Memory capable of storing information and the method of forming and operating the same

Abstract

A method for manufacturing a memory unit capable of storing multibits binary information. A gate is formed on a dielectric layer over a semiconductor substrate. Next, a first etching is performed to etch the semiconductor substrate by using the gate acting as an etching mask to remove exposed surface of the dielectric layer. Subsequently, a first oxide layer is conformally formed on the gate and the semiconductor substrate. An charge-trapping layer is conformally formed on the first oxide layer, and subsequently a second oxide layer is conformally formed on the isolating layer. Next, a second etching is performed to etch the second oxide layer and the charging-trapping layer to form sandwich spacers composed of the second oxide layer/the isolating layer/the first oxide layer on the substrate and the gate sidewall. An ion implantation is performed by using the gate and the spacers acting as a mask to form source/drain doped regions in the semiconductor substrate, wherein junctions of the substrate to the source/drain doped regions locate right under the spacers.