Method of forming split-gate cell for non-volative memory devices
View Patent ↗Fabrication of a slim split gate cell and the resulting device are disclosed. Embodiments include forming a first gate on a substrate, the first gate having an upper surface and a hard-mask covering the upper surface, forming an interpoly isolation layer on side surfaces of the first gate and the hard-mask, forming a second gate on one side of the first gate, with an uppermost point of the second gate below the upper surface of the first gate, removing the hard-mask, forming spacers on exposed vertical surfaces, and forming a salicide on exposed surfaces of the first and second gates.
1. A method comprising:
forming a first gate on a substrate, the first gate having an upper surface and a nitride hard-mask covering, and directly contacting, the upper surface;
forming an interpoly oxide layer or charge storage layer on side surfaces of the first gate and the nitride hard-mask;
depositing a blanket polysilicon layer;
etching the blanket polysilicon layer to form a polysilicon spacer with an uppermost point of the polysilicon spacer below the upper surface of the first gate on each side of the first gate;
removing the polysilicon spacer from a first side of the first gate, the remaining polysilicon spacer forming a second gate on a second side of the first gate opposite to the first side;
removing the nitride hard-mask;
forming spacers on all exposed vertical surfaces; and
forming a salicide on exposed surfaces of the first and second gates,
wherein the first gate is one of a select gate and a control gate, and the second gate is the other of a select gate and a control gate,
wherein an uppermost point of the interpoly oxide layer or charge storage layer on the first side is lower than an uppermost point of the second side and an uppermost point of the first gate is lower than the uppermost point of the interpoly oxide layer or charge storage layer on the first side.
2. The method according to claim 1 , comprising forming the hard-mask of a nitride.
3. The method according to claim 1 , comprising forming the interpoly oxide layer or charge storage layer of an oxide.
4. The method according to claim 1 , comprising forming the interpoly oxide layer or charge storage layer on the substrate concurrently with forming the interpoly oxide layer or charge storage layer on side surfaces of the first gate.
5. The method according to claim 1 , further comprising forming the interpoly oxide layer or charge storage layer between the first and second gates.