| 摘要 |
<p>A vertical channel flash memory cell with a silicon germanium layer (24) in the channel region provides enhanced secondary electron injection when programming the device. The device includes a silicon substrate (10), a silicon germanium alloy layer (24) epitaxially grown on the substrate, and a silicon layer (260) epitaxially grown on the silicon germanium layer. A sidewall through the stacked structure is formed by etching thereby exposing edges of the silicon layer and the silicon germanium layer and a portion of the substrate. A floating gate (18) is formed overlying the sidewall and insulated therefrom with a control gate (20) overlying the floating gate and insulated therefrom. A source region (14) is formed in the silicon layer and a drain region (12) is formed in the substrate with a channel therebetween along the sidewall and including the silicon germanium layer. The silicon germanium layer (24) is preferably compressively strained and can have a uniform mole fraction or a graded mole fraction. The vertical structure permits the fabrication of flash memory cells with smaller dimensions and lower operating voltages.</p> |
