mask for etching it is so hard to etch out the polysilicon inner word gate that poly residuals 23 remains along the word gate corner as shown in fig5 b it may cause word word short or word cg short the negative slope comes from defining the word gate as remained pattern it is defined by trench pattern with positive slope opening in this embodiment followed by filling polysilicon and patterning the word line the word gate 142 may also be stepped down into the underlying channel punch through current due to short channel has recently been garnering serious attention the channel length of twin monos is figured out by 2 u00d7 control gate width word gate width it has a benefit in short channel because of the 2 u00d7 control gate width however serious problems will occur even in twin monos in the 0 09 um and beyond era the short channel punchthrough can be controlled by stepping down the word gate into the channel by a few nm the array architecture of the second embodiment is for diffusion bit array organization u s pat no 6 255 166b1 the control gate 140 and bit line 141 run along the 2 nd direction crossing the word line 143 along the 1 st direction in fig7 the diffusion contact 161 is.