Samsung Electronics Co., Ltd.

Woon-kyung Lee

He-jueng Lee

Joon-Sung Lee

Eui-do Kim

A mask read only memory (ROM) and a method of fabricating the same is provided. This mask ROM and related method is capable of reducing the pitch of buried impurity diffusion regions. In the mask ROM fabrication process, a gate insulation layer is formed over a semiconductor substrate, and parallel conductive layer patterns are formed on the gate insulation layer. These conductive layer patterns are separated from each other by a first predetermined interval and extend in the same direction. Ion implantation is then carried out using the conductive layer patterns as a mask to form buried impurity diffusion regions near the semiconductor substrate between the conductive layer patterns. A conductive layer for use in forming word lines is then formed over the entire surface of the resultant structure, and both the conductive layer and the conductive layer patterns are etched so as to form word lines and pad conductive layers. The word lines are formed to be parallel to each other, are separated from each other by a second predetermined interval, and extend in a direction perpendicular to the buried impurity diffusion regions. The pad conductive layers, which form ohmic contacts with the word lines, are formed in an island shape channel regions. These channel regions are defined as the areas between the buried impurity diffusion regions that are overlapped by the word lines.

Mask ROM fabrication method

The present invention provides a nonvolatile memory device having high reliability with novel sidewall spacer structures. The gate stack structure for use in a nonvolatile memory device comprises a semiconductor substrate, a gate stack formed on the semiconductor substrate. The gate stack has a sidewall and a top surface. A multi-layer sidewall spacer structure is formed on the sidewall of the gate stack. The multi-layer sidewall spacer structure includes a first oxide layer, a first nitride layer, a second oxide layer, and a second nitride layer that are sequentially stacked. With the present invention, even if the second nitride layer is perforated or damaged during the formation of contact holes, sidewalls of the gate stack of nonvolatile memory cell can be protected with the first nitride layer from mobile ions. Also, etching damage to source/drain regions or field regions can be reduced.

Nonvolatile semiconductor memory device with a multi-layer sidewall spacer structure and method for manufacturing the same

A method for fabricating a mask ROM capable of effectively reducing the distance of buried impurity diffusion regions. The method includes stacking a pad oxide layer and a first anti-oxidation layer in sequence in a cell array region and a peripheral circuit region of a semiconductor substrate. The anti-oxidation layer is partially etched to form a first pattern defining an isolation region of the peripheral circuit region and a second pattern defining a buried impurity diffusion region of the cell array region, and a second anti-oxidation layer is stacked, and then the second anti-oxidation layer stacked in the peripheral circuit region is removed, so that the second anti-oxidation layer stacked in the cell array region remains. Then, a field oxide layer is formed in the isolation region of the peripheral circuit region, exposed by the remaining second anti-oxidation layer; and impurities are implanted to form the buried impurity diffusion region.

There are provided a semiconductor device and a fabricating method thereof, in which a plurality of buried diffusion layers repeatedly extend on a semiconductor substrate and a plurality of word lines repeatedly extend on the buried diffusion layers, perpendicularly to the buried diffusion layers. The cross-sections of the word lines are shaped in asymmetrical polygons, with odd-numbered word lines having the same cross-section and the even-numbered word lines having the same cross-section. Narrow gate electrodes can be formed on the buried diffusion layers, using a spacer mask, so that the area of a memory cell array can be reduced by 50% and thus a cell integration level can be increased.

Growing community of inventors

Kyungki-do, South Korea

Woon-kyung Lee