Nonvolatile semiconductor memory device

Abstract

Disclosed herein is a nonvolatile semiconductor memory device containing a semiconductor layer, a block insulating layer, an organic molecular layer which is formed between the semiconductor layer and the block insulating layer, and a control gate electrode formed on the block insulating layer. The organic molecular layer contains first organic molecules and second organic molecules, such that the first organic molecule has a first alkyl chain or a first alkyl halide chain on the semiconductor layer side and a charge trapping unit on the block insulating layer side, and the second organic molecule has a second alkyl chain or a second alkyl halide chain on the semiconductor layer side and a hydroxy group, an ether group, a carboxyl group or an ester group on the block insulating layer side.

What is claimed is: 
     
         1 . A nonvolatile semiconductor memory device, comprising:
 a semiconductor layer;   a block insulating layer;   an organic molecular layer formed between the semiconductor layer and the block insulating layer, the organic molecular layer having first organic molecules and second organic molecules, the first organic molecule having a first alkyl chain or a first alkyl halide chain on the semiconductor layer side and a charge trapping unit on the block insulating layer side, and the second organic molecule having a second alkyl chain or a second alkyl halide chain on the semiconductor layer side and a hydroxy group, an ether group, a carboxyl group or an ester group on the block insulating layer side; and   a control gate electrode formed on the block insulating layer.   
     
     
         2 . The device according to  claim 1 , further comprising
 a tunnel insulating layer formed between the semiconductor layer and the organic molecular layer,   wherein the first alkyl chain or the first alkyl halide chain are bonded to the tunnel insulating layer and the second alkyl chain or the second alkyl halide chain are bonded to the tunnel insulating layer.   
     
     
         3 . The device according to  claim 1 , wherein
 the first alkyl chain or the first alkyl halide chain are bonded to the semiconductor layer and the second alkyl chain or the second alkyl halide chain are bonded to the semiconductor layer, and   the carbon number of the first alkyl chain or the first alkyl halide chain is not smaller than 6 and not larger than 30.   
     
     
         4 . The device according to  claim 1 , further comprising:
 a tunnel insulating layer formed on the semiconductor layer side between the semiconductor layer and the organic molecular layer; and   a conductive layer formed on the organic molecular layer side between the semiconductor layer and the organic molecular layer,   wherein the first alkyl chain or the first alkyl halide chain are bonded to the conductive layer and the second alkyl chain or the second alkyl halide chain are bonded to the conductive layer.   
     
     
         5 . The device according to  claim 1 , wherein the concentration of the second organic molecules is not larger than 10% of the concentration of the first organic molecules. 
     
     
         6 . The device according to  claim 1 , wherein the carbon number of the second alkyl chain or the second alkyl halide chain is not smaller than 3 and not larger than 30. 
     
     
         7 . The device according to  claim 1 , wherein the charge trapping unit is a porphyrin derivative, a phthalocyanine derivative, a chlorine derivative, a tetrapyrrole derivative, a bipyridine derivative, an indole derivative, an acene derivative, a quinoxaline derivative, a phenylenevinylene derivative, or a fullerene derivative. 
     
     
         8 . The device according to  claim 1 , wherein a relatively negative voltage with respect to the semiconductor layer is applied to the control gate electrode at the time of a writing operation. 
     
     
         9 . The device according to  claim 1 , wherein a relatively positive voltage with respect to the semiconductor layer is applied to the control gate electrode at the time of a writing operation. 
     
     
         10 . The device according to  claim 1 , wherein the block insulating layer is a metal oxide film formed by ALD (Atomic Layer Deposition). 
     
     
         11 . A nonvolatile semiconductor memory device, comprising:
 a semiconductor layer;   a control gate electrode; and   an organic molecular layer formed between the semiconductor layer and the control gate electrode, the organic molecular layer having first organic molecules and second organic molecules, the first organic molecule having a first alkyl chain or a first alkyl halide chain on the semiconductor layer side and a charge trapping unit on the control gate electrode side, and the second organic molecule having a second alkyl chain or a second alkyl halide chain on the semiconductor layer side and a hydroxy group, an ether group, a carboxyl group or an ester group on the control gate electrode.   
     
     
         12 . The device according to  claim 11 , wherein the second alkyl chain or the second alkyl halide chain is provided with a side chain diverging from a main chain to the control gate electrode side. 
     
     
         13 . The device according to  claim 11 , wherein the concentration of the second organic molecules is not larger than 10% of the concentration of the first organic molecules. 
     
     
         14 . The device according to  claim 11 , wherein the carbon number of the second alkyl chain or the second alkyl halide chain is not smaller than 3 and not larger than 30. 
     
     
         15 . The device according to  claim 11 , wherein the charge trapping unit is a porphyrin derivative, a phthalocyanine derivative, a chlorine derivative, a tetrapyrrole derivative, a bipyridine derivative, an indole derivative, an acene derivative, a quinoxaline derivative, a phenylenevinylene derivative, or a fullerene derivative.