Nonvolatile semiconductor memory device

US7875925B2 · kind B2 · utility

Assignee

• Kabushiki Kaisha Toshiba · JP

Inventor

• Tsunehiro Ino · Yokohama, JP

Key dates

• Filing date: Aug 18, 2008
• Grant date: Jan 25, 2011
• Expiry date: Aug 7, 2029

Classification

• Technology area (CPC H): Electricity
• CPC primary: H10D64/685

Abstract

A nonvolatile semiconductor memory device includes a source region and a drain region spaced from each other in a surface of a semiconductor layer, a tunnel insulating film provided on the semiconductor layer between the source region and the drain region, a charge storage film provided on the tunnel insulating film, a block insulating film provided on the charge storage film, and a control gate electrode provided on the block insulating film. The block insulating film is made of (Rm1−xLnx)2−yAlyO3+δ, where Ln is one or more selected from Pr, Tb, Ce, Yb, Eu, and Sm, Rm is one or more selected from La, Nd, Gd, Dy, Ho, Er, Tm, Lu, Y, and Sc, 0<x<0.167 (but 0<x<0.333 if Ln is Pr, and 0<x<0.292 if Ln is Tb), 0.95≦y≦1.20, and 0≦δ≦x(2−y)/2 (but −x(2−y)/2≦δ≦0 if Ln is Yb, Eu, and Sm, 0≦δ≦x(2−y)/3 if Ln is Pr, and 0≦δ≦3x(2−y)/14 if Ln is Tb).