Nonvolatile semiconductor device and method of manufacturing nonvolatile semiconductor device

Abstract

A semiconductor substrate having a main surface, first and second floating gates formed spaced apart from each other on the main surface of the semiconductor substrate, first and second control gates respectively located on the first and second floating gates, a first insulation film formed on the first control gate, a second insulation film formed on the second control gate to contact the first insulation film, and a gap portion formed at least between the first floating gate and the second floating gate by achieving contact between the first insulation film and the second insulation film are included. With this, a function of a nonvolatile semiconductor device can be ensured and a variation in a threshold voltage of a floating gate can be suppressed.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a nonvolatile semiconductor device having reduced capacitive coupling between floating gates and a method of manufacturing the same.[0003]2. Description of the Background Art[0004]A generally known nonvolatile semiconductor device allowing electrical writing and erasing includes a plurality of floating gate electrodes formed on a main surface of a semiconductor substrate and control gate electrodes formed on the floating gate electrodes. As a degree of integration of a semiconductor integrated circuit becomes higher in recent years, a dimension between floating gates becomes smaller and a large capacity is readily generated between adjacent floating gates. As a result, a problem due to so-called capacitive coupling occurs, that is, a threshold voltage during reading of the floating gate varies according to potentials of surrounding floating gates.[0005]Therefore, a nonvolatile semiconduc...

AI Technical Summary

Benefits of technology

The present invention provides a nonvolatile semiconductor device with suppressed variation in threshold voltage of a floating gate and ensured function of the device. The device includes a semiconductor substrate, first and second floating gates, first and second control gates, first and second insulation films, and a gap portion. The invention solves the problem of insulation film entering space between the floating gates and control gates, and prevents hydrogen or water from inhibiting the function of the device.

Problems solved by technology

With this, suppression of capacitive coupling between adjacent floating gates becomes difficult and a threshold voltage of a selected floating gate varies.

Furthermore, in a nonvolatile semiconductor device having low-permittivity films having a permittivity lower than that of a silicon oxide film which are formed between floating gates and between control gates, hydrogen or water may exude to a gate insulation film, which inhibits a function of the nonvolatile semiconductor device.

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