconductor substrate

A method of forming a capacitor on a semiconductor substrate, comprising the steps of:

• forming a mask layer having an opening on a major surface of said substrate,
• forming a trench having a bottom wall and a side wall in said substrate by anisotropic etching through said opening,
• filling said trench with a photoresist,
• exposing the photoresist in the trench to a standing wave of light intensity which is created by interference between incident light directed to the bottom of the trench and reflected light from the bottom of the trench,
• developing the photoresist exposed to said standing wave of light intensity to leave periodic regions of photoresist along the side wall of the trench in the direction of its depth,
• etching the side wall of the trench using the residual periodic photoresist as a mask to create periodic hollows along the side wall of the trench,
• removing the residual periodic photoresist and forming an insulation layer on the side wall and bottom wall of the trench, and
• forming a conductive layer on the insulation layer formed on the side wall and bottom wall of the trench.