Sharp Kabushiki Kaisha Corporation

Kenji Hakozaki

Shinichi Sato

Takuji Tanigami

Kenichi Tanaka

Naoyuki Shinmura

Takayuki Taniguchi

Masanori Yoshimi

Shin-ichi Sato

A non-volatile semiconductor memory device comprising: a first conductive type well formed within a semiconductor substrate; and a memory cell having a gate insulating film, a floating gate, an insulating film, a control gate and a pair of source/drain region, the gate insulating film, the floating gate, the insulating film, the control gate being layered in this order above the first conductive type well, the pair of source/drain regions being made up of second conductive type diffusion layers and formed within the first conductive type well, wherein the source region is electrically connected to the first conductive type well.

Non-volatile semiconductor memory device and manufacturing method of the same

The present invention provides a process for fabricating semiconductor device comprising the steps of: forming an etching-stop layer on a semiconductor substrate; patterning the etching-stop layer so that the etching-stop layer remains in a region to be an active region and is removed from a region to be a device isolation region, followed by forming a trench in the region to be the device isolation region; depositing on the semiconductor substrate an insulating film having a thickness greater than or equal to the depth of the trench; forming a resist pattern having an opening above the etching-stop layer above the active region adjacent to a device isolation region whose width is greater than or equal to a predetermined value, followed by etching the insulating film using the resist pattern as a mask; and polishing the insulating film existing on the resulting semiconductor substrate for flattening after removing the resist pattern.

Process for fabricating a semiconductor device

A method including: a first writing step for writing data by injecting electrons into the floating gate; a first verifying step for verifying whether the threshold voltage is higher than the first reference level after performing the first writing operation; a step of repeating the first writing step and the first verifying step until the threshold voltage becomes higher than the first reference level, if the threshold voltage is lower than the first reference level; a second verifying step for verifying whether the threshold voltage is higher than a second reference level which is set to be higher than the first reference level, if the threshold voltage is higher than the first reference level; a step of ending the writing operation if the threshold voltage is lower than the second reference level; and a second writing step for writing data by discharging electrons from the floating gate until the threshold voltage becomes higher than the first reference level and lower than the second reference level, if the threshold voltage is higher than the second reference level.

Method for writing data into non-volatile semiconductor memory cell

There is provided a method for writing a multiple value into a nonvolatile memory capable of writing multiple value data into a floating gate type memory cell in an equal time even when the data are varied. With a specified voltage applied to a control gate of a memory cell, a drain voltage which is varied according to each of data values '11', '10' and '01' to a drain so that a write time required for setting a varied threshold voltage is equalized. By moving electrons between a floating gate and a drain through a gate insulating film, the threshold voltage of the memory cell is set.

Method for writing multiple value into nonvolatile memory in an equal

According to the present invention, a method for producing a nonvolatile semiconductor memory device is provided. The method includes the steps of: forming stripe-shaped silicon portions including a plurality of first portions to be used as a plurality of floating gates and a plurality of second portions interposed between two adjacent portions of the plurality of first portions by patterning a silicon film; forming a conductive film so as to cover an insulating film; forming a control gate so as to cover the plurality of first portions of the stripe-shaped silicon portions by patterning the conductive film; converting the plurality of second portions of the stripe-shaped silicon portions into a silicon oxide film, and forming the plurality of floating gates from the plurality of first portions by thermally oxidizing the plurality of second portions; and implanting impurity ions through the silicon oxide film into the active region on the semiconductor substrate by using the control gate as a mask, thereby forming a source region and a drain region in the active region.

Growing community of inventors

Fukuyama, Japan

Kenji Hakozaki