Method for enhancing reliability of SONOS (Silicon Oxide Nitride Oxide Semiconductor) flash memory device by means of selective epitaxy

Abstract

The invention discloses a method for enhancing the reliability of an SONOS (Silicon Oxide Nitride Oxide Semiconductor) flash memory device by means of selective epitaxy, which comprises the following steps: step 1, growing an epitaxial doping layer on a silicon substrate by adopting a selective epitaxial process; step 2, growing a tunneling oxidation layer on the epitaxial doping layer; step 3, growing a silicon oxynitride trap layer on the tunneling oxidation layer, and simultaneously carrying out in-situ doping on the silicon oxynitride trap layer by using N2O to form a silicon oxynitride mixture to serve as a medium for storing charges; and step 4, growing a high-temperature thermal-oxidation layer on the silicon oxynitride trap layer. In the method disclosed by the invention, an erasing voltage is regulated by means of selective epitaxial doping growth instead of ion implantation so as to avoid the damage to a silicon surface, thus the reliability of the SONOS flash memory device is improved and the service life of the SONOS flash memory device is prolonged.

Description

technical field [0001] The invention belongs to the field of semiconductor integrated circuit manufacturing, and relates to a manufacturing process method of a SONOS flash memory device, in particular to a method for improving the reliability of the SONOS flash memory device by using selective epitaxy. Background technique [0002] SONOS flash memory device (a flash memory device using silicon nitride as a charge storage medium) has become one of the main flash memory types at present because of its good scaling characteristics and radiation resistance characteristics. SONOS flash memory devices are also facing many problems in application. Among them, there are two main issues related to reliability: one is Endurance (endurance) characteristics, which is to measure the degradation of SONOS device characteristics after multiple programming / erasing. The second is the Data Retention (data retention) feature, which is the data storage capability of SONOS devices. Since the ad...

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Problems solved by technology

However, ion implantation will cause damage to the silicon surface, which will cause more defects at the interface between the tunnel oxide layer of SONOS and silicon, and ultimately directly reduce the reliability life of the device.

At the same time, the subsequent tunneling oxide layer formation process may bring about the redistribution of ion implantation doping, increasing the instability of device performance

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