Method for fabricating silicon nitride ROM

Abstract

The invention discloses a process for making silicon nitride read-only memory, wherein a silicon oxide / silicon nitride / silicon oxide stack layer is first formed on a substrate, then a protective layer is formed on the stack layer, later an etching process is proceeded to pattern the protective layer and the stack layer, and expose part of the substrate. Then use a cleaning process to remove the protective layer, and apply an ion implanting process to form a doping area on the exposed substrate, later forming insulator on the doping area, and a character thread is formed on the substrate.

Description

technical field [0001] The present invention relates to a method of manufacturing a read only memory (ROM for short), and in particular to a method of manufacturing a silicon nitride read only memory (nitride ROM). Background technique [0002] The method of silicon nitride read-only memory is to form a trapping layer on the substrate first, and the trapping layer is a stacked layer of silicon oxide / silicon nitride / silicon oxide (oxide-nitride-oxide, ONO for short). ) composed of a stacked structure, a read-only memory that uses this material as a capture layer is called a silicon nitride read-only memory. Then, etching defines the silicon oxide / silicon nitride / silicon oxide stack layer, and then performs an ion implantation process on the substrate to form doped regions in the substrate. Then, an oxide layer is formed on the doped region, and polysilicon word lines are formed on the silicon oxide / silicon nitride / silicon oxide stack layer. [0003] It is known that when et...

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Problems solved by technology

However, if the top oxide layer is thickened, it may violate the trend of component miniaturization.

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