Semiconductor device and manufacturing method thereof

A semiconductor device, comprising:

• a stacked structure including:
• a first polysilicon layer disposed over a substrate;
• a first dielectric layer disposed over the first polysilicon layer;
• and
• a second polysilicon layer disposed over the first dielectric layer;
• a plurality of sidewall spacer layers disposed on opposing sides of the stacked structure,
• wherein the plurality of sidewall spacer layers include an inner sidewall spacer layer and an outermost sidewall spacer layer, the inner sidewall spacer layer and outermost sidewall spacer layer are formed on opposing sides of the first polysilicon layer and the second polysilicon layer, and
• wherein the inner sidewall spacer layer has a three layer structure including at least one silicon nitride layer and at least one silicon oxide layer;
• and
• a third polysilicon layer disposed over an oxide layer and on the opposing sides of the stacked structure,
• wherein the outermost sidewall spacer layer is inclined along a side of the stacked structure with respect to a normal line to a surface of the substrate, making an angle θ2 between the outermost spacer layer and the normal line, wherein 0°<θ2<15° measured from the normal line.

A method for manufacturing a semiconductor device including a non-volatile memory, comprising:

• forming a first polysilicon layer over a substrate;
• forming a first dielectric layer over the first polysilicon layer;
• forming a second polysilicon layer over the first dielectric layer;
• patterning the first polysilicon layer, the first dielectric layer, and the second polysilicon layer to form spaced-apart first and second stack structures;
• forming sidewall spacer layers on opposing sides of the first and second stacked structures,
• wherein the forming the sidewall spacer layers include:
• forming a first sidewall spacer layer on opposing sides of the second polysilicon layer and the first dielectric layer after the second polysilicon layer and the first dielectric layer are patterned and before the first polysilicon layer is patterned;
• and
• forming a second sidewall spacer layer over the first sidewall spacer layer and opposing sides of the first polysilicon layer and the second polysilicon layer after the first polysilicon layer is patterned;
• forming a third polysilicon layer over and between the first and second stacked structures;
• removing an upper portion of the third polysilicon layer so that the first and second stack structures protrude from the third polysilicon layer,
• wherein an upper surface of third polysilicon layer between the first and second stack structures and the sidewall spacer layers in contact with the third polysilicon layer form an angle θ1 at a contact point of the upper surface of the third polysilicon layer and the sidewall spacer layers, where 90°<θ1<115° measured from the upper surface of the third polysilicon layer.