Semiconductor integrated circuit device and a method of manufacturing the same
Manufacturing technique for an IC device which includes forming the first conductor film over a memory cell forming region and over a peripheral circuit forming region of a semiconductor substrate, patterning the first conductive film lying over the memory cell forming region to form a first conductive pattern which serves as a first or control gate electrode of a memory cell and leaving the first conductive film over the peripheral circuit forming region, forming a second conductive film over both the memory cell forming region and the first conductive film in the peripheral circuit forming region, etching the second conductive film to form a second or memory gate electrode of the memory cell on at least a side wall of the first conductive pattern, and followed by the formation of a gate electrode of a peripheral circuit transistor by etching the first conductive film in the peripheral circuit forming region.
1. A method of manufacturing a semiconductor integrated circuit device, comprising steps of:
(a) forming a first conductive film over a memory cell forming region and over a peripheral circuit forming region of a semiconductor substrate;
(b) patterning the first conductive film lying over the memory cell forming region to form a first conductive pattern which serves as a first gate electrode of a memory cell and leaving the first conductive film over the peripheral circuit forming region;
(c) after the step (b), forming a second conductive film over the memory cell forming region and over the first conductive film in the peripheral circuit forming region;
(d) after the step (c), forming a second gate electrode of the memory cell on at least one side wall of the first conductive pattern by etching the second conductive film; and
(e) after the step (d), forming a gate electrode of a peripheral circuit transistor by etching the first conductive film in the peripheral circuit forming region.
2. A method according to claim 1 , further comprising the step of:
(f) before the step (c), forming a charge storage layer over at least a region of the substrate where the first conductive film is removed in the step (b),
wherein the first gate electrode constitutes a control gate electrode of the memory cell, and
wherein the second gate electrode constitutes a memory gate electrode of the memory cell.
3. A method according to claim 2 , wherein, in the step (d), the second gate electrode is formed on the one side wall of the first conductive pattern, through an insulating film, in sidewall spacer shape.
4. A method according to claim 2 , wherein, in the step (d), an electrode withdrawal portion of the second gate electrode is formed by using a mask covering the electrode withdrawal portion in etching the second conductive film.
5. A method according to claim 2 , wherein, in the steps (d) and (e), the second conductive film and the first conductive film are etched in the peripheral circuit forming region to form the gate electrode of the peripheral circuit transistor.
6. A method according to claim 1 , further comprising the step of:
(g) before the step (c), introducing an impurity in a region of the substrate where the first conductive film is removed in the step (b).
7. A method according to claim 6 , wherein, in the step (d), the second gate electrode is formed on the one side wall of the first conductive pattern, through an insulating film, in sidewall spacer shape.
8. A method according to claim 6 , wherein, in the step (d), an electrode withdrawal portion of the second gate electrode is formed by using a mask covering the electrode withdrawal portion in etching the second conductive film.
9. A method according to claim 6 , wherein, in the steps (d) and (e), the second conductive film and the first conductive film are etched in the peripheral circuit forming region to form the gate electrode of the peripheral circuit transistor.
10. A method according to claim 1 , wherein, in the step (d), the second gate electrode is formed on the one side wall of the first conductive pattern, through an insulating film, in sidewall spacer shape.
11. A method according to claim 1 , wherein, in the step (d), an electrode withdrawal portion of the second gate electrode is formed by using a mask covering the electrode withdrawal portion in etching the second conductive film.
12. A method according to claim 1 , wherein, in the steps (d) and (e), the second conductive film and the first conductive film are etched in the peripheral circuit forming region to form the gate electrode of the peripheral circuit transistor.