Mosel Vitelic Corporation

Ting-S Wang

Chun-Lin Chen

Juinn-Sheng Chen

Der-Tsyr Fan

Chon-Shin Jou

The present invention discloses a method for fabricating a non-volatile memory structure from a single layer of polysilicon in a semiconductor substrate, wherein the semiconductor substrate with two active areas, first and second, are divided by isolation regions. In accordance with this method, a doped buried layer is formed in the first active area. Then, a first floating gate is formed on the buried layer and a second floating gate is formed on the second active area from the single layer of polysilicon. Next, two doped regions are formed at opposite sides of the second floating gate in the second active areas. Finally, a floating gate connection line is employed to connect the first and second floating gate for making sure that the two floating gates are in the same potential.

Single poly non-volatile memory structure and its fabricating method

The present invention discloses a single poly non-volatile memory structure including a semiconductor substrate with two active areas divided by isolation regions. A control gate doped with N-type impurities is embedded in the first active area, and a first floating gate is formed thereon. A second floating gate is formed on the substrate of the second active area, and two doped regions are implanted at opposite sides of the second active areas in the substrate. A floating gate line is employed to connect the first and second floating gate for making sure that the two floating gates are in the same potential. When the control gate is biased to a voltage level, the voltage level would be coupled to the first floating gate so as to keep the second floating gate in the same potential with the first floating gate. While one of the doped regions is biased to a voltage level, electrons would eject from the other doped region and trapped in the floating gates, thereby preserving information in this memory structure.

A method of damage-free doping for forming a dynamic random access memory cell is disclosed herein. A phosphoric silicate glass is deposited as a diffusion source. The phosphorous ions of phosphoric silicate glass can be diffused into a substrate to form the source/drain regions by a high temperature during a thermal annealing process. Next, a thermal oxide layer is formed on the gate electrode and the surface of the substrate by the thermal oxidation process. The thermal oxide layer can prevent ions from diffusing into the substrate during the subsequent thermal treatment process. Therefore, the present invention can reduce the damage of a dynamic random access memory.

Growing community of inventors

Hsinchu Hsien, Taiwan

Ting-S Wang