Patent ID: 6359303
Filing Date: 2002-03-19
Classification: H01L,Y10S

Abstract:
A structure of a channel region of a first conductivity type between source and drain diffusion regions of a second conductivity type, parts of said drain region and of said channel region underlying a floating gate electrode, said channel region comprising:a first channel sub-region being directly adjacent to said drain region, said first channel sub-region being under said floating gate electrode, and said first channel sub-region having a first impurity concentration range; a second channel sub-region being directly adjacent to said first channel sub-region, so that said first channel sub-region is disposed between said drain region and said second channel sub-region, said second channel sub-region being under said floating gate electrode, and said second channel sub-region having a second impurity concentration range which is lower than said first impurity concentration range; and a third channel sub-region being directly adjacent to said second channel sub-region, so that said second channel sub-region is between said first and third channel sub-regions, said third channel sub-region being closer to said source region than said second channel sub-region, a boundary between said second and third channel sub-regions being substantially aligned to an edge of said floating gate electrode, and said third channel sub-region having a third impurity concentration range which is lower than said second impurity concentration range.